Image forming apparatus

Abstract

To improve, for cleaning, workability of work for accessing sensors that detect a toner image on a surface of a movable body.SOLUTION: An image forming apparatus 100 has: sensors 113, 114 that detect a toner image on a surface of a movable body; a shutter member 112 that is movable to an open position and a closed position; a driving source 119 of the shutter member 112; a transmission member 122 that is removably connected to the shutter member 112 and transmits a driving force from the driving source 119 to the shutter member 112; an elastic member 123 that urges the shutter member 112 in a direction toward the closed position; and a supporter 102 that holds the sensors 113, 114 and the shutter member 112. A first end 123a of the elastic member 123 is attached to the transmission member 122, and a second end 123b of the elastic member 123 is attached to the supporter 102.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of functions of these machines, which uses an electrophotographic or electrostatic recording method. [Background technology]

[0002] Conventionally, image forming apparatuses such as electrophotographic copying machines are sometimes provided with a sensor unit having a sensor that detects a toner image as a detection target on a moving body such as an intermediate transfer belt, and a holder that holds the sensor and the like (Patent Document 1). In addition, the sensor unit is sometimes provided with a shutter member that can cover the detection surface of the sensor against the surface of the moving body in order to prevent the detection surface of the sensor from being contaminated by toner scattered from an image formed on the moving body. The shutter member is movably held by the holder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-13033 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, the opening / closing mechanism that moves the shutter member of the sensor unit between an open position where the detection surface of the sensor is exposed to the surface of the movable body and a closed position where the detection surface of the sensor is covered from the surface of the movable body may be configured as follows: That is, the shutter member is biased in a direction from the open position to the closed position by an elastic member, and the shutter member is moved from the closed position to the open position by a drive source at a predetermined timing against the biasing force of the biasing member.

[0005] However, in the conventional configuration, one end of the elastic member that biases the shutter member is attached to the shutter member, and the other end of the elastic member is attached to the above-mentioned holder, which has been found to have the following problems.

[0006] That is, by providing the shutter member in the sensor unit, contamination of the detection surface of the sensor by toner can be suppressed. However, it is difficult to prevent the detection surface of the sensor from gradually becoming dirty with toner, and for example, it may be necessary to periodically clean the detection surface of the sensor. During the above cleaning, the detection surface of the sensor needs to be exposed, so the shutter member needs to be removed from the holder. At this time, if one end of the elastic member that biases the shutter member is attached to the shutter member as described above, it is necessary to remove one end of the elastic member from the shutter member and reattach it every time the above cleaning work is performed. Such work of removing and reattaching the elastic member may lead to a decrease in workability (work efficiency) due to an increase in man-hours.

[0007] The same applies to the sensor replacement when it becomes necessary.

[0008] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to improve the efficiency of an operation for accessing a sensor that detects a toner image on the surface of a moving body for cleaning or the like. [Means for solving the problem]

[0009] The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention is an image forming apparatus comprising: a sensor for detecting a toner image on a surface of a moving body; a shutter member arranged between the sensor and the surface of the moving body and movable between an open position where the sensor is exposed to the surface of the moving body and a closed position where the sensor is covered from the surface of the moving body; a drive source for generating a drive force for moving the shutter member; a transmission member detachably connected to the shutter member and transmitting the drive force from the drive source to the shutter member; an elastic member for biasing the shutter member in a direction from the open position to the closed position; and a holder for holding the sensor, the shutter member, the drive source, the transmission member, and the elastic member, wherein a first end of the elastic member is attached to the transmission member, and a second end of the elastic member opposite to the first end is attached to the holder. Effect of the Invention

[0010] According to the present invention, it is possible to improve the efficiency of an operation for accessing a sensor that detects a toner image on the surface of a moving body for cleaning or the like. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Diagram 2] FIG. 2 is a schematic block diagram illustrating a control configuration of the image forming apparatus. [Diagram 3] FIG. 2 is an external perspective view of the sensor unit. [Figure 4] FIG. 2 is an external perspective view of a sensor unit and a belt unit. [Diagram 5] FIG. 2 is a side view of the inside of the sensor unit. [Figure 6] FIG. [Figure 7] FIG. 4 is a perspective view of the shutter member in a closed state. [Figure 8] FIG. 4 is a perspective view of the shutter member in an open state. [Figure 9]13 is a side view of the periphery of a transmission member when the opening / closing mechanism of the shutter member is in a closed state. FIG. [Figure 10] 13 is a side view of the periphery of a transmission member when the opening / closing mechanism of the shutter member is in an open state. FIG. [Figure 11] FIG. [Figure 12] 11 is a perspective view of the sensor unit for explaining the attachment and detachment of the shutter member. FIG. [Figure 13] 11 is a perspective view of the sensor unit for explaining the attachment and detachment of the shutter member. FIG. [Figure 14] 13 is a plan view of a portion of the shutter member for illustrating a shutter regulating portion. FIG. [Figure 15] 13 is a side view of the periphery of the transmission member for illustrating a transmission member restricting portion. FIG. [Figure 16] 13 is a side view of the periphery of the transmission member, illustrating another example of the transmission member restricting portion. FIG. [Figure 17] FIG. 13 is a schematic side view of the inside of a sensor unit according to another example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[0013] [Example 1] 1. Overall configuration and operation of the image forming apparatus 1 is a schematic cross-sectional view of an image forming apparatus 100 according to this embodiment. The image forming apparatus 100 according to this embodiment is a tandem printer that employs an intermediate transfer method capable of forming a full-color image using an electrophotographic method. The image forming apparatus 100 can form and output an image on a sheet-shaped recording material P according to image information (image signal) acquired from an external device such as an image reading device or a personal computer.

[0014] The image forming apparatus 100 has four image forming sections (image forming units) 1Y, 1M, 1C, and 1K that form toner images of each color, yellow (Y), magenta (M), cyan (C), and black (K), as a plurality of image forming sections. The four image forming sections 1Y, 1M, 1C, and 1K are arranged in series along the moving direction of an image transfer surface of an intermediate transfer belt 31, which is arranged substantially horizontally, as described later. Elements having the same or corresponding functions or configurations provided for each color may be generally described by omitting the Y, M, C, and K at the end of the reference numerals indicating that the elements are for any of the colors. In this embodiment, the image forming section 1 is configured to include a photosensitive drum 11, a charging device 12, an exposure device 13, a developing device 14, and a drum cleaning device 15, which will be described later.

[0015] The photosensitive drum 11, which is a rotatable drum-type (cylindrical) photosensitive member (electrophotographic photosensitive member) serving as a first image carrier, is rotated in the direction of arrow R1 (counterclockwise direction) in the figure by a driving motor (not shown) serving as a driving means. The surface (outer circumferential surface) of the rotating photosensitive drum 11 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging device 12 serving as a charging means. The surface of the charged photosensitive drum 11 is irradiated with laser light corresponding to image information by an exposure device (laser scanner device) 13 serving as an exposure means, and is scanned and exposed, so that an electrostatic latent image (electrostatic image) corresponding to the image information is formed on the photosensitive drum 11. The electrostatic latent image formed on the photosensitive drum 11 is developed (visualized) by a developing device 14 serving as a developing means, which supplies toner as a developer, and a toner image (toner image, developer image) is formed on the photosensitive drum 11. In this embodiment, toner charged with the same polarity as the charge polarity of the photosensitive drum 11 (negative polarity in this embodiment) adheres to the exposed portion (image portion) on the photosensitive drum 11, which has been uniformly charged and then exposed to light to reduce the absolute value of the potential (reverse development method). In this embodiment, the normal charge polarity of the toner, which is the main charge polarity of the toner during development, is negative polarity.

