JP3213665B2 - Developing device and image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image with a one-component powder developer and an image forming apparatus to which the developing device is applied.

[0002]

2. Description of the Related Art In recent years, in response to the color orientation of offices,
Full color image forming apparatuses have appeared. As one of the full-color image forming apparatuses, there is a photosensitive drum four-drum tandem system. This method has four image forming functions.
A set of image forming mechanisms is built in, and a developer image of each color is formed on a photosensitive drum as four image carriers using a one-component developer (toner) of yellow, magenta, cyan, and black powders Then, the developer image is sequentially transferred to one transfer material to obtain a color image.

On the other hand, as a developing device for visualizing an electrostatic latent image, a one-component developing system for developing using a one-component powder developer is becoming mainstream. Among them, the non-magnetic one-component developing method in which a magnet is not provided in the developing roller has a feature that it is advantageous for reducing the size and weight of the developing device and reducing the price, and thus tends to be widely used.

In this non-magnetic one-component developing system, a metal, synthetic resin, or the like is used to form a thin film of a developer on a developing roller formed of an elastic body that supplies the developer to a developing portion with rotation. The developer thin layer forming member is pressed to charge the developer on the developing roller guided to the developing section and regulate the layer.Furthermore, the developing roller is brought into contact with the photosensitive drum as an image carrier. The electrostatic latent image on the photosensitive drum is developed by bringing the electrostatic latent image into close proximity.

In this method, it is necessary to increase the pressing force of the developer thin layer forming member in order to give a sufficient charge to the developer and to form a uniform thin layer. However, the developer used in the developing device applied to the above-described full-color image forming apparatus or the like has a low softening point because the three or four colors of developer are completely melted and fused at the time of fixing. A developer made of a soft thermoplastic resin is used.

[0006] Such a developer is stuck to the layer forming member and the developing roller when the pressure of the developer thin layer forming member is strong, so that a stable charged developer layer cannot be formed, which causes image deterioration. There was a problem of becoming.

To solve the problem, Japanese Patent Application Laid-Open No. 62-11 / 1987
As disclosed in Japanese Patent No. 3178, there is a proposal to use the developer thin layer forming member while abrading the member, but there is no measure for preventing sticking to the developing roller.

In particular, in the case of the above-described full-color image forming apparatus or an image forming apparatus of two or more colors such as a color printer and a color copying machine which have been actively developed in recent years, a plurality of developing devices can be simultaneously operated by one motor. In many cases, drive control is performed, so that the developing roller of the developing device may be driven even during a period of time not involved in development.

For this reason, the developer is excessively rubbed at the contact portion between the developing roller and the developer thin layer forming member and at the contact portion between the developing roller and the image carrier, so that the developer is more likely to adhere to the developing roller. There was a problem.

[0010]

As described above, in a developing device applied to a conventional color image forming apparatus or the like, not only a developer having a softening point lower than usual is used, but also a developer which is not involved in development. However, since the transport operation accompanying the driving of the developing roller is performed, the developer is subjected to excessive stress due to unnecessary contact friction with the developer, and the developer is developed on the developer holding means such as the developer thin layer forming member and the developing roller. There was a problem that the agent was fixed.

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and a first object of the present invention is to provide a developer holding means for supplying a developer to a portion to be developed with rotation, and a method for holding the developer holding means. It is an object of the present invention to provide a developing device capable of preventing a developer from sticking to a developer thin layer forming means for forming a thin layer of a developer on a surface and performing a stable developing operation.

A second object is to provide a developer holding means for supplying a developer to a portion to be developed with rotation, and to form a thin layer of the developer on the surface of the developer holding means. It is possible to prevent the developer from sticking to the developer thin layer forming means,
An object of the present invention is to provide an image forming apparatus including a developing device capable of performing a stable developing operation and capable of forming a good image.

[0013]

According to the present invention, as a first means for solving the above-mentioned problems and achieving the first object, a rotatable member is provided which is provided with a developer to be developed with the rotation. Formed of a first material and a developer holding means for supplying the developer
It is in contact with the developing operation with respect to the developer holding means
A thin developer layer forming means for forming a thin layer of the developer to be supplied to the object to be developing portion on the surface of the developer holding means, said first
Is formed by a second material different from the first material, anda developer removing means for holding the developer non-development contact during operation the developer holding means relative to said developer holding means, said developing said developer removing means the agent thin layer forming means,
The configuration is such that they are bonded to each other .

According to the present invention, as a second means for solving the above problems and achieving the first object, there is provided a developer which is rotatably provided and supplies a developer to a portion to be developed with rotation. and holding means, the surface of the developer holding means by contact with the surface of the developer holding unit, a first material to form a thin layer of the developer the formed onto the developing unit
Formed by a second material different from said first material to remove the developer of the developer holding means by contact with the first contact portion and said developer holding means formed Ri
A layer regulating member and a second contact portion which is, at the time of developing operation, the layer contacting the first contact portion of the regulating member to the developer holding unit, at the time of non-developing operation, the second Switching means for switching the contact portion to contact the developer holding means.

According to the present invention, as a third means for solving the above problems and achieving the first object, there is provided a cylindrical member which is rotatably provided and supplies a developer to a portion to be developed with rotation. a developer holding means, the surface of the developer holding means by contact with the surface of the developer holding unit, a first contact portion to form a thin layer of the developer the formed onto the developing unit and a second and a contact portion, switchable layer regulating member during the developing operation and the time of non-developing operation to remove the developer of the developer holding means by contact with the developer holding unit, The first contact portion for forming the developer thin layer is defined by a radius of curvature R, where R ≧ curvature radius of developer holding unit ×
With a shape that satisfies 0.5, the second contact portions of the developer removed, the second contact portion is tangent to the second contact portions of the developer holding means in that contact The angle θ formed with the edge is a shape satisfying θ ≦ 90 °.

