JP2021067879A - Image forming apparatus, method for determining replacement time, and program for determining replacement time - Google Patents

Abstract

To accurately determine the time to replace an image carrier.SOLUTION: An MFP comprises: an image carrier 23Y that has an electrostatic latent image formed on its surface, the electrostatic latent image being developed with toner into a toner image, and carries the toner image that is developed; an electrifying roller 22Y that provides an electric charge to the image carrier 23Y; a power supply circuit 145 that applies a voltage to the electrifying roller 22Y according to an input setting value; a current value sensor 117 that detects the current value of a current flowing in the image carrier 23Y; and a determination unit that determines the time to replace the image carrier 23Y based on performance data in which the value of the voltage applied to the electrifying roller 22Y is determined as an execution value by the power supply circuit 145 according to the setting value, the setting value, and the current value detected by the current value sensor 117.SELECTED DRAWING: Figure 4

Description

The present invention relates to an image forming apparatus, an exchange timing determination method and an exchange timing determination program, and particularly to an image forming apparatus for forming an image using toner, an exchange timing determining method executed by the image forming apparatus, and a computer. The present invention relates to an exchange timing determination program for executing a timing determination method.

An image forming apparatus represented by an MFP (Multifunction Peripheral) forms a toner image on a photoconductor drum by developing an electrostatic latent image formed on the photoconductor drum with toner. Since the photoconductor layer formed on the surface of this photoconductor drum deteriorates with use, it is replaced at the end of its life. As a method of determining the life period, a method is known in which the driving distance or the number of printed sheets reaches a predetermined threshold value, but the degree of deterioration of the photoconductor drum depends on how to use the MFP and the photoconductor drum. It may differ depending on individual differences.

Therefore, Japanese Patent Application Laid-Open No. 9-237018 includes a charged body having a photoconductor on the surface, a charging member arranged in contact with the photoconductor, and a voltage applying means for applying a voltage to the charging member. In an image forming apparatus that charges or eliminates the photoconductor via the charging member, a current detecting means for detecting a current output when charging or eliminating the photoconductor via the charging member, and the current. The first storage means for updating and storing the integrated value of the current detected by the detecting means, the integrated value of the current updated and stored by the first storage means, and the integrated value of the current corresponding to the life of the photoconductor are stored. Described is an image forming apparatus comprising: a control means for predicting the life of the photoconductor by comparison.

However, it is known that there are individual differences in the voltage applying means for applying a voltage to the charging member. FIG. 13 is a diagram showing an example of individual differences in the voltage applying means. The first quadrant shows the relationship between the input voltage and the output voltage of the voltage applying means, and the second quadrant shows the relationship between the voltage applied to the charging member and the current flowing through the charged body. Since the output voltage of the voltage applying means and the voltage applied to the charging member are the same, they are shown here on the same axis.

In the first quadrant, the relationship between the input voltage and the output voltage of each of the three voltage applying means HV1, HV2, and HV3 is shown. The voltage applying means HV1 has a smaller ratio of the output voltage to the input voltage than the voltage applying means HV2 and the voltage applying means HV3. The voltage applying means HV3 has a larger ratio of the output voltage to the input voltage than the voltage applying means HV1 and the voltage applying means HV2. In the voltage applying means HV2, the ratio of the output voltage to the input voltage is larger than that of the voltage applying means HV1 and smaller than that of the voltage applying means HV3.

For example, for an input voltage of 1600V, the voltage applying means HV2 has an output voltage of 1600V, whereas the voltage applying means HV1 has an output voltage smaller than 1600V and the voltage applying means HV3 has an output voltage larger than 1600V. .. Therefore, even if the same charged body has the same current value, the current flowing through the charged body is the largest when the voltage is applied to the charged body by the voltage applying means HV3, and the voltage is applied to the charged body by the voltage applying means HV2. Is applied, the current flowing through the charged body is the next largest, and when the voltage is applied to the charged body by the voltage applying means HV1, the current flowing through the charged body is the smallest. As described above, since the value of the current flowing through the charged body differs depending on which of the three voltage applying means HV1, HV2, and HV3 is used, there is a problem that the replacement time of the charged body cannot be accurately determined. ..

Japanese Unexamined Patent Publication No. 9-237018

One of the objects of the present invention is to provide an image forming apparatus capable of accurately determining the replacement time of the image carrier.

According to another aspect of the present invention, it is an object of the present invention to provide a method for determining the exchange time, which can accurately determine the exchange time of the image carrier.

According to still another aspect of the present invention, it is an object of the present invention to provide an exchange time determination program capable of accurately determining the exchange time of the image carrier.

According to an aspect of the present invention, in an image forming apparatus, an electrostatic latent image formed on a surface is developed by a toner, and an image carrier carrying the developed toner image and an image carrier are charged. The charging means, the power supply circuit that applies a voltage to the charging means according to the input set value, the current detecting means that detects the current value of the current flowing through the image carrier, and the voltage that the power supply circuit applies to the charging means according to the set value. A determination means for determining the replacement time of the image carrier is provided based on the performance data, the set value, and the current value detected by the current detecting means.