[0016] An intermediate transfer belt 31, which is an intermediate transfer body formed of an endless belt as a second image carrier, is disposed so as to face the four photosensitive drums 11Y, 11M, 11C, and 11K. The intermediate transfer belt 31 is stretched across a plurality of tension rollers, which are a drive roller 33, a backup roller 34, a tension roller 35, a secondary transfer pre-roller 37, and a secondary transfer inner roller 32. The intermediate transfer belt 31 rotates (moves around) in the direction of arrow R2 in the figure (clockwise direction) by a drive motor (not shown) as a drive means that drives the drive roller 33 to rotate. The tension roller 35 is pressed in the direction from the inner circumferential surface side to the outer circumferential surface side of the intermediate transfer belt 31 at both ends in the rotation axis direction by tension springs 38 formed of compression coil springs as elastic members as biasing means. As a result, the tension roller 35 applies a predetermined tension to the intermediate transfer belt 31. On the inner peripheral surface side of the intermediate transfer belt 31, primary transfer rollers 35Y, 35M, 35C, and 35K, which are roller-type primary transfer members serving as primary transfer means, are arranged in correspondence with the photosensitive drums 11Y, 11M, 11C, and 11K. The primary transfer rollers 35 are pressed toward the photosensitive drums 11 and come into contact with the photosensitive drums 11 via the intermediate transfer belt 31, forming a primary transfer portion (primary transfer nip portion) N1, which is the contact portion between the photosensitive drums 11 and the intermediate transfer belt 31. The tension rollers other than the driving roller 33 and each primary transfer roller 35 are driven to rotate with the rotation of the intermediate transfer belt 31. The toner image formed on the photosensitive drum 11 is transferred (primary transfer) onto the rotating intermediate transfer belt 31 at the primary transfer portion N1. During primary transfer, a primary transfer voltage (primary transfer bias) of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the primary transfer roller 35. For example, when forming a full-color image, the Y, M, C, and K color toner images formed on each photosensitive drum 11 are transferred sequentially to the intermediate transfer belt 31 at each primary transfer portion N1 so as to be superimposed on the same image position.

[0017] On the outer peripheral surface side of the intermediate transfer belt 31, a secondary transfer outer roller (secondary transfer roller) 41, which is a roller-type secondary transfer member serving as a secondary transfer means, is disposed at a position facing the secondary transfer inner roller (secondary transfer opposing roller) 32. The secondary transfer outer roller 41 is pressed toward the secondary transfer inner roller 32 and abuts against the secondary transfer inner roller 32 via the intermediate transfer belt 31 to form a secondary transfer portion (secondary transfer nip portion) N2, which is a contact portion between the intermediate transfer belt 31 and the secondary transfer outer roller 41. The secondary transfer outer roller 41 rotates in accordance with the rotation of the intermediate transfer belt 31. The toner image formed on the intermediate transfer belt 31 is transferred (secondary transfer) onto the recording material P, which is being conveyed while being sandwiched between the intermediate transfer belt 31 and the secondary transfer outer roller 41, at the secondary transfer portion N2. During secondary transfer, a secondary transfer voltage (secondary transfer bias) of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the secondary transfer outer roller 41. The inner secondary transfer roller 32 is connected to a ground potential. It is also possible to apply a secondary transfer voltage having the same polarity as the normal charging polarity of the toner to the inner secondary transfer roller 32, and connect the outer secondary transfer roller 41 to the ground potential. A recording material (recording medium, transfer material, sheet) P such as paper is fed from the feeding section 6 and supplied to the secondary transfer section N2. That is, the recording material P is stored in cassettes 61, 62, and 63 serving as a recording material storage section of the feeding section 6. The recording material P stored in the cassettes 61, 62, and 63 is sent out from one of the cassettes 61, 62, and 63 by rotating one of the feeding rollers 64, 65, and 66 serving as a feeding member of the feeding section 6. This recording material P is sent to the registration rollers 21 serving as a conveying member through the feeding conveying path 67. The registration rollers 21 convey this recording material P to the secondary transfer section N2 in synchronization with the toner image on the intermediate transfer belt 31.

[0018] The recording material P onto which the toner image has been transferred is transported by a transport belt 60 as a transport member to a fixing device (thermal fixing device) 5 as a fixing means. The fixing device 5 heats and pressurizes the recording material P carrying the unfixed toner image, thereby fixing (melting and bonding) the toner image to the surface of the recording material P. The recording material P onto which the toner image has been fixed is discharged (output) through a discharge transport path 68 to a discharge tray 69 as a discharge section provided outside the device main body (hereinafter also simply referred to as the "device main body") 2 of the image forming apparatus 100.

[0019] Meanwhile, the toner remaining on the photosensitive drum 11 after the primary transfer (primary transfer residual toner) is removed from the photosensitive drum 11 and collected by a drum cleaning device 15 serving as a photosensitive body cleaning means. Also, deposits such as the toner remaining on the intermediate transfer belt 31 after the secondary transfer (secondary transfer residual toner) are removed from the intermediate transfer belt 31 and collected by a belt cleaning device 36 serving as an intermediate transfer body cleaning means.

[0020] The exposure device 3 is provided with a laser light source whose light emission is controlled according to an image signal, and optical components such as a mirror for directing the laser light from the laser light source onto the photosensitive drum 1. By adjusting the emission timing of the laser light and the arrangement of the mirror, it is possible to adjust the image writing timing and adjust the image position of each color. In addition, by adjusting the potential of the photosensitive drum 1 and the light amount of the laser light source, it is possible to adjust the image density of each color.

[0021] The image forming apparatus 100 also has a sensor unit 101 disposed downstream of the most downstream primary transfer portion N1K in the moving direction of the surface of the intermediate transfer belt 31 and upstream of the secondary transfer portion N2 so as to face the surface (outer circumferential surface) of the intermediate transfer belt 31. The sensor unit 101 has a registration sensor 113 and a density sensor 114 (FIGS. 2 and 6) which are optical sensors. A backup roller 34 is disposed at a position facing the sensor unit 101 on the inner circumferential surface side of the intermediate transfer belt 31. The sensor unit 101 will be described in more detail later.

[0022] In this embodiment, the photosensitive drum 11, the charging device 12, the developing device 14, and the drum cleaning device 15 in each image forming unit 1 integrally constitute a cartridge (process cartridge) that is detachable from the apparatus main body 2. In this embodiment, the intermediate transfer belt 31, the multiple tension rollers of the intermediate transfer belt 31, the primary transfer rollers 35, the belt cleaning device 36, and a frame supporting these, etc., integrally constitute a belt unit 3 that is detachable from the apparatus main body 2.

