JP2023133119A - Image forming apparatus - Google Patents

Abstract

To provide a technique to accurately determine whether a member of an image forming apparatus is replaced despite the absence of a replacement detection mechanism.SOLUTION: An image forming apparatus is used which comprises a replaceable roller member, application means that applies voltage to the roller member, current detection means that detects current flowing in the roller member applied with voltage, and control means. The control means calculates a value of inclination of current-voltage characteristics of the roller member based on first current detected when first voltage is applied to the roller member and second current detected when second voltage is applied to the roller member, and determines whether the roller member is replaced based on an amount of change from a value of first inclination calculated at a first timing to a value of second inclination calculated at a second timing later than the first timing.SELECTED DRAWING: Figure 7

Description

The present invention relates to an image forming apparatus.

Conventionally, electrophotographic image forming apparatuses include those that directly transfer a toner image from a photoreceptor to a transfer material, and those that transfer a toner image primarily from a photoreceptor to an intermediate transfer belt and secondarily transfer it to a transfer material. There are image forming apparatuses that use an intermediate transfer method to output images.

When these image forming apparatuses form images, a transfer voltage is applied to the transfer roller. As a result of the voltage application, the resistance value of the transfer roller changes irreversibly over time of use of the device. If the resistance value of the transfer roller changes beyond a predetermined value, there is a risk that a transfer failure will occur and it will not be possible to form a good image even if a set transfer voltage is applied.

Therefore, it has been proposed to notify the user to replace the transfer roller when it is determined that the transfer roller has reached the end of its lifespan. To determine the lifespan, for example, you can set the lifespan in advance based on the number of prints or the total rotation time, or measure the resistance value of the transfer roller, and if the measured resistance value is outside the specified tolerance range, the transfer roller There are ways to determine when a product has reached its lifespan.

Here, in measuring the resistance value of a transfer roller, etc., it is affected by the environment such as temperature and humidity. Therefore, Patent Document 1 proposes a method of accurately measuring the resistance value based on the resistance value of the transfer roller detected by the resistance detection means and the environmental information detected by the environment detection means.

Further, in Patent Document 2, for a member whose electrical characteristic of resistance value changes with energization, the resistance value is detected when two or more levels of current or voltage are switched and applied. The authors have also proposed a method of determining the deterioration state by calculating the slope of the current-voltage characteristic from the detected resistance value and determining the lifespan of the member.

Japanese Patent Application Publication No. 2003-195700 JP 2019-159132 Publication

If the image forming apparatus has a replacement detection mechanism that detects whether a member that has been notified to the user that it has reached the end of its service life has been replaced, the occurrence of replacement can be automatically detected after the user replaces the member. Thereby, the image forming apparatus can reset the lifespan of the member that is being counted for management purposes, and can start counting the lifespan of the replaced member anew. On the other hand, if there is no replacement detection mechanism, it is necessary for the user to manually reset the lifespan after replacing a member, for example, by operating an operation panel. However, if the user forgets to perform an operation and the lifespan is not reset, the lifespan of the replaced member will not be properly counted, resulting in the problem that the lifespan cannot be calculated correctly.

The present invention has been made in view of the above problems, and an object thereof is to provide a technique for accurately determining whether a member of an image forming apparatus has been replaced, even in the absence of a replacement detection mechanism. .

The present invention employs the following configuration. That is,
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on a first current detected when a first voltage is applied to the roller member and a second current detected when a second voltage is applied to the roller member, Calculating the value of the slope of the current-voltage characteristic of the roller member,
The roller member is adjusted based on the amount of change from the first slope value calculated at the first timing to the second slope value calculated at the second timing after the first timing. The image forming apparatus is characterized by determining whether or not it has been replaced.

The present invention employs the following configuration. That is,
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Calculating the difference between the maximum value and the average value of the current detected after the voltage is applied to the roller member,
The roller member is adjusted based on the amount of change from the first difference value calculated at the first timing to the second difference value calculated at the second timing after the first timing. The image forming apparatus is characterized by determining whether or not it has been replaced.

The present invention also employs the following configuration. That is,
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on at least three levels of voltage applied to the roller member and each current detected when each voltage is applied, the slope of the current-voltage characteristics of at least two or more types of the roller member is determined. Calculate the determined index value,
The roller member is moved based on the value of the first index value calculated at the first timing and the value of the second index value calculated at the second timing after the first timing. This image forming apparatus is characterized by determining whether or not it has been replaced.

According to the present invention, it is possible to provide a technique for accurately determining whether a member of an image forming apparatus has been replaced even in the absence of a replacement detection mechanism.

Schematic sectional view of an image forming apparatus according to an embodiment Diagram explaining the relationship between detection resistance value and component life in one example Diagram explaining current-voltage characteristics in one example Diagram explaining the relationship between the number of prints and current-voltage characteristics in one example Diagram explaining the relationship between roller tolerance and current-voltage characteristics in one example Diagram illustrating changes in current-voltage characteristics due to durability in one example Flow diagram illustrating one embodiment A diagram explaining the rising waveform of voltage and current in one embodiment Diagram illustrating changes in overshoot amount in one example Flow diagram illustrating one embodiment Graph showing a current-voltage characteristic curve regarding a transfer roller in one embodiment Graph showing two types of slopes of current-voltage characteristic curve in one example

Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the following examples should be changed as appropriate depending on the configuration and various conditions of the device to which the present invention is applied. Therefore, unless there is a specific description, it is not intended to limit the scope of the present invention.

Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

[Example 1]
1. Overall Configuration of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 of this embodiment is a tandem image forming apparatus (laser beam printer) that uses an intermediate transfer method to form a full-color image using an electrophotographic method. Note that the image forming apparatus to which the present invention is applied is not limited thereto, and can be applied to various image forming apparatuses such as copying machines and printers that utilize electrophotography or electrostatic recording.

The image forming apparatus 100 includes first, second, third, and fourth image forming sections PY, PM, PC, and PK as a plurality of image forming sections. The first, second, third, and fourth image forming units PY, PM, PC, and PK form yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively. . In this embodiment, the configuration and operation of each of the image forming units PY, PM, PC, and PK are substantially the same except for the color of toner used. Therefore, if no particular distinction is required, the suffixes Y, M, C, and K of the reference numerals representing elements for one of the colors will be omitted, and the elements will be generally described.

The image forming section P has a drum-shaped electrophotographic photoreceptor (photoreceptor), that is, a photoreceptor drum 1 as an image carrier. The photosensitive drum 1 is rotationally driven in the direction of an arrow R1 in the drawing by a driving means (not shown). Around the photosensitive drum 1, a primary charging roller 2 as a primary charging means composed of a roller-type charging member and an exposure device (laser unit) as an exposure means (image writing means) are arranged along the rotation direction of the photosensitive drum 1. ) 3. A developing device 4 as a developing means is arranged. Subsequently, a primary transfer roller 5 as a first transfer roller and a drum cleaner 6 as a photoreceptor cleaning means are respectively arranged.

The developing device 4 includes a developing roller 41 as a developer carrier, and a toner container 42 containing toner as a developer. The drum cleaner 6 includes a drum cleaning blade 61 as a cleaning means and a waste toner container 62.

