JP2001109250A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically detect which is selected a toner recycling type or a toner recovering type and to apply a toner concentration control according to the selected type by considering that the control method for the toner concentration is different when either of the types is applied to an image forming device of an electrostatic copying method. SOLUTION: Relating to this device, which is applied the toner recycling type or the toner recovering type is discriminated by detecting attachment or detachment of a toner recovering tank recovering toner through an opening formed in a middle part of a toner carrying path communicating a cleaning device and a developing device by a detecting switch 90, so that a toner concentration reference value in the toner concentration control of the developing device is varied according to the judged result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic copying type image forming apparatus for recording an image on a sheet using toner.

[0002]

2. Description of the Related Art In an electrostatic copying type image forming apparatus, for example, an electrostatic latent image is formed on a drum-shaped photosensitive member, and this electrostatic latent image is developed into a toner image by a developing device. The image is formed by being transferred to the surface. The image forming apparatus further includes a cleaning device for removing residual toner on the surface of the photoconductor.

[0003] In this image forming apparatus, a toner recovery system is generally employed in which toner discharged from a cleaning device is collected in a toner recovery tank and collected and discarded. However, the toner discharged from the cleaning device is sent to a developing device. There is also known a recycle type image forming apparatus which conveys and reuses it for image formation. The image forming apparatus employing this recycling method can reduce the toner cost because the toner can be reused.However, since the recovered toner is often inferior in chargeability and contains fine paper powder, it is used. The image quality of the toner image is slightly deteriorated as compared with the image forming apparatus employing the toner collection method. As described above, the recycling method has advantages and disadvantages.
The image forming apparatus is selected according to the user's preference whether to give priority to cost. In recent years, user demands have been diversified, and it is preferable that one image forming apparatus can appropriately select a toner collection method or a recycling method.

Therefore, there has been known an image forming apparatus in which a single image forming apparatus can appropriately select a toner collecting method or a recycling method (for example, Japanese Patent Laid-Open No. 10-32606).
No. 9).

[0005]

However, the method of controlling the toner density differs between the two methods. In the toner recycling method, the returned non-transferred toner has fine particles, is inferior in chargeability, and is mixed with paper powder. Therefore, if the toner sensor is controlled to maintain the toner density at a normal target value, the number of toner particles relatively increases and the image density tends to increase. Therefore, it is necessary to control so as to lower the toner density of the developing device.

On the other hand, in the toner recovery method, since the toner is always new and the charge amount is also appropriate, control may be performed to maintain the toner concentration of the developing device at a normal target value. As described above, the control method of the toner concentration is different depending on the toner recycling method or the toner collecting method. Therefore, when selecting a new method, it is necessary to switch or exchange control software.
If the user forgets to switch or replace the control software, a defect occurs in the image.

However, it is time-consuming and troublesome for a serviceman to switch or exchange control software. Accordingly, it is an object of the present invention to realize an image forming apparatus capable of automatically detecting which method is selected and adopting toner density control according to the selected method. Also, a part of the toner discharged from the cleaning device is collected and discarded, and the rest is reused.
A mixed form of the toner recycling method and the toner collection method is also conceivable. In this case, the ratio of the toner to be collected and discarded is referred to as a “toner collection method adoption ratio”, and the ratio of the toner to be reused is referred to as a “toner recycling method adoption ratio”. The sum of the “ratio” and “the adoption ratio of the toner recycling method” is always 1).

[0008] Also in this case, according to the adoption ratio of both types,
It is preferable to change the method of controlling the toner concentration. Accordingly, an object of the present invention is to realize an image forming apparatus that can automatically detect the adoption ratio of both types and adopt toner density control according to the adoption ratio.

[0009]

According to the present invention, there is provided an image forming apparatus, comprising: a photosensitive member having an electrostatic latent image formed on a surface thereof; and a developing device for developing the electrostatic latent image on the photosensitive member surface into a toner image. Device, a cleaning device for removing residual toner on the surface of the photoconductor, and a toner conveying path that communicates the cleaning device and the developing device, and determines whether a toner collection method or a toner recycling method is selected. The image forming apparatus includes a method detecting means for detecting, and a reference value changing means for changing a toner density reference value in toner density control of the developing device according to a detection result of the method detecting means.