According to this aspect, a voltage is applied to the charging means by the power supply circuit, and the current value of the current flowing through the image carrier is detected. Then, the replacement time of the carrier is determined based on the performance data, the set value, and the current value determined by the value of the voltage applied to the charging means by the power supply circuit according to the set value as the execution value. Since the performance data determines the value of the voltage applied to the charging means by the power supply circuit according to the set value as the execution value, the difference between the voltage actually applied from the power supply circuit to the charging means and the set value can be considered. As a result, it is possible to provide an image forming apparatus capable of accurately determining the replacement time of the image carrier.

Preferably, the determining means compares the current value detected by the current detecting means with a threshold value determined for the set value.

According to this aspect, a predetermined relationship between the voltage applied to the charging means and the current flowing through the image carrier can be used.

Preferably, the determination means corrects the threshold based on the performance data.

According to this aspect, since the set value may be compared with the threshold value corrected based on the performance data, the replacement time can be easily determined.

Preferably, the determination means changes the threshold value to a larger value as the difference obtained by subtracting the set value from the execution value determined by the performance data with respect to the set value is larger, and changes the threshold value to a smaller value as the difference is smaller.

Preferably, the determination means determines the threshold value using the related information that defines the relationship between the set value, the difference, and the threshold value.

According to this aspect, the threshold value can be easily corrected.

Preferably, the determination means corrects the set value based on the performance data.

According to this aspect, since the set value may be compared with the effective value corrected based on the performance data with the threshold value determined for the effective value, the replacement time can be easily determined.

Preferably, the power supply circuit controls the current flowing through the charging means, and the performance data is determined by determining the value of the voltage applied to the charging means by the power supply circuit according to the set value and the value of the current flowing through the charging means as the execution values. The means determines the replacement time of the image carrier based on the performance data, the set value, and the current value detected by the current detecting means.

According to this aspect, since it is possible to cope with the fluctuation of the load of the charging means, it is possible to accurately determine the replacement time of the image carrier.

Preferably, a storage means for storing performance data in advance is further provided.

According to this aspect, it is easy to acquire performance data.

Preferably, the storage means is provided in the power supply circuit.

According to this aspect, it is easy to acquire the performance data peculiar to the power supply circuit.

According to another aspect of the present invention, the replacement time determination method is a replacement time determination method executed by the image forming apparatus, and the image forming apparatus is provided in the image forming means for forming the toner image, and the toner image is formed. An image carrier that carries an image carrier, a charging means that charges the image carrier, a power supply circuit that applies a voltage to the charging means according to an input set value, and a current that detects the current value of the current flowing through the image carrier. The replacement timing of the image carrier is determined based on the performance data, the set value, and the current value detected by the current detection means, which are determined by the detection means and the value of the voltage applied to the charging means by the power supply circuit according to the set value. Includes a determination step to determine.

According to this aspect, it is possible to provide an exchange time determination method capable of accurately determining the exchange time of the image carrier.

According to another aspect of the present invention, the replacement time determination program is a replacement time determination program executed by a computer that controls the image forming apparatus, and the image forming apparatus is provided in the image forming means for forming the toner image. An image carrier that carries a toner image, a charging means that applies a charge to the image carrier, a power supply circuit that applies a voltage to the charging means according to an input set value, and a current value of a current flowing through the image carrier. The image carrier is based on the performance data, the set value, and the current value detected by the current detecting means, in which the value of the voltage applied to the charging means by the power supply circuit according to the set value is set as the execution value. Have the computer perform a determination step to determine when to replace the.

According to this aspect, it is possible to provide an exchange time determination program capable of accurately determining the exchange time of the image carrier.

It is a perspective view which shows the appearance of the MFP in one of the Embodiments of this invention. It is a block diagram which shows the outline of the hardware structure of the MFP. It is a schematic cross-sectional view which shows the internal structure of the MFP. It is a figure which shows the detailed structure of an image formation unit. It is a figure which shows the relationship between the current flowing through a photosensitive drum and the film thickness of the photosensitive layer of a photosensitive drum. It is a block diagram which shows an example of the function which the CPU included in the MFP has. It is a figure which shows an example of the arithmetic expression which defined the relationship between a difference and a threshold value. It is a figure which shows an example of the flow of performance data setting processing. It is a flowchart which shows an example of the flow of exchange time determination processing. It is a figure which shows an example of the case where the effective value of a power supply circuit is larger than a set value. It is a figure which shows an example of the case where the effective value of a power supply circuit is larger than a set value. It is a block diagram which shows an example of the function which the CPU provided in the MFP in the 1st modification. It is a figure which shows an example of the individual difference of a voltage application means.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are the same. Therefore, detailed explanations about them will not be repeated.

FIG. 1 is a perspective view showing the appearance of the MFP in one of the embodiments of the present invention. FIG. 2 is a block diagram showing an outline of the hardware configuration of the MFP. With reference to FIGS. 1 and 2, the MFP (Multi Function Peripheral) 100 is an example of an image forming apparatus, and conveys a main circuit 110, a document reading unit 130 for reading a document, and a document to the document reading unit 130. It includes an automatic document transfer device 120, an image forming unit 140 that forms an image on paper based on image data, a paper feeding unit 150 that supplies paper to the image forming unit 140, and an operation panel 160 as a user interface.

The automatic document transfer device 120 automatically transports a plurality of sheets of paper set on the document tray one by one to the document reading position of the document reading unit 130, and the document reading unit 130 reads the image formed on the document. The created original is ejected onto the original paper ejection tray.

