JPH11212360A - Non-magnetic one-component developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent needless toner from adhering to a photoreceptor drum and to execute development with good toner consumption efficiency by recovering the toner adhering to a developing roller after finishing the development. SOLUTION: After finishing a developing and printing stage, the toner on the developing roller is recovered. Namely, after finishing the development and printing, potential applied on a reset roller and a doctor blade is set to 0 V again, and the developing roller is rotated at least once, then applying developing bias is stopped and a developing motor and a reset motor are stopped. During T3 till the developing roller is stopped after it is rotated at least once, reverse bias which is reverse to the ordinary developing bias is applied on the reset roller and the doctor blade again, and the toner adhering to the surface of the developing roller is removed. Therefore, the entire outer periphery of the developing roller is cleaned by rotating the developing roller once or more times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developing method, and more particularly to a non-magnetic one-component developing method, which is characterized by a structure for eliminating wasteful toner consumption due to adhesion to an uncharged portion of a photosensitive drum at the start of development. And a non-magnetic one-component developing method.

[0002]

2. Description of the Related Art In recent years, with the generalization of computers and word processors, there has been a demand for electrophotographic devices as peripheral devices to operate in a wider environment.
There is a demand for miniaturization, low cost, and high resolution of the apparatus, and a one-component developing method using a non-magnetic developer having advantageous characteristics in response to such a demand has attracted attention.

In such a non-magnetic one-component development, generally, a developer, that is, a developer carrying member for transporting toner,
That is, the developing roller is formed of an elastic body, and this is brought into contact with the electrostatic latent image carrier, that is, the surface of the photosensitive roller at the developing section,
The adhesion of toner to the electrostatic latent image and the prevention of toner adhesion to the background portion of the latent image are performed by electrostatic force.

Here, a conventional non-magnetic one-component developing method will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a cross-sectional view showing an example of a schematic configuration of a process unit using a conventional non-magnetic one-component developing method, in which a photosensitive drum 11 serving as an electrostatic latent image carrier, a non-magnetic one-component developing device 12,
It comprises a brush charger 13, an exposure device shown as a laser beam 14, a roller transfer device 15, a cleaning blade 16, and a toner cartridge 17.

The non-magnetic one-component developing device 12 includes a developing roller 19 which is a developer carrier, a reset roller 20 for supplying toner to the developing roller 19, and charges the supplied toner. Agitator 2 for agitating toner discharged from toner cartridge 17 by doctor blade 21 and outer 22 which are developer layer thickness regulating members for regulating the thickness of the toner layer to be adhered.
3, and a paddle 24 that transports the agitated toner to the reset roller 20.

The developing roller 19, the reset roller 20, and the doctor blade 21 are all conductive and have predetermined biases V _b , V _r , and so as to stably supply toner. V _bl is applied, and a bias is applied to the developing roller 19 and the reset roller 20 via metal shafts 25 and 26 which are rotating shafts.

The developing roller 19 is formed by surrounding a metal shaft 25 serving as a rotating shaft with a conductive elastic member made of urethane rubber to which an alkali metal salt is added as a conductive agent. 11 is arranged to be in contact with the developing unit. In this case, it is desirable that the resistance of the urethane rubber having conductivity given to the developing roller 19 be in the range of 10 ⁵ to 10 ⁸ Ω · cm.

The reset roller 20 has a pore density,
That is, the number of cells is 20 to 80 cells / inch ² (3.1 to 1).
2.4 / cm ² ) soft porous conductive elastic member 2
8, for example, a urethane foam sponge having a resistance of about 10 ⁵ to 10 ⁷ Ω · cm is wound around a metal shaft 26 serving as a rotation axis, and is in contact with the developing roller 19 and in the same direction as the developing roller 19. To rotate.

FIG. 4 is an explanatory view of a developing method of a conventional electrophotographic apparatus and its problems. As shown in FIG.
After being uniformly charged by the brush charger 13, an electrostatic latent image is formed on the surface of the photosensitive drum 11 by the irradiation of the laser beam 14 corresponding to the image information, and the electrostatic latent image is formed with the rotation of the photosensitive drum 11. The image is conveyed to a developing unit, and is conveyed to a position of a roller transfer unit 15 for transferring a toner image formed by attaching the toner 29 to the electrostatic latent image onto a sheet 30. The fixed visible image is fixed by a fixing device (not shown), and the sheet 30 on which the visible image is fixed is discharged to a stacker (not shown). The surface of the photosensitive drum 11 after the transfer is completed
The toner that has been cleaned and removed by the cleaning blade 16 is stored in a waste toner box 18 and then discarded, and the surface of the photosensitive drum 11 is neutralized by a neutralization unit (not shown) to return to an initial state.

