JP2022070732A - Image forming device and control method of the same - Google Patents

Abstract

To provide an image forming device that can estimate a capacity of a battery without installing a resistor for measurement therein.SOLUTION: A printer (an image forming device) comprises: a control part 200; a battery 203 that is used as a power source for operating the printer; and a thermal head 103 that forms an image on a recording medium being conveyed by thermal transfer. The control part 200 connects the battery 203 to the thermal head 103, and measures currents flowing into the thermal head 103. The control part 200 obtains an internal resistance value Rb of the battery 203 on the basis of a measured value of the currents obtained through the measurement, and estimates a capacity of the battery 203 on the basis of the internal resistance value.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus and a control method thereof.

A secondary battery used in an electronic device such as an image forming apparatus usually has an increased internal resistance value due to performance deterioration due to repeated charging. As a result, it becomes difficult to correctly detect the capacity of the battery. Therefore, for example, in Patent Document 1, there is a technique of measuring the internal resistance value of a battery by passing a current through a resistor (dummy load resistance) provided for measurement and determining the remaining amount of the battery based on the internal resistance value. Proposed.

Japanese Unexamined Patent Publication No. 2018-152976

However, in the conventional technique as described above, it is necessary to provide a dummy load resistor for measuring the internal resistance value of the battery, which leads to an increase in size and complexity of the device.

Therefore, an object of the present invention is to provide an image forming apparatus capable of estimating the capacity of a battery without providing a resistance for measurement.

The image forming apparatus according to one aspect of the present invention includes a battery used as a power source for the image forming apparatus, an image forming means having a thermal head for forming an image by thermal transfer on the surface of a recording medium to be conveyed, and the battery. And the thermal head are connected to each other, and the internal resistance value of the battery is acquired based on the measuring means for measuring the current flowing through the thermal head and the measured value of the current obtained by the measurement by the measuring means. It is characterized by comprising a first estimation means for estimating the capacity of the battery based on the internal resistance value.

According to the present invention, it is possible to provide an image forming apparatus capable of estimating the capacity of a battery without providing a resistance for measurement.

Cross-sectional view showing a schematic hardware configuration example of a printer Block diagram showing an example of printer control configuration The figure which shows an example of the connection structure of a voltage measuring part. The figure which shows the structural example of a thermal head The figure which shows an example of the SOC-OCV characteristic of a battery. The figure which shows an example of the cycle life characteristic of a battery A diagram showing an example of printer operation when a print job is executed. A diagram showing an example of printer operation when a print job is executed. A flowchart showing the procedure of printing processing according to a print job. A flowchart showing the procedure of the battery capacity estimation process (S102). A flowchart showing the procedure of the power consumption estimation process (S103). A flowchart showing the procedure of the print determination process (S104). Flow chart showing the procedure for controlling the use of resistors The figure which shows an example of a resistance table

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. In addition, the same or similar configuration will be given the same reference number, and duplicated explanations will be omitted.

<Image forming device>
FIG. 1 is a cross-sectional view showing a schematic hardware configuration example of a printer 100, which is an example of an image forming apparatus according to an embodiment of the present invention. The printer 100 includes an operation unit 102, a thermal head 103, a medium heater 104, an ink ribbon cartridge 105, a transfer roller pair 106, a transfer roller 107, a medium sensor 108, a tip sensor 109, a platen roller 112, and a cutting unit 114. are doing. The operation unit 102 has a display unit 121 for displaying information to the user and an input unit 122 for receiving an instruction from the user. The platen roller 112 is arranged at a position facing the thermal head 103.

The printer 100 includes an image forming unit having a thermal head 103 that forms an image by thermal transfer on a recording medium to be conveyed. In the present embodiment, the thermal head 103 forms an image on a tubular recording medium M that is inserted from the insertion slot 110 and conveyed along the transport path. The tubular recording medium M is manually inserted by the user from the insertion port 110 of the transport path. The tip of the recording medium M passes through the inside of the cylindrical medium heater 104, is abutted against the transport roller pair 106, and is sandwiched by the transport roller pair 106. The medium heater 104 is a heater that heats the surface (recording surface) of the recording medium M in a low temperature environment.

