JP7472570B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

Patent document 1 discloses an image forming apparatus. The image forming apparatus disclosed in patent document 1 includes an image forming unit and a drive mechanism. The image forming unit includes a photosensitive drum and a cleaning blade. The photosensitive drum carries a toner image. The cleaning blade cleans toner remaining on the peripheral surface of the photosensitive drum. The cleaning blade is made of rubber. The cleaning blade is fixed and contacts the peripheral surface of the photosensitive drum. The drive mechanism rotates the photosensitive drum and moves the photosensitive drum back and forth in the axial direction of the photosensitive drum.

JP 2012-133268 A

However, in the image forming device disclosed in Patent Document 1, as time passes from the time when the cleaning blade comes into contact with the peripheral surface of the photosensitive drum (hereinafter referred to as the "manufacturing date and time"), the linear pressure applied from the cleaning blade toward the center of the photosensitive drum decreases due to the occurrence of permanent strain in the rubber that constitutes the cleaning blade. Furthermore, in the image forming device disclosed in Patent Document 1, when the photosensitive drum is moved back and forth in the axial direction of the photosensitive drum, the force applied from the cleaning blade toward the center of the photosensitive drum is dispersed in the axial direction of the photosensitive drum, decreasing the linear pressure.

The image forming device may be used even after the period since the date of manufacture (hereinafter referred to as the "period since manufacture") exceeds the period during which the quality of the image forming unit is guaranteed (hereinafter referred to as the "usage warranty period"). The usage warranty period indicates the period from the date of manufacture. For example, if the image forming device is started to be used after a long period has passed since the date of manufacture, the image forming device may continue to be used even after the period since manufacture exceeds the period equivalent to the usage warranty period (hereinafter referred to as the "usage warranty equivalent period"). If the image forming device disclosed in Patent Document 1 is used continuously after the period since manufacture exceeds the usage warranty equivalent period, scratches may occur on the circumferential surface of the photosensitive drum due to a decrease in linear pressure. Furthermore, there is a risk that toner and external additives may slip through between the circumferential surface of the photosensitive drum and the cleaning blade. As a result, there is a risk that image defects may occur in the image forming device disclosed in Patent Document 1.

In view of the above problems, the present invention aims to provide an image forming device that can maintain the quality of an image forming unit even if the date and time when the image forming unit begins to be used is later than the date and time of manufacture and the period of time that has elapsed since manufacture exceeds the period of guaranteed use.

The image forming apparatus according to the present invention prints an image on a sheet. The image forming apparatus includes an image forming unit, a first drive unit, a control unit, a reading unit, and a memory unit. The image forming unit has an image carrier and a cleaning member. The cleaning member is pressed against the image carrier. The first drive unit executes a thrust operation. The thrust operation is an operation for relatively moving the image carrier and the cleaning member back and forth along the rotation axis direction of the image carrier. The control unit controls the first drive unit. The reading unit reads manufacturing date and time information from the image forming unit. The manufacturing date and time information indicates the manufacturing date and time of the image forming unit. The memory unit stores usage guarantee information. The usage guarantee information indicates a period equivalent to a usage guarantee period (Xl) from the manufacturing date and time that guarantees the quality of the image forming unit. The control unit calculates the elapsed period (Xi) from the manufacturing date and time to the date and time when the image forming unit is attached to the image forming apparatus based on the manufacturing date and time information. The control unit calculates the remaining period (Xr) until an image defect occurs based on the elapsed period (Xi). The control unit determines whether the remaining period (Xr) is longer than the guaranteed usage period (Xl). When the control unit determines that the remaining period (Xr) is not longer than the guaranteed usage period (Xl), it controls the first drive unit so that the linear pressure of the cleaning member against the circumferential surface of the image carrier is increased at a timing that satisfies a predetermined condition.

According to the present invention, even if the date and time when the image forming unit begins to be used is later than the date and time when it was manufactured, and the period of time that has passed since manufacture exceeds the period of guaranteed use, the quality of the image forming unit can be maintained.

1 is a cross-sectional view showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a cleaner included in the image forming apparatus according to the embodiment of the present invention. 1 is a diagram showing a photosensitive drum, a cleaning blade, and a driving mechanism included in an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a photoconductor drum according to the embodiment of the present invention. 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention; FIG. 13 is a diagram showing the relationship between pressure contact time and blade linear pressure. FIG. 13 is a diagram showing the relationship between pressure contact time and blade linear pressure. FIG. 13 is a diagram showing the relationship between pressure contact time and blade linear pressure. 5 is a flowchart showing a thrust stop timing determination process of the image forming apparatus according to the embodiment of the present invention. 5 is a flowchart showing a thrust stop timing determination process of the image forming apparatus according to the embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be given the same reference symbols and the description will not be repeated. The drawings mainly show each component in a schematic manner to facilitate understanding, and the shape of each illustrated component may differ from the actual shape for the convenience of creating the drawings.

With reference to FIG. 1, an image forming apparatus 1 according to an embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing the image forming apparatus 1. Note that in FIG. 1, the X-axis, Y-axis, and Z-axis are mutually orthogonal.

The image forming device 1 prints an image on a sheet P. In this embodiment, the image forming device 1 is a full-color printer. As shown in FIG. 1, the image forming device 1 includes a feed section 10, a transport section 20, an image forming section 30, a fixing section 40, and an ejection section 50. The sheet P includes, for example, plain paper, copy paper, recycled paper, thin paper, thick paper, glossy paper, or an overhead projector (OHP) sheet.

The feeding unit 10 includes a cassette 11. The cassette 11 can accommodate a plurality of sheets P. The feeding unit 10 feeds the sheets P from the cassette 11 to the conveying unit 20. The feeding unit 10 includes a pickup roller, a feed roller, and a retard roller.

The transport unit 20 has a transport path. The transport path extends from the feeding unit 10 to the discharge unit 50. The transport unit 20 transports the sheet P along the transport path. The transport unit 20 includes multiple pairs of transport rollers.

The image forming unit 30 executes an image forming process. The image forming process refers to a process of forming a color toner image on the sheet P using toner. The color toner image is an example of an image.

The fixing unit 40 applies heat and pressure to the sheet P to fix the color toner image to the sheet P. This causes the color toner image to be printed on the sheet P. The fixing unit 40 includes a heating member and a pressure member.

The discharge section 50 discharges the sheet P to the outside of the image forming device 1. The discharge section 50 includes a pair of discharge rollers.

Next, the configuration of the image forming unit 30 will be further described with reference to FIG. 1.

The image forming section 30 includes an exposure unit 31, an M unit 32M, a C unit 32C, a Y unit 32Y, a BK unit 32BK, an intermediate transfer belt 33, a secondary transfer roller 34, a primary transfer roller 35, a static electricity removal lamp 36, and a toner supply section 37. Hereinafter, any one of the M unit 32M, the C unit 32C, the Y unit 32Y, and the BK unit 32BK may be referred to as a "replacement unit 32." Each of the M unit 32M, the C unit 32C, the Y unit 32Y, and the BK unit 32BK is an example of an image forming unit.

