JP2003330267A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device in which sticking and slippage caused by the contact and the relative movement of a developer carrier with a regulating member are prevented in a device using a regulating roller as a developer regulating member and an image forming apparatus in which the unevenness of image density is prevented. <P>SOLUTION: The regulating roller 130 is pressed to the side of a developing roller 110 by a spring 132, so as to abut on the developing roller. Toner rubbed on the developing roller by a supply roller 120 enters a regulation nip between the regulating roller and the developing roller, and a uniform developer layer is formed in a thrust direction on the surface of the developing roller. Then, the regulating roller 130 is constituted so that the ASKER C-type hardness of the surface is set in the range of ≥35 and ≤60. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus used in copying machines, facsimiles, printers and the like.

[0002]

2. Description of the Related Art Conventionally, as a developing device of this type, there is one having a developer carrying member for carrying a developer on its surface and a developer regulating member for regulating the amount of the developer on the developer carrying member. Then, there is a blade type in which a regulating blade is used as a developer regulating member for regulating the amount of the developer carried on the surface of a developing roller or the like used as the developer carrying member. FIG. 3 is a schematic configuration diagram showing an example of a blade type developing device. This developing device includes a developer carrier 2, a developer supply member 3, a regulating blade 4, a developer hopper 5, three developer transport members 6a, 6b, 6c, a discharge paddle 7, and the like. The regulating blade 4 is a cantilever having one side supported and one side free end, and the free end side is pressed against the developer carrying member 2. The developer adhering to the surface of the developer carrying member 2 by the developer supplying member 3 is partially passed through the restricting nip which is the contact portion between the tip of the restricting blade 4 and the developer carrying member 2. It The amount of the developer adhering to the surface of the developer carrier that passes to the downstream side of the regulation nip and the amount of which the passage is regulated are determined by the shape of the regulation nip and the contact pressure of the regulation blade 4. Further, the developer passing through the regulation nip is subjected to frictional electrification when passing through the regulation nip, and a developer layer having a uniform and stable electrification is formed,
It is sent to the development section. The developer scraped off by the regulation blade 4 is returned to the hopper 5 side by the discharge paddle 7.

In the above-mentioned blade system, the toner is charged by the mechanical friction of the toner at the contact portion between the developer carrying member 2 and the regulating blade 4. Therefore, if the rotational linear velocity of the developer carrying member is increased in order to increase the printing speed, the stress on the toner increases. Then, the toner is aggregated at the regulation nip, that is, the contact portion between the developer carrying member and the regulation blade,
Eventually, toner adheres to the surface of the regulation blade. In this way, at the position where the surface of the regulation blade on which the toner is fixed and the developer carrying member are in contact with each other, the toner cannot pass through and the toner clogging easily occurs. When the toner clogging occurs, there is a problem in that the amount of the toner sent from this position to the developing unit is insufficient and white streaks occur in the image. As the regulating blade, examples of using a urethane rubber blade or a metal blade are known, but in all cases, white stripes are generated due to clogging of toner.

Therefore, instead of the regulating blade, a roller type using a roller-shaped developer regulating member has been proposed. FIG. 4 is a schematic configuration diagram showing an example of a roller type developing device. This developing device is provided with a regulating roller 130 instead of the regulating blade 4 shown in FIG. The developing device has a cleaning roller 1 for reversing the rotation direction of the developer carrying member and removing the residual toner after development from the surface of the developer carrying member, unlike the developing device of FIG.
0 is set. Further, the regulation rollers 130 move their surfaces in opposite directions in the same direction as the developer carrying member, that is, the nip portion with the developer carrying member 2, and rotate at a low speed.
It has been found that such a roller system has an effect of preventing the occurrence of white lines as in the blade system. Specifically, there is a track record that white stripes did not occur even when a toner cartridge was replaced 10 times or more in an apparatus of a system in which a metal regulation roller and an elastic developing roller are used and the regulation roller is constantly rotated.

The reason why white streaks can be prevented by the roller system as described above is as follows. When the surface of the regulation roller 130 moves in the opposite direction to the surface of the developer carrying member, aggregated toner, foreign matter, etc. are returned to the inside of the developing device without being accumulated in the regulation nip. Therefore, the toner clogging at the regulation nip does not occur, and it is possible to prevent the occurrence of white stripes. As described above, it was found that the roller system using the roller-shaped developer regulating member can prevent the occurrence of white stripes due to toner clogging, as compared with the blade system. Note that it is not limited to the regulation roller that the white streak caused by such toner clogging can be prevented. The same can be prevented as long as it is provided so as to contact the surface of the developer carrier, and the opposing surfaces thereof move in the direction opposite to the moving direction of the surface of the developer carrier at least during development. .
Further, if it is further expanded, if the regulating member that comes into contact with the surface of the developer carrying body moves relative to the surface of the developer carrying body, it is possible to avoid toner or foreign matter from staying in the regulating nip, and it is possible to prevent toner clogging. White spots that occur can be prevented.

[0006]

However, in a developing device using a regulating member that makes surface contact with the surface of the developer carrying member and moves relative to the surface of the developer carrying member, uneven image density may occur. I knew it was. For example, in the case of a regulation roller, the surfaces of the developer carrying body and the regulation roller are moved relative to the surface of the developer carrying body while being in contact with each other, so that their surfaces are rubbed against each other. It has been found that the surfaces of the developer carrying member and the regulation roller do not slide smoothly and make a series of movements (hereinafter referred to as stick-slip) in which they are caught or slipped to each other, and vibration may occur. When an image is formed using a developing device that generates such vibration, the toner layer is disturbed, and the density of the formed image is not uniform, resulting in a problem of uneven image density. And such a stick
Slip may occur similarly when a regulation member other than the regulation roller is used which is in surface contact with the surface of the developer carrying body and moves relative to the surface of the developer carrying body.

