JPH08262872A - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] To provide an image forming apparatus capable of preventing toner from scattering even when vibration or impact is applied to the apparatus body without complicating the maintainability of the apparatus body. A moving mechanism 60 is slidable in a vertical direction with respect to a main body of the apparatus, and is rotatably supported by a moving frame 61 which is rotatably supported around a rotation center shaft 115 and front and rear side plates 110 and 111 of the main body. Cam shaft 113 supported by
And a pressure cam 114B attached to the opposite side of the rotation center shaft 115 of the cam shaft 113. The rotation center shaft 115 of the moving mechanism 60 is used as the toner supply port 400 of the developing unit 4.
The moving mechanism is rotated in the vicinity. As a result, even when the developing unit 4 is separated from the photosensitive drum 1,
Since there is no gap between the toner discharge port 203 of the toner hopper 200 and the supply port 400 of the developing unit 4, it is possible to prevent the toner from scattering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a recording device using an electrophotographic system, that is, a developing device used for developing and visualizing an electrostatic latent image formed on an image carrier. For example, the present invention relates to an image forming apparatus such as a printer, a facsimile, a copying machine, etc., and is particularly characterized by a developing device that makes contact with and separates from an image carrier.

Further, the present invention relates to a color image forming apparatus having a plurality of developing devices arranged in parallel.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus for recording by an electrophotographic method, an electrostatic latent image on an image carrier is generally developed by a developing device having a structure as described below.

FIG. 8 and FIG. 9 show an example of such a developing device. The developing device includes a developing container 10 whose interior is partitioned into a stirring chamber 104a and a developing chamber 104b by a partition 106.
4, the developing roller 101 is rotatably supported in the opening 104c above the developing chamber, and the developing roller 101 is rotatable in the arrow direction of the drawing by a drive system (not shown).

Further, the stirring chamber 104a and the developing chamber 104b
Inside the developer carrying screws 102 and 103, respectively.
Is rotatably provided. The developing roller 101 is supported by the developing container 104 by pressing a seal material 107 such as felt that prevents the developer from leaking to both ends of the developing roller 101.

The screw 102 in the stirring chamber 104a is
By rotating a drive system (not shown), as shown in FIG. 9, the developer in the developing container 104 is agitated with the toner replenished in the agitating chamber 104a from the toner replenishing port 104d opened on the front side of the developing container. While carrying in the direction of arrow V in the figure,
The developer is transferred into the developing chamber 104b through the opening 106a located at the tip of the partition plate 106 in the arrow V direction.

The screw 103 in the developing chamber 104b is
Similarly, by rotating a drive system (not shown), the developer transferred from the stirring chamber 104a into the developing chamber 104b is conveyed in the W direction opposite to the arrow V, and the developer is separated from the partition plate 106. It returns to the inside of the stirring chamber 104a through the opening 106b at the tip position of the arrow W direction.

The developer in the developing chamber 104b is drawn up by the rotating developing roller 101 while being conveyed in the direction of the arrow W by the screw 103, and is regulated by the blade 105 close to the developing roller 101 to a predetermined level. A developer layer having a predetermined layer thickness is formed on the developing roller 101 by being applied in a layer thickness. And this developer layer is
As shown in FIG. 8, the electrostatic latent image formed on the surface of the photosensitive drum 100 is conveyed to the opening 104c of the developing chamber 104b as the developing roller 101 rotates, and supplies the developer to the photosensitive drum 100 there. Toner is attached to the image and developed to visualize it as a toner image.

Next, a moving mechanism for the developing device to move toward and away from the photosensitive drum 100 will be described with reference to FIGS.

The moving mechanism 120 passes through the guide groove 121A provided in the moving frame 121 and the front and rear side plates 11 of the main body.
A total of four pins 112, which are fixed to 0 and 111, support the device main body so as to be slidable in the vertical direction. A cam shaft 113 is rotatably supported by the front and rear side plates 110 and 111 of the body, and two pressure cams 114A are fixed to the cam shaft 113 with a predetermined shell. A leaf spring 122 fixed to the bent portion 121B of the moving frame 121 is provided on the outer peripheral surface of the pressure cam 114A.
Are in contact.

The cam shaft 113 is rotated by 180 ° by the action of a half-rotation clutch and a plunger (not shown) and then stopped so that the pressure cam 114A is selectively displaced between two states. repeat. The moving frame 121 moves up and down in conjunction with the operation of the pressure cam 114A, whereby the developing device 4 approaches and separates from the photosensitive drum 100. Note that FIG. 11 shows the close state and FIG. 12 shows the separated state.

