JP6273857B2 - Power supply control apparatus, image forming apparatus, voltage output method, and program - Google Patents

Description

  The present invention relates to a power supply control device, an image forming apparatus, a voltage output method, and a program.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a uniformly charged image carrier, and the formed electrostatic latent image is developed with toner to form a toner image. The formed toner image Is transferred to a recording paper and fixed, thereby forming an image on the recording paper.

  By the way, recording paper usually has unevenness, and toner is not easily transferred to the concave portion compared to the convex portion. Therefore, when forming an image on recording paper having large unevenness, the toner is not transferred to the concave portion and the image is white. Density unevenness such as omission may occur.

  For this reason, for example, in Patent Document 1, a DC power supply and an AC power supply are connected in series, and a DC voltage is applied to the transfer portion in accordance with the size of the unevenness of the transfer object to transfer an image to the transfer object. There is disclosed a technique for switching by a relay whether to perform transfer or to apply a superimposed voltage obtained by superimposing a DC voltage and an AC voltage to a transfer unit to transfer an image to a transfer target.

  However, in the conventional technology as described above, it takes more time for the DC voltage output from the DC power supply to rise than in the case of a DC power supply alone due to the configuration of the power supply.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply control device, an image forming apparatus, a voltage output method, and a program that can shorten the voltage rise time.

In order to solve the above-described problems and achieve the object, a power supply control device according to one aspect of the present invention includes a DC power supply that outputs a DC voltage by switching between constant current control and constant voltage control, and a DC voltage. When a predetermined condition is satisfied, an AC power supply that outputs either a superimposed voltage on which an AC voltage is superimposed, or a DC voltage, a bypass capacitor that removes a voltage output from the AC power supply that is not applied to an application target, and A power supply control unit that switches the DC power supply from constant voltage control to constant current control, and a current detection unit that detects a DC current based on the DC voltage and outputs the DC current to the power supply control unit. Is switched to constant current control, the target signal output to the DC power supply is set to the target value based on the output value of the current detection unit, the target value of the predetermined DC current, and the target time determined in advance. It performed changes so as to approach gradually the target time is current overshoot when no change is being shorter than the convergence time to converge to the target value.

  According to the present invention, it is possible to shorten the voltage rise time.

FIG. 1 is a mechanical configuration diagram illustrating an example of a printing apparatus according to the present embodiment. FIG. 2 is a mechanical configuration diagram illustrating an example of the image forming unit of the present embodiment. FIG. 3 is a block diagram showing an example of the configuration of the secondary transfer power supply according to the present embodiment. FIG. 4 is a circuit diagram showing an example of the configuration of the secondary transfer power supply according to the present embodiment. FIG. 5 is a block diagram illustrating an example of the configuration of the engine control unit included in the printing apparatus according to the present embodiment. FIG. 6 is a diagram showing a comparative example with the present embodiment. FIG. 7 is a diagram illustrating an example of switching control according to the present embodiment. FIG. 8 is a diagram showing a comparative example with the present embodiment. FIG. 9 is a diagram illustrating a control example of the present embodiment. FIG. 10 is a flowchart illustrating an example of control performed by the DC power supply and the power supply control unit of the present embodiment. FIG. 11 is a circuit diagram illustrating an example of the configuration of the secondary transfer power supply according to the first modification. FIG. 12 is a block diagram illustrating an example of the configuration of the engine control unit of the third modification.

  Hereinafter, embodiments of a power supply control device, an image forming apparatus, a voltage output method, and a program according to the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the image forming apparatus of the present invention is an electrophotographic color printing apparatus, specifically, four colors of yellow (Y), magenta (M), cyan (C), and black (K). The case where the present invention is applied to a printing apparatus that forms an image by superimposing color component images on recording paper will be described as an example, but the present invention is not limited to this. The image forming apparatus of the present invention can be applied to both color and monochrome as long as it is an apparatus that forms an image by an electrophotographic method. For example, the image forming apparatus can be applied to an electrophotographic copying machine or a multifunction peripheral (MFP). Applicable. Note that a multifunction peripheral is a device having at least two functions among a printing function, a copying function, a scanner function, and a facsimile function.

  First, the configuration of the printing apparatus according to the present embodiment will be described.

  FIG. 1 is a mechanical configuration diagram illustrating an example of a printing apparatus 1 according to the present embodiment. As shown in FIG. 1, the printing apparatus 1 includes an image forming unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 60, support rollers 61 and 62, a secondary transfer unit counter roller (repulsive roller) 63, and the like. A secondary transfer roller 64, a paper cassette 70, a paper feed roller 71, a transport roller pair 72, a fixing device 90, and a secondary transfer power source 200.

  As shown in FIG. 1, the image forming units 10Y, 10M, 10C, and 10K are arranged in the order of the image forming units 10Y, 10M, 10C, and 10K from the upstream side in the moving direction (arrow a direction) of the intermediate transfer belt 60. Arranged along the intermediate transfer belt 60.

  FIG. 2 is a mechanical configuration diagram illustrating an example of the image forming unit 10Y according to the present embodiment. As shown in FIG. 2, the image forming unit 10Y includes a photosensitive drum 11Y, a charging device 20Y, a developing device 30Y, a primary transfer roller 40Y, and a cleaning device 50Y. The image forming unit 10Y and the irradiation device (not shown) perform yellowing on the photosensitive drum 11Y by performing an image forming process (charging process, irradiation process, developing process, transfer process, and cleaning process) on the photosensitive drum 11Y. The toner image (color component image) is formed and transferred to the intermediate transfer belt 60.

  The image forming units 10M, 10C, and 10K all have the same components as the image forming unit 10Y. The image forming unit 10M forms a magenta toner image by performing an image forming process. The image forming unit 10C forms a cyan toner image by performing an image forming process, and the image forming unit 10K forms a black toner image by performing an image forming process. Therefore, in the following, description will be mainly given of the constituent elements of the image forming unit 10Y, and the constituent elements of the image forming units 10M, 10C, and 10K are denoted by Y added to the reference numerals of the constituent elements of the image forming unit 10Y. Instead, M, C, and K are added (see FIG. 1), and description thereof is omitted.

  The photoreceptor drum 11Y is an image carrier and is rotationally driven in the direction of arrow b by a photoreceptor drum driving device (not shown). The photoreceptor drum 11Y is an organic photoreceptor having an outer diameter of 60 mm, for example. Similarly, the photosensitive drums 11M, 11C, and 11K are rotationally driven in the direction of arrow b by a photosensitive drum driving device (not shown).

  The black photosensitive drum 11K and the color photosensitive drums 11Y, 11M, and 11C may be driven to rotate independently. Thus, when forming a monochrome image, only the black photosensitive drum 11K is rotationally driven, and when forming a color image, the photosensitive drums 11Y, 11M, 11C, and 11K are simultaneously rotationally driven. it can.

