Image forming apparatus

Abstract

To provide an image forming apparatus equipped with a thermal head that can detect the supply status of the digital operating voltage Vdd. [Solution] The image forming apparatus of this embodiment includes a thermal head equipped with a heating element and a driver IC (Integrated Circuit) that has a logic circuit for controlling the operation of the heating element, and a control unit that determines whether or not a digital operating voltage Vdd capable of driving the logic circuit is applied to the logic circuit.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an image forming apparatus. [Background Art]

[0002] Conventionally, image forming apparatuses equipped with a thermal head, such as thermal printers and portable printers, are known.

[0003] Conventionally, there has been no way to confirm whether the digital operating voltage Vdd for a logic circuit in a driver IC (Integrated Circuit) mounted on a thermal head is correctly supplied. As a result, there have been cases where the head driving voltage is applied when the digital operating voltage Vdd is not correctly supplied, causing the head to fail. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2024-154640 [Summary of the Invention] [Problems to be Solved by the Invention]

[0005] A problem to be solved by the present invention is to provide an image forming apparatus including a thermal head that can detect the supply state of the digital operating voltage Vdd. [Means for Solving the Problem]

[0006] The image forming apparatus according to an embodiment comprises: a thermal head including a heating element and a driver IC (Integrated Circuit) including a logic circuit that controls the operation of the heating element; and a control unit that determines whether or not the digital operating voltage Vdd capable of driving the logic circuit is applied to the logic circuit. [Brief Description of the Drawings]

[0007] [Figure 1] An external view showing the configuration of the image forming apparatus according to the embodiment. [Figure 2] A first side view showing an example of the internal configuration of an image forming apparatus according to an embodiment. [Figure 3] A second side view showing an example of the internal configuration of an image forming apparatus according to an embodiment. [Figure 4] A block diagram showing an example of the system configuration of an image forming apparatus according to an embodiment. [Figure 5] A circuit diagram showing an example of a circuit related to the control of a thermal head in an embodiment. [Figure 6] A flowchart showing an example of the processing flow performed by the image forming apparatus in the embodiment. [Figure 7] A figure showing the first example of the position of the SVdd node in a modified example. [Figure 8] A figure showing a second example of the position of the SVdd node in a modified example. [Modes for carrying out the invention]

[0008] The image forming apparatus of the embodiment will be described below with reference to the drawings. Figure 1 is an external view showing an example of the configuration of an image forming apparatus 100 according to the embodiment. Note that the image forming apparatus 100 may be any image forming apparatus equipped with a thermal head, such as a thermal printer or a portable printer.

[0009] The image forming apparatus 100 prints a predetermined image onto a label and issues the label with the printed image. The image forming apparatus 100 has a high-speed printing function. The high-speed printing function is a function that allows printing at a printing speed (second printing speed) that is faster than the printing speed of normal printing (first printing speed). In other words, with the high-speed printing function, the label transport speed at low speed is faster than the transport speed at low speed in normal printing. As shown in Figure 1, the image forming apparatus 100 includes a display unit 200, an operation unit 300, and an output port 350.

[0010] The display unit 200 is an image display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The display unit 200 operates as an output interface and displays characters and images. The display unit 200 may also operate as an input interface and accept instructions from the user.

[0011] The control unit 300 is configured using existing input devices such as buttons. The control unit 300 is operated by the user when inputting user instructions to the image forming apparatus 100. For example, the control unit 300 receives input of an instruction to start printing. For example, the control unit 300 receives input from the user of an instruction for normal printing or an instruction for high-speed printing.

[0012] The discharge port 350 discharges the label on which the image is printed.

[0013] Figures 2 and 3 are side views showing an example of the internal configuration of the image forming apparatus 100 according to the embodiment. Figures 2 and 3 show the internal configuration of the image forming apparatus 100 viewed from different sides. As shown in Figures 2 and 3, the image forming apparatus 100 has a first chamber Sa and a second chamber Sb inside the housing. The first chamber Sa and the second chamber Sb are separated by a vertical wall Wa. First, the configuration inside the first chamber Sa will be explained using Figure 2.

[0014] The first chamber Sa is equipped with a label roll paper 1, a pinch roller Xa, a transport roller Za, a paper detection sensor 51, a paper detection sensor 52, an ink ribbon 6, an ink ribbon supply shaft 7, an ink ribbon winding shaft 8, a platen roller PR, a print head 9, a thermal head 10, and a peeling unit 11.