The position of the developing roller 101 with respect to the photosensitive drum 100 is determined by bringing the abutting roller 108 mounted on the shaft of the developing roller 101 into contact with the surface of the photosensitive drum, or directly abutting the surface of the photosensitive drum. When it is not possible, as shown in FIG. 9, the photosensitive drum 100 fixed to the front and rear side plates 110 and 111 of the main body.
It is determined by abutting on the abutment block 109 having the same radius as the above. However, the butting block 109 needs to be accurately positioned with respect to the photosensitive drum 100. The pressing force of the developing device 4 is generated by the bending of the leaf spring 122.

Next, details of the toner replenishing device will be described with reference to FIG. 13 is a magenta toner hopper 201M, a cyan toner hopper 201C, and a black toner hopper 20 shown in FIG.
It is the sectional view which looked at either 1BK from the right side.

The toner stored in the toner hopper 201 is stored in the toner hopper by the first screw 3 arranged in the toner hopper.
01 is conveyed in the direction A in the drawing. As a result, toner near the position 201b farthest from the connection port 201a between the toner transport path 300 and the toner hopper 201 is prevented from staying, and the volume of the hopper can be effectively utilized.

The toner carried to the connection port 201a enters the toner carrying path 300 arranged in the axial direction of the drawing, is carried forward by the second screw 302 arranged inside, and is discharged from the toner discharging port 203. Then, the toner is supplied to the developing unit 4 through the toner supply port 400.

Above the first screw 301,
The wire-shaped stirring member 303 is locked to the stirring shaft 304, and the stirring member 303 is driven by transmitting the driving force of the first screw 301 via a gear.

The stirring member 303 is the toner hopper 201.
It prevents the toner from aggregating inside. If the aggregated toner is replenished to the developing unit, tribo becomes locally insufficient, or a uniform coating thickness on the developing sleeve cannot be obtained, and it becomes difficult to form a high quality image.

Next, referring to FIG. 14, the developing device,
A conventional image forming apparatus using a moving mechanism and a toner replenishing device will be described. Conventionally, a color electrophotographic copying machine is a typical example of an image forming apparatus provided with a toner replenishing device. FIG. 14 shows an example of a color electrophotographic copying machine. According to the color electrophotographic copying machine of this example, the toner is replenished to each developing unit from the toner replenishing device fixed to the main body of the developing device having the plurality of developing units.

In FIG. 14, a photosensitive drum 100 as an image carrier for carrying an electrostatic latent image is carried so as to be rotatable in the arrow direction. Around the photosensitive drum 100, a corona charger 2, an exposure optical device 3, a developing device 4, a transfer system 50, a cleaning device 6 and the like are arranged.

The original reading system 7 is provided on the upper part of the device.
And a photoelectric scanning element 7b including a document scanning section 7a and a color separation filter.
The exposure optical device 3 forms a color-separated electrostatic latent image on the photosensitive drum 100 in accordance with the above signal.

The developing device 4 includes four developing units, for example, a yellow developing unit 4Y using yellow toner, a magenta developing unit 4M using magenta toner, a cyan developing unit 4C using cyan toner, and a black developing unit 4BK using black toner. It is provided and set on the four moving mechanisms that operate independently as described above. Then, by the action of these moving mechanisms, a required developing unit is selectively brought into contact with the photosensitive drum 100 to perform a developing operation.

Due to the disposition of the developing device 4, only the yellow moving mechanism has a configuration in which it slides with an inclination of lower left-lower right (in the direction of arrow Z in the figure), which is slightly different from the vertical slide described above.

The transfer system 50 includes a transfer drum 50b having a gripper 50a, a transfer discharger 50c is provided inside the transfer drum 50b, and the recording paper supported by the transfer drum 50b is subjected to toner development on the photosensitive drum 100. The toner image is transferred to the recording paper from the photosensitive drum 100 at the transfer position. This process is sequentially repeated for each toner to form a full-color image on the recording paper. The recording paper is supplied from the cassette 41 or the manual feed section 41T, and when the transfer is completed, the recording paper is separated from the transfer drum 50b by the separating means 8, conveyed to the fixing section 9 and fixed, and then stored on the tray 10. To be done.

FIG. 15 shows the developing units 4Y and 4Y.
The arrangement relationship between M, 4C, and 4BK and the respective toner storage portions (hoppers) for the arrangement is shown.

The toner replenishing device 200 includes a yellow toner hopper 201Y, a magenta toner hopper 201M, a cyan toner hopper 201C, and a black toner hopper 2 which store color toners to be replenished in respective developing units.
01BK is fixed to a support frame 202 provided outside the front plate of this embodiment in the same order as the developing unit.