According to another aspect of the present invention , a plurality of image carriers and a plurality of latent images forming latent images on each of the image carriers are provided as means for solving the above problems and achieving the second object. Forming means, and before forming by each of these latent image forming means.
A plurality of developing device for visualizing the developer a latent image on the serial image bearing member, transfer material conveying means for sequentially conveying the transfer material to the image bearing member on which a toner image is formed by the respective developing devices And a plurality of transfer units provided respectively corresponding to the respective image carriers, for respectively transferring the images formed on the respective image carriers to the transfer material transported by the transport unit. An image forming apparatus for sequentially transferring a developer image formed by the developing device to one transfer material to obtain a color image, wherein each of the developing devices is rotatably provided with rotation. a developer holding means for supplying the developing section a developer Te, the surface of the developer holding means by contact with the surface of the developer holding unit, a thin layer of the developer the formed onto the developing unit Formed by the first material forming the
<br/> said formed by a second material different from said first material to remove developer in the developer holding means by contact with the first contact portion and said developer holding means which is a layer regulating member and a second contact portion, at the time of developing operation, the first contact portion of the layer regulating member is brought into contact with the developer holding unit, when the non-developing operation, the second contact portion And a switching means for switching the contact of the developer with the developer holding means.

[0017]

According to the developing device of the first means, the developer holding means for supplying the developer to the portion to be developed with the rotation is brought into contact with the developer holding means during the non-development operation, and the developer of the developer holding means is contacted. Has a developer removing means for removing the developer, the unnecessary contact friction of the developer accompanying the transport in the direction of the developing portion during the non-developing operation is prevented, and the developer thin layer forming means and the developer holding means can be removed. Is prevented, and a stable developing operation can be performed.

Further, since the developer removing means and the developer thin layer forming means are also used, it is not necessary to provide the developer removing means independently, and the configuration can be simplified. According to the developing device of the second means, the developer is supplied to the developing portion on the surface of the developer holding device by contacting the surface of the developer holding device for supplying the developer to the developing portion with the rotation. A layer contacting member having a first contact portion that forms a thin layer of developer and a second contact portion that removes the developer of the developer holding unit by contacting the developer holding unit. Since the first contact portion of the layer regulating member is brought into contact with the developer holding means during the developing operation, and the second contact portion is brought into contact with the developer holding means during the non-developing operation, so that the switching is performed. Unnecessary contact friction of the developer accompanying the transport in the direction of the developing portion during the non-development operation is prevented, and the sticking of the developer to the developer thin layer forming means and the developer holding means is prevented. Operation becomes possible.

Further, by switching the first and second contact portions formed on one layer regulating member, it is possible to selectively form a thin layer of the developer on the developer holding means and to remove the developer. There is no need to provide a separate agent removing means, and the configuration can be simplified.

According to the developing device of the third means, in addition to the function of the second means, the first contact portion for forming a thin developer layer is further provided with a radius of curvature R, R ≧ developing. Since the shape that satisfies the radius of curvature of the developer holding means × 0.5, the effect of preventing the developer from sticking to the developer holding means and the developer thin layer forming portion can be enhanced, and a more stable developing operation can be performed. Gain.

Further, the second contact portion for removing the developer is
The angle θ formed between the tangent of the developer holding means at the point where the second contact portion abuts and the edge of the second contact portion is θ ≦ 90.
°, the developer removing action during the non-development operation can be reliably performed, and the effect of preventing the developer from being fixed can be further enhanced.

According to the image forming apparatus of the above means, each of the plurality of developing devices is brought into contact with the surface of the developer holding means for supplying the developer to the portion to be developed with rotation, whereby the developer is held. A first contact portion for forming a thin layer of the developer supplied to the developing portion on the surface of the device and a second contact portion for removing the developer from the developer holding device by contacting the developer holding device; A layer regulating member provided with a contact portion of the type described above, wherein the first contact portion of the layer regulating member is brought into contact with developer holding means during a developing operation, and the second contact portion is contacted with the developer holding means during a non-developing operation. , So that unnecessary contact friction of the developer during the non-development operation in the direction of the developing portion is prevented, and the development to the developer thin layer forming means and the developer holding means is prevented. The adhesive is prevented from sticking, Making it possible to operate, it is possible to good image formation.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. First, the overall configuration of a color image forming apparatus 1 employing a developing device 14 of the present invention will be schematically described with reference to FIG.

In the apparatus main body 2, an image is formed using a one-component developer (hereinafter, referred to as toner) of yellow (Y), magenta (M), cyan (C), and black (BK). Four sets of recording devices 10Y, 10M, 10C, 10B
K are arranged side by side.

Each of the recording devices 10Y, 10M, 10C, 10
Since the BKs are made of the same components, the yellow recording device 10Y will be described for simplicity, and the other recording devices 10M, 10C, and 10BK will be omitted.

Note that the same reference numerals are assigned to the same parts for each color, and a subscript indicating each color is added to the code to distinguish the configuration of each color. The recording device 10Y has a photosensitive drum 11Y as an image carrier, and a corona charger 12Y as a charging unit and an L as a latent image forming unit around the photosensitive drum 11Y.
An ED exposure head 13Y, a developing device 14Y as a developing unit described later, a transfer roller 15Y as a transfer unit, a cleaning device 16Y as a cleaning unit, and the like are provided.