  First, in the charging step, the charging device 20Y charges the surface of the photosensitive drum 11Y that is being rotationally driven. Specifically, the charging device 20Y applies a voltage obtained by superimposing an AC voltage on a DC voltage to a charging roller (not shown) that is, for example, a roller-shaped conductive elastic body. As a result, the charging device 20Y directly discharges between the charging roller and the photosensitive drum 11Y, and charges the photosensitive drum 11Y to a predetermined polarity, for example, a negative polarity.

  Subsequently, in the irradiation step, an irradiation device (not shown) irradiates the charged surface of the photosensitive drum 11Y with the laser light L that has been light-modulated to form an electrostatic latent image on the surface of the photosensitive drum 11Y. As a result, the portion where the absolute value of the potential of the surface portion of the photosensitive drum 11Y is lowered by the irradiation with the laser beam L becomes an electrostatic latent image (image portion), and the absolute value of the potential is kept high without being irradiated with the laser beam L. The sagging part becomes the background part.

  Subsequently, in the developing process, the developing device 30Y develops the electrostatic latent image formed on the photoreceptor drum 11Y with yellow toner, and forms a yellow toner image on the photoreceptor drum 11Y.

  The developing device 30Y includes a storage container 31Y, a developing sleeve 32Y stored in the storage container 31Y, and a screw member 33Y stored in the storage container 31Y. The storage container 31Y stores a two-component developer having yellow toner and a carrier. The developing sleeve 32Y is a developer carrier, and is disposed so as to face the photosensitive drum 11Y through the opening of the storage container 31Y. The screw member 33Y is a stirring member that conveys the developer while stirring. The screw member 33Y is disposed on the developer supply side on the developing sleeve side and on the receiving side that receives supply from a toner supply device (not shown), and is rotatably supported by the storage container 31Y by a bearing member (not shown). Yes.

  Subsequently, in the transfer process, the primary transfer roller 40Y transfers the yellow toner image formed on the photosensitive drum 11Y to the intermediate transfer belt 60. Note that a small amount of untransferred toner remains on the photosensitive drum 11Y even after the toner image is transferred.

  The primary transfer roller 40Y is an elastic roller having a conductive sponge layer, for example, and is disposed so as to be pressed against the photosensitive drum 11Y from the back surface of the intermediate transfer belt 60. The elastic roller is applied with a constant current controlled bias as a primary transfer bias. For example, the primary transfer roller 40Y has an outer shape of 16 mm, a mandrel diameter of 10 mm, and a sponge layer resistance R of about 3E7Ω. The resistance R of the sponge layer is determined from the current I flowing when a voltage V of 1000 V is applied to the mandrel of the primary transfer roller 40Y with a grounded metal roller having an outer diameter of 30 mm pressed by 10 N, from the current I. It is a value calculated using the law (R = V / I).

  Subsequently, in the cleaning process, the cleaning device 50Y wipes off the untransferred toner remaining on the photosensitive drum 11Y. The cleaning device 50Y includes a cleaning blade 51Y and a cleaning brush 52Y. The cleaning blade 51Y cleans the surface of the photoconductive drum 11Y while being in contact with the photoconductive drum 11Y from the counter direction with respect to the rotation direction of the photoconductive drum 11Y. The cleaning brush 52Y cleans the surface of the photosensitive drum 11Y while being in contact with the photosensitive drum 11Y while rotating in the direction opposite to the rotation direction of the photosensitive drum 11Y.

  Returning to FIG. 1, the intermediate transfer belt 60 is an endless belt wound around a plurality of rollers such as support rollers 61 and 62 and a secondary transfer unit facing roller 63, and one of the support rollers 61 and 62 is rotationally driven. As a result, it moves endlessly in the direction of arrow a. First, a yellow toner image is transferred to the intermediate transfer belt 60 by the image forming unit 10Y. Subsequently, the magenta toner image is transferred by the image forming unit 10M, the cyan toner image is transferred by the image forming unit 10C, and the image forming unit 10K is pressed. Black toner images are sequentially superimposed and transferred. As a result, a full-color toner image (full-color image) is formed on the intermediate transfer belt 60. The intermediate transfer belt 60 conveys the formed full-color toner image between the secondary transfer portion facing roller 63 and the secondary transfer roller 64. For example, the intermediate transfer belt 60 has a thickness of 20 to 200 μm (preferably about 60 μm) and a volume resistivity of 6.0 to 13.0 Log Ωcm (preferably 7.5 to 12.5 Log Ωcm, more preferably about 9 Log Ωcm) and an endless carbon-dispersed polyimide resin having a surface resistivity of 9.0 to 13.0 Log Ωcm (preferably 10.0 to 12.0 Log Ωcm). The volume resistivity is a resistance measurement value at 100 V, 10 sec, manufactured by Mitsubishi Chemical Hiresta HRS probe, and the surface resistivity is a resistance measurement value at 500 V, 10 sec, manufactured by Mitsubishi Chemical Hiresta HRS probe. The support roller 62 is grounded.

  In the paper cassette 70, a plurality of recording papers are accommodated on each tray (not shown). It is assumed that the recording paper has a different paper type and size for each tray. In the present embodiment, the recording paper is, for example, plain paper or a highly rugged resack paper, but is not limited to this.

  The paper feed roller 71 is in contact with the recording paper P positioned at the top of the tray of the paper cassette 70 and feeds the recording paper P in contact therewith.

  The transport roller pair 72 transports the recording paper P fed by the paper feed roller 71 between the secondary transfer portion facing roller 63 and the secondary transfer roller 64 (in the direction of arrow c) at a predetermined timing.

  The secondary transfer portion facing roller 63 and the secondary transfer roller 64 are conveyed by the intermediate transfer belt 60 at a secondary transfer nip (not shown) between the secondary transfer portion facing roller 63 and the secondary transfer roller 64. The full-color toner image is collectively transferred onto the recording paper P transported by the transport roller pair 72.

  The secondary transfer portion facing roller 63 is, for example, a conductive NBR rubber layer having an outer shape of 24 mm and a mandrel diameter of 16 mm. In addition, the value of resistance R of the conductive NBR rubber layer is 6.0 to 12.0 LogΩ (or SUS), and preferably 4.0 LogΩ. The secondary transfer roller 64 is, for example, a conductive NBR rubber layer having an outer shape of 24 mm and a mandrel diameter of 14 mm. In addition, the value of resistance R of the conductive NBR rubber layer is 6.0 to 8.0 LogΩ, and preferably 7.0 to 8.0 LogΩ. The volume resistance of the secondary transfer roller 64 is a resistance measurement value measured by rotation measurement. Weight: 5 N / one side, bias application: 1 KV applied to the transfer roller shaft, resistance of one roller rotation measured during 1 min measurement, average The value is a volume resistance.

