Image forming apparatus

Abstract

To suppress deterioration of detection accuracy of a developer amount.SOLUTION: The light guide means has a first projection part and a fourth projection part projecting to the outside of the container with respect to the wall surface of the container, and a second projection part and a third projection part projecting to the inside of the container with respect to the wall surface. The upper surface of the second protruding portion is located above a first virtual straight line along the upper surface of the first protruding portion when viewed in a direction intersecting both the first direction in which the first protruding portion protrudes and the gravity direction, and the upper surface of the third protruding portion is located above a second virtual straight line along the upper surface of the fourth protruding portion when viewed in a direction intersecting both the second direction in which the fourth protruding portion protrudes and the gravity direction.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 technology]

[0002] Electrophotographic image forming apparatuses are equipped with 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. A known method for detecting the remaining amount of developer (toner remaining amount) in a developing device is a light transmission remaining amount detection method that uses light. Patent Document 1 describes a remaining amount detection configuration that includes a light-emitting side light guide and a light-receiving side light guide that penetrate from the outside to the inside of a container of the developing device. In this configuration, light emitted by a light-emitting element enters the light-emitting side light guide outside the container, passes from the light-emitting side light guide through the internal space of the container, enters the light-receiving side light guide, and is emitted from the light-receiving side light guide outside the container and received by a light-receiving element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-066899 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration described in the above document, the light-emitting light-guiding section and the light-receiving light-guiding section protrude into the container of the developing device, and therefore, developer accumulation on the protruding sections of the light-emitting light-guiding section and the light-receiving light-guiding section can cause developer clumps to grow, which can then adhere to the surfaces of the light-emitting light-guiding section and the light-receiving light-guiding section that form the optical path, blocking the optical path and potentially reducing the accuracy of developer amount detection.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus capable of suppressing a decrease in the accuracy of detecting the amount of developer. [Means for solving the problem]

[0006] One aspect of the present invention is an image forming apparatus that forms an image on a recording material using the developer, the image forming apparatus comprising: a container that stores developer; a light-emitting element and a light-receiving element arranged outside the container; a light-guiding unit that is provided on a wall surface of the container and guides light emitted by the light-emitting element to reach the light-receiving element through the internal space of the container, and a detection unit that changes an output signal of the light-receiving element depending on the amount of the developer in the container, the light-guiding unit comprising: a first protrusion that protrudes outward from the wall surface 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 at a tip end in the first direction; a second protrusion that protrudes inward from the wall surface of the container in the first direction, the second protrusion outputting the light that has entered the first protrusion into the internal space of the container; and a third protrusion that protrudes inward from the wall surface of the container in a second direction intersecting with the direction of gravity, the third protrusion a third protrusion protruding from the wall surface in the second direction toward the outside of the container, and a fourth protrusion having an emission surface at its tip in the second direction, which emits light incident on the third protrusion toward the light receiving element, the fourth protrusion having an emission surface at its tip in the second direction, the fourth protrusion having an emission surface at its tip in the second direction, which emits light incident on the third protrusion toward the light receiving element, the upper surface of the second protrusion being located above a first imaginary line extending along the upper surface of the first protrusion when viewed in a direction intersecting both the first direction and the direction of gravity, and the upper surface of the third protrusion being located above a first imaginary line extending along the upper surface of the first protrusion when viewed in a direction intersecting both the second direction and the direction of gravity When viewed from above, the fourth protrusion is positioned above a second virtual straight line extending along the top surface of the fourth protrusion, the first protrusion and the second protrusion are configured so that the direction in which light travels from the outside to the inside of the container through the first protrusion and the second protrusion intersects the direction of gravity, and the third protrusion and the fourth protrusion are configured so that the direction in which light travels from the inside to the outside of the container through the third protrusion and the fourth protrusion intersects the direction of gravity. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress a decrease in the accuracy of detecting the amount of developer. [Brief explanation of the drawings]

[0008] [Figure 1] 1A is a cross-sectional view and FIG. 1B is a perspective view of an image forming apparatus according to a first embodiment. [Figure 2] 1A is a cross-sectional view and FIG. 1B is a perspective view of an image forming apparatus according to a first embodiment. [Figure 3] 1A and 1B are perspective views of an image forming apparatus according to a first embodiment. [Figure 4] 1A is a perspective view and FIG. 1B is a front view of a developing container and a toner pack according to the first embodiment, and FIG. 1C is a perspective view of an agitating member according to the first embodiment. [Figure 5] 5A-5A cross-sectional view (a) and 5B-5B cross-sectional view (b) of FIG. 4B. [Figure 6] FIG. 2 is a perspective view showing a toner pack according to the first embodiment. [Figure 7] 1A and 1B are diagrams showing a toner pack according to the first embodiment and its modified examples (b and c). [Figure 8] FIG. 2 is a perspective view of a developing device according to the first embodiment. [Figure 9] 1A is a perspective view showing a developing container and a substrate according to the first embodiment, and FIG. 1B is a perspective view showing a substrate and a substrate holding member according to the first embodiment. [Figure 10] 1A is a cross-sectional view perpendicular to the longitudinal direction of a developing device according to a first embodiment, and FIG. 1B is a cross-sectional view along the longitudinal direction. [Figure 11] FIG. 2 is a circuit diagram showing the basic configuration of a remaining toner sensor according to the first embodiment. [Figure 12] 2A and 2B are cross-sectional views of a developing container according to the first embodiment. [Figure 13] FIG. 2 is a block diagram showing a control system of the image forming apparatus according to the first embodiment. [Figure 14] 3A to 3D are perspective views of a remaining toner panel according to the first embodiment. [Figure 15] 1A and 1B are perspective views of a light-guiding member according to a first embodiment. [Figure 16]1A is a front view, (b, c) side views, (d) a plan view, (e) a bottom view, and (f) an enlarged view of a light guide member according to a first embodiment. [Figure 17] 3A and 3B are perspective views of a developing container lid and a light guide member according to the first embodiment. [Figure 18] FIG. 2 is a perspective view of a light guide member according to the first embodiment. [Figure 19] FIG. 10 is a perspective view of a light guide member according to a modified example. [Figure 20] FIG. 10 is a perspective view of a light guide member according to a second embodiment. [Figure 21] FIG. 10 is a perspective view of a light guide member according to a third embodiment. [Figure 22] 10A is a plan view of a light guide member according to a third embodiment, and FIG. 10B is an enlarged view of a part of the light guide member according to the third embodiment. [Figure 23] 10A and 10C are a front view and side views of a light guide member according to a third embodiment. [Figure 24] FIG. 10 is a view of a light guide member according to a fourth embodiment, as viewed from the outside of a developing container. [Figure 25] 10A and 10B are perspective views of a light-guiding member according to a fifth embodiment. [Figure 26] 10A is a front view, (b, c) side views, (d) a plan view, (e) a bottom view, and (f) a rear view of a light guide member according to a fifth embodiment. [Figure 27] 10A and 10B are cross-sectional views of a light-guiding member according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0010] First Embodiment 1(a) is a schematic diagram showing the configuration of an image forming apparatus 1 according to a first embodiment. The image forming apparatus 1 is a monochrome printer that forms an image on a recording material based on image information input from an external device. The recording material includes a variety of sheet materials made of different materials, such as paper such as plain paper and cardboard, plastic film such as sheets for overhead projectors, sheets of special shapes such as envelopes and index paper, and cloth.

[0011] [Overall configuration] 1(a) and 1(b), the image forming apparatus 1 has a printer main body 100 as the device main body, a reading device 200 supported by the printer main body 100 so as to be openable and closable, and an operation unit 300 attached to the exterior surface of the printer main body 100. The printer main body 100 has an image forming unit 10 that forms a toner image on a recording material, a feeding unit 60 that feeds the recording material to the image forming unit 10, a fixing unit 70 that fixes the toner image formed by the image forming unit 10 to the recording material, and a pair of discharge rollers 80.

[0012] The image forming section 10 includes a scanner unit 11, an electrophotographic process unit 20, and a transfer roller 12 that transfers a toner image (developer image) formed on a photosensitive drum 21 of the process unit 20 to a recording material. As shown in FIGS. 5(a) and 5(b), the process unit 20 includes the photosensitive drum 21 and a developing device 30 including 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 main body 100. Note that the process unit 20 may be fastened to the printer main body 100 with screws, and may be removed primarily by a service technician rather than a user. However, the process unit 20 does not include structural components of the printer main body 100, such as the housing frame of the printer main body 100.

[0013] The photosensitive drum 21 is a cylindrically shaped photosensitive member. The photosensitive drum 21 of this embodiment has a photosensitive layer formed of a negatively chargeable organic photosensitive member on a drum-shaped substrate made of aluminum. The photosensitive drum 21, which serves as an image carrier, is rotated by a motor in a predetermined direction (clockwise in the drawing) at a predetermined process speed.

[0014] The charging roller 22 contacts the photosensitive drum 21 with a predetermined pressure to form a charging portion. A desired charging voltage is applied by a charging high-voltage power supply, thereby uniformly charging the surface of the photosensitive drum 21 to a predetermined potential. In this embodiment, the photosensitive drum 21 is negatively charged by the charging roller 22. The pre-exposure device 23 neutralizes the surface potential of the photosensitive drum 21 before it enters the charging portion in order to generate a stable discharge in the charging portion.

[0015] The scanner unit 11, which serves as an exposure means, scans and exposes the surface of the photosensitive drum 21 by irradiating the photosensitive drum 21 with laser light corresponding to image information input from an external device or the reading device 200 using a polygon mirror. This exposure forms an electrostatic latent image corresponding to the image information on the surface of the photosensitive drum 21. Note that the scanner unit 11 is not limited to a laser scanner device, and may, for example, be an LED exposure device having an LED array in which a plurality of LEDs are arranged along the longitudinal direction of the photosensitive drum 21.

[0016] The developing device 30 includes a developing roller 31 as a developer carrier that carries developer, a developing container 32 as a frame of the developing device 30, and a supply roller 33 that can supply 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 disposed at the opening of the developing container 32 so as to face the photosensitive drum 21. The supply roller 33 rotatably contacts the developing roller 31, and the toner contained in the developing container 32 as the developer 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 as long as the configuration can supply a sufficient amount of toner to the developing roller 31.

[0017] The developing device 30 of this embodiment uses a contact development method. That is, a toner layer carried on the developing roller 31 comes into contact with the photosensitive drum 21 in a development section (development area) where the photosensitive drum 21 and the developing roller 31 face each other. A development voltage is applied to the developing roller 31 by a high-voltage development power supply. Under the development voltage, the toner carried on the developing roller 31 is transferred from the developing roller 31 to the drum surface in accordance with the potential distribution on the surface of the photosensitive drum 21, thereby developing the electrostatic latent image into a toner image. Note that this embodiment employs a reversal development method. That is, a toner image is formed by the toner adhering to the surface area of ​​the photosensitive drum 21, which has been charged in a charging process and then exposed in an exposure process, where the charge amount has attenuated.

[0018] In this embodiment, a toner having a particle size of 6 μm and a normal negative charge polarity is used. As an example, the toner used in this embodiment is a polymerized toner produced by a polymerization method. The toner used in this embodiment does not contain a magnetic component, and is a so-called non-magnetic single-component developer in which the toner is carried on the developing roller 31 mainly by intermolecular forces and electrostatic forces (image forces). However, a single-component developer containing a magnetic component may also be used. In addition to toner particles, a single-component developer may also contain additives (e.g., wax or silica particles) to adjust the fluidity and charging performance of the toner. A two-component developer composed of a non-magnetic toner and a magnetic carrier may also be used. When a magnetic developer is used, a cylindrical developing sleeve with a magnet disposed inside is used as the developer carrier.

[0019] An agitating member 34 is provided inside the developing container 32. The agitating member 34 is driven to rotate by a motor M1 (see FIG. 13), thereby agitating the toner in the developing container 32 and transporting the toner toward the developing roller 31 and the supply roller 33. The agitating member 34 also circulates toner that has not been used for development and has been scraped off from the developing roller 31 within the developing container, thereby homogenizing the toner in the developing container. The agitating member 34 is not limited to a rotating type. For example, an agitating member that oscillates may be used. Furthermore, in addition to the agitating member 34, another agitating member may be provided.

[0020] A developing blade 35 is disposed at the opening of the developing container 32 in which the developing roller 31 is disposed, to regulate the amount of toner carried by the developing roller 31. The toner supplied to the surface of the developing roller 31 passes through the area facing the developing blade 35 as the developing roller 31 rotates, whereby the toner is uniformly formed into a thin layer and is negatively charged by frictional charging.

[0021] 1(a) and 1(b), the feeding section 60 has a front door 61 supported by the printer main body 100 so as to be able to open and close, 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 a recording material storage space that appears 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 urges the middle plate 63 upward, pressing the recording material P loaded on the middle plate 63 against the pickup roller 65. Note that the front door 61 closes the recording material storage space when closed relative to the printer main body 100, and supports the recording material P together with the tray section 62 and middle plate 63 when open relative to the printer main body 100.

[0022] The fixing unit 70 is a thermal fixing unit that fixes an image by heating and melting the toner on the recording material. The fixing unit 70 includes a fixing film 71, a fixing heater such as a ceramic heater that heats the fixing film 71, a thermistor that measures the temperature of the fixing heater, and a pressure roller 72 that presses against the fixing film 71.

[0023] Next, an image forming operation of the image forming apparatus 1 will be described. When an image formation command is input to the image forming apparatus 1, the image forming process is started by the image forming unit 10 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 a laser beam toward the photosensitive drum 21 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 by the irradiation of the laser beam. Thereafter, the electrostatic latent image is developed by the developing roller 31, and a toner image is formed on the photosensitive drum 21.

[0024] In parallel with the image forming process described above, the pickup roller 65 of the feeding section 60 feeds out the recording material P supported by the front door 61, the tray section 62, and the middle plate 63. The recording material P is fed by the pickup roller 65 to the pair of registration rollers 15, and any skew is corrected by the recording material P hitting the nip of the pair of registration rollers 15. The pair of registration rollers 15 is then driven in synchronization with the transfer timing of the toner image, and conveys the recording material P toward the transfer nip formed by the transfer roller 12 and the photosensitive drum 21.

