JP2020204741A - Image forming apparatus - Google Patents

Abstract

To improve the efficiency in removing a toner accumulated on a sensor.SOLUTION: An image forming apparatus comprises: a density sensor 24 that has a sensor surface 24S in a planar shape that optically reads a toner image formed on a transfer belt; a shutter 40 that is provided between the transfer belt and the density sensor 24, and rotates on a shutter rotation axis Rc from a shutter open state of allowing the density sensor 24 to perform reading to a shutter closed state of blocking the density sensor 24; a cleaning film 48 that is fixed to the shutter 40 at an upper end being one end, and in association with the rotation of the shutter 40 between the shutter open state and the shutter closed state, is brought into contact with the sensor surface 24S of the density sensor 24 at a lower end being the other end; and a regulating unit that, in the process during which the shutter 40 rotates between the shutter open state and the shutter closed state, regulates the shutter 40 so that the upper end of the cleaning film 48 moves toward the shutter rotation axis Rc.SELECTED DRAWING: Figure 12

Description

The present invention relates to an image forming apparatus, and is suitable for application to a cleaning mechanism of a light receiving surface of a density sensor and a color shift sensor in an electrophotographic color image forming apparatus.

In a conventional image forming apparatus, an image of each color at an end portion in the width direction is imaged at the time of calibration or the like in the vicinity of both ends in the width direction of the transfer belt under the transfer belt provided so as to face the image forming portion of each color. A color shift sensor that detects the misalignment between them is provided. Further, at an intermediate position between the two color shift sensors, a density sensor for detecting the density of the image is provided so that the planar sensor surface is along the horizontal direction with respect to the transport direction orthogonal to the width direction of the transfer belt.

Since these color shift sensors and density sensors are arranged below the transfer belt and face the transfer belt, falling dust and dirt are likely to adhere to the sensor surface located on the upper surface side of the transfer belt. Since the toner attached to the transfer belt drops, the sensor surface is easily soiled.

On the other hand, if the sensor surface becomes dirty, normal detection cannot be performed by each sensor. Therefore, by providing a shutter that closes between the sensor surface and the transfer belt except when detecting, the sensor surface is covered. There is an image forming apparatus that suppresses surface contamination (see, for example, Patent Document 1). Some of the shutters rotate along the arc direction with a rotation axis provided below each sensor as a fulcrum. Further, in the image forming apparatus, a cleaning member which is an elastic body is provided above each sensor on the lower surface of the shutter, and the tip of the cleaning member moves on the sensor surface of each sensor in conjunction with the rotation operation when the shutter opens and closes. Some clean the sensor surface of each sensor by sweeping.

Japanese Unexamined Patent Publication No. 2006-208645 (Fig. 22 etc.)

However, in such an image forming apparatus, since the shutter rotates in an arc shape with respect to the planar sensor surface of the density sensor, there is a possibility that the toner accumulated in the density sensor cannot be sufficiently removed.

The present invention has taken the above points into consideration, and attempts to propose an image forming apparatus capable of improving the removal efficiency of toner accumulated in the sensor.

In order to solve such a problem, the image forming apparatus of the present invention has an image forming portion for forming a toner image and a toner image supporting body for carrying the toner image, and the toner image of the image forming portion is transferred to a medium. An image forming apparatus for printing, which is provided between a sensor having a planar light receiving surface for optically reading a toner image formed on a toner image carrier and a sensor provided between the toner image carrier and the sensor. A rotating member that rotates around the rotating shaft from an open state that enables reading of the sensor to a closed state that shields the sensor, and a closed state and an open state of the rotating member that is fixed to one end side of the rotating member. In the process of rotating between the elastic cleaning member whose other end contacts the light receiving surface of the sensor and the rotating member between the closed state and the open state, one end side of the elastic cleaning member becomes , A regulating part that regulates the rotating member so as to move toward the rotating shaft is provided.

According to the present invention, in the process of rotating the rotating member that rotates in an arc shape about the rotation axis located below the light receiving surface of the sensor from the open state to the closed state, the other end side of the elastic cleaning member. Can be brought into close contact with the planar light-receiving surface of the sensor to remove the toner accumulated on the light-receiving surface.

According to the present invention, it is possible to realize an image forming apparatus capable of improving the removal efficiency of toner accumulated in the sensor.

It is a left side view which shows the whole structure of an image forming apparatus. It is a perspective view which shows the structure (1) of a sensor unit and a transfer belt. It is a rear view which shows the structure (2) of a sensor unit and a transfer belt. The configuration of the density sensor and the cleaning film is shown, (A) is a rear view, and (B) is a left side view. It is an upper perspective view which shows the structure (1) of the shutter in a shutter closed state. It is a lower perspective view which shows the structure (2) of the shutter in a shutter closed state. It is a top view which shows the structure (3) of the shutter in a shutter closed state. It is a perspective view which shows the structure of a sensor part. The configuration of the sensor unit according to the first embodiment is shown, (A) is a rear view, and (B) is a right side view. The operation (1) of the sensor unit according to the 1st Embodiment is shown, and it is the cross-sectional view taken along the arrow AA in FIG. The operation (2) of the sensor unit according to the 1st Embodiment is shown, and it is sectional drawing on the arrow AA in FIG. The operation (3) of the sensor unit according to the 1st Embodiment is shown, and it is sectional drawing on arrow AA in FIG. The operation (4) of the sensor unit according to the 1st Embodiment is shown, and it is sectional drawing on arrow AA in FIG. It is a rear view which shows the warp of a shutter. The configuration of the sensor unit according to the second embodiment is shown, (A) is a rear view, and (B) is a right side view. It is sectional drawing which shows the operation (1) of the sensor unit by 2nd Embodiment. It is sectional drawing which shows the operation (2) of the sensor unit by 2nd Embodiment. It is sectional drawing which shows the operation (3) of the sensor unit by 2nd Embodiment. It is sectional drawing which shows the operation (4) of the sensor unit by 2nd Embodiment. The configuration of the sensor unit according to the third embodiment is shown, (A) is a rear view, and (B) is a right side view. It is sectional drawing which shows the operation (1) of the sensor unit by 3rd Embodiment. It is sectional drawing which shows the operation (2) of the sensor unit by 3rd Embodiment. It is sectional drawing which shows the operation (3) of the sensor unit by 3rd Embodiment. It is sectional drawing which shows the operation (4) of the sensor unit by 3rd Embodiment.

Hereinafter, embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

[1. First Embodiment]
[1-1. Configuration of image forming apparatus]
As shown in FIG. 1, the image forming apparatus 1 is an electrophotographic printer and has a substantially box-shaped apparatus housing 2. Here, the right side in the drawing of the device housing 2 is the front surface, the left side in the drawing is the rear surface, the direction from the front surface to the rear surface of the device housing 2 is the rear direction, the direction from the rear surface to the front surface is the front direction, and the device housing 2 The direction from the lower side to the upper side is upward, the direction from the upper side to the lower side of the device housing 2 is downward, the direction from the front side to the back side in the figure of the device housing 2 is the right direction, and the device housing. The direction from the back side to the front side in the figure of 2 is the left direction.

Inside the device housing 2, there are four color toners (for example, black (K), yellow (Y), magenta (M), and cyan (C)) that are handled by the image forming device 1 on the upper part. ), Four image forming portions 3 (3K, 3Y, 3M and 3C) corresponding to each of) are provided side by side in the front-rear direction along the transport path R of the paper P.

Each image forming unit 3 (3K, 3Y, 3M and 3C) has a photoconductor drum 4 (4K, 4Y, 4M and 4C) and a toner cartridge 5 (5K, 5Y, 5M and 5C). Each image forming unit 3 (3K, 3Y, 3M and 3C) irradiates and exposes the surface of the photoconductor drum 4 (4K, 4Y, 4M and 4C) with light to expose the photoconductor drum 4 (4K, 4Y, After forming an electrostatic latent image on the surface of 4M and 4C), the toner supplied from the toner cartridge 5 (5K, 5Y, 5M and 5C) is attached to the electrostatic latent image to cause the photoconductor drum 4 (5K, 5Y, 5M and 5C). A toner image is formed on the surface of 4K, 4Y, 4M and 4C).

Further, inside the apparatus housing 2, a transfer unit 6 is provided below the image forming unit 3 (3K, 3Y, 3M and 3C). The transfer unit 6 includes a transfer belt 7 which is an annular endless belt movably arranged rearward (to the left in the figure) along the transport path R, and a photoconductor drum 4 (with the transfer belt 7 sandwiched between them). It has transfer rollers 8 (8K, 8Y, 8M and 8C) arranged opposite to each other below 4K, 4Y, 4M and 4C). The transfer belt 7 is a front belt drive roller 15 arranged on the front side and rotationally driven by a belt drive roller (not shown), and a rear belt drive 15 arranged on the rear side and rotated with the rotation of the transfer belt 7. It is stretched over the roller 16.