The image forming unit 140 forms an image on the paper conveyed by the feeding unit 150 by a well-known electrophotographic method. In the present embodiment, the image forming unit 140 forms an image on the paper conveyed by the paper feeding unit 150 under the image data and the image forming conditions corresponding to the medium type of the paper. The paper on which the image is formed is ejected to the output tray 159.

The main circuit 110 includes a CPU (Central Processing Unit) 111 that controls the entire MFP 100, a communication interface (I / F) unit 112, a ROM (ReadOnlyY Memory) 113, a RAM (Random Access Memory) 114, and It includes a hard disk drive (HDD) 115 as a large-capacity storage device, a facsimile unit 116, a current value sensor 117, and an external storage device 118. The CPU 111 is an example of a computer that executes a program. By executing the program, the CPU 111 is connected to the automatic document transfer device 120, the document reading unit 130, the image forming unit 140, the paper feeding unit 150, and the operation panel 160, and controls the entire MFP 100.

The ROM 113 stores a program executed by the CPU 111 or data necessary for executing the program. The RAM 114 is used as a work area when the CPU 111 executes a program. Further, the RAM 114 temporarily stores image data continuously sent from the document reading unit 130.

The operation panel 160 is provided on the upper part of the MFP 100. The operation panel 160 includes a display unit 161 and an operation unit 163. The display unit 161 is, for example, a liquid crystal display (LCD), and displays an instruction menu for the user, information on acquired image data, and the like. If the device displays an image instead of the LCD, for example, an organic EL (electroluminescence) display can be used.

The operation unit 163 includes a touch panel 165 and a hard key unit 167. The touch panel 165 is a capacitance type. The touch panel 165 is not limited to the capacitance method, and other methods such as a resistance film method, a surface acoustic wave method, an infrared method, and an electromagnetic induction method can be used. The hard key unit 167 includes a plurality of hard keys. The hard key is, for example, a contact switch.

The communication I / F unit 112 is an interface for connecting the MFP 100 to the network. The communication I / F unit 112 communicates with another computer or data processing device connected to the network by a communication protocol such as TCP (Transmission Control Protocol) or FTP (File Transfer Protocol). The network to which the communication I / F unit 112 is connected is a local area network (LAN), and the connection form may be wired or wireless. The network is not limited to a LAN, and may be a wide area network (WAN), a public switched telephone network (PSTN), the Internet, or the like.

The facsimile unit 116 is connected to the public switched telephone network (PSTN) and transmits facsimile data to or receives facsimile data from the PSTN. The facsimile unit 116 stores the received facsimile data in the HDD 115, converts it into print data that can be printed by the image forming unit 140, and outputs it to the image forming unit 140. As a result, the image forming unit 140 forms an image of the facsimile data received by the facsimile unit 116 on the paper. Further, the facsimile unit 116 converts the data stored in the HDD 115 into facsimile data and transmits the data to the facsimile apparatus connected to the PSTN.

The external storage device 118 is controlled by the CPU 111, and is equipped with a CD-ROM (Compact Disk Read OnlyY Memory) 118A or a semiconductor memory. In the present embodiment, an example in which the CPU 111 executes a program stored in the ROM 113 will be described, but the CPU 111 controls the external storage device 118 and reads a program for the CPU 111 to execute from the CD-ROM 118A. , The read program may be stored in the RAM 114 and executed.

The CPU 111 controls the image forming unit 140 to form an image of image data on a recording medium such as paper. The image data output by the CPU 111 to the image forming unit 140 includes image data such as print data received from the outside in addition to the image data input from the document reading unit 130.

The recording medium for storing the program to be executed by the CPU 111 is not limited to the CD-ROM118A, but is not limited to a CD-ROM118A, but is a flexible disk, a cassette tape, an optical disk (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versailles Disc). )), An IC card, an optical card, a mask ROM, a medium such as a semiconductor memory such as an EPROM (Erasable Program ROM) may be used. Further, the CPU 111 downloads the program from the computer connected to the network and stores it in the HDD 115, or the computer connected to the network writes the program to the HDD 115 and loads the program stored in the HDD 115 into the RAM 114. Then, it may be executed by the CPU 111. The program referred to here includes not only a program that can be directly executed by the CPU 111, but also a source program, a compressed program, an encrypted program, and the like.

FIG. 3 is a schematic cross-sectional view showing the internal configuration of the MFP. With reference to FIG. 3, the automatic document transfer device 120 separates one or more documents placed on the document tray and transfers them one by one to the document reading unit 130. The document reading unit 130 exposes an image of a document set on the document glass 11 by the automatic document transport device 120 with an exposure lamp 13 attached to a slider 12 that moves downward thereof. The reflected light from the document is guided to the lens 16 by the mirror 14 and the two reflecting mirrors 15 and 15A, and is imaged on the CCD (Charge Coupled Devices) sensor 18.

The reflected light imaged on the CCD sensor 18 is converted into image data as an electric signal in the CCD sensor 18. The image data is converted into printing data of cyan (C), magenta (M), yellow (Y), and black (K), and output to the image forming unit 140.

The image forming unit 140 includes yellow, magenta, cyan, and black image forming units 20Y, 20M, 20C, and 20K, respectively. Here, "Y", "M", "C" and "K" represent yellow, magenta, cyan and black, respectively. An image is formed by driving at least one of the image forming units 20Y, 20M, 20C, and 20K. When all of the image forming units 20Y, 20M, 20C, and 20K are driven, a full-color image is formed. Printing data of yellow, magenta, cyan, and black are input to the image forming units 20Y, 20M, 20C, and 20K, respectively. Since the image forming units 20Y, 20M, 20C, and 20K differ only in the colors of the toners they handle, the image forming unit 20Y for forming a yellow image will be described here.

