JP2019015960A - Heating control device, image forming apparatus, heating control method, and program - Google Patents

Abstract

To ensure the total amount of output from a plurality of heat sources and linearity of lighting to achieve stable lighting control.SOLUTION: A heating control device comprises: a voltage detection processing unit 11 that detects the values of voltage of a plurality of supply power sources that supply power to a plurality of respective heat sources that heat a fixing member; and a heating control unit 10 that allocates the maximum lighting duty obtained by adding up lighting duties of the plurality of heat sources to the plurality of respective heat sources so that the maximum output values of the plurality of respective heat sources have a constant value, and lights the plurality of heat sources with duty control. The heating control unit 10 corrects the total amount of power of the plurality of heat sources to be linear to a predetermined duty according to the voltage values detected by the voltage detection processing unit 11 and the rated output value of the heat sources.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heating control device, an image forming apparatus, a heating control method, and a program.

  Conventionally, in an image forming apparatus such as an electrophotographic copying machine, printer, facsimile, etc., heat fixing as a fixing device for fixing an unfixed image (toner image) transferred to a recording material such as transfer paper on the recording material. The device is widely used. As a control problem of the heater used in the fusing unit, there is known a technology that achieves both the followability (stability) of fusing temperature and the reduction of harmonics and flicker (flicker phenomenon) required by EMC (European Union). ing.

  A technique called “allocation control” is known as a method for lighting a fixing heater that clears the EMC flicker regulation reference value and supplies the duty required by the fixing unit without fluctuation in waveform. For this allocation control, for example, Patent Literature 1 discloses a lighting method in which only one of the plurality of heaters performs duty control, and the other heaters perform on / off control.

  However, in the above-described conventional technology, it is assumed that a plurality of heaters (heat sources) having the same output are used. For this reason, normally, the plurality of heaters are supplied with power from the same power source. However, when the number of heaters or the number of outputs W increases, a plurality of power sources may be provided. At this time, when the output voltage of the power source is different, there is a problem that the total power amount (output heat amount) of the heater and the linearity of the heater lighting cannot be maintained. Moreover, the same thing occurs with respect to power limitation.

  The present invention has been made in view of the above, and realizes stable lighting control by ensuring the total power amount of the heat source and linearity of lighting when lighting control of a plurality of heat sources by a plurality of power sources is performed. For the purpose.

  In order to solve the above-described problems and achieve the object, the present invention provides voltage values of a plurality of power supplies that supply power to a plurality of heat sources that heat a fixing member of a fixing device that fixes a toner image on a recording medium. A plurality of voltage detection units to detect, and a heating control unit that performs duty control in order to turn on the plurality of heat sources, and the heating control unit includes the voltage values and the heat sources detected by the plurality of voltage detection units. The duty of at least one heat source of the plurality of heat sources is corrected based on the rated output value.

  The present invention has an effect of ensuring stable lighting control by securing the total power amount of the heat source and lighting linearity when lighting control of a plurality of heat sources is performed by a plurality of power sources.

FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. FIG. 2 is an explanatory diagram illustrating a configuration example of the fixing device according to the embodiment. FIG. 3 is a block diagram illustrating a hardware configuration example of the image forming apparatus according to the embodiment. FIG. 4 is a block diagram illustrating a functional configuration example of the image forming apparatus according to the embodiment. FIG. 5 is a block diagram illustrating a configuration of the fixing control unit according to the embodiment. FIG. 6 is a flowchart illustrating a processing flow of the duty assignment example according to the embodiment. FIG. 7 is a flowchart of an allocation calculation example according to the embodiment. FIG. 8 is a graph showing a conventional heater control example (1). FIG. 9 is a graph showing a conventional heater control example (2). FIG. 10 is a graph showing a conventional heater control example (3). FIG. 11 is a graph showing a conventional heater control example (4). FIG. 12 is a graph showing an example of heater control in the present invention.

