JP2017105151A - Printing device, control method and printing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal type printing device having a head element and the like which can gradually inspect the deterioration state of the head element without problem in printing processing and suppress the circuit scale.SOLUTION: A printing device includes: a thermal head which executes printing to a printing medium by a plurality of head elements; a voltage application circuit which applies the first voltage or second voltage to the head element; and a head control part which measures the divided voltage of the head element. The head control part switches the voltage applied to the head element to the second voltage by the voltage application circuit and measures the divided voltage of the head element when the state where printing cannot be executed is detected.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal printing apparatus and the like provided with a head element, and in particular, the deterioration state of the head element can be inspected step by step without impeding the printing process, and the circuit scale can be kept small. The present invention relates to a printing apparatus and the like.

  Thermal printers are widely used for printing receipts and the like.

  A thermal printer includes a plurality of head elements in a thermal head, and applies a voltage to these head elements to generate heat on the resistance elements (heating elements) of the head elements, thereby printing on a sheet. In such a printer, if the head element is defective, the print quality is undesirably lowered. Thus, conventionally, a method for inspecting a head element of a thermal printer has been proposed.

  Patent Document 1 below proposes a thermal head defect detection method, and discloses that head resistance is determined based on a maximum value and a minimum value using the resistance value of a heating element. Japanese Patent Application Laid-Open No. 2004-228561 discloses a method for detecting head element deterioration during printing as one of the techniques for realizing high-speed detection.

JP 2000-141730 A JP-A-10-166737

  However, the method described in Patent Document 1 is to detect whether the head element is good or defective, and it is impossible to grasp the progress of deterioration of the head element, and at an appropriate timing before the head element becomes defective. Since the head element cannot be replaced, there is a possibility that a problem may occur in the printing result.

  In addition, in the receipt printer of a cash register used in restaurants, convenience stores, etc. that are open 24 hours a day, it is necessary to stop the receipt output depending on the inspection method, which may hinder the sales. There is a problem of getting out.

  With respect to this problem, Patent Document 2 proposes a method in which all signal lines are provided with current detection resistors and the like and inspected during printing of a receipt. However, this method increases the circuit scale and increases the cost. There is a problem of becoming.

  Accordingly, an object of the present invention is a thermal printing apparatus including a head element, which can inspect the deterioration state of the head element step by step without causing any trouble in the printing process, and to suppress the circuit scale to be small. It is to provide a printing apparatus capable of performing the above.

  In order to achieve the above object, according to one aspect of the present invention, a printing apparatus applies a first voltage or a second voltage to a thermal head in which printing is performed on a print medium by a plurality of head elements. And a head control unit that measures a divided voltage of the head element. When the head control unit detects a state in which the printing cannot be performed, the voltage application circuit The voltage applied to the head element is switched to the second voltage, and the divided voltage of the head element is measured.

  As a result, since the head element is inspected using a time during which printing cannot be performed, the deterioration of the head element can be diagnosed without hindering the printing process. Furthermore, since it is not necessary to inspect the head element in parallel with the printing process, the circuit scale can be reduced.

  Furthermore, in the above invention, the preferable aspect further includes a data storage unit, the thermal head further includes a selection unit, and the head control unit detects a state where the printing cannot be performed. For each head element, the selection unit selects the head element, measures the divided voltage of the series circuit by the resistance element of the head element and the test resistor of the voltage application circuit, and the measured divided voltage and the A deterioration determination process is performed in which a deterioration state of the head element is determined based on an initial divided voltage value stored in the data storage unit.

  Thereby, since the deterioration state of the head element is determined based on the initial divided voltage value, the deterioration state of each head element can be determined accurately.

  Further, in the above invention, a preferable aspect is that the deterioration determination process is executed for a predetermined number of head elements obtained by dividing the total number of head elements, which can be completed while the printing cannot be executed. It is characterized by.

  As a result, deterioration determination processing is not performed for all head elements continuously, but deterioration determination processing is performed for the number of head elements that can be completed during a period in which printing cannot be performed such as during cutting processing. There is no problem with the printing process.

  Furthermore, in the above-described invention, a preferable aspect thereof is characterized in that the head control unit determines a deterioration state of the head element using a plurality of threshold values preset with respect to the divided voltage. .

  Thereby, since the determination of the degree of deterioration (deterioration state) is performed using a plurality of threshold values, fine management is possible.

  Furthermore, in the said invention, the preferable aspect has an auto cutter which cut | disconnects the said printing medium after the said printing, and the detection of the state which the said printing cannot be performed detects the start of the said cutting | disconnection by the said auto cutter. It is characterized by that.

  As a result, the deterioration determination process is executed during the print medium cutting process, so that a process that does not interfere with the print process is guaranteed. Furthermore, since the printing medium is printed and cut as long as the printing apparatus is used, the head element can be surely inspected.

  Furthermore, in the above-described invention, a preferable aspect is that the casing of the printing apparatus includes a cover that can open the storage portion of the print medium, and the detection of the state where the printing cannot be performed is performed by opening the cover. It is characterized by detecting.

  As a result, the head element is inspected when printing is stopped or when the cover is opened, so that printing can be performed without any trouble.

  Furthermore, in the above-described invention, a preferable aspect thereof is characterized in that the detection of the state where the printing cannot be performed is detection of the occurrence of an error in the printing apparatus.

  Thus, the head element is inspected when printing is stopped or when an error occurs, so that it can be executed without causing any trouble in printing.

  Furthermore, in the above-described invention, a preferable aspect thereof is characterized in that the second voltage and the voltage of the head control unit are the same.

  As a result, an error in the value obtained by A / D conversion from the measured divided voltage is reduced, so that it is possible to accurately determine the deterioration of the head element.

  In order to achieve the above object, another aspect of the present invention provides a thermal head that performs printing on a print medium using a plurality of head elements, and voltage application that applies a first voltage or a second voltage to the head elements. A printing apparatus control method comprising: a circuit; and a head control unit that measures a divided voltage of the head element, wherein the head control unit applies the voltage when detecting a state in which the printing cannot be performed. The voltage applied to the head element is switched to the second voltage by a circuit, and the divided voltage of the head element is measured.

  In order to achieve the above object, still another aspect of the present invention provides a thermal head that performs printing on a print medium using a plurality of head elements, and voltage application that applies a first voltage or a second voltage to the head elements. A printing system including a circuit, a head control unit that measures a divided voltage of the head element, and a communication unit, and a host device of the printing device, the head control unit of the printing device When the state in which the printing cannot be performed is detected, the voltage applied to the head element is switched to the second voltage by the voltage application circuit, the divided voltage of the head element is measured, and the divided voltage is measured. Using a preset threshold value for the voltage, the deterioration state of the head element is determined, and the measured divided voltage and / or the determination result based on the threshold value is determined by the communication unit. Transmitted to strike device, said host device acquires the information being sent is that.

  As a result, the deterioration information of the printing apparatus can be easily acquired by an external apparatus such as a host apparatus, and the deterioration management of the printer, particularly the intensive management in the remote apparatus can be easily performed.

  Further, in the above invention, a preferable aspect thereof is that the host device transmits a command to the printing device, and the printing device receives the command and transmits information to the host device by the head control unit. Is to do.

  Accordingly, the host device can operate the deterioration information of the head element from the remote device by a command, and the management of the deterioration information becomes diverse.

  Further objects and features of the present invention will become apparent from the embodiments of the invention described below.

