Fixing device and image forming apparatus

In a fixing device, a heating section is disposed opposite to an inner circumferential surface of a fixing belt. The heating section includes a heater, a heater holding member, a heat sensitive body disposed opposite to the heater on the heater holding member, a covering member disposed opposite to the heater holding member with the heat sensitive body therebetween, and an urging member disposed between the covering member and the heat sensitive body and urging the heat sensitive body in an urging direction. First and second restricting portions of the heater holding member restrict movement of the covering member in a direction opposite to the urging direction. In a state in which first and second engaging portions of the covering member respectively engage with the first and second restricting portions in a slidable manner in the urging direction, the urging member urges the heat sensitive body in the urging direction.

INCORPORATION BY REFERENCE

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2018-239761, filed on Dec. 21, 2018. The contents of this application are incorporated herein by reference in their entirety.

BACKGROUND

The present disclosure relates to a fixing device and an image forming apparatus.

A fixing device using a heating film has been known to be included in an electrographic image forming apparatus. One of such fixing devices includes a fixing assembly and a pressure roller that presses against the fixing assembly to form a fixing nip part. The fixing assembly includes a tubular fixing film, a heater in contact with an inner surface of the fixing film, a heat insulating holder that holds the heater, a metal frame stay that presses the heat insulating holder against the pressure roller, a thermistor, and a heat conduction member. The thermistor is provided on the heat insulating holder and in contact with the heat conduction member at a specific pressure through a through hole in the heat insulating holder. The thermal transmission member is held by the heat insulating holder between the heater and the heat insulating holder.

Each of the heater, the heat insulating holder, the metal frame stay, and the heat conduction member extends in a direction perpendicular to a recording medium conveyance direction. When the metal stay is attached to the heat insulating holder, the load of the metal stay is transmitted to the entirety of the heat insulating holder in the longitudinal direction of the heat insulating holder via pressure springs disposed at the opposite ends of the metal stay in the longitudinal direction of the metal stay. Heat accumulated in a paper non-passing area of the fixing nip part is transmitted to the thermistor via the heat conduction member. In the fixing device, an excessive increase in temperature of the paper non-passing area can be suppressed.

SUMMARY

A fixing device according to an aspect of the present disclosure includes a fixing belt and a heating section. The heating section is disposed opposite to an inner circumferential surface of the fixing belt. The heater includes: a heater that heats the fixing belt; a heater holding member that holds the heater; a heat sensitive body disposed on the heater holding member so as to be located opposite to the heater; a covering member disposed opposite to the heater holding member with the heat sensitive body therebetween; and an urging member that is disposed between the covering member and the heat sensitive body and that urges the heat sensitive body in an urging direction from the heat sensitive body toward the heater. The heater holding member includes a first restricting portion and a second restricting portion. Each of the first restricting portion and the second restricting portion restricts movement of the covering member in a direction opposite to the urging direction. The covering member includes a first engaging portion engaging with the first restricting portion and a second engaging portion engaging with the second restricting portion. In a state in which the first engaging portion and the second engaging portion respectively engage with the first restricting portion and the second restricting portion in a slidable manner in the urging direction, the urging member urges the heat sensitive body in the urging direction.

According to another aspect of the present disclosure, an image forming apparatus includes the above-described fixing device and an image forming section. The image forming section forms a toner image on a sheet. The fixing device fixes the toner image to the sheet.

DETAILED DESCRIPTION

The following describes embodiments of the present disclosure with reference to the accompanying drawings. Elements that are the same or equivalent are indicated by the same reference signs in the drawings, and description thereof is not repeated. In a three-dimensional rectangular coordinate system in the following embodiments, an X axis and a Y axis are parallel to a horizontal plane and a Z axis is parallel to a vertical direction. A direction of the Y axis is an example of a direction parallel to a “rotation axis” of a “pressure member” in the present disclosure.

An embodiment of a fixing device1according to the present disclosure will be described with reference toFIG. 1.FIG. 1is a cross-sectional view of the fixing device1. As illustrated inFIG. 1, the fixing device1includes a fixing belt10, a pressure member20, and a heating section30. The fixing device1is included for example in an electrographic image forming apparatus.

The fixing belt10is an endless belt. The pressure member20applies pressure to the fixing belt10while in contact with an outer circumferential surface of the fixing belt10, and rotates about a rotation axis L of the pressure member20. The pressure member20is for example a pressure roller.

