JP2017181567A - Image forming apparatus and program for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing the occurrence of paper passage failure and transfer failure without depending on an environmental condition and preventing melting of toner caused by unnecessary temperature rise.SOLUTION: The image forming apparatus includes transfer current application means S and R2 for outputting a transfer current applied to a carrier through a transfer nip area from the inner surface of a transfer belt in the transfer nip area N where an endless belt B rotated to convey a paper sheet P placed on an outer surface presses a carrier 181 for a toner image, current detection means 190 for detecting the leakage current not applied to the carrier of the transfer current, temperature increasing means 200 for increasing the temperature of the transfer belt, and control means for controlling the temperature increase of the transfer belt by the temperature increasing means on the basis of the value of the leakage current.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus and a program for the image forming apparatus.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed by exposing a uniformly charged surface of a photosensitive drum based on image data, and a toner image is formed by developing the electrostatic image. . Then, an image is formed on the paper by transferring and fixing the toner image onto the paper.

  It is known that a toner image is transferred to a sheet as follows. That is, in the nip region where the transfer belt is pressed against the photosensitive drum, the paper placed on the transfer belt and the toner image carried on the photosensitive drum are brought into close contact with each other. By applying a transfer current to the photosensitive drum from the transfer belt side through the paper closely attached to the toner image, the charged toner is attracted to the paper and the toner image is transferred to the paper.

  However, moisture may adhere to the surface of the transfer belt made of a high resistance material depending on environmental conditions such as temperature and humidity. The moisture can cause a phenomenon that the transfer current leaks at a high rate to the stretching roller and the driving unit for stretching the transfer belt. Due to the occurrence of such a leakage current, the transfer current is not sufficiently applied to the photosensitive drum, so that the sheet is electrostatically attracted to the transfer belt, and a sheet passing defect can occur frequently. Furthermore, problems may occur in the transfer of toner images to paper.

  By optimizing the output position of the transfer current and the resistance values of the transfer belt and the stretching roller, the leakage current can be suppressed to some extent, but it is difficult to prevent the above problems under all environmental conditions.

  As a conventional technique for preventing a paper passing defect due to environmental conditions, there is one described in Patent Document 1 below. That is, the transfer roller that transfers the toner image on the intermediate transfer belt to the sheet by applying a transfer bias by bringing the sheet into contact with the intermediate transfer belt, based on the temperature and humidity detection information in the image forming apparatus, Warm up for a specified time after turning on the power. This prevents the potential difference balance between the intermediate transfer belt and the transfer roller from deviating from a desired value due to fluctuations in the resistance value of the transfer roller due to environmental conditions. As a result, it is possible to prevent a paper passing defect caused by the paper being attracted and wound around the intermediate transfer belt or the like.

JP 2007-310270 A

  However, the above conventional technique has the following problems because it does not detect the moisture on the surface of the transfer roller as the transfer means.

  That is, there are cases where the amount of moisture on the surface of the transfer unit is larger than assumed based on the temperature and humidity of the atmosphere in the apparatus, and in this case, there is a possibility that moisture on the surface of the transfer unit is not properly removed due to the temperature rise. As a result, the bias current is not accurately applied due to the leakage current, which may cause a paper passing defect due to the sheet adsorbing to the transfer unit and a transfer defect.

  In some cases, the amount of water on the surface of the transfer unit is sufficiently smaller than assumed based on the temperature and humidity of the atmosphere in the apparatus. In this case, the temperature of the transfer unit may be unnecessarily increased. As a result, in a mechanism in which toner such as a developing machine and a drum cleaner arranged near the transfer unit is present, a problem that the toner melts and the toner cannot be conveyed can occur.

  The present invention has been made to solve the above problems. In other words, it is an object to prevent the occurrence of sheet passing defects and transfer defects regardless of environmental conditions, and to prevent toner melting due to unnecessary temperature rise.

  The above-described problems of the present invention are solved by the following means.

  (1) A carrier carrying a toner image on its surface and an endless belt, which are placed on the outer surface by rotating while forming a transfer nip region by pressing the carrier. A transfer belt for bringing the toner image into close contact with the recording medium in the transfer nip region and conveying the recording medium, and a transfer for applying to the carrier from the inner surface of the transfer belt via the transfer nip region A transfer current applying means for outputting a current; a current detecting means for detecting a leakage current that is not applied to the carrier among the transfer currents output from the transfer current applying means; and a temperature rise for raising the temperature of the transfer belt And an image form having control means for controlling the temperature rise of the transfer belt by the temperature raising means based on the value of the leakage current detected by the current detecting means. Apparatus.