1 is a configuration diagram according to a first exemplary embodiment of a printing apparatus to which the present invention is applied. FIG. 3 is a circuit diagram showing an example of a voltage application circuit 25 and a thermal head 26. FIG. It is the flowchart which illustrated the procedure of the initial setting process. It is a graph which shows the relationship between a divided voltage and a resistance value change rate. It is the figure which illustrated the temporary conversion table. It is a time chart which illustrated operation timing. 5 is a flowchart illustrating a processing procedure for one cycle of receipt printing. It is the flowchart which illustrated the procedure of the degradation judgment process. 4 is a diagram showing an example of deterioration information stored in a nonvolatile memory 24. FIG. It is a graph which shows the relationship between a divided voltage value (AD value) and resistance value (Rhead). It is the figure which showed an example of the conversion table CT. It is the flowchart which illustrated the procedure of the initial value acquisition process. It is the flowchart which illustrated the procedure of the state value acquisition process. It is the flowchart which illustrated the procedure of the degradation information acquisition process. It is the figure which showed an example of deterioration information. It is the flowchart which showed the procedure in the case of acquiring acquisition of a state value and acquisition of deterioration information continuously.

  Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention. In the drawings, the same or similar elements are denoted by the same reference numerals or reference symbols.

[First Embodiment]
FIG. 1 is a configuration diagram according to a first embodiment of a printing apparatus to which the present invention is applied. The printer 2 shown in FIG. 1 is a printing apparatus to which the present invention is applied. In the printer 2, the resistance values of the head elements (RH-1 to RH-n) provided in the thermal head 26 at the first startup or the like. (Each divided voltage) is measured and stored. After that, during the printing process, each resistance value (each divided voltage) of the head elements (RH-1 to RH-n) is measured at the timing of cutting the printing medium (rolled paper or the like) by the auto cutter 27. To do. The deterioration state of each head element (RH-1 to RH-n) is determined from the measured value and the resistance value change rate obtained by conversion from the stored initial resistance values (each divided voltage). To do. Moreover, it can be set as the structure which transmits the information regarding a measured value and / or a determination result to an external device (POS terminal device 1, degradation management server 3, etc.).

  Thereby, the deterioration state of each head element (RH-1 to RH-n) can be grasped step by step. In addition, since the deterioration detection process is performed when the print medium is cut, it is possible to detect the deterioration without hindering the printing process. Furthermore, the deterioration management of the printer 2 can be easily performed in the host device or the like.

  As shown in FIG. 1, in the present embodiment, the printer 2 is a printing apparatus that prints a receipt or the like in accordance with a print command from a POS (Point Of Sales) terminal device 1. The POS terminal device 1 and the printer 2 are each configured to be able to communicate with the deterioration management server 3 via a communication network 4 such as the Internet. The printer system 100 can be configured by the POS terminal device 1 and the printer 2, and the deterioration management system 200 is configured by the POS terminal device 1 and the printer 2 and the deterioration management server 3 or by the printer 2 and the deterioration management server 3. Can be configured.

  Although not shown, a plurality of printer systems 100, a POS server, and the like can be connected to the communication network 4.

  The POS terminal device 1 is a so-called cash register installed in a store or the like, and is a host device of the printer 2 that issues a print instruction such as a receipt to the printer 2. Although not shown, the POS terminal device 1 includes a CPU, a RAM, a ROM, a display device, an input device (such as a barcode reader), a communication device, and the like, and executes a checkout process at the time of product sales. Further, as will be described later, the POS terminal device 1 may perform deterioration management of the head elements (RH-1 to RH-n) of the printer 2.

  As shown in FIG. 1, the POS terminal device 1 includes a POS application unit 11, a printer driver unit 12, and a deterioration management unit 13 as functional configurations.

  The POS application unit 11 is a part responsible for checkout processing at the time of product sales, receipt / coupon print request, data transmission to a POS server (not shown), and the like. When printing is requested, print request data is output to the printer driver unit 12.

  The printer driver unit 12 is a part that performs a driver function for the receipt printer 2. The printer driver unit 12 receives the print request data output from the POS application unit 11, generates print data expressed by a command for the printer 2 according to the print request data, and transmits the print data to the printer 2.

  The deterioration management unit 13 is a part that performs deterioration management of the head elements (RH-1 to RH-n) of the printer 2. Specific functions will be described later.

  The POS application unit 11, the printer driver unit 12, and the deterioration management unit 13 are each configured by a program that instructs each processing content, a CPU that operates according to the program, a RAM, and the like.

  Next, the deterioration management server 3 is a server that manages information related to deterioration of a printer to be managed such as the printer 2. Although not shown, the deterioration management server 3 is composed of a server computer and includes a CPU, RAM, ROM, HDD, display device, input device, communication device, and the like. Specific functions of the deterioration management server 3 will be described later.

  Next, the printer 2 is a thermal printer including a line head that prints a receipt, a coupon, or the like according to an instruction from the POS terminal device 1 (according to print data). The printer 2 prints a print target on a print medium, and when printing is completed, the printer 2 cuts and discharges the paper with the auto cutter 27.

  The printer 2 is a so-called intelligent printer, and includes a data processing device (arithmetic device) similar to a personal computer in addition to a control device that performs printing control in a general printer.

  The printer 2 has a functional configuration as shown in FIG. The communication unit 21 is a communication device that communicates with an external device, and has a communication function with the POS terminal device 1, the degradation management server 3, and the like.

  The main control unit 22 is a main controller of the printer 2 that has a control function other than the control function of the head control unit 23 described later. The data processing device (arithmetic device) is the same as the personal computer described above. The main control unit 22 and the head control unit 23 may be separate or integrated.

  The head control unit 23 controls the thermal head 26 and the voltage application circuit 25 to execute printing on the print medium and determine the deterioration state of the head elements (RH-1 to RH-n) included in the thermal head 26. I do. The head control unit 23 includes a CPU, a RAM, a ROM, an ASIC, and the like, and executes processing by the CPU operating mainly according to a program stored in the ROM. Specific processing contents by the head controller 23 will be described later.

  The nonvolatile memory 24 (data storage unit) is a part that stores data related to the process of determining the deterioration state of the head elements (RH-1 to RH-n) described above by the head control unit 23. The nonvolatile memory 24 includes a provisional conversion table, a conversion table for each head element (RH-1 to RH-n), deterioration information (a head element identification number and a deterioration degree of the head element, etc.), etc. Store the data. Note that the nonvolatile memory 24 can be configured by NVRAM or the like.

  The voltage application circuit 25 is a circuit that applies a voltage to the thermal head 26. The voltage application circuit 25 includes two power supplies (24 V, 3.3 V) having different voltage values, and applies a printing voltage (24 V, (first voltage)) to the thermal head 26 when printing is performed. −1 to RH-n), the voltage is applied to the thermal head 26 by switching to the inspection voltage (3.3 V, (second voltage)).

  The thermal head 26 includes a plurality of head elements (RH-1 to RH-n) and their selection units. When printing is performed, a printing voltage is applied to the head elements (RH-1 to RH-n) selected by the selection unit, and the heating element (resistive element) of the head element generates heat, and printing is performed on the print medium. . In addition, during the inspection of the head elements (RH-1 to RH-n), the inspection voltage is applied to the head elements (RH-1 to RH-n) selected by the selection unit.

  The auto cutter 27 includes a blade and its drive unit, and when printing of a receipt is completed, the print medium is cut under the control of the main control unit 22.

  The paper transport unit 28 includes a transport roller, a driving unit thereof, and the like. Under the control of the main control unit 22, the printing medium is conveyed from the printing medium storage unit to the position of the head element, and when printing is completed, the printing medium is conveyed to the position of the auto cutter 27.

  The cover 29 is a lid that is provided in the casing of the printing apparatus and can open the storage portion for the print medium. When the operator opens the cover 29, for example, when replacing the print medium, the main control unit 22 detects the opening.