  Exemplary embodiments of a heating control apparatus, an image forming apparatus, a heating control method, and a program according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
First, an example of an image forming apparatus on which the heating control apparatus of the present embodiment is mounted will be described. FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. In FIG. 1, a tandem intermediate transfer type image forming apparatus main body is shown as the image forming apparatus 100. In the image forming apparatus 100, a paper feed table is arranged at the bottom. The image forming apparatus 100 also includes a tandem intermediate transfer image forming unit (hereinafter referred to as a tandem image forming unit) 120 in which a plurality of image forming units 118Y, 118M, 118C, and 118K are arranged in parallel. The subscripts Y, M, C, and K attached to the above symbols indicate yellow, magenta, cyan, and black colors, respectively. The image forming apparatus 100 is provided with an endless belt-shaped intermediate transfer body (hereinafter referred to as an intermediate transfer belt) 110 near the center. The intermediate transfer belt 110 is wound around a plurality of support rollers 114, 115a, 115b, 116a and the like so as to be able to rotate and convey clockwise in the drawing.

  In the illustrated example, a cleaning device 117 for the intermediate transfer belt is provided on the left of the support roller 116a. The cleaning device 117 removes residual toner remaining on the intermediate transfer belt 110 after image transfer. On the intermediate transfer belt 110 stretched between the support roller 114 and the support roller 115a, four images of yellow (Y), magenta (M), cyan (C), and black (K) are arranged along the conveyance direction. Forming means 118Y, 118M, 118C, and 118K (hereinafter referred to as 118Y, M, C, and K) are arranged side by side to constitute the tandem type image forming unit 120. The image forming units 118Y, 118M, 118C, and 118K of the tandem image forming unit 120 are photosensitive drums 140Y, 140M, 140C, and 140D as image carriers that carry toner images of yellow, magenta, cyan, and black, respectively. K. Hereinafter, the suffixes Y, M, C, and K may be omitted as long as there is no problem.

  On the tandem image forming unit 120, two exposure devices 121 are provided as shown in FIG. Each exposure device 121 corresponds to two image forming means (118Y and 118M, 118C and 118K), for example, two light source devices (such as a semiconductor laser, a semiconductor laser array, or a multi-beam light source) and a coupling optical system. , An optical scanning type exposure apparatus composed of a common optical deflector (polygon mirror, etc.), two scanning imaging optical systems, etc., according to the image information of each color of yellow, magenta, cyan, and black The photosensitive drums 140Y, M, C, and K are exposed to form an electrostatic latent image.

  Further, around the photosensitive drums 140Y, M, C, and K of the image forming units 118Y, 118M, 118C, and 118K, charging devices 113Y, 113M, and 113B that uniformly charge the photosensitive drums prior to the exposure described above. C, K, developing devices 111Y, M, C, K for developing the electrostatic latent image formed by the exposure device 121 with each color toner, and photoconductor cleaning for removing transfer residual toner on the photoconductor drum 140 Devices 117Y, M, C, K are provided. Further, at the primary transfer position where the toner image is transferred from the photosensitive drums 140Y, M, C, K to the intermediate transfer belt 110, the photosensitive drums 140Y, M, C, K are interposed with the intermediate transfer belt 110 interposed therebetween. Primary transfer rollers 162Y, 162M, 162C, and 162K are provided as constituent elements of the primary transfer unit so as to face each other.

  Of the plurality of support rollers that support the intermediate transfer belt 110, the support roller 114 is a drive roller that rotationally drives the intermediate transfer belt 110, and is driven via a drive transmission mechanism (gear, pulley, belt, etc.) not shown. Connected with motor. Further, when a black (K) single color image is formed on the intermediate transfer belt 110, the supporting rollers 115a and 115b other than the supporting roller 114 are moved by a moving mechanism (not shown), and the yellow, magenta, and cyan photosensitive materials are moved. The body drums 140Y, 140M, 140C can be separated from the intermediate transfer belt 110.

  A secondary transfer device 122 is provided on the opposite side of the intermediate transfer belt 110 from the tandem type image forming unit 120. In FIG. 1, the secondary transfer device 122 applies a transfer electric field by pressing the secondary transfer roller 116 b against the secondary transfer counter roller 116 a to form an image on the intermediate transfer belt 110 as a sheet as a transfer medium. Transfer onto transfer paper S. Next to the secondary transfer device 122, a fixing device 125 that fixes a transfer image (unfixed toner image) on the transfer paper S by the action of heat and pressure is provided.

  The fixing device 125 is configured by pressing a pressure roller 127 against a fixing belt 126 that is an endless belt. The fixing belt 126 is wound around two support rollers, and at least one of the rollers is provided with heating means (not shown) (a heater, a lamp, an electromagnetic induction heating device, or the like). The fixing device 125 is controlled to turn on the heater by a heating control device to be described later.