[0015] Label roll paper 1 is a label paper composed of multiple labels attached to a strip-shaped backing. Label roll paper 1 is wound into a roll to form a roll section 2. Label roll paper 1 is pulled out from the roll section 2 and transported to the transport path 3.

[0016] Further, the label roll paper 1 indicated by the solid line in FIG. 2 shows a label roll paper in a state where the diameter of the roll portion 2 is relatively large. On the other hand, the alternate long and short dash line La shown in FIG. 2 indicates the position of the label roll paper in a state where the diameter of the roll portion 2 is relatively reduced. Further, the arrow Ya shown in FIG. 2 indicates the feeding direction of the label roll paper 1.

[0017] The pinch roller Xa is disposed opposite to the conveyance roller Za. The conveyance roller Za is driven by a motor (not shown). The pinch roller Xa and the conveyance roller Za convey the label roll paper 1, which is a backing sheet with labels attached thereon.

[0018] The paper detection sensor 51 is an irradiation unit that irradiates light onto the conveyance path 3. The paper detection sensor 52 is a light receiving unit that receives light irradiated from the paper detection sensor 51. The paper detection sensor 52 detects a voltage level corresponding to the amount of received light. The paper detection sensor 52 detects a label according to the detected voltage level. When the detected voltage level is less than a threshold value, the paper detection sensor 52 detects a label. On the other hand, when the detected voltage level is equal to or higher than the threshold value, the paper detection sensor 52 does not detect a label. The paper detection sensor 52 outputs a detection result to the control device 400. The detection result includes information on whether a label is detected. The paper detection sensor 52 outputs the detection result periodically or at preset timings. The paper detection sensor 51 and the paper detection sensor 52 are, for example, transmission sensors. In addition, in the following description, the paper detection sensor 51 and the paper detection sensor 52 will be referred to as the paper detection sensor 5 unless particularly distinguished.

[0019] The ink ribbon 6 is a tape-shaped ink cartridge. The ink ribbon 6, together with the label roll paper 1, is sandwiched between the thermal head 10 and the platen roller PR. The ink of the ink ribbon 6 is transferred onto the label roll paper 1 by heat applied from the thermal head 10.

[0020] The ink ribbon supply shaft 7 is a shaft that feeds out the ink ribbon 6. The supply shaft 7 is provided on the feed-out side of the ink ribbon 6. A roll portion 71 of the ink ribbon 6 is set on the supply shaft 7. Hereinafter, the roll portion 71 of the ink ribbon 6 is referred to as a ribbon roll. The supply shaft 7 is rotationally driven by a rotational drive mechanism including a DC motor, a gear, a belt, and the like.

[0021] The ink ribbon take-up shaft 8 is a shaft that takes up the ink ribbon 6. The take-up shaft 8 is provided on the take-up side of the ink ribbon 6. The take-up shaft 8 is rotationally driven by a rotational drive mechanism including a DC motor, a gear, a belt, and the like. The rotation of the take-up shaft 8 causes the ink ribbon 6 to be taken up onto the take-up shaft 8 and pulled out from the ribbon roll.

[0022] The platen roller PR is rotationally driven by an unillustrated rotational drive mechanism including an unillustrated motor such as a stepping motor, a gear, a belt, and the like. The platen roller PR is disposed opposite to the thermal head 10 provided in the print head 9.

[0023] The print head 9 comprises the thermal head 10. The print head 9 presses the label roll paper 1, which is conveyed between the thermal head 10 and the platen roller PR, against the platen roller PR.

[0024] The thermal head 10 is disposed above the platen roller PR and opposite to the platen roller PR. The thermal head 10 uses the ink ribbon 6 to perform printing on a label attached to the backing sheet of the conveyed label roll paper 1. The thermal head 10 has a plurality of heating elements arranged in a line. The heating elements generate heat when power is applied thereto. The thermal head 10 causes the heating elements to generate heat by selectively applying power to the plurality of heating elements. The thermal head 10 melts or sublimates the ink of the ink ribbon 6 by the heat generated from the heating elements, and transfers the ink to the label to perform printing.