  FIG. 2 is a circuit diagram showing an example of the voltage application circuit 25 and the thermal head 26. As shown in FIG. 2, the thermal head 26 includes a shift register 263 including a plurality of head elements (RH-1 to RH-n) constituting the line head, a latch driver 262, and n stages of FFs (flip-flops). Yes. The selection unit described above includes a latch driver 262 and a shift register 263. Each head element (RH-1 to RH-n) includes a resistance element that is a heating element, as shown in FIG.

  The shift register 263 is sequentially connected so that DO (Data Out) of the first-stage shift register is connected to DI (Data In) of the second-stage shift register.

  The latch driver 262 includes a strobe signal input terminal STB and a latch signal input terminal LAT. Each n-stage shift register includes an input terminal DI to which serial data as print data is input, an input terminal CLK for a clock signal, and an output terminal DO from which serial data overflowing from the shift register 263 is output. .

  In accordance with a control signal from the head controller 23 connected to these circuits on the left side of FIG. 2, serial data for one line is input bit by bit from the input terminal DI of the first-stage shift register corresponding to the clock signal. Is done. Next, when the serial data for one line is stored in the shift register, the serial data for one line is stored in the latch driver 5 as parallel data by the latch signal.

  Next, the latch driver 262 that has received the strobe signal energizes the head element corresponding to “1” of the latched data while receiving the strobe signal. By this energization, an image for one line (one dot) is formed on the printing medium, and paper feeding for one dot is executed by a paper feeding mechanism (not shown). Printing is executed by repeating this procedure.

  The voltage application circuit 25 controls the ON / OFF of the print power supply 24 [V] and the inspection power supply 3.3 [V] of the head element by a switch signal (SW24VA or DOT_DETECT). The inspection power supply is preferably the same voltage as the power supply of the head control unit 23, and is 3.3V here as an example. Thereby, an error at the time of A / D conversion described later is reduced.

  At the time of executing the printing described above, the switching element QF5 composed of the FET is turned on by the SW24VA signal from the head control unit 23, and the printing voltage 24V is applied to the head elements (RH-1 to RH-n).

  On the other hand, at the time of inspection of the head elements (RH-1 to RH-n), the switching element QF5 is turned OFF, and the switching elements QF1 and QF2 formed by FETs are turned ON by the DOT_DETECT signal from the head control unit 23, respectively. An inspection voltage of 3.3 V is applied to the head elements (RH-1 to RH-n).

  Next, the head control unit 23 designates (selects) the head elements (RH-1 to RH-n) to be inspected by the DI signal, and the head elements (RH-1 to RH-n) are energized by the latch driver 262. Is done.

  As a result, a series circuit that connects the inspection resistor R1 and the resistance element (heating element) of the head element is formed, and the head control unit 23 uses the READ_HEAD signal to check the resistance R1 of the series circuit and the resistance element (heat generation) of the head element. Acquire (measure) the divided voltage between the body. Specifically, the A / D converted value (AD value) is acquired via the A / D converter ADC. Note that printing (coloring) may occur if the energization time becomes long due to the Joule heat applied to the head element within the inspection time per head element. Therefore, it is preferable to keep the inspection time within a certain time so that the temperature does not rise to the color developing temperature.

  The printer 2 having the above-described configuration is characterized by processing related to the deterioration determination of the head elements (RH-1 to RH-n), and the specific contents thereof will be described below.

  In the head elements (RH-1 to RH-n), it is known that the resistance value of the heating element (resistive element) changes as the deterioration progresses. There are several phenomena in the way of change, but in one phenomenon, the resistance value gradually increases. In other phenomena, the resistance value gradually decreases and then increases rapidly. In either case, if the resistance value increases more than a certain level, there is a risk of not generating sufficient heat during printing and causing printing failure.

  Therefore, in determining the deterioration of the head elements (RH-1 to RH-n), it is important to grasp the change in resistance value (of the heating element) of each head element (RH-1 to RH-n) step by step. is there.

  Therefore, in the printer 2, first, after performing processing (initial setting processing) for grasping the initial state (initial resistance value) of each head element (RH-1 to RH-n), an appropriate value is determined based on the initial state. The resistance value is measured at a frequency, and the deterioration determination process is executed.

  Further, the resistance value of each head element (RH-1 to RH-n) is obtained by measuring the above-mentioned divided voltage of the series circuit connecting the inspection resistor R1 and the resistance element (heating element) of the head element. Therefore, the initial state and the deteriorated state are grasped by measuring the divided voltage.

  FIG. 3 is a flowchart illustrating the procedure of the initial setting process. In this initial setting process, a conversion table is created for each head element (RH-1 to RH-n) so that the process can be performed quickly in the subsequent deterioration determination process. In this conversion table, each value (more specifically, AD value) of the divided voltage to be measured is associated with the rate of change in resistance value from the initial resistance value.

  FIG. 4 is a graph showing the relationship between the divided voltage and the resistance value change rate. The example shown in FIG. 4 shows the divided voltage (AD value) when the resistance value of the heating element of the head elements (RH-1 to RH-n) is 564Ω and the resistance value of the inspection resistor R1 is 255Ω. The relationship of the resistance value change rate is shown. The resistance value change rate represents the change (increase) from the initial resistance value (here, 564Ω) as a percentage. This relationship can be obtained by calculation based on mathematical expressions.

  FIG. 5 is a diagram illustrating a temporary conversion table. The provisional conversion table shown in FIG. 5 represents the graph shown in FIG. 4 in a table format. In the “divided voltage” in the temporary conversion table, X means the divided voltage corresponding to the initial resistance value 564Ω of the heating element of the head elements (RH-1 to RH-n) in the temporary conversion table. Yes. Specifically, X = 176. That is, when the resistance value of the heating element is 564Ω in the initial state, a value of “176” is acquired when the divided voltage is measured by the above-described procedure. This value is the initial divided voltage value.

  When the divided voltage is measured after the printer 2 is used to some extent and, for example, a value of “181” is obtained, the “divided voltage” is “X + 5” in the temporary conversion table. It can also be seen that the resistance value of the heating element “10_11%” of the “resistance value change rate” has increased.

  The initial resistance value 564Ω of the heating element of the head elements (RH-1 to RH-n) is a value (specification value) according to the specification of the device, and the actual resistance value is about 10% from this specification value. It may contain errors. Therefore, in order to accurately determine the degree of deterioration for each head element (RH-1 to RH-n), the initial resistance value is accurately grasped, and a conversion table (divided voltage and resistance value change rate) based on the initial resistance value is obtained. It is necessary to prepare a table showing the relationship of The initial resistance value 564Ω varies depending on the thermal head, and the above is an example.

  The provisional conversion table described above is created in advance and stored in the nonvolatile memory 24.

  Hereinafter, specific processing contents of the initial setting processing will be described with reference to FIG. When the printer 2 is activated for the first time, the initial setting process is executed. First, as described above, the head controller 23 outputs a signal to the voltage application circuit 25 and applies the inspection voltage (3.3 V) to the thermal head 26 (step S1 in FIG. 3).

  Next, the head control unit 23 selects one head element (RH-1 to RH-n) for initial setting (step S2 in FIG. 3). Specifically, as described above, the DI signal is output to the thermal head 26 and the head element is energized.

  As a result, a series circuit is formed that connects the inspection resistor R1 and the resistance element (heating element) of the head element. Therefore, the head control unit 23 uses the READ_HEAD signal to check the resistance R1 of the series circuit and the resistance of the head element. The divided voltage between the elements (heating elements) is measured, and the value is acquired (step S3 in FIG. 3). That is, information (initial divided voltage value) corresponding to the initial resistance value (of the resistance element (heating element)) of the head element is acquired.