The medium sensor 108 is arranged between the outlet of the medium heater 104 and the transfer roller pair 106, and detects the presence or absence of the recording medium M. The medium sensor 108 may have, for example, a light emitting element and a light receiving element. The detection signal of the medium sensor 108 changes depending on whether or not the light output from the light emitting element toward the light receiving element is blocked by the recording medium M. Further, in the transport path, a tip sensor 109 is provided between the transport roller 107 and the discharge port 111. The location of the tip of the recording medium M on the transport path is determined based on the detection results of the medium sensor 108 and the tip sensor 109.

The thermal head 103 presses the ink ribbon against the recording medium M from the back surface side of the ink ribbon loaded in the ink ribbon cartridge 105. As a result, a part (recording surface) of the surface of the tubular recording medium M becomes substantially flat. The thermal head 103 has a large number of heat sources (heating element elements). The thermal head 103 selectively energizes a plurality of heat sources according to an image signal, melts the ink ribbon, and transfers the ink to the surface of the tubular recording medium M. The thermal head 103 is configured to be movable between a retracted position separated from the platen roller 112 and a printing position where the recording medium M (and the ink ribbon) is pressed against the platen roller 112.

The transport roller 107 transports the recording medium M in cooperation with the platen roller 112, and discharges the recording medium M from the discharge port 111. A cutting portion 114 is provided between the transport roller 107 and the discharge port 111. The recording medium M is discharged from the discharge port 111 after being cut as needed by the cutting unit 114.

<Control configuration>
FIG. 2 is a block diagram showing an example of a control configuration of the printer 100. The control unit 200 includes a CPU, ROM, and RAM connected to each other by an internal bus. The control program of the printer 100 is stored in the ROM. RAM functions as a work area for the CPU. The control unit 200 may be configured by a microcomputer.

The control unit 200 controls the operation of each device connected to the control unit 200. The control unit 200 includes an operation unit 102 (display unit 121 and input unit 122), a thermal head 103, a medium heater 104, a medium sensor 108, a tip sensor 109, a cutting unit 114, motor drivers 201 and 202, a battery 203, and the like. The voltage measuring unit 204 is connected. Further, the control unit 200 accepts instructions and image information (print data) input from the operation unit 102 (input unit 122), and displays information for the user on the operation unit 102 (display unit 121). ..

The control unit 200 may be connectable to an external device such as a personal computer, or may receive instructions and image information from the external device. Further, an external storage device such as a RAM card or USB may be attached to the printer 100, and the data stored in such an external storage device may be used by the control unit 200.

The motor driver 201 controls the operation of the transport motor 211. The transfer motor 211 is a motor that drives the transfer roller pair 106 and the transfer roller 107. The motor driver 202 controls the operation of the head motor 212. The head motor 212 is a motor that moves the thermal head 103 between the above-mentioned retracted position and the printing position. The transport motor 211 and the head motor 212 are composed of, for example, a stepping motor. The battery 203 is used as a power source for operating the printer 100 and is composed of a rechargeable secondary battery. The voltage measuring unit 204 measures the voltage on the line between the battery 203 and the thermal head 103, as will be described later with reference to FIG.

<Voltage measurement unit>
FIG. 3 is a diagram showing an example of the connection configuration of the voltage measuring unit 204. The voltage measuring unit 204 is connected between the battery 203 and the thermal head 103. The battery 203 is composed of an internal resistance Rb and a power supply DC. The voltage measuring unit 204 has a voltage detector 301, DC-DC (voltage converters) 302 and 303, and switches S1 to S4. The switches S1 to S4 are each composed of, for example, FETs.