[0023] 2. Control Unit 2 is a schematic block diagram showing the control configuration of the image forming apparatus 100 in this embodiment. The control unit 200 as a control means provided in the image forming apparatus 100 is configured with a CPU 201 which is a central element for performing arithmetic processing, and a memory 202 such as a ROM and a RAM which are storage elements. The RAM stores the detection results of the sensors and the calculation results, and the ROM stores the control program and a data table obtained in advance. The control unit 200 comprehensively controls each part of the image forming apparatus 100. For example, the image forming units 1Y, 1M, 1C, and 1K, the registration sensor 113 and the density sensor 114 of the sensor unit 101, and a solenoid 119 to be described later are connected to the control unit 200. The control unit 200 corrects the operation of the image forming units SY, 1M, 1C, and 1K based on the detection results of the registration sensor 113 and the density sensor 114 of the sensor unit 101, and executes control for adjusting the image position of each color and the image density of each color. The control unit 200 also controls the driving of a solenoid 119 (to be described later) of the sensor unit 101 and the like.

[0024] 3.Sensor unit Next, the sensor unit 101 in this embodiment will be described. In the following description, the near side of the paper in FIG. 1 will be referred to as the front (front side) and the far side of the paper in FIG. 1 will be referred to as the far side (rear side). In addition, the left and right sides of the image forming apparatus 100 and its elements when viewed from the front side will be referred to as the left and right sides, respectively. The depth direction connecting the front and far sides of the image forming apparatus 100 is assumed to be approximately parallel to the direction of the rotation axis of the photosensitive drum 11. In addition, the up-down direction refers to the up-down direction in the direction of gravity (vertical direction), but does not mean only directly above and directly below, but also includes the upper and lower sides of a horizontal plane passing through the element or position of interest.

[0025] Fig. 3 is an external perspective view of the sensor unit 101 as viewed from the right front side. Fig. 4 is an external perspective view of the sensor unit 101 and a part of the belt unit 3 as viewed from the right front side. Fig. 5 is a side view of the inside of a housing 110 of the sensor unit 101, which will be described later, as viewed from the right side. Fig. 6 is a perspective view of a holding member 111 of the sensor unit 101, which will be described later, as viewed from the detection surface 120 side (intermediate transfer belt 31 side) of the registration sensor 113 and the density sensor 114.

[0026] The sensor unit 101 is broadly composed of a housing 110, a registration sensor 113, a density sensor 114, a holding member 111, and a shutter member 112. The housing 110 as a support portion constitutes the outer frame of the sensor unit 101. The registration sensor 113 and the density sensor 114 as a plurality of sensors detect a registration patch and a density patch, which are detection targets on the surface of the intermediate transfer belt 31 as a moving body (conveyor), respectively. The holding member 111 is supported by a frame 115 constituting the housing 110, and holds the registration sensor 113, the density sensor 114, the shutter member 112, a solenoid 119 to be described later, a shutter spring 123 to be described later, and the like. The holding body 102 is composed of the housing 110 constituted by the frame 115 and the like, a holding member support plate 116 to be described later fixed to the frame 115, the holding member 111 supported by the frame 115 via the holding member support plate 116, and the like. The holder 102 holds a registration sensor 113, a density sensor 114, a shutter member 112, a solenoid 119 (described later), a shutter spring 123 (described later), etc. Each component will be described in detail below.

[0027] <Case> As shown in FIGS. 3 and 4, the housing 110 has a box shape that is long in a direction (width direction of the intermediate transfer belt 31) that intersects (almost perpendicular in this embodiment) with the moving direction of the surface of the intermediate transfer belt 31. The housing 110 is configured with a frame 115 used for fixing the sensor unit 101 to the device body 2 of the image forming device 100 as a base. As shown in FIG. 5, a holding member support plate 116, an electric board 117, a fan 118, and the like are fixed to the inside of the frame 115. The holding member support plate 116 supports the holding member 111. The electric board 118 processes electric signals exchanged between the registration sensor 113, the concentration sensor 114, the fan 118, and a solenoid 119 (described later) under the control of the control unit 200. In addition, an opening 110a is provided on the lower surface of the housing 110 so that the detection surfaces 120 (FIG. 6) of the registration sensor 113 and the concentration sensor 114 held by the holding member 111 can be exposed to the surface of the intermediate transfer belt 31 as shown in FIG.

[0028] In this embodiment, the fan 118 is provided to prevent the adhesion of dirt such as toner to the detection surfaces 120 (FIG. 6) of the registration sensor 113 and the concentration sensor 114 due to the airflow, thereby preventing the adhesion of dirt such as toner to the detection surfaces 120 (FIG. 6) of the registration sensor 113 and the concentration sensor 114. The sensor unit 101 is configured to blow air sent out from the fan 118 through the detection surfaces 120 (FIG. 6) of the registration sensor 113 and the concentration sensor 114 and out of a detection opening 124 (FIG. 8) of the slide shutter 112a described later.

[0029] Here, in this embodiment, the sensor unit 101 (holding body 102) is configured to be detachable from the device body 2. In this embodiment, the sensor unit 101 is inserted from the front side of the device body 2 toward the back side to be attached to the device body 2, and conversely, is removed from the device body 2 by being pulled out from the back side of the device body 2 toward the front side. When the sensor unit 101 is attached to the device body 2, a unit side positioning portion 110b (FIGS. 4 and 5) provided on the frame 115 of the housing 110 of the sensor unit 101 is fitted into a body side positioning portion (not shown) provided on the frame of the device body 2. In this way, the position of the sensor unit 101 in the device body 2 is determined and the sensor unit 101 is fixed to the device body 2. At this time, the sensor unit 101 is positioned at a position where the detection surfaces 120 (FIG. 6) of the registration sensor 113 and the density sensor 114 face the surface of the intermediate transfer belt 31.

[0030] <Sensor> With reference to FIG. 6, the registration sensor 113 and the density sensor 114 are sensors that detect a toner image as a detection target on the surface of the intermediate transfer belt 31. In this embodiment, the registration sensor 113 and the density sensor 114 are each configured as a reflective optical sensor. The registration sensor 113 and the density sensor 114 each have a light emitting unit that irradiates light toward the surface of the intermediate transfer belt 31, a light receiving unit that receives light from the light emitting unit reflected from the surface of the intermediate transfer belt 31 or the toner image thereon, and a storage unit that stores them. A cover member made of glass or synthetic resin that can transmit light (irradiated light, reflected light) from the light emitting unit is provided on a side of the storage unit that faces the surface of the intermediate transfer belt 31. The registration sensor 113 and the density sensor 114 each have a detection surface (detection unit) 120 that faces the surface of the intermediate transfer belt 31 when detecting at least a toner image. In this embodiment, the surface of the cover member forms this detection surface 120. The registration sensor 113 is an optical sensor that reads a reference image for color misregistration correction (also referred to here as a "registration patch"), which is a toner image formed on the intermediate transfer belt 31. The density sensor 114 is an optical sensor that reads a reference image for density correction (also referred to here as a "density patch"), which is a toner image formed on the intermediate transfer belt 31.

