Image forming apparatus

Abstract

To provide an image forming device allowing a user to easily attach / detach a belt unit to / from a device body.SOLUTION: A mounting part 105b on at least one end side in a belt width direction (X direction) of a sensor support member, which is the detection support member of a sensor unit as a detection unit, includes an engagement groove 115 to be engaged with a shaft 106a on one end side in the belt widthwise direction, penetrating from a roller support member of a counter roller. Further, the mounting part 105b on the one end side is attached to the device body so that it can move relative to the device body. The engagement groove 115 of the mounting part 105b on the one end side is opened in the downstream side in a direction (+Z direction) of removing a secondary transfer device, which is the belt unit, from the device body.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Conventionally, an image forming apparatus is known that includes a belt unit having a belt member stretched around a plurality of stretching rollers and a roller support member that rotatably supports the plurality of stretching rollers, and a detection unit having the following configuration. That is, the detection unit has a detection unit that is arranged to face a facing roller, which is one of the plurality of stretching rollers, via the belt member, and detects the state of the belt surface of the belt member or the state of a detection target on the belt surface, and a detection support member that supports the detection unit.

[0003] Patent Document 1 describes the above image forming apparatus in which one end of a meandering correction roller serving as the facing roller is rotatably supported by a swing plate serving as the roller support member, and the other end is rotatably supported by a fixed plate serving as the roller support member. Further, one end of a sensor support plate serving as the detection support member of the detection unit is attached to the swing plate, and the other end is attached to the fixed plate. By swinging the swing plate to move one end of the meandering correction roller in the swinging direction of the swing plate, the meandering correction roller is tilted, and the meandering of the belt is corrected. In addition, as one end of the sensor support plate moves in the swinging direction of the swing plate as the swing plate swings, the sensor support plate tilts in the same manner as the meandering correction roller. This describes that even when the meandering correction roller is tilted, the posture of the photosensor serving as the detection unit relative to the intermediate transfer belt serving as the belt member can be maintained.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, the detection unit is attached to the roller support member of the belt unit and is provided on the belt unit. Therefore, when attaching or detaching the belt unit to the device body, it is necessary to plug and unplug the connector of the detection means of the detection unit to the connector of the device body, which presents the problem that the belt unit cannot be easily attached to or detached from the device body. [Means for solving the problem]

[0005] To solve the above-mentioned problems, the present invention provides an image forming apparatus comprising: a belt unit having a belt member stretched over a plurality of tension rollers and a roller support member that rotatably supports the plurality of tension rollers; and a detection unit having detection means and a detection support member that support the detection means, which are positioned opposite to an opposing roller that is one of the plurality of tension rollers via the belt member, and which detect the state of the belt surface of the belt member or the state of an object to be detected on the belt surface, wherein the belt unit is configured to be detachably attached to the apparatus body in a direction perpendicular to the belt width direction of the belt member, both ends of the detection support member of the detection unit in the belt width direction are attached to the apparatus body, at least one end of the detection support member in the belt width direction is provided with an engagement groove that engages with the shaft on the one end in the belt width direction that penetrates the roller support member of the opposing roller, and is movably attached to the apparatus body, and the engagement groove is open on the downstream side in the direction of removing the belt unit from the apparatus body. Furthermore, one end of the detection support member in the belt width direction is attached to the device body so as to be movable in a direction perpendicular to the extraction direction. It is characterized by the following: [Effects of the Invention]

[0006] According to the present invention, the belt unit can be easily attached to and detached from the main body of the device. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of an electrophotographic color printer as an image forming apparatus according to this embodiment. [Figure 2]Schematic diagram of the secondary transfer apparatus. [Figure 3] A diagram illustrating the configuration of the mounting portion at one end of the sensor support member. [Figure 4] A perspective view showing the orientation of the adhesion amount detection sensor when the opposing roller is tilted. [Figure 5] A diagram illustrating how the shafts of opposing rollers are inserted into the engagement grooves. [Figure 6] This diagram shows a modified example of the mounting section at one end. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram of an electrophotographic color printer (hereinafter referred to as "printer") as an image forming apparatus according to the embodiment. This printer 100 is equipped with four image forming units 1Y, 1M, 1C, and 1K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. It is also equipped with a transfer unit 30 as an intermediate transfer device, a secondary transfer device 40, a cassette 60 for storing the recording material P as the material to be transported, and a fixing device 90.

[0009] The four image forming units 1Y, 1M, 1C, and 1K, which constitute the image forming section, use toners of different colors, Y, M, C, and K, as powder developers. Otherwise, they have the same configuration. Each image forming unit 1Y, 1M, 1C, and 1K is equipped with a drum-shaped photoreceptor 2Y, 2M, 2C, and 2K that serves as the image carrier, drum cleaning devices 3Y, 3M, 3C, and 3K, static eliminator, charging devices 6Y, 6M, 6C, and 6K, and developing devices 8Y, 8M, 8C, and 8K, etc.