  A secondary transfer power supply 200 for transfer bias is connected to the secondary transfer portion facing roller 63. The secondary transfer power supply 200 (an example of a power supply device) applies a voltage to the secondary transfer unit facing roller 63 in order to transfer a full color toner image onto the recording paper P at the secondary transfer nip. Specifically, the secondary transfer power supply 200 applies only a DC voltage (hereinafter sometimes referred to as “DC bias”) to the secondary transfer unit facing roller 63 according to a user setting, A superimposed voltage (hereinafter sometimes referred to as “superimposed bias”) superimposed with an AC voltage is applied to the secondary transfer unit facing roller 63. As a result, a potential difference is generated between the secondary transfer portion facing roller 63 and the secondary transfer roller 64, and a voltage is generated in which the toner travels from the intermediate transfer belt 60 to the recording paper P side. Can be transferred to. Here, the potential difference in the present embodiment is (potential of the secondary transfer portion facing roller 63) − (potential of the secondary transfer roller 64).

  The fixing device 90 fixes the full-color toner image on the recording paper P by heating and pressing the recording paper P on which the full-color toner image is transferred. Then, the recording paper P on which the full-color toner image is fixed is discharged outside the printing apparatus 1.

  FIG. 3 is a block diagram showing an example of the configuration of the secondary transfer power supply 200 of the present embodiment. As illustrated in FIG. 3, the printing apparatus 1 includes a power supply control unit 342 and a secondary transfer power supply 200. The secondary transfer power supply 200 includes a DC power supply 210, an AC power supply 240, and an output abnormality detection unit 270. The DC power source 210 is a power source for toner transfer, and includes a DC output control unit 211, a DC drive unit 212, a DC voltage transformer 213, and a DC output detection unit 214. The AC power supply 240 is a power supply for toner vibration, and includes an AC output control unit 241, an AC drive unit 242, an AC voltage transformer 243, and an AC output detection unit 244. The power supply control unit 342 controls the secondary transfer power supply 200 and can be realized by, for example, a CPU (Central Processing Unit).

  The DC output control unit 211 receives a DC_PWM signal (DC bias output signal) that controls the output level of the DC voltage from the power supply control unit 342, and the DC output detection unit 214 receives the DC output detection unit 214. The output value of the DC voltage transformer 213 detected by is input. Then, the DC output control unit 211 is based on the duty ratio of the input DC_PWM signal and the output value of the DC voltage transformer 213 so that the output value of the DC voltage transformer 213 becomes the output value indicated by the DC_PWM signal. The driving of the DC voltage transformer 213 is controlled via the DC driver 212.

  The DC output control unit 211 receives a switching signal for instructing switching between constant current control and constant voltage control from the power supply control unit 342, and the DC output control unit 211 receives the switching signal according to the input switching signal. Switch between constant current control and constant voltage control. In the present embodiment, the DC power source 210 mainly performs constant current control in order to keep the toner transfer rate constant, but may also perform constant voltage control in order to shorten the rise time of the DC voltage. In the case of constant current control, the DC output control unit 211 uses the DC voltage transformer 213 via the DC drive unit 212 so that the current value of the DC voltage transformer 213 becomes the current value indicated by the DC_PWM signal. Control the drive. Further, in the case of constant voltage control, the DC output control unit 211 uses the DC voltage transformer 213 via the DC drive unit 212 so that the voltage value of the DC voltage transformer 213 becomes the voltage value indicated by the DC_PWM signal. Control the drive.

  The DC drive unit 212 drives the DC voltage transformer 213 according to the control from the DC output control unit 211.

  The DC voltage transformer 213 is driven by the DC driving unit 212 and outputs a negative DC high voltage output (DC bias output).

  The DC output detection unit 214 periodically detects the output value of the DC high voltage output of the DC voltage transformer 213 and outputs it to the DC output control unit 211. Further, the DC output detection unit 214 outputs the detected output values to the power supply control unit 342 as an FB_DCV signal and an FB_DCC signal (feedback signal). The FB_DCV signal indicates an output value of a direct current high voltage, and the FB_DCC signal indicates an output value of a direct current based on the direct current high voltage. This is because the duty of the DC_PWM signal is controlled in the power supply control unit 342 so that the transferability does not deteriorate due to the environment and load. In the present embodiment, when the DC output control unit 211 performs constant current control, the power supply control unit 342 controls the value of the DC_PWM signal based on the FB_DCC signal, which will be described in detail later.

  The AC output control unit 241 detects an AC_PWM signal (AC bias output signal) for controlling the output level of the AC voltage from the power supply control unit 342, and detects the AC output detection unit 244 from the AC output detection unit 244. The output value of the AC voltage transformer 243 is input. The AC output control unit 241 then sets the output value of the AC voltage transformer 243 to the output value indicated by the AC_PWM signal based on the duty ratio of the input AC_PWM signal and the output value of the AC voltage transformer 243. The driving of the AC voltage transformer 243 is controlled via the AC driving unit 242.

  The AC driver 242 receives an AC_CLK signal that controls the output frequency of the AC voltage. The AC driving unit 242 drives the AC voltage transformer 243 based on the control from the AC output control unit 241 and the AC_CLK signal. The AC driving unit 242 drives the AC voltage transformer 243 based on the AC_CLK signal, thereby controlling the output waveform generated by the AC voltage transformer 243 to an arbitrary frequency indicated by the AC_CLK signal.

  The AC voltage transformer 243 is driven by the AC drive unit 242 to generate an AC voltage, and generates a superimposed voltage by superimposing the generated AC voltage and a DC high voltage output from the DC voltage transformer 213. The generated superimposed voltage (superimposed bias) is output (applied) to the secondary transfer unit facing roller 63. The AC voltage transformer 243 outputs (applies) the DC high voltage (DC bias) output from the DC voltage transformer 213 to the secondary transfer unit facing roller 63 when the AC voltage is not generated. The voltage (superimposed bias or DC bias) output to the secondary transfer portion facing roller 63 is then fed back into the DC power supply 210 via the secondary transfer roller 64.

  The AC output detection unit 244 detects the output value of the AC voltage of the AC voltage transformer 243 and outputs it to the AC output control unit 241. In addition, the AC output detection unit 244 outputs the detected output value to the power supply control unit 342 as an FB_AC signal (feedback signal). This is because the power control unit 342 controls the duty of the AC_PWM signal so that the transferability does not deteriorate due to the environment or load.

  In the present embodiment, the AC power supply 240 performs constant voltage control. However, the present invention is not limited to this, and constant current control may be performed.

