JP2012194392A - Cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cartridge and an image forming apparatus which can prevent the inside of a developer storage chamber from being erroneously determined that it is in an empty state in spite of the fact that much toner is present therein.SOLUTION: Each of side walls 31 and 32 of a housing 11 is provided with a pair of light transmission windows 36 mutually opposed in the facing direction of the side walls and capable of being transmitted with light beams advancing in the facing direction thereof. The inside of a main body casing 2 is provided with an empty sensor to receive the light beams transmitting the light transmission windows 36 and to output signals therefrom. Based on the signals output from this empty sensor, an amount of the toner stored inside a toner storage chamber 12 is detected (estimated). The right side wall 32 is provided with a light extinction member 61 for irreversibly reducing the amount of light beams transmitting the light transmission window 36 in connection with a rise of surrounding temperature. Hence, when a developer cartridge 6 is left under the environment of high temperature, the amount of light beams transmitting the light transmission windows 36 is irreversibly reduced.

Description

  The present invention relates to an image forming apparatus such as a laser printer and a cartridge attached to the image forming apparatus.

  In an example of an image forming apparatus such as a laser printer, a photosensitive drum and a developing device are provided. In the case of the developing device, a toner storage chamber and a developing chamber that are in communication with each other are formed. For example, an agitator made of PET (polyethylene terephthalate) is rotatably provided in the toner storage chamber. A developing roller is rotatably provided in the developing chamber. A part of the developing roller is exposed outside the developing chamber and is in contact with the surface of the photosensitive drum.

  The toner in the toner chamber is supplied from the toner chamber to the developing chamber while being stirred in the toner chamber by the rotation of the agitator. The toner supplied into the developing chamber is supplied to the surface of the photosensitive drum by the developing roller. On the other hand, an electrostatic latent image is formed on the surface of the photosensitive drum. Then, the electrostatic latent image is developed into a toner image with toner, and the toner image is transferred to a sheet, thereby forming an image on the sheet.

  For this reason, toner is consumed as the image is formed on the paper. When the toner in the developing device runs out, an image cannot be formed on the paper, so that it is necessary to replace the developing device or supply toner to the toner storage chamber.

  Therefore, the image forming apparatus is provided with a configuration for detecting a state (empty state) in which the remaining amount of toner in the toner storage chamber is low. That is, a pair of light transmission windows are formed on the side wall of the toner storage chamber at positions facing each other in a direction parallel to the rotational axis of the agitator. A light emitting element is disposed outside the developing device at a position facing one light transmission window, and a light receiving element is disposed at a position facing the other light transmission window.

  As the agitator rotates, the toner rises in the toner storage chamber. The rising toner blocks light entering the toner storage chamber from the light transmission window. The amount of toner that rises depends on the remaining amount of toner in the toner storage chamber. That is, the amount of toner that rises is large when the amount of toner remaining in the toner chamber is large, and the amount of toner that rises is small when the amount of toner remaining in the toner chamber is small. As the amount of toner that rises increases, the amount of light that reaches the light receiving element decreases, so that the remaining amount of toner in the toner storage chamber can be estimated (detected) based on the amount of light received by the light receiving element.

Japanese Patent Laid-Open No. 2001-5276

  When the developing device is left in a high temperature environment, the properties of the toner in the developing device change. Specifically, the external additive on the surface of the toner is peeled off and the fluidity of the toner is lowered. Therefore, the amount of toner that rises due to the rotation of the agitator decreases, and the amount of light that reaches the light receiving element increases. As a result, the remaining amount of toner in the toner storage chamber is estimated to be less than the actual remaining amount based on the amount of light received by the light receiving element, and the toner storage chamber has a large amount of toner remaining despite the fact that much toner remains. There is a risk of erroneous determination that the toner is in an empty state where almost no toner remains.

  An object of the present invention is to provide a cartridge and an image forming apparatus that can prevent erroneous determination of being in an empty state even though a large amount of toner remains in the developer accommodating chamber.

