JP2021026080A - Load determination device and image forming device - Google Patents

Abstract

To determine the load at low cost.SOLUTION: Voltage generation means generates an output voltage to be supplied to a load based on the voltage output from boosting means. A power supply generates an input voltage so that the output voltage is the target voltage. Detection means detects the input voltage. Determination means is configured to monitor the increase of input voltage while increasing the output voltage, and determine the changes of the load based on the increase amount of the output voltage and the increase amount of the input voltage.SELECTED DRAWING: Figure 2

Description

The present invention relates to a load determination device and an image forming device.

According to Patent Document 1, a static elimination member that makes it easy to separate the sheet from the transfer portion has been proposed. A high voltage is applied to this static elimination member to generate an electric discharge. According to Patent Document 2, a technique for detecting a discharge or a load fluctuation generated in a member to which a high voltage is applied is described.

Japanese Unexamined Patent Publication No. 5-100593 JP-A-2009-180882

When the static eliminator member is repeatedly discharged, the shape of the static eliminator member changes from the initial shape. If the shape of the static eliminator member changes significantly, the static eliminator member cannot exhibit the static eliminator performance expected in the design. Patent Document 2 detects discharge and load fluctuation by a current detection circuit, but the current detection circuit of Patent Document 2 is expensive. Therefore, an object of the present invention is to determine the load at low cost.

The present invention is, for example,
A boosting means having a primary winding and a secondary winding, boosting the input voltage input to the primary winding and outputting it to the secondary winding.
A voltage generating means that generates an output voltage supplied to the load based on the voltage output from the boosting means, and
A power supply that generates the input voltage so that the output voltage becomes the target voltage,
A detection means for detecting the input voltage and
It has a determination means for determining the fluctuation of the load.
The determination means monitors an increase in the input voltage while increasing the output voltage, and determines the fluctuation of the load based on the increase amount of the output voltage and the increase amount of the input voltage. A determination device is provided.

According to the present invention, it is possible to determine the load at low cost.

The figure explaining the image forming apparatus The figure explaining the load determination apparatus The figure explaining the function of a CPU Flow chart showing the load determination method Diagram explaining the transition of various voltages Diagram explaining the experimental results Diagram explaining the table The figure explaining the load determination apparatus Diagram explaining the transition of various voltages Diagram explaining the experimental results The figure explaining the load determination apparatus Diagram explaining the experimental results Flow chart showing the load determination method

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

[Example 1]
<Overview of image forming device>
As shown in FIG. 1, the image forming apparatus 100 is a color laser printer that forms a multicolor image. The image forming apparatus 100 has four image forming portions because it uses a developer (toner) of yellow (Y), magenta (M), cyan (C) and black (K). The image forming apparatus 100 may be, for example, any of a printing apparatus, a printer, a copying machine, a multifunction device (MFP), and a facsimile apparatus. In the following, when it is not necessary to distinguish colors, reference codes with the trailing Y, M, C, and K omitted are used. The process cartridge 7 has a photosensitive drum 1, a charging roller 2, a developing roller 24, a developer coating roller 25, and a toner container.

The photosensitive drum 1 is an image carrier that rotates in the direction of arrow B. The power supply device 30 has a power supply circuit that generates high voltages such as a charging voltage (charging bias), a transfer voltage (transfer bias), and a developing voltage (development bias, coating bias). A negative electrode charging bias is applied to the charging roller 2 to charge the surface of the photosensitive drum 1. The exposure unit 3 forms an electrostatic latent image on the photosensitive drum 1 by irradiating the photosensitive drum 1 with a laser beam to expose the photosensitive drum 1 based on image information (image signal). A coating bias is applied to the developer coating roller 25 by the power supply device 30, and toner is applied to the developing roller 24. A development bias is applied to the developing roller 24 to attach toner to the electrostatic latent image to form a toner image. The intermediate transfer belt 12 is an image carrier that moves (rotates) in the direction of arrow F. The primary transfer roller 26 is applied with a primary transfer bias to transfer the toner image from the photosensitive drum 1 to the intermediate transfer belt 12. The intermediate transfer belt 12 transfers the toner image to the secondary transfer nip 15.

The feeding cassette 11 is a storage for storing the sheet S. The feeding roller 9 feeds the sheet S from the feeding cassette 11 to the transport path. The sheet S is transported to the secondary transfer nip 15 along the transport direction indicated by the arrow D. The secondary transfer roller 16 cooperates with the intermediate transfer belt 12 to form the secondary transfer nip 15. The power supply device 30 applies a secondary transfer bias to the roller shaft of the secondary transfer roller 16. The toner image is transferred to the sheet S by the secondary transfer roller 16 and the intermediate transfer belt 12 carrying the sheet S while sandwiching the sheet S.

A static elimination member 27 is arranged on the downstream side of the secondary transfer roller 16 in the transport direction of the sheet S. The static elimination member 27 is a metal member having a plurality of sharp shapes arranged along the longitudinal direction of the secondary transfer roller 16. The power supply device 30 applies a static elimination voltage to the static elimination member 27 that promotes separation of the sheet S from the secondary transfer nip 15. The polarity of the static elimination voltage is opposite to the polarity of the secondary transfer bias. As a result, the sheet S is prevented from being wound around the secondary transfer roller 16 and the distortion of the toner image is reduced.

The fuser 14 applies heat and pressure to the sheet S and the toner image to fix the toner image on the sheet S. The discharge roller pair 20 discharges the sheet S to the discharge tray 21.

The control unit 29 has a CPU 28 and a storage device 31. CPU is an abbreviation for central processing unit. The CPU 28 controls the image forming apparatus 100 by executing a control program stored in the ROM area of the storage apparatus 31. The CPU 28 displays a message or the like on the display device of the operation unit 32.

<Configuration and operation of load determination device>
As shown in FIG. 2, the control unit 29 and the power supply device 30 occupy the main parts of the load determination device. The power supply device 30 has power supply circuits 155a, 155b, and 155c. Alphabets such as a, b, c, and d added to the end of the reference code may be omitted when common matters are explained. The power supply circuit 155a generates a positive secondary transfer bias for transferring the toner image. The power supply circuit 155b generates a negative secondary transfer bias for cleaning the toner adhering to the secondary transfer roller 16. The output end of the power supply circuit 155b is connected to one end of a resistor R0 arranged in the power supply circuit 155a, and a high negative voltage is applied to the roller shaft 17 of the secondary transfer roller 16 via the resistor R0. The power supply circuit 155C generates a static elimination bias and applies it to the static elimination member 27.