[0031] As shown in Fig. 6, three registration sensors 113 are arranged in the width direction of intermediate transfer belt 31. Then, based on the detection results of the registration patches of each color of yellow, magenta, cyan, and black by these registration sensors 113, the misalignment amount of each color is calculated by control unit 200. This calculated misalignment amount indicates the amount of misalignment due to multiple factors including the conveyance direction of intermediate transfer belt 31, the direction perpendicular to the conveyance direction, and the inclination on a plane. The calculated misalignment amount is fed back to the image (control of image forming unit 1) that is processed and output by control unit 200.

[0032] 6, three density sensors 114 are arranged in the width direction of the intermediate transfer belt 31. Then, based on the detection results of the density patches of each color of yellow, magenta, cyan, and black by the density sensors 114, the control unit 200 calculates a density adjustment amount for adjusting the density of the image of each color to an appropriate density for the image to be output. The calculated density adjustment amount is fed back to the image processed and output by the control unit 200 (control of the image forming unit 1).

[0033] In this embodiment, multiple registration sensors 113 and multiple concentration sensors 114 are provided, but the numbers of registration sensors 113 and concentration sensors 114 are not limited to those in this embodiment. At least one sensor may be configured to function as both a registration sensor and a concentration sensor. The number of sensors in total or for each of the registration sensors and concentration sensors may be more or less than that in this embodiment (there may be only one sensor in total).

[0034] <Retaining material> As shown in Fig. 6, the holding member 111 holds the registration sensor 113 and the registration sensor 114. In this embodiment, the holding member 111 is supported by the frame 115 of the housing 110 so as to be movable relative to the frame 115. Specifically, as shown in Fig. 5, the holding member 111 is supported by a holding member support plate 116 fixed to the frame 115 of the housing 110 via a support spring 121 constituted by a compression coil spring which is an elastic member serving as a biasing means. As a result, the holding member 111 is supported by the frame 115 so as to be movable in a direction substantially perpendicular to the surface of the intermediate transfer belt 31.

[0035] Further, a sensor positioning portion 111b is provided at the end of the holding member 111 in the front-rear direction. When the sensor unit 101 is attached to the device body 2, the sensor positioning portion 111b is abutted against an abutment portion (not shown) provided on the belt unit 3 by the pressing force of the support spring 121. This keeps the distance between the registration sensor 113 and the density sensor 114 held by the holding member 111 and the surface of the intermediate transfer belt 31 constant. The abutment portion is provided, for example, on the rotation axis of the backup roller 34 arranged on the inner circumferential surface side of the intermediate transfer belt 31. For example, this abutment portion is a bearing that rotatably supports the backup roller 34.

[0036] <Shutter parts> Figures 7 and 8 are perspective views of the shutter member 112 as viewed from the registration sensor 113 and concentration sensor 114 side (inside the housing 110), with Fig. 7 showing the shutter member 112 in a closed position to be described later, and Fig. 8 showing the shutter member 112 in an open position to be described later. Also, Figs. 9 and 10 are side views of a part of the interior of the sensor unit 101 as viewed from the right side, showing the opening and closing mechanism of the shutter member 112, with Fig. 9 showing the shutter member 112 in a closed position to be described later, and Fig. 10 showing the shutter member 112 in an open position to be described later.

[0037] In this embodiment, as shown in FIG. 7 and FIG. 8, the shutter member (stain-proof member) 112 is configured to have a slide shutter 112a as a first shutter member and a rotating shutter 112b as a second shutter member. In this embodiment, the shutter member 112 is supported by a holding member 111 and is disposed between the detection surface 120 of the register sensor 113 and the density sensor 114 and the surface of the intermediate transfer belt 31. The shutter member 112 may be supported by the housing 110 (frame 115, etc.). That is, the shutter member 112 only needs to be supported by the holding body 102 composed of the housing 110, the holding member 111, etc. The shutter member 112 is movable between an open position (first position) where the detection surface 120 is exposed to the surface of the intermediate transfer belt 31 and a closed position (second position) where the detection surface 120 is covered (shielded) from the surface of the intermediate transfer belt 31. Moreover, the shutter member 112 is driven by a solenoid 119 serving as a drive source (drive unit). In this embodiment, the solenoid 119 is supported by a holding member 111. The solenoid 119 may be supported by the housing 110 (such as the frame 115). In other words, it is sufficient that the solenoid 119 is supported by the holding body 102 constituted by the housing 110, the holding member 111, and the like.

[0038] As shown in Figs. 10 and 11, the driving force from the solenoid 119 is transmitted to the shutter member 112 via a transmission member (link member) 122. That is, the sensor unit 101 has a transmission member 122 that is connected to a plunger 119a as a movable part provided in the solenoid 119 and a slide shutter 112a of the shutter member 112 and is movable together with the plunger 119a. In this embodiment, a part of the transmission member 122 is fixed to the plunger 119a, and another part is detachably fixed to the slide shutter 112a of the shutter member 112 as described later. A first spring attachment part 122a is provided on the transmission member 122, and a first end part 123a, which is one end part of a shutter spring 123 constituted by a tension coil spring that is an elastic member serving as a biasing means, is attached to the first spring attachment part 122a. In this embodiment, the holding member 111 is provided with a second spring attachment portion 111a, and a second end portion 123b, which is the other end portion of the shutter spring 123, is attached to the second spring attachment portion 111a.

[0039] When a current is applied to the solenoid 119, the plunger 119a of the solenoid 119 is attracted into the solenoid 119, and in conjunction with this, the transmission member 122 moves toward the left side (front side) in FIG. 9. Then, this movement is transmitted to the shutter member 112, and the shutter member 112 moves to the open position shown in FIGS. 8 and 10. Also, when the current is stopped from flowing to the solenoid 119, the plunger 119a of the solenoid 119 is no longer attracted, and the transmission member 122 is pulled by the shutter spring 123 and moves toward the right side (rear side) in FIG. 10. Then, this movement is transmitted to the shutter member 112, and the shutter member 112 moves (returns) to the closed position shown in FIGS. 7 and 9. By using the shutter spring 123 that biases the shutter member 112 in a direction from the open position toward the closed position, the shutter member 112 can be maintained in the closed position even when the power supply to the solenoid 119 is stopped.

[0040] Here, the second end 123b of the shutter spring 123 may be attached anywhere other than the shutter member 112 (the sliding shutter 112a in this embodiment) and the transmission member 122. In this embodiment, the second spring attachment portion 111a is provided on the holding member 111, but the second spring attachment portion may be provided on the housing 110 (such as the frame 115), for example. In other words, it is sufficient that the second spring attachment portion 111a is provided on the holding body 102 constituted by the housing 110, the holding member 111, etc.

[0041] 7 and 8, in this embodiment, the slide shutter 112a is a member having a substantially rectangular plate shape that is long in the width direction of the intermediate transfer belt 31. In addition, in this embodiment, the rotating shutter 112b is disposed corresponding to each of the registration sensor 113 and the density sensor 114.