The transfer roller 8 (8K, 8Y, 8M and 8C) reverses the paper P to the toner when the paper P passes between the photoconductor drum 4 (4K, 4Y, 4M and 4C) and the transfer belt 7. By charging the paper to a polarity, the toner image of each color formed on the photoconductor drum 4 (4K, 4Y, 4M and 4C) is transferred to the paper P.

Further, a tray 9 for accommodating the paper P is provided below the transfer unit 6 at the lower part inside the apparatus housing 2. In the vicinity of the tray 9, a hopping roller 10 is provided to feed the paper P housed in the tray 9 one by one to the transport path R. Further, inside the apparatus housing 2, a transport roller or the like for transporting the paper P is provided on the transport path R between the tray 9 and the transfer unit 6.

Further, inside the apparatus housing 2, a fixing device 11 is provided on the rear side of the transfer unit 6 on the downstream side in the paper transport direction. The fuser 11 has an upper fixing belt 12 and a lower pressure roller 13, and when the paper P passes through a nip portion formed between the fixing belt 12 and the pressure roller 13. By heating and pressurizing the paper P, the toner image is fixed on the paper P.

Further, a stacker 14 for ejecting the paper P is provided at the upper end of the apparatus housing 2. Further, inside the apparatus housing 2, a discharge roller or the like for discharging the paper P to the stacker 14 is provided on the transport path R between the fixing device 11 and the stacker 14. Further, inside the apparatus housing 2, media detection sensors and the like for detecting the paper P are provided at a plurality of locations on the transport path R. Although omitted in FIG. 1, a control unit composed of a CPU (Central Processing Unit) and the like, a motor for driving each roller, and the like are also provided inside the apparatus housing 2. Further, an operation unit or the like for receiving an operation by a user is provided outside the device housing 2.

In such a configuration, the image forming apparatus 1 feeds the paper P housed in the tray 9 one by one into the transport path R by the hopping roller 10. The paper P fed out to the transport path R is transported to the transfer unit 6, and is sequentially conveyed to the image forming units 3K, 3Y, 3M, and 3C by the transfer belt 7 of the transfer unit 6. Here, the image forming portions 3K, 3Y, 3M and 3C form toner images of each color on the surfaces of the photoconductor drums 4K, 4Y, 4M and 4C. The toner images thus formed on the surfaces of the photoconductor drums 4K, 4Y, 4M and 4C are transferred onto the paper P by the transfer rollers 8K, 8Y, 8M and 8C, whereby the color is transferred onto the paper P. A toner image is formed.

The paper P on which the color toner image is formed is conveyed from the transfer unit 6 to the fixing device 11. The fixer 11 fixes the color toner image on the paper P. As a result, the color image is printed on the paper P. After that, the paper P is conveyed to the stacker 14 and discharged onto the stacker 14.

[1-2. Sensor unit configuration]
As shown in FIGS. 2, 3 and 4, the sensor unit 20 is arranged on the lower side of the rear belt drive roller 16 at a position facing the lower surface of the transfer belt 7. The sensor unit 20 mainly has a sensor unit 21 and a shutter 40.

[1-2-1. Sensor unit configuration]
The sensor unit 21 is configured around the frame 60 shown in FIG. 9, and the left side color shift sensor 22L, the right side color shift sensor 22R, the density sensor 24, and the like are attached to the frame 60. Hereinafter, the left side color shift sensor 22L and the right side color shift sensor 22R are also collectively referred to as a color shift sensor 22.

The frame 60 (FIG. 9) is formed by bending a metal plate and has a shape like an uppercase letter "U" when viewed from the rear, and the main body portion 60a, the shutter support portion 60bL, and the shutter support portion 60bR are formed. Has been done. The main body 60a has a predetermined width in the front-rear direction and extends along the left-right direction. The shutter support portions 60bL and 60bR are bent upward from the left end portion and the right end portion of the main body portion 60a, respectively. The shutter support portions 60bL and 60bR move the shutter 40 in the shutter rotation direction Dh (FIGS. 5 and 6) by inserting the shutter fulcrum portion 43 (FIGS. 5 and 6) of the shutter 40 from the inside in the left-right direction. A cylindrical shutter support hole 60ba that rotatably supports along the line is bored.

Further, as shown in FIGS. 5 and 6, a solenoid 42 for generating a driving force and a rotating lever 50 are attached to the frame 60. In FIGS. 5 to 7, the frame 60 is not shown and is omitted. The right end of the lever 50 is connected to the suction portion 42a of the solenoid 42, and the left end of the lever 50 can rotate along the lever rotation direction Dl with the post 51 fixed to the frame 60 as a fulcrum.

The color shift sensors 22 (FIGS. 2 and 3) are symmetrically arranged at the left and right ends of the sensor unit 20 so as to face both ends in the width direction of the transfer belt 7. Further, the left side color shift sensor 22L and the right side color shift sensor 22R are each mounted on a substrate fixed to a support member in a state of being exposed upward. The color shift sensor 22 optically detects a pattern (toner image) for color shift detection transferred to the transfer belt 7 by each image forming unit 3 (FIG. 1). Specifically, each of the left side color shift sensor 22L and the right side color shift sensor 22R has a light emitting element and a light receiving element. The light emitting element irradiates the pattern for detecting color shift formed on the transfer belt 7 with light. The light receiving element detects the reflected light from the pattern for detecting color shift and outputs a voltage signal according to the intensity of the reflected light.

The left side color shift sensor 22L and the right side color shift sensor 22R are covered with the left side sensor cover 26L and the right side sensor cover 26R, respectively. The left side sensor cover 26L and the right side sensor cover 26R are molded products made of a transparent plastic material, and are locked to the frame 60.

The concentration sensor 24 faces the central portion in the width direction of the transfer belt 7 at the left and right central portions of the sensor unit 20, and the sensor surface 24S is inclined in the horizontal direction with respect to the surface (lower surface) of the transfer belt 7 as shown in FIG. It is fixed to the rear surface side of the density sensor substrate 28 by soldering so as to be performed. Further, the density sensor 24 is provided so that the planar sensor surface 24S is along the horizontal direction with respect to the front-rear direction. The concentration sensor substrate 28 has a thin plate shape that is thin in the front-rear direction and extends along the left-right direction. The density sensor 24 optically detects a density detection pattern (toner image) transferred from each image forming unit 3 to the transfer belt 7. Specifically, the density sensor 24 has a light emitting element and a light receiving element. The light emitting element irradiates a pattern for density detection formed on the transfer belt 7 with light from the central portion in the left-right direction of the sensor surface 24S. The light receiving element detects the reflected light from the density detection pattern at both ends of the sensor surface 24S in the left-right direction, and outputs a voltage signal corresponding to the intensity of the reflected light.

On the rear surface side of the concentration sensor substrate 28, at the upper end portion of the position facing the concentration sensor 24 in the left-right direction and the right side of the concentration sensor 24, an FG sheet metal 30 which is a metal plate is attached to the frame 60 (FIG. 9) is fastened together with the concentration sensor board 28 with a screw.

The FG sheet metal 30 comes into contact with the cleaning film 48 (described later) in a state where the shutter 40 is opened and the sensor surface 24S is exposed, and static electricity is released to the outside through the frame 60 (FIG. 9). It prevents noise from entering the signal of the density sensor 24. The FG sheet metal 30 has a shape in which the capital letter "U" is rotated by 180 [°] when viewed from the left side, and the substrate fixing portion 31 and the holding portion 32 are formed. As shown in FIG. 10, the substrate fixing portion 31 extends from the lower side of the upper end portion of the concentration sensor substrate 28 to the upper side of the upper end portion of the concentration sensor substrate 28 along the vertical direction in parallel with the concentration sensor substrate 28. It is fixed to the concentration sensor board 28.

In the holding portion 32, the FG sheet metal 30 is bent toward the front lower side at the upper end portion of the substrate fixing portion 31, and the front end thereof extends to the front side of the concentration sensor substrate 28. The holding portion 32 is formed with a holding portion 32a when opened and a holding portion 32b when closed.

The open holding portion 32a bends at a right angle from the upper end portion of the substrate fixing portion 31 and extends forward along the horizontal direction to above the front surface of the concentration sensor substrate 28. Therefore, on the upper surface of the open holding portion 32a, a flat open holding portion surface 32aS along the horizontal direction is formed.

The closed holding portion 32b is bent by about 45 [°] from the front end portion of the open holding portion 32a, is inclined in the horizontal direction toward the front lower side, and extends to the front side of the concentration sensor substrate 28. Therefore, on the upper surface of the closed holding portion 32b, a planar shape closed holding portion surface 32bS that inclines downward with respect to the horizontal direction is formed.

Further, a sliding portion 32c, which is a bent corner portion, is formed between the holding portion surface 32aS when opened and the holding portion surface 32bS when closed.

