JPH0452671A - Toner storage amount detecting device - Google Patents

Abstract

PURPOSE:To detect the storage amount of toner in a developing container directly by providing a transparent electret which has the same polarity with toner as part of the internal wall surfaces of the developing container and detecting the storage amount of toner in the developing container by an optical sensor. CONSTITUTION:The transparent filmy electret E is stuck entirely on the respective internal wall surfaces of the projection part 126 of the developing container 122 with an adhesive. The electret E constitutes part of the respective internal wall surfaces of the developing container 122 and is stuck so that the surface on the side which is exposed in the container 122 has the same polarity with the toner 124. The optical sensor 128 is arranged nearby the electret E so that its light emitting element 128a and light receiving element 128b face each other across the projection part 126. Consequently, the storage amount of toner in the developing container can be detected directly, and relatively easily and securely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner accommodation amount detection device applied to a developing device of an image generating device such as an electrostatic copying machine or an electrostatic printing machine.

[Conventional technology]

In general, image generation is performed by electrostatically attaching charged fine particles (toner), which is a developer, to an electrostatic latent image formed on the surface of a photoreceptor to create a visible image, which is then transferred and fixed onto copy paper. The device has been well known and widely put into practical use.

An electrostatic copying machine as an example of this type of image generation device includes:
A unit frame that is detachably mounted in a support structure (housing) and a process unit that includes an image output means such as a photosensitive drum (rotary drum) that is rotatably supported by the unit frame. Exists (Jitsukai Showa 6)
3-86639). The electrostatic copying machine disclosed in the publication will be explained as a conventional technique with reference to FIG.

The illustrated electrostatic copying machine includes a box-shaped housing generally designated by the number 2. The housing 2 is comprised of a so-called shell-shaped support structure consisting of a lower support frame 4 and an upper support frame 6 attached to the lower support frame 4. The lower left end of the upper support frame 6 is rotatably connected to the lower support frame 4 via a shaft 8 extending in the front-rear direction of the lower support frame 4, that is, in the direction perpendicular to the paper plane in FIG. There is.

On the upper surface of the housing 2, ie, on the upper surface of the upper support frame 6, a document mounting means 10 is mounted so as to be able to reciprocate in the left-right direction. The document placing means 10 includes a transparent plate 12 on which a document to be copied is placed, and a document cover (not shown) that can be opened and closed to cover the transparent plate 12 and the document placed thereon. ).

A process unit 14 located at the center of the housing 2 is detachably attached to the upper support frame 6. The mounting structure is as follows.

That is, the upper support frame 6 has a pair of support rails 16 and 1 extending in a direction perpendicular to the plane of the paper at intervals in the left-right direction.
8 is fixed. - The Sumo Riki process unit 14 has a process unit frame 20 (unit frame 20), and supported parts 22 and 24 are provided at both left and right ends of this unit frame 20, extending in a direction perpendicular to the paper surface. The supported parts 22 and 24 of this unit frame 20 are positioned on the support rails 16 and 18 of the upper support frame body 6, respectively,
By sliding the unit frame 20 in a direction perpendicular to the plane of the paper, the process unit 14 is detachably attached to the upper support frame 6.

At the center of the unit frame 20, a photoreceptor drum (rotating drum) 2 is provided with a suitable electrostatic photoreceptor on its circumferential surface.
6 is rotatably attached.

The unit frame 20 further includes a charging device (corona discharger for charging) 30, a developing device 32, and a cleaning device around the photosensitive drum 26, which is rotationally driven in the direction shown by an arrow 28. A device 34 is attached.

The developing device 32 includes a sleeve mechanism 36 that supplies toner, which is a developer, to the circumferential surface of the photoreceptor drum 260.

The cleaning device 34 also includes an elastic blade 38 that comes into contact with the circumferential surface of the photoreceptor drum 26 and a toner collection chamber 40 .

The above-described photosensitive drum 26, charging device 30, and developing device 3
2, the cleaning device 34, and the like constitute an image output means. Regarding the above process unit 14,
This will be described further below.

The upper support frame 6 further includes the process unit 14.
Irradiation lamp 42 and reflection plate 44 located above
, and an optical system consisting of SELFOC Micro Lens (trade name) 46 and the like. Light from the irradiation lamp 42 passes through the transparent plate 12 and irradiates the document placed thereon, as shown by the dashed line. The reflected light from the original is transmitted through the SELFOC microlens 46 and the unit frame 20.
The light is projected onto the circumferential surface of the photoreceptor drum 26 in an exposure area 52 through an exposure opening 50 formed in the upper wall 48 .