  The transfer sheet S on which the image is transferred by the secondary transfer device 122 is transported to the fixing device 125 by a transport belt supported by two rollers 123. Of course, the conveyance belt 124 may be a fixed guide member, a conveyance roller, a conveyance roller, or the like.

  In the illustrated example, the transfer sheet S is recorded below the secondary transfer device 122 and the fixing device 125 in order to record images on both sides of the transfer sheet S in parallel with the tandem image forming unit 120 described above. A sheet reversing device for reversing and conveying is provided.

  FIG. 2 is an explanatory diagram illustrating a configuration example of the fixing device 125 according to the embodiment. The fixing device 125 in this example is a belt fixing method, and includes a fixing belt 126, a pressure roller 127, a fixing roller 128, a heating roller 129, and the like.

  The fixing belt 126 is an endless belt in which a base material of PI (polyimide resin) is coated with silicone rubber and PFA (fluorocarbon-polymers). The fixing belt 126 is made of a material having an excellent surface releasability in order to suppress toner adhesion during fixing. The pressure roller 127 is made of a metal cored bar and silicone rubber, has a heater 133 built in the cored bar part, and is pressed against the fixing roller 128 with a predetermined pressure. The fixing roller 128 is made of a metal core and silicone rubber. The heating roller 129 is an aluminum hollow roller, and a heat pipe is embedded in the aluminum portion, whereby the temperature in the axial direction can be made constant.

  In the hollow portion of the heating roller 129, a first heater 130 using a halogen heater, a second heater 131, and a third heater 132 are incorporated. The first heater 130 is a halogen heater, and has an output of 1100 W and a rated voltage of 200 V, and a voltage is applied from a plurality of power cables described later. The second heater 131 is a heater having the same specifications as the first heater 130, and a voltage is applied from a power cable described later. The 3rd heater 132 is a heater of the same specification as the 2nd heater 131, and a voltage is applied from the power cable mentioned below. In the vicinity of the heating roller 129, a temperature detection sensor 245 using, for example, a thermopile is arranged to monitor the temperature of the fixing belt 126. The lighting control of the first heater 130 to the third heater 132 will be described in detail later.

  FIG. 3 is a block diagram illustrating a hardware configuration example of the image forming apparatus 100 according to the embodiment. As illustrated, the image forming apparatus 100 includes a main control unit 200, an image forming unit 210, a fixing control unit 220, and the like. The main control unit 200 is a microcomputer system, and includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, and a RAM (Random Access Memory) 203. The fixing control unit 220 includes the heating control unit 10, a voltage detection unit 230, and a temperature detection sensor 245.

  The main control unit 200 comprehensively controls each unit of the image forming apparatus 100. The fixing control unit 220 performs lighting control of the first heater 130 to the third heater 132 of the fixing device 125 by a predetermined control signal sent from the main control unit 200. The heating control unit 10 includes a CPU 221, a ROM 222, and a RAM 223. The voltage detection unit 230 includes a first voltage detection unit 231 and a second voltage detection unit 232, detects a voltage applied to the heater from the power cable, and feeds it back to the heating control unit 10.

  FIG. 4 is a block diagram illustrating a functional configuration example of the image forming apparatus 100 according to the embodiment. As shown in the figure, the image forming apparatus 100 has functions of a heating control unit 10, a voltage detection processing unit 11, a temperature detection processing unit 12, and the like.

  The voltage detection processing unit 11 acquires the voltage value applied to each heater detected by the first voltage detection unit 231 and the second voltage detection unit 232, and executes a predetermined process. The voltage detection processing unit 11 detects voltage values of a plurality of power supplies that supply power to each of a plurality of heat sources that heat the fixing belt 126. The temperature detection processing unit 12 acquires a temperature value in the vicinity of the fixing belt 126 of the fixing device 125 detected by the temperature detection sensor 245, and executes a predetermined process.