The heating section30is disposed opposite to an inner circumferential surface of the fixing belt10. The heating section30includes a heater31, a heater holding member32, at least one heat sensitive body33, at least one covering member34, and at least one urging member35.

The heater31heats the fixing belt10. The heater31is planar in shape or in a slender thin plate-like shape. The heater31extends in a direction parallel to the rotation axis L of the pressure member20. The heater31is for example a ceramic heater and includes a ceramic substrate and a resistance heating element. The heater31has a thickness of 1 mm, for example.

The heat sensitive body33is located opposite to the heater31. The heat sensitive body33is disposed on the heater holding member32. The heat sensitive body33senses heat of the heater31. The heat sensitive body33detects a temperature of the heater31in the present embodiment.

The urging member35is disposed between the covering member34and the heat sensitive body33. The urging member35is for example a coil spring. The urging member35is for example in a cylindrical shape, a conical shape, or a barrel shape. The urging member35urges the heat sensitive body33in an urging direction D1. The urging direction D1is a direction from the heat sensitive body33toward the heater31.

The heater holding member32holes the heater31. The heater holding member32is disposed opposite to the fixing belt10with the heater31therebetween. The heater holding member32is for example made from a heat-resistant resin. The heater holding member32extends in a direction parallel to the rotation axis L of the pressure member20. The heater holding member32includes a first restricting portion32A and a second restricting portion32B. Each of the first restricting portion32A and the second restricting portion32B restricts movement of the covering member34in a direction D2opposite to the urging direction D1.

The covering member34is disposed opposite to the heater holding member with the heat sensitive body33therebetween. The covering member34includes a first engaging portion34A and a second engaging portion34B. The first engaging portion34A engages with the first restricting portion32A. The first engaging portion34A in a state of engaging with the first restricting portion32A is slidable on the first restricting portion32A in the urging direction D1. The second engaging portion34B engages with the second restricting portion32B. The second engaging portion34B in a state of engaging with the second restricting portion32B is slidable on the second restricting portion32B in the urging direction D1. In the following, a state in which the first engaging portion34A engages with the first restricting portion32A in a slidable manner in the urging direction D1and the second engaging portion34B engages with the second restricting portion32B in a slidable manner in the urging direction D1may be referred to simply as an “engaging state”. As a result of the first engaging portion34A and the second engaging portion34B being slidable in the engaging state, a user can push the covering member34to a further extent in the urging direction D1.

The urging member35in the engaging state urges the heat sensitive body33in the urging direction D1. As a result of the urging member35in the engaging state urging the heat sensitive body33, the heater holding member32provisionally secures the covering member34, the urging member35, and the heat sensitive body33on the heater31with the heat sensitive body33in contact with the heater31. Thus, such a simple configuration can inhibit displacement of the heat sensitive body33without need for the user to keep supporting the heat sensitive body33using the fingers in assembling the heating section30. Thus, the number of components can be reduced and convenience in assembly can be improved.

Operation and configuration of an image forming apparatus100including the fixing device1will be described next with reference toFIG. 2.FIG. 2is a diagram illustrating the image forming apparatus100. The image forming apparatus100is for example a copier, a printer, a facsimile machine, or a multifunction peripheral that implements functions of the aforementioned machines. The following describes an embodiment in which the image forming apparatus100is a monochrome multifunction peripheral.

As illustrated inFIG. 2, the image forming apparatus100includes a reading section3, a feeding section4, a conveyance section5, an image forming section2, the fixing device1, and an ejection section6.

The reading section3reads an image of a document G. The reading section3generates image data based on the read image. The feeding section4accommodates a plurality of sheets S and feeds the sheets S to the conveyance section5one at a time. Each of the sheets S is for example a sheet of paper or a sheet made from a synthetic resin. The conveyance section5includes a plurality of conveyance roller pairs and conveys the sheet S to the image forming section2.

The image forming section2electrographically forms a toner image on the sheet S. Specifically, the image forming section2includes a photosensitive drum, a charger, a light exposure device, a development device, a replenishment device, a transfer device, a cleaner, and a static eliminator. The toner image represents for example the image of the document G. The fixing device1fixes the toner image to the sheet S by applying heat and pressure to the toner image. The conveyance section5conveys the sheet S with the toner image fixed thereto to the ejection section6. The ejection section6ejects the sheet S out of the image forming apparatus100.