[0042] The sliding shutter 112a as a moving member is attached to the holding member 111 so as to be slidable in a direction (width direction of the intermediate transfer belt 31) intersecting (almost perpendicular in this embodiment) the moving direction of the surface of the intermediate transfer belt 31. The sliding shutter 112a has a detection opening 124 which is an opening that exposes the detection surface 120 of the register sensor 113 and the density sensor 114 to the intermediate transfer belt 31. That is, the detection opening 124 faces the detection surface 120 when the sliding shutter 112a moves to the open position (FIG. 8). Also, the detection opening 124 moves away from the position facing the detection surface 120 when the sliding shutter 112a moves to the closed position (FIG. 7). Note that in this embodiment, the detection opening 124 moves away from a part of the detection surface 120 when the sliding shutter 112a moves to the closed position. However, the detection opening 124 may move away from the entire detection surface 120 when the sliding shutter 112a moves to the closed position. In this embodiment, the detection opening 124 is configured to expose the entire detection surface 120 to the intermediate transfer belt 31 when the slide shutter 112a moves to the open position. However, the detection opening 124 may be configured to expose a part of the detection surface 120 to the intermediate transfer belt 31 when the slide shutter 112a moves to the open position. It is sufficient that detection by the registration sensor 113 and the density sensor 114 is possible.

[0043] The rotating shutter 112b as a covering member is supported by the holding member 111 in a rotatable and detachable manner, and rotates in conjunction with the movement of the sliding shutter 112a. FIG. 11 is a plan view of one rotating shutter 112b as viewed from the sliding shutter 112a side (outside the housing 110). In this embodiment, a rotating shaft 111c is provided on the holding member 111, and a rotating hole 112c that rotatably fits with the rotating shaft 111c is provided on the rotating shutter 112b. Also, in this embodiment, an engagement boss 112d is provided on the sliding shutter 112a, and an engagement hole 112e that engages with the engagement boss is provided on the rotating shutter 112b. When the slide shutter 112a slides (linearly moves) in the width direction of the intermediate transfer belt 31, the engagement boss 112d engages with the engagement hole 112e, and the rotating shutter 112b rotates (rotates) around the rotation shaft 111c and the rotation hole 112c. When the slide shutter 112a moves to the open position, the rotating shutter 112b moves out of the position covering (facing) the detection opening 124 (FIG. 8). When the slide shutter 112a moves to the closed position, the rotating shutter 112b covers (facing) the detection opening 124 (FIG. 7). In this embodiment, when the rotating shutter 112b moves to the closed position, it covers the entire detection opening 124. However, when the rotating shutter 112b moves to the closed position, it may cover a part of the detection opening 124. It is sufficient that the detection surface 120 has sufficient antifouling properties. In this embodiment, when the rotating shutter 112b moves to the open position, it is arranged to be out of a part of the detection opening 124. However, when the rotating shutter 112b moves to the open position, it may be arranged to be out of the entire detection opening 124. It is sufficient that the registration sensor 113 and the density sensor 114 can detect it.

[0044] With this configuration, when the shutter member 112 is in the closed position (closed state), it is possible to prevent toner from adhering to the detection surfaces 120 of the registration sensor 113 and the concentration sensor 114. Furthermore, when the shutter member 112 is in the open position (open state), it is possible for the registration sensor 113 and the concentration sensor 114 to detect the toner image on the intermediate transfer belt 31.

[0045] 4.Removing the shutter parts When the shutter member 112 is closed, the detection surfaces 120 of the registration sensor 113 and the density sensor 114 are covered by the shutter member 112, suppressing the adhesion of toner. However, when the registration sensor 113 and the density sensor 114 read the registration patch and the density patch, respectively, the detection surfaces 120 of the registration sensor 113 and the density sensor 114 are exposed to the surface of the intermediate transfer belt 31. For example, even if the time during which the shutter member 112 is open is shortened as much as possible, it is difficult to prevent the detection surfaces 120 of the registration sensor 113 and the density sensor 114 from gradually becoming dirty with toner. If the detection surfaces 120 of the registration sensor 113 and the density sensor 114 become dirty with toner, it becomes difficult to accurately read the registration patch and the density patch. This makes it difficult to correctly perform color shift correction and density correction, leading to image defects. For this reason, it may be necessary to periodically clean the detection surfaces 120, for example. During the above cleaning work, it is necessary to remove the shutter member 112 from the holder 102 in order to expose the detection surface 120 .

[0046] At this time, if one end of the elastic member that biases the shutter member 112 is attached to the shutter member 112, it is necessary to remove one end of the elastic member from the shutter member 112 and reattach it every time the above-mentioned cleaning work is performed. Such work of removing and reattaching the elastic member may lead to a decrease in workability (work efficiency) due to an increase in the number of steps. In addition, such work may lead to an increased risk of damage to parts, such as deformation of the elastic member during work.

[0047] The same can be said about replacement work when the registration sensor 113 or the density sensor 114 needs to be replaced due to a malfunction or the like.

[0048] Therefore, in this embodiment, as described above, the transmission member 122 is provided between the plunger 119a of the solenoid 119 and the shutter member 112 (the sliding shutter 112a in this embodiment). In this embodiment, the first end 123a, which is one end of the shutter spring 123, is attached to the first spring attachment portion 122a provided on this transmission member 122.

[0049] 12 and 13 are perspective views of a part of the sensor unit 101 seen from the intermediate transfer belt 31 side, for explaining the removal operation of the shutter member 112 (slide shutter 112a) in this embodiment. Fig. 12 shows a state in which the shutter member 112 (slide shutter 112a) is attached to the holder 102, and Fig. 13 shows a state in which the shutter member 112 (slide shutter 112a) has been removed from the holder 102.

[0050] As shown in FIG. 13, the transmission member 122 is provided with a screw hole 122b as a shutter fixing portion constituting a connection portion detachably connected to the shutter member 112. The screw hole 122b is provided on the surface side of the intermediate transfer belt 31 (the shutter member 112 side, the outside of the housing 110) of the intermediate transfer belt 31 relative to the first spring mounting portion 122a of the transmission member 122 and the second spring mounting portion 111a of the holding member 111 in the normal direction of the surface of the intermediate transfer belt 31 at the position where the registration patch and the density patch are detected by the registration sensor 113 and the density sensor 114. In addition, the sliding shutter 112a is provided with a fixing hole 112f. By passing a screw 126 as a fixing member through the fixing hole 112f of the sliding shutter 112a and screwing it into the screw hole 122b of the transmission member 122, the sliding shutter 112a can be fixed to the transmission member 122 as shown in FIG. 12. At this time, the sliding shutter 112a may be held by the holding member 111 by, for example, movably and detachably engaging with an engagement portion provided on the holding member 111.

[0051] With this configuration, as shown in Figs. 12 and 13, the sliding shutter 112a can be removed from the holding member 111 while the shutter spring 123 is hung on the transmission member 122. That is, in this embodiment, the sliding shutter 112a can be removed from the holding member 111 without removing the first end 123a of the shutter spring 123 from the first spring mounting portion 122a provided on the transmission member 122. At this time, the second end 123b of the shutter spring 123 is also left attached to the second spring mounting portion 111a of the holding member 111. As a result, it is possible to suppress the above-mentioned deterioration in workability and the increase in the risk of damage to parts during work. Therefore, it is possible to efficiently and easily perform the above-mentioned cleaning work and replacement work.