  The heating control unit 10 allocates a lighting duty to a plurality of heat sources, assigns a lighting duty to a plurality of heat sources, and adds a lighting duty to each of a plurality of heat sources so that a maximum output value of each of the heat sources becomes a constant value. The heat source is turned on by duty control. Moreover, the heating control part 10 correct | amends the total electric energy of a some heat source linearly with respect to a predetermined | prescribed duty according to the voltage value detected by the some voltage detection part and the rated output value of a heat source. In addition, the heating control unit 10 allocates a lighting duty to each of the plurality of heat sources, assigning a lighting duty to each of the plurality of heat sources, so that the maximum output value of each of the plurality of heat sources becomes a constant value. These heat sources are turned on by duty control in descending order of lighting priority of a plurality of preset heat sources. In addition, the heating control unit 10 calculates the total electric energy of the plurality of heat sources as the voltage value detected by the plurality of voltage detection units when the lighting priority is changed while the fixing device 125 is operating. According to the rated output value of the heat source, it is linearly corrected for a predetermined duty.

  A part or all of the functional configuration of the image forming apparatus 100 described above may be realized by software or hardware.

  The duty indicates a ratio of energization time to the heater per unit time (control cycle).

  FIG. 5 is a block diagram illustrating a configuration of the fixing control unit 220 according to the embodiment. As illustrated, the fixing control unit 220 includes a feedback unit 255, a first heater control unit 271, a second heater control unit 272, and a third heater control unit 273.

  Based on the temperature information detected by the temperature detection sensor 245, the feedback unit 255 calculates a difference from the target value (Tref) of the fixing temperature of the fixing belt 126 and the current temperature (Tcur) of the fixing belt 126 detected by the temperature detection sensor 245. A value (= Tref−Tcur) is calculated. Then, the calculated difference value is sent to the main control unit 200. The first heater control unit 271 includes a PID control unit 281 and an on / off control unit 282. The second heater control unit 272 includes a PID control unit 283 and an on / off control unit 284. The third heater control unit 273 includes a PID control unit 285 and an on / off control unit 286. The 1st heater control part 271, the 2nd heater control part 272, and the 3rd heater control part 273 perform lighting control of each heater mentioned below.

  PID control is an abbreviation for Proportional Integral Differential Controller, and the input value is controlled by performing P (proportional), I (integral), and D (differential) on the difference between the set value and the current value. Control.

  In this example, the rated current of the power source output from the first power cable 291 is 20A, and the rated current of the power source output from the second power cable 292 is 20A.

  The first power cable 291 is connected to the first heater 130, and the voltage of the first power cable 291 is applied to the first heater 130. The second power cable 292 is connected to the second heater 131 and the third heater 132, and the voltage of the second power cable 292 is applied to the second heater 131 and the third heater 132. The first voltage detector 231 detects the voltage of the first power cable 291. The second voltage detector 232 detects the voltage of the second power cable 292. The voltage detection values by the first voltage detection unit 231 and the second voltage detection unit 232 are input to the heating control unit 10. The heating control unit 10 performs predetermined control based on this information.

  Next, an example in which the lighting duty allocation control of each heater is performed and the lighting duty and output of each heater are linearly controlled will be described. First, lighting priority (also referred to as lighting priority) and lighting patterns of each heater will be described. Here, the heater A, the heater B, and the heater C are referred to as control heater names, and the order of lighting priority is the heater A, the heater B, and the heater C. The actual first heater 130, second heater 131, and third heater 132 are assigned patterns to heaters A, B, and C, and are set as shown in Table 1 below.

  Calculation of the lighting duty of each heater of the first heater 130 to the third heater 132 is performed by PID calculation. Although there are three actual heaters in the present embodiment, calculation is performed assuming that the number is one, and 0% or more is output. Even if it is 100% or more, it is adopted. The calculated value is tripled.

Next, an example of duty assignment will be described. First, the output W when a voltage is applied to the halogen heater and the power is stabilized is expressed by the following relational expression.
Hw = Htw × (Vin / Vt) ^ (1.54)
Hw: Heater output power W
Htw: Output power at the rated voltage of the heater Vin: Applied voltage Vt: Rated voltage of the heater From the above equation, the ratio of the output voltage when different voltages are applied to the same heater is the power of 1.54 of the voltage ratio .

  Subsequently, calculation is performed on the assumption that different voltages are applied to the heater A, the heater B, and the heater C in terms of control. In this configuration, since the same power cable is used for the second heater 131 and the third heater 132, the same voltage is applied. However, in the calculation, it is possible to cope with the application of different voltages. Thereby, it can respond even if the power supply cables (power supplies) for applying a voltage to a some heater increase. In this example, the voltage from the first power supply cable 291 is referred to as a main power supply voltage (Vmain), and the voltage from the second power supply cable 292 is referred to as a sub power supply voltage (Vsub). The reference voltage used in the calculation was based on the sub power supply voltage that is the voltage from the second power cable 292. By the PID calculation, the output duty of the three heaters, the first, second and third heaters is obtained. The reference voltage is applied to one of the three heaters.