In the power supply circuit 155a, a voltage charged in the electrolytic capacitor C1a is applied as an input voltage to the primary winding of the transformer T1a. The FET 1a switches the input voltage applied to the primary winding according to the pulse voltage applied to the gate terminal. As a result, an AC output voltage is induced in the secondary winding of the transformer T1a. The pulse voltage is output from the output port CLK1 of the control unit 29. The diode D1a and the capacitor C2a form a rectifying smoothing circuit 102a that converts alternating current into direct current. The diode D1a is a rectifying element that rectifies this output voltage. The capacitor C2a is a smoothing element that smoothes the rectified output voltage. As a result, a direct current positive bias is generated.

The voltage detection circuit 101a detects the input voltage Vin_trP generated across the electrolytic capacitor C1a and outputs the detection result (detection voltage Vin_tr) to the input port AD1 of the control unit 29. The voltage detection circuit 101a is formed by resistors R1 and R2.

The voltage generation circuit 160a is a circuit that generates an input voltage Vin_trP. The voltage generation circuit 160a charges the electrolytic capacitor C1a to set the voltage across the electrolytic capacitor C1a to the input voltage Vin_trP. The output port PWM1 of the control unit 29 outputs a pulse voltage having a duty ratio corresponding to a positive bias value. This duty ratio indicates the target voltage of the secondary transfer bias Vtr. The resistor R3 and the capacitor C3 rectify and smooth the pulse voltage to generate a DC voltage, and apply the DC voltage to the-terminal of the operational amplifier Op. The resistors R4, R5, R6 and the power supply voltage Vcc form a voltage divider circuit that divides the secondary transfer bias Vtr. A voltage proportional to the secondary transfer bias Vtr is applied to the + terminal of the operational amplifier Op. The operational amplifier Op adjusts the output voltage so that the voltage input to the + terminal satisfies the virtual ground relationship with respect to the − terminal. The transistor Tr1 is turned on by the output current from the operational amplifier Op. A voltage Vin_trP, which is a voltage Vbe between the base and emitter of the transistor Tr1 with respect to the output voltage of the operational amplifier Op, is applied to the electrolytic capacitor C1a. In this way, the feedback control is executed so that the secondary transfer bias Vtr becomes the target voltage.

In the power supply circuit 155b, the voltage across the electrolytic capacitor C1b is applied as an input voltage to the primary winding of the transformer T1b. The FET 1b switches the input voltage applied to the primary winding according to the pulse voltage applied to the gate terminal. As a result, an AC output voltage is induced in the secondary winding of the transformer T1b. The pulse voltage applied to the gate terminal is output from the output port CLK2 of the control unit 29. The diode D1b and the capacitor C2b form a rectifying smoothing circuit 102b that converts alternating current into direct current. The diode D1b is a rectifying element that rectifies this output voltage. The capacitor C2b is a smoothing element that smoothes the rectified output voltage. This creates a negative DC bias. The voltage generation circuit 160b generates an input voltage according to the pulse voltage output from the output port PWM2 and applies it to the electrolytic capacitor C1b. Since the configuration and operation of the voltage generation circuit 160b are the same as or similar to those of the voltage generation circuit 160a, the description thereof will be omitted.

In the power supply circuit 155c, the voltage across the electrolytic capacitor C1c is applied as the input voltage Vin_disP to the primary winding of the transformer T1c. The FET 1c switches the input voltage applied to the primary winding according to the pulse voltage applied to the gate terminal. As a result, an AC output voltage is induced in the secondary winding of the transformer T1c. The pulse voltage applied to the gate terminal is output from the output port CLK2 of the control unit 29. The diode D1c and the capacitor C2c form a rectifying smoothing circuit 102c that converts alternating current into direct current. The diode D1c is a rectifying element that rectifies this output voltage. The capacitor C2c is a smoothing element that smoothes the rectified output voltage. As a result, a DC static elimination bias is generated. The voltage generation circuit 160c generates an input voltage according to the pulse voltage output from the output port PWM3 and applies it to the electrolytic capacitor C1c. Since the configuration and operation of the voltage generation circuit 160c are the same as or similar to those of the voltage generation circuit 160a, the description thereof will be omitted.

<Aging of static elimination member>
When the image forming apparatus 100 forms an image for many years, the static elimination member 27 changes over time. The aging is, for example, "deformation of the tip shape" or "adhesion of paper dust". In the image forming process, an electric discharge is generated between the secondary transfer roller 16 and the static elimination member 27. This discharge causes "deformation of the tip shape". The tip shape of the static elimination member 27 is sharp in the initial state in which the image forming apparatus 100 is shipped from the factory. However, the tip shape gradually becomes rounded due to the discharge over many years. As a result, the position of the tip of the static elimination member 27 also changes. That is, the distance between the sheet S and the static elimination member 27 becomes longer than the initial distance. “Adhesion of paper dust” means that the paper dust of the sheet S adheres to the static elimination member 27 when the sheet S passes near the static elimination member 27. As a result, the resistance value of the static elimination member 27 increases.

These two secular changes depend on a plurality of conditions such as the environment in which the image forming apparatus 100 is installed, the paper type of the sheet S, and the number of printed sheets. It is difficult to predict these secular changes and accurately control the static elimination bias.

<Determination of static elimination bias>
As the static elimination member 27 changes over time, the value of the static elimination bias required to satisfy the static elimination performance and transfer performance assumed at the time of designing the static elimination member 27 changes. Therefore, the CPU 28 sets the value of the static elimination bias according to the degree of aging. The required static elimination bias correlates with the discharge start voltage. The discharge start voltage is a voltage at which discharge starts to occur between the secondary transfer roller 16 and the static elimination member 27. As the discharge start voltage increases, so does the static elimination bias.

The CPU 28 determines the discharge start voltage based on the change in the relationship between the output voltage from the power supply device 30 and the detection result of the voltage detection circuit 101a. The CPU 28 determines the static elimination bias based on the duty ratio set when the discharge start voltage is observed. As a result, the problem associated with the secular change of the static elimination member 27 is solved.

<Discharge detection method>
The CPU 28 executes discharge detection by causing the power supply circuit 155a to variably output the secondary transfer bias Vtr and measuring the input voltage Vin_trP. This corresponds to measuring the detection voltage Vin_tr by variably outputting the pulse voltage output from the output port PWM1. The relationship between the secondary transfer bias Vtr and the input voltage Vin_trP before the start of discharge is almost the first relationship. On the other hand, the relationship between the secondary transfer bias Vtr and the input voltage Vin_trP after the start of discharge is almost the second relationship. The discharge start voltage is detected by utilizing the difference between the first relationship and the second relationship.

