JP6631330B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image by transferring and fixing a toner image on a sheet.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image on a sheet using toner has been known. In such an image forming apparatus, an electrostatic latent image is formed on a photoconductor in accordance with the image, and in a process called development, toner is attached to the electrostatic latent image on the photoconductor by a developing device to form the electrostatic latent image. Is visualized to form a toner image.

  The toner image formed on the photoconductor is primarily transferred to an intermediate transfer member, and secondarily transferred from the intermediate transfer member to a sheet. The sheet on which the toner image has been transferred is transported to a fixing device, and the toner image is fixed on the sheet by heating and pressing.

  By the way, in each process such as the development described above, toner scattering occurs in the image forming apparatus. Therefore, an image forming apparatus provided with a toner collecting unit for collecting the scattered toner has been proposed.

  The toner collecting section is configured to collect the toner in the toner-containing air with a filter. When the amount of toner attached to the filter increases, the toner cannot be held by the filter, and the toner passes through the filter. In order to suppress the discharge of the toner-containing air to the outside, there has been proposed a technique of detecting dirt on a filter and determining a filter replacement time or the like (for example, see Patent Document 1).

  In addition, a technique has been proposed in which toner adhering to a wall surface of an air passage on the downstream side of a filter is detected to determine a filter replacement time or the like (for example, see Patent Document 2). Further, a technique for detecting the amount of dust in an air path with an optical sensor has been proposed (for example, see Patent Document 3).

JP-A-2013-160843 JP 2012-032377 A Japanese Patent No. 2719822

  In the configuration for detecting dust in the air passage, the detection result becomes unstable due to the influence of dirt on the detection portion and dirt on the optical sensor not caused by toner adhesion. If the sensitivity of the optical sensor is increased to solve this problem, erroneous detection often occurs.

  In the configuration that detects toner adhering to the filter and the configuration that detects toner adhering to the inner wall surface of the air path with an optical sensor, the amount of toner adhering to the same location is high, so the sensor output is saturated, and the filter to be set originally Before the end of the service life, a detection result indicating that a predetermined amount of toner is attached is output. In order to solve this, if the sensitivity of the optical sensor is lowered, erroneous detection often occurs.

  The present invention has been made in order to solve such a problem. In addition to applying a sufficient amount of toner for detection, it is also possible to stably detect toner adhesion by suppressing excessive toner adhesion. It is an object of the present invention to provide an image forming apparatus according to the present invention.

In order to solve the above-mentioned problem, the invention according to claim 1 is an image forming unit that transfers toner to a sheet to form an image, and a toner collecting unit that collects toner by sucking toner-containing air in the apparatus. Means, and the toner collecting means includes a detection window projecting outward from a discharge air passage through which the toner-containing air passes, and an optical sensor for detecting toner in the detection window from outside the detection window . comprising a deposition surface which projects detection position by the optical sensor in detection knowledge within the window, adhesion surface, the image forming apparatus composed of at least one inclined surface inclined with respect to the flowing direction of the toner containing air through the exhaust air duct It is.

The invention according to claim 2, detection window is provided on the downstream side of the attachment surface with respect to the flowing direction of the toner containing air through the exhaust air duct, protrude from the inner surface of the discharge air passage, attachment surface of the toner-laden air The image forming apparatus according to claim 1, further comprising a dam unit that guides the user.

  The invention according to claim 3 is the image forming apparatus according to claim 1 or claim 2, wherein the detection window has a part of the attachment surface protruding from the inner surface of the discharge air passage.

  According to a fourth aspect of the present invention, the toner collecting means includes at least one filter for collecting the toner in the toner-containing air, a filter guide protruding from the inner surface of the discharge air passage, and a filter attached to the filter. 4. The image forming apparatus according to claim 2, wherein a height of protrusion of the damming portion is less than or equal to a filter guide. 5.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the optical sensor is arranged so that light entering and exiting is orthogonal to a direction in which the toner-containing air flows through the discharge air path. Device.

  The invention according to claim 6 is the image forming apparatus according to any one of claims 1 to 5, wherein the toner collecting unit includes a cyclone unit configured to centrifuge the toner from the toner-containing air.