On the other hand, the intermediate transfer belt 30 is suspended by the driving roller 33 and the driven roller 34 so as not to be loosened. When the drive roller 33 rotates counterclockwise in FIG. 3, the intermediate transfer belt 30 rotates counterclockwise in FIG. 3 at a predetermined speed. As the intermediate transfer belt 30 rotates, the driven roller 34 rotates counterclockwise.

As a result, the image forming units 20Y, 20M, 20C, and 20K sequentially transfer the toner image onto the intermediate transfer belt 30. The timing at which the image forming units 20Y, 20M, 20C, and 20K each transfer the toner image onto the intermediate transfer belt 30 is adjusted by detecting the reference mark attached to the intermediate transfer belt 30. As a result, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 30.

The toner image formed on the intermediate transfer belt 30 is transferred to the paper by the action of an electric field force by the secondary transfer roller 26 which is a transfer member. The paper is conveyed to the nip portion where the intermediate transfer belt 30 conveyed by the timing roller 31 and the secondary transfer roller 26 are in contact with each other. The paper on which the toner image is transferred is conveyed to the fixing roller 32, and is heated and pressurized by the fixing roller 32. As a result, the toner is melted and fixed on the paper. After that, the paper is ejected to the output tray 39.

A belt cleaning blade 29 is provided upstream of the image forming unit 20Y of the intermediate transfer belt 30. The belt cleaning blade 29 removes the toner remaining on the intermediate transfer belt 30 without being transferred to the paper.

Papers of different sizes are set in the paper cassettes 35, 35A, and 35B. The paper contained in each of the paper cassettes 35, 35A, 35B is supplied to the transport path by the take-out rollers 36, 36A, 36B attached to the paper cassettes 35, 35A, 35B, respectively, and is supplied by the paper feed roller 37. It is sent to the timing roller 31.

The MFP 100 drives all of the image forming units 20Y, 20M, 20C, and 20K when forming a full-color image, but any one of the image forming units 20Y, 20M, 20C, and 20K when forming a monochrome image. Drive one. Further, an image can be formed by combining two or more image forming units 20Y, 20M, 20C, and 20K. Here, an example in which the MFP 100 adopts a tandem system including image forming units 20Y, 20M, 20C, and 20K for forming toners of four colors on paper will be described, but one photoconductor drum has four colors. A 4-cycle method may be adopted in which the toners of the above are transferred to the paper in order.

The image forming units 20Y, 20M, 20C, and 20K have the same configuration except that the toners handled are different. Here, the image forming unit 20Y will be described as an example.

FIG. 4 is a diagram showing a detailed configuration of the image forming unit. With reference to FIG. 4, the image forming unit 20Y uniformly charges the surfaces of the exposure device 21Y into which yellow printing data is input, the photoconductor drum 23Y which is an image carrier, and the photoconductor drum 23Y. A charging roller 22Y for this purpose, a developing device 24Y, and a primary transfer roller 25Y for transferring a toner image formed on the photoconductor drum 23Y onto an intermediate transfer belt 30 which is an image carrier by the action of an electric current force. A drum cleaning blade 27Y, a power supply circuit 145, and a current value sensor 117 are provided to remove the transfer residual toner on the photoconductor drum 23Y.

A charging roller 22Y, an exposure device 21Y, a developing device 24Y, a primary transfer roller 25Y, and a drum cleaning blade 27Y are arranged in order around the photoconductor drum 23Y along the rotation direction of the photoconductor drum 23Y.

The charging roller 22Y is arranged so as to come into contact with the photoconductor drum 23Y. The photoconductor drum 23Y has a photosensitive layer made of a photoconductor such as OPC (organic optical semiconductor) formed on the surface of an aluminum cylinder.

The photoconductor drum 23Y is connected to the current value sensor 117. The power supply circuit 145 is controlled by the CPU 111, and applies a voltage corresponding to the set value to the charging roller 22Y according to the set value input from the CPU 111. The power supply circuit 145 is equipped with a ROM 147. The performance data of the power supply circuit 145 is stored in the ROM 147. Performance data will be described later.

When a predetermined voltage is applied to the charging roller 22Y by the power supply circuit 145, the charging roller 22Y charges the photoconductor drum 23Y. During this period, the value of the current flowing through the photoconductor drum 23Y is measured by the current value sensor 117.

The photoconductor drum 23Y is charged by the charging roller 22Y and then irradiated with the laser beam emitted by the exposure apparatus 21Y. A predetermined voltage is applied to the charging roller 22Y by the power supply circuit 145. The exposure apparatus 21Y exposes the image-corresponding portion on the surface of the photoconductor drum 23Y to form an electrostatic latent image. As a result, an electrostatic latent image is formed on the photoconductor drum 23Y. Subsequently, the developing device 24Y develops the electrostatic latent image formed on the photoconductor drum 23Y with the charged toner.