  In order to achieve the above object, according to a first aspect of the present invention, there is provided a developer accommodating chamber for accommodating a developer between the pair of side walls, the cartridge having a pair of side walls facing each other with a space therebetween. The developer housed in the developer housing chamber is agitated by rotation about a rotation axis provided in the developer housing chamber and extending in the opposing direction of the pair of side walls. A stirring member, a pair of light transmitting portions provided on each of the side walls, facing each other in the facing direction and transmitting light traveling in a traveling direction parallel to the facing direction, and at least one of the pair of side walls And a light-reducing member provided on one side and irreversibly reducing the amount of light transmitted through the light-transmitting portion with respect to an increase in ambient temperature.

  According to a second aspect of the present invention, in the image forming apparatus, the cartridge according to any one of claims 1 to 9, a main body casing that accommodates the cartridge, the main body casing, and the pair of A sensor that receives light transmitted through the light transmitting portion and outputs a signal, and a developer amount that detects the amount of developer contained in the developer containing chamber based on a signal output from the sensor And a detector.

  According to the first invention, the housing of the cartridge has a pair of side walls facing each other with a space therebetween, and a developer containing chamber for containing the developer between the pair of side walls. A stirring member is provided in the developer accommodating chamber. The agitating member agitates the developer accommodated in the developer accommodating chamber by rotation about a rotation axis extending in the opposing direction of the pair of side walls.

  Each side wall of the housing is provided with a pair of light transmitting portions that face each other in the facing direction and can transmit light traveling in the facing direction. For this reason, a sensor that receives light transmitted through the pair of light transmitting portions and outputs a signal is provided, and the amount of developer stored in the developer storage chamber is detected based on a signal output from the sensor. (Estimated).

  At least one of the pair of side walls is provided with a light reducing member that irreversibly reduces the amount of light transmitted through the light transmitting portion with respect to an increase in ambient temperature. Therefore, when the cartridge is left in a high temperature environment, the amount of light that passes through the light transmission portion is irreversibly reduced. As a result, since the flowability of the developer in the developer containing chamber is reduced, the amount of light transmitted through the light transmitting portion can be kept small even if the amount of the developer that rises due to the rotation of the stirring member is small. it can. Therefore, even though a large amount of toner remains in the developer accommodating chamber, the empty in which the toner hardly remains in the developer accommodating chamber based on the amount of light transmitted through the light transmitting portion (the amount of light received by the sensor). It can be prevented that the state is erroneously determined.

  According to the second invention, the housing of the cartridge has a pair of side walls facing each other with a space therebetween, and a developer containing chamber for containing the developer between the pair of side walls. A stirring member is provided in the developer accommodating chamber. The agitating member agitates the developer accommodated in the developer accommodating chamber by rotation about a rotation axis extending in the opposing direction of the pair of side walls.

  Each side wall of the housing is provided with a pair of light transmitting portions that face each other in the facing direction and can transmit light traveling in the facing direction. A sensor that receives light transmitted through the light transmission portion and outputs a signal is provided in the main body casing. Based on the signal output from this sensor, the amount of developer contained in the developer containing chamber is detected (estimated).

  At least one of the pair of side walls is provided with a light-reducing member that irreversibly decreases the amount of light transmitted through the light transmission part with respect to an increase in ambient temperature. Therefore, when the cartridge is left in a high temperature environment, the amount of light that passes through the light transmission portion is irreversibly reduced. As a result, since the flowability of the developer in the developer containing chamber is reduced, the amount of light transmitted through the light transmitting portion can be kept small even if the amount of the developer that rises due to the rotation of the stirring member is small. it can. Therefore, even though a large amount of toner remains in the developer accommodating chamber, the empty in which the toner hardly remains in the developer accommodating chamber based on the amount of light transmitted through the light transmitting portion (the amount of light received by the sensor). It can be prevented that the state is erroneously determined.

