JPH04323676A - Image forming device - Google Patents

Abstract

PURPOSE:To provide the image forming device where attachment of a toner recovery roll to a developing device is facilitated and the positioning of the toner recovery roll and a developing roll is also facilitated. CONSTITUTION:In the image forming device, the toner recovery roll 22, formed of at least its outer periphery part with an insulator 22c is installed in the vicinity of the actuating positions of an image bearing body 1 and the developing roll 14 of the developing device 3. A member for triboelectrification 23c installed in contact with the outer periphery surface of the toner recovery roll 22 to triboelectrify the outer periphery surface of the toner recovery roll 22 to the polarity reverse to the toner. A bearing fitting chamfer 41 is formed to fit in a bearing 24 of the toner recovery roll 22 to a specified position of a required member of the developing device 3. The toner recovery roll 22 is attached to the developing device 3 in a state of having the bearing 24 of the toner recovery roll 22 fitted to the bearing fitting chamfer 41.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to copying machines, printers,
The present invention relates to an image forming apparatus such as a facsimile machine.

0002

2. Description of the Related Art In a copying machine, an electrode made of a metal rotating roller is provided downstream in the rotating direction of a developing roller of a developing device, and a bias voltage is applied to this electrode to generate an electric field between the developing roller and the electrode. A device has already been developed that prevents image unevenness and fog by attracting toner remaining on the surface of the developing roller and floating toner to an electrode after toner is supplied to the photoreceptor drum (Utility Model Application Publication No. 1-57763).
(see publication).

0003

SUMMARY OF THE INVENTION The conventional device described above has the following problems. (a) A power source is required to apply a bias voltage to the electrodes, which increases cost.

(b) In order to supply voltage to the metal rotating roller electrode, a terminal such as a brush must be used, and the bias tends to become unstable and the terminal must be replaced periodically.

(c) Immediately after the machine stops, when the power is turned off after copying is completed, or when the front door of the copier is opened due to a recording paper jam, etc., no bias is applied to the electrodes, so the electrodes float. The toner cannot be attracted to the electrode.

(d) Metal rotating roller electrodes have high thermal conductivity, so if there is a temperature change during replacement etc., dew condensation will occur on the surface of the metal rotating roller electrodes and will adhere to the metal rotating roller electrodes. The toner melts, and the melted toner is collected in the developing device, which adversely affects the toner.

[0007] Therefore, in order to solve these problems,
The present applicant arranges a toner collection roller, at least the outer periphery of which is made of an insulator, in the vicinity of the action position of the image carrier and the developing roller, in order to frictionally charge the outer periphery of the toner collection roller to a polarity opposite to that of the toner. We have developed an image forming apparatus that triboelectrically charges a toner collection roller by providing a frictional charging member in contact with the outer peripheral surface of the toner collection roller.

The present invention relates to an improvement of the above-mentioned image forming apparatus developed by the present applicant, in which the toner collection roller can be easily attached to the developing device, and the toner collection roller and the developing roller can be easily positioned. The purpose of the present invention is to provide an image forming apparatus.

[0009]

[Means for Solving the Problems] An image forming apparatus according to the present invention includes a toner collection roller whose at least an outer peripheral portion is formed of an insulating material and which is disposed near a position where an image carrier and a developing roller of a developing device act; A frictional charging member is provided in contact with the outer circumferential surface of the toner collecting roller and for frictionally charging the outer circumferential surface of the toner collecting roller to a polarity opposite to that of the toner. A bearing fitting notch for fitting the bearing is formed, and the toner collecting roller is attached to the developing device with the bearing of the toner collecting roller fitted in the bearing fitting notch. do.

The image carrier includes a photosensitive drum, a photosensitive belt, a dielectric drum, and the like. As the toner collection roller, a toner collection roller whose entire body is made of an insulating material, a toner collection roller which is made of a metal roller body and an insulating layer formed on the outer peripheral surface of the metal roller body, etc. are used.