[0010] The surfaces of the photoreceptors 2Y, 2M, 2C, and 2K are uniformly charged by the charging devices 6Y, 6M, 6C, and 6K. Next, electrostatic latent images for each color are formed by optical scanning with exposure light, such as laser light, emitted from the optical writing unit 101 located above the image forming units 1Y, 1M, 1C, and 1K. These electrostatic latent images are developed by the developing devices 8Y, 8M, 8C, and 8K, which have toners of each color, to form toner images T for each color. Toner images are formed on the photoreceptor 2. The toner images T of the photoreceptors 2Y, 2M, 2C, and 2K are primary transferred and supported on the surface of the intermediate transfer belt 31, which is made of an endless belt member.

[0011] Below the image forming units 1Y, 1M, 1C, and 1K, a transfer unit 30 is provided, which is an intermediate transfer device that moves endlessly (rotates) in a clockwise direction in the figure while tensioning an intermediate transfer belt 31. In this embodiment, the surface movement direction of the intermediate transfer belt 31 is defined as the belt movement direction a.

[0012] The transfer unit 30 includes, in addition to the intermediate transfer belt 31, a drive roller 32, a secondary transfer back roller 33, a cleaning backup roller 34, four primary transfer rollers 35Y, 35M, 35C, and 35K, and a pre-transfer roller 37. The intermediate transfer belt 31 is wrapped around and supported by the drive roller 32, the secondary transfer back roller 33, the cleaning backup roller 34, the primary transfer rollers 35Y, 35M, 35C, and 35K, and the pre-transfer roller 37, and is stretched taut. The intermediate transfer belt 31 is then transported by the rotational force of the drive roller 32, which is rotated clockwise in the figure by a driving means such as a drive motor, moving endlessly in the same direction.

[0013] Below the loop outside the intermediate transfer belt 31, a secondary transfer device 40 is positioned, which includes a secondary transfer belt 102 that is a belt member and a transfer belt. The secondary transfer belt 102 is wrapped around a plurality of tension rollers, including a secondary transfer roller 41. The secondary transfer device 40 includes a cleaning member 42 for cleaning the surface of the secondary transfer belt 102. In addition, an adhesion amount detection sensor 104, which is a reflective optical sensor, is positioned opposite one of the tension rollers, an opposing roller 106, via the secondary transfer belt 102.

[0014] Below the secondary transfer device 40, a cassette 60 is provided, which serves as a storage section capable of accommodating multiple stacks of recording material P. The cassette 60 has a roller 60a in contact with the topmost recording material P in the stack, and by rotating this roller at a predetermined timing, the recording material P is fed from the cassette 60 towards the transport path 65 leading to the secondary transfer nip N2. The recording material P fed into the transport path 65 is then sent to the secondary transfer nip N2 by a pair of registration rollers 61 at a timing synchronized with the toner image on the front surface of the intermediate transfer belt 31 within the secondary transfer nip N2.

[0015] The toner image on the front surface of the intermediate transfer belt 31 is transferred in one go onto the recording material P by the secondary transfer nip N2 due to the action of the secondary transfer electric field and nip pressure, and combined with the white color of the recording material P, it becomes a full-color toner image.

[0016] A fuser 90 is located downstream of the secondary transfer nip N2 in the recording material transport direction b. The fuser 90 includes a heating roller 91, a fuser roller 93, a support roller 96, and a tension roller 95, which also serves as a tension member, as support rollers for the fuser belt 94. The fuser 90 also includes a pressure roller 92 that contacts the fuser roller 93 while sandwiching the fuser belt 94. The recording material P onto which the toner image has been transferred is fed into the fuser 90 and sandwiched between the fuser nip, where the fuser roller 93 and the pressure roller 92 come into contact. The fuser 90 applies pressure to the nip and transfers heat to the recording material P via the fuser belt 94 from the heating roller 91, which has a heat source inside, softening and fixing the toner in the full-color toner image. After fixing, the recording material P is discharged from inside the fuser 90 and out of the machine.

[0017] Figure 2 is a schematic diagram of the secondary transfer apparatus 40. In the following description, the belt width direction of the secondary transfer belt 102 is described as the X direction, the direction in which the adhesion amount detection sensor 104 faces the opposing roller 106 is described as the Y direction, and the direction perpendicular to all three directions (X and Y) is described as the Z direction. In this embodiment, the Z direction is the vertical direction. The secondary transfer device 40, which is a belt unit, has a pair of roller support plates 109a and 109b, which are roller support members that rotatably support a plurality of tension rollers that tension the secondary transfer belt 102. The secondary transfer device 40 is supported by a pull-out housing 103, which is a support housing that can be pulled out in the X direction (belt width direction) relative to the main body of the device.

[0018] Positioning sections 107 and 108 for positioning the secondary transfer device 40 are provided on both side plates 103a and 103b of the drawer housing 103. Positioning section 108 on one end in the X direction is a secondary reference for positioning, and positioning section 107 on the other end in the X direction is a primary reference for positioning.

