Image forming apparatus

Abstract

To prevent reduction in accuracy of detecting an amount of developer.SOLUTION: Light guide means has a first projection and a fourth projection that project to the outside of a container from a wall surface of the container, and a second projection and a third projection that project to the inside of the container from the wall surface. When seen in a direction intersecting both a gravity direction and a first direction in which the first projection projects, a top face of the second projection is located above a first virtual straight line along a top face of the first projection, and when seen in a direction intersecting both the gravity direction and a second direction in which the fourth projection projects, a top face of the third projection is located above a second virtual straight line along a top face of the fourth projection.SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a recording material.

Background Art

[0002] An electrophotographic image forming apparatus includes a developing device that develops a toner image on the surface of an image carrier such as a photosensitive drum using a developer containing toner. As a method for detecting the remaining amount of the developer (toner remaining amount) in the developing device, a light transmission type remaining amount detection method using light is known. Patent Document 1 describes a remaining amount detection configuration including a light emitting side light guide portion and a light receiving side light guide portion that penetrate from the outside to the inside of a container of the developing device. In this configuration, light emitted from a light emitting element enters the light emitting side light guide portion outside the container, enters the light receiving side light guide portion via the internal space of the container from the light emitting side light guide portion, is emitted from the light receiving side light guide portion outside the container, and is received by a light receiving element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration described in the above document, the light emitting side light guide portion and the light receiving side light guide portion protruded inside the container of the developing device. Therefore, agglomerated masses of the developer grew due to the deposition of the developer on the protruding portions of the light emitting side light guide portion and the light receiving side light guide portion, and the developer adhered to the surfaces forming the optical paths of the light emitting side light guide portion and the light receiving side light guide portion, blocking the optical paths, and there was a possibility that the detection accuracy of the developer amount decreased.

[0005] Therefore, an object of the present invention is to provide an image forming apparatus capable of suppressing a decrease in the detection accuracy of the developer amount.

Means for Solving the Problems

[0006] One aspect of the present invention is an image forming apparatus for forming an image on a recording material using the developer, comprising: a container for containing a developer; a light-emitting element and a light-receiving element disposed on the outside of the container; a light-guiding means provided on the wall surface of the container for guiding light emitted by the light-emitting element to reach the light-receiving element via the internal space of the container; and a detection means for which the output signal of the light-receiving element changes according to the amount of developer in the container, wherein the light-guiding means comprises: a first projection protruding outward from the wall surface of the container and having an incident surface into which light emitted by the light-emitting element is incident; a second projection protruding inward from the wall surface of the container and emitting the light incident on the first projection into the internal space of the container; and a third projection protruding inward from the wall surface of the container and from the second projection to the container The image forming apparatus is characterized by having a third projection into which light emitted into the internal space is incident, and a fourth projection projecting outward from the wall surface of the container, the fourth projection having an emission surface that emits light incident on the third projection toward the light receiving element, wherein the incident surface is provided at the tip of the first projection in a first direction in which the first projection projects outward from the wall surface, and the emission surface is provided at the tip of the fourth projection in a second direction in which the fourth projection projects outward from the wall surface, the upper surface of the second projection is located above a first virtual line along the upper surface of the first projection when viewed in a direction intersecting both the first direction and the direction of gravity, and the upper surface of the third projection is located above a second virtual line along the upper surface of the fourth projection when viewed in a direction intersecting both the second direction and the direction of gravity.

[0007] Another aspect of the present invention is an image forming apparatus for forming an image on a recording material using the developer, comprising: a container for containing a developer; a light-emitting element and a light-receiving element disposed on the outside of the container; a light-guiding means provided on the wall surface of the container for guiding light emitted by the light-emitting element to reach the light-receiving element via the internal space of the container; and a detection means for which the output signal of the light-receiving element changes according to the amount of developer in the container, wherein the light-guiding means is a first projection that protrudes outward from the wall surface of the container, and is activated by the light-emitting element The container has a first projection having an incident surface into which light emitted from it enters, a second projection projecting inward from the wall surface of the container and emitting light incident on the first projection to the internal space of the container, a third projection projecting inward from the wall surface of the container and emitting light emitted from the second projection to the internal space of the container to enter, and a fourth projection projecting outward from the wall surface of the container and having an emission surface that emits light incident on the third projection towards the light receiving element, The first projection has a first side surface extending in a first direction along the wall surface of the container, and a first reflective surface provided at one end of the first side surface in the first direction, the incident surface is provided at the other end of the first side surface in the first direction, the fourth projection has a second side surface extending in a second direction along the wall surface of the container, and a second reflective surface provided at one end of the second side surface in the second direction, the exit surface is provided at the other end of the second side surface in the second direction, and the upper surface of the second projection is the first The image forming apparatus is characterized in that, when viewed in a direction intersecting both the direction and the direction of gravity, the line passing through the upper end of the first reflecting surface is located above a first virtual line drawn in the direction of reflection when light in the first direction is incident on the first reflecting surface and reflected, and the upper surface of the third protrusion is located above a second virtual line drawn in the direction of incidence when light incident on the second reflecting surface is reflected in the second direction, when viewed in a direction intersecting both the second direction and the direction of gravity. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the decrease in the detection accuracy of the amount of developer. [Brief explanation of the drawing]

[0009] [Figure 1] A cross-sectional view (a) and a perspective view (b) of an image forming apparatus according to the first embodiment. [Figure 2] A cross-sectional view (a) and a perspective view (b) of an image forming apparatus according to the first embodiment. [Figure 3] Perspective views (a, b) of an image forming apparatus according to the first embodiment. [Figure 4] A perspective view (a) and a front view (b) of the developing container and toner pack according to the first embodiment, and a perspective view (c) of the stirring member according to the first embodiment. [Figure 5] Cross-sectional view (a) of the 5A-5A section and cross-sectional view (b) of the 5B-5B section in Figure 4(b). [Figure 6] A perspective view showing a toner pack according to the first embodiment. [Figure 7] A figure showing a toner pack (a) and modified examples thereof (b, c) according to the first embodiment. [Figure 8] A perspective view of a developing apparatus according to the first embodiment. [Figure 9] A perspective view (a) showing a developing container and substrate according to the first embodiment, and perspective views (b, c) of the substrate and substrate holding member. [Figure 10] A cross-sectional view (a) perpendicular to the longitudinal direction and a cross-sectional view (b) along the longitudinal direction of the developing apparatus according to the first embodiment. [Figure 11] A circuit diagram showing the basic configuration of the toner level sensor according to the first embodiment. [Figure 12] Cross-sectional views (a, b) of the developing container according to the first embodiment. [Figure 13] A block diagram showing the control system of an image forming apparatus according to the first embodiment. [Figure 14] Perspective views (a-d) of the toner level panel according to the first embodiment. [Figure 15] Perspective views (a, b) of the light guide member according to the first embodiment. [Figure 16] Front view (a), side views (b, c), plan view (d), bottom view, and enlarged view (e) of the light guide member according to the first embodiment. [Figure 17] Perspective views (a, b) of the developing container lid and the light guide member according to the first embodiment. [Figure 18] Perspective view of the light guide member according to the first embodiment. [Figure 19] Perspective view of the light guide member according to the modified example. [Figure 20] Perspective view of the light guide member according to the second embodiment. [Figure 21] Perspective view of the light guide member according to the third embodiment. [Figure 22] Plan view (a) of the light guide member according to the third embodiment and enlarged views (b, c) of a part thereof. [Figure 23] Front view (a) and side views (b, c) of the light guide member according to the third embodiment. [Figure 24] View of the light guide member according to the fourth embodiment as seen from the outside of the developing container. [Figure 25] Perspective views (a, b) of the light guide member according to the fifth embodiment. [Figure 26] Front view (a), side views (b, c), plan view (d), bottom view (e), and rear view (f) of the light guide member according to the fifth embodiment. [Figure 27] Cross-sectional views (a, b) of the light guide member according to the fifth embodiment.

Mode for Carrying Out the Invention

[0012] [Overall structure] As shown in Figures 1(a, b), the image forming apparatus 1 includes a printer body 100 as the main body of the apparatus, a reading device 200 supported by the printer body 100 so as to be openable and closable, and an operating unit 300 attached to the outer surface of the printer body 100. The printer body 100 includes an image forming unit 10 for forming a toner image on a recording material, a feeding unit 60 for feeding the recording material to the image forming unit 10, a fixing unit 70 for fixing the toner image formed by the image forming unit 10 onto the recording material, and a pair of discharge rollers 80.

[0013] The image forming unit 10 includes a scanner unit 11, an electrophotographic process unit 20, and a transfer roller 12 that transfers a toner image, which is a developer image formed on the photosensitive drum 21 of the process unit 20, to a recording material. As shown in Figures 5(a, b), the process unit 20 includes a photosensitive drum 21, a developing device 30 which includes a charging roller 22, a pre-exposure device 23, and a developing roller 31 arranged around the photosensitive drum 21. The process unit 20 is detachably attached to the printer body 100. The process unit 20 may also be screwed to the printer body 100, and may be removed mainly by a service technician rather than a user. On the other hand, the process unit 20 does not include structural members of the printer body 100, such as the housing frame of the printer body 100.

[0014] The photosensitive drum 21 is a photoreceptor molded into a cylindrical shape. In this embodiment, the photosensitive drum 21 has a photosensitive layer formed of a negatively charged organic photoreceptor on a drum-shaped substrate made of aluminum. The photosensitive drum 21, as an image carrier, is rotated by a motor in a predetermined direction (clockwise in the figure) at a predetermined process speed.

[0015] The charging roller 22 contacts the photosensitive drum 21 with a predetermined pressure, forming a charged area. Furthermore, by applying a desired charging voltage from a high-voltage charging power supply, the surface of the photosensitive drum 21 is uniformly charged to a predetermined potential. In this embodiment, the photosensitive drum 21 is negatively charged by the charging roller 22. The pre-exposure device 23 discharges the surface potential of the photosensitive drum 21 before it enters the charged area in order to generate a stable discharge in the charged area.

[0016] The scanner unit 11, acting as an exposure means, scans and exposes the surface of the photosensitive drum 21 by irradiating it with laser light corresponding to image information input from an external device or reading device 200 using a polygon mirror. This exposure forms an electrostatic latent image on the surface of the photosensitive drum 21 corresponding to the image information. The scanner unit 11 is not limited to a laser scanner device; for example, an LED exposure device having an LED array in which multiple LEDs are arranged along the longitudinal direction of the photosensitive drum 21 may be used.

[0017] The developing device 30 includes a developing roller 31 as a developer carrier for holding the developer, a developing container 32 as the frame of the developing device 30, and a supply roller 33 capable of supplying developer to the developing roller 31. The developing roller 31 and the supply roller 33 are rotatably supported by the developing container 32. The developing roller 31 is positioned at the opening of the developing container 32 so as to face the photosensitive drum 21. The supply roller 33 is in rotatable contact with the developing roller 31, and the toner, which is the developer contained in the developing container 32, is applied to the surface of the developing roller 31 by the supply roller 33. Note that the supply roller 33 is not necessarily required if a configuration is in place that can supply sufficient toner to the developing roller 31.

[0018] The developing apparatus 30 of this embodiment uses a contact developing method. That is, the toner layer supported on the developing roller 31 comes into contact with the photosensitive drum 21 in the developing section (developing region) where the photosensitive drum 21 and the developing roller 31 face each other. A developing voltage is applied to the developing roller 31 by a high-voltage developing power supply. Under the developing voltage, the toner supported on the developing roller 31 is transferred from the developing roller 31 to the drum surface according to the potential distribution on the surface of the photosensitive drum 21, thereby developing an electrostatic latent image into a toner image. In this embodiment, an inversion developing method is employed. That is, after being charged in the charging process, the toner adheres to the surface region of the photosensitive drum 21, where the amount of charge has decreased due to exposure in the exposure process, thereby forming a toner image.

[0019] Furthermore, in this embodiment, a toner with a particle size of 6 μm and a normal charge polarity of negative polarity is used. As an example, the toner in this embodiment is a polymerized toner produced by polymerization. In addition, the toner in this embodiment does not contain magnetic components, and the toner is supported on the developing roller 31 mainly by intermolecular forces and electrostatic forces (mirror image forces), making it a so-called non-magnetic one-component developer. However, a one-component developer containing magnetic components may also be used. In addition, the one-component developer may contain additives (for example, wax or silica fine particles) to adjust the fluidity and charge performance of the toner, in addition to toner particles. Alternatively, a two-component developer composed of a non-magnetic toner and a magnetic carrier may be used as the developer. When a magnetic developer is used, for example, a cylindrical developing sleeve with a magnet placed inside may be used as the developer carrier.

[0020] An agitator 34 is provided inside the developing container 32. Driven by a motor M1 (see Figure 13), the agitator 34 rotates to agitate the toner inside the developing container 32 and to transport the toner toward the developing roller 31 and the supply roller 33. The agitator 34 also circulates the toner that is not used for developing and has been stripped from the developing roller 31 within the developing container, thereby homogenizing the toner inside the developing container. The agitator 34 is not limited to a rotating form. For example, an oscillating agitator may be used. In addition, another agitator may be provided in addition to the agitator 34.

[0021] Furthermore, a developing blade 35 is positioned at the opening of the developing container 32 where the developing roller 31 is located, to regulate the amount of toner carried on the developing roller 31. The toner supplied to the surface of the developing roller 31 passes through the area opposite the developing blade 35 as the developing roller 31 rotates, resulting in a uniformly thin layer and negative charge due to triboelectricity.

[0022] As shown in Figures 1(a, b), the feeding unit 60 includes a front door 61 that is openably and closably supported by the printer body 100, a tray section 62, a middle plate 63, a tray spring 64, and a pickup roller 65. The tray section 62 forms the bottom surface of the recording material storage space that is revealed when the front door 61 is opened, and the middle plate 63 is supported by the tray section 62 so as to be able to move up and down. The tray spring 64 biases the middle plate 63 upward, pressing the recording material P loaded on the middle plate 63 against the pickup roller 65. The front door 61 closes the recording material storage space when closed relative to the printer body 100, and supports the recording material P together with the tray section 62 and the middle plate 63 when open relative to the printer body 100.

[0023] The fixing unit 70 is a thermal fixing type that performs image fixing by heating and melting the toner on the recording material. The fixing unit 70 comprises a fixing film 71, a fixing heater such as a ceramic heater for heating the fixing film 71, a thermistor for measuring the temperature of the fixing heater, and a pressure roller 72 that presses against the fixing film 71.

[0024] Next, the image forming operation of the image forming apparatus 1 will be described. When an image forming command is input to the image forming apparatus 1, the image forming process by the image forming unit 10 is started based on image information input from an external computer or reading device 200 connected to the image forming apparatus 1. The scanner unit 11 irradiates the photosensitive drum 21 with laser light based on the input image information. At this time, the photosensitive drum 21 is pre-charged by the charging roller 22, and an electrostatic latent image is formed on the photosensitive drum 21 when the laser light is irradiated. Subsequently, this electrostatic latent image is developed by the developing roller 31, and a toner image is formed on the photosensitive drum 21.

[0025] In parallel with the image formation process described above, the pickup roller 65 of the feeding unit 60 feeds out the recording material P supported by the front door 61, tray unit 62, and middle plate 63. The recording material P is fed to the registration roller pair 15 by the pickup roller 65, and its skew is corrected when it abuts against the nip of the registration roller pair 15. The registration roller pair 15 is then driven in accordance with the timing of the toner image transfer and transports the recording material P toward the transfer nip formed by the transfer roller 12 and the photosensitive drum 21.