[0025] The peeling unit 11 is a device that peels labels from the label roll paper 1 that has been transported along the transport path 3. The peeling unit 11 includes a peeling bar 12, a peeling sensor 131, a peeling sensor 132, an outlet 14, an outlet 15, a pinch roller Xb, and a transport roller Rb.

[0026] The peeling bar 12 is flat and positioned in front of the thermal head 10, that is, basically perpendicular to the direction in which the label roll paper 1 is fed out.

[0027] The peel sensor 131 is an illumination unit that irradiates light onto the transport path 3. The peel sensor 132 is a light receiving unit that receives the light irradiated from the peel sensor 131. The peel sensor 132 detects a voltage level corresponding to the amount of light received. The peel sensor 132 detects a label according to the detected voltage level. If the detected voltage level is below a threshold, the peel sensor 132 detects a label.

[0028] On the other hand, if the detected voltage level is above a threshold, the peel sensor 132 does not detect the label. The peel sensor 132 outputs the detection result to the control device 400. The detection result includes whether or not the label was detected. The peel sensor 132 outputs the detection result periodically or at a preset timing. The peel sensors 131 and 132 are, for example, transmissive sensors. In the following description, unless otherwise specified, the peel sensors 131 and 132 will be referred to as peel sensor 13.

[0029] The discharge port 14 is the discharge port through which the backing paper 16, from which the label has been peeled off by the peeling bar 12, is discharged.

[0030] The pinch roller Xb is positioned opposite the conveyor roller Rb.

[0031] The transport roller Rb is driven by a motor (not shown). The pinch roller Xb and the transport roller Rb transport the backing paper 16 from which the label has been peeled off.

[0032] Next, we will explain the configuration of the second chamber Sb using Figure 3. As shown in Figure 3, the second chamber Sb is equipped with a control device 400 and a power supply unit 500.

[0033] The control device 400 controls the operation of the entire image forming apparatus 100. For example, the control device 400 controls the transport of the label roll paper 1 by controlling the motors of the transport roller Za, transport roller Rb, and platen roller PR. More specifically, the control device 400 controls the transport speed of the label roll paper 1 by controlling the motors of the transport roller Za, transport roller Rb, and platen roller PR. The control device 400 also controls the thermal head 10 to print the data to be printed (hereinafter referred to as "print data") onto the labels on the backing of the label roll paper 1.

[0034] The Power Supply Unit (PSU) 500 supplies power to the image forming apparatus 100. The dashed line 23 represents the path through which data passes between the display unit 200 and the control unit 400, both of which are provided in the image forming apparatus 100. The dashed line 24 represents the path through which data passes between the control unit 400 and the operation unit 300.

[0035] Figure 4 is a block diagram showing an example of the system configuration of the image forming apparatus 100 according to the embodiment. The image forming apparatus 100 includes a control unit 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, a motor driver 404, a head control circuit 405, a wire breakage check circuit 406, a power switch 407, an LED (Light Emitting Diode) 408, a communication I / F 409, a transmission sensor 410, and a thermal head 10. Each functional unit is connected via a bus 401a.

[0036] The control unit 401 includes a processor 91 such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), or NPU (Neural Network Processing Unit) connected by a bus, and memory 92, and executes programs.

[0037] The control unit 401 controls each functional part of the image forming apparatus 100 by executing the program. The control unit 401 also stores information about predetermined distances. This information about predetermined distances includes the distance from the transmission sensor 410 to the thermal head 10 and the distance between labels.

[0038] ROM402 is a read-only memory that pre-stores a program for operating the image forming apparatus 100.

[0039] RAM403 is a read / write memory that stores various types of information. The program read from ROM402 is loaded into RAM403. RAM403 also stores various types of data generated by program execution (such as print data).

[0040] The motor driver 404 drives a motor (not shown) for transporting paper. In the image forming apparatus 100, the paper is a label attached to a strip-shaped backing. The motor driver 404 controls the paper transport speed by controlling the torque of the motor.

[0041] The head control circuit 405 controls the power supply to the thermal head 10.

[0042] The disconnection check circuit 406 checks for disconnections in the heating elements that make up the thermal head 10. The head control circuit 405 is connected to the disconnection check circuit 406.

[0043] The power switch 407 is turned on and off mechanically and softly. Softly means that it is turned on and off by a control signal of the image forming apparatus 100.

