JP2000221768A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the toner end so as possible to be recognized in a state that the toner in the toner hopper is almost running out. SOLUTION: This image forming device is allowed to respectively dispose 4 developing units 41, to respectively dispose a pair of light guide bodies 47A and 47B in the toner hopper 43 of those developing unit 41, and to make the pair of light guide bodies on another developing unit come to the toner end detecting position, coming to the lowest position in the toner hopper 43 of the developing units 41, when shifting one of the developing units to the developing position. The device is allowed to fix the toner end detecting sensor 52, on the outside of the toner hopper and beneath the rotary center shaft O 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 There is an electrophotographic image forming apparatus having a plurality of developing units in a developing device such as a color developing device.
Conventionally, this type of image forming apparatus uses a toner end detection sensor including a light emitting element and a light receiving element, and inputs the light emitted from the light emitting element into a toner hopper of a developing unit, so that the toner in the toner hopper becomes less than a certain amount. When light is transmitted, the transmitted light is received by the light receiving element,
The toner end in the toner hopper was detected.

That is, the toner end is recognized when a certain amount of toner in the toner hopper remains. When the toner end is detected, new toner is supplied into the toner hopper by, for example, replacing the toner cartridge.

[0004]

However, when the toner end is detected as described above, the toner end of one color is detected rather than replenishing new toner in the toner hopper by, for example, replacing a toner cartridge. At this time, it was found that replacing the developing unit itself with a new one can further reduce the total cost.

However, in this case, the toner end is recognized when a certain amount of toner remains in one toner hopper as in the prior art, and the developing unit itself is left with a certain amount of toner still remaining in the toner hopper. It would be uneconomical to exchange for a new one. It is preferable that the toner end is recognized when the toner in the toner hopper is almost exhausted, and the developing unit itself is replaced with a new one after the toner in the toner hopper is almost exhausted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrophotographic image forming apparatus having a plurality of developing units so that a toner end can be recognized in a state where toner in a toner hopper is almost exhausted.

[0007]

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. The pair of light guides of the other developing unit are located at the lowest position in the toner hopper of the other developing unit, and one of the pair of light guides is A toner end detection sensor that sends light to the outside of the toner hopper is fixed, and when there is no toner between the pair of light guides, light is transmitted from the one light guide to the other light guide, Light is returned from the other light guide to the toner end detection sensor, so that it is recognized that the toner in the toner hopper has run out.

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 at the lowest position in the toner hopper of the other developing unit that has reached the toner end detecting position is connected to the outside. When there is no toner between the pair of light guides, light is transmitted from one of the light guides to the other light guide, and toner is transmitted from the other light guide. Since the light returns to the end detection sensor, it is recognized that the toner in the toner hopper has run out.

According to a second aspect of the present invention, in the electrophotographic image forming apparatus according to the first aspect, the toner end detection sensor is positioned just below a toner hopper of the developing unit at the toner end detection position. Is fixed.

According to a third aspect of the present invention, in the electrophotographic image forming apparatus according to the first or second aspect, the rotary developing device is provided with a plurality of the developing units for each color to form a color image. It is characterized by the following.

[0012]

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 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 a cleaning member 15A of a 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 makes one rotation. 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 then intermediately. 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 device 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 rotated to selectively move one of the four developing units 41 to the developing position, and the one developing unit 41 is moved 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.

Now, in the rotary developing device 6 described above,
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 supports 48 standing 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.

Then, the pair of light guides 4 of the yellow developing unit 41Y at the toner end detection position
7A and 47B are located at the lowest position in the toner hopper 43 of the yellow developing unit 41Y.

On the other hand, as the toner end detecting device 46,
As shown in FIG. 5, a position outside the toner hopper 43 is below the rotation center axis O of the rotary support 40 of the rotary developing device 6 and just below the toner hopper of the yellow developing unit 41Y that has reached the toner end detection position. To this end, the toner end detection sensor 52 that sends light to one of the pair of light guides is fixed to an appropriate member in the apparatus main body 9. At this time, the toner end detection sensor 52
It is installed at a position corresponding to the pair of light guides 47A and 47B.

As described above, when 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. 7 (b), 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 the present invention, the pair of light guides 47A, 47
Since B is provided at the lowest position in the toner hopper 43 at the toner end detection position, as shown in FIG. 8, the toner gathers at the lowest portion along the curvature of the outer peripheral portion, and at this lower portion, If the toner end is detected, the toner end can be recognized in a state where the toner in the toner hopper 43 is almost exhausted.

When developing, 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.

At 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 1/4 turn in the direction of arrow C to move from the toner end detection position to the position on the left side of the rotation center axis O in FIG. 9, the state is maintained. You.

However, when the rotary developing device 6 further rotates by 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.

[0044]

When a small amount of toner remains in the toner hopper, when the toner hopper reaches the toner end detection position, the toner moves to the lowest position in the toner hopper by gravity. According to the present invention, since a pair of light guides is provided at the lowest position in the toner hopper at the toner end detection position, if a small amount of toner remains in the toner hopper, the light is transmitted to the toner end detection sensor. And it is possible to reliably recognize that there is still toner in the toner hopper. Therefore, the toner end can be recognized when the toner in the toner hopper is almost exhausted, so that even when the developing unit itself is replaced with a new one,
The amount of toner remaining in the toner hopper can be reduced to almost zero, which is economical.

Also, 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 detection 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 toner end detection sensor is fixed so as to be located immediately below the toner hopper of the developing unit at the toner end detection position, installation of the toner end detection sensor is facilitated. be able to.

According to the third 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 (3)

[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 and the plurality of developing units are rotated. 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. The light guide is positioned at the lowest position in the toner hopper of the developing unit, and the toner engine that sends light to one of the pair of light guides is used. A light detection sensor is fixed outside the toner hopper, and when there is no toner between the pair of light guides, light is transmitted from the one light guide to the other light guide, and the other light guide is transmitted. An electrophotographic image forming apparatus, which recognizes that the toner in the toner hopper has run out by returning light from the body to the toner end detection sensor. 2. The electrophotographic image forming apparatus according to claim 1, wherein the toner end detection sensor is fixed so as to be located directly below a toner hopper of the developing unit that has reached the toner end detection position. 3. 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.