[0026] A transfer voltage is applied to the transfer roller 12, which acts as a transfer means, from a transfer high-voltage power supply, and the toner image supported on the photosensitive drum 21 is transferred to the recording material P, which is transported by the registration roller pair 15. The recording material P, on which the toner image has been transferred, is transported to the fixing unit 70, where the toner image is heated and pressurized as it passes through the nip between the fixing film 71 and the pressure roller 72 of the fixing unit 70. This causes the toner particles to melt and then solidify, fixing the toner image to the recording material P. The recording material P that has passed through the fixing unit 70 is discharged to the outside of the image forming apparatus 1 (outside the machine) by the discharge roller pair 80 and loaded onto the discharge tray 81 formed on the top of the printer body 100.

[0027] The discharge tray 81 is inclined upward toward the downstream direction in which the recording material is discharged, and the recording material discharged into the discharge tray 81 slides down the discharge tray 81 so that its rear end is aligned with the regulating surface 84.

[0028] The transfer method is not limited to a direct transfer method in which the toner image is directly transferred from the image carrier to the recording material, but may also be an intermediate transfer method in which the toner image is transferred from the image carrier to the recording material via an intermediate transfer body. In that case, instead of the transfer roller 12, an intermediate transfer unit is used that includes, for example, an endless intermediate transfer belt stretched over a plurality of rollers, a primary transfer roller facing the photosensitive drum with the intermediate transfer belt in between, and a secondary transfer roller facing the outer surface of the intermediate transfer belt. The toner image formed on the photosensitive drum is first transferred to the intermediate transfer belt by the primary transfer roller, and then secondarily transferred to the recording material by the secondary transfer roller. Such an intermediate transfer unit is another example of a transfer method.

[0029] Furthermore, although this embodiment describes a monochrome printer, the techniques described below may also be applied to an image forming apparatus that includes multiple sets of image carriers and developing devices and forms color images using multiple toners.

[0030] As shown in Figures 3(a, b), the reading device 200 includes a reading unit 201 which houses a reading section (not shown) and a pressure plate 202 which is supported by the reading unit 201 so as to be openable and closable. The upper surface of the reading unit 201 is provided with a document glass 203 which transmits light emitted from the reading section and on which the document is placed.

[0031] When the user wants the scanner 200 to read the image of a document, the user places the document on the document glass 203 with the pressure plate 202 open. Then, by closing the pressure plate 202, the user prevents the document from shifting position on the document glass 203, and outputs a reading command to the image forming apparatus 1 by, for example, operating the control unit 300. When the reading operation starts, the reading unit within the reading unit 201 moves back and forth in the sub-scanning direction, that is, in the left-right direction with the control unit 300 of the image forming apparatus 1 facing forward. The reading unit emits light from the light-emitting unit towards the document, receives the light reflected by the document with the light-receiving unit, and reads the image of the document by converting it into photoelectric light. In the following, the forward-backward direction, left-right direction, and up-down direction are defined based on the state with the control unit 300 facing forward.

[0032] As shown in Figure 2(a, b), a first opening 101 that opens upward is formed at the top of the printer body 100, and in the normal operating state (a state in which image forming operation can be performed), it is covered by the output tray 81. The output tray 81 is supported so as to be openable and closable relative to the printer body 100 around a pivot axis that extends in the left-right direction. The output tray 81 opens from the front to the back when the reader 200 is open relative to the printer body 100. In addition, the first opening 101 is configured to expose a mounting section 57 having a replenishment port 32a into which a toner pack 40, which will be described later, can be attached (see Figure 4(a, b)). The user accesses the mounting section 57 by opening the output tray 81. The reader 200 and the output tray 81 may be configured to be held in the open and closed states by a holding mechanism such as a hinge mechanism.

[0033] Thus, in this embodiment, while the developing device 30 remains attached to the image forming apparatus 1, the user replenishes toner from a toner pack 40 (see Figure 1(a, b)) that is filled with replenishment toner to the developing device 30 (direct replenishment method).

[0034] [Collection of leftover toner] This embodiment employs a cleanerless configuration in which residual toner that remains on the photosensitive drum 21 without being transferred to the recording material P is collected in the developing unit 30 and reused. The residual toner is removed in the following steps. The residual toner contains a mixture of positively charged toner and negatively charged toner that does not have sufficient charge. The photosensitive drum 21 after transfer is discharged by the pre-exposure device 23, and a uniform discharge is generated by the charging roller 22, causing the residual toner to be negatively charged again. The residual toner, which has been negatively charged again in the charging section, reaches the developing section as the photosensitive drum 21 rotates. The surface area of ​​the photosensitive drum 21 that has passed through the charging section is then exposed by the scanner unit 11 with the residual toner still attached to the surface, and an electrostatic latent image is written.

[0035] Here, the behavior of the transfer residue toner that reaches the developing section will be explained separately for the exposed and unexposed sections of the photosensitive drum 21. The transfer residue toner adhering to the unexposed section of the photosensitive drum 21 is transferred to the developing roller 31 in the developing section due to the potential difference between the potential of the unexposed section (dark area potential) and the developing voltage, and is collected in the developing container 32. This is because, assuming that the normal charging polarity of the toner is negative, the developing voltage applied to the developing roller 31 is positive relative to the potential of the unexposed section. The toner collected in the developing container 32 is then mixed and dispersed with the toner in the developing container by the stirring member 34, and is then carried on the developing roller 31 for use in the developing process again.

[0036] On the other hand, the residual toner adhering to the exposure area of ​​the photosensitive drum 21 remains on the drum surface without being transferred from the photosensitive drum 21 to the developing roller 31 in the developing section. This is because, assuming that the normal charging polarity of the toner is negative, the developing voltage applied to the developing roller 31 is at a potential that is even more negative than the potential of the exposure area (bright area potential). The residual toner remaining on the drum surface, along with other toner transferred from the developing roller 31 to the exposure area, is carried on the photosensitive drum 21 and moves to the transfer section, where it is transferred to the recording material P.

[0037] As described above, this embodiment employs a cleanerless configuration (simultaneous development and recovery method) in which the transfer residue toner is recovered and reused in the developing device 30. However, a conventional configuration in which the transfer residue toner is recovered using a cleaning blade that contacts the photosensitive drum 21 may also be used. In that case, the transfer residue toner recovered by the cleaning blade is collected in a recovery container installed separately from the developing device 30. However, by adopting a cleanerless configuration, the installation space for a recovery container for collecting the transfer residue toner, etc., is not required, making it possible to further miniaturize the image forming apparatus 1, and printing costs can also be reduced by reusing the transfer residue toner.

[0038] [Developing container and toner pack configuration] Next, the configuration of the developing container 32 and the toner pack 40 as a replenishment container will be described. Figure 4(a) is a perspective view showing the developing container 32 and the toner pack 40, and Figure 4(b) is a front view showing the developing container 32 and the toner pack 40. Figure 4(c) is a perspective view showing the stirring member 34 inside the developing container 32. Figure 5(a) is a cross-sectional view of 5A-5A in Figure 4(b), and Figure 5(b) is a cross-sectional view of 5B-5B in Figure 4(b).

[0039] As shown in Figures 4(a) to 5(b), the developing container 32 (container), as part of the developing apparatus 30, has a transport chamber 36 that houses the stirring member 34. The transport chamber 36, which serves as a storage section for toner, extends along the entire length of the developing container 32 in the longitudinal direction LD (left-right direction). The longitudinal direction LD of the developing container 32 is the direction of the rotation axis of the developing roller 31, which is the developer carrier. The developing container 32 is also composed of a developing container frame 320 and a developing container lid 321, which are connected by a connecting part 322. The developing roller 31 and the supply roller 33 are rotatably supported by the developing container frame 320.

[0040] Furthermore, the developing container 32 has a replenishment projection 37 that protrudes upward from one end in the longitudinal direction of the transport chamber 36 and communicates with the transport chamber 36. More specifically, the replenishment projection 37 is provided at one end of the developing container lid 321 in the direction of the rotation axis of the developing roller 31 (longitudinal direction LD). The replenishment projection 37 protrudes toward the discharge tray 81 in a direction that intersects the rotation axis direction (particularly upward in the direction of gravity) from the central part of the developing container 32 in the rotation axis direction.

[0041] In this embodiment, the replenishment projection 37 is formed to be hollow inside and is located on the left side of the developing container 32. The end of the replenishment projection 37 is provided with a mounting section 57 on which a toner pack 40 can be attached, and the mounting section 57 is provided with a rotatable replenishment port 32a for supplying developer from the toner pack 40 to the transport chamber 36. The toner pack 40 can be attached to the mounting section 57 in a state where it is exposed to the outside of the device.

[0042] The replenishment projection 37 extends diagonally from the transport chamber 36 toward the front of the device and upward. That is, the replenishment projection 37 protrudes downstream and upward in the discharge direction of the discharge roller pair 80. As a result, the replenishment port 32a located on the replenishment projection 37 is positioned on the front side of the image forming apparatus 1, making it easy to replenish toner to the developing container 32. Furthermore, by providing the replenishment projection 37, where the replenishment port 32a is located, on one side in the longitudinal direction of the developing container 32, a laser passage space can be secured through which the laser emitted from the scanner unit 11 can pass, allowing the image forming apparatus 1 to be miniaturized.

[0043] As shown in Figures 4(a) to 5(b), the toner pack 40 is configured to be detachably attached to the mounting portion 57 of the replenishment projection 37. The toner pack 40 also has a shutter member 41 that is provided at the opening of the toner pack 40 and can be opened and closed, and a groove 42 that corresponds to a projection 32b formed on the mounting portion 57. When the user replenishes toner in the developing container 32, the user aligns the groove 42 of the toner pack 40 so that it passes through the projection 32b of the mounting portion 57, and connects the toner pack 40 to the mounting portion 57. Then, in this state, the user operates a lever (not shown) provided on the image forming apparatus 1 to rotate the shutter member 41 of the toner pack 40 by 90 degrees. As a result, the replenishment port 32a also rotates together with the shutter member 41 and abuts against a butt portion (not shown) of the mounting portion 57, causing the shutter member 41 to open completely and simultaneously opening the replenishment port 32a and the opening of the toner pack 40. As a result, the toner contained in the toner pack 40 leaks out from the opening of the toner pack 40, and the leaked toner enters the transport chamber 36 through the hollow supply protrusion 37 via the supply port 32a.

[0044] Here, as shown in Figure 4(c), the stirring member 34 has a stirring shaft 34a extending in the longitudinal direction LD, and a first blade portion 34b1 and a second blade portion 34b2 extending radially outward from the stirring shaft 34a, respectively. Both the first blade portion 34b1 and the second blade portion 34b2 are formed from a flexible sheet, and their radially outward extensions are different. The first blade portion 34b1 is longer than the second blade portion 34b2. Figures 5(a, b) show the rotation trajectory of the first blade portion 36b1 as Tb1, assuming that the first blade portion 34b1 rotates in a straight position, ignoring the wall surface of the developing container 32. Similarly, Figure 5(a, b) shows the rotational trajectory of the second blade 34b2 as Tb2, assuming that the second blade 34b1 rotates in a straight position, ignoring the wall surface of the developing container 32. The wiping portion 34c of the stirring member 34 shown in Figure 4(c) will be described later.

[0045] As shown in Figure 5(a), toner supplied from the supply port 32a located upstream in the transport direction of the agitator 34 is fed towards the developing roller 31 and the supply roller 33 as the agitator 34 rotates. The supply port 32a and the supply projection 37 are located at one end of the longitudinal direction LD of the developing container 32, but by repeatedly rotating the agitator 34, the toner is distributed throughout the entire length of the developing container 32. In other words, the transport direction of the agitator 34 is parallel to the longitudinal direction LD of the developing container 32 (see Figure 4(a)) and also intersects with the longitudinal direction LD (the direction from the transport chamber 36 toward the developing roller 31 and the supply roller 33). Here, as shown in the rotation trajectories Tb1 and Tb2, the longer blade section, the first blade section 34b1, functions as the main part that transports the toner toward the developing roller 31 and the supply roller 33. On the other hand, the shorter blade section, the second blade section 34b2, functions as an auxiliary section for transporting toner in areas where the first blade section 34b1 would hit the underside and not transport it effectively, such as the corners 36e of the transport chamber 36.

[0046] In this embodiment, the toner pack 40 is made of a bag made of easily deformable plastic film, as shown in Figures 6 and 7(a), but is not limited thereto. For example, the toner pack (supply container) may be made of a substantially cylindrical bottle container 40B as shown in Figure 7(b), or of a paper container 40C as shown in Figure 7(c). In any case, the material and shape of the toner pack (supply container) can be anything. Furthermore, the method for discharging toner from the toner pack (supply container) is preferably by the user squeezing it with their fingers if it is the toner pack 40 or paper container 40C, and if it is the bottle container 40B, it is preferable for the user to vibrate the container by tapping it or the like to cause it to leak out. In addition, a discharge mechanism may be provided inside the bottle container 40B to discharge toner from the bottle container 40B. Furthermore, the discharge mechanism may be configured to engage with the printer body 100 and receive driving force from the printer body 100.

[0047] Furthermore, the shutter member 41 may be omitted in any toner pack, and a sliding shutter member may be used instead of the rotating shutter member 41. Also, the shutter member 41 may be configured to be destroyed when the toner pack is installed in the supply port 32a or when the toner pack is rotated while installed, or it may be a removable lid structure such as a seal.

[0048] Furthermore, in this embodiment, the stirring member 34 is equipped with two blade sections 34b1 and 34b2 of different lengths, but the length and number of blade sections are not limited thereto. For example, they may be freely set considering the shape of the developing container 32, transport efficiency, etc.

[0049] [Method for detecting toner level] From here, the configuration of the developing device 30 related to toner level detection in this embodiment will be explained in more detail using Figures 8 to 14. Figure 8 is a perspective view showing the developing device 30. Figure 9(a) is a perspective view showing the assembly of the substrate 700 and the substrate holding member 710 to the developing container lid 321. Figure 9(b) is a perspective view showing the substrate 700 and the substrate holding member 710, and Figure 9(c) is another perspective view showing the substrate 700 and the substrate holding member 710. Figure 10(a) is a cross-sectional view of the developing device 30 passing through the light-emitting element 510a of the developing device 30 in the orientation of the developing device 30 when detecting the toner level, and Figure 10(b) is a cross-sectional view taken along 10B-10B of Figure 10(a). Figure 11 is a schematic circuit diagram showing an example of the circuit configuration of the toner level sensor 500. Figure 12(a) is a cross-sectional view showing the developing container 32 in the orientation of the developing device 30 when detecting the toner level, with a low toner level. Figure 12(b) is a cross-sectional view showing the developing container 32 in a state where the toner level is high, in the orientation of the developing device 30 when detecting the remaining toner level.

[0050] As shown in Figure 8, the developing container lid 321, which constitutes part of the developing container 32, has substrate positioning parts 321a and 321b and substrate fixing parts 321c and 321d. A light guide member 600 is installed as a light guide means at a position between the substrate fixing parts 321c and 321d of the developing container lid 321 in the longitudinal LD. The light guide member 600 has an emitter-side light guide 610 and a light receiver-side light guide 620. The emitter-side light guide 610 guides light emitted from the light-emitting element 510a (described later) into the transport chamber 36 of the developing container 32. The light receiver-side light guide 620 guides light emitted from the emitter-side light guide 610 and incident via the spatial optical path Q (see Figure 10(a, b)) in the transport chamber 36 to the light receiver element 510b (described later). The light guide member 600 is provided on the developing container lid 321, which is the wall surface of the developing container 32 (container), and functions as a light guide means that guides the light emitted by the light-emitting element 510a to reach the light-receiving element 510b via the internal space of the developing container 32. Furthermore, the light guide member 600, the light-emitting element 510a, and the light-receiving element 510b constitute a toner remaining amount sensor 500, which serves as a means for detecting the amount of developer.