The frictional charging member for frictionally charging the outer peripheral surface of the toner collection roller to a polarity opposite to that of the toner may also be used as a toner scraping member for scraping off the toner suctioned and adhered to the toner collection roller. It is preferable that the toner collection roller and the frictional charging member are attached to the same frame to form a unit.

[0012] A bearing having an oval-shaped bearing part is used as the bearing of the toner collection roller, and the notch for fitting the bearing is formed into a narrow part of the opening whose width is slightly larger than the short axis length of the oval-shaped bearing part and a narrow part. The oval bearing part of the toner collection roller bearing is fitted into the circular part from the narrow part of the notch. The oval shaped bearing portion may be fitted into the circular portion by rotating the bearing portion by a predetermined angle after being inserted.

[0013]

[Operation] In the image forming apparatus according to the present invention, when the toner collection roller is rotated, the frictional charging member and the insulating outer peripheral surface of the toner collection roller rub, and the insulating outer peripheral surface of the toner collection roller is opposite to the toner. Frictionally charged in polarity.

[0014] Therefore, toner scattered from the developing roller or floating toner immediately after the machine stops, when the machine is turned off immediately after copying is finished, when the front door of the copying machine is opened due to a recording paper jam, etc. It is attracted and attached to the collection roller.

Furthermore, a bearing fitting notch for fitting the bearing of the toner collection roller is formed in a predetermined position of a required member of the developing device, and the bearing of the toner collection roller is fitted into the bearing fitting notch. Since the toner collecting roller is attached to the developing device in this state, it is easy to attach the toner collecting roller to the developing device, and it is also easy to position the toner collecting roller and the developing roller.

Furthermore, since at least the outer circumferential portion of the toner collection roller is formed of an insulator, temperature changes may cause
There is no occurrence of dew condensation on the surface of the toner collection roller, and the toner is not adversely affected.

[0017] When the frictional charging member for frictionally charging the outer peripheral surface of the toner collection roller to a polarity opposite to that of the toner also serves as a toner scraping member for scraping off the toner suctioned and adhered to the toner collection roller. In this case, the toner adhering to the toner collecting roller is scraped off by a frictional charging member and returned to, for example, the developing device.

[0018]

Embodiments Hereinafter, embodiments in which the present invention is applied to a copying machine will be described with reference to the drawings.

FIG. 1 shows an image forming section of a copying machine.

Around the photosensitive drum 1, there is a charger 2 for charging the photosensitive layer on the surface of the photosensitive drum, and a charger 2 formed on the photosensitive layer along the direction of rotation (direction indicated by arrow A in FIG. 1). A developing device 3 that makes an electrostatic latent image noticeable as a toner image, a recording paper guide path 4 that guides the recording paper to the photosensitive drum 1, and a transfer device that transfers the toner image formed on the photosensitive layer onto the recording paper. A discharger 5, a separation discharger 6 for separating the recording paper from the photoreceptor drum 1, and a cleaning device 7 for removing toner remaining on the photoreceptor drum 1 after transfer are arranged.

Inside the housing 11 of the developing device 3, there are a developing spiral 12, an agitation roller 13, and a developing roller 14.
are arranged. A toner collection unit 20 is attached to the housing 11 of the developing device 3 .

2 to 4 show the toner collection unit 20. As shown in FIGS.

In the following description, the front refers to the left side of FIG. 3, and the rear refers to the right side of the figure.

The toner collection unit 20 includes a frame 21
, a toner collection roller 22 rotatably attached to the frame 21, and a toner scraping/frictional charging unit 23 attached to the frame 21.