  According to the present invention, since a part of the toner-containing air can be guided into the detection window and a necessary and sufficient amount of toner can be attached to the attachment surface, the attachment of the predetermined amount of toner can be reliably detected. This makes it possible to appropriately determine the life of the filter and the like.

1 is a configuration diagram illustrating an example of an image forming apparatus according to the present embodiment. FIG. 2 is a configuration diagram illustrating an example of a toner collection unit according to the exemplary embodiment. FIG. 2 is a configuration diagram illustrating an example of a toner collection unit according to the exemplary embodiment. FIG. 2 is a configuration diagram illustrating an example of a toner detection unit according to the exemplary embodiment. FIG. 2 is a configuration diagram illustrating an example of a toner detection unit according to the exemplary embodiment. FIG. 4 is an explanatory diagram illustrating a flow of air in a toner detection unit. FIG. 9 is a configuration diagram illustrating a modified example of the toner detection unit according to the present embodiment. FIG. 9 is a configuration diagram illustrating a modified example of the toner detection unit according to the present embodiment.

  Hereinafter, an embodiment of an image forming apparatus of the present invention will be described with reference to the drawings.

<Configuration Example of Image Forming Apparatus of Present Embodiment>
FIG. 1 is a configuration diagram illustrating an example of an image forming apparatus according to the present embodiment, and FIGS. 2 and 3 are configuration diagrams illustrating an example of a toner collection unit according to the present embodiment. The image forming apparatus 1A is, for example, an electrophotographic image forming apparatus such as a copying machine. In this example, a full-color image is formed by arranging a plurality of photoconductors in a vertical direction facing one intermediate transfer belt. This is a so-called tandem type color image forming apparatus.

  The image forming apparatus 1A includes a document reading unit 10, an image forming unit 11, a sheet conveying unit 2, a fixing unit 3, and a toner collecting unit 4.

  The document reading unit 10 scans and exposes the image of the document by the optical system of the scanning exposure device, reads the reflected light with a line image sensor, and obtains an image signal. The image forming apparatus 1A may have a configuration in which an automatic document feeder (not shown) that feeds a document is provided at an upper portion.

  The image forming unit 11 is an example of an image forming unit, and includes an image forming unit 11Y that forms a yellow (Y) image, an image forming unit 11M that forms a magenta (M) image, and a cyan (C) image. And an image forming unit 11BK for forming a black (BK) image.

  The image forming unit 11Y includes a photosensitive drum Y and a developing device 12Y, and a charging unit, an optical writing unit, a drum cleaner, and the like (not shown). Similarly, the image forming units 11M, 11C, and 11BK include photoconductor drums M, C, and BK, and developing devices 12M, 12C, and 12BK, and a charging unit, an optical writing unit, and a drum cleaner (not shown).

  A latent image is formed on the photosensitive drum Y by scanning exposure. The developing device 12Y visualizes the latent image on the photoconductor drum Y by developing with a toner. As a result, an image (toner image) of a predetermined color corresponding to yellow is formed on the photosensitive drum Y.

  Similarly, a latent image is formed on the photosensitive drum M by scanning exposure. The developing device 12M visualizes the latent image on the photosensitive drum M by developing with a toner. As a result, a toner image of a predetermined color corresponding to magenta is formed on the photosensitive drum M.

  A latent image is formed on the photosensitive drum C by scanning exposure. The developing device 12C visualizes the latent image on the photosensitive drum C by developing with the toner. As a result, a toner image of a predetermined color corresponding to cyan is formed on the photosensitive drum C.

  A latent image is formed on the photosensitive drum BK by scanning exposure. The developing device 14BK develops a latent image on the photoconductor drum BK by developing with a toner. As a result, a toner image of a predetermined color corresponding to black is formed on the photosensitive drum BK.

  The images formed on the photosensitive drums Y, M, C, and BK are sequentially transferred to predetermined positions on an intermediate transfer belt 16 which is a belt-shaped intermediate transfer member by primary transfer rollers 17Y, 17M, 17C, and 17BK. Transcribed.