[0051] The substrate positioning parts 321a and 321b are positioned outside the substrate fixing parts 321c and 321d in the longitudinal LD ​​of the developing container 32, and have a boss shape that protrudes away from the developing container 32. The shape of the substrate positioning parts 321a and 321b is not limited to a boss shape and may be any shape. The longitudinal LD ​​of the developing container 32 is the same as the longitudinal LD ​​of the process unit 20 (see Figure 4(a)). Fasteners such as screws can be screwed into the substrate fixing parts 321c and 321d.

[0052] In this embodiment, as shown in Figure 9(a), the substrate 700 and the substrate holding member 710 are assembled to the developing container lid 321. The substrate holding member 710 is assembled to the developing container lid 321 while being sandwiched between the developing container lid 321 and the substrate 700. It is also possible to simplify the substrate holding configuration and assemble the substrate 700 directly to the developing container lid 321 without using the substrate holding member 710.

[0053] As shown in Figure 9(b), the substrate 700 is provided on the surface facing the substrate holding member 710 and has a light-emitting element 510a and a light-receiving element 510b for detecting the remaining amount of toner in the transport chamber 36. In this embodiment, an LED is used for the light-emitting element 510a and a phototransistor that turns on when light from the LED is used for the light-receiving element 510b, but the embodiment is not limited to these. For example, a halogen lamp or fluorescent lamp may be used for the light-emitting element 510a, and a photodiode or avalanche photodiode may be used for the light-receiving element 510b.

[0054] Furthermore, the circuit board 700 is provided with a cable connector 700n, which is connected by a cable to a control unit 90, which will be described later, located on the printer body 100.

[0055] Furthermore, the substrate 700 has positioning holes 700a and 700b through which substrate positioning parts 321a and 321b are inserted and engaged, and substrate fixing holes 700c and 700d through which screws that are screwed into substrate fixing parts 321c and 321d can pass.

[0056] Similarly, the substrate holding member 710 has positioning holes 710a and 710b through which the substrate positioning parts 321a and 321b are inserted and engaged, and substrate fixing holes 710c and 710d through which screws that are screwed into the substrate fixing parts 321c and 321d can pass. Furthermore, the substrate holding member 710 has a first hole 711a into which the light-emitting side light guide 610 of the light guide member 600 is inserted, and a second hole 711b into which the light-receiving side light guide 620 of the light guide member 600 is inserted. These first hole 711a and second hole 711b have a cylindrical shape. The substrate holding member 710 functions as a holder for holding the substrate 700.

[0057] Furthermore, light-shielding plates 710e and 710f are provided on the side of the substrate holding member 710 facing the substrate 700, serving as shielding portions. These light-shielding plates 710e and 710f are positioned between the light-emitting element 510a and the light-receiving element 510b in the longitudinal LD ​​when the substrate 700 and the substrate holding member 710 are assembled to the developing container lid 321, and are also provided in close proximity to the substrate 700.

[0058] As shown in Figures 8 to 10(a), the substrate holding member 710 is positioned relative to the developing container lid 321 by the substrate positioning 321a and 321b of the developing container lid 321 penetrating and engaging with the positioning holes 710a and 710b. Similarly, the substrate 700 is positioned relative to the developing container lid 321 by the substrate positioning 321a and 321b of the developing container lid 321 penetrating and engaging with the positioning holes 700a and 700b. In this way, by using the substrate positioning 321a and 321b in common for positioning the substrate holding member 710 and the substrate 700, the developing container lid 321, the substrate holding member 710, and the substrate 700 can be positioned with higher precision.

[0059] Furthermore, with the substrate holding member 710 and the substrate 700 positioned relative to the developing container lid 321, screws are inserted into the substrate fixing holes 700c, 700d, 710c, and 710d, and the screws are screwed into the substrate fixing portions 321c and 321d of the developing container lid 321. As a result, the substrate holding member 710 and the substrate 700 are fastened together with the developing container lid 321 by the screws, and the substrate holding member 710 and the substrate 700 are fixed to the developing container lid 321.

[0060] As shown in Figures 8 to 10(b), when the substrate holding member 710 and the substrate 700 are assembled to the developing container lid 321, the light-emitting side light guide 610 of the light guide member 600 is inserted (fitted) into the first hole 711a of the substrate holding member 710. The light-emitting side light guide 610 is then positioned in close proximity to the light-emitting element 510a of the substrate 700. Similarly, the light-receiving side light guide 620 of the light guide member 600 is inserted (fitted) into the second hole 711b of the substrate holding member 710. The light-receiving side light guide 620 is then positioned in close proximity to the light-receiving element 510b of the substrate 700.

[0061] As described above, the substrate holding member 710 and the substrate 700 are precisely positioned on the developing container lid 321, which increases the ratio of the amount of light incident on the light-emitting side light guide 610 to the amount of light emitted from the light-emitting element 510a. The light that passes through the inside of the light-emitting side light guide 610 and is guided to the inside of the developing container 32 is then emitted from the light-emitting side light guide 610 toward the longitudinal LD.

[0062] Then, the light traveling through the spatial light path Q inside the transport chamber 36 enters the light-receiving light guide 620 and is guided through the inside of the light-receiving light guide 620 to the outside of the developing container 32. Since the light-receiving light guide 620 is positioned close to the light-receiving element 510b, the ratio of the amount of light received by the light-receiving element 510b to the amount of light emitted from the light-receiving light guide 620 can be increased.

[0063] Furthermore, as shown in Figures 9(b) and 9(c), the substrate holding member 710 has light-shielding plates 710e and 710f positioned between the light-emitting element 510a and the light-receiving element 510b, and close to the substrate 700. As a result, light emitted from the light-emitting element 510a that goes towards the light-receiving element 510b without passing through the light-emitting side light guide 610 and the light-receiving side light guide 620 is shielded by the light-shielding plates 710e and 710f. This suppresses false detections caused by stray light (light that does not pass through the spatial optical path Q) being received by the light-receiving element 510b.

[0064] Here, the arrangement of the light-emitting element 510a and the light-receiving element 510b will be explained in more detail. As shown in Figure 10(a, b), the light-emitting element 510a and the light-receiving element 510b are arranged facing each other on the side 36a of the developing container 32 opposite to the developing roller 31. Furthermore, the light-emitting element 510a and the light-receiving element 510b are located in the central part of the transport chamber 36 in the longitudinal LD. More specifically, as shown in Figure 10(b), in the longitudinal LD, the center 31a (dashed line) of the developing roller 31 is located between the light-emitting element 510a and the light-receiving element 510b. By placing the light-emitting element 510a and the light-receiving element 510b in the central part of the transport chamber 36 in this way, the remaining amount of toner in the transport chamber 36 can be detected accurately. That is, while developer may be unevenly distributed at the ends of the transport chamber 36 in the longitudinal LD, the central part of the transport chamber 36 has less uneven distribution of developer, so the remaining amount of toner can be detected more accurately.

[0065] As shown in the circuit diagram of the toner level sensor 500 in Figure 11, a switch (not shown) is provided between the light-emitting element 510a and the power supply voltage Vcc. When this switch is turned ON, the voltage from the power supply voltage Vcc is applied to the light-emitting element 510a, causing the light-emitting element 510a to become conductive. On the other hand, a switch (not shown) is also provided between the light-receiving element 510b and the power supply voltage Vcc, and when this switch is turned ON, the light-receiving element 510b becomes conductive due to a current corresponding to the detected amount of light.

[0066] The light-emitting element 510a is connected to a power supply voltage Vcc and a current-limiting resistor R1, and the light-emitting element 510a emits light according to the current determined by the current-limiting resistor R1. The light emitted from the light-emitting element 510a passes through the spatial light path Q (Figure 10(b)) inside the developing container 32 and is received by the light-receiving element 510b. The power supply voltage Vcc is connected to the collector terminal of the light-receiving element 510b, and a detection resistor R2 is connected to the emitter terminal. The light-receiving element 510b, which is a phototransistor, receives the light emitted from the light-emitting element 510a and outputs a signal (current) corresponding to the amount of light received. This signal is converted to a voltage V1 by the detection resistor R2 and input to the A / D conversion unit 95 of the control unit 90 (see Figure 11). That is, the light-receiving element 510b changes the value of the output signal (voltage value) according to the amount of toner (developer) contained in the transport chamber 36.

[0067] The control unit 90 (CPU 91) determines whether the light-receiving element 510b has received light from the light-emitting element 510a based on the input voltage value. The control unit 90 (CPU 91) calculates the amount of toner (amount of developer) in the developing container 32 based on the length of time the light-receiving element 510b detected each light and the received light intensity when the toner in the developing container 32 was stirred for a certain period of time by the stirring member 34. In other words, the ROM 93 has in advance stored a table that can output the remaining amount of toner from the light reception time and light intensity when the toner was transported by the stirring member 34, and the control unit 90 predicts / calculates the remaining amount of toner based on the input to the A / D conversion unit 95 and the table.

[0068] More specifically, as shown in Figure 10(a), the spatial optical path Q of the toner level sensor 500 is set to overlap with the rotational trajectories Tb1 and Tb2 of the stirring member 34 when viewed in the axial direction of the stirring member 34's rotation axis. In other words, the light emitted from the light-emitting element 510a of the toner level sensor 500 passes inside the conveying chamber 36, within the rotational trajectories Tb1 and Tb2 of the stirring member 34 when viewed in the axial direction of the stirring member 34. The time during which the spatial optical path Q is blocked by the toner conveyed by the stirring member 34 during one rotation of the stirring member 34, that is, the time during which the light-receiving element 510b does not detect light from the light-emitting element 510a, changes depending on the remaining toner level. The intensity of the light incident on the light-receiving element 510b (amount of light received) also changes depending on the remaining toner level.

[0069] In other words, when there is a lot of toner remaining, the spatial light path Q is more easily blocked by the toner, so the time that the light-receiving element 510b receives light becomes shorter, and the intensity of the light received by the light-receiving element 510b becomes lower (the amount of light received is less). Conversely, when there is little toner remaining, the time that the light-receiving element 510b receives light becomes longer, and the intensity of the light received by the light-receiving element 510b becomes stronger (the amount of light received is more). Therefore, the control unit 90 can determine the toner level based on the light-receiving time and light-receiving intensity of the light-receiving element 510b as follows.

[0070] For example, if the time the light-receiving element 510b is receiving light exceeds a predetermined threshold, or if the light-receiving intensity of the light-receiving element 510b is stronger than a predetermined threshold, it is determined that the amount of toner remaining in the transport chamber 36 of the developing container 32 is low, as shown in Figure 12(a). On the other hand, if the time the light-receiving element 510b is receiving light exceeds a predetermined threshold, or if the light-receiving intensity of the light-receiving element 510b is weaker than a predetermined threshold, it is determined that the amount of toner remaining in the transport chamber 36 of the developing container 32 is high, as shown in Figure 12(b).

[0071] [Control system for image forming apparatus] Figure 13 is a block diagram showing the control system of the image forming apparatus 1. The control unit 90, which serves as the control means for the image forming apparatus 1, includes a CPU 91 as an arithmetic unit, a RAM 92 used as the work area for the CPU 91, and a ROM 93 for storing various programs. The control unit 90 also includes an I / O interface 94 as an input / output port for connecting to external devices, and an A / D conversion unit 95 for converting analog signals into digital signals.

[0072] The input side of the control unit 90 is connected to a toner level sensor 500, a mounting sensor 53, and an open / close sensor 54. The mounting sensor 53 detects when the toner pack 40 is mounted in the replenishment port 32a of the developing container 32. For example, the mounting sensor 53 consists of a pressure-sensitive switch provided in the replenishment port 32a that outputs a detection signal when pressed by a protrusion on the toner pack 40. The open / close sensor 54 detects whether or not the discharge tray 81 is open. The open / close sensor 54 consists of, for example, a pressure-sensitive switch or a magnetic sensor.

[0073] Furthermore, the control unit 90 is connected to an operation unit 300, an image forming unit 10, and a toner level panel 400 which serves as a notification means capable of notifying information regarding the remaining toner level. The operation unit 300 has a display unit 301 capable of displaying various setting screens and physical keys, etc. The display unit 301 is composed of, for example, a liquid crystal panel. The image forming unit 10 has a motor M1 as a drive source for driving the photosensitive drum 21, developing roller 31, supply roller 33, and agitation member 34, etc. Note that the photosensitive drum 21, developing roller 31, supply roller 33, and agitation member 34 may each be configured to be driven by separate motors.

[0074] As shown in Figures 1(b) and 14(a) to 14(d), the toner level panel 400 is located on the right side of the front of the printer body 100, that is, on the opposite side from the operation unit 300 located on the left side, and displays information regarding the remaining toner in the developing container 32. In this embodiment, the toner level panel 400 is a panel member consisting of multiple (three in this embodiment) scales arranged vertically, with each scale corresponding to Low level, Mid level, and Full level.

[0075] Specifically, as shown in Figure 14(a), when only the lower scale is blinking, the toner level in the developing container 32 is at the NearOut level. As shown in Figure 14(b), when only the lower scale is lit, the toner level in the developing container 32 is at the Low level. As shown in Figure 14(c), when the lower and middle scales are lit and the upper scale is off, the toner level in the developing container 32 is at the Mid level. As shown in Figure 14(d), when all three scales are lit, the toner level in the developing container 32 is at the Full level.

[0076] The NearOut level indicates the amount of toner remaining in the developing container 32, which is about to run out and will no longer be able to properly form an image. The Low level indicates a toner level higher than the NearOut level and lower than the Mid level. The Mid level indicates a toner level higher than the Low level and lower than the Full level.

[0077] The toner level panel 400 is not limited to a liquid crystal panel; it may also consist of a light source such as an LED or incandescent lamp and a diffusion lens. Furthermore, the placement of the toner level panel 400 is not limited to the right side. For example, it may be placed on the left side, the same side as the operation unit 300. Alternatively, instead of providing a separate toner level panel 400, the toner level may be displayed on the display of the operation unit 300 using the scales described in this embodiment. Additionally, when the toner level in the developing container 32 reaches a low level, a toner replenishment notification may be displayed on the operation unit 300 to prompt to replenish the toner. Furthermore, when the toner runs out, a toner replenishment notification may be displayed on the operation unit 300 to prompt to replenish the toner.

[0078] Furthermore, although this embodiment describes a configuration that displays four states using three scales, the number of scales is not limited to this and may be set appropriately according to the configuration of the image forming apparatus. Also, the toner level may be continuously displayed using a percentage display or gauge display. In addition, the toner level may be notified to the user via voice using a speaker.

[0079] Furthermore, in the examples shown in Figures 14(a) to (d), the toner level panel 400 was described as a notification means for indicating the remaining toner level, but this is not limited to this. For example, the display in Figure 14(b) could be used to indicate that toner replenishment is needed, the display in Figure 14(c) could be used to indicate that toner replenishment is not needed, and the display in Figure 14(d) could be used to indicate that sufficient toner has been replenished.

[0080] Furthermore, the light-emitting element 510a and the light-receiving element 510b in this embodiment are arranged side by side along the longitudinal LD ​​of the process unit 20, and are located on the same side (front side) relative to the transport chamber 36 when viewed along the longitudinal LD. This allows the light-emitting element 510a and the light-receiving element 510b to be arranged compactly. In addition, the light-emitting element 510a and the light-receiving element 510b are provided together on the substrate 700. This allows power to be easily supplied to the light-emitting element 510a and the light-receiving element 510b, and signals can be easily exchanged between the light-emitting element 510a and the light-receiving element 510b. Thus, the process unit 20 can be miniaturized.

[0081] [Light guide component] Next, the configuration of the light guide member 600 in this embodiment will be described in more detail. Figures 15(a, b) are perspective views showing the light guide member 600 as a single component before it is integrated with the developing container lid 321. Figure 15(a) shows the front side of the light guide member 600, i.e., the side that does not come into contact with the developer inside the developing container 32 and is exposed to the outside of the developing container 32. Figure 15(b) shows the back side of the light guide member 600, i.e., the side that comes into contact with the developer inside the developing container 32 and is exposed to the inside of the developing container 32. The detection light OP shown in Figures 15(a, b) represents the representative optical path (optical axis) of the light emitted from the aforementioned light-emitting element 510a, passing through the light guide member 600, and being received by the light-receiving element 510b. The spatial optical path Q described above is the portion of the path followed by the detection light OP that passes through the internal space of the developing container 32.