At the center of the lower support 4 is a transfer device (
The transfer corona discharger) 56 and the stripping static eliminator 587''') located downstream thereof are removed.

At the right end of the lower support 4, there is provided a copy paper supply means, generally indicated by the number 60, and at the left end, there is provided a copy paper tray 6.
2 is provided. A copy paper conveying system 64 for conveying the copy paper through the transfer area 54 is provided between the copy paper supply means 60 and the copy paper tray 62.

The copy paper supply means 60 includes a paper feed tray 66 and a pair of paper feed rollers 68 provided on the downstream side thereof.

Therefore, when copy paper is placed on the paper feed table 66 and inserted through the open lower 2 formed on the right wall 70 of the housing 2 to the paper feed roller pair 68, the paper feed roller rotates in the direction of the arrow. Due to the action of pair 68, copy paper is fed to copy paper transport system 64 through guide plate 74.

The copy paper transport system 64 includes a transport roller pair 76 and a lower guide plate 78.
, a guide member 80, a pair of heating and fixing rollers 82, and a pair of discharge rollers 84. These components define a copy paper transport path 86 that guides the copy paper fed from the copy paper supply means 60 to the copy paper tray 62. A heating means 90 is provided inside the upper and front heat rollers 88 of the heat fixing roller pair 82 .

The unit frame 20 in the process unit 14 is
It has a front wall and a back wall (neither shown) spaced apart in a direction perpendicular to the plane of the paper. The above-described top wall 48, left side wall 102, right side wall 104, and bottom wall 100 are provided between the front wall and the rear wall.

A step is provided at the center of the widthwise beam of the upper wall 48, and the exposure opening 50, which is elongated in the front-rear direction, is formed in the center of the step. In addition, in the widthwise central part of the bottom wall 100,
A transfer opening 110 extending in the front-rear direction is formed. The lower part of the photosensitive drum 26 is exposed to the outside through the transfer opening 110.

A developing device 32 and a cleaning device 34 are provided along with the photosensitive drum 26 between the front wall and the rear wall of the unit frame 20.

The photosensitive drum 26 is rotatably supported between the front wall and the rear wall via shaft portions (not shown) provided at both ends thereof. The upper support frame 6 at the rear of the rear wall of the unit frame 20 (at the back in the direction perpendicular to the paper) is provided with a rear board extending vertically, and a gear is rotatably installed on the rear board. (none shown). The details of the photoreceptor drum 26 are drivingly connected to the above-mentioned gear via a clutch means (not shown) when the unit frame 20 is mounted on the upper support frame 6 and set in the operating position.

This gear is connected to a drive source (not shown) via another gear (not shown). When each gear is rotated by this drive source, the photosensitive drum 26 is rotated in the direction shown by an arrow 28.

In the electrostatic copying machine configured as described above, while the photosensitive drum 26 is rotationally driven in the direction shown by the arrow 28,
The charging device 30 substantially uniformly charges the photoreceptor of the photoreceptor drum 26 to a specific polarity, for example, a positive polarity. Next, in the exposure area 52, the image of the original on the transparent plate 12 is projected onto the photoreceptor through the exposure aperture 50 by the optical system, and a charged area corresponding to the image of the original, that is, an electrostatic latent, is formed on the photoreceptor. An image is formed. This electrostatic latent image is developed into a toner image by supplying toner charged to a specific polarity, for example, a negative polarity, from the sleeve mechanism of the developing device 32.

The copy paper supplied from the copy paper supply means 60 and conveyed by the copy paper conveyance system 64 is brought into close contact with the circumferential surface of the photoreceptor drum 26 in the transfer area 54, and by the action of the transfer device 56, the copy paper is transferred onto the photoreceptor drum 26. The toner image is transferred onto the copy paper. Next, by the action of the stripping static eliminator 58,
The copy paper is peeled off from the photosensitive drum 26.

The peeled copy paper is conveyed through a pair of heating and fixing rollers 82, and the toner image on the copy paper is heated and fixed. The copy paper with the toner image fixed thereon is passed through an opening 94 in the left wall 92 of the housing 2 by a pair of ejection rollers 84 and delivered to the copy paper tray 6.
2.