The intermediate transfer belt 8 serving as an intermediate transfer member is stretched between a drive roller 9 and a tension roller 10, and is driven to rotate in the direction of arrow R2 in the figure by transmitting a driving force to the drive roller 9.

The primary transfer roller 5 is pressed toward the photosensitive drum 1 via the intermediate transfer belt 8 . The primary transfer roller 5 and the photosensitive drum 1 are in contact with each other via the intermediate transfer belt 8 to form a primary transfer portion (primary transfer nip) N1.

A secondary transfer roller 11 serving as a second transfer roller is arranged on the outer peripheral surface side of the intermediate transfer belt 8 at a position facing the drive roller 9 . The secondary transfer roller 11 is pressed toward the drive roller 9 via the intermediate transfer belt 8 . The secondary transfer roller 11 and the drive roller 9 are in contact with each other via the intermediate transfer belt 8, forming a secondary transfer portion (secondary transfer nip) N2. In this embodiment, the drive roller 9 also serves as a roller facing the secondary transfer roller.

A belt cleaner 52 serving as intermediate transfer belt cleaning means is disposed on the outer peripheral surface of the intermediate transfer belt 8 at a position facing the tension roller 10 . The belt cleaner 52 includes a belt cleaning blade 21 and a waste toner container 22 as contact members.

A replaceable intermediate transfer belt unit 50 is composed of the primary transfer roller 5, intermediate transfer belt 8, drive roller 9, tension roller 10, belt cleaner 52, and the like.

In this embodiment, in each image forming section P, the photosensitive drum 1, charging roller 2, developing device 4, and drum cleaner 6 integrally constitute a process cartridge 7. Each of the process cartridges 7Y, 7M, 7C, and 7K can be attached to and detached from the apparatus main body 110 of the image forming apparatus 100, respectively.

In this embodiment, the configurations of the process cartridges 7Y, 7M, 7C, and 7K are substantially the same, and the toner contained in each of the toner containers 42Y, 42M, 42C, and 42K is yellow (Y) and magenta (M). , cyan (C), and black (K).

Further, the image forming apparatus 100 is provided with a control board 25 on which an electric circuit for controlling the image forming apparatus 100 is mounted. The control board 25 is equipped with a CPU 26 as a control means. The CPU 26 operates according to programs and user instructions, and collectively controls the overall operation of the image forming apparatus 100 related to image formation. The CPU 26 controls drive control means such as a drive source for transporting the transfer material S, a drive source for the intermediate transfer belt 8 and each image forming section P, an application means for controlling voltage applied during image formation, a current detection means, and temperature and humidity. The operation of the device is controlled based on signals from temperature and humidity sensors (environmental sensors) that detect environmental information. The control board 25 includes a memory as a storage section.

2. Transfer Configuration Next, the configuration regarding primary transfer and secondary transfer in this embodiment will be explained in more detail. In this embodiment, an intermediate transfer belt 8, which can be easily miniaturized, is used as the intermediate transfer member.

The intermediate transfer belt 8 is an endless belt made of a resin material to which a conductive agent is added to impart conductivity. The intermediate transfer belt 8 is stretched between two axes, a drive roller 9 and a tension roller 10, and the tension roller 10 applies a total tension of 100N. As the intermediate transfer belt 8 of this example, an endless belt with a thickness of 70 μm was used, which was made of polyimide resin whose volume resistivity was adjusted to 1×10E10 Ω·cm by mixing carbon as a conductive agent.

The volume resistivity of the intermediate transfer belt 8 is preferably in the range of 1×10E9 to 10E11 Ω·cm from the viewpoint of transferability. If the volume resistivity is lower than 1×10E9 Ω·cm, a transfer current may escape in a high temperature and high humidity environment, resulting in transfer failure. On the other hand, if the volume resistivity is higher than 1×10E11 Ω·cm, a transfer failure may occur due to abnormal discharge in a low-temperature, low-humidity environment.

Here, the volume resistivity of the intermediate transfer belt 8 is determined by the following measuring method. That is, using Mitsubishi Chemical Corporation's Hiresta-UP (MCP-HT450), the measurement probe was UR, the indoor temperature at the time of measurement was set to 23 ° C., the indoor humidity was set to 50%, the applied voltage was 250 V, and the measurement time was 10 seconds. Measurement is carried out under the following conditions.

Although polyimide resin is used as the material for the intermediate transfer belt 8 in this embodiment, the material for the intermediate transfer belt 8 is not limited to this. For example, as long as it is a thermoplastic resin, other materials such as the following may be used. For example, materials such as polyester, polycarbonate, polyarylate, acrylonitrile-butadiene-styrene copolymer (ABS), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVdF), polyethylene naphthalate (PEN), and mixed resins thereof. .

Further, although an electronically conductive intermediate transfer belt using carbon as a conductive agent is used here, an ion conductive conductive agent may be used as the conductive agent, for example. Examples of the ionic conductive agent include polyvalent metal salts and quaternary ammonium salts. Quaternary ammonium salts include tetraethylammonium ion, tetrapropylammonium ion, tetraisopropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, etc. as the cation part, and as the anion part, Examples include halogen ions, fluoroalkyl sulfate ions, fluoroalkyl sulfite ions, and fluoroalkyl borate ions whose fluoroalkyl group has 1 to 10 carbon atoms.

Further, it is also possible to adopt a structure in which a polyether ester amide resin is mainly used, and potassium perfluorobutane sulfonate or the like is added thereto in combination.

In this embodiment, the primary transfer roller 5 is made of a nickel-plated steel rod with an outer diameter of 6 mm as a core metal, and an NBR layer with a volume resistivity adjusted to about 1×10E5 to 1×10E7 Ω·cm as an elastic layer. An elastic roller having an outer diameter of 12 mm and covered with a foamed sponge body having a thickness of 3 mm and containing epichlorohydrin rubber as a main component was used. The primary transfer roller 5 is brought into contact with the photosensitive drum 1 via the intermediate transfer belt 8 with a pressing force of 9.8 N, and rotates as the intermediate transfer belt 8 rotates. Further, when the toner on the photosensitive drum 1 is being primarily transferred to the intermediate transfer belt 8, a DC voltage (primary transfer voltage) of about 1000 to 2000 V is applied to the primary transfer roller 5.

The secondary transfer roller 11 is mainly made of a nickel-plated steel rod with an outer diameter of 8 mm as a core metal, and NBR and epichlorohydrin rubber with a volume resistivity adjusted to 1×10E7 to 1×10E8 Ω・cm as an elastic layer. An elastic roller with an outer diameter of 16 mm and covered with a foamed sponge material with a thickness of 4 mm was used.

The secondary transfer roller 11 is brought into contact with the intermediate transfer belt 8 with a pressing force of 50 N, and rotates as the intermediate transfer belt 8 rotates. Further, when the toner on the intermediate transfer belt 8 is secondarily transferred to the transfer material S such as paper, a DC voltage (secondary transfer voltage) of about 1000 to 5000 V is applied to the secondary transfer roller 11.

These values should be set optimally depending on the belt material, roller material, device configuration, etc., and are not limited to these configurations and values.