[0082] Figures 16(a-e) show the light guide member 600 and the detection light OP from five directions using third-angle projection, with the back side of the light guide member 600 as the front. Figure 16(a) is a front view showing the back side of the light guide member 600. Figure 16(b) is a side view of the longitudinal LD ​​as seen from the light-emitting element 510a side. Figure 16(c) is a side view of the longitudinal LD ​​as seen from the light-receiving element 510b side. Figure 16(d) is a plan view seen from above the height direction ND. Figure 16(e) is a bottom view of the light guide member 600 and an enlarged view of a part thereof as seen from below the height direction ND.

[0083] In the following explanation, the vertical direction refers to the gravity direction WD (vertical direction) in the orientation of the light guide member 600 when it detects the amount of developer (position at detection, see Figure 12). The gravity direction WD does not necessarily coincide with the height direction ND of the light guide member 600, which will be described later. Furthermore, the direction perpendicular to both the longitudinal direction LD and the gravity direction WD of the developing container 32 is defined as the horizontal direction HD.

[0084] As shown in Figures 15(a) to 16(d), the light guide member 600 is a component in which the light-emitting side light guide 610, the light-receiving side light guide 620, and the frame portion 650 are integrally formed. The light guide member 600 is made of a translucent resin material that transmits light emitted by the light-emitting element 501a, and is integrally molded by a molding method such as injection molding. Note that the light guiding means is not limited to a configuration in which the light-emitting side light guide 610 and the light-receiving side light guide 620 are integrally molded via the frame portion 650, but for example, the light-emitting side light guide 610 and the light-receiving side light guide 620 may be molded as separate components and each attached to the developing container lid 321.

[0085] (Frame) The frame portion 650 is a plate-like portion that, together with the developing container lid 321, constitutes the wall surface of the developing container 32. The frame portion 650 has an installation surface 680 (Figure 17(a, b)) which is the surface that abuts against the mounting seat surface 3211 of the developing container lid 321, which will be described later.

[0086] (Light-emitting side light guide) The light-emitting side light guide 610 is a light guide for guiding the detection light OP emitted from the light-emitting element 501a on the outside of the developing container 32 into the transport chamber 36. The light-emitting side light guide 610 includes an outer light guide portion 611 that protrudes from the surface 653 of the frame portion 650 toward the outside of the developing container 32, and an inner light guide portion 612 that protrudes from the back surface 654 of the frame portion 650 toward the inside of the developing container 32. Above the inner light guide portion 612, an inner upper portion 630 is provided, which is a portion that extends upward from the inner light guide portion 612. The inner upper portion 630, together with the inner light guide portion 612, protrudes from the back surface 654 of the frame portion 650 toward the inside of the developing container 32.

[0087] The outer light guide portion 611 of the light-emitting side light guide 610 protrudes outward from the frame portion 653, which forms part of the outer surface of the developing container 32, toward the right side of the developing container 32 (right side in Figure 16(b)). The outer light guide portion 611 is the first protrusion in this embodiment. The inner light guide portion 612 and the inner upper portion 630 of the light-emitting side light guide 610 protrude inward from the back surface 654, which forms part of the inner surface of the developing container 32, toward the left side of the developing container 32 (left side in Figure 16(b)). The inner light guide portion 612 and the inner upper portion 630 are the second protrusions in this embodiment. The inner light guide portion 612 is the lower part of the second protrusion in this embodiment, and the inner upper portion 630 is the upper part of the second protrusion in this embodiment.

[0088] The protrusion direction TD of the outer light guide portion 611, inner light guide portion 612, and inner upper portion 630 relative to the frame portion 650 is substantially perpendicular to the mounting surface 680, which is the surface of the frame portion 650 that abuts the developing container lid 321 (a direction perpendicular to both the longitudinal direction LD and the height direction ND). However, the outer light guide portion 611, inner light guide portion 612, or inner upper portion 630 may protrude at an angle that intersects obliquely with the direction perpendicular to the mounting surface 680. The protrusion direction TD is also the optical axis direction of the detection light OP guided from the outer light guide portion 611 toward the inner light guide portion 612 inside the light-emitting side light guide body 610.

[0089] In this embodiment, the side surface of the inner upper part 630 is continuous with the side surface of the inner light guide part 612, and the inner upper part 630 is integrally formed from the same material as the inner light guide part 612. However, the inner upper part 630 and the inner light guide part 612 may be formed from different materials.

[0090] The inner upper part 630 differs in function from the inner light guide part 612 in that its shape is not designed to guide the detection light OP. Therefore, the boundary line between the inner light guide part 612 and the inner upper part 630 is shown as the first imaginary line IL1. When viewed in the longitudinal direction LD, the first imaginary line IL1 is a straight line that passes through the boundary part 611ct between the upper surface 611c of the outer light guide part 611 and the surface 653 of the frame part 650, and extends in the direction of the optical axis of the detection light OP from the outer light guide part 611 to the inner light guide part 612. In other words, the part of the second protrusion that substantially forms the optical path of the detection light OP (the part below the first imaginary line IL1) is designated as the inner light guide part 612, and the part that does not substantially contribute to the formation of the optical path of the detection light OP (the part above the first imaginary line IL1) is designated as the inner upper part 630.

[0091] (Light-receiving light guide) The light-receiving light guide 620 is a light guide that directs light incident via the spatial light path Q in the transport chamber 36 to the light-receiving element 501b on the outside of the developing container 32. The light-receiving light guide 620 includes an outer light guide portion 621 that protrudes from the surface 653 of the frame portion 650 toward the outside of the developing container 32, and an inner light guide portion 622 that protrudes from the back surface 654 of the frame portion 650 toward the inside of the developing container 32. The light-receiving light guide 620 also has an inner upper portion 640 above the inner light guide portion 622, which is a portion that extends upward from the inner light guide portion 622. The inner upper portion 640, together with the inner light guide portion 622, protrudes from the back surface 654 of the frame portion 650 toward the inside of the developing container 32.

[0092] The outer light guide portion 621 of the light-receiving light guide body 620 is the fourth protrusion of this embodiment, projecting outwards from the surface 653 of the frame portion 650, which constitutes a part of the outer surface of the developing container 32, toward the outside of the developing container 32 (left side in Figure 16(c)). The inner light guide portion 622 and the inner upper portion 640 of the light-receiving light guide body 620 are the third protrusion of this embodiment, projecting outwards from the back surface 654 of the frame portion 650, which constitutes a part of the inner surface of the developing container 32, toward the inside of the developing container 32 (right side in Figure 16(c)). The inner light guide portion 622 is the lower part of the third protrusion in this embodiment, and the inner upper portion 640 is the upper part of the third protrusion in this embodiment.

[0093] The protrusion direction TD of the outer light guide portion 621, inner light guide portion 622, and inner upper portion 640 relative to the frame portion 650 is substantially perpendicular to the mounting surface 680 of the frame portion 650 (a direction perpendicular to both the longitudinal direction LD and the height direction ND). In other words, the protrusion direction of the outer light guide portion 621, inner light guide portion 622, and inner upper portion 640 of the light-receiving light guide body 620 relative to the frame portion 650 is substantially the same as the protrusion direction TD of the outer light guide portion 611, inner light guide portion 612, and inner upper portion 630 of the light-emitting light guide body 610. However, the outer light guide portion 621, inner light guide portion 622, or the inner upper portion 640 of the light-receiving light guide body 620 may protrude at an angle that intersects obliquely with the direction perpendicular to the mounting surface 680. The protruding direction TD is the optical axis direction of the detection light OP guided from the outer light guide portion 621 toward the inner light guide portion 622 inside the light-receiving light guide body 620.

[0094] In this embodiment, the side surface of the inner upper part 640 of the light-receiving light guide 620 is continuous with the side surface of the inner light guide portion 622, and the inner upper part 640 is integrally formed from the same material as the inner light guide portion 622. However, the inner upper part 640 may be formed from a different material than the inner light guide portion 622.

[0095] The inner upper part 640 of the light-receiving light guide 620 has a different function from the inner light guide portion 622 in that it is not shaped to guide the detection light OP. Therefore, the boundary line between the inner light guide portion 622 and the inner upper part 640 is shown as the second imaginary line IL2. The second imaginary line IL2 is a straight line that extends in the direction of the optical axis of the detection light OP from the inner light guide portion 622 toward the outer light guide portion 621, passing through the boundary portion 621ct between the upper surface 621c of the outer light guide portion 621 and the surface 653 of the frame portion 650, when viewed in the longitudinal direction LD. In other words, the part of the third protrusion that substantially forms the optical path of the detection light OP (the part below the second imaginary line IL2) is designated as the inner light guide portion 622, and the part that is not substantially necessary for forming the optical path of the detection light OP (the part above the second imaginary line IL2) is designated as the inner upper part 640.

[0096] (Optical path design) The outer light guide portion 611 of the light-emitting side light guide 610 has an incident surface 611a (first incident surface) into which the detection light OP irradiated from the light-emitting element 510a is incident. The incident surface 611a is provided at the tip of the outer light guide portion 611 in the projection direction TD of the outer light guide portion 611 relative to the surface 653 of the frame portion 650 (outer surface of the developing container 32). The light-emitting element 510a (Figure 9(b)) is positioned to face the incident surface 611a. The light irradiated from the light-emitting element 510a is generally diffuse light, and the incident surface 611a has a convex lens shape in order to correct this to light in a single direction. The lens shape is designed considering the distance between the light-emitting element 510a and the incident surface 611a.

[0097] The inner light guide portion 612 of the light-emitting side light guide 610 has a reflective surface 612b and a light-emitting window 612a. The reflective surface 612b is a surface that changes the direction of the detection light OP inside the light-emitting side light guide 610 by specularly reflecting the detection light OP that has been incident on the incident surface 611a of the outer light guide portion 611 and passed from the outer light guide portion 611 to the inner light guide portion 612 toward the light-emitting window 612a. The light-emitting window 612a is an emission surface (second emission surface) that emits the detection light OP reflected by the reflective surface 612b toward the spatial light path Q in the transport chamber 36.

[0098] The inner light guide portion 622 of the light-receiving light guide 620 has a light-receiving window 622a and a reflective surface 622b. The light-receiving window 622a is the incident surface (second incident surface) into which the detection light OP passing through the spatial optical path Q in the transport chamber 36 enters the light-receiving light guide 620. The reflective surface 622b is the surface that changes the direction of the detection light OP inside the light-emitting light guide 610 by specularly reflecting the detection light OP that has entered the light-receiving window 622a of the inner light guide portion 622 toward the outer light guide portion 621.

[0099] The outer light guide portion 621 of the light-receiving light guide body 620 has an output surface 621a (first output surface) that emits detection light OP, which is incident on the light-receiving window 622a of the inner light guide portion 622 and whose orientation is changed by the reflective surface 622b, toward the light-receiving element 510b. The output surface 621a is provided at the tip of the outer light guide portion 621 in the direction of protrusion TD of the outer light guide portion 621 relative to the surface 653 of the frame portion 650 (outer surface of the developing container 32). The light-receiving element 510b (Figure 9(b)) is positioned to face the output surface 621a of the light-receiving light guide body 620.

[0100] The light-emitting window 612a of the light-emitting side light guide 610 and the light-receiving window 622a of the light-receiving side light guide 620 are arranged to face each other inside the developing container 32. A spatial light path Q is formed between the light-emitting window 612a and the light-receiving window 622a through which the detection light OP passes. In this embodiment, the light-emitting window 612a and the light-receiving window 622a face each other in the longitudinal direction LD inside the developing container 32. In this embodiment, the orientation of the spatial light path Q is substantially parallel to the longitudinal direction LD of the developing container 32, but the spatial light path Q may be set to an orientation different from the longitudinal direction LD as long as it intersects with the gravity direction WD. In this embodiment, the orientation of the spatial light path Q is the longitudinal direction LD, and the light guide member 600 is arranged so that the spatial light path Q passes through the position of the center 31a of the developing roller 31 in the longitudinal direction LD (dashed line in Figure 10(b)). This makes the system less susceptible to the uneven distribution of developer within the transport chamber 36, thus improving the accuracy of developer quantity detection. However, the light guide member 600 may be placed in other locations.

[0101] (Relationship between stirring member and light guide member) Here, the configuration of the stirring member 34 related to the light guide member 600 will be described. As shown in Figure 4(c), the stirring member 34 has a wiping section 34c including an emitting side wiping end 34c1 and a receiving side wiping end 34c2, and a wiping auxiliary section 34d, at a position facing the light guide member 600 in the longitudinal direction LD. The wiping auxiliary section 34d is positioned on the downstream side in the rotational direction of the stirring member 34, overlapping with the wiping section 34c. These wiping sections 34c and wiping auxiliary section 34d are flexible sheets. Furthermore, the rotational trajectory Tc of the wiping section 34c as viewed in the axial direction (longitudinal direction LD) of the stirring member 34 is set to coincide with the spatial light path Q (see Figure 10(a)). The rotational trajectory Tc of the wiping section 34c is drawn as a circle with a rotational radius that assumes the wiping section 34c extends straight around the rotational axis of the stirring member 34, ignoring the wall surface of the developing container 32.

[0102] As the stirring member 34 rotates, the light-emitting side wiping end 34c1 passes through the light guide member 600 while rubbing against the light-emitting window 612a of the light-emitting side light guide body 610, and the light-receiving side wiping end 34c2 passes through the light guide member 600 while rubbing against the light-receiving window 622a of the light-receiving side light guide body 620. In other words, with each rotation of the stirring member 34, the developer adhering to the light-emitting window 612a and the light-receiving window 622a is wiped away by the wiping section 34c. The wiping assist section 34d is for adjusting the contact pressure and entry angle of the wiping section 34c against the light-emitting window 612a and the light-receiving window 622a, and is designed taking into account the shape and positional relationship between the light guide member 600 and the stirring member 34. Note that if the developer wiping performance of the wiping section 34c alone is sufficient, the wiping assist section 34d may be omitted. Alternatively, the wiping section 34c may be omitted, and the blades of the stirring member 34 may be used to clean the light-emitting window 612a and the light-receiving window 622a of the light-guiding member 600.

[0103] As shown in the enlarged view A of Figure 16(e), which is a bottom view of the light guide member 600, the light-emitting window 612a is not a perfect plane, but has a curved shape that is convex toward the side of the spatial light path Q (inside the developing container 32) when viewed in the ND direction of height. Similarly, the light-receiving window 622a also has a curved shape that is convex toward the side of the spatial light path Q (inside the developing container 32) when viewed in the ND direction of height. As a result, the wiping portion 34c of the stirring member 34 makes strong local contact with the apex of the curved surfaces of the light-emitting window 612a and the light-receiving window 622a, allowing the developer to be wiped off more strongly.

[0104] (Positioning and integration of the light guide member with the developing container) Here, we will explain the positioning and integration method of the light guide member 600 with the developing container 32 (developing container lid 321). Figure 17(a, b) is a perspective view showing the light guide member 600 as a single component before integration with the developing container lid 321.

[0105] The developing container lid 321 has two surfaces 3212a and 3212b for determining the position of the light guide member 600 in the longitudinal direction LD, and two surfaces 3212c and 3212d for determining the position of the light guide member 600 in the height direction ND. Surfaces 3212a and 3212b face each other in the longitudinal direction LD and extend in the height direction ND. Surfaces 3212c and 3212d face each other in the height direction ND and extend in the longitudinal direction LD. These surfaces 3212a to 3212d form a rectangular opening 3212 for exposing the light guide member 600 to the inside of the developing container 32.