[0019] The positioning portion 107 on the other end side in the X direction, which is the main reference for positioning, has an insertion hole into which the other end of the shaft 106a of the opposing roller 106 is inserted. The inner diameter of this insertion hole is slightly larger than the outer diameter of the shaft 106a of the opposing roller 106, and by inserting the other end of the shaft 106a of the opposing roller 106 into the insertion hole of the positioning portion 107 on the other end side, the other end side of the secondary transfer device 40 is positioned in the Y direction and the Z direction.

[0020] The positioning portion 108 on one end side, which is the secondary reference for positioning, has a groove shape that is open upward in the vertical direction. By fitting one end of the shaft 106a of the opposing roller 106 into the positioning portion 108 on this one end side, one end side of the secondary transfer device 40 is positioned in the Y direction.

[0021] Further, the upper portions (+Z direction) of both side plates 103a and 103b of the drawer housing 103 are provided with support portions 123 that support the shaft 41a of the secondary transfer roller 41. The secondary transfer device 40 is supported by the drawer housing 103 via these support portions 123 and the positioning portions 107 and 108 on both sides in the belt width direction.

[0022] The positioning portion 107 on the other end side in the belt width direction is attached to the side plate 103b on the other end side of the drawer housing 103 so as to be slidable in the X direction. By sliding the positioning portion 107 on the other end side in the -X direction, the positioning support with the shaft 106a of the opposing roller 106 is released. By releasing the positioning support, the secondary transfer device 40 becomes attachable to and detachable from the drawer housing 103 in the Z direction (vertical direction).

[0023] A sensor unit 110, consisting of a detection means, an adhesion amount detection sensor 104, and a detection support member, a sensor support member 105, is attached to the drawer housing 103. The adhesion amount detection sensor 104, which is positioned opposite the opposing roller 106 via the secondary transfer belt 102, has detection parts 104a located in the center in the X direction (belt width direction) and at both ends. The adhesion amount detection sensor 104 also has a sensor substrate 104b to which these detection parts 104a are attached. Each detection part 104a has a light-emitting element and a light-receiving element, and the adhesion amount detection sensor 104 is positioned on the device body in such a manner that the light from the light-emitting element is directed towards the rotation center of the opposing roller 106.

[0024] Each detection unit 104a receives reflected light from the detection pattern, which is a toner image and is the object to be detected, that has been secondarily transferred from the intermediate transfer belt 31 to the secondary transfer belt 102, and outputs a voltage corresponding to the amount of toner deposited on the detection pattern (image density). The printer's control unit detects the amount of toner deposited on the detection pattern (image density) based on the output voltage of these detection units 104a, and adjusts the image formation conditions, such as exposure conditions, to achieve a predetermined image density based on the detection result. Thus, in this embodiment, the secondary transfer belt 102 functions as a toner image carrier that carries the detection pattern as a toner image.

[0025] Furthermore, the system detects image skew based on the difference in detection timing of the detection patterns by each detection unit 104a, and controls the skew correction mechanism of the optical writing unit 101 to correct the image skew.

[0026] The sensor support member 105 extends in the X direction (belt width direction) and has a sensor mounting portion 105a to which the adhesion amount detection sensor 104 is attached. In addition, mounting portions 105b and 105c extend from both ends of the sensor mounting portion 105a in the X direction toward the secondary transfer device 40 side (+Y direction). The mounting portion 105c on the other end in the belt width direction on the lower side of the figure is fixed to the other end side plate 103b of the drawer housing 103 by a screw 120 so as not to move. On the other hand, the mounting portion 105b on one end is fixed to the one end side plate 103a so as to be movable relative to the one end side plate 103a.

[0027] Figure 3 is a diagram illustrating the configuration of the mounting portion 105b on one end of the sensor support member 105. Figures 3(a) and 3(c) show the state when the opposing roller 106 is not tilted, and Figure 3(b) shows the state when the opposing roller 106 is tilted in the Z direction (vertical direction) and the Y direction (direction opposite the secondary transfer belt 102 of the adhesion amount detection sensor 104). The mounting portion 105b on one end in the belt width direction has an elongated support hole 105d that is long in the Y direction. A support projection 113 extending from the side plate 103a on one end of the drawer housing 103 passes through this support hole 105d. In addition, the other end of a spring 116, which is a biasing member and whose one end is fixed to the side plate 103a on one end of the drawer housing 103, is attached to the tip of the mounting portion 105b on one end. As a result, one end of the sensor support member 105 is attached to the drawer housing 103 so that it can move relative to the side plate 103a on one end within a predetermined range in the Y direction and rotate relative to it around the X axis, by means of the support projection 113 and the spring 116.

[0028] Furthermore, the sensor mounting portion 105a of the sensor support member 105 is a long, plate-like shape with its thickness in the Y direction and elongated in the X direction, and is capable of torsional elastic deformation around the X axis. Also, because the sensor support member 105 has this shape, it is also possible for the sensor support member 105 to be elastically deformed so that the sensor mounting portion 105a tilts in the Y direction, using the other end of the sensor mounting portion 105a as a pivot point. In addition, the adhesion amount detection sensor 104 held by the sensor mounting portion 105a is mainly composed of a sensor substrate 104b that is elongated in the belt width direction, and is attached to the sensor mounting portion 105a such that the thickness direction of the sensor substrate 104b is in the Y direction. Therefore, the adhesion amount detection sensor 104 is also capable of torsional elastic deformation around the X axis.