- The photoconductor drum 26 continues to rotate further, and toner remaining on the photoconductor after transfer is removed by the action of the elastic blade 38 of the cleaning device 34. The removed toner is collected into the toner collection chamber 40.

The process unit 14 is configured to process the nozzling 2 as described above.
It is removably installed inside. For this attachment and detachment, the process unit 14 is provided with a known handle (not shown), and is also provided with a suitable locking means between it and the rear substrate within the housing 2. Therefore, if a trouble occurs in the image output means such as a photosensitive drum provided in the process unit 14, or if a predetermined life span is reached, the process unit 14 can be easily replaced with a new one.

[Problem to be solved by the invention]

The above-mentioned conventional electrostatic copying machine having the process unit 14 removably mounted within the housing 2 is generally provided with a device for detecting the lifespan of the process unit 14.

As a device for detecting the lifespan of the process unit 14, a built-in counter type, a toner recovery amount detection type, and the like are known.

The built-in counter method detects the lifespan by counting the number of copies. In this method, −
When a large number of sheets of small-sized copy paper are used, in which the amount of toner used per sheet is relatively small, the amount of toner stored (remaining amount) in the developer container of the developing device 32 is sufficient. Nevertheless, the process unit 14 is considered to have reached the end of its lifespan and is replaced, resulting in the process unit 14 being discarded earlier than its actual lifespan.

Therefore, this method is inaccurate as a lifespan detection device and results in a large amount of waste.

The toner collection amount detection method is a method for detecting the lifespan by detecting the amount of toner collected in the toner collection device. In this method, if the rate of toner transfer to the copy paper becomes excessive for some reason, the amount of toner collected reaches a predetermined amount faster than the normal pace, and as with the previous method, the amount of toner in the developer container is reduced. Even though the storage capacity is sufficient, the process unit 14 is considered to have reached the end of its lifespan and is replaced, resulting in it being discarded earlier than its actual lifespan. Therefore, this method is also inaccurate as a lifespan detection device and results in a great deal of waste.

In general, it is considered most desirable that the life of the process unit 14, ie, the time for replacement, be when the toner in the developer container is fully used up. For this purpose, the best method is to directly detect the amount of toner contained (remaining amount) in the developer container to detect its lifespan.

Therefore, devices have been known that detect the amount of toner contained in the developer container by measuring the concentration of toner in the developer container. However, there are some cases where the measured toner density and the amount of toner contained do not necessarily match due to variations in density measurement. Therefore, this method is also inaccurate as a lifespan detection device and cannot be said to be practically suitable.

On the other hand, in general electrostatic copying machines that are not equipped with the above-mentioned process unit, when a predetermined amount of toner in the developer container is used up, it is time to replenish the toner, and it also indicates that it is time for maintenance of the copying machine. In some cases.

For any type of electrostatic copying machine, for the above reasons,
Although there is a desire for a device that directly detects the amount of toner contained in the developer container, the reality is that it has not yet been realized.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a toner storage amount detection device that can directly, relatively easily and reliably detect the amount of toner contained in a developer container.

[Failure to solve the problem]

In order to achieve the above object, according to this publication, in an image generating apparatus having an image output means including a photosensitive drum rotatably supported within a support structure and a developing device, the image generating device is housed in a developing container of the developing device. A transparent electret having the same polarity as the toner is provided so as to constitute a part of the inner wall surface of the developer container, and a transparent electret having the same polarity as the toner is provided near the electret to accommodate the toner in the developer container via the electret. An optical sensor is installed to detect the amount.
An image generation device characterized by:

[Effect]

In the image generating device, a transparent electret having the same polarity as the toner contained in the developing container of the developing device,
An optical sensor is provided so as to constitute a part of the inner wall surface of the developer container, and is disposed near the electret to detect the amount of toner contained in the developer container via the electret.

As is well known, an electret is a charged body that generates an electric field semi-permanently outside and has electric polarization characteristics. The surface of the electret, which forms part of the inner wall surface of the developer container, is held at the same polarity as the toner (for example, negative polarity), so the toner is electrically repelled and does not adhere to the surface.