A voltage detector 301 for detecting a voltage is arranged on the line between the battery 203 and the thermal head 103. Further, on the line between the voltage detector 301 and the thermal head 103, a switch S1 for switching the connection between the battery 203 and the thermal head 103 is arranged. Further, three parallel lines in which the switches S2 to S4 are arranged are connected between the switch S1 and the thermal head 103. The DC-DC 302 is connected between the switches S1 and S2. DC-DC303 is connected between switches S1 and S3. The control unit 200 controls the on / off of the switch S1 and also controls the on / off of the switches S2 to S3 so that any of the switches S2 to S3 is turned on. Specifically, the control unit 200 controls the switches S1 to S4 as follows.

(1) When printing is executed, the control unit 200 supplies a voltage from the battery 203 to the thermal head 103 via the DC-DC 302 by turning on the switches S1 and S2. At this time, the voltage output from the battery 203 is boosted to a predetermined voltage for printing by DC-DC 302 and applied to the thermal head 103.
(2) When detecting the resistance value Rs of the thermal head 103, the control unit 200 supplies a voltage from the battery 203 to the thermal head 103 via the DC-DC 303 by turning on the switches S1 and S3. do. At this time, the voltage output from the battery 203 is stepped down to a predetermined voltage for detecting the resistance value Rs by the DC-DC 302, and is applied to the thermal head 103.
(3) When estimating the capacity of the battery 203 (measuring the current flowing through the thermal head 103), the control unit 200 turns on the switches S1 and S4 so that the battery does not go through the DC-DC 302 and 302. The 203 is directly connected to the thermal head 103.

In this way, when image formation is performed by the image forming unit, the output voltage of the battery 203 is converted into a predetermined voltage and output to the thermal head 103 via a voltage converter (DC-DC302), and the battery 203 and the battery 203 are formed. The thermal head 103 is connected. On the other hand, when the current flowing through the thermal head 103 is measured, the battery 203 and the thermal head 103 are directly connected without going through the voltage converter (DC-DC302). The switches S1 to S4 function as a connection switching unit for switching the connection between the battery 203 and the thermal head 103 in this way.

In the battery capacity estimation process (S102) described later, the control unit 200 measures the voltage detected by the voltage detector 301 with the switch S1 turned off as the closed circuit voltage V1 of the battery 203. Further, the control unit 200 measures the current flowing through the thermal head 103 based on the voltage detected by the voltage detector 301 with the switch S1 (and S4) turned on.

<Thermal head>
FIG. 4 is a diagram showing a configuration example of the thermal head 103. The thermal head 103 has 128 resistors R1 to R128 and a control circuit 401 that controls energization of each resistor. Each resistor has a resistance value within an error range from the reference value (nominal value). In this example, each resistor is assumed to have a resistance value within the range of ± 15% from the reference value Rref (for example, 800Ω). The control circuit 401 causes a current to flow through the resistors R1 to R128 according to the DATA signal output from the control unit 200. The DATA signal is composed of 128 bits corresponding to each resistor.

The control circuit 401 sets whether or not to pass a current (energize) to the corresponding resistor according to each bit of the DATA signal. The DATA signal is synchronized with the CLOCK signal. The control circuit 401 sets whether or not to energize each of the resistors R1 to R128 by sequentially taking in data (bits) from the DATA signal at the rising edge of the pulse of the CLOCK signal. When the LATCH signal is output from the control unit 200, the control circuit 401 determines the energization setting for the resistors R1 to R128. After that, the control circuit 401 energizes the resistors R1 to R128 while the STROBE signal output from the control unit 200 is on, according to the determined energization setting.

<Battery characteristics>
FIG. 5 shows an example of a charge rate (SOC: State Of Charge) -closed circuit voltage (OCV: Open Circuit Voltage) characteristic (SOC-OCV characteristic) as a characteristic of the battery 203. This SOC-OCV characteristic shows the relationship between the charge rate and the voltage in the state of not being connected to the load of the battery 203 (that is, the closed circuit voltage). The charge rate corresponds to the ratio of the amount of electricity charged (the amount of electricity excluding the amount of discharged electricity) to the electric capacity in the state where the battery 203 is fully charged. The charge rate of the battery 203 can be estimated by detecting the closed circuit voltage of the battery 203 and obtaining the charge rate corresponding to the detected voltage by using the SOC-OCV characteristic. In this embodiment, as will be described later, the charge rate of the battery 203 is estimated using the SOC-OCV characteristics shown in FIG. 5, and the capacity of the battery 203 is further estimated.