When the CPU 28 outputs a pulse voltage having a duty ratio, the power supply circuit 155a adjusts the input voltage Vin_trP so that the secondary transfer positive bias Vtr matches the target voltage corresponding to the duty ratio. When the discharge is started, a discharge current flows along the path Pa shown in FIG. When the output current flowing along the path Pa increases, the output load of the power supply circuit 155a increases. As the output load increases, the input voltage Vin_trP increases. As the input voltage Vin_trP increases, the detection voltage Vin_tr also increases. At the boundary between the non-discharged state and the discharged state, the amount of change in the detection voltage Vin_tr with respect to the amount of change in the duty ratio becomes large. The CPU 28 monitors the amount of change in the detection voltage Vin_tr while gradually increasing the duty ratio, and detects the occurrence of discharge based on the monitoring result.

<Discharge detection sequence>
● CPU Functions FIG. 3 shows functions realized by the CPU 28 executing a control program. The function shown by the broken line will be described in the fourth embodiment. The load determination unit 301 determines the fluctuation of the load depending on the secular change of the load, such as the discharge start voltage. The setting unit 302 sets the duty ratio of the pulse voltage. When the image formation is instructed, the setting unit 302 sets the duty ratio for image formation. When the discharge detection is instructed, the setting unit 302 gradually increases the duty ratio by a predetermined amount (example: 10%) from the initial value (example: 10%) to the final value (example: 100%). The output port PWM1 generates and outputs a pulse voltage having a duty ratio set by the setting unit 302. The acquisition unit 303 acquires the detection voltage Vin_tr through the input port AD1 and stores it in the RAM area of the storage device 31. The difference calculation unit 304 calculates the amount of change in the detection voltage Vin_tr. The discharge detection unit 305 detects the discharge start voltage based on the amount of change in the detection voltage Vin_tr. The adjusting unit 306 adjusts the target voltage of the static elimination bias based on the discharge start voltage. As a result, the target voltage of the static elimination bias is appropriately determined according to the degree of aging of the static elimination member 27.

● Flow chart FIG. 4 is a flowchart showing a method of determining a static elimination vise (load determination method) including discharge detection. When the start condition is satisfied, the CPU 28 starts the load determination method. The start condition is, for example, that the start is instructed through the operation unit 32, or that the number of images formed reaches a predetermined number (eg, every 1000 images).

In S401, the CPU 28 (setting unit 302) sets the duty ratio of the pulse voltage output from the output port PWM1 to the initial value. In S402, the CPU 28 outputs a pulse voltage having a set duty ratio from the output port PWM1.

FIG. 5A shows the transition of the secondary transfer bias Vtr in the discharge detection sequence. The horizontal axis shows time. In this example, the output of the pulse voltage having the duty ratio of the initial value is started at time t1. The CPU 28 increases the duty ratio every time interval Δt. Therefore, the secondary transfer bias Vtr also increases every time interval Δt. The time interval Δt is set to be longer than the time required for the detection voltage Vin_tr to stabilize after the duty ratio of the pulse voltage is changed. As shown in FIG. 5A, if the duty ratio is increased by a predetermined value, the secondary transfer bias Vtr also increases by a predetermined voltage.

FIG. 5B shows the transition of the detection voltage Vin_tr in the discharge detection sequence. The horizontal axis shows time. For example, the power supply voltage Vcc is 24 [V]. The variable range of the detection voltage Vin_tr is from 0 [V] to 20 [V]. The variable range of the secondary transfer bias Vtr is from 0 [V] to 5000 [V]. The duty ratio can be set in the range of 0% to 100%. The frequency of the pulse voltage output from the output port PWM1 is 80 [kHz]. The frequency of the pulse voltage output from the output port CLK1 is 50 [kHz]. The duty ratio of the pulse voltage output from the output port CLK1 is 25% (fixed value).

In S403, the CPU 28 (acquisition unit 303) acquires the detection voltage Vin_tr through the input port AD1 and stores it in the storage device 31. In S404, the CPU 28 (difference calculation unit 304) acquires the change amount Δvin_tr with respect to the detection voltage Vin_tr acquired this time and stores it in the storage device 31. The amount of change Δvin_tr is the difference between the detection voltage Vin_tr acquired last time and the detection voltage Vin_tr acquired this time.

In S405, the CPU 28 determines whether or not the measurement for the detection voltage Vin_tr is completed. For example, if the duty ratio of the pulse voltage output from the output port PWM1 reaches 100%, the CPU 28 determines that the measurement is completed. If the measurement is completed, the CPU 28 proceeds to S406. If the measurement is not completed, the CPU 28 proceeds to S410. In S410, the CPU 28 (setting unit 302) increases the duty ratio by a predetermined value (example: 10%) and proceeds to S403. In this way, S403, S404, S405 and S410 are repeatedly executed until the measurement is completed. According to FIG. 5B, the measurement is completed at time t3.

In S406, the CPU 28 (discharge detection unit 305) acquires the maximum change amount (maximum value) among the acquired plurality of change amounts Δvin_tr. In S407, the CPU 28 (discharge detection unit 305) specifies the duty ratio corresponding to the maximum value.

FIG. 6A shows the detection voltage Vin_tr, the amount of change Δvin_tr, and the secondary transfer bias Vtr stored in the storage device 31. In this example, the maximum value of the amount of change Δvin_tr is 3.0. The duty ratio corresponding to the maximum value is 60%. According to FIG. 5B, the maximum value is observed at time t2. The discharge start voltage is 3000 [V].

In S408, the CPU 28 (adjusting unit 306) determines the target value of the static elimination bias based on the maximum value. FIG. 7A shows a table 700a that stores the relationship between the duty ratio at the start of discharge and the target value of the static elimination bias. The table 700a is stored in the ROM area of the storage device 31. The adjusting unit 306 acquires a target value corresponding to the duty ratio at the start of discharge from the table 700a. A mathematical formula having the same function as that of the table 700a may be used. The adjusting unit 306 stores the acquired target value in the storage device 31 as a target value of the static elimination bias used in the image forming process. According to FIG. 7A, the target value is set to −2000 [V]. The CPU 28 outputs a pulse voltage having a predetermined duty ratio from the output port PWM3. The predetermined duty ratio is a duty ratio corresponding to the target value of −2000 [V].

<Determination of static elimination bias for image formation>
There is a correlation between the target value of the static elimination bias and the duty ratio at the start of discharge. When the duty ratio at the start of discharge is 60%, the secondary transfer bias Vtr corresponding to 60% is 3000 [V]. The secondary transfer bias Vtr is a potential difference generated between the roller shaft 17 of the secondary transfer roller 16 and the static elimination member 27.