According to the above configuration, it is possible to automatically detect which of the toner recovery system and the toner recycling system is selected, and to perform the optimum toner density control according to the selected system. Therefore, a proper and high-quality image can always be obtained. The image forming apparatus has an opening formed in the middle of the toner conveyance path, a toner collection tank mounting section for mounting a toner collection tank that collects the toner removed by the cleaning device through the opening, An opening opening / closing mechanism for opening an opening when the toner collection tank is mounted on the collection tank mounting portion and closing the opening when the toner collection tank is not mounted to the toner collection tank; It may detect whether or not the collection tank is attached (claim 2).

According to the present invention, when the toner collection tank is not mounted, the opening formed in the toner conveyance path is closed, and the toner discharged from the cleaning device is not conveyed to the toner collection tank, and the toner is not developed. Conveyed to the device.
Further, when the toner collection tank is mounted, the toner discharged from the cleaning device is transported to the toner collection tank because the opening is opened. Therefore, by detecting whether the toner recovery tank is mounted or not, it is possible to know whether the toner recovery method or the recycling method is selected.

According to a third aspect of the present invention, there is provided an image forming apparatus according to the first aspect.
In the image forming apparatus described in the above, an opening formed in the middle of the toner conveying path, a toner collection tank mounting portion for mounting a toner collection tank that collects the toner removed by the cleaning device through the opening, And an opening and closing means for opening and closing the opening, wherein the system detecting means detects an opening and closing state of the opening. In this configuration, the open / closed state of the opening is directly detected instead of detecting the mounting / non-mounting of the toner recovery tank.

A drive unit for driving the opening / closing means and an operating unit for operating the driving unit are further provided, and the system detecting means detects the opening / closing state of the opening based on a control signal from the operating unit. Good (claim 4). According to the present invention, a control signal from an operation unit that operates a drive unit is used to detect the open / closed state of the opening. An image forming apparatus according to claim 5, wherein a photosensitive member on which an electrostatic latent image is formed, a developing device for developing the electrostatic latent image on the photosensitive member surface into a toner image,
A method adoption ratio detecting means, comprising: a cleaning device for removing residual toner on the surface of the photoreceptor; and a toner conveying path communicating the cleaning device and the developing device, and detecting an adoption ratio of a toner collection method and a toner recycling method. And a reference value changing means for continuously or stepwise changing the toner density reference value in the toner density control of the developing device according to the detection result of the system adoption ratio detecting means.

According to this configuration, the toner density control can be performed by continuously or stepwise changing the toner density reference value in the toner density control in accordance with the ratio between the toner recovery method and the toner recycling method. . Therefore, when the user can arbitrarily select a mixed mode of the toner recycling method and the toner collection method, it is possible to perform optimal control according to the method adoption ratio. An opening formed in the middle of the toner conveying path, a toner collection tank mounting portion for mounting a toner collection tank for collecting the toner removed by the cleaning device through the opening, and an opening degree of the opening. The system adoption ratio detecting unit may further include an opening degree changing unit that detects an opening degree of the opening (claim 6).

If the opening formed in the middle of the toner conveying path is completely open, most of the toner removed by the cleaning device is collected in the toner collecting tank, and the opening is completely closed. If they are all recycled. Therefore, the system adoption ratio can be estimated from the opening degree. A drive unit for driving the opening / closing unit and an operation unit for operating the drive unit are further provided, and the system adoption ratio detection unit detects the opening / closing degree of the opening based on a control signal from the operation unit. (Claim 7). Thus, the control signal from the operation unit that operates the drive unit can be used to detect the degree of opening of the opening.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic longitudinal sectional view for explaining the internal structure of the image forming apparatus 1. The image forming apparatus 1 is a multifunctional device that is basically used as a copying machine and can also be used as a printer or a facsimile. The image forming apparatus 1 includes a photosensitive drum 3 in a housing 2. Photoconductor drum 3
, A developing device 5 for developing the electrostatic latent image formed on the surface of the photosensitive drum 3 into a toner image, and a main charger 4 for causing the surface of the photosensitive drum 3 to have a constant potential. A cleaning device 6 for removing toner remaining on the surface of the photosensitive drum 3 is provided. In this embodiment, the photosensitive drum 3, the main charger 4, the developing device 5, and the cleaning device 6
Are integrated as an image forming unit 7 and are detachably mounted in the housing 2. Further, the toner is supplied to the developing device 5 of the image forming unit 7.
Is detachably mounted. Reference numeral 65 denotes a toner supply roller that is driven when supplying toner to the developing tank of the developing device 5. Although not shown, a toner supply motor that drives the toner supply roller 65 is also provided.