  The image of each color transferred on the intermediate transfer belt 16 is transferred by the secondary transfer unit 18 to the sheet P conveyed at a predetermined timing by the sheet conveying unit 2. The secondary transfer unit 18 forms a transfer nip 19 by placing the secondary transfer roller 18a in pressure contact with the intermediate transfer belt 16, and transfers an image to the paper P while transporting the paper P.

  In the secondary transfer unit 18, a positive voltage is applied from the back side of the paper P by the secondary transfer roller 18 a in order to transfer the toner image onto the paper P. As a result, the sheet P that has passed through the secondary transfer unit 18 is charged with the negative electrode on the image forming surface side where the toner is transferred and the positive electrode on the back surface.

  In the present example, the paper transport unit 2 includes a plurality of paper feed trays 21 in which the paper P is stored, and a paper feed unit 21a that feeds out the paper P stored in the paper feed tray 21. The paper transport unit 2 includes a main transport path 23 through which the paper P fed from the paper feed tray 21 is transported, and a reverse transport path 24 that reverses the front and back of the paper P.

  The main transport path 23 constitutes a transport path from the paper feed tray 21 to the paper discharge tray 25. When the external paper feed tray 22 referred to as a manual feed tray is opened and used, the transport path from the external paper feed tray 22 joins the main transport path 23 upstream from the junction of the main transport path 23 and the reverse transport path 24. I do.

  The paper transport unit 2 is a registration roller 26 that corrects the inclination of the paper P, which is called skew, with respect to the paper P transported along the main transport path 23, and the deviation of the position of the paper P in the width direction orthogonal to the transport direction. Is provided. In addition, the paper transport unit 2 includes a loop roller 27 that abuts the paper against the registration roller 26.

  The registration roller 26 is composed of a pair of rollers opposed to each other with the sheet P conveyed through the main conveyance path 23 interposed therebetween, has an axis perpendicular to the direction of conveyance of the sheet P, and rotates along the conveyance direction of the sheet P. I do.

  The loop roller 27 is composed of a pair of rollers facing each other with the sheet P conveyed through the main conveyance path 23 interposed therebetween, and is provided on the upstream side of the registration roller 26 with respect to the conveyance direction of the sheet P. The loop roller 27 has an axis perpendicular to the transport direction of the paper P, and transports the paper P by rotating along the transport direction of the paper P.

  With the registration roller 26 stopped, the paper P is conveyed by the loop roller 27, and the leading end of the paper P abuts against a nip 26a formed by a contact portion of a pair of rollers. By conveying the sheet P until the state is reached, the inclination in the direction along the surface of the sheet P is corrected.

  After the inclination of the paper P is corrected, the registration roller 26 is rotated and driven along the transport direction of the paper P, so that the paper P is nipped and transported. Further, by moving the registration roller 26 in the width direction of the sheet P orthogonal to the transport direction of the sheet P, the position of the sheet P in the width direction is corrected. As described above, a series of sheet position correction operations for correcting the deviation of the position in the width direction while conveying the sheet P is referred to as registration swing.

  The reverse transport path 24 branches off from the main transport path 23 on the downstream side of the fixing unit 3, and includes a switching gate 23 a at a branch point between the main transport path 23 and the reverse transport path 24. The reverse transport path 24 includes a first reverse transport path 24a that branches off from the main transport path 23 and extends in a substantially horizontal direction below the main transport path 23. In the first reverse transport path 24a, the transport direction of the paper P is reversed from the direction of arrow D1 to the direction of arrow D2.

  The reverse transport path 24 branches upward from the first reverse transport path 24a in the transport direction indicated by the arrow D2, and is bent from a second reverse transport path 24b and a second reverse transport path 24b. , And a third reverse transport path 24c extending along the first reverse transport path 24a. Further, the reverse transport path 24 is provided with a fourth reverse transport path 24 d that bends in a substantially U shape from the third reverse transport path 24 c and merges with the main transport path 23.