[0106] The height direction ND of the light guide member 600 is perpendicular to the longitudinal direction LD and parallel to the mounting base surface 3211. The height direction ND does not necessarily coincide with the gravity direction WD in the orientation when the light guide member 600 is integrated with the developing container 32 and assembled to the image forming apparatus 2 (the orientation when detecting the amount of developer). In this embodiment, the light guide member 600 is inclined such that, when viewed in the longitudinal direction LD, the height direction ND intersects the gravity direction WD at a small angle (Figure 10(a)). The light guide member 600 is inclined such that the lower part of the light guide member 600 in the height direction ND is close to the rotation center of the stirring member 34 in the horizontal direction HD, and the upper part of the light guide member 600 is farther from the rotation center of the stirring member 34 in the horizontal direction HD.

[0107] As shown in Figure 17(a, b), the light guide member 600 has a first positioning rib 661 and a second positioning rib 662 on the surface (installation surface 680) that abuts against the mounting seat surface 3211 of the developing container lid 321. The first positioning rib 661 and the second positioning rib 662 protrude from the installation surface 680 so as to protrude into the space inside the opening 3212 of the mounting seat surface 3211 when the installation surface 680 is in contact with the mounting seat surface 3211.

[0108] The first positioning rib 661 includes a surface 661a for determining the position of the longitudinal LD ​​and surfaces 661c and 661d for determining the position of the height ND. The second positioning rib 662 includes a surface 662b for determining the position of the longitudinal LD ​​and surfaces 662c and 662d for determining the position of the height ND. The engagement of surfaces 3212a and 3212b of the developing container lid 321 with surfaces 661a and 662b of the light guide member 600 determines the position of the longitudinal LD ​​of the light guide member 600 relative to the developing container lid 321. The engagement of surfaces 3212c and 3212d of the developing container lid 321 with surfaces 661c, 662c, 661d, and 662d of the light guide member 600 determines the position of the height ND of the light guide member 600 relative to the developing container lid 321.

[0109] The developing container lid 321 and the light guide member 600 are integrated by welding the director portion 670 provided on the light guide member 600 to the mounting seat surface 3211 of the developing container lid 321 by ultrasonic welding. The director portion 670 is a melting allowance provided in a rectangular area surrounding the opening 3212 of the developing container lid 321 (see also Figure 15(b)). Furthermore, as described above, the developing container 32 is integrated by joining the developing container frame 320 and the developing container lid 321.

[0110] In this embodiment, the developing container lid 321 and the light guide member 600 are integrated (joined) by ultrasonic welding, but the integration method (joining method) is not limited to this. Any method that can integrate the light guide member 600 and the developing container lid 321 without any gaps may be used, for example, by using double-sided tape or adhesive.

[0111] (Details of the upper part of the light-emitting side and the upper part of the light-receiving side) Next, the configuration of the inner upper part 630 of the light-emitting side light guide 610 and the inner upper part 640 of the light-receiving side light guide 620 in this embodiment will be described in detail. Figure 18 is a perspective view of the back side of the light guide member 600 attached to the developing container lid 321, seen from inside the transport chamber 36 in which the developer is contained.

[0112] First, the inner upper part 630 of the light-emitting side light guide 610 will be described. The inner upper part 630 has a first side surface 630a that extends upward from the light-emitting window 612a along the height direction ND, and a second side surface 630b that extends upward from the reflective surface 612b along the height direction ND. The inner upper part 630 also has an upper surface 630c (first upper surface) that connects the upper edges of these first side surface 630a and second side surface 630b to the back surface 654 of the frame portion 650 (the wall surface of the developing container 32). When viewed in the height direction ND, the upper surface 630c covers the area enclosed by the light-emitting window 612a, the reflective surface 612b, and the back surface 654 of the frame portion 650. In other words, when viewed in the height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, the upper surface of the second protrusion covers the area enclosed by the wall surface, the first emission surface, and the first reflection surface.

[0113] The upper surface 630c of the inner upper part 630 is a surface that intersects the gravity direction WD and the height direction ND. In this embodiment, the upper surface 630c is perpendicular to the height direction ND, or slightly inclined with respect to the height direction ND as a draft angle during molding. The direction of the inclination is downward in the height direction ND as it moves away from the back surface 654 (wall surface of the developing container) of the frame part 650, in the protruding direction TD (protruding direction of the second protruding part) of the inner light guide part 612 and the inner upper part 630.

[0114] As shown in Figure 16(b), the upper surface 630c of the inner upper part 630 is located above the first extension line EL1 of the upper surface 611c of the outer light guide portion 611 of the light-emitting side light guide body 610 when viewed in the longitudinal LD ​​direction in the developer amount detection position. The first extension line EL1 is a virtual straight line (first virtual straight line) drawn along the upper surface 611c of the outer light guide portion 611 when viewed in the longitudinal LD ​​direction. The light-emitting window 612a that forms the optical path of the detection light OP is located below the first extension line EL1 when viewed in the longitudinal LD ​​direction.

[0115] Furthermore, as shown in Figure 16(b), the upper surface 630c of the inner upper part 630 is located above the first virtual line IL1 described above when viewed in the longitudinal direction LD in the orientation when detecting the amount of developer. The upper surface 630c is located above the horizontal plane perpendicular to the direction of gravity WD that passes through the boundary portion 611ct between the upper surface 611c of the outer light guide portion 611 and the surface 653 of the frame portion 650. As described above, the region above the first virtual line IL1 is a portion that does not substantially contribute to the formation of the optical path of the detection light OP.

[0116] Here, the outer light guide portion 611 of the light-emitting side light guide 610 is formed in the shape of a rectangular prism extending in the protruding direction TD, or in the shape of a truncated pyramidal pyramid with a slight draft angle so that the cross-sectional area decreases toward the outside of the developing container 32 in order to improve release properties during molding. Therefore, inside the developing container 32, the first extension line EL1 of the upper surface 611c of the outer light guide portion 611 coincides with the first imaginary line IL1, or is located above the first imaginary line IL1. Consequently, when viewed in the longitudinal direction LD in the posture when detecting the amount of developer, the upper surface 630c of the inner upper part 630 of the light-emitting side light guide 610 is located above the first extension line EL1 of the upper surface 611c of the outer light guide portion 611.

[0117] In other words, in this embodiment, an inner upper part 630 (first upper part), which is not originally necessary for forming the optical path of the detection light OP, is provided above the inner light guide portion 612 (first lower part) of the light-emitting side light guide 610. The upper surface 630c (first upper surface) of the inner upper part 630 is positioned above the first extension line EL1 (first virtual straight line) drawn along the upper surface 611c of the outer light guide portion 611 of the light-emitting side light guide 610. To put it another way, when viewed in a direction that intersects both the protrusion direction TD (first direction) and the gravity direction WD of the outer light guide portion 611 (first protrusion) relative to the wall surface of the developing container 32, the upper surface 630c (first upper surface) of the inner upper part 630 is positioned above the first extension line EL1 (first virtual straight line). Here, the direction intersecting both the first direction and the gravity direction WD is preferably a direction perpendicular to the gravity direction WD and along the wall surface of the developing container 32 where the light guide member 600 is provided. Furthermore, the direction intersecting both the first direction and the gravity direction WD is preferably a direction in which the inner light guide portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, it is the longitudinal direction LD of the developing container 32.

[0118] Next, the inner upper part 640 of the light-receiving light guide 620 will be described. The inner upper part 640 has a first side surface 640a that extends upward from the light-receiving window 622a along the height direction ND, and a second side surface 640b that extends upward from the reflective surface 622b along the height direction ND. The inner upper part 640 also has an upper surface 640c (second upper surface) that connects the upper edges of these first side surface 640a and second side surface 640b to the back surface 654 of the frame portion 650 (the wall surface of the developing container). When viewed in the height direction ND, the upper surface 640c covers the area enclosed by the light-receiving window 622a, the reflective surface 622b, and the back surface 654 of the frame portion 650. In other words, when viewed in the height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, the upper surface of the third protrusion covers the area enclosed by the wall surface, the second incident surface, and the second reflective surface.

[0119] The upper surface 640c of the inner upper part 640 is a surface that intersects the gravity direction WD and the height direction ND. In this embodiment, the upper surface 640c is perpendicular to the height direction ND, or slightly inclined with respect to the height direction ND as a draft angle during molding. The direction of the inclination is downward in the height direction ND as it moves away from the back surface 654 (wall surface of the developing container) of the frame part 650, in the protruding direction TD (protruding direction of the third protruding part) of the inner light guide part 622 and the inner upper part 640.

[0120] As shown in Figure 16(c), the upper surface 640c of the inner upper part 640 is located above the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 of the light receiving side light guide body 620 when viewed in the longitudinal LD ​​direction in the developer amount detection position. The second extension line EL2 is a virtual straight line (second virtual straight line) drawn along the upper surface 621c of the outer light guide portion 621 when viewed in the longitudinal LD ​​direction. The light receiving window 622a that forms the optical path of the detection light OP is located below the second extension line EL2 when viewed in the longitudinal LD ​​direction.

[0121] Furthermore, as shown in Figure 16(c), the upper surface 640c of the inner upper part 640 is located above the second virtual line IL1 described above when viewed in the longitudinal direction LD in the orientation when detecting the amount of developer. The upper surface 640c is located above the horizontal plane perpendicular to the direction of gravity WD that passes through the boundary portion 621ct between the upper surface 621c of the outer light guide portion 621 and the surface 653 of the frame portion 650. As described above, the region above the second virtual line IL2 is a portion that does not substantially contribute to the formation of the optical path of the detection light OP.

[0122] Here, the outer light guide portion 621 of the light-receiving light guide 620 is formed in the shape of a rectangular prism extending in the protruding direction TD, or in the shape of a truncated pyramidal pyramid with a slight draft angle so that the cross-sectional area decreases toward the outside of the developing container 32 in order to improve release properties during molding. Therefore, inside the developing container 32, the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 coincides with the second imaginary line IL2, or is located above the second imaginary line IL2. Consequently, when viewed in the longitudinal direction LD in the orientation when detecting the amount of developer, the upper surface 640c of the inner upper part 640 of the light-receiving light guide 620 is located above the second extension line EL2 of the upper surface 621c of the outer light guide portion 621.

[0123] In other words, in this embodiment, an inner upper part 640 (second upper part), which is not originally necessary for forming the optical path of the detection light OP, is provided above the inner light guide portion 622 (second lower part) of the light-receiving light guide body 620. Furthermore, the upper surface 640c (second upper surface) of the inner upper part 640 is positioned above the second extension line EL2 (second virtual straight line) drawn along the upper surface 611c of the outer light guide portion 611 of the light-receiving light guide body 620. To put it another way, when viewed in a direction that intersects both the protrusion direction TD (second direction) and the gravity direction WD of the outer light guide portion 621 (fourth protrusion) relative to the wall surface of the developing container 32, the upper surface 640c (second upper surface) of the inner upper part 640 is positioned above the second extension line EL2 (second virtual straight line). Here, the direction intersecting both the second direction and the gravity direction WD is preferably a direction perpendicular to the gravity direction WD and along the wall surface of the developing container 32 where the light guide member 600 is provided. Furthermore, the direction intersecting both the second direction and the gravity direction WD is preferably a direction in which the inner light guide portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, it is the longitudinal direction LD of the developing container 32.

[0124] (Advantages of this embodiment) When the developer in the transport chamber 36 is stirred by the stirring member 34, the developer accumulates on the upper surfaces 630c and 640c of the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 due to gravity and inertial forces. If the amount of accumulated developer increases, the developer may grow into aggregates due to electrostatic forces and liquid crosslinking forces acting between the developer particles, and for example, these aggregates may extend and adhere to the first side surfaces 630a and 640a of the inner upper parts 630 and 640.

[0125] In the conventional configuration, where the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 are absent, the upper surfaces of the inner light guide sections 612 and 622 (the upward-facing surfaces at the positions of the first virtual line IL1 and the second virtual line IL2) are exposed into the transport chamber 36. In this configuration, aggregates of developer that accumulate and grow on the upper surfaces of the inner light guide sections 612 and 622 may reach and adhere to the light-emitting window 612a or light-receiving window 622a adjacent to the upper surface. In this case, the optical path of the detection light OP may be blocked by the developer adhering to the light-emitting window 612a or light-receiving window 622a, potentially reducing the accuracy of developer quantity detection.

[0126] In contrast, in this embodiment, the upper surface 630c of the inner upper part 630 of the light-emitting side light guide 610 is located above the first extension line EL1 of the upper surface 611c of the outer light guide part 611 (Figure 16(b)). Also, the upper surface 640c of the inner upper part 640 of the light-receiving side light guide 620 is located above the second extension line EL2 of the upper surface 621c of the outer light guide part 621 (Figure 16(c)). Therefore, even if the developer accumulates on the upper surfaces 630c and 640c and grows into aggregates, it becomes difficult for the aggregates to reach the light-emitting window 612a or the light-receiving window 622a. As a result, the possibility of the optical path of the detection light OP being blocked by the developer adhering to the light-emitting window 612a or the light-receiving window 622a is reduced.

[0127] Therefore, the configuration of this embodiment makes it possible to suppress a decrease in the detection accuracy of the toner level sensor 500. In other words, it is possible to reduce false detection of the amount of developer (a decrease in detection accuracy) caused by the developer blocking the light-emitting window 612a or the light-receiving window 622a at an unexpected time, which shortens the time that the light-receiving element 510b receives the detection light OP (or reduces the received light intensity).

[0128] Furthermore, in this embodiment, the simplistic configuration in which the inner upper parts 630 and 640 are integrally molded from the same material as the inner light guides 612 and 622 to the light-emitting side light guide 610 and the light-receiving side light guide 620 reduces the likelihood of misdetection of the developer amount.

[0129] Furthermore, the greater the vertical ND distance between the upper surface 630c of the inner upper part 630 of the light-emitting side light guide 610 and the light-emitting window 612a, the less likely it is that aggregates of developer originating from the upper surface 630c will reach the light-emitting window 612a. Similarly, the greater the vertical ND distance between the upper surface 640c of the inner upper part 640 of the light-receiving side light guide 620 and the light-receiving window 622a, the less likely it is that aggregates of developer originating from the upper surface 640c will reach the light-receiving window 622a. Therefore, the greater the distance between the upper surfaces 630c, 640c and the light-emitting window 612a and the light-receiving window 622a, the more reliably false detection of the amount of developer can be reduced.

[0130] Specifically, the height of the second protrusion adjacent to the frame portion 650 is set to, for example, 120% or more, more preferably 150% or more, of the height of the first protrusion adjacent to the frame portion 650 (see Figure 16(b)). The height of the second protrusion is the distance in the height direction ND from the lower surface 612f of the inner light guide portion 612 to the upper surface 630c of the inner upper portion 630, and the height of the first protrusion is the distance in the height direction ND from the lower surface 611f of the outer light guide portion 611 to the upper surface 611c. Furthermore, when viewed in the longitudinal direction LD, it is preferable to space the entire upper surface 630c of the inner upper portion 630 upward from the first extension line EL1 by at least 2 mm or more, more preferably 5 mm or more. This ensures the distance from the upper surface 630c to the upper edge of the light-emitting window 612a.

[0131] Similarly, the height of the third protrusion adjacent to the frame portion 650 is set to, for example, 120% or more, more preferably 150% or more, of the height of the fourth protrusion adjacent to the frame portion 650 (see Figure 16(c)). The height of the third protrusion is the distance in the height direction ND from the lower surface 622f of the inner light guide portion 622 to the upper surface 640c of the inner upper portion 640, and the height of the fourth protrusion is the distance in the height direction ND from the lower surface 621f of the outer light guide portion 621 to the upper surface 621c. Furthermore, when viewed in the longitudinal direction LD, it is preferable to space the entire upper surface 640c of the inner upper portion 640 upward from the second extension line EL2 by at least 2 mm or more, more preferably 5 mm or more. This ensures the distance from the upper surface 640c to the upper edge of the light receiving window 622a.