  The parameters used for control are defined as shown in Table 2. D in Table 2 is a value calculated by PID calculation and tripled, and is referred to as a calculated duty.

  Next, the processing flow of the duty assignment example will be described with reference to the flowchart shown in FIG. In FIG. 6, the duty is assigned in the order of heater A → heater B → heater C. When the sub power supply voltage is applied to the second heater 131 (heater C) and the third heater 132 (heater A), the coefficient calculation of the DUTY allocation is performed in the first heater 130 (heater B) to which the main power supply voltage is applied. .

The heating control unit 10 acquires the calculated duty at the start of this process, and sets D = 63 × 3 = 189%. First, the heating control unit 10 acquires the lighting pattern acquisition of Table 1 (step S101). If the pattern 2 is selected, the heaters A to C used in the control, the actual first heater 130 to the third heater 132, and the applied voltage are as follows.
Heater A = third heater 132 (voltage application from sub power supply)
Heater B = first heater 130 (voltage application from main power supply)
Heater C = second heater 131 (voltage application from sub power supply)

Subsequently, the heating control unit 10 calculates output coefficients Ka, Kb, and Kc with respect to the sub power supply voltage (Vsub) (step S102). Here, it is assumed that the voltage detection result of the main power source (first power cable 291) is 236V and the voltage detection result of the sub power source (second power cable 292) is 200V.
Ka = 1
Kb = (236/200) ^ 1.54 = 1.29
Kc = 1

  Subsequently, the heating control unit 10 determines whether or not the duty can be satisfied by the heater A (step S103). That is, the heating control unit 10 determines whether or not [D-100Ka> 0]. In this example, [D-100Ka> 0] → 189-100 = 89> 0, which means that only the heater A cannot obtain the requested output. In step S103, the heating control unit 10 proceeds to step S104 if the determination is Yes, and proceeds to step S107 if the determination is No.

  In step S107, the heating control unit 10 calculates the duty of the heater A. On the other hand, in step S104, the heating control unit 10 determines whether or not the duty can be satisfied by the heater A + B. That is, the heating control unit 10 determines whether [D-100Ka-100Kb> 0]. In step S104, in this example, [D-100Ka-100Kb> 0] → 189-100-129 = −40, and a higher voltage is applied to the heater B than the heater A, and a correction of 1.29 is applied. Yes. This means that the output required by heater A and heater B can be obtained. In step S104, the heating control unit 10 proceeds to step S105 if the determination is Yes, and proceeds to step S108 if the determination is No.

In step S108, the heating control unit 10 calculates the duty of the heater B. That is, in step S108, the heating control unit 10 calculates [Da = 100, Db = (D-100Ka) / Kb, Dc = 0]. In this example, [Da = 100, Db = (D-100Ka) / Kb, Dc = 0]
Da = 100,
Db = (189-100) /1.29=69 and
Dc = 0.

  The heating control unit 10 calculates the duty assigned to Db. Since the heater B has an output of 1.29 times the same duty as the heater A, the heating control unit 10 applies a correction of 1.29 to match the value when the heater A outputs 189%. (Divide). Thus, the heater duty and the output are in a linear relationship. Further, even if the heater lighting pattern is changed by this calculation, the same output is obtained with respect to the calculated duty.

  On the other hand, in step S105, the heating control unit 10 determines whether (D-100Ka-100Kb-100Kc) is larger than “0”. In step S105, the heating control unit 10 proceeds to step S106 if the determination is Yes, and proceeds to step S109 if the determination is No.

  In step S109, the heating control unit 10 calculates the duty of the heater C. On the other hand, in step S106, the heating control unit 10 ends this operation with Da = 100, Db = 100, and Dc = 100.

  Next, an example of limiting the heater output will be described. The maximum value of the duty allocated to the three is set so that the maximum output value of the heater becomes a constant value. A value obtained by adding the three maximum duty values is referred to as a maximum lighting duty.