The present invention has been made in view of the above background, and an object of the present invention is to provide a developing device and an image forming apparatus which use, as a developer regulating member, a regulating member which makes surface contact with the surface of a developer carrying member while moving relative to the surface of the developer carrying member. , To enable: That is, the first object is to provide a developing device capable of preventing the occurrence of stick-slip between the developer carrying member and the regulating member. A second object is to provide an image forming apparatus in which uneven image density due to stick / slip does not occur.

[0008]

When the present inventors have investigated the cause of the stick-slip, the hardness of the surface of the developer-regulating member (Asker C hardness) is one of them. I understood. When the Asker C hardness of the surface of the developer regulating member is low and the surface is elastic, the surface of the developing roller is easily deformed at the regulating nip, which causes stick-slip. Further, an elastic body may be used for the developing roller used as the developer bearing member, but in this case, the surfaces of the developer regulating member and the developing roller are easily deformed at the regulating nip, and stick / slip is prevented. Likely to happen. There is also a case where a regulation roller having a metal surface is used as the developer regulation member. The surface of the metal roller is hard and stick-slip is less likely to occur, but in that case, since the regulation roller surface is less likely to deform, pressure deviation occurs between the regulation roller and the developing roller surface, and the pressure distribution is It tends to be uneven. Therefore, it is not preferable to simply harden the surface of the developer regulating member. In order to achieve the first object, the developing device according to claim 1 is a developer carrying member carrying a developer on its surface, and a developer on the developer carrying member in contact with the surface of the developer carrying member. A developing device having a developer regulating member having a regulating surface for regulating the amount, wherein the latent image is developed by the developer on the developer carrying member whose developer amount is regulated by the developer regulating member. The restriction surface of the developer restriction member is configured to be movable relative to the developer carrier during the forming operation, and the surface hardness of at least one of the restriction surfaces of the developer carrier and the developer restriction member. Is set to a hardness such that stick-slip does not occur due to contact and relative movement between the two. A developing device according to a second aspect is the developing device according to the first aspect, wherein the developer regulating member is constituted by a roller-like regulating roller, and a hardness of the regulating roller surface is 35 degrees or more in Asker C hardness, 60 degrees or more. It is characterized in that it is less than or equal to the degree. The developing device according to claim 3 is the developing device according to claim 1 or 2, wherein the surface of the developer carrying member is easily charged to a polarity opposite to the predetermined polarity of the developer as compared with at least a metal. It is characterized by being composed of a charged material. A developing device according to a fourth aspect is the developing device according to the first, second, or third aspect, in which at least one surface of the developer carrier and the regulation surface of the developer regulating member has a reduced surface energy. It is characterized in that it is composed of a substance for reducing surface energy. Further, a developing device according to a fifth aspect is characterized in that, in the developing device according to the fourth aspect, a fluorine-containing resin is used as a surface energy lowering substance constituting the regulation surface. In the developing device according to claims 1, 2, 3, 4, and 5, the surface hardness of at least one of the developer carrier and the developer regulating member is set as follows. Even if the surface of the developer carrying member and the restricting surface of the developer restricting member come into contact with each other at the restricting nip and move relative to each other, sticking or slipping occurs due to deformation of at least one of the surface of the developer carrying member and the developer restricting member. The hardness is such that no crack occurs. Therefore, the lower limit of the surface hardness of at least one of the two, that is, the softer limit is set. As a result, even if the surface of the developer carrying member and the surface of the developer regulating member move relative to each other at the regulating nip, the surface of the developer regulating member is prevented from being excessively deformed to cause stick-slip. It is also possible to set the relationship between the surface hardness of the developer carrier and the surface hardness of the developer regulating member such that stick-slip does not occur. In order to achieve the second object, the image forming apparatus according to claim 6 is an image forming apparatus having a latent image carrier for carrying a latent image on its surface and a developing device for developing the latent image. The developing device as claimed in claim 1,
The developing device of 3, 4, or 5 is used. In the image forming apparatus according to the sixth aspect, the latent image is developed by using the developing device that does not cause stick-slip. This prevents vibration due to stick-slip during the image forming operation, from the developing area to the area that affects image formation.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment in which the present invention is applied to an electrophotographic color printer (hereinafter referred to as a color printer) which is an image forming apparatus will be described below. First, the schematic configuration and operation of the color printer according to this embodiment will be described with reference to FIG. The color printer 1 includes a photoconductor unit 10 and a writing optical unit 2.
0, developing unit 30, intermediate transfer unit 40, secondary transfer unit 50, fixing unit 60, double-sided printing paper reversing unit 70, and the like. Then, the following four color images are printed on the photoconductor belt 11 of the photoconductor unit 10.
The images are sequentially visualized on top of each other, and these are superposed to form a final four-color full-color image. The four colors are Black: black (hereinafter referred to as Bk), Cyan: cyan (hereinafter referred to as C), Magenta: magenta (hereinafter referred to as M), and Yellow: yellow (hereinafter referred to as Y).

The photoconductor belt 11 rotates clockwise in the direction of arrow A, and around the photoconductor belt 11, the photoconductor cleaning device 1 is provided.
2, the charging roller 13, the selected developing device of the developing unit 30, the intermediate transfer belt 41 of the intermediate transfer unit 40, and the like are arranged. The photoconductor belt 11 is a drive roller 1.
4, which is stretched between the primary transfer counter roller 15 and the tension roller 16 and is rotationally moved in the direction of arrow A by a drive motor (not shown). When the photoconductor belt 11 having a joint is used, a joint mark is provided in a non-image forming area at the end of the photoconductor belt 11, a sensor (not shown) detects the joint, and an image is formed while avoiding the joint.

Further, the writing optical unit 20 is
The color image data is converted into an optical signal, and optical writing corresponding to each color image is performed to form an electrostatic latent image on the photoconductor belt 11. The writing optical unit 20 includes a semiconductor laser as a light source, a laser emission drive control unit (none of which is shown), a polygon mirror 22, and three reflection mirrors 2.
3a, b, c and the like.