Then, a negative charge is given by the corona charger 12Y, and the charge is uniformly charged to -400 to -800v. Next, exposure is performed by the LED exposure head 13Y in accordance with the image information sent from the image processing unit, and a yellow light image latent image is formed on the photosensitive drum 11Y.
This latent image is developed by the developing device 14Y to form a visible image (toner image) on the photosensitive drum 11Y.

On the other hand, a recording paper P as a material to be transferred is fed from a paper feed cassette 20 provided at the bottom of the apparatus main body 2 to a paper feed mechanism 24 composed of a pickup roller 21, a paper feed roller 22, a separating member 23 and the like. , Only the uppermost sheet P is taken out, and the leading edge is aligned by a pair of registration rollers 25, and is sent to the transfer belt 26 as transfer material transfer means at the same timing.

The recording paper P conveyed by the transfer material conveying belt 26 enters the transfer area of the recording device 10Y for forming a yellow image, and is 4 to 6 kV by the transfer roller 15Y.
And the toner image on the photosensitive drum 11Y is transferred to the recording paper P.

The recording paper P further advances and sequentially enters the transfer area of the recording apparatus 10M for forming a magenta image, the transfer area of the recording apparatus 10C for forming a cyan image, and the transfer area of the recording apparatus 10BK for forming a black image. The toner images are transferred under the action of the transfer rollers 15M, 15C, and 15BK in the same manner as in the case of the above-described recording apparatus 10Y for forming a yellow image.

The recording paper P on which the four color toner images have been transferred is fixed by the fixing device 27 and discharged onto the discharge tray 29 via the discharge roller pair 28. As described above, in the color image forming apparatus 1, in order to perform the exposure, development, and transfer operations for each color,
A set of developing devices 14Y, 14M, 14C, and 14BK are selectively operated.

The four developing devices 14Y, 14M, 1
4C and 14BK, the rotation of which is controlled by using a single motor (not shown) as a drive source. The non-magnetic one-component toner T is placed in contact with the photosensitive drum 11 with rotation. Developing rollers 32Y, 32M, 32C, 32BK as developer holding means for transporting to developing section 30
Are turned on and off at the same time.

On the other hand, the developing devices 14Y, 14M, 14C,
14BK switches the contact position of the layer regulating members 34Y, 34M, 34C, and 34BK arranged inside, as described later, so that a thin layer of the toner T supplied to the developing unit 30 at the time of the developing operation is developed. 32Y, 32M, 3
The toner T is removed from the developing rollers 32Y, 32M, 32C, and 32BK during non-developing operation to make development impossible.

That is, during the developing operation of the developing device 14Y, the toner T on the developing rollers 30M, 30C, and 30BK of the other developing devices 14M, 14C, and 14BK is scraped to be in a non-developing state. Before the developing operation is completed, the layer regulating member 34M of the developing device 14M switches to a portion where a thin toner layer is formed, and the developing operation is performed in accordance with the timing at which the recording paper P enters the transfer area. .

On the other hand, the developing device 14Y that has completed the developing operation
Is switched to a portion where the toner T is scraped off, and collects the toner T from above the developing roller 32Y. The developing devices 14C and 14BK sequentially perform the same operation.

Next, the developing devices 14Y, 14M, 14
The developing device 14 constituting C, 14BK will be described with reference to FIG. In the figure, reference numeral 40 denotes a developing device main body which serves as a developer storing portion (hereinafter referred to as a toner storing portion) 42 for storing the toner T which is a powder one-component developer. A toner hopper 44 as a developer accommodating means is provided continuously.

In the developing device main body 40, a part of the toner storage portion 42 is interposed, and the toner T
To the photosensitive drum 11 (11Y, 11M, 11C, 11B
K) A developing roller 32 made of an elastic body as a rotatable developer holding unit to be supplied to the developing unit 30 opposed to K)
Are provided in a state of contact (or proximity).

The developing rollers 32Y, 32M, 32C,
The developing roller 32 of the 32BK includes a line L ₁ connecting the centers of rotation of the developing roller 32 and the photosensitive drum 11, a vertical line passing through the center of rotation of the photosensitive drum 11 L
₂ is arranged at a position where an angle Θ ₁ formed by ₂ is 30 °.

Further, in the developing device main body 40, the toner T in the toner storage section 32 is supplied to the developing roller 36 with the rotation while being in contact with the rear side of the developing roller 32, and is used in the developing section 30. A toner supply roller (intermediate roller) 46 is provided as developer supply means for collecting the toner T remaining on the developing roller 36 returned to the toner storage section 42 without returning.

Further, the angle に 対 し て formed with respect to the line L ₁ connecting the rotation center of the developing roller 32 and the rotation center of the photosensitive drum 11 downstream of the toner supply roller 46 in the toner transfer direction, ie, the rotation center of the photosensitive drum 11. ₂ is a layer regulating member 34 in a state having a center of rotation on the vertical line L ₃ becomes 150 °
Layer regulating member 3 constituting Y, 34M, 34C, 34BK
4 are provided.