Specifically, the developing device 24Y includes a case 200Y, a second screw 203Y, a first screw 201Y, and a developing roller 221Y. A developing roller 221Y, a first screw 201Y, and a second screw 203Y are provided in the case 200Y in parallel. The rotation of the second screw 203Y and the first screw 201Y causes the developer to circulate in the case 200Y. The developing roller 221Y has a sleeve shape containing magnets having a plurality of magnetic poles, and is rotationally driven while maintaining a slight distance from the photoconductor drum 23Y. The developing roller 221Y is provided so as to face the first screw 201Y. Further, the developing roller 221Y is exposed from the case 200Y and faces the photoconductor drum 23Y. The developing roller 221Y has a built-in magnet, and magnetically attracts magnetic carriers together with non-magnetic toner to support the developer conveyed by the first screw 201Y.

The developing roller 221Y applies toner to the photoconductor drum 23Y to develop an electrostatic latent image. Specifically, a development bias is applied to the development roller 221Y. As a result, the potential of the peripheral surface of the developing roller 221Y is lower than the potential (approximately 0V) of the portion irradiated with the laser beam by the exposure device 21Y on the peripheral surface of the photoconductor drum 23Y, and the circumference of the photoconductor drum 23Y. It becomes higher than the potential of the part of the surface that is not irradiated with the laser beam. Since the toner in the developer carried by the developing roller 221Y is negatively charged, it adheres to the peripheral surface of the photoconductor drum 23Y irradiated with the laser beam. As a result, a toner image is formed on the peripheral surface of the photoconductor drum 23Y by the negatively charged toner.

The toner image formed on the photoconductor drum 23Y is transferred by the action of an electric field force on the intermediate transfer belt 30 which is an image carrier by the primary transfer roller 25Y. The toner remaining on the photoconductor drum 23Y without being transferred is removed from the photoconductor drum 23Y by the drum cleaning blade 27Y.

In the photoconductor drum 23Y, the film thickness of the photosensitive layer decreases due to wear or the like as the number of times of image formation increases. The current flowing through the photoconductor drum 23Y in a state where a predetermined voltage is applied to the charging roller 22Y by the power supply circuit 145 is proportional to the film thickness of the photosensitive layer of the photoconductor drum 23Y, and the thinner the film thickness, the larger the current.

FIG. 5 is a diagram showing the relationship between the current flowing through the photoconductor drum and the film thickness of the photosensitive layer of the photoconductor drum. The horizontal axis shows the current value, and the vertical axis shows the film thickness of the photosensitive layer. Using the relationship shown in FIG. 5, the film thickness of the photosensitive layer of the photosensitive drum 23Y is determined from the current flowing through the photosensitive drum 23Y. The MFP 100 in the present embodiment determines the life thickness of the photoconductor drum 23Y, and detects the current flowing through the photoconductor drum 23Y in a state where a predetermined voltage is applied to the charging roller 22Y by the power supply circuit 145. Then, the replacement time of the photoconductor drum 23Y is determined.

FIG. 6 is a block diagram showing an example of the functions of the CPU included in the MFP. The function shown in FIG. 6 is realized by the CPU 111 included in the MFP 100 by executing the replacement time determination program stored in the ROM 113, HDD 115, or CD-ROM 118A.

With reference to FIG. 6, the CPU 111 includes a current detection unit 51, a power supply control unit 53, a determination unit 55, and a performance data acquisition unit 57. The performance data acquisition unit 57 reads the performance data stored in the ROM 147 included in the power supply circuit 145 and outputs the performance data to the determination unit 55. The performance data is data showing the characteristics of the power supply circuit 145, and is a value unique to the power supply circuit 145. The performance data determines the effective value of the voltage applied to the charging roller 22Y by the power supply circuit 145 according to the set value. Performance data is generated by inspecting the power supply circuit 145 and stored in ROM 147. The performance data is stored in the ROM 147, for example, in the inspection process after the power supply circuit 145 is manufactured. When there are a plurality of set values, the performance data includes an effective value corresponding to each of the plurality of set values. When there is a predetermined correlation between the set value and the effective value, the performance data may be an arithmetic expression that defines the relationship between the set value and the effective value.

The power supply control unit 53 inputs a set value to the power supply circuit 145, and causes the power supply circuit 145 to apply a voltage to the charging roller 22Y. The power supply control unit 53 outputs the set value input to the power supply circuit 145 to the determination unit 55. The current detection unit 51 controls the current value sensor 117 to detect the current flowing through the photoconductor drum 23Y. The current detection unit 51 outputs the current value detected by the current value sensor 117 to the determination unit 55.

The determination unit 55 determines whether or not it is time to replace the photoconductor drum 23Y. Specifically, the determination unit 55 compares the current flowing through the photoconductor drum 23Y with a threshold value determined for the voltage applied to the charging roller 22Y, and determines that it is time to replace the current when it is larger than the threshold value. The threshold value is the upper limit of the current flowing through the photoconductor drum 23Y.

The determination unit 55 includes a threshold value correction unit 63 and a comparison unit 61. The threshold value correction unit 63 changes the threshold value based on the set value input from the power supply control unit 53 and the performance data input from the performance data acquisition unit 57. The threshold value correction unit 63 outputs the changed threshold value to the comparison unit 61. Specifically, the threshold value correction unit 63 calculates a difference obtained by subtracting a set value from the execution value, changes the threshold value to a larger value as the difference is larger, and changes the threshold value to a smaller value as the difference is smaller. When an arithmetic expression that defines the relationship between the difference and the threshold value is prepared, the changed threshold value may be obtained using the arithmetic expression.