The developing unit 30 includes a Bk developing device 31K, a C developing device 31C, an M developing device 31M, and a Y developing device 31Y, and moves the developing devices in the left-right direction in the drawing to contact the photosensitive belt 11. It is composed of a contacting / separating mechanism (not shown) that performs a separating operation. The developer accommodating cases 32K, C, M, and Y of the developing devices 31K, C, M, and Y accommodate one-component developers, which are toners of respective colors, as developers. In the illustrated example, a Bk developing device 31K containing black toner and a C containing cyan toner are sequentially arranged from the lower side of the apparatus main body.
Developing device 31C, M developing device 31 containing magenta toner
The Y developing device 31Y contains M and yellow toner. The contact / separation mechanism operates an electromagnetic solenoid (not shown) to cause the developer accommodating cases 32K, C, M, Y
Is moved to the photoreceptor belt 11 side (left side in the figure). At the time of development, any one of the developing devices 31K, C, M, and Y selected moves to move the photosensitive belt 1
Abut 1. On the other hand, when the electromagnetic solenoid is turned off, the developing device, which is in contact with the photoconductor belt 11, moves in the direction away from the photoconductor belt 11 (right side in the drawing) by the pull-back spring built in the electromagnetic solenoid. The developing devices 31K, C, M and Y will be described in detail later.

In the standby state of the color printer main body, the developing unit 30 is set at a position where all the developing devices 31K, C, M and Y are separated from the photosensitive belt 11. Then, when the printing operation is started, optical writing by laser light and electrostatic latent image formation start based on the color image data (hereinafter, the electrostatic latent image based on the Bk image data is referred to as Bk electrostatic latent image. C and M). , And Y). This Bk
Before the front end of the electrostatic latent image reaches the Bk developing position so that the front end of the electrostatic latent image can be developed, the developing roller 110 is started to rotate and the Bk electrostatic latent image is developed with the Bk toner. Then, after that, the developing operation of the Bk electrostatic latent image area is continued.
When the rear end of the electrostatic latent image k passes the Bk developing position, B
The k developing device 31K separates from the photoconductor belt 11, and the developing device of the next color immediately contacts the photoconductor belt 11. This is completed at least before the leading edge of the electrostatic latent image by the next image data reaches the developing position.

The intermediate transfer unit 40 is composed of an intermediate transfer belt 41, a belt cleaning device 42, a position detecting sensor 43 and the like. The intermediate transfer belt 41 is stretched around a drive roller 44, a primary transfer roller 45, a secondary transfer counter roller 46, a cleaning counter roller 47, and a tension roller 48, and is driven and controlled in the direction of arrow B by a drive motor (not shown). . A plurality of position detection marks (not shown) are provided in the non-image forming area at the end of the intermediate transfer belt 41. Any one of these position detection marks (the position detection mark that first passed the position detection sensor 43 at the start of the image forming operation)
Is detected by the position sensor 43, and image formation is started at this detection timing. Also, the belt cleaning device 4
2 is a cleaning brush 42a, a contact / separation mechanism (not shown)
Etc. While the first color Bk image is being transferred to the intermediate transfer belt 41, and while the second, third, and fourth color images are being transferred to the intermediate transfer belt 41, cleaning is performed from the surface of the intermediate transfer belt 41 by the contact / separation mechanism. Brush 42
a is separated. The toner cleaned from the surface of the intermediate transfer belt 41 is stored in the discharged toner tank 49 provided inside the intermediate transfer unit 40.

Transfer paper is stored in the transfer paper cassette 80 of the color printer 1, and the paper feed roller 81
Paper feed in the direction of the registration roller pair 82 by a, b, and c,
Be transported. On the right side surface of the color printer 1, O
Manual feed tray 83 for manual paper feed such as HP paper and thick paper
Is provided.

The secondary transfer unit 50 also includes a secondary transfer roller 51, a swing mechanism (not shown) having a clutch or the like for bringing the secondary transfer roller 51 into and out of contact with the intermediate transfer belt 41, and the like. It is composed of. The secondary transfer roller 51 swings around the rotation axis of the swing mechanism at the timing when the transfer sheet reaches the transfer position. The secondary transfer roller 51 and the secondary transfer counter roller 46 bring the transfer paper and the intermediate transfer belt 41 into contact with each other at a constant pressure. The secondary transfer roller 51 is maintained in parallel positional accuracy with the secondary transfer counter roller 46 by a positioning member (not shown) provided in the intermediate transfer unit 40. Further, the contact pressure of the secondary transfer roller 51 with respect to the intermediate transfer belt 41 is made constant by a positioning roller (not shown) provided on the secondary transfer roller 51. The secondary transfer roller 51 is connected to the intermediate transfer belt 4
When the secondary transfer roller 51 is brought into contact with the first transfer roller 51, a transfer bias having a polarity opposite to that of the toner is applied to the secondary transfer roller 51.
The superimposed toner image on 1 is collectively transferred to a transfer paper.

The above units can be easily attached to and detached from the apparatus. For example, in FIG. 2, when removing the intermediate transfer unit 40, it can be easily removed by opening a front cover (not shown) and sliding the unit from the back side to the front side of the paper surface.

In the color printer 1 having the above-described structure, when the image forming cycle is started, first, the photosensitive belt 11 is started.
Is rotated clockwise by arrow A and the intermediate transfer belt 41 is rotated counterclockwise by arrow B by a drive motor (not shown). A position detection sensor 43 detects a position detection mark (not shown) provided on the intermediate transfer belt 41. Then, Bk toner image formation, C toner image formation, and M toner image formation on the photoconductor belt 11 according to the detection timing of the position detection mark.
Toner image formation and Y toner image formation are performed. Finally B
Toner images are formed on the intermediate transfer belt 41 in the order of k, C, M, and Y. At this time, the bias applied to the primary transfer roller 45 is generally higher in sequence, but it differs depending on the resistance characteristics of the intermediate transfer belt 41 and the like.