FIG. 1 is a sectional view of a laser printer according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration for toner amount detection. FIG. 3 is a right side view of the developing cartridge, showing a state in which the moving unit is located at the non-dimming position. FIG. 4 is a right side view of the developing cartridge, showing a state in which the moving unit is located at the dimming position. FIG. 5A is a cross-sectional view (hatching is omitted) showing the light reducing member and the right side wall of the housing of the developing cartridge, and shows a state where the moving unit is located at the non-light reducing position. FIG. 5B is a cross-sectional view (hatching is omitted) showing the light-reducing member and the right side wall of the housing of the developing cartridge, and shows a state where the moving unit is moving from the non-light-reducing position to the light-reducing position. FIG. 5C is a cross-sectional view (hatch is omitted) showing the light reducing member and the right side wall of the housing of the developing cartridge, and shows a state where the moving unit is positioned beyond the light reducing position. FIG. 5D is a cross-sectional view (hatch is omitted) showing the light reducing member and the right side wall of the housing of the developing cartridge, and shows a state where the moving unit is located at the light reducing position.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1. Laser Printer As shown in FIG. 1, a laser printer 1 as an example of an image forming apparatus includes a main body casing 2. A front cover 3 is provided on the front side wall of the main casing 2 so as to be openable and closable.

  The front side of the laser printer 1 is the front side in the front-rear direction. Further, in a state where the laser printer 1 is placed on a plane, the direction perpendicular to the plane is the vertical direction. Then, when the laser printer 1 placed on a plane is viewed from the front side, the left and right sides of the laser printer 1 are defined.

  A process cartridge 4 is mounted at a position slightly in front of the center in the front-rear direction in the main casing 2. The process cartridge 4 is mounted in the main casing 2 and detached from the main casing 2 through the cartridge attaching / detaching port 3 with the front cover 3 opened.

  The process cartridge 4 includes a drum cartridge 5 and a developing cartridge 6 that is detachably attached to the drum cartridge 5.

  The drum cartridge 5 includes a drum frame 7 as an example of a frame. A photosensitive drum 8 is rotatably held at the rear end of the drum frame 7. The drum frame 7 holds a charger 9 and a transfer roller 10. The charger 9 and the transfer roller 10 are disposed behind and below the photosensitive drum 8, respectively.

  The developing cartridge 6 as an example of the cartridge is mounted on a portion of the drum frame 7 ahead of the photosensitive drum 8. The developing cartridge 6 includes a housing 11 that accommodates toner. Inside the housing 11, a toner storage chamber 12 and a developing chamber 13 are formed adjacent to each other in the front-rear direction. The toner storage chamber 12 and the developing chamber 13 are in communication with each other.

  The toner storage chamber 12 as an example of a developer storage chamber is a space for storing toner. The toner storage chamber 12 stores an agitator 14 made of a resin film. An agitator 14 as an example of a stirring member is attached to an agitator shaft 15 extending in the left-right direction, and is provided so as to be rotatable integrally with the agitator shaft 15. As the agitator 14 rotates, the toner stored in the toner storage chamber 12 is agitated and sent from the toner storage chamber 12 to the developing chamber 13.

  In the developing chamber 13, a developing roller 16 and a supply roller 17 are provided so as to be rotatable about a developing roller shaft 18 and a supply roller shaft 19 that extend in the left-right direction, respectively. The developing roller 16 is disposed such that a part of its surface (circumferential surface) is exposed rearward from the housing 11. The developing cartridge 6 is mounted on the drum cartridge 5 so that the surface of the developing roller 16 is in contact with the surface (circumferential surface) of the photosensitive drum 8. The supply roller 17 is disposed such that the surface (circumferential surface) thereof is in contact with the surface of the developing roller 16 from the front lower side. The toner in the developing chamber 13 is supplied to the surface of the developing roller 16 by the supply roller 17 and is carried as a thin layer on the surface of the developing roller 16.