  In the image forming apparatus 1 </ b> A, an image is formed on the surface of the sheet P that has been transported along the main transport path 23 and passed through the transfer nip 19 and the fixing unit 3, facing upward. When an image is formed on both sides of the sheet P, the sheet P having an image formed on one surface facing upward is conveyed from the main conveyance path 23 to the first reversal conveyance path 24 a of the reversal conveyance path 24. , The image forming surface faces downward.

  The sheet P transported to the first reverse transport path 24a is transported from the second reverse transport path 24b to the third reverse transport path 24c, so that the image forming surface faces upward. Then, the sheet P transported to the third reverse transport path 24c is transported from the fourth reverse transport path 24d to the main transport path 23, so that the image forming surface faces downward. As a result, the sheet P is turned upside down, and an image can be formed on another surface facing upward.

  The fixing unit 3 is an example of a fixing unit, and performs a fixing process for fixing an image on the sheet P on which the image has been transferred. The fixing unit 3 includes a fixing roller 31 and a fixing roller 32 as a pair of fixing members arranged so as to be pressed against each other. The fixing nip 33 is formed by pressing the fixing roller 31 and the fixing roller 32 against each other.

  The fixing unit 3 includes a fixing heater 34 for heating the fixing roller 31 as a heating unit for heating the fixing member. The fixing heater 34 is turned on by energization, and for example, a halogen lamp can be used. The fixing unit 3 conveys the sheet P, performs pressure fixing by the pair of fixing rollers 31 and 32, and performs heat fixing by the fixing heater 34, thereby fixing the image on the sheet P.

  The toner collecting section 4 is connected to a duct 40 attached to the image forming apparatus 1A. The duct 40 includes a first duct 40a provided corresponding to each of the image forming units 11Y, 11M, 11C, and 11BK, and a second duct 40b for assembling the first ducts 40a into one air path. Each first duct 40a is provided at a position where the toner scattered in the image forming units 11Y, 11M, 11C, and 11BK can be sucked.

  The toner collecting unit 4 includes a cyclone unit 41, a collecting unit 42, a filter unit 43, and a blowing unit 44. The cyclone unit 41 is an example of a centrifugal separation unit, and includes a separation unit 41a that generates an air flow for separating the toner from the toner-containing air, a toner collection path 41b that connects the separation unit 41a and the collection unit 42, and a separation unit 41a. And a filter section 43 and a cyclone section discharge air path 41c.

  The separation unit 41a communicates with the second duct 40b and centrifugally separates the toner from the toner-containing air sucked from the image forming units 11Y, 11M, 11C, and 11BK via the duct 40. The separation unit 41a includes an air path forming member having a cylindrical axis extending vertically, in order to generate a flow of rotating air and drop centrifugally separated toner in the direction of gravity.

  The cyclone unit 41 causes the separation unit 41a to generate a flow of air that is swirled by suction by the blower unit 44. Most of the toner in the swirling toner-containing air moves radially outward due to centrifugal force, so that most of the toner is centrifugally separated from the air. The separated toner falls downward by its own weight, and is stored in the recovery unit 42 through the toner recovery path 41b.

  The cyclone part discharge air path 41c includes a reversing part for reversing the direction in which the air from which the toner is separated flows up and down in this example, and introduces the air from which the toner is separated into the filter part 43.

Filter unit 43, a plurality of filters, in this example three filters _43a 1 _{~43a 3,} is attached to the exhaust air passage 43b which communicates with the cyclone unit discharge air passage 41c. Filter unit 43 is configured to collect the toner remaining in the air which the toner is centrifuged at filter 43a ₁ ~43a _3, it is permeable to air.

  The filter unit 43 includes a toner detection unit 43e that detects the amount of toner passing through the discharge air passage 43b. 4 and 5 are configuration diagrams illustrating an example of the toner detection unit according to the present embodiment. The toner detecting unit 43e is an example of a stain detecting unit, and includes a detecting window 43f protruding from the side surface of the discharge air passage 43b to the outside of the filter unit 43.

Detection window 43f during the one attached to the filter unit 43 th filter 43a ₁ and the second sheet of filter 43a _2, i.e., to the flow of air through the exhaust air passage 43 b, 1 sheet of filter 43a ₁ is provided on the downstream side. As a result, the toner detection unit 43e detects the amount of toner that has passed through the _first filter 43a1.