The Bk toner image formation is performed as follows. The charging roller 13 is driven by an applied voltage from a power source (not shown).
Uniformly charges the photosensitive belt 11. Then, the laser light LD for writing performs exposure based on the Bk color image signal. When this exposure is performed, in the exposed portion of the photoreceptor belt 11 that is initially uniformly charged, the charge proportional to the exposure light amount disappears, and a Bk electrostatic latent image is formed. Then, the Bk toner on the developing roller 110 comes into contact with the Bk electrostatic latent image, so that the toner does not adhere to the portion of the photoconductor belt 11 where the electric charge remains, so that there is no electric charge, that is, the exposed portion. Bk toner is adsorbed on the. In this way, a Bk toner image similar to the electrostatic latent image is formed. Then, the Bk toner image formed on the photoconductor belt 11 contacts the intermediate transfer belt 41 at the primary transfer position. At this primary transfer position, the primary transfer rollers 45 and 1
A nip is formed between the intermediate transfer belt 41 and the photoconductor belt 11 by the next transfer counter roller 15. Then, the Bk toner image is transferred to the intermediate transfer belt 41 by applying a bias having a polarity opposite to that of the Bk toner image to the primary transfer roller 45.

A small amount of untransferred residual toner on the photoconductor belt 11 is cleaned by the photoconductor cleaning device 12 in preparation for reuse of the photoconductor belt 11. The toner collected here is stored in an exhaust toner tank (not shown) via a collection pipe.

On the side of the photosensitive belt 11, the Bk image forming process is followed by the C image forming process, and the position detecting sensor 4 is used.
Writing with the laser light LD based on the C image data is performed according to the detection timing of 3, and a C electrostatic latent image is formed. Then, after the trailing end of the previous Bk electrostatic latent image has passed and before the leading end of the C electrostatic latent image has arrived, the Bk developing device retracts from the developing position, and the C developing device C moves to the developing position. And the C electrostatic latent image is developed with C toner. After that, the development of the C electrostatic latent image area is continued, but when the trailing end of the C electrostatic latent image passes, the C developing device C retracts from the developing position as in the case of the Bk developing device B. , Next M developing device M is moved to the developing position. This is also completed before the leading edge of the next M electrostatic latent image reaches the developing position. Note that the M and Y image forming steps are the same as the above-described Bk and C steps in the electrostatic latent image forming and developing operations, and thus the description thereof is omitted.

On the intermediate transfer belt 41, Bk, C, M and Y toner images sequentially formed on the photosensitive belt 11 are formed.
By sequentially aligning on the same surface, a four-color toner image is formed. Then, in the next secondary transfer step, this 4
The color toner images are collectively transferred to the transfer paper.

At the time when the image forming operation is started, the transfer sheet is fed from either the transfer sheet cassette 80 or the manual feed tray 83, and stands by at the nip between the pair of registration rollers 82. Then, when the front end of the four-color toner image on the intermediate transfer belt 41 reaches the secondary transfer roller 51, the registration roller pair 82 is driven so that the front end of the transfer paper coincides with the front end of this toner image. . This will align the transfer paper and the toner image,
The transfer paper is superimposed on the toner image on the intermediate transfer belt 41 and passes through the secondary transfer position. At this time, the secondary transfer roller 51
The transfer bias charges the transfer paper, and most of the toner image is transferred onto the transfer paper.

The transfer paper on which the four-color superposed toner images are collectively transferred from the intermediate transfer belt 41 is the fixing unit 60.
Be transported to. Here, the toner image is melted and fixed in the nip between the fixing belt 61 and the pressure roller 62, which are controlled to a predetermined temperature, is sent out of the apparatus main body (in the direction of arrow C), and is stacked face down on the paper discharge tray 84 to be full color. Get a copy.

When performing double-sided printing, the transfer sheet that has passed through the fixing unit 60 is guided in the direction of arrow D by the discharge switching claw 85 and sent to the double-sided printing sheet reversing unit 70. After the trailing edge of the transfer paper passes through the paper transport switching claw 71,
The conveyance roller pair 72 stops, and the transfer paper also stops. Then, the conveying roller pair 72 starts reversing after a certain blank time, and the transfer sheet starts switchback. At this time, the paper transport switching claw 71 is switched, and the transfer paper is guided in the direction of arrow E and sent to the registration roller pair 82. The transfer sheet sent to the registration roller pair 82 is turned over and stands by at the nip of the registration roller pair 82. And
The registration roller pair 82 is driven at a predetermined timing,
The transfer paper is sent to the secondary transfer position and the four-color superposed toner images are collectively transferred from the intermediate transfer belt 41, and then the toner images are fused and fixed by the fixing unit 60 and sent out of the apparatus main body.

On the other hand, the surface of the photoconductor belt 11 after the primary transfer is cleaned by the photoconductor cleaning device 12 and uniformly discharged by a charge eliminating lamp (not shown). Also,
The surface of the intermediate transfer belt 41 after the toner image is transferred onto the transfer paper is cleaned by pressing the cleaning brush 42a of the belt cleaning device 42 with the contact / separation mechanism. The toner cleaned from the intermediate transfer belt 41 is stored in the discharged toner tank 49.

In the color printer according to this embodiment, the photosensitive belt is used as the latent image carrier, but a drum-shaped latent image carrier may be used by suppressing the hardness of the developing roller 110 to a low level. It is possible.

Next, the developing unit 30 will be described in more detail. Each color developing device 31 of the developing unit 30
Since K, C, M, and Y have the same configuration, the Bk developing device 31K will be described. FIG. 1 shows a Bk developing device 31.
It is a schematic block diagram of K. The Bk developing device 31K includes the following members and the like. A developing roller 110 that transfers the developer to the photoreceptor belt 11 to form a visible image, and the developing roller 110.
A developer supply roller 120 that supplies the developer while pre-charging. A roller-shaped regulating roller 130 as a developer regulating member that regulates the amount of developer adhered to the developing roller 110 and frictionally charges the developer, and a scraping member 131 that scrapes off the developer on the surface of the regulating roller 130. Further, a developer hopper 101, which is an accommodation space surrounded by a case for accommodating the developer so as not to leak out of the developing device, and three developers that convey the developer from the developer hopper 101 to the developer supply roller 120. Transport members 141, 142, 14
It is 3.

