JPH11338240A - Developer container and image forming device using the container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the developer running out so as possible to be determined in further appropriate timing by preventing the generation of a ghost signal at the time point still the adequate quantity of the developer is remaining. SOLUTION: This developer container is allowed, to attach a cutoff member 15 to an agitating wing 12 rotated in a container 11 containing toner T, to arrange the cutoff member 15 so as to be rotated at a lag angle with respect to one side of a film sheet 13, and to shut off detecting light entering when the film sheet 13 wipes off a window 16 inside. In such a manner, the ghost peak is prevented from appearing in the output signal of a light receiving device 19, and moreover, the device is prevented from erroneously judging that toner runs out although a sizable quantity of the toner is still remaining in the container 11, therefore the toner is prevented from being wasted unwittingly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer accommodating container for accommodating a developer to be used in an image forming process and an image forming apparatus using the same. More specifically, the present invention relates to a developer storage container capable of appropriately predicting the emptyness of a stored developer and effectively utilizing the developer, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art A developer accommodating container for accommodating a developer is attached to a developing device of an image forming apparatus. This is because the developer is supplied to the developing device and subjected to the developing process. In such a developer accommodating container, it is necessary to notify an operator when the developer is almost exhausted. This is to take measures to replace the developer container with a new one or to replenish the developer container with the developer.

[0003] In view of this, there has been proposed a light-detecting type developer container as shown in FIG. In this developer container, a rotating shaft 10 is provided inside a container 101 for storing the developer.
2 and a stirring blade 103 attached thereto. A part of the container 101 has a developer supply port 1.
04 is formed. The rotation of the rotating shaft 102 by driving from the image forming apparatus main body side causes the stirring blade 1 to rotate.
This is for extruding the developer toward the developer supply port 104 while wiping the inner surface of the container 101 to supply the developer to the image forming portion located to the right of the developer supply port 104 in FIG.

[0004] A translucent window 106 and a mirror 107 provided therein are provided in a part of the container 101. A light emitting device 108 and a light receiving device 109 are provided on the image forming apparatus main body side so as to face the window 106. When there is a large amount of developer inside the container 101,
The light that has entered the interior of the container 101 from the light emitter 108 via the window 106 is scattered by the developer, and
7, and the light receiver 109 does not detect the reflected light. However, when the developer is low,
As long as the light is not scattered by the stirring blade 103, the mirror 10
7 and returns to the window 106.
Can detect this. Therefore, the running out of the developer can be detected by the output signal of the light receiver 109.

[0005]

However, the above-described conventional developer container has the following problems. That is, when it is attempted to detect the running out of the developer by the light detection type, the light receiver 109 detects the light much earlier than the developer in the container 101 completely runs out. This is because the distribution of the developer in the container 101 is not uniform. In particular, immediately after the inner surface of the window 106 is wiped off by the stirring blade 103, the amount of the developer near the inner surface of the window 106 is significantly reduced. In such a case, the container 1
Even if a considerable amount of the developer remains in other places in the image sensor 01, the light receiver 109 may detect light. FIG. 19 shows exactly that state.

For this reason, generally, it is not determined that the developer runs out immediately after the output signal of the light receiver 109 has been turned on even once, but an alarm of the running out of the developer is issued when a certain time has elapsed since then. I have. But still,
This did not solve the problem, and there was a strong tendency for a developer out alarm to be issued when the remaining amount of developer is still large. In particular, in the case where two stirring blades 103 are provided as shown in FIG. 19, the above-mentioned early signal is generated twice per rotation of the rotating shaft 102, so that the tendency is more remarkable. For this reason, when the developer storage container is replaced, the developer remaining in the old container 101 may be wasted.

The present invention has been made to solve the above-mentioned problems of the conventional developer container.
That is, the problem is that a ghost signal generated when a considerable amount of the developer is still remaining is suppressed, and a developer storage container that can determine the running out of the developer at a more appropriate timing and a developer container using the same. To provide an image forming apparatus.

[0008]

Means for Solving the Problems A developer accommodating container according to the present invention made to solve this problem includes a container for accommodating a developer and a light transmitting member provided on a part of a frame of the container. A window, a conveying member rotatably provided around an axis inside the container, and a conveying member for conveying the developer while wiping an inner surface of the container by rotating; and a rotatable member inside the container together with the conveying member. And a light blocking means that is provided and crosses an optical path of light entering from the window by rotating.