Each of the M unit 32M to the BK unit 32BK includes a photoconductor drum 61, a charging roller 62, a developing roller 63, and a cleaner 64. The photoconductor drum 61 is an example of an image carrier.

The photoconductor drum 61 rotates around a rotation axis. The photoconductor drum 61 is, for example, a positively charged OPC (Organic Photoconductor) drum. Alternatively, the photoconductor drum 61 is a negatively charged OPC drum. In this embodiment, the photoconductor drum 61 is an OPC drum. The photosensitive layer 611 of the photoconductor drum 61 may be a single-layer photosensitive layer or a multi-layer photosensitive layer.

The charging roller 62 charges the peripheral surface of the photosensitive drum 61 (the surface of the photosensitive layer). Specifically, the charging roller 62 contacts the peripheral surface of the photosensitive drum 61 and applies a charging bias to the peripheral surface of the photosensitive drum 61. In other words, the charging method for charging the photosensitive drum 61 is a roller charging method (an example of a contact charging method). The charging roller 62 charges the photosensitive drum 61 by causing a proximity discharge between the charging roller 62 and the peripheral surface of the photosensitive drum 61. In this embodiment, the charging bias is a DC voltage. An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 61 (the surface of the photosensitive layer) by the exposure unit 31.

The discharge lamp 36 removes residual charge from the peripheral surface of the photosensitive drum 61 (the surface of the photosensitive layer).

The cleaner 64 removes toner (residual toner) remaining on the peripheral surface of the photoreceptor drum 61. In addition, if powder (e.g., cellulose clumps or filler clumps) generated by the sheet P adheres to the peripheral surface of the photoreceptor drum 61, the cleaner 64 can remove the adhered powder. Hereinafter, residual toner and foreign matter such as external additives adhering to the peripheral surface of the photoreceptor drum 61 may be collectively referred to as "adhered matter." The configuration of the cleaner 64 will be described later with reference to FIG. 2.

The exposure unit 31 irradiates the photoconductor drum 61 included in each of the M unit 32M to the BK unit 32BK with light based on image data, and forms an electrostatic latent image on the photoconductor drum 61 included in each of the M unit 32M to the BK unit 32BK.

M unit 32M forms a magenta toner image based on the electrostatic latent image. C unit 32C forms a cyan toner image based on the electrostatic latent image. Y unit 32Y forms a yellow toner image based on the electrostatic latent image. BK unit 32BK forms a black toner image based on the electrostatic latent image. Each of M unit 32M to BK unit 32BK is detachable from image forming device 1. In this embodiment, M unit 32M to BK unit 32BK are replaced simultaneously.

The primary transfer roller 35 transfers the toner image formed on the peripheral surface of the photosensitive drum 61 onto the outer surface of the intermediate transfer belt 33.

Four color toner images are transferred onto the outer surface of the intermediate transfer belt 33 in a superimposed manner. As a result, a color toner image is formed on the outer surface of the intermediate transfer belt 33.

The secondary transfer roller 34 transfers the color toner image formed on the outer surface of the intermediate transfer belt 33 onto the sheet P.

The developing roller 63 supplies toner to the peripheral surface of the photoconductor drum 61. This causes the toner to adhere to the peripheral surface of the photoconductor drum 61 in accordance with the electrostatic latent image, developing the electrostatic latent image. As a result, a toner image is formed on the peripheral surface of the photoconductor drum 61.

The toner supply unit 37 includes cartridges 37M, 37C, 37Y, and 37BK. Cartridge 37M contains magenta toner. Cartridge 37C contains cyan toner. Cartridge 37Y contains yellow toner. Cartridge 37BK contains black toner. Cartridges 37M to 37BK supply toner (developer) to the developing rollers 63 of M unit 32M to BK unit 32BK, respectively.

Next, we will explain the developer contained in cartridges 37M to 37BK. The developer may be a one-component developer or a two-component developer. The developer contains toner. In the case of a two-component developer, the developer contains a carrier in addition to the toner.

The toner is a powder composed of a plurality of toner particles (a large number of toner particles). The toner particles may contain toner base particles and external additives. The external additives adhere to the surfaces of the toner base particles. The toner base particles may contain a binder resin for the toner base particles and internal additives. The internal additives include, for example, a release agent and a colorant. If not necessary, the toner particles may not contain external additives. In this case, the toner base particles correspond to the toner particles. If necessary, the toner base particles may contain a charge control agent and/or a magnetic powder as an internal additive. If not necessary, the toner base particles may not contain an internal additive. The toner may be a capsule toner. A capsule toner can be produced by forming a shell layer on the surface of the toner base particles.

Next, the cleaner 64 will be described with reference to Figures 1 and 2. Figure 2 shows the cleaner 64.

As shown in FIG. 2, the cleaner 64 includes a cleaning blade 641 and a toner seal 642. The cleaning blade 641 is an example of a cleaning member.

The cleaning blade 641 is made of, for example, rubber. The cleaning blade 641 is pressed against the peripheral surface of the photosensitive drum 61 downstream of the primary transfer roller 35 in the rotation direction R of the photosensitive drum 61. Specifically, the tip of the cleaning blade 641 is pressed against the peripheral surface of the photosensitive drum 61. The direction from the base end of the cleaning blade 641 to the tip is opposite to the rotation direction R at the contact point between the tip of the cleaning blade 641 and the peripheral surface of the photosensitive drum 61, and intersects with the rotation direction R. With this configuration, the cleaning blade 641 removes adhesions (residual toner, etc.) that have adhered to the peripheral surface of the photosensitive drum 61.

In this embodiment, the line pressure of the cleaning blade 641 against the peripheral surface of the photosensitive drum 61 is set to be equal to or greater than the minimum quality assurance line pressure (bmin). Hereinafter, the line pressure of the cleaning blade 641 against the peripheral surface of the photosensitive drum 61 will be referred to as the "blade line pressure". The blade line pressure indicates the line pressure applied to the peripheral surface of the photosensitive drum 61 in the direction from the tip of the cleaning blade 641 toward the center of the photosensitive drum 61. The minimum quality assurance line pressure (bmin) indicates the minimum value of the blade line pressure (N/m) at which no image defects occur. Therefore, if the blade line pressure is less than the minimum quality assurance line pressure (bmin), image defects occur. The minimum quality assurance line pressure (bmin) varies depending on the material of the rubber constituting the cleaning blade 641 and the configuration of the image forming apparatus 1. For example, the minimum quality assurance line pressure (bmin) is 9.8 N/m, 12.3 N/m, 12.5 N/m, or 14.2 N/m. The minimum quality assurance linear pressure (bmin) will be described later with reference to Figure 6.

The blade linear pressure is measured using a load cell when the image forming unit 30 is stopped. More specifically, a jig is created in which a load cell is placed in place of the photosensitive drum 61 at the contact position of the cleaning blade 641 against the circumferential surface of the photosensitive drum 61 of the image forming device 1. The contact angle of the cleaning blade 641 against the load cell is set to 23 degrees. The cleaning blade 641 is pressed against the load cell. The load cell is used to measure the linear pressure 10 seconds after the start of pressure contact, and a measured value is obtained.