[0132] When determining the actual positions of the upper surfaces 630c and 640c of the inner upper parts 630 and 640, the optimal design should be achieved by considering factors such as the aggregation characteristics of the developer, interference with other components, and shrinkage of the light guide member 600.

[0133] [Differentiation] Next, a modified version of the first embodiment will be described. Figure 19 is a perspective view of the back side of the light guide member 600 attached to the developing container lid 321, seen from inside the transport chamber 36. As shown in Figure 19, the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 are configured as separate components from the inner light guide sections 612 and 622, respectively, and are fixed to the inner light guide sections 612 and 622. For example, the lower surface 630d of the inner upper part 630 of the light-emitting side light guide 610 is joined to the upper surface 612c of the inner light guide section 612 by adhesive means such as double-sided tape or adhesive. Also, the lower surface 640d of the inner upper part 640 of the light-receiving side light guide 620 is joined to the upper surface 622c of the inner light guide section 622 by adhesive means such as double-sided tape or adhesive. Furthermore, the method of joining the inner upper parts 630 and 640 and the inner light guide parts 612 and 622 is not limited to adhesive bonding; it may also be mechanical joining such as snap-fitting or welding such as ultrasonic welding.

[0134] As described above, configuring the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 as separate components from the inner light-guiding parts 612 and 622 offers the following advantages. Since the inner upper parts 630 and 640 do not contribute to the formation of the optical path of the detected light OP, the light-guiding performance of the light-guiding member 600 is maintained even if the inner upper parts 630 and 640 are manufactured separately from the other parts of the light-guiding member 600. Furthermore, in the first embodiment, care must be taken to prevent sink marks during molding because the light-guiding member 600 becomes thicker due to the inner upper parts 630 and 640, whereas in this modified example, the occurrence of sink marks due to the increased thickness is suppressed. Therefore, this modified example makes it possible to suppress the occurrence of sink marks when molding the part of the light-guiding member 600 excluding the inner upper parts 630 and 640 while maintaining the light-guiding performance of the light-guiding member 600.

[0135] Furthermore, the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 do not need to be made of the same material as the inner light guide sections 612 and 622. The inner upper parts 630 and 640 can be made of a material that has lower transmittance of detection light OP than the inner light guide sections 612 and 622 (for example, matte black polyethylene resin or polypropylene resin). Alternatively, a black paint that blocks detection light OP may be applied to the surface of the inner upper parts 630 and 640, which are formed of the same material as the inner light guide sections 612 and 622. This reduces stray light passing through the inner upper parts 630 and 640, and suppresses misdetection of the amount of developer due to stray light.

[0136] <Second Embodiment> A second embodiment of this disclosure will now be described. In this embodiment, the positional relationship between the inner upper parts 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 and the inner light guide parts 612, 622 differs from that of the first embodiment. The other configurations of the image forming apparatus 1 and process unit 20 are the same as those of the first embodiment. Hereinafter, elements denoted by the same reference numerals as in the first embodiment have substantially the same configuration and operation as those described in the first embodiment, and the parts that differ from the first embodiment will be described mainly.

[0137] Figure 20 is a perspective view of the back side of the light guide member 600 attached to the developing container lid 321, seen from inside the transport chamber 36. As shown in Figure 20, a slit 615 (first slit) is provided between the inner upper part 630 of the light-emitting side light guide body 610 and the inner light guide portion 612, and a slit 625 (second slit) is provided between the inner upper part 640 of the light-receiving side light guide body 620 and the inner light guide portion 622.

[0138] These slits 615 and 625 extend in a direction intersecting the gravity direction WD when the process unit 20 is inside the printer body 100, that is, in the position when the developer amount is detected (see Figure 12). Slit 615 is a first space formed between the lower surface 630d of the inner upper part 630 (first upper part) of the light-emitting side light guide 610 and the upper surface 612c of the inner light guide part 612 (first lower part). Slit 625 is a second space formed between the lower surface 640d of the inner upper part 640 (second upper part) of the light-receiving side light guide 620 and the upper surface 622c of the inner light guide part 622 (second lower part).

[0139] The slit 615 separates the inner light guide portion 612 and the inner upper portion 630 of the light-emitting side light guide 610, thereby suppressing stray light from the detection light OP through the inner light guide portion 612 and the inner upper portion 630 to the photodetector 510b. Similarly, the slit 625 separates the inner light guide portion 622 and the inner upper portion 640 of the light-receiving side light guide 620, thereby suppressing stray light from the detection light OP through the inner upper portion 640 and the inner light guide portion 622 to the photodetector 510b.

[0140] Furthermore, the lower surface 630d of the inner upper part 630 of the light-emitting side light guide 610 and the upper surface 612c of the inner light guide portion 612 do not necessarily have to be parallel. In this embodiment, due to the draft angle during molding, the lower surface 630d of the inner upper part 630 and the upper surface 612c of the inner light guide portion 612 are inclined relative to each other. That is, when viewed in the longitudinal LD ​​direction, the further the inner upper part 630 and the inner light guide portion 612 are from the back surface 654 of the frame portion 650 in the direction of protrusion of the frame portion 650, the wider the distance ND in the height direction between the lower surface 630d of the inner upper part 630 and the upper surface 612c of the inner light guide portion 612 becomes. Similarly, the lower surface 640d of the inner upper part 640 of the light-receiving side light guide 620 and the upper surface 622c of the inner light guide portion 622 do not necessarily have to be parallel. In this embodiment, the lower surface 640d of the inner upper part 640 and the upper surface 622c of the inner light guide part 622 are inclined relative to each other due to the draft angle during molding.

[0141] Furthermore, the width of the slits 615 and 625 is preferably narrow in order to prevent aggregates from growing from the developer that has entered the slits 615 and 625 and adhering to the light-emitting window 612a and the light-receiving window 622a. In this embodiment, considering the moldability (release properties) due to the draft angle during molding, the minimum width of the slits 615 and 625 (width at the position adjacent to the back surface 654 of the frame portion 650) is designed to be nominally 1 mm. However, this is not limited to this, and for example, if a developer that is less prone to aggregation is used, the width of the slits 615 and 625 may be set wider in consideration of moldability.

[0142] In this embodiment as well, the upper surface 630c of the inner upper part 630 of the light-emitting side light guide 610 is located above the first extension line EL1 of the upper surface 611c of the outer light guide portion 611 of the light-emitting side light guide 610 when viewed in the longitudinal direction LD in the position used for developer quantity detection. Similarly, the upper surface 640c of the inner upper part 640 of the light-receiving side light guide 620 is located above the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 of the light-receiving side light guide 620 when viewed in the longitudinal direction LD in the position used for developer quantity detection. Therefore, similar to the first embodiment, the possibility of developer aggregates growing from the upper surfaces 612c and 622c of the inner light guide portions 612 and 622 and reaching the light-emitting window 612a or the light-receiving window 622a can be reduced. This makes it possible to suppress false detection of the developer quantity (reduction in detection accuracy) by the toner remaining amount sensor 500.

[0143] In addition, according to this embodiment, by providing slits 615 and 625 between the inner light guide sections 612 and 622 and the inner upper sections 630 and 622, it is possible to suppress erroneous detection of the amount of developer due to stray light.

[0144] Furthermore, similar to the modified example described in the first embodiment, the inner upper part 630 of the light-emitting side light guide 610 may be a separate component from the inner light-guiding part 612, and the inner upper part 640 of the light-receiving side light guide 620 may be a separate component from the inner light-guiding part 622. This modified example makes it possible to suppress the occurrence of sink marks when molding the parts of the light guide member 600 excluding the inner upper parts 630 and 640, while maintaining the light-guiding performance of the light guide member 600. In addition, by making the inner upper parts 630 and 640 of a material that is less permeable to detection light OP than the inner light-guiding parts 612 and 622, it is possible to further suppress erroneous detection of the amount of developer due to stray light.

[0145] <Third Embodiment> A third embodiment of this disclosure will now be described. In this embodiment, the shape of the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 differs from that of the second embodiment. The other configurations of the image forming apparatus 1 and process unit 20 are the same as those of the first and second embodiments. Hereinafter, elements denoted by reference numerals common to the first and second embodiments will have substantially the same configuration and operation as those described in the first and second embodiments, and the parts that differ from the first and second embodiments will be described mainly.

[0146] Figure 21 is a perspective view of the back side of the light guide member 600 attached to the developing container lid 321, seen from inside the transport chamber 36. Figures 22(a-c) show the light guide member 600 as a single component. Figure 22(a) is a front view of the light guide member 600. Figure 22(b) is an enlarged view of the light-emitting region B in Figure 22(a). Figure 22(c) is an enlarged view of the light-receiving region C in Figure 22(a). Figures 23(a-c) show the light guide member 600 from three directions using third-angle projection. Figure 23(a) is a front view of the back side of the light guide member 600, Figure 23(b) is a side view of the light-emitting element 510a side in the longitudinal LD, and Figure 23(c) is a side view of the light-receiving element 510b side in the longitudinal LD.

[0147] As shown in Figure 21, the inner upper part 630 of the light-emitting side light guide 610 has a first side surface 631a (first offset surface) located above the light-emitting window 612a and a second side surface 631b located above the reflective surface 612b. The inner upper part 630 also has an upper surface 631c (first upward surface) located above the first side surface 631a and the second side surface 631b, and an end surface 631e (first end surface) provided at the tip in the direction normal to the mounting surface 680 of the frame portion 650 (projection direction TD). The upper surface 631c is a surface that extends in a direction intersecting the direction of gravity in the orientation when detecting the amount of developer (see Figure 12). The end surface 631e is adjacent to the first side surface 631a and the second side surface 631b, respectively, and is provided between the first side surface 631a and the second side surface 631b in the longitudinal direction LD.

[0148] As shown in Figure 22(b), the first side surface 631a and the end surface 631e are offset to the root side (upper side in the figure) in the protrusion direction TD of the inner light guide portion 612 so that they do not protrude relative to the light-emitting window 612a when viewed in the height direction ND. This prevents the first side surface 631a or the end surface 631e from obstructing the wiping of the light-emitting window 612a by the wiping portion 34c of the stirring member 34.

[0149] Furthermore, the end face 630e makes surface contact with the flexible sheet, such as the first blade portion 34b1 and the second blade portion 34b2 of the stirring member 34, thereby suppressing damage such as tearing of the sheet. The rib portion forming the second side surface 631b is intended to increase the surface area of ​​the end face 631e. For example, if a thick, tear-resistant sheet material is used for the blade portion 34b of the stirring member 34, the end face 631e and the second side surface 631b may be omitted.

[0150] The upper surface 631c includes an inclined surface 631s that slopes downward in the direction of gravity toward the tip side in the protruding direction TD of the inner upper part 630. Furthermore, the inclination angle of the inclined surface 641s is designed such that the angle it makes with the horizontal plane is greater than or equal to the angle of repose of the developer in the orientation when the amount of developer is detected (see Figure 12). In this way, by making at least a part of the upper surface 631c an inclined surface that is inclined with respect to the horizontal plane, the accumulation of developer on the upper surface 631c of the inner upper part 630 can be suppressed. Therefore, the upper surface 630c of the inner upper part 630 in the first and second embodiments may be inclined as the inclined surface 631s of this embodiment. Note that the first side surface 631a and the second side surface 631b have a larger angle with the horizontal plane than the upper surface 631c.

[0151] Furthermore, as shown in Figure 23(b), the upper surface 631c of the inner upper part 630 is located above the first extension line EL1 of the upper surface 611c of the outer light guide portion 611 of the light-emitting side light guide body 610 when viewed in the longitudinal direction LD in the position used for developer amount detection.

[0152] As shown in Figure 21, the inner upper part 640 of the light-receiving light guide 620 has a first side surface 641a (second offset surface) located above the light-receiving window 622a and a second side surface 641b located above the reflective surface 622b. The inner upper part 640 also has an upper surface 641c (first upward surface) located above the first side surface 641a and the second side surface 641b, and an end surface 641e (second end surface) provided at the tip in the direction normal to the mounting surface 680 of the frame portion 650 (projection direction TD). The upper surface 641c is a surface that extends in a direction intersecting the direction of gravity in the orientation when detecting the amount of developer (see Figure 12). The end surface 641e is adjacent to the first side surface 641a and the second side surface 641b, respectively, and is provided between the first side surface 641a and the second side surface 641b in the longitudinal direction LD.

[0153] As shown in Figure 22(c), the first side surface 641a and the end surface 641e are offset to the base side (upper side in the figure) in the protrusion direction TD of the inner light guide portion 622 so that they do not protrude relative to the light receiving window 622a when viewed in the height direction ND. This prevents the first side surface 641a or the end surface 641e from obstructing the wiping of the light receiving window 622a by the wiping portion 34c of the stirring member 34.

[0154] Furthermore, the end face 640e makes surface contact with the flexible sheet, such as the first blade portion 34b1 and the second blade portion 34b2 of the stirring member 34, thereby suppressing damage such as tearing of the sheet. The rib portion forming the second side surface 641b is intended to increase the surface area of ​​the end face 641e. For example, if a thick, tear-resistant sheet material is used for the blade portion 34b of the stirring member 34, the end face 641e and the second side surface 641b may be omitted.

[0155] The upper surface 641c includes an inclined surface 641s that slopes downward in the direction of gravity toward the tip side in the protruding direction TD of the inner upper part 640. Furthermore, the inclination angle of the inclined surface 641s is designed such that the angle it makes with the horizontal plane is greater than or equal to the angle of repose of the developer in the orientation when the amount of developer is detected (see Figure 12). In this way, by making at least a part of the upper surface 641c an inclined surface with respect to the horizontal plane, the accumulation of developer on the upper surface 641c of the inner upper part 640 can be suppressed. Therefore, the upper surface 640c of the inner upper part 640 in the first and second embodiments may be inclined as the inclined surface 641s of this embodiment. Note that the first side surface 641a and the second side surface 641b have a larger angle with the horizontal plane than the upper surface 641c.

[0156] Furthermore, as shown in Figure 23(c), the upper surface 641c of the inner upper part 640 is located above the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 of the light receiving side light guide body 620 when viewed in the longitudinal direction LD in the position when detecting the amount of developer.

[0157] Since the angle of repose varies depending on the developer, the inclination angles of the inclined surfaces 631s and 641s provided on the upper surfaces 631c and 641c of the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 can be appropriately changed according to the characteristics of the developer. Even if the inclination angles of the inclined surfaces 631s and 641s are less than the angle of repose, if the angle that the inclined surfaces 631s and 641s make with the horizontal plane is greater than the angle that the upper surfaces 612c and 622c of the inner light guide parts 612 and 622 make with the horizontal plane, the effect of suppressing developer deposition can be obtained.

[0158] In this embodiment as well, the upper surface 631c of the inner upper part 630 of the light-emitting side light guide 610 is located above the first extension line EL1 of the upper surface 611c of the outer light guide portion 611 of the light-emitting side light guide 610 when viewed in the longitudinal direction LD in the position used for developer quantity detection. Similarly, the upper surface 641c of the inner upper part 640 of the light-receiving side light guide 620 is located above the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 of the light-receiving side light guide 620 when viewed in the longitudinal direction LD in the position used for developer quantity detection. Therefore, similar to the first embodiment, the possibility of developer aggregates growing from the upper surfaces 612c and 622c of the inner light guide portions 612 and 622 and reaching the light-emitting window 612a or the light-receiving window 622a can be reduced. This makes it possible to suppress false detection of the developer quantity (reduction in detection accuracy) by the toner remaining amount sensor 500.