[0025] A transfer voltage is applied to the transfer roller 12 as a transfer means from a transfer high-voltage power supply, and the toner image carried on the photosensitive drum 21 is transferred onto the recording material P being conveyed by a pair of registration rollers 15. The recording material P with the transferred toner image is conveyed to a fixing section 70, and the toner image is heated and pressurized as it passes through a nip between a fixing film 71 and a pressure roller 72 of the fixing section 70. This melts the toner particles and then solidifies them, thereby fixing the toner image to the recording material P. After passing through the fixing section 70, the recording material P is discharged to the outside of the image forming apparatus 1 (outside the machine) by a pair of discharge rollers 80, and is stacked on a discharge tray 81 formed at the top of the printer main body 100.

[0026] The discharge tray 81 is inclined upward toward the downstream side in the discharge direction of the recording material, and the recording material discharged onto the discharge tray 81 slides down the discharge tray 81 so that its rear end is aligned by a regulating surface 84 .

[0027] The transfer means is not limited to a direct transfer type in which a toner image is directly transferred from an image carrier to a recording material, but may also be an intermediate transfer type in which a toner image is transferred from an image carrier to a recording material via an intermediate transfer body. In this case, instead of the transfer roller 12, an intermediate transfer unit including, for example, an endless intermediate transfer belt stretched over multiple rollers, a primary transfer roller facing the photosensitive drum across the intermediate transfer belt, and a secondary transfer roller facing the outer surface of the intermediate transfer belt is used. The toner image formed on the photosensitive drum is primarily 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 means.

[0028] Furthermore, although the present embodiment describes a monochrome printer, the technology described below may also be applied to an image forming apparatus that has multiple sets of image carriers and developing devices and forms color images using toners of multiple colors.

[0029] 3(a) and 3(b), the reading device 200 has a reading unit 201 that incorporates a reading section (not shown) therein, and a pressure plate 202 that is openably and closably supported by the reading unit 201. On the top surface of the reading unit 201, there is provided a document table glass 203 that transmits light emitted from the reading section and on which a document is placed.

[0030] When a user wants to have the image of a document read by the reading device 200, the user places the document on the document glass 203 with the pressure plate 202 open. Then, by closing the pressure plate 202, the document on the document glass 203 is prevented from shifting position, and a reading command is output to the image forming device 1 by operating, for example, the operation unit 300. When the reading operation is started, the reading unit in the reading unit 201 moves back and forth in the sub-scanning direction, that is, in the left-right direction with the operation unit 300 of the image forming device 1 facing forward. The reading unit emits light toward the document from the light-emitting unit, receives light reflected by the document with the light-receiving unit, and reads the image of the document by photoelectrically converting the light. Note that, hereinafter, the front-rear direction, left-right direction, and up-down direction are defined based on the state in which the operation unit 300 is facing forward.

[0031] As shown in FIGS. 2(a) and 2(b), a first opening 101 that opens upward is formed in the upper part of the printer main body 100, and is covered by a discharge tray 81 in a normal operating state (a state in which an image forming operation can be performed). The discharge tray 81 is supported on the printer main body 100 so as to be openable and closable around a pivot shaft extending in the left-right direction. The discharge tray 81 opens from the front side toward the back side when the reading device 200 is opened relative to the printer main body 100. The first opening 101 is configured to expose a mounting section 57 having a replenishing port 32a into which a toner pack 40, which will be described later, can be attached (see FIGS. 4(a) and 4(b)). A user accesses the mounting section 57 by opening the discharge tray 81. The reading device 200 and the discharge tray 81 may be configured to be held in an open state and a closed state by a holding mechanism such as a hinge mechanism.

[0032] In this way, in this embodiment, a method (direct replenishment method) is adopted in which the user replenishes toner from a toner pack 40 (see Figures 1(a) and 1(b)) filled with replenishment toner to the developing device 30 while the developing device 30 is still attached to the image forming device 1.

[0033] [Recovery of residual toner after transfer] This embodiment employs a cleanerless configuration in which residual toner remaining on the photosensitive drum 21 without being transferred to the recording material P is collected in the developing device 30 and reused. The residual toner is removed through the following process. The residual toner includes a mixture of positively charged toner and negatively charged toner that does not have a sufficient charge. The pre-exposure device 23 neutralizes the photosensitive drum 21 after transfer, and the charging roller 22 generates a uniform discharge, thereby re-charging the residual toner to a negative polarity. The residual toner, re-charged to a negative polarity 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 adhering to the surface, and an electrostatic latent image is written onto it.

[0034] Here, the behavior of the transfer residual toner that has reached the development unit will be explained separately for the exposed and non-exposed areas of the photosensitive drum 21. The transfer residual toner adhering to the non-exposed area of ​​the photosensitive drum 21 is transferred to the development roller 31 in the development unit due to the potential difference between the potential of the non-exposed area (dark area potential) of the photosensitive drum 21 and the development voltage, and is then collected in the development container 32. This is because the normal charge polarity of the toner is negative, and the development voltage applied to the development roller 31 is positive relative to the potential of the non-exposed area. The toner collected in the development container 32 is stirred and dispersed with the toner in the development container by the stirring member 34, and is then carried by the development roller 31 and used again in the development process.

[0035] On the other hand, the transfer residual toner adhering to the exposed portion of the photosensitive drum 21 does not transfer from the photosensitive drum 21 to the developing roller 31 at the developing portion, but remains on the drum surface. This is because the normal charging polarity of the toner is negative, and the developing voltage applied to the developing roller 31 has a potential that is more negative than the potential of the exposed portion (light portion potential). The transfer residual toner remaining on the drum surface is carried by the photosensitive drum 21 together with other toner transferred from the developing roller 31 to the exposed portion, and moves to the transfer portion, where it is transferred to the recording material P.

[0036] As described above, the present embodiment employs a cleaner-less configuration (a simultaneous development and recovery method) in which the transfer residual toner is recovered in the developing device 30 and reused, but a conventionally known configuration in which the transfer residual toner is recovered using a cleaning blade that contacts the photosensitive drum 21 may also be used. In this case, the transfer residual toner recovered by the cleaning blade is collected in a collection container that is installed separately from the developing device 30. However, by adopting a cleaner-less configuration, installation space for a collection container for recovering the transfer residual toner and the like is not required, which enables the image forming apparatus 1 to be further miniaturized, and also reduces printing costs by reusing the transfer residual toner.

[0037] [Configuration of the developer container and toner pack] Next, the configurations of the developing container 32 and the toner pack 40 serving as a supply container will be described. Fig. 4(a) is a perspective view showing the developing container 32 and the toner pack 40, and Fig. 4(b) is a front view showing the developing container 32 and the toner pack 40. Fig. 4(c) is a perspective view showing the stirring member 34 in the developing container 32. Fig. 5(a) is a cross-sectional view taken along line 5A-5A in Fig. 4(b), and Fig. 5(b) is a cross-sectional view taken along line 5B-5B in Fig. 4(b).

[0038] As shown in FIGS. 4(a) to 5(b), a developer container 32 (container) as part of the developing device 30 has a transport chamber 36 that houses an agitator 34. The transport chamber 36, which serves as a container for accommodating toner, extends over the entire length of the developer container 32 in the longitudinal direction LD (left-right direction). The longitudinal direction LD of the developer container 32 is the direction of the rotation axis of the developer roller 31, which is a developer carrier. The developer container 32 is configured by connecting a developer container frame 320 and a developer container lid 321 by a connecting portion 322. The developer roller 31 and the supply roller 33 are rotatably supported by the developer container frame 320.

[0039] The developing container 32 also has a supply protrusion 37 that protrudes upward from one end of the conveying chamber 36 in the longitudinal direction and communicates with the conveying chamber 36. More specifically, the supply protrusion 37 is provided at one end of the developing container lid 321 in the rotational axis direction (longitudinal direction LD) of the developing roller 31. The supply protrusion 37 protrudes toward the discharge tray 81 in a direction intersecting the rotational axis direction (particularly, upward in the direction of gravity) beyond the center of the developing container 32 in the rotational axis direction.

[0040] In this embodiment, the supply protrusion 37 is hollow and is disposed on the left side of the developing container 32. An attachment portion 57 to which the toner pack 40 can be attached is provided at the end of the supply protrusion 37, and a rotatable supply port 32a is disposed in the attachment portion 57 so that the developer can be replenished from the toner pack 40 to the conveying chamber 36. The toner pack 40 can be attached to the attachment portion 57 in a state where it is exposed to the outside of the device.

[0041] The supply protrusion 37 extends obliquely from the transport chamber 36 toward the front and upward of the apparatus. That is, the supply protrusion 37 protrudes toward the downstream and upward in the discharge direction of the discharge roller pair 80. Therefore, the supply port 32a arranged in the supply protrusion 37 is arranged on the front side of the image forming apparatus 1, making it easy to supply toner to the developing container 32. Furthermore, by providing the supply protrusion 37 where the supply port 32a is arranged on one side in the longitudinal direction of the developing container 32, it is possible to ensure a laser passage space through which the laser emitted from the scanner unit 11 can pass, and the image forming apparatus 1 can be made more compact.

[0042] As shown in FIGS. 4(a) to 5(b), the toner pack 40 is configured to be detachably attached to the mounting portion 57 of the supply protrusion 37. The toner pack 40 also has an openable / closable shutter member 41 provided at the opening of the toner pack 40 and a groove 42 formed in correspondence with the protrusion 32b formed on the mounting portion 57. When replenishing toner into the developing container 32, the user aligns the toner pack 40 so that the groove 42 passes through the protrusion 32b of the mounting portion 57, and then 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. This causes the supply port 32a to rotate together with the shutter member 41 and abut against an abutment portion (not shown) of the mounting portion 57, completely opening the shutter member 41 and simultaneously connecting the supply port 32a to 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 passes through the replenishing port 32a and the hollow replenishing protrusion 37 and enters the transport chamber .

[0043] As shown in FIG. 4(c), the agitating member 34 has an agitating 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 agitating shaft 34a. The first blade portion 34b1 and the second blade portion 34b2 are both formed of flexible sheets and have different lengths of extension radially outward. The first blade portion 34b1 is longer than the second blade portion 34b2. In FIGS. 5(a) and 5(b), Tb1 indicates the rotation trajectory of the first blade portion 34b1 when it is assumed that the first blade portion 34b1 rotates in a straight state, ignoring the wall surface of the developing container 32. 5(a) and 5(b) show the rotation trajectory Tb2 of the second blade portion 34b2 when it is assumed that the second blade portion 34b2 rotates in a straight extended state, ignoring the wall surface of the developing container 32. The wiping portion 34c of the agitating member 34 shown in FIG. 4(c) will be described later.

[0044] As shown in FIG. 5A, toner supplied from the supply port 32a, which is located upstream of the agitator 34 in the conveying direction, is sent toward the developing roller 31 and the supply roller 33 as the agitator 34 rotates. The supply port 32a and the supply protrusion 37 are located at one end of the developer container 32 in the longitudinal direction LD, and repeated rotation of the agitator 34 distributes the toner throughout the entire length of the developer container 32. In other words, the conveying direction of the agitator 34 is parallel to the longitudinal direction LD of the developer container 32 (see FIG. 4A) and also intersects with the longitudinal direction LD (the direction from the conveying chamber 36 toward the developing roller 31 and the supply roller 33). Here, as shown by the rotation loci Tb1 and Tb2, the first blade portion 34b1, which is the longer blade portion, functions as a main portion that conveys toner toward the developing roller 31 and the supply roller 33. On the other hand, the second blade portion 34b2, which is the shorter blade portion, functions as an auxiliary portion for transporting toner at, for example, the corner portion 36e of the transport chamber 36, which the first blade portion 34b1 cannot transport properly due to contact with the bottom portion.

[0045] In this embodiment, the toner pack 40 is configured as a bag made of easily deformable plastic film, as shown in FIGS. 6 and 7(a), but is not limited thereto. For example, the toner pack (supply container) may be configured as a substantially cylindrical bottle container 40B as shown in FIG. 7(b), or as a paper container 40C made of paper as shown in FIG. 7(c). In either case, the toner pack (supply container) may be made of any material and any shape. Furthermore, the toner is preferably discharged from the toner pack (supply container) by squeezing the toner pack 40 or the paper container 40C with the user's fingers, while the toner is preferably discharged from the bottle container 40B by vibrating the container, such as by tapping the container. A discharge mechanism may also be provided within the bottle container 40B to discharge the toner from the bottle container 40B. Furthermore, the discharge mechanism may be configured to engage with the printer main body 100 and receive driving force from the printer main body 100.

[0046] Furthermore, the shutter member 41 may be omitted in either toner pack, or a sliding shutter member may be used instead of the rotating shutter member 41. The shutter member 41 may be configured to be destroyed when the toner pack is attached to the replenishing port 32a or when the toner pack is rotated while attached, or may have a removable lid structure such as a seal.

[0047] Furthermore, in this embodiment, the stirring member 34 is provided with two blade portions 34b1 and 34b2 having different lengths, but the length and number of the blade portions are not limited to this. For example, they may be freely set in consideration of the shape of the developing container 32, transport efficiency, etc.

[0048] [Method for detecting remaining toner] Next, the configuration of the developing device 30 for detecting remaining toner amount according to this embodiment will be described in more detail with reference to FIGS. 8 to 14. FIG. 8 is a perspective view of the developing device 30. FIG. 9(a) is a perspective view showing the state in which the substrate 700 and the substrate holding member 710 are assembled to the developing container lid 321. FIG. 9(b) is a perspective view showing the substrate 700 and the substrate holding member 710, and FIG. 9(c) is another perspective view showing the substrate 700 and the substrate holding member 710. FIG. 10(a) is a cross-sectional view passing through the light-emitting element 510a of the developing device 30 in the position of the developing device 30 when detecting the remaining toner amount, and FIG. 10(b) is a cross-sectional view taken along line 10B-10B of FIG. 10(a). FIG. 11 is a circuit diagram schematically illustrating an example of the circuit configuration of the remaining toner amount sensor 500. FIG. 12(a) is a cross-sectional view showing the developing container 32 in a state in which the remaining toner amount is low in the position of the developing device 30 when detecting the remaining toner amount. FIG. 12(b) is a cross-sectional view showing the developing container 32 in a state where there is a large amount of remaining toner, in the attitude of the developing device 30 when the amount of remaining toner is detected.