Each of the toner hoppers 201Y to 201BK has a toner replenishing port 4 depending on the developing operation of each developing unit.
00Y, 400M, 400C, 400BK (10 in FIG. 9
(Corresponding to 4d) and the toner discharge ports 203Y, 203M, and 203 so that the toner can be replenished.
C and 203BK are provided.

The toner stored in each of the toner hoppers 201Y to 201BK is supplied to the toner discharge port 2 by means of toner conveying paths 300Y to 300BK in which a screw is arranged.
03Y to 203BK and are discharged to the toner supply ports 400Y to 400BK of each developing unit.

In some cases, the toner conveying path may be arranged horizontally depending on the position of the toner discharge port, such as magenta, cyan, and black toner conveying paths 300M, 300C, and 300BK in FIG. It may be arranged in the axial direction like the yellow toner transport path 300Y.

16 to 18 are top views of the toner hopper portion. In FIG. 16, a support frame 202 that supports the toner hopper is composed of four sides of a rectangle, one side of which 20
2a is fixed to the support plate 270 by the pivot 250 and the screw 260. The support plate 270 is supported by the protruding support portion 110B of the front plate 110 of the main body via a slide rail 280. The other side 202b of the support frame 202 is supported by the guide member 290a fixed to the front plate 110 of the main body by the protrusion 220a protruding from the side 202b. The support frame 202 is movable in the horizontal front-rear direction with respect to the front plate 110 of the main body by expansion and contraction of the slide rail 280 supported in parallel with the protruding support portion 110B.

FIG. 17 shows a frame 202 and toner hoppers 201Y, 201M, 201C and 20 for replenishing toner.
It is a figure showing the state where 1BK was pulled out to the front side. As can be seen from the figure, the supply ports 400Y, 400 of the developing device
M, 400C, and 400BK project forward from the front plate 110 of the main body, are located immediately below the hopper discharge port in the hopper fixing position, and toner is replenished by free fall from the hopper discharge port.

Further, toner hoppers 201Y to 201BK
Is supported with respect to the main body of the apparatus so that it can be rotated for maintenance and inspection inside the machine. FIG. 18 is a view showing a state in which the toner replenishing device 200 is pulled out as shown in FIG. 17 for supplying toner, and then the toner replenishing device 200 is rotated to stand by at a position where in-machine maintenance is possible. Toner supply device 200
To put the toner replenishing device 200 into the waiting state, the screw 260 may be removed, and the toner replenishing device 200 may be moved to the position shown in FIG.

[0032]

Now, the attaching / detaching operation of the developing unit to / from the apparatus main body will be described. Due to its function, the developing unit is frequently maintained, and it is desirable that the developing unit can be easily attached and detached. However, in general, many functional parts are arranged around the photosensitive drum, and therefore it is usual to draw the developing unit in the axial direction of the photosensitive drum. Therefore, it is necessary to separate the developing unit and the photosensitive drum from each other to some extent so as not to contact and damage the photosensitive drum during the drawing of the developing unit.

However, the developing unit is close to the photosensitive drum only during the developing operation, and is apart from the photosensitive drum at other times. In this state, the toner discharging port of the toner hopper and the replenishing port of the developing unit are provided. Are still separated. Naturally, the replenishment operation from the hopper is not performed in that state, but even in such a case, some toner may be dropped due to the vibration of the apparatus or the impact from the outside.

As an example, there are the following cases. That is, when replenishing toner to the hopper, as shown in FIG. 17, if the entire hopper is once pulled out and then pushed in again, if a strong force is applied, an impact is generated at the moment of hitting the apparatus main body, In this case, a certain amount of toner drop cannot be avoided. As a result, there is a concern that the falling toner leaks from the gap between the toner discharge port of the toner hopper and the supply port of the developing unit, scatters inside the apparatus main body, and gradually contaminates the inside of the apparatus.

For example, if the dropped toner adheres to the corona charger, it causes uneven charging, which in turn causes image deterioration. Further, in the color image forming apparatus, when the dropped toner spreads to the developing units in the vicinity, a problem of color mixing occurs. In particular, in the case of a color image forming apparatus, since multicolor developing units are separated during development of a certain color, the separated state is long, resulting in a large amount of scattering. Moreover, in the color image forming apparatus, the developing unit is selectively brought into contact with or separated from the photosensitive drum, which is a serious problem.