  (2) It further has a conducting portion that contacts the inner surface of the transfer belt and is electrically connected to the housing of the image forming apparatus, and the current detection unit includes a current that flows through the housing through the conducting portion. Is detected as the leakage current. The image forming apparatus according to (1).

  (3) The image forming apparatus according to (2), wherein the conduction portion is a belt stretching roller that stretches the transfer belt.

  (4) The image forming apparatus according to any one of (1) to (3), wherein the temperature raising unit is a heater provided so as to be able to contact and separate from the transfer belt.

  (5) The image forming apparatus according to (4), wherein the heater is provided in a space inside the transfer belt generated by stretching the transfer belt.

  (6) The temperature raising unit according to any one of (1) to (3), wherein the temperature raising unit is a heater provided in at least one of belt stretching rollers that stretch the transfer belt. Image forming apparatus.

  (7) The control unit raises the temperature of the transfer belt by the temperature raising unit when the value of the leakage current detected by the current detection unit exceeds a preset threshold value. ) To (6).

  (8) There are a plurality of conducting parts, and the current detection unit flows to the housing through the conducting part that is closest to the output position of the transfer current by the current applying unit among the plurality of conducting parts. The image forming apparatus according to (2), wherein a current is detected as the leakage current.

  (9) There are a plurality of the conducting portions, and the current detection means is located upstream and downstream in the transport direction of the recording medium with respect to the output position of the transfer current by the current applying means among the plurality of conducting portions. The image forming apparatus according to (2), wherein a combined value of currents flowing through the casing via the nearest conducting portions is detected as the leakage current.

  (10) The image forming apparatus according to any one of (1) to (9), wherein the current detection unit detects the leakage current after the transfer belt has rotated one or more times.

  (11) A carrier that carries a toner image on its surface and an endless belt that is placed on the outer surface by rotating while forming a transfer nip region by pressing the carrier. An image forming apparatus having a transfer belt for bringing the toner image into close contact with a recording medium in the transfer nip region and transporting the recording medium from the inner surface of the transfer belt via the transfer nip region. A step (a) of outputting a transfer current to be applied to the body, a step (b) of detecting a leakage current not applied to the carrier among the transfer currents output in the step (a), A program for executing the procedure (c) for controlling the temperature rise of the transfer belt based on the value of the leakage current detected in the procedure (b).

  Using the fact that the leakage current that is not applied to the carrier among the transfer current depends on the amount of moisture on the surface of the transfer belt, the transfer belt surface is heated based on the leakage current to remove the moisture on the surface of the transfer belt. Thereby, regardless of the environmental conditions, it is possible to prevent the occurrence of sheet passing defects and transfer defects and to prevent the toner from melting due to unnecessary temperature increase.

1 is a block diagram illustrating a configuration of an image forming apparatus. FIG. 3 is an explanatory diagram schematically showing a configuration of an image forming unit of the image forming apparatus together with configurations of a leakage current detection unit and a transfer belt heater. 6 is a graph showing measured values of the ambient temperature in the vicinity of the transfer belt and the temperature of the transfer belt. 3 is a flowchart illustrating a warm-up operation of the image forming apparatus. 3 is a flowchart illustrating an image forming operation of the image forming apparatus.

  Hereinafter, an image forming apparatus and an image forming apparatus program according to an embodiment of the present invention will be described in detail with reference to the drawings. The dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from the actual ratios.

  FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

  The image forming apparatus 100 includes a CPU (Central Processing Unit) 110, a storage unit 120, a communication interface 130, an operation unit 140, a display unit 150, an image control unit 160, a reading unit 170, an image forming unit 180, a leakage current detection unit 190, And a transfer belt heater 200. These components are connected to each other via a bus 210 for exchanging signals.

  The CPU 110 controls each component of the image forming apparatus 100 and performs various arithmetic processes according to a program. That is, the CPU 110 performs overall control related to various processes including image formation while cooperating with each component constituting the image forming apparatus 100. Detailed functions of the CPU 110 will be described later.