In this developer storage container, the developer in the container is used for image formation by the transport member rotating around the axis and transporting the developer while wiping the inner surface of the container. When the remaining amount of the developer in the container is large, light trying to enter from the window is blocked by the developer, so that the light cannot travel in the container. When the remaining amount of the developer starts to decrease, light may enter through the window. However, when the light blocking means crosses the light path, the light is blocked by the light blocking means.
I can't go any further. For this reason, even though the remaining amount of the developer is still considerable, a ghost caused by the progress of the light entering through the window is unlikely to occur, and the running out of the developer can be detected at an appropriate time.

Therefore, in the developer accommodating container of the present invention, it is desirable that the light blocking means is provided at a position which crosses the optical path when the inner surface of the window is wiped off by the transport member. It is at this timing that the ghost is most likely to occur, and the effect of the light blocking means at this time is large. Specifically, this can be achieved by arranging the light blocking means at a position delayed from the conveying member with respect to the axis of rotation.

In the developer container of the present invention,
A light-transmissive second window may be provided in a part of the frame of the container, at a position where the light reaches unless the light is blocked by the light blocking means, the transport member, or the developer. In this case, the developer storage container is a transmission type developer storage container in which the running out of the developer is detected by the emission from the second window of the light that has entered through the window and has proceeded without being hindered by the developer or light blocking means. It is. Note that the position of the second window is not limited to the position where the light incident from the window travels straight and reaches. A reflecting mirror or the like may exist in the middle of the optical path.

Alternatively, the developer accommodating container of the present invention may have a reflecting mirror that reflects the light toward the window when the light arrives. In this case, in the developer storage container, light that has entered the window and has proceeded without being hindered by the developer or light blocking means is reflected by the reflecting mirror and then returns to the window and is emitted. This is a reflective developer container.

Further, in the developer accommodating container of the present invention, a light blocking member for blocking the light can be used as the light blocking means. In this case, light entering from the window when the light blocking member, which is the light blocking means, is crossing the optical path is blocked by the light blocking member and cannot travel further. Therefore, the ghost is suppressed by the light shielding member. The light shielding member may be a member that absorbs the received light or a member that irregularly reflects the received light.

In the case of a reflective developer container, a reflection member that reflects the light can be used as the light blocking means. However, when crossing the optical path, it is necessary to arrange the reflected light so that the reflected light travels outside the window. In this case, light entering from the window when the reflection member, which is the light blocking means, is crossing the optical path is reflected by the reflection member in the direction of the day after tomorrow and cannot return to the window. For this reason, the ghost is suppressed by the reflection member.

Further, the image forming apparatus of the present invention includes the above-mentioned developer container, a light emitter for entering light into the developer container from the window, and detecting light emitted from the developer container. And an empty detecting means for detecting running out of the developer based on an output signal of the light receiving device, and an image is formed on a recording material using the developer stored in the developer storing container. To form.

In this image forming apparatus, when the light from the light emitter enters the inside of the container through the window, proceeds without being hindered by the developer or light blocking means, and reaches the light receiver, the light receiver emits an output signal. . Based on this output signal, the empty detector is used to detect that the developer has run out. However, when a large amount of the developer is present in the container, the light of the light emitting device is blocked by the developer and cannot travel in the container. Therefore, this light is not captured by the light receiver. In this state, image formation is performed using the developer supplied from inside the container. When the remaining amount of the developer starts to decrease, light may enter through the window. However, when the light blocking means is crossing the light path, the light is blocked by the light blocking means and cannot proceed further. For this reason, it is difficult for ghost to occur when light entering through the window advances and is caught by the light receiver even though the remaining amount of the developer is still considerable, and it is possible to detect the running out of the developer at an appropriate time. it can.

Generally, the light emitting device and the light receiving device are provided on the main body side of the image forming apparatus (at locations other than the developer container). In particular, the light emitter is arranged facing the window of the container. The light receiver is arranged facing the second window in the case of the transmission type, and is arranged facing the window together with the light emitter in the case of the reflection type.