If the secondary transfer bias Vtr at the start of discharge is 4000 [V], it means that the secular change of the static elimination member 27 is further advanced. That is, the resistance value between the secondary transfer roller 16 and the static elimination member 27 is high by 1000 [V] (the space distance is wide or the amount of paper dust adhered is large). Similarly, the relationship between the static elimination member 27 and the sheet S is also affected by the secular change of the static elimination member 27. Therefore, the resistance value between the static elimination member 27 and the sheet S is also higher. According to FIGS. 6 (A) and 7 (A), if the discharge start voltage is 4000 [V], the duty ratio is 80%. The target value of the static elimination bias corresponding to this duty ratio is -2400 [V]. In this way, the static elimination bias is increased as the static elimination member 27 changes over time. The table 700a may be created by performing an experiment or a simulation in advance.

[Example 2]
In the first embodiment, the discharge start voltage is searched for by variably outputting the secondary transfer bias Vtr. In the second embodiment, the discharge start voltage is searched for by variably outputting the static elimination bias Vdis. In the second embodiment, the description of the same or similar matters as the first embodiment is omitted.

<Voltage detection circuit>
FIG. 8 shows the power supply device 30 of the second embodiment. As compared with the first embodiment, the voltage detection circuit 101a is deleted from the power supply circuit 155a, and the voltage detection circuit 101c is added to the power supply circuit 155c. The circuit configuration of the voltage detection circuit 101c and the circuit configuration of the voltage detection circuit 101a are common. The voltage detection circuit 101c detects the input voltage Vin_disP of the transformer T1c and outputs the detection voltage Vin_dis proportional to the input voltage Vin_disP to the input port AD3 of the CPU 28.

<Discharge detection sequence>
FIG. 5C shows the transition of the static elimination bias Vdis in the discharge detection sequence of Example 2. FIG. 5D shows the transition of the detection voltage Vin_dis in the discharge detection sequence of the second embodiment. Also in the second embodiment, the duty ratio of the pulse voltage output from the output port PWM3 is increased every time interval Δt. The power supply voltage Vcc is 24 [V]. The variable range of the detection voltage Vin_dis is from 0 [V] to 20 [V]. The variable range of the static elimination bias Vdis is from -4000 [V] to 0 [V]. The duty ratio can be set in the range of 0% to 100%. The initial value is 10%. The amount of increase is 10%. The frequency of the pulse voltage output from the output port PWM3 is 80 [kHz]. The frequency of the pulse voltage output from the output port CLK3 is 50 [kHz]. The duty ratio of the pulse voltage output from the output port CLK3 is 25% (fixed value).

The CPU 28 starts the discharge detection sequence at time t11. In S401 to S405 and S410, the CPU 28 (setting unit 302, acquisition unit 303) measures the detection voltage Vin_dis while gradually increasing the duty ratio of the pulse voltage output from the output port PWM3. In S404, the CPU 28 (difference calculation unit 304) acquires the change amount Δvin_dis of the detection voltage Vin_dis. The measurement is completed at time t13. In S406, the CPU 28 (discharge detection unit 305) determines the maximum value among the plurality of change amounts Δvin_dis.

FIG. 6B shows the relationship between the detection voltage Vin_dis, the amount of change Δvin_dis, and the static elimination bias Vdis stored in the storage device 31. In S407, the CPU 28 (discharge detection unit 305) specifies the duty ratio corresponding to the maximum value. In FIG. 5B, the maximum value of Δvin_dis is 2.0 [V]. The static elimination bias Vdis corresponding to the maximum value is -3200 [V], which is the discharge start voltage. The duty ratio corresponding to the maximum value is 80%. In FIGS. 5C and 5D, the amount of change Δvin_dis reaches the maximum value at time t12.

FIG. 8B shows a table 700b that holds the duty ratio corresponding to the discharge start voltage and the target value of the static elimination bias. In S408, the CPU 28 (adjusting unit 306) determines the static elimination bias Vdis based on the specified duty ratio. For example, the adjusting unit 306 acquires the target value corresponding to the duty ratio (example: 80%) from the table 700b. In this example, the target value of the static elimination bias Vdis is -2000 [V]. This target value is held in the storage device 31 and used in the image forming process.

In this way, the discharge start voltage is determined by variably outputting only the static elimination bias. Further, an appropriate target value of the static elimination bias Vdis corresponding to the discharge start voltage is determined.

[Example 3]
In the third embodiment, the CPU 28 outputs both the secondary transfer bias Vtr and the static elimination bias Vdis to determine the discharge start voltage. However, the CPU 28 maintains the secondary transfer bias Vtr constant, but variably controls the static elimination bias Vdis. The CPU 28 detects the discharge start voltage or the discharge start duty ratio based on the detection voltage Vin_tr. In the third embodiment, the power supply device 30 shown in FIG. 2 is used. In the third embodiment, the description of the same or similar matters as those in the first and second embodiments is omitted.

<Discharge detection method>
Discharge occurs when only the static elimination bias Vdis is increased while maintaining the secondary transfer bias Vtr constant. Since the output current flowing in the path Pa increases, the output load of the power supply circuit 155a increases. As the output load increases, the secondary transfer bias Vin_tr increases. At the boundary between the non-discharged state and the discharged state, the change amount of the detection voltage Vin_tr becomes large as the change amount of the duty ratio of the pulse voltage output from the output port PWM3. That is, the amount of change in the output of the power supply circuit 155a is larger than the amount of change in the input of the power supply circuit 155c. Therefore, the CPU 28 can detect the discharge based on the change in the slope of the detection voltage Vin_tr.

<Discharge detection sequence>
In S401, the CPU 28 sets the duty ratio of the pulse voltage output from the output port PWM1 to the initial value, and sets the duty ratio of the pulse voltage output from the output port PWM3 to the initial value. In S402, the CPU 28 starts generating the secondary transfer bias Vtr and the static elimination bias Vdis, which are the output voltages.

FIG. 9A shows the transition of the secondary transfer bias Vtr in Example 3. FIG. 9B shows the transition of the detection voltage Vin_tr in the third embodiment. FIG. 9C shows the transition of the static elimination bias Vdis in Example 3. FIG. 9D shows the transition of the detection voltage Vin_dis in the third embodiment. Here, the discharge detection sequence is started at time t21. At time t21, the static elimination bias Vdis is −400 [V]. The secondary transfer bias Vtr is 1500 [V]. As shown in FIG. 9A, the secondary transfer bias Vtr is kept constant. This is because the duty ratio of the pulse voltage output from the output port PWM1 is fixed to the initial value. In this example, the discharge is started at time t22. As shown in FIG. 9D, the amount of change Δvin_dis increases at time t22. As shown in FIG. 9B, the input voltage Vin_tr changes at time t22. That is, the amount of change Δvin_tr increases.