  The storage unit 120 can be configured by a RAM (Random Access Memory), a ROM (Read Only Memory), and an HDD (Hard Disk Drive). A program executed by the CPU 110 and data processed by the CPU 110 are temporarily stored in the RAM. Various programs and various data are stored in the ROM. The HDD stores various programs including a program for controlling each component of the image forming apparatus 100, image data obtained through the communication interface 130 or the reading unit 170, and other various data.

  The communication interface 130 is an interface for performing communication between the image forming apparatus 100 and an external device such as an information processing apparatus (not shown). The communication interface 130 includes various network connection interfaces such as Ethernet (registered trademark), SATA, PCI Express, USB, and IEEE 1394, and various local connection interfaces such as wireless communication interfaces such as Bluetooth (registered trademark) and IEEE 802.11. Used.

  The operation unit 140 has various fixed types such as a touch panel for performing various settings, a numeric keypad for setting the number of copies, a start key for instructing start of operation, a stop key for instructing stop of operation, and a reset key for initializing various setting conditions. It consists of keys.

  The display unit 150 includes a touch panel that displays various types of information and inputs various settings, and a display lamp. In addition, the function which overlaps with the operation part 140 and the display part 150 can have either the operation part 140 or the display part 150.

  The image control unit 160 performs layout processing and rasterization processing of print data included in a print job received from the information processing apparatus or the like by the communication interface 130, and generates image data that is bitmap image data. A print job is a generic term for a print command for the image forming apparatus 100 and includes print data and print settings. The print data is data of a document to be printed, and the print data can include various data such as image data, vector data, and text data. Specifically, the print data may be PDL (Page Description Language) data, PDF (Portable Document Format) data, or TIFF (Tagged Image File Format) data. The print setting is a setting related to image formation on a recording medium paper and a setting related to post-processing of a printed material. Various settings may be included.

  The reading unit 170 applies light to a document set at a predetermined reading position on the document table with a light source such as a fluorescent lamp, and photoelectrically converts the reflected light with an imaging device such as a CCD (Charge Coupled Device) image sensor. Image data is generated from the electrical signal.

  The image forming unit 180 performs image formation based on image data on a sheet through the respective steps of charging, exposure, development, transfer, and fixing by an electrophotographic method, and outputs the sheet.

  The leakage current detection unit 190 constitutes a current detection unit. As will be described later, the leakage current detection unit 190 includes, in the transfer process by the image forming unit 180, a photoconductor among transfer currents to be applied to the photoconductor drum via a nip region where the transfer belt presses the photoconductor drum. Detects leakage current that is not applied to the drum. In the nip region, a transfer current is applied to the photosensitive drum through the paper, and the toner image on the photosensitive drum is attracted to the transfer belt by the electrostatic force through the paper, whereby the toner image is transferred to the paper. The

  The leakage current depends on the amount of moisture adhering to the transfer belt surface due to environmental conditions such as temperature and humidity. If the leakage current increases due to moisture adhering to the surface of the transfer belt, the transfer current is not sufficiently applied to the photosensitive drum, so that the sheet can be electrostatically attracted to the transfer belt and a paper passing defect can occur. Furthermore, problems such as transfer defects can occur in the transfer of toner images to paper.

  The transfer belt heater 200 constitutes a temperature raising means. The transfer belt heater 200 can remove moisture adhering to the transfer belt by evaporation by heating the transfer belt by heating.

  Detailed functions of the CPU 110 will be described.

  The CPU 110 constitutes a control unit. The CPU 110 controls the temperature increase of the transfer belt by the transfer belt heater 200 based on the value of the leakage current detected by the leakage current detection unit 190. The CPU 110 removes moisture on the surface of the transfer belt by heating the transfer belt with the transfer belt heater 200 when the detected leakage current value exceeds a preset threshold value. The threshold value is determined based on, for example, an experimental result of a relationship between the value of the leakage current and the occurrence rate of a paper passing failure due to moisture adhering to the transfer belt or a toner image transfer failure. The threshold value can be, for example, the value of the leakage current when the ratio of the leakage current to the transfer current is 10% to 15%. The threshold value is more preferably the value of the leakage current when the ratio of the leakage current to the transfer current is 10%.