Incidentally, the LED exposure head 13Y,
13M, 13C, and 13BK, the LED exposure head 13 has a vertical line L ₂ passing through the rotation center of the photosensitive drum 11.
Above and directly above the photosensitive drum 11, the transfer roller 15
Transfer Roller 1 Constituting Y, 15M, 15C, 15BK
Reference numeral 5 is disposed on a vertical line L ₂ passing through the rotation center of the photosensitive drum 11 and directly below the photosensitive drum 11. Further, the cleaning devices 16Y, 16M, 16C, and 1 are located downstream of the position where the transfer roller 15 is provided.
6BK, a cleaning device 16 is further provided between the cleaning device 16 and the LED exposure head 13.
A corona charger 12 constituting the corona chargers 12Y, 12M, 12C, and 12BK is arranged.

The layer regulating member 34 includes a layer forming portion 48 as a first contact portion having a semicircular cross section, and a second contact portion having a rectangular cross section provided integrally on the flat surface side of the layer forming portion 48. Shafts 5 provided at both ends in the longitudinal direction, having a layer removing portion 50
2 is rotatable around the center of rotation.

The layer forming section 48, which is the first contact section, contacts the surface of the developing roller 32 so that the developing roller 32
A developer thin layer forming unit that forms a thin layer of the toner T supplied to the developing unit 30 on the surface of the developing unit 30, and the layer removing unit 50, which is a second contact unit, A developer removing unit that removes the toner T of the developing roller 32 by making contact with the developing roller 32 is configured, and the layer regulating member 34 serves both as a developer thin layer forming unit and a developer removing unit.

The layer forming section 48 for forming a thin developer layer is made of R7
mm, the layer removing portion 50 for removing the developer has an edge portion angle of 90 °.
It is made of a US member, and is bonded together with an adhesive.

The layer forming portion 48 made of a silicon rubber member has a thickness of 30 to 600 g / cm ² by a spring 54 (see FIG. 3) acting on a bearing portion for supporting the support shaft 52.
(2.94 × 10 ^{−3 to} 5.88 × 10 ⁻² N / mm 2). Incidentally, the developing roller 32 has a diameter of 18 mm.

The layer regulating member 34 is provided in the developing device main body 4.
Switching mechanism 56 as switching means provided on the rear side of
Thereby, at the time of the developing operation, the layer forming portion 48 as the first contact portion of the layer regulating member 34 is brought into contact with the developing roller 32,
During the non-development operation, the layer removing section 50, which is the second contact section.
Is brought into contact with the developing roller 32.

The switching mechanism 56 has a configuration as shown in FIG. That is, the support shaft 5 of the layer regulating member 34
A gear 58 is attached to 2, and the gear 58 is in a state of meshing with a fan-shaped gear 62 having a support shaft 60 as a rotation fulcrum.

A plunger type solenoid 64 as a driving source is connected to the sector gear 62.
The fan-shaped gear 62 is rotated in the direction of arrow A so that the layer regulating member 34 rotates 90 ° in one stroke of 4. The fan-shaped gear 62 has a solenoid 6
A spring 66 as an urging member is attached to the side opposite to the side 4, and when no voltage is applied to the solenoid 64,
By pulling with the spring 66, the layer regulating member 34
The fan-shaped gear 62 is rotated in the direction of arrow B so as to rotate in the opposite direction by 0 °.

Next, the switching operation of the layer regulating member 34 during the developing operation and the non-developing operation by the switching mechanism 56 will be described with reference to FIGS. Recording device 10Y,
The recording devices 10 constituting 10M, 10C, and 10BK are:
Process speed 100 mm / sec, photoreceptor drum diameter φ30 mm, angle 30 degrees between LED exposure head 13 and development target 30 (development nip), rotation peripheral speed ratio of development roller 32 is 1.5 times the process speed, development Roller diameter φ1
8 mm, and an angle of 150 degrees between the layer regulating member 34 and the development target portion 30 (development nip portion).

Then, a drive timing signal for the solenoid 64 of the switching mechanism 56 is sent from the control unit 70 as control means, which will be described later. The switching from the removing section 50 to the layer forming section 48 as the first contact section as shown by the solid line in FIG.

The formed thin layer of the toner T reaches the developing portion 30 (developing nip portion) in 0.16 seconds. 0.7 seconds after the solenoid drive timing, an exposure head drive circuit 72Y (72M, 72M,
72C, 72BK), and emits light to start forming a latent image. The electrostatic latent image enters the developing section 30 in 0.08 seconds due to the rotation of the photosensitive drum 11. At this time, a thin layer of the toner T has already been formed on the developing roller 32, and the charged toner moves to develop the electrostatic latent image.

At the same time as the end of the exposure, the voltage applied to the solenoid 64 is also stopped, and the layer regulating member 34 makes one rotation in the reverse direction by the force of the spring 66. As shown by the two-dot chain line, the operation is switched to the layer removing section 50 which is the second contact section.

In this manner, a necessary layer of the toner T can be formed on the developing roller 32 only during the developing operation. When the size, arrangement angle, and process speed of the photosensitive drum 11 and the developing roller 32 are changed, the drive timing of the solenoid 64 is changed to change the
The entry of the toner layer on the developing roller 32 into the (development nip) may be controlled so as to be about 0.1 second faster than the entry of the electrostatic latent image.

FIG. 4 shows a layer forming portion 48 as a first contact portion.
Indicates a developing operation state in which the developing roller 32 is in contact with the developing roller 32. Then, the amount of the toner T supplied to the developing unit 30 side by the layer forming unit 48 is regulated. At the same time, the rotation of the developing roller 32 causes toner particles to be taken into a nip portion formed at a contact portion between the layer forming portion 48 and the developing roller 32, and the toner T
Is formed, and the toner particles are triboelectrically charged due to the difference in peripheral speed between the two.