  The detection window 43f includes an attachment surface 43g for adhering toner contained in the air passing through the discharge air passage 43b, and a dam portion 43h for guiding the toner-containing air passing through the discharge air passage 43b to the attachment surface 43g.

  The attachment surface 43g is constituted by at least one slope inclined at an angle of less than 90 ° with respect to the direction in which the toner-containing air flows through the discharge air passage 43b, and protrudes into a concave space constituting the detection window 43f. In this example, the attachment surface 43g is formed in a V-shape that opens on the downstream side with respect to the direction in which the toner-containing air flows through the discharge air passage 43b, and mainly attaches the toner to the two outer surfaces. Further, in this example, the attachment surface 43g has a height that protrudes from the detection window 43f to the inner surface of the discharge air passage 43b.

  The dam portion 43h is provided on the downstream side of the attachment surface 43g with respect to the direction in which the toner-containing air flows through the discharge air passage 43b, and protrudes inward from the inner surface of the filter portion 43. Thereby, a part of the toner-containing air passing through the discharge air passage 43b hits the dam portion 43h and is guided to the attachment surface 43g.

Here, the protrusion height of the attachment surface 43 g and the dam portion 43 h into the discharge air passage 43 b is determined by the filter rib 43 j ₁ for attaching the filter 43 a ₁ to the filter portion 43 and the filter rib 43 j ₂ for attaching the filter 43 a ₂ to the filter portion 43. configured below the projecting height of the filter rib 43j _2. Thereby, the attachment surface 43g and the dam portion 43h protruding into the discharge air passage 43b are configured so as not to obstruct the flow of air.

  In the toner detection unit 43e, the detection window 43f and the attachment surface 43g are made of, for example, a transparent material that is non-transparent to toner or transmits light having a predetermined wavelength with low transmittance. In this example, the detection window 43f, the attachment surface 43g, and the dam portion 43h are formed of an integral transparent resin.

The toner detection unit 43e includes an optical sensor 43i that mainly detects toner attached to the attachment surface 43g in the detection window 43f. The optical sensor 43i is configured by a light receiving element and the pair of light emitting elements, as shown in FIG. 5 (a), light emitted from the light emitting element 43i ₁ is incident on the light-receiving element 43i ₂ passes through the attachment surface 43g a transmission type or, as shown in FIG. 5 (b), light emitted from the light emitting element 43i ₁ is either reflective incident on the light-receiving element 43i ₂ is reflected on the toner adhering to the attachment surface 43g It consists of.

Blowing section 44 is one example of the blowing means, to the flow of air through the exhaust air passage 43b, is provided in the discharge air passage 43b on the downstream side of the filter _43a 1 _{~43a 3.} Blower unit 44, a fan 44a, a motor for driving the fan 44a, which both generates a flow of air swirling in the separation portion 41a of the cyclone unit 41, the air passing through the filter _43a 1 _{~43a 3} device outside the Discharge.

  As shown in FIG. 3, the toner collection unit 4 is supported by a guide rail 101 with respect to a frame 100 provided in the image forming apparatus 1A, and is configured to be detachable by moving in the direction of arrow A. The optical sensor 43i of the toner detecting unit 43e is attached to the frame 100 on the image forming apparatus 1A side.

When the toner collection unit 4 is attached to the image forming apparatus 1A and the cyclone unit 41 is attached to the toner collection unit 4, the suction port 41e of the separation unit 41a of the cyclone unit 41 is connected to the second duct 40b of the duct 40. Communicate. Further, a cyclone discharge air passage 41 c of the cyclone 41 communicates with the filter 43. The filter unit 43, a plurality of filters _43a 1 _{~43a 3} is independently may be detachably attached to the filter unit 43.