However, when the rotation of the photosensitive drum 11 is started, the surface potential of the photosensitive drum 11 is 0 V. Therefore, the contact point between the photosensitive drum 11 and the brush charger 13 and the contact point between the photosensitive drum 11 and the developing roller 19 are different. Part L between
The surface potential of _{No. 1} remains at 0 V, which is the same state as when light is irradiated after charging.

On the other hand, the toner 29 on the surface of the developing roller 19
Remains toner 29 and the contact point of the doctor blade 21, the non-charged so not receiving a frictional charging action of the doctor blade 21 in the portion L ₂ between the photosensitive drum 11 and the contact point of the developing roller, surface potential on the photosensitive drum 11 is the same state as when irradiated with light becomes the toner 29 adheres to the portion L ₁ of 0V after charging, toner 29 adhering is discarded is removed by the cleaning blade 16 Therefore, the toner at the start of the development is wasted, the consumption of the toner is increased, and the cost is increased. And such a problem,
This is particularly problematic in a so-called cleanerless process that does not use a cleaning blade, which has recently attracted attention.

To prevent such undesired toner adhesion, it has been proposed to change the timing of applying the developing bias with respect to the pre-charging bias. This will be described with reference to FIG. . FIG. 5 is a timing chart showing a proposed driving method of the electrophotographic apparatus. As shown in FIG. 5, when a print start signal is input, an OPC motor (photosensitive drum motor), a developing motor, , A voltage is simultaneously applied to the reset motor, and the photosensitive drum 11, the developing roller 19, and
The reset roller 20 starts rotating at the same time, and the pre-charging bias (−650 V) simultaneously with the rotation of the photosensitive drum 11.
Is applied, and the surface potential of the photosensitive drum 11 is uniformly charged to −650 V by the brush charger 13.

The charged portion of the photosensitive drum 11 first contacts the photosensitive drum 1 and the developing drum 19, that is,
At the time of reaching the developing section (T ₁ ), the developing bias (V _b = −
300V), an electrostatic latent image is formed by the laser beam 14 based on the print signal, the toner 29 adheres to the electrostatic latent image in the developing section, and the toner image is formed on the paper 30 in the roller transfer unit 15. Transcribe. Note that the reset bias (V _r = −400 V) and the blade bias (V _bl
= −400 V) is applied at the same time as the pre-charging bias, and a bias whose potential is larger than the developing bias _Vb in absolute value of the potential is applied so that the toner 29 is supplied efficiently.

[0014] Thus, the timing of applying the developing bias V _b, since uncharged region L ₁ is set to a time when finished passing through the developing unit in FIG. 4, the developing roller 19
To prevent the uncharged toner 29 adhering to the surface of the photosensitive drum 11 from adhering to the uncharged photosensitive drum 11 having a potential of 0 V.

As another solution, the photosensitive drum and the developing roller are separated from each other by mechanical means so as to be in a non-contact state before the start of the developing operation. To prevent the photosensitive drum and the developing roller from being deformed due to long-term contact, and to eliminate wasteful consumption of toner (see JP-A-4-43378, if necessary).
See JP-A-7-295382).

[0016]

However, in the case of the conventional method of adjusting the timing of applying the developing bias _Vb , an improvement can be seen as compared with the case where the timing is not adjusted, but the toner remains on the developing roller. Therefore, in the contact type developing device in which the photosensitive drum and the developing roller are in contact with each other, even if the developing bias _{Vb is set} to 0 V, there is a problem that some toner cannot be prevented from adhering to the photosensitive drum. is there.

In the case of a method in which the photosensitive drum and the developing roller are kept in a non-contact state mechanically before the start of the developing operation,
Therefore, a mechanical structure and a driving means for the same are required,
There is a problem that the device becomes larger, more complicated, and the operation becomes more complicated.

Accordingly, it is an object of the present invention to control the timing of applying each bias so as to collect the toner on the developing roller and prevent unnecessary toner from adhering.

[0019]

FIG. 1 is a timing chart showing the basic structure of the present invention. Referring to FIG. 1, means for solving the problems in the present invention will be described. Note that T ₁ and T ₄ are the time required for the charged portion of the electrostatic latent image carrier to come into contact with the developer carrier. See FIG. 1. (1) In the present invention, the electrostatic latent image carrier is brought into contact with the electrostatic latent image carrier through a thin layer of non-magnetic developer formed on the surface, and is applied to the electrostatic latent image carrier by application of a developing bias _VbH. A developer carrier that adheres a non-magnetic developer to an electrostatic latent image to visualize the electrostatic latent image, and a layer thickness regulation that regulates a thickness of a thin layer of a non-magnetic developer formed on the developer carrier. A member using a developer supply / recovery member that contacts the developer carrier and rotates in the same direction to supply the nonmagnetic developer to the developer carrier and recover the nonmagnetic developer. In the magnetic one-component developing method, a thin layer of the non-magnetic developer on the surface of the developer carrier is collected at least before the end of the rotation of the developer carrier.