  The CPU 110 controls the temperature increase of the transfer belt by the transfer belt heater 200, so that the value of the leakage current is maintained below a preset threshold value. As a result, the moisture on the surface of the transfer belt is maintained below a certain amount that does not cause a paper passing defect and a toner image transfer defect.

  FIG. 2 is an explanatory diagram schematically showing the configuration of the image forming unit of the image forming apparatus together with the configurations of the leakage current detecting unit and the transfer belt heater.

  The image forming unit 180 includes a photosensitive drum 181 and a charging unit 182 disposed in the periphery thereof, an optical writing unit 183, a developing unit 184, and a drum cleaner 185.

  The charging unit 182 charges the photosensitive drum 181 uniformly. The optical writing unit 183 writes an image information signal based on the image data to the charged photosensitive drum 181, and forms a latent image based on the image information signal on the photosensitive drum 181. The developing unit 184 develops the latent image with toner. As a result, a toner image which is a visible image is formed on the photosensitive drum 181 and is carried by the photosensitive drum 181.

  The transfer belt B is stretched by a plurality of rollers and is rotatably supported.

  The paper P is stored in the paper feed cassette C, fed by the paper feed unit C1, transported through the transport path, and placed on the outer surface of the endless transfer belt B via the registration roller R1. The paper P placed on the transfer belt B is conveyed to the transfer nip region N as the transfer belt B rotates. The transfer nip region N is a region where the transfer belt B presses the photosensitive drum 181 by the backup roller R2. In the transfer nip region N, the paper P is in close contact with the toner image carried on the photosensitive drum 181.

  The transfer bias current source S constitutes transfer current application means together with the backup roller R2. The transfer bias current source S outputs a transfer current (thick arrow in the figure) to be applied to the photosensitive drum 181 from the inner surface of the transfer belt B via the backup roller R2. When a transfer current is applied to the photosensitive drum 181 through the transfer nip region N, the transfer belt B becomes a positive potential relative to the photosensitive drum 181. As a result, the toner image having a negative potential carried on the photosensitive drum 181 is attracted to the transfer belt B via the paper P by the electrostatic force, and the toner image is transferred to the paper P. The paper P onto which the toner image has been transferred is conveyed to the fixing unit 186 by the transfer belt B.

  Among the belt stretching rollers that stretch the transfer belt B, the first position closest to the output position upstream in the transport direction of the paper P with respect to the output position of the transfer current from the backup roller R2 (hereinafter simply referred to as “output position”). The one stretching roller r1 is made of a conductor. The first tension roller r1 is electrically connected to the casing of the image forming apparatus 100, and constitutes a conductive portion. Similarly, the second stretching roller r2 closest to the output position downstream of the output position in the transport direction of the paper P is also made of a conductor. The second tension roller r2 is electrically connected to the housing of the image forming apparatus 100, and constitutes a conductive portion.

  The leakage current detection unit 190 is not applied to the photosensitive drum 181 among the transfer current output from the output position, and the housing of the image forming apparatus 100 via the first stretching roller r1 and the second stretching roller r2. The sum of the currents flowing through the body can be detected as a leakage current. The leakage current detection unit 190 is connected to the first stretching roller r1 and the second stretching roller r2, and the current connected between the supporting member that supports the first stretching roller r1 and the second stretching roller r2, respectively. It can be constituted by a total. The support member has conductivity and is electrically connected to the housing of the image forming apparatus 100. The first stretching roller r1 and the second stretching roller r2 constitute conductive portions that are closest to the output position in the upstream and downstream in the conveyance direction of the paper P, respectively.

  The leakage current detection unit 190 detects a current flowing through the housing of the image forming apparatus 100 via the first stretching roller r1 closest to the output position as a leakage current among the transfer currents output from the output position. Good.

  The leakage current accurately reflects the amount of moisture adhering to the surface of the transfer belt B due to environmental conditions such as temperature and humidity. On the other hand, since the ambient temperature near the transfer belt has a relatively large difference from the temperature of the transfer belt B, it is difficult to accurately estimate the amount of moisture adhering to the surface of the transfer belt B based on the ambient temperature near the transfer belt. is there.

  FIG. 3 is a graph showing measured values of the ambient temperature in the vicinity of the transfer belt and the temperature of the transfer belt. The horizontal axis of the graph indicates the time after the power is turned on and the warm-up operation is started. The vertical axis of the graph indicates the measured value of temperature.

