JP2000221767A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make toner end accurately detected by respectively minimizing the soiling on a light transparent surface of the light transmission body in respective toner hopper. SOLUTION: This image forming device is allowed to respectively dispose 4 unit of developing unit 41 for the rotary developing device 6, and in the toner hopper 43 of those developing unit 41, allowed to respectively dispose a pair of light guide bodies 47A and 47B and a cleaning member 51 fitted to a weight 50 turning with the center at a supporting shaft 49. The device is allowed to fix the toner end detecting sensor 52 fitted to an appropriate member in the image forming device main body, beneath the rotary center shaft O in the rotary developing device 6 and outside the toner hopper 43. Then, the device is allowed to detect the presence or absence of the toner in the toner hopper 43 brought into the toner end detecting position by the toner end detecting sensor 52 based on whether light is permitted to pass through between a pair of light transparent bodies or not. Moreover, the device is allowed to clean light transparent surfaces of a pair of light guide bodies by the cleaning member 51 by turning the weight 50 with the center at the supporting shaft 49 by rotary drive of the rotary developing device 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction peripheral thereof. More specifically, the present invention relates to an electrophotographic image forming apparatus that develops an electrostatic latent image formed on an image carrier by attaching toner with a developing device.

[0002]

2. Description of the Related Art Conventionally, as a mechanism for detecting a toner end in a toner hopper for replenishing toner to a developing unit, a light guide provided in the toner hopper and a toner end detection sensor for sending light to the light guide to detect the light end are provided. It is known to recognize the presence or absence of toner in combination.

[0003]

However, in this conventional mechanism, it is difficult to accurately detect the toner end because toner is present in the toner hopper and stains the light transmitting surface of the light guide. There was a problem. SUMMARY OF THE INVENTION An object of the present invention is to make it possible to accurately detect a toner end by minimizing dirt on a light transmitting surface of a light guide in a toner hopper.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a rotary developing device is provided with a plurality of developing units integrally having a developing device and a toner hopper for supplying toner to the developing device. Is rotated to selectively move one developing unit of the plurality of developing units to the developing position, and toner is adhered by a developing device of the one developing unit to form on the image carrier. In an electrophotographic image forming apparatus for developing an electrostatic latent image, a pair of light guides is provided in a toner hopper of the developing unit, and when the one developing unit is moved to a developing position, the developing unit comes to a toner end detecting position. A toner end detection sensor that sends light to one of the pair of light guides of another developing unit is fixed to the outside of the toner hopper, and the pair of light guides is fixed. When there is no toner between the bodies, light is transmitted from the one light guide to the other light guide, and light returns from the other light guide to the toner end detection sensor. A cleaning member that moves between the pair of light guides and cleans the light transmitting surfaces of the pair of light guides while rotating the rotary developing device while recognizing that the toner has run out. It is characterized by.

When an image is recorded on a recording medium, one of the plurality of developing units is selectively moved to a developing position by rotating the rotary developing device, and the one developing unit is moved. Attach the toner with a developing device to develop the electrostatic latent image formed on the image carrier,
The toner image obtained by the development is finally transferred to a recording medium.

In this case, when one developing unit is moved to the developing position, one of the pair of light guides provided in the toner hopper of the other developing unit at the toner end detecting position is connected to one of the pair of light guides by an external toner end detecting sensor. When light is sent and there is no toner between the pair of light guides, light is transmitted from one light guide to the other light guide, and light is transmitted from the other light guide to the toner end detection sensor. From the return, it is recognized that the toner in the toner hopper has run out.

[0007] With the rotation of the rotary developing device, the rotary developing device moves between the pair of light guides and cleans the light transmitting surfaces of the pair of light guides with the cleaning member.

According to a second aspect of the present invention, in the electrophotographic image forming apparatus according to the first aspect, the cleaning member comprises:
It is characterized in that the rotary developing device moves between the pair of light guides based on gravity together with the rotational driving of the rotary developing device.

According to a third aspect of the present invention, in the electrophotographic image forming apparatus according to the second aspect, the cleaning member includes:
The rotary developing device is attached to a weight that rotates about a support shaft, and is moved based on gravity together with the rotation of the rotary developing device.

[0010] The invention described in claim 4 is based on claims 1, 2,
Alternatively, in the electrophotographic image forming apparatus described in Item 3, a plurality of the developing units are provided for each color in the rotary developing device to form a color image.

[0011]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall schematic configuration diagram of an electrophotographic color image forming apparatus to which the present invention is applied.