[0052] To explain further, when removing the shutter member 112 from the holder 102, the sensor unit 101 is removed from the apparatus body 2 and arranged so that the shutter member 112 faces upward. After that, the screw 126 is removed from the screw hole 122b of the transmission member 122, and the sliding shutter 112a is removed from the transmission member 122 (FIGS. 12 and 13). At this time, the engagement boss 112d of the sliding shutter 112a is removed from the engagement hole 112e of the rotating shutter 112b (FIG. 11). After that, the rotating shutter 112b is removed from the holding member 111 so as to remove the rotating shaft 111c of the holding member 111 from the rotating hole 112c of the rotating shutter 112b (FIG. 11), and the detection surface 120 of the registration sensor 113 and the density sensor 114 can be exposed. In this way, it is not necessary to remove the shutter spring 123 in order to expose the detection surfaces 120 of the registration sensor 113 and the density sensor 114 .

[0053] When the shutter member 112 is attached to the holder 102, the rotating shutter 112b is attached to the holder 111 by fitting the rotating hole 112c of the rotating shutter 112b to the rotating shaft 111c of the holder 111 facing upward as described above (FIG. 11). At this time, the rotating shutter 112b is placed in a closed position that covers the detection surface 120 of the registration sensor 113 and the density sensor 114. After that, the engagement bosses 112d of the slide shutter 112a are inserted into the engagement holes 112e of the slide shutter 112b (FIG. 11), and the position of the fixing hole 112f of the slide shutter 112a is aligned with the position of the screw hole 122b of the transmission member 122 (FIG. 13). Here, in this embodiment, as shown in FIG. 13, the transmission member 122 is provided with a positioning protrusion 122c adjacent to the screw hole 122b. In this embodiment, two positioning protrusions 122c are provided so as to sandwich the screw hole 122b. In addition, the sliding shutter 112a is provided with a positioning hole 112g adjacent to the fixing hole 112f. In this embodiment, two positioning holes 112g are provided so as to sandwich the fixing hole 112f. As a result, by fitting the positioning holes 112g into the positioning protrusions 122c, it is easy to insert each engagement boss 112d into each engagement hole 112e as described above and to align the position of the fixing hole 112f with the position of the screw hole 122b. After that, the sliding shutter 112a is fixed to the transmission member 122 by the screw 126 (FIG. 12). In this way, when attaching the shutter member 112 to the holder 102, it is not necessary to attach the shutter spring 123.

[0054] As described above, in this embodiment, the image forming apparatus 100 includes sensors 113 and 114 for detecting a toner image on the surface of the movable body 31, a shutter member 112 that is disposed between the sensors 113 and 114 and the surface of the movable body 31 and is movable between an open position where the sensors 113 and 114 are exposed to the surface of the movable body 31 and a closed position where the sensors 113 and 114 are covered from the surface of the movable body 31, a drive source 119 that generates a drive force for moving the shutter member 112, and a shutter section 113 that is detachably connected to the shutter member 112. The shutter member 112 has a transmission member 122 that transmits a driving force from a driving source 119 to the shutter member 112, an elastic member 123 that urges the shutter member 112 in a direction from the open position toward the closed position, and a holder 102 that holds the sensors 113, 114, the shutter member 112, the driving source 119, the transmission member 122, and the elastic member 123, and a first end 123a of the elastic member 123 is attached to the transmission member 122, and a second end 123b of the elastic member 123 opposite the first end 123a is attached to the holder 102. In this embodiment, the transmission member 122 has a connection portion 122b that is detachably connected to the shutter member 112, on the surface side of the movable body 31 relative to the first mounting portion 122a to which the first end portion 123a of the transmission member 122 is attached and the second mounting portion 111a to which the second end portion 123b of the holder 102 is attached, in relation to the normal direction of the surface of the movable body 31 at the position where the toner image is detected by the sensors 113 and 114. In this embodiment, the shutter member 112 includes a first shutter member 112a that is disposed between the sensors 113 and 114 and the surface of the moving body 31 and is movable along a direction intersecting the moving direction of the moving body 31, and a second shutter member 112b that is disposed between the sensors 113 and 114 and the first shutter member 112a and is rotatable with the movement of the first shutter member 112a, and the transmission member 122 is detachably connected to the first shutter member 112a. In this embodiment, the transmission member 122 is movable along a direction intersecting the moving direction of the moving body 31. In this embodiment, the drive source 119 is configured with a solenoid. In this embodiment, the elastic member 123 is configured with a tension coil spring.However, the elastic member 123 may be of another form, such as a compression coil spring, by appropriately changing the arrangement of the first and second spring attachment portions 122a and 111a. In this embodiment, the holder 102 is detachable from the main body 2 of the image forming apparatus 100. In this embodiment, the movable body 31 is formed of an endless belt stretched by a plurality of tension rollers.

[0055] As described above, according to this embodiment, it is possible to reduce the number of parts to be attached and detached in order to access the sensors 113, 114 of the sensor unit 101 for cleaning or the like. Therefore, according to this embodiment, it is possible to improve the workability of the work of accessing the sensors 113, 114 of the sensor unit 101 for cleaning or the like. Furthermore, according to this embodiment, it is possible to reduce the risk of damage to parts during the work of accessing the sensors 113, 114 of the sensor unit 101 for cleaning or the like.

[0056] [Example 2] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of embodiment 1, and detailed explanations are omitted.

[0057] In this embodiment, the shutter unit 101 is configured such that, when the shutter member 112 is attached to the holder 102 and moves to the closed position, a part of the shutter member 112 abuts against the holder 111. FIG. 14 is an enlarged plan view of one rotating shutter 112b in the closed position in this embodiment, as viewed from the intermediate transfer belt 31 side. In FIG. 14, the slide shutter 112a is omitted from illustration. In this embodiment, when the shutter member 112 moves to the closed position, a side surface 112h on the downstream side in the rotation direction toward the closed position of the rotating shutter 112b abuts against a shutter abutment portion 111d provided on the holder 111. This determines the position of the shutter members (slide shutter 112a, rotating shutter 112b) in the closed position. It is sufficient that the position of the shutter member 111 in the closed position is determined by at least one of the multiple rotating shutters 112b abutting against the shutter abutment portion 111d. The shutter abutment portion 111d constitutes a shutter regulating portion that regulates the position of the shutter member 112 that is biased by the shutter spring 123 and moves in a direction from the open position toward the closed position when the shutter member 112 is attached to the holder 102. With this configuration, the position of the shutter member 112 in the closed position can be fixed every time it moves to the closed position. This allows the detection surface 120 to maintain stable anti-soiling properties, and reduces the risk of image defects occurring due to toner stains on the detection surface 120 preventing color shift correction and density correction from being performed correctly.