If the distance between the developing units is reduced to prevent this, the possibility of damaging the photosensitive drum when the developing unit is attached or detached increases. Further, it is conceivable that the amount of the normal separation is reduced, and the amount of the separation when the developing unit is attached / detached is increased in three different states, but the configuration and the operation are complicated. Further, there is also a method in which the toner hopper is moved at the same time as the developing unit so as not to make a gap, but it is very difficult to realize it, and the size of the main body of the apparatus is increased.

Therefore, the main object of the present invention is to prevent the toner from scattering even when vibration or impact is applied to the apparatus body without complicating the maintainability of the apparatus body. Is to provide.

Further, another object of the present invention is to prevent contamination of the inside of the apparatus due to toner scattering even if vibration or impact is applied to the apparatus body without complicating maintenance of the apparatus body and accompanying it. An object is to provide an image forming apparatus capable of preventing image deterioration.

[0039]

The above object can be achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
A developing device for developing the latent image formed on the surface of the image bearing member with a developer, a moving mechanism for moving the developing device closer to and away from the image bearing member, and the developing device accommodating the developer. It has a hopper device that supplies a required amount of developer to the device and is fixed to the main body of the device during operation of the device, and supplies the developer from the hopper device to a protrusion formed at one end of the developing device. In an image forming apparatus provided with a replenishing port for receiving, when the developing device is in a separated state by the moving mechanism, the amount of separation of the developing device from the image carrier is toward the side where the replenishing port of the developing device is located. The image forming apparatus is characterized by gradually becoming smaller.

It is preferable that the moving mechanism is constructed so as to rotate about the vicinity of the supply port of the developing device. According to another aspect, the moving mechanism has a cam or a link mechanism near both ends in the axial direction of the image carrier, and the moving amount of the developing device by the cam or the link mechanism near the replenishment port. Is preferably smaller than the amount of movement on the side far from the supply port. It is preferable that the developing device is detachably held on the moving mechanism along the axial direction of the image carrier.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

First Embodiment A first embodiment of the image forming apparatus according to the present invention will be specifically described with reference to FIGS. The present invention is applied to a color image forming apparatus in which the present invention is considered to be particularly effective. Members having the same functions and configurations as those of the above-described conventional device are designated by the same reference numerals.

As shown in FIG. 1, the color image forming apparatus of this embodiment has a digital color image reader section in the upper part and the printer section in the lower part.

In the reader unit, the original 30 is placed on the original glass 31 and is exposed and scanned by the exposure lamp 32. Then, the reflected light image from the original 30 is condensed by the lens 33 on the full-color sensor 34 to obtain a color-separated image signal. This signal passes through an amplifier circuit (not shown), undergoes various processing in a video processing unit (not shown), and is then sent to the printer section.

The printer section has a configuration as described below. A photosensitive drum 1 as an image bearing member is rotatably supported at its center, and is rotationally driven in the arrow direction by a motor (not shown). The pre-exposure lamp 11, the primary charger 2, the exposure optical system 3 by a laser, the potential sensor 12, the developing device 4, the on-drum light amount detection means 13, the transfer drum, facing the outer peripheral surface of the photosensitive drum 1 in the order of its rotation direction. 5, a cleaning device 6 is arranged.

The pre-exposure lamp 11 and the primary charger 2 apply a uniform charge amount to the surface of the photosensitive drum 1.
Then, the optical system 3 exposes a light beam, such as a laser beam E, which is modulated according to the recording image signal, onto the photosensitive drum through the polygon mirror 3A, the lens 3B, the reflection mirror 3C, etc. Form an image.

The developing device 4 includes four developing units 4Y and 4Y which respectively store four color developers (hereinafter referred to as toners) of yellow, cyan, magenta and black.
C, 4M, and 4BK are arranged side by side, and are configured to be movable so as to be selectively close to the photosensitive drum 1 by the operation of the eccentric cam. This movement function (details of which will be described later) visualizes the electrostatic latent image.

On the downstream side of the image transfer area, the cleaning device 6 cleans the drum surface by scraping off the toner left on the photosensitive drum without being transferred to the recording paper.

An image is formed with toner by the process described above.

The present apparatus is equipped with a three-stage cassette paper feeder consisting of top, top, middle and bottom tiers and one manual paper feeder. The upper, middle, and lower cassette sheet feeders have the same configuration, and only the middle cassette sheet feeder among them will be described, and description of the other cassette sheet feeders will be omitted.