The developing roller 110 has a linear velocity ratio of 1.1 with respect to the photosensitive belt 11 in the same direction as the traveling direction of the photosensitive belt 11, that is, in the direction of the arrow CW (clockwise direction).
Rotating at ~ 2.0 times speed. Three developer transport members 1
41, 142 and 143 respectively rotate in the direction of arrow CW (clockwise) to supply the developer to the developer supply roller 120.
Transport to. The developer supply roller 120 is the developing roller 11
0 at a predetermined nip and rotated CCW (counterclockwise) to rub the developer on the surface of the developer supply roller 120 against the surface of the development roller 110 in the nip. As a result, the developer is supplied while being pre-frictionally charged. The peripheral speed ratio of the developer supply roller to the developing roller 110 is
It is preferable to select in the range of 0.5 to 0.9 times speed or 1.1 to 1.8 times speed. By the way, in a range close to a constant speed of 0.9 to 1.1 times, the charging of the toner is insufficient and the supplyability to the developing roller is deteriorated. If the speed is 0.5 times or less, the amount of toner to be supplied may be insufficient, and uneven density may occur in a solid image having a large area ratio. On the other hand, when the speed exceeds 1.8 times, the rubbing is too strong, and the temperature rises and the vibration occurs.

The regulating roller 130 urges the bearing portion 133 toward the developing roller 110 by the spring 132,
It is in contact with the developing roller 110 with a predetermined load.
The rotation direction of the regulation roller 130 can be selected in the same direction as the developing roller 110 (CW in the drawing) or in the opposite direction (CCW in the drawing). However, in the case of the reverse rotation, the toner may overflow from the restriction nip that is the nip between the restriction roller 130 and the developing roller 110 unless the speed is considerably reduced, and the arrangement of the driving means becomes slightly difficult. Therefore, the rotation direction of the regulation roller 130 is normally set to the developing roller 1.
It is easier to configure the unit if the direction is the same as 10. Further, by rotating in the same direction, even if aggregated toner and foreign matter are likely to be clogged in the regulation nip, they can be returned to the inside of the unit, and toner clogging is less likely to occur. Therefore, the risk of white stripes in the image is reduced. Also in this embodiment, the directions are the same. Also,
The rotation speed of the regulation roller 130 is slower than that of the developing roller 110. The contact direction of the scraping member 131 needs to be changed depending on the rotation direction of the regulation roller 130. In FIG. 2, the rotation direction of the regulation roller 130 is C.
It is arranged in the direction of the W direction. The toner rubbed by the supply roller is regulated by the regulating roller 130 and the developing roller 11.
It goes into the restriction nip between 0 and 0, and the passing amount is made uniform so that a uniform developer layer is formed in the thrust direction on the surface of the developing roller 110. Further, since the passed developer is frictionally charged by the surfaces of both the regulation roller 130 and the developing roller 110, the developer supplied to the photosensitive belt 11 may have a stable charge amount. it can. Excess toner scraped off by the developing roller 110 and the restriction roller 130 is conveyed by the restriction roller 130 and scraped off by the scraping member 1.
It is removed from the surface of the regulation roller 130 by 31 and is returned to the developing unit hopper and circulated.

In the printer of this embodiment, the rotation direction of the developer supply roller 120 is opposite to that of the developing roller 110 as described above. Here, the conventional printer will be described. Conventionally, there has been a CW (clockwise) direction in which the rotation direction of the developer supply roller 120 is opposite to that of the present embodiment. However, the arrangement and rotation direction of the developing roller 110, the regulation roller 130, etc. are the same as in this embodiment. When the rotation direction of the developer supply roller 120 is conventional, the flow of toner in the Bk developing device 31K is delayed and the regulation roller 130
It sometimes stayed at the top. This is the developer supply roller 120 and the developer transport members 141, 142, 14
By the rotation of 3, the toner is pushed into the area A between the regulation roller and the fixed plate 221. Originally, the toner should not stay in the area A and flow from the developing roller 110 side to the hopper 101 side and be supplied again to the developer supply roller 120, but this may not happen. The developing roller 110 is carried on the surface of the developer supplying roller 120.
There is toner that is scraped off at the contact portion with and carried on the surface of the developing roller 110, and toner that is scraped off and drops. However, this scraping cannot affect the toner in the area A to the extent that it causes a flow toward the hopper 101 side, and the toner remains in the area A. In addition to this, since the pressure of the toner conveyance by the developer conveyance member 141 is applied, the toner in the area A is further packed toward the vicinity of the regulation nip. When such toner retention occurs, the toner agglomerates generated at the entrance of the regulation nip become immobile, and the frequency of white streak generation due to the agglomerates also increases.

In place of such a conventional structure, the developer supply roller 120 is rotated in the CC direction opposite to that of the developing roller 110.
In the W (counterclockwise) direction, the toner flow is as follows. The toner sent from the developer carrying member 141 is carried from the right peripheral surface of the developer supply roller 120 in FIG. 1 along the rotation direction thereof, and the toner flow is constantly formed from the top to the bottom of the drawing. . Toner pre-charged by rubbing against the developer supply roller 120 adheres to the surface of the developing roller 110. The remaining toner rides on this flow and is sent to the vicinity of the facing portion (regulating nip) between the developing roller 110 and the regulating roller 130 without adhering to the developing roller 110.
It is presumed that the flowing toner acts on the toner remaining in the vicinity of the regulation nip to prevent the excess toner from staying in this portion, and helps to move the toner in the area A into the hopper 101. It Further, when the blade of the paddle of the developer conveying member 141 lifts the toner and passes through the position facing the developer supply roller 120 to reach the upper side, the area A and the lower portion of the blade of the developer conveying member 141 are negative compared with the surroundings. There is a space that becomes pressure. This also has a function of making it easier for the staying toner in the area A including the vicinity of the restriction nip to return to the hopper 101. By adopting the rotation direction of the developer supply roller 120 as in this embodiment,
The flow of toner from the vicinity of the regulation nip toward the hopper 101 can be assisted. As a result, even if the toner agglomerates enter the vicinity of the restriction nip, the toner agglomerates can flow out to the hopper side, and the occurrence of white lines can be prevented. Further, since the toner does not stay in the area A or the vicinity of the regulation nip, the toner deterioration is not promoted, the chargeability can be stabilized, and the image quality over time can be maintained.