Further, in the image forming apparatus according to the present invention, it is preferable that the empty detecting means determines that the developer has run out when the number of times of detection of the output signal of the light receiver reaches a predetermined number. Since the ghost is suppressed by the light-blocking means, the running out of the developer can be determined at an appropriate timing by appropriately setting a predetermined number of times.

[0019]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The present embodiment is an apparatus for forming an image on a recording medium such as printing paper by electrophotography using a toner as a developer, in which the toner is housed in a detachable cartridge type container. .

[First Embodiment] An image forming apparatus according to a first embodiment includes a toner cartridge 1 shown in a sectional view of FIG.
It is mainly configured. In the toner cartridge 1, a stirring blade 1 is provided inside a container 11 for storing the toner T.
2 and two flexible film sheets 13 attached thereto are provided rotatably about an axis. Further, a toner supply port 14 is formed in a part of the container 11. In the toner cartridge 1, the stirring blade 12 rotates (30 to 1) when driven from the image forming apparatus main body side.
20 rpm), the film sheet 13 pushes the toner T toward the toner supply port 14 while wiping and cleaning the inner surface of the container 11, and the toner supply port 14 in FIG.
Is to supply the toner T to the image forming unit located on the right side of the image forming apparatus.

Further, the stirring blade 12 is provided with a blocking member 15. The blocking member 15 is provided at a position delayed from one of the film sheets 13 with respect to the stirring blade 12. When the stirring blade 12 rotates, the blocking member 15 rotates following the film sheet 13. The stirring blade 12, the blocking member 15, and the film sheet 13 are all formed of a material having no surface gloss. A translucent window 16 and a mirror 17 provided inside are provided in a part of the container 11.

A light emitting device 18 and a light receiving device 19 are provided on the image forming apparatus main body side so as to face the window 16.
The light emitter 18 is arranged so that light (hereinafter, referred to as “detection light”) is incident from the window 16 toward the inside of the container 11. Then, the detection light is applied to the toner T or the film sheet 1.
Unless disturbed by 3 or the blocking member 15, the mirror 17 and the light receiving device 19 are reflected by the mirror 17 and returned to the window 16 to be captured by the light receiving device 19.
Is arranged. That is, the toner cartridge 1
It adopts a reflection type light detection method. However, when there is a large amount of toner T inside the container 11, the light emitting device 1
Since the detection light that has entered the inside of the container 11 from the window 8 through the window 16 is scattered by the toner T, it cannot reach the mirror 17 and the light receiver 19 does not detect the detection light. The light receiver 19 is connected to a controller 20 which is a control unit of the image forming apparatus main body. The controller 20 has a function of detecting running out of toner in the toner cartridge 1 based on an output signal of the light receiver 19 as described later.

As shown in FIG. 2, the toner cartridge 1 has a substantially semi-cylindrical body 11A forming a part of a container 11,
The agitation blade 12 provided with the film sheet 13 and the blocking member 15 is attached, the toner is filled, and then the opening on the upper surface is closed with a lid having the mirror 17 and assembled. It should be noted that, of the two film sheets 13, the lower one in FIG. 2 is for the purpose of stirring and transporting the toner, and covers the entire area of the stirring blade 12 in the longitudinal direction. On the other hand, the upper film sheet 13 in FIG. 2 is provided only for cleaning the window 16 and is provided only at a position corresponding to the window 16. However, the upper film sheet 13 may be provided in the whole area in the longitudinal direction as in the lower film sheet. The toner cartridge 1 is detachable from the main body of the image forming apparatus. The window 16 of the toner cartridge 1 attached to the main body faces downward. When the toner inside the container 11 is used for image formation and the amount thereof is significantly reduced, the toner is removed from the main body of the image forming apparatus, and a new toner cartridge 1 filled with toner is attached instead, so that the image formation is continued. Is possible.

The blocking member 15 is, as shown in FIG.
The film sheet 13 is attached to the agitating blade 12 at the attachment position 13 a of the film sheet 13 in the rotation direction behind the film sheet 13. However, the mounting position of the blocking member 15 may be anywhere within the range from the position 13a to the rotation axis of the stirring blade 12 (shown by a in the figure) as long as it is behind the film sheet 13 in the rotation direction.