The paper feeding unit 40 conveys the cassette 41 for accommodating the recording paper P, the pickup roller 42 for feeding the recording paper one by one from the cassette, and the recording paper fed from the pickup roller to the transfer / conveyance unit. Paper feed rollers 43A and 43B, transport rollers 45A, 45B and 45C, and a paper guide. The manual feed section includes a manual feed tray 41T, a paper feed roller 42M (and a separation pad (not shown)), and the like.

Downstream of the paper feed unit 40, a conveyance roller 46 for guiding the recording paper which is inherited from the paper feed unit, pre-registration conveyance rollers 47A and 47B, and recording paper according to the image forming timing of the image forming unit. The transfer drum 5 described later
It has a pair of registration rollers 44 for sending out to and a guide for guiding the recording paper between these rollers. still,
The conveying roller 46 is a curling roller for curling the recording paper in the direction in which the recording paper is wound around the transfer drum 5.

The transfer drum 5 will be described with reference to FIG. The transfer drum 5 includes an annular member 55 arranged to face each other.
It is formed by winding a transfer sheet film 55S in a cylindrical shape around a frame 55F in which A is connected by a connecting member 55B. Examples of the material of the transfer sheet film 55S include PET (polyethylene terephthalate)
PVdF (polyvinylidene fluoride) or the like is used.

Referring again to FIG. 1, the registration roller pair 44
The suction roller 5G is supported at a position where the recording paper P sent from the recording medium P protrudes into the transfer drum 5 so that the suction roller 5G can be brought into and out of contact with the transfer drum 5.
A back-up member and an attraction charger 5C are arranged on the opposite side with the pressing force of the roller opposed to each other.

In the image transfer area where the photosensitive drum 1 and the transfer drum 5 face each other, the transfer charger 5B is arranged on the back side of the transfer sheet film. A separating member for separating the recording paper, specifically, a discharging charger 5H, a separating claw 8A, a transfer sheet pushing roller 8B, and the like are provided downstream thereof, and subsequently, a transferring sheet discharging charger 5D, 5
E is arranged so as to sandwich the transfer sheet film 55S.

Further downstream, the brush roller 14 and the corona discharger or brush type static eliminator 15 for cleaning the toner and paper dust adhering to the recording sheet holding surface of the transfer sheet film, and the fixing unit are used. Oil may adhere to the surface of the transfer sheet film through the recording paper during double-sided recording (described later), and an oil removing roller 16 and a backup brush 17 for cleaning the oil are provided.

The transfer drum 5 is constructed so as to be separable from and in contact with the photosensitive drum 1, and is separated from each other except during normal operation. This is to prevent the transfer drum 5 and the photosensitive drum 1 from coming into contact with each other for a long time and damaging the surface. The transfer drum 5 and the photosensitive drum 1 each have a gear flange at one end thereof, and when both drums are in contact with each other, the gears mesh with each other and the rotation of the photosensitive drum 1 is transmitted to the transfer drum 5 side.

The fixing unit 9 includes a fixing roller 9A having a heat source such as a halogen heater therein, a pressure roller 9B which is pressed against the fixing roller 9A (this roller may also have a heat source), and the roller pair. A transport belt 9C and an entrance guide 9D for guiding the recording paper to the nip portions of 9A and 9B,
Further, the recording sheet discharged from the roller pair 9A, 9B is further composed of a sheet discharging roller 9E for guiding the recording sheet to the outside of the apparatus.

Next, a mechanism for automatically recording images on both sides of the recording paper will be described. A transport path switching guide 19 is provided immediately downstream of the fixing unit 9 so that after fixing, either the paper path discharged outside the machine or the paper path for double-sided recording is automatically selected. The double-sided recording paper path includes a conveyance vertical path 20, a reverse path 21A, and a reverse roller 21.
B, the intermediate tray 22, and the like, and the recording paper, which is once guided to the reverse path 21A, is sent by the reverse rotation of the reverse roller 21B in a direction opposite to the direction in which the trailing end when sent is the first and the intermediate. It is stored in the tray 22. After that, the paper is fed from the intermediate tray 22 again, and an image is formed on the other surface of the recording paper by the image forming process described above.

A plurality of guides are selectively moved up and down in the guide portion 23 at the upper part of the intermediate tray according to the size of the recording paper to be stored. As a result, sheets of any size can be stored and stacked at the top of the intermediate tray.

The control unit comprises a control board and a motor drive board for controlling the operation of the mechanism in each unit.

Next, a further explanation will be given according to the operation of the apparatus. The case of feeding paper from the cassette feeding device in the middle stage will be described.