In the present embodiment, the layout of each member is as described above, so that the transfer paper conveyance path has a substantially shortest distance. Specifically, it is conveyed vertically from bottom to top along the left edge of the apparatus from the storage position at the bottom of the apparatus to the sheet discharge section after passing through the transfer section and the fixing section. By shortening the transport path in this manner, there is an advantage that the entire apparatus can be downsized as compared with the case where the transport path is long. The transfer path for the transfer paper can be minimized because the arrangement of the regulating rollers 130 for the color developing devices 31K, C, M, and Y and the rotation direction of the developing roller 110 are configured as described above.

Incidentally, the developer supply roller 120 of the present embodiment.
Is a metal cored bar (a steel rod is plated or stainless) and a foamed material such as polyurethane, silicon, EPDM, or polycarbonate. At least one or more of the cell size of the foam material, the surface hardness of the developer supply roller 120, the amount of bite into the developing roller 110, the linear velocity ratio, and the like can be adjusted. By this adjustment, it was confirmed that it is possible to avoid the occurrence of white streaks over time while maintaining the stability of toner charging and the toner supply property. In the following embodiments, when the configuration of the developer supply roller 120 is limited, the adjustment is to be performed as needed.

By the way, when the developing roller 110 and the regulating roller 130 are brought into contact with each other and their surfaces are moved relative to each other as in the printer of this embodiment, a stick
Easy to slip. Here, stick-slip refers to a non-smooth movement in which stopping and sliding are repeated. This is also the case where the contact surfaces of the developing roller 110 and the regulating roller 130 do not slip smoothly on each other, and relative movement accompanied by vibration occurs. The stick-slip causes vibration, which may cause unevenness in the image density of the formed image. Therefore, the present invention has a configuration capable of preventing stick slip. The features of the present invention will be described in Examples 1 to 3 below.

[Embodiment 1] In Embodiment 1, the regulation roller 130 is made of a rubber roller in order to reduce the surface hardness of the regulation roller 130 to some extent. For example, a roller is formed of a rubber material around a nickel-plated steel shaft or a SUS shaft.

Now, the results of examining the relationship between the Asker C hardness of the regulation roller 130 and the quality of the toner layer formed on the surface of the developing roller 110 will be described with reference to Table 1. In Table 1, the quality of the toner layer is "OK" when the toner layer formed on the surface of the developing roller 110 is uniform and a good image can be formed, and "NG" in other cases.

[Table 1] The rubber materials used here are NBR, hydrin rubber,
And silicone rubber. Further, as a means for bringing the regulating roller 130 into contact with the developing roller 110, the metal shafts at both ends of the regulating roller 130 are pressed by the springs toward the developing roller 110. However, the pressure may cause the metal of the regulation roller 130 to bend. In particular, when the diameter of the metal shaft is reduced to reduce the weight, the bending becomes large. In such a case, by making the outer shape of the rubber roller thick at the central portion, the regulation roller 130 and the developing roller 1
The pressure distribution with 10 can be made constant. Further, by using the rubber roller as the regulation roller 130, the regulation roller 1
The weight of the unit 30 can be reduced as compared with the case where the unit 30 is made of a heavy material such as metal, and as a result, the entire unit weight can be reduced.

As shown in Table 1, when the Asker C hardness of the regulation roller 130 was 25 degrees or less, the image density and resolution were lowered due to insufficient toner charge amount, and scumming occurred. When the Asker C hardness was around 30 degrees, stick-slip occurred due to the deformation of the regulation roller 130 at the regulation nip, which is the contact portion between the developing roller 110 and the regulation roller 130. The stick-slip causes vibration, and the contact pressure in the regulation nip is partially insufficient, so that the toner is partially insufficiently charged. Then, when developing the latent image on the photoconductor, unevenness occurs in the image. When the Asker C hardness was 35 degrees or more and 60 degrees or less, stick-slip did not occur, and a good toner layer could be formed on the developing roller 110. When the Asker C hardness was 63 degrees or more, stick-slip did not occur, but since the amount of deformation of the regulation roller 130 was small, a pressure deviation that caused uneven pressure distribution in the regulation nip occurred. Therefore, the toner charge amount becomes unstable, which is not preferable. The upper limit of the Asker C hardness on the surface of the regulation roller 130 is 60 degrees or less in order to avoid the toner charge amount from becoming unstable.

In the first embodiment, the regulation roller 130 has the surface Asker C hardness of 35 degrees or more and 6 or less.
The range is set to 0 degrees or less. Regulation roller 130
By setting the Asker C hardness of the surface to 35 degrees or more, the occurrence of stick / slip can be prevented. Here, if the Asker C hardness of the surface of the regulation roller 130 is 35 degrees or more, regardless of the hardness, surface roughness, material, etc. of the surface of the developing roller 110 facing the stick roller,
The slip can be prevented to the extent that development is not hindered.