3. Image Forming Process of Image Forming Apparatus The image forming process of the image forming apparatus of the present invention will be described below. During image formation, the outer peripheral surface of the rotating photosensitive drum 1 is charged with a predetermined polarity (negative polarity in this embodiment) by a primary charging roller 2 to which a primary charging voltage of a predetermined polarity (negative polarity in this embodiment) is applied. is charged to a predetermined potential of Thereafter, the charged surface of the photosensitive drum 1 is exposed to light by the laser unit 3 based on the image signal. As a result, an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 1.

This electrostatic latent image is developed (visualized) as a toner image by the developing device 4 using toner as a developer. At this time, a developing voltage of a predetermined polarity (negative polarity in this embodiment) is applied to the developing roller 41. In this embodiment, a toner image is formed on the photosensitive drum 1 by image exposure and reversal development. That is, by attaching toner charged to the same polarity as the charging polarity of the photosensitive drum 1 to the exposed portion of the photosensitive drum 1 whose absolute value has decreased due to exposure after being uniformly charged, A toner image is formed. Note that in this embodiment, the toner used for development is negatively charged. That is, the charge polarity (regular charge polarity) of the toner during development is negative.

The toner image formed on the photosensitive drum 1 rotating as described above is transferred onto the intermediate transfer belt 8 that is in contact with the photosensitive drum 1 and rotating at approximately the same speed as the photosensitive drum 1 in the primary transfer portion N1. (primary transfer). At this time, a primary transfer voltage power source (high voltage power source) 51 as a primary transfer voltage applying means is applied to the primary transfer roller 5 with a polarity opposite to that of the toner during development (positive polarity in this embodiment). A primary transfer voltage of is applied.

This primary transfer voltage has a target current value set in advance so as to obtain optimal image formation, and the target current value is set before the toner image formed on the photosensitive drum 1 reaches the primary transfer section N1. The transfer voltage is controlled by the high voltage control means so that In a series of image forming processes, the period from when the photosensitive drum starts rotating until just before the toner image on the photosensitive drum reaches the transfer section and transfer of the toner image onto the intermediate transfer belt is started. Defined as pre-rotation in primary transfer. Further, the transfer voltage control performed at this time is called ATVC (Auto Transfer Voltage Control).

When a full-color image is formed, the toner images formed on the photosensitive drums 1Y, 1M, 1C, and 1K of the first, second, third, and fourth image forming units PY, PM, PC, and PK are The images are transferred onto the intermediate transfer belt 8 in such a way that they are successively overlapped. Then, the four-color toner images are conveyed to the secondary transfer portion N2 by rotation of the intermediate transfer belt 8 in an overlapping state.

On the other hand, a transfer material S such as recording paper sent out from the feeding/conveying device 12 is conveyed to the secondary transfer section N2 by a pair of registration rollers 16. The feeding and conveying device 12 includes a paper feeding and conveying roller 14 that feeds out the transfer material S from within a cassette 13 that stores the transfer material S, and a pair of conveying rollers 15 that conveys the transferred transfer material S. The transfer material S conveyed from the feeding conveyance device 12 is conveyed to the secondary transfer portion N2 by a pair of registration rollers 16 in synchronization with the toner image on the intermediate transfer belt 8.

The toner image on the intermediate transfer belt 8 is transferred (secondary transfer) onto the transfer material S that is conveyed while being sandwiched between the intermediate transfer belt 8 and the secondary transfer roller 11 in the secondary transfer portion N2. . At this time, a secondary transfer voltage power source (high voltage power source) 53 as a means for applying a secondary transfer voltage is applied to the secondary transfer roller 11 with a polarity opposite to that of the toner during development (in this embodiment, a positive polarity). ) is applied.

Similar to the primary transfer voltage control, this secondary transfer voltage also has a target current value set in advance so as to obtain optimal image formation. In addition, in a series of image forming operation processes, the period from when the photosensitive drum starts rotating until the toner image reaches the secondary transfer portion N2 and immediately before the transfer of the toner image onto the transfer material is started. , is defined as the pre-rotation in secondary transfer. By performing transfer voltage control (ATVC) in the secondary transfer section during pre-rotation in the secondary transfer, the transfer voltage is controlled by the high voltage control means so that the target current is achieved during image formation.

The transfer material S onto which the toner image has been transferred is conveyed to a fixing device 17 as a fixing means. The transfer material S is conveyed while being sandwiched between a fixing film 18 and a pressure roller 19 included in the fixing device 17, and is heated and pressurized to fix the toner image on its surface. The transfer material S with the toner image fixed thereon is discharged to the outside of the apparatus main body 110 by a pair of discharge rollers 20 .

Note that toner remaining on the surface of the photosensitive drum 1 after the primary transfer process (primary transfer residual toner) is cleaned by a drum cleaner 6. That is, the primary transfer residual toner is scraped off from the rotating photosensitive drum 1 by the drum cleaning blade 61 disposed in contact with the photosensitive drum 1 and collected in the waste toner container 62 .

4. Lifespan Detection Means Next, the lifespan detection means used in this embodiment will be explained. Here, the secondary transfer roller 11 will be explained as an example of a replaceable member.

During the above-described secondary transfer image formation, the control means calculates the resistance value of the secondary transfer roller 11 from the voltage value of the high voltage control means and the value of the detected current obtained by the current detection means. The lifespan of the secondary transfer roller 11 is determined by detecting fluctuations in the calculated resistance value. Specifically, the control means detects the current at each timing that applies to a predetermined condition, calculates the resistance value, and stores it in the data storage means (memory) in the image forming apparatus, thereby calculating the resistance value for the number of prints. Detect changes over time.

In this embodiment, the timing that satisfies the predetermined conditions is the timing when the operation is stopped for 8 hours or more after the job ends and the secondary transfer roller 11 is in a cold state (so-called "first thing in the morning" timing). The current detection means may be, for example, the ammeter 58, and the ammeter 58 and the control means for controlling it may be regarded as the current detection means.

FIG. 2 shows the variation in resistance value of the secondary transfer roller 11 according to the number of durable sheets (number of sheets printed). The secondary transfer roller 11 used in this embodiment has a characteristic that the resistance value of the member increases due to deterioration caused by long-term energization due to durability. In this embodiment, the upper limit resistance value of the secondary transfer roller 11 is set in order to guarantee the quality of the image. The control means compares the calculated resistance value with the upper limit resistance value, and determines that the secondary transfer roller 11 has reached the end of its life when the upper limit resistance value is reached.

In this example, as shown in FIG. 2, the remaining life of a new resistor whose resistance value is the initial resistance value is set to 1.
00%, and the remaining life at the upper limit resistance when the resistance value is the upper limit resistance value is set to 0%. The control means calculates the remaining life in percentage by calculating the ratio between the upper limit resistance value and the initial resistance value at the current resistance value position. Then, the user is notified of the lifespan on a screen or the like. Note that the method of notifying the lifespan is not limited to this, and for example, a configuration may be adopted in which only a warning is notified when the lifespan has been reached.

In this embodiment, the actual resistance value is detected when performing the transfer voltage control (ATVC) during pre-rotation in the secondary transfer described above. The control means calculates the resistance value R from the voltage V applied during the pre-rotation and the current I detected by the current detection means (Equation 1 below).
R=V/I...(1)

It is also preferable to obtain a correction formula by calculating in advance the relationship between environmental information such as temperature/humidity and absolute moisture content and the resistance value, and then perform environmental correction on the resistance value. Alternatively, the relationship between environmental information and resistance values may be obtained in advance as a resistance value correction table and used for correction. This correction formula and table differ depending on the material of the secondary transfer roller, device configuration, process speed, etc.