The frame 21 includes a base 21a extending in the length direction of the developing roller 14, and a pair of bearings 21b formed at both ends of the base 21a. The base portion 21a has an upper wall 31 that is substantially parallel to the lower wall of the housing 11 of the developing device 3.
, a lower wall 32 located behind the upper wall 31 and substantially parallel to the upper wall 31 , and a connecting wall 33 connecting the upper wall 31 and the lower wall 32 . The upper wall 31 is provided with a plurality of elongated holes 34 for screw insertion in the front and rear directions at predetermined intervals in the length direction. Elongated holes 35 for screw insertion are formed in both ends of the lower wall 32 in the front and back.

The bearing portion 21b extends from both ends of the upper wall 31.
It is provided to protrude upward and forward, and each bearing part 2
A synthetic resin bearing 24 is attached to 1b so as to pass through it. Each bearing part 24 has two oval parts 24a.
and 24b, both oval shaped parts 24a and 24b.
are connected such that their long axes form a 90 degree angle. The oval portions 24a inside each bearing portion 24 are fitted into oval holes 25 formed in both bearing portions 21b.

The toner collection roller 22 is connected to the photosensitive drum 1.
and the developing roller 14 in the rotational direction of the developing roller 14 (
It is disposed on the downstream side in the direction shown by arrow B in FIG. The toner collection roller 22 has an insulating layer 2 on the entire outer peripheral surface of a metal roller body 22a having a small diameter shaft portion 22b at both ends.
2c is formed by coating. For example, non-magnetic stainless steel is used as the material for the roller body 22a. The material for the insulating layer 22c is nylon resin (for example, Asahi Placoat ARM-
Synthetic resins such as 900) are used.

Both shaft portions 2 of the toner collection roller 22
2b is rotatably inserted into a corresponding bearing 24. A retainer 26 is fitted to the end of one shaft portion 22b that protrudes from the bearing 24. A lever 27 is provided at the end of the other shaft portion 22b protruding from the bearing 24, so that it rotates integrally with the shaft portion 22b in one direction and idles with respect to the shaft portion 22b in the opposite direction. installed.

[0029] Toner scraping/frictional charging unit 2
Reference numeral 3 denotes a sheet support member 23a extending in the length direction of the developing roller 14 and having a trapezoidal cross section with a front surface inclined forward and upward.
, a toner scraping/frictional charging sheet 23c applied to the front surface of the sheet support member 23a via a reinforcing sheet 23b, and a toner scraping/frictional charging sheet 23
c and a clamping plate 23d that clamps the reinforcing sheet 23b and the front surface of the sheet supporting member 23a.

The seat support member 23a is applied to the lower surface of the upper wall 31 of the base 21b of the frame 21, and is attached to the frame 21 by a screw 36 inserted into a long screw insertion hole 34.
is screwed to.

The clamping plate 23d has a substantially horizontal L-shape in cross section and consists of a fixing part 37 along the lower surface of the sheet supporting member 23a and a clamping part 38 along the front surface of the sheet supporting member 23a. Then, with the toner scraping/frictional charging sheet 23c and the reinforcing sheet 23b sandwiched between the holding portion 38 and the front surface of the sheet support member 23a, the fixing portion 37 is screwed to the sheet support member 23a with the screw 39. By this,
A toner scraping/frictional charging sheet 23c and a reinforcing sheet 23b are attached to the sheet support member 23a.

Toner scraping/frictional charging sheet 23
The upper part of c protrudes upward from the reinforcing sheet 23b and is in pressure contact with the toner collection roller 22. The reinforcing sheet 23b is for reinforcing the toner scraping/frictional charging sheet 23c. Toner scraping/frictional charging sheet 2
Considering that the stiffness of the reinforcing sheet 3c is weaker at both ends than at the center, the vertical widths of both ends of the reinforcing sheet 23b are made wider.

Toner scraping/frictional charging sheet 23
c is a synthetic resin sheet such as a polyester sheet,
A conductive sheet (for example, a cast polycarbonate film containing special conductive carbon (trade name: KL3) manufactured by Vantech Co., Ltd.) is used. Reinforcement sheet 23
As b, a synthetic resin sheet such as a polyester sheet is used.

