Printer, thermal head control method, program

Abstract

To improve the noise immunity of the thermal head in printers. [Solution] A printer according to one aspect of the present invention includes a thermal head having a heating section having a plurality of heating elements arranged in a line, a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energizing period based on a signal indicating the energizing period of the heating section during the printing period of one line, and a control unit that sets a voltage supply period, which is the period during which the heating section voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating section is the heating section voltage.

Description

[Technical Field]

[0001] This invention relates to a printer that performs printing using a thermal head. [Background technology]

[0002] A thermal head is equipped with multiple heating elements, and a printer equipped with a thermal head is configured to print on the printing medium by selectively heating these multiple heating elements. It is known that a thermal head includes multiple heating elements as well as a driver IC for controlling the power supply to each heating element (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-190334 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, if the driver IC mounted on the thermal head is subjected to external noise, the driver IC may enter a latch-up state. For example, near the thermal head, the printing medium and thermal transfer ink ribbon can become charged as they are transported within the printer, making the thermal head susceptible to noise caused by electrostatic discharge from the printing medium and ink ribbon. When the driver IC enters a latch-up state, it cannot be controlled from the outside, and the multiple heating elements corresponding to the driver IC continue to be energized, causing them to overheat. This can result in printing being darker than intended and ultimately leading to a break in the circuit.

[0005] Therefore, the present invention aims to improve the noise immunity of the thermal head in a printer. [Means for solving the problem]

[0006] One aspect of the present invention is a thermal head having a plurality of heating elements arranged in a line, and a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energization period based on a signal indicating the energization period of the heating section during a one-line printing period. A printer comprising: a control unit that sets a voltage supply period, which is a period during which the heating section voltage, which is a voltage for energizing the heating section, is supplied to the thermal head, according to the energization period.

Advantages of the Invention

[0007] According to one aspect of the present invention, in a printer, the noise resistance of the thermal head can be improved.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1A is a schematic side view of a printer according to an embodiment, and FIG. 1B is a schematic side view showing an enlarged view of a portion related to printing by the printer shown in FIG. 1A. [Figure 2] It is a functional block diagram of a printer according to an embodiment. [Figure 3] It is a functional block diagram showing a detailed configuration of the control unit in FIG. 2. [Figure 4] It is a schematic circuit diagram of a thermal head according to an embodiment. [Figure 5] It is a schematic circuit diagram of a thermal head when including a plurality of driver ICs. [Figure 6] It is a diagram showing an operation example of a thermal head in a printer according to an embodiment. [Figure 7] It is a diagram showing an example of operation waveforms of a strobe signal and a heating section voltage in FIG. 6. [Figure 8] It is a diagram showing an operation example of a thermal head in a printer according to an embodiment. [Figure 9] It is a diagram showing an operation example of a thermal head in a printer according to an embodiment. [Figure 10] Figure 9 shows an example of the operating waveforms of the heating element voltage and the IC power supply voltage. [Figure 11] This figure shows an example of the operation of a thermal head in a printer according to one embodiment. [Figure 12] This figure shows an example of the operation of a thermal head in a printer according to one embodiment. [Figure 13] This figure shows an example of the operation of a thermal head in a printer according to one embodiment. [Figure 14] This figure shows an example of the operation of a thermal head at different printing speeds in a printer according to one embodiment. [Figure 15] This figure shows an example of operation in one embodiment of a printer, where a stop process is performed after printing a label to reset the driver IC. [Figure 16] This figure shows an example of operation in one embodiment of a printer, where a stop process is performed after the completion of a single print job to reset the driver IC. [Modes for carrying out the invention]

[0009] The forms described below are not limited to those shown in the brief description of the drawings.

[0010] A first aspect of one aspect of the present invention is a printer comprising: a heating unit having a plurality of heating elements arranged in a line; a drive circuit that drives the heating unit to control whether or not to energize each heating element of the heating unit during the energizing period based on a signal indicating the energizing period of the heating unit during the printing period of one line; and a control unit that sets a voltage supply period, which is the period during which the heating unit voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating unit is the heating unit voltage.

[0011] According to a first aspect of a certain embodiment of the present invention, the noise immunity of a thermal head can be improved.

[0012] A second aspect of a certain embodiment of the present invention is the printer according to the first embodiment, wherein the control unit sets the voltage supply period such that the energizing period is included in the voltage supply period.

[0013] According to a second aspect of a certain embodiment of the present invention, the voltage supply period can be appropriately set taking into account the delay in supplying the head operating voltage, etc.

[0014] A third aspect of a certain embodiment of the present invention is the printer according to the first or second embodiment, wherein the control unit sets the voltage supply period such that it starts a predetermined time before the start time of the energizing period and ends a predetermined time after the end time of the energizing period.

[0015] According to a third aspect of a certain embodiment of the present invention, the voltage supply period can be appropriately set considering the delay in supplying the head operating voltage, etc.

[0016] A fourth aspect of a certain embodiment of the present invention is the printer according to the first embodiment, wherein the control unit sets the voltage supply period so that the voltage supply period is synchronized with the energization period.

[0017] According to a fourth aspect of a certain embodiment of the present invention, the start and end of the supply of the head operating voltage can be made to coincide with the start and end of the energizing period.

[0018] A fifth aspect of a certain embodiment of the present invention is a printer according to any one of the first to fourth embodiments, wherein the control unit sets the voltage supply period such that, when the power supply period is set multiple times within the printing period of one line, the supply of the heating element voltage is started according to the start time of the first power supply period among the multiple power supply periods, and the supply of the heating element voltage is stopped according to the end time of the last power supply period.