5. Replacement Detection Means Next, the exchange detection means used in this embodiment will be explained. In this embodiment, the control means simultaneously calculates the slope of the current-voltage characteristic curve when performing transfer voltage control (ATVC) during image formation. Then, by detecting the fluctuation in the calculated inclination, the replacement state of the secondary transfer roller is determined. Although the control means here functions as a replacement detection means, a dedicated replacement detection means may be provided. There is no particular restriction on the timing of image formation to detect the tilt, and it may be performed every time, every predetermined number of prints, or every predetermined time.

The slope related to current-voltage characteristics will hereinafter be referred to as "slope." Note that terms such as "larger/smaller" and "increases/decreases" regarding the slope are used when the horizontal axis is the voltage and the vertical axis is the current, as in the graph of this embodiment. When the slope is "large/small", it means that the amount of increase in current relative to the amount of increase in voltage in the same section is "large/small". In addition, for parts such as rollers, the slope of the current-voltage characteristic curve is sometimes described as "large/small", but this magnitude is not an absolute value, but rather a comparison of parts with different durability conditions and initial characteristics. It is a relative matter of time. The inclination is determined by the first current detected when the first voltage is applied to the secondary transfer roller 11 and the second current detected when the second voltage is applied to the secondary transfer roller 11. It can be said that this value corresponds to the current-voltage characteristics of the secondary transfer roller, which is calculated based on the current and .

FIG. 3 is a graph showing the slopes of the above-mentioned current-voltage characteristic curves for new and durable transfer rollers, with the horizontal axis representing voltage and the vertical axis representing current. The solid line in FIG. 3 shows the slope in a new state, and the broken line shows the slope in a durable product. In this embodiment, the slope K is defined as follows, and is calculated from the detected currents I1 and I2 when two preset levels of voltages V1 and V2 are applied (Equation 2 below).
K=(I2-I1)/(V2-V1)...(2)

As can be seen from FIG. 3, the slope changes greatly between new and durable products, and the slope of durable products tends to be smaller than that of new products.

FIG. 4 is a graph showing the relationship between the slope K and the number of prints. In this way, it can be seen that the slope K decreases (becomes smaller) as the number of prints increases. In other words, as the number of prints increases from the new state, the amount of increase in the detection current relative to the amount of increase in the applied voltage becomes smaller.

FIG. 5 is a diagram showing the inclinations of the secondary transfer roller 11 having different initial resistance values. Generally, when manufacturing parts, there is a manufacturing tolerance as an allowable range of individual differences. The resistance value of the secondary transfer roller 11 used in this embodiment also has a manufacturing tolerance defined by an upper limit value and a lower limit value. In FIG. 5, the secondary transfer roller 11 (upper limit resistance product) whose initial resistance value is the upper limit value in the manufacturing tolerance range, the secondary transfer roller 11 (center resistance product) whose initial resistance value is the center value, and the secondary transfer roller 11 whose initial resistance value is the lower limit value. It shows the inclinations of the three secondary transfer rollers 11, roller 11 (lower limit resistance product). From this, it can be seen that when the initial resistance values are different, the slopes are also different, and that the slope becomes smaller as the initial resistance value at the time of manufacturing becomes higher.

Here, an example of calculating the slope K in the case of a center resistance product will be shown. In this embodiment, two levels of voltages V1 and V2 are set as follows. The timing of applying each of V1 and V2 within the ATVC period is not particularly limited as long as measurement is possible, and there is no limitation on the sequential relationship between V1 and V2.
V1=1000V
V2=2000V

The detection currents I1 and I2 detected for each voltage were as follows.
I1=45μA
I2=98μA

Therefore, from equation (2), the initial value of the slope of the center resistance product was K=0.053. Similarly, the initial value of the slope of the upper limit resistance product was K=0.040. Further, the initial value of the slope of the lower limit resistance product was K=0.085. From the above, it has been found that within the manufacturing tolerance range of the resistance value of the transfer roller, the possible tolerance range of the initial value of the slope K is 0.040 to 0.085.

FIG. 6 is a diagram illustrating changes in the inclination K of the secondary transfer roller 11 due to durability (increase in the number of prints) and changes when the roller is replaced after reaching its lifespan.

The initial value of the slope K in the case of a new product has the above-mentioned tolerance range (0.040 to 0.085) (initial K value range). Then, as the number of prints increases, the slope K gradually decreases due to durability. The solid line shows the durability variation of the slope K in the case of the resistance value upper limit product, and the broken line shows the durability variation in the slope K in the case of the resistance value lower limit product. In this example, the range of the slope K after durability (K value range after durability) was 0.015 to 0.030.

Then, when the secondary transfer roller 11 is replaced after reaching its lifespan, the inclination K changes significantly. After replacing with a new one, K returns to the initial value from the once lowered value. The control means of this embodiment determines that the transfer roller has been replaced by detecting this change in inclination.

The solid line A and the broken line B in FIG. 6 indicate the slope K after replacement, and the solid line A indicates the case where the transfer roller is replaced with the one with the upper resistance limit, and the broken line B shows the case where the transfer roller is replaced with the one with the lower resistance limit product. It shows the case. Note that from now on, the amount of change in K, which is the amount of change from the first slope value calculated at the first timing to the second slope value calculated at the second timing, will be referred to as ΔK. .

Here, the combination in which the amount of change in K when the transfer roller is replaced is the smallest is when the transfer roller resistance lower limit product is replaced with the transfer roller resistance upper limit product B. In this case, the amount of change in K changes from K=0.030 after durability of the transfer roller resistance lower limit product to K=0.040, which is the initial value of the transfer roller resistance upper limit product B. In other words, the upper limit (0.030) of the range of slope values (0.015 to 0.030) that can be taken when the secondary transfer roller 11 reaches the end of its life, and when the secondary transfer roller 11 is new. It is considered that the difference between the lower limit value (0.040) of the range of possible slope values (0.040 to 0.085) and the minimum value of the amount of change ΔK.

Therefore, in this embodiment, it is determined that the transfer roller has been replaced when the amount of change ΔK≧0.010 is detected. The amount of change ΔK=0.010 is the first threshold value. When the amount of change in inclination is equal to or greater than the first threshold value, it is determined that the secondary transfer roller 11 has been replaced. On the other hand, when the amount of change in inclination is less than the first threshold value, it is not determined that the secondary transfer roller 11 has been replaced.

In this way, in this embodiment, it is possible to determine whether the roller has been replaced by determining whether the amount of change in the inclination K is greater than or equal to a predetermined value, and when replacement is detected, the life count is automatically counted. Reset is possible. Note that various values used for control, such as the set value of the applied voltage and the predetermined value of the amount of change in the slope K, may be determined as appropriate depending on the characteristics of the member, the environment of the apparatus, and the like. Values, formulas, tables, etc. used for control may be calculated based on measurement results performed in advance and stored in a memory included in the control board 25.