  Next, the head control unit 23 reads the provisional conversion table stored in the nonvolatile memory 24, and substitutes the acquired divided voltage of the head element for “X” in the table. A head element conversion table is generated (step S4 in FIG. 3). That is, a conversion table showing the relationship between the divided voltage and the resistance value change rate based on the actual initial resistance value of the head element is generated.

  The head control unit 23 stores (saves) the generated conversion table in the nonvolatile memory 24 so as to be readable (step S5 in FIG. 3), and ends the initial setting process for the head element.

  The head controller 23 executes the above-described initial setting process (S2-S5) for all the head elements (RH-1 to RH-n) (Yes in step S6 in FIG. 3).

  Thereafter, the head controller 23 sets threshold values in the conversion tables generated for all the head elements (RH-1 to RH-n) and stored in the nonvolatile memory 24 (step S7 in FIG. 3). Here, a plurality of threshold values are set for each head element (RH-1 to RH-n) so that the deterioration state of each head element (RH-1 to RH-n) can be grasped in detail.

  The threshold value is set to the resistance value change rate associated with the divided voltage acquired as the AD value in the conversion table. For example, the resistance value change rates of 51%, 15%, −15%, and −30% are 4 One threshold is set in advance. For example, if the provisional conversion table shown in FIG. 5 is a conversion table of a certain head element in which the measured initial resistance value is substituted for X, the four threshold values N1, N2, N3 and N4 is set.

  As described above, the initial setting process ends.

  Next, after the initial setting process is performed, when the printer 2 is used and a predetermined timing is reached, the head control unit 23 executes a deterioration determination process. The predetermined timing at which the deterioration determination process is executed is one major characteristic of the printer 2, and specifically, is the timing at which the print medium is cut after the printing process is completed. During the print medium cutting process, the printing process is stopped and the printing process cannot be executed. When the printer 2 detects the state of the cutting process in which this printing cannot be performed, the head element deterioration determination process is executed.

  FIG. 6 is a time chart showing the timing of the deterioration determination process executed in the printer 2. In FIG. 6, the horizontal axis indicates the elapsed time t. The vertical axis indicates the execution (upper value) / non-execution (lower position) of the process, or ON (upper value) / OFF (lower position) of the voltage.

  (A) is a diagram showing a receipt issuing process. Each mountain (ΔT1, ΔT2, ΔT3 and ΔT4, ΔT5 and ΔT6,... ΔTn and ΔTn + 1) of the time chart corresponds to one receipt issuing process. In each mountain, the former (ΔT1, ΔT3, ΔT5,... ΔTn) corresponds to a printing process, and the latter (ΔT2, ΔT4, ΔT6,... ΔTn + 1) corresponds to a cutting process. For example, ΔT1 (t1 to t2) is a time for printing on a receipt when the head controller 23 issues a signal to the voltage application circuit 25 and a voltage is applied to the thermal head 26. Further, ΔT2 (from t2 to t3) is a time during which the auto cutter 27 is controlled by the main control unit 22 and the receipt is cut.

  (B) is a diagram showing the timing of applying a printing voltage (24V) to the thermal head 26 in order to print on the receipt. Each mountain in (B) corresponds to the printing process (ΔT1, ΔT3, ΔT5,... ΔTn) in (A). When printing on the receipt is completed at each printing processing time (ΔT1, ΔT3, ΔT5,... ΔTn) in (A), the voltage application circuit 25 performs printing applied to the thermal head 26 under the control of the head control unit 23. The voltage (24V) is cut off.

  (C) is a diagram showing timing for applying the inspection voltage (3.3 V) to the thermal head 26. FIG. Each mountain in (C) corresponds to the cutting process (ΔT2, ΔT4, ΔT6,... ΔTn + 1) in (A). Then, at the start of each cutting process (ΔT2, ΔT4, ΔT6,... ΔTn + 1) in (A), the voltage application circuit 25 applies a test voltage (3.3 V) to the thermal head 26 under the control of the head controller 23. Apply.

  (D) to (G) show the execution timing of the deterioration determination process. The execution timing of the deterioration determination process coincides with the application time of the cutting process (ΔT2, ΔT4, ΔT6,... ΔTn + 1) in (A) and the inspection voltage (3.3 V) in (C). In each degradation determination processing time from (D) to (G), in this embodiment, as an example, processing is performed for 50 head elements. The number of head elements is not limited to 50, but the number that can be processed within the time of the cutting process (ΔT2, ΔT4, ΔT6,... ΔTn + 1) in (A) is selected.

  As described above, in the printer 2, while the receipt is cut by the auto cutter 27, the deterioration determination process is executed for a predetermined number of head elements obtained by dividing the total number of head elements. In other words, the deterioration determination process is not continuously performed for all the head elements, but is performed for the number of head elements that can be completed while the printing process cannot be performed.

  Next, processing contents of the deterioration determination process will be described. As described above, the deterioration determination process is performed during one cycle until the receipt is output. Therefore, first, the process of one cycle until the receipt is output will be described.

  FIG. 7 is a flowchart illustrating an example of a processing procedure for one cycle of receipt printing. First, the head control unit 23 receives a receipt printing instruction from the main control unit 22, outputs a signal to the voltage application circuit 25, and applies a printing voltage (24V) to the thermal head 26 (step S11 in FIG. 7).

  Next, the main control unit 22 starts processing for printing a receipt based on the print data received from the POS application unit 11 (step S12 in FIG. 7). Specifically, the paper transport unit 28 is controlled to sequentially transport the print medium to the position of the thermal head 26 (step S12 in FIG. 7).

  Further, the head control unit 23 is instructed to execute printing on the conveyed print medium. When the printing of the receipt is completed (step S13 in FIG. 7), the head control unit 23 outputs a signal to the voltage application circuit 25 and cuts off the application of the printing voltage (24V) to the thermal head 26 (step in FIG. 7). S14).

  Next, the main control unit 22 drives the auto cutter 27 to start cutting the print medium (step S15 in FIG. 7). Here, the head control unit 23 receives a signal to start driving the auto cutter 27 from the main control unit 22 and executes a deterioration determination process for the thermal head 26 (step S16 in FIG. 7). That is, the head control unit 23 detects the state of the cutting process in which printing cannot be performed, and starts the deterioration determination process. Specific processing contents of the deterioration determination processing will be described later.

  When the cutting of the print medium by the auto cutter 27 ends, the main control unit 22 stops driving the auto cutter 27 and ends the cutting of the print medium (step S17 in FIG. 7).

  In this way, processing for one receipt is executed. This process is executed by the printer 2 every time a receipt printing request is received from the POS terminal device 1.

  Next, the deterioration determination process will be described. FIG. 8 is a flowchart illustrating a specific processing procedure in step S <b> 16 of FIG. 7. First, as described above, the head controller 23 outputs a signal to the voltage application circuit 25 and applies the inspection voltage (3.3 V) to the thermal head 26 (step S161 in FIG. 8).

  Next, the head controller 23 selects one head element (RH-1 to RH-n) for which deterioration is determined (step S162 in FIG. 8). Specifically, as described above, the DI signal is output to the thermal head 26 and the head element is energized.

  As a result, the divided voltage between the inspection resistor R1 and the resistance element (heating element) of the head element is measured, and the value is obtained (step S163 in FIG. 8). That is, information corresponding to the resistance value of the head element (resistance element (heating element)) at this time is acquired.

  Next, the head control unit 23 reads the conversion table of the head element stored in the nonvolatile memory 24, and the resistance value associated with the acquired divided voltage at this time point in the conversion table. The rate of change is read (obtained) (step S164 in FIG. 8). That is, the divided voltage is converted into resistance value information.