Each configuration of the heating section30and the fixing device1will be described next in detail with reference toFIGS. 3A and 3B.FIG. 3Ais a perspective view of the fixing device1. Note thatFIG. 3Aillustrates a state in which the fixing belt10is removed from the fixing device1.FIG. 3Bis a diagram illustrating the fixing device1. Note thatFIG. 3Bis simplified for the sake of easy viewing of the heating section30.

As illustrated inFIG. 3A, preferably, the heating section30further includes a reinforcing member36in addition to the heater31, the heater holding member32, the heat sensitive body33, the covering member34, and the urging member35described with reference toFIG. 1. The reinforcing member36reinforces the heater holding member32. The reinforcing member36is for example a slim and long metal stay. The reinforcing member36has two ends in a longitudinal direction thereof, one of which is a first end36B and the other of which is a second end36C.

The reinforcing member36includes a first side plate36D, a second side plate36E, and a top plate36A. The first and second side plates36D and36E each stand from the top plate36A. The first side plate36D is disposed opposite to the second side plate36E with the top plate36A therebetween. The reinforcing member36is overlaid with the heater holding member32in a longitudinal direction of the heater holding member32at a location opposite to the heater holding member32. The reinforcing member36extends in a direction parallel to the rotation axis L of the pressure member20.

One end of the two ends of the heater holding member32in the longitudinal direction thereof is referred to as a third end32F. The other end thereof is referred to as a fourth end32G. The third end32F functions as a connector receiving part. The connector receiving part is capable of receiving a connector of a main body of the image forming apparatus100. The third end32F is located opposite to the first end36B of the reinforcing member36. The fourth end32G is located opposite to the second end36C of the reinforcing member36.

The heat sensitive body33illustrated inFIG. 3Bincludes at least one of a thermal fuse, a thermostat, and a thermistor. The thermal fuse is a protection element such as a one-shot thermostat. The thermal fuse shuts off electric power supply to the heater31when the temperature of the heater31is equal to or higher than a first threshold. In particular, once the thermal fuse shuts off the electric power supply according to the temperature of the heater31, the electric power supply is not resumed. Therefore, accuracy in suspending heating of the fixing belt10by the heater31when the temperature of the heater31is excessively increased can be improved.

The thermostat shuts off the electric power supply to the heater31when the temperature of the heater31is equal to or higher than a second threshold, and causes the electric power supply to the heater31to be resumed when the temperature of the heater31becomes lower than the second threshold. In the above configuration, the heater31for heating the fixing belt10can be turned on and off with delicate accuracy corresponding to temperature change of the heater31.

The thermistor is a semiconductor element for measuring the temperature of the heater31. The image forming apparatus100controls the heater31according to the temperature measured by the thermistor. As a result of the heat sensitive body33being a thermistor, accuracy in controlling the temperature of the heater31can be improved. Note that the following embodiments describe a case in which the heat sensitive body33is a thermistor.

The reinforcing member36is in contact with the covering member34. Specifically, the reinforcing member36has substantially an inverted U-shape in cross section as viewed in a direction parallel to the rotation axis L. The top plate36A has a contact surface36A1. The contact surface36A1is in contact with the covering member34. The reinforcing member36in contact with the covering member34is secured at a location opposite to the heater holding member32with the covering member34therebetween. In the following, a “state in which the reinforcing member36and the heater holding member32are secured at a location opposite to each other” may be referred to as a “reinforcing member opposed state”.

In the reinforcing member opposed state, the urging member35urges the heat sensitive body33in the urging direction D1in a further extent. A pressure by an urging force of the urging member35in the reinforcing member opposed state is greater than a pressure by an urging force of the urging member35in the engaging state. That is, when the heating section30transitions from the engaging state to the reinforcing member opposed state, the covering member34is pushed in a further extent in the urging direction D1. The heat sensitive body33is accordingly in close contact with the heater31. In the above configuration, an ideal load of the heat sensitive body33can be caused to act on the heater31with a simple configuration. Thus, the number of components can be reduced and a load of the heat sensitive body33on the heater31can be stabilized with a simple configuration.

Preferably, the contact surface36A1of the top plate36A is a planar surface. As a result of the contact surface36A1being a planar surface, inclination of the contact surface36A1relative to the covering member34can be prevented in the contact surface36A1coming into contact with the covering member34. Thus, the covering member34is prevented from being inclined in assembly. In turn, convenience in assembly can be further improved.