Next, the operation of detecting the out of toner will be described.
When the remaining amount of toner in the container 11 is large, the light receiver 19 does not catch the detection light as described above. Therefore, in this state, as shown in FIG. 4, the output signal of the light receiver 19 remains off.

When the toner T in the container 11 decreases,
When the film sheet 13 wipes the inner surface of the window 16, detection light can enter from the window 16. However, in the state of FIG. 1, since the blocking member 15 crosses the optical path of the detection light,
The entered detection light is disturbed by the blocking member 15 and is
7 cannot be reached. Therefore, the output signal of the light receiver 19 is also off. That is, a ghost signal is prevented. The rotation of the stirring blade 12 causes the blocking member 15 to move as shown in FIG.
5 is reflected by the mirror 17 and captured by the light receiver 19 as shown in FIG. Therefore, the output signal of the light receiver 19 turns on. Therefore, in this state, a peak appears in the output signal of the light receiver 19 as shown in FIG. One peak appears during one rotation of the stirring blade 12. The controller 20 counts this peak, and determines that the toner cartridge 1 is out of toner when the count value reaches a predetermined value. Based on this determination, a warning or the like for urging the operator to replace the toner cartridge 1 is displayed.

As described above in detail, in the toner cartridge 1 according to the present embodiment, the blocking member 15 is attached to the stirring blade 12 rotating in the container 11, and the blocking member 15 is retarded to one of the film sheets 13. Since the film sheet 13 is disposed so as to rotate, the detection light entering when the film sheet 13 wipes the inner surface of the window 16 is blocked by the blocking member 15.
Is shut off by This prevents a ghost peak from appearing in the output signal of the light receiver 19. For this reason, it is not determined that the toner has run out even though a considerable amount of toner still remains in the container 11, and waste of toner is prevented.

If the blocking member 15 is not provided as described in the section of the prior art, two peaks appear during one rotation of the rotating shaft as shown in FIG. Become. One of them is a ghost peak. Because of this ghost peak, it is determined that the toner is out of toner even though a considerable amount of toner still remains in the container 11, resulting in waste of toner. This is prevented in the toner cartridge 1 according to the present embodiment.

The present embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, in this embodiment, the cartridge type is detachable from the apparatus main body. However, the present invention is not limited to this. Further, the toner may be a one-component type or a two-component type. Further, the blocking member 15 only needs to have no surface gloss, and a member different from the member constituting the stirring blade 12 may be attached to the rotating shaft (see FIG. 8),
It may be integrally molded using a part of the members constituting the stirring blade 12 (see FIG. 9). Furthermore, film sheet 1
3 does not necessarily have to be two, but may be only one, or three or more. Further, the determination of the out of toner in the controller 20 may be other than the determination based on the peak count.

[Second Embodiment] The image forming apparatus according to the second embodiment is mainly composed of a toner cartridge 2 shown in a sectional view of FIG. This toner cartridge 2
Of the toner cartridge 1 of the first embodiment is as follows.
The mirror 17 is abolished, and instead, a translucent second window 21 is provided at that position. In response to this, the position of the light receiver 19 is changed to a position facing the window 21 on the apparatus body side. As a result, the detection light that has entered from the light emitting device 18 through the window 16 is emitted from the window 21 and caught by the light receiving device 19 as long as it is not disturbed by the toner T, the film sheet 13, or the blocking member 15. That is, the toner cartridge 2 employs a transmission type light detection method. There is no particular difference other than these.

In the case of the transmission type as well, the detection of running out of toner is performed in the same manner as in the case of the reflection type of the first embodiment. That is, when the remaining amount of toner in the container 11 is large, the light receiver 19 does not catch the detection light, and the output signal of the light receiver 19 is kept off (FIG. 4). Toner T in container 11
When the film thickness decreases, the detection light may enter from the window 16 when the film sheet 13 wipes the inner surface of the window 16. However, in the state shown in FIG.
And cannot reach the window 21. Therefore, the output signal of the light receiver 19 is also off. That is, a ghost signal is prevented. When the blocking member 15 is in a position opposite to the state shown in FIG. 10 due to the rotation of the stirring blade 12, it is captured by the light receiver 19 via the window 21 as shown in FIG. Therefore, the output signal of the light receiver 19 turns on. Therefore, in this state, a peak appears in the output signal of the light receiver 19 (FIG. 6). The number of peaks is one during one rotation of the stirring blade 12, and the ghost peak is suppressed by the blocking member 15 as in the case of the first embodiment.