[0159] In addition, according to this embodiment, since inclined surfaces 631s and 641s are provided on the upper surfaces 631c and 641c of the inner upper parts 630 and 640, the accumulation of developer on the upper surfaces 631c and 641c can be suppressed. This further suppresses erroneous detection of the amount of developer by the toner level sensor 500.

[0160] Furthermore, since end faces 631e and 641e are provided at the tips of the inner upper parts 630 and 640, where the first blade portion 34b1 and the second blade portion 34b2 of the stirring member 34 made of sheet material make surface contact, damage such as tearing of the sheet material can be suppressed.

[0161] Furthermore, similar to the modified example described in the first embodiment, the inner upper part 630 of the light-emitting side light guide 610 may be a separate component from the inner light-guiding part 612, and the inner upper part 640 of the light-receiving side light guide 620 may be a separate component from the inner light-guiding part 622. This modified example makes it possible to suppress the occurrence of sink marks when molding the parts of the light guide member 600 excluding the inner upper parts 630 and 640, while maintaining the light-guiding performance of the light guide member 600. In addition, by making the inner upper parts 630 and 640 of a material that is less permeable to detection light OP than the inner light-guiding parts 612 and 622, it is possible to further suppress erroneous detection of the amount of developer due to stray light.

[0162] <Fourth Embodiment> A fourth embodiment of this disclosure will now be described. In this embodiment, the shape of a part of the frame portion 650 of the light guide member 600 differs from that of the first to third embodiments. The other configurations of the image forming apparatus 1 and process unit 20 are the same as those of the first to third embodiments. Hereinafter, elements denoted by reference numerals common to the first to third embodiments have substantially the same configuration and operation as those described in the first to third embodiments, and the parts that differ from the first to third embodiments will be described mainly.

[0163] In the configuration of the toner level sensor 500 described in the first to third embodiments, some of the detection light OP emitted from the light-emitting element 510a may enter the light guide member 600 from a side other than the incident surface 611a of the light guide member 600. Such light may reach the light-receiving element 510b as stray light that travels a different path from the designed optical path shown in Figures 15(a) to 16(d), etc. If the amount of stray light reaching the light-receiving element 510b is large, the light transmission time may be detected as longer than expected, which can lead to misdetection of the developer amount.

[0164] Figure 24 is a view of the light guide member 600 attached to the developing container 32, as seen from the outside of the developing container 32 (developing container lid 321). As shown in Figure 24, the frame portion 650 of the light guide member 600 includes a flat portion 651 and a retractable portion 655.

[0165] The flat portion 651 is a flat plate that extends in the longitudinal direction LD and the height direction ND. The flat portion 651 has a surface surface 651s and four sides (first side surface 651a, second side surface 651b, third side surface 651c, and fourth side surface 651d) that are connected at the corners by curved surfaces, as the surface exposed to the outside of the developing container 32. The first side surface 651a and the second side surface 651b are the ends of the flat portion 651 in the longitudinal direction LD, and the third side surface 651c and the fourth side surface 651d are the ends of the flat portion 651 in the height direction ND.

[0166] The retracted section 655 is provided on the inside of the four sides of the flat section 651 and has a concave shape that is recessed (retracted) toward the outside of the developing container 32 relative to the flat section 651. The retracted section 655 forms a space into which the wiping section 34c of the stirring member 34 can enter when wiping the light-emitting window 612a and the light-receiving window 622a with the wiping section 34c. The retracted section 655 has a front retracted surface 655s and front side surfaces 655a and 655b as surfaces exposed to the outside of the developing container 32. The front retracted surface 655s is a surface that is curved convexly toward the outside of the developing container 32 when viewed in the longitudinal direction LD. The front side surfaces 655a and 655b are surfaces that rise from the front surface 651s of the flat section 651 toward the outside of the developing container 32 and are connected to both ends of the front retracted surface 655s in the longitudinal direction LD.

[0167] The front surface 651s and the front retractable surface 655s are subjected to a roughening treatment (roughening treatment) with a ten-point average roughness of 20 μm or more. This roughening treatment allows the incident light OP emitted from the light-emitting element 510a to be diffused and scattered when it is incident on the front surface 651s and the front retractable surface 655s. Therefore, the amount of stray light from the detection light OP emitted from the light-emitting element 510a that enters the light guide member 600 from the front surface 651s and the front retractable surface 655s and reaches the light-receiving element 510b can be suppressed. This suppresses misdetection of the amount of developer due to stray light (reduction in detection accuracy). Note that a similar effect can be expected if the surface roughness (ten-point average roughness) of at least a portion of the surface of the light guide member 600 that is exposed to the outside of the developing container 32, excluding the first and fourth protrusions, is greater than the surface roughness of the first and fourth protrusions.

[0168] In this implementation, the sides (651a-651d, 655a, 655b) of the light guide member 600 parallel to the die-cutting direction (normal direction of the installation surface 680, protruding direction TD) are not treated with an uneven surface to improve moldability (release properties). Furthermore, the light-emitting side light guide 610 and the light-receiving side light guide 620 are mirror-finished to a maximum height of 0.2 μm or less in order to minimize light intensity loss of the detection light OP due to refraction and reflection. Thus, the light-emitting side light guide 610 and the light-receiving side light guide 620, which guide the detection light OP, have smooth surfaces in the parts exposed to the outside of the light guide member 600, while the other parts have rough surfaces while considering moldability. This suppresses light intensity attenuation of the detection light OP passing through the designed optical path, while also suppressing erroneous detection of developer amount due to stray light (reduction in detection accuracy).

[0169] Regarding the actual surface roughness, if the roughness of the other surfaces is set to be rougher than the surfaces of the light-emitting light guide 610 and the light-receiving light guide 620, a suppression effect of false detection due to stray light caused by the detection light OP can be obtained, although the degree may vary. The setting of the roughness (smoothness) of each surface of the light guide member 600 is appropriately changed according to the specific configuration, such as the light intensity of the LED as the light-emitting element 510a and the sensitivity of the phototransistor as the light-receiving element 510b.

[0170] The configuration of the surface of the light guide member 600 exposed to the outside of the developing container 32, as described in this embodiment, can be implemented in combination with the inner upper parts 630 and 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620, as described in the first to third embodiments. Therefore, by providing the inner upper parts 630 and 640, false detection of the amount of developer by the toner level sensor 500 (reduction in detection accuracy) can be suppressed, and false detection can be further reduced by the uneven surface treatment of the surface plane 651s and the surface retractable surface 655s.

[0171] <Fifth Embodiment> A fifth embodiment of this disclosure will now be described. This embodiment differs from the first to fourth embodiments in the shape of the outer light guide portions 611 and 621 of the light-emitting side light guide 610 and the light-receiving side light guide 620 of the light guide member 600, and in the optical path design of the toner level sensor 500. The other configurations of the image forming apparatus 1 and process unit 20 are the same as those of the first to fourth embodiments. Hereinafter, elements denoted by reference numerals common to the first to fourth embodiments have substantially the same configuration and operation as those described in the first to fourth embodiments, and the parts that differ from the first to fourth embodiments will be mainly described.

[0172] Figures 25(a, b) are perspective views showing the light guide member 600 as a single component before it is integrated with the developing container lid 321. Figure 25(a) shows the front side of the light guide member 600, i.e., the side that does not come into contact with the developer inside the developing container 32 and is exposed to the outside of the developing container 32. Figure 25(b) shows the back side of the light guide member 600, i.e., the side that comes into contact with the developer inside the developing container 32 and is exposed to the inside of the developing container 32.

[0173] Figures 26(a-f) show the light guide member 600 and the detection light OP from six directions using third-angle projection, with the back side of the light guide member 600 as the front. However, due to space limitations, the rear view (f) is placed below the bottom view (e). Figure 26(a) is a front view showing the back side of the light guide member 600. Figure 26(b) is a side view of the light guide member 600 as seen from the light-emitting element 510a side in the longitudinal LD. Figure 26(c) is a side view of the light guide member 600 as seen from the light-receiving element 510b side in the longitudinal LD. Figure 26(d) is a plan view of the light guide member 600 as seen from above the height direction ND. Figure 26(e) is a bottom view of the light guide member 600 as seen from below the height direction ND. Figure 26(f) is a rear view showing the back side of the light guide member 600.

[0174] Figure 27(a) is a cross-sectional view of the light guide member 600 cut along the cutting line AA shown in Figure 26(a, f) with a plane perpendicular to the longitudinal direction LD and passing through the light-emitting side light guide 610. Figure 27(b) is a cross-sectional view of the light guide member 600 cut along the cutting line BB shown in Figure 26(a, f) with a plane perpendicular to the longitudinal direction LD and passing through the light-receiving side light guide 620.

[0175] The detection light OP shown in Figures 25(a) to 27(b) represents a typical optical path (optical axis) of light emitted from the aforementioned light-emitting element 510a, passing through the light guide member 600, and reaching the light-receiving element 510b.

[0176] In the first to fourth embodiments, the incident surface 611a of the outer light guide portion 611 of the light-emitting side light guide 610 and the exit surface 621a of the outer light guide portion 621 of the light-receiving side light guide 620 were located at the tip of the outer light guide portions 611 and 621 in the protruding direction TD of the outer light guide portions 611 and 621. In contrast, the outer light guide portions 611 and 621 in this embodiment extend in a direction along the planar portion 651 of the frame portion 650.

[0177] As shown in Figures 25(a) and 26(a-f), the outer light guide portion 611 of the light-emitting side light guide 610 is formed in a prismatic shape extending in a first extension direction D1 (first direction) along the surface 653 (surface plane 651s) of the frame portion 650. The outer light guide portion 611 has a side portion 611d extending in the first extension direction D1, an incident surface 611a provided at one end of the side portion 611d in the first extension direction D1, and a reflective surface 611b provided at the other end of the side portion 611d in the first extension direction D1.

[0178] The incident surface 611a is the surface to which light from the light-emitting element 510a is incident. In this embodiment, the light-emitting element 510a is positioned to face this incident surface 611a (Figure 27(a)). The incident surface 611a is formed in the shape of a convex lens so that the diffused light irradiated from the light-emitting element 510a becomes a light beam substantially parallel to the first extending direction D1 of the outer light guide portion 611.

[0179] The first reflective surface 611b is the surface that reflects (specularly reflects) the detection light OP that is incident on the incident surface 611a and travels through the inside of the outer light guide portion 611 in the first extension direction D1 toward the inner light guide portion 612 (Figure 27(a)). As an example, in a cross section perpendicular to the longitudinal direction LD (Figure 27(a)), the angle that the reflective surface 611b makes with respect to the first extension direction D1 (the direction along the surface plane 651s of the frame portion 650) is 45°.

[0180] The side portion 611d, which serves as the first side portion, has three U-shaped surfaces in a cross section perpendicular to the first extension direction D1, and these three surfaces and the frame portion 650 form a substantially square cross section. Of the three surfaces of the side portion 611d, the two surfaces that face each other in the longitudinal direction LD may have a draft angle during molding. In this case, the cross section of the outer light guide portion 611 perpendicular to the first extension direction D1 is trapezoidal in shape, with the side opposite to the frame portion 650 being slightly shorter than the side that contacts the frame portion 650.

[0181] As shown in Figures 25(a) and 26(a-f), the outer light guide portion 621 of the light receiving side light guide 620 is formed in a prismatic shape extending in the second extension direction D2 (second direction) along the surface 653 (surface plane 651s) of the frame portion 650. The outer light guide portion 621 has a side portion 621d extending in the second extension direction D2, an emission surface 621a provided at one end of the side portion 621d in the second extension direction D2, and a reflective surface 621b provided at the other end of the side portion 621d in the second extension direction D2.

[0182] The emission surface 621a is the surface that emits the detection light OP, which has been incident on the inner light guide section 622 via the spatial optical path Q in the transport chamber 36, toward the photoreceiving element 510b. In this embodiment, the photoreceiving element 510b is positioned to face this emission surface 621a (Figure 27(b)).

[0183] The reflective surface 621b, as the second reflective surface, is the surface that reflects (specularly reflects) the detection light OP, which is incident on the inner light guide portion 622 and travels through the inside of the light receiving side light guide body 620 from the inner light guide portion 622 toward the outer light guide portion 621, toward the second extension direction D2 (Figure 27(b)). As an example, in a cross section perpendicular to the longitudinal direction LD (Figure 27(b)), the angle that the reflective surface 621b makes with respect to the second extension direction D2 (the direction along the surface plane 651s of the frame portion 650) is 45°.

[0184] The side portion 621d, which serves as the second side portion, has three U-shaped surfaces in a cross section perpendicular to the second extension direction D2, and these three surfaces and the frame portion 650 form a roughly square cross section. Of the three surfaces of the side portion 621d, the two surfaces that face each other in the longitudinal direction LD may have a draft angle during molding. In this case, the cross section of the outer light guide portion 611 perpendicular to the second extension direction D2 is a trapezoid shape in which the side opposite to the frame portion 650 is slightly shorter than the side that is in contact with the frame portion 650.

[0185] (Positional relationship between the reflective surface of the outer light guide and the upper inner part) In the first to fourth embodiments, the outer light guides 611 and 612 were provided with an incident surface 611a into which light from the light-emitting element 510a enters, and an exit surface 621a that emits light toward the light-receiving element 510b at the tip of the protruding direction TD. Furthermore, it was explained that by positioning the upper surfaces 630c and 640c of the inner upper parts 630 and 640 above the extensions of the upper surfaces 611c and 621c of the outer light guides 611 and 612 (EL1 and EL2 in Figure 16(b and c)), it is possible to reduce the false detection of the amount of developer.

[0186] In contrast, the outer light guide portion 611 of the light-emitting side light guide 610 in this embodiment is configured such that light incident on the incident surface 611a travels through the inside of the outer light guide portion 611 in a first extension direction D1, is reflected by the reflective surface 611b, and is guided toward the inner light guide portion 612. Similarly, the outer light guide portion 621 of the light-receiving side light guide 620 in this embodiment is configured such that light traveling from the inner light guide portion 622 to the outer light guide portion 621 is reflected by the reflective surface 621b and is guided toward the output surface 621a in a second extension direction D2.

[0187] In this configuration, the region through which the light beam reflected by the reflective surface 611b of the first protrusion (outer light guide portion 611) of the second protrusion of the light guide member 600 passes can be said to substantially constitute the optical path of the detection light OP. Similarly, the region through which the light beam reflected by the reflective surface 621b when it moves from the third protrusion to the fourth protrusion (outer light guide portion 611) of the third protrusion of the light guide member 600 passes can be said to substantially constitute the optical path of the detection light OP.

[0188] Therefore, in this embodiment, the upper surface of the second projection of the light-emitting side light guide 610 is positioned above a straight line (IL3) that passes through the upper end 611bt of the reflective surface 611b of the outer light guide 611 and extends in the direction of light reflection D3 at the reflective surface 611b. Also, in this embodiment, the upper surface of the third projection of the light-receiving side light guide 620 is positioned above a straight line (IL4) that passes through the upper end 621bt of the reflective surface 621b of the outer light guide 621 and extends in the direction of light incidence D4 with respect to the reflective surface 621b.

[0189] Specifically, the virtual line IL3 shown in Figure 27(a) is a straight line passing through the upper end 611bt of the reflective surface 611b in the gravity direction WD, and is a straight line drawn in the reflection direction D3 when light in the first extension direction D1 is specularly reflected by the reflective surface 611b. Of the second protrusion of the light guide member 600, the portion below the virtual line IL3 is the inner light guide portion 612, which forms the optical path of the detection light OP. Of the second protrusion of the light guide member 600, the portion above the virtual line IL3 is the inner upper portion 630, which does not contribute to the formation of the optical path of the detection light OP. The upper surface 630c of the inner upper portion 630 is located above the virtual line IL3 (the first virtual line) when viewed in the longitudinal direction LD. In other words, when viewed in a direction that intersects both the first extending direction D1 (first direction) and the gravity direction WD, along which the outer light guide portion 611 (first protrusion) extends along the wall surface of the developing container 32, the upper surface 630c (first upper surface) of the inner upper portion 630 is located above the virtual straight line IL3 (first virtual straight line). Here, the direction that intersects both the first direction and the gravity direction WD is preferably a direction perpendicular to the gravity direction WD and along the wall surface of the developing container 32 where the light guide member 600 is provided. Furthermore, the direction that intersects both the first direction and the gravity direction WD is preferably the direction in which the inner light guide portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, it is the longitudinal direction LD of the developing container 32.