When a threshold value table in which a plurality of threshold values are set corresponding to a plurality of voltage values is stored, the threshold value correction unit 63 may change the threshold value using the threshold value table. Specifically, the threshold value correction unit 63 determines the effective value corresponding to the set value based on the performance data. Then, the threshold value correction unit 63 changes the threshold value set for the set value in the threshold value table to the threshold value predetermined for the effective value in the threshold value table.

The comparison unit 61 compares the current value input from the current detection unit 51 with the threshold value input from the threshold value correction unit 63. The comparison unit 61 determines that the photoconductor drum 23Y is replacement time when the current value is larger than the threshold value, and determines that the photoconductor drum 23Y is not replacement time when the current value is equal to or less than the threshold value. When the photoconductor drum 23Y determines that it is time to replace the photoconductor drum 23Y, the comparison unit 61 displays, for example, a message indicating that it is time to replace the photoconductor drum 23Y on the display unit 161.

FIG. 7 is a diagram showing an example of an arithmetic expression that defines the relationship between the difference and the threshold value. With reference to FIG. 7, the horizontal axis represents the difference and the vertical axis represents the threshold. The arithmetic expression is represented by a function in which the difference and the threshold value are proportional to each other. The function sets a larger threshold as the difference is larger, and a smaller threshold as the difference is smaller.

FIG. 8 is a diagram showing an example of the flow of performance data setting processing. The performance data setting process is a process executed by the inspection computer when the inspection computer inspecting the power supply circuit 145 executes the performance data setting program. With reference to FIG. 8, the inspection computer sets a set value in the power supply circuit 145 to be inspected. Specifically, a command including a set value is input to the input terminal of the power supply circuit 145. Then, the output voltage of the power supply circuit 145 is detected (step S02). The inspection computer causes a voltmeter to measure the voltage between the output terminals of the power supply circuit 145, and acquires the voltage from the voltmeter.

In the next step S03, the voltage acquired from the voltmeter is set to the effective value, and the process proceeds to step S04. In step S04, performance data associated with the set value set in the power supply circuit 145 in step S01 and the voltage set in the execution value in step S03 is generated, and the performance data is stored in the ROM 147 included in the power supply circuit 145. And end the process. When performance data for determining the effective value is generated for each of the plurality of set values, steps S01 to S04 are repeated for the number of set values.

FIG. 9 is a flowchart showing an example of the flow of the replacement time determination process. The replacement time determination process is a process executed by the CPU 111 when the CPU 111 included in the MFP 100 executes the exchange time determination program stored in the ROM 113, HDD 115, or CD-ROM 118A. With reference to FIG. 9, the CPU 111 reads the performance data from the ROM 147 included in the power supply circuit 145 (step S21), and proceeds to the process in step S22.

In step S22, the set value is set in the power supply circuit 145, and the process proceeds to step S23. At this stage, a voltage is applied from the power supply circuit 145 to the charging roller 22Y. Specifically, a command including a set value is input to the input terminal of the power supply circuit 145. In step S23, the effective value is determined, and the process proceeds to step S24. In the performance data, the effective value determined for the set value is determined. In step S24, the difference obtained by subtracting the set value from the effective value is calculated, and the process proceeds to step S25.

In step S25, the changed threshold value is determined using the arithmetic expression shown in FIG. 7, and the process proceeds to step S26. In step S26, the threshold value determined for the set value is changed to the threshold value determined in step S25, and the process proceeds to step S27.

In step S27, the current flowing through the photoconductor drum 23Y is detected, and the process proceeds to step S28. The current measured by the current value sensor 117 is acquired. In step S28, it is determined whether or not the current flowing through the photoconductor drum 23Y is larger than the threshold value changed in step S26. If the current flowing through the photoconductor drum 23Y is greater than the changed threshold, the process proceeds to step S29, otherwise the process ends. In step S29, it is determined that it is time to replace the photoconductor drum 23Y, and the process proceeds to step S30. In step S30, a message notifying that it is time to replace the photoconductor drum 23Y is displayed on the display unit 161 and the process ends.

<Example>
FIG. 10 is a diagram showing an example when the effective value of the power supply circuit is larger than the set value. In FIG. 10, the upper graph shows the current value flowing through the photoconductor drum 23Y with respect to the number of printed sheets, and the lower graph shows the film thickness of the photoconductor drum 23Y with respect to the number of printed sheets. The number of prints is directly proportional to the current value flowing through the photoconductor drum 23Y, and the current value increases as the number of prints increases. The number of printed sheets is directly proportional to the film thickness of the photoconductor drum 23Y, and the current value decreases as the number of printed sheets increases.

When the effective value of the power supply circuit 145 is larger than the set value, the threshold value is changed to a larger value. Therefore, the film thickness of the photoconductor drum 23Y in the number of printed sheets P2 at the time when the current value exceeds the threshold value after the change is close to the film thickness predetermined for the replacement time. Therefore, the replacement time of the photoconductor drum 23Y is appropriately determined.

When the effective value of the power supply circuit 145 is larger than the set value, when the threshold value is not changed to a larger value, the film thickness of the photoconductor drum 23Y in the number of prints P1 at the time when the current value exceeds the threshold value is in advance with respect to the replacement time. It is larger than the specified film thickness. Therefore, when the effective value of the power supply circuit 145 is larger than the set value, the threshold value is changed to a larger value, so that the photoconductor drum 23Y is not determined to be replaced even though it has not reached the replacement time. Can be done.