[0029] An engagement groove 115 is provided at the tip of the mounting portion 105b on one end of the sensor support member 105, with its vertically upward opening. One end of the shaft 106a of the opposing roller 106, which is exposed to the outside of the secondary transfer device 40 by passing through the roller support plate 109a, engages with this engagement groove 115. Furthermore, the tip of the mounting portion 105b on one end is biased vertically upward (+Z direction) by a spring 116. Due to the biasing force of this spring 116, the engagement groove 115 presses against the shaft 106a of the opposing roller 106 from below. The biasing force of this spring 116 is greater than the force required to torsionally deform the sensor mounting portion 105a. As a result, when the shaft 106a on one end of the opposing roller 106 is displaced vertically upward, the sensor mounting portion 105a is torsionally deformed around the X axis, causing the engagement groove 115 to follow the shaft 106a.

[0030] As shown in Figure 4, due to manufacturing errors or other factors, one end of the secondary transfer device 40 mounted on the main body of the device may twist relative to the other end in the direction of arrow a in the figure. In this case, the opposing roller 106 will tilt in the Z and Y directions. When the opposing roller 106 tilts in the Y direction, the distance between the adhesion amount detection sensor 104 and the secondary transfer belt 102 will not be uniform in the X direction (belt width direction), which may reduce the accuracy of the detection result of the adhesion amount detection sensor 104. Also, when the opposing roller 106 tilts in the Z direction, the orientation of the adhesion amount detection sensor 104 relative to the secondary transfer belt 102 will differ in the X direction, and among the multiple detection units 104a, there will be some in which the light from the light-emitting element does not point towards the rotation center of the opposing roller 106. As a result, there will be detection units 104a in which the incident angle of the light from the light-emitting element on the surface of the secondary transfer belt in the direction of belt movement deviates from the target incident angle, which may reduce the accuracy of the detection result of the adhesion amount detection sensor 104.

[0031] In this embodiment, when the opposing roller 106 tilts in the Y direction, and one end of the opposing roller 106 is displaced by α mm in the Y direction relative to the other end, as shown in Figure 3(b), the sensor support member 105 can tilt in accordance with the opposing roller 106 as follows. That is, since the engagement groove 115 of the mounting portion 105b on one end of the sensor support member 105 is engaged with the shaft 106a of the opposing roller 106, the engagement groove 115 tends to displace by α mm in the Y direction together with the shaft 106a. The mounting portion 105b on one end of the sensor support member 105 is movable in the Y direction relative to the side plate 103a on one end of the drawer housing 103. As a result, the engagement groove 115 moves by α mm in the Y direction, following the one end of the opposing roller 106. At this time, the sensor support member 105 elastically deforms with the other end of the sensor mounting portion 105a as the pivot point, and the sensor mounting portion 105a tilts in the Y direction in accordance with the opposing roller 106. As a result, one end of the adhesion amount detection sensor 104 attached to the sensor mounting section 105a is shifted by α mm relative to the other end in the direction of arrow b in Figure 4, causing the adhesion amount detection sensor 104 to tilt in accordance with the opposing roller 106. As a result, the distance between each detection section 104a and the secondary transfer belt 102 can be kept constant.

[0032] Furthermore, when the opposing roller 106 tilts in the Z direction, and one end of the opposing roller 106 is displaced by β mm in the Z direction relative to the other end, as shown in Figure 3(b), the adhesion amount detection sensor 104 twists around the X axis together with the sensor support member 105, as shown by arrow c in Figure 4. That is, when the engagement groove 115, which engages with the shaft 106a of the opposing roller 106, is displaced by β mm in the Z direction, the mounting portion 105b on one end rotates in the direction of arrow γ in Figure 3(b), pivoting on the support projection 113. At this time, the sensor substrate 104b of the adhesion amount detection sensor 104 undergoes torsional elastic deformation around the X axis together with the sensor mounting portion 105a. This suppresses changes in the posture of each detection portion 104a of the adhesion amount detection sensor 104 relative to the secondary transfer belt 102. As a result, it is possible to suppress the light from the light-emitting elements of each detection unit 104a from being directed away from the rotation center of the opposing roller 106, and to suppress the incident angle of the light from the light-emitting elements on the belt surface from deviating from the target incident angle.

[0033] Thus, in this embodiment, even if the opposing roller 106 is tilted in the Y and Z directions due to manufacturing errors or the like, the accuracy of the detection result of the adhesion amount detection sensor 104 can be maintained.