[0044] LED408 illuminates in different colors depending on the voltage state of the secondary battery (not shown), under the control of the control unit 401.

[0045] Communication I / F9 is an interface for communication between the image forming apparatus 100 and other devices different from the image forming apparatus 100. These other devices may be, for example, a host computer (not shown). Other devices may also be a speaker (not shown) or a storage device (not shown).

[0046] The transmission sensor 410 detects paper. For example, the transmission sensor 410 detects the label edge of the paper. The transmission sensor 410 consists of an irradiating unit and a light receiving unit. The irradiating unit emits light. The light receiving unit receives the light emitted from the irradiating unit and detects a voltage level corresponding to the amount of light received. The light receiving unit then detects the label edge of the paper according to the detected voltage level. Specifically, if the detected voltage level is below a threshold, the light receiving unit detects the label edge of the paper.

[0047] On the other hand, if the detected voltage level is above a threshold, the light receiving unit does not detect the label edge of the paper. The transmission sensor 410 outputs the detection result to the control unit 401. The detection result includes whether or not the label edge was detected. The transmission sensor 410 outputs the detection result periodically or at a preset timing.

[0048] Figure 5 is a circuit diagram showing an example of a circuit related to the control of the thermal head 10 in an embodiment. Figure 5 shows the thermal head 10 and the printer control board 600. The printer control board 600 includes a head control circuit 405, a control unit 401, a power supply unit 500, and a connector 601.

[0049] Connector 601 is one of a pair of components that electrically connect the printer control board 600 and the thermal head 10, and is the one attached to the printer control board 600. Therefore, connector 601 is a so-called connector, and in the image forming apparatus 100, it is the connector attached to the printer control board 600.

[0050] The power output from the power supply unit 500 flows into the thermal head 10 via connector 601 and connector 101. Connector 101 is one of a pair of components that electrically connect the printer control board 600 and the thermal head 10, and is attached to the thermal head 10. Therefore, connector 101 is a so-called connector, and in the image forming apparatus 100, it is the connector attached to the thermal head 10. Connector 601 and connector 101 form a pair.

[0051] The signals flowing between the head control circuit 405 and the thermal head 10 flow from one to the other or from one to the other via connectors 601 and 101.

[0052] The thermal head 10 includes one or more driver ICs 102. The driver ICs 102 are integrated circuits that control the operation of the heating element. A digital operating voltage Vdd is applied to the driver ICs 102. The application of the digital operating voltage Vdd to the driver ICs 102 is performed by the power supply unit 500. Therefore, at least a portion of the power output by the power supply unit 500 is supplied to the driver ICs 102 as power for the digital operating voltage Vdd.

[0053] The driver IC 102 includes a logic circuit 121. The digital operating voltage Vdd applied to the driver IC 102 by the power supply unit 500 is specifically applied to the logic circuit 121. The logic circuit 121 is a logic circuit that controls the operation of the heating element.

[0054] In Figure 5, the power of the voltage VH output from the power supply unit 500 is defined as the power used to drive the heating element. This voltage VH is applied to the driver IC 102.

[0055] The DATA signal, CLOCK signal, LATCH signal, and STROBE signal flow between the head control circuit 405 and the logic circuit 121. The DATA signal is a signal transmitted from the head control circuit 405 to the logic circuit 121 and represents an instruction to the head control circuit 405. The CLOCK signal is a signal indicating the synchronization clock. The CLOCK signal is used to send the DATA signal.

[0056] The LATCH signal indicates the end of the CLOCK signal and the start of the STROBE signal. The STROBE signal indicates whether or not power is supplied to the heating element. The digital operating voltage Vdd is also used for these signals.

[0057] The control unit 401 and the logic circuit 121 are connected by a wire. More specifically, the wire connecting the power supply unit 500 and the logic circuit 121 (hereinafter referred to as the "Vdd wire") is connected to the control unit 401 at the SVdd node. Even more specifically, the control unit 401 is connected to the logic circuit 121 via a wire connecting the control unit 401 and the SVdd node (hereinafter referred to as the "SVdd wire").

[0058] An SVdd node is a predetermined position on the Vdd line. The SVdd node may be, for example, a predetermined position on the Vdd line that is not at the end. The end of the Vdd line is the location of the power supply unit 500 or the logic circuit 121. Node Pa in the example in Figure 5 is an example of an SVdd node.