The radius R of curvature of the layer forming section 48 is equal to or larger than the outer radius of the developing roller 32 (= radius of curvature) × 0.5. The reason is obtained from the experimental data shown in FIG. FIG. 5 shows the number of running sheets when the toner T adheres to the developing roller 32 when the radius of curvature R is changed.

The radius of curvature R is equal to the outer radius of the developing roller × 0.
If it is about 5, the life of 10,000 sheets can be achieved, and if it is larger than that, the sticking of the toner T is more difficult to occur. When the toner T adheres to the developing roller 32,
Problems such as an extreme increase in toner fogging in the non-image area and toner falling off without the toner layer being held on the developing roller 32 occur.

The reason why the curvature of the layer forming portion 48 is as described above is not necessarily logically clear. However, if the curvature is smaller than the above, the nip width cannot be increased, and the pressing force is required to sufficiently frictionally charge the toner T. The pressure needs to be increased. In this case, since the applied pressing force is concentrated on the narrow nip portion, the pressing force per unit area increases, and the toner T adheres to the developing roller 32 easily.

On the other hand, if the curvature is large, the nip width can be increased because the developing roller 32 is an elastic body, and the friction T of the toner T increases, so that the pressure required for frictional charging can be reduced. Therefore, since the contact area is large, the pressing force per unit area is small, so that the toner T is hardly fixed.

The material of the layer forming portion 48 is SU
Although metals such as S, copper, phosphor bronze, aluminum, zinc plating, and nickel plating can be used, the use of a synthetic resin such as silicon rubber or urethane rubber causes abrasion depending on the use, and the toner may adhere. More desirable because there is no. Incidentally, in this example, a silicone rubber member having a curvature of R7 mm was used.

Thus, the layer forming section 48 is
During the developing operation, the non-magnetic one-component toner T in the toner storage section 42 in the developing device main body 40 is sent to the developing roller 32 by the toner supply roller 46, and then the developing roller 32 rotates. Then, as shown by an arrow C, it passes through the nip portion with the layer forming portion 48, and is sent to the developing portion 30 in a thin layer state and in a state in which charges having the same polarity as the electrostatic image charges are given.

When the developing unit 30 comes into contact with the photosensitive drum 11, it moves to the photosensitive drum 11 side,
The electrostatic latent image on the photosensitive drum 11 is visualized.

On the other hand, the remaining toner T not contributing to the development is transferred to the toner storage section 42 by the rotation of the developing roller 32.
It is returned and collected. During the developing operation, an AC bias voltage or a DC bias voltage, or a bias voltage in which DC and AC are superimposed may be applied between the developing roller 32 and the photosensitive drum 11.

FIG. 6 shows a layer removing section 50 as a second contact section.
5 shows a non-developing operation state in which the edge portion of the developing roller 32 is in contact with the developing roller 32. The thin layer of the toner T on the developing roller 32 is scraped off by the edge 50A of the layer removing section 50. The toner T scraped off from the developing roller 32 and the toner T conveyed by the rotation of the toner supply roller 46 are once guided upward along the flat surface 50B of the layer removing section 50 as indicated by an arrow D, and are stored in the toner storage section 42. Is returned to. As a result, even though the developing roller 32 is rotating,
No toner T is conveyed to the side.

As described above, since the toner T does not exist on the developing roller 32 except during the developing operation, the nip between the developing roller 32 and the photosensitive drum 11 and the nip between the developing roller 32 and the layer regulating member 34 are formed. As a result, the toner T is not subjected to excessive stress, and the toner T does not adhere to the developing roller 32.

In addition, the layer removing section 50 is formed by the method shown in FIG.
As shown in the tangent L ₄ and the angle theta ₃ of the edge portion 50A which contacts with the developing roller 32 is in the 90 ° or less. As shown in FIG. 7 (b), the angle between the tangent line L ₄ and the edge portion 50A which contacts with the developing roller 32, 90 °
When large angle theta ₄ than, easily capture the toner T in the space formed by the edge portion 500A of the surface and the layer removing portion 500 of the developing roller 32, the desired effect of scraping off the toner T from the developing roller 32 is obtained Absent. If the angle is smaller than 90 °, in principle it does not matter how small it is. However, if it is too small in practice, there will be a problem with the strength, the surface of the elastic developing roller 32 will be damaged, and However, it is desirable that the angle is about 30 ° or more.

Further, as the material, metal, synthetic resin such as urethane rubber can be used. Incidentally, in this embodiment, the angle of the edge portion 59A is 90 ° and the material is SU.
S.

Here, the structure of the developing device described as an embodiment is for explaining a non-magnetic one-component contact developing system, and the arrangement and dimensions of the components of the developing device are not limited thereto.

Further, as shown in FIG.
Operation signals are input to Y, 10M, 10C, and 10BK from a control unit 70 as control means, and a series of image forming operations are performed.

That is, the control unit 70 includes the developing device 14
Solenoid drive circuit 74 for driving solenoid 64 for switching the layer regulating members of Y, 14M, 14C, and 14BK
Y, 74M, 74C, and 74BK are connected. Further, the LED exposure heads 13Y, 13M, 13C, 13B
Exposure head drive circuits 72Y and 7 for controlling the driving of K
2M, 72C and 72BK are connected.