[0034] Furthermore, in this embodiment, the sensor unit 110 is attached to the drawer housing 103 of the main body of the device. In addition, the upper vertical part of the engagement groove 115 is opened, and one end of the shaft 106a of the opposing roller 106 is moved vertically upward (+Z direction), thereby disengaging the engagement between the engagement groove 115 and the shaft 106a. With this configuration, the sensor unit 110 can remain in the main body of the device (drawer housing 103), while only the secondary transfer device 40 can be attached to and detached from the main body of the device.

[0035] Specifically, when removing the secondary transfer device 40 from the main device body, first, the drawer housing 103 is pulled out from the main device body. Next, the positioning part 107 on the other end is slid to release the positioning support between the opposing roller 106 and the shaft 106a. This removes any restriction on the vertical upward movement of the secondary transfer device 40. Therefore, by moving the secondary transfer device 40 vertically upward, the secondary transfer device 40 can be removed from the main device body while the sensor unit 110 remains in the main device body.

[0036] When the sensor unit 110 is installed in the secondary transfer device 40, it is necessary to disconnect the connector that electrically connects the adhesion amount detection sensor 104 to the device body when removing the secondary transfer device 40 from the device body (drawer housing 103), resulting in poor workability for attaching and detaching the secondary transfer device 40. In addition, installing the sensor unit 110 in the secondary transfer device 40 increases the cost of the secondary transfer device 40, leading to higher replacement costs and increased maintenance costs. Furthermore, when reusing the secondary transfer device 40, the sensor unit 110 must be removed, which is an additional inconvenience.

[0037] In contrast, in this embodiment, the sensor unit 110 can be left in the main body of the device, and only the secondary transfer device 40 can be removed from the main body of the device (drawer housing 103). As a result, when removing the secondary transfer device 40 from the main body of the device, it is not necessary to disconnect the connector that electrically connects the adhesion amount detection sensor 104 to the main body of the device, and the secondary transfer device 40 can be easily removed from the main body of the device. Furthermore, after the secondary transfer device 40 is installed in the main body of the device, it is not necessary to connect the connector of the adhesion amount detection sensor 104 to the connector of the main body of the device, thus improving the ease of installation of the secondary transfer device 40.

[0038] Furthermore, compared to a configuration in which the sensor unit 110 is provided in the secondary transfer device 40, the cost of the secondary transfer device 40 can be reduced, the replacement cost of the secondary transfer device 40 can be made cheaper, and maintenance costs can be lowered. In addition, the effort required to reuse the secondary transfer device 40 can be reduced.

[0039] Furthermore, in this embodiment, since the upper vertical portion of the engagement groove 115 is open, it is unnecessary to perform the work of disengaging the engagement between the engagement groove 115 and the opposing roller 106 when removing the secondary transfer device 40 from the main body of the device. This makes it easy to remove the secondary transfer device 40 from the main body of the device.

[0040] Furthermore, in this embodiment, as shown in Figure 3(a), the engagement groove 115 has a tapered section 115a on the opening side that serves as a guide, with the opening widening as it goes vertically upward. As a result, as shown in Figure 5, when the secondary transfer device 40 is mounted on the device body (drawer housing 103), the shaft 106a of the opposing roller 106 can be guided into the engagement groove 115 by the tapered section 115a. This makes it easy to engage the shaft 106a of the opposing roller 106 with the engagement groove 115, and the secondary transfer device 40 can be easily mounted on the device body.

[0041] As shown in Figure 2, in this embodiment, the mounting portion 105c on the other end of the sensor support member 105 of the sensor unit 110 is fixed to the other end side plate 103b, which is a member that positions the other end of the opposing roller 106 in the belt width direction in the Y and Z directions. As a result, the other end of the adhesion amount detection sensor 104 can be positioned accurately at the target position relative to the secondary transfer belt 102.

[0042] Furthermore, as shown in Figure 2, one end of the opposing roller 106 in the belt width direction is positioned in the Y direction by the positioning part 108 on the other end. Therefore, the tilt of the opposing roller 106 in the Y direction is small, and depending on the target detection accuracy, the tilt of the opposing roller 106 in the Y direction may be ignored. In this case, as shown in Figure 6(a), the supported hole 105d through which the support projection 113 passes may be made into a round hole, and the mounting part 105b on one end may be configured to be rotatable relative to the pull-out housing 103 only around the X axis in the figure.

[0043] Furthermore, as shown in Figure 6(b), the plate-shaped sensor mounting portion 105a may be provided perpendicular to the Z direction (vertical direction), the supported hole 105d may be made into a long elongated hole in the vertical direction, and the mounting portion 105b at one end may be configured to be movable relative to the side plate 103b in the vertical direction. In such a configuration, when the opposing roller 106 is tilted in the Z direction, the sensor support member 105 elastically deforms with the other end of the sensor mounting portion 105a in the belt width direction as the pivot point, and the sensor mounting portion 105a can be tilted in the Z direction to follow the opposing roller 106. As a result, even if the opposing roller 106 is tilted in the Z direction, the light from the light-emitting element of each detection unit 104a can be directed towards the rotation center O1 of the opposing roller 106, and the incident angle of the light from the light-emitting element on the belt surface can be prevented from deviating from the target incident angle.