FIG. 11 is a diagram showing an example when the effective value of the power supply circuit is smaller than the set value. In FIG. 11, the upper graph shows the current value flowing through the photoconductor drum 23Y with respect to the number of printed sheets, and the lower graph shows the film thickness of the photoconductor drum 23Y with respect to the number of printed sheets. The number of prints is directly proportional to the current value flowing through the photoconductor drum 23Y, and the current value increases as the number of prints increases. The number of printed sheets is directly proportional to the film thickness of the photoconductor drum 23Y, and the current value decreases as the number of printed sheets increases.

If the effective value of the power supply circuit 145 is smaller than the set value, the threshold value is changed to a smaller value. Therefore, the film thickness of the photoconductor drum 23Y in the number of printed sheets P2 at the time when the current value exceeds the threshold value after the change is close to the film thickness predetermined for the replacement time. Therefore, the replacement time of the photoconductor drum 23Y is appropriately determined.

When the effective value of the power supply circuit 145 is smaller than the set value, when the threshold value is not changed to a smaller value, the film thickness of the photoconductor drum 23Y in the number of prints P2 at the time when the current value exceeds the threshold value is predetermined with respect to the replacement time. It is smaller than the specified film thickness. Therefore, when the effective value of the power supply circuit 145 is smaller than the set value, the threshold value is changed to a smaller value, so that the replacement time is not notified even after the replacement time of the photoconductor drum 23Y has passed. Can be done.

<First modification>
The MFP 100 in the first modification corrects the set value so that the voltage applied to the charging roller 22Y by the power supply circuit 145 becomes the same value as the set value, instead of changing the threshold value with respect to the set value. Since the MFP 100 in the first modification corrects the set value based on the performance data, the CPU 111 may compare the set value corrected based on the performance data with the threshold value, so that the replacement time can be easily changed. You can judge. Hereinafter, the value set in the power supply circuit 145 is referred to as an input value.

FIG. 12 is a block diagram showing an example of the function of the CPU included in the MFP in the first modification. The function shown in FIG. 12 is realized by the CPU 111 included in the MFP 100 by executing the replacement time determination program stored in the ROM 113, HDD 115, or CD-ROM 118A.

With reference to FIG. 12, the difference from the function shown in FIG. 6 is that the determination unit 55 is changed to the determination unit 55A and the set value correction unit 71 is added. Since the other functions are the same as those shown in FIG. 6, the description is not repeated here.

The set value correction unit 71 corrects the set value based on the performance data. Specifically, the input value input to the power supply circuit 145 is changed from the set value so that the voltage applied to the charging roller 22Y by the power supply circuit 145 becomes the same value as the set value. Specifically, the set value correction unit 71 determines the set value associated with the same effective value as the set value in the performance data as the input value.

The set value correction unit 71 outputs the input value to the power supply control unit 53. In this case, the power supply control unit 53 applies a voltage corresponding to the input value to the charging roller 22Y. As a result, the effective value becomes equal to the set value.

Therefore, the comparison unit 61 included in the determination unit 55A compares the current value input from the current detection unit 51 with the threshold value determined for the set value. The comparison unit 61 determines that the photoconductor drum 23Y is not the replacement time when the current value is not less than the threshold value, and determines that the photoconductor drum 23Y is not the replacement time when the current value is not less than the threshold value.

<Second modification>
The power supply circuit 145 may control the current flowing through the charging roller 22Y. Specifically, the voltage corresponding to the set value is applied to the charging roller 22Y according to the set value input from the power supply circuit 145 and the CPU 111, and the voltage and the current are applied to the charging roller 22Y so that the current value corresponding to the set value flows through the charging roller 22Y. Control.

In the second modification, the performance data defines the value of the voltage applied to the load by the power supply circuit according to the set value and the value of the current flowing through the load as the execution value. Also, the threshold is set for a set of voltage and current. Therefore, the threshold value correction unit 63 in the second modification sets a threshold value determined for the set value of the voltage value and the current value as a set of the effective value of the voltage and the effective value of the current determined by the performance data. Change to the threshold value set for.

In the second modification, since the voltage applied to the charging roller 22Y and the current flowing through the charging roller 22Y are controlled by the power supply circuit 145, the light is exposed even when the load of the charging roller 22Y changes with time. The replacement time of the body drum 23Y can be accurately determined.

<Third modification example>
The performance data may be stored in the HDD 115 included in the MFP 100. Further, the timing at which the performance data is stored in the HDD 115 is not limited, but is at the stage where the power supply circuit 145 is incorporated.

As described above, in the MFP 100 of the present embodiment, the electrostatic latent image formed on the surface is developed by the toner, and the photoconductor drum 23Y carrying the developed toner image and the photoconductor drum 23Y are charged. The charging roller 22Y to be charged, the power supply circuit 145 that applies a voltage to the charging roller 22Y according to the input set value, the current value sensor 117 that detects the current value of the current flowing through the photoconductor drum 23Y, and the power supply circuit 145 are set values. A CPU 111 for determining the replacement time of the photoconductor drum 23Y based on the performance data, the set value, and the current value detected by the current value sensor 117, in which the value of the voltage applied to the charging roller 22Y is determined as the execution value according to the above. .. The CPU 111 determines the replacement time of the photoconductor drum 23Y by using a predetermined relationship between the voltage applied to the charging roller 22Y and the current flowing through the photoconductor drum 23Y. Since the performance data determines the value of the voltage applied to the charging roller 22Y by the power supply circuit 145 according to the set value as the execution value, the difference between the voltage actually applied from the power supply circuit 145 to the charging roller 22Y and the set value is taken into consideration. The replacement time is determined. Therefore, the replacement time of the photoconductor drum 23Y can be accurately determined.