[Example 2]
Example 2 will be explained. When replacing the roller, the transfer roller may not be replaced with a new roller, but with another transfer roller that has a history of use. Even in this case, depending on the operating state of the device before replacement and the state of the transfer roller at the time of detection, there is a possibility that the amount of change ΔK≧0.010 will be detected. In that case, even if replacement of the transfer roller can be detected, it is difficult to accurately determine whether the transfer roller has been replaced with a new one. In this case, there is a risk that the lifespan of the replaced member will not be counted appropriately.

Therefore, in this embodiment, a threshold value for detecting a new product is set in advance at the same time as detecting replacement. In this example, as mentioned earlier, K at the transfer roller resistance upper limit roller resistance, where the initial value of K is the smallest, was K = 0.040. The threshold value was set as K≧0.035 (new product detection threshold value in FIG. 6).

That is, in this embodiment, the control means not only compares the change amount ΔK with the threshold value but also compares the K value itself with the threshold value at each detection timing. If ΔK≧0.010 and K≧0.035 are detected at a certain detection timing, it is determined that the roller has been replaced with a new one, and the life counter is reset. That is, the new product detection threshold is the second threshold. If K is greater than or equal to the second threshold, it is determined that the secondary transfer roller 11 has been replaced with a new one.

On the other hand, if the transfer roller is replaced with a previously used transfer roller other than a new roller, ΔK≧0.010 is detected and it is determined that the transfer roller has been replaced, but K≧0.035 is not satisfied. , it cannot be determined that the product has been replaced with a new one. That is, if K is less than the second threshold value, it is not clear whether or not the product has been replaced with a new product.

Note that even if the roller is replaced with a new one, the replacement may be delayed depending on various circumstances (for example, the usage environment and usage history of the image forming apparatus at the time of replacement, the storage condition of the new transfer roller for replacement, etc.) There is a possibility that the slope will be less than the new product detection threshold (that is, K≧0.035 will not be satisfied) when the slope is acquired immediately after. In that case, it is not possible to accurately determine whether to replace it with a new product.

Therefore, if it is detected that the roller has been replaced but it is unclear whether it has been correctly replaced with a new one (in this example, when ΔK≧0.010 and K<0.035 are detected), The user may be notified via the operation panel to prompt the user to perform the operation. In the notification, for example, it is possible to request the user to reset the lifespan count if the battery has been correctly replaced with a new one.

As described above, according to this embodiment, the problem of resetting the life count even though the transfer roller is replaced with a transfer roller that is not new and has a history of use, and the problem of the counter being reset even though the transfer roller is replaced with a new one can be solved. This makes it possible to avoid the problem of not being able to reset and correctly detecting the lifespan after replacement.

The flow of this embodiment will be explained using FIG. 7. This flow starts at a predetermined timing during image formation. First, the control means calculates the slope K based on the applied voltage and the detected current (step S101). Next, the control means calculates the amount of change in the slope K, ΔK, and determines whether ΔK≧0.010 (step S102).

When the control means detects ΔK<0.010 (S102=No), the control means determines that the roller has not been replaced, and ends the replacement detection. On the other hand, if ΔK≧0.010 is detected (S102=Yes), the process advances to step S103. Subsequently, the control means determines whether K≧0.035 (step S103). When the control means detects K≧0.035 (S103=Yes), it determines that the product has been replaced with a new one, stops the life warning, resets the life count, and ends the replacement detection (step S104).

On the other hand, if K<0.035 is detected in step S103 (S103=No), the control means notifies the user (step S105). In the notification, the user is prompted to input either Yes or No via the operation panel as to whether or not the roller has been replaced with a new roller. If Yes, the control means stops the life warning, resets the life count, and ends the replacement detection (step S104). In the case of No, the control means ends the replacement detection without taking any action. In this case, the lifespan warning remains notified and the lifespan count continues.

The tolerance range of the initial value of the inclination K, the replacement judgment value, and the new detection threshold that have been explained above are values that are determined in advance depending on the prescription of the secondary transfer roller and the device configuration, and if the prescription and device configuration differ, Since this value is calculated and set anew in each case, it can be set each time in each situation.

Here, an example has been described in which the slope K regarding the current-voltage characteristic curve is calculated when performing ATVC during the pre-rotation, but the calculation of the slope K may be performed individually at another timing. For example, if it is performed separately from the ATVC, the detection time can be set longer than the ATVC, and the slope K can be calculated with higher accuracy. This makes it possible to use the averaged detection results even in a situation where periodic unevenness occurs in the detection current in the second half of the durability test.

Further, the calculation may be performed at a predetermined timing by aligning the usage environment and operating conditions, and in this case as well, measurement variations can be suppressed and calculation can be performed with higher accuracy.

Although the secondary transfer roller 11 has been described above as a replaceable member, the scope of the present invention is not limited to this. For example, the present invention may be applied to various roller members such as a primary transfer roller or a transfer roller in a monochrome machine. When applied to the primary transfer roller, it can also be used to detect replacement of an intermediate transfer unit that is a replaceable unit that includes the primary transfer roller.

[Example 3]
In this embodiment, a method will be described in which the replacement detection means determines whether to replace the transfer roller by detecting a change in the overshoot amount of the detection current when high voltage is applied at the start of image formation.

As described above, the transfer roller used in this embodiment has a characteristic that the resistance value of the member increases due to deterioration caused by long-term energization due to durability. Deterioration due to energization is, for example, when high pressure is applied, the surface of the roller may deteriorate due to oxidation due to discharge, etc. that occurs between the transfer roller and the opposing member (in this case, between the transfer roller and the opposing roller via the belt). This is a phenomenon that causes Due to such deterioration, the resistance near the surface of the rubber layer, which is the conductive layer of the transfer roller, gradually increases, and as a result, the overall resistance of the transfer roller increases, and the detection resistance itself during ATVC increases. .

Hereinafter, a description will be given of the rise of the detection current when a high voltage is applied to a transfer roller whose resistance value has increased due to deterioration caused by electricity supply due to durability and a transfer roller in a new state. FIGS. 8A and 8B are diagrams showing the waveforms of high voltage application and detection current at the start of image formation in the case of a new roller and a roller after durability use, respectively. The horizontal axis indicates time. In the graph, the straight thick solid line is the applied voltage, and the wavy thin solid line is the detected current. The vertical axis schematically shows voltage and current values. The transfer rollers used here were compared in the case where both the new roller and the roller after durability test had almost the same detection resistance value during ATVC.

As can be seen from this figure, even if the detection resistance during ATVC is almost the same, the new roller and the roller after durability test have different current rise characteristics when high voltage is applied. That is, the new roller shown in FIG. 8(a) exhibits the current rise characteristics with respect to voltage application in the case of a single-layer roller in which the resistance in the thickness direction of the roller conductive layer is uniform. On the other hand, the roller after durability testing shown in FIG. 8(b) exhibits the current rise characteristics of a so-called two-layer roller having a high resistance layer on the surface layer. Specifically, a new roller exhibits so-called overshoot, in which a large current flows immediately after voltage application. On the other hand, the time constant of the roller after durability increases due to the effect of the high resistance layer on the surface layer, the responsiveness of the current start-up characteristic to voltage application decreases, and the amount of overshoot at start-up decreases.