FIG. 6 shows an example of the cycle life characteristic of the battery 203, the relationship between the number of times the battery 203 is charged and the capacity [mAh] of the battery 203, and the number of times the battery 203 is charged and the internal resistance value Rb of the battery 203. Shows the relationship. Generally, as shown in FIG. 6, the capacity of the battery 203 gradually increases as the internal resistance value Rb of the battery 203 increases as the number of times of charging increases due to the deterioration of the battery due to repeated charging, and the capacity of the battery 203. Gradually decreases. In the present embodiment, as will be described later, the internal resistance value Rb of the battery 203 is detected (measured), and the capacity of the battery 203 is estimated using the cycle life characteristic shown in FIG. 6 based on the measured internal resistance value. do.

<Operation when executing a print job>
7 and 8 are diagrams showing an example of the operation of the printer 100 when the print job is executed. FIG. 7 shows an example in which the number of printed copies in the print job is one, and FIG. 8 shows an example in which the number of printed copies in the print job is three, and shows the timing of each operation. In FIGS. 7 and 8, “conveyance” indicates the timing at which the transport roller pair 106 and the transport roller 107 perform an operation of transporting the tubular recording medium M. “Printing” indicates the timing at which the thermal head 103 performs an operation of forming an image on the recording medium M. “Cut” indicates the timing at which the cutting unit 114 cuts the recording medium M on which the image is formed. “Heating” indicates the timing at which the medium heater 104 operates to heat the recording medium M in order to maintain the flexibility of the recording medium M.

As shown in FIGS. 7 and 8, each operation related to the execution of the print job is executed in accordance with the transfer timing of the tubular recording medium M. Further, the timing at which the recording medium M is cut by the cutting portion 114 after the image is formed by the thermal head 103 changes according to the distance between the thermal head 103 and the cutting portion 114 in the transport path. Further, the current flowing through the thermal head 103 (each resistor) changes according to the image forming operation shown in FIGS. 7 and 8. Therefore, in the process of estimating the power consumption at the time of executing the print job (described later with reference to FIG. 11), it is necessary to estimate the power consumption in consideration of each operation related to the execution of the print job.

<Flowchart: Printing process>
FIG. 9 is a flowchart showing the procedure of the printing process in the printer 100. When the printer 100 receives a print job execution instruction from the user via the operation unit 102, the control unit 200 starts executing the print job according to the procedure of FIG. First, in S101, the control unit 200 drives the head motor 212 so as to move the thermal head 103 from the retracted position to the printing position and press the recording medium M (and the ink ribbon) against the platen roller 112. When the movement of the thermal head 103 to the print position is completed, the control unit 200 advances the process to S102.

In S102, the control unit 200 executes the process of estimating the capacity of the battery 203 according to the procedure shown in FIG. 10, and proceeds to S103. In S103, the control unit 200 executes a process of estimating the amount of power used when the print job is executed according to the procedure shown in FIG. 11, and advances the process to S104. The process of S103 may be executed before the process of S102, or may be executed in parallel with the process of S102.

In S104, the control unit 200 compares the remaining capacity of the battery 203 estimated in S102 with the power consumption estimated in S103, and determines whether or not to execute the printing process based on the comparison result. Perform the processing. When it is determined that the print process is to be executed, the control unit 200 starts the print process of forming an image on the recording medium M according to the print job in S105.

After the start of the printing process, in S106, the control unit 200 determines whether or not the output voltage of the battery 203 has dropped to a predetermined voltage, and if the output voltage has dropped to a predetermined voltage, the process proceeds to S108 and the output is performed. If the voltage has not dropped to a predetermined voltage, the process proceeds to S107. This predetermined voltage is predetermined as a voltage obtained by adding a certain margin to the minimum voltage corresponding to the usage limit of the battery 203 configured as a secondary battery in order to prevent over-discharging of the battery 203. When the battery 203 is over-discharged and the remaining capacity reaches 0, the battery 203 is in a deep discharge state, and the cells constituting the battery are deteriorated and cannot be recovered. The processing of S106 is performed in order to prevent the battery 203 from reaching such a state.