In the first embodiment, the regulation roller 1
Only the Asker C hardness of the surface 30 is limited, and any ordinary developing roller 110 can be used. It is possible to prevent stick-slip by setting the surface hardness of both the developing roller 110 and the regulation roller 130 instead of the configuration of the first embodiment. When the hardness of the surface of the developing roller 110 is also low, when the developing roller 110 and the regulating roller 130 move at the contact portion with a linear velocity difference, the surface of the developing roller 110 is deformed so as to be laterally displaced by receiving a tangential elastic force. Wake up. When both the regulation roller 130 and the developing roller 110 are deformed by receiving the elastic force, the force for restoring the deformation is the surface of the developing roller 110 and the regulation roller 1.
It may work on 30 surfaces simultaneously. In this case, vibration at the regulation nip portion becomes large, and unevenness of the toner layer is more likely to occur. Therefore, if not only the regulation roller 130 but also the Asker C hardness of the surface of the developing roller 110 is set to be somewhat high, vibration due to stick / slip can be more reliably prevented. Therefore, the developing roller 11
It is conceivable that 0 is made of metal or various other hard materials. In addition, by appropriately setting the relationship between the surface hardness of the developing roller 110 and the surface hardness of the developing roller 110 so that the deformation amount of the developing roller 110 is smaller than the deformation of the regulating roller 130.
Vibration due to stick-slip can be prevented more reliably.

Example 2 Next, Example 2 will be described as another example using the printer of this embodiment. In the second embodiment, the developing roller 110 is composed of a metal roller, and the surface of the developing roller 110 is coated with an oppositely charged substance that is more easily charged to a polarity opposite to the polarity of the toner than that of a metal. For example, when the charge polarity of the toner is negative, a material that is likely to be positively charged is coated. Examples of this include polyamide resin and melamine resin that is more resistant to abrasion. Further, the regulation roller 130 has the same configuration as that of the first embodiment.

When the surface of the developing roller 110 is coated with these reversely charged substances, the charge amount of the toner layer of the developing roller 110 depends on the setting condition, as compared with the case where only the metal is used.
Increased by 0% to 50%. As a result, the mixing ratio of the oppositely charged toner was reduced, the occurrence of background stain on the formed image could be reduced, and the resolution and sharpness could be improved.

Here, by coating the surface of the developing roller 110 with an oppositely-charged substance for the toner, it becomes easy to raise the amount of charge of the toner to a desired level, and therefore the developing roller 110
It is possible to slightly lower the contact pressure between the control roller 130 and the regulating roller 130. By lowering the contact pressure, the rate of increase in the amount of charge on the toner layer will be somewhat lower, but stick-slip at the restriction nip will be less likely to occur. Further, the vibration due to the stick / slip can be prevented more reliably than in the first embodiment. Therefore, there is an effect that vibration due to stick-slip can be prevented without reducing the charge amount of the toner.

The metal used for the developing roller 110 is
Aluminum, which is lightweight and advantageous, can be used, and if the life is not sufficient, the surface hardness can be increased by alumite treatment or plating treatment to improve durability. Alternatively, stainless steel can be used. Further, if the developing roller 110, which is a metal roller having a large outer diameter, is made hollow, it is effective to reduce the weight of the entire developing unit.
By coating the surface of the developing roller 110 with the oppositely charged substance as described above, in addition to the metal developing roller,
The charge amount of the toner can be easily increased to a desired level as compared with the following conventional developing roller. For example, as the developing roller that has been conventionally used, there is a rubber roller having a medium resistance, a developing roller made of urethane, silicon or the like.

Example 3 Next, Example 3 will be described as another example using the printer of this embodiment. In the third embodiment, the surface of the regulation roller 130 used in the first and second embodiments is coated with a fluororesin. The fluororesin has a function of lowering the surface energy of the regulation roller 130, and is effective as a so-called surface energy lowering substance.

The use of such a regulation roller 130 has the following effects. Since the smoothness of the surface of the regulation roller 130 is improved, stick-slip is less likely to occur between the regulation roller 130 and the developing roller 110. Therefore, vibration is less likely to occur, and both rollers 110, 13
Zero running is stable. The surface energy of the regulation roller 130 is reduced, and it is possible to prevent toner, additives, and foreign matter from adhering to each other. Further, the cleaning with the scraping member 131 can be favorably performed. The surface of the regulation roller 130 becomes smoother, the aggregates are not retained in the regulation nip, and are quickly detached so that white lines are less likely to appear. Developing roller 110 and regulating roller 1
It is possible to reduce the generation of frictional heat with 30 and prevent deterioration of the toner, the surfaces of both rollers, and the like due to temperature rise. Further, it is possible to suppress the excessive increase of the developing unit torque due to the sliding of the developing roller 110 and the regulation roller 130. Further, since the slippage with respect to the developing roller 110 is improved, the restriction on the material of the surface of the developing roller 110 can be removed. That is, it becomes easy to use a medium resistance layer having a certain thickness such as resin or rubber on the surface.
It is possible to avoid raising the electrostatic capacitance inversely proportional to the thickness of the medium resistance layer. Therefore, the electric resistance of the developing roller 110 can be set to, for example, 10 ⁶ to 10 ¹⁰ [Ω] to improve the halftone reproducibility. In addition, the developer supply roller 1
From 20, it is possible to improve the toner supply property by the electric field effect.

However, if the fluorine content of the fluororesin to be coated is too high, the toner holding power is lost and the triboelectric chargeability of the toner is lowered. Moreover, at the sites where many fluorine atoms are present, the fluorine atoms are strongly charged negatively, so that the toner is likely to be positively charged. Therefore, in the case where the above-mentioned predetermined polarity is negatively charged toner, it has an adverse effect on the charging of the toner to the predetermined polarity. Here, the negatively charged toner is relatively often used. Therefore, when the negatively charged toner is used, the regulation roller 1 has a resin structure including a site in which the toner is easily negatively charged.
Coat 30. As a result, it is possible to achieve the effect of the low surface energy of the fluorine-containing resin described above while stabilizing the charging of the toner.

The surface of the developing roller 110 may be coated with a surface energy reducing substance. In this case, even if only the developing roller 110 is coated with the surface energy lowering substance and the regulation roller 130 has a normal configuration, stick-slip can be prevented to some extent. Further, both the developing roller 110 and the regulation roller 130 may be coated with the surface energy reducing substance.