  Here, the arrangement of the optical sensor 43i is substantially perpendicular to the attachment / detachment direction of the toner collecting unit 4 with respect to the image forming apparatus 1A along the direction in which the toner-containing air flows in the discharge air passage 43b, even in a direction where the optical axis is substantially inclined. It may be the direction to do. However, as shown in FIGS. 5A and 5B, the optical axis of the optical sensor 43i is set to a direction substantially orthogonal to the direction in which the toner collecting unit 4 is attached to and detached from the image forming apparatus 1A. A configuration in which the sensor 43i is attached to the frame 100 on the image forming apparatus 1A side can be easily realized.

<Operation Example of Image Forming Apparatus of Present Embodiment>
Hereinafter, an operation example of the image forming apparatus 1A according to the present embodiment will be described with reference to the drawings.

  An outline of an operation of forming an image on a sheet P by the image forming apparatus 1A will be described. The image forming unit 11 is controlled based on image data obtained from a document by the document reading unit 10 or image data obtained from the outside, and An electrostatic latent image is formed on the body drums Y, M, C, and BK in accordance with the image, and the electrostatic latent images on the respective photosensitive drums Y, M, C, and BK are tonered by the developing devices 12Y, 12M, 12C, and 12BK. The image is deposited to form a toner image. The toner image formed on each of the photosensitive drums Y, M, C, and BK is primarily transferred to the intermediate transfer belt 16, secondarily transferred from the intermediate transfer belt 16 to the sheet P, and the toner image is transferred to the sheet P. You. Then, the fixing unit 3 is controlled to fix the image on the sheet P, and the sheet P on which the image is formed is discharged.

  In the toner collecting section 4, an air flow for separating the toner from the toner-containing air is generated in the cyclone section 41, and the toner centrifuged in the separating section 41a is stored in the collecting section 42 through the toner collecting path 41b. .

In the toner collecting section 4, all the toner cannot be separated from the toner-containing air in the cyclone section 41, and a part of the toner is sucked into the cyclone section discharge air passage 41 c, It is adsorbed to 43a _1. When the amount of toner adsorbed on the _first filter 43a1 increases, the toner passes through the _first filter 43a1 and is adsorbed on the _second filter 43a2. When the amount of toner adsorbed the second sheet to the filter 43a ₂ increases, it passes through the filter 43a ₂ of the toner is second sheet is adsorbed to the third sheet of the filter 43a _3.

The toner that has passed through the _first filter 43a1 adheres to the adhesion surface 43g of the detection window 43f in the toner detection unit 43e. 6A and 6B are explanatory diagrams showing the flow of air in the toner detection unit. FIG. 6A is a flow velocity distribution in an embodiment having a dam unit 43h, and FIG. 6B is not having a dam unit. 4 schematically shows a flow velocity distribution in an embodiment. In FIGS. 6A and 6B, a region with a high flow velocity is indicated by a solid arrow, and a region with a low flow velocity is indicated by a dashed arrow.

  As shown in FIG. 6B, in the embodiment having no dam portion, air flows into the detection window 43f protruding from the side surface of the discharge air passage 43b to the outside of the filter portion 43, but a decrease in flow velocity is observed. Can be

  On the other hand, as shown in FIG. 6A, in the embodiment provided with the dam portion 43h, a part of the air flowing in the direction of arrow W hits the dam portion 43h, so that the filter portion is moved from the side surface of the discharge air passage 43b. A flow of air is generated which is guided to the detection window 43f protruding out of the outside 43. In addition, since the attachment surface 43g protrudes from the inner surface of the discharge air passage 43b, the air hitting the attachment surface 43g is guided to the detection window 43f.

  In the detection window 43f, a sufficient amount of toner does not adhere to a surface substantially parallel to the direction in which the air flows as indicated by the arrow W. On the other hand, on the attachment surface 43g inclined with respect to the direction of air flow indicated by the arrow W, the air hitting the dam portion 43h sufficiently hits the attachment surface 43g and can be guided into the detection window 43f.

  As a result, a sufficient amount of toner adheres to the vicinity of the detection position Q of the optical sensor 43i on the attachment surface 43g for detection by the optical sensor 43i.