[1-2-2. Shutter configuration]
As shown in FIGS. 5, 6 and 7, the shutter 40 is provided between the sensor portion 21 and the transfer belt 7 and is formed by resin molding to form the main body portion 40a, the support column 40bL and the support column 40bR. Has been done. Further, as shown in FIG. 9A, the shutter 40 is formed in a shape in which the central portion in the longitudinal direction (left-right direction) is curved so as to be curved downward in a natural state in which no external force is applied. There is.

The main body portion 40a has a predetermined width in the front-rear direction, extends along the left-right direction, and is curved so that the central portion in the front-rear direction bulges upward in the right side view (FIG. 9B). .. The columns 40bL and 40bR extend downward from the left end and the right end of the main body 40a, respectively. The columns 40bL and 40bR have a cylindrical shutter fulcrum 43 that fits into the shutter support hole 60ba (FIG. 9) of the frame 60 at the lower end. The shutter 40 is rotatably supported along the shutter rotation direction Dh by fitting the shutter fulcrum portion 43 into the shutter support hole 60ba.

Therefore, the shutter 40 has a shutter closed state that covers the upper part of the sensor surface 24S of the concentration sensor 24 as shown in FIG. 10 and a shutter open state that opens the upper part of the sensor surface 24S of the concentration sensor 24 as shown in FIG. The space is rotated along the shutter rotation direction Dh with the shutter rotation shaft Rc, which is the rotation shaft of the shutter fulcrum portion 43, as a fulcrum. In the following, the direction in which the shutter 40 rotates from the shutter closed state to the shutter open state is also referred to as the shutter opening direction Dha, and the direction in which the shutter 40 rotates from the shutter open state to the shutter closed state is the shutter closing direction Dhb. Also called.

The shutter 40 is urged in the shutter closing direction Dhb by a compression spring 45. Further, in the lever 50 described above, when the solenoid 42 is energized and the suction portion 42a is sucked in the suction portion suction direction Dsa which is the right direction of the suction portion movement direction Ds along the left-right direction, the left end portion is the lever rotation direction Dl. By rotating in the contact surface proximity direction Dla close to the lever contact surface 40c, which is a part of the rear surface of the shutter 40, the lever contact surface 40c is moved to the shutter closing direction Dhb, which is the return direction thereof. It is pressed so as to rotate in the shutter opening direction Dha against the urging force of the compression spring 45. As a result, the shutter 40 rotates in the shutter opening direction Dha.

In the vicinity of the left side color shift sensor 22L and the right side color shift sensor 22R in the shutter 40, cleaning blades 47L and 47R for cleaning the light receiving surfaces of the left side color shift sensor 22L and the right side color shift sensor 22R are provided. The sensor 22 is fixed so that it can be contacted with a predetermined angle for cleaning the light receiving surface of the sensor 22.

Further, the cleaning film 48 is fixed to the lower surface side of the main body 40a of the shutter 40, that is, the sensor facing surface 40aS side facing the sensor surface 24S of the density sensor 24 in the vertical direction. The cleaning film 48 can sweep (remove) the toner deposited on the sensor surface 24S of the density sensor 24 by sliding it on the sensor surface 24S in a state where the lower end side, which is one end side, is in contact with the sensor surface 24S. As described above, for example, a material having appropriate elasticity such as a polyester Mylar film having an appropriate thickness is used, and the lower end side is in contact with the sensor surface 24S. The cleaning film 48 is fixed to the shutter 40 using, for example, an adhesive or double-sided tape.

As shown in FIG. 10, the film holding portion 40ah protrudes downward toward the density sensor 24 from the vicinity of the end portion of the main body portion 40a of the shutter 40 on the shutter closing direction Dhb side. The root portion of the cleaning film 48 is attached to the film holding portion 40ah. Therefore, the film holding portion 40ah prevents the root portion of the flexible cleaning film 48 from bending.

Further, as shown in FIG. 10, on the sensor facing surface 40aS side of the main body 40a of the shutter 40, one shutter rib 54 extending in the front-rear direction is elongated at a portion facing the FG sheet metal 30 (FIG. 8) in the left-right direction. Is integrally molded with the shutter 40. The shutter rib 54 is formed with a protrusion 55 and a recess 56, and is in contact with the holding portion 32 of the FG sheet metal 30. The protrusion 55 is composed of a protrusion 55a and a protrusion 55b.

The protrusion 55a as the first protrusion is formed at the end of the main body 40a on the shutter closing direction Dhb side, and has a length in the front-rear direction of about one-fourth of the short direction (front-back direction) of the main body 40a. An inclined surface is formed which projects from the sensor facing surface 40aS toward the concentration sensor 24 and is inclined toward the recess 56 at the end portion on the Dha side in the shutter opening direction. The protrusion 55a comes into contact with the holding portion 32 of the FG sheet metal 30 in the shutter open state.

The protrusion 55b as the second protrusion is formed at the end of the main body 40a on the Dha side in the shutter opening direction, and has a length in the front-rear direction of about one-fourth of the lateral direction (front-back direction) of the main body 40a. A sloped surface is formed that projects from the sensor facing surface 40aS toward the concentration sensor 24 by the same height as the protrusion 55a, and is inclined toward the recess 56 at the end on the Dhb side in the shutter closing direction. .. The protrusion 55b comes into contact with the holding portion 32 of the FG sheet metal 30 in the shutter closed state.

The recess 56 is formed in the central portion of the main body portion 40a in the lateral direction (front-rear direction), has a length in the front-rear direction about half of the main body portion 40a in the lateral direction, and is formed from the concentration sensor 24 to the sensor facing surface 40aS. It is recessed from the protrusions 55a and 55b toward. The recess 56 comes into contact with the holding portion 32 of the FG sheet metal 30 when transitioning between the shutter open state and the shutter closed state.

The shutter rib 54 is formed so that the recess 56 is cut away from the design standard as a whole. That is, the sensor unit 20 is configured such that the state in which the protrusion 55 is in contact with the open holding portion surface 32aS and the closed holding portion surface 32bS of the holding portion 32 is a design reference.

[1-3. Shutter operation]
In such a configuration, when the image forming apparatus 1 determines that the density correction is necessary, such as immediately after the power of the image forming apparatus 1 is turned on or immediately after the image forming unit 3 or the like is replaced, the image forming apparatus 1 sets the density. The correction process is started and the solenoid 42 is energized. When the solenoid 42 is energized and the suction portion 42a is sucked in the suction portion suction direction Dsa, the left end portion of the lever 50 rotates in the direction close to the contact surface Dla, and the lever contact surface 40c of the shutter 40 is closed. It is pressed so as to rotate in the shutter opening direction Dha against the urging force of the compression spring 45 in the direction Dhb. As a result, the shutter 40 is rotated in the shutter opening direction Dha.

At this time, as shown in FIG. 10, in the shutter closed state before the solenoid 42 is energized, the protrusion 55b rides on the holding portion 32 of the FG sheet metal 30 so as to abut the closed holding portion surface 32bS, that is, the holding portion 32. Lifts the shutter 40 from below. Therefore, the downward warp in the central portion of the shutter 40 in the longitudinal direction is reduced, and the shutter 40 has a substantially linear shape along the left-right direction. As a result, the distance D1 between the sensor shutters, which is the vertical distance between the sensor surface 24S of the density sensor 24 and the shutter 40, is sufficiently maintained. That is, the lower end of the film holding portion 40ah of the shutter 40 is located above the sensor surface 24S of the density sensor 24. As a result, the image forming apparatus 1 can prevent the film holding portion 40ah of the shutter 40 from colliding with the density sensor 24 when the shutter 40 is rotated in the shutter opening direction Dha from the shutter closed state. When the shutter 40 is rotated in the shutter opening direction Dha from the shutter closed state, the cleaning film 48 comes into contact with the density sensor 24, but the cleaning film 48 is flexible and therefore bends to the density sensor 24. It rides on the sensor surface 24S of the density sensor 24 without being caught.

From the shutter closed state, until immediately after the solenoid 42 is energized, the shutter 40 starts to rotate in the shutter opening direction Dha, and the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24 as shown in FIG. The holding portion 32 lifts the shutter 40 by riding so that the protrusion 55b comes into contact with the closing holding portion surface 32bS of the holding portion 32.

Further, when the shutter 40 rotates in the shutter opening direction Dha, the shutter 40 rotates while the lower surface of the shutter rib 54 abuts on the sliding portion 32c of the holding portion 32, and as shown in FIG. 12, the shutter 40 is in the shutter opening state. In the state between the shutter closed state and the shutter closed state, that is, in the position where the shutter 40 is in the middle of opening, the protrusion 55b does not come into contact with the holding portion 32 of the FG sheet metal 30. Since the central portion of the shutter 40 (FIG. 9 (A)) facing the density sensor 24 in the longitudinal direction is curved toward the lower side, that is, the density sensor 24, the shutter 40 cannot be lifted from the lower side. The portion facing the density sensor 24, which is the central portion in the longitudinal direction in the above, is lowered.