A toner sensor 6 for detecting the magnetic permeability μ of the developer (toner and carrier) in the developing tank of the developing device 5
2 are provided. A paper feed tray 9 is housed in the main body housing 2. The paper P placed in the paper feed tray 9 is taken out one by one and transported between the photosensitive drum 3 of the image forming unit 7 and the transfer roller 10 in contact with the photosensitive drum 3. The toner image on the surface of the photoconductor drum 3 is transferred to the paper P by passing the paper P between the photoconductor drum 3 and the transfer roller 10.

The sheet P on which the toner image has been transferred is placed on a fixing device 1.
It is transported to 1. The fixing device 11 includes a pair of rollers 12, and the sheet P passes between the pair of rollers 12 so that the toner image transferred to the sheet P is fixed on the sheet P. The sheet P on which the toner image has been fixed is conveyed to the sheet discharge tray 13. FIG. 2 is a perspective view illustrating a configuration of the image forming unit 7. On the bottom surface of the housing 14 on one end 7a side of the image forming unit 7, a toner collecting tank mounting portion 16 for mounting a toner collecting tank 15 for collecting the toner discharged from the cleaning device 6 is provided. FIG. 2 shows a mounted state of the toner collection tank 15.

FIG. 3 is a cross-sectional view of the main part around the image forming unit 7 when mounted in the housing 2 as viewed from above. The housing 55 of the developing device 5 includes a developing roller 17, an auxiliary roller 18 that supplies developer to the developing roller 17, and a supply unit 53 that supplies toner to the developing roller 17 and the auxiliary roller 18. I have. In the supply section 53, two development conveyance spirals 19 extending in parallel with the photosensitive drum 3 are attached.

A cleaning conveying spiral 22 is mounted in the housing 20 of the long cleaning device 6, and one end 22 b of a rotating shaft 22 a protrudes from one end 3 a of the photosensitive drum 3. A toner outlet 21 is formed on the bottom surface of the housing 20 of the cleaning device 6 on one end 20a side. On one end 7 a side of the image forming unit 7, a toner conveying path 23 that communicates the toner discharge port 21 of the cleaning device 6 with the developing device 5 is provided. A rotating shaft 25 extending in the same direction as the toner conveying path 23 extends in the toner conveying path 23.
And a transfer spiral 24 having a spiral spiral blade 26 projecting from the rotation shaft 25.

An opening 27 is provided in the middle of the toner conveying path 23.
Are formed. When the toner collecting tank 15 is mounted, the toner collecting tank 15 is disposed below the opening 27. On the other end 2b side of the housing 2 of the image forming apparatus 1,
There is a drive mechanism 56 for rotationally driving the photosensitive drum 3, various rollers 17, 18, and various transport spirals 19, 22, 24. The drive mechanism 56 includes the motor 28 and a plurality of gears linearly combined along the housing 2.

The image forming unit 7 includes gears 30 and 3 connected to the developing roller 17, the auxiliary roller 18, and the two rotating shafts of the two developing and conveying spirals 19 and 19, respectively.
1, 32, 33, and these gears 30,
Reference numerals 31, 32, and 33 are driven by the driving mechanism 56, and are linearly combined on the other end 7b side of the image forming unit 7. Further, a gear 34 driven by a driving mechanism 56 is provided on the other end 22c side of the rotating shaft 22a of the cleaning transport spiral 22.

Further, a gear 57 is provided on one end 22b side of the rotating shaft 22a of the cleaning transport spiral 22. The gear 57 is connected to the gear 35A through gears 58 and 59. These gears 57,
58 and 59 are linearly combined on one end 7a side of the image forming unit 7. The gear 35A
It engages with a gear 35B provided on the rotating shaft 25 of the transport spiral 24.