When the output voltage of the battery 203 drops to a predetermined voltage, the control unit 200 stops the printing process being executed in S108, performs the backup process in S109, and ends the process according to the procedure of FIG. The backup process includes, for example, a process of backing up data and the like input from the input unit 122 by the user, and a process of displaying a message indicating that the battery is dead on the display unit 121.

On the other hand, in S107, the control unit 200 determines whether or not to end the printing process. When the formation of the image according to the print job is completed, the control unit 200 determines that the printing process is completed, and ends the process according to the procedure of FIG. When the control unit 200 continues to form the image according to the print job, the control unit 200 repeats the process of S106 by returning the process to S106.

● Battery capacity estimation processing FIG. 10 is a flowchart showing a procedure for battery capacity estimation processing in S102. The control unit 200 estimates the capacity (battery capacity) and the remaining capacity of the battery 203 by using the voltage measuring unit 204 and the thermal head 103.

First, in S111, the control unit 200 stops the output to the DC-DC 302 and 303 provided in the voltage measuring unit 204, and proceeds to the process to S112. The control unit 200 may turn off the switches S2 and S3 connected to the DC-DCs instead of stopping the outputs of the DC-DCs 302 and 303.

In S112, the control unit 200 turns off the switch S1, measures the voltage detected by the voltage detector 301, and acquires the obtained measured value as the closed circuit voltage (OCV) V1. After that, in S113, the control unit 200 turns on the switches S1 and S4, and causes (energizes) a current from the battery 203 to the thermal head 103 via the switches S1 and S4. At this time, of the plurality of resistors (resistors R1 to R128) included in the thermal head 103, the resistor determined by the process of FIG. 13 described later is energized. With the thermal head 103 energized, the control unit 200 measures the voltage detected by the voltage detector 301, and acquires the obtained measured value as the voltage V2. The voltage V2 corresponds to the voltage applied to the thermal head 103.

The control unit 200 measures the current flowing through the thermal head 103 based on the voltage V2. The current is determined to be V2 / Rs based on the resistance value Rs of the thermal head 103.
As will be described later, the resistance value Rs of the thermal head 103 is set to correspond to the average value of the resistance value of the resistor used in S113 and to be equal to the reference value Rref. In S114, the control unit 200 acquires the internal resistance value Rb of the battery 203 using the following equation based on the measured values (V2 / Rs) of the closed circuit voltage V1, the voltage V2, and the current flowing through the thermal head 103.
V1-V2 = (V2 / Rs) * Rb
In this way, the internal resistance value of the battery 203 is acquired (measured) based on the measured value of the current flowing through the thermal head 103.

After acquiring the internal resistance value Rb of the battery 203, then in S115, the control unit 200 estimates the current capacity Y of the battery 203 using the cycle life characteristic of the battery 203 (FIG. 6). Specifically, the control unit 200 obtains the number of times of charging corresponding to the internal resistance value Rb, and further obtains the capacity corresponding to the number of times of charging. In this way, the control unit 200 can estimate the current (total) capacity Y of the battery 203. The data showing the cycle life characteristic (FIG. 6) and the SOC-OCV characteristic (FIG. 5) of the battery 203 are stored in advance in the ROM in the control unit 200, and are read out from the ROM and used.

After that, in S116, the control unit 200 obtains the charge rate (SOC) by using the SOC-OCV characteristic (FIG. 5) of the battery 203 based on the closed circuit voltage (OCV) V1 measured in S112. The charge rate n of the battery 203 is estimated. Further, in S117, the control unit 200 estimates the current remaining capacity Z (= n * Y) of the battery 203 based on the current capacity Y of the battery and the charge rate n, and processes according to the procedure of FIG. 10 (S102). ) Is terminated, and the process proceeds to S103.