At this time, the film sensor penetration amount D2, which is the vertical distance between the lower end of the cleaning film 48 and the sensor surface 24S of the density sensor 24, that is, the cleaning film 48 is not in contact with the density sensor 24 in a natural state. In some cases, the amount of overlap with the density sensor 24, that is, the amount of penetration is sufficiently maintained. That is, when the cleaning film 48 is not in contact with the sensor surface 24S from the upper end of the cleaning film 48 rather than the distance from the upper end (root) of the cleaning film 48 to the sensor surface 24S of the density sensor 24. The distance to the lower end (tip) in the natural state is longer. In other words, when the cleaning film 48 is in a natural state, the lower end (tip) of the cleaning film 48 is located below the sensor surface 24S. As a result, the image forming apparatus 1 can bring the cleaning film 48 into contact with the sensor surface 24S of the density sensor 24. Further, in the density sensor 24, the sensor surface 24S is inclined in the left-right direction (longitudinal direction) with respect to the horizontal direction, whereas the cleaning film 48 is natural at all positions in the longitudinal direction of the density sensor 24. When in this state, the lower end is located below the sensor surface 24S. At this time, the recess 56 rides so as to abut the sliding portion 32c in the holding portion 32, that is, the holding portion 32 supports the recess 56 from below, so that the central portion in the longitudinal direction of the shutter 40 is further downward. You can prevent it from warping.

Further, when the shutter 40 rotates in the shutter opening direction Dha, as shown in FIG. 13, the cleaning film 48 and the FG sheet metal 30 come into contact with each other, and the shutter 40 is in the shutter opening state. At this time, the cleaning film 48 is perpendicular to the sensor surface 24S of the density sensor 24 except for the bent portion at the lower end. At this time, the protrusion 55a rides on the holding portion 32 so as to come into contact with the opening holding portion surface 32aS, that is, the holding portion 32 lifts the shutter 40 from below. As a result, the shutter 40 is lifted and the amount of deflection at the lower end of the cleaning film 48 is reduced, so that the sensor optical shaft 24a of the light emitting element that emits light from the density sensor 24 and the lower end of the cleaning film 48 are in the front-rear direction. The distance D3 between the sensor optical axis films, which is the interval between the two, is sufficiently maintained. In this shutter open state, the protrusion 55a comes into contact with the open holding portion surface 32aS having a flat shape along the horizontal direction, so that the shutter is in a stable state.

In this way, the image forming apparatus 1 cleans the sensor surface 24S of the density sensor 24 and the upper surface of each color shift sensor 22 by opening the shutter 40, and then performs density correction and color shift correction. When the correction is completed, the image forming apparatus 1 ends the energization of the solenoid 42. When the energization of the solenoid 42 is completed and the suction portion 42a moves in the suction portion return direction Dsb, the left end portion of the lever 50 rotates in the contact surface separation direction Dlb. As a result, the shutter 40 rotates in the shutter closing direction Dhb by the urging force of the compression spring 45 to close, and returns to the shutter closed state.

[1-4. Effect, etc.]
Conventionally, when the shutter 40 moves from the shutter closed state to the shutter open state along an arc, when the vertical position of the shutter 40 is brought close to the density sensor 24 in order to bring the cleaning film 48 into contact with the sensor surface 24S, the film When the vertical distance between the lower end of the holding portion 40ah and the sensor surface 24S of the concentration sensor 24 is narrowed, and the central portion in the longitudinal direction of the shutter 40 is warped downward, the shutter 40 is released from the shutter closed state. When starting to rotate in the opening direction Dha, there is a possibility that the density sensor 24 may physically interfere with the normal operation.

On the other hand, it is conceivable to move the shutter 40 upward so that the film holding portion 40ah of the shutter 40 does not interfere with the density sensor 24, but in that case, the shutter 40 arcs from the shutter closed state to the shutter open state. When moving along the line, the lower end of the cleaning film 48 may not reach the sensor surface 24S and may not come into contact with the sensor surface 24S, resulting in deterioration of the toner removal performance.

On the other hand, the image forming apparatus 1 forms the shutter rib 54 on the sensor facing surface 40aS side of the shutter 40 and forms the holding portion 32 on the FG sheet metal 30. In the shutter closed state (FIG. 10), the protrusion 55b of the shutter rib 54 is formed. The lower end surface of the FG sheet metal 30 was brought into contact with the closed holding portion surface 32bS. Therefore, the image forming apparatus 1 protrudes from the shutter closed state (FIG. 10) until the shutter 40 rotates in the shutter opening direction Dha and the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24 (FIG. 11). The shutter 40 is lifted by bringing 55b into contact with the holding portion surface 32bS at the time of closing, and the lower end portion of the film holding portion 40ah is positioned above the sensor surface 24S to separate them so that a sufficient distance D1 between the sensor shutters can be secured. As a result, when the shutter 40 starts to open from the shutter closed state (FIG. 10), the image forming apparatus 1 prevents the film holding portion 40ah from interfering with the density sensor 24 and normally operates the shutter 40 in the shutter opening direction Dha. Can be made to.

Further, the image forming apparatus 1 forms a recess 56 on the shutter closing direction Dhb side of the protrusion 55b on the shutter rib 54 so as to be separated from the protrusion 55b from the shutter rotation axis Rc, that is, a recess 56 having a low height, and the shutter is formed. During the transition from the closed state (FIG. 10) to the shutter open state (FIG. 13), the shutter 40 is rotated while the lower end surface of the recess 56 of the shutter rib 54 is in contact with the sliding portion 32c of the FG sheet metal 30. did. Therefore, in the image forming apparatus 1, after the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24, the shutter 40 rotates in the shutter opening direction Dha, and the shutter 40 rotates under the protrusion 55a in the stage before the shutter opening state (FIG. 13). The protrusion 55b is removed from the closed holding portion surface 32bS until the end surface abuts on the open holding portion surface 32aS of the FG sheet metal 30, that is, in a state where the lower end portion of the cleaning film 48 passes through the sensor surface 24S of the concentration sensor 24. By bringing the separated sliding portion 32c into contact with the recess 56, the position of the shutter 40, that is, the upper end portion of the cleaning film 48 can be lowered, and the film sensor penetration amount D2 can be sufficiently secured. As a result, in the image forming apparatus 1, after the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24, the lower end portion of the cleaning film 48 continues to be in contact with the sensor surface 24S of the density sensor 24 without being separated. The shutter 40 can be operated in the shutter opening direction Dha while maintaining the above, and the toner on the sensor surface 24S can be cleaned. Thus, the image forming apparatus 1 can stably correct the density by accurately detecting the density.

Further, the image forming apparatus 1 brings the lower end surface of the protrusion 55a of the shutter rib 54 into contact with the opening holding portion surface 32aS of the FG sheet metal 30 in the shutter open state (FIG. 13). Therefore, in the shutter open state (FIG. 13), the image forming apparatus 1 brings the protrusion 55a into contact with the holding portion surface 32aS at the time of opening to lift the shutter 40, and reduces the amount of bending of the lower end of the cleaning film 48 to cause bending. The distance D3 between the sensor optical axis films can be sufficiently secured so as not to be too much. As a result, the image forming apparatus 1 prevents the lower end of the cleaning film 48 from touching the sensor optical axis 24a in the shutter open state (FIG. 13), and accurately corrects the density without increasing the output of the density sensor 24. Can be done.

Here, the image forming apparatus 1 is shuttered by the regulating unit 62 so that the upper end side of the cleaning film 48 moves toward the shutter rotation axis Rc in the process of rotating the shutter 40 from the shutter open state to the shutter closed state. It can be said that 40 is regulated, that is, guided. The regulation portion 62 is composed of a shutter rib 54 as an abutting portion of the shutter 40, a holding portion 32 of the FG sheet metal 30, and a shutter 40. Since the shutter 40 has a downward warp at the central portion in the longitudinal direction, the warp functions as a part of the regulating portion 62.

In the above configuration, in the image forming apparatus 1, the shutter 40 rotates in an arc shape about the shutter rotation axis Rc located below the flat sensor surface 24S along the horizontal direction in the density sensor 24. As the shutter 40 rotates, the lower end of the cleaning film 48 moves so as to draw an arc rather than parallel to the sensor surface 24S, so that the distance between the density sensor 24 and the shutter 40 and the cleaning film 48 changes. It has become.

Further, the image forming apparatus 1 holds the protrusion 55b at the time of closing in the shutter closed state (FIG. 10) with respect to the portion of the shutter 40 that rotates in an arc shape with respect to the sensor surface 24S along the horizontal direction and faces the sensor surface 24S. The warp of the shutter 40 is lifted by abutting the portion surface 32bS to form a linear shape. Further, in the image forming apparatus 1, the protrusion 55b is formed between the shutter open state and the shutter closed state, that is, at a position (FIG. 12) where the sensor surface 24S is cleaned by the cleaning film 48 in the process of opening and closing the shutter 40. The central portion in the longitudinal direction is lowered so as not to abut on the holding portion 32 and the shutter 40 is returned to the natural state, and the shutter 40 is guided so as to bring the cleaning film 48 closer to the density sensor 24. Further, in the shutter open state (FIG. 13), the image forming apparatus 1 raises the warp of the shutter 40 to form a linear shape by bringing the protrusion 55a into contact with the holding portion surface 32aS at the time of opening.