When the image forming operation start signal is issued, the cam 71 first makes a half rotation, and accordingly the transfer drum 5 swings to move to the operating position, and the gears of the transfer drum 5 and the flange of the photosensitive drum 1 mesh with each other. Therefore, it rotates in synchronization with the photosensitive drum 1. At the same time, the pickup roller 42 feeds the recording paper P one by one from the cassette 41. The paper feed rollers 43A and 43B and the transport rollers 45B and 4
5C guides the paper between the paper feed guides and conveys it to the conveyance roller 46. The recording paper is curled by a predetermined amount in the direction in which the recording paper is wound around the transfer drum when passing through the roller 46.

Thereafter, pre-registration transport rollers 47A and 47B
Also, it is conveyed to the registration roller 44 while changing the conveying direction by the action of the paper guide. Then the registration roller 4
4 is stopped, and the leading end of the recording paper hits the nip portion of the registration roller 44. And after a certain time,
The driving of the transport rollers is stopped. After that, the registration roller 44 and the pre-registration conveyance roller 47A after a predetermined time based on the timing when the image forming unit starts forming an image,
47B starts rotating. The timing of this rotation is set so that the recording paper and the toner image on the photosensitive drum coincide with each other in the image transfer area.

When the recording paper enters and contacts the transfer drum 5, it is electrostatically adsorbed on the transfer sheet film 55S by the corona discharge from the adsorbing charger 5C and the action of the adsorbing roller 5G. The suction roller 5G is normally separated from the transfer drum 5 to reduce the load, and is brought into pressure contact with the transfer drum 5 only when the recording paper is inserted. The transfer drum rotates in synchronization with the photosensitive drum, and the recording paper is conveyed to the image transfer area while being held on it.

Therefore, after the toner image formed on the photosensitive drum by the above-mentioned process is transferred onto the surface thereof by the transfer charger 5B, the recording paper is conveyed to the separating section. Here, since one color image is transferred at one time,
In the case of a single color image, the paper is separated by the operation described later, but in the case of forming a multicolor image, the separation operation is not performed, and the paper is held once on the transfer drum, and the paper is conveyed once again to the transfer area. . Then, the next toner image is further transferred onto the previous image, and this process is repeated as many times as necessary. The brush roller 14 and the like are supported so as to be separable from and in contact with the surface of the transfer drum, and are separated at least in the multiple transfer step.

Upon completion of the transfer process, the recording paper is transferred by the action of the discharging charger 5H in the separating portion to reduce the attraction force between the recording paper and the transfer sheet film 55S, and the subsequent operation of the separating claw 8A or the like. Separated from drum 5.

The recording paper P separated from the transfer drum 5 is conveyed to the fixing unit 9 by the conveying belt 9C and accurately guided on the entrance guide 9D to the nip portion of the fixing roller. Then, the toner image is fixed on the surface of the recording paper by the heat of the roller 9A. After that, the recording paper is conveyed by the paper discharge rollers 9E, and the recording paper is discharged to the paper discharge tray 10 outside the machine. Finally, the transfer drum 5 is separated from the photosensitive drum 1 to the retracted position, and the apparatus stops.

Here, the case of double-sided recording will be described. When the switching guide 19 operates, the recording paper on which one side is recorded and fixed is guided to the conveyance vertical path 20, and then the recording paper P ′ is reversed by the reversing roller 21B through the reversing path 21A and is stored in the intermediate tray 22. It After the required number of sheets are stacked, the single-sided recording paper P ′ is sent out from the intermediate tray 22 one by one by the pickup roller 25, and the paper feed rollers 26A, 2
It is conveyed to the conveying roller 46 by 6B or the like. After that, an image is recorded on the other surface of the recording paper by going through the same steps as described above. Finally, the recording paper is discharged to the paper discharge tray 10 outside the machine without operating the switching guide 19.

Now, the moving mechanism of the developing unit and its operation will be described in detail with reference to FIGS.
In this description, only the points different from the conventional example described with reference to FIG. 10 will be described.

The moving frame 61 of the moving mechanism 60 has a guide pin 112 whose back side is fixed to the body rear side plate 111.
And is supported so as to be vertically slidable with respect to the main body.

On the other hand, there is a round hole on the front side of the moving frame 61, and the swing center shaft 115 fixed to the bending and raising surface 110A of the front plate 110 of the main body is fitted into the round hole. Moving frame 6 centered on the moving center axis 115
1 is rotatably supported up and down. Front and rear side plates 1
A cam shaft 113 is rotatably supported by 10, 111, and a pressure cam 114B is fixed at one position on the back side of the cam shaft 113.