[0049] As shown in FIG. 8, the developer-container lid 321, which constitutes a part of the developer container 32, has substrate positioning members 321a and 321b and substrate fixing portions 321c and 321d. A light-guiding member 600 serving as a light guide is provided between the substrate fixing portions 321c and 321d of the developer-container lid 321 in the longitudinal direction LD. The light-guiding member 600 has a light-emitting side light guide 610 and a light-receiving side light guide 620. The light-emitting side light guide 610 guides light emitted from a light-emitting element 510a (described later) into the transfer chamber 36 of the developer container 32. The light-receiving side light guide 620 guides light that has been emitted from the light-emitting side light guide 610 and passed through a spatial optical path Q (see FIGS. 10(a) and 10(b)) in the transfer chamber 36 to a light-receiving element 510b (described later). The light guiding member 600 is provided on the developer container lid 321, which is a wall surface of the developer container 32 (container), and functions as a light guiding means for guiding the light emitted by the light emitting element 510a to reach the light receiving element 510b through the internal space of the developer container 32. The light guiding member 600, the light emitting element 510a, and the light receiving element 510b form a remaining toner amount sensor 500 as a means for detecting the amount of developer.

[0050] The substrate positioning members 321a and 321b as positioning members are disposed outside the substrate fixing members 321c and 321d, respectively, in the longitudinal direction LD of the developing container 32, and have boss shapes that protrude in directions away from the developing container 32. The shapes of the substrate positioning members 321a and 321b are not limited to boss shapes and may be any shapes. The longitudinal direction LD of the developing container 32 is the same as the longitudinal direction LD of the process unit 20 (see FIG. 4(a)). Fixing members such as screws can be threaded into the substrate fixing members 321c and 321d.

[0051] 9A, in this embodiment, a substrate 700 and a substrate holding member 710 are assembled to the developer container lid 321. The substrate holding member 710 is assembled to the developer container lid 321 in a state where it is sandwiched between the developer container lid 321 and the substrate 700. It is also possible to simplify the structure for holding the substrate 700 and assemble the substrate 700 directly to the developer container lid 321 without using the substrate holding member 710.

[0052] 9(b), the substrate 700 is provided on a surface facing the substrate holding member 710 and has a light emitting element 510a and a light receiving element 510b for detecting the amount of toner remaining in the transfer chamber 36. In this embodiment, an LED is used as the light emitting element 510a, and a phototransistor that is turned on by light from the LED is used as the light receiving element 510b, but this is not limiting. For example, a halogen lamp or a fluorescent lamp may be used as the light emitting element 510a, and a photodiode or an avalanche photodiode may be used as the light receiving element 510b.

[0053] The substrate 700 is also provided with a cable connector 700n, which is connected to a control unit 90 (described later) provided in the printer main body 100 via a cable.

[0054] The substrate 700 also has positioning holes 700a and 700b into which the substrate positioning members 321a and 321b are inserted and engaged, and substrate fixing holes 700c and 700d through which screws that are screwed into the substrate fixing portions 321c and 321d can pass.

[0055] Similarly, the substrate holding member 710 has positioning holes 710a and 710b into which the substrate positioning members 321a and 321b are inserted and engaged, and substrate fixing holes 710c and 710d through which screws that are screwed into the substrate fixing members 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-guiding member 600 is inserted, and a second hole 711b into which the light-receiving side light guide 620 of the light-guiding member 600 is inserted. The first hole 711a and the second hole 711b have a cylindrical shape. The substrate holding member 710 functions as a holder that holds the substrate 700.

[0056] Furthermore, light-shielding plates 710e and 710f are provided as shielding portions on the side of the substrate holding member 710 facing the substrate 700. These light-shielding plates 710e and 710f are disposed between the light-emitting element 510a and the light-receiving element 510b in the longitudinal direction LD in a state in which the substrate 700 and the substrate holding member 710 are attached to the developing container lid 321, and are provided in the vicinity of the substrate 700.

[0057] 8 to 10(a), the substrate holding member 710 is positioned relative to the developer container lid 321 by the substrate positioning members 321a and 321b of the developer container lid 321 penetrating and engaging with the positioning holes 710a and 710b. The substrate 700 is positioned relative to the developer container lid 321 by the substrate positioning members 321a and 321b of the developer container lid 321 penetrating and engaging with the positioning holes 700a and 700b. In this way, the substrate positioning members 321a and 321b are commonly used to position the substrate holding member 710 and the substrate 700, so that the developer container lid 321, the substrate holding member 710, and the substrate 700 can be positioned with higher accuracy.

[0058] 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 to the developing container lid 321 with the screws, and the substrate holding member 710 and the substrate 700 are fixed to the developing container lid 321.

[0059] As shown in FIGS. 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-guiding 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 proximity to the light-emitting element 510a of the substrate 700. Similarly, the light-receiving side light guide 620 of the light-guiding 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 proximity to the light-receiving element 510b of the substrate 700.

[0060] As described above, the substrate holding member 710 and the substrate 700 are accurately positioned on the developing container lid 321, which can increase 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 has passed through the light-emitting side light guide 610 and is guided to the inside of the developing container 32 is emitted from the light-emitting side light guide 610 in the longitudinal direction LD.

[0061] Then, the light traveling along the spatial optical path Q inside the transfer chamber 36 enters the light-receiving-side light guide 620, passes through the inside of the light-receiving-side light guide 620, and is guided to the outside of the developing container 32. Since the light-receiving-side light guide 620 is disposed 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-side light guide 620 can be increased.

[0062] 9(b) and 9(c), light-shielding plates 710e and 710f are disposed on the substrate holding member 710 between the light-emitting element 510a and the light-receiving element 510b and in close proximity to the substrate 700. Therefore, the light emitted from the light-emitting element 510a and traveling toward the light-receiving element 510b without passing through the light-emitting side light guide 610 and the light-receiving side light guide 620 is blocked by the light-shielding plates 710e and 710f. This reduces false detections caused by light that does not pass through the spatial light path Q (stray light) being received by the light-receiving element 510b.

[0063] The arrangement of the light-emitting element 510a and the light-receiving element 510b will now be described in more detail. As shown in FIGS. 10(a) and 10(b), the light-emitting element 510a and the light-receiving element 510b are arranged facing the side surface 36a of the developer container 32 opposite the developing roller 31. The light-emitting element 510a and the light-receiving element 510b are also provided in the central portion of the transport chamber 36 in the longitudinal direction LD. More specifically, as shown in FIG. 10(b), the light-emitting element 510a and the light-receiving element 510b are arranged such that the center portion 31a (broken line) of the developing roller 31 is located between the light-emitting element 510a and the light-receiving element 510b in the longitudinal direction LD. By providing the light-emitting element 510a and the light-receiving element 510b in the central portion of the transport chamber 36 in this way, the remaining toner amount 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 direction LD, the central portion of the transport chamber 36 has less uneven distribution of developer, allowing for more accurate detection of the remaining toner amount.

[0064] 11, a switch (not shown) is provided between light-emitting element 510a and power supply voltage Vcc. By turning on this switch, voltage from power supply voltage Vcc is applied to light-emitting element 510a, causing light-emitting element 510a to enter a conductive state. Meanwhile, a switch (not shown) is also provided between light-receiving element 510b and power supply voltage Vcc, and by turning on this switch, light-receiving element 510b enters a conductive state due to a current corresponding to the detected amount of light.

[0065] A power supply voltage Vcc and a current limiting resistor R1 are connected to the light-emitting element 510a, and the light-emitting element 510a emits light using a current determined by the current limiting resistor R1. The light emitted from the light-emitting element 510a passes through the spatial optical path Q (FIG. 10(b)) inside the developing container 32 and is received by the light-receiving element 510b. A 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 FIG. 11). That is, the light-receiving element 510b changes the value of its output signal (voltage value) according to the amount of toner (developer) contained in the transfer chamber 36.

[0066] 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 that the light receiving element 510b detects each light and the intensity of the received light when the toner in the developing container 32 is stirred for a certain time by the stirring member 34. That is, the ROM 93 stores in advance a table that can output the remaining toner amount from the light receiving time and light intensity when the toner is transported by the stirring member 34, and the control unit 90 predicts / calculates the remaining toner amount based on the input to the A / D conversion unit 95 and the table.

[0067] 10A, the spatial light path Q of the remaining toner amount sensor 500 is set to overlap with the rotation loci Tb1 and Tb2 of the agitator 34 when viewed in the axial direction of the rotation shaft of the agitator 34. In other words, the light emitted from the light-emitting element 510a of the remaining toner amount sensor 500 passes inside the conveying chamber 36, inside the rotation loci Tb1 and Tb2 of the agitator 34 when viewed in the axial direction of the agitator 34. The time during which the spatial light path Q is blocked by the toner conveyed by the agitator 34 when the agitator 34 makes one rotation, i.e., the time during which the light-receiving element 510b does not detect light from the light-emitting element 510a, varies depending on the amount of remaining toner. The intensity of light incident on the light-receiving element 510b (the amount of received light) also varies depending on the amount of remaining toner.

[0068] In other words, when the remaining toner amount is high, the spatial optical path Q is more likely to be blocked by the toner, so the time during which the light receiving element 510b receives light is shorter, and the intensity of the light received by the light receiving element 510b is lower (the amount of light received is smaller). Conversely, when the remaining toner amount is low, the time during which the light receiving element 510b receives light is longer, and the intensity of the light received by the light receiving element 510b is stronger (the amount of light received is larger). Therefore, the control unit 90 can determine the remaining toner amount level as follows, based on the light receiving time and light intensity of the light receiving element 510b.

[0069] For example, if the time during which the light receiving element 510b receives light is longer than a predetermined threshold, or the intensity of light received by 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 small, as shown in Figure 12(a). On the other hand, if the time during which the light receiving element 510b receives light is shorter than the predetermined threshold, or the intensity of light received by the light receiving element 510b is weaker than the predetermined threshold, it is determined that the amount of toner remaining in the transport chamber 36 of the developing container 32 is large, as shown in Figure 12(b).

[0070] [Image forming device control system] 13 is a block diagram showing a control system of image forming apparatus 1. A control unit 90 serving as a control means of image forming apparatus 1 includes a CPU 91 as a calculation device, a RAM 92 used as a work area for 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 connected to external devices, and an A / D conversion unit 95 for converting analog signals into digital signals.

[0071] The input side of the control unit 90 is connected to a remaining toner amount sensor 500, an attachment sensor 53, and an open / close sensor 54. The attachment sensor 53 detects that the toner pack 40 has been attached to the supply port 32a of the developing container 32. For example, the attachment sensor 53 is provided in the supply port 32a and is configured from a pressure-sensitive switch that outputs a detection signal when pressed by a protrusion on the toner pack 40. The open / close sensor 54 detects whether the discharge tray 81 has been opened. The open / close sensor 54 is configured from, for example, a pressure-sensitive switch or a magnetic sensor.

[0072] The control unit 90 is also connected to an operation unit 300, the image forming unit 10, and a toner remaining amount panel 400 as a notification unit capable of notifying information related to the amount of remaining toner. The operation unit 300 has a display unit 301 capable of displaying various setting screens, physical keys, etc. The display unit 301 is configured, for example, with 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, agitator 34, etc. Note that the photosensitive drum 21, developing roller 31, supply roller 33, and agitator 34 may each be driven by a separate motor.

[0073] 1(b) and 14(a) to (d), the remaining toner amount panel 400 is provided on the right side of the front surface of the housing of the printer main body 100, i.e., on the opposite side to the operation unit 300 located on the left side, and displays information regarding the remaining amount of toner in the developing container 32. In this embodiment, the remaining toner amount panel 400 is a panel member made up of multiple scales (three in this embodiment) arranged vertically, and each scale corresponds to a low level, a mid level, and a full level.

[0074] That is, as shown in Figure 14(a), when only the lower scale is flashing, the remaining toner amount in the developing container 32 is at the NearOut level. As shown in Figure 14(b), when only the lower scale is lit, the remaining toner amount in the developing container 32 is at the Low level. As shown in Figure 14(c), when the lower and center scales are lit and the upper scale is off, the remaining toner amount in the developing container 32 is at the Mid level. As shown in Figure 14(d), when all three scales are lit, the remaining toner amount in the developing container 32 is at the Full level.

[0075] The NearOut level indicates the amount of remaining toner that will soon run out in the developer container 32, making it impossible to form an image properly. The Low level indicates the amount of remaining toner that is greater than the NearOut level and less than the Mid level. The Mid level indicates the amount of remaining toner that is greater than the Low level and less than the Full level.

[0076] The toner remaining amount panel 400 is not limited to a liquid crystal panel, and may be configured with a light source such as an LED or an incandescent lamp and a diffusion lens. The placement of the toner remaining amount panel 400 is not limited to the right side. For example, it may be provided on the left side, the same as the operation unit 300. Alternatively, instead of providing a separate toner remaining amount panel 400, the display of the operation unit 300 may display the remaining toner amount using scales as described in this embodiment. When the toner remaining amount in the developing container 32 reaches a low level, a replenishment notice may be displayed on the operation unit 300 to prompt the user to replenish toner. When the toner runs out, a replenishment notice may be displayed on the operation unit 300 to prompt the user to replenish toner.

[0077] In addition, in this embodiment, a configuration in which four states are displayed using three scales has been described, but the number of scales is not limited to this and may be set appropriately depending on the configuration of the image forming apparatus. Furthermore, the remaining toner amount may be continuously displayed using a percentage or gauge display. Furthermore, the remaining toner amount may be notified to the user by voice using a speaker.

[0078] 14(a) to 14(d), the toner remaining amount panel 400 has been described as a means for notifying the user of the amount of remaining toner, but the present invention is not limited to this. For example, the display in FIG. 14(b) may indicate that toner needs to be replenished, the display in FIG. 14(c) may indicate that toner does not need to be replenished, and the display in FIG. 14(d) may indicate that toner has been sufficiently replenished.

[0079] Furthermore, the light-emitting element 510a and the light-receiving element 510b of this embodiment are arranged side by side in the longitudinal direction LD of the process unit 20, and are arranged on the same side (the front side) of the transfer chamber 36 as viewed in the longitudinal direction LD. This allows the light-emitting element 510a and the light-receiving element 510b to be arranged compactly. Furthermore, the light-emitting element 510a and the light-receiving element 510b are mounted 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 also allows signals to be easily exchanged between the light-emitting element 510a and the light-receiving element 510b. This allows the process unit 20 to be made smaller.

[0080] [Light guide member] Next, the configuration of the light-guiding member 600 in this embodiment will be described in more detail. FIGS. 15(a) and 15(b) are perspective views showing the light-guiding member 600 as a single component before being integrated with the developer-container lid 321. FIG. 15(a) shows the front side of the light-guiding member 600, i.e., the side that does not come into contact with the developer in the developer container 32 and is exposed to the outside of the developer container 32. FIG. 15(b) shows the back side of the light-guiding member 600, i.e., the side that comes into contact with the developer in the developer container 32 and is exposed to the inside of the developer container 32. The detection light OP shown in FIGS. 15(a) and 15(b) represents the representative optical path (optical axis) of light emitted from the light-emitting element 510a, passing through the light-guiding member 600, and then received by the light-receiving element 510b. The spatial optical path Q described above is the portion of the path of the detection light OP that passes through the internal space of the developer container 32.