[0044] Furthermore, if the other end of the opposing roller 106 is not positioned, it is preferable to have the mounting portion 105c on the other end of the sensor support member 105 configured in the same way as the mounting portion 105b on the one end shown in Figure 3.

[0045] Furthermore, in this embodiment, the adhesion amount detection sensor 104 is positioned opposite the secondary transfer belt 102, but the adhesion amount detection sensor 104 may also be positioned opposite the intermediate transfer belt 31. By configuring the sensor support member of the sensor unit in which the adhesion amount detection sensor 104 is positioned opposite the intermediate transfer belt 31 as described above, the amount of toner adhering to the detection pattern on the intermediate transfer belt 31 can be detected with high accuracy. In addition, the transfer unit 30, which functions as an intermediate transfer device, can be removed from the main body of the device while leaving the sensor unit in the main body.

[0046] Furthermore, the detection means of the sensor unit 110 may be a surface detection sensor that detects the state of the belt surface, or a temperature sensor that detects the belt surface temperature as the state of the belt surface. Therefore, for example, the present invention can also be applied to a temperature detection unit that detects the temperature of the fixing belt 94. By applying the present invention to a temperature detection unit that detects the temperature of the fixing belt 94, it becomes possible to accurately detect the temperature of the fixing belt in the belt width direction. In addition, it becomes possible to attach and detach the fixing belt unit while the temperature detection unit remains in the fixing device.

[0047] The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) A belt unit such as a secondary transfer device 40 has a belt member such as a secondary transfer belt 102 stretched over multiple tension rollers and roller support members such as roller support plates 109a, 109b that rotatably support the multiple tension rollers, and a sensor unit which has detection means such as a toner adhesion detection sensor 104 that is positioned opposite to one of the multiple tension rollers, an opposing roller 106, via the belt member, and detects the state of the belt surface of the belt member or the amount of toner adhered to an object to be detected, such as a detection pattern on the belt surface, and a detection support member such as a sensor support member 105 that supports the detection means. In an image forming apparatus equipped with a detection unit such as T110, the belt unit is configured to be detachably attached to the apparatus body in a direction perpendicular to the belt width direction of the belt member, and both ends of the detection support member of the detection unit in the belt width direction are attached to the apparatus body, and at least one end of the detection support member in the belt width direction is provided with an engagement groove 115 that engages with the shaft on the one end in the belt width direction that penetrates from the roller support member of the opposing roller 106, and is movably attached to the apparatus body, and the engagement groove 115 is open on the downstream side in the direction of removing the belt unit from the apparatus body. According to Embodiment 1, the following configuration makes it possible to suppress the displacement of the detection means's orientation relative to the belt member even when the opposing roller is tilted. Specifically, an engagement groove is provided on at least one end of the detection support member in the belt width direction, which engages with the axis on one end of the opposing roller in the belt width direction, and at least one end of the detection support member in the belt width direction is attached to the device body so as to be movable relative to the device body. In this way, since one end of the detection support member in the belt width direction is attached to the device body so as to be movable relative to the device body, when the opposing roller is tilted and the position of the axis on one end of the opposing roller is displaced relative to the position of the axis on the other end, the engaging groove moves in the direction of the displacement on the one end. As a result, the detection support member tilts in the same way as the opposing roller, and the orientation of the detection means relative to the belt member can be maintained. Therefore, it is possible to suppress differences in the distance from the detection means to the belt surface in the belt width direction, and differences in the angle of incidence of light emitted from the detection means to the belt surface in the belt width direction, and to detect the state of the object to be detected, such as the state of the belt surface of the belt member or the detection pattern on the belt surface, in an accurate manner. Furthermore, in Embodiment 1, the detection unit is attached to the main body of the device, and the downstream side of the engagement groove in the direction from which the belt unit is removed from the main body of the device is open. Therefore, by moving the belt unit in the direction from which it is removed from the main body of the device, the engagement between the engagement groove and the shaft on one end of the opposing roller is released, and the belt unit can be attached to and detached from the main body of the device while the detection unit remains attached to the main body of the device. As a result, when attaching or detaching the belt unit to and from the main body of the device, it is not necessary to plug and unplug the connector of the detection means of the detection unit to the connector of the main body of the device, and the belt unit can be easily attached to and detached from the main body of the device.