  As shown in FIG. 3, it can be seen that the ambient temperature near the transfer belt B has a relatively large difference from the temperature of the transfer belt B.

  Referring to FIG. 2 again, the transfer belt heater 200 is provided in a space inside the transfer belt B generated by the transfer belt B being stretched by the first stretching roller r1 and the second stretching roller r2. Can be.

  The transfer belt heater 200 can be provided so as to be able to contact and separate from the transfer belt B. The transfer belt heater 200 can be brought into contact with the transfer belt B only during the operation of raising the temperature of the transfer belt B, and can be separated from the transfer belt B except during the operation.

  The transfer belt heater 200 may be provided in at least one of the first stretching roller r1 and the second stretching roller r2 that are in contact with the transfer belt B.

  The transfer belt heater 200 raises the temperature of the transfer belt when the leakage current detected by the leakage current detection unit 190 exceeds a preset threshold under the control of the CPU 110. Thereby, moisture on the surface of the transfer belt B is removed.

  The fixing unit 186 fixes the toner image on the paper P by applying heat and pressure to the paper P on which the toner image is transferred, and the paper P on which the image is formed by transferring and fixing the toner image is conveyed by a roller. It is transported through the road and discharged out of the device.

  The operation of the image forming apparatus will be described.

  FIG. 4 is a flowchart illustrating a warm-up operation of the image forming apparatus. This flowchart can be executed by the CPU 110 in accordance with an image forming system program stored in the storage unit 120 of the image forming apparatus 100.

  The CPU 110 starts a warm-up operation when the power is turned on (S101).

  The CPU 110 operates the transfer belt B for a predetermined time. The predetermined time can be, for example, a time during which the transfer belt B rotates at least once.

  CPU110 starts the detection of the leakage current by the leakage current detection part 190 (S103).

  When the CPU 110 determines that the value of the leakage current detected by the leakage current detection unit 190 is equal to or less than a preset threshold (S104: YES), the CPU 110 ends the detection of the leakage current (S105). The CPU 110 confirms completion of various processes by the warm-up operation (S106) and ends the warm-up operation (S107).

  If the CPU 110 determines that the leakage current detected by the leakage current detection unit 190 exceeds a preset threshold (S104: NO), the CPU 110 continues to detect the leakage current (S108), and the transfer belt heater The operation of 200 is started (S109).

  The CPU 110 continues the operation of the transfer belt heater 200 until it is determined that the value of the leakage current is not more than a preset threshold value (S110: NO, S111).

  If the CPU 110 determines that the leakage current detected by the leakage current detector 190 is equal to or less than a preset threshold value (S110: YES), the CPU 110 ends the operation of the transfer belt heater 200 (S112), and the leakage current The detection of is terminated (S105). The CPU 110 confirms completion of various processes by the warm-up operation (S106) and ends the warm-up operation (S107). The image formable state due to the end of the warm-up operation can be notified to the user by being displayed on the display unit 150 or the like.

  Moisture adherence to the surface of the transfer belt B occurs relatively remarkably during an operation immediately after the image forming apparatus 100 is left without operating for a long time in a high humidity environment. Therefore, by removing the surface moisture of the transfer belt B in the warm-up operation before the image formation of the image forming apparatus 100, it is possible to effectively prevent a paper passing defect and a transfer failure due to a leakage current.

  The detection of the leakage current and the temperature increase of the transfer belt B based on the detected value of the leakage current can be periodically executed even during the image forming operation after the warm-up operation is completed.

  FIG. 5 is a flowchart showing an image forming operation of the image forming apparatus. This flowchart can be executed by the CPU 110 in accordance with an image forming system program stored in the storage unit 120 of the image forming apparatus 100.

  The CPU 110 starts image formation on the paper P (S201).

  The CPU 110 waits until a preset set time for detecting the leak current elapses (S202: NO). When the set time is reached (S202: YES), the leak current detection unit 190 detects the leak current. Is started (S203). The setting time is set in advance based on experimental results such as the fluctuation history of the leakage current value during actual image forming operations under environmental conditions where moisture easily adheres to the surface of the transfer roller. The maximum time that does not exceed the set threshold may be determined. The set time can be, for example, 20 minutes to 1 hour.