In the first embodiment, the regulation roller 13 is used.
0 is in the range where the Asker C hardness of the surface is 35 degrees or more and 60 degrees or less. By setting the Asker C hardness of the surface of the regulation roller 130 to 35 degrees or more, it is possible to prevent the occurrence of stick-slip and obtain a uniform image without density unevenness. This is because vibration due to stick-slip does not occur, so contact unevenness between the developing roller 110 and the regulating roller 130 in the regulating nip can be prevented, and a uniform toner layer can be formed on the developing roller 110. Further, by setting the Asker C hardness to 60 degrees or less, it is possible to prevent pressure deviation in the regulation nip and prevent the toner charge amount from becoming unstable. A member other than the regulation roller 130 is also in contact with the developing roller 110, and it is not easy to change the elasticity of the surface of the developing roller. By changing the hardness of the regulation roller surface as in Example 1, the stick
If slippage can be prevented, the hardness of the developing roller does not need to be changed, which is preferable. Further, in the second embodiment, the surface of the developing roller 110 is coated with a substance oppositely charged to the toner. As a result, the developing roller 110 and the regulation roller 1
When the developer is frictionally charged by contact with 30 and relative movement, the developer is easily charged to a desired charge polarity. Therefore, the developing roller 110 and the regulating roller 130
It is possible to slightly lower the contact pressure with the contact point, and when a structure for lowering the contact pressure is adopted, it is possible to more effectively prevent the occurrence of stick-slip. Therefore, a uniform image without density unevenness can be obtained. Further, in the third embodiment, at least one surface of the regulation roller 130 and the developing roller 110 is coated with fluororesin. As a result, it is possible to more effectively prevent the occurrence of stick-slip and obtain a uniform image without density unevenness. Because the regulation roller 130
This is because the smoothness of the surface is improved, and the traveling of both rollers is stabilized in the regulation nip between the developing roller 110 and the regulation roller 130.

Although the roller-shaped regulating roller is used as the developer regulating member in the above embodiment, the developer regulating member to which the present invention can be applied is not limited to the regulating roller. Any restricting member that comes into surface contact with the surface of the developing roller and relatively moves the surface facing the surface of the developing roller with respect to the developing roller can be applied. For example, a belt-shaped regulation belt,
A restricting member or the like, which is oscillated and supported in a fan-shaped cross section in the axial direction, can be considered. Further, in the above-described embodiment, the rotation direction of the regulation roller is such that the surface of the facing portion moves in the opposite direction to the developing roller. The invention is not limited to this, and the toner may be moved in the forward direction with respect to the developing roller so that the toner and the foreign matter pass through the regulation nip and are discharged. Even in this case, it is possible to suppress the occurrence of white stripes in the image. Furthermore, in the above-described embodiment, the present invention is applied to the color image forming apparatus that superimposes images of a plurality of colors, but the printer to which the present invention can be applied is not limited to this. If the printer uses a roller as a regulation member that regulates at least the toner layer on the developer carrying member,
Applicable.

[0051]

According to the developing devices of claims 1, 2, 3, 4, and 5, the following effects can be obtained. That is, by setting the surface hardness of at least one of the developer carrying member and the regulating surface of the regulating member, at least one surface of the two does not deform excessively so as to cause stick-slip. Therefore, even if a regulating member that makes surface contact with the surface of the developer carrier while moving relative to the surface of the developer carrier is used to prevent white lines due to toner clogging, the occurrence of stick-slip between the developer carrier and the regulating member is prevented. It has an excellent effect that it can be prevented. Further, according to the image forming apparatus of the sixth aspect, the developing device that does not cause stick-slip between the developer carrying member and the regulating member is used. Therefore, there is an excellent effect that it is possible to prevent the occurrence of image density unevenness due to stick / slip.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a Bk developing device according to the present invention.

FIG. 2 is an explanatory diagram of a main part of the image forming apparatus according to the embodiment.

FIG. 3 is a schematic configuration diagram showing an example of a developing device adopting a blade system as a conventional technique.

FIG. 4 is a schematic configuration diagram showing an example of a developing device adopting a roller system as a conventional technique.

[Explanation of symbols]

1 color printer 2 Developer support 3 Developer supply member 4 regulation blade 10 Photoconductor unit 11 photoconductor belt 30 development unit 31K Bk developing device 32K developer storage case 102 electromagnetic solenoid 110 developing roller 120 developer supply roller 130 regulation roller 141, 142, 143 developer transport member

Claims (6)

[Claims] 1. A developer carrying member carrying a developer on its surface,
A developer regulation member having a regulation surface that is in contact with the surface of the developer carrier and regulates the amount of the developer on the developer carrier,
In a developing device for developing a latent image with the developer on the developer carrier whose amount of developer is regulated by the developer regulating member, the regulation surface of the developer regulating member is held by the developer supporting member during image forming operation. The surface hardness of at least one of the developer carrying member and the regulating surface of the developer regulating member is configured to be movable relative to the body so that stick and slip do not occur due to contact and relative movement between the two. A developing device characterized by being set to hardness. 2. The developing device according to claim 1, wherein the developer regulating member comprises a roller-like regulating roller, and the surface of the regulating roller has a hardness of 35 as Asker C hardness.
A developing device characterized in that the temperature is not less than 60 degrees and not more than 60 degrees. 3. The developing device according to claim 1 or 2, wherein the surface of the developer carrying member is composed of at least a reversely charged substance which is easily charged to a polarity opposite to the predetermined polarity of the developer as compared with metal. A developing device characterized by the above. 4. The developing device according to claim 1, 2 or 3, wherein the surface energy of at least one surface of the developer carrier and the restriction surface of the developer restricting member is decreased to reduce the surface energy. A developing device comprising a material. 5. The developing device according to claim 4, wherein the surface energy lowering substance that constitutes the regulation surface is:
A developing device using a fluorine-containing resin. 6. An image forming apparatus having a latent image carrier for carrying a latent image on its surface and a developing device for developing the latent image, wherein the developing device is any one of claims 1, 2, 3, 4, or An image forming apparatus using the developing device of No. 5.