[0059] The control unit 401 receives signals flowing through the SVdd line (hereinafter referred to as "SVdd signals").

[0060] <<Determination by Control Unit 401>> The control unit 401 performs a determination process. The determination process determines whether a digital operating voltage Vdd capable of driving the logic circuit 121 is applied to the logic circuit 121 based on the SVdd signal. For example, in the determination process, the control unit 401 determines whether a digital operating voltage Vdd capable of driving the logic circuit 121 is applied to the logic circuit 121 based on the signal level of the SVdd signal.

[0061] For example, if the signal level of the SVdd signal is above a predetermined strength, the control unit 401 determines that a digital operating voltage Vdd capable of driving the logic circuit 121 is applied to the logic circuit 121. More specifically, in the case of the circuit configuration shown in Figure 5, this determination means that a digital operating voltage Vdd capable of driving all logic circuits 121 provided by the thermal head 10 is applied.

[0062] On the other hand, if the signal level of the SVdd signal is below a predetermined strength, the control unit 401 determines that no digital operating voltage Vdd capable of driving the logic circuit 121 is applied to the logic circuit 121. Several examples of the more specific content of this determination are shown below. In the case of the circuit configuration shown in Figure 5, this determination more specifically means that no drivable digital operating voltage Vdd is applied to at least a portion of the logic circuit 121 provided by the thermal head 10.

[0063] In the example shown in Figure 5, the thermal head 10 is equipped with a buffer 123. The buffer 123 converts the Vdd power supply into a detection signal, which has the effect of enabling the addition of a pull-down circuit to the PPAS signal.

[0064] The provision of buffers 123 will be explained. For example, if Vdd power is not supplied and the input to the buffer is undefined, the printer may not be able to detect the potential. In this case, if a pull-down resistor is attached to the PPAS signal, the output of the buffer will be at GND level, and the abnormality can be detected. If it is connected directly to the Vdd power, it will be at an intermediate potential. Under normal conditions, the buffer output is the output of the CMOS circuit and will be 5V (H level), and even if there is a pull-down resistor circuit (e.g., 10kΩ), the PPAS detection signal will be H, and it will be possible to detect that it is normal.

[0065] In the example shown in Figure 5, node Pa is located on the thermal head 10. Thus, the SVdd node may be located on the thermal head 10, for example.

[0066] Figure 6 is a flowchart showing an example of the processing flow performed by the image forming apparatus 100 in the embodiment. Here, we will explain as an example a determination process that determines whether or not a digital operating voltage Vdd capable of driving the logic circuit 121 is applied based on whether or not the signal level of the SVdd signal is above a predetermined strength.

[0067] The control unit 401 acquires the SVdd signal (ACT101). Next, based on the acquired SVdd signal, the control unit 401 determines whether the signal level of the SVdd signal is above a predetermined strength (ACT102).

[0068] If the signal level of the SVdd signal is above a predetermined strength (ACT102: YES), the control unit 401 determines that the digital operating voltage Vdd is being supplied correctly (ACT103). That is, the control unit 401 determines that a digital operating voltage Vdd capable of driving the logic circuit 121 is being applied to the logic circuit 121.

[0069] On the other hand, if the signal level of the SVdd signal is below a predetermined strength (ACT102:NO), the control unit 401 determines that the digital operating voltage Vdd is not being supplied correctly (ACT104). In other words, the control unit 401 determines that the digital operating voltage Vdd capable of driving the logic circuit 121 is not being applied to the logic circuit 121.

[0070] Next, the control unit 401 outputs the result of the determination obtained in step S103 or step S104 to a predetermined output destination that is communicably connected to the control unit 401 and controllable by the control unit 401 (ACT105). The predetermined output destination is, for example, the display unit 200. The control unit 401 may control the operation of the display unit 200 to display the result of the determination obtained in step S103 or step S104 on the display unit 200.

[0071] The predetermined output destination may be connected to the control unit 401 via, for example, the communication interface 9. Therefore, the predetermined output destination may be, for example, a host computer, a speaker, or a storage device. The speaker reads out the judgment result aloud when the control unit 401 outputs the judgment result. The storage device stores the judgment result when the control unit 401 outputs the judgment result.