[0019] According to a fifth aspect of a certain embodiment of the present invention, when multiple energizing periods are set, the head operating voltage can be reliably supplied during each energizing period.

[0020] A sixth aspect of a certain embodiment of the present invention is a printer according to any one of the first to fifth embodiments, wherein when the control unit starts driving the heat-generating part, it starts supplying a circuit voltage to operate the drive circuit before starting to supply the heat-generating part voltage, and when it stops driving the heat-generating part, it stops supplying the heat-generating part voltage before stopping the supply of the circuit voltage.

[0021] According to a sixth aspect of a certain embodiment of the present invention, it is possible to avoid a situation in which the heat-generating part is energized when no voltage is supplied to the signal generation part.

[0022] A seventh aspect of a certain embodiment of the present invention is a printer according to any one of the first to sixth embodiments, wherein the control unit controls the drive circuit to perform a stop process that resets the drive circuit by stopping the supply of an operating voltage for operating the drive circuit for a predetermined period of time.

[0023] According to a seventh aspect of a certain embodiment of the present invention, the noise immunity of the thermal head can be further improved.

[0024] An eighth aspect of one aspect of the present invention is a control method for a thermal head. The thermal head includes a heating section having a plurality of heating elements arranged in a line, and a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energizing period, based on a signal indicating the energizing period of the heating section during the printing period of one line. The control method includes the steps of supplying a signal indicating the energizing period to the thermal head, and setting a voltage supply period, which is the period during which the heating element voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating element is the heating element voltage.

[0025] According to an eighth aspect of a certain embodiment of the present invention, the noise immunity of a thermal head can be improved.

[0026] A ninth aspect of one aspect of the present invention is a program that causes a computer to perform a predetermined procedure in a printer having a thermal head. The thermal head includes a heating section having a plurality of heating elements arranged in a line, and a drive circuit that drives the heating section to control whether or not to energize each heating element of the heating section during the energizing period, based on a signal indicating the energizing period of the heating section during the printing period of one line. The predetermined procedure includes a procedure for supplying a signal indicating the energizing period to the thermal head, and a procedure for setting a voltage supply period, which is the period during which the heating element voltage is supplied to the thermal head, according to the energizing period, when the voltage used to energize the heating element is defined as the heating element voltage.

[0027] According to a ninth aspect of a certain embodiment of the present invention, the noise immunity of a thermal head can be improved.

[0028] The printer 1 according to this embodiment will be described in detail below with reference to the drawings. Figure 1A is a side view of the main parts of printer 1 with the internal components visible. Figure 1B is a magnified and schematic side view showing the parts related to printing by printer 1 as shown in Figure 1A. Printer 1 is a thermal printer that prints information such as characters, symbols, graphics, or codes onto labels having a heat-sensitive color-developing layer on one side. As shown in Figure 1A, the printer 1 contains a paper supply unit 9, a head unit 5, and an ink ribbon unit 12. Printer 1 is equipped with a retractable printer cover (not shown), but Figure 1A shows the printer with the cover removed.

[0029] The paper supply unit 9 is loaded with roll paper R. Roll paper R is made by winding a strip of continuous paper CP into a roll. Roll paper R can be replaced by opening the printer cover (not shown). In one embodiment, although not shown, the continuous paper CP has, for example, a strip of backing paper and a plurality of labels temporarily attached to the backing paper at predetermined intervals. The label attachment surface of the backing paper is coated with a release agent such as silicone so that each label can be easily peeled off. In another embodiment, the continuous paper CP may be labels without backing paper.

[0030] As shown in Figure 1B, in the printer 1, the platen roller 10 is supported in a state where it can rotate freely in forward and reverse directions. The platen roller 10 is a conveying means for transporting the continuous paper CP drawn from the roll paper R. The rotation axis of the platen roller 10 extends along the width direction of the continuous paper CP. A gear (not shown) is provided at one end of the platen axis of the platen roller 10, and this gear is mechanically connected to a stepping motor (not shown) for roller driving. The stepping motor operates based on a signal transmitted from the control unit, which will be described later, and the platen roller 10 rotates. Printing takes place on the label on the continuous paper CP while the continuous paper CP is being pulled from the roll paper R and ejected from the output slot 20.

[0031] The ink ribbon unit 12 comprises a ribbon supply unit 12a and a ribbon winding unit 12b, and supplies and winds up an ink ribbon RB coated with printing ink. The ribbon supply unit 12a supports the ink ribbon RB wound into a roll so that it can rotate. The ribbon winding unit 12b winds up and collects the printed ink ribbon RB. When using the ink ribbon RB, the ink ribbon RB is pulled out from the ribbon supply unit 12a, passed under the head unit 5, and wound up by the ribbon winding unit 12b.

[0032] The head unit 5 is installed inside the printer 1 in a state where it can be opened and closed, and includes a thermal head 15 that prints on labels. The thermal head 15 is a printing means that sequentially prints information onto multiple labels on continuous paper CP. As described later, the thermal head 15 is equipped with multiple heating elements (heating resistors) arranged along the width direction of the continuous paper CP, and prints by selectively energizing the multiple heating elements based on signals transmitted from the control unit. When the heating elements of the thermal head 15, which are heated by the current, are pressed against the labels on the continuous paper CP via the ink ribbon RB, the printing ink of the ink ribbon RB melts and is transferred to the labels, thereby printing information onto the labels. The thermal head 15 will be explained in more detail later.