As described above, since the toner collecting roller 22 and the toner scraping/frictional charging sheet 23c are integrated into a unit, it is easy to replace them. Further, since the toner scraping/frictional charging unit 23 is screwed to the frame 21 by a screw 36 inserted into the long screw insertion hole 34 of the frame 21, the toner collecting roller 23 is screwed to the frame 21.
The toner scraping and frictional charging sheet 23c can be accurately positioned using a jig or the like when assembling the toner collection unit 20. Therefore, the toner scraping/frictional charging sheet 23c can be accurately positioned with respect to the toner collection roller 22 at a position where it is effective in scraping off toner and where the pressing force is not too large.

5 to 7 show a structure and method for attaching the toner recovery unit 20 to the housing 11 of the developing device 3.

Bearing members 40 of the developing roller 14 are fixed to both end surfaces of the housing 11 of the developing device 3. A keyhole-shaped notch 41 into which the bearing 24 for the toner collection roller 22 of the toner collection unit 20 is fitted is formed at the lower front end of both bearing members 40 . This notch 4
1 is a narrow part 41a of the opening and a circular part 41 following it.
It consists of b. The width of the narrow portion 41a is slightly larger than the length of the short axis of the oval portions 24a, 24b of the bearing 24. The diameter of the circular part 41b is the same as that of the oval part 2 of the bearing 24.
It is formed to be slightly larger than the length of the long axis of 4a and 24b.

The toner collection unit 20 is attached to the housing 11.
5 and 6, first, as shown in FIG. 5 and FIG. Then, the notch 41 is fitted into the circular part 41b from the narrow part 41a.

Next, as shown in FIGS. 6 and 7, the toner collection unit 20 is rotated approximately 90 degrees counterclockwise about the shaft portion 22b, and the lower wall 32 of the base portion 21b of the frame 21 is attached to the housing 11. Apply it to the outer surface of the lower wall.

At this time, the oval portion 24b of each bearing 24 is also rotated approximately 90 degrees, and as shown in FIG. The oval-shaped portion 24b cannot be removed from the circular portion 41b of the notch 41.

Thereafter, the toner is collected by screwing the screw 42 inserted into the long screw insertion hole 35 formed in the lower wall 32 of the frame 21 into the screw hole 43 formed in the lower wall of the housing 11. Unit 20 is attached to housing 11. Note that the toner collection roller 22
The metal roller body 22a is not grounded.

In this manner, after the bearing 24 of the toner collection unit 20 is fitted into the notch 41 formed in the bearing member 40 of the developing roller 14, the toner collection unit 20
The toner collection unit 20 can be attached to the developing device 3 by a simple operation such as rotating and screwing.

Furthermore, the bearing 24 of the toner collection unit 20
is fitted into a notch 41 formed in the bearing member 40 of the developing roller 14, so that the distance between the toner collection roller 22 and the developing roller 14 is accurately positioned.

Furthermore, when the toner collection unit 20 is attached to the developing device 3, the screw 36 for adjusting the position of the toner collection roller 22 and the toner scraping/frictional charging sheet 23c is located at a position where it cannot be operated. This prevents the screw 36 from being operated erroneously, and a good positional relationship between the toner collection roller 22 and the toner scraping/frictional charging sheet 23c is maintained.

FIG. 8 shows a drive mechanism for the toner collection roller 22. As shown in FIG.

A gear 51 is fitted onto one end of the shaft 14a of the developing roller 14 on the outer surface side of one bearing member 40 of the developing roller 14. A gear 52 rotatably attached to the bearing member 40 meshes with this gear 51 . Furthermore, a gear 53 that is rotatably attached to the bearing member 40 meshes with the gear 52 . A substantially rectangular cam 54 having four concave curved surfaces on its outer periphery is fixed to the shaft of this gear 53.