When the amount of toner contained in the developer container is large, the level in the container is at a high position beyond the portion where the electret is provided. The toner is filled in the developer container so as to cover the entire surface of the electret facing inward of the developer container. Since the electret is transparent, the same portion appears as black toner from outside the developer container. This state is detected by an optical sensor placed nearby, indicating that the amount of toner contained in the developer container is sufficient.

As the copying machine is used, the amount of toner contained in the developer container gradually decreases and its level drops. Finally, it will be at a lower position than the electret part. The black color of the toner disappears from the transparent electret portion, and the transparent electret portion appears while remaining transparent. This is because the toner in the developer container does not adhere to the surface of the electret as described above. This state is detected by the optical sensor as indicating that the amount of toner contained in the developer container has reached a predetermined remaining amount.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 3.

In FIG. 1, numeral 120 indicates a developing device, and a toner 124 as a developer is stored inside a developing container 122 of the developing device. The toner 124 is a component non-magnetic toner, and is triboelectrically charged to a specific polarity, for example, a negative polarity, by a stirring roller (not shown) disposed in the developer container 122 . The developer container 122 is integrally molded from synthetic resin, and a convex portion 126 that protrudes outward is provided at a lower position of a side wall portion of the developer container 122 . The convex portion 126 has an upright cube shape in this example. A concave portion (space) along the convex portion 126 is formed inside the convex portion 126, and constitutes a part of the inner wall surface of the developer container 122. The convex portion 126 is connected to the developer container 122.
It may be integrally molded with or attached separately, but it must be made of a transparent member. The bottom wall of the protrusion 126 is sloped downward so that the toner filled in the internal space of the protrusion 126 can be smoothly discharged as the amount of toner stored in the developer container 122 decreases. This is desirable.

A film-like electret E is attached to each inner wall surface of the convex portion 126 with an adhesive.

Transparent members are selected for both Electret) E and the adhesive.

As described above, the electret is a charged body that semipermanently generates an electric field outside, has electric polarization characteristics, and is known to be formed from various polymeric materials. Electret E in this example is a film made of a copolymer of tetrafluoroethylene and hexafluoropropylene, which is suitable for having stable polarization characteristics, and is formed by a known electretization method.

Examples of the electret-forming means include applying a DC high voltage at high temperature to both sides of the film under predetermined conditions and then cooling it to room temperature to obtain an electret with different surface charges on both sides; A suitable method is to perform a corona discharge treatment on the surface of the film so that charges are trapped on the surface to generate electrets.

The transparent film-like electret (electret) E thus made into an electret is shaped into an appropriate shape so that it can be attached to substantially the entire surface of each inner wall surface (five surfaces in the illustrated example) of the convex portion 126. , are attached using adhesive (see the shaded area in the figure). The electret E constitutes a part of the inner wall surface of the developer container 122, and the surface of the inner wall surface exposed inside the developer container 122 is the toner 124.
It is important that it is attached to the inner wall surface of the convex portion 126 so that the polarity is the same as that of the convex portion 126 . It is also conceivable that the convex portion 126 itself be made of electret E. In this case too,
It is important that the surface on the inner wall side be positioned to have the same polarity as the toner 124.

An optical sensor 128 is arranged near the electret E. Specifically, the sensor 128 is a transmission type detector in which a light-emitting element and a light-receiving element face each other, and the light-receiving element directly detects light from the light-emitting element.

The sensor 128 has a light emitting element 128a and a light receiving element 1.
28b are arranged to face each other with the front protrusion 126 in between.

In the illustrated example, the developing device 120 is provided in a copying machine that does not include a process unit.

When the developing device 120 is provided within the unit frame 20 of the process unit 14 shown in FIG.
8 is preferably provided outside the unit frame 20. In this case, the developing device 120 is the process unit 14
Since they are also attached to and detached from the copying machine, it is necessary to consider the form and arrangement of the protrusion 126 and the sensor 128 so as not to interfere with their attachment and detachment operations. For example, developer container 12
2 as part of the unit frame 20, for example, ABS resin,
It is conceivable to integrally mold it with nylon resin, vinyl chloride resin, etc. In that case, the wall of the developer container 122, and therefore the convex portion 126,
), and the sensor 128 is disposed outside the unit frame 20 so as to sandwich the convex portion 126 from above and below.

When the process unit 14 is removed from the copying machine, the sensor 128 is left on the copying machine side. Furthermore, when the process unit 14 is installed in a copying machine, the convex portion 126 is configured to be in the set position with respect to the sensor 128.