[0033] Next, we will explain the internal configuration of printer 1 with reference to Figure 2. Figure 2 is a block diagram showing the internal configuration of printer 1. As shown in Figure 2, printer 1 includes, for example, a control unit 11, a drive circuit 13, a motor 14, a thermal head 15, a power supply unit 16, and a storage unit 18. The control unit 11 includes a processor and memory and controls various operations of the printer 1. The processor reads and executes firmware stored in memory when the printer 1 is started up. For example, the control unit 11 sends control signals to the drive circuit 13 for controlling the rotational movement of the motor 14, and sends data signals and control signals for printing to the thermal head 15. The control unit 11 performs the printing process by selectively controlling the flow of current to each of the multiple heating elements included in the thermal head 15 based on the image data to be printed. The image data is data obtained by drawing the file for printing as bitmap data. A detailed configuration example of the control unit 11 will be described later.

[0034] Storage 18 is a storage device such as an SSD (Solid State Drive). Storage 18 stores, for example, print files obtained from the host computer and print format information for printing information on each label. The drive circuit 13 is a circuit that drives a motor 14 that controls the rotation of the platen roller 10 in response to a transport request from the control unit 11. The clock pulse M_CLK is a pulse signal supplied from the control unit 11 to the drive circuit 13 to operate the motor 14. The motor 14 is, for example, a stepping motor and is mechanically connected to the platen roller 10. The transport request includes, for example, information on the transport direction (forward or reverse) and the amount to be transported (e.g., number of steps). The power supply unit 16 is connected to a commercial AC power supply and generates a DC reference voltage that serves as the basis for operating each part of the printer 1.

[0035] Next, the printing operation of printer 1 will be described with reference to Figures 3 and 4. Figure 3 is a functional block diagram showing the detailed configuration of the control unit 11 in Figure 2. Figure 4 is a schematic circuit diagram of the thermal head 15.

[0036] As shown in Figure 3, the control unit 11 includes a head controller 21, a memory 22, a heat generation unit 23, and an IC power generation unit 24. The head controller 21 controls the entire printing operation in the control unit 11. The head controller 21 supplies the clock pulse CLK, data signal DATA, latch pulse LATCH, and strobe signal STB to the thermal head 15. The clock pulse CLK is the reference pulse used to operate the thermal head 15. In printer 1, the start of the printing cycle is synchronized with the clock pulse M_CLK. In this sense, the thermal head 15 operates based on the clock pulse M_CLK. Memory 22 is, for example, RAM (Random Access Memory) and has an image buffer with a FIFO (First In First Out) configuration. Image data is stored in the image buffer. The image data is the dot-level data of the entire image to be printed on a single label.

[0037] In one embodiment, the head controller 21 sequentially generates data signals DATA based on line-by-line image data (line data). The data signals DATA are signals indicating whether or not to energize the corresponding heating element for each dot in a line within the energizing period defined by the strobe signal STB (data indicating "energized" or "not energized"). In some cases, one strobe signal STB may be set within the printing period of one line, while in other cases, multiple strobe signal STBs may be set. For example, when printing is performed using thermal history control, multiple strobe signals (STBs) are set during the printing cycle to precisely control the energization period and timing within the printing period of one line (hereinafter also referred to as the "printing cycle").

[0038] When a single strobe signal STB is set during the printing cycle (hereinafter referred to as "single strobe"), the data signal DATA indicates whether or not to energize each heating element during the energizing period defined by the single strobe signal STB. In one embodiment, the strobe signal STB is a low-active signal that indicates the energizing period when it is at an L level. When multiple strobe signals STB are set during the printing cycle (hereinafter referred to as "multi-strobe"), the data signal DATA is a signal that indicates whether or not to energize each heating element during each energizing period defined by each of the multiple strobe signals STB.

[0039] As shown in Figure 3, the control unit 11 includes a heat-generating unit 23 and an IC power-generating unit 24. The heat-generating unit 23 and the IC power-generating unit 24 each include a boost circuit and / or a buck circuit. The heat-generating section power generation unit 23 generates a voltage V1 for energizing the heat-generating section 40 (see Figure 4) of the thermal head 15, based on the reference voltage generated by the power supply unit 16. The voltage V1 is, for example, 19 to 24V. The IC power generation unit 24 generates a voltage V2 that operates the driver IC 30 (see Figure 4) of the thermal head 15, based on the reference voltage generated by the power supply unit 16. The voltage V2 is, for example, 3.3 to 5V.

[0040] As shown in Figure 3, the control unit 11 includes a switch SW1 provided between the heat generation unit 23 and the thermal head 15, and a switch SW2 provided between the IC power generation unit 24 and the thermal head 15. Switches SW1 and SW2 may each be composed of transistors. The head controller 21 controls the conduction state of switch SW1 by the control signal CTRL1, thereby setting the heat-generating part voltage VH to voltage V1 or 0V. When the heat-generating part voltage VH is voltage V1, the voltage required to energize the heat-generating part 40 of the thermal head 15 is effectively supplied to the thermal head 15. In the following explanation, setting the heat-generating part voltage VH to voltage V1 is equivalent to supplying the heat-generating part voltage VH to the thermal head 15. The head controller 21 controls the conduction state of switch SW2 by the control signal CTRL2, thereby setting the IC power supply voltage Vdd to voltage V2 or 0V. When the IC power supply voltage Vdd is voltage V2, the voltage required to operate the driver IC 30 of the thermal head 15 is effectively supplied to the thermal head 15. In the following explanation, setting the IC power supply voltage Vdd to voltage V2 is equivalent to supplying the IC power supply voltage Vdd to the thermal head 15.

[0041] As shown in Figure 4, the thermal head 15 has a driver IC 30 (an example of a drive circuit) and a heating element 40. The heating element 40 includes a plurality of heating elements (heating resistors) 40_1, 40_2, ..., 40_n arranged in a line. The driver IC 30 operates to selectively supply current to each heating element of the heating unit 40 (i.e., selectively energize each heating element) based on various signals supplied from the head controller 21.