A setting example of the maximum lighting duty will be described. The output W when a voltage is applied to the halogen heater and the power is stabilized is expressed by the following relational expression.
Hw = Htw × (Vin / Vt) ^ (1.54)
Hw: Heater output power W
Htw: Output power at the rated voltage of the heater Vin: Applied voltage Vt: Rated voltage of the heater From the above equation, the ratio of the output voltage when different voltages are applied to the same heater is the power of 1.54 of the voltage ratio .

  Subsequently, calculation is performed on the assumption that different voltages are applied to the heater A, the heater B, and the heater C in terms of control. In this configuration, since the same power cable is used for the second heater 131 and the third heater 132, the same voltage is applied to the second heater 131 and the third heater 132, but different voltages are applied in the calculation. Even so, be prepared. Thereby, it can respond even if a power supply cable increases.

  Here, as the names of the voltages, the voltage from the first power cable 291 is called a main power voltage, and the voltage from the second power cable 292 is called a sub power voltage.

  Parameters used for control are defined as shown in Table 3. The total power Wall is assumed to be power limited by the image forming apparatus 100. It is considered that the maximum power Wma of one heater is read with a maximum error of 2% higher than the true value of the voltage detection. Therefore, 102% of the detected voltage is a voltage applied to the heater.

  Next, an allocation calculation example will be described with reference to the flowchart shown in FIG. Here, the rated voltage of the first heater 130, the second heater 131, and the third heater 132 is set to 208V. Further, in this example, it is assumed that the voltage detection desires a maximum value higher than the true value (the actual voltage is 102% of the detection voltage). Also, the heater is considered to have the maximum tolerance. Under this condition, the duty when the set total power is consumed by the image forming apparatus is the maximum lighting duty. Further, the duty is assigned in the order of heater A (heater identification Ha) → heater B (heater identification Hb) → heater C (heater identification Hc). The total power is 3300W.

  In FIG. 7, first, an applied voltage is acquired by the first voltage detector 231 and the second voltage detector 232 (step S201). It is assumed that the detected main voltage is 200V and the detected sub voltage is 240V. Further, the rated voltage of the heater is 208 V, the power is 1100 W, and the power tolerance is −5 to 0%.

Subsequently, a lighting pattern is acquired (step S202). Here, the lighting pattern is assumed to be pattern 1 (see Table 1). At this time, the maximum power of one heater is calculated as follows.
Wma = 1067W (application of voltage by main power supply)
Wmb = 1414W (application of voltage by sub power supply)
Wmc = 1414W (voltage application by sub power supply)

  Subsequently, it is determined whether or not [Wall> Wma] (step S203). That is, it is confirmed whether the heater A can compensate the total power Wall. In this example, 3300-1066> 0, and the output of the heater A is less than the limit power. In step S203, if the determination is Yes, the process proceeds to step S204. If the determination is No, the process proceeds to step S208.

  In step S208, the duty of heater A is calculated. That is, Dda = Wall / Wma × 100, Ddb = 0, and Ddc = 0 are calculated. On the other hand, in step S204, it is determined whether or not [Wall-Wma> Wmb]. That is, it is confirmed whether the total power Wall can be supplemented by the heater A + B. In this example, 3300-1067 = 2233> 1414, and the total output of the heaters A and B is equal to or lower than the limit power. In step S204, if the determination is Yes, the process proceeds to step S205. If the determination is No, the process proceeds to step S209.

  In step S209, the duty of heater A + B is calculated. That is, Dda = 100, Ddb = (Wall−Wma) / Wmb × 100, and Ddc = 0 are calculated. On the other hand, in step S205, it is determined whether or not [Wall-Wma-Wmb> Wmc]. That is, in step S205, it is confirmed whether or not the total power Wall can be supplemented by the heater A + B + C. In this example, 3300-1067-1414 = 819 <1414, and the total output of heater A, heater B, and heater C is equal to or greater than the limit power. Therefore, it is necessary to limit the output of the heater C.

  In step S205, if the determination is Yes, the process proceeds to step S206. If the determination is No, the process proceeds to step S210. In step S206, Dda = 100, Ddb = 100, and Ddc = 100.

  In step S210, [Dda = 100, Ddb = 100, Ddc = (Wall-Wma-Wmb) / Wmc × 100] is calculated. Dda = 100, Ddb = 100, Ddc = (3300-1067-1414) / 1414 X100 = 57, and the limiting duty of the heater C is 68%.