  In the main casing 2, an exposure device 20 including a laser is disposed above the process cartridge 4.

  At the time of image formation, the photosensitive drum 8 is rotated at a constant speed clockwise as viewed from the left side. As the photosensitive drum 8 rotates, the surface of the photosensitive drum 8 is uniformly charged by the discharge from the charger 9. On the other hand, a laser beam is emitted from the exposure unit 20 based on image data received from a personal computer (not shown) connected to the laser printer 1. The laser beam passes between the charger 9 and the developing cartridge 6 and is irradiated onto the uniformly positively charged surface of the photosensitive drum 8 to selectively expose the surface of the photosensitive drum 8. As a result, charges are selectively removed from the exposed portion of the photosensitive drum 8, and an electrostatic latent image is formed on the surface of the photosensitive drum 8. When the electrostatic latent image faces the developing roller 16 by the rotation of the photosensitive drum 8, toner is supplied from the developing roller 16 to the electrostatic latent image. As a result, a toner image is formed on the surface of the photosensitive drum 8.

  A paper feed cassette 21 that stores paper P is disposed at the bottom of the main casing 2. A pickup roller 22 for feeding paper from the paper feed cassette 21 is provided above the paper feed cassette 21. Further, a conveyance path 23 having an S-shape in side view is formed in the main body casing 2. The conveyance path 23 reaches from the paper feed cassette 21 to the paper discharge tray 24 formed on the upper surface of the main casing 2 via the space between the photosensitive drum 8 and the transfer roller 10. The paper P stored in the paper feed cassette 21 is sent out one by one to the transport path 23 by the pickup roller 22. Then, the paper P is transported along the transport path 23 toward the paper discharge tray 24.

  During the conveyance, when the paper P passes between the photosensitive drum 8 and the transfer roller 10, the toner image on the surface of the photosensitive drum 8 is transferred to the paper P by the electrical action of the transfer roller 10. .

On the conveyance path 23, a fixing device 25 is provided on the downstream side in the conveyance direction of the paper P with respect to the transfer roller 10. The paper P on which the toner image has been transferred is transported through the transport path 23 and passes through the fixing device 25. In the fixing device 25, the toner image becomes an image and is fixed on the paper P by heating and pressing. The paper P on which the image is thus formed is discharged onto the paper discharge tray 24 by the paper discharge roller 26.
2. Housing of Developer Cartridge As shown in FIG. 2, the housing 11 of the developer cartridge 6 includes a pair of side walls 31 and 32 that face each other with a space therebetween in the left-right direction. As shown in FIG. 1, an upper wall 33 is installed between the upper ends of the side walls 31 and 32. Further, a lower wall 34 is installed between the lower end portions of the side walls 31 and 32 as shown in FIG.

  A V-shaped partition portion 35 that is pointed upward is formed in the middle portion of the lower wall 34 in the front-rear direction. A portion of the lower wall 34 in front of the partition portion 35 has a semicircular arc shape that is convexly curved downward, and a front end portion thereof is connected to a front end portion of the upper wall 33. The toner storage chamber 12 is defined by the front side portions of the side walls 31, 32, the upper wall 33 and the lower wall 34. On the other hand, the developing chamber 13 is defined by the rear portions of the side walls 31, 32, the upper wall 33 and the lower wall 34. The rear end portion of the lower wall 34 is parallel to the rear end portion of the upper wall 33 with a space therebetween, and the developing chamber 13 is located at each rear end edge of the side walls 31, 32, the upper wall 33 and the lower wall 34. It is opened rearward through an enclosed opening. The developing roller 16 is disposed so as to close the opening. Further, the toner storage chamber 12 and the developing chamber 13 communicate with each other via the upper wall 33 and the partition portion 35.