  The head controller 23 checks whether or not the acquired resistance value change rate exceeds a threshold value set in the conversion table (step S165 in FIG. 8), and information such as the acquired resistance value change rate ( Deterioration information) is stored (stored) in the nonvolatile memory 24 (step S166 in FIG. 8).

  FIG. 9 is an example of specific data (degradation information) stored in the nonvolatile memory 24.

  In the present embodiment, information of “resistance value change rate” and “alarm flag” is stored (stored) for each head element (head element identification number) of all 512 head elements as deterioration information. The resistance value change rate (%) is the resistance value change rate acquired in step S164, and the “alarm flag” is set (ON) when it is determined that the threshold value is exceeded by the determination in step S165. Flag). In this embodiment, since four threshold values (N1, N2, N3, N4) are set in the conversion table, the “alarm flag” data is data that can be used to determine which threshold value is exceeded. ON (N2) indicates that the threshold value N2 is exceeded but not exceeded, and ON (N1) indicates that the threshold value N1 is exceeded. Further, ON (N3) indicates that the threshold value N3 is exceeded in the minus direction but does not exceed the threshold value N4, and ON (N4) indicates that the threshold value N4 is exceeded in the minus direction.

  In the example illustrated in FIG. 9, for example, the head element “1” indicates that the current (resistance value change rate in the latest detection result) resistance value change rate is “2 to 3%” and does not exceed the threshold value. ing.

  The head element “30” has a resistance value change rate of “−16%”, which indicates that the threshold value N3 is exceeded.

  The head element “50” has a resistance value change rate of “16_17_18%”, which indicates that the threshold value N2 is exceeded.

  In the process of step S166, the values of “resistance change rate (%)” and “alarm flag” are stored (updated) for the selected head element.

  When the resistance value change rate is between -15% and + 15%, the head element has not deteriorated so much (it is not immediately in a deteriorated state to be dealt with) and exceeds 15%. If it is present, or if it is less than −15%, it can be determined that the head element has been degraded (it is a degraded state to be watched).

  It should be noted that the deterioration information may be stored only for the head element whose resistance value change rate exceeds the threshold value as the deterioration information. Further, the divided voltage value measured and the resistance value that can be converted from the divided voltage value may be recorded for each head element.

  In this way, the deterioration determination process for the head element ends. Then, the process proceeds to step S167.

  In step S167, the head control unit 23 applies the test voltage (3.3V) this time (after step S161), and then ends the processing (S162 to S166) for a predetermined number (for example, 50) of head elements. (Step S167 in FIG. 8), and if not finished yet (No in step S167), the process from step S162 is performed for the next head element.

  On the other hand, when the process has been completed for a predetermined number of head elements (Yes in step S167), the head control unit 23 outputs a signal to the voltage application circuit 25 and ends the application of the inspection voltage (3.3V). (Blocked) (Step S168 in FIG. 8).

  In this way, the deterioration determination process executed during the cutting process by the auto cutter 27 ends.

  By such deterioration determination processing, information on a head element in a deteriorated state to be watched and information on the degree of deterioration (resistance value change rate) of the head element can be stored and used for maintenance processing such as replacement of the head element. .

  Note that the number of head elements that perform the deterioration determination process during the cutting process by the auto cutter 27 (the “predetermined number” in step S167 in FIG. 8) is determined in advance as the number of completions of the deterioration determination process during the cutting process. Keep it. When the predetermined number is 50 and the total number of heads is 512, the deterioration determination process for all the head elements is completed while printing of 10 receipts is performed.

  Further, the execution timing of the deterioration determination process is not limited to the time when the auto cutter 27 cuts the print medium, and may be executed at another timing as long as the receipt printing operation cannot be executed. For example, the printing operation of the printer 2 is stopped, for example, when the print medium runs out and the operator opens the cover 29 that can open the storage unit for the print medium or when an error occurs in the printer 2. You may go there. In the former case, the head control unit 23 detects a signal from the main control unit 22 that opens the storage unit, that is, detects a state in which printing cannot be performed, and starts the deterioration determination process. In the latter case, the head controller 23 detects an error occurrence signal issued from the main controller 22, that is, detects a state where printing cannot be executed, and starts the deterioration determination process.

  Further, in the above embodiment, a configuration (mode) may be adopted in which deterioration information is provided to the host device (POS terminal device 1, deterioration management server 3, etc.) side. Specifically, the host device transmits a command to the printer 2, and the printer 2 that has received the command determines whether the determination is based on the measured divided voltage and / or a preset threshold value (degradation using the above threshold value). The result of the determination process is transmitted to the host device.

  If the host device manages the deterioration of the head element by the command from the host device (POS terminal device 1, deterioration management server 3, etc.), a command for instructing (commanding) the initial setting process is prepared. The initial setting process described above in the printer 2 may be performed by transmitting the command from the host device. Further, in this case, a temporary conversion table is stored in the host device, the printer 2 returns the measured divided voltage of each head element to the host device, and each head element is returned by the divided voltage returned by the host device. These conversion tables may be created and stored. In this case, also in the deterioration determination process, the printer 2 (head control unit 23) responds to the command transmitted from the host device and returns the measured divided voltage of each head element to the host device. The above-described deterioration determination (comparison with a threshold value, storage of deterioration information, etc.) is performed using the divided voltage acquired by and the stored conversion table. When the host device is the POS terminal device 1, the deterioration management unit 13 performs these processes.

  Further, it may be possible to set the validity / invalidity (execution / non-execution) and execution timing of the deterioration determination process in the printer 2 by a command from the host device.

  As a modification of the above-described embodiment, a function called ASB (auto status back) is applied to a method in which the host device (POS terminal device 1, deterioration management server 3, etc.) acquires head element deterioration information. May be. Normally, the host device and the printer are in a master / slave relationship, and in principle, the printer does not spontaneously send information to the host device, but the printer 2 sets the predetermined status information. When the status information changes, the status information can be spontaneously transmitted from the printer side to the host device, and its function is ASB. By applying this function, when there is a change in the deterioration information stored in the nonvolatile memory 24, the deterioration information is spontaneously transmitted to the host device. That is, the head control unit 23 reads the deterioration information from the nonvolatile memory 24, and the read deterioration information is sent from the main control unit 22 via the communication unit 21 to the host device (for example, the deterioration management unit 13 of the POS terminal device 1). Sent to.

  Further, as a modification of the above-described embodiment, the deterioration determination process performed for each head element may be performed for each of two or more head elements (a group including a plurality of head elements). That is, the head elements included in the group are energized, the divided voltage is measured, and the degree of deterioration of the entire group is determined. In this case, it is desirable to create and store a conversion table for each group in the initial setting process. In this method, a deterioration determination process for each head element is executed again for a group having a large degree of deterioration (resistance value change rate). In this modification, the number of times of deterioration determination processing (divided voltage measurement) can be reduced and the processing time can be shortened. In this case, in order to increase the measurement accuracy, a multiplexer or the like may be provided to change the resistance value of the inspection resistor R1.

  Further, assuming that the initial resistance values of all the head elements are specification values (resistance values determined by the product specifications), “X” (see FIG. 5) in the temporary conversion table corresponds to the specification value. A table into which is substituted can also be used as a conversion table for all head elements. In this case, although the deterioration judgment accuracy is lowered, the time for the initial setting process can be shortened.

  As described above, in the printer 2 according to the present embodiment and the modified example, printing is not possible, for example, during a cutting process of a print medium, without using a circuit that can perform head element inspection in parallel with the printing process. Since the head element is inspected by using a time that cannot be executed, the deterioration of the head element can be diagnosed without causing any trouble in the printing process. As a matter of course, it is not necessary to increase the circuit scale.