  Subsequently, [maximum lighting duty, Max_duty = Dda + Ddb + Ddc] is obtained (step S207). As a result, in this example, Max_duty = 100 + 100 + 57 = 257.

  Next, a limitation example in the above-described heater lighting control will be described. The total lighting duty of the three heaters (the first heater 130 to the third heater 132) performed by the duty allocation is compared with the maximum lighting duty, and the total lighting duty of the three heaters exceeds the maximum lighting duty. If so, the maximum lighting duty is further allocated to control the lighting of the heater. This limits the heater lighting duty and output.

  When the lighting priority is changed while the fixing device 125 is operating, the heater on / off pattern (see Table 1) is changed (rotated). When duty allocation control is used, if the same lighting state continues for a long time, the temperature of the heater that is lit at 100% may increase. In particular, when the input voltage to the heater is high, the temperature in the fixing device 125 is likely to increase. Therefore, the heater lighting pattern is rotated at predetermined intervals. Thereby, the temperature rise of a heater can be suppressed. It is to be noted that the heater temperature is likely to rise during the passage of paper, that is, because the fixing device 125 is in operation, and the heater ON / OFF pattern during the passage of the transfer paper S being conveyed to the fixing device 125. Make changes.

For example, the following [1] to [4] are performed using the heater lighting pattern (see Table 1) as a rotation.
[1] The lighting pattern is changed for a certain period during which the fixing device 125 is operated and the recording paper S is passed.
[2] The lighting pattern is changed when the total lighting time of the three heaters (the first heater 130, the second heater 131, and the third heater 132) (the time during which the heater is turned on) exceeds a certain threshold. To do.
[3] The lighting pattern is changed when the number of printed sheets exceeds a preset threshold.
[4] Change the lighting pattern when starting a new printing.

  Next, a conventional example of the heater control described above and the present invention will be further described. First, conventional control will be described. Conventionally, it is assumed that three heaters are lit by allocation control. There are two lighting methods in the allocation control. One is a duty handling heater designation method, in which one heater for duty control is designated. Assuming that the three heaters are A, B, and C, the heater C is designated as a heater for duty control. On the other hand, there is a priority setting method for setting the lighting priority order of a plurality of heaters, in which the duty is filled in the order of heater A → heater B → heater C. This example is shown in Table 4.

  When the power supplies of the three heaters are the same, the linearity was maintained even if there was a difference in the amount of heat output by the heater with respect to the duty, but when there are multiple power supply systems and the respective voltages are different, the duty and The linearity of the heater output heat quantity cannot be maintained.

  In the case of duty control, as shown in FIGS. 8 and 9, there may be a step in the output with respect to the duty, and in the worst case, the output may reverse. Furthermore, as shown in FIGS. 10 and 11, in the case of setting the heater priority, the output may not be completely linear.

  On the other hand, this invention solves the problem of the conventional heater control mentioned above. As in the above-described embodiment, the present invention detects the voltage applied to the heater, corrects the output difference due to the voltage, and controls the heater to maintain the linearity of the output (see FIG. 12).

  Thus, according to the embodiment described above, the following first to third problems are solved. First, when the output voltages of the power sources are different, it becomes impossible to maintain the linearity of the output heat quantity and lighting of the heater. When the linearity cannot be maintained, the relationship between the duty and the heater output is reversed or the linearity is lost. When these occur, the followability of the temperature of the fixing belt 126 or the heating roller 129 is lost, and thus the print image quality such as uneven gloss is adversely affected. Therefore, in the present embodiment, the output linearity is provided by having a plurality of voltage detection units that detect voltages applied to a plurality of power supplies, and applying a correction for the voltage applied to each heater to the duty. By keeping the above, the above problems are solved.

  Secondly, as the image forming apparatus 100, it is necessary to perform voltage detection in order to keep the power to be used within the rating. However, since the power supply is made plural, power limitation using a plurality of voltage results is required. . In the present embodiment, as described above, the total duty of each heater is compared with the maximum lighting duty, and when the total duty of each heater exceeds the maximum lighting duty, the duty of each heater is again set. Allocation is performed. Thus, by providing a duty limit when each heater is turned on, the power can be within the rating.

  Thirdly, when the lighting control of the heater is performed, there may be a heater that continues to light at 100%. If the input voltage is high and the lamp is kept on for 100%, the temperature of the heater itself increases, which may lead to a reduction in the life of the heater itself. Therefore, in the present embodiment, the temperature rise can be suppressed by changing the lighting priority (see Table 1) while the heater is operating.