  When the CPU 110 determines that a preset time set in advance for detection of leakage current has elapsed (S202: YES), the leakage current detection unit 190 starts detection of leakage current (S203).

  When the CPU 110 determines that the value of the leakage current detected by the leakage current detection unit 190 is equal to or less than a preset threshold value (S204: YES), the CPU 110 ends the detection of the leakage current (S205) and performs image formation. Continue (S206).

  The CPU 110 determines whether or not the image formation of the print job is finished until the next set time set in advance for detecting the leakage current is reached (S215). Since the time required for image formation per sheet is known, the product of the remaining number of sheets on which no image is formed and the time required for image formation per sheet is the remaining time of the predetermined time. The determination in step S215 is made depending on whether or not the number exceeds.

  When the CPU 110 determines that the image formation of the print job is completed before the set time set in advance for detecting the leakage current reaches next (S215: YES), the CPU 110 continues the image formation (S216), and the print job The image formation is terminated (S217).

  When the CPU 110 determines that the image formation of the print job does not end before the set time reaches the next time (S215: NO), the CPU 110 determines that the time set in advance for the detection of the leakage current elapses (S202: NO). ) Continue image formation. When the CPU 110 determines that the set time has been reached (S202: YES), the CPU 110 executes the operations of steps S203 to S215. As a result, even during the print job, the leakage current is periodically detected and the moisture on the surface of the transfer belt B is removed by increasing the temperature of the transfer belt B based on the detected leakage current value.

  In step S204, when the CPU 110 determines that the value of the detected leakage current exceeds a preset threshold value (S204: NO), the CPU 110 continues to detect the leakage current (S207). The CPU 110 stops image formation (S208) and starts the operation of the transfer belt heater 200 (S209).

  The CPU 110 continues the operation of the transfer belt heater 200 until it is determined that the value of the leakage current is not more than a preset threshold value (S210: NO, S211).

  When the CPU 110 determines that the leakage current detected by the leakage current detection unit 190 is equal to or less than a preset threshold value (S210: YES), the CPU 110 ends the operation of the transfer belt heater 200 (S212). The detection of is terminated (S106). Thereafter, the CPU 110 resumes image formation (S214), proceeds to step S215, and continues the processing.

  Note that the detection of the leakage current and the temperature increase of the transfer belt B based on the detected leakage current value can also be executed during the standby for image formation.

  This embodiment has the following effects.

  The transfer belt surface is dehydrated by raising the temperature of the transfer belt based on the leakage current. Thereby, regardless of the environmental conditions, it is possible to prevent the occurrence of sheet passing defects and transfer defects and to prevent the toner from melting due to unnecessary temperature increase.

  Further, the current flowing through the housing through the conductive portion that contacts the inner surface of the transfer belt and is electrically connected to the housing of the image forming apparatus is detected as a leakage current. Accordingly, the leakage current can be detected more accurately and easily by detecting the leakage current at a location closer to the transfer current output position.

  Further, a belt stretching roller that stretches the transfer belt is used as a conducting portion. As a result, the number of members that need to be added is reduced, and the leakage current can be detected with high accuracy at low cost.

  Further, the temperature raising means is constituted by a heater provided so as to be able to contact and separate from the transfer belt. This makes it possible to remove moisture on the surface of the transfer belt more effectively by bringing the heater into contact with the transfer belt only when the temperature of the transfer belt rises, and to prevent wear of the transfer belt due to friction when the heater is in contact with the transfer belt. Can be suppressed.

  Further, a heater of the temperature raising means is provided in a space inside the transfer belt generated by stretching the transfer belt. Thereby, the temperature of the transfer belt can be increased more effectively by providing the heater in a space having a high sealing degree by being surrounded by the transfer belt.

  Furthermore, the temperature of the transfer belt is raised when the value of the leakage current exceeds a preset threshold value. Thereby, the amount of moisture adhering to the transfer belt can be easily maintained to such an extent that no paper defects and poor transfer occur.

  Furthermore, a current flowing through the casing through the conduction portion closest to the transfer current output position among the plurality of conduction portions is detected as a leakage current. As a result, the leakage current can be detected at a location where the transfer current is most likely to leak.

  Further, the sum of the currents flowing through the casing through the conducting portions closest to the transfer current output position upstream and downstream of the transfer current output position among the plurality of conducting portions is detected as a leakage current. . As a result, the leakage current can be detected with high accuracy and the minimum necessary configuration.