Each exposure head drive circuit 72Y,
The page memories 76Y, 76M, 76C, and 76BK are connected to the 72M, 72C, and 72BK, respectively.
These page memories 76Y, 76M, 76C, 76BK
, Color image information is input from an external device (not shown) such as a color image reading device or a personal computer via the interface 78.

The time required for the recording paper P taken out of the paper feed cassette 20 to be conveyed to the transfer section where the transfer roller 15Y of the yellow image recording apparatus 10Y is disposed is represented by T ₁ , and the magenta image is recorded. The time to the transfer portion is T ₂ , the time to the transfer portion of the cyan image is T ₃ , and the time to the transfer portion of the black image is T ₄ . The time t ₁ during which the photosensitive drum 11 rotates from the exposure unit to the transfer unit from T ₁ , T ₂ , T ₃ , and T _4.
Are calculated so that the entry of the toner layer on the developing roller 32 into the development nip is about 0.1 second faster than the entry of the electrostatic latent image as described above. Time difference t ₂ from the exposure timing
The time subtracted from y, Tm, Tc, Tbk is Ty ′, T
m ', Tc', and Tbk '.

Four sets of photosensitive drums 11Y, 11M, 11
C, 11BK, and four developing devices 14Y, 14M, 1
4C and 14BK are each driven by one data. The photosensitive drums 11Y, 11M,
11C, 11BK, developing devices 14Y, 14M, 14C,
A 14BK motor (not shown) starts driving, and at the same time, a neutralizing lamp (not shown) is driven to
Clean 1Y, 11M, 11C, 11BK.

After several seconds, the pickup roller 21
Is driven, and at the same time, the corona chargers 12Y, 12M, 12C, and 12BK, which are charging means, are turned on. After Ty time from there, the exposure head drive circuit 72Y of the LED exposure head 13Y for yellow is changed to Ty '.
After a lapse of time, the yellow solenoid drive circuit 74Y is turned on, and after a time T1, the transfer voltage to the yellow transfer roller 15Y is turned on.

In this way, Tm, Tc, Tbk
At the time, the exposure head drive circuits 72M and 72 for each color are used.
C, 72BK are ON, and solenoid driving circuits 74M, 74C, 74BK of each color are used at the time of Tm ', Tc', Tbk '.
There ON, transferred to T _2, T _3, T ₄ hours B - La 15M,
The transfer voltage for 15C and 15BK is turned on. T
y, Tm, Tc, Tbk, Ty ', Tm', Tc ', T
bk 'is the page memory 76Y, 76M, 76C, 76B
It turns off as soon as the data in K disappears, and T _1-
T ₄ is the timing of the ON setting paper size is time after OFF of passes through the transfer portion.

The solenoid driving circuits 74Y, 74M, 74
When C, 74BK is ON, the layer regulating members 34Y, 34M,
34C and 34BK, the layer forming portion 48 as the first contact portion is in contact with the developing rollers 32Y, 32M, 32C and 32BK (see FIG. 4), and when turned off, the layer removing portion as the second contact portion. 50 is a developing roller 32Y, 32M, 32
C, 32BK (see FIG. 6).

As described above, the photosensitive drums 11Y, 11M,
11C, 11BK, developing rollers 32Y, 32M, 32
Even if the drive motors of C and 32BK are common to the four colors, the layer of the toner T is formed on the developing rollers 32Y, 32M, 32C and 32BK only during development, so that the layer regulation members 34Y, 34M, 34C, The service life of the toner T and the components of the developing devices 14Y, 14M, 14C, and 14BK can be extended without applying extra stress due to the 34BK.

FIG. 9 shows a modification of the layer regulating member 34.
This layer regulating member 341 is a layer forming portion 4 which is a substantially fan-shaped first contact portion in which one end portion having a semicircular cross section is removed at a right angle.
80 and a layer removing portion 50 which is a second contact portion having a semicircular cross section.
1 is joined.

Then, by rotating by 90 ° about the support shaft 52, the layer forming portion 480, which is the first contact portion, is brought into contact with the developing roller 32, and the edge portion 501A of the layer removing portion 501 is brought into contact with the developing roller 32. Is switched so as to come into contact with.

The layer forming section 480 and the layer removing section 501
The material, the pressing force, and the switching mechanism are the same as those described in the above-described embodiment, and the operation and the like are the same.

FIG. 10 shows still another modification of the layer regulating member 34. The layer regulating member 342 has a layer forming portion 481 which is a first contact portion having a fan-shaped cross section, and a narrower portion. Layer removing portion 502 which is a second contact portion having a fan-shaped cross section
Are joined.

By rotating by 90 ° about the support shaft 52, the layer forming portion 481, which is the first contact portion, is brought into contact with the developing roller 32, and the edge portion 502A of the layer removing portion 502 is brought into contact with the developing roller 32. Is switched so as to come into contact with.

The layer forming section 480 and the layer removing section 501
The material, the pressing force, and the switching mechanism are the same as those described in the above-described embodiment, and the operation and the like are the same.

FIG. 11 shows a modification of the switching mechanism 56 for switching the layer regulating member 34, in which a rotary solenoid 640 is used as a drive source instead of the plunger type solenoid 64 described above. Rotary solenoid 64
Actuator 644 that rotates around the 0 support shaft 642 as a rotation center
, A layer regulating member 343 is integrally attached.

Then, by applying a voltage to the coil 646 and rotating the operating body 644 by 20 degrees, the layer forming portion 481 which is the first contact portion having a sector-shaped cross section of the layer regulating member 343 is formed.
The edge portion 50A of the layer removing portion 50 having a rectangular cross section, which is the second contact portion, is selectively brought into contact with the developing roller 32.