Therefore, the image forming apparatus 1 is less susceptible to the influence of manufacturing dimensional error and assembly error of parts, keeps the distance between the density sensor 24 and the shutter 40 within a necessary range during the opening / closing operation of the shutter 40, and ensures cleanability. Therefore, while keeping the distance between the sensor surface 24S of the density sensor 24 and the cleaning film 48 close to each other, the shutter 40 does not interfere with the density sensor 24 when the shutter 40 rotates from the shutter closed state to the shutter opening direction Dha. At the same time, it is possible to suppress the bending of the lower end portion of the cleaning film 48 in the shutter open state so as not to interfere with the sensor optical axis 24a.

Further, the image forming apparatus 1 moves the shutter 40 by a rotary motion with the shutter rotation shaft Rc as a fulcrum. Therefore, the image forming apparatus 1 can reduce the frictional load and stably move the shutter 40 as compared with the case where the shutter is slid and moved in parallel, so that the sensor surface 24S is stably cleaned. At the same time, the length of the sensor unit 20 in the front-rear direction can be shortened to reduce the size.

Further, here, instead of forming the shutter rib 54 on the shutter 40, the lengths of the columns 40bL and 40bR in the vertical direction are formed to be long, and the curvature of the arc of the movement locus when the shutter 40 moves in an arc shape is increased. As a result, the cleaning film 48 is moved substantially in parallel with the sensor surface 24S of the density sensor 24, and the lower end of the cleaning film 48 is slid while being in stable contact with the sensor surface 24S to clean the sensor surface 24S. It is also possible. However, in that case, the size of the shutter 40 in the vertical direction becomes large, and the sensor unit 20 becomes large.

On the other hand, the image forming apparatus 1 lifts the shutter 40, which rotates in an arc shape, while maintaining the vertical lengths of the columns 40bL and 40bR, in the shutter closed state and the shutter open state, and raises the shutter open state and the shutter. It was lowered at the position where the sensor surface 24S was cleaned between the closed state and the closed state. As a result, the image forming apparatus 1 can stably clean the sensor surface 24S while reducing the size of the shutter 40, that is, the sensor unit 20.

Further, as shown in FIG. 14A, the image forming apparatus 1 has a shape in which the shutter 40 is curved so that the central portion in the longitudinal direction warps downward toward the density sensor 24. Here, in the shutter closed state and the shutter open state, the state in which the central portion of the shutter 40 facing the density sensor 24 in the longitudinal direction is separated upward from the density sensor 24 is the separated state shown by the broken line in FIG. 14 (A). Let it be SU1. In this state, the shutter 40 is in a state of being substantially horizontal as a whole because the downward warp in the central portion in the longitudinal direction is lifted.

Further, when the sensor surface 24S is cleaned with the cleaning film 48, the shutter 40 is in a natural state in which the central portion in the longitudinal direction cannot be lifted and is in a state close to the density sensor 24 (A). It becomes the proximity state SD1 shown by the solid line. In this state, the shutter 40 is in a state in which the central portion in the longitudinal direction is warped downward with respect to the horizontal direction as a whole.

On the other hand, as shown in FIG. 14 (B), if the shutter 40 is formed in a curved shape so that the central portion in the longitudinal direction bends upward in the natural state, the shutter is in the shutter closed state and the shutter open state. The state in which the central portion in the longitudinal direction facing the concentration sensor 24 in 40 is separated upward from the concentration sensor 24 is the separated state SU2 shown by the broken line in FIG. 14 (B). In this state, the central portion of the shutter 40 in the longitudinal direction is lifted, and the central portion in the longitudinal direction is warped upward with respect to the substantially horizontal direction as a whole.

Further, when the sensor surface 24S is cleaned with the cleaning film 48, the shutter 40 is in a natural state because the central portion in the longitudinal direction cannot be lifted, and is in a state close to the density sensor 24 (B). It becomes the proximity state SD2 shown by the solid line. In this state, the shutter 40 is in a state substantially along the horizontal direction as a whole. At this time, based on the proximity state SD2, the separation state SU2 is warped by the amount of upward warp W1 in the vertical direction. That is, when the shutter 40 shifts from the proximity state SD2 to the separation state SU2, a space is required by the amount of the upward warp amount W1 from the state in which the shutter 40 extends linearly along the horizontal direction.

On the other hand, as shown in FIG. 14A, the image forming apparatus 1 has a shape in which the shutter 40 is naturally curved so that the central portion in the longitudinal direction warps downward toward the density sensor 24. Therefore, as shown in FIG. 14B, the image forming apparatus 1 has a shutter 40 having a shape in which the central portion in the longitudinal direction is curved upward in the natural state. And when the cleaning film 48 is to be brought closer to the density sensor 24, it can be brought closer to the density sensor 24 than in the horizontal direction, and conversely, the shutter 40 and the cleaning film 48 are to be separated from the density sensor 24. In this case, since the central portion of the shutter 40 in the longitudinal direction is originally warped downward in the natural state, the central portion in the longitudinal direction may be lifted so as to follow the horizontal direction. Therefore, the image forming apparatus 1 can contribute to space saving by the amount of the upward warp amount W1.

According to the above configuration, the image forming apparatus 1 has an image forming unit 3 for forming a toner image and a transfer belt 7 for supporting the toner image, and the paper P using the toner image of the image forming unit 3 as a medium. A density sensor 24 having a sensor surface 24S as a planar light receiving surface for optically reading a toner image formed on the transfer belt 7, and a density sensor 24 having a transfer belt 7 and a density. A shutter rotation shaft as a rotation shaft is provided between the sensor 24 and the shutter open state as an open state that enables reading of the density sensor 24 to a shutter closed state as a closed state that shields the density sensor 24. The shutter 40 that rotates around Rc and the upper end side that is one end side are fixed to the shutter 40, and the lower end that is the other end side as the shutter 40 rotates between the shutter open state and the shutter closed state. In the process of rotating the cleaning film 48 whose side is in contact with the sensor surface 24S of the density sensor 24 and the shutter 40 between the shutter open state and the shutter closed state, the upper end side of the cleaning film 48 is the shutter rotation shaft Rc. A regulating unit 62 that regulates the shutter 40 is provided so as to move toward.

As a result, in the image forming apparatus 1, the shutter 40, which rotates in an arc shape about the shutter rotation axis Rc located below the sensor surface 24S of the density sensor 24, rotates from the shutter open state to the shutter closed state. In the process, the lower end side of the cleaning film 48 can be brought into close contact with the planar sensor surface 24S of the density sensor 24 to remove the toner accumulated on the sensor surface 24S.

[2. Second Embodiment]
[2-1. Configuration of image forming apparatus]
The image forming apparatus 101 (FIG. 1) according to the second embodiment has a sensor unit 120 (FIG. 15) that replaces the sensor unit 20 (FIG. 9) as compared with the image forming apparatus 1 according to the first embodiment. Although they differ in that they have, they are configured in the same way in other respects.
[2-2. Sensor unit configuration]
As shown in FIG. 15 in which the members corresponding to those in FIG. 9 are designated by the same reference numerals, the sensor unit 120 according to the second embodiment has a shutter 40 as compared with the sensor unit 20 according to the first embodiment. Although the shutter 140 is different in that the frame 160 is provided instead of the frame 60, the other points are similarly configured.

[2-2-1. Frame composition]
The frame 160 (FIG. 15) differs from the frame 60 (FIG. 9) in that the shutter support portions 160bL and 160bR are provided instead of the shutter support portions 60bL and 60bR, but the other points are the same. It is configured in. The shutter support portions 160bL and 160bR are provided with a shutter support hole 160ba instead of the shutter support hole 60ba, and at the upper end portion, the spring upper end support portion 64 projects outward in the left-right direction. The shutter support hole 160ba is an elongated hole along the vertical direction, and the shutter 140 is rotatably supported along the shutter rotation direction Dh by inserting the shutter fulcrum portion 143 of the shutter 140 from the inside in the left-right direction. At the same time, the shutter 140 is movably supported along the vertical direction. The upper end of the compression spring 66 is locked to the spring upper end support portion 64.