In S403, the CPU 28 acquires the detection voltage Vin_tr. In S404, the CPU 28 acquires the amount of change Δvin_tr and stores it in the RAM area. In S405, the CPU 28 determines whether the measurement is completed. If the measurement is not completed, the CPU 28 proceeds to S410 and increases the duty ratio of the pulse voltage output from the output port PWM3 by a predetermined amount (example: 10%). After that, the CPU 28 proceeds to S403. When the duty ratio reaches 100%, the CPU 28 proceeds to S406.

In S406, the CPU 28 specifies the maximum value among the plurality of change amounts Δvin_tr. FIG. 10 shows the relationship between the duty ratio stored in the RAM area and Δvin_tr. Here, as a supplement, Vin_tr, Vdis, Vin_dis and Δvin_dis are also shown. According to FIG. 10, the maximum value is 2.2 [V]. -1600 [V], which is the static elimination bias when Δvin_tr becomes 2.2 [V], is the discharge start voltage.

In S407, the CPU 28 specifies a duty ratio corresponding to the maximum value. According to FIG. 10, the duty ratio that brought about the maximum value is 40%. This may be referred to as the discharge start duty ratio. In FIG. 9B, the duty ratio is set to 40% at time t22, and the discharge is started.

In S408, the CPU 28 determines the static elimination bias based on the specified duty ratio. FIG. 7C shows a table 700c that holds the relationship between the duty ratio and the target value of the static elimination bias. The table 700c is stored in the storage device 31 in advance. The CPU 28 refers to the table 700c based on the specified duty ratio and acquires the target value corresponding to the specified duty ratio. In this example, since the duty ratio is 40%, the target value of the static elimination bias used in the image forming process is determined to be −2000 [V].

In Example 3, the detection accuracy of the discharge start voltage can be improved as compared with Examples 1 and 2. The input / output voltage characteristics of the transformer T1a and the input / output voltage characteristics of the transformer T1c may be different. For example, for the transformer T1a, the change in the input voltage is large with respect to the change in the output voltage. For the transformer T1c, the change in the input voltage with respect to the change in the output voltage is small. In this case, the amount of change Δvin_tr at the start of discharge is large, but the amount of change Δvin_dis is small. That is, the method of determining the discharge start voltage by paying attention to the amount of change Δvin_dis as in the second embodiment would be disadvantageous. On the other hand, when a plurality of high voltages are output as in the third embodiment, the load seen from the power supply circuit 155a increases. That is, not only the detection voltage Vin_dis but also the detection voltage Vin_tr changes. In the transformer T1a, the change in the input voltage with respect to the change in the output voltage is larger than that in the transformer T1c. The amount of change in Vin_tr is larger than the amount of change in Vin_dis. Therefore, Example 3 in which the discharge start voltage is determined based on the amount of change Δvin_tr is advantageous.

Whether the power supply circuit 155a or the power supply circuit 155c should be provided with the voltage detection circuit 101 depends on the input / output voltage characteristics of the transformer T1a and the transformer T1c. Therefore, when designing the image forming apparatus 100, the power supply circuit on which the voltage detection circuit 101 should be mounted may be determined by comparing the input / output voltage characteristics of the transformer T1a with the input / output voltage characteristics of the transformer T1c.

In the third embodiment, the discharge start voltage is determined based on the amount of change Δvin_tr when the static elimination bias is changed stepwise. On the contrary, the secondary transfer positive bias may be changed stepwise while keeping the static elimination bias constant, and the discharge start voltage may be determined based on the change amount Δvin_tr or the change amount Δvin_dis.

[Example 4]
The fourth embodiment relates to a method of detecting an abnormal load fluctuation occurring at an output end by using a power supply circuit including a voltage detection circuit. In the fourth embodiment, the load fluctuation is a load fluctuation that can be observed through the output voltage of the power supply circuit. For example, if a scratch is formed on the surface of the photosensitive drum 1, the output voltage of the power supply circuit that supplies the charging bias to the charging roller 2 is affected by the load fluctuation. This is because the resistance value of the portion of the surface of the photosensitive drum 1 where the scratches are present and the resistance value of the portion where the scratches are not present are different. That is, the CPU 28 detects an abnormality in the load (eg, a scratch is generated on the surface of the photosensitive drum 1) by monitoring the output voltage of the power supply circuit.

Here, it is assumed that the central axis of the photosensitive drum 1 is connected to the frame ground of the image forming apparatus 100. The normal photosensitive drum 1 functions as a capacitor. This is because when the normal photosensitive drum 1 is charged, the surface potential becomes a predetermined potential according to the charging bias. On the other hand, the potential of the surface on which the scratch is formed is maintained at the same potential as the central axis of the photosensitive drum 1. In the image formed by the photosensitive drum 1 having scratches, a strip-shaped defective image parallel to the longitudinal direction of the photosensitive drum 1 occurs. Therefore, the CPU 28 detects the failure of the photosensitive drum 1 by monitoring the input voltage in the power supply circuit that generates the charging bias, as in the first to third embodiments. The CPU 28 notifies the display device of the operation unit 32 of the failure of the photosensitive drum 1 (process cartridge 7). In Example 4, the description of the same or similar matters as in Examples 1 to 3 is omitted.

FIG. 11 is a diagram illustrating a power supply circuit 155d. In the power supply circuit 155d, the voltage charged in the electrolytic capacitor C1d is applied as an input voltage to the primary winding of the transformer T1d. The FET 1d switches the input voltage applied to the primary winding according to the pulse voltage applied to the gate terminal. As a result, an AC output voltage is induced in the secondary winding of the transformer T1d. The pulse voltage input to the FET 1d is output from the output port CLK4 of the control unit 29. The diode D1d and the capacitor C2d form a circuit that converts alternating current into direct current. The diode D1d is a rectifying element that rectifies this output voltage. The capacitor C2d is a smoothing element that smoothes the rectified output voltage. This creates a negative DC bias. The diode D1d and the capacitor C2d form a rectifying smoothing circuit 102d. The voltage generation circuit 160d generates an input voltage according to the pulse voltage output from the output port PWM4 and applies it to the electrolytic capacitor C1d. Since the configuration and operation of the voltage generation circuit 160d are the same as or similar to those of the voltage generation circuit 160a, the description thereof will be omitted.