Then, the bent portion 121B of the moving frame 112 is provided on the outer peripheral surface of the pressure cam 114B via the leaf spring 122.
Are in contact. By controlling the rotation of the cam shaft 113, the pressure cam 114B repeats two states as in the conventional example, and the moving frame 61 is interlocked with the operation of the pressure cam 141B.
Swings. FIG. 2 shows a state in which the developing unit 4 is close to the photosensitive drum 1, and FIG. 3 shows a state in which both are separated.

A feature of this embodiment is that the center of rotation of the moving mechanism 60 is arranged near the toner supply port 400 of the developing unit 4 to rotate the moving mechanism 60. Accordingly, even in the separated state, there is almost no gap between the toner discharge port 203 of the toner hopper 200 and the supply port 400 of the developing unit 4. FIG. 4 is an explanatory diagram showing the difference between the present embodiment shown by the solid line and the conventional example shown by the two-dot chain line when the developing unit is in the separated state.

The distance between the photosensitive drum 1 and the developing roller 101 will be described below. Since the distance between the photosensitive drum 1 and the developing roller 101 is parallel in the prior art, the distance between the front and rear is about 7 mm, and a similar gap is formed between the replenishment port and the discharge port. Oops. On the other hand, in this embodiment, the front gap g ₁ is 4 mm and the rear gap g ₂ is 14 m.
m, the gap between the toner supply ports is 1 mm or less.

Although the gap on the front side is smaller than that of the conventional one by about 3 mm, the risk of contact with the photosensitive drum when the developing unit is attached or detached does not immediately increase. The reason is that the worker presses the developing unit with his / her hand near the front plate of the main body, so that the developing unit hardly flutters on the front side of the photosensitive drum. On the contrary, since the gap is wide on the back side, which is the most prone to flutter, the possibility of damaging the photosensitive drum is reduced.

The two-dot chain line in FIG. 3 shows a state in which the developing unit is pulled out substantially along the axial direction of the photosensitive drum. Here, in the same way as in the conventional example, in order to secure a working space for maintenance of the apparatus including attachment and detachment of the developing unit,
The hopper is configured to be easily retracted from its location.

When the present invention is implemented with the configuration described above, the following effects are obtained. Even if vibration of the apparatus occurs, the toner dropped from the hopper discharge port hardly leaks to the outside, and the inside of the machine can be prevented from being contaminated. As a result, image deterioration does not occur, and it becomes possible to always maintain good quality. Further, since there is almost no risk of damaging the drum surface by contacting the photosensitive drum when the developing unit is detached from the main body, the work can be easily performed. Further, there is an advantage that the device does not become large in size because it does not require a specially complicated mechanism.

Second Embodiment Next, a second embodiment according to the present invention will be described with reference to FIGS. In the first embodiment, the center of rotation of the moving mechanism is arranged near the toner replenishing port of the developing unit. However, depending on the apparatus, there may be a case where a space for arranging the moving mechanism cannot be secured. Considering this, another embodiment of the present invention will be described below.

FIG. 5 shows a side view when the developing unit is separated in this embodiment. The main difference between the first embodiment and the conventional example is that two pressure cams 114B and 114C are arranged at the back and the front, and the shapes of both are changed. That is, the cross-sectional shapes of the cam 114B at the back and the cam 114C at the front are as shown in FIG.
As shown in, when the developing unit is close to the photosensitive drum, the maximum cam height of the inner cam 114B is set to be larger than the maximum cam height of the front cam 114C. The heights are set equal.

In addition, the leaf spring 12 of the moving frame 71
The height of the bent portion 71B for making contact with the pressure cams 114B and 114C via 2 is set so that the front side is lower than the back side.

When the pressure cams 114B and 114C are at the position of the top dead center, that is, when the developing unit 4 is close to the photosensitive drum 1, the maximum cam height of the pressure cams is as shown in FIG. The back is higher than the front. However, since the height of the bent portion 71B of the moving frame 71 is lower on the front side, the moving frame 71 becomes substantially horizontal, and the abutting rollers 108 on the front side and the back side of the developing unit abut on the abutting block 109 of the main body with substantially the same pressing force. Applied.

On the other hand, when the cam is at the bottom dead center position, that is, when the developing unit is at the separated position, the heights of the upper surfaces of the cams are the same, but the heights of the bent portions 71B of the moving frame 71 are different. The moving frame 71 is tilted, and as a result, the developing unit is tilted. At this time, the actual separation amount is such that the gap between the photosensitive drum and the developing roller is 4 mm in the front and 8 mm in the back, and the gap between the toner supply ports is 2.5 mm.
It is the following.