Further, as shown in FIG. 2, a light transmission window 36 as an example of a light transmission portion is formed on each of the side walls 31 and 32. As shown in FIGS. 3 and 4, the light transmission window 36 is formed by fitting a circular plate made of a transparent resin into a circular hole formed through the side walls 31 and 32. And the light transmission window 36 of each side wall 31 and 32 is arrange | positioned in the position spaced apart ahead with respect to the partition part 35 of the lower wall 34, and has mutually opposed in the left-right direction.
3. Empty Sensor As shown in FIG. 2, an empty sensor 43 as an example of a sensor composed of a pair of a light emitting element 41 and a light receiving element 42 is provided in the main body casing 2. The light emitting element 41 and the light receiving element 42 are disposed so as to face each other in the left-right direction across the position where the developing cartridge 6 is disposed in the main casing 2. In a state where the process cartridge 4 (developing cartridge 6) is mounted in the main casing 2, the light emitting element 41 faces the light transmission window 36 of the left side wall 31 from the left side (outside), and the light receiving element 42. Is opposed to the light transmission window 36 of the right side wall 32 from the right side (outside). That is, with the process cartridge 4 mounted in the main casing 2, the toner storage chamber 12 of the developing cartridge 6 and the pair of light transmission windows 36 are disposed on the optical path from the light emitting element 41 to the light receiving element 42. .
4). Toner amount detection unit The laser printer 1 also includes a toner amount as an example of a developer amount detection unit for detecting the amount (remaining amount) of toner T stored in the toner storage chamber 12 of the developing cartridge 6. A detection unit 51 is provided. For example, the toner amount detection unit 51 is incorporated in the control unit 52 for controlling each unit of the laser printer 1 as a part of its function. The control unit 52 is composed of a microcomputer.

  A light emitting element 41 and a light receiving element 42 are connected to the toner amount detection unit 51. The toner amount detection unit 51 controls light emission of the light emitting element 41. For example, the light receiving element 42 outputs a voltage corresponding to the amount of light received from the light emitting element 41 as a signal.

  As the agitator 14 rotates, the toner rises in the toner storage chamber 12. On the other hand, the light from the light emitting element 41 enters the toner storage chamber 12 through the light transmission window 36. This light is blocked by the toner rising in the toner storage chamber 12. The amount of toner that rises depends on the remaining amount of toner in the toner storage chamber 12. That is, when the amount of toner remaining in the toner storage chamber 12 is large, the amount of toner rising is large, and when the amount of toner remaining in the toner storage chamber 12 is small, the amount of toner rising is small. As the amount of toner that rises increases, the amount of light that reaches the light receiving element 42 decreases.

The toner amount detection unit 51 controls the light emission of the light emitting element 41, and based on the level of the signal output from the light receiving element 42 at the time of control, that is, the amount of received light in the light receiving element 42, Estimate (detect) the amount. Then, when the remaining amount of toner in the toner storage chamber 12 becomes equal to or less than a predetermined amount, the toner amount detection unit 51 determines that the toner is almost empty in the toner storage chamber 12 and is in an empty state. Control for notifying that it is in a state (for example, control for displaying that fact on a display unit provided in the laser printer 1) is executed.
5. Dimming member Further, as shown in FIGS. 3 and 4, a dimming member 61 is provided on the right side wall 32 of the housing 11 of the developing cartridge 6 above the light transmission window 36. The dimming member 61 includes a moving part 62 and a facing part 63 fixed to the tip of the moving part 62.

  The moving part 62 is made of a bimetal wound in a spiral shape. Specifically, the moving part 62 includes a high expansion metal plate 64 made of a metal (for example, brass) having a relatively large thermal expansion coefficient and a metal (for example, nickel copper) having a relatively small thermal expansion coefficient. A low-expansion metal plate 65 made of is attached to form an elongated plate shape. A cylindrical boss 66 is formed on the side wall 32 at a position in front of the light transmission window 36, and one end in the longitudinal direction of the moving part 62 is fixed to the boss 66. And the moving part 62 is wound by the spiral shape clockwise seen from the right side so that the low expansion metal plate 65 may become inside. At normal temperature (about 25 ° C.), as shown in FIG. 3, the other end portion (tip portion) of the moving portion 62 extends downward.