One shaft portion 22b of the toner collection roller 22
The lever 27 attached to the lever 27 rotates integrally with the shaft portion 22b in the direction shown by arrow E in FIG. 8, and idles with respect to the shaft portion 22b in the opposite direction. The lever 27 is always biased in the direction opposite to the arrow E with respect to the shaft portion 22b by a spring 55, and the tip of the lever 27 is pressed against the outer circumferential surface of the cam 54 due to this biasing force.

When the shaft 14a of the developing roller 14 is driven by a drive motor (not shown), the gear 51 rotates in the direction of arrow B, and the gear 52 rotates in the direction of arrow C accordingly. Further, as the gear 52 rotates, the gear 53 rotates in the direction of arrow D, and the cam 54 rotates in the same direction.

The lever 27 rotates as the cam 54 rotates.
It swings back and forth within a certain angle range, and when it rotates in the direction of arrow E, it rotates the toner collection roller 22 in that direction. In other words, the toner collection roller 22 rotates at a speed with high acceleration intermittently.

9 to 11 show a state in which the toner collecting roller 22 sucks the toner scattered from the developing roller 14 and the sucked toner is returned to the developing device 3.

In these figures, arrows A, B and E
indicates the rotation direction of the photosensitive drum 1, the developing roller 14, and the toner collection roller 22.

As the toner collection roller 22 rotates, the toner scraping/frictional charging sheet 23c and the insulating layer 22c on the surface of the toner collection roller 22 rub, and as shown in FIG. The (-) charge moves to the toner scraping/frictional charging sheet 23c, and the insulating layer 22c is positively charged (+).

Since the toner has negative polarity, FIG.
As shown in the figure, toner 50 scattered from the developing roller 14
is attracted to the insulating layer 22c on the surface of the toner collection roller 22 and adheres to the insulating layer 22c.

Insulating layer 22 on the surface of toner collection roller 22
As shown in FIG. 11, the toner 50 adhering to the toner 50 is scraped off by the toner scraping/frictional charging sheet 23c, and is returned into the housing 11 of the developing device 3 by the ear of the developing roller 14.

Furthermore, even when the machine is turned off immediately after the machine stops, immediately after copying is completed, or when the front door of the copying machine is opened due to a recording paper jam, etc., the charged potential of the toner collection roller 22 immediately goes to zero. There is still a certain amount left, so
In this case as well, the floating toner is attracted and adhered to the toner collecting roller 22 and returned into the housing 11 of the developing device 3.

In this manner, toner scattered and floating toner from the developing roller 14 can be collected, thereby preventing image unevenness and fogging. Since the outer peripheral surface of the toner collection roller 22 is covered with an insulating layer 22c, condensation does not occur on the surface of the toner collection roller due to temperature changes, and the toner is not adversely affected.

FIG. 12 shows the charging potential [V] of the insulating layer 22c on the surface of the toner collecting roller 22 and the average rotation of the toner collecting roller 22 with respect to the average rotational speed (rotating speed of the gear 53) [rpm] of the toner collecting roller 22. The graph shows experimental data of the rise time [sec] of the charging potential immediately after the rotation of the toner collection roller 22 starts with respect to several [rpm]. Figure 1
2, the black circles indicate the charging potential and the white circles indicate the rise time.

It is understood from this figure that the higher the average rotational speed of the toner collection roller 22, the faster the charging potential rises immediately after the toner collection roller 22 starts rotating, and the higher the charging potential becomes.

However, as the average rotational speed of the toner collection roller 22 increases, the degree of wear of the toner scraping/frictional charging sheet 23c increases, so the rotational speed of the gear 53 is preferably 20 to 70 [rpm]. .

In this embodiment, the toner collection roller 22 is rotated by the cam 54 and the lever 27 at a speed with intermittently large acceleration.
Compared to the case where the toner collecting roller 22 rotates at the same constant speed as the rotational speed of the gear 53, there is an advantage that the rising speed of the charged potential immediately after the start of rotation of the toner collection roller 22 becomes faster and the charged potential becomes higher.