[0081] 16(a) to 16(e) are views showing the light-guiding member 600 and the detection light OP from five directions by third-angle projection, with the back side of the light-guiding member 600 as the front. FIG. 16(a) is a front view showing the back side of the light-guiding member 600. FIG. 16(b) is a side view seen from the light-emitting element 510a side in the longitudinal direction LD. FIG. 16(c) is a side view seen from the light-receiving element 510b side in the longitudinal direction LD. FIG. 16(d) is a plan view seen from above in the height direction ND. FIG. 16(e) is a bottom view of the light-guiding member 600 seen from below in the height direction ND and an enlarged view of a portion thereof.

[0082] In the following description, the up-down direction refers to the direction of gravity WD (vertical direction) in the posture when the light guiding member 600 detects the amount of developer (posture at the time of detection, see FIG. 12). The direction of gravity WD does not necessarily coincide with the height direction ND of the light guiding member 600, which will be described later. The direction perpendicular to both the longitudinal direction LD of the developing container 32 and the direction of gravity WD is defined as the horizontal direction HD.

[0083] 15(a) to 16(d), the light-guiding member 600 is a member in which a light-emitting side light guide 610, a light-receiving side light guide 620, and a frame 650 are integrally formed. The light-guiding 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 the light-emitting side light guide 610 and the light-receiving side light guide 620 integrally molded via the frame 650. For example, the light-emitting side light guide 610 and the light-receiving side light guide 620 may be molded as separate members and attached to the developing container lid 321, respectively.

[0084] (frame) The frame portion 650 is a plate-like portion that constitutes the wall surface of the developer container 32 together with the developer container lid 321. The frame portion 650 has an installation surface 680 (FIGS. 17(a) and 17(b)) that is a surface that comes into contact with a mounting seat surface 3211 of the developer container lid 321, which will be described later.

[0085] (Light-emitting side light guide) The light-emitting side light-guiding body 610 is a light-guiding body for guiding the detection light OP emitted from the light-emitting element 501a outside the developing container 32 into the transfer chamber 36. The light-emitting side light-guiding body 610 includes an outer light-guiding portion 611 that protrudes from a surface 653 of the frame portion 650 toward the outside of the developing container 32, and an inner light-guiding portion 612 that protrudes from a back surface 654 of the frame portion 650 toward the inside of the developing container 32. An inner upper portion 630 that is a portion extending upward from the inner light-guiding portion 612 is provided above the inner light-guiding portion 612. The inner upper portion 630, together with the inner light-guiding portion 612, protrudes from the back surface 654 of the frame portion 650 toward the inside of the developing container 32.

[0086] The outer light-guiding portion 611 of the light-emitting side light guide 610 protrudes from a surface 653 of a frame portion 650 that constitutes part of the outer surface of the developing container 32 toward the outside of the developing container 32 (the right side in FIG. 16(b)). The outer light-guiding portion 611 is a first protruding portion in this embodiment. The inner light-guiding portion 612 and the inner upper portion 630 of the light-emitting side light guide 610 protrude from a back surface 654 of the frame portion 650 that constitutes part of the inner surface of the developing container 32 toward the inside of the developing container 32 (the left side in FIG. 16(b)). The inner light-guiding portion 612 and the inner upper portion 630 are second protruding portions in this embodiment. The inner light-guiding portion 612 is a lower portion of the second protruding portion in this embodiment, and the inner upper portion 630 is an upper portion of the second protruding portion in this embodiment.

[0087] The protruding direction TD of the outer light guiding portion 611, the inner light guiding portion 612, and the upper inner portion 630 relative to the frame 650 is a direction substantially perpendicular to an installation surface 680 (a direction perpendicular to both the longitudinal direction LD and the height direction ND), which is a surface of the frame 650 that abuts against the developing container lid 321. However, the outer light guiding portion 611, the inner light guiding portion 612, or the upper inner portion 630 may protrude at an angle that obliquely intersects with the direction perpendicular to the installation surface 680. The protruding direction TD is also the optical axis direction of the detection light OP guided from the outer light guiding portion 611 toward the inner light guiding portion 612 inside the light-emitting side light-guiding body 610.

[0088] In this embodiment, the side surface of the inner upper portion 630 is continuous with the side surface of the inner light guiding portion 612, and the inner upper portion 630 is integrally formed of the same material as the inner light guiding portion 612. However, the inner upper portion 630 and the inner light guiding portion 612 may be formed of different materials.

[0089] The inner upper portion 630 has a different function from the inner light guide 612 in that it is not shaped to guide the detection light OP. Therefore, a boundary line between the inner light guide 612 and the inner upper portion 630 is illustrated as a first imaginary line IL1. When viewed in the longitudinal direction LD, the first imaginary line IL1 is a straight line that passes through a boundary portion 611ct between the upper surface 611c of the outer light guide 611 and the surface 653 of the frame portion 650 and extends in the direction of the optical axis of the detection light OP from the outer light guide 611 to the inner light guide 612. In other words, within the second protrusion, a portion that substantially forms the optical path of the detection light OP (a portion below the first imaginary line IL1) is defined as the inner light guide 612, and a portion that does not substantially contribute to forming the optical path of the detection light OP (a portion above the first imaginary line IL1) is defined as the inner upper portion 630.

[0090] (light receiving side light guide) The light-receiving-side light guide 620 is a light guide that guides light incident via the spatial light path Q in the transfer chamber 36 to the light-receiving element 501b outside the developing container 32. The light-receiving-side light guide 620 includes an outer light guide portion 621 that protrudes from a 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 a back surface 654 of the frame portion 650 toward the inside of the developing container 32. The light-receiving-side light guide 620 also includes an inner upper portion 640 that is located above the inner light guide portion 622 and 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.

[0091] The outer light guiding portion 621 of the light-receiving side light guide 620 is a fourth protrusion of this embodiment that protrudes from a surface 653 of a frame portion 650 that constitutes part of the outer surface of the developer container 32 toward the outside of the developer container 32 (the left side in FIG. 16(c)). The inner light guiding portion 622 and the inner upper portion 640 of the light-receiving side light guide 620 are third protrusions of this embodiment that protrude from a back surface 654 of the frame portion 650 that constitutes part of the inner surface of the developer container 32 toward the inside of the developer container 32 (the right side in FIG. 16(c)). The inner light guiding portion 622 is a lower portion of the third protrusion of this embodiment, and the inner upper portion 640 is an upper portion of the third protrusion of this embodiment.

[0092] The protruding direction TD of the outer light guiding portion 621, the inner light guiding portion 622, and the upper inner portion 640 relative to the frame 650 is a direction substantially perpendicular to the installation surface 680 of the frame 650 (a direction perpendicular to both the longitudinal direction LD and the height direction ND). In other words, the protruding direction of the outer light guiding portion 621, the inner light guiding portion 622, and the upper inner portion 640 of the light-receiving side light guide 620 relative to the frame 650 is substantially the same as the protruding direction TD of the outer light guiding portion 611, the inner light guiding portion 612, and the upper inner portion 630 of the light-emitting side light guide 610. However, the outer light guiding portion 621, the inner light guiding portion 622, or the upper inner portion 640 of the light-receiving side light guide 620 may protrude at an angle that obliquely intersects with the direction perpendicular to the installation 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 side light guide 620.

[0093] In this embodiment, the side surface of the inner upper portion 640 of the light-receiving side light guide 620 is continuous with the side surface of the inner light-guiding portion 622, and the inner upper portion 640 is integrally formed with the inner light-guiding portion 622 using the same material. However, the inner upper portion 640 may be formed with a material different from that of the inner light-guiding portion 622.

[0094] The inner upper portion 640 of the light-receiving side light guide 620 has a different function from the inner light guide 622 in that it is not shaped to guide the detection light OP. Therefore, the boundary between the inner light guide 622 and the inner upper portion 640 is illustrated as a second imaginary line IL2. When viewed in the longitudinal direction LD, the second imaginary line IL2 is a straight line that passes through a boundary portion 621ct between the upper surface 621c of the outer light guide 621 and the surface 653 of the frame portion 650 and extends in the optical axis direction of the detection light OP from the inner light guide 622 toward the outer light guide 621. In other words, within the third protrusion, a portion that substantially forms the optical path of the detection light OP (a portion below the second imaginary line IL2) is defined as the inner light guide 622, and a portion that is not substantially necessary for forming the optical path of the detection light OP (a portion above the second imaginary line IL2) is defined as the inner upper portion 640.

[0095] (Optical path design) The outer light-guiding section 611 of the light-emitting side light-guiding body 610 has an incident surface 611a (first incident surface) onto 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-guiding section 611 in the protruding direction TD of the outer light-guiding section 611 relative to the surface 653 of the frame section 650 (the outer surface of the developing container 32). The light-emitting element 510a (FIG. 9(b)) is disposed so as to face the incident surface 611a. The light irradiated from the light-emitting element 510a is generally diffused light, and the incident surface 611a is shaped like a convex lens to correct this light to light oriented in the same direction. The lens shape is designed taking into consideration the distance between the light-emitting element 510a and the incident surface 611a, etc.

[0096] The inner light-guiding section 612 of the light-emitting side light-guiding body 610 has a reflecting surface 612b and a light-emitting window 612a. The reflecting surface 612b mirror-reflects the detection light OP, which is incident on the incident surface 611a of the outer light-guiding section 611 and passes from the outer light-guiding section 611 to the inner light-guiding section 612, toward the light-emitting window 612a, thereby changing the direction of the detection light OP inside the light-emitting side light-guiding body 610. The light-emitting window 612a is an exit surface (second exit surface) that emits the detection light OP reflected by the reflecting surface 612b into the spatial light path Q within the transfer chamber 36.

[0097] The inner light-guiding section 622 of the light-receiving side light-guiding body 620 has a light-receiving window 622a and a reflecting surface 622b. The light-receiving window 622a is an incident surface (second incident surface) through which the detection light OP passing through the spatial light path Q in the transfer chamber 36 enters the light-receiving side light-guiding body 620. The reflecting surface 622b is a surface that specularly reflects the detection light OP that has entered the light-receiving window 622a of the inner light-guiding section 622 toward the outer light-guiding section 621, thereby changing the direction of the detection light OP inside the light-emitting side light-guiding body 610.

[0098] The outer light-guiding section 621 of the light-receiving side light guide 620 has an exit surface 621a (first exit surface) that emits the detection light OP, which is incident on the light-receiving window 622a of the inner light-guiding section 622 and has been redirected by the reflecting surface 622b, toward the light-receiving element 510b. The exit surface 621a is provided at a tip of the outer light-guiding section 621 in the protruding direction TD of the outer light-guiding section 621 relative to the surface 653 of the frame section 650 (the outer surface of the developing container 32). The light-receiving element 510b (FIG. 9(b)) is disposed to face the exit surface 621a of the light-receiving side light guide 620.

[0099] 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 disposed to face each other inside the developing container 32. A spatial light path Q through which the detection light OP passes is formed between the light-emitting window 612a and the light-receiving window 622a. 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 direction of the spatial light path Q is substantially parallel to the longitudinal direction LD of the developing container 32; however, the spatial light path Q may be oriented in a direction different from the longitudinal direction LD as long as it intersects with the direction of gravity WD. In this embodiment, the direction of the spatial light path Q is the longitudinal direction LD, and the light guide member 600 is disposed 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 (indicated by the broken line in FIG. 10(b)). This makes it less susceptible to the influence of uneven distribution of developer in the transport chamber 36, and is expected to improve the accuracy of detecting the amount of developer, but the light guide member 600 may be disposed at another position.

[0100] (Relationship between the stirring member and the light guide member) Here, the configuration of the agitating member 34 related to the light-guiding member 600 will be described. As shown in FIG. 4(c), the agitating member 34 has a wiping portion 34c including a light-emitting side wiping end 34c1 and a light-receiving side wiping end 34c2, and an auxiliary wiping portion 34d, at a position facing the light-guiding member 600 in the longitudinal direction LD. The auxiliary wiping portion 34d is disposed downstream in the rotation direction of the agitating member 34, overlapping with the wiping portion 34c. The wiping portion 34c and the auxiliary wiping portion 34d are flexible sheets. In addition, the rotation locus Tc of the wiping portion 34c as viewed in the axial direction (longitudinal direction LD) of the agitating member 34 is set to overlap with the spatial light path Q (see FIG. 10(a)). The rotation trajectory Tc of the wiping portion 34c is drawn as a circle with a rotation radius centered on the rotation axis of the stirring member 34, assuming that the wiping portion 34c extends straight, ignoring the wall surface of the developing container 32.

[0101] As the agitating member 34 rotates, the light-emitting side wiping end 34c1 passes through the light-guiding member 600 while rubbing against the light-emitting window 612a of the light-emitting side light guide 610, and the light-receiving side wiping end 34c2 passes through the light-guiding member 600 while rubbing against the light-receiving window 622a of the light-receiving side light guide 620. That is, with each rotation of the agitating member 34, the wiping portion 34c wipes away developer adhering to the light-emitting window 612a and the light-receiving window 622a. The wiping assistant portion 34d adjusts the contact pressure and angle of the wiping portion 34c with the light-emitting window 612a and the light-receiving window 622a, and is designed taking into consideration the shapes and positional relationship between the light-guiding member 600 and the agitating member 34. Note that if the wiping portion 34c alone can sufficiently wipe off developer, the wiping assistant portion 34d may be omitted. Furthermore, the wiping portion 34c may be omitted, and the blade portion of the agitating member 34 may be used to clean the light-emitting window 612a and the light-receiving window 622a of the light-guiding member 600.

[0102] 16(e), which is a bottom view of the light-guiding member 600, the light-emitting window 612a is not completely flat, but has a curved surface shape that is convex toward the spatial light path Q side (inside the developing container 32) when viewed in the height direction ND. The light-receiving window 622a also has a curved surface shape that is convex toward the spatial light path Q side (inside the developing container 32) when viewed in the height direction ND. This allows the wiping portion 34c of the agitating member 34 to locally and strongly abut near the vertices of the curves of the light-emitting window 612a and the light-receiving window 622a, thereby more firmly wiping the developer.