As described above, in the second embodiment, too, the detection of toner shortage is performed without the appearance of a ghost peak in the output signal of the photodetector 19, so that even though a considerable amount of toner remains in the container 11, It is not determined that the toner has run out, and waste of toner is prevented. In the case of the transmission type, similarly to the case of the reflection type, the blocking member 15 can be configured such that a member different from the member constituting the stirring blade 12 is attached to the rotating shaft (FIG. 1).
2), it is also possible to integrally mold using a part of the members constituting the stirring blade 12 (FIG. 13).

[Third Embodiment] The image forming apparatus according to the third embodiment is mainly composed of a toner cartridge 3 shown in a sectional view of FIG. This toner cartridge 3
In this example, a stirring blade 32 and a flexible film sheet 33 attached to the stirring blade 32 are provided inside a container 31 containing the toner T so as to be rotatable around an axis. The surface of the film sheet 33 is a matte surface without gloss. Also,
A toner supply port 34 is formed in a part of the container 31. Further, a reflection surface 35 is provided on the stirring blade 32. A part of the container 31 has a translucent window 36.
And a mirror 37 provided inside.

On the main body side of the image forming apparatus, a light emitting device 18 and a light receiving device 19 are provided facing the window 36.
The light emitter 18 is arranged so that the detection light is incident from the window 36 toward the inside of the container 31. As long as the detection light is not disturbed by the toner T, the film sheet 33 or the stirring blade 32, the detection light reaches the mirror 37, is reflected there, returns to the window 36, and is captured by the light receiver 19.
The mirror 37 and the light receiver 19 are arranged. The reflection surface 35 of the stirring blade 32 is formed in a part of the stirring blade 32 that crosses the optical path of the detection light by rotation.
When the reflection surface 35 is on the optical path of the detection light, the reflection surface 35 has an angle at which the detection light is reflected toward a direction other than the window 36 (see FIG. 15).

That is, the toner cartridge 3 is common to the first embodiment in that the toner cartridge 3 employs a reflection type light detection system.
The difference from the first embodiment is that the positional relationship between the window 36 and the mirror 37 is upside down, the number of the film sheet 33 is one, and the stirring blade 32 has a reflecting surface instead of the blocking member 15. 35 is provided.

Also in the case of the present embodiment, when the amount of toner remaining in the container 31 is large, the detection light is scattered by the toner T, so that the light receiver 19 does not catch the detection light. Even when a part of the stirring blade 32 crosses the optical path of the detection light due to the rotation, the detection light is applied to the stirring blade 3 as shown in FIG.
Since the light strikes the second reflecting surface 35 and is reflected in the direction of the day after tomorrow, it is not captured by the light receiver 19. FIG.
Even when the film sheet 33 faces the light emitter 18 and the light receiver 19 as shown in FIG.
Is a matte surface, the detection light hitting the film sheet 33 is irregularly reflected in all directions, and the reflected light of effective intensity is not captured by the light receiver 19.

When the amount of toner remaining in the container 31 becomes very small, the optical path of the detection light becomes clear when the film sheet 33 wipes the surface of the mirror 37, and the detection light reflected by the mirror 37 is captured by the light receiver 19. Can be FIG. 14 shows this state. At this time, the running out of toner is determined by the coat roller 20 based on the output signal of the light receiver 19.

As described above in detail, in the toner cartridge 3 according to the present embodiment, the reflecting surface 35 is provided in a portion of the stirring blade 32 rotating in the container 31 which crosses the optical path of the detection light, and the reflecting surface 35 is provided in the optical path. , The detection light is reflected in a direction other than the window 36. For this reason, even if the detection light hits the stirring blade 32, the reflected light is prevented from being caught by the light receiver 19 and causing a ghost signal. For this reason, it is not determined that the toner has run out even though a considerable amount of toner still remains in the container 11, and waste of toner is prevented.

If the reflecting surface 35 is not inclined as shown in FIG. 17, the light reflected by the stirring blade is captured by the light receiver 19, and a ghost signal is generated. Also, if the surface of the film sheet 33 is a glossy surface, a ghost signal may be generated in the state of FIG. Because of these ghost signals, it is determined that the toner has run out even though a considerable amount of toner still remains in the container, resulting in waste of toner. This is prevented in the toner cartridge 3 according to the present embodiment.