With the image forming unit 7 mounted in the housing 2 of the image forming apparatus 1, the gears of the drive mechanism 56 and the gears 30 and 34 are connected. By these,
The gear 29 connected to the motor 28 includes gears 30, 31,
32, 33 and the gear 34, and the gear 35B is geared with the gear 57. When the motor 28 is driven, the developing transport spiral 19 and the cleaning transport spiral 22 rotate, and the toner supplied from the toner cartridge 8 into the developing device 5 is rotated by the rotating developing transport spiral 19 as indicated by an arrow B in FIG. The toner remaining on the photosensitive drum 3 removed by a cleaning blade or the like (not shown) is transported toward the toner discharge port 21 by the cleaning transport spiral 22 of the cleaning device 6 as shown by an arrow C in FIG. .

The cleaning transport spiral 22
Of the transport spiral 2 in the toner transport path 23 with the rotation of
The rotation shaft 25 rotates, and the toner discharged from the toner discharge port 21 is conveyed to the developing device 5 in the direction of arrow E. As described above, the cleaning transport spiral 22 and the transport spiral 24 can be driven by the single motor 28, so that an extra drive source for rotating the transport spiral 24 is not required.

FIG. 4 is a perspective view of the toner recovery tank 15. The toner collection tank 15 has an opening 36 penetrating the upper surface thereof. 36a is a sealing member. FIG.
5 is a bottom view of the image forming unit 7 for explaining the toner collecting tank mounting section 16. FIG. The toner collecting tank mounting section 16 includes a shutter 38 that can slide in the horizontal direction, and a spring 39 that biases the shutter 38 rightward as shown in FIG. Further, a projection 40 is provided on the left end of the shutter 38 shown in FIG. Since the shutter 38 is biased, the opening 27 is covered by the shutter 38 when the toner collection tank 15 is not mounted, as shown in FIG. The shutter 38 has a substantially rectangular through hole 41 formed therein.
When sliding to the left as shown in FIG. 2B, the opening 27 and the through hole 41 of the shutter 38 overlap. Thus, the opening 27 is opened.

The image forming unit 7 is provided with a detection switch 60 for detecting whether or not the toner collection tank 15 is mounted by whether or not the contact 61 contacts the projection 40. The configuration of the electric circuit that processes the detection signal of the detection switch 60 will be described later. FIG. 6 and FIG. 7 are diagrams illustrating the manner in which the toner collection tank 15 is mounted on the toner recovery tank mounting section 16.

As shown in FIG. 6, the toner collection tank 15
Is mounted by sliding in the direction of arrow D. When mounted on the toner recovery tank mounting section 16, the toner recovery tank 15 is held by other components from below. For this reason, the toner collection tank 15
With the image forming unit 7 mounted in the housing 2, the image forming unit 7 can be mounted and fixed to the toner collection tank mounting portion 16. An elastic claw 42 is provided at one end 16 a of the toner collection tank mounting portion 16. The elastic claw 42 includes an operation unit 51, and by operating the operation unit 51, the elastic claw 42 can be displaced upward / downward. With the elastic claws 42 positioned below,
The state in which the toner recovery tank 15 is mounted on the toner recovery tank mounting portion 16 can be maintained.

Next, a method for mounting the toner collecting tank 15 to the toner collecting tank mounting section 16 will be described. First, the elastic claw 42 is displaced upward by the operation of the operation section 51 to position the toner collection tank 15 between the toner collection tank mounting section 16 and other parts, and then the arrow D shown in FIGS. Slide in the direction of. Then, one side surface of the toner collection tank 15 is engaged with the protrusion 40.
When the toner collection tank 15 is further slid, the shutter 38 slides in the direction of arrow D in conjunction with the slide of the toner collection tank 15. When the toner collection tank 15 is slid by a predetermined amount, as shown in FIG. 7, the attachment of the toner collection tank 15 to the image forming unit 7 is achieved, and the elastic claws 42 are displaced downward. When the toner collection tank 15 is mounted, the opening 27 is opened, and the opening 27 and the toner collection tank 15 are opened.
Overlaps with the opening 36.