[0103] (Positioning and integration of light guide member with developing container) Here, a method for positioning and integrating the light guide member 600 with the developer container 32 (developer container lid 321) will be described. Figures 17(a) and 17(b) are perspective views showing the light guide member 600 as a single component before being integrated with the developer container lid 321.

[0104] 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. The surfaces 3212a and 3212b face each other in the longitudinal direction LD and extend in the height direction ND. The 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 inside the developing container 32.

[0105] The height direction ND of the light guide member 600 is a direction perpendicular to the longitudinal direction LD and parallel to the mounting seat surface 3211. The height direction ND does not necessarily coincide with the direction of gravity WD in the posture when the light guide member 600 is integrated with the developing container 32 and assembled to the image forming apparatus 2 (the posture when detecting the amount of developer). In this embodiment, the light guide member 600 is inclined so that the height direction ND intersects with the direction of gravity WD at a small angle when viewed in the longitudinal direction LD ( FIG. 10( a) ). The light guide member 600 is inclined so that a lower portion of the light guide member 600 in the height direction ND is close to the center of rotation of the agitator 34 in the horizontal direction HD, and an upper portion of the light guide member 600 is farther from the center of rotation of the agitator 34 in the horizontal direction HD.

[0106] 17(a) and 17(b), the light guide member 600 has a first positioning rib 661 and a second positioning rib 662 on a 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 abuts against the mounting seat surface 3211.

[0107] The first positioning rib 661 includes a surface 661a for determining the position in the longitudinal direction LD and surfaces 661c and 661d for determining the position in the height direction ND. The second positioning rib 662 includes a surface 662b for determining the position in the longitudinal direction LD and surfaces 662c and 662d for determining the position in the height direction ND. The surfaces 3212a and 3212b of the developer container lid 321 engage with the surfaces 661a and 662b of the light guide member 600, thereby determining the position of the light guide member 600 in the longitudinal direction LD relative to the developer container lid 321. The surfaces 3212c and 3212d of the developer container lid 321 engage with the surfaces 661c, 662c, 661d, and 662d of the light guide member 600, thereby determining the position of the light guide member 600 in the height direction ND relative to the developer container lid 321.

[0108] The developing container lid 321 and the light guide member 600 are integrated by ultrasonically welding a director portion 670 provided on the light guide member 600 to the mounting seat surface 3211 of the developing container lid 321. The director portion 670 is a melting portion provided in a rectangular area surrounding the periphery of the opening 3212 of the developing container lid 321 (see also FIG. 15(b)). As described above, the developing container 32 is integrated by joining the developing container frame 320 and the developing container lid 321.

[0109] 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. As long as the light guide member 600 and the developing container lid 321 can be integrated without any gaps, they may be integrated using, for example, double-sided tape or an adhesive.

[0110] (Details of the upper part of the light-emitting side and the upper part of the light-receiving side) Next, the configurations of the inner upper portion 630 of the light-emitting side light guide 610 and the inner upper portion 640 of the light-receiving side light guide 620 in this embodiment will be described in detail. Figure 18 is a perspective view showing the back side of the light guide member 600 attached to the developer container lid 321, viewed from inside the transfer chamber 36 in which the developer is stored.

[0111] First, the inner upper portion 630 of the light-emitting side light guide 610 will be described. The inner upper portion 630 has a first side surface 630a extending upward from the light-emitting window 612a along the height direction ND and a second side surface 630b extending upward from the reflecting surface 612b along the height direction ND. The inner upper portion 630 also has an upper surface 630c (first upper surface) connecting the upper edges of the first side surface 630a and the second side surface 630b to the back surface 654 of the frame portion 650 (wall surface of the developing container 32). When viewed in the height direction ND, the upper surface 630c covers an area surrounded by the light-emitting window 612a, the reflecting surface 612b, and the back surface 654 of the frame portion 650. In other words, when viewed in a height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, the upper surface of the second protrusion covers an area surrounded by the wall surface, the first emission surface, and the first reflecting surface.

[0112] The upper surface 630c of the upper inner surface 630 is a surface that intersects with the direction of gravity WD and the height direction ND. In this embodiment, the upper surface 630c is perpendicular to the height direction ND or is slightly inclined with respect to the height direction ND as a draft angle during molding. The inclination direction is a direction that moves downward in the height direction ND as the distance from the back surface 654 of the frame portion 650 (wall surface of the developing container) increases in the protruding direction TD (protruding direction of the second protruding portion) of the inner light guiding portion 612 and the upper inner surface 630.

[0113] 16(b), when viewed in the longitudinal direction LD in the attitude during developer amount detection, the upper surface 630c of the inner upper part 630 is located above a first extension line EL1 of the upper surface 611c of the outer light-guiding portion 611 of the light-emitting side light-guiding body 610. The first extension line EL1 is a virtual line (first virtual line) drawn along the upper surface 611c of the outer light-guiding portion 611 when viewed in the longitudinal direction LD. Note that the light-emitting window 612a forming the optical path of the detection light OP is located below the first extension line EL1 when viewed in the longitudinal direction LD.

[0114] 16(b), the top surface 630c of the inner upper part 630 is located above the first imaginary line IL1 described above when viewed in the longitudinal direction LD in the attitude during developer amount detection. The top surface 630c is located above a horizontal plane perpendicular to the direction of gravity WD that passes through a boundary 611ct between the top surface 611c of the outer light guiding part 611 and the surface 653 of the frame part 650. As described above, the area above the first imaginary line IL1 is a part that does not substantially contribute to forming the optical path of the detection light OP.

[0115] Here, the outer light-guiding portion 611 of the light-emitting side light-guiding body 610 is formed in the shape of a quadrangular prism extending in the protruding direction TD or a truncated pyramid having a slight draft angle so that the cross-sectional area decreases toward the outside of the developing container 32 to improve mold releasability during molding. Therefore, inside the developing container 32, a first extension line EL1 of the upper surface 611c of the outer light-guiding portion 611 overlaps with the first imaginary line IL1 or is located above the first imaginary line IL1. Therefore, when viewed in the longitudinal direction LD in the attitude during developer amount detection, an upper surface 630c of the inner upper portion 630 of the light-emitting side light-guiding body 610 is located above the first extension line EL1 of the upper surface 611c of the outer light-guiding portion 611.

[0116] That is, in this embodiment, an inner upper portion 630 (first upper portion), which is not essentially necessary for forming an optical path of the detection light OP, is provided above the inner light guiding portion 612 (first lower portion) of the light-emitting side light guide 610. An upper surface 630c (first upper surface) of the inner upper portion 630 is located above a first extension line EL1 (first imaginary straight line) drawn along the upper surface 611c of the outer light guiding portion 611 of the light-emitting side light guide 610. In other words, when viewed in a direction intersecting both the protruding direction TD (first direction) of the outer light guiding portion 611 (first protruding portion) with respect to the wall surface of the developing container 32 and the direction of gravity WD, the upper surface 630c (first upper surface) of the inner upper portion 630 is located above the first extension line EL1 (first imaginary straight line). Here, the direction intersecting both the first direction and the direction of gravity WD is preferably a direction perpendicular to the direction of gravity WD and along the wall surface of the developing container 32 in which the light guiding member 600 is provided. In addition, the direction intersecting both the first direction and the direction of gravity WD is preferably a direction in which the inner light guiding portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and is the longitudinal direction LD of the developing container 32 in this embodiment.

[0117] Next, the upper inner surface 640 of the light-receiving side light guide 620 will be described. The upper inner surface 640 has a first side surface 640a extending upward from the light-receiving window 622a along the height direction ND and a second side surface 640b extending upward from the reflecting surface 622b along the height direction ND. The upper inner surface 640 also has an upper surface 640c (second upper surface) connecting the upper edges of the first side surface 640a and the 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 an area surrounded by the light-receiving window 622a, the reflecting surface 622b, and the back surface 654 of the frame portion 650. In other words, when viewed in a height direction perpendicular to the longitudinal direction and parallel to the wall surface of the container, the upper surface of the third protrusion covers an area surrounded by the wall surface, the second incident surface, and the second reflecting surface.

[0118] The upper surface 640c of the upper inner surface 640 is a surface that intersects with the direction of gravity WD and the height direction ND. In this embodiment, the upper surface 640c is perpendicular to the height direction ND or is slightly inclined with respect to the height direction ND as a draft angle during molding. The inclination direction is a direction that moves downward in the height direction ND as the distance from the back surface 654 of the frame portion 650 (wall surface of the developing container) increases in the protruding direction TD (protruding direction of the third protruding portion) of the inner light guiding portion 622 and the upper inner surface 640.

[0119] 16(c), when viewed in the longitudinal direction LD in the attitude during developer amount detection, the upper surface 640c of the inner upper part 640 is located above a second extension line EL2 of the upper surface 621c of the outer light guide 621 of the light-receiving side light guide 620. The second extension line EL2 is a virtual line (second virtual line) drawn along the upper surface 621c of the outer light guide 621 when viewed in the longitudinal direction LD. Note that the light-receiving window 622a forming the optical path of the detection light OP is located below the second extension line EL2 when viewed in the longitudinal direction LD.

[0120] 16(c), the top surface 640c of the inner upper part 640 is located above the second imaginary line IL1 described above when viewed in the longitudinal direction LD in the attitude during developer amount detection. The top surface 640c is located above a horizontal plane perpendicular to the direction of gravity WD that passes through a boundary 621ct between the top surface 621c of the outer light guiding part 621 and the surface 653 of the frame part 650. As described above, the area above the second imaginary line IL2 is a part that does not substantially contribute to forming the optical path of the detection light OP.

[0121] Here, the outer light guide portion 621 of the light-receiving side light guide 620 is formed in the shape of a quadrangular prism extending in the protruding direction TD, or in the shape of a truncated pyramid having a slight draft angle so that the cross-sectional area decreases toward the outside of the developer container 32 to improve mold releasability during molding. Therefore, inside the developer container 32, the second extension line EL2 of the upper surface 621c of the outer light guide portion 621 overlaps with the second imaginary line IL2 or is located above the second imaginary line IL2. Therefore, when viewed in the longitudinal direction LD in the attitude during developer amount detection, the upper surface 640c of the inner upper portion 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.

[0122] That is, in this embodiment, an inner upper portion 640 (second upper portion), which is not essentially necessary for forming an optical path of the detection light OP, is provided above the inner light guiding portion 622 (second lower portion) of the light-receiving side light guide 620. An upper surface 640c (second upper surface) of the inner upper portion 640 is located above a second extension line EL2 (second imaginary straight line) drawn along the upper surface 611c of the outer light guiding portion 611 of the light-receiving side light guide 620. In other words, when viewed in a direction intersecting both the protruding direction TD (second direction) of the outer light guiding portion 621 (fourth protruding portion) with respect to the wall surface of the developing container 32 and the direction of gravity WD, the upper surface 640c (second upper surface) of the inner upper portion 640 is located above the second extension line EL2 (second imaginary straight line). Here, the direction intersecting both the second direction and the direction of gravity WD is preferably a direction perpendicular to the direction of gravity WD and along the wall surface of the developing container 32 in which the light guiding member 600 is provided. In addition, the direction intersecting both the second direction and the direction of gravity WD is preferably a direction in which the inner light guiding portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and is the longitudinal direction LD of the developing container 32 in this embodiment.

[0123] (Advantages of this embodiment) When the developer in the conveying chamber 36 is agitated by the agitating member 34, gravity and inertial force cause the developer to accumulate on the upper surfaces 630c, 640c of the inner upper portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620. If the amount of accumulated developer increases, the developer may grow into clumps due to electrostatic forces and liquid bridging forces acting between developer particles, and the clumps may extend and adhere to the first side surfaces 630a, 640a of the inner upper portions 630, 640, for example.

[0124] In a conventional configuration in which the light-emitting side light guide 610 and the light-receiving side light guide 620 do not have their upper inner portions 630, 640, the upper surfaces of the inner light guides 612, 622 (the upward surfaces at the positions of the first imaginary line IL1 and the second imaginary line IL2) are exposed to the transfer chamber 36. In this configuration, agglomerates of developer that have accumulated and grown on the upper surfaces of the inner light guides 612, 622 may reach and adhere to the light-emitting window 612a or the light-receiving window 622a adjacent to the upper surfaces. In this case, the developer adhering to the light-emitting window 612a or the light-receiving window 622a may block the optical path of the detection light OP, potentially reducing the accuracy of developer amount detection.

[0125] In contrast, in this embodiment, the upper surface 630c of the inner upper portion 630 of the light-emitting light guide 610 is located above the first extension line EL1 of the upper surface 611c of the outer light guide 611 (FIG. 16(b)). Furthermore, the upper surface 640c of the inner upper portion 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 621 (FIG. 16(c)). Therefore, even if the developer accumulates on the upper surfaces 630c, 640c and grows as agglomerates, the agglomerates are less likely to reach the light-emitting window 612a or the light-receiving window 622a. As a result, the possibility that the light path of the detection light OP is blocked by the developer adhering to the light-emitting window 612a or the light-receiving window 622a is reduced.

[0126] Therefore, the configuration of this embodiment can suppress a decrease in the detection accuracy of the remaining toner amount sensor 500. That is, it is possible to reduce erroneous detection of the developer amount (decrease in detection accuracy) caused by developer unexpectedly blocking the light-emitting window 612a or the light-receiving window 622a, shortening the time during which the light-receiving element 510b receives the detection light OP (or reducing the intensity of the received light).

[0127] Furthermore, in this embodiment, the simple configuration in which the inner upper portions 630, 640 are integrally formed with the light-emitting side light guide 610 and the light-receiving side light guide 620 using the same material as the inner light guide portions 612, 622 can reduce erroneous detection of the developer amount.

[0128] Note that the greater the distance in the height direction ND between the upper surface 630c of the inner upper portion 630 of the light-emitting side light guide 610 and the light-emitting window 612a, the more unlikely it is that agglomerates of developer originating from the upper surface 630c will reach the light-emitting window 612a. Similarly, the greater the distance in the height direction ND between the upper surface 640c of the inner upper portion 640 of the light-receiving side light guide 620 and the light-receiving window 622a, the more unlikely it is that agglomerates 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 erroneous detection of the developer amount can be reduced.

[0129] Specifically, the height of the second protrusion at the position adjacent to the frame 650 is set to, for example, 120% or more, more preferably 150% or more, of the height of the first protrusion at the position adjacent to the frame 650 (see FIG. 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 guiding 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 guiding portion 611 to the upper surface 611c. When viewed in the longitudinal direction LD, it is preferable that the entire upper surface 630c of the inner upper portion 630 is spaced upward by at least 2 mm or more, more preferably 5 mm or more, from the first extension line EL1. This ensures a sufficient distance from the upper surface 630c to the upper edge of the light-emitting window 612a.