  The facing part 63 is made of a light reducing film. As the light-reducing film, for example, a light amount adjusting filter (ND filter No. 0.5) manufactured by FUJIFILM Corporation can be employed. The facing portion 63 is attached to the distal end portion of the moving portion 62 so that one end edge thereof is along the distal end portion of the moving portion 62. At normal temperature, as shown in FIG. 3, the facing portion 63 has a slightly lower front corner portion (a corner portion formed by an edge along the tip portion of the moving portion 62 and an edge perpendicular thereto) at the light transmission window 36. It is disposed at a position that does not substantially overlap the light transmission window 36 in the left-right direction to the extent that it has reached.

  Note that the concept of the position where the facing portion 63 does not substantially overlap the light transmission window 36 in the left-right direction at room temperature may include a position where the facing portion 63 does not overlap the light transmission window 36 at all. A position where the portion 63 does not overlap the light transmission window 36 in the left-right direction may be included.

  Further, as shown in FIGS. 5A, 5B, 5C, and 5D, the moving portion 62 has a protruding locking portion 67 on the left side at a position spaced in the longitudinal direction of the facing portion 63 and the moving portion 62. Is formed to protrude.

Correspondingly, the right side wall 32 of the housing 11 of the developing cartridge 6 has a position facing the front upper corner of the facing portion 63 in the left-right direction at room temperature, as shown in FIG. A locked portion 68 is formed protruding rightward. As shown in FIGS. 5A to 5D, the locked portion 68 becomes higher on the upstream side in the moving direction (described later) of the facing portion 63 as the ambient temperature increases (the side wall becomes higher in the moving direction). It has the inclined surface 69 which inclines so that it may leave | separate from 32. The locked portion 68 has an orthogonal surface 70 orthogonal to the side wall 32 on the downstream side in the movement direction.
6). Change under High Temperature Environment Under normal temperature environment, as shown in FIG. 5A, the locking portion 67 of the dimming member 61 is opposed to the locked portion 68 formed on the side wall 32 of the developing cartridge 6. The distal end portion (opposing portion 63) of the moving portion 62 is disposed at a position spaced from the upstream side in the moving direction.

  When the developing cartridge 6 is placed in a high temperature environment (for example, in an environment of 50 ° C.), the high expansion metal plate 64 and the low expansion metal plate 65 of the moving part 62 of the light reducing member 61 are thermally expanded. Since the thermal expansion coefficients of the high expansion metal plate 64 and the low expansion metal plate 65 are different from each other, the high expansion metal plate 64 and the low expansion metal plate 65 thermally expand with different expansion amounts. As a result, the distal end portion of the moving unit 62 is directed toward a dimming position (position shown in FIG. 4) that has a posture extending forward and downward from a non-dimming position (position shown in FIG. 3) that has a posture extending downward. Move.

  Along with the movement of the tip of the moving part 62, the facing part 63 of the light reducing member 61 does not substantially overlap in the left-right direction with the light transmission window 36 provided on the right side wall 32 of the housing 11 of the developing cartridge 6. From such a position (position shown in FIG. 3), it overlaps with the light transmission window 36 in the opposing portion 63 in the left-right direction toward a position (position shown in FIG. 4) that overlaps the light transmission window 36 in the left-right direction. Move so that the area of the part increases.

  During the movement of the moving part 62 and the opposing part 63, the locking part 67 contacts the inclined surface 69 of the locked part 68 as shown in FIG. 5B. When the moving part 62 further moves after the contact, the locking part 67 slides on the inclined surface 69 to the right. By this sliding, the moving part 62 moves while curving so as to be concave to the right.