[2-2-2. Shutter configuration]
The shutter 140 (FIG. 15) differs from the shutter 40 (FIG. 9) in that the shutter fulcrum portion 143 is provided instead of the shutter fulcrum portion 43, but the other points are similarly configured. There is. Further, as compared with the shutter 40, the shutter 140 has a linear shape in which the central portion in the longitudinal direction does not warp downward and warps in the left-right direction when viewed from the rear. The shutter fulcrum portion 143 is formed to be longer in the left-right direction than the shutter fulcrum portion 43, and protrudes to the outside in the left-right direction from the shutter support hole 160ba. The lower end of the compression spring 66 is locked to the outer end of the shutter fulcrum 143 in the left-right direction. The compression spring 66 is locked to the spring upper end support portion 64 and the shutter fulcrum portion 143 in a state of being compressed more than in the natural state. Therefore, the shutter 140 is urged downward by the restoring force of the compression spring 66 that is about to return to the natural state. The shutter 140 is supported so as to be movable in the vertical direction and rotatably along the shutter rotation direction Dh by slidably fitting the shutter fulcrum portion 143 into the shutter support hole 160ba.

[2-3. Shutter operation]
When performing the density correction process in such a configuration, the image forming apparatus 101 energizes the solenoid 42 and rotates the shutter 140 from the shutter closed state to the shutter opening direction Dha as in the first embodiment.

At this time, as shown in FIG. 16, in the shutter closed state, the protrusion 55b rides so as to abut the closed holding portion surface 32bS in the holding portion 32 of the FG sheet metal 30, that is, the holding portion 32 rides on the closed holding portion surface. By supporting 32bS from below, the distance D1 between the sensor shutters is sufficiently maintained. As a result, the image forming apparatus 101 can prevent the film holding portion 40ah of the shutter 140 from colliding with the density sensor 24 when the shutter 140 is rotated in the shutter opening direction Dha from the shutter closed state.

From the shutter closed state, until the solenoid 42 is energized, the shutter 140 starts to rotate in the shutter opening direction Dha, and the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24 as shown in FIG. The holding portion 32 supports the shutter 140 by riding the protrusion 55b so as to abut the closing holding portion surface 32bS in the holding portion 32.

Further, when the shutter 140 rotates in the shutter opening direction Dha, the shutter 40 rotates while the lower surface of the shutter rib 54 abuts on the sliding portion 32c of the holding portion 32, and as shown in FIG. 18, the shutter 140 is in the shutter opening state. In the state between the shutter closed state and the shutter closed state, the protrusion 55b does not come into contact with the holding portion 32 of the FG sheet metal 30. At this time, when the protrusion 55b is no longer supported by the holding portion 32b when closed, the shutter fulcrum portion 143 moves downward inside the shutter support hole 160ba due to the urging force of the compression spring 66, so that the entire shutter 140 is lowered.

At this time, the film sensor penetration amount D2 is sufficiently maintained. As a result, the image forming apparatus 101 can bring the cleaning film 48 into contact with the sensor surface 24S of the density sensor 24. At this time, the recess 56 rides so as to abut the sliding portion 32c in the holding portion 32, that is, the holding portion 32 supports the recess 56 from below, so that the shutter 140 of the holding portion 32 moves further downward. You can prevent it from moving.

Further, when the shutter 140 rotates in the shutter opening direction Dha, as shown in FIG. 19, the cleaning film 48 and the FG sheet metal 30 come into contact with each other, and the shutter 140 is in the shutter opening state. At this time, the shutter fulcrum portion 143 moves upward inside the shutter support hole 160ba against the urging force of the compression spring 66, so that the entire shutter 140 is raised. At this time, the protrusion 55a rides on the holding portion 32 so as to abut the open holding portion surface 32aS, that is, the holding portion 32 supports the opening holding portion surface 32aS from below, whereby the shutter 140 is lifted. By reducing the amount of deflection at the lower end of the cleaning film 48, the distance D3 between the sensor optical axis films is sufficiently maintained.

In this way, the image forming apparatus 101 cleans the sensor surface 24S of the density sensor 24 and the upper surface of each color shift sensor 22 by opening the shutter 140, and then performs density correction and color shift correction. When the correction is completed, the image forming apparatus 101 ends the energization of the solenoid 42, rotates the shutter 140 in the shutter closing direction Dhb, and returns to the shutter closed state, as in the first embodiment.

[2-4. Effect, etc.]
In the image forming apparatus 1 according to the first embodiment described above, it is assumed that the central portion of the shutter 40 in the longitudinal direction is warped downward, and the holding portion 32 of the FG sheet metal 30 and the shutter rib 54 of the shutter 40 Was in contact with each other.

On the other hand, the image forming apparatus 101 urges the shutter 140 to move toward the density sensor 24, that is, the shutter rotation axis Rc by the compression spring 66, and the shutter support hole 160ba, which is a long hole along the vertical direction. By fitting the shutter fulcrum portion 143 of the shutter 140 into the shutter 140, the shutter 140 can be moved along the shutter rotation direction Dh and the vertical direction in which the shutter 140 is separated from the shutter rotation axis Rc.

Therefore, even when the central portion of the shutter 140 in the longitudinal direction is not warped downward, the image forming apparatus 101 is affected by the urging force of the compression spring 66 when transitioning between the shutter open state and the shutter closed state. , The shutter rib 54 of the shutter 140 is always in contact with the holding portion 32 of the FG sheet metal 30, and the shutter 140 can be moved stably.

As a result, the image forming apparatus 101 keeps the distance between the density sensor 24 and the shutter 140 within a necessary range, and keeps the distance between the sensor surface 24S of the density sensor 24 and the cleaning film 48 close to each other in order to ensure cleanability. When the shutter 140 rotates from the shutter closed state to the shutter opening direction Dha, the shutter 140 can be prevented from interfering with the density sensor 24, and the lower end portion of the cleaning film 48 is suppressed from bending in the shutter open state. It can be prevented from interfering with 24a.

Further, in the image forming apparatus 101, the shutter 140 is controlled by the regulating unit 162 so that the upper end side of the cleaning film 48 moves toward the shutter rotation axis Rc in the process of rotating the shutter 140 from the shutter closed state to the shutter open state. It can be said that it regulates, that is, guides. The regulating portion 162 includes a compression spring 66 as an urging member, a shutter rib 54 of the shutter 140, a holding portion 32 of the FG sheet metal 30, a shutter fulcrum portion 143 of the shutter 140, and a shutter as a long hole portion of the frame 160. It is composed of a support hole 160ba.

In other respects, the image forming apparatus 101 according to the second embodiment can exhibit the same effects as the image forming apparatus 1 according to the first embodiment.

[3. Third Embodiment]
[3-1. Configuration of image forming apparatus]
The image forming apparatus 201 (FIG. 1) according to the third embodiment has a sensor unit 220 (FIG. 20) that replaces the sensor unit 20 (FIG. 9) as compared with the image forming apparatus 1 according to the first embodiment. Although they differ in that they have, they are configured in the same way in other respects.
[3-2. Sensor unit configuration]
As shown in FIG. 20, in which the members corresponding to those in FIG. 9 are designated by the same reference numerals, the sensor unit 220 according to the third embodiment has a shutter 40 as compared with the sensor unit 20 according to the first embodiment. Although the shutter 240 is different in that the frame 260 is provided instead of the frame 60, the other points are similarly configured. Further, in the sensor unit 220, the shutter rib 54 of the shutter 40 and the holding portion 32 of the FG sheet metal 30 are omitted as compared with the sensor unit 20.

[3-2-1. Frame composition]
The frame 260 (FIG. 20) differs from the frame 60 (FIG. 9) in that the shutter support portions 260bL and 260bR are provided in place of the shutter support portions 60bL and 60bR, but the other points are the same. It is configured in. The shutter support portions 260bL and 260bR are provided with a shutter support hole 260ba instead of the shutter support hole 60ba, and a cam groove 68 is formed at the upper side. The shutter support hole 260ba is an elongated hole whose upper end is inclined forward in the vertical direction, and the shutter fulcrum portion 43 of the shutter 240 is inserted from the inside in the horizontal direction to insert the shutter 240 along the shutter rotation direction Dh. The shutter 240 is rotatably supported and the shutter 240 is movably supported in the vertical direction.

The cam groove 68 is formed substantially along an arc shape with the shutter rotation shaft Rc as a fulcrum, and a closed holding portion 68a, an open holding portion 68b, and a transition holding portion 68c are formed, and the shutter rotation described later is performed. The moving portion 70 is slidably inserted.

The closed holding portion 68a is formed at the end of the cam groove 68 on the shutter closing direction Dhb side, has a length in the front-rear direction of about one-third of the front-rear direction of the cam groove 68, and is a transition holding portion 68c. It is separated from the shutter rotation shaft Rc. Further, the closed holding portion 68a is formed with an inclined portion inclined toward the transition holding portion 68c at the end portion on the Dha side in the shutter opening direction. The shutter rotating portion 70 of the shutter 240 is located in the closed holding portion 68a in the shutter closed state.

The open holding portion 68b is formed at the end of the cam groove 68 on the shutter opening direction Dha side, has a length in the front-rear direction of about one-third of the front-rear direction of the cam groove 68, and has a length in the front-rear direction of the cam groove 68. It is separated from the shutter rotation shaft Rc by the same distance as the holding portion 68a when closed. Further, the open holding portion 68b is formed with an inclined portion inclined toward the transition holding portion 68c at the end portion on the shutter closing direction Dhb side. The shutter rotating portion 70 of the shutter 240 is located in the open holding portion 68b in the shutter open state.