[0130] Similarly, the height of the third protrusion at a position adjacent to the frame 650 is set to, for example, 120% or more, more preferably 150% or more, of the height of the fourth protrusion at a position adjacent to the frame 650 (see FIG. 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 guiding 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 guiding portion 621 to the upper surface 621c. When viewed in the longitudinal direction LD, it is preferable that the entire upper surface 640c of the inner upper portion 640 be spaced upward by at least 2 mm or more, more preferably 5 mm or more, from the second extension line EL2. This ensures a sufficient distance from the upper surface 640c to the upper edge of the light receiving window 622a.

[0131] When determining the actual positions of the upper surfaces 630c, 640c of the inner upper portions 630, 640, it is only necessary to optimally design them in consideration of the cohesion characteristics of the developer, interference with other components, sink marks on the light guide member 600, and the like.

[0132] [Variations] Next, a modified example of the first embodiment will be described. Fig. 19 is a perspective view showing the back side of the light-guiding member 600 attached to the developer container lid 321 from inside the transfer chamber 36. As shown in Fig. 19, the upper inner portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 are formed as separate members from the inner light guides 612, 622, respectively, and are fixed to the inner light guides 612, 622. For example, a lower surface 630d of the upper inner portion 630 of the light-emitting side light guide 610 is joined to an upper surface 612c of the inner light guide 612 by an adhesive such as double-sided tape or adhesive. A lower surface 640d of the upper inner portion 640 of the light-receiving side light guide 620 is joined to an upper surface 622c of the inner light guide 622 by an adhesive such as double-sided tape or adhesive. The method of joining the inner upper portions 630, 640 and the inner light guiding portions 612, 622 is not limited to adhesive bonding, but may be mechanical joining such as snap fitting or welding such as ultrasonic welding.

[0133] Constructing the upper inner portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 as separate members from the inner light guides 612, 622 in this manner has the following advantages. Because the upper inner portions 630, 640 do not contribute to forming the optical path of the detection light OP, the light-guiding performance of the light-guiding member 600 is maintained even if the upper inner portions 630, 640 are formed separately from the other portions of the light-guiding member 600. Furthermore, in the first embodiment, the upper inner portions 630, 640 increase the thickness of the light-guiding member 600, so care must be taken to prevent sink marks from occurring during molding. However, in this modification, the occurrence of sink marks due to the increased thickness is suppressed. Therefore, this modification makes it possible to suppress the occurrence of sink marks when molding the portions of the light-guiding member 600 excluding the upper inner portions 630, 640 while maintaining the light-guiding performance of the light-guiding member 600.

[0134] Furthermore, the upper inner portions 630, 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 guides 612, 622. The upper inner portions 630, 640 can be made of a material that is less transparent to the detection light OP than the inner light guides 612, 622 (for example, a matte black polyethylene resin or polypropylene resin). Alternatively, a black paint that blocks the detection light OP may be applied to the surfaces of the upper inner portions 630, 640 that are made of the same material as the inner light guides 612, 622. This reduces stray light that passes through the upper inner portions 630, 640, and prevents erroneous detection of the developer amount due to stray light.

[0135] Second Embodiment A second embodiment of the present disclosure will be described. This embodiment differs from the first embodiment in the positional relationship between the inner upper portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 and the inner light guides 612, 622. The rest of the configuration of the image forming apparatus 1 and the process unit 20 is the same as in the first embodiment. Below, elements with the same reference numerals as in the first embodiment have substantially the same configuration and function as those described in the first embodiment, and differences from the first embodiment will be mainly described.

[0136] 20 is a perspective view showing the back side of the light-guiding member 600 attached to the developing container lid 321 from inside the transfer chamber 36. As shown in Fig. 20, a slit 615 (first slit) is provided between the inner upper part 630 of the light-emitting side light-guiding body 610 and the inner light-guiding portion 612, and a slit 625 (second slit) is provided between the inner upper part 640 of the light-receiving side light-guiding body 620 and the inner light-guiding portion 622.

[0137] These slits 615, 625 extend in a direction intersecting the direction of gravity WD when the process unit 20 is inside the printer main body 100, i.e., in the position during developer amount detection (see FIG. 12). The slit 615 is a first space formed between a lower surface 630d of an inner upper part 630 (first upper part) of the light-emitting side light guide 610 and an upper surface 612c of the inner light guide 612 (first lower part). The slit 625 is a second space formed between a lower surface 640d of an inner upper part 640 (second upper part) of the light-receiving side light guide 620 and an upper surface 622c of the inner light guide 622 (second lower part).

[0138] The slit 615 separates the inner light-guiding portion 612 and the upper inner portion 630 of the light-emitting side light-guiding body 610, thereby suppressing stray light of the detection light OP traveling from the inner light-guiding portion 612 through the upper inner portion 630 and finally to the light-receiving element 510b. Similarly, the slit 625 separates the inner light-guiding portion 622 and the upper inner portion 640 of the light-receiving side light-guiding body 620, thereby suppressing stray light of the detection light OP traveling from the upper inner portion 640 through the inner light-guiding portion 622 and finally to the light-receiving element 510b.

[0139] The lower surface 630d of the inner upper portion 630 of the light-emitting side light guide 610 and the upper surface 612c of the inner light guide 612 do not necessarily need to be parallel to each other. In this embodiment, the lower surface 630d of the inner upper portion 630 and the upper surface 612c of the inner light guide 612 are inclined relative to each other due to a draft angle during molding. That is, when viewed in the longitudinal direction LD, the distance in the height direction ND between the lower surface 630d of the inner upper portion 630 and the upper surface 612c of the inner light guide 612 increases with increasing distance from the back surface 654 of the frame 650 in the direction in which the inner upper portion 630 and the inner light guide 612 protrude relative to the frame 650. Similarly, the lower surface 640d of the inner upper portion 640 of the light-receiving side light guide 620 and the upper surface 622c of the inner light guide 622 do not necessarily need to be parallel to each other. In this embodiment, the lower surface 640d of the inner upper portion 640 and the upper surface 622c of the inner light guiding portion 622 are inclined relative to each other due to a draft angle created during molding.

[0140] It is preferable that the width of the slits 615, 625 is narrow in order to prevent the growth of agglomerates originating from the developer that has entered the slits 615, 625 and adhering to the light-emitting window 612a and the light-receiving window 622a. In this embodiment, the minimum width of the slits 615, 625 (the width at a position adjacent to the back surface 654 of the frame portion 650) is designed to be nominally 1 mm, taking into consideration moldability (mold releasability) due to the draft angle during molding. However, the present invention is not limited to this, and the width of the slits 615, 625 may be set wider in consideration of moldability, for example, if a developer that is less likely to aggregate is used.

[0141] In this embodiment, too, the upper surface 630c of the inner upper portion 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 attitude during developer amount detection. The upper surface 640c of the inner upper portion 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 attitude during developer amount detection. Therefore, as in the first embodiment, it is possible to reduce the possibility that developer aggregates will grow from the upper surfaces 612c, 622c of the inner light guides 612, 622 and reach the light-emitting window 612a or the light-receiving window 622a. This reduces erroneous detection of the developer amount by the toner remaining amount sensor 500 (deterioration in detection accuracy).

[0142] In addition, according to this embodiment, by providing the slits 615, 625 between the inner light guiding portions 612, 622 and the inner upper portions 630, 622, it is possible to suppress erroneous detection of the developer amount due to stray light.

[0143] As in the modified example described in the first embodiment, the upper inner portion 630 of the light-emitting side light guide 610 may be formed as a separate member from the inner light guide 612, and the upper inner portion 640 of the light-receiving side light guide 620 may be formed as a separate member from the inner light guide 622. This modified example makes it possible to prevent sink marks from occurring when molding the portions of the light guide member 600 excluding the upper inner portions 630 and 640, while maintaining the light guide performance of the light guide member 600. Furthermore, by using a material for the upper inner portions 630 and 640 that is less transparent to the detection light OP than the inner light guides 612 and 622, it is possible to further prevent erroneous detection of the developer amount due to stray light.

[0144] <Third embodiment> A third embodiment of the present disclosure will be described. This embodiment differs from the second embodiment in the shapes of the upper inner portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620. The rest of the configuration of the image forming apparatus 1 and the process unit 20 is the same as in the first and second embodiments. Hereinafter, elements with the same reference numerals as in the first and second embodiments will be considered to have substantially the same configurations and functions as those described in the first and second embodiments, and differences from the first and second embodiments will be mainly described.

[0145] FIG. 21 is a perspective view of the back side of the light guide member 600 attached to the developer container lid 321 from inside the transfer chamber 36. FIGS. 22(a) to 22(c) are views showing the light guide member 600 as a single component. FIG. 22(a) is a front view of the light guide member 600. FIG. 22(b) is an enlarged view of region B on the light-emitting side in FIG. 22(a). FIG. 22(c) is an enlarged view of region C on the light-receiving side in FIG. 22(a). FIGS. 23(a) to 23(c) are views showing the light guide member 600 from three directions using the third angle projection method. FIG. 23(a) is a front view of the back side of the light guide member 600, FIG. 23(b) is a side view of the light-emitting element 510a side in the longitudinal direction LD, and FIG. 23(c) is a side view of the light-receiving element 510b side in the longitudinal direction LD.

[0146] As shown in FIG. 21, the upper inner portion 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 reflecting surface 612b. The upper inner portion 630 also has a top 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 of the frame portion 650 in the normal direction (projection direction TD) of the installation surface 680. The top surface 631c is a surface that extends in a direction intersecting with the direction of gravity in the orientation during developer amount detection (see FIG. 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.

[0147] 22(b), the first side surface 631a and the end surface 631e are offset toward the base side (upper side in the figure) in the protruding direction TD of the inner light-guiding portion 612 so as not to protrude beyond 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 interfering with wiping of the light-emitting window 612a by the wiping portion 34c of the agitating member 34 described above.

[0148] Furthermore, damage such as tearing of the sheet can be suppressed by end surface 630e coming into surface contact with a flexible sheet such as first blade portion 34b1 and second blade portion 34b2 of agitator 34. Note that the rib portion forming second side surface 631b is intended to increase the surface area of ​​end surface 631e, and for example, if a thick, tear-resistant sheet material is used for blade portion 34b of agitator 34, end surface 631e and second side surface 631b may be omitted.

[0149] The upper surface 631c includes an inclined surface 631s that is inclined downward in the direction of gravity toward the tip end of the upper inner surface 630 in the protruding direction TD. Furthermore, the inclination angle of the inclined surface 631s is designed so that the angle formed with the horizontal plane is equal to or greater than the angle of repose of the developer when the upper inner surface 630 is in the position at the time of developer amount detection (see FIG. 12). By forming at least a portion of the upper surface 631c as an inclined surface inclined with respect to the horizontal plane, it is possible to suppress the accumulation of developer on the upper surface 631c of the upper inner surface 630. Therefore, the upper surface 630c of the upper inner surface 630 in the first and second embodiments may be inclined like the inclined surface 631s of this embodiment. The first side surface 631a and the second side surface 631b form larger angles with the horizontal plane than the upper surface 631c.

[0150] Also, as shown in Figure 23(b), the upper surface 631c of the inner upper portion 630 is located above the first extension line EL1 of the upper surface 611c of the outer light-guiding portion 611 of the light-emitting side light guide 610 when viewed in the longitudinal direction LD in the attitude when detecting the developer amount.

[0151] As shown in FIG. 21, the upper inner portion 640 of the light-receiving side 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 reflecting surface 622b. The upper inner portion 640 also has a top surface 641c (first upward surface) located above the first and second side surfaces 641a and 641b, and an end surface 641e (second end surface) provided at the tip of the frame 650 in the normal direction (projection direction TD) of the installation surface 680. The top surface 641c is a surface extending in a direction intersecting with the direction of gravity in the orientation during developer amount detection (see FIG. 12). The end surface 641e is adjacent to the first and second side surfaces 641a and 641b, respectively, and is provided between the first and second side surfaces 641a and 641b in the longitudinal direction LD.

[0152] 22(c), the first side surface 641a and the end surface 641e are offset toward the base side (upper side in the figure) in the protruding direction TD of the inner light guiding portion 622 so as not to protrude beyond 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 interfering with wiping of the light receiving window 622a by the wiping portion 34c of the agitating member 34 described above.

[0153] Furthermore, damage such as tearing of the sheet can be suppressed by end surface 640e coming into surface contact with a flexible sheet such as first blade portion 34b1 and second blade portion 34b2 of agitator 34. Note that the rib portion forming second side surface 641b is intended to increase the surface area of ​​end surface 641e, and for example, when a thick, tear-resistant sheet material is used for blade portion 34b of agitator 34, end surface 641e and second side surface 641b may be omitted.

[0154] The upper surface 641c includes an inclined surface 641s that is inclined downward in the direction of gravity toward the tip end of the upper inner surface 640 in the protruding direction TD. Furthermore, the inclination angle of the inclined surface 641s is designed so that the angle formed with the horizontal plane is equal to or greater than the angle of repose of the developer when the upper inner surface 641c is in the position during developer amount detection (see FIG. 12). By forming at least a portion of the upper surface 641c as an inclined surface inclined with respect to the horizontal plane, it is possible to suppress the accumulation of developer on the upper surface 641c of the upper inner surface 640. Therefore, the upper surface 640c of the upper inner surface 640 in the first and second embodiments may be inclined like the inclined surface 641s of this embodiment. The first side surface 641a and the second side surface 641b form larger angles with the horizontal plane than the upper surface 641c.

[0155] Also, as shown in Figure 23(c), the upper surface 641c of the inner upper portion 640 is located above the second extension line EL2 of the upper surface 621c of the outer light-guiding portion 621 of the light-receiving side light guide 620 when viewed in the longitudinal direction LD in the attitude when detecting the developer amount.

[0156] Note that, because the angle of repose varies depending on the developer, the angle of inclination of the inclined surfaces 631s, 641s provided on the upper surfaces 631c, 641c of the inner upper portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 can be changed as appropriate to suit the characteristics of the developer. Even if the angle of inclination of the inclined surfaces 631s, 641s is less than the angle of repose, the effect of suppressing accumulation of developer can be obtained as long as the angle between the inclined surfaces 631s, 641s and the horizontal plane is at least larger than the angle between the upper surfaces 612c, 622c of the inner light guides 612, 622 and the horizontal plane.