  Further, the AC voltage generated by the AC voltage transformer 243 (AC power supply 240) may be either a sine wave or a rectangular wave, but in the present embodiment, it is a short pulse rectangular wave. This is because the waveform of the alternating voltage can be contributed to the improvement of the image quality by making it a short pulse rectangular wave.

  The output abnormality detection unit 270 is disposed on the output line of the secondary transfer power supply 200, and outputs an SC signal to the power supply control unit 342 when an output abnormality occurs due to a ground fault or the like of the electric wire. Thereby, control for stopping the high voltage output from the secondary transfer power supply 200 by the power supply control unit 342 becomes possible.

  FIG. 4 is a circuit diagram showing an example of the configuration of the secondary transfer power supply 200 of the present embodiment.

  The DC power supply 210 receives a DC (−) _ PWM signal and a switching signal from the power supply control unit 342 and inputs to the switching circuit 229. When the switching signal instructs switching to constant voltage control (CV) (in this embodiment, when the switching signal is High), the switching circuit 229 sends the DC (−) _ PWM signal to the current control circuit 222 (comparator). When the switching signal instructs to switch to constant current control (CC) (in this embodiment, when the switching signal is Low), the DC (−) _ PWM signal is output to the voltage control circuit 221 (comparator). .

  The DC (−) _ PWM signal output to the current control circuit 222 is integrated and input to the current control circuit 222. The value of the integrated DC (−) _ PWM signal becomes a reference voltage in the current control circuit 222. The direct current detection circuit 228 periodically detects the direct current output from the direct current power supply 210 on the output line of the secondary transfer power supply 200, and inputs the output value of the detected direct current to the current control circuit 222. The detected output value of the direct current is fed back to the power supply control unit 342 as an FB_DCC (−) signal. The current control circuit 222 actively drives the DC drive circuit 223 of the DC high-voltage transformer when the DC current is smaller than the reference voltage, and DC drive of the DC high-voltage transformer when the DC current is larger than the reference voltage. The driving of the circuit 223 is restricted. As a result, the DC power supply 210 ensures constant current.

  The DC (−) _ PWM signal output to the voltage control circuit 221 is integrated and input to the voltage control circuit 221. The value of the integrated DC (−) _ PWM signal becomes a reference voltage in the voltage control circuit 221. The DC voltage detection circuit 226 detects the DC voltage output from the DC power supply 210 and inputs the output value of the detected DC voltage to the voltage control circuit 221. When the output value of the DC voltage is smaller than the reference voltage, the voltage control circuit 221 actively drives the DC drive circuit 223 of the DC high-voltage transformer, and the output value of the DC voltage reaches the reference voltage (upper limit). At this time, the driving of the DC drive circuit 223 of the DC high-voltage transformer is restricted. Thereby, the DC power supply 210 ensures constant voltage characteristics. The DC voltage detection circuit 227 feeds back the output value of the DC voltage detected by the DC voltage detection circuit 226 to the power supply control unit 342 as an FB_DCV (−) signal.

  By driving the direct current drive circuit 223 according to the control of the current control circuit 222 and the voltage control circuit 221, the primary side winding N1_DC (−) 224 of the direct current high voltage transformer and the secondary side winding N2_DC (−) of the direct current high voltage transformer. The output generated at 225 is smoothed by a diode and a capacitor, then input as a DC voltage from the AC power supply input unit 257 to the AC power supply 240, and applied to the secondary winding N2_AC256 of the AC high-voltage transformer.

  The AC power supply 240 receives an AC_PWM signal from the power supply controller 342 and inputs it to the voltage control circuit 251 (comparator). The value of the input AC_PWM signal becomes a reference voltage in the voltage control circuit 251. Further, the AC voltage detection circuit 262 predicts the output value of the AC voltage from the mutual induction voltage generated by the primary side winding N3_AC255 of the AC high voltage transformer, and inputs the predicted output value of the AC voltage to the voltage control circuit 251. This is because it is difficult to detect only the output (AC voltage) of the AC power supply 240 itself on the output line of the secondary transfer power supply 200 because the AC voltage is superimposed on the DC voltage. The voltage control circuit 251 actively drives the AC drive circuit 253 of the AC high voltage transformer when the AC voltage is smaller than the reference voltage, and AC drive of the AC high voltage transformer when the AC voltage is larger than the reference voltage. The driving of the circuit 253 is restricted. Thereby, AC power supply 240 has secured constant voltage property.

  The AC current detection circuit 260 detects an AC current on the low voltage side of the AC bypass capacitor 259 that is an output line of the secondary transfer power supply 200, and outputs the detected AC current output value to the current control circuit 252 (comparator). input. The current control circuit 252 regulates driving of the AC drive circuit 253 of the AC high-voltage transformer when the output value of the AC current reaches the upper limit. Further, the AC current detection circuit 261 feeds back the detected output value of the AC current to the power supply control unit 342 as an FB_AC signal.

  The AC drive circuit 253 of the AC high voltage transformer is driven according to the AND logic of the AC_CLK signal input from the power supply control unit 342 and the voltage control circuit 251 and the current control circuit 252 to generate an output having the same cycle as AC_CLK.

  The AC voltage generated by the primary side winding N1_AC254 of the AC high-voltage transformer by being driven by the AC driving circuit 253 is superimposed on the DC voltage applied to the secondary side winding N2_AC256, and is output from the high-voltage output unit 258. The superimposed voltage is output (applied) to the secondary transfer portion facing roller 63. However, when the AC power supply 240 is not driven, the DC voltage applied to the secondary winding N2_AC256 is directly output (applied) from the high voltage output unit 258 to the secondary transfer unit facing roller 63.

  The output abnormality detection circuit 271 detects an output abnormality due to a ground fault or the like on the output line of the secondary transfer power supply 200 and outputs an SC signal to the power supply control unit 342.

  Here, the property of the AC bypass capacitor 259 in the secondary transfer power supply 200 will be described.

  The AC bypass capacitor 259 removes a voltage that has not been output (applied) to the secondary transfer unit facing roller 63 (an example of an application target) from the voltage (DC voltage or superimposed voltage) output from the AC power supply 240. belongs to. Thereby, it is possible to prevent the superimposed voltage that has not been output (applied) to the secondary transfer unit facing roller 63 from flowing into the DC power supply 210 and to suppress loss in the AC power supply 240.

  However, since no electric charge is accumulated in the AC bypass capacitor 259 when the DC power supply 210 is activated, the impedance of the AC bypass capacitor 259 is very low, and the DC voltage output from the DC power supply 210 is the AC voltage. It will flow into the bypass capacitor 259. For this reason, the DC power supply 210 cannot supply sufficient power to the secondary transfer unit facing roller 63 until the electric charge is accumulated in the AC bypass capacitor 259, and the rise time is delayed.