Further, since the CPU 111 compares the current value detected by the current value sensor 117 with the threshold value determined for the set value, the voltage applied to the charging roller 22Y and the current flowing through the photoconductor drum 23Y are between the voltage and the current flowing through the photoconductor drum 23Y. The replacement time of the photoconductor drum 23Y can be determined using a predetermined relationship.

Further, since the CPU 111 corrects the threshold value based on the performance data, the replacement time can be accurately determined. Further, since the CPU 111 may compare the set value with the threshold value corrected based on the performance data, the replacement time can be easily determined.

Further, the CPU 111 may store in advance related information that defines the relationship between the set value, the difference obtained by subtracting the set value from the execution value, and the threshold value. In this case, since the threshold value is determined using the related information, the CPU 111 can easily correct the threshold value.

Further, since the power supply circuit 145 includes the ROM 147 in which the performance data is stored, the CPU 111 can easily acquire the performance data unique to the power supply circuit 145.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

100 MFP, 111 CPU, 20Y, 20M, 20C, 20K image forming unit, 21Y, 21M, 21C, 21K exposure device, 22Y, 22M, 22C, 22K charging roller, 23Y, 23M, 23C, 23K photoconductor drum, 24Y, 24M, 24C, 24K developer, 25Y, 25M, 25C, 25K primary transfer roller, 26 secondary transfer roller, 27Y, 27M, 27C, 27K drum cleaning blade, 29 belt cleaning blade, 30 intermediate transfer belt, 31 timing roller , 32 Fixing roller, 33 Drive roller, 34 Driven roller, 35, 35A, 35B Paper cassette, 37 Paper roller, 39 Paper output tray, 200Y case, 201Y 1st screw, 203Y 2nd screw, 221Y developing roller, 51 Current detection unit, 53 power supply control unit, 55, 55A judgment unit, 57 performance data acquisition unit, 61 comparison unit, 63 threshold correction unit, 71 set value correction unit.

Claims (11)

An electrostatic latent image formed on the surface is developed with toner, and an image carrier that supports the developed toner image and an image carrier.
A charging means for imparting an electric charge to the image carrier,
A power supply circuit that applies a voltage to the charging means according to the input set value,
A current detecting means for detecting the current value of the current flowing through the image carrier, and
Replacement of the image carrier based on performance data in which the value of the voltage applied to the charging means by the power supply circuit according to the set value is set as an execution value, the set value, and the current value detected by the current detection means. An image forming apparatus including a determination means for determining the timing. The image forming apparatus according to claim 1, wherein the determination means compares the current value detected by the current detecting means with a threshold value determined for the set value. The image forming apparatus according to claim 2, wherein the determination means corrects the threshold value based on the performance data. The determination means changes the threshold value to a larger value as the difference obtained by subtracting the set value from the execution value determined by the performance data with respect to the set value is larger, and reduces the threshold value to a smaller value as the difference is smaller. The image forming apparatus according to claim 3, which is modified. The image forming apparatus according to claim 4, wherein the determination means determines the threshold value by using the related information that determines the relationship between the set value, the difference, and the threshold value. The image forming apparatus according to claim 1 or 2, wherein the determination means corrects the set value based on the performance data. The power supply circuit controls the current flowing through the charging means according to the set value.
In the performance data, the value of the voltage applied to the charging means by the power supply circuit according to the set value and the value of the current flowing through the charging means are defined as execution values.
The image according to any one of claims 1 to 6, wherein the determination means determines the replacement time of the image carrier based on the performance data, the set value, and the current value detected by the current detection means. Forming device. The image forming apparatus according to any one of claims 1 to 7, further comprising a storage means for storing the performance data in advance. The image forming apparatus according to claim 8, wherein the storage means is provided in the power supply circuit. It is a replacement time determination method executed by the image forming apparatus.
The image forming apparatus
An image carrier provided on the image forming means for forming the toner image and supporting the toner image, and an image carrier.
A charging means for imparting an electric charge to the image carrier,
A power supply circuit that applies a voltage to the charging means according to the input set value,
A current detecting means for detecting the current value of the current flowing through the image carrier, and
Replacement of the image carrier based on performance data in which the value of the voltage applied to the charging means by the power supply circuit according to the set value is set as an execution value, the set value, and the current value detected by the current detection means. A method for determining the replacement time, which includes a determination step for determining the time. An exchange time determination program executed by a computer that controls an image forming apparatus.
The image forming apparatus
An image carrier provided on the image forming means for forming the toner image and supporting the toner image, and an image carrier.
A charging means for imparting an electric charge to the image carrier,
A power supply circuit that applies a voltage to the charging means according to the input set value,
A current detecting means for detecting the current value of the current flowing through the image carrier, and
Replacement of the image carrier based on the performance data, the set value, and the current value detected by the current detecting means, in which the value of the voltage applied to the charging means by the power supply circuit according to the set value is set as the execution value. A replacement timing determination program that causes the computer to execute a determination step for determining the timing.

Images