Here, the case where the developing device as an embodiment is applied to a tandem-type image forming device in which four sets of photosensitive drums, developing devices, and the like are arranged horizontally is described. Other than the above-mentioned colors can be applied to an image forming apparatus in which two sets of developing apparatuses are incorporated so that printing can be selectively performed one by one or two colors can be combined, and black (BK) can be used. The present invention can be applied to an image forming apparatus in which three developing devices loaded with the removed toners T of yellow (Y), magenta (M), and cyan (C) are incorporated. In addition, it goes without saying that the present invention can be variously modified and implemented without departing from the gist of the present invention.

[0086]

As described above, according to the present invention, the following effects can be obtained. According to the developing device of the first aspect, the developing device is formed of the second material and comes into contact with the developer holding unit that supplies the developer to the developing portion with the rotation when the device is not operating, and The developer removing means for holding the developer, and unnecessary contact friction of the developer accompanying the transport in the direction of the developing portion during the non-developing operation is prevented, and the developer thin layer forming means and the developer holding means Sticking of the developer is prevented, and a stable developing operation can be performed.

Further, by using the developer thin layer forming means and the developer removing means attached to each other, it is not necessary to provide the developer removing means independently, and the configuration can be simplified. According to the second aspect of the present invention, the developing unit is formed on the surface of the developer holding unit by contacting the surface of the developer holding unit that supplies the developer to the developing unit with the rotation. A layer regulating member having a first contact portion for forming a thin layer of developer and a second contact portion for removing the developer of the developer holding means by contacting the developer holding means; during the developing operation, by contacting the first contact portion of the layer regulating member to the developer holding means, at the time of non-developing operation, from the second contact portion to be switched so as to contact with the developer holding unit, a non-developing operation When the developer is transported in the direction of the developing section, unnecessary contact friction of the developer is prevented, and the developer is prevented from sticking to the developer thin layer forming means and the developer holding means, and a stable developing operation is possible. Becomes

Further, by switching the first and second contact portions formed on one developer layer regulating member, it is possible to selectively form a thin layer of the developer on the developer holding means and remove the developer. In addition, there is no need to provide the developer removing means independently, and the configuration can be simplified.

According to the third aspect of the present invention, in addition to the operation of the second means, the first contact portion for forming a thin layer of the developer is further provided with a radius of curvature R of R ≧ developer. Since the shape is such that the radius of curvature of the holding means × 0.5 is satisfied, the effect of preventing the developer from sticking to the developer holding means and the developer thin layer forming portion can be enhanced, and a more stable developing operation can be performed. It will be.

Further, the second contact portion for removing the developer is
The angle θ formed between the tangent of the developer holding means at the point where the second contact portion abuts and the edge of the second contact portion is θ ≦ 90.
°, the developer removing action during the non-development operation can be reliably performed, and the effect of preventing the developer from being fixed can be further enhanced.

According to the image forming apparatus of the present invention, each of the plurality of developing devices comes into contact with the surface of the developer holding means for supplying the developer to the developing portion with the rotation, whereby the developing is performed. The developer of the developer holding unit is removed by contacting the first holding unit that forms a thin layer of the developer supplied to the developing unit on the surface of the developer holding unit and the developer holding unit. A developer layer regulating member having a second contact portion is provided, and the first contact portion of the developer layer regulating member is brought into contact with a developer holding means during a developing operation, and the second contact is carried out during a non-developing operation. The contact portion is switched so as to contact the developer holding means, so that unnecessary contact friction of the developer accompanying the transport toward the developing portion during the non-development operation is prevented, and the developer thin layer forming means and the developing Prevents developer from sticking to developer holding means Are, making it possible to stable development operation, it is possible to good image formation.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating the overall configuration of an image forming apparatus according to the present invention.

FIG. 2 is a schematic sectional view of a recording apparatus provided with an embodiment of the developing device of the present invention.

FIG. 3 is a diagram showing a configuration of a layer regulating member switching mechanism of the developing device shown in FIG. 2;

FIG. 4 is an explanatory diagram illustrating a state during a developing operation of the developing device illustrated in FIG. 2;

5 is a correlation diagram between a radius of curvature of a layer forming portion of a layer regulating member in the developing device shown in FIG. 2 and the number of toner sticking occurrences.

FIG. 6 is an explanatory diagram showing a state of the developing device shown in FIG. 2 during a non-developing operation.

FIG. 7 is a diagram showing a state of an edge angle of a layer removing portion of a layer regulating member in the developing device shown in FIG. 2;

FIG. 8 is a control block diagram in a case where a layer regulating member is switched and used in the image forming apparatus shown in FIG. 1;

FIG. 9 is a view showing a first modification of a layer regulating member which is a main part of the present invention.

FIG. 10 is a view showing a second modification of the layer regulating member which is a main part of the present invention.