  For this reason, in this embodiment, the DC power supply 210 accumulates charges in the AC bypass capacitor 259 at an early stage by performing constant voltage control when the DC voltage is raised, thereby advancing the rise time of the DC voltage. Therefore, according to the present embodiment, it is possible to shorten the power-on time and the paper interval, and it is possible to reduce power consumption and improve printing productivity.

  FIG. 5 is a block diagram illustrating an example of the configuration of the engine control unit 300 included in the printing apparatus 1 of the present embodiment. As shown in FIG. 5, the printing apparatus 1 includes an engine control unit 300, a secondary transfer power source 200, and a secondary transfer unit facing roller 63.

  The engine control unit 300 performs engine control, for example, control related to image formation, and includes an I / O control unit 310, a RAM (Random Access Memory) 320, a ROM (Read Only Memory) 330, and a CPU 340. Is provided.

  The I / O control unit 310 controls input / output of various signals, and controls input / output of signals exchanged with the secondary transfer power supply 200.

  The RAM 320 is a volatile storage device (memory), and is used as a work area for the CPU 340 and the like.

  The ROM 330 (an example of a storage unit) is a non-volatile storage device (memory) for reading, and stores various programs executed by the printing apparatus 1 and data used for various processes executed by the printing apparatus 1. To do. The ROM 330 may be realized by a flash memory or the like so that writing can be performed. For example, the ROM 330 specifies specific information for specifying a constant voltage switching timing for causing the DC power source 210 to switch to constant voltage control and a constant current switching timing for causing the DC power source 210 to switch to constant current control (an example of a predetermined timing). Remember. The identification information specifies, for example, a constant voltage switching timing and a constant voltage switching timing based on a printing start reference signal indicating a printing start reference.

  The CPU 340 accepts an input of a print start reference signal or accepts user settings from an operation unit (not shown) such as an operation panel. For example, when the recording paper is plain paper, the user inputs “high voltage output with only DC bias” as the user setting of the high voltage output from the operation unit, and when the recording paper is a lazac paper with large unevenness, Then, “High voltage output with superimposed bias” is input as the user setting of the high voltage output. Then, the CPU 340 causes the secondary transfer power source 200 to output a high voltage according to the user setting via the I / O control unit 310. The CPU 340 includes a power control unit 342.

  The power supply control unit 342 controls the output of the DC voltage by the DC power supply 210 based on the specific information stored in the ROM 330 when causing the secondary transfer power supply 200 to perform high voltage output (DC voltage output or superimposed voltage output). To do. Specifically, the power supply control unit 342 causes the DC power supply 210 to switch to constant voltage control and constant current control based on the specific information.

  Hereinafter, referring to FIG. 6 and FIG. 7, when the DC power source 210 outputs a DC voltage only by constant current control, the DC power source 210 switches between constant voltage control and constant current control and outputs DC voltage. The difference from the case of performing is described.

  FIG. 6 is a diagram illustrating an example of the rising timing of the DC bias when the DC power source 210 outputs the DC bias only by constant current control, and is a diagram illustrating a comparative example with the present embodiment. FIG. 7 is a diagram illustrating an example of the rising timing of the DC bias when the DC power supply 210 performs switching between constant voltage control and constant current control to output a DC bias, and illustrates an example of switching control according to the present embodiment. FIG.

  Note that the term “rise” refers to a state in which there is a potential difference regardless of plus or minus from a state without potential difference (0 kV). Further, for reference, the falling means that a state having a potential difference regardless of plus or minus changes from a state having no potential difference (0 kV).

  In the example shown in FIG. 6, it takes 200 ms for the bias value to reach the target value (−10 kV) after the DC power supply 210 starts outputting the DC bias.

  This is because, as described above, the DC bias output from the DC power supply 210 flows into the AC bypass capacitor 259 until the electric charge is accumulated in the AC bypass capacitor 259. In particular, in the case of constant current control, the upper limit of the amount of charge output as a DC bias is determined by the current value, so that it takes time until the charge is accumulated in the AC bypass capacitor 259.

  On the other hand, in the example shown in FIG. 7, when the CPU 340 accepts the input of the print start reference signal, the power supply control unit 342 measures the elapsed time, refers to the specific information, and refers to the constant voltage switching timing and the constant current switching timing. Is identified.

  Then, when the constant voltage switching timing comes, the power supply control unit 342 outputs a switching signal instructing switching from the I / O control unit 310 to the DC power supply 210 to the constant voltage control (CV). When a switching signal instructing switching from the I / O control unit 310 to constant voltage control (CV) is input, the DC power supply 210 switches from constant current control to constant voltage control.

  Subsequently, the power supply control unit 342 stops the output of the reverse bias output signal from the I / O control unit 310 to the DC power supply 210 at the timing when the switching from the constant current control to the constant voltage control of the DC power supply 210 is completed, A DC bias output signal is output from the I / O control unit 310 to the DC power supply 210. When a DC bias output signal is input from the I / O control unit 310, the DC power supply 210 performs constant voltage control and starts outputting a DC bias.

  Also in this case, the DC bias output from the DC power supply 210 flows into the AC bypass capacitor 259 until the electric charge is accumulated in the AC bypass capacitor 259, but is output as a DC bias in the case of constant voltage control. Since the amount of charge can theoretically be infinite, the charge can be accumulated in the AC bypass capacitor 259 in a short time.

  Subsequently, at the constant current switching timing, the power supply control unit 342 outputs a switching signal instructing switching from the I / O control unit 310 to the DC power supply 210 to the constant current control (CC). The constant current switching timing is a timing at which the charge accumulation in the AC bypass capacitor 259 is completed, and is obtained from experimental data or the like. When a switching signal instructing switching from the I / O control unit 310 to constant current control (CC) is input to the DC power supply 210 (an example of establishment of a predetermined condition), switching from constant voltage control to constant current control is performed. Output DC bias.

  In the example shown in FIG. 7, since the DC bias is output by switching between the constant voltage control and the constant current control, the bias value is the target value in 50 ms after the DC power supply 210 starts the output of the DC bias. (−10 kV), and the rise time of the DC bias can be shortened.

  Further, when the power source control unit 342 causes the DC power source 210 to switch from constant voltage control to constant current control, the output value of the DC current detected by the DC output detection unit 214 (DC current detection circuit 228) is determined in advance. Based on the target value of the direct current and the predetermined target time, the target signal is changed so as to gradually approach the target value, and is output to the DC power source 210. The DC output detection unit 214 (DC current detection circuit 228) is an example of a current detection unit.