In this embodiment, there is a slight gap in the toner supply port, but it has been confirmed that practically no problem occurs with this amount. In addition, there is almost no risk of damage when the developing unit is attached or detached. Of course, it is also possible to review the shape of the pressure cams on the front side and the back side, and the shape may be set to an optimum shape as appropriate in the device to which the present invention is applied.

In this embodiment, since it is not necessary to secure a space for the moving mechanism near the replenishing port of the developing unit, there is an advantage that the degree of freedom in designing the apparatus is increased.

Although a cam is used as an example of the moving mechanism so far, the present invention is not limited to this, and the same effect can be obtained by using a link mechanism. Further, although the drum-shaped one has been described as the photoreceptor, it may have a belt-shaped one. Further, the effect of the present invention is highest when the developing device is attached / detached in the axial direction of the photoconductor, but the effect can be sufficiently obtained even in the case of a device that pulls out in a direction other than the axial direction of the photoconductor.

[0087]

As is apparent from the above description, in the image forming apparatus of the present invention, when the developing device is in the separated state by the moving mechanism, the distance from the image carrier is the supply port of the developing device. By being configured to be smaller toward the side, the following effects can be obtained.

1. Since toner is not scattered from the discharge port of the hopper to the outside, the inside of the machine is not contaminated, and as a result, a good transferred image without image deterioration can always be obtained.

2. There is almost no risk of damaging the photoconductor during maintenance of the developing device, and the work can be performed easily.

3. The device size does not increase because no specially complicated mechanism is required.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an image forming apparatus embodying the present invention.

FIG. 2 is a side view showing the moving mechanism of the first embodiment according to the present invention, showing a state in which the developing unit is close to the photosensitive drum.

FIG. 3 is a side view showing a state where the developing unit is separated from the photosensitive drum by the moving mechanism of FIG.

FIG. 4 is a partial side view comparatively showing the separated state of the developing unit in the first embodiment and the conventional example.

FIG. 5 is a configuration diagram showing a second embodiment of the moving mechanism according to the present invention.

FIG. 6 is an explanatory diagram showing a cam shape according to the second embodiment.

7 is a configuration diagram showing a transfer drum in the image forming apparatus of FIG.

FIG. 8 is a sectional view showing a developing device.

FIG. 9 is a development view of the developing device in FIG.

FIG. 10 is a side view showing a conventional moving mechanism.

11 is a front view of the moving mechanism shown in FIG. 10, showing a proximity state.

12 is a front view of the moving mechanism of FIG. 10, showing a separated state.

FIG. 13 is a sectional view showing a detailed configuration of a hopper device.

FIG. 14 is an overall configuration diagram showing a conventional image forming apparatus.

FIG. 15 is a schematic configuration diagram of a hopper device.

FIG. 16 is an explanatory view showing the operation of the hopper device,
It shows a state in which the hopper device is set on the developing device.

FIG. 17 is an explanatory diagram showing a state in which the hopper device of FIG. 16 is pulled out to the front side.

FIG. 18 is an explanatory view showing a state where the hopper device of FIG. 17 is rotated.

[Explanation of symbols]

1 photosensitive drum (image carrier) 4 developing device 4M, 4C, 4Y, 4BK developing unit 60, 70 moving mechanism 61, 71 114A, 114B, 114C pressure cam 200 toner hopper 400M, 400C, 400Y, 400BK developing device supply port

Claims (4)

[Claims] 1. A developing device for developing a latent image formed on a surface of an image bearing member with a developer, and a moving mechanism for moving the developing device closer to or away from the image bearing member.
A hopper device that contains a developer and replenishes the developing device with a required amount of the developer and is fixed to the main body of the device during operation of the developing device, and the hopper is provided at a protruding portion formed at one end of the developing device. In an image forming apparatus provided with a replenishment port for replenishing the developer from the apparatus, when the developing device is in a separated state by the moving mechanism, the amount of separation of the developing device from the image carrier is the replenishment of the developing device. An image forming apparatus characterized in that it gradually becomes smaller toward the mouth side. 2. The image forming apparatus according to claim 1, wherein the moving mechanism rotates about a vicinity of a supply port of the developing device. 3. The moving mechanism has cams or link mechanisms near both ends in the axial direction of the image carrier, and the moving amount of the developing device by the cam or link mechanism near the replenishment port The image forming apparatus according to claim 1, wherein the amount of movement is smaller than that on the side far from the supply port. 4. The image forming apparatus according to claim 1, wherein the developing device is detachably held on the moving mechanism along the axial direction of the image carrier.