[0042] The driver IC 30 includes a shift register (S / R) 31 for temporarily storing one line of data signal DATA in synchronization with the clock pulse M_CLK, a latch circuit (L) 32, an inverter 33, a NAND gate section 34, and a switch section 35. The data corresponding to each dot of the data signal DATA for one line is bit data for each power-on period ("powered": H (High) level, "not powered": L (Low) level). The latch circuit 32 is connected in parallel to the shift register 31, and in response to the latch pulse LATCH, it simultaneously and in parallel transfers and holds each bit of the data signal DATA stored in the shift register 31. This allows the data signal DATA corresponding to the next power-on period to be input to the shift register 31 even during the power-on period.

[0043] The NAND gate section 34 includes multiple NAND gates 34_1, 34_2, ..., 34_n, each corresponding to a bit of data in one line of data signal DATA. Each NAND gate in the NAND gate section 34 outputs a negative logical AND of the corresponding bit data from the data signal DATA and the inverted signal of the strobe signal STB. The strobe signal STB is a low-active signal that is energized when it is at a low level. Therefore, each NAND gate outputs a low level when the corresponding bit data from the data signal DATA is at a high level ("energized") and the strobe signal STB is at a low level. The switch section 35 includes a plurality of switches 35_1, 35_2, ..., 35_n, each corresponding to a NAND gate 34_1, 34_2, ..., 34_n. When the output of a NAND gate is at a low level, the corresponding switch turns ON. Each switch in the switch section 35 can be configured, for example, by a transistor.

[0044] With the above configuration, during the energized period when the strobe signal STB is at a low level, if the bit data corresponding to a specific dot in the data signal DATA for one line is at a high level, the corresponding switch in the switch unit 35 turns ON and energizes the heating element. The output signals of each NAND gate in the NAND gate unit 34 are examples of signals that control whether or not to energize each heating element in the heating unit 40 during the energized period. As described later, if the head controller 21 stops supplying the heating element voltage VH and / or the IC power supply voltage Vdd, the corresponding heating element will not be energized even if the switch included in the switch unit 35 is turned ON.

[0045] Furthermore, the thermal head 15 can also be operated using a logic configuration different from the one shown in Figure 4. For example, unlike the above, if we assume that the strobe signal STB is a signal that is energized when it is at a high level, then instead of the NAND gate section 34, an AND gate section consisting of multiple AND gates may be provided, and the strobe signal STB may be input directly to each AND gate without going through the inverter 33. In that case, the switch corresponding to the output of each AND gate is configured to turn ON when the output of the AND gate is at a high level. As a result, during the energized period when the strobe signal STB is at a high level, if the bit data corresponding to a specific dot in the data signal DATA for one line is at a high level, the corresponding switch in the switch section 35 turns ON and the heating element is energized.

[0046] In Figure 4, one driver IC 30 is configured to process the heat-generating elements for one line, but this is not limited to that configuration. Multiple driver ICs may be used to distribute the processing of the heat-generating elements for one line. Figure 5 is a schematic circuit diagram of a thermal head that includes multiple driver ICs. In the example shown in Figure 5, the thermal head includes six driver ICs 30_1, 30_2, ..., 30_6. Each of the driver ICs 30_1, 30_2, ..., 30_6 corresponds to a group of heating elements G1, G2, ..., G6, and performs the process of selectively energizing each heating element included in the corresponding group. For example, if one line consists of 864 dots, each driver IC is responsible for processing the group of heating elements (containing 144 heating elements) corresponding to 144 dots. The head controller 21 divides the data signal DATA for one line into data signals DATA1, DATA2, ..., DATA6, and supplies each to six driver ICs 30_1, 30_2, ..., 30_6. The operation of each driver IC is the same as that of the configuration shown in Figure 4.

[0047] If the driver ICs shown in Figures 4 and 5 are subjected to external noise, the driver ICs may enter a latch-up state. For example, if driver IC 30 enters a latch-up state, the power supply to the multiple heat-generating elements corresponding to driver IC 30 will continue, resulting in an overpower condition where each heat-generating element continues to generate heat. This can cause the printed lines to become darker than intended and ultimately lead to a disconnection. In one embodiment, the head controller 21 sets a heating element voltage supply period in the printing cycle (printing period of one line) for supplying a heating element voltage VH according to the energizing period required to perform printing. In another embodiment, the head controller 21 sets an IC power supply voltage supply period in the printing cycle for supplying an IC power supply voltage Vdd according to the energizing period. Both the heating element voltage supply period and the IC power supply voltage supply period, or either one, may be set according to the energizing period. As shown in Figure 3, the heating element voltage supply period and the IC power supply voltage supply period are set by the head controller 21 controlling switches SW1 and SW2, respectively.

[0048] Below, several specific examples in which both or either the heat-generating element voltage supply period and the IC power supply voltage supply period are set according to the energizing period will be explained with reference to Figures 6 to 11.

[0049] (A-1) First example of operation of a single strobe Figure 6 is a timing chart showing a first example of operation when the thermal head 15 is operated with a single strobe. In one embodiment, the clock pulse M_CLK used to operate the motor 14 is used as the reference pulse when performing the printing operation during the printing cycle. In this example, the printing cycle corresponds to two cycles of the clock pulse M_CLK. In the timing chart of Figure 6, the data signal DATA is supplied to the shift register 31 with reference to the clock pulse M_CLK. This data signal DATA is transferred to and held in the latch circuit 32 when the latch pulse LATCH changes to a low level. At the start of the printing cycle, the heat-generating part voltage VH is 0V. Next, in response to the latch pulse LATCH, the strobe signal STB becomes L level, and the energization period T STB The setting is configured. In response to the latch pulse LATCH, the heat-generating part voltage VH becomes voltage V1, and the heat-generating part voltage supply period T VH This is set. During the energizing period, each heating element of the heating section 40 (Figure 4) becomes energizable. Energizing period T STB In this configuration, the heating element of the heating section 40 is selectively energized according to the data signal DATA.