As described above, at least before the end of the rotation of the developer carrying member, the thin layer of the non-magnetic developer on the surface of the developer carrying member is recovered, so that the developer is started at the next development start. Since the non-magnetic developer does not adhere to the surface of the carrier, the non-magnetic developer does not adhere to the uncharged portion of the electrostatic latent image carrier, and unnecessary consumption of toner can be eliminated.

(2) In the present invention according to the above (1), in order to collect a thin layer of non-magnetic developer on the surface of the developer carrying member, a developer supply / collection member and a layer thickness regulating member may be used. At least one of the developing biases V _bH
Lower recovery voltage V _rL, and applying the V _{bl L.}

As described above, the non-magnetic surface of the developer carrier
To collect a thin layer of the image agent, a developer supply / collection member
And at least one of the layer thickness regulating members
Dead bias V_blHOr reset bias V_rHOpposite to
Supply the voltage at which the potential difference occurs, that is, supply the non-magnetic developer
Voltage that generates a potential difference in the opposite direction to the potential difference
V _rL, V_blLShould be added. In addition, such recovery voltage
Is added to both the developer supply / recovery member and the layer thickness regulating member.
You can.

(3) The present invention is characterized in that, in the above (2), the recovery voltages V _rL and V _blL lower than the developing bias in absolute value are 0V.

As such recovery voltages V _rL and V _blL ,
It is desirable to set the potential to 0 V, that is, the collection efficiency is increased and the potential is easily set, that is, the ground potential.

(4) Further, according to the invention (2) or (3), when the rotation of the developer carrying member is completed,
The method is characterized in that after the recovery voltage is applied, the developer carrier is rotated at least once (T ₃ ), and then the rotation of the developer carrier is stopped.

As described above, at the end of the rotation of the developer carrier, after the recovery voltage is applied, the developer carrier becomes at least one.
It is desirable to rotate the developer carrier until it rotates (T ₃ ), and during one revolution, the thin layer of non-magnetic developer on the surface of the developer carrier is peeled off, and the entire surface of the developer carrier is removed. Be clean.

(5) In the present invention, in any one of the above (2) to (4), at least one of the developer supply / recovery member and the layer thickness regulating member at the start of rotation of the developer carrying member On the other hand, in absolute value, the developing bias V _bH
A lower recovery voltage is applied, and after the recovery voltage is applied, the recovery voltage is applied until the developer carrier to which the developing bias _VbH has been applied makes at least one rotation (T ₂ ). .

As described above, even at the start of rotation of the developer carrier, a print signal is applied by recovering the thin layer of non-magnetic developer on the surface of the developer carrier by applying a recovery voltage. This makes it possible to more reliably prevent the non-magnetic developer from adhering to the electrostatic latent image carrier during the interim period, thereby further reducing unnecessary toner consumption.

(6) Further, according to the present invention, in any one of the above (1) to (5),
The cleaning blade is not provided.

As described above, by providing the means for collecting the non-magnetic developer, the cleaning blade is not provided around the electrostatic latent image carrier, so that undesired adhesion of the non-magnetic developer in a so-called cleaning-less process is achieved. The problem goes away.

[0031]

Embodiments of the present invention will now be described with reference to FIG. In the description of the embodiment of the present invention, a description will be given using a process unit using the non-magnetic one-component developing device of FIG. FIG. 2 is a timing chart showing a driving method according to the embodiment of the present invention. As shown in FIG. 2, when a print start signal is input, an OPC motor (photosensitive drum motor) , The developing motor, and the reset motor are simultaneously applied, and the photosensitive drum 11, the developing roller 19, and the reset roller 20 start rotating at the same time, and the pre-charging bias (−650) at the same time as the photosensitive drum 11 rotates.
V) is applied, and the surface potential of the photosensitive drum 11 is uniformly charged to −650 V by the brush charger 13.

Then, the charging portion of the photosensitive drum 11 first contacts the photosensitive drum 1 and the developing drum 19, that is,
After reaching the developing section (T ₁ ), the developing bias (V _b = −
300V) is applied. In this case, the surface of the developing roller 19 has been cleaned by the recovery process after completion of the development, which will be described later, further, while in contact with the uncharged portion L ₁ of the photosensitive drum 11 does not apply a developing bias V _b Therefore, it is possible to reliably prevent the toner 29 from adhering to the photosensitive drum 11, and thereafter, the charging potential of the photosensitive drum 11 (-
650 V) prevents the toner 29 from adhering.