When the developing container 122, which is separate from the process unit 14, is provided within the process unit 14, that is, the unit frame 20, the unit frame 20 should be provided with a window hole or a transparent portion through which light can pass. is necessary.

When the amount of toner 124 contained in the developer container 122 is large, the level in the container 122 is at a high position beyond the convex portion 126 provided with the electrons ()E. The toner 124 is also filled in the convex portion 126 . That is, the toner 124 is filled in the developer container 122 so as to cover the entire surface of the electron (electron) E facing inward of the convex portion 126 . Since the convex portion 126 containing the electret E is transparent, the same portion cannot be seen from the outside of the developer container 122.
It appears as the black color of the toner filled inside.

This state is detected by the sensor 128 as indicating that the amount of toner 124 contained in the developer container 122 is sufficient.

As the copying machine is used, the toner 124 in the developer container 122 is removed.
The carrying capacity of will gradually decrease and its level will decline. Finally, the position is lower than the convex portion 126. The inside of the convex part 126 that had been filled with the toner 124 became empty, the black color of the toner 124 disappeared from the part of the convex part 126 containing transparent electrons) E, and the part of the transparent convex part 126 was kept in a transparent state. It is expressed in the state. This is because the toner 124 in the developer container 122 does not adhere to the surface of the electret E as described above. This state is
The sensor 128 detects that the amount of toner 124 contained in the developer container 122 has reached a predetermined remaining amount.

By connecting the sensor 128 to a known warning means (for example, an alarm lamp or a buzzer (none of which are shown)), the detection result can be used to indicate when it is time to replenish toner, when it is time for maintenance of the copying machine, or when the process unit 14 It can be notified as the lifespan (replacement time).

In the above embodiment, the electron) E is the convex portion 126
Although the sensor 128 is provided on each inner wall surface of the sensor 128, the purpose can be achieved if the sensor 128 is provided at least on a portion of the wall through which the light of the sensor 128 passes (in the figure, the left and right opposing walls). but,
The wider the installation surface of the electret E, the greater the repulsion effect on the toner, which is advantageous in improving the detection function.

2 and 3 show another embodiment of the present invention, in which a toner 1 is stored in a developing container 132 of a developing device 130.
34 are accommodated. The toner 134 is a one-component non-magnetic toner, and is replenished from the hot spring <-136. The toner 134 in the developer container 132 is conveyed toward the sleeve 142 while being triboelectrically charged (for example, negatively charged) by stirring rollers 138 and 140 .

The developer container 132 is integrally molded from synthetic resin, and a rectangular window hole 144 is formed at the lower side of the side wall thereof. A transparent film-like resin film E is attached to the inner wall surface of the developer container 132 with an adhesive so as to cover the window hole 144. The electret (electret) E constitutes a part of the inner wall surface of the developer container 122. The electret E may also be configured by being attached to the surface of a transparent plate member serving as a base, and may be attached from inside the window hole 144 in the same manner as described above. If the developer container 122 is made of a transparent member, the electret E may be directly attached to the inner wall surface of the developer container 122 without forming the window hole 144.

A reflective member 143 is attached to the inner wall surface of the developer container 122 at the position where the window hole 144 is formed. The reflective member 143 is composed of a white synthetic resin plate, an iron plate, or a synthetic resin plate painted with white paint. The reflective member 143 also has a parallel portion on the inner wall surface at a predetermined interval inside the window hole 144, and the end thereof is bent into an L shape and fixed by adhesive or screws. It is attached. of the reflective member 143,
On the inside facing the window hole 144 (two sides in this example),
A transparent film-like electret E similar to that described above is attached with an adhesive.

In this case as well, it can be said that the electret E constitutes a part of the inner wall surface of the developer container 122.

Electret) E constitutes a part of the inner wall surface of the developer container 132, and is positioned so that the surface of the inner wall surface exposed inside the developer container 132 has the same polarity as the toner 134 (for example, negative polarity). is important.

In this example, the developing device 130 is provided within the unit frame 20 of the process unit 14 shown in FIG. Of course, the wall of the developer container 132 may be formed integrally with the wall of the unit frame 20, as described in the embodiment of FIG. The conditions in that case are the same as above.