Then, as shown in FIG. 7, when the contact 61 of the detection switch 60 comes into contact with the projection 40 and is pushed in, the attachment of the toner recovery tank 15 is detected. FIG.
FIG. 4 is a sectional view of an essential part taken along a cutting line AA in FIG. 3. In FIG. 8, the transport spiral 24 is omitted. The toner conveying path 23 is inclined downward toward the end in the direction of arrow E shown in FIG. For this reason, the toner discharged from the cleaning device 6 can be favorably conveyed to the toner collection tank 15 or the developing device 5.

The toner recovery tank 15 shown in FIG.
In the state where is not mounted, since the opening 27 is closed, all the toner discharged from the cleaning device 6 and transported through the toner transport path 23 is transported to the developing device 5 without being transported to the toner collection tank 15. Also, the toner collection tank 1
8 (b) in which No. 5 is mounted on the toner recovery tank mounting portion 16
In the state (1), the opening 27 is opened and the opening 27 overlaps the opening 36, so that the toner discharged from the cleaning device 6 and conveyed through the toner conveying path 23 is conveyed to the toner collecting tank 15, and the toner collecting tank 15 Is stored in the toner.

Thus, with one image forming apparatus, the toner discharged from the cleaning device 6 is collected in the toner collecting tank 15 and collected and discarded with a simple structure by mounting / non-mounting the toner collecting tank 15. Both a collection method and a recycling method in which the toner discharged from the cleaning device 6 is transported to the developing device 5 and reused for image formation can be selected. FIG. 9 shows an electric configuration of a circuit for detecting whether the toner collection method or the toner recycling method is selected, and changing the toner density reference value in the toner density control of the developing device 5 according to the detection result. FIG.

This circuit includes a central processing unit (CPU) 63 provided in the image forming apparatus 1 and a toner collection tank 15
And a toner sensor 62 for detecting the magnetic permeability μ of the developer in the developing tank of the developing device 5.
And a toner supply motor 64 that drives a toner supply roller 65 that supplies toner to the developing tank of the developing device 5. The operation of the program loaded into the CPU 63 will be described.

The CPU 63 detects which of the toner recovery method and the toner recycling method is selected based on the output signal of the detection switch 60. When the toner recovery method is selected, the toner supply motor 64 is controlled based on the output signal of the toner sensor 62 such that the toner concentration in the developing tank is maintained at a normal target value, for example, 3.5%. Control. Specifically, the toner sensor 6
2 is inversely proportional to the toner density, so if the output voltage of the toner sensor 62 is higher than the reference voltage, the toner supply motor 64 is rotated, and the output voltage of the toner sensor 62 is lower than the reference voltage. For example, the rotation of the toner supply motor 64 is stopped.

However, when the toner recycling method is selected, it is preferable to control so as to reduce the toner density of the developing device as described in [Problems to be Solved by the Invention]. Therefore, in this case, the reference voltage is increased. As a result, the time period during which the toner supply motor 64 rotates decreases, and the toner density can be reduced to a value lower than the normal target value (for example, 3%). In the embodiment described so far, the projection 40 of the shutter 38 engages with the toner collection tank 15 in accordance with the attachment of the toner collection tank 15 to the image forming unit 7, and the opening 2.
7 and the through-hole 41 of the shutter 38 overlap,
Thus, the opening 27 was opened.

However, the attachment of the toner collecting tank 15 to the image forming unit 7 and the opening of the opening 27 may be performed by independent and separate operations. FIG. 10 is a cross-sectional view showing a structure in which the mounting of the toner collection tank 15 to the image forming unit 7 and the opening and closing of the opening 27 are performed independently. In this structure, unlike FIG. 7, the projection 38 is not formed on the shutter 38. According to FIG. 10, after the toner collection tank 15 is mounted, the shutter 27 is manually slid in the direction of arrow F, so that the opening 27 and the through hole 41 of the shutter 38 can be overlapped. As a result, the opening 27 is opened, so that the toner can be collected in the toner collection tank 15.