[0058] Note that the portion of the shutter member 112 that abuts against the shutter abutment portion is not limited to being provided on the rotating shutter 112b, but may be provided on the sliding shutter 112a. For example, the leading end of the sliding shutter 112a when moving to the closed position can be made to abut against a shutter abutment portion provided on the holding member 111. Also, the shutter abutment portion against which the shutter member 112 abuts is not limited to being provided on the holding member 111, but may be provided on the housing 110 (frame 115, etc.). In other words, it is sufficient that the shutter abutment portion is provided on the holding body 102 that is composed of the housing 110, the holding member 111, etc.

[0059] On the other hand, in this embodiment, the shutter unit 101 is configured so that when the shutter member 112 is removed from the holder 102 and the transmission member 122 is pulled by the shutter spring 123, the transmission member 122 abuts against the holder 111. That is, the solenoid 119 may be configured so that the plunger 119a can be pulled out. In such a configuration, if the movement of the transmission member 122 is not restricted in a state in which the shutter member 112 is removed from the holder 102, the transmission member 122 may be pulled by the shutter spring 123 and fall off. FIG. 15 is a side view of a part of the inside of the sensor unit 101 in a state in which the shutter member 112 in this embodiment is removed from the holder 102, as viewed from the right side. In this embodiment, a transmission member abutment portion 125 against which the transmission member 122 abuts when the shutter member 112 is removed from the holder 111 and the transmission member 122 is pulled by the shutter spring 123 is provided in the holder 111. The transmission member abutment portion 125 constitutes a transmission member regulating portion that regulates the position of the transmission member 122 biased by the shutter spring 123 when the shutter member 112 is removed from the holder 102. In this embodiment, the transmission member abutment portion 125 is formed in a wall shape. This makes it possible to prevent the transmission member 122 from falling off due to the biasing force of the shutter spring 123. In addition, since the transmission member 122 is fixed by being pressed against the transmission member abutment portion 125 by the biasing force of the shutter spring 123, the shutter member 112 can be attached to the holder 102 in a stable state. This makes it easy to attach the shutter member 112 to the holder 102.

[0060] The transmission member abutment portion against which the transmission member 122 abuts is not limited to a wall shape, and may be, for example, a shaft shape or a rib shape against which one or more contact portions abut.

[0061] 16, the transmission member regulating portion 125 may have a receiving portion 128 that receives a force from the transmission member 122 corresponding to the transmission member abutting portion, and a buffer member 127 that is disposed between the transmission member 122 and the receiving portion 128. The buffer member 127 can be fixed to the surface of the receiving portion 128 on the transmission member 122 side. This can reduce the impact sound when the transmission member 122 abuts against the transmission member abutting portion. The buffer member 127 can be an elastic member or a flexible member such as a sponge (foamed elastic body) made of foamed rubber or the like, or a felt or a nonwoven fabric made of elastic or flexible fibers. FIG. 16 is an enlarged side view of the periphery of the transmission member 122 of the sensor unit 101 provided with the buffer member 127, viewed from the right side.

[0062] Here, in this embodiment, as described above, in a state where the shutter member 112 is attached to the holder 102, the position of the shutter member 112 is determined and the transmission member 122 comes to rest. On the other hand, in this embodiment, as described above, in a state where the shutter member 112 is detached from the holder 102, the position of the transmission member 122 is determined and the transmission member 122 comes to rest. Thus, in this embodiment, the position at which the transmission member 122 comes to rest when pulled by the shutter spring 123 differs between a state where the shutter member 112 is attached to the holder 102 and a state where the shutter member 112 is not attached. That is, as described above, in a state where the shutter member 112 is detached from the holder 102, that is, when the transmission member 122 and the shutter member 112 are connected, the position of the shutter member 112 is determined by the transmission member 122. On the other hand, in a state where the shutter member 112 is attached to the holder 102, that is, in a state where the image forming apparatus 100 is in operation, it is desired to improve the positional accuracy of the shutter member 112 in the closed state and to improve the antifouling properties of the detection surface 120. In this state, if the position of the shutter member 112 is determined by determining the position of the transmission member 122, there is a possibility that the positional accuracy of the shutter member 112 in the closed state will decrease depending on the degree of dimensional error of the shutter member 112 and the transmission member 122.

[0063] Therefore, in this embodiment, the rest position of the transmission member 122 when pulled by the shutter spring 123 is made different between the state in which the shutter member 112 is attached to the holder 102 and the state in which the shutter member 112 is not attached as described above. However, the difference in the rest position of the transmission member 122 in the above two states is set to an extent that does not hinder the operation of fitting the positioning hole 112g into the positioning protrusion 122c and inserting each engagement boss 112d into each engagement hole 112e in the attachment work described in the first embodiment.

[0064] Although the description is omitted in the first embodiment, the transmission member restricting portion described in the present embodiment may be provided in the sensor unit 101 in the first embodiment. However, if the plunger 119a is configured not to be pulled out, the sensor unit 101 may not be provided with the transmission member restricting portion described in the present embodiment. Examples of the configuration in which the plunger 119a is not pulled out include a configuration in which the solenoid 119 is provided with a structure that prevents the plunger 119a from being pulled out, and a configuration in which the dimensions are such that the plunger 119a cannot be pulled out even when the shutter spring 123 is in a natural length state. Similarly, although the description is omitted in the first embodiment, the shutter restricting portion described in the present embodiment may be provided in the sensor unit 101 in the first embodiment.

[0065] Thus, in this embodiment, the transmission member 122 is movable along a direction intersecting the movement direction of the movable body 31. In this embodiment, the holder 102 has a transmission member regulating portion 125 that regulates the position of the transmission member 122 biased by the elastic member 123 in a state in which the shutter member 112 is detached from the holder 102. In this embodiment, the transmission member regulating portion 125 is configured as an abutment portion against which the transmission member 122 abuts. The transmission member regulating portion 125 may also be configured to have a receiving portion 128 that receives a force from the transmission member 122, and a buffer member 127 that is arranged between the transmission member 122 and the receiving portion 128. Furthermore, in this embodiment, the holder 102 has a shutter regulating portion 111d that regulates the position of the shutter member 112 that has been forced by the elastic member 123 to move in the direction from the open position toward the closed position when the shutter member 112 is attached to the holder 102, and the position at which the transmission member 122 comes to rest when the position of the transmission member 122 is regulated by the transmission member regulating portion 125 when the shutter member 112 is detached from the holder 102 is different from the position at which the transmission member 122 comes to rest when the position of the shutter member 112 is regulated by the shutter regulating portion 111d when the shutter member 112 is attached to the holder 102.

[0066] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained, and it is also possible to prevent the transmission member 122 from falling off when the shutter member 112 is removed from the holder 102, which may occur depending on the configuration of the solenoid 119, etc.

[0067] [Example 3] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of embodiment 1, and detailed explanations are omitted.