  That is, when the power supply control unit 342 causes the DC power supply 210 to switch to the constant current control, every time the FB_DCC (−) signal is input, the value of the FB_DCC (−) signal, the predetermined DC (− ) Based on the value of the _PWM signal and a predetermined target time, the value of the DC (−) _ PWM signal is changed so as to approach the target value, and is output to the DC power supply 210. Is output. As a result, the value of the DC (−) _ PWM signal output to the DC power supply 210 is changed so as to gradually approach the target value. In the present embodiment, the example in which the value of the DC (−) _ PWM signal is changed every time the FB_DCC (−) signal is input has been described. However, the present invention is not limited to this, and for example, the FB_DCC (−) signal. The value of the DC (−) _ PWM signal may be changed in a predetermined cycle longer than the cycle in which the signal is input.

  Specifically, in the power supply control unit 342, the output value of the DC current detected next by the DC output detection unit 214 (DC current detection circuit 228) becomes the current value indicated by the changed DC (−) _ PWM signal. Thus, the DC power supply 210 is caused to output a DC voltage.

  Hereinafter, referring to FIGS. 8 and 9, the DC bias of the DC power supply 210 when the power supply control unit 342 performs feedback using the FB_DCC (−) signal or the like after the DC power supply 210 is switched to the constant current control. And the output of the DC bias of the DC power supply 210 when the power supply control unit 342 does not perform feedback using the FB_DCC (−) signal or the like will be described.

  FIG. 8 is a diagram illustrating an example of a DC bias output of the DC power supply 210 when the power supply control unit 342 does not perform feedback using the FB_DCC (−) signal or the like after the DC power supply 210 is switched to constant current control. It is a figure which shows the comparative example with this embodiment. FIG. 9 is a diagram illustrating an example of the output of the DC bias of the DC power supply 210 when the power supply control unit 342 performs feedback using the FB_DCC (−) signal or the like after the DC power supply 210 is switched to constant current control. It is a figure which shows the example of control of this embodiment. Note that the alternate long and short dash line in the graph indicates the DC bias voltage value, and the solid line indicates the DC bias voltage value.

  In the example shown in FIGS. 8 and 9, the DC bias current value suddenly decreases before the DC power supply 210 is switched from constant voltage control to constant current control. Therefore, immediately after switching to the constant current control, the power supply control unit 342 sets a target value of the DC bias current value as the value of the DC (−) _ PWM signal, and outputs the DC bias to the DC power supply 210. As shown in FIG. 8, the DC bias current value overshoots the target value and then gradually converges to the target value.

  Here, how much the DC bias current value overshoots and the convergence time until convergence to the target value depends on the use environment of the printing apparatus 1. A necessary DC bias value cannot be ensured at the time of image transfer, resulting in deterioration of image quality.

  On the other hand, in the example illustrated in FIG. 9, the power supply control unit 342 is input immediately after switching to the constant current control without setting the target value of the DC bias current value as the value of the DC (−) _ PWM signal. The value of the FB_DCC (−) signal, the target value of the DC bias current value, and a value based on a predetermined target time are set, and the DC power supply 210 outputs the DC bias. Thereafter, the power supply control unit 342 sets the value of the DC (−) _ PWM signal in the process every time the FB_DCC (−) signal is input, and causes the DC power supply 210 to output a DC bias.

  As described above, in the example shown in FIG. 9, the current value of the DC bias is gradually approached to the target value from the current value immediately before switching to the constant current control, so that the current value as in the example shown in FIG. No overshoot occurs. For this reason, in the example shown in FIG. 9, the DC bias current value can be controlled to the target value by the target time without depending on the use environment of the printing apparatus 1, and the DC bias necessary for image transfer Can be secured during image transfer.

  In the example shown in FIG. 9, if the value of the DC (−) _ PWM signal updated at any time is set to reach the target value by the target time, a non-linearity is formed as shown in FIG. Even if it sets, you may set so that linearity may be formed. For example, the power supply control unit 342 may set the value of the DC (−) _ PWM signal by PI control. Specifically, the power supply control unit 342 adds the value of the FB_DCC (−) signal to the target value of the DC bias current value, subtracts the differential value of the value of the FB_DCC (−) signal, and applies a gain. May be set to the value of the DC (−) _ PWM signal. The gain may be determined according to the target time.

  Next, the operation of the printing apparatus according to the present embodiment will be described.

  FIG. 10 is a flowchart illustrating an example of control performed by the DC power supply 210 and the power supply control unit 342 of the present embodiment.

  First, the power supply control unit 342 starts outputting a reverse bias output signal from the I / O control unit 310 to the DC power supply 210 (step S101).

  Subsequently, the power control unit 342 refers to the specific information and waits until the constant voltage switching timing is reached (No in step S103).

  Subsequently, when the constant voltage switching timing comes (Yes in step S103), the power supply control unit 342 outputs a switching signal instructing switching from the I / O control unit 310 to the DC power supply 210 to the constant voltage control (CV). . When a switching signal instructing switching from the I / O control unit 310 to constant voltage control (CV) is input, the DC power supply 210 switches from constant current control to constant voltage control (step S105).

  Subsequently, the power supply control unit 342 stops the output of the reverse bias output signal from the I / O control unit 310 to the DC power supply 210 at the timing when the switching from the constant current control to the constant voltage control of the DC power supply 210 is completed ( In step S107, a DC bias output signal is output from the I / O control unit 310 to the DC power supply 210 (step S109). When a DC bias output signal is input from the I / O control unit 310, the DC power supply 210 performs constant voltage control and starts outputting a DC bias.

  Subsequently, the power control unit 342 refers to the specific information and waits until the constant current switching timing is reached (No in step S111).

  Subsequently, when the constant current switching timing comes (Yes in step S111), the power supply control unit 342 outputs a switching signal instructing switching from the I / O control unit 310 to the DC power supply 210 to the constant current control (CC). . When a switching signal instructing switching from the I / O control unit 310 to constant current control (CC) is input, the DC power supply 210 switches from constant voltage control to constant current control and outputs a DC bias (step) S113). Specifically, every time the FB_DCC (−) signal is input, the power supply control unit 342 receives the value of the FB_DCC (−) signal, the value of the predetermined DC (−) _ PWM signal, and the predetermined value. Since the value of the DC (−) _ PWM signal is changed based on the target time and output to the DC power supply 210, the DC power supply 210 outputs a DC bias based on the DC (−) _ PWM signal after the change. .

  As described above, in the present embodiment, after the constant voltage control is performed and the output of the DC voltage is started, the DC voltage is output by switching to the constant current control. For this reason, according to this embodiment, even if the power supply configuration is such that the DC voltage output from the DC power source flows into the bypass capacitor until the electric charge is accumulated in the bypass capacitor, it is early in the bypass capacitor. The charge can be accumulated in the DC voltage, and the rise time of the DC voltage can be shortened. As a result, the power-on time can be shortened and the interval between sheets can be shortened, so that power consumption can be reduced and printing productivity can be improved.