The circuit configuration of the voltage detection circuit 101d and the circuit configuration of the voltage detection circuit 101a are common. The voltage detection circuit 101d detects the input voltage Vin_priP of the transformer T1d and outputs the detection voltage Vin_pri proportional to the input voltage Vin_priP to the input port AD4 of the CPU 28.

<Load fluctuation detection method>
As shown in FIG. 11, the photosensitive drum 1 has a scratch hole 1100. The CPU 28 applies a predetermined charging bias Vpri to the charging roller 2. On the other hand, when the CPU 28 (rotation control unit 307) drives the motor 33, the photosensitive drum 1 rotates in the direction of the arrow B. The detection voltage Vin_pri measured when the scratch is in contact with the charging roller 2 is different from the detection voltage Vin_pri measured when the portion where the scratch does not exist is in contact with the charging roller 2. The CPU 28 detects load fluctuations (occurrence of scratches 1100) by monitoring the detection voltage Vin_pri output by the voltage detection circuit 101d.

When a predetermined charging bias Vpri is applied to the charging roller 2, an output current (load current) flows along the path Pc. Since the load current increases at the timing when the scratched hole 1100 comes into contact with the charging roller 2, the output load seen from the output end of the charging bias Vpri increases. The CPU 28 determines the duty ratio of the pulse voltage output from the output port PWM4 in order to set the target voltage of the charging bias Vpri.

The power supply circuit 155d adjusts the input voltage Vin_priP so that the charging bias Vpri matches the target value corresponding to the duty ratio (feedback control). Even if the output load increases, the input voltage Vin_priP needs to be increased in order to maintain the charge bias Vpri at the target value. Therefore, the CPU 28 can recognize the load fluctuation by observing the change of the detection voltage Vin_pri correlated with the input voltage Vin_priP.

<Load abnormality discrimination sequence>
FIG. 12 shows the transition of the charge bias Vpri and the transition of the detection voltage Vin_pri in the discrimination sequence. In this example, the photosensitive drum 1 rotates twice in the discrimination sequence. The power supply voltage Vcc of the power supply circuit 155d is 24 [V]. The variable range of the detection voltage Vin_pri is from 0 [V] to 20 [V]. The variable range of the charge bias Vpri is from -1500 [V] to 0 [V]. The duty ratio can be set from 0% to 100%. The frequency of the pulse voltage output from the output port PWM4 is 80 [kHz]. The frequency of the pulse voltage output from the output port CLK4 is 50 [kHz].

In this example, the output of the charging bias Vpri is started at time t31. Normally, the detection voltage Vin_pri is maintained at a predetermined value (eg 14V), but the detection voltage Vin_pri increases due to scratches. In particular, fluctuations in the detection voltage Vin_pri are detected at times t33 and t34. The discrimination sequence is completed at time t35. As will be described in detail below, the threshold value determination unit 311 determines the discrimination threshold value (example: 14V) based on the detection voltage Vin_pri in the period from the time t31 to the time t32. The threshold value comparison unit 312 determines the abnormality of the load by comparing the discrimination threshold value with each sampling value of the detection voltage Vin_pri.

FIG. 13 is a flowchart showing a discrimination sequence (load determination method) executed by the CPU 28. When the determination sequence start condition is satisfied, the CPU 28 starts the determination sequence. The start condition is, for example, that a start instruction has been input from the operation unit 32. The discrimination sequence may be included in the cleaning sequence of the image forming apparatus 100. The discrimination sequence may be performed during image formation.

In S1301, the CPU 28 (rotation control unit 307) starts the rotation of the photosensitive drum 1 by activating the motor 33. In S1302, the CPU 28 (setting unit 302) sets the duty ratios of the two types of pulse voltages to the initial values. The initial value of the pulse voltage output from the output port PWM4 is, for example, 70%. The duty ratio of the pulse voltage output from the output port CLK4 is, for example, 25%. In S1303, the CPU 28 outputs a pulse voltage having a set duty ratio from the output port PWM4 and the output port CLK4 to start the generation of the charge bias Vpri which is the output voltage.

In S1304, the CPU 28 (acquisition unit 303) acquires the detection voltage Vin_pri through the input port AD4 and stores it in the storage device 31. In S1305, the CPU 28 determines whether or not the measurement for the detection voltage Vin_pri is completed. For example, when the photosensitive drum 1 rotates twice with reference to the time when the measurement of the detection voltage Vin_pri is started, the CPU 28 determines that the measurement is completed. Whether or not the two rotations are completed may be determined based on whether or not the elapsed time from the start of the measurement of the detection voltage Vin_pri has reached a predetermined time. The predetermined time may be longer than or equal to the time required for the photosensitive drum 1 to rotate twice (twice the rotation cycle). For example, when the peripheral length of the photosensitive drum 1 is 90 [mm] and the rotation speed is 150 rpm], the rotation cycle of the photosensitive drum 1 is 400 [msec]. When the diameter of the scratch 1100 is 0.5 [mm], the period Δt3 in which the detection voltage Vin_pri fluctuates depending on the scratch 1100 is 2.22 [msec]. The acquisition cycle of the detection voltage Vin_pri may be 1 [msec] or less. If the measurement is not completed, the CPU 28 proceeds to S1304. If the measurement is completed, the CPU 28 proceeds to S1306.

At S1306, the CPU 28 ends the generation of the charge bias Vpri, which is the output voltage. In S1307, the CPU 28 stops the motor 33. As a result, the photosensitive drum 1 also stops.

In S1308, the CPU 28 (threshold value determination unit 311) determines the threshold value Vth. For example, the threshold determination unit 311 adds a margin value (example: 3 [V]) to the average value (example: 14 [V]) of the detection voltage Vin_pri acquired in the period from time t31 to time t32. , The threshold Vth (eg 17 [V]) is determined. It will be sufficient if the threshold value Vth is determined depending on the magnitude of the load fluctuation to be determined as abnormal.

In S1309, the CPU 28 (threshold comparison unit 312) determines whether or not the abnormal condition is satisfied. The abnormality condition is, for example, that an abnormality has occurred n times while the photosensitive drum 1 has rotated n times. In FIG. 12, n is set to 2. That is, when the two detection voltages Vin_pri exceed the threshold value Vth, the threshold value comparison unit 312 determines that the abnormal condition is satisfied. According to FIG. 12, the detection voltage Vin_pri measured at time t33 and the detection voltage Vin_pri measured at time t34 each exceed the threshold value Vth. The threshold value comparison unit 312 may have a counter that counts the number of times that the detection voltage Vin_pri exceeds the threshold value Vth. In this case, the threshold value comparison unit 312 may determine whether or not the count value exceeds the count threshold value (eg, twice). Since the count threshold value is determined according to the sampling cycle of the detection voltage Vin_pri and the diameter of the hole to be detected, it may be two or more times. If the abnormal condition is not satisfied, the CPU 28 skips S1310. If the abnormal condition is satisfied, the CPU 28 proceeds to S1310.