[0048] (Aspect 2) In Embodiment 1, at least one end of a detection support member, such as a sensor support member 105, in the belt width direction is attached to the device body so as to be movable in the direction opposite to the opposing roller 106 of the detection means, such as an adhesion amount detection sensor 104, and so as to be rotatable around the belt width direction. The detection support member extends in the belt width direction and has a detection mounting portion, such as a sensor mounting portion 105a, to which the detection means, such as the adhesion amount detection sensor 104, is attached, and the detection mounting portion is torsionally elastically deformable around the belt width direction. According to this, as described in the embodiment, when the opposing roller 106 tilts in the opposing direction (Y direction), one end of the detection support member, such as the sensor support member 105, moves in the opposing direction according to the amount of positional displacement of one end of the opposing roller relative to the other end. As a result, the detection support member tilts in the opposing direction following the opposing roller, and it is possible to suppress the difference in the distance between the detection means and the belt member in the belt width direction. Furthermore, when the opposing roller 106 tilts in a direction (Z direction) perpendicular to both the opposing direction (Y direction) and the belt width direction, the detection mounting portion of the detection support member, such as the sensor mounting portion 105a, undergoes torsional elastic deformation around the belt width direction. This allows the orientation of the detection means supported by the detection support member to be maintained at each position in the belt width direction such that a line drawn perpendicularly from the center of the opposing surface facing the belt surface passes through the rotation center O1 of the opposing roller. This prevents the angle of incidence of light from the detection means onto the belt surface from deviating from the target angle of incidence, and enables good detection of the surface condition of the belt member or the amount of toner adhering to the object to be detected, such as a detection pattern on the belt surface. As a result, regardless of how the opposing roller 106 is tilted, the surface condition of the belt member or the amount of toner adhering to the object to be detected, such as the detection pattern on the belt surface, can be detected accurately.

[0049] (Aspect 3) In embodiment 1 or 2, the engagement groove 115 is provided with a biasing member such as a spring 116 that biases it in the removal direction. According to this, as described in the embodiment, even if one end of the opposing roller 106 is misaligned relative to the other end in the direction of removing the belt unit such as the secondary transfer device 40, the biasing force of the biasing member such as the spring 116 can cause the engagement groove 115 to follow the misalignment direction of one end of the opposing roller 106. This prevents the shaft of the opposing roller from coming out of the engagement groove 115, and also makes it possible to change the posture of the detection means according to the inclination of the opposing roller in the direction of attachment and detachment of the belt unit, thereby enabling accurate detection of the surface condition of the belt member or the amount of toner adhering to the object to be detected, such as the detection pattern on the belt surface.

[0050] (Aspect 4) In any of embodiments 1 to 3, the axis of the other end of the opposing roller 106 in the belt width direction passes through a roller support member such as a roller support plate 109a and is positioned on the device body in the direction of opposition (Y direction) and removal (Z direction) of the detection means to the opposing roller, and the other end of the detection support member in the belt width direction is fixed to the device body. According to this, as described in the embodiment, by positioning the axis of the other end of the opposing roller 106 in the belt width direction in the opposing direction (Y direction) and the removal direction (Z direction), the other end does not shift position in the opposing direction (Y direction) and the removal direction (Z direction). Therefore, by fixing the other end of the detection support member in the belt width direction to the device body, the distance of the detection means from the belt surface to the other end in the belt width direction can be maintained at the target distance, and the attitude of the other end of the detection means relative to the belt member can be maintained at the target attitude.

[0051] (Aspect 5) In any of embodiments 1 to 4, the detection support member, such as the sensor support member 105, has a guide portion, such as a tapered portion 115a, that guides the shaft of the opposing roller 106 into the engagement groove 115. According to this, as described in the embodiment, the shaft 106a of the opposing roller 106 can be easily engaged with the engagement groove 115, and the belt unit such as the secondary transfer device 40 can be easily attached to the device body.

[0052] (Aspect 6) In any of embodiments 1 to 5, the belt member is an image-carrying belt that carries a toner image, and the detection means detects the toner image on the image-carrying belt. According to this, as described in the embodiment, the toner image can be detected with high accuracy.

[0053] (Aspect 7) In embodiment 6, the image-carrying belt is an intermediate transfer belt on which the toner image is transferred. According to this method, the toner image on the intermediate transfer belt can be detected with high accuracy.

[0054] (Pattern 8) In embodiment 6, the image-carrying belt is a secondary transfer belt. According to this, toner images such as detection patterns supported on the secondary transfer belt can be detected with high accuracy. [Explanation of symbols]

[0055] 30: Transfer Unit 31: Intermediate transfer belt 40: Secondary transfer device 41: Secondary transfer roller 41a: Shaft of the secondary transfer roller 42: Cleaning parts 100: Printer 102: Secondary transfer belt 103: Drawer enclosure 103a: Side plate on one end 103b: Side plate on the other end 104: Adhesion amount detection sensor 104a: Detection unit 104b: Sensor board 105: Sensor support member 105a: Sensor mounting section 105b: Mounting part on one end 105c: Mounting part on the other end 105d: Supported hole 106: Opposing roller 106a: Axis of the opposing roller 107: Positioning part on the other end 108: Positioning part on one end 109a: Roller support plate on one end 109b: Roller support plate on the other end 110: Sensor Unit 113: Support protrusion 115: Engagement groove 115a: Tapered section 116: Spring 120: Screw 123: Support part O1: Center of rotation of the opposing roller [Prior art documents] [Patent Documents]