The transition holding portion 68c is formed in the central portion of the cam groove 68 in the front-rear direction, has a length in the front-rear direction of about one-third of the front-rear direction of the cam groove 68, and has a closing holding portion 68a and an opening holding portion 68a. It is closer to the shutter rotation shaft Rc than the holding portion 68b. The shutter rotating portion 70 of the shutter 240 is located in the transition holding portion 68c when transitioning between the shutter open state and the shutter closed state.

As described above, the cam groove 68 has a shape in which the transition holding portion 68c is closer to the shutter rotation shaft Rc with respect to the closing holding portion 68a and the opening holding portion 68b.

[3-2-2. Shutter configuration]
The shutter 240 (FIG. 20) differs from the shutter 40 (FIG. 9) in that the shutter rotating portion 70 is provided, but the other points are similarly configured. Further, as compared with the shutter 40, the shutter 240 has a linear shape in which the central portion in the longitudinal direction is not warped downward and is warped in the left-right direction in the rear view. The shutter rotating portion 70 has a cylindrical shape and projects from the left and right side surfaces of the main body portion 40a of the shutter 140 toward the left and right outside, and slides inside the cam groove 68 of the frame 260 along the cam groove 68. The shutter 240 is movable in the vertical direction and the shutter rotation direction by slidably fitting the shutter fulcrum portion 43 into the shutter support hole 260ba and the shutter rotating portion 70 into the cam groove 68. It is rotatably supported along Dh.

[3-3. Shutter operation]
When performing the density correction process in such a configuration, the image forming apparatus 201 energizes the solenoid 42 and rotates the shutter 240 from the shutter closed state to the shutter opening direction Dha as in the first embodiment.

At this time, as shown in FIG. 21, in the shutter closed state, the distance between the sensor shutters D1 is sufficiently maintained because the shutter rotating portion 70 is located at the closing holding portion 68a. As a result, the image forming apparatus 201 can prevent the film holding portion 40ah of the shutter 240 from colliding with the density sensor 24 when the shutter 240 is rotated in the shutter opening direction Dha from the shutter closed state.

From the shutter closed state, until the solenoid 42 is energized, the shutter 240 starts to rotate in the shutter opening direction Dha, and the cleaning film 48 starts to ride on the sensor surface 24S of the density sensor 24 as shown in FIG. 22. By locating the shutter rotating portion 70 at the closing holding portion 68a, the shutter 140 is separated from the density sensor 24.

Further, when the shutter 240 rotates in the shutter opening direction Dha, the shutter rotating portion 70 slides inside the cam groove 68, and as shown in FIG. 23, the shutter 240 is in a state between the shutter open state and the shutter closed state. Then, the shutter fulcrum portion 43 moves downward inside the shutter support hole 260ba, and the shutter rotating portion 70 is located at the transition holding portion 68c, so that the entire shutter 140 is lowered.

At this time, the film sensor penetration amount D2 is sufficiently maintained. As a result, the image forming apparatus 201 can bring the cleaning film 48 into contact with the sensor surface 24S of the density sensor 24. At this time, by locating the shutter rotating portion 70 at the transition holding portion 68c, the frame 260 can prevent the shutter 240 from moving further downward.

Further, when the shutter 240 rotates in the shutter opening direction Dha, as shown in FIG. 24, the cleaning film 48 and the FG sheet metal 30 come into contact with each other, and the shutter 240 is in the shutter opening state. At this time, the shutter fulcrum portion 43 moves upward inside the shutter support hole 260ba, and the shutter rotating portion 70 is located at the opening holding portion 68b, so that the entire shutter 240 is raised. At this time, the shutter 240 is lifted and the amount of deflection at the lower end of the cleaning film 48 is reduced, so that the distance D3 between the sensor optical axis films is sufficiently separated.

In this way, the image forming apparatus 201 cleans the sensor surface 24S of the density sensor 24 and the upper surface of each color shift sensor 22 by opening the shutter 240, and then performs density correction and color shift correction. When the correction is completed, the image forming apparatus 201 ends the energization of the solenoid 42, rotates the shutter 240 in the shutter closing direction Dhb, and returns to the shutter closed state, as in the first embodiment.

[3-4. Effect, etc.]
In the image forming apparatus 1 according to the first embodiment described above, it is assumed that the central portion of the shutter 40 in the longitudinal direction is warped downward, and the holding portion 32 of the FG sheet metal 30 and the shutter rib 54 of the shutter 40 Was in contact with each other.

On the other hand, the image forming apparatus 201 fits the shutter rotating portion 70 into the cam groove 68 and fits the shutter fulcrum portion 43 of the shutter 240 into the shutter support hole 260ba which is a long hole along the vertical direction. The 240 is made movable along the shutter rotation direction Dh and the vertical direction in which the shutter 240 is separated from the shutter rotation axis Rc.

Therefore, even when the central portion of the shutter 240 in the longitudinal direction is not warped downward, the image forming apparatus 201 cams the shutter rotating portion 70 when transitioning between the shutter open state and the shutter closed state. The shutter 240 can be stably moved along the cam groove 68 by sliding the inside of the groove 68.

As a result, the image forming apparatus 201 keeps the distance between the density sensor 24 and the shutter 240 within a necessary range, and keeps the distance between the sensor surface 24S of the density sensor 24 and the cleaning film 48 close to each other in order to ensure cleanability. When the shutter 240 rotates from the shutter closed state to the shutter opening direction Dha, the shutter 240 can be prevented from interfering with the density sensor 24, and the lower end portion of the cleaning film 48 is suppressed from bending in the shutter open state. It can be prevented from interfering with 24a. Further, the image forming apparatus 201 can eliminate the need for the compression spring 45 as in the second embodiment.

Further, in the image forming apparatus 201, the shutter 240 is controlled by the regulating unit 262 so that the upper end side of the cleaning film 48 moves toward the shutter rotation axis Rc in the process of rotating the shutter 240 from the shutter closed state to the shutter open state. It can be said that it regulates, that is, guides. The restricting portion 262 includes a shutter rotating portion 70 of the shutter 240, a cam groove 68 as a guide groove of the frame 260, a shutter fulcrum portion 43 as a sliding portion of the shutter 240, and a long hole portion of the frame 260. It is composed of a shutter support hole 260ba.

In other respects, the image forming apparatus 201 according to the third embodiment can exhibit the same effects as the image forming apparatus 1 according to the first embodiment.

[4. Other embodiments]
In the first embodiment described above, the case where the shutter 40 is formed so that the central portion in the longitudinal direction warps downward has been described. The present invention is not limited to this, and the central portion may be warped downward by pressing the central portion in the longitudinal direction of the shutter with a spring or the like.

Further, in the above-described first embodiment, the case where the heights of the protrusions 55a and 55b with respect to the recesses 56 are the same has been described. The present invention is not limited to this, and the heights of the protrusions 55a and 55b with respect to the recess 56 may be different from each other. In short, the protrusion 55b may have a height at which the lower end of the film holding portion 40ah is located above the density sensor 24 when the projection 55b comes into contact with the holding portion surface 32bS when closed, and the protrusion 55a is open. The lower end of the film holding portion 40ah may be at a height that does not contact the sensor surface 24S of the density sensor 24 and interfere with the sensor optical shaft 24a when it comes into contact with the holding portion surface 32aS. The same applies to the second embodiment.

Further, the holding portion 32 according to the first embodiment described above may be shaped like a cam groove 68 according to the third embodiment and extended forward.

Further, in the above-described first embodiment, the case where one shutter rib 54 is provided on the shutter 40 has been described. The present invention is not limited to this, and the shutter 40 may be provided with an arbitrary number of two or more shutter ribs 54. The same applies to the second embodiment.

Further, in the first embodiment described above, the case where the shutter rib 54 is formed so that the recess 56 is cut with respect to the design standard has been described. The present invention is not limited to this, and the shutter rib 54 may be formed so that the protrusion 55 is piled up with respect to the design standard. In that case, the sensor unit 20 is configured so that the state in which the recess 56 is in contact with the holding portion 32 becomes a design reference. In that case, even if the central portion of the shutter 40 in the longitudinal direction bends more than expected, the protrusion 55 abuts on the holding portion 32, so that the shutter 40 does not bend any more.

Further, in the first embodiment described above, the case where the FG sheet metal 30 has a shape obtained by rotating the uppercase letter "U" by 180 [°] in the left side view has been described. The present invention is not limited to this, and the FG sheet metal 30 may have various shapes such as a curved shape centered on the shutter rotation shaft Rc when viewed from the left side. The same applies to the second embodiment.