  In the configuration for detecting the toner floating in the discharge air passage, the detection result becomes unstable due to the influence of the contamination of the detection portion and the contamination of the optical sensor which are not caused by the adhesion of the toner. If the sensitivity of the optical sensor is increased to solve this problem, erroneous detection often occurs.

  On the other hand, a sufficient amount of toner for the detection by the optical sensor 43i can be attached near the detection position Q of the optical sensor 43i on the attachment surface 43g. For example, when the optical sensor 43i is a transmission type, The change in the transmission amount due to the presence or absence of the adhesion of the toner becomes large, and the adhesion of the predetermined amount of the toner can be reliably detected by eliminating the influence of the contamination of the detection window 43f due to the adhesion of the toner and the contamination of the optical sensor 43i.

  The number of the attached surfaces 43g may be one, but by using two attached surfaces 43g, the amount of attenuation of transmitted light increases, and the attachment of a predetermined amount of toner can be detected more reliably.

Furthermore, construction of detecting the toner adhered to the filter 43a ₁ ~43a _3, in the configuration for detecting the toner adhered to the inner wall surface of the discharge air passage 43b in the optical sensor, since the amount of adhesion of the toner to the point is high, the sensor A detection result indicating that a predetermined amount of toner has adhered is output before the output is saturated and the life of the filter or the like to be originally set is reached. To solve this problem, if the sensitivity of the optical sensor is reduced, erroneous detection often occurs.

  On the other hand, since the excessive adhesion of the toner can be suppressed on the adhesion surface 43g, it can be reliably detected that the amount of the toner judged to be the life of the filter is adhered.

<Modification of Toner Detecting Unit of Present Embodiment>
7 and 8 are configuration diagrams illustrating a modification of the toner detection unit according to the present embodiment. As shown in FIG. 7, the provision of the damming portion 43h allows air to flow into the detection window 43f even if the attachment surface 43g has the same height as the inner surface of the discharge air passage 43b, and the attachment surface 43g has a sufficient height. Amount of toner can be deposited.

  As shown in FIG. 8, the adhesion surface 43g is formed in a V-shape in which the upstream side opens in the direction of the flow of the air containing the toner passing through the discharge air passage 43b. Also in the configuration for attaching, a sufficient amount of toner can be attached to the attaching surface 43g.

  The present invention is applied to an image forming apparatus that charges a sheet and transfers a toner image.

  1A: Image forming apparatus, 2: Paper transport unit, 3: Transfer unit, 4: Toner collecting unit, 43e: Toner detecting unit, 43f: Detection window, 43g ... · Adhered surface, 43h ··· dam part, 43i ··· optical sensor

Claims (6)

Image forming means for transferring toner to paper to form an image;
A toner collecting means for collecting toner by sucking the toner-containing air in the apparatus,
The toner collecting means includes:
A detection window projecting outward from a discharge air passage through which the toner-containing air passes, and an optical sensor that detects toner in the detection window from outside the detection window,
The detection window is provided with an adhesion surface for projecting detection position by the optical sensor in front Symbol detection within the window, the attachment surface is at least 1 which is inclined with respect to the flowing direction of the toner containing air through the exhaust air duct An image forming apparatus comprising: two slopes . The detection window is provided on the downstream side of the attachment surface with respect to the flowing direction of the toner containing air through said exhaust air duct, protrude from the inner surface of the discharge air path to guide the toner containing air to the attachment surface The image forming apparatus according to claim 1, further comprising a dam unit. The image forming apparatus according to claim 1, wherein the detection window has a part of the attachment surface protruding from an inner surface of the discharge air passage. The toner collecting means includes at least one filter for collecting toner in the toner-containing air, and a filter guide protruding from an inner surface of the discharge air passage, to which the filter is attached, the adhering surface and the damming portion. The image forming apparatus according to claim 2, wherein a projection height of the filter is equal to or less than the filter guide. The image forming apparatus according to any one of claims 1 to 4, wherein the optical sensor is configured such that light incident and emitted is orthogonal to a direction in which the toner-containing air flows through the discharge air path. . The image forming apparatus according to claim 1, wherein the toner collecting unit includes a cyclone unit configured to centrifuge the toner from the toner-containing air.

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