  By the way, a program executed by the image forming apparatus 100 of the present embodiment is provided by being incorporated in advance in the ROM 222 or the like. The above program is recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), etc. in a file that can be installed or executed. May be provided.

  Furthermore, the program executed in the present embodiment may be configured to be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. In addition, the program executed in the present embodiment may be configured to be provided or distributed via a network such as the Internet.

  The program executed in the present embodiment has a module configuration including the above-described units. As actual hardware, the CPU 221 reads out the program from the ROM 222 and executes the program, so that each unit is loaded onto the main storage device, and each unit is generated on the main storage device.

  The embodiment described above is presented as an example for realizing the present invention, and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Heating control part 11 Voltage detection process part 12 Temperature detection process part 100 Image forming apparatus 125 Fixing apparatus 126 Fixing belt 130 1st heater 131 2nd heater 132 3rd heater 200 Main control part 220 Fixing control part 231 1st voltage detection part 232 Second voltage detection unit 245 Temperature detection sensor 291 First power cable 292 Second power cable

Japanese Patent Laid-Open No. 2006-28262

Claims (12)

A plurality of voltage detectors that detect voltage values of a plurality of power supplies that supply power to a plurality of heat sources that heat a fixing member of a fixing device that fixes a toner image on a recording medium;
A heating control unit that performs duty control in order to light a plurality of the heat sources;
The heating control unit corrects the duty of at least one heat source of the plurality of heat sources based on the voltage value detected by the plurality of voltage detection units and the rated output value of the heat source. . The heating control device according to claim 1,
The heating control unit corrects a duty of at least one heat source of the plurality of heat sources so that a relationship between a total electric energy of the plurality of heat sources and a duty used in the duty control is linear. Heating control device. The heating control device according to claim 1 or 2,
The heating control unit sets the duty of the plurality of heat sources in descending order of the lighting priority of the plurality of heat sources set in advance, and is detected by the plurality of voltage detection units when changing the lighting priority. A heating control device that corrects the duty of at least one heat source of the plurality of heat sources based on the voltage value and the rated output value of the heat source. It is a heating control device according to any one of claims 1 to 3,
The heating control unit compares the total lighting duty with a maximum lighting duty that is a duty when the fixing device consumes the total power set, and the total lighting duty exceeds the maximum lighting duty. A heating control device, wherein the lighting duty of a plurality of heaters is allocated. The heating control device according to claim 3,
The heating control device, wherein the heating control unit changes the lighting priority in accordance with a time during which the fixing device is operating. The heating control device according to claim 3,
The heating control unit, wherein the lighting priority is changed according to a lighting time of the heat source. The heating control device according to claim 3,
The heating control device, wherein the lighting control unit changes the lighting priority order according to the number of the recording media on which the fixing device fixes. The heating control device according to claim 3,
The heating control device, wherein the heating control unit changes the lighting priority for each print job to be fixed by the fixing device. It is a heating control device according to any one of claims 1 to 8,
The heating control unit is characterized in that the duty control is performed by PID (Proportional Integral Differential) control. A fixing device for fixing a toner image to a recording medium using a fixing member;
The heating control device according to any one of claims 1 to 9, wherein the heating control of the fixing device is performed.
An image forming apparatus. A heating control method for a fixing device having a plurality of heat sources, which fixes a toner image on a recording medium using a fixing member,
A detection step in which a plurality of voltage detectors detect voltage values of a plurality of power supplies that supply power to a plurality of heat sources that heat the fixing member;
When the heating control unit turns on the plurality of heat sources by duty control, based on the voltage value detected by the plurality of voltage detection units and the rated output value of the heat source, at least one heat source of the plurality of heat sources. A heating control method comprising: a duty correction step for correcting the duty. Computer
A plurality of voltage detectors that detect voltage values of a plurality of power supplies that supply power to a plurality of heat sources that heat a fixing member of a fixing device that fixes a toner image on a recording medium;
In order to light a plurality of the heat sources, function as a heating control unit that performs duty control,
When functioning as the heating control unit, based on the voltage value detected by the plurality of voltage detection units and the rated output value of the heat source, function to correct the duty of at least one heat source of the plurality of heat sources. A program characterized by

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