A belt-shaped photosensitive member 1 serving as an image carrier is rotatably supported by rotating rollers 2 and 3 and is circulated in the direction of arrow A. A charging unit 4, a discharging roller 5, and a cleaning unit 1 for cleaning the photoconductor 1 are provided on an outer peripheral portion of the photoconductor 1.
5 are arranged. At a position downstream of the charging device 4, there is an optical writing unit to which the laser light L emitted from the laser writing unit LW is irradiated. At a position downstream of the optical writing unit, a rotary developing device 6 in which a plurality of developing units are supported so as to be switchable is arranged. The rotary developing device 6 is provided for each of the four stored toners.
It has a yellow developing unit, a cyan developing unit, a magenta developing unit, and a black developing unit. Any one of these developing units moves to a developing position where the developing operation for the photoconductor 1 is possible in synchronization with the corresponding developing timing.

In this embodiment, the rotary developing device 6
There is a mechanism for selecting the four color developing units by rotating 90 degrees around the circumference.

Although not shown, in the laser writing unit LW, light from a laser light source is scanned by a polygon mirror rotated by a motor, and fθ
After passing through a lens, a mirror, and the like, the laser beam L reaches the photoconductor 1 as a writing laser beam L, and forms an electrostatic latent image corresponding to writing information on the photoconductor 1 charged by the charging device 4.

The electrostatic latent image on the photoreceptor 1 is developed by the above-described developing unit, and a visible image by toner is formed and held on the surface of the photoreceptor. The upper portion of the photoconductor 1 is in contact with an intermediate transfer belt 10 which is an intermediate transfer member.

The intermediate transfer belt 10 includes a rotating roller 11
12 rotatably supported and circulated in the direction of arrow B. The toner image on the photoreceptor 1 is transferred to the intermediate transfer belt 10 by a bias unit 13 on the back side of the intermediate transfer belt 10.
Transferred to the surface.

The photosensitive member 1 is cleaned for each color by the cleaning member 15A of the cleaning unit 15, and a toner image of a predetermined color is sequentially formed on the photosensitive member 1, and each time the intermediate transfer belt 10 rotates once. Each time, the color toner image is transferred to the same position on the surface, and a color toner image in which several colors are superimposed on the intermediate transfer belt 10 is formed. Then, the color toner image is transferred to a sheet.

At the time of transfer to a sheet, a sheet 17A stored in a sheet feeding device (sheet feeding cassette) 17 passes through a sheet feeding roller 18, a pair of conveying rollers 19A and 19B, and a pair of registration rollers 20A and 20B, and passes through an intermediate portion. The paper and the image are conveyed to the nip between the transfer belt 10 and the transfer roller 14 at a timing such that the positions of the sheet and the image become normal. The sheet on which the toner images of several colors on the intermediate transfer belt 10 are collectively transferred by the action of the transfer roller 14 is sent to a fixing device 80, where the toner image on the sheet is fixed, and a pair of discharge rollers 81A. The paper is discharged to the paper discharge stack 82 at the upper part of the apparatus main body 9 by 81B.

On the outer periphery of the intermediate transfer belt 10, a cleaning device 16 for the intermediate transfer belt is
The cleaning blade 16A is configured to be able to freely contact and separate via a cleaning blade contacting / separating arm 16C. This cleaning blade 16A
In the process in which the intermediate transfer belt 10 receives the toner image from the photoreceptor 1, the intermediate transfer belt 10 separates from the intermediate transfer belt 10 and comes into contact with the toner image after being transferred from the intermediate transfer belt 10 to a sheet. Scrape off toner.

The waste toner scraped off from the intermediate transfer belt 10 is transported by an auger 16B provided inside the intermediate transfer belt cleaning device 16, and the cleaning unit 15 can be replaced by transport means (not shown). Is collected in a simple collection container 15C. Further, the waste toner scraped from the photoconductor 1 by the cleaning member 15A as described above is also collected in the collection container 15C.

The photosensitive member 1, the charging device 4, the intermediate transfer belt 10, the cleaning unit 15, the cleaning device 16, the transport guide 30 for forming the paper transport path, and the like are integrally unitized as a process cartridge 31. It can be replaced at the end of its life.

In addition to replacing the process cartridge 31, the rotary developing device 6 and the like are also replaced at the end of their service life, but the front frame 8 can be opened to facilitate its exchangeability and the handling of jammed paper. The main body 9 is pivotally supported by a support shaft 9A.

The electrical equipment / control device E is accommodated in the rear part of the apparatus main body 9, and a fan for exhausting air to prevent an excessive temperature rise in the apparatus is disposed above the electric equipment / control apparatus E. further,
Another relatively small paper feeder can be attached to the main body 9.