The toner seal 642 contacts the peripheral surface of the photosensitive drum 61 between the primary transfer roller 35 and the cleaning blade 641, and prevents the scattering of any adhering matter (residual toner, etc.) removed and collected by the cleaning blade 641.

Next, the photoconductor drum 61 and its surroundings will be described with reference to FIG. 3. FIG. 3 shows the photoconductor drum 61, cleaning blade 641, and thrust drive unit 70.

As shown in FIG. 3, the photosensitive drum 61 is cylindrical and extends along the rotation axis direction D of the photosensitive drum 61. The cleaning blade 641 is plate-shaped and extends along the rotation axis direction D.

The image forming apparatus 1 further includes a thrust drive unit 70. When the thrust drive unit 70 is driven, the photosensitive drum 61 and the cleaning blade 641 move back and forth relative to each other along the rotation axis direction D (thrust). In other words, the thrust drive unit 70 moves the photosensitive drum 61 and the cleaning blade 641 back and forth relative to each other along the rotation axis direction D (thrust). Hereinafter, "the thrust drive unit 70 moves the photosensitive drum 61 and the cleaning blade 641 back and forth relative to each other along the rotation axis direction D" will be described as "the thrust drive unit 70 executes a thrust operation" and the like. However, since the mechanism for simultaneously moving the photosensitive drum 61 and the cleaning blade 641 back and forth is complicated, it is preferable to move one of the photosensitive drum 61 and the cleaning blade 641 back and forth. In addition, since the mechanism for moving the cleaning blade 641 back and forth is complicated compared to the mechanism for moving the photosensitive drum 61 back and forth, it is preferable to move the photosensitive drum 61 back and forth. The thrust drive unit 70 is an example of a first drive unit.

In this embodiment, the thrust drive unit 70 periodically reciprocates (thrusts) the photosensitive drum 61 relative to the fixed cleaning blade 641. The thrust drive unit 70 includes, for example, a drive source such as a motor, a gear train, multiple cams, and multiple elastic members. The cleaning blade 641 is fixed, for example, to the housing of the image forming device 1.

As described with reference to FIG. 3, according to this embodiment, the photosensitive drum 61 is reciprocated (thrust) in the direction of the rotation axis D relative to the cleaning blade 641. As a result, the deposits accumulated on the tip of the cleaning blade 641 move in the direction of the rotation axis D, making it difficult for the deposits to become unevenly distributed. As a result, uneven wear of the circumferential surface of the photosensitive drum 61 caused by uneven distribution of the deposits is suppressed, and the friction coefficient of the circumferential surface of the photosensitive drum 61 is kept constant along the direction of the rotation axis D. Therefore, the slipperiness of the circumferential surface of the photosensitive drum 61 is maintained, making it difficult for deposits and deposits to slip through the tip of the cleaning blade 641. In addition, when the circumferential surface of the photosensitive drum 61 is unevenly worn, the deposits and deposits are likely to slip through the tip of the cleaning blade 641 from the unevenly worn area. In contrast, in this embodiment, uneven wear of the circumferential surface of the photosensitive drum 61 is suppressed, making it difficult for deposits and deposits to slip through the tip of the cleaning blade 641.

In addition, according to this embodiment, since the photosensitive drum 61 is moved back and forth, it is possible to move the photosensitive drum 61 and the cleaning blade 641 back and forth relative to each other along the rotation axis direction D with a simple configuration. Furthermore, compared to the case where the cleaning blade 641 is moved back and forth, it is easier to obtain the driving force required for the reciprocating movement, and it is possible to suppress toner leakage from both ends of the cleaning blade 641.

Next, the photoconductor drum 61 will be further described with reference to FIG. 4. FIG. 4 is a perspective view showing the photoconductor drum 61.

As shown in FIG. 4, the photosensitive drum 61 rotates in a rotation direction R around the rotation axis AX. The rotation axis direction D is the direction in which the rotation axis AX extends. The photosensitive drum 61 includes a photosensitive layer 611. The photosensitive layer 611 contains a charge generating agent, a charge transport agent, and a binder resin. The photosensitive layer 611 further contains a plurality of filler particles. In this embodiment, the binder resin is a polycarbonate resin. By using a polycarbonate resin as the binder resin, wear of the photosensitive layer 611 can be suppressed even if the pressure applied from the tip of the cleaning blade 641 to the photosensitive layer 611 becomes high. Therefore, the life of the photosensitive drum 61 can be extended.

Next, the configuration of the image forming device 1 will be further described with reference to Figures 1 to 5. Figure 5 is a block diagram showing the configuration of the image forming device 1 according to this embodiment.

As shown in FIG. 5, the image forming device 1 includes a reading unit 71, a rotation drive unit 72, a torque detection unit 73, a communication unit 74, a memory unit 75, and a control unit 76. The rotation drive unit 72 is an example of a second drive unit.

Each of the M unit 32M to the BK unit 32BK has an IC (Integrated Circuit) tag. The IC tag is located, for example, on the outer periphery of each of the M unit 32M to the BK unit 32BK.

The IC tag of each of the M unit 32M to BK unit 32BK stores unit information. The unit information includes usage information, manufacturing date and time information, and product number information. The usage information indicates whether the corresponding one of the M unit 32M to BK unit 32BK is new or not. The manufacturing date and time information indicates the manufacturing date and time of the corresponding one of the M unit 32M to BK unit 32BK. The product number information indicates the product number of the corresponding one of the M unit 32M to BK unit 32BK.

In this embodiment, the reading unit 71 has a first reading unit, a second reading unit, a third reading unit, and a fourth reading unit. The first reading unit reads unit information from the IC tag of the M unit 32M. The second reading unit reads unit information from the IC tag of the C unit 32C. The third reading unit reads unit information from the IC tag of the Y unit 32Y. The fourth reading unit reads unit information from the IC tag of the BK unit 32BK.

In this embodiment, the rotation drive unit 72 drives and rotates the photoconductor drums 61 of each of the M unit 32M to the BK unit 32BK. The rotation drive unit 72 includes, for example, a motor.

The torque detection unit 73 detects the torque of the rotation drive unit 72 when rotating and driving each of the photoconductor drums 61 of the M unit 32M to the BK unit 32BK. The torque detection unit 73 includes, for example, a magnetostrictive torque sensor, a strain gauge torque sensor, a piezoelectric torque sensor, an optical torque sensor, a spring torque sensor, or a capacitance torque sensor.

The communication unit 74 communicates with an external terminal via a network. The communication unit 74 receives image formation job data transmitted from the external terminal. The image formation job data indicates image data and setting information. The setting information includes number of copies information, single-sided/double-sided information, and black-and-white/color information. The number of copies information indicates the number of copies. The single-sided/double-sided information indicates whether an image is formed on one side of the sheet P or on both sides of the sheet P. The black-and-white/color information indicates whether a black-and-white image or a color image is formed. The communication unit 74 is a communication interface. The external terminal is, for example, a desktop personal computer, a notebook personal computer, a tablet terminal, or a smartphone.