[0072] The image forming apparatus 100 configured in this way includes a thermal head 10 and a control unit 401. The thermal head 10 includes a heating element and a driver IC 102 equipped with a logic circuit 121 that controls the operation of the heating element. The control unit 401 determines whether or not a digital operating voltage Vdd capable of driving the logic circuit 121 is applied to the logic circuit 121. Therefore, the image forming apparatus 100 is an image forming apparatus equipped with a thermal head that can detect the supply status of the digital operating voltage Vdd.

[0073] (modified version) If the thermal head 10 includes multiple logic circuits 121, the control unit 401 may perform a determination for each logic circuit 121 to be determined. The determination target may be a predetermined part or all of the multiple logic circuits 121 included in the thermal head 10.

[0074] If there are multiple logic circuits 121 to be judged, judgment for each logic circuit 121 is possible, for example, if the Vdd lines connecting the power supply unit 500 and the logic circuit to be judged are different for each logic circuit and do not have any common parts. In this case, there is an SVdd node for each logic circuit to be judged, and the SVdd lines are also different for each SVdd node and do not have any common parts.

[0075] The case where there is only one object to be judged will also be described. In this case, judgment for each logic circuit 121 to be judged is possible, for example, if the Vdd line connecting the power supply unit 500 and the object to be judged is a different Vdd line from the other logic circuits 121 and they do not have any common parts. In this case, the Vdd lines connecting the other logic circuits 121 and the power supply unit 500 may be different for each other logic circuit 121 and have no common parts, or they may have common parts.

[0076] Figure 7 shows a first example of the position of the SVdd node in a modified example. For simplicity of explanation, in the example of Figure 7, there are three logic circuits 121 connected to the power supply unit 500. In the example of Figure 7, three logic circuits 121-1 to 121-3 are connected to the power supply unit 500, but the Vdd lines connecting each logic circuit 121 to the power supply unit 500 are different and do not have a common part.

[0077] Furthermore, there are SVdd nodes for each conductor. Specifically, these are SVdd node Pc-a, SVdd node Pc-b, and SVdd node Pc-c. SVdd node Pc-a is an SVdd node located on the Vdd line connecting logic circuit 121-1 and power supply unit 500. SVdd node Pc-b is an SVdd node located on the Vdd line connecting logic circuit 121-2 and power supply unit 500. SVdd node Pc-c is an SVdd node located on the Vdd line connecting logic circuit 121-3 and power supply unit 500.

[0078] Furthermore, each of the SVdd nodes Pc-a to Pc-c is connected to the control unit 401 by a wire. In this case, the control unit 401 performs a determination process for each SVdd signal flowing through each SVdd line. As a result, the control unit 401 determines whether or not a digital operating voltage Vdd capable of driving the logic circuit 121-1 is applied to the logic circuit 121-1.

[0079] Furthermore, the control unit 401 determines whether a digital operating voltage Vdd capable of driving logic circuit 121-2 is applied to logic circuit 121-2. The control unit 401 also determines whether a digital operating voltage Vdd capable of driving logic circuit 121-3 is applied to logic circuit 121-3.

[0080] In the example shown in Figure 7, if, for example, the only circuit to be judged is logic circuit 121-1, the control unit 401 does not need to perform judgment processing on logic circuits 121-2 and 121-3.

[0081] Note that in Figure 7, conductors Lb, Lc, and Ld are all examples of Vdd wires. Also, conductors Le, Lf, and Lg are all examples of SVdd wires.

[0082] Figure 8 shows a second example of the position of the SVdd node in a modified example. In the example in Figure 8, for the sake of simplicity, there are three logic circuits 121 connected to the power supply unit 500. In the example in Figure 8, three logic circuits 121-1 to 121-3 are connected to the power supply unit 500. The Vdd line connecting logic circuit 121-1 to the power supply unit 500 is not a conductor that shares a common part with the Vdd lines connecting the other logic circuits 121 to the power supply unit 500.

[0083] On the other hand, the Vdd line connecting the logic circuit 121-2 and the power supply unit 500 has a common section with the Vdd line connecting the logic circuit 121-2 and the power supply unit 500. There are two SVdd nodes: SVdd node Pc-a and SVdd node Pc-d.