The fixing device1further includes a belt holding member37and an unillustrated drive mechanism in addition to the fixing belt10, the pressure member20, and the heating section30described with reference toFIG. 1.

The fixing belt10is a flexible endless belt in a substantial tubular shape. The fixing belt10includes a plurality of layers. The fixing belt10includes for example a polyimide layer and a release layer disposed on the polyimide layer. The release layer is for example a heat-resistant film made from a fluororesin.

The pressure member20is columnar in shape. The pressure member20includes a columnar core bar21, a cylindrical elastic layer22, and a release layer23. The elastic layer22is disposed around the core bar21, and the release layer23covers a surface of the elastic layer22. The core bar21is for example made from stainless or aluminum. The elastic layer22is elastic and is made from for example a silicone rubber. The release layer23is made from for example a fluororesin.

The pressure member20is pressed against the heater31with the fixing belt10therebetween, thereby being in pressure contact with the fixing belt10. A nip part N is formed at a location where the pressure member20is in pressure contact with the fixing belt10. When the pressure member20is driven and rotate, the fixing belt10follows the rotation of the pressure member20to be rotated. When the sheet S passes through the nip part N through conveyance of the sheet S in a sheet conveyance direction D3, the toner image TN is melted and fixed to the sheet S.

The belt holding member37holds two ends of the fixing belt10in a width direction of the fixing belt10. Specifically, the belt holding member37includes a first belt holding portion37A and a second belt holding portion37B. The first belt holding portion37A holds an end of the fixing belt10that is located in correspondence with (close to) the first end36B of the reinforcing member36. The second belt holding portion37B holds an end of the fixing belt10that is located in correspondence with (close to) the second end36C of the reinforcing member36.

Furthermore, the belt holding member37secures the reinforcing member36to the heater holding member32. Specifically, the belt holding member37is fitted to the reinforcing member36and the heater holding member32in the state in which the reinforcing member36is located opposite to the heater holding member32. The first belt holding portion37A secures the first end36B of the reinforcing member36to the third end32F of the heater holding member32. The second belt holding p37B secures the second end36C of the reinforcing member36to the fourth end32G of the heater holding member32.

The drive mechanism drives and rotates the pressure member20. The drive mechanism includes for example a drive motor and a gear. The drive mechanism is connected to one of two ends of the core bar21of the pressure member20in a longitudinal direction of the pressure member20. The drive mechanism is disposed for example close to the second end36C of the first and second ends36B and36C of the reinforcing member36.

Detailed description of the engaging state and the configuration of the heating section30will continue with reference toFIGS. 4A to 5B.FIGS. 4A and 5Aare perspective views of the heating section30.FIGS. 4B and 5Bare cross-sectional views of the heating section30.FIG. 4Acorresponds toFIG. 4B.FIG. 5Acorresponds toFIG. 5B.FIGS. 4A and 4Beach illustrate a state in which the covering member34is detached and separate from the heater holding member32.

As illustrated inFIGS. 4A and 4B, the covering member34is for example a heat-resistant box-shaped member made from a resin. The covering member34extends in the longitudinal direction of the heater holding member32. The covering member34has a shape corresponding to the shape of the heat sensitive body33. Specifically, the covering member34includes a top wall34C, a first side wall34D, and a second side wall34E in addition to the first engaging portion34A and the second engaging portion34B described with reference toFIG. 1.

The top wall34C includes a protrusion34C1, a plurality of arms34C2, and an opposing surface34C3. The opposing surface34C3faces the heat sensitive body33. The protrusion34C1protrudes in the urging direction D1. That is, the protrusion34C1protrudes from the opposing surface34C3toward the heat sensitive body33. The protrusion34C1has a shape for example corresponding to the inner diameter of the coil spring.

Preferably, the urging member35is secured to the protrusion34C1. Posture stability of the urging member35can be improved in the urging member35urging the heat sensitive body33against the heater31in the reinforcing member opposed state. Accordingly, the urging member35can be prevented from being buckled. Thus, displacement of the urging member35relative to the heat sensitive body33can be inhibited and convenience in assembly can be further increased.

The arms34C2each protrude for example from the first side wall34D in parallel to the opposing surface34C3. The arms34C2hold for example various wirings.

The first side wall34D and the second side wall34E are disposed opposite to each other with the top wall34C therebetween. The first side wall34D and the second side wall34E extend in the longitudinal direction of the heater holding member32.