The storage unit 75 is composed of a hard disk drive (HDD), a random access memory (RAM), and a read only memory (ROM). The storage unit 75 stores a control program for controlling the operation of each part of the image forming device 1. The storage unit 75 stores image formation job data received by the communication unit 74.

The storage unit 75 stores the usage guarantee information. The usage guarantee information indicates a period equivalent to the usage guarantee period (Xl) of each of the M unit 32M to the BK unit 32BK (hereinafter, referred to as the "usage guarantee equivalent period (Xl')"). The usage guarantee period (Xl) of the M unit 32M is a period during which the quality of the M unit 32M is guaranteed, and this period starts from the manufacturing date and time of the M unit 32M. The usage guarantee period (Xl) of each of the C unit 32C to the BK unit 32BK is also the same as the usage guarantee period (Xl) of the M unit 32M. For example, the usage guarantee period (Xl) is 1 year (8760 hours), 3 years (26280 hours), or 5 years (43800 hours). The length of the usage guarantee period (Xl) and the length of the usage guarantee equivalent period (Xl') are the same. In this embodiment, the usage guarantee period (Xl) of each of the M unit 32M to the BK unit 32BK is the same.

The storage unit 75 stores the usage upper limit information. The usage upper limit information indicates the usage upper limit period (Xf) of each of the M unit 32M to the BK unit 32BK. The usage upper limit period (Xf) of the M unit 32M indicates the shortest period from the manufacturing date and time of the M unit 32M to the occurrence of an image defect caused by the M unit 32M. The usage upper limit period (Xf) of each of the C unit 32C to the BK unit 32BK is also the same as the usage upper limit period (Xf) of the M unit 32M. In this embodiment, the usage upper limit period (Xf) of each of the M unit 32M to the BK unit 32BK is the same. The usage upper limit period (Xf) is shorter than the usage guarantee period (Xl). Details of the usage upper limit period (Xf) will be described later with reference to FIG. 6.

The control unit 76 is a hardware circuit. The hardware circuit includes a processor such as a CPU (Central Processing Unit). The control unit 76 executes a control program stored in the memory unit 75 to control the feeding unit 10, the conveying unit 20, the image forming unit 30, the fixing unit 40, the discharge unit 50, the thrust drive unit 70, the reading unit 71, the rotation drive unit 72, the communication unit 74, and the memory unit 75.

The control unit 76 executes a thrust stop timing determination process to determine the thrust stop timing (Xs). The control unit 76 causes the thrust drive unit 70 to perform a thrust operation until the thrust stop timing (Xs). When the period from the start of use of the replacement unit 32 exceeds the thrust stop timing (Xs), the control unit 76 does not cause the thrust drive unit 70 to perform a thrust operation thereafter. In other words, the thrust stop timing (Xs) indicates the timing at which the thrust drive unit 70 stops (ends) the execution of the thrust operation. The thrust stop timing determination process will be described in detail later with reference to Figures 9 and 10.

Next, the blade line pressure prediction formula will be explained with reference to Figure 6. Figure 6 shows the relationship between pressure contact time and blade line pressure.

6, the horizontal axis indicates the pressure contact time (hours). The pressure contact time indicates the time elapsed from the date and time of manufacture of the replacement unit 32, that is, from the date and time of the cleaning blade 641 being pressed against the peripheral surface of the photosensitive drum 61. Hereinafter, the pressure contact time may be referred to as the "period of time elapsed since manufacture". The vertical axis indicates the blade linear pressure (N/m). The solid line indicates the predicted curve G of the blade linear pressure. The predicted curve G of the blade linear pressure indicates the predicted value of the blade linear pressure with respect to the pressure contact time. The predicted curve G of the blade linear pressure is derived under the first condition and the second condition. The first condition is that the image forming apparatus 1 has been using the replacement unit 32 since the replacement unit 32 was manufactured. The second condition is that the thrust drive unit 70 is performing a thrust operation. The predicted curve G of the blade linear pressure is based on the prediction formula (1) below. The plot indicates the measured value of the blade linear pressure. bmin indicates the minimum quality assurance linear pressure (N/m). Xf is the upper limit of use (hours). The upper limit of use (Xf) indicates the period from the date and time of manufacture of the replacement unit 32 to the pressure contact time corresponding to the minimum quality assurance linear pressure (bmin). Xl indicates the guaranteed use period.

The inventors have conducted extensive research into the relationship between pressure contact time and blade line pressure. As a result of focusing on the decrease in blade line pressure caused by the occurrence of permanent distortion of the rubber constituting the cleaning blade 641 and the decrease in blade line pressure caused by the driving of the thrust drive unit 70 when the thrust drive unit 70 is performing a thrust operation from the manufacturing date and time of the replacement unit 32, the inventors have found that the relationship between pressure contact time and blade line pressure is close to the prediction formula shown in the following formula (1).

In formula (1), Y represents the blade linear pressure (N/m). X represents the pressure contact time (hours). Each of a and b represents a numerical value (N/m) based on the characteristics of the rubber that constitutes the cleaning blade 641 and the rate of change in linear pressure due to thrust operation.

As shown in FIG. 6, the predicted value of the blade line pressure obtained from the prediction formula shown in the above formula (1) corresponds to the measured value of the blade line pressure. Therefore, it can be seen that the prediction formula shown in the above formula (1) can predict the change in the actual blade line pressure over the course of the pressure contact time. Furthermore, it can be seen that if the date and time when the replacement unit 32 started to be used is the date and time when the replacement unit 32 was manufactured, no image defects will occur even if the thrust drive unit 70 performs a thrust operation from the date and time when the replacement unit 32 started to be used until the warranty period (Xl) of the replacement unit 32. The memory unit 75 stores prediction formula information. The prediction formula information indicates the prediction formula shown in the above formula (1).

Next, referring to Figures 7 and 8, the relationship between the pressure contact time and the equivalent period of guaranteed use (Xl') when the date and time when the replacement unit 32 begins to be used is later than the date and time when the replacement unit 32 was manufactured will be described. Figures 7 and 8 are diagrams showing the relationship between the pressure contact time and the blade line pressure when the date and time when the replacement unit 32 begins to be used is later than the date and time when the replacement unit 32 was manufactured. In particular, Figure 7 shows the relationship between the pressure contact time and the equivalent period of guaranteed use (Xl') when the elapsed period (Xi) is relatively short. Figure 8 shows the relationship between the pressure contact time and the equivalent period of guaranteed use (Xl') when the elapsed period (Xi) is relatively long.

In Figures 7 and 8, Xi indicates the elapsed period from the date and time of manufacture of the replacement unit 32 to the date and time when use of the replacement unit 32 began. Hereinafter, Xi will be referred to as the "elapsed period (Xi)". Xl' indicates the equivalent period of guaranteed use. Xr indicates the remaining period until an image defect occurs. Hereinafter, Xr will be referred to as the "remaining period (Xr)". The remaining period (Xr) indicates the period obtained by subtracting the elapsed period (Xi) from the upper limit use period (Xf). In Figure 8, Xs indicates the thrust stop timing. The thrust stop timing (Xs) indicates the period obtained by adding the thrust operation period described later with reference to Figure 9 to the elapsed period (Xi).