An optical sensor 146 is arranged near the electret E. Sensor 146, in this example,
A reflection type detector is used that illuminates the surface of the electret E with light from a light emitting element and detects the reflected light with a light receiving element.

In this example, the sensor 146 is provided outside the unit frame 20 in the same way as described in the embodiment of FIG. The conditions in that case are the same as above.

When the amount of toner 134 contained in the developer container 132 is large, the level in the container 132 is at a high position beyond the window hole 144 provided with the electret (E). The toner 134 is filled in the developer container 132 so as to cover the entire surface of the electret E located inside the window hole 144. Since Electret) E is transparent, the same portion can be seen from the outside of the developing container 132 as the black color of the toner filled inside through the window hole 144. In this state, the sensor 146 detects that the toner 1 in the developer container 132 is
The storage capacity of 34 is detected to be sufficient.

As the copying machine is used, the toner 134 in the developer container 132 is removed.
The carrying capacity of will gradually decrease and its level will decline. Finally, the position is lower than the window hole 144. The inner vicinity of the window hole 144 that had been filled with the toner 134 is now empty, the black color of the toner 134 disappears from the window hole 144 and the transparent electret E, and the transparent electret E is maintained in a transparent state. It appears in a state of being The surface of the electret E is provided with the developer container 1 as described above.
This is because the toner 134 in 32 does not adhere. This state is detected by the sensor 146 as indicating that the amount of toner 134 contained in the developer container 132 has reached a predetermined remaining amount. That is, since the toner 134 that was blocking the light from the sensor 146 is gone, the light is reflected by the white reflective member 143.

It is important that the toner 134 in the space between the reflective member 143 and the window hole 144 is always maintained at a level that accurately captures the amount of toner 134 contained in the developer container 132. Various modifications can be made to this effect, such as a configuration in which the upper part of the reflecting member 143 is not closed.

By connecting the sensor 146 to a known warning means, such as an alarm lamp or a buzzer (none of which are shown), the detection results can be transmitted to the process unit 14.
It can be notified as the lifespan (replacement time).

It goes without saying that the pair of developing device 130 and sensor 146 can also be applied to general copying machines that are not equipped with a process unit.

〔Effect of the invention〕

According to the present invention described above based on the embodiments, it is possible to obtain a toner accommodation amount detection device that can directly, relatively easily and reliably detect the amount of toner accommodation in the developer container. You can get an effect like this.

(1) It is possible to accurately determine the timing of toner replenishment or maintenance of the image generating device. As a result, the image generation device can be used with maximum efficiency, thereby extending the life of the image generation device and
Significantly improves its reliability.

(2) When the above-mentioned toner accommodation amount detection device is provided in an image generating apparatus equipped with a process unit, it is possible to accurately determine the lifespan of the process unit. As a result, the process unit can be used with maximum efficiency without waste, thereby significantly improving the reliability of the image generating apparatus.

(3) The toner content detection device described above is composed of a transparent electret and a known optical sensor, so it can be easily implemented in the developer container, and a highly reliable detection function can be obtained, and its practical value is Extremely expensive.

Although the present invention has been described in detail based on the embodiments above, the present invention is not limited to the embodiments described above, and various modifications and modifications can be made within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing another embodiment of the invention. FIG. 3 is a perspective schematic diagram showing a part of FIG. 2; FIG. 4 is a schematic cross-sectional view of a conventional electrostatic copying machine equipped with a process unit. 14...Process unit 20...Unit frame 120.130...Developing device 122.132...Developing container 124.134...Toner 126...
・Convex portion 128.146...Optical sensor 143...
・Reflective member E...Electret

Claims (1)

[Scope of Claims] 1. In an image generating device having an image output means including a photosensitive drum rotatably supported within a support structure and a developing device, the toner contained in the developing container of the developing device is the same as the toner contained in the developing container of the developing device. A transparent electret having polarity is provided so as to constitute a part of the inner wall surface of the developer container, and an optical device is provided near the electret to detect the amount of toner contained in the developer container via the electret. A toner storage amount detection device characterized by being equipped with a type sensor. 2. The image generating device includes a unit frame detachably mounted within the support structure, and the image output means including the photosensitive drum and the developing device rotatably supported by the unit frame. Claim 1: A process unit is provided, and the electret and the optical sensor are provided to detect the amount of toner contained in a developing container of the developing device in the process unit.
The toner capacity detection device described.