  Further, the leakage current is detected after the transfer belt has rotated one or more times. Thereby, the leakage current in the actual use state of the image forming apparatus can be detected.

  The image forming apparatus and the image forming apparatus program according to the embodiment of the present invention have been described above, but the present invention is not limited to the above-described embodiment.

  For example, in the above-described embodiment, the photosensitive drum has been described as an example of the toner image carrier. However, one or a plurality of image forming units are provided, and after the primary transfer is performed on the intermediate transfer belt, two sheets are formed on the sheet. In the case of an image forming apparatus that performs the next transfer, the toner image carrier may be an intermediate transfer belt.

  Further, the temperature increase of the transfer belt may be performed using radiant heat from the heating means of the fixing unit.

  In addition, some or all of the functions executed by the program in the above-described embodiment may be replaced with hardware such as an electronic circuit.

  The recording medium is not limited to paper, and may be, for example, a plastic film or an envelope.

B transfer belt,
N transfer nip area,
P paper,
S transfer bias current source,
r1 first tension roller,
r2 Second tension roller,
R1 registration roller,
R2 backup roller,
100 image forming apparatus,
110 CPU,
180 image forming unit,
181 photoconductor drum,
190 Leakage current detector,
200 Transfer belt heater.

Claims (11)

A carrier carrying a toner image on the surface;
An endless belt that rotates while forming a transfer nip region by pressing the carrier, thereby bringing the toner image into close contact with the recording medium placed on the outer surface in the transfer nip region And a transfer belt for conveying the recording medium,
A transfer current applying means for outputting a transfer current to be applied to the carrier through the transfer nip region from the inner surface of the transfer belt;
Among the transfer currents output from the transfer current application means, current detection means for detecting a leakage current that is not applied to the carrier; and
A temperature raising means for raising the temperature of the transfer belt;
Control means for controlling the temperature rise of the transfer belt by the temperature raising means based on the value of the leakage current detected by the current detection means;
An image forming apparatus. A conductive portion that is in contact with the inner surface of the transfer belt and is electrically connected to the housing of the image forming apparatus;
The image forming apparatus according to claim 1, wherein the current detection unit detects a current flowing through the housing via the conduction unit as the leakage current.   The image forming apparatus according to claim 2, wherein the conductive portion is a belt stretching roller that stretches the transfer belt.   The image forming apparatus according to claim 1, wherein the temperature raising unit is a heater provided so as to be able to contact and separate from the transfer belt.   The image forming apparatus according to claim 4, wherein the heater is provided in a space inside the transfer belt generated by stretching the transfer belt.   4. The image forming apparatus according to claim 1, wherein the temperature raising unit is a heater provided in at least one of belt stretching rollers that stretch the transfer belt. 5.   7. The control unit according to claim 1, wherein when the value of the leakage current detected by the current detection unit exceeds a preset threshold value, the temperature of the transfer belt is increased by the temperature increase unit. The image forming apparatus according to claim 1. There are a plurality of the conductive parts,
The current detection unit detects, as the leakage current, a current flowing through the casing through the conduction unit that is closest to an output position of the transfer current by the current application unit among the plurality of conduction units. Item 3. The image forming apparatus according to Item 2. There are a plurality of the conductive parts,
The current detection unit includes the housing through the conduction unit that is closest to the output position of the transfer current by the current application unit in the upstream and the downstream in the conveyance direction of the recording medium among the plurality of conduction units. The image forming apparatus according to claim 2, wherein a total value of currents flowing through the body is detected as the leakage current.   The image forming apparatus according to claim 1, wherein the current detection unit detects the leakage current after the transfer belt has rotated one or more times. A carrier that carries a toner image on its surface, and an endless belt that rotates on the outer surface by forming a transfer nip region by pressing the carrier. An image forming apparatus having a transfer belt that closely contacts the toner image in the transfer nip region and conveys the recording medium;
A procedure (a) for outputting a transfer current to be applied to the carrier via the transfer nip region from the inner surface of the transfer belt;
A step (b) of detecting a leakage current that is not applied to the carrier among the transfer currents output in the step (a);
A procedure (c) for controlling the temperature increase of the transfer belt based on the value of the leakage current detected in the procedure (b);
A program for running