● Estimating Process of Electric Energy Used FIG. 11 is a flowchart showing a procedure of estimating the electric energy used in S103. In the present embodiment, the control unit 200 is based on at least one of the print rate in the print job, the print length in the transport direction of the recording medium M, the print mode, and the number of print copies for each print job to be executed. , Estimate the amount of power used.

First, in S121, the control unit 200 acquires the print rate α in the image formation by the thermal head 103 based on the print data included in the print job. The print ratio corresponds to the ratio of the region where the image is formed (the ink is transferred) in the region where the image can be formed on the recording surface of the recording medium M.

In S122, the control unit 200 confirms the preheating setting for the heating operation (preheating operation) of the recording medium M by the medium heater 104 in the print job, so that the time θ required for the preheating and the power D can be determined. Get the settings. When it is set not to perform the preheating operation, the time θ and the power D are set to 0.

In S123, the control unit 200 acquires the number of times m of cutting by the cutting unit 114 and the power C required for the cutting operation by confirming the print mode in the print job. When the print mode in which the disconnection operation is not performed is used, the number of disconnections m and the power C are set to 0. Further, in S124, the control unit 200 acquires the print length β per copy in the transport direction of the recording medium M and the number of print copies ε by confirming the print settings in the print job. The processes of S121 to S124 can be executed in any order.

After that, in S125, the control unit 200 estimates the power consumption Wb at the time of executing the print job based on the parameter values acquired in S121 to S124. The amount of power used Wb [Wb] is calculated by the following equation.
Wb = [{α * (β / A) * B} + (m * C)] * ε + [ε * θ * D]
A is the printing speed, and B is the power consumption of the thermal head 103. When the control unit 200 estimates the power consumption Wb, the control unit 200 ends the process (S103) according to the procedure of FIG. 11 and proceeds to the process to S104.

● Print determination process FIG. 12 is a flowchart showing a procedure of the print determination process in S104. First, in S131, the control unit 200 obtained the estimation result of the remaining capacity Z (= n * Y) of the battery 203 obtained by the processing of S102 (FIG. 10) and the processing of S103 (FIG. 11). Compare with the estimation result of the electric energy used Wb. Here, the control unit 200 converts the remaining capacity Z of the battery 203 into the electric energy Wa [Wb] by the following equation in order to enable comparison with the electric energy Wb.
Wa = V1 * Z * τ
Note that τ is the voltage conversion efficiency of DC-DC302. As a result, the control unit 200 compares the electric energy Wa [Wh] corresponding to the remaining capacity Z of the battery 203 with the electric energy Wb [Wh] used.

Based on the comparison result in S131, in S132, the control unit 200 determines whether or not the remaining capacity Z of the battery 203 is insufficient for executing the print job. When Wa ≧ Wb, the control unit 200 determines that the remaining capacity Z of the battery 203 is not insufficient, and proceeds to S133. In S133, the control unit 200 displays a notification indicating that printing is possible on the display unit 121, ends the process (S104) according to the procedure of FIG. 12, and advances the process to S105.

On the other hand, when Wa <Wb, the control unit 200 determines that the remaining capacity Z of the battery 203 is insufficient, and proceeds from S132 to S134. In S134, the control unit 200 displays a notification indicating that the remaining capacity Z of the battery 203 is insufficient on the display unit 121, and confirms to the user whether or not to perform the printing process. In S135, the control unit 200 determines whether or not to execute the printing process based on the user's instruction input from the input unit 122. When executing the printing process, the control unit 200 ends the process (S104) according to the procedure of FIG. 12 and advances the process to S105. On the other hand, when the print process is not executed, the control unit 200 stops the execution of the print job by ending the process according to the procedures of FIGS. 12 and 9.

<Flowchart: Control of resistance>
FIG. 13 shows control of the use of the resistor for determining the resistor used in S113 in the battery capacity estimation process (S102) among the plurality of resistors (resistors R1 to R128) of the thermal head 103. It is a flowchart which shows the procedure of. The resistor used in S113 is predetermined at the time of shipment from the printer 100, and therefore the number N of resistors used is also predetermined (for example, N = 80). However, the resistance value of each resistor used in the thermal head 103 changes with the passage of time. Therefore, it is desirable to redetermine the resistor used in S113 according to the change in the resistance value of each resistor after a certain period of time.