[0050] In the example shown in Figure 6, the heating element voltage VH is not always set to voltage V1 during the printing cycle (i.e., the heating element voltage is supplied throughout the entire period), but rather the heating element voltage supply period T VH During the power supply period T STB The settings are configured accordingly. Therefore, even if the driver IC30 enters a latch-up state, an overpower condition where power continues to be supplied to multiple heat-generating elements and they continue to generate heat is avoided.

[0051] FIG. 7 is a diagram showing an enlarged view of the operation waveforms of the strobe signal STB and the heating unit voltage VH when the strobe signal STB becomes the L level in FIG. 6. As shown in FIG. 7, during the energization period T STB is included in the heating unit voltage supply period T VH the heating unit voltage supply period T VH is set. In one embodiment, as shown in FIG. 7, the heating unit voltage supply period T STB is started a predetermined time Δt1 before the start time of the energization period T VH and the heating unit voltage supply period T STB ends a predetermined time Δt2 after the end time of the energization period T VH so that the heating unit voltage supply period T VH is set. In this case, the predetermined times Δt1 and Δt2 are set in the head controller 21 in advance. By providing the predetermined times Δt1 and Δt2, the heating unit voltage supply period T VH can be appropriately set in consideration of the delay times of the rise (0 → V1) and fall (V1 → 0) of the heating unit voltage VH. When the delay times of the rise and fall of the heating unit voltage VH are short enough to be ignored, the heating unit voltage supply period T VH may be set to be synchronized with the energization period T STB (that is, T VH = T STB ).

[0052] (A-2) Second operation example of single strobe FIG. 8 is a timing chart showing a second operation example when the thermal head 15 is operated with a single strobe. In the operation example shown in FIG. 8, the operation of the IC power supply voltage Vdd is different from that in FIG. 6. That is, instead of always setting the IC power supply voltage Vdd to the voltage V2 during the printing cycle (that is, making it the IC power supply voltage supply period throughout), the IC power supply voltage supply period T Vdd is set according to the energization period T STB . Specifically, when the strobe signal STB becomes the H level and the energization period T STB ends, or simultaneously with the end of the energization period T STBAfter the end time, the IC power supply voltage Vdd is set to 0V. In this case, the heating element voltage supply period T VH It is preferable to set the IC power supply voltage Vdd to 0V after a predetermined time. In the example shown in Figure 8, even if the driver IC 30 enters a latch-up state, the driver IC 30 is reset after the power-on period ends, resolving the malfunction, and thereafter the driver IC 30 operates normally.

[0053] (A-3) First example of operation of the multistrobe Figure 9 is a timing chart showing a first example of operation when the thermal head 15 is operated in multi-strobe mode. In a multi-strobe system, the heat generated from the heating element can be dispersed within the printing cycle, thus improving print quality compared to a single-strobe system. Figure 9 shows an example in which a power supply period T1 and multiple power supply periods T2 are provided by a strobe signal STB. In one embodiment, power supply period T1 is the main power supply period for printing, and power supply periods T2 are sub-power supply periods for preheating, etc. Unlike in Figure 9, the power-on period for the sub-unit may be set earlier than the power-on period for the main unit in the printing cycle.

[0054] In the timing chart of Figure 9, the data signal DATA includes data signal D1 corresponding to energization period T1 and data signal D2 corresponding to multiple energization periods T2. The latch pulse LATCH includes latch pulse L1 corresponding to data signal D1 and latch pulse L2 corresponding to data signal D2.

[0055] First, a data signal D1 is supplied to the shift register 31 with the clock pulse M_CLK as the reference. This data signal D1 is transferred to the latch circuit 32 and held there when the latch pulse L1 changes to a low level. Next, the strobe signal STB becomes low, and the energizing period T1 is set. During the energizing period T1, the heating elements of the heating section 40 are selectively energized according to the data signal D1. Subsequently, a data signal D2 is supplied to the shift register 31. This data signal D2 is transferred to and held in the latch circuit 32 when the latch pulse L2 changes to an L level. Then, multiple energizing periods T2 are set. During each energizing period T2, the heating elements of the heating section 40 are selectively energized according to the data signal D2.

[0056] In the example shown in Figure 9, the heating element voltage VH is not always set to voltage V1 during the printing cycle (i.e., the heating element voltage is supplied for the entire printing cycle), but rather the heating element voltage supply period T VH This is set according to the energizing periods T1 and T2. Therefore, even if the driver IC 30 enters a latch-up state, an overpower condition where the energizing of multiple heat-generating elements continues to generate heat is avoided. This effect is also achieved even if the IC power supply voltage Vdd is always supplied (a different case from Figure 9).

[0057] In one embodiment, as shown in Figure 9, the IC power supply voltage supply period T Vdd This is set according to the power supply period T2. Therefore, even if the driver IC30 enters a latch-up state, the driver IC30 is reset after the end of the power supply period T2, resolving the malfunction, and the driver IC30 will operate normally thereafter. Note that in Figure 9, the voltage supply period T of the heating element. VH and IC power supply voltage supply period T Vdd This can be set to occur after the transfer of data signals D1 and D2 is complete, or as a trigger using latch pulses L1 and L2.