The first engaging portion34A and the second engaging portion34B are each in an L shape in cross section. Specifically, the first engaging portion34A connects the first side wall34D to the second side wall34E at one of the two ends in the longitudinal direction of the heater holding member32. The second engaging portion34B connects the first side wall34D to the second side wall34E at the other end thereof. The first engaging portion34A and the second engaging portion34B are disposed opposite to each other with the top wall34C therebetween. The first engaging portion34A has a shape corresponding to the shape of the first restricting portion32A of the heater holding member32. The second engaging portion34B has a shape corresponding to the shape of the second restricting portion32B of the heater holding member32. For example, each of the first engaging portion34A and the second engaging portion34B has a hook-like shape such as a substantial L shape in cross section as viewed in a direction parallel to a width direction of the heater holding member32and perpendicular to the rotation axis L.

The heater holding member32includes a bottom wall32C, a third side wall32D, and a fourth side wall32E in addition to the first restricting portion32A and the second restricting portion32B described with reference toFIG. 1. The third side wall32D and the fourth side wall32E each stand from the bottom wall32C. The third side wall32D is disposed opposite to the fourth side wall32E with the bottom wall32C therebetween.

The first restricting portion32A and the second restricting portion32B each protrude in an inverted L shape in cross section from the heater holding member32. Specifically, the first restricting portion32A and the second restricting portion32B are each disposed on the bottom wall32C. The first restricting portion32A has a shape corresponding to the shape of the first engaging portion34A of the covering member34. The second restricting portion32B has a shape corresponding to the shape of the second engaging portion34B of the covering member34. For example, the first restricting portion32A and the second restricting portion32B each have a hook-like shape such as a substantial inverted L shape in cross section as viewed in a direction along a plane parallel to the bottom wall32C and perpendicular to the rotation axis L. The first restricting portion32A is located opposite to the second restricting portion32B with the heat sensitive body33therebetween.

The heater holding member32has an opening32C1. The opening32C1has a shape corresponding to the shape of the heat sensitive body33, that is, the shape of a bottom portion33B of the heat sensitive body33, for example. The opening32C1is a rectangular in shape, for example.

The heat sensitive body33includes a main body portion33A and the bottom portion33B. A portion of the heat sensitive body33is inserted in the opening32C1of the bottom wall32C to be adjacent to the heater31. The portion of the heat sensitive body33is for example the bottom portion33B. The bottom portion33B protrudes from the main body portion33A in the urging direction D1. The bottom portion33B is inserted in the opening32C1of the heater holding member32.

FIGS. 5A and 5Billustrates the engaging state. As illustrated inFIGS. 5A and 5B, the covering member34is mounted on the heater holding member32for example in a snap-fit manner.

Specifically, the first engaging portion34A and the first restricting portion32A engage with each other. That is, a tip end in a hook-like shape of the first engaging portion34A is in contact with a tip end in a hook-like shape of the first restricting portion32A on a plane parallel to the bottom wall32C. The first restricting portion32A restricts movement of the first engaging portion34A in the direction D2opposite to the urging direction D1. The first engaging portion34A is slidable in the urging direction D1on the first restricting portion32A. A distance in which the first engaging portion34A is slidable is 1 mm, for example.

Furthermore, the second engaging portion34B and the second restricting portion32B engage with each other. That is, a tip end in a hook-like shape of the second engaging portion34B is in contact with a tip end in a hook-like shape of the second restricting portion32B on a plane parallel to the bottom wall32C. The second restricting portion32B restricts movement of the second engaging portion34B in the direction D2opposite to the urging direction D1. The second engaging portion34B is slidable in the urging direction D1on the second restricting portion32B. A distance in which the second engaging portion34B is slidable is 1 mm, for example.

The protrusion34C1is preferably disposed opposite to the heater31with the urging member35and the heat sensitive body33therebetween in a state in which the bottom portion33B of the heat sensitive body33is fitted in the opening32C1. Specifically, the urging member35is in contact with the main body33A of the heat sensitive body33above the opening32C1of the bottom wall32C. The urging member35urges the heat sensitive body33in the urging direction D1. In the above configuration, the bottom portion33B of the heat sensitive body33can be pressed against the heater31in an effective manner. Thus, convenience in assembly and accuracy in sensing the heat of the heater31can be improved.