  When the moving part 62 further moves and the locking part 67 exceeds the locked part 68 as shown in FIG. 5C, the moving part 62 returns to a posture almost parallel to the side wall 32. Then, in a state where the thermal expansion of the moving part 61 is completed, the locking part 67 is arranged at a position spaced from the locked part 68 on the downstream side in the moving direction of the moving part 62.

  Thereafter, when the developing cartridge 6 is returned to the normal temperature environment, the moving part 62 (the high expansion metal plate 64 and the low expansion metal plate 65) is thermally contracted. Thereby, the front-end | tip part of the moving part 62 moves toward a non-light reduction position. In the middle of this movement, as shown in FIG. 5D, the locking portion 67 contacts the orthogonal surface 70 of the locked portion 68. As a result, the locking portion 67 is locked to the locked portion 68, further movement of the moving portion 62 is prevented, and the facing portion 63 is held at a position that overlaps the light transmission window 36 in the left-right direction. . At this time, the position of the distal end portion of the moving unit 62 is a dimming position.

In a state in which the facing portion 63 largely overlaps the light transmission window 36 in the left-right direction, the light from the light emitting element 41 passes through the light transmission window 36 on the right side wall 32 of the housing 11 of the developing cartridge 6 and then the facing portion 63. And enters the light receiving element 42. As the light passes through the facing portion 63, the amount of light incident on the light receiving element 42 is reduced. Therefore, once the developing cartridge 6 is exposed to a high temperature environment, the amount of light incident on the light receiving element 42 is irreversibly reduced as compared to before being exposed to the high temperature environment.
7). Effect 7-1. Effect 1
As described above, the housing 11 of the developing cartridge 6 has the pair of side walls 31 and 32 opposed to each other with a space therebetween and the toner containing chamber 12 for containing toner between the pair of side walls 31 and 32. is doing. An agitator 14 is provided in the toner storage chamber 12. The agitator 14 agitates the toner stored in the toner storage chamber 12 by rotation about the rotation axis extending in the opposite direction of the pair of side walls 31, 32, that is, in the left-right direction.

  The side walls 31 and 32 of the housing 11 are provided with a pair of light transmission windows 36 that face each other in the facing direction and are capable of transmitting light traveling in the facing direction. In the main casing 2, an empty sensor 43 that receives light transmitted through the light transmission window 36 and outputs a signal is provided. Based on the signal output from the empty sensor 43, the amount of toner stored in the toner storage chamber 12 is detected (estimated).

At least one of the pair of side walls 31 and 32 is provided with a light reducing member 61 that irreversibly reduces the amount of light transmitted through the light transmission window 36 with respect to an increase in ambient temperature. Therefore, when the developing cartridge 6 is left in a high temperature environment, the amount of light transmitted through the light transmission window 36 is irreversibly reduced. As a result, since the fluidity of the toner in the toner storage chamber 12 is reduced, the amount of light transmitted through the light transmission window 36 can be kept small even if the amount of toner that rises due to the rotation of the agitator 14 is small. it can. Therefore, although a large amount of toner remains in the toner storage chamber 12, almost no toner remains in the toner storage chamber 12 based on the amount of light transmitted through the light transmission window 36 (the amount of light received by the sensor). It is possible to prevent erroneous determination that the state is not empty.
7-2. Effect 2
The light reducing member 61 is provided on the right side wall 32 of the pair of side walls 31 and 32. That is, the dimming member 61 is disposed on the side wall 32 on the light receiving element 42 side of the pair of side walls 31 and 32. Therefore, the distance between the light reducing member 61 and the light receiving element 42 is short. Thereby, even if the light transmitted through the light transmission window 36 is refracted at the position of the light reducing member 61, the light can be satisfactorily received by the light receiving element 42.
7-3. Effect 3
The dimming member 61 moves so that the area overlapping the light transmission window 36 in the opposite direction increases as the ambient temperature rises. Thereby, the amount of light transmitted through the light transmission window 36 can be reduced as the ambient temperature rises.
7-4. Effect 4
Specifically, the light reducing member 61 includes a moving part 62 and a facing part 63. The moving unit 62 moves from the non-dimming position toward the dimming position as the ambient temperature increases. The facing portion 63 is made of, for example, a light-reducing film that transmits light while reducing the amount thereof, and extends from the moving portion 62 to the downstream side in the moving direction. The facing portion 63 does not overlap the light transmitting window 36 in the facing direction when the moving portion 62 is located at the non-light-reducing position, and at least the light-transmitting window 36 is located when the moving portion 62 is located at the light-reducing position. It overlaps with the part in the opposite direction. Thereby, the area of the part which overlaps with the light transmission window 36 in the light reduction member 61 (opposing part 63) in an opposing direction can be increased with the surrounding temperature rise.
7-5. Effect 5
A locking part 67 is formed on the light reducing member 61. On the other hand, a locked portion 68 is formed in the housing 11. The locking part 67 is locked to the locked part 68 in a state where the moving part 62 of the light shielding member is located at the light reduction position. Thereby, the moving part 62 can be prevented from returning from the dimming position to the non-dimming position, and irreversible dimming with respect to an increase in ambient temperature can be achieved.
8). Modifications Although one embodiment of the present invention has been described above, the present invention can be implemented in other forms.