For example, in this embodiment, the gear 53 is
In order to obtain a charging potential approximately equal to the charging potential of the insulating layer 22c on the surface of the toner collection roller 22 generated when the toner collection roller 22 is rotated at a constant speed, the toner collection roller 22 must be rotated at a constant speed. Approximately 500 [rpm]
The toner scraping/frictional charging sheet 23c has to be rotated at a high speed, which shortens the life of the toner scraping/frictional charging sheet 23c.

FIG. 13 shows how the toner collection roller 22 and the toner scraping/frictional charging sheet 23c are charged when a conductive sheet is used as the toner scraping/frictional charging sheet 23c.

Due to the friction between the toner collection roller 22 and the toner scraping/frictional charging sheet 23c, the outer surface side of the insulating layer 22c on the surface of the toner collection roller 22 becomes positive (+).
The inner surface of the insulating layer 22c is negatively charged (-),
The roller body 22a of the toner collection roller 22 is positively (+) charged. Further, the toner scraping/frictional charging sheet 23c is negatively charged (-).

Toner scraping/frictional charging sheet 23
When a conductive sheet is used as c, the roller body 2
2a, the insulating layer 22c and the toner scraping/frictional charging sheet 23c are a capacitor sandwiched between the insulating layer 22c, which is an insulator, and the roller body 22a, which is a conductor, and the toner scraping/frictional charging sheet 23c. form a structure.

Therefore, in this case, compared to the case where an insulating sheet is used as the toner scraping/frictional charging sheet 23c, charges are more easily accumulated in the insulating layer 22c, and the charged potential of the insulating layer 22c and After the drive of the toner collection roller 22 is stopped, the charging potential falls slowly.

FIG. 14 shows the charging of the toner collection roller 22 when a conductive sheet (cast polycarbonate film containing special conductive carbon (trade name: KL3) manufactured by Vantech Co., Ltd.) is used as the toner scraping and frictional charging sheet 23c. FIG. 15 shows the potential of the toner collection roller 22 when an insulating sheet (polyester sheet) is used as the toner scraping/frictional charging sheet 23c.
The charging potential of is shown respectively.

In the above embodiment, the toner collection roller 22 is composed of a metal roller body 22a and an insulating layer 22c formed on the outer peripheral surface of the roller body 22a, but the toner collection roller 22 is entirely made of synthetic resin or the like. It may be made of an insulator.

Furthermore, in the above embodiment, the toner collection roller 22 is rotated at a speed with intermittently large acceleration by the cam 54 and the lever 27, but the toner collection roller 22 is rotated at a constant speed. You can also do this.

Further, in the above embodiment, a frictional charging member is used to frictionally charge the outer circumferential surface of the toner collection roller to a polarity opposite to that of the toner, and a toner scraping member is used to scrape off the toner suctioned and adhered to the toner collection roller. is the same member (
Although the toner scraping and frictional charging sheet 23c) is used, the frictional charging member and the toner scraping member may be provided separately.

[0069]

According to the present invention, it is possible to prevent image unevenness and fog from occurring. Moreover, there is no need to apply a bias voltage, and costs can be reduced. Also, if you turn off the power to the machine immediately after it stops or finishes copying,
Even when the front door of the copying machine is opened due to a recording paper jam, etc., floating toner can be sucked out. Further, the toner is not adversely affected by temperature changes or the like.

Further, a notch for fitting a bearing into which the bearing of the toner collection roller is fitted is formed in the support member of the developing roller, and with the bearing of the toner collection roller fitted into the notch for fitting the bearing, Since the toner collecting roller is attached to the developing device, it is easy to attach the toner collecting roller to the developing device, and it is also easy to position the toner collecting roller and the developing roller.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an image forming section of a copying machine.

FIG. 2 is an enlarged perspective view showing a toner collection unit.