As has been described with reference toFIGS. 4A to 5B, each of the first restricting portion32A and the second restricting portion32B protrudes in an inverted L shape in cross section from the heater holding member32. The first engaging portion34A and the second engaging portion34B are each in an L shape in cross section. Accordingly, the covering member34can be provisionally attached to the heater holding member32with a simple configuration such as in a snap-fit manner. Thus, the number of components can be reduced and convenience in assembly can be improved.

Detailed description of the reinforcing member opposed state will continue with reference toFIGS. 6A to 7B.FIGS. 6A and 7Aare perspective views of the heating section30.FIGS. 6B and 7Bare cross-sectional views of the heating section30.FIG. 6Acorresponds toFIG. 6B.FIG. 7Acorresponds toFIG. 7B.FIGS. 6A and 6Beach illustrate a state in which the reinforcing member36is detached and separate from the heater holding member32.

As illustrated inFIGS. 6A and 6B, the reinforcing member36extends in the longitudinal direction of the heater holding member32. The reinforcing member36is mounted on the heater holding member32in parallel to the heater holding member32to cover the covering member34that is in the engaging stated.

FIGS. 7A and 7Billustrate the reinforcing member opposed state. As illustrated inFIGS. 7A and 7B, the reinforcing member36is mounted on the heater holding member32in parallel to the heater holding member32. The reinforcing member36is secured to the heater holding member32while in contact with the covering member34at a location opposite to the heater holding member32with the covering member34therebetween. The contact surface36A1of the reinforcing member36is in contact with an end of the covering member34on a side in the direction D2opposite to the urging direction D1. For example, the contact surface36A1is in contact with the first side wall34D, the second side wall34E, and the arms34C2of the covering member34.

As a result of the reinforcing member36coming into contact with the covering member34, the urging member35urges the heat sensitive body33in the urging direction D1to a further extent. The first engaging portion34A slides in the urging direction D1on the first restricting portion32A to approach the heater31. The second engaging portion34B slides in the urging direction D1on the second restricting portion32B to approach the heater31. In other words, the reinforcing member36pushes the covering member34and the heating section30transitions from the engaging state to the reinforcing member opposed state. In the reinforcing member opposed state, engagement between the first engaging portion34A and the first restricting portion32A is released. Similarly, engagement between the second engaging portion34B and the second restricting portion32B is released in the reinforcing member opposed state.

Note that the number of heat sensitive bodies33may be plural as illustrated inFIG. 8.FIG. 8is a perspective view of the fixing device1. For the sake of easy viewing of arrangement of the heat sensitive bodies33, the fixing belt10, the reinforcing member36, the urging member35, the covering member34, and the heater holding member32are omitted inFIG. 8. The heat sensitive bodies33include first heat sensitive bodies33C and second heat sensitive bodies33D. Two first heat sensitive bodies33C are arranged on the heater31, for example. The first heat sensitive bodies33C are thermistors, for example. Two second heat sensitive bodies33D are arranged on the heater31, for example. The second heat sensitive bodies33D are thermal fuses, for example. The heat sensitive bodies33are arranged in a longitudinal direction of the heater31. The urging member35and the covering member34are arranged for each of the heat sensitive bodies33.

Embodiments of the present disclosure have been described so far with reference to the accompanying drawings. However, the present disclosure is not limited to the above-described embodiments and can be practiced in various ways within the scope without departing from the essence of the present disclosure. Elements of configuration disclosed in the above embodiments can be combined as appropriate in various different forms. For example, some of the elements of configuration may be omitted among all of the elements of configuration described in the embodiment. Alternatively or additionally, elements of configuration described in different embodiments may be combined as appropriate. The drawings are schematic illustrations that emphasize elements of configuration in order to facilitate understanding thereof, and the thickness, length, numbers, distance, and the like of each element of configuration illustrated in the drawings may differ from actual ones thereof in order to facilitate preparation of the drawings. The materials, shape, dimension, and so on of each element of configuration shown in the above-described embodiments are merely examples that do not impart any particular limitations and may be altered in various ways, so long as such alterations do not substantially deviate from the configuration of the present disclosure.

As described with reference toFIG. 2, the image forming apparatus100is a monochrome multifunction peripheral in the embodiments, which should not be taken to limit the present disclosure. The image forming apparatus100only need to be an electrographic image forming apparatus. For example, the image forming apparatus100may be a color multifunction peripheral.