As shown in FIG. 7, when the elapsed period (Xi) is relatively short, that is, when the relationship of "(Xi + Xl') < Xf" is satisfied, the pressure contact time does not reach the upper limit of the usage period (Xf) even if the usage guarantee period (Xl') has elapsed. Therefore, when the usage guarantee period (Xl') has elapsed, the blade line pressure exceeds the minimum quality guarantee line pressure (bmin), and no image defects occur.

On the other hand, as shown in FIG. 8, when the elapsed period (Xi) is relatively long, that is, when the relationship of "(Xi + Xl') > Xf" is satisfied, the pressure contact time reaches the upper limit of the usage period (Xf) before the usage guarantee period (Xl') has elapsed. Therefore, when the usage guarantee period (Xl') has elapsed, the blade line pressure falls below the quality guarantee minimum line pressure (bmin), and image defects occur.

Therefore, the inventors have conducted extensive research and found that, based on the prediction formula shown in the above formula (1), by stopping the driving of the thrust drive unit 70 just before the blade line pressure reaches the minimum quality assurance line pressure (bmin), the blade line pressure becomes higher than when the thrust drive unit 70 is driven, and the quality of the replacement unit 32 can be maintained even if the pressure contact time reaches the upper limit of the use period (Xf). In other words, by stopping the driving of the thrust drive unit 70 just before the blade line pressure reaches the minimum quality assurance line pressure (bmin), the blade line pressure becomes higher, and it is possible to suppress the occurrence of the slipping of the deposits between the circumferential surface of the photosensitive drum 61 and the cleaning blade 641. Furthermore, by stopping the driving of the thrust drive unit 70 just before the blade line pressure reaches the minimum quality assurance line pressure (bmin), that is, in a state in which the blade line pressure is reduced due to the occurrence of permanent deformation of the rubber constituting the cleaning blade 641, it has been found that even if the external additive aggregates at the tip of the cleaning blade 641, scratches will not occur on the circumferential surface of the photosensitive drum 61. For example, it has been discovered that the quality of the replacement unit 32 can be maintained by having the control unit 76 execute the thrust stop timing determination process described below with reference to Figures 9 and 10.

Next, the thrust stop timing determination process executed by the control unit 76 will be described with reference to Figures 9 and 10. Figures 9 and 10 are flowcharts showing the thrust stop timing determination process of the image forming device 1 according to this embodiment.

The thrust stop timing determination process shown in Figures 9 and 10 starts when the replacement unit 32 is attached to the image forming device 1.

Step S10: As shown in FIG. 9, the control unit 76 determines whether the replacement unit 32 attached to the image forming device 1 is new or not based on the output of the reading unit 71. If the control unit 76 determines that the replacement unit 32 attached to the image forming device 1 is new (Step S10: Yes), the process proceeds to Step S11. If the control unit 76 determines that the replacement unit 32 attached to the image forming device 1 is not new (Step S10: No), the process ends (see FIG. 10).

Step S11: The control unit 76 calculates the elapsed period (Xi) based on the manufacturing date and time information acquired by the reading unit 71. The process proceeds to step S12.

Step S12: The control unit 76 calculates the remaining period (Xr) based on the elapsed period (Xi) and the usage upper limit information stored in the storage unit 75. The process proceeds to step S13.

Step S13: The control unit 76 determines whether the remaining period (Xr) is longer than the period equivalent to the guaranteed use (Xl'). If the control unit 76 determines that the remaining period (Xr) is longer than the period equivalent to the guaranteed use (Xl') (Step S13; Yes), the process proceeds to Step S15 shown in FIG. 10. If the control unit 76 determines that the remaining period (Xr) is not longer than the period equivalent to the guaranteed use (Xl') (Step S13; No), the process proceeds to Step S14.

Step S14: The control unit 76 calculates the thrust operation period based on the remaining period (Xr). The thrust operation period indicates the period from the elapsed period (Xi) until the thrust drive unit 70 is caused to perform the thrust operation. The process proceeds to step S15 shown in FIG. 10. The thrust operation period is an example of a timing that satisfies a predetermined condition.

In this embodiment, the control unit 76 calculates the thrust operation period by multiplying the remaining period (Xr) by a safety factor. The safety factor is adjusted appropriately depending on the characteristics of the rubber, which is the material of the cleaning blade 641, and the decrease in blade line pressure caused by the thrust operation. For example, the safety factor is 0.7. The memory unit 75 stores the safety factor.

Step S15: As shown in FIG. 10, the control unit 76 counts the period that has elapsed since the date and time when the replacement unit 32 was first used. The control unit 76 determines whether or not the period that has elapsed since the date and time when the replacement unit 32 was first used exceeds the thrust operation period. If the control unit 76 determines that the period that has elapsed since the date and time when the replacement unit 32 was first used exceeds the thrust operation period (Step S15; Yes), the process proceeds to Step S18. If the control unit 76 determines that the period that has elapsed since the date and time when the replacement unit 32 was first used does not exceed the thrust operation period (Step S15; No), the process proceeds to Step S16.

Step S16: The control unit 76 detects the torque of the rotation drive unit 72 when driving and rotating the photosensitive drum 61 based on the output of the torque detection unit 73. The process proceeds to step S17.

Step S17: The control unit 76 determines whether the torque of the rotation drive unit 72 is equal to or less than a predetermined value based on the output of the torque detection unit 73. If the control unit 76 determines that the torque of the rotation drive unit 72 is equal to or less than the predetermined value (Step S17: Yes), the process proceeds to Step S18. If the control unit 76 determines that the torque of the rotation drive unit 72 is not equal to or less than the predetermined value (Step S17: No), the process returns to Step S15.

The specified value is adjusted as appropriate depending on the configuration of the image forming device 1. For example, the specified value is 14.5 N/m. The memory unit 75 stores the specified value.

Step S18: The control unit 76 decides to stop (end) the thrust operation performed by the thrust drive unit 70. The process ends.

In this manner, in this embodiment, the image forming device 1 determines the thrust operation period before the elapsed time since manufacture reaches the upper limit of the use period (Xf). In other words, the image forming device 1 determines the thrust operation period at the date and time when the replacement unit 32 starts to be used. The timing at which the thrust operation period elapses is an example of the thrust stop timing (Xs). When the elapsed time since manufacture reaches the thrust operation period, the image forming device 1 stops driving the thrust drive unit 70, thereby maintaining the quality of the replacement unit 32. Furthermore, in this embodiment, the image forming device 1 grasps the decrease in the blade line pressure based on the output of the torque detection unit 73, and when the decrease rate of the blade line pressure is greater than expected, stops driving the thrust drive unit 70 before the elapsed time since manufacture reaches the thrust operation period, thereby maintaining the quality of the replacement unit 32. The timing at which the blade line pressure becomes equal to or less than a predetermined value is an example of the thrust stop timing (Xs).

The following describes examples of the present invention, but the present invention is not limited to the following examples.