[0056] [Patent Document 1] Patent No. 5459609

Claims

1. A belt unit having a belt member stretched over multiple tension rollers and a roller support member that rotatably supports the multiple tension rollers, In an image forming apparatus, an image forming apparatus comprises a detection unit having a detection means for detecting the state of the belt surface of the belt member or the state of an object to be detected on the belt surface, and a detection support member for supporting the detection means, which is positioned opposite to an opposing roller, one of a plurality of tension rollers, via the belt member, The belt unit is configured to be detachably attached to the device body in a direction perpendicular to the belt width direction of the belt member, Both ends of the detection support member of the detection unit in the belt width direction are attached to the main body of the device. At least one end of the detection support member in the belt width direction is provided with an engagement groove that engages with the shaft of the opposing roller that penetrates from the roller support member at one end in the belt width direction, and is movably mounted to the device body. The engagement groove is open on the downstream side in the direction in which the belt unit is removed from the main body of the device. An image forming apparatus characterized in that one end of the detection support member in the belt width direction is attached to the main body of the apparatus so as to be movable in a direction perpendicular to the extraction direction.

2. A belt unit having a belt member stretched over a plurality of tension rollers and a roller support member that rotatably supports the plurality of tension rollers, In an image forming apparatus, an image forming apparatus comprises a detection unit having a detection means for detecting the state of the belt surface of the belt member or the state of an object to be detected on the belt surface, and a detection support member for supporting the detection means, which is positioned opposite to an opposing roller, one of a plurality of tension rollers, via the belt member, The belt unit is configured to be detachably attached to the device body in a direction perpendicular to the belt width direction of the belt member, Both ends of the detection support member of the detection unit in the belt width direction are attached to the main body of the device. At least one end of the detection support member in the belt width direction is provided with an engagement groove that engages with the shaft of the opposing roller that penetrates from the roller support member at one end in the belt width direction, and is movably mounted to the device body. The engagement groove is open on the downstream side in the direction in which the belt unit is removed from the main body of the device. At least one end of the detection support member in the belt width direction is attached to the device body so as to be movable in the direction opposite to the opposing roller of the detection means and so as to be rotatable around the belt width direction. The detection support member extends in the belt width direction and has a detection mounting portion to which the detection means is attached. The image forming apparatus is characterized in that the detection mounting portion is torsionally elastically deformable around the belt width direction.

3. In the image forming apparatus according to claim 1, An image forming apparatus characterized by comprising a biasing member that biases the engagement groove in the direction of removal.

4. A belt unit having a belt member stretched over a plurality of tension rollers and a roller support member that rotatably supports the plurality of tension rollers, In an image forming apparatus, an image forming apparatus comprises a detection unit having a detection means for detecting the state of the belt surface of the belt member or the state of an object to be detected on the belt surface, and a detection support member for supporting the detection means, which is positioned opposite to an opposing roller, one of a plurality of tension rollers, via the belt member, The belt unit is configured to be detachably attached to the device body in a direction perpendicular to the belt width direction of the belt member, Both ends of the detection support member of the detection unit in the belt width direction are attached to the main body of the device. At least one end of the detection support member in the belt width direction is provided with an engagement groove that engages with the shaft of the opposing roller that penetrates from the roller support member at one end in the belt width direction, and is movably mounted to the device body. The engagement groove is open on the downstream side in the direction in which the belt unit is removed from the main body of the device. The axis of the other end of the opposing roller in the belt width direction is positioned on the device body in the direction opposite to the opposing roller and in the direction of extraction of the detection means. An image forming apparatus characterized in that the other end of the detection support member in the belt width direction is fixed to the main body of the apparatus.

5. In the image forming apparatus according to claim 1, The image forming apparatus is characterized in that the detection support member has a guide portion that guides the shaft of the opposing roller into the engagement groove.

6. In the image forming apparatus according to claim 1, The aforementioned belt member is an image-carrying belt that carries a toner image, The image forming apparatus is characterized in that the detection means detects a toner image on the image carrying belt.

7. In the image forming apparatus according to claim 6, The image forming apparatus is characterized in that the image carrying belt is an intermediate transfer belt on which a toner image is intermediately transferred.

8. A belt unit having a belt member stretched over a plurality of tension rollers and a roller support member that rotatably supports the plurality of tension rollers, In an image forming apparatus, an image forming apparatus comprises a detection unit having a detection means for detecting the state of the belt surface of the belt member or the state of an object to be detected on the belt surface, and a detection support member for supporting the detection means, which is positioned opposite to an opposing roller, one of a plurality of tension rollers, via the belt member, The belt unit is configured to be detachably attached to the device body in a direction perpendicular to the belt width direction of the belt member, Both ends of the detection support member of the detection unit in the belt width direction are attached to the main body of the device. At least one end of the detection support member in the belt width direction is provided with an engagement groove that engages with the shaft of the opposing roller that penetrates from the roller support member at one end in the belt width direction, and is movably mounted to the device body. The engagement groove is open on the downstream side in the direction in which the belt unit is removed from the main body of the device. The aforementioned belt member is an image-carrying belt that carries a toner image, The detection means detects the toner image on the image carrying belt, The image forming apparatus is characterized in that the image carrying belt is a secondary transfer belt.

Images