Here, the overshoot amount ΔI of the current at startup is calculated by the following equation (3) from the maximum current I_MAX and the average current I_AVE during a preset constant voltage application period from the constant voltage application timing during ATVC. Calculated.
ΔI = I_MAX−I_AVE…(3)

In this example, the constant voltage application period when performing ATVC during pre-rotation was set to 300 msec. Then, each period was set as follows. Note that the average current can be calculated, for example, by a method of calculating the arithmetic mean of current values acquired at a plurality of timings during the average current acquisition period. Further, it is sufficient if a representative value of the current during a period without overshoot can be obtained. For example, a median value may be used instead of an average value.
・Maximum current acquisition period (first predetermined period): Constant voltage application timing ~ 100 msec after constant voltage application timing (period of 100 msec)
・Average current acquisition period (second predetermined period): 100 msec after constant voltage application timing to 300 msec after constant voltage application timing (200 msec period)

In this example, the start-up applied voltage at the time of overshoot detection was set to 1 kV under a test environment of 23° C./50%. Each current value in this case was as follows.
I_MAX=34.50μA, I_AVE=22.18μA when new
Therefore, ΔI when new = 12.32μA
After durability I_MAX=22.43μA, I_AVE=21.23μA
Therefore, ΔI after durability = 1.20μA

FIG. 9 is a diagram showing the durability transition of ΔI and the fluctuation of ΔI after replacement. In the figure, the solid line shows the variation in the case of a product with a lower resistance limit of manufacturing tolerance, and the broken line shows the variation in the case of a product with the upper limit of resistance limit in manufacturing tolerance. As can be seen here, in the initial state, ΔI shows a value in a predetermined range (initial value range), ΔI gradually decreases with durability, and in the latter half of durability, ΔI is almost 0 (no overshoot).

When the roller is replaced in such a state, ΔI changes greatly from a state of almost zero. Therefore, in this embodiment, by detecting this change, it is determined whether the roller has been replaced. That is, the first difference calculated at the first timing (the difference between I_MAX and I_AVE at the first timing) and the second difference calculated at the second timing (the difference between I_MAX and I_AVE at the second timing). The amount of change (difference) is compared with a third threshold.

In this embodiment, a threshold value ΔI_TH (third threshold value) for determining whether a new product is detected is set in advance. Here, ΔI is calculated in advance when ΔI is the smallest, that is, when the tolerance of the resistance value at the time of manufacturing is at the standard upper limit, and ΔI_TH is set. Here, when the resistance value upper limit is new, ΔI is as follows, assuming that the start-up applied voltage at the time of overshoot detection is 1 kV.
I_MAX=27.50μA, I_AVE=21.20μA when new
Therefore, ΔI when new = 6.30μA

Therefore, in this embodiment, taking the detection error into account, ΔI_TH was set to 4.0 μA. That is, when ΔI≧4.0 μA is detected (when it is greater than or equal to the third threshold value), it is determined that the roller has been replaced with a new roller, and the life counter is reset.

Note that even if the transfer roller is replaced with a new one, depending on various circumstances (for example, the usage environment and usage history of the image forming apparatus at the time of replacement, and the storage condition of the new replacement transfer roller), There is a possibility that the overshoot amount ΔI immediately after replacement becomes less than the threshold value ΔI_TH (less than the third threshold value) for new product detection judgment. Therefore, it is also preferable to set ΔI_TH2 as an auxiliary threshold (fourth threshold) for detecting a new product.

In other words, even if ΔI≧4.0μA is not satisfied, if a certain amount of change is detected, it is possible to detect that the roller itself has been replaced, although it is unclear whether the roller has been replaced with a new one. . Specifically, as shown in FIG. 8, the fluctuation range obtained by subtracting the minimum value from the maximum value in the average current acquisition section is defined as I_VAR. When detecting roller replacement after the end of its life, if the relationship between ΔI and the fluctuation range I_VAR at the time of current detection is ΔI > I_VAR/2 (if it is greater than or equal to the fourth threshold), at least the roller is It is possible to determine that it may have been exchanged. In this example, I_VAR/2=1.15 μA. Therefore, taking into account the detection error, ΔI_TH2=2.0 μA was set as the threshold for determining replacement.

As described above, in this embodiment, although replacement of the transfer roller is detected, if it is not possible to detect a value equal to or higher than the threshold value for new product detection judgment, ΔI_TH2≦ΔI≦ΔI_TH, that is, 2.0 μA≦ΔI<4.0 μA is detected. In this case, instead of automatically resetting the life counter, a notification is displayed on the operation panel to the user, requesting the user to perform an operation to determine whether or not the roller has been replaced with a new one. This makes it possible to correctly reset the life count even if, for example, the overshoot amount ΔI immediately after replacement becomes less than the threshold value ΔI_TH for new product detection judgment even though the roller has been replaced with a new one.

The flow will be explained using FIG. 10. This flow starts at a predetermined timing during image formation. First, ΔI is calculated (step S201). Next, it is determined whether ΔI≧4.0 μA (step S202).

When the control means detects ΔI≧4 μA (S202=Yes), the control means determines that the roller has been replaced, stops the life warning, resets the life count, and ends the replacement detection (step S203). On the other hand, if ΔI<4μA is detected in step S202 (S202=No), the control means determines whether 2μA≦ΔI<4μA (step S204).

If ΔI<2μA (S204=No), the control means determines that the roller has not been replaced and ends the process. On the other hand, if 2 μA≦ΔI (S204=Yes), the control means notifies the user (step S205). In the notification, the user is prompted to input either Yes or No via the operation panel as to whether or not the roller has been replaced with a new roller.

If the user operation in step S205 is "replaced (Yes)," the life warning is stopped, the life count is reset, and replacement detection is ended (step S203). On the other hand, if the user operation in step S205 is "not replaced (No)", the replacement detection ends without taking any action. In this case, the lifespan warning remains notified and the lifespan count continues.

According to the above flow, replacement of the transfer roller can be detected. Furthermore, there are problems where the life count is reset even though the transfer roller is replaced with a used one that is not new, and the counter cannot be reset even though it is replaced with a new one, and the lifespan after replacement is This makes it possible to avoid the problem of not being able to detect images correctly.

Since ΔI_TH and ΔI_TH2 used here change depending on the device configuration, roller prescription, resistance value, voltage application conditions, measurement conditions, timing of data acquisition, etc., they may be set each time. Furthermore, the correction may be performed by measuring environmental information in the measurement environment such as temperature and humidity, and calculating a formula for the relationship between the environment and ΔI in advance and applying it, or by creating a correction table.

In this embodiment, an example has been described in which the acquisition period of the maximum current I_MAX and the average current I_AVE is divided into a preset maximum current acquisition period and an average current acquisition section. However, in order to simplify control, the maximum current I_MAX and the average current I_A are
You may also obtain VE.

As described above, according to the present invention, it is possible to determine whether a member has been replaced even if the image forming apparatus does not have a member replacement detection mechanism. As a result, when it is determined that a member has been replaced, the life count can be automatically reset without the user performing a reset operation.

[Example 4]
In Examples 1 and 2, the slope of the current-voltage characteristics of the transfer roller was obtained to determine whether the transfer roller was replaced with a new one. In Example 4 below, a method for further improving the accuracy of judgment will be described.

As mentioned earlier, in the transfer roller used in this example, the surface of the roller undergoes oxidative deterioration due to energization, and the resistance near the surface layer of the rubber layer, which is the conductive layer of the transfer roller, gradually increases. . Therefore, the current-voltage characteristics of the transfer roller after durability behave like a so-called two-layer roller having a high resistance layer on the surface layer.