In this embodiment, a TASKalfa 2550Ci (manufactured by Kyocera Document Solutions, Inc.) modified for 40 sheets was used as the image forming apparatus. The development method of this modified machine is a non-magnetic two-component jumping development method.

In this embodiment, replacement unit A, replacement unit B, and replacement unit C were used as the replacement unit 32. Replacement unit A, replacement unit B, and replacement unit C each have the same configuration, except that the material of the cleaning blade 641 is different.

[Example 1]
A replacement unit A was used as the replacement unit 32. In Example 1, the blade linear pressure at the manufacturing date and time of the replacement unit A (hereinafter referred to as "initial linear pressure"), the quality assurance minimum linear pressure (bmin), and the usage guarantee period (Xl) were set as follows.
Initial line pressure: 20 N / m
Minimum quality assurance line pressure (bmin): 12.5 N/m
Guaranteed usage period (Xl): 26,280 hours Maximum usage period (Xf): 34,607 hours

The elapsed period (Xi) was 8,760 hours. The remaining period (Xr) was 25,847 hours. In other words, the remaining period (Xr) was shorter than the equivalent usage guarantee period (Xl'), which was the same length as the usage guarantee period (Xl). The control unit 76 calculated the thrust operation period at the date and time when replacement unit A began to be used. The thrust operation period was 18,093 hours. The safety factor was set to 0.7.

In the image forming apparatus of the first embodiment, the control unit 76 causes the image forming unit 30 to execute the image formation process, and then causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the replacement unit 32 started to be used exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation.

[Comparative Example 1]
The image forming apparatus of Comparative Example 1 is similar to that of Example 1, except that the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation.

[Comparative Example 2]
The image forming apparatus of Comparative Example 2 is similar to that of Example 1, except that the control unit 76 causes the thrust drive unit 70 to perform the thrust operation even if the period from when the use of the replacement unit 32 started exceeds the thrust operation period.

[Example 2]
A replacement unit B was used as the replacement unit 32. In the second embodiment, the initial linear pressure, the quality assurance minimum linear pressure (bmin), and the usage guarantee period (Xl) of the replacement unit A are set as follows.
Initial line pressure: 20 N / m
Minimum quality assurance line pressure (bmin): 14.2 N/m
Guaranteed usage period (Xl): 26,280 hours Maximum usage period (Xf): 32,204 hours

The elapsed period (Xi) was 6,132 hours. The remaining period (Xr) was 26,072 hours. In other words, the remaining period (Xr) was shorter than the equivalent usage guarantee period (Xl'), which was the same length as the usage guarantee period (Xl). The control unit 76 calculated the thrust operation period at the date and time when replacement unit B began to be used. The thrust operation period was 18,250 hours. The safety factor was set to 0.7.

In the image forming apparatus of the second embodiment, the control unit 76 causes the image forming unit 30 to execute the image formation process, and then causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the replacement unit 32 started to be used exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation.

[Comparative Example 3]
The image forming apparatus of Comparative Example 3 is similar to that of Example 2, except that the control unit 76 causes the thrust drive unit 70 to perform the thrust operation even if the period from when the use of the replacement unit 32 began exceeds the thrust operation period.

[Example 3]
A replacement unit C was used as the replacement unit 32. In Example 3, the initial linear pressure, the quality assurance minimum linear pressure (bmin), and the usage guarantee period (Xl) of the replacement unit C were set as follows.
Initial line pressure: 20 N / m
Minimum quality assurance line pressure (bmin): 12.3 N/m
Guaranteed usage period (Xl): 8760 hours Maximum usage period (Xf): 12671 hours

The elapsed period (Xi) was 4,380 hours. The remaining period (Xr) was 8,291 hours. In other words, the remaining period (Xr) was shorter than the equivalent usage guarantee period (Xl'), which was the same length as the usage guarantee period (Xl). The control unit 76 calculated the thrust operation period at the date and time when replacement unit C began to be used. The thrust operation period was 5,804 hours. The safety factor was set to 0.7.

In the image forming apparatus of the third embodiment, the control unit 76 causes the image forming unit 30 to execute the image formation process, and then causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the replacement unit 32 started to be used exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation.

[Comparative Example 4]
The image forming apparatus of Comparative Example 4 is similar to that of Example 3, except that the control unit 76 causes the thrust drive unit 70 to perform the thrust operation even if the period from when the use of the replacement unit 32 started exceeds the thrust operation period.

[Example 4]
A replacement unit A was used as the replacement unit 32. In Example 4, the initial linear pressure, the quality assurance minimum linear pressure (bmin), and the usage guarantee period (Xl) of the replacement unit A were set as follows.
Initial line pressure: 15 N / m
Minimum quality assurance line pressure (bmin): 9.8 N/m
Guaranteed usage period (Xl): 8760 hours Maximum usage period (Xf): 10932 hours

The elapsed period (Xi) was 2628 hours. The remaining period (Xr) was 8304 hours. In other words, the remaining period (Xr) was shorter than the equivalent usage guarantee period (Xl') which was the same length as the usage guarantee period (Xl). The control unit 76 calculated the thrust operation period at the date and time when replacement unit A began to be used. The thrust operation period was 5813 hours. The safety factor was set to 0.7.

In the image forming apparatus of Example 4, the control unit 76 causes the image forming unit 30 to execute the image formation process, and then causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the replacement unit 32 started to be used exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation.

[Comparative Example 5]
The image forming apparatus of Comparative Example 5 is similar to that of Example 4, except that the control unit 76 causes the thrust drive unit 70 to perform the thrust operation even if the period from when the use of the replacement unit 32 started exceeds the thrust operation period.

For the image forming apparatuses 1 of Examples 1 to 4 and Comparative Examples 1 to 5, a drum scratch evaluation, slip-through evaluation, and unit warranty evaluation were performed at the time when the usage warranty equivalent period (Xl') had elapsed from the date and time when the replacement unit 32 was first used. The methods for the drum scratch evaluation, slip-through evaluation, and unit warranty evaluation are as follows.

(Drum scratch evaluation)
5,000 sheets P with a printing rate of 0.5% were continuously printed, and the peripheral surface of the photosensitive drum 61 was observed to see if scratches had occurred. Furthermore, it was confirmed whether image defects had occurred on the printed sheets P. From the observation results of the peripheral surface of the photosensitive drum 61, the drum scratches were evaluated according to the following criteria.
◯: No scratches were found on the peripheral surface of the photosensitive drum 61. No image defects were found on the printed sheet P.
Δ: Scratches were found on the peripheral surface of the photosensitive drum 61, but no image defects were found on the printed sheet P.
x: Scratches were found on the peripheral surface of the photosensitive drum 61. Image defects were found on the printed sheet P.

(Slip-through evaluation)
At the time when a period equivalent to the usage guarantee period (Xl) had elapsed from the elapsed period (Xi), 5,000 sheets P with a printing rate of 50% were continuously printed, and the state of contamination of the peripheral surface of the charging roller 62 was visually observed. From the observation results of the peripheral surface of the charging roller 62, a slip-through evaluation was made according to the following criteria.
◯: No contamination was observed on the peripheral surface of the charging roller 62.
×: Contamination was observed on the peripheral surface of the charging roller 62.