[0058] Figure 10 is an enlarged view of the operating waveforms of the heating element voltage VH and IC power supply voltage Vdd when the IC power supply voltage Vdd becomes 0V in Figure 9. In one embodiment, as shown in Figure 10, the heating element voltage supply period T VH During the IC power supply voltage supply period T Vdd The timing is set so that it is included. For example, during the voltage supply period T of the heat-generating part. VH The IC power supply voltage supply period T is a predetermined time Δt3 before the start time.Vdd The heating element voltage supply period T is initiated. VH After a predetermined time Δt4 from the end time, the IC power supply voltage supply period T Vdd The IC power supply voltage supply period T is set to end. Vdd This is set. In this case, the predetermined times Δt3 and Δt4 are set in advance in the head controller 21. By providing the predetermined times Δt3 and Δt4, the situation in which the heat-generating part 40 is energized when the IC power supply voltage Vdd is not supplied to the driver IC 30 is avoided, and the driver IC 30 can be properly protected.

[0059] (A-4) Second example of operation of the multistrobe Figure 11 is a timing chart showing a second example of operation when the thermal head 15 is operated in multi-strobe mode. In the example shown in Figure 11, multiple energizing periods T1 and T2 are set within the printing cycle, similar to Figure 9, but the operation of the heating element voltage VH and IC power supply voltage Vdd differs from that in Figure 9. Specifically, the supply of the heating element voltage VH starts according to the start time of the first energizing period T1 among the multiple energizing periods, and the supply of the heating element voltage VH ends according to the end time of the last energizing period T2, so that the heating element voltage supply period T VH This is set. In this case, the heating element voltage supply period T VH This is set according to the initial energization period T1. This setting takes into account the case where the intervals between adjacent energizing periods (between energizing period T1 and energizing period T2, and between adjacent energizing periods T2) are short. That is, if the setting is as shown in Figure 9, when the intervals between adjacent energizing periods are short, the heating element voltage VH may not reach voltage V1 by the start time of the energizing period, for example, due to the delay time of the rise and fall of the heating element voltage VH. Therefore, by setting it as shown in Figure 11, it is possible to reliably supply the heating element voltage VH during the energizing period.

[0060] As explained in the operation examples in Figures 6, 8, 9, and 11, in one embodiment of the printer 1, the head controller 21 sets the heating element voltage supply period and / or IC power supply voltage supply period according to the power supply period in the printing cycle of one line. For example, the heating element voltage VH and IC power supply voltage Vdd are turned ON / OFF in accordance with the ON / OFF of the strobe signal STB that determines the power supply period. Therefore, even if the driver IC 30 of the thermal head 15 is subjected to external noise and enters a latch-up state, printing can continue while preventing the circuit of the heating element from being disconnected. In other words, the noise immunity of the thermal head 15 is improved.

[0061] As one embodiment, a control method for the thermal head 15 is disclosed. This control method includes the following steps (I) and (II). Also, as one embodiment, a program for causing a computer to perform the following steps (I) and (II) is disclosed. (I) A step of supplying a strobe signal indicating the energization period to the thermal head 15. (II) A step of setting the voltage supply period, which is the period during which the heat-generating voltage VH is supplied to the thermal head 15, according to the above energization period. The above program may be executed by one or more processors. One embodiment is a non-temporary computer-readable recording medium that stores the above program.

[0062] Next, we will describe another control method using the head controller 21. In this alternative control method, the supply of the IC power supply voltage Vdd (an example of the operating voltage) that operates the driver IC 30 to the thermal head 15 is stopped for a predetermined period of time to perform a stop process that resets the driver IC 30. Even if the driver IC 30 enters a latch-up state, the above stop process resets the driver IC 30, preventing an overpower condition where power continues to be supplied to multiple heat-generating elements, causing them to continue generating heat. The stopping process is performed by the head controller 21 controlling switches SW1 and SW2 (see Figure 3), respectively. Below, we will first explain an example of operation in which a stop process is performed at least once within the printing period of one line, in which the supply of the IC power voltage Vdd is stopped for a predetermined period to reset the driver IC 30, with reference to Figures 12 to 14.

[0063] (B-1) Example of single strobe operation Figure 12 is a timing chart showing an example of operation when the thermal head 15 is operated with a single strobe. In the example shown in Figure 12, the operation of the heating element voltage VH and the IC power supply voltage Vdd differs from that in Figure 6. That is, in Figure 12, the energizing period T STB After the above is completed, the supply of the heat-generating part voltage VH is stopped for a predetermined period, and during the period when the supply of the heat-generating part voltage VH is stopped, a stop process Ps is performed to reset the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period. In the following, the period during which the supply of the heat-generating part voltage VH and the IC power supply voltage Vdd is stopped by the stop process Ps will be referred to as the "stop period." The length of the stop period for the heat-generating part voltage VH and the length of the stop period for the IC power supply voltage Vdd may be different. In the example shown in Figure 12, even if the driver IC 30 enters a latch-up state, the heat-generating element voltage VH is stopped, thus avoiding an overpower condition where power continues to be supplied to multiple heat-generating elements, causing them to continue generating heat. In addition, the driver IC 30 is reset by stopping the supply of the IC power supply voltage Vdd, resolving any malfunction of the driver IC 30 caused by the latch-up state.

[0064] As shown in Figure 12, it is preferable to terminate the supply of the IC power supply voltage Vdd after the supply of the heat-generating part voltage VH has ended, and to start supplying the heat-generating part voltage VH after the supply of the IC power supply voltage Vdd has started. This prevents a situation in which the heat-generating part 40 is energized when the IC power supply voltage Vdd is not supplied to the driver IC 30, thereby properly protecting the driver IC 30. If the driver IC 30 has high tolerance, during the shutdown period, the supply of the IC power supply voltage Vdd may be stopped while the supply of the heat-generating part voltage VH is maintained.