[0084] SVdd node Pc-d is an SVdd node on the Vdd line connecting logic circuits 121-2 and 121-3 to the power supply unit 500. Each SVdd node is connected to the control unit 401 by an SVdd line.

[0085] Therefore, in this case, the control unit 401 receives SVdd signals flowing through the SVdd line connecting SVdd node Pc-a and the control unit 401, and SVdd signals flowing through the SVdd line connecting SVdd node Pc-d and the control unit 401. The control unit 401 performs a determination process for each SVdd signal.

[0086] As a result, the control unit 401 determines whether a digital operating voltage Vdd capable of driving logic circuit 121-1 is applied to logic circuit 121-1. The control unit 401 also determines whether a digital operating voltage Vdd capable of driving either logic circuit 121-2 or logic circuit 121-3 is applied to both logic circuit 121-2 and logic circuit 121-3.

[0087] In the example shown in Figure 8, if, for example, the only circuit to be judged is logic circuit 121-1, the control unit 401 does not need to perform judgment processing on logic circuits 121-2 and 121-3.

[0088] Note that in the example in Figure 8, wire Lh is an example of a Vdd wire, and wire Li is an example of an SVdd wire.

[0089] Furthermore, if the thermal head 10 has multiple logic circuits 121, power may be supplied to each logic circuit 121 by branching the signal flowing from the power supply unit 500 to each logic circuit 121. The signal flowing from the power supply unit 500 is the signal flowing through the Vdd line. The circuits in Figure 5 and Figure 8, which consist of logic circuits 121-2 and 121-3 and the power supply unit 500, are examples of circuits in which power is supplied by such branching.

[0090] In such cases, the SVdd node may be located before the signal branching along the Vdd line. For example, in the example in Figure 5, node Pa is located between branch point Pb and the power supply unit 500. Therefore, in the example in Figure 5, the SVdd node is located before the signal branching along the Vdd line. In the example in Figure 8, node Pc-d may also be located between branch point Pd and the power supply unit 500. Branch point Pd is a branching point on the conductor connecting the power supply unit 500 to logic circuits 121-2 and 121-3, where the signal flowing out of the power supply unit 500 branches into logic circuits 121-2 and 121-3.

[0091] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0092] 100…Image forming apparatus, 200…Display unit, 300…Operation unit, 350…Outlet, 1…Label roll paper, 2…Roll section, 3…Conveyor path, 4…Roll holding shaft, 51, 52…Paper detection sensor, 6…Ink ribbon, 7…Ink ribbon supply shaft, 71…Roll section, 8…Ink ribbon winding shaft, 9…Print head, 10…Thermal head, 11…Peeling unit, 12…Peeling bar, 131, 132…Peeling sensor, 14…Outlet 15…Outlet, 16…Backing board, Wa…Vertical wall, 401…Control unit, 402…ROM, 403…RAM, 404…Motor driver, 405…Head control circuit, 406…Disconnection check circuit, 407…Power switch, 408…LED, Communication I / F…409, 410…Transmission sensor, 101…Connector, 102…Driver IC, 500…Power supply unit, 600…Printer control board, 91…Processor, 92…Memory

Claims

1. A thermal head comprising a heating element and a driver IC (Integrated Circuit) equipped with a logic circuit for controlling the operation of the heating element, A control unit that determines whether or not a digital operating voltage Vdd capable of driving the logic circuit is applied to the logic circuit, An image forming apparatus equipped with the following features.

2. The control unit performs the determination based on the SVdd signal, which is a signal flowing through a conductor connecting the control unit to an SVdd node, which is a predetermined position on a conductor connecting the power supply that outputs power to the logic circuit and the logic circuit. The image forming apparatus according to claim 1.

3. The control unit performs the determination based on the signal level of the SVdd signal. The image forming apparatus according to claim 2.

4. The thermal head comprises a plurality of the logic circuits, The control unit performs the determination for each logic circuit that is subject to determination. The image forming apparatus according to claim 1.

5. The thermal head comprises a plurality of the logic circuits, Each of the aforementioned logic circuits is supplied with power by a signal flowing out from a power supply that outputs power, which is then branched out to each of the aforementioned logic circuits. The SVdd node, which is a predetermined position on the conductor connecting the power supply that outputs power to the logic circuit and the logic circuit, is located before the branching of the signal. The image forming apparatus according to claim 1.

Images