Incidentally, the above-described rotary developing device 6 has the appearance shown in FIG. This rotary developing device 6
The developing unit 41 shown in FIG. 3B is detachably provided on the rotary support 40 shown in FIG. 3A.

As shown in FIG. 3B, the developing unit 41 integrally includes a developing device 42 and a toner hopper 43 for supplying toner to the developing device 42. The developing unit 42 includes a developing roller (not shown), a toner supply roller, and a blade (not shown).
It is housed in a four cylindrical case. Toner hopper 43
As shown in FIG. 4, a partition plate 44 and an opening 45 are provided in a quarter-circular can-shaped case.

The opening 45 is provided near the center of the upstream side of the toner hopper 43 so as to communicate with the developing device 42. The partition plate 44 is provided so as to collect the toner in the toner hopper 43 to the opening 45 together with the rotation of the rotary developing device 6.

When an image is recorded on a recording medium, the rotary developing device 6 is driven to rotate to selectively move one of the four developing units 41 to the developing position. The developing device 42 of the unit 41 applies toner to develop the electrostatic latent image formed on the image carrier.

The rotary developing device 6 described above includes:
As shown in FIG. 5, a toner end detecting device 46 is provided. As the toner end detecting device 46, a pair of light guides 47A,
7B is provided.

Further, as shown in FIG. 6, a support shaft 49 is horizontally supported by a pair of support columns 48 erected on an outer peripheral arc portion. This support shaft 49 is fixed to the base end of the weight 50. In addition, weight 5
A cleaning member 51 having a rectangular plate shape is attached to the base end of the zero.

In the illustrated rotary developing device 6, for example, as shown in FIG.
When 1C is moved to the developing position, the developing unit 41Y of the yellow adjacent to the downstream side comes to the toner end detecting position.

On the other hand, as the toner end detecting device 46,
Outside the toner hopper 43, as shown in FIG. 5, a toner end detection sensor 52 for sending light to one of the pair of light guides below the rotation center axis O of the rotation support 40 of the rotary developing device 6 shown in the drawing. Is fixed to an appropriate member in the apparatus main body 9.

As described above, when the toner is present between the pair of light guides 47A and 47B, FIG.
As shown in the figure, even if the light is sent to one light guide 47A, the light is blocked by the toner, and the other light guide 47A is blocked.
Since no light is returned from B to the toner end detection sensor 52, it is recognized that there is still toner in the toner hopper 43.

However, when there is no toner between the pair of light guides 47A and 47B, as shown in FIG. 7B, each light is transmitted from one light guide 47A to the other light guide 47B. The light is transmitted through the surface 53 and the other light guide 4
Since the light returns from 7B to the toner end detection sensor 52, it is recognized that the toner in the toner hopper 43 has run out.

In this example, a pair of light guides 47A, 47B
8 is provided at the lowest position in the toner hopper 43 at the toner end detection position.
As shown in (2), the toner collects at the lowermost portion along the curvature of the outer peripheral portion, and if the toner end is detected at the lowermost portion, the presence or absence of the remaining toner in the toner hopper 43 can be more accurately recognized.

When performing development, as shown in FIG.
With the rotation of the rotary developing device 6 in the direction of the arrow C, the weight 50 rotates around the support shaft 49 based on gravity, and the cleaning member 51 moves accordingly.

In the toner end detection position shown in FIG. 9, the center of gravity is set so that the weight 50 is in a falling state, and the cleaning member 51 and the weight 50 are connected to the pair of light guides 47A and 47B. And does not affect the toner end detection at all.

Then, even if the rotary developing device 6 makes a quarter turn in the direction of arrow C and comes from the toner end detection position to the position on the left of the rotation center axis O in FIG. 9, the state is maintained. You.

However, when the rotary developing device 6 further rotates 1/4 in the direction of arrow C and reaches the upper position in FIG. 9, the weight 50 is held in a suspended state due to gravity. However, the pair of light guides 47A and 47B face downward, and accordingly, the cleaning member 51
And 47B, and rub the light transmitting surfaces 53 of the pair of light guides to clean them.

Further, even if the rotary developing device 6 is rotated by 1/4 in the direction of arrow C to a position on the right side of the rotation center axis O in FIG. , The state is maintained as it is.

Further, when the rotary developing device 6 makes a quarter turn in the direction of arrow C and returns to the toner end detection position shown in FIG. 9, the weight 50 moves clockwise about the support shaft 49 based on gravity. And the cleaning member 51
Moves out of the space between the light guides 47A and 47B,
The light transmitting surfaces 53 of the pair of light guides are again rubbed and cleaned.