The present embodiment is merely an example, and does not limit the present invention. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, the reflecting surface 35 may be a stepped surface 35A as shown in FIG.

[0041]

As is apparent from the above description, according to the present invention, since the generation of the ghost signal is suppressed, it is determined that the developer has run out even though a considerable amount of the developer still remains. There is provided a developer accommodating container capable of determining the running out of the developer at a more appropriate timing without erroneous determination, and an image forming apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main part of a reflective toner cartridge according to a first embodiment.

FIG. 2 is an exploded perspective view of the toner cartridge of FIG.

FIG. 3 is a diagram illustrating a positional relationship between a film sheet and a blocking member.

FIG. 4 is a graph showing an output signal of a light receiver in a state where the amount of remaining toner is large.

FIG. 5 is a diagram showing a state in which detection light is captured by a light receiver.

FIG. 6 is a graph showing an output signal of a light receiver when the remaining amount of toner is reduced.

FIG. 7 is a graph showing an output signal of a light receiver in the case of a conventional toner cartridge.

FIG. 8 is a diagram showing a configuration in which a blocking member is attached to a stirring blade.

FIG. 9 is a view showing a configuration in which a blocking member is formed as a part of a stirring blade.

FIG. 10 is a cross-sectional view illustrating a main part of a transmission type toner cartridge according to a second embodiment.

FIG. 11 is a diagram illustrating a state in which detection light is captured by a light receiver.

FIG. 12 is a diagram showing a configuration in which a blocking member is attached to a stirring blade.

FIG. 13 is a view showing a configuration in which a blocking member is formed as a part of a stirring blade.

FIG. 14 is a cross-sectional view illustrating a main part of a reflective toner cartridge according to a third embodiment.

FIG. 15 is a diagram illustrating a reflection surface of a stirring blade.

FIG. 16 is a diagram illustrating that the surface of the film sheet is a matte surface.

FIG. 17 is a diagram showing a case where the reflection surface has no inclination for comparison.

FIG. 18 is a diagram showing a modification of the reflection surface.

FIG. 19 is a diagram illustrating a conventional toner cartridge.

[Explanation of symbols]

 11, 31 Container 12, 32 Stirring blade (conveying member) 13, 33 Film sheet 15 Blocking member 16, 36 Window 17, 37 Mirror 18 Light emitting device 19 Light receiving device 20 Controller 21 Second window 35 Reflecting surface

Claims (8)

[Claims] A container for storing a developer, a light-transmitting window provided in a part of a frame of the container, and a rotatable member provided inside the container so as to be rotatable around an axis. A conveying member for conveying the developer while wiping the inner surface of the container;
A developer accommodating container comprising: a rotatable member provided inside the container so as to be rotatable together with the transport member; and a light blocking unit that rotates and crosses an optical path of light entering the window. 2. The developer accommodating container according to claim 1, wherein the light blocking means is provided at a position crossing the optical path when an inner surface of the window is wiped off by the transport member. A developer accommodating container characterized by the above-mentioned. 3. The developer container according to claim 1, further comprising a light-transmitting second window provided in a part of a frame of the container, wherein the second window is The developer container is provided at a position where the light reaches unless the light is blocked by the light blocking means, the transport member, or the developer. 4. The developer storage container according to claim 1, further comprising a reflecting mirror that reflects the light toward the window when the light reaches the developer storage container. . 5. The method according to claim 1, wherein:
In the developer container described in (1), the light blocking means is a light blocking member that blocks the light. 6. The developer accommodating container according to claim 4, wherein the light blocking means is a reflecting member that reflects the light toward a portion other than the window when crossing the optical path. Developer container. 7. One of claims 1 to 6
A light receiving device for detecting light emitted from the developer storage container, a light emitting device for emitting light from the window into the developer storage container, and an output signal of the light receiving device. An image forming apparatus for forming an image on a recording material using the developer stored in the developer storage container. 8. An image forming apparatus according to claim 7, wherein said empty detecting means determines that the developer has run out when the number of times of detection of the output signal of said light receiver reaches a predetermined number. Image forming apparatus.