  For example, although the opposing part 63 consists of a light reduction film, you may be comprised by the light shielding film which interrupts | blocks light.

  Further, although the monochrome laser printer 1 is taken up as an example of the image forming apparatus, the present invention can also be applied to a color laser printer.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body casing 11 Housing | casing 12 Toner storage chamber 14 Agitator 31 Side wall 32 Side wall 36 Light transmission window 43 Empty sensor 51 Toner amount detection part 61 Light reducing member 62 Moving part 63 Opposing part 67 Locking part 68 Locked part

Claims (8)

A housing having a pair of side walls opposed to each other with a space therebetween, and a developer storage chamber for storing a developer between the pair of side walls;
A stirring member that is provided in the developer storage chamber and that stirs the developer stored in the developer storage chamber by rotation about a rotation axis that extends in an opposing direction of the pair of side walls;
A pair of light transmitting portions provided on each of the side walls, facing each other in the facing direction, and capable of transmitting light traveling in a traveling direction parallel to the facing direction;
And a dimming member that is provided on at least one of the pair of side walls and irreversibly decreases the amount of light transmitted through the light transmission portion with respect to an increase in ambient temperature.   2. The cartridge according to claim 1, wherein the dimming member is provided on the side wall that is relatively disposed downstream of the pair of side walls in the traveling direction.   3. The cartridge according to claim 1, wherein the dimming member moves so that an area overlapping the light transmitting portion in the facing direction increases with an increase in ambient temperature. The dimming member is
A moving part that moves from a non-dimming position toward a dimming position as the ambient temperature rises,
The moving portion extends downstream from the moving direction, and the moving portion is not substantially overlapped with the light transmitting portion in the opposing direction in a state where the moving portion is located at the non-dimming position, and the moving portion is located at the dimming position. The cartridge according to claim 3, further comprising at least a part of the light transmission portion and a facing portion that overlaps in the facing direction when positioned. The light shielding member includes a locking portion,
The cartridge according to claim 4, wherein the housing is formed with a locked portion to which the locking portion is locked in a state where the moving portion is located at the dimming position.   The cartridge according to claim 4, wherein the facing portion is formed of a light-reducing film that transmits light while reducing the amount thereof.   The cartridge according to claim 4, wherein the facing portion is made of a light shielding film that blocks light. A cartridge according to any one of claims 1 to 7,
A main body casing for housing the cartridge;
A sensor that is provided in the main body casing, receives light transmitted through the pair of light transmission portions, and outputs a signal;
An image forming apparatus comprising: a developer amount detection unit configured to detect the amount of developer accommodated in the developer accommodating chamber based on a signal output from the sensor.

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