In S1310, the CPU 28 (notification unit 313) notifies the abnormality. For example, the notification unit 313 outputs a code or a message indicating that an abnormality has occurred in the process cartridge 7 to the display device of the operation unit 32. The notification unit 313 may output a code or a message indicating that the process cartridge 7 needs to be inspected, cleaned, or replaced on the display device of the operation unit 32.

<Summary>
[Viewpoint 1]
The transformer T1 has a primary winding and a secondary winding, and functions as a boosting means for boosting the input voltage input to the primary winding and outputting it to the secondary winding. The rectifying and smoothing circuit 102 functions as a voltage generating means for generating an output voltage supplied to the load based on the voltage output from the boosting means. The voltage generation circuit 160 functions as a power source that generates an input voltage so that the output voltage becomes a target voltage. The voltage detection circuit 101 functions as a detection means for detecting the input voltage. The CPU 28 and the load determination unit 301 function as determination means for determining load fluctuations. The CPU 28 and the load determination unit 301 monitor the increase in the input voltage while increasing the output voltage. The CPU 28 and the load determination unit 301 determine the fluctuation of the load based on the increase amount of the output voltage and the increase amount of the input voltage. For example, the CPU 28 and the load determination unit 301 determine the load fluctuation based on whether the relationship between the increase amount of the output voltage and the increase amount of the input voltage satisfies a predetermined relationship. As described above, since the current detection circuit is not used in the present invention, it is possible to determine the load at low cost.

[Viewpoint 2]
The CPU 28 may repeatedly obtain the amount of change in the input voltage while repeatedly increasing the output voltage by a constant amount of increase, and determine the fluctuation of the load based on the plurality of amounts of change. The relationship between the amount of increase in output voltage and the amount of change in input voltage can change at the boundary between the non-discharged state and the discharged state. Therefore, by using this relationship, the CPU 28 may determine the fluctuation of the load.

[Viewpoint 3]
The CPU 28 and the adjusting unit 306 may function as adjusting means for adjusting the target voltage according to the fluctuation of the load. When the load resistance of the static elimination member 27 changes, the target voltage of the static elimination bias also changes. Therefore, by adjusting the target voltage according to the fluctuation of the load, the performance required for the load (eg, static elimination performance) will be maintained.

[Viewpoint 4]
The fluctuation of the load may be a change in the load resistance with the aging of the load. The load resistance of the static eliminator member 27 changes with aging. This is because the shape of the tip of the static elimination member 27 changes and paper dust adheres to the tip.

[Viewpoint 5]
As described in Examples 1 to 3, the discharge start voltage with respect to the load changes due to the change in the load resistance. The CPU 28 may detect the discharge start voltage based on this characteristic.

[Viewpoint 6]
The voltage generation circuit 160 is configured to generate an input voltage according to a control parameter (eg, duty ratio) for setting a target voltage. The CPU 28 may specify the control parameter corresponding to the discharge start voltage and reset the target voltage according to the specified control parameter.

[Viewpoint 7]
Table 700 is an example of a table that holds the relationship between a plurality of control parameters and a plurality of target voltages. The CPU 28 may determine the target voltage corresponding to the specified control parameter by referring to the table 700. This will allow the target voltage to be determined easily and accurately.

[Viewpoint 8]
The static elimination member 27 is an example of an application member in which a load is applied to the sheet in order to separate the sheet from the transfer body of the image forming apparatus. The present invention is similarly applicable as long as it is a member to which a high voltage is applied.

[Viewpoint 9]
As described in the fourth embodiment, the CPU 28 determines the load abnormality based on the number of occurrences of the load fluctuation detected while the rotating body as the load is rotating for a predetermined number of laps and the number of laps. It functions as a discriminating means. As a result, load abnormalities will be detected accurately.

[Viewpoint 10]
The load may have a photosensitive drum that is a rotating body and a charger (eg, charging roller 2) that charges the surface of the photosensitive drum. The abnormality of the load may be that a scratch 1100 is generated on the surface of the photosensitive drum.

[Viewpoint 11]
The secondary transfer roller 16 functions as a transfer means for transferring an image to a sheet by applying a transfer voltage. The static elimination member 27 is provided on the downstream side of the transfer means in the sheet transport direction, and functions as an application member that applies a separation promoting voltage to the sheet to promote the separation of the sheets in the transfer means. The static elimination bias is an example of the separation promoting voltage. The power supply circuit 155a functions as a first generation unit that generates a transfer voltage. The power supply circuit 155c functions as a second generation unit that generates a separation promoting voltage. The CPU 28 functions as a control means for controlling the power supply device 30. The CPU 28 and the load determination unit 301 function as determination means for determining the degree of aging of the applied member. The CPU 28 and the load determination unit 301 monitor the increase in the input voltage while increasing the output voltage, and the aging of the application member is based on whether the relationship between the increase in the output voltage and the increase in the input voltage satisfies a predetermined relationship. The degree of may be determined. For example, the CPU 28 monitors an increase in the input voltage in one of the first generation unit and the second generation unit while increasing the output voltage in one of the first generation unit and the second generation unit. The CPU 28 may determine the degree of secular change of the applied member based on whether or not the relationship between the increase amount of the output voltage on one side and the increase amount of the input voltage on the other side satisfies a predetermined relationship. This makes it possible to inexpensively determine the degree of aging of the applied member.

[Viewpoints 12 and 13]
As described in Examples 1 and 3, the output voltage may be a transfer voltage. As described in Examples 2 and 3, the output voltage may be a separation promoting voltage. The CPU 28 may monitor an increase in the input voltage in the second generation unit while increasing the output voltage in the first generation unit. The CPU 28 may determine the degree of aging of the applied member based on whether or not the relationship between the amount of increase in the output voltage in the first generation unit and the amount of increase in the input voltage in the second generation unit satisfies a predetermined relationship. The CPU 28 may monitor an increase in the input voltage in the first generation unit while increasing the output voltage in the second generation unit. The CPU 28 may determine the degree of aging of the applied member based on whether or not the relationship between the amount of increase in the output voltage in the second generation unit and the amount of increase in the input voltage in the first generation unit satisfies a predetermined relationship.

[Viewpoint 14]
As described in the first embodiment, the CPU 28 may adjust the separation promoting voltage according to the degree of aging of the applied member. This will allow the sheet S to be properly separated from the transfer means.