That is, since the transfer roller after durability has a high surface layer resistance, the voltage value at which current begins to flow is higher than that of a transfer roller that has high resistance from the beginning due to manufacturing tolerances. Even if the usage environments of the two are different when ATVC is executed and the slopes of the current-voltage characteristics are similar, it is possible to distinguish between the two based on the characteristics of the current-voltage characteristics.

FIG. 11 is a graph showing current-voltage characteristic curves regarding three transfer rollers, where the horizontal axis shows voltage and the vertical axis shows current. The solid line shows the profile of current-voltage characteristics after durability of the product with a high resistance, and the broken line shows the profile of the minimum resistance product after durability. On the other hand, the thick line shows the profile of the new product with the upper resistance limit, but it shows the results when ATVC was performed in an environment with lower humidity than other rollers. This assumes that the humidity changes before and after replacing the transfer roller.

If the transfer roller with the upper limit of resistance is in a low humidity environment, the resistance will be high and the current value will be low even when the same voltage is applied. Therefore, the slope becomes similar to the profile of the current-voltage characteristic after durability of the transfer roller at the lower limit of resistance, and it may be difficult to distinguish between them.

Therefore, the difference in current-voltage characteristic profiles between a new transfer roller and a roller after durability use is utilized. As mentioned above, in the profile of the transfer roller of the new high-resistance product, the slope of the current value with respect to the voltage does not differ that much between the low voltage side and the high voltage side. On the other hand, the two transfer rollers after durability have a larger slope on the high voltage side than on the low voltage side, and have a different profile from the new state.

Here, a method for distinguishing between a new transfer roller and a used transfer roller by comparing the slope on the low voltage side and the slope on the high voltage side will be described.

First, a voltage V3 on the low voltage side and a detection current I3 when voltage V3 is applied are newly defined. In this embodiment, V3 was set as follows.
V3=500V

Next, two types of slopes K1 and K2 are defined as follows based on V1 and V2 set in the first embodiment and V3 newly set. This slope K2 is the same as K defined in the first embodiment.
K1=(V1-V3)/(I1-I3)...(4)
K2=(V2-V1)/(I2-I1)...(5)

Further, in order to determine whether a new transfer roller or a used transfer roller has been used, the ratio a obtained from the inclination K1 and the inclination K2 is defined as follows.
a=K2/K1...(6)

Finally, the usage status of the transfer roller is determined by comparing the value of a with a threshold value for determining whether the transfer roller is new. If the value of a is greater than or equal to a certain threshold, it is determined that the product has been used for durability, and if the value of a is less than or equal to another threshold, it is determined that the product is new.

Specifically, Table 1 shows the values of inclinations K1 and K2 obtained from the current-voltage characteristic profile of FIG. 11 and the value of a obtained from the two inclinations for the three transfer rollers.

FIG. 12 is a graph showing the relationship between two types of slopes of the current-voltage characteristic curve of the transfer roller, where the horizontal axis shows the value of K1 and the vertical axis shows the value of K2. In FIG. 12, the values of K1 and K2 of the three transfer rollers are plotted. The solid line points show the resistance center roller after durability, the broken line points show the resistance lower limit roller after durability, and the thick line points show the initial resistance upper limit roller in a low humidity environment.

The transfer roller after durability has a relatively large value of K2 relative to the value of K1, and is plotted in the upper left area. On the other hand, for a new transfer roller, the value of K2 is relatively small compared to the value of K1, and is plotted in the lower right area.

Here, FIG. 12 shows the relationship between K1 and K2 when the value of a, which is the ratio of K1 and K2, is 1.3 and 1.5, respectively. Both of the two rollers after durability testing had a value larger than a=1.5, and the new roller had a value smaller than 1.3. Therefore, the post-endurance threshold for determining that the transfer roller is a durable one is set to 1.5, and the new threshold for determining that the transfer roller is a new one is set to 1.3. By comparing these two threshold values, it is determined whether the transfer roller is new or has undergone durability testing.

By determining whether the transfer roller is new as described above, it can be used to detect replacement of the transfer roller. That is, in this embodiment, the control means calculates the a value at each detection timing, and determines that "the previously calculated a value (a0) is greater than or equal to the post-endurance threshold" and that "the currently calculated a value (a1) is greater than or equal to the post-endurance threshold". If the value is "below the new product threshold", it is determined that the transfer roller after durability has been replaced with a new transfer roller, and the life counter is automatically reset.

Here, the effects of this embodiment will be described. There are multiple methods for replacing a high-resistance product after durability with a new upper-resistance product (low-humidity condition), and when replacing a low-resistance product after durability with a new upper-resistance product (low-humidity condition). The results are shown when a replacement decision is made.

In the method of this embodiment, it is determined whether the transfer roller is a new transfer roller or a transfer roller that has been used for durability, depending on the ratio of the slope on the low voltage side to the slope on the high voltage side, and the transfer roller is replaced based on the result. Decide whether or not it was successful. The results of the replacement determination in this manner are shown in Table 2 below.

As shown in the results in Table 2, in each case in this example, after the roller before replacement was used for durability, the roller after replacement was determined to be new, and the replacement could be determined. That is, according to the configuration of this embodiment, even if the temperature and humidity before and after replacement are different, it is possible to accurately determine that the replacement has been performed.

As described above, in this embodiment, by comparing the a value obtained from two or more levels of inclination with the threshold value, it is possible to determine whether the transfer roller is new or has undergone durability. By comparing this determination result with the previous determination result, it is possible to determine whether the transfer roller has been replaced with a new one. Note that various values and settings used for control, such as the set value of the applied voltage and the method of calculating the a value, may be determined as appropriate depending on the characteristics of the member, the environment of the apparatus, and the like. Values, formulas, tables, etc. used for control may be calculated based on measurement results performed in advance and stored in a memory included in the control board 25.

In this example, three voltage values from V1 to V3 were set for determining the slope, and two slopes related to the current-voltage characteristics were determined. The method for determining the slope is not limited to this, and four or more voltage values may be set, and two or more slopes may be determined based on the results and used for determination.

In addition, in this example, the judgment of old and new and the judgment of replacement were made based on the index value calculated from the result of one measurement, but the index value was calculated by statistically processing multiple measurements. It may be calculated and determined.

In addition, in this embodiment, two types of threshold values are set for comparison with the a value obtained from two or more levels of inclination, and the rollers are determined to be new or used, respectively. The threshold value is not limited to this, and only one threshold value may be set. For example, if the threshold was exceeded in the previous measurement and the threshold was not exceeded in the current measurement, it may be determined that the transfer roller has been replaced.

As described above, according to the present invention, even if an image forming apparatus does not have a member replacement detection mechanism, it is possible to determine whether or not a member has been replaced by using changes in the profile of current-voltage characteristics due to deterioration caused by energization. becomes possible. As a result, when it is determined that a member has been replaced, the life count can be automatically reset without the user performing a reset operation.