[0065] (B-2) Example of multistrobe operation Figure 13 is a timing chart showing an example of operation when the thermal head 15 is operated in multi-strobe mode. In Figure 13, as in Figure 12, the printing period corresponds to two cycles of the clock pulse M_CLK. In the timing chart of Figure 13, the data signal DATA includes data signal D1 corresponding to energization period T1 and data signal D2 corresponding to multiple energization periods T2. The latch pulse LATCH includes latch pulse L1 corresponding to data signal D1 and latch pulse L2 corresponding to data signal D2.

[0066] First, a data signal D1 is supplied to the shift register 31 with the clock pulse M_CLK as the reference. This data signal D1 is transferred to the latch circuit 32 and held there when the latch pulse L1 changes to a low level. Next, the strobe signal STB becomes low, and the energizing period T1 is set. During the energizing period T1, the heating elements of the heating section 40 are selectively energized according to the data signal D1. Subsequently, a data signal D2 is supplied to the shift register 31. This data signal D2 is transferred to and held in the latch circuit 32 when the latch pulse L2 changes to an L level. Then, multiple energizing periods T2 are set. During each energizing period T2, the heating elements of the heating section 40 are selectively energized according to the data signal D2. After the last power-on period T2 ends, similar to the single-strobe case in Figure 12, the supply of the heat-generating part voltage VH is stopped for a predetermined period, and during the period when the supply of the heat-generating part voltage VH is stopped, a stop process Ps is performed to reset the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period. In other words, when multiple power-on periods are set within the printing cycle, the head controller 21 controls the system to perform the stop process Ps after the end of the last of the multiple power-on periods.

[0067] In the operation example shown in Figure 13, the same effect as in the single-strobe case in Figure 12 is obtained. That is, even if the driver IC 30 enters a latch-up state, the heating element voltage VH is stopped, thus avoiding an overpower condition in which power continues to be supplied to multiple heating elements and causes them to continue generating heat. In addition, the driver IC 30 is reset by stopping the supply of the IC power supply voltage Vdd, and malfunctions of the driver IC 30 caused by the latch-up state are resolved.

[0068] Furthermore, when adjusting the printing speed in the example operation shown in Figure 13, the operation of the printing cycle shown in Figure 13 should be repeated multiple times according to the printing speed. In other words, if the operation of the printing cycle shown in Figure 13 is used as the basic operation, when performing processing at a lower printing speed than in Figure 13, it is advisable to configure the system to repeat the basic operation shown in Figure 13 two or more times. Figure 14 shows examples of operation at high and low printing speeds. In Figure 14, the operation at high printing speeds shows the same basic operation as in the example in Figure 13. In Figure 14, when the printing speed is low, the system is configured to repeat the basic operation twice, for example. As shown in Figure 14, in the basic operation (operation at high printing speed), the stop process Ps is performed once, whereas in the case of low printing speed, the stop process Ps is performed multiple times (twice in the example in Figure 14). Since the operation at low printing speed is performed by repeating the basic operation, the control is made so that the multiple stop processes Ps are performed at equal intervals. In other words, if the stop process Ps is performed one or more times within the printing cycle, the slower (lower) the printing speed, the more stop processes Ps are provided within the printing cycle. By increasing the number of stop processes Ps within the printing cycle, there is an advantage in that the time during which the heat-generating section 40 is in an overpowered state is shortened.

[0069] In the basic operation with high printing speed, a stop period is provided within the printing cycle after the power-on period (the last power-on period in the example in Figure 13) due to the stop process Ps. When this power-on period and stop period are considered as one set period, if the basic operation is repeated multiple times within the printing cycle (when the printing speed is relatively low), the system is configured so that there are N sets of sets (where N is an integer greater than or equal to 1) within that printing cycle. This has the advantage of allowing the number of sets to be configured as an integer multiple depending on the printing speed, thus enabling efficient configuration of processing within the printing cycle.

[0070] When adjusting the printing speed, the practice of repeating the basic operation multiple times within the printing cycle, according to the printing speed, can also be applied to the operation examples shown in Figures 6, 8, 9, 11, and 12.

[0071] The system may be controlled to perform a stop process that resets the driver IC 30 by stopping the supply of the IC power supply voltage Vdd for a predetermined period of time, at least once for printing one label, or at least once for printing in one print job.

[0072] Figure 15 shows an example of operation in printer 1 where a stop process is performed after printing a label to reset the driver IC 30. In the example shown in Figure 15, at the time when the printing period for the Nth label ends, the supply of the heating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heating element voltage VH is stopped, a stop process Ps is performed in which the supply of the IC power supply voltage Vdd is stopped for a predetermined period. Similarly, a stop process Ps is performed after the printing period for the N+1th label ends. By performing the stop process Ps at least once for each label printed, even if a label cannot be printed normally due to a malfunction of the driver IC 30, the driver IC 30 is reset before the start of printing the next label, and the next label can be printed normally.

[0073] Figure 16 shows an example of operation in printer 1 where a stop process is performed after the completion of one print job to reset the driver IC 30. In the example shown in Figure 16, at the time when the printing period of the Nth print job ends, the supply of the heating element voltage VH is stopped for a predetermined period, and during the period when the supply of the heating element voltage VH is stopped, a stop process Ps is performed in which the supply of the IC power supply voltage Vdd is stopped for a predetermined period. By performing the stop process Ps at least once for printing by one print job, even if the labels are not printed correctly in a print job (for example, a print job that prints 10 labels) due to a malfunction of the driver IC 30, the driver IC 30 is reset before the start of printing by the next print job, and the next print job will be able to print correctly from the first label.