FIG. 3 is an enlarged side view showing the toner collection unit.

FIG. 4 is an enlarged sectional view showing a toner collection roller and a toner scraping/frictional charging unit.

FIG. 5 is an enlarged side view showing a method of attaching the toner collection unit to the housing of the developing device.

FIG. 6 is an enlarged side view showing a method of attaching the toner collection unit to the housing of the developing device.

FIG. 7 is an enlarged side view showing a method of attaching the toner collection unit to the housing of the developing device.

FIG. 8 is an enlarged side view showing the drive mechanism of the toner collection roller.

FIG. 9 is an explanatory diagram for explaining how the insulating layer on the surface of the toner collection roller is charged due to friction between the toner collection roller and the toner scraping/frictional charging sheet.

FIG. 10 is an explanatory diagram for explaining how toner scattered from a developing roller is attracted and adhered to an insulating layer on the surface of a toner collection roller.

FIG. 11 is an explanatory diagram illustrating how the toner adhering to the insulating layer on the surface of the toner collection roller is scraped off by a toner scraping/frictional charging sheet and returned into the housing of the developing device. .

FIG. 12 is a graph showing experimental data of the charging potential of the insulating layer on the surface of the toner collection roller relative to the average rotational speed of the toner collection roller and the rise time of the charging potential immediately after the start of rotation of the toner collection roller relative to the average rotational speed of the toner collection roller. It is.

FIG. 13 is a schematic diagram showing how a toner collection roller and a toner scraping/frictional charging sheet are charged when a conductive sheet is used as the toner scraping/frictional charging sheet.

FIG. 14 is a graph showing the charging potential of the toner collection roller when a conductive sheet is used as the toner scraping and frictional charging sheet.

FIG. 15 is a graph showing the charging potential of the toner collection roller when an insulating sheet is used as the toner scraping and frictional charging sheet.

[Explanation of symbols]

1 Photosensitive drum 11 Housing 14 Developing roller 20 Toner collection unit 22 Toner collection roller 22a Roller body 22c Insulating layer 23c Toner scraping and frictional charging sheet 24
Bearing 24a Oval part 24b Oval part 40 Bearing member 41 Notch 41a Narrow part 41b Circular part

Claims (6)

[Claims] Claims: 1. A toner collection roller, at least the outer peripheral portion of which is formed of an insulator, and which is disposed near a position where an image carrier and a developing roller of a developing device act, and which is provided in contact with the outer peripheral surface of the toner collection roller. and a frictional charging member for frictionally charging the outer peripheral surface of the toner collection roller to a polarity opposite to that of the toner, and a bearing fitting notch for fitting the bearing of the toner collection roller into a predetermined position of a required member of the developing device. An image forming apparatus in which a toner collection roller is attached to a developing device in a state where a bearing of the toner recovery roller is fitted into a notch for fitting the bearing. [Claim 2] The bearing of the toner collection roller has an oval-shaped bearing part, and the notch for fitting the bearing has a width slightly larger than the short axis length of the oval-shaped bearing part, a narrow part of the opening, and a narrow part. The oval-shaped bearing part of the toner collection roller bearing is fitted into the circular part from the narrow part of the notch, and then rotated at a predetermined angle. 2. The image forming apparatus according to claim 1, wherein the oval-shaped bearing portion is fitted into the circular portion. 3. The image forming apparatus according to claim 1, wherein the toner collection roller and the frictional charging member are attached to the same frame to form a unit. 4. The image forming apparatus according to claim 1, wherein the toner collection roller comprises a metal roller body and an insulating layer formed on the outer peripheral surface of the metal roller body. 5. The image forming apparatus according to claim 1, wherein the entire toner collection roller is made of an insulating material. 6. The image forming apparatus according to claim 1, wherein the frictional charging member also serves as a toner scraping member for scraping off toner suctioned and adhered to the toner collection roller.