When the shutter 38 is pulled in the direction opposite to the arrow F, the opening 27 is closed, so that the toner can be transported to the developing device 5. When the shutter 38 is pulled, the toner collection tank 15 does not come out.
A member (a member equivalent to the elastic claw 42 shown in FIG. 6; not shown) for supporting the toner collection tank 15 is provided. Since the position of the shutter 38 can be detected by the detection switch 60, it is possible to detect which of the toner collection method and the toner recycling method is selected based on the output signal of the detection switch 60. By changing the toner density reference value according to the detection result as described above, the toner density of the developing device 5 can be controlled.

In the above description, the shutter 38 is manually slid, but may be mechanically slid by a motor or the like. In this case, the operation unit for operating the drive of the motor or the like may be provided on, for example, an operation panel (not shown) of the image forming apparatus 1. Further, when the shutter 38 is mechanically slid by a motor or the like, it is configured to detect whether the toner collection method or the toner recycling method is selected based on a signal from an operation unit that operates the drive of the motor or the like. You may. Thus, since the detection switch 60 can be omitted, the configuration of the image forming apparatus 1 can be simplified.

Next, an embodiment of the present invention for changing the degree of opening of the opening 27 will be described. FIG. 11 is a view showing the shutter 38 of the toner collection tank mounting portion and its periphery.
The shutter 38 is slidable. When the shutter 38 is manually slid in the direction of the arrow F or in the opposite direction by hand, the opening 27 of the toner conveying path 23 and the shutter 38 are moved.
The degree of overlap with the through hole 41, that is, the degree of opening can be changed. The opening degree can be known, for example, by reading a scale S written near the opening 27 of the toner conveying path 23 through a cursor K provided on the shutter 38. If the read value of the opening degree is input to the CPU 63 using the operation panel, the CPU 63 can control the toner concentration in the developing tank in accordance with the input opening degree.

A specific control method will be described with reference to the graph of FIG. In the graph of FIG. 12, the horizontal axis indicates the aperture (unit%), and the vertical axis indicates the target toner density value (unit%). According to this graph, the toner density value is 3.0% when the opening degree is 0% to 20%, while the opening degree is 2%.
For every 0% increase, the toner density value increases by 0.125%. The CPU 63 stores the data of the control target value of the toner density corresponding to the graph of FIG. 12, and sets the control target value of the toner density according to the input opening degree. Then, the toner concentration is controlled so that the toner concentration in the developing tank reaches the control target value.

As described above, the opening degree of the toner collecting tank mounting portion can be changed from 0% to 100%, and the toner concentration is controlled in accordance with the opening degree. More fine-grained control can be performed as compared with the case where control is performed based on alternatives. In the graph of FIG. 12, the opening degree and the toner density value change in five steps, but the present invention is not limited to this, and a graph in which the degree changes in an arbitrary step can be adopted.

FIG. 13 is a sectional view showing another structure for changing the aperture. According to this structure, the linear gear 71 is formed on the shutter 38, and is driven by the circular gear 72 mounted on the motor 70, whereby the shutter 3 is driven.
8 can be moved in a linear direction. Thus, the degree of opening between the opening 27 of the toner conveying path 23 and the through hole 41 of the shutter 38 can be continuously changed. The control of the rotation direction and the rotation time of the motor 70 is performed by operating the operation panel. Therefore, the operation signal of the operation panel is transmitted to the CPU 63.
, The toner concentration can be controlled such that the toner concentration in the developing tank reaches a control target value corresponding to the opening degree.

Although the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view for explaining an internal structure of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view illustrating a configuration of an image forming unit.

FIG. 3 is a cross-sectional view of a main part around the image forming unit in a state where the main body is mounted in a housing, as viewed from above.

FIG. 4 is a perspective view of a toner collection tank.

FIG. 5 is a bottom view of the image forming unit for explaining a toner collection tank mounting portion.

FIG. 6 is a diagram illustrating a state in which a toner collection tank is mounted on a toner recovery tank mounting portion.

FIG. 7 is a diagram illustrating a state after the toner collection tank is mounted on the toner recovery tank mounting section.

8 is a cross-sectional view of a main part of the toner conveyance path taken along a cutting line AA in FIG.

FIG. 9 is an electrical configuration of a control circuit for detecting whether the toner recovery method or the toner recycling method is selected, and changing a toner density reference value in the toner density control of the developing device 5 according to the detection result. FIG.