Therefore, in the present embodiment, the control unit 200 has a plurality of resistances in the measurement so that the average resistance value Rave of the resistor energized in the measurement of the current flowing through the thermal head 103 becomes a predetermined value (reference value Rref). Controls the energization of the body. Specifically, the control unit 200 redetermines the resistor used in S113 by executing the control according to the procedure of FIG. 13 every time a predetermined number of images are formed.

The control unit 200 executes control according to the procedure of FIG. 13 at the start of execution of the print job every time a predetermined number of images are formed. First, in S141, the control unit 200 turns off S2 and S4, turns on switches S1 and S3, and energizes each resistor of the thermal head 103 in order from the battery 203 via the switch S1, DC-DC303, and the switch S3. do. Further, the control unit 200 measures the value of the current flowing through the resistor by measuring the voltage detected by the voltage detector 301 while each resistor is energized, and the resistor is based on the measurement result. Get the resistance value of. As a result, the control unit 200 acquires the resistance values of the resistors R1 to R128 as shown in FIG.

Next, in S142, the control unit 200 generates a list in which the resistors R1 to R128 are rearranged in ascending or descending order of resistance values, as shown in FIG. 14, based on the measurement results in S141, and the list is used. Update the resistance table. The resistance table is held in a state of being stored in ROM or RAM.

Further, in S143, the control unit 200 determines whether or not the maximum resistance value among the resistance values of the resistors R1 to R128 is lower than the reference value Rref (for example, 800Ω), and if it is lower than that, the process proceeds to S144. In S144, the control unit 200 reduces the number N of resistors used in S113 by F (that is, N = NF), and advances the process to S147. On the other hand, if the maximum resistance value does not fall below the reference value Rref, the process proceeds from S143 to S145. In S145, the control unit 200 determines whether or not the minimum resistance value among the resistance values exceeds the reference value Rref (for example, 800Ω) with respect to the resistors R1 to R128, and if it exceeds, proceeds to S146. In S146, the control unit 200 increases the number N of resistors used in S113 by F (that is, N = N + F), and advances the process to S147. On the other hand, if the minimum resistance value does not exceed the reference value Rref, the process proceeds from S145 to S147.

In S147, the control unit 200 specifies a range in the resistor table in which the average resistance value Rave of the resistors included in the range is equal to the reference value Rref as a range consisting of N consecutive resistors. The control unit 200 further adjusts the range of use of the resistor in the resistor table by defining the specified range as the range of use in S113. For example, the control unit 200 makes such an adjustment by shifting a range of N consecutive resistors so that the average resistance value Rave for the range approaches the reference value Rref.

Finally, in S148, the control unit 200 determines N resistors included in the adjusted use range in S147 as resistors to be used in S113, and ends the process according to the procedure of FIG. In this way, by controlling the use of the resistor so that the resistance value of the thermal head 103 becomes constant, it is possible to improve the estimation accuracy of the capacity of the battery 203.

In the example of FIG. 13, the use of the resistor is controlled so that the resistance value of the thermal head 103 is constant, but even if the resistance value of the thermal head 103 is variable, FIGS. 10 to 12 It is possible to estimate the capacity of the battery 203 by the procedure of.

As described above, in the printer 100 (image forming apparatus) of the present embodiment, the control unit 200 connects the battery 203 and the thermal head 103, and measures the current flowing through the thermal head 103. The control unit 200 acquires the internal resistance value Rb of the battery 203 based on the measured value of the current obtained by the measurement, and estimates the capacity of the battery 203 based on the internal resistance value. As described above, according to the present embodiment, it is possible to provide an image forming apparatus capable of estimating the capacity of the battery 203 without providing a resistance for measuring the internal resistance value Rb of the battery 203.

Further, by estimating the capacity of the battery 203 based on the internal resistance value Rb of the battery 203, it is possible to avoid deterioration of the estimation accuracy of the battery capacity due to an increase in the internal resistance value Rb due to deterioration of the battery performance. ..