  Further, since the deterioration state of the head element is determined based on the initial divided voltage value acquired in the initial setting process, the deterioration state of each head element can be determined appropriately.

  In addition, the deterioration determination process is not performed continuously for all the head elements, but the deterioration determination process is performed for the number of head elements that can be completed during a period in which printing cannot be performed, such as during the cutting process. There is no hindrance to processing.

  Further, since the deterioration determination process is performed using a plurality of threshold values preset for the divided voltage, the determination of the deterioration state of each head element can be managed in detail.

  In addition, since the deterioration determination process is executed during the print medium cutting process, a process that does not interfere with the print process is guaranteed. Furthermore, as long as the printer 2 is used, the printing medium is printed and cut, so that the head element can be reliably inspected.

  In addition, by performing the determination of head element deterioration when the cover 29 is opened or when an error occurs, processing that does not hinder the printing processing is guaranteed.

  As described above, since the head element deterioration determination process is executed when the receipt printing operation cannot be executed, for example, a receipt printer used in a restaurant or a convenience store that is open for 24 hours. In this case, the head element can be inspected for deterioration without hindering sales.

  Furthermore, by transmitting information related to deterioration determination to the host device, it becomes possible to easily acquire printer deterioration information by an external device such as a host device. Centralized management can be easily performed.

  Further, the host device can operate the deterioration information of the head element from a remote device by a command, and the management of the deterioration information becomes diverse.

  In this way, the printer 2 can grasp the deterioration state of each head element step by step, so that the head element can be replaced at an appropriate time, and printing defects due to defective head elements can be prevented. can do.

  In addition, since the information regarding the deterioration of the printer 2 is transmitted to the POS terminal device 1 and the deterioration management server 3 by the ASB function or the like, the deterioration information of the printer can be easily acquired on the host device side. Therefore, it becomes possible to easily manage the deterioration of the printer, particularly the intensive management in the remote device.

[Second Embodiment]
In the first embodiment, the divided voltage and the resistance value change rate are stored in the form of a conversion table in the initial setting process, and the resistance value change rate is acquired immediately from the divided voltage measured at the time of deterioration determination. Although this method is used, since it is necessary to hold a conversion table for each head element (RH-1 to RH-n), in the second embodiment, one conversion table CT is used. And using the conversion table CT, a method of calculating a resistance value change rate at the time of deterioration determination is adopted.

  Hereinafter, the specific contents will be described focusing on the differences from the first embodiment.

  First, the device configuration (functional configuration) and the circuit configurations of the voltage application circuit 25 and the thermal head 26 are the same as those in the first embodiment described with reference to FIGS.

  However, the non-volatile memory 24 stores one common conversion table CT instead of the temporary conversion table and the conversion table of each head element (RH-1 to RH-n).

  This conversion table CT is a table for converting a divided voltage value (AD value) into a resistance value (Ω). The conversion table CT is generated before shipment of the printer 2 and is non-volatile of the printer 2. Stored in the memory 24. Hereinafter, the contents of the conversion table CT will be described.

  In the series circuit connecting the inspection resistor R1 and the resistance element (heating element) of the head element, which is formed when the head elements (RH-1 to RH-n) are inspected (deterioration judgment), the resistance of the inspection resistor R1 When the value (Ω) is expressed by R and the resistance value (Ω) of the resistance element of the head element is expressed by Rhead, the following relational expression (1) is established.

Rhead = (R × AD) / (255−AD) (1)
Note that AD is a divided voltage value (AD value) read via the A / D converter ADC by “READ_HEAD” in FIG. 2, for example, 1 byte of 0-255 (corresponding to 0-3.3 V) It is expressed with the data. The divided voltage value (AD value) is preferably expressed by data of 4 bytes or less.

  FIG. 10 is a graph showing the relationship between the divided voltage value (AD value) and the resistance value (Rhead). The graph illustrated in FIG. 10 is obtained based on the relational expression (1) when the resistance value R of the inspection resistor R1 is 255Ω. The graph can be used to convert a measured (acquired) divided voltage value (AD value) into a resistance value (Rhead), and the correspondence table is expressed in a tabular form as a conversion table CT. .

  FIG. 11 is a diagram illustrating an example of the conversion table CT. As shown in FIG. 11, the “resistance value (Ω)” associated with the relational expression (1) is associated with the “AD value” that is the divided voltage value in the conversion table CT. . Therefore, if the conversion table CT is used, the resistance value (Rhead) of the head element to be measured can be immediately acquired from the AD value measured (acquired) at the time of inspection (degradation judgment).

  Such a conversion table CT is stored in each printer before shipment. Since each printer 2 has an error due to the pattern on the substrate and the resistance value of the element, the actual measurement is performed and the value (resistance value) of the conversion table CT is adjusted so as to match the measurement result. Alternatively, the AD value may be corrected. In this case, a conversion table CT corresponding to each individual printer 2 is generated and stored in the printer 2.

  In the second embodiment, the following processing is executed using the conversion table CT described above.

  First, instead of the conversion table creation processing for each head element (RH-1 to RH-n) described with reference to FIG. 3 performed in the first embodiment, each head element (RH-1 to RH). -N) The initial value acquisition process is performed.

  In the head elements (RH-1 to RH-n), it is known that the resistance value of the heating element (resistive element) changes as the deterioration progresses. There are several phenomena in the way of change, but in one phenomenon, the resistance value gradually increases. In other phenomena, the resistance value gradually decreases and then increases rapidly. In either case, if the resistance value increases more than a certain level, there is a risk of not generating sufficient heat during printing and causing printing failure.

  Therefore, in determining the deterioration of the head elements (RH-1 to RH-n), it is important to grasp the change in resistance value (of the heating element) of each head element (RH-1 to RH-n) step by step. is there.

  Therefore, in the second embodiment, first, after performing processing (initial value acquisition processing) for grasping the initial state values (initial values) of the head elements (RH-1 to RH-n), A value (state value) indicating the state at that time is measured at a certain frequency, and the deterioration is determined based on the initial value and the state value.

  FIG. 12 is a flowchart illustrating the procedure of the initial value acquisition process. The initial value acquisition process is executed when the printer 2 is activated for the first time.

  First, the head controller 23 outputs a signal to the voltage application circuit 25 and applies a test voltage (3.3 V) to the thermal head 26 (step S21 in FIG. 12).

  Next, the head controller 23 selects one head element (RH-1 to RH-n) from which an initial value is acquired, and energizes the head element (RH-1 to RH-n) (see FIG. 12). Steps S22 and S23). Specifically, as described above, the DI signal is output to the thermal head 26 and the head element is energized.

  This forms a series circuit that connects the inspection resistor R1 and the resistance element (heating element) of the head element. After waiting for the voltage to stabilize (step S24 in FIG. 12), the head controller 23 A measured value (AD value) of the divided voltage between the inspection resistor R1 of the series circuit and the resistance element (heating element) of the head element is acquired by the READ_HEAD signal (step S25 in FIG. 12). That is, information corresponding to the initial resistance value (of the resistance element (heating element)) of the head element is acquired.

  Next, the head controller 23 stores (saves) the acquired AD value in the nonvolatile memory 24 as an initial value of the head element (step S26 in FIG. 12).

  The acquired AD value may be converted into a resistance value using the conversion table CT stored in the nonvolatile memory 24, and the converted resistance value may be stored in the nonvolatile memory 24 as an initial value. . Note that by setting the AD value as an initial value, the amount of data to be stored can be suppressed to 1 byte.