  Furthermore, in this embodiment, the DC power supply 210 detects a DC current based on the output DC voltage, feeds back the output value of the detected DC current to the power supply control unit 342, and the power supply control unit 342 starts from the constant voltage control. After switching to the current control, the target value is changed based on the output value fed back, the predetermined target value of DC current, and the predetermined target time, and the DC power supply 210 is changed based on the changed target value. To output a DC voltage. For this reason, according to this embodiment, after switching from constant voltage control to constant current control, no overshoot of the current value occurs, and the target value is controlled by the target time without depending on the use environment of the printing apparatus 1. Therefore, a DC bias value necessary for image transfer can be secured at the time of image transfer. If the current value overshoots, the overshooted current value varies depending on the environment, so the convergence time until the overshooted current value converges to the target value also varies depending on the environment, and the convergence time exceeds the expected value. May end up. In this case, the value of the DC voltage necessary for image transfer cannot be ensured at the time of image transfer, resulting in deterioration of image quality.

  As described above, according to the present embodiment, both shortening of the voltage rise time and prevention of deterioration of the image quality can be achieved.

(Program structure)
The program executed by the power supply control unit 342 of the above embodiment is provided by being incorporated in advance in a ROM or the like.

  Further, the program executed by the power control unit 342 of the above embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program executed by the power control unit 342 of the above embodiment may be provided or distributed via a network such as the Internet.

  In addition, the program executed by the power control unit 342 of the above-described embodiment is a computer such as a CD-ROM, a CD-R, a memory card, a DVD, a flexible disk (FD), etc. in an installable or executable file. May be stored in a readable storage medium and provided.

  The program executed by the power control unit 342 of the above embodiment has a module configuration for realizing the power control unit 342 on a computer. As actual hardware, for example, the CPU reads out a program from the ROM to the RAM and executes the program, whereby the above-described units are realized on the computer.

(Modification)
In addition, this invention is not limited to said each embodiment, A various deformation | transformation is possible.

(Modification 1)
In the embodiment described above, an example is described in which the timing for completing the accumulation of charges in the AC bypass capacitor 259 is obtained from experimental data, and switching from constant voltage control to constant current control is performed based on this timing. However, the capacitance of the electric charge accumulated in the AC bypass capacitor 259 may be detected, and switching from constant voltage control to constant current control may be performed based on the detection result.

  FIG. 11 is a circuit diagram illustrating an example of the configuration of the secondary transfer power supply 400 according to the first modification. In the example illustrated in FIG. 11, the secondary transfer power supply 400 includes a voltage detection circuit 472 that detects the voltage of the AC bypass capacitor 259.

  The voltage detection circuit 472 (an example of a detection unit) detects the voltage of the AC bypass capacitor 259 to detect the capacity of the electric charge accumulated in the AC bypass capacitor 259. The voltage detection circuit 472 outputs an FB_C signal (feedback signal) to the power supply control unit 342 when detecting that the electric charge of a predetermined capacity or more is accumulated in the AC bypass capacitor 259.

  When the power supply control unit 342 receives the FB_C signal from the voltage detection circuit 472, the power supply control unit 342 causes the I / O control unit 310 to output a switching signal instructing the DC power supply 210 to switch to constant current control (CC). When a switching signal instructing switching from the I / O control unit 310 to constant current control (CC) is input, the DC power supply 210 switches from constant voltage control to constant current control and outputs a DC bias.

  In this case, the identification information only needs to identify the constant voltage switching timing, and does not need to identify the constant current switching timing.

(Modification 2)
In the above embodiment, the power supply control unit 342 may rewrite the specific information stored in the ROM 330 based on an external input. For example, a service person may perform rewrite input of specific information from an operation unit (not shown) such as an operation panel, and the power supply control unit 342 may rewrite the specific information based on this input.

  Although the time until the charge is accumulated in the AC bypass capacitor 259 is affected by the installation environment of the printing apparatus 1 such as temperature and humidity, according to the second modification, it corresponds to the fluctuation of the charge accumulation time depending on the installation environment. be able to.

(Modification 3)
In the above embodiment, the specific information may be rewritten based on at least one of the temperature and humidity of the AC bypass capacitor 259.

  FIG. 12 is a block diagram illustrating an example of the configuration of the engine control unit 500 of the third modification. In the third modification, the printing apparatus 1 includes a detection unit 550 that detects at least one of the temperature and humidity of the AC bypass capacitor 259, and the detection result of the detection unit 550 is a power source of the CPU 540 from the I / O control unit 510. Input to the control unit 542. The power supply control unit 542 rewrites the specific information stored in the ROM 330 based on the detection result of the detection unit 550 (at least one of the temperature and humidity of the AC bypass capacitor 259).

  The time until the charge is accumulated in the AC bypass capacitor 259 is affected by the installation environment of the printing apparatus 1 such as temperature and humidity, but according to the third modification, the charge accumulation time varies automatically depending on the installation environment. Can respond.

(Modification 4)
In the above-described embodiment, an example in which the transfer bias is applied by connecting the transfer bias secondary transfer power supply 200 to the secondary transfer unit facing roller 63 has been described. However, the transfer bias secondary transfer power supply 200 is used as the secondary transfer power supply. Even if the transfer bias is applied by connecting to the roller 64, the toner image can be transferred onto the recording paper without any problem. Further, for example, even when one of the secondary transfer power supply 200 for transfer bias is connected to the secondary transfer portion facing roller 63 and the other is connected to the secondary transfer roller 64, the toner image can be transferred onto the recording paper without any problem. Can do.

(Modification 5)
In the above embodiment, the output timing of the high-voltage output is specified by software, but may be specified by hardware.

(Modification 6)
In the above embodiment, the secondary transfer power source 200 may include a cleaning DC power source.

(Modification 7)
The above-described embodiments and modifications are examples, and it has been confirmed in other image forming apparatuses and various image forming environments that the present invention can be realized even if the configuration and process conditions are changed. .