[0074] As illustrated in the operation examples in Figures 12 to 16, in one embodiment of the printer 1, the head controller 21 controls the system to perform a stop process once, which involves stopping the supply of the IC power supply voltage Vdd to the thermal head 15 for a predetermined period of time to reset the driver IC 30. By performing such a stop process, even if the driver IC 30 enters a latch-up state due to noise, the driver IC 30 is reset, resolving the malfunction of the driver IC 30 associated with the latch-up state. In other words, the noise immunity of the thermal head 15 is improved.

[0075] As shown in Figure 15, the head controller 21 may be controlled to perform the stop process Ps after printing on a label is finished and before printing on the next label begins. Performing this inter-label stop process can further improve the noise immunity of the thermal head 15. The inter-label stop process may be performed in place of, or in conjunction with, the stop process within the printing cycle shown in Figures 12 and 13.

[0076] In one embodiment, the head controller 21 may stop supplying the heat-generating element voltage VH and the IC power supply voltage Vdd when the printer cover (not shown) changes from a closed state to an open state, and start supplying the heat-generating element voltage VH and the IC power supply voltage Vdd when the printer cover changes from an open state to a closed state.

[0077] As one embodiment, a control method for the thermal head 15 is disclosed. This control method includes the following steps (I) and (II). Also, as one embodiment, a program for causing a computer to perform the following steps (I) and (II) is disclosed. (I) A step of supplying a strobe signal indicating the energization period to the thermal head 15. (II) A step of controlling the driver IC 30 to perform a stop process that resets the driver IC 30 by stopping the supply of the operating voltage that operates the driver IC 30 for a predetermined period of time. The above program may be executed by one or more processors. One embodiment is a non-temporary computer-readable recording medium that stores the above program.

[0078] Although several embodiments of the printer, thermal head control method, and program of the present invention have been described above, the present invention is not limited to the above embodiments. Furthermore, the above embodiments and technical matters can be combined as appropriate without departing from the spirit of the present invention. [Explanation of Symbols]

[0079] 1…Printer 5…Head unit 9…Roll paper storage room 10... Platen roller 11…Control Unit 12…Ink ribbon section 12a...Ribbon supply unit, 12b...Ribbon winding unit, 121,122...Ribbon rollers 13…Drive circuit 14…motor 15…Thermal head 16...Power supply section 18…Storage 20…Issuing Account 21…Head controller 22...Memory 23…Heat generation section Power generation section 24...IC power generation section 30, 30_1~30_6… Driver ICs 31... Shift register 32…Latch Circuit 33…Inverter 34...NAND gate section, 34_1, 34_2, ..., 34_n...NAND gates 35... Switch section, 35_1, 35_2, ..., 35_n... Switch 40...heating element, 40_1, 40_2, ..., 40_n...heating element CP…Continuous paper G1~G6... Group of heating elements R... Roll paper

Claims

1. A heating section having multiple heating elements arranged in a line, A thermal head having a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line, When the voltage used to energize the heating element is defined as the heating element voltage, a control unit sets the voltage supply period, which is the period during which the heating element voltage is supplied to the thermal head, according to the energization period. A printer equipped with [a specific feature / feature].

2. The control unit sets the voltage supply period such that the energizing period is included in the voltage supply period. The printer according to claim 1.

3. The control unit sets the voltage supply period such that the voltage supply period starts a predetermined time before the start time of the energizing period and ends a predetermined time after the end time of the energizing period. The printer according to claim 1.

4. The control unit sets the voltage supply period so that the voltage supply period is synchronized with the energization period. The printer according to claim 1.

5. The control unit sets the voltage supply period such that, if the power supply period is set multiple times within the printing period of one line, the supply of the heating element voltage starts according to the start time of the first power supply period among the multiple power supply periods, and the supply of the heating element voltage ends according to the end time of the last power supply period. The printer according to claim 1.

6. The control unit, When starting to drive the heat-generating part, the supply of the circuit voltage that operates the drive circuit is started first, and then the supply of the heat-generating part voltage is started. When terminating the operation of the heat-generating part, the supply of voltage to the heat-generating part is terminated first, and then the supply of voltage to the circuit is terminated. The printer according to claim 1.

7. The control unit controls the drive circuit to perform a stop process that resets the drive circuit by stopping the supply of the operating voltage for operating the drive circuit for a predetermined period of time. A printer according to any one of claims 1 to 6.

8. A control method for a thermal head, The thermal head is, A heating section having multiple heating elements arranged in a line, The device includes a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line. The control method described above is The steps include supplying a signal indicating the energization period to the thermal head, The step includes setting a voltage supply period, which is the period during which the voltage used to energize the heating element is supplied to the thermal head, according to the energization period, when the voltage used to energize the heating element is defined as the heating element voltage. A control method for thermal heads.

9. A program for a printer having a thermal head that causes a computer to perform a predetermined procedure, The thermal head is, A heating section having multiple heating elements arranged in a line, The device includes a drive circuit that drives the heating element to control whether or not to energize each heating element of the heating element during the energizing period, based on a signal indicating the energizing period of the heating element during the printing period of one line. The aforementioned prescribed procedure is, A procedure for supplying a signal indicating the energization period to the thermal head, The procedure includes setting the voltage supply period, which is the period during which the voltage used to energize the heating element is supplied to the thermal head, according to the energization period, when the voltage used to energize the heating element is defined as the heating element voltage. program.

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