  The head controller 23 executes the above-described initial value acquisition process (S22-S26) for all the head elements (RH-1 to RH-n) (No in step S27 in FIG. 12).

  When the initial value acquisition process is executed for all the head elements (RH-1 to RH-n) (Yes in step S27 in FIG. 12), the process ends, and all the head elements (RH-1 to RH-n) are processed. ) Is stored in the nonvolatile memory 24.

  Next, the degradation determination process in the second embodiment will be described. The deterioration determination process is performed at the same timing as in the case of the first embodiment, that is, the printing process described based on FIG. 7 is performed in the same manner, and the deterioration determination process described based on FIG. 8 is performed. Instead, the following processing is executed.

  The head control unit 23 executes the state value acquisition process at this timing.

  FIG. 13 is a flowchart illustrating the procedure of the state value acquisition process. First, the head control unit 23 outputs a signal to the voltage application circuit 25 and applies a test voltage (3.3 V) to the thermal head 26 (step S31 in FIG. 13).

  Next, the head control unit 23 selects one head element (RH-1 to RH-n) from which the state value is acquired, and energizes the head element (RH-1 to RH-n) (see FIG. 13). Steps S32 and S33). Specifically, as described above, the DI signal is output to the thermal head 26 and the head element is energized.

  This forms a series circuit that connects the inspection resistor R1 and the resistance element (heating element) of the head element. After waiting for the voltage to stabilize (step S34 in FIG. 13), the head controller 23 A measured value (AD value) of the divided voltage between the inspection resistor R1 of the series circuit and the resistance element (heating element) of the head element is acquired by the READ_HEAD signal (step S35 in FIG. 13). That is, information corresponding to the current resistance value of the head element (of the resistance element (heating element)) is acquired.

  Next, the head control unit 23 stores (saves) the acquired AD value as the state value of the head element in the nonvolatile memory 24 (step S36 in FIG. 13). The state value may be stored in a RAM in the head controller 23.

  The acquired AD value may be converted into a resistance value using the conversion table CT stored in the nonvolatile memory 24, and the converted resistance value may be stored in the nonvolatile memory 24 as a state value. . Note that the amount of data to be stored can be suppressed to 1 byte by using the AD value as the state value.

  The head controller 23 executes the state value acquisition process (S32-S36) described above for a predetermined number of head elements (RH-1 to RH-n) similar to those in the first embodiment (FIG. 13). No of step S37).

  When the state value acquisition process is executed for the predetermined number of head elements (RH-1 to RH-n) (Yes in step S18 in FIG. 13), the head control unit 23 sets the inspection voltage (3.3V). The application is cut off (step S38 in FIG. 13), and the process ends. As a result, the state values are stored in the nonvolatile memory 24 for all the head elements (RH-1 to RH-n).

  The state value acquisition process described above is repeatedly executed at a timing at which the printing described in the first embodiment cannot be executed, and the state values are acquired for all the head elements (RH-1 to RH-n). Then, the head control unit 23 executes a deterioration information acquisition process (resistance value change rate acquisition process).

  FIG. 14 is a flowchart illustrating the procedure of the deterioration information acquisition process. First, the head controller 23 selects one head element (RH-1 to RH-n) (step S41 in FIG. 14). Thereafter, the head controller 23 accesses the nonvolatile memory 24 and reads the initial values of the selected head elements (RH-1 to RH-n) (step S42 in FIG. 14). The initial value is acquired and stored in the initial value acquisition process described above.

  The head control unit 23 converts the read initial value into a resistance value using the conversion table CT stored in the nonvolatile memory 24 (step S43 in FIG. 14). Since the read initial value is an AD value, conversion to a resistance value is performed by reading the resistance value (Ω) stored in association with the AD value in the conversion table CT.

  Next, the head controller 23 accesses the nonvolatile memory 24 and reads the state values of the selected head elements (RH-1 to RH-n) (step S44 in FIG. 14). The state value is acquired and stored in the state value acquisition process described above.

  The head control unit 23 converts the read state value into a resistance value using the conversion table CT stored in the nonvolatile memory 24 (step S45 in FIG. 14). Since the read state value is an AD value, conversion to a resistance value is performed by reading the resistance value (Ω) stored in association with the AD value in the conversion table CT.

  Next, the head controller 23 calculates a resistance value change rate (step S46 in FIG. 14). Specifically, the following equation (2) is used.

Resistance value change rate (%) = (state value (Ω) −initial value (Ω)) / initial value (Ω) × 100 (2)
The initial value (Ω) is the initial value converted into the resistance value in step S43, and the state value (Ω) is the state value converted into the resistance value in step S45.

  If the calculated resistance value change rate is negative, it means that the resistance values of the head elements (RH-1 to RH-n) are decreasing, and the calculated resistance value change rate is positive. In this case, it means that the resistance value of the head elements (RH-1 to RH-n) is increased.

  As described above, when the deterioration of the head elements (RH-1 to RH-n) is progressing, the resistance value may be decreasing or increasing, and in any case, the absolute value is If it exceeds a predetermined value, the user should be informed that there is a risk of missing dots.

  Therefore, the predetermined value is set as a threshold value, and the head controller 23 determines whether or not the calculated resistance value change rate exceeds the threshold value. Specifically, for example, the threshold value is set to “15%” and “30%” in absolute values.

  Thereafter, the head controller 23 stores (saves) the determination result using the calculated resistance value change rate and the threshold value in the nonvolatile memory 24 as deterioration information (step S47 in FIG. 14).

  FIG. 15 is a diagram showing an example of deterioration information. The deterioration information illustrated in FIG. 15 includes the calculated resistance of the head element (RH-1 to RH-n) in the identification information (head element No.) of each head element (RH-1 to RH-n). This is information in which a value change rate is associated with an alarm flag as a determination result using the threshold value. These pieces of information are stored (saved) in the nonvolatile memory 24.

  In the example illustrated in FIG. 15, for example, four threshold values “15%”, “30%”, “−15%”, and “−30%” are set as the above-described threshold values. The threshold values of “15%” and “−15%” are criteria for mild progress of deterioration, and head elements (RH-1 to RH-n) exceeding these (“-15%” is lower than this). ) ON (A) is set (stored) in the alarm flag. In addition, the threshold values of “30%” and “−30%” are criteria for the progress of deterioration of the strength, and head elements (RH-1 to RH) exceeding these values (“−30%” is lower than this). The alarm flag (-n) is ON (B) (stored). Note that OFF is stored in the alarm flags of the head elements (RH-1 to RH-n) that do not exceed the threshold value.

  For example, in FIG. The head element (RH-1 to RH-n) “2” has a resistance value change rate of “5%”, and therefore the alarm flag is “OFF”. The head element No. The head element (RH-1 to RH-n) “61” has a resistance value change rate of “−18%”, and therefore the alarm flag is “ON (A)”. The head element No. The head element (RH-1 to RH-n) “150” has a resistance value change rate of “33%”, and therefore the alarm flag is “ON (B)”. From these deterioration information, the head element No. It can be determined that the head elements (RH-1 to RH-n) “2” have not deteriorated so much. It can be determined that the head elements (RH-1 to RH-n) of “61” have deteriorated to some extent. It can be judged that the head elements (RH-1 to RH-n) of “150” have considerably deteriorated.

  The head control unit 23 executes the deterioration information acquisition process (S41 to S47) described above for all the head elements (RH-1 to RH-n) (No in step S48 in FIG. 14).

  When the deterioration information acquisition process is executed for all the head elements (RH-1 to RH-n) (Yes in step S48 in FIG. 14), the process ends and all the head elements (RH-1 to RH-n). ) Is stored in the nonvolatile memory 24.