A slip-through evaluation of "◯" means that the attached matter did not slip through between the circumferential surface of the photosensitive drum 61 and the cleaning blade 641. A slip-through evaluation of "×" means that the attached matter did slip through between the circumferential surface of the photosensitive drum 61 and the cleaning blade 641.

(Unit Warranty Evaluation)
The unit warranty was evaluated according to the following criteria:
○: Slip-through evaluation and drum scratch evaluation are "○"
×: At least one of the slip-through evaluation and the drum scratch evaluation is "×".

The evaluation results of image forming device 1 for Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 1.

In Comparative Example 1, the control unit 76 did not cause the thrust drive unit 70 to execute the thrust operation. Therefore, in the image forming device of Comparative Example 1, the drum damage evaluation was "x" and the unit warranty evaluation was "x". In other words, in Comparative Example 1, it was found that the quality of the replacement unit 32 could not be maintained when the period since manufacture exceeded the usage warranty equivalent period (Xl').

In Comparative Example 2, the control unit 76 caused the thrust drive unit 70 to perform the thrust operation even if the period from when the replacement unit 32 began to be used exceeded the thrust operation period. In the image forming device of Comparative Example 2, the remaining period (Xr) was shorter than the usage guarantee equivalent period (Xl') at the time when the replacement unit 32 began to be used, so the slip-through evaluation was "x" and the unit warranty evaluation was "x". It is presumed that the slip-through evaluation was "x" because the drop in blade line pressure caused by the driving of the thrust drive unit 70 caused the deposit to slip through between the circumferential surface of the photosensitive drum 61 and the cleaning blade 641. In other words, in Comparative Example 2, it was found that the quality of the replacement unit 32 cannot be maintained when the period since manufacture exceeded the usage guarantee equivalent period (Xl').

On the other hand, in Example 1, when the control unit 76 causes the image forming unit 30 to execute the image formation process, it causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the use of the replacement unit 32 started exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation. Therefore, in the image forming device of Example 1, the remaining period (Xr) at the date and time when the use of the replacement unit 32 started was shorter than the equivalent period of the usage guarantee (Xl'), but the drum scratch evaluation and slip-through evaluation were "good", and the unit warranty evaluation was "good". In other words, it was found that in Example 1, the quality of the replacement unit 32 can be maintained even if the period since manufacture exceeded the equivalent period of the usage guarantee (Xl').

In Comparative Example 3, the control unit 76 caused the thrust drive unit 70 to execute the thrust operation even when the period from when the replacement unit 32 began to be used exceeded the thrust operation period. In the image forming device of Comparative Example 3, the remaining period (Xr) at the date and time when the replacement unit 32 began to be used was shorter than the equivalent period of the usage guarantee (Xl'), so the slip-through evaluation was "X" and the unit warranty evaluation was "X". In other words, in Comparative Example 3, it was found that the quality of the replacement unit 32 cannot be maintained when the period since manufacture exceeds the equivalent period of the usage guarantee (Xl').

On the other hand, in Example 2, when the control unit 76 causes the image forming unit 30 to execute the image formation process, it causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the use of the replacement unit 32 started exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation. Therefore, in the image forming device of Example 1, the remaining period (Xr) at the date and time when the use of the replacement unit 32 started was shorter than the equivalent period of the usage guarantee (Xl'), but the drum scratch evaluation and slip-through evaluation were "good", and the unit warranty evaluation was "good". In other words, it was found that in Example 2, the quality of the replacement unit 32 can be maintained even if the period since manufacture exceeded the equivalent period of the usage guarantee (Xl').

In Comparative Example 4, the control unit 76 caused the thrust drive unit 70 to perform the thrust operation even if the period from when the replacement unit 32 began to be used exceeded the thrust operation period. In the image forming device of Comparative Example 3, the remaining period (Xr) was shorter than the equivalent period of the usage guarantee (Xl') at the date and time when the replacement unit 32 began to be used, so the drum scratch evaluation was "△", the slip-through evaluation was "×", and the unit warranty evaluation was "×". It is presumed that the drum scratch evaluation was "△" because the elapsed period (Xi) was long and the initial linear pressure was low. In other words, in Comparative Example 4, it was found that the quality of the replacement unit 32 cannot be maintained when the elapsed period after manufacture exceeds the equivalent period of the usage guarantee (Xl').

On the other hand, in Example 3, when the control unit 76 causes the image forming unit 30 to execute the image formation process, it causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the use of the replacement unit 32 started exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation. Therefore, in the image forming device of Example 1, the remaining period (Xr) at the date and time when the use of the replacement unit 32 started was shorter than the equivalent period of the usage guarantee (Xl'), but the drum scratch evaluation and slip-through evaluation were "good", and the unit warranty evaluation was "good". In other words, it was found that in Example 3, the quality of the replacement unit 32 can be maintained even if the period since manufacture exceeded the equivalent period of the usage guarantee (Xl').

In Comparative Example 5, the control unit 76 caused the thrust drive unit 70 to execute the thrust operation even if the period from when the replacement unit 32 began to be used exceeded the thrust operation period. In the image forming device of Comparative Example 3, the remaining period (Xr) at the date and time when the replacement unit 32 began to be used was shorter than the equivalent period of the usage guarantee (Xl'), so the slip-through evaluation was "X" and the unit warranty evaluation was "X". In other words, in Comparative Example 3, it was found that the quality of the replacement unit 32 cannot be maintained when the period since manufacture exceeds the equivalent period of the usage guarantee (Xl').

On the other hand, in Example 4, when the control unit 76 causes the image forming unit 30 to execute the image formation process, it causes the thrust drive unit 70 to execute the thrust operation. Furthermore, when the period from when the use of the replacement unit 32 started exceeds the thrust operation period, the control unit 76 does not cause the thrust drive unit 70 to execute the thrust operation. Therefore, in the image forming device of Example 1, the remaining period (Xr) at the date and time when the use of the replacement unit 32 started was shorter than the equivalent period of the usage guarantee (Xl'), but the drum scratch evaluation and slip-through evaluation were "good", and the unit warranty evaluation was "good". In other words, in Example 4, it was found that the quality of the replacement unit 32 can be maintained even if the period since manufacture exceeded the equivalent period of the usage guarantee (Xl').

As described with reference to Figures 1 to 10, the image forming device 1 includes a replacement unit 32, a thrust drive unit 70, a control unit 76, a reading unit 71, and a memory unit 75. The replacement unit 32 includes a photosensitive drum 61 and a cleaning blade 641. The control unit 76 calculates the elapsed period (Xi) from the manufacturing date and time of the replacement unit 32 to the date and time when the replacement unit 32 is attached to the image forming device 1 based on the manufacturing date and time information. The control unit 76 calculates the remaining period (Xr) until an image defect occurs based on the elapsed period (Xi). The control unit 76 determines whether the remaining period (Xr) is longer than the usage guarantee equivalent period (Xl'). When the control unit 76 determines that the remaining period (Xr) is not longer than the usage guarantee equivalent period (Xl'), it controls the thrust drive unit 70 so that the linear pressure of the cleaning blade 641 against the circumferential surface of the photosensitive drum 61 is increased at a timing that satisfies a predetermined condition. As a result, the blade line pressure is unlikely to fall below the minimum quality assurance line pressure (bmin) even if the date and time when the replacement unit 32 begins to be used lags behind the date and time of manufacture and the period since manufacture reaches the equivalent period of guaranteed use (Xl'). Therefore, the image forming device 1 can maintain the quality of the replacement unit 32 even if the date and time when the replacement unit 32 begins to be used lags behind the date and time of manufacture and the period since manufacture exceeds the equivalent period of guaranteed use.