FIG. 10 shows an image forming unit 7 of the toner collecting tank 15.
FIG. 7 is a cross-sectional view showing a structure in which mounting to the camera and opening and closing of an opening 27 are performed independently.

FIG. 11 is a view showing a slidable shutter 38 and its periphery.

FIG. 12 is a graph illustrating a method for controlling the toner concentration in the developing tank according to the degree of opening of the opening 27 of the toner conveying path 23.

13A is a cross-sectional view showing a structure for mechanically changing the degree of opening of an opening 27 of a toner conveying path 23, and FIG. 13B is a bottom view of a shutter 38.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Photoreceptor drum 5 Developing device 6 Cleaning device 15 Toner recovery tank 16 Toner recovery tank mounting part 23 Toner transport path 24 Transport spiral 25 Rotary shaft 26 Spiral blade 27 Opening 36 Toner recovery tank opening 38 Shutter 41 Through hole 60 detection switch 62 toner sensor 63 central processing unit (CPU) 64 toner supply motor 65 toner supply roller 70 motor 71 linear gear 72 gear

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DD07 DE04 EA06 2H034 CA01 CA05 CA08 2H077 AA09 AA18 AA37 AC02 AC04 AD06 BA01 DA10 DA24 DA52 DB02 DB22

Claims (7)

[Claims] 1. An electrostatic copying type image forming apparatus for recording an image on a sheet, comprising: a photosensitive member having an electrostatic latent image formed on a surface thereof; and a toner image forming the electrostatic latent image on the photosensitive member surface. A developing device for developing the toner, a cleaning device for removing residual toner on the surface of the photoreceptor, and a toner conveying path communicating the cleaning device and the developing device. An image forming apparatus comprising: a method detecting unit that detects which one is selected; and a reference value changing unit that changes a toner concentration reference value in toner concentration control of a developing device according to a detection result of the method detecting unit. . An opening formed in a middle portion of the toner conveying path; a toner collecting tank mounting portion for mounting a toner collecting tank for collecting the toner removed by the cleaning device through the opening; An opening opening / closing mechanism for opening an opening when the toner collection tank is mounted on the tank mounting portion and closing the opening when the toner collection tank is not mounted on the toner collection tank; 2. The image forming apparatus according to claim 1, wherein the presence or absence of the tank is detected. 3. An opening formed in the middle of the toner conveying path, a toner collecting tank mounting section for mounting a toner collecting tank through which the toner removed by the cleaning device is collected, and the opening. 2. The image forming apparatus according to claim 1, further comprising an opening / closing means for opening / closing the opening, wherein the system detecting means detects an opening / closing state of the opening. 4. A driving unit for driving the opening / closing means, and an operating unit for operating the driving unit, wherein the system detecting means detects an opening / closing state of the opening based on a control signal from the operating unit. The image forming apparatus according to claim 3, wherein: 5. An image forming apparatus of an electrostatic copying system for recording an image on a sheet, comprising: a photosensitive member having an electrostatic latent image formed on a surface thereof; and a toner image forming the electrostatic latent image on the photosensitive member surface. A developing device for developing the toner, a cleaning device for removing residual toner on the surface of the photoconductor, and a toner conveying path communicating the cleaning device and the developing device. Adopting a toner collecting method and a toner recycling method A method for detecting a ratio; a method for detecting a ratio; and a reference value varying means for continuously or stepwise changing a toner concentration reference value in toner concentration control of a developing device according to a detection result of the method to be used. An image forming apparatus comprising: 6. An opening formed in the middle of the toner conveying path, a toner collecting tank mounting section for mounting a toner collecting tank for collecting the toner removed by the cleaning device through the opening, and the opening. 6. The image forming apparatus according to claim 5, further comprising an opening degree changing unit that changes an opening degree of the opening, wherein the method adoption ratio detecting unit detects an opening degree of the opening. 7. A drive unit for driving the opening / closing means, and an operation unit for operating the drive unit, wherein the system adoption ratio detecting means determines an opening / closing degree of the opening based on a control signal from the operation unit. The image forming apparatus according to claim 6, wherein the image is detected.