[0157] In this embodiment, too, the upper surface 631c of the inner upper portion 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 attitude during developer amount detection. The upper surface 641c of the inner upper portion 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 attitude during developer amount detection. Therefore, as in the first embodiment, it is possible to reduce the possibility that developer aggregates will grow from the upper surfaces 612c, 622c of the inner light guides 612, 622 and reach the light-emitting window 612a or the light-receiving window 622a. This reduces erroneous detection of the developer amount by the toner remaining amount sensor 500 (deterioration in detection accuracy).

[0158] In addition, according to this embodiment, the inclined surfaces 631s, 641s are provided on the upper surfaces 631c, 641c of the inner upper portions 630, 640, so that accumulation of developer on the upper surfaces 631c, 641c can be suppressed, thereby further suppressing erroneous detection of the developer amount by the remaining toner amount sensor 500.

[0159] Furthermore, end faces 631e, 641e are provided at the tips of the inner upper portions 630, 640 with which the first blade portion 34b1 and the second blade portion 34b2 of the agitator 34 made of sheet material come into surface contact, thereby preventing damage such as tearing of the sheet material.

[0160] As in the modified example described in the first embodiment, the upper inner portion 630 of the light-emitting side light guide 610 may be formed as a separate member from the inner light guide 612, and the upper inner portion 640 of the light-receiving side light guide 620 may be formed as a separate member from the inner light guide 622. This modified example makes it possible to prevent sink marks from occurring when molding the portions of the light guide member 600 excluding the upper inner portions 630 and 640, while maintaining the light guide performance of the light guide member 600. Furthermore, by using a material for the upper inner portions 630 and 640 that is less transparent to the detection light OP than the inner light guides 612 and 622, it is possible to further prevent erroneous detection of the developer amount due to stray light.

[0161] <Fourth embodiment> A fourth embodiment of the present disclosure will be described. In this embodiment, the shape of a portion 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 the process unit 20 are the same as those of the first to third embodiments. Hereinafter, elements that are given the same reference numerals as those of the first to third embodiments have substantially the same configurations and functions as those described in the first to third embodiments, and differences from the first to third embodiments will be mainly described.

[0162] In the configuration of the remaining toner amount sensor 500 described in the first to third embodiments, a portion of the detection light OP emitted from the light-emitting element 510a may enter the light-guiding member 600 from a point other than the incident surface 611a of the light-guiding member 600. Such light may reach the light-receiving element 510b as stray light that travels a path different from the designed light path illustrated in, for example, FIGS. 15(a) to 16(d). If the amount of stray light that reaches the light-receiving element 510b is large, the transmitted time of the light may be detected as longer than expected, and this may result in erroneous detection of the developer amount.

[0163] 24 is a view of the light guide member 600 attached to the developer container 32 as viewed from the outside of the developer container 32 (developer container lid 321). As shown in FIG. 24, a frame portion 650 of the light guide member 600 includes a flat portion 651 and a retracted portion 655.

[0164] The flat surface portion 651 has a flat plate shape extending in the longitudinal direction LD and the height direction ND. The flat surface portion 651 has a front surface 651s and four side surfaces (a first side surface 651a, a second side surface 651b, a third side surface 651c, and a fourth side surface 651d) whose corners are connected by curved surfaces as surfaces exposed to the outside of the developing container 32. The first side surface 651a and the second side surface 651b are both end portions of the flat surface portion 651 in the longitudinal direction LD, and the third side surface 651c and the fourth side surface 651d are both end portions of the flat surface portion 651 in the height direction ND.

[0165] The retracted portions 655 are provided on the inside of the four side surfaces of the flat portion 651 and have a concave shape recessed (retracted) toward the outside of the developing container 32 relative to the flat portion 651. The retracted portions 655 form a space into which the wiping portion 34c of the agitating member 34 can enter when wiping the light-emitting window 612a and the light-receiving window 622a with the wiping portion 34c. The retracted portion 655 has a front-side retracted surface 655s and front-side side surfaces 655a and 655b as surfaces exposed to the outside of the developing container 32. The front-side retracted surface 655s is a surface that curves convexly toward the outside of the developing container 32 when viewed in the longitudinal direction LD. The front-side side surfaces 655a and 655b are surfaces that rise from the front surface 651s of the flat portion 651 toward the outside of the developing container 32 and are connected to both ends of the front-side retracted surface 655s in the longitudinal direction LD.

[0166] The surface plane 651s and the surface retraction surface 655s are subjected to a roughening treatment (roughening treatment) with a ten-point mean roughness of 20 μm or more. This roughening treatment diffuses and diffuses the detection light OP emitted from the light-emitting element 510a when it is incident on the surface plane 651s and the surface retraction surface 655s. Therefore, the amount of stray light of the detection light OP emitted from the light-emitting element 510a that penetrates the light-guiding member 600 from the surface plane 651s and the surface retraction surface 655s and reaches the light-receiving element 510b can be reduced. This reduces erroneous detection of the developer amount (decreased detection accuracy) due to stray light. Note that a similar effect can be expected if the surface roughness (ten-point mean roughness) of at least a portion of the surface of the light-guiding member 600 exposed to the outside of the developer container 32, excluding the first and fourth protruding portions, is configured to be greater than the surface roughness of the first and fourth protruding portions.

[0167] In this embodiment, the side surfaces (651a to 651d, 655a, 655b) of the light-guiding member 600 parallel to the die-cutting direction (normal direction of the installation surface 680, protruding direction TD) are not textured in consideration of moldability (mold releasability). The light-emitting side light guide 610 and the light-receiving side light guide 620 are mirror-finished with a maximum height of 0.2 μm or less to minimize loss of the detection light OP due to refraction and reflection. In this manner, the exposed portions of the light-guiding member 600, the light-emitting side light guide 610 and the light-receiving side light guide 620 for guiding the detection light OP, have smooth surfaces, while the remaining portions have as rough surfaces as possible in consideration of moldability. This configuration suppresses attenuation of the detection light OP passing through the designed optical path while preventing erroneous detection of the developer amount due to stray light (deterioration in detection accuracy).

[0168] Regarding the actual value of the surface roughness, if the roughness of the surfaces other than the light-emitting side light guide 610 and the light-receiving side light guide 620 is set to be rougher than the surfaces of the light-emitting side light guide 610 and the light-receiving side light guide 620, the effect of suppressing false detection due to stray light caused by the detection light OP can be obtained, although to varying degrees. The setting of the roughness (smoothness) of each surface of the light-guiding member 600 is changed as appropriate depending on the specific configuration, such as the light intensity of the LED serving as the light-emitting element 510a and the sensitivity of the phototransistor serving as the light-receiving element 510b.

[0169] The configuration of the surface of the light-guiding member 600 that is exposed to the outside of the developing container 32, described in this embodiment, can be implemented in combination with the inner upper portions 630, 640 of the light-emitting side light guide 610 and the light-receiving side light guide 620 described in the first to third embodiments. Therefore, by providing the inner upper portions 630, 640, it is possible to suppress erroneous detection of the developer amount by the toner remaining amount sensor 500 (reduction in detection accuracy), while further reducing erroneous detection by the uneven surface treatment of the front flat surface 651s and the front retraction surface 655s.

[0170] Fifth Embodiment A fifth embodiment of the present disclosure will be described. This embodiment differs from the first to fourth embodiments in the shapes of the light-emitting side light guide 610 and the outer light guide portions 611, 621 of the light-receiving side light guide 620 of the light-guiding member 600, and in the optical path design of the remaining toner amount sensor 500. The rest of the configuration of the image forming apparatus 1 and the process unit 20 is the same as in the first to fourth embodiments. Below, elements with the same reference numerals as in the first to fourth embodiments have substantially the same configurations and functions as those described in the first to fourth embodiments, and differences from the first to fourth embodiments will be mainly described.

[0171] 25(a) and 25(b) are perspective views showing the light guide member 600 as a single component before being integrated with the developer container lid 321. FIG. 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 in the developer container 32 and is exposed to the outside of the developer container 32. FIG. 25(b) shows the back side of the light guide member 600, i.e., the side that comes into contact with the developer in the developer container 32 and is exposed to the inside of the developer container 32.

[0172] 26(a) to 26(f) are views showing the light-guiding member 600 and the detection light OP from six directions by third-angle projection, with the back side of the light-guiding member 600 as the front. However, due to space limitations, the back view (f) is placed below the bottom view (e). FIG. 26(a) is a front view showing the back side of the light-guiding member 600. FIG. 26(b) is a side view of the light-guiding member 600 as seen from the light-emitting element 510a side in the longitudinal direction LD. FIG. 26(c) is a side view of the light-guiding member 600 as seen from the light-receiving element 510b side in the longitudinal direction LD. FIG. 26(d) is a plan view of the light-guiding member 600 as seen from above in the height direction ND. FIG. 26(e) is a bottom view of the light-guiding member 600 as seen from below in the height direction ND. FIG. 26(f) is a back view showing the back side of the light-guiding member 600.

[0173] Fig. 27(a) is a cross-sectional view of the light-guiding member 600 taken along a plane that passes through the light-emitting side light guide 610 and is perpendicular to the longitudinal direction LD, along the cutting line AA shown in Fig. 26(a, f). Fig. 27(b) is a cross-sectional view of the light-guiding member 600 taken along a plane that passes through the light-receiving side light guide 620 and is perpendicular to the longitudinal direction LD, along the cutting line BB shown in Fig. 26(a, f).

[0174] The detection light OP shown in each of FIGS. 25(a) to 27(b) indicates a representative optical path (optical axis) of light emitted from the above-mentioned light-emitting element 510a, passing through the light-guiding member 600, and reaching the light-receiving element 510b.

[0175] In the first to fourth embodiments, the incident surface 611a of the outer light guiding portion 611 of the light-emitting side light guide 610 and the exit surface 621a of the outer light guiding portion 621 of the light-receiving side light guide 620 are provided at the tip portions of the outer light guiding portions 611, 621 in the protruding direction TD of the outer light guiding portions 611, 621. In contrast, the outer light guiding portions 611, 621 of the present embodiment extend in a direction along the flat portion 651 of the frame portion 650.

[0176] 25(a) and 26(a-f), the outer light-guiding portion 611 of the light-emitting side light-guiding body 610 is formed in a prismatic shape extending in a first extension direction D1 (first direction) along a surface 653 (front surface 651s) of the frame portion 650. The outer light-guiding portion 611 has a side surface portion 611d extending in the first extension direction D1, an incident surface 611a provided at one end of the side surface portion 611d in the first extension direction D1, and a reflecting surface 611b provided at the other end of the side surface portion 611d in the first extension direction D1.

[0177] The incident surface 611a is a surface onto which light from the light-emitting element 510a is incident. The light-emitting element 510a of this embodiment is disposed to face the incident surface 611a (FIG. 27(a)). The incident surface 611a is formed in a convex lens shape so as to convert the diffused light emitted from the light-emitting element 510a into a substantially parallel beam of light in the first extension direction D1 of the outer light-guiding section 611.

[0178] The reflecting surface 611b as the first reflecting surface is a surface that reflects (specularly reflects) the detection light OP that is incident on the incident surface 611a and travels inside the outer light-guiding portion 611 in the first extension direction D1 toward the inner light-guiding portion 612 (FIG. 27(a)). As an example, in a cross section perpendicular to the longitudinal direction LD (FIG. 27(a)), the angle that the reflecting surface 611b forms with respect to the first extension direction D1 (the direction along the front surface 651s of the frame portion 650) is 45°.

[0179] The side surface portion 611d as the first side surface portion has three surfaces that form a U-shape 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 surface portion 611d, two surfaces that face each other in the longitudinal direction LD may be provided with a draft angle during molding. In this case, the cross section of the outer light guiding unit 611 perpendicular to the first extension direction D1 has a trapezoidal shape in which the side opposite the frame portion 650 is slightly shorter than the side that contacts the frame portion 650.

[0180] 25(a) and 26(a-f), the outer light-guiding 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 (front surface 651s) of the frame portion 650. The outer light-guiding portion 621 has a side surface portion 621d extending in the second extension direction D2, an emission surface 621a provided at one end of the side surface portion 621d in the second extension direction D2, and a reflection surface 621b provided at the other end of the side surface portion 621d in the second extension direction D2.

[0181] The exit surface 621a is a surface that emits, toward the light receiving element 510b, the detection light OP that has entered the inner light guiding part 622 via the spatial optical path Q in the transfer chamber 36. The light receiving element 510b in this embodiment is disposed to face the exit surface 621a (FIG. 27(b)).

[0182] The reflecting surface 621b as the second reflecting surface is a surface that reflects (specularly reflects) the detection light OP that enters the inner light-guiding portion 622 and travels inside the light-receiving side light-guiding body 620 from the inner light-guiding portion 622 toward the outer light-guiding portion 621, in the second extension direction D2 (FIG. 27(b)). As an example, in a cross section perpendicular to the longitudinal direction LD (FIG. 27(b)), the angle that the reflecting surface 621b forms with the second extension direction D2 (the direction along the front surface 651s of the frame portion 650) is 45°.

[0183] The side surface portion 621d as the second side surface portion has three surfaces that form a U-shape in a cross section perpendicular to the second extension direction D2, and these three surfaces and the frame portion 650 form a substantially square cross section. Of the three surfaces of the side surface portion 621d, two surfaces that face each other in the longitudinal direction LD may be provided with a draft angle during molding. In this case, the cross section of the outer light guiding unit 611 perpendicular to the second extension direction D2 has a trapezoidal shape in which the side opposite the frame portion 650 is slightly shorter than the side that contacts the frame portion 650.

[0184] (Positional relationship between the reflective surface of the outer light guide and the upper inner surface) In the first to fourth embodiments, the incident surface 611a into which light from the light emitting element 510a is incident and the exit surface 621a that emits light toward the light receiving element 510b are provided at the tip ends of the outer light guides 611, 612 in the protruding direction TD. It has been described that erroneous detection of the developer amount can be reduced by arranging the upper surfaces 630c, 640c of the inner upper parts 630, 640 above the extension lines (EL1, EL2 in FIGS. 16(b) and 16(c)) of the upper surfaces 611c, 621c of the outer light guides 611, 612.

[0185] In contrast, the outer light-guiding section 611 of the light-emitting side light guide 610 of this embodiment is configured so that light incident on the incident surface 611a travels inside the outer light-guiding section 611 in the first extension direction D1 and is reflected by the reflecting surface 611b to be guided toward the inner light-guiding section 612. Similarly, the outer light-guiding section 621 of the light-receiving side light guide 620 of this embodiment is configured so that light traveling from the inner light-guiding section 622 to the outer light-guiding section 621 is reflected by the reflecting surface 621b to be guided in the second extension direction D2 toward the exit surface 621a.