[Viewpoint 15]
The motor 33 is an example of a motor that rotates the photosensitive drum 1. The charging roller 2 functions as a charging means for charging the surface of the photosensitive drum 1 using a charging voltage. The CPU 28 and the rotation control unit 307 control the motor 33 to rotate the photosensitive drum 1. The CPU 28 samples the input voltage. The CPU 28 may determine the abnormality of the photosensitive drum 1 based on the number of sampling values exceeding the threshold value among the plurality of sampling values acquired for the input voltage while the photosensitive drum 1 rotates for a predetermined number of laps. As a result, it will be possible to appropriately detect the abnormality of the photosensitive drum 1.

[Viewpoint 16]
The CPU 28 functions as a threshold value determining means for determining the threshold value Vth based on the statistical values of a plurality of sampling values acquired for the input voltage while the photosensitive drum 1 rotates for a predetermined number of laps. The statistical value may be, for example, the average value of a plurality of sampling values acquired during one rotation or n rotations of the photosensitive drum 1. As shown in FIG. 12, an abnormality of the detection voltage Vin_pri occurs once while the photosensitive drum 1 rotates once. By averaging a plurality of sampling values acquired during one rotation or n rotations of the photosensitive drum 1, the abnormality of the detection voltage Vin_pri is less likely to affect the threshold value Vth. Therefore, it will be easy to obtain an appropriate threshold value Vth.

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

100: Image forming apparatus, T1: Transformer, 102: Rectifying and smoothing circuit, 160: Voltage generation circuit, 101: Voltage detection circuit, 28: CPU

Claims (16)

A boosting means having a primary winding and a secondary winding, boosting the input voltage input to the primary winding and outputting it to the secondary winding.
A voltage generating means that generates an output voltage supplied to the load based on the voltage output from the boosting means, and
A power supply that generates the input voltage so that the output voltage becomes the target voltage,
A detection means for detecting the input voltage and
It has a determination means for determining the fluctuation of the load.
The determination means monitors an increase in the input voltage while increasing the output voltage, and determines the fluctuation of the load based on the increase amount of the output voltage and the increase amount of the input voltage. Judgment device. The determination means is characterized in that the change amount of the input voltage is repeatedly obtained while repeatedly increasing the output voltage by a constant increase amount, and the change of the load is determined based on the plurality of change amounts. The load determination device according to 1. The load determination device according to claim 1 or 2, further comprising an adjusting means for adjusting the target voltage according to the fluctuation of the load. The load determination device according to claim 3, wherein the fluctuation of the load is a change in the load resistance with the aging of the load. The load determination device according to claim 4, wherein the discharge start voltage related to the load changes according to the change in the load resistance. The power supply is configured to generate the input voltage according to control parameters for setting the target voltage.
The fifth aspect of the present invention is characterized in that the adjusting means is configured to specify the control parameter corresponding to the discharge start voltage and reset the target voltage according to the specified control parameter. The load determination device described. It also has a table that holds the relationship between multiple control parameters and multiple target voltages.
The load determination device according to claim 6, wherein the adjusting means determines a target voltage corresponding to the specified control parameter by referring to the table. The load determination device according to any one of claims 1 to 7, wherein the load is an application member that applies a voltage to the sheet in order to separate the sheet from the transfer body of the image forming apparatus. It is characterized by further having a discriminating means for discriminating an abnormality of the load based on the number of occurrences of load fluctuation detected while the rotating body as the load is rotating for a predetermined number of laps and the number of laps. The load determination device according to any one of claims 1 to 7. The load has a photosensitive drum that is a rotating body and a charger that charges the surface of the photosensitive drum.
The load determination device according to claim 9, wherein the load abnormality is that a scratch is generated on the surface of the photosensitive drum. A transfer means that transfers an image to a sheet by applying a transfer voltage,
An application member provided on the downstream side of the transfer means in the transport direction of the sheet and applying a separation promoting voltage to the sheet to promote separation of the sheet in the transfer means.
The first generation unit that generates the transfer voltage and
The second generation unit that generates the separation promotion voltage and
It has a first generation unit and a control means for controlling the second generation unit.
The first generation unit and the second generation unit are each
A boosting means having a primary winding and a secondary winding, boosting the input voltage input to the primary winding and outputting it to the secondary winding.
A voltage generating means that generates an output voltage based on the voltage output from the boosting means, and
A power supply that generates the input voltage so that the output voltage becomes the target voltage,
It has a detection means for detecting the input voltage and
The control means
It has a determination means for determining the degree of aging of the applied member.
The determination means increases the output voltage in one of the first generation unit and the second generation unit, while increasing the input voltage in the other of the first generation unit and the second generation unit. An image forming apparatus, characterized in that the increase in the output voltage is monitored and the degree of aging of the applied member is determined based on the increase in the output voltage on the one side and the increase in the input voltage on the other side. The determination means monitors an increase in the input voltage in the second generation unit while increasing the output voltage in the first generation unit, and increases the output voltage in the first generation unit and the second generation unit. The image forming apparatus according to claim 11, wherein the degree of aging of the applied member is determined based on the amount of increase in the input voltage in the generation unit. The determination means monitors an increase in the input voltage in the first generation unit while increasing the output voltage in the second generation unit, and increases the output voltage in the second generation unit and the first generation unit. The image forming apparatus according to claim 11, wherein the degree of aging of the applied member is determined based on the amount of increase in the input voltage in the generation unit. The image according to any one of claims 11 to 13, wherein the control means further includes an adjusting means for adjusting the separation promoting voltage according to the degree of aging of the applied member. Forming device. Photosensitive drum and
A motor that rotates the photosensitive drum and
A charging means for charging the surface of the photosensitive drum using a charging voltage, and
A boosting means having a primary winding and a secondary winding, boosting the input voltage input to the primary winding and outputting it to the secondary winding.
A voltage generating means that generates a charging voltage based on the voltage output from the boosting means, and
A power supply that generates the input voltage so that the charging voltage becomes the target voltage,
A detection means for detecting the input voltage and
With control means,
The control means
By controlling the motor to rotate the photosensitive drum,
Image formation characterized in that an abnormality of the photosensitive drum is determined based on the number of sampling values exceeding a threshold value among a plurality of sampling values acquired for the input voltage while the photosensitive drum rotates for a predetermined number of revolutions. apparatus. 15. The thirteenth aspect of the present invention, further comprising a threshold value determining means for determining the threshold value based on statistical values of a plurality of sampling values acquired for the input voltage while the photosensitive drum rotates for a predetermined number of revolutions. Image forming device.

Images