[0068] FIG. 17 is a schematic side view of the inside of the sensor unit 101 as viewed from the right side, showing the opening and closing mechanism of the shutter member 112 of the sensor unit 101 in this embodiment. In this embodiment, the transmission member 122 is attached to the holding member 111 so as to be rotatable around a transmission member rotation shaft 111e provided on the holding member 111. The plunger 119a of the solenoid 119 is fixed to one end of the transmission member 122 across the transmission member rotation shaft 111e, and the first end 123a of the shutter spring 123 is attached to a first spring attachment portion 122a provided on the other end. Thus, in this embodiment, the transmission member 122 is rotatable around the rotation center, and the first spring attachment portion 122a is provided on the opposite side of the rotation center to the solenoid 119. A second end 123b of the shutter spring 123 is attached to a second spring attachment portion 111a provided on the holding member 111. In this embodiment, the plunger 119 and the tension spring 123 (second spring attachment portion 111a) are disposed on the same side of the transmission member 122 in the opening / closing direction of the sliding shutter 112a (the width direction of the intermediate transfer belt 31). In this embodiment, the sliding shutter 112a moves to the left in FIG. 17 to be disposed in the closed position, and moves to the right in FIG. 17 to be disposed in the open position.

[0069] In this manner, in this embodiment, the transmission member 122 is rotatably supported by the holder 102. This makes it possible to prevent the transmission member 122 from falling off without providing a transmission member regulating portion as described in the second embodiment. Furthermore, by making the transmission member 122 rotatable, it is possible to reduce the frictional resistance between the transmission member 122 and the holder 111 compared to a case in which the transmission member 122 is slid along the opening and closing direction of the sliding shutter 112a. This makes it possible to reduce wear of the transmission member 122 due to repeated use, and to extend the lifespan of the transmission member 122 and the holder 111.

[0070] In addition, the solenoid 119 and the shutter spring 123 may be on the same side of the transmission member 122 in the opening and closing direction of the sliding shutter 112a (as in this embodiment), or on opposite sides. When the solenoid 119 and the shutter spring 123 are on opposite sides of the transmission member 122, the shutter spring 123 may be formed of a compression coil spring or the like to urge the shutter member 112 in the direction from the open position to the closed position.

[0071] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-mentioned embodiments.

[0072] In the above-mentioned embodiment, the shutter member is configured to have a sliding shutter (first shutter member) and a rotating shutter (second shutter member). This allows the opening of the shutter member to be sufficiently covered against the surface of the moving body, thereby obtaining a relatively high level of anti-fouling properties. However, the present invention is not limited to this embodiment. For example, the shutter member may be configured only with a member corresponding to the sliding shutter in the above-mentioned embodiment. In this case, too, a reasonable level of anti-fouling properties can be obtained by moving the opening of the sliding shutter to a position away from the detection surface of the sensor.

[0073] In the above embodiment, the drive source of the shutter member is constituted by a solenoid, but the present invention is not limited to this form. The drive source of the shutter member may be a drive source of another form, such as a motor, that is capable of generating a drive force for moving the shutter member.

[0074] In the above embodiment, the connection between the transmission member and the shutter member is detachably fixed by a screw as a fixing member, but the present invention is not limited to this. The connection between the transmission member and the shutter member may be detachably fixed by other fixing means such as press-fitting or snap-fitting. Also, the connection between the transmission member and the shutter member may not be fixed by the fixing means as described above, but may be connected so as to transmit the driving force by fitting or engagement, and the shutter member may be held movably and detachably by a holder.

[0075] In the above embodiment, the sensor unit detects the adjustment toner image carried and transported on the intermediate transfer body as a moving body (transport body), but the present invention is not limited to this. That is, in the above embodiment, the image forming apparatus is of an intermediate transfer type in which the toner image formed on the image carrier is first transferred to the intermediate transfer body and then secondarily transferred to the recording material. In contrast, there is an image forming apparatus of a direct transfer type in which the toner image formed on the image carrier is directly transferred to the recording material transported by the recording material carrier. The sensor unit may detect the adjustment toner image carried and transported on the recording material carrier as a moving body. An endless belt similar to the intermediate transfer belt in the above embodiment is often used as the recording material carrier.

[0076] In the above embodiment, the sensor unit has a density sensor and a registration sensor, but it may have only a density sensor. The sensor unit may detect an adjustment toner image carried and transported on a moving body such as a photoconductor or an electrostatic recording dielectric. The sensor unit may detect any other adjustment toner image.

[0077] In addition, the intermediate transfer body and the recording material carrier as the moving body are not limited to endless belts, and may be, for example, a drum-shaped body formed by stretching a film (sheet) on a frame, etc. In addition, the photosensitive body as the moving body is not limited to a drum type, and may be an endless belt, etc. [Explanation of symbols]

[0078] 31 Intermediate transfer belt 100 Image forming device 101 Sensor unit 102 Holding body 111 Retaining member 112 Shutter member 112a Slide shutter 112b Rotating shutter 113 Cash register sensor 114 Concentration sensor 119 Solenoid 122 Transmission components 123 Shutter Spring

Claims

1. A moving body configured to carry and move a toner image; a sensor configured to detect a toner image carried on the surface of the moving body; a shutter movably supported between the sensor and the surface of the moving body, the shutter being movable between an open position exposing the sensor to the surface of the moving body and a closed position covering the sensor from the surface of the moving body; a drive source configured to generate a drive force that moves the shutter between the open position and the closed position; a shutter mounting portion to which the shutter is detachably attached and configured to move integrally with the shutter when the shutter moves between the open position and the closed position; a biasing member configured to bias the shutter mounting portion; An image forming apparatus comprising:

2. An image forming apparatus as described in Claim 1, characterized in that the shutter is removable from the shutter mounting portion while the spring member is attached to the shutter mounting portion.

3. An image forming apparatus as described in claim 1, further comprising a screw configured to removably fix the shutter to the shutter mounting portion.

4. An image forming apparatus as described in claim 1, characterized in that it further has a regulating portion configured to abut against the shutter mounting portion and regulate the position of the shutter mounting portion when the shutter is removed from the shutter mounting portion and the shutter mounting portion is moved by being forced by the force member.

5. An image forming apparatus as described in Claim 4, characterized in that it further has a shutter regulating portion configured to abut against the shutter and regulate the position of the shutter when the shutter mounting portion is moved by being forced by the force member while the shutter is attached to the shutter mounting portion.

6. An image forming apparatus as described in Claim 5, characterized in that the first position at which the shutter mounting portion comes to rest when the shutter mounting portion is regulated by the regulating portion is different from the second position at which the shutter mounting portion comes to rest when the shutter is regulated by the shutter regulating portion.

7. An image forming apparatus as described in claim 1, characterized in that the shutter is configured to move between the open position and the closed position by the shutter mounting portion being driven by the drive source.

8. An image forming apparatus as described in claim 1, further comprising a positioning portion provided in the shutter mounting portion and configured to position the shutter on the shutter mounting portion.

9. The image forming apparatus described in Claim 1, characterized in that the moving body is composed of an endless belt stretched by a plurality of tension rollers.

10. A casing portion configured to house the sensor; a holding member supported so as to be movable relative to the casing portion and configured to hold the sensor; and The shutter is held so as to be movable relative to the holding member.

10. The image forming apparatus according to claim 9,

11. An image forming apparatus as described in Claim 10, characterized in that one end of the urging member is fixed to the holding member.

Images