[Configuration 1]
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on a first current detected when a first voltage is applied to the roller member and a second current detected when a second voltage is applied to the roller member, Calculating the value of the slope of the current-voltage characteristic of the roller member,
The roller member is adjusted based on the amount of change from the first slope value calculated at the first timing to the second slope value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced.
[Configuration 2]
The control means may determine that the roller member has been replaced when the amount of change from the first slope value to the second slope value is greater than or equal to a first threshold value. The image forming apparatus according to configuration 1.
[Configuration 3]
The first threshold value of the amount of change is an upper limit value of the range of values of the slope that can be taken when the roller member reaches the end of its life, and a range of values of the slope that can be taken when the roller member is new. The image forming apparatus according to configuration 2, wherein the image forming apparatus is set based on a difference between the lower limit of and .
[Configuration 4]
Configuration 2 or 3. The image forming apparatus according to 3.
[Configuration 5]
The control means is characterized in that when the value of the inclination is less than a second threshold value when it is determined that the roller member has been replaced, the control means prompts the user to perform an operation regarding whether or not the roller member has been replaced with a new one. The image forming apparatus according to configuration 4.
[Configuration 6]
The image according to configuration 4 or 5, wherein the second threshold value of the inclination value is set based on a lower limit value of a range of the inclination values that can be taken when the roller member is new. Forming device.
[Configuration 7]
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Calculating the difference between the maximum value and the average value of the current detected after the voltage is applied to the roller member,
The roller member is adjusted based on the amount of change from the first difference value calculated at the first timing to the second difference value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced.
[Configuration 8]
The control means may determine that the roller member has been replaced when the amount of change from the first difference value to the second difference value is greater than or equal to a third threshold. The image forming apparatus according to configuration 7.
[Configuration 9]
The third threshold value of the difference is the difference between the value of the difference when the roller member reaches the end of its life and the lower limit value of the range of the value of the difference that can be taken when the roller member is new. The image forming apparatus according to configuration 8, wherein the image forming apparatus is configured based on the configuration.
[Configuration 10]
The control means includes:
If the amount of change from the first difference value to the second difference value is greater than or equal to the third threshold, determining that the roller member has been replaced with a new one;
If the amount of change from the first difference value to the second difference value is less than the third threshold and greater than or equal to the fourth threshold, which is smaller than the third threshold, The image forming apparatus according to configuration 8 or 9, characterized in that the image forming apparatus prompts the user to perform an operation regarding whether or not the roller member has been replaced with a new one.
[Configuration 11]
The control means obtains the maximum value during a first predetermined period immediately after the application means applies the voltage to the roller member, and obtains the maximum value after the first predetermined period has elapsed. The image forming apparatus according to any one of configurations 7 to 10, wherein the average value is acquired during a period.
[Configuration 12]
12. The image forming apparatus according to configuration 11, wherein the maximum value of the current is a value corresponding to occurrence of an overshoot when the current rises during the first predetermined period.
[Configuration 13]
a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on at least three levels of voltage applied to the roller member and each current detected when each voltage is applied, the slope of the current-voltage characteristics of at least two or more types of the roller member is determined. Calculate the determined index value,
The roller member is moved based on the value of the first index value calculated at the first timing and the value of the second index value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced.
[Configuration 14]
14. The image forming apparatus according to configuration 13, wherein the index value is determined by two or more types of calculated slopes.
[Configuration 15]
15. The image forming apparatus according to configuration 13 or 14, wherein the control means determines that the roller member is new when the index value is less than or equal to a fifth threshold value.
[Configuration 16]
Configurations 13 to 15, characterized in that the control means determines that the roller member has been replaced when it is determined that it is not new according to the first index value and it is determined that it is new according to the second index value. The image forming apparatus according to any one of the above.

11: Secondary transfer roller, 53: Secondary transfer voltage power supply, 25: Control board, 26: CPU

Claims (16)

a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on a first current detected when a first voltage is applied to the roller member and a second current detected when a second voltage is applied to the roller member, Calculating the value of the slope of the current-voltage characteristic of the roller member,
The roller member is adjusted based on the amount of change from the first slope value calculated at the first timing to the second slope value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced. The control means may determine that the roller member has been replaced when the amount of change from the first slope value to the second slope value is greater than or equal to a first threshold value. The image forming apparatus according to claim 1. The first threshold value of the amount of change is an upper limit value of the range of values of the slope that can be taken when the roller member reaches the end of its life, and a range of values of the slope that can be taken when the roller member is new. The image forming apparatus according to claim 2, wherein the image forming apparatus is set based on a difference between the lower limit of and the lower limit of . 2. The control means determines that the roller member has been replaced with a new one when the value of the inclination when determining that the roller member has been replaced is greater than or equal to a second threshold value. The image forming apparatus described in . The control means is characterized in that when the value of the inclination is less than a second threshold value when it is determined that the roller member has been replaced, the control means prompts the user to perform an operation regarding whether or not the roller member has been replaced with a new one. The image forming apparatus according to claim 4. 6. The second threshold value of the inclination value is set based on a lower limit value of the range of the inclination value that can be taken when the roller member is new. Image forming device. a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Calculating the difference between the maximum value and the average value of the current detected after the voltage is applied to the roller member,
The roller member is adjusted based on the amount of change from the first difference value calculated at the first timing to the second difference value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced. The control means may determine that the roller member has been replaced when the amount of change from the first difference value to the second difference value is greater than or equal to a third threshold. The image forming apparatus according to claim 7. The third threshold value of the difference is the difference between the value of the difference when the roller member reaches the end of its life and the lower limit value of the range of the value of the difference that can be taken when the roller member is new. The image forming apparatus according to claim 8, wherein the image forming apparatus is set based on the image forming apparatus. The control means includes:
If the amount of change from the first difference value to the second difference value is greater than or equal to the third threshold, determining that the roller member has been replaced with a new one;
If the amount of change from the first difference value to the second difference value is less than the third threshold and greater than or equal to the fourth threshold, which is smaller than the third threshold, 9. The image forming apparatus according to claim 8, wherein the image forming apparatus prompts the user to perform an operation regarding whether or not the roller member has been replaced with a new one. The control means obtains the maximum value during a first predetermined period immediately after the application means applies the voltage to the roller member, and obtains the maximum value after the first predetermined period has elapsed. The image forming apparatus according to any one of claims 7 to 10, wherein the average value is acquired during a period. 12. The image forming apparatus according to claim 11, wherein the maximum value of the current is a value that corresponds to the occurrence of an overshoot when the current rises during the first predetermined period. a replaceable roller member;
application means for applying voltage to the roller member;
current detection means for detecting a current flowing through the roller member to which the voltage is applied;
control means;
An image forming apparatus comprising:
The control means includes:
Based on at least three levels of voltage applied to the roller member and each current detected when each voltage is applied, the slope of the current-voltage characteristics of at least two or more types of the roller member is determined. Calculate the determined index value,
The roller member is moved based on the value of the first index value calculated at the first timing and the value of the second index value calculated at the second timing after the first timing. An image forming apparatus characterized by determining whether or not it has been replaced. The image forming apparatus according to claim 13, wherein the index value is determined by two or more types of calculated slopes. The image forming apparatus according to claim 13, wherein the control means determines that the roller member is new when the index value is less than or equal to a fifth threshold value. From claim 13, wherein the control means determines that the roller member has been replaced when the first index value determines that the roller member is not new, and the second index value determines that the roller member is new. 16. The image forming apparatus according to any one of 15 to 15.

Images