[0190] Furthermore, the virtual line IL4 shown in Figure 27(b) is a straight line passing through the upper end 621bt of the reflective surface 621b in the gravity direction WD, and is a straight line drawn in the incident direction D4 of the incident light when the incident light incident on the reflective surface 621b is specularly reflected in the second extension direction D2. Of the third protrusion of the light guide member 600, the portion below the virtual line IL4 is the inner light guide portion 622, which forms the optical path of the detection light OP. Of the third protrusion of the light guide member 600, the portion above the virtual line IL4 is the inner upper portion 640, which does not contribute to the formation of the optical path of the detection light OP. The upper surface 640c of the inner upper portion 640 is located above the virtual line IL4 (the second virtual line) when viewed in the longitudinal direction LD. In other words, when viewed in a direction that intersects both the second extending direction D2 (second direction) and the gravity direction WD, along which the outer light guide portion 621 (fourth protrusion) extends along the wall surface of the developing container 32, the upper surface 640c (second upper surface) of the inner upper portion 640 is located above the virtual straight line IL4 (second virtual straight line). Here, the direction that intersects both the second direction and the gravity direction WD is preferably a direction perpendicular to the gravity direction WD and along the wall surface of the developing container 32 where the light guide member 600 is provided. Furthermore, the direction that intersects both the second direction and the gravity direction WD is preferably the direction in which the inner light guide portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, it is the longitudinal direction LD of the developing container 32.

[0191] Thus, although the optical path design of the outer light guides 611 and 621 differs from that of the first to fourth embodiments, the inner upper parts 630 and 640 are provided above the inner light guides 612 and 622, and their upper surfaces 630c and 640c are positioned above the virtual straight lines IL3 and IL4.

[0192] In other words, the upper surface 630c of the second projection of the light guide member 600 is located above a hypothetical straight line IL3 (first hypothetical straight line) drawn in the reflection direction D3 when light in the first extension direction D1 (first direction) is incident on the first reflection surface, as viewed in the longitudinal direction LD of the developing container 32. Furthermore, the upper surface 640c of the third projection of the light guide member 600 is located above a hypothetical straight line IL4 (second hypothetical straight line) drawn in the incident direction D4 when light incident on the second reflection surface is reflected in the second extension direction D2 (second direction), as viewed in the longitudinal direction LD of the developing container 32.

[0193] With this configuration, even if developer accumulates on the upper surfaces 630c and 640c of the inner upper parts 630 and 640 when the developer amount is detected, it is difficult for aggregated developer to reach the light-emitting window 612a or light-receiving window 622a of the inner light-guiding section 612 and 622. In other words, even with the configuration of this embodiment, it is possible to reduce the adhesion of developer to the light-emitting window 612a or light-receiving window 622a and suppress false detection of the developer amount by the toner remaining amount sensor 500 (reduction in detection accuracy).

[0194] In this embodiment, the extension directions of the outer light guides 611 and 621 are described as being substantially parallel to the height direction ND, but the outer light guides 611 and 621 may be configured to extend in other directions. The extension directions of the outer light guides 611 and 621 can be appropriately changed in relation to the arrangement of the light-emitting element 510a and the light-receiving element 510b in the image forming apparatus. For example, the outer light guide 611 of the light-emitting side light guide 610 may extend to one side of the longitudinal direction LD, and the outer light guide 621 of the light-receiving side light guide 620 may extend to the other side of the longitudinal direction LD. In this case, the reflective surface 611b of the outer light guide 611 of the light-emitting side light guide 610 is arranged to reflect light coming from the incident surface 611a through the interior of the outer light guide 611 in the longitudinal direction LD, which is the first direction, toward the inner light guide 612. Furthermore, the reflective surface 621b of the outer light guide portion 621 of the light-receiving light guide 620 is arranged to reflect the light that has traveled from the inner light guide portion 622 to the outer light guide portion 611 toward the emission surface 621a along the longitudinal direction LD, which is the second direction.

[0195] Even if the extension direction (first direction) of the outer light guide portion 611 (first protrusion) of the light-emitting side light guide 610 differs from that of this embodiment, the upper surface of the second protrusion may be positioned above the first virtual straight line when viewed in the longitudinal direction LD. This first virtual straight line is a straight line passing through the upper end of the reflective surface (first reflective surface) of the outer light guide portion 611, and is a virtual straight line drawn in the direction of reflection when light in the first direction is incident on the first reflective surface and reflected. Similarly, even if the extension direction (second direction) of the outer light guide portion 621 (fourth protrusion) of the light-receiving side light guide 620 differs from that of this embodiment, the upper surface of the third protrusion may be positioned above the second virtual straight line when viewed in the longitudinal direction LD. This second virtual straight line is a straight line passing through the upper end of the reflective surface (second reflective surface) of the outer light guide portion 621, and is a virtual straight line drawn in the direction of incidence when light incident on the second reflective surface is reflected in the second direction. This makes it possible to suppress false detection of the developer amount (a decrease in detection accuracy), similar to the present embodiment.

[0196] Furthermore, similar to the modified example described in the first embodiment, the inner upper part 630 of the light-emitting side light guide 610 may be a separate component from the inner light-guiding part 612, and the inner upper part 640 of the light-receiving side light guide 620 may be a separate component from the inner light-guiding part 622. This modified example makes it possible to suppress the occurrence of sink marks when molding the parts of the light guide member 600 excluding the inner upper parts 630 and 640, while maintaining the light-guiding performance of the light guide member 600. In addition, by making the inner upper parts 630 and 640 of a material that is less permeable to detection light OP than the inner light-guiding parts 612 and 622, it is possible to further suppress erroneous detection of the amount of developer due to stray light.

[0197] Furthermore, the inner upper parts 630 and 640 in this embodiment may be replaced with the configurations of the inner upper parts 630 and 640 described in the second and third embodiments, and the uneven surface treatment described in the fourth embodiment may be applied to the frame part 650 of this embodiment.

[0198] <Other embodiments> In the embodiments described above, the light-emitting element 510a and the light-receiving element 510b are arranged in the process unit 20, but the light-emitting element 510a and the light-receiving element 510b may be arranged, for example, in the printer body 100 of the image forming apparatus 1. Also, in the embodiments described above, a substrate holding member 710 is provided between the developing container lid 321 and the substrate 700, but the substrate holding configuration is not limited to this. That is, the substrate 700 may be directly attached to the developing container lid 321 without providing the substrate holding member 710.

[0199] Furthermore, in the embodiments described above, the light-emitting side light guide 610 and the light-receiving side light guide 620 are configured as a single molded component via a frame portion 650, but the invention is not limited to this. For example, the light-emitting side light guide 610 and the light-receiving side light guide 620 may be configured as separate components and each attached to the developing container 32.

[0200] Furthermore, in the embodiments described above, the spatial optical path Q was arranged to overlap with the rotational trajectories Tb1 and Tb2 of the stirring member 34 when viewed in the axial direction of the stirring member 34, but this is not limited to this. That is, the spatial optical path Q may be arranged so as not to overlap with the rotational trajectories Tb1 and Tb2 of the stirring member 34.

[0201] In the embodiments described above, the reading device 200 was provided above the printer body, but this is not the only option. That is, the image forming apparatus may be a printer without a reading device. Also, the reading device may be a reading device equipped with an ADF (Auto Document Feeder) for feeding documents. [Explanation of Symbols]

[0202] 32...Container (developing container) / 500...Detection means (toner level sensor) / 510a...Light-emitting element / 510b...Light-receiving element / 600...Light-guiding means (light-guiding member) / 611...First protrusion (outer light-guiding part of the light-emitting side light-guiding body) / 611a...First incident surface (incident surface) / 611b...First reflective surface / 611c...Upper surface of the first protrusion / 611d...First side surface / 612...Second protrusion, first lower part (inner light-guiding part) / 612a...Second emission surface (light-emitting window) / 621...Fourth protrusion (outer light-guiding part) / 621a...First emission surface (Emitting surface) / 621b...Second reflecting surface / 621c...Upper surface of the fourth protrusion / 621d...Second side surface / 622...Third protrusion, second lower part (inner light guide) / 622a...Second incident surface (light receiving window) / 630...Second protrusion, first upper part (inner upper part) / 630c...Upper surface of the second protrusion / 640...Third protrusion, second upper part (inner upper part) / 640c...Upper surface of the third protrusion / EL1,IL3...First virtual straight line (first extension line, virtual straight line) / EL2,IL4...Second virtual straight line (second extension line, virtual straight line)

Claims

1. A container for containing a developer; a light emitting element and a light receiving element arranged on the outside of the container, and a light guiding means provided on a wall surface of the container to guide the light emitted by the light emitting element to reach the light receiving element through the internal space of the container, and a detection means in which an output signal of the light receiving element changes depending on the amount of the developer in the container; an image forming apparatus for forming an image on a recording material by using the developer, The light guiding means is a first protrusion protruding from the wall surface to the outside of the container in a first direction intersecting with the direction of gravity, the first protrusion having an incident surface on which light emitted by the light emitting element is incident, the first protrusion being provided at a tip end in the first direction; a second protrusion protruding inwardly of the container from the wall surface in the first direction, the second protrusion emitting light incident on the first protrusion into the internal space of the container; a third protrusion protruding inwardly from the wall surface in a second direction intersecting with the gravity direction, the third protrusion receiving light emitted from the second protrusion into the internal space of the container; a fourth protrusion protruding from the wall surface in the second direction to the outside of the container, the fourth protrusion having an exit surface at a tip end in the second direction that emits the light incident on the third protrusion toward the light receiving element; having an upper surface of the second protrusion is located above a first imaginary straight line extending along an upper surface of the first protrusion when viewed in a direction intersecting both the first direction and the gravity direction; an upper surface of the third protrusion is located above a second imaginary straight line extending along an upper surface of the fourth protrusion when viewed in a direction intersecting both the second direction and the direction of gravity; The first protrusion and the second protrusion are configured such that a direction in which light travels from the outside to the inside of the container through the first protrusion and the second protrusion intersects with the direction of gravity, The third protrusion and the fourth protrusion are configured so that a direction in which light travels from the inside to the outside of the container through the third protrusion and the fourth protrusion intersects with the direction of gravity.

1. An image forming apparatus comprising:

2. the second protrusion portion has a first lower portion located below the first virtual straight line as viewed in the direction intersecting both the first direction and the direction of gravity, and a first upper portion located above the first lower portion, the upper surface of the second protrusion is a part of the first upper portion, the third protrusion portion has a second lower portion located below the second virtual straight line as viewed in the direction intersecting both the second direction and the direction of gravity, and a second upper portion located above the second lower portion, The upper surface of the third protrusion is a part of the second upper portion.

2. The image forming apparatus according to claim 1,

3. the first upper portion is integrally molded with the first lower portion using the same material as the first lower portion; The second upper portion is integrally molded with the second lower portion using the same material as the second lower portion.

3. The image forming apparatus according to claim 2,

4. the first upper portion is a separate member from the first lower portion, and a lower surface of the first upper portion and an upper surface of the first lower portion are joined together; The second upper part is a separate member from the second lower part, and a lower surface of the second upper part and an upper surface of the second lower part are joined together.

3. The image forming apparatus according to claim 2,

5. a first space is provided between a lower surface of the first upper portion and an upper surface of the first lower portion; A second space is provided between a lower surface of the second upper portion and an upper surface of the second lower portion.

3. The image forming apparatus according to claim 2,

6. the first upper portion is formed of a material having a lower transmittance of light emitted by the light emitting element than the first lower portion; The second upper portion is formed of a material having a lower transmittance for light emitted by the light emitting element than the second lower portion.

6. The image forming apparatus according to claim 4, wherein the image forming apparatus is a multi-color image forming apparatus.

7. a stirring member disposed inside the container, rotating about an axis extending in a longitudinal direction of the container, and stirring the developer in the container; The stirring member has a shaft extending in the longitudinal direction and a blade portion formed of a flexible sheet material and protruding from the shaft, A first end surface extending in the longitudinal direction is provided at an end portion of the first upper portion opposite to the wall surface of the container, A second end surface extending in the longitudinal direction is provided at an end portion of the second upper portion opposite to the wall surface of the container.

7. The image forming apparatus according to claim 2, wherein the image forming apparatus is a multi-color image forming apparatus.

8. At least a portion of the upper surface of the second protrusion is inclined downward toward an inside of the container when viewed in the direction intersecting both the first direction and the direction of gravity, At least a part of the upper surface of the third protrusion is inclined downward toward the inside of the container when viewed in the direction intersecting both the second direction and the gravity direction.

8. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

9. an inclination angle of at least a portion of the upper surface of the second protruding portion with respect to a horizontal plane, and an inclination angle of at least a portion of the upper surface of the third protruding portion with respect to a horizontal plane are greater than an angle of repose of the developer; 9. The image forming apparatus according to claim 8,

10. The incident surface of the first protrusion is a first incident surface, and the exit surface of the fourth protrusion is a first exit surface, the second protrusion has a second exit surface that emits the light incident on the first protrusion into the internal space of the container, the third protrusion has a second incident surface into which the light emitted from the second protrusion into the internal space of the container is incident, The second exit surface and the second entrance surface face each other in the longitudinal direction of the container.

10. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

11. a wiping portion that is arranged inside the container, rotates about an axis extending in the longitudinal direction, and comes into contact with the second exit surface of the second protruding portion and the second entrance surface of the third protruding portion to wipe off the developer adhering to the second exit surface and the second entrance surface.

11. The image forming apparatus according to claim 10.

12. the second protrusion has a first offset surface extending above the second emission surface in a direction along the second emission surface, the third protrusion has a second offset surface extending above the second incidence surface in a direction along the second incidence surface, the first offset surface is offset toward a side closer to the wall surface with respect to the second emission surface when viewed in a height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, The second offset surface is offset toward the wall surface with respect to the second incident surface when viewed in the height direction.

12. The image forming apparatus according to claim 11.

13. the second exit surface is curved convexly toward the second entrance surface in the longitudinal direction when viewed in a height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, The second entrance surface is curved convexly toward the second exit surface in the longitudinal direction when viewed in the height direction.

13. The image forming apparatus according to claim 11 or 12.

14. the second protrusion has a reflective surface provided on an opposite side to the second exit surface in the longitudinal direction, the reflective surface reflecting light traveling from the first protrusion to the second protrusion toward the second exit surface, the third protrusion has a reflecting surface provided on the opposite side to the second incident surface in the longitudinal direction, the reflecting surface reflecting the light incident on the second incident surface toward the first exit surface of the fourth protrusion, 14. The image forming apparatus according to claim 11,

15. An opening is provided in the wall of the container, the light guide means has a frame portion attached to the opening, the first protruding portion, the second protruding portion, the third protruding portion, the fourth protruding portion, and the frame portion are integrally molded.

15. The image forming apparatus according to claim 1,

16. a surface roughness of at least a part of a surface of the light guiding means exposed to the outside of the container, excluding the first protrusion and the fourth protrusion, is greater than a surface roughness of the first protrusion and the fourth protrusion; 16. The image forming apparatus according to claim 1,

17. The second protrusion and the third protrusion face each other in a longitudinal direction of the container, The direction intersecting both the first direction and the direction of gravity, and the direction intersecting both the second direction and the direction of gravity are the longitudinal direction.

17. The image forming apparatus according to claim 1,

Images