1 Printing device 10Y, 10M, 10C, 10K Image forming unit 11Y, 11M, 11C, 11K Photosensitive drum 20Y, 20M, 20C, 20K Charging device 30Y, 30M, 30C, 30K Developing device 31Y Housing container 32Y Developing sleeve 33Y Screw member 40Y, 40M, 40C, 40K Primary transfer roller 50Y, 50M, 50C, 50K Cleaning device 51Y Cleaning blade 52Y Cleaning brush 60 Intermediate transfer belt 61, 62 Support roller 63 Secondary transfer unit facing roller 64 Secondary transfer roller 70 Paper cassette 71 Feed roller 72 Transport roller pair 90 Fixing device 200, 400 Secondary transfer power supply 210 DC power supply 211 DC output control unit 212 DC drive unit 213 DC voltage transformer 214 DC output detection unit 221 Voltage control Circuit 222 a current control circuit 223 dc driving circuit 224 primary winding N1_DC (-)
225 Secondary winding N2_DC (-)
226 DC voltage detection circuit 227 DC voltage detection circuit 228 DC current detection circuit 229 switching circuit 240 AC power supply 241 AC output control unit 242 AC drive unit 243 AC voltage transformer 244 AC output detection unit 251 Voltage control circuit 252 Current control circuit 253 AC Drive circuit 254 Primary winding N1_AC
255 Primary winding N3_AC
256 Secondary winding N2_AC
257 AC power supply input unit 258 High voltage output unit 259 AC bypass capacitor 260 AC current detection circuit 261 AC current detection circuit 262 AC voltage detection circuit 270 Output abnormality detection unit 271 Output abnormality detection circuit 300, 500 Engine control unit 310, 510 I / O control unit 320 RAM
330 ROM
340, 540 CPU
342, 542 Power control unit 472 Voltage detection circuit 550 detection unit

JP 2012-42835 A

Claims (13)

A DC power source that switches between constant current control and constant voltage control to output a DC voltage;
A superimposed voltage obtained by superimposing an AC voltage on the DC voltage, and an AC power supply that outputs any one of the DC voltages;
A bypass capacitor that removes a voltage that is not applied to an application target from among the voltages output from the AC power supply;
When a predetermined condition is satisfied, a power supply control unit that switches the DC power supply from the constant voltage control to the constant current control,
A current detector that detects a direct current based on the direct current voltage and outputs the detected direct current to the power supply controller;
With
When the DC power supply is switched to the constant current control, the power supply control unit, based on the output value of the current detection unit, a predetermined target value of the DC current, and a predetermined target time, The target signal output to the DC power source is changed so as to gradually approach the target value, and the target time is longer than the convergence time until the overshooting current converges to the target value when the change is not made. Short thing
A power supply control device. The current detection unit periodically detects a direct current and outputs it to the power supply control unit,
The power supply control device according to claim 1, wherein the power supply control unit causes the DC power supply to output the DC voltage so that an output value of the DC current detected next becomes a value of the target signal.   The power supply control device according to claim 1, wherein the predetermined condition is a lapse of a predetermined timing after the start of the constant voltage control.   The power supply control device according to claim 3, wherein the predetermined timing is a timing specified with reference to a print start reference signal. A detector for detecting a capacity of the electric charge accumulated in the bypass capacitor;
3. The power supply control device according to claim 1, wherein the predetermined condition is that it is detected that electric charges of a predetermined capacity or more are accumulated in the bypass capacitor. A storage unit for storing specific information for specifying the predetermined timing;
The power supply control unit switches the DC power supply from the constant voltage control to the constant current control at the predetermined timing based on the specific information,
The power supply control device according to claim 3 or 4, wherein the power supply control unit rewrites the specific information stored in the storage unit based on an external input. A storage unit for storing specific information for specifying the predetermined timing;
A detection unit for detecting at least one of temperature and humidity of the bypass capacitor;
Further comprising
The power supply control unit switches the DC power supply from the constant voltage control to the constant current control at the predetermined timing based on the specific information,
The power supply control unit according to claim 3 or 4, wherein the power supply control unit rewrites the specific information stored in the storage unit based on at least one of temperature and humidity of the bypass capacitor detected by the detection unit. apparatus. A DC power source that switches between constant current control and constant voltage control to output a DC voltage;
A superimposed voltage obtained by superimposing an AC voltage on the DC voltage, and an AC power supply that outputs any one of the DC voltages;
A bypass capacitor that removes a voltage that is not applied to an application target from among the voltages output from the AC power supply;
A power supply control unit that switches the DC power supply from the constant voltage control to the constant current control when a predetermined timing after the start of the constant voltage control has elapsed;
A current detector that detects a direct current based on the direct current voltage and outputs the detected direct current to the power supply controller;
A storage unit for storing specific information for specifying the predetermined timing;
A detection unit for detecting at least one of temperature and humidity of the bypass capacitor;
With
The power supply control unit switches the DC power supply from the constant voltage control to the constant current control at the predetermined timing based on the specific information,
When the DC power supply is switched to the constant current control, the power supply control unit, based on the output value of the current detection unit, a predetermined target value of the DC current, and a predetermined target time, Change the target signal output to the DC power supply so that it gradually approaches the target value,
The power supply control unit rewrites the specific information stored in the storage unit based on at least one of temperature and humidity of the bypass capacitor detected by the detection unit.
A power supply control device. The current detection unit periodically detects a direct current and outputs it to the power supply control unit,
  The power supply control unit causes the DC power supply to output the DC voltage so that an output value of the DC current detected next becomes a value of the target signal.
  The power supply control device according to claim 8. The predetermined timing is a timing specified based on a print start reference signal.
  10. The power supply control device according to claim 8 or 9, wherein: An image forming apparatus comprising the power supply control device according to claim 1 . A switching step for switching from constant voltage control to constant current control when the predetermined condition is satisfied;
A first output step of performing the constant voltage control to start output of a DC voltage, switching to the constant current control, and then performing the constant current control to output the DC voltage;
A second output step of outputting either the superimposed voltage obtained by superimposing the alternating current voltage on the direct current voltage or the direct current voltage;
A detection step of detecting and outputting a direct current based on the direct current voltage;
When switching to the constant current control, the output value of the DC current, the predetermined target value of the DC current, and the target signal output to the DC power source that outputs the DC voltage gradually approach the target value. A target signal that is output to the DC power source that outputs the DC voltage, based on a target time that is determined to be shorter than the convergence time until the overshooting current converges to the target value when the change is not performed. Changing step to gradually approach the target value,
Including voltage output method. A DC power source that outputs a DC voltage by switching between constant current control and constant voltage control, a superimposed voltage obtained by superimposing an AC voltage on the DC voltage, an AC power source that outputs one of the DC voltages, and the AC power source A computer that controls a power supply device including a bypass capacitor that removes a voltage that is not applied to an application target from among the voltages that are output from, and a current detection unit that detects and outputs a DC current based on the DC voltage,
A switching step for switching the DC power source from the constant voltage control to the constant current control when a predetermined condition is satisfied;
When the DC power supply is switched to the constant current control, the output value of the DC current, the predetermined target value of the DC current, and the target signal output to the DC power supply that outputs the DC voltage are the target value. The target signal to be output to the DC power source is based on a target time that is set so that the overshooting current becomes shorter than the convergence time until the current converges to the target value when the change to gradually approach the target value is not performed. A change step of changing so as to gradually approach the target value;
A program for running

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