[0186] In this configuration, it can be said that a region of the second protrusion of the light-guiding member 600 through which the light flux reflected by the reflecting surface 611b of the first protrusion (outer light-guiding member 611) passes is a portion that substantially constitutes the optical path of the detection light OP. Similarly, it can be said that a region of the third protrusion of the light-guiding member 600 through which the light flux reflected by the reflecting surface 621b passes when traveling from the third protrusion to the fourth protrusion (outer light-guiding member 611) is a portion that substantially constitutes the optical path of the detection light OP.

[0187] Therefore, in this embodiment, the upper surface of the second protrusion of the light-emitting side light guide 610 is disposed above a line (IL3) that passes through an upper end 611bt of the reflecting surface 611b of the outer light guide 611 and extends in a light reflection direction D3 at the reflecting surface 611b. Also, in this embodiment, the upper surface of the third protrusion of the light-receiving side light guide 620 is disposed above a line (IL4) that passes through an upper end 621bt of the reflecting surface 621b of the outer light guide 621 and extends in a light incident direction D4 to the reflecting surface 621b.

[0188] 27(a) is a line passing through an upper end 611bt of the reflecting surface 611b in the gravity direction WD, and is a line drawn in a reflection direction D3 when light in the first extension direction D1 is specularly reflected by the reflecting surface 611b. A portion of the second protrusion of the light-guiding member 600 below the imaginary line IL3 is an inner light-guiding portion 612 that forms the optical path of the detection light OP. A portion of the second protrusion of the light-guiding member 600 above the imaginary line IL3 is an inner upper portion 630 that does not contribute to forming the optical path of the detection light OP. An upper surface 630c of the inner upper portion 630 is located above the imaginary line IL3 (first imaginary line) when viewed in the longitudinal direction LD. In other words, when viewed in a direction intersecting both the direction of gravity WD and a first extension direction D1 (first direction) in which the outer light guiding 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 an imaginary line IL3 (first imaginary line). Here, the direction intersecting both the first direction and the direction of gravity WD is preferably a direction orthogonal to the direction of gravity WD and along the wall surface of the developing container 32 in which the light guiding member 600 is provided. Furthermore, the direction intersecting both the first direction and the direction of gravity WD is preferably a direction in which the inner light guiding portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, is the longitudinal direction LD of the developing container 32.

[0189] 27(b) is a line passing through an upper end 621bt of the reflecting surface 621b in the gravity direction WD, and is a line drawn in the incident direction D4 of incident light when incident light incident on the reflecting surface 621b is specularly reflected in the second extension direction D2. Of the third protrusion of the light-guiding member 600, a portion below the imaginary line IL4 is an inner light-guiding portion 622 that forms the optical path of the detection light OP. Of the third protrusion of the light-guiding member 600, a portion above the imaginary line IL4 is an inner upper portion 640 that does not contribute to forming the optical path of the detection light OP. An upper surface 640c of the inner upper portion 640 is located above the imaginary line IL4 (second imaginary line) when viewed in the longitudinal direction LD. In other words, when viewed in a direction intersecting both the second extension direction D2 (second direction) in which the outer light guiding portion 621 (fourth protrusion) extends along the wall surface of the developing container 32 and the direction of gravity WD, the upper surface 640c (second upper surface) of the inner upper portion 640 is located above the imaginary line IL4 (second imaginary line). Here, the direction intersecting both the second direction and the direction of gravity WD is preferably a direction orthogonal to the direction of gravity WD and along the wall surface of the developing container 32 in which the light guiding member 600 is provided. Furthermore, the direction intersecting both the second direction and the direction of gravity WD is preferably a direction in which the inner light guiding portions 612, 622 (second protrusion, third protrusion) face each other inside the developing container 32, and in this embodiment, is the longitudinal direction LD of the developing container 32.

[0190] As described above, although the optical path design of the outer light-guiding sections 611, 621 in this embodiment differs from that of the first to fourth embodiments, the inner upper sections 630, 640 are provided above the inner light-guiding sections 612, 622, and the upper surfaces 630c, 640c are positioned above the imaginary straight lines IL3, IL4.

[0191] That is, when viewed in the longitudinal direction LD of the developing container 32, the upper surface 630c of the second protrusion of the light guide member 600 is located above an imaginary line IL3 (first imaginary line) that is a line passing through an upper end of the reflecting surface 611b (first reflecting surface) and that is drawn in a reflection direction D3 when light in the first extension direction D1 (first direction) is incident on the first reflecting surface and reflected therefrom. Furthermore, when viewed in the longitudinal direction LD of the developing container 32, the upper surface 640c of the third protrusion of the light guide member 600 is located above an imaginary line IL4 (second imaginary line) that is a line passing through an upper end of the reflecting surface 621b (second reflecting surface) and that is drawn in an incident direction D4 when light that is incident on the second reflecting surface is reflected in the second extension direction D2 (second direction).

[0192] With this configuration, even if developer accumulates on the upper surfaces 630c, 640c of the inner upper portions 630, 640 in the attitude at the time of developer amount detection, it is possible to make it difficult for clumps of developer to reach the light-emitting window 612a or the light-receiving window 622a of the inner light-guiding portions 612, 622. In other words, with the configuration of this embodiment, adhesion of developer to the light-emitting window 612a or the light-receiving window 622a is reduced, and erroneous detection of the developer amount by the toner remaining amount sensor 500 (deterioration in detection accuracy) can be suppressed.

[0193] In the present embodiment, the outer light guides 611, 621 are described as extending in directions substantially parallel to the height direction ND. However, the outer light guides 611, 621 may extend in other directions. The extension directions of the outer light guides 611, 621 may be changed as appropriate in relation to the arrangement of the light-emitting elements 510a and the light-receiving elements 510b in the image forming apparatus. For example, the outer light guide 611 of the light-emitting side light guide 610 may extend on one side of the longitudinal direction LD, and the outer light guide 621 of the light-receiving side light guide 620 may extend on the other side of the longitudinal direction LD. In this case, the reflecting surface 611b of the outer light guide 611 of the light-emitting side light guide 610 is disposed so as to reflect, toward the inner light guide 612, light traveling from the incident surface 611a through the interior of the outer light guide 611 in the longitudinal direction LD, which is defined as a first direction. In addition, the reflecting surface 621b of the outer light-guiding portion 621 of the light-receiving side light guide 620 is positioned so as to reflect light that has traveled from the inner light-guiding portion 622 to the outer light-guiding portion 611 toward the exit surface 621a along the longitudinal direction LD as the second direction.

[0194] Even if the extension direction (first direction) of the outer light guide 611 (first protrusion) of the light-emitting side light guide 610 is different from that of this embodiment, the upper surface of the second protrusion may be disposed above the first imaginary line as viewed in the longitudinal direction LD. This first imaginary line is a line passing through the upper end of the reflecting surface (first reflecting surface) of the outer light guide 611 and is an imaginary line drawn in the reflection direction when light in the first direction is incident on the first reflecting surface and reflected therefrom. Similarly, even if the extension direction (second direction) of the outer light guide 621 (fourth protrusion) of the light-receiving side light guide 620 is different from that of this embodiment, the upper surface of the third protrusion may be disposed above the second imaginary line as viewed in the longitudinal direction LD. This second imaginary line is a line passing through the upper end of the reflecting surface (second reflecting surface) of the outer light guide 621 and is an imaginary line drawn in the incident direction when light incident on the second reflecting surface is reflected in the second direction. This makes it possible to prevent erroneous detection of the developer amount (reduction in detection accuracy) in the same way as in this embodiment.

[0195] As in the modified example described in the first embodiment, the upper inner portion 630 of the light-emitting side light guide 610 may be formed as a separate member from the inner light guide 612, and the upper inner portion 640 of the light-receiving side light guide 620 may be formed as a separate member from the inner light guide 622. This modified example makes it possible to prevent sink marks from occurring when molding the portions of the light guide member 600 excluding the upper inner portions 630 and 640, while maintaining the light guide performance of the light guide member 600. Furthermore, by using a material for the upper inner portions 630 and 640 that is less transparent to the detection light OP than the inner light guides 612 and 622, it is possible to further prevent erroneous detection of the developer amount due to stray light.

[0196] Furthermore, the inner upper portions 630, 640 in this embodiment may be replaced with the configuration of the inner upper portions 630, 640 described in the second and third embodiments, and the uneven surface treatment described in the fourth embodiment may be applied to the frame portion 650 of this embodiment.

[0197] <Other embodiments> In the above-described embodiment, the light-emitting element 510a and the light-receiving element 510b are disposed in the process unit 20, but the light-emitting element 510a and the light-receiving element 510b may be disposed, for example, in the printer body 100 of the image forming apparatus 1. Also, in the above-described embodiment, the substrate holding member 710 is provided between the developing container lid 321 and the substrate 700, but the holding configuration for the substrate 700 is not limited to this. In other words, the substrate 700 may be attached directly to the developing container lid 321 without providing the substrate holding member 710.

[0198] In the above-described embodiment, the light-emitting side light guide 610 and the light-receiving side light guide 620 are configured as an integrally molded member via the frame portion 650, but the present 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 members, and each may be attached to the developing container 32.

[0199] In the above-described embodiment, the spatial light path Q is arranged so as to overlap with the rotation loci Tb1 and Tb2 of the stirring member 34 when viewed in the axial direction of the stirring member 34, but this is not limiting. In other words, the spatial light path Q may be arranged so as not to overlap with the rotation loci Tb1 and Tb2 of the stirring member 34.

[0200] In the above-described embodiment, the reading device 200 is provided above the printer body, but this is not limiting. That is, the image forming apparatus may be a printer that does not have a reading device. Also, the reading device may be a reading device equipped with an ADF (Auto Document Feeder) that feeds documents. [Explanation of symbols]

[0201] 32...container (developing container) / 500...detection means (toner remaining amount sensor) / 510a...light emitting element / 510b...light receiving element / 600...light guiding means (light guiding member) / 611...first protrusion (outer light guiding portion of light emitting side light guiding body) / 611a...first incident surface (incident surface) / 611b...first reflecting surface / 611c...top surface of first protrusion / 611d...first side portion / 612...second protrusion, first lower portion (inner light guiding portion) / 612a...second exit surface (light emitting window) / 621...fourth protrusion (outer light guiding portion) / 621a...first exit surface (Exit surface) / 621b... second reflecting surface / 621c... upper surface of fourth protrusion / 621d... second side portion / 622... third protrusion, second lower portion (inner light guiding portion) / 622a... second incident surface (light receiving window) / 630... second protrusion, first upper portion (inner upper portion) / 630c... upper surface of second protrusion / 640... third protrusion, second upper portion (inner upper portion) / 640c... upper surface of 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 detecting means having a light emitting element and a light receiving element arranged outside the container, and a light guiding means provided on a wall surface of the container to guide light emitted by the light emitting element to reach the light receiving element through the internal space of the container, the detecting means being configured to change an output signal of the light receiving element depending on the amount of the developer in the container; an image forming apparatus for forming an image on a recording material using the developer, The light guiding means is a first protrusion that protrudes outward from the container relative to the wall surface 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 having a tip end in the first direction; a second protrusion that protrudes toward the inside of the container relative to the wall surface in the first direction and that emits light that has entered the first protrusion into the internal space of the container; a third protrusion protruding inward from the wall surface in a second direction intersecting the gravity direction, the third protrusion receiving light emitted from the second protrusion into the internal space of the container; a fourth protrusion that protrudes from the wall surface in the second direction to the outside of the container, the fourth protrusion having an exit surface that emits the light that has entered the third protrusion toward the light receiving element, the fourth protrusion being provided at a tip end in the second direction; and an upper surface of the second protrusion is located above a first imaginary line extending along the upper surface of the first protrusion when viewed in a direction intersecting both the first direction and the direction of gravity; an upper surface of the third protrusion is located above a second imaginary 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. An image forming apparatus characterized by:

2. the second protrusion has a first lower portion located below the first imaginary 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 has a second lower portion located below the second imaginary 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, wherein the image forming apparatus is a recording medium.

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, wherein the image forming apparatus is a recording medium.

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 portion is a separate member from the second lower portion, and a lower surface of the second upper portion and an upper surface of the second lower portion are joined together; 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

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 the lower surface of the second upper portion and the upper surface of the second lower portion; 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

6. the first upper portion is formed of a material having a lower transmittance of light emitted from the light emitting element than the first lower portion; the second upper portion is formed of a material that has lower transmittance to 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 recording medium.

7. a stirring member disposed inside the container, rotating about an axis extending in the longitudinal direction of the container, for 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 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 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 recording medium.

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 direction of gravity.

8. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. an inclination angle of at least a portion of the upper surface of the second protrusion with respect to a horizontal plane, and an inclination angle of at least a portion of the upper surface of the third protrusion 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 that has entered the first protrusion into the internal space of the container, the third protrusion has a second incident surface onto which light emitted from the second protrusion into the internal space of the container is incident, the second exit surface and the second entrance surface are opposed to each other in the longitudinal direction of the container.

10. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

11. a wiping portion that is arranged inside the container, rotates around 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 light exit surface in a direction along the second light exit surface, the third protrusion has a second offset surface extending above the second incident surface in a direction along the second incident surface, the first offset surface is offset toward the wall surface with respect to the second emission surface when viewed in a height direction that is 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 incident surface in the longitudinal direction when viewed in a height direction that is perpendicular to the longitudinal direction and parallel to the wall surface of the container, the second incident 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 the opposite side to the second exit surface in the longitudinal direction, the reflective surface reflecting the light traveling from the first protrusion to the second protrusion toward the second exit surface, the third protrusion has a reflective surface provided on the opposite side to the second incident surface in the longitudinal direction, the reflective 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, wherein the image forming apparatus is a recording medium.

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, wherein the image forming apparatus is a recording medium.

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, wherein the image forming apparatus is a recording medium.

17. the second protrusion and the third protrusion face each other in the 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, wherein the image forming apparatus is a recording medium.

18. the first direction is a direction intersecting the longitudinal direction of the container, the second direction is a direction intersecting the longitudinal direction, The second protruding portion and the third protruding portion face each other in the longitudinal direction.

18. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

19. a space in which the second protrusion and the third protrusion face each other in the longitudinal direction, the space being located at a center of the container in the longitudinal direction; 19. The image forming apparatus according to claim 18.

Images