The invention is not limited to the above embodiment, and various modifications and changes can be made within the scope of the gist of the invention.

100: Printer, 103: Thermal head, 200: Control unit, 203: Battery, 204: Voltage measurement unit, 301: Voltage detector

Claims (12)

It is an image forming device
A battery used as a power source for the image forming apparatus and
An image forming means having a thermal head for forming an image by thermal transfer on the surface of a conveyed recording medium, and an image forming means.
A measuring means for connecting the battery and the thermal head and measuring the current flowing through the thermal head,
A first estimation means that acquires the internal resistance value of the battery based on the measured value of the current obtained by the measurement by the measuring means and estimates the capacity of the battery based on the internal resistance value.
An image forming apparatus comprising. When image formation is performed by the image forming means, the battery and the thermal head are connected via a voltage converter that converts the output voltage of the battery into a predetermined voltage and outputs the voltage to the thermal head. The image forming apparatus according to claim 1, wherein when the measurement by the measuring means is performed, the battery and the thermal head are directly connected without going through the voltage converter. The measuring means further measures the closed circuit voltage of the battery.
The first estimation means is according to claim 1 or 2, wherein the capacitance is estimated based on the measured value of the closed circuit voltage obtained by the measurement by the measuring means and the measured value of the current. The image forming apparatus described. A voltage detecting means provided on the line between the battery and the thermal head to detect the voltage,
A switch provided on the line between the voltage detecting means and the thermal head and switching the connection between the battery and the thermal head is further provided.
The measuring means is
The voltage detected by the voltage detecting means with the switch turned off is measured as the closed circuit voltage.
The image forming apparatus according to claim 3, wherein the current is measured based on a voltage detected by the voltage detecting means while the switch is on. The fourth aspect of the present invention is characterized in that the measuring means obtains a measured value of the current based on a voltage detected by the voltage detecting means with the switch turned on and a resistance value of the thermal head. The image forming apparatus according to the description. The thermal head has a plurality of resistors that are selectively energized according to an image signal.
The measuring means according to claim 3 to 5, wherein the measuring means controls energization of the plurality of resistors in the measurement so that the average resistance value of the resistors energized in the measurement becomes a predetermined value. The image forming apparatus according to any one item. The first estimation means further obtains a charge rate corresponding to a measured value of the closed circuit voltage by using a characteristic showing the relationship between the closed circuit voltage and the charge rate of the battery, and obtains the charge rate corresponding to the measured value of the closed circuit voltage, and the capacity and the charge rate. The image forming apparatus according to any one of claims 3 to 6, wherein the remaining capacity of the battery is estimated based on the above. A second estimation method for estimating the amount of power used when executing a print job,
The remaining capacity estimated by the first estimation means is compared with the power consumption estimated by the second estimation means, and image formation by the image forming means is controlled based on the result of the comparison. The image forming apparatus according to claim 7, further comprising a control means. The image according to claim 8, wherein the control means stops the execution of the print job when it is determined that the remaining capacity is insufficient for the execution of the print job based on the result of the comparison. Forming device. The second estimation means is used for each print job to be executed based on at least one of the print rate in the print job, the print length in the transport direction of the recording medium, the print mode, and the number of copies. The image forming apparatus according to claim 8 or 9, wherein the image forming apparatus is characterized in that the amount of electric power is estimated. The image forming apparatus according to claim 10, wherein the print mode indicates whether or not to perform a cutting operation of the recording medium and whether or not to perform a heating operation of the recording medium. A control method for an image forming apparatus including an image forming means having a thermal head for forming an image on the surface of a conveyed recording medium by thermal transfer, and a battery used as a power source for the image forming apparatus.
A measurement step of connecting the battery and the thermal head and measuring the current flowing through the thermal head.
A step of acquiring the internal resistance value of the battery based on the measured value of the current obtained by the measurement and estimating the capacity of the battery based on the internal resistance value.
A method for controlling an image forming apparatus, which comprises.

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