FIG. 11 is a diagram showing another embodiment of the switching mechanism of the layer regulating member, which is a main part of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Color image forming apparatus, 2 ... Device main body, recording apparatus 10
(10Y, 10M, 10C, 10BK) Recording device, 1
1 (11Y, 11M, 11C, 11BK): Photosensitive drum (image carrier), 12 (12Y, 12M, 12C, 12)
BK) Corona charger (charging means), 13 (13Y, 1
3M, 13C, 13BK LED exposure head (latent image forming means), 14 (14Y, 14M, 14C, 14BK)
Developing device (developing means), 15 (15Y, 15M, 15
C, 15BK): transfer roller (transfer means), 30: developing portion, 32 (32Y, 32M, 32C, 32BK) developing roller (developer holding means), 34, (34Y, 34M,
34C, 34BK): Layer regulating member, 40: Developing device main body, 42: Toner storage section (developer storage section), 44: Toner hopper (developer storage section), 46: Toner supply roller (developer supply section), 48 ... Layer forming part (developer thin layer forming means) as first contact part, 50... Layer removing part (developer removing means) as second contact part, 50A.
... Support shaft, 54. Spring, 56. Switching mechanism (switching means), 64. Plunger solenoid (drive source), 66.
... springs (biasing members), 341, 342, 343 ... layer regulating members, 480, 481 ... layer forming portions (developer thin layer forming means) as first contact portions, 500, 501 ... second contact portions Layer removing section (developer removing means), 500A, 50
1A: edge portion, 640: rotary solenoid (drive source), P: recording paper (transfer material), T: toner (powder one-component developer).

Continuing on the front page (72) Inventor Toshihiro Kasai 70 Yanagicho, Kochi-ku, Kawasaki-shi, Kanagawa Pref.Toshiba Yanagicho Plant Co., Ltd. (72) Inventor Yasuyuki Fukudome 70 Yanagimachi, Yuki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagimachi Plant Co., Ltd. (56) References JP-A-5-27579 (JP, A) JP-A-4-204961 (JP, A) JP-A-56-125776 (JP, A) JP-A-4-88374 (JP, A) JP-A-4-221978 (JP, A) Japanese Utility Model Application No. 64-49861 (JP, U) Japanese Utility Model Application No. Sho 61-76453 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/08 504

Claims (6)

(57) [Claims] A developer holding means which is rotatably provided and supplies a developer to a portion to be developed along with the rotation ; and is formed of a first material and comes into contact with the developer holding means during a developing operation. wherein a thin developer layer forming means for forming a thin layer of the developer the the surface of the developer holding means is supplied to the developing unit, is formed by a second material different from the first material, the developer with respect to the holding means in contact during the non-development operation anda developer removing means for holding the developer of the present <br/> image-carrying means, the thin developer layer forming means and said developer removing means Are each other
A developing device, wherein the developing device is bonded to the developing device. 2. A developer holding means which is rotatably provided and supplies a developer to a portion to be developed with rotation, and said developer holding means is brought into contact with a surface of said developer holding means by contacting said developer holding means. the surface means, the developer by making contact with the first of the first contact portion and said developer holding means formed of a material for forming a thin layer of the developer the formed onto the developing unit The first means for removing the developer in the holding means ;
A layer regulating member and a second contact portion formed by a second material different from the material, at the time of developing operation, the first contact portion of the layer regulating member
Wherein contacting the developer holding means, at the time of non-developing operation, the developing device, characterized in that said second contact portion formed by anda switching means for switching so as to contact with the developer holding unit. 3. A cylindrical developer holding means which is rotatably provided and supplies a developer to a portion to be developed with the rotation, and said developing means is brought into contact with a surface of said developer holding means. on the surface of the image-carrying means, the developer of the developer holding means by contact with the first contact portion and said developer holding means for forming a thin layer of the developer the formed onto the developing unit A second contact portion for removing a developing agent, a layer regulating member which can be switched between a developing operation and a non-developing operation, and a first contact portion for forming a thin developer layer, which has a radius of curvature R
But with a shape that satisfies the curvature radius × 0.5 of R ≧ developer holding means, said second contact portion of the developer removed, the developer at the point where the second contact portion is in contact angle formed by the tangent of the retaining means and said second contact portion of the edge θ is,
A developing device having a shape satisfying θ ≦ 90 °. 4. A plurality of image bearing members, a plurality of latent image forming means for forming a latent image on each of these image bearing member, a latent image on the image bearing member formed by respective latent image forming means A plurality of developing devices for visualizing the image with a developer; transfer material transporting means for sequentially transporting a transfer material to each image carrier on which a toner image is formed by each of the developing devices; A plurality of transfer units respectively provided corresponding to each other and transferring the images formed on the respective image carriers to the transfer material conveyed by the conveyance unit. An image forming apparatus for sequentially transferring a developer image formed by the developing device to a material to obtain a color image, wherein each of the developing devices is rotatably provided, and the developer is transferred to a development target portion with rotation. Developer holding means for supplying, and a surface of the developer holding means On the surface of the current <br/> image-carrying means by contacting said first contact portion and the development formed of a first material to form a thin layer of developer formed the developing unit by contact with the agent-holding means and the first removing the developer of the developer holding means
A layer regulating member and a second contact portion formed by a second material different from the material, at the time of developing operation, the first contact portion of the layer regulating member
Wherein contacting the developer holding means, at the time of non-developing operation, the image forming apparatus, characterized in that said second contact portion formed by anda switching means for switching so as to contact with the developer holding unit. 5. The method according to claim 1, wherein said developer thin layer forming means is
The first material is, for example, silicone rubber, and the second material used for the developer removing means is, for example, stainless steel.
3. The developing device according to claim 1, wherein the developing device is made of stainless steel . 6. The method according to claim 6, wherein said developer thin layer forming means is
The first material is, for example, silicone rubber, and the second material used for the developer removing means is, for example, stainless steel.
5. The image forming apparatus according to claim 4, wherein the image forming apparatus is made of stainless steel .