The width of the cleaning member 51 is determined by the light guides 47A and 47B.
In the illustrated example, the width between the cleaning members 51 is narrower than the width between the cleaning members 51, and does not become a load when the cleaning member 51 moves. Even if the width of the cleaning member 51 is narrow as described above, there is play in the direction of arrow D shown in FIG. 6 in supporting the weight 50, and thus the cleaning member 51 comes into contact with both the left and right light guides. And can be cleaned.

[0042]

According to the present invention, since the rotary developing device is driven to rotate and moves between the pair of light guides to clean the light transmission surfaces of the pair of light guides with the cleaning member, the light transmission surface is cleaned. The toner end in the toner hopper can be accurately detected by removing the toner attached to the toner hopper.

Also, with one toner end detection sensor,
It is possible to detect the presence or absence of toner in the toner hopper provided in each of the plurality of developing units, and it is not necessary to provide a plurality of toner end detection sensors. Therefore, it is possible to detect the toner end of the plurality of developing units provided in the rotary developing device at low cost. Can be.

Further, since the toner end detecting sensor is provided outside the developing unit, it is economical because the developing unit is not discarded when the developing unit is replaced.

According to the second aspect of the present invention, since the cleaning member is moved between the pair of light guides based on gravity together with the rotation of the rotary developing device, the driving device for moving the cleaning member is additionally provided. It is not necessary, and the toner end can be detected at low cost.

According to the third aspect of the present invention, the cleaning member is attached to the weight that rotates about the support shaft and moves based on gravity together with the rotation of the rotary developing device. Can be reliably moved with an inexpensive configuration.

According to the fourth aspect of the present invention, since a plurality of developing units are provided for each color in the rotary developing device and a color image is formed, the toner end of each color developing unit is accurately recognized in the color image forming apparatus. be able to.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an electrophotographic color image forming apparatus to which the present invention is applied.

FIG. 2 is a perspective view of a rotary developing device used in the image forming apparatus.

FIG. 3A is a perspective view of a rotary support used in the rotary developing device, and FIG. 3B is a perspective view of a developing unit.

FIG. 4 is a sectional view of a toner hopper portion of the rotary developing device.

FIG. 5 is a schematic diagram illustrating the configuration of a toner end detecting device of the rotary developing device.

FIG. 6 is a partial perspective view of the toner end detecting device.

FIGS. 7A and 7B are explanatory diagrams illustrating toner end detection; FIG.
(B) is when there is no toner between the pair of light guides, and (b) is when there is no toner between the pair of light guides.

FIG. 8 is a cross-sectional view of a toner hopper for explaining toner end detection.

FIG. 9 is an explanatory diagram illustrating cleaning by a cleaning member accompanying rotation driving of the rotary developing device.

[Explanation of symbols]

 Reference Signs List 1 photoconductor (image carrier) 6 rotary developing device 41 developing unit 42 developing device 43 toner hopper 44 partition plate 45 opening 46 toner end detecting device 47A light guide 47B light guide 49 support shaft 50 weight 51 cleaning member 52 toner End detection sensor 53 Light transmitting surface

Claims (4)

[Claims] A rotary developing device is provided with a plurality of developing units each integrally having a developing device and a toner hopper for supplying toner to the developing device. When an image is recorded on a recording medium, the rotary developing device is driven to rotate to form a plurality of the developing units. One of the developing units is selectively moved to a developing position, and toner is adhered by a developing device of the one developing unit to develop an electrostatic latent image formed on the image carrier. In the photographic image forming apparatus, a pair of light guides is provided in a toner hopper of the developing unit, and when the one developing unit is moved to a developing position, the pair of light guides of another developing unit that is at a toner end detection position is provided. A toner end detection sensor that sends light to one of the light guides is fixed outside the toner hopper, and when there is no toner between the pair of light guides, Since light is transmitted from the one light guide to the other light guide and returned from the other light guide to the toner end detection sensor, it is recognized that the toner in the toner hopper is depleted. An electrophotographic image forming apparatus, comprising: a cleaning member that moves between the pair of light guides and cleans the light transmitting surfaces of the pair of light guides while rotating the rotary developing device. 2. The electrophotographic image forming apparatus according to claim 1, wherein the cleaning member is moved between the pair of light guides based on gravity together with the rotation of the rotary developing device. 3. The electrophotographic image according to claim 2, wherein the cleaning member is attached to a weight that rotates about a support shaft, and moves based on gravity together with the rotation of the rotary developing device. Forming equipment. 4. The electrophotographic image forming apparatus according to claim 1, wherein a plurality of the developing units are provided for each color in the rotary developing device to form a color image.