  In the above-described embodiment, the deterioration information acquisition process is performed after the state values are acquired for all the head elements (RH-1 to RH-n), but the head elements (RH-1 to RH-n) are used. ), It may be a processing procedure for continuously obtaining the state value and obtaining the deterioration information.

  FIG. 16 is a flowchart illustrating a procedure in a case where acquisition of state values and acquisition of deterioration information are performed continuously. This process is executed at a timing at which printing cannot be performed, similarly to the process described with reference to FIG.

  First, the head control unit 23 outputs a signal to the voltage application circuit 25 and applies a test voltage (3.3 V) to the thermal head 26 (step S51 in FIG. 16).

  Next, the head controller 23 selects one head element (RH-1 to RH-n) and energizes the head element (RH-1 to RH-n) (steps S52 and S53 in FIG. 16). . Specifically, as described above, the DI signal is output to the thermal head 26 and the head element is energized.

  As a result, a series circuit that connects the inspection resistor R1 and the resistance element (heating element) of the head element is formed. After waiting for the voltage to stabilize (step S54 in FIG. 16), the head controller 23 A measured value (AD value) of the divided voltage between the inspection resistor R1 of the series circuit and the resistance element (heating element) of the head element is acquired by the READ_HEAD signal (step S55 in FIG. 16). That is, information corresponding to the current resistance value of the head element (of the resistance element (heating element)) is acquired.

  Next, the head controller 23 converts the acquired state value into a resistance value using the conversion table CT stored in the nonvolatile memory 24 (step S56 in FIG. 16). Since the read state value is an AD value, conversion to a resistance value is performed by reading the resistance value (Ω) stored in association with the AD value in the conversion table CT.

  Next, the head controller 23 accesses the nonvolatile memory 24 and reads the initial values of the selected head elements (RH-1 to RH-n) (step S57 in FIG. 16). The initial value is acquired and stored in the initial value acquisition process described above.

  The head control unit 23 converts the read initial value into a resistance value using the conversion table CT stored in the nonvolatile memory 24 (step S58 in FIG. 16). Since the read initial value is an AD value, conversion to a resistance value is performed by reading the resistance value (Ω) stored in association with the AD value in the conversion table CT.

  Next, the head controller 23 calculates a resistance value change rate (step S59 in FIG. 16). Specifically, it is performed in the same manner as step S46 in FIG.

  Thereafter, the head control unit 23 executes a deterioration information storing process (step S60 in FIG. 16). Specifically, it is performed in the same manner as step S47 in FIG.

  The head controller 23 executes the above-described deterioration determination process (S52-S60) for a predetermined number of head elements (RH-1 to RH-n) as in FIG. 13 (in step S61 of FIG. 16). No).

  When the deterioration determination process is executed for the predetermined number of head elements (RH-1 to RH-n) (Yes in step S61 in FIG. 16), the head controller 23 applies the inspection voltage (3.3V). (Step S62 in FIG. 16), and the process ends. As a result, the deterioration information is stored in the nonvolatile memory 24 for all the head elements (RH-1 to RH-n).

  The processing described above is repeatedly executed at a timing at which printing described in the first embodiment cannot be executed, and deterioration information is acquired and stored for all the head elements (RH-1 to RH-n). The

  In the second embodiment, the process is executed in this way. The other points are the same as in the case of the first embodiment.

  As described above, in the printer 2 according to the second embodiment, deterioration can be determined from the resistance value at an appropriate timing for each head element, and the printer 2 stores the conversion table CT in advance. Therefore, the amount of data stored in the printer 2 can be reduced.

  In addition, since the initial values (divided voltage value (AD value) and resistance value (Ω)) of each head element are used for the deterioration determination, an appropriate deterioration determination can be performed.

  Since the deterioration information includes the resistance value change rate of the head element, it is possible to accurately determine the deterioration.

  The AD value stored until the resistance value change rate is calculated is data of 4 bytes or less, and the amount of data to be stored can be reduced.

  The protection scope of the present invention is not limited to the above-described embodiment, but covers the invention described in the claims and equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... POS terminal device, 2 ... Printer, 3 ... Deterioration management server, 4 ... Communication network, 11 ... POS application part, 12 ... Printer driver part, 13 ... Deterioration management part, 21 ... Communication part, 22 ... Main control part, DESCRIPTION OF SYMBOLS 23 ... Head control part, 24 ... Non-volatile memory, 25 ... Voltage application circuit, 26 ... Thermal head, 27 ... Auto cutter, 28 ... Paper conveyance part, 29 ... Cover, 100 ... Printer system, 200 ... Deterioration management system, 262 ... Latch driver, 263 ... Shift register, RH-1 to RH-n ... Head element, CT ... Conversion table.

Claims (11)

A thermal head for performing printing on a print medium by a plurality of head elements;
A voltage application circuit for applying a first voltage or a second voltage to the head element;
A head controller that measures a divided voltage of the head element,
When the head control unit detects a state where the printing cannot be performed, the voltage application circuit switches the voltage applied to the head element to the second voltage, and measures the divided voltage of the head element. A printing apparatus characterized by that. In claim 1,
Furthermore, it has a data storage unit,
The thermal head further includes a selection unit,
When the head control unit detects a state where the printing cannot be performed,
For each head element,
The selection unit selects the head element, measures the divided voltage of the series circuit by the resistance element of the head element and the test resistor of the voltage application circuit, and stores the measured divided voltage and the data storage unit in advance. A printing apparatus that performs a deterioration determination process that determines a deterioration state of the head element based on the stored initial divided voltage value. In claim 2,
The deterioration determination process is executed for a predetermined number of head elements obtained by dividing the total number of head elements that can be completed while the printing cannot be executed. In any one of Claims 1 thru | or 3,
The printing apparatus according to claim 1, wherein the head control unit determines a deterioration state of the head element by using a plurality of threshold values preset for the divided voltage. In any one of Claims 1 thru | or 4,
Furthermore, it has an auto cutter for cutting the printing medium after the printing,
The detection of the state where the printing cannot be executed is to detect the start of the cutting by the auto cutter. In any one of Claims 1 thru | or 5,
Furthermore, the housing of the printing apparatus has a cover that can open the storage portion for the print medium,
The detection of the state in which the printing cannot be performed is to detect the opening of the cover. In any one of Claims 1 thru | or 6,
Detection of a state where the printing cannot be performed is detection of occurrence of an error in the printing apparatus. In any one of Claims 1 thru | or 7,
The printing apparatus, wherein the second voltage and the voltage of the head control unit are the same. A thermal head that performs printing on a print medium by a plurality of head elements, a voltage application circuit that applies a first voltage or a second voltage to the head elements, a head controller that measures a divided voltage of the head elements, A control method for a printing apparatus comprising:
When the head control unit detects a state where the printing cannot be performed, the voltage application circuit switches the voltage applied to the head element to the second voltage, and measures the divided voltage of the head element. A control method characterized by that. A thermal head that performs printing on a print medium by a plurality of head elements, a voltage application circuit that applies a first voltage or a second voltage to the head elements, a head controller that measures a divided voltage of the head elements, A printing system including a communication unit, and a host device of the printing device,
When the head controller of the printing apparatus detects a state where the printing cannot be performed, the voltage application circuit switches the voltage applied to the head element to the second voltage, thereby dividing the voltage of the head element. Measure the voltage,
The degradation state of the head element is determined using a threshold value set in advance with respect to the divided voltage, and the determination result based on the measured divided voltage and / or the threshold value is determined by the communication unit by the host device. Send to
The printing system, wherein the host device acquires the transmitted information. In claim 10,
The host device sends a command to the printing device;
The printing system receives the command and transmits information to the host device by the head control unit.

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