Further, in the first embodiment described above, the case where the sensor surface 24S of the density sensor 24 is inclined in the left-right direction with respect to the surface of the transfer belt 7 has been described. The present invention is not limited to this, and the sensor surface 24S of the density sensor 24 may be parallel to the surface of the transfer belt 7 without being inclined in the left-right direction. The same applies to the second and third embodiments.

Further, in the first embodiment described above, the case where the cleaning film 48 is perpendicular to the sensor surface 24S of the density sensor 24 except for the bent portion at the lower end portion is described in the shutter open state. The present invention is not limited to this, and the cleaning film 48 may be tilted with respect to the sensor surface 24S of the density sensor 24 except for the bent portion at the lower end portion in the shutter open state. The same applies to the second and third embodiments.

Further, in the first embodiment described above, the case where the shutter 40 is formed in a curved shape so that the central portion in the longitudinal direction bends downward has been described. The present invention is not limited to this, and the shutter 40 may have a curved shape so that the central portion in the longitudinal direction bends downward due to the manufacturing convenience of resin molding. Further, the shutter 40 is formed in a curved shape so that the central portion in the longitudinal direction bends upward in a natural state, and when the sensor surface 24S is cleaned with the cleaning film 48, the central portion in the longitudinal direction of the shutter 40 is natural. It may be bent downward from the state so that it has a substantially linear shape.

Further, in the above-described embodiment, the case where the present invention is applied to the image forming devices 1, 101 and 201, which are electrophotographic color printers, has been described. The present invention is not limited to this, and may be applied to, for example, an image forming apparatus which is a monochrome printer, an image forming apparatus having a configuration including an intermediate transfer belt, and the like. It may be applied to an image forming apparatus such as a machine. Further, it may be applied to various devices having a mechanism for making a part of the circular motion of the rotating component into a motion different from the circular motion.

Furthermore, the present invention is not limited to each of the above-described embodiments and other embodiments. That is, the scope of the present invention extends to an embodiment in which each of the above-described embodiments and a part or all of the above-mentioned other embodiments are arbitrarily combined, and an embodiment in which a part is extracted. Is.

Further, in the first embodiment described above, the image forming unit 3 as an image forming unit, the transfer belt 7 as a toner image carrier, the density sensor 24 as a sensor, and the shutter 40 as a rotating member. The case where the image forming apparatus 1 as an image forming apparatus is formed by the cleaning film 48 as an elastic cleaning member and the regulating portion 62 as a regulating portion has been described. The present invention is not limited to this, and an image forming apparatus is configured by an image forming portion having various other configurations, a toner image carrier, a sensor, a rotating member, an elastic cleaning member, and a regulating portion. Is also good.

The present invention can be used in an image forming apparatus for printing by forming a toner image by, for example, an electrophotographic method and fixing it on paper.

1, 101, 201 ... Image forming device, 2 ... Device housing, 3 ... Image forming part, 4 ... Photoreceptor drum, 5 ... Toner cartridge, 6 ... Transfer unit, 7 ... Transfer belt, 8 ... Transfer roller, 9 ... Tray, 10 ... Hopping roller, 11 ... Fixer, 12 ... Fixing belt, 13 ... Pressurized roller, 14 ... Stacker, 15 ... Front belt drive roller, 16 ...... Rear belt drive roller, 20, 120, 220 ... Sensor unit, 21 ... Sensor unit, 22L ... Left side color shift sensor, 22R ... Right side color shift sensor, 24 ... Density sensor, 24S ... Sensor Surface, 24a ... Sensor optical axis, 26L ... Left side sensor cover, 26R ... Right side sensor cover, 28 ... Density sensor board, 30 ... FG sheet metal, 31 ... Board fixing part, 32 ... Holding part, 32a ... Opening holding part, 32aS ... Opening holding part surface, 32b ... Closed holding part, 32bS ... Closed holding part surface, 32c ... Sliding part, 40, 140, 240 ... Shutter, 40a Main body, 40aS, sensor facing surface, 40ah, film holding part, 40bL, 40bR, strut, 40c, lever contact surface, 42 ... solenoid, 42a ... suction part, 43, 143 ... Shutter fulcrum, Rc: Shutter rotation shaft, 45: Compression spring, 47L, 47R: Cleaning blade, 48: Cleaning film, 50: Lever, 51: Post, 54: Shutter rib, 55 ... Projection, 55a ... Projection, 55b ... Projection, 56 ... Recession, 60, 160, 260 ... Frame, 60a ... Main body, 60bL, 60bR, 160bL, 160bR, 260bL, 260bR ... Shutter support , 60ba, 160ba, 260ba ... Shutter support hole, 62, 162, 262 ... Regulatory part, 64 ... Spring upper end support part, 66 ... Compression spring, 68 ... Cam groove, 68a ... Holding part when closed , 68b ... Holding part at the time of opening, 68c ... Holding part at the time of transition, 70 ... Shutter rotating part, Ds ... Suction part moving direction, Dsa ... Suction part suction direction, Dsb ... ...... Lever rotation direction, Dla ... Contact surface proximity direction, Dlb ... Contact surface separation direction, Dh ... Shutter rotation direction, Dha ... Shutter opening direction, Dhb ... Shutter closing direction, D1 ... Distance between sensor shutters, D2 …… Film sensor penetration amount, D3 …… Sensor optical axis Distance between films.

Claims (15)

An image forming part that forms a toner image and
A toner image carrier that supports the toner image is provided.
An image forming apparatus that transfers the toner image of the image forming unit to a medium for printing.
A sensor having a planar light-receiving surface that optically reads the toner image formed on the toner image carrier,
A rotating member provided between the toner image carrier and the sensor, which rotates about a rotation axis from an open state that enables reading of the sensor to a closed state that shields the sensor.
An elastic cleaning member whose one end side is fixed to the rotating member and whose other end side comes into contact with the light receiving surface of the sensor as the rotating member rotates between the closed state and the open state.
Regulation that regulates the rotating member so that one end side of the elastic cleaning member moves toward the rotating shaft in the process of rotating the rotating member between the closed state and the open state. An image forming apparatus including a part. The regulatory department
The image forming according to claim 1, wherein in the open state of the rotating member, the rotating member is regulated so that one end side of the elastic cleaning member moves in a direction away from the rotating shaft. apparatus. The regulatory department
The first or second aspect of the present invention is characterized in that, in the closed state of the rotating member, the rotating member is regulated so that the one end side of the elastic cleaning member moves in a direction away from the rotating shaft. The image forming apparatus described. The regulatory department
The image forming apparatus according to claim 3, wherein the one end side of the elastic cleaning member is regulated to be located above the light receiving surface in the closed state of the rotating member. The light receiving surface is
The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus is located between the rotating shaft and the toner image carrier. Claims 1 to 1, wherein the restricting portion includes a holding portion and a contact portion provided on the rotating member and abutting the holding portion in the process of rotating from the closed state to the open state. The image forming apparatus according to any one of claims 3. The contact portion is
In the open state of the rotating member, a first protrusion that comes into contact with the holding portion and
The image forming apparatus according to claim 6, further comprising a second protrusion that comes into contact with the holding portion in the closed state of the rotating member. The rotating member
Between the first protrusion and the second protrusion, the first protrusion and the second protrusion are formed so as to be separated from the rotation axis, and the closed state and the open state are formed. The image forming apparatus according to claim 7, further comprising a recess that comes into contact with the holding portion when rotating between states. The contact portion is
The image forming apparatus according to claim 8, wherein the concave portion is formed so as to be cut from the first protrusion and the second protrusion. The image forming according to any one of claims 7 to 9, wherein the rotating member abuts the first protrusion on a horizontal surface of the holding portion in the open state. apparatus. A support member for supporting the rotating member is further provided.
The support member includes a guide groove that is a part of the regulation portion and
The rotating member
A sliding portion that is a part of the regulating portion that slides along the guide groove in the process of rotating from the closed state to the open state.
It has an elongated hole portion that is a part of the regulation portion into which the rotation shaft is inserted.
The method according to any one of claims 1 to 3, wherein the rotating shaft slides along the elongated hole portion when the sliding portion slides inside the guide groove. Image forming device. A support member that supports the rotating member and
Further provided with an urging member that is a part of the regulating portion that urges the rotating member toward the sensor.
The support member has an elongated hole portion that is a part of the regulation portion into which the rotation shaft is inserted.
The image forming apparatus according to any one of claims 6 to 10, wherein the rotating shaft slides along the elongated hole portion by the urging of the urging member. The sensor is located at the center of the rotating member in the longitudinal direction.
The first aspect of the present invention is characterized in that, when the one end side of the elastic cleaning member is restricted to move toward the rotation axis, the rotating member is deformed toward the sensor in the longitudinal direction. The image forming apparatus described. The claim is characterized in that when the one end side of the elastic cleaning member is restricted to move toward the rotation axis, the rotating member is deformed so as to be curved toward the sensor in the longitudinal direction. Item 13. The image forming apparatus according to item 13. The image forming apparatus according to claim 14, wherein the rotating member has a shape curved toward the sensor in the longitudinal direction.

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