As described with reference to Figures 1 to 10, when the control unit 76 determines that the remaining period (Xr) is not longer than the equivalent period of guaranteed use (Xl'), it controls the thrust drive unit 70 to stop driving the thrust operation at a timing that satisfies a predetermined condition. The blade line pressure when the thrust drive unit 70 is not driven is higher than when the thrust drive unit 70 is stopped. This allows the image forming device 1 to maintain the quality of the replacement unit 32 with a simple configuration.

As described with reference to Figures 1 to 10, the control unit 76 calculates the thrust operation period based on the remaining period (Xr). The timing at which the specified condition is satisfied includes the date and time at which the thrust operation period elapses from the date and time at which the replacement unit 32 is attached to the image forming device 1. In other words, the execution of the thrust operation is maintained until the elapsed time since manufacture reaches the upper usage limit period (Xf). As a result, the image forming device 1 can maintain the quality of the replacement unit 32.

As described with reference to Figures 1 to 10, the image forming device 1 includes a rotation drive unit 72 and a torque detection unit 73. The control unit 76 determines whether the torque is equal to or less than a predetermined value based on the output of the torque detection unit 73. The timing at which the predetermined condition is satisfied includes the timing at which the torque is equal to or less than the predetermined value. This allows the image forming device 1 to increase the blade linear pressure when the torque becomes high, even if the time since manufacture has not exceeded the usage guarantee equivalent period (Xl'). Therefore, the image forming device 1 can maintain the quality of the replacement unit 32.

The above describes the embodiments of the present invention with reference to Figures 1 to 10. However, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the gist of the present invention (for example, (1) to (7) shown below). The drawings are mainly schematic illustrations of the components for ease of understanding, and the thickness, length, number, etc. of each component shown in the drawings differ from the actual ones due to the convenience of creating the drawings. In addition, the materials, shapes, dimensions, etc. of each component shown in the above embodiments are merely examples and are not particularly limited, and various modifications are possible without substantially departing from the effects of the present invention.

(1) As described with reference to Figs. 1 to 10, in this embodiment, the control unit 76 increases the blade line pressure by stopping the driving of the thrust drive unit 70, but the present invention is not limited to this. For example, the control unit 76 may increase the blade line pressure by controlling the thrust drive unit 70 to change at least one of the thrust speed and the thrust period. The thrust speed indicates the relative movement distance of the photosensitive drum 61 and the cleaning blade 641 while the photosensitive drum 61 rotates once. The thrust period indicates, for example, the number of rotations of the photosensitive drum 61 while the photosensitive drum 61 makes one reciprocating movement against the cleaning blade 641 during the thrust operation.

(2) As described with reference to Figures 1 to 10, in this embodiment, the thrust stop timing includes the timing when the torque becomes equal to or less than a predetermined value, but the present invention is not limited to this. The thrust stop timing does not have to include the timing when the torque becomes equal to or less than a predetermined value.

(3) As described with reference to Figures 1 to 10, in this embodiment, the image forming device 1 includes a torque detection unit 73, but the present invention is not limited to this. The image forming device 1 does not have to include a torque detection unit 73.

(4) As described with reference to Figures 1 to 10, in this embodiment, the photoconductor is an organic photoconductor, but the present invention is not limited to this. For example, the photoconductor may be an inorganic photoconductor.

(5) As described with reference to Figures 1 to 10, in this embodiment, the image forming device 1 is a printer, but the present invention is not limited to this. For example, the image forming device 1 may be a multifunction device.

(6) As described with reference to Figures 1 to 10, in this embodiment, the image forming device 1 employs a roller charging method, but the present invention is not limited to this. For example, the image forming device 1 may employ a belt charging method, a non-contact charging method that utilizes the proximity discharge phenomenon, or a method of charging the photosensitive drum 61 by corona discharge (such as a scorotron method).

(7) As described with reference to FIGS. 1 to 10, in this embodiment, the charging bias is a DC voltage and does not include an AC voltage, but the present invention is not limited to this. For example, the charging bias may be a voltage in which an AC voltage is superimposed on a DC voltage.

The present invention can be used in the field of image forming devices.

1 image forming apparatus 32 replacement unit,
61 Photosensitive drum 641 Cleaning blade 70 First driving section 71 Reading section 75 Storage section 76 Control section D Rotational axis direction of photosensitive drum

Claims (3)

An image forming apparatus that prints an image on a sheet,
an image forming unit having an image carrier and a cleaning member that is in pressure contact with the image carrier;
a first drive unit that performs a thrust operation to relatively reciprocate the image carrier and the cleaning member along a rotation axis direction of the image carrier;
A control unit that controls the first driving unit;
a reading unit that reads manufacturing date and time information indicating a manufacturing date and time of the image forming unit from the image forming unit;
a storage unit that stores usage guarantee information indicating a period equivalent to a usage guarantee period (Xl) from the manufacturing date and time that guarantees the quality of the image forming unit,
The control unit is
Calculating an elapsed period (Xi) from the manufacturing date and time to the date and time when the image forming unit was installed in the image forming apparatus based on the manufacturing date and time information;
Calculating the remaining period (Xr) until an image defect occurs based on the elapsed period (Xi);
determining whether the remaining period (Xr) is longer than a period corresponding to the usage guarantee period (Xl);
the image forming apparatus, when it determines that the remaining period (Xr) is not longer than a period equivalent to the usage guarantee period (Xl), causes the first drive unit to perform at least one of stopping the thrust operation, changing the speed of the thrust operation, and changing the period of the thrust operation so that the line pressure of the cleaning member against the circumferential surface of the image carrier is increased at a timing when a specified condition is satisfied. the control unit calculates a thrust operation period indicating a period from the elapsed period (Xi) during which the first drive unit performs the thrust operation, based on the remaining period (Xr);
2 . The image forming apparatus according to claim 1 , wherein the timing at which the predetermined condition is satisfied includes a date and time at which the thrust operation period elapses from a date and time at which the image forming unit is attached to the image forming apparatus. a second drive unit that drives and rotates the image carrier;
a torque detection unit that detects a torque of the second drive unit when the image carrier is rotationally driven,
The control unit determines whether the torque is equal to or less than a predetermined value based on an output of the torque detection unit,
3. The image forming apparatus according to claim 1, wherein the timing at which the predetermined condition is satisfied includes a timing at which the torque becomes equal to or lower than the predetermined value.

Images