Next, the developing bias V is applied to the developing roller 19.
_bIs applied at least once after the developing roller 19 is applied.
After turning (T_Two), The reset roller 20 and the doctor
-Reset bias (V_r= -400
V) and blade bias (V _bl= -400V)
To supply the toner 29 to the developing roller 19.
Then, the toner 29 is uniformly frictionally charged.

During the period T ₂ , the reset roller 20 and the doctor blade 21 are grounded, that is, 0 V is applied, so that a reverse bias opposite to the normal bias is applied to the developing bias _Vb . State and the developing roller 1
Even if toner 29 is present on the surface of No. 9, it will be removed. In particular, since the reset roller 20 rotates in the same direction as the developing roller 19, that is, counterclockwise in FIG. 3, at the point of contact between the two, the traveling directions in the circumferential direction are opposite to each other. 29 will be stripped.

Thereafter, based on the print signal, the laser light 14
A toner is adhered to the electrostatic latent image in the developing unit, and the toner image is transferred to the paper 30 in the roller transfer unit 15 to which a transfer bias is applied.

[0036] Then, after the development and printing has been completed, again the 0V potential to be applied to the reset roller 20 and the doctor blade 21, after the developing roller 19 by at least one revolution, to stop application of the developing bias V _b Then, the developing motor and the reset motor are stopped.

During the time T ₃ until the developing roller 19 rotates at least once and stops, the reset roller 20 and the doctor blade 21 are again applied with a reverse bias to the developing bias _Vb . In this state, the toner 29 adhered to the surface of the developing roller 19 is removed, and the entire outer periphery of the developing roller 19 is cleaned by the rotation of the developing roller 19 by one rotation or more.

Next, the photosensitive drum 11 and the brush charger 1
After a lapse of time (T ₄ = T ₁ ) during which the region rotates between the contact point 3 and the contact portion between the photosensitive drum 1 and the developing drum 19, the application of the pre-charging bias is stopped and the OPC The motor is stopped and one development cycle is completed.

As described above, in the embodiment of the present invention, the toner 29 on the developing roller 19 is collected after the completion of the developing / printing process. Toner 2 is applied to the uncharged portion of drum 11
As a result, unnecessary toner is not consumed.

In the early stage of the developing / printing process,
Since the toner 29 on the developing roller 19 is collected, the adhesion of the toner 29 to the uncharged portion of the photosensitive drum 11 can be more reliably prevented. Note that the toner collecting step in the initial stage of the developing / printing step is not always essential.

The embodiment of the present invention has been described above. However, the present invention is not limited to the configuration described in the embodiment, and various modifications are possible. Although the same voltage is applied to both the reset roller 20 and the doctor blade 21, different voltages may be applied.

Further, members for applying the recovered voltage may be only one of the reset roller 20 and the doctor blade 21, also the voltage to be applied is also not limited to 0V, and the developing bias V _b On the other hand, any voltage may be used as long as a potential difference is generated in a direction opposite to the case where toner is supplied. Depending on the type of toner, a recovery voltage of -200 V may be applied to a developing bias _{Vb of} -300 V. . Further, a positive recovery voltage may be applied to the developing bias _{Vb of} -300 V, but the power supply system becomes complicated.

Although the present invention has been described as an ordinary electrophotographic apparatus having a cleaner blade,
The present invention is also applied to a cleanerless electrophotographic apparatus, and is more effective when applied to a cleanerless electrophotographic apparatus which does not have such a toner collecting means for the photosensitive drum.

[0044]

According to the present invention, since the toner adhering to the developing roller is recovered at least after the development is completed, unnecessary toner does not adhere to the photosensitive drum.
Therefore, it is possible to perform development with good toner consumption efficiency, so that the running cost of the electrophotographic apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a basic configuration of the present invention.

FIG. 2 is an explanatory diagram of a driving method according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a process unit of a conventional electrophotographic apparatus.

FIG. 4 is an explanatory view of a conventional developing method of an electrophotographic apparatus and its problems.

FIG. 5 is an explanatory diagram of a driving method of a conventional electrophotographic apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 photosensitive drum 12 non-magnetic one-component developing device 13 brush charger 14 laser light 15 roller transfer device 16 cleaning blade 17 toner cartridge 18 waste toner box 19 developing roller 20 reset roller 21 doctor blade 22 outer 23 agitator 24 paddle 25 metal shaft 26 Metal shaft 27 Conductive elastic member 28 Conductive elastic member 29 Toner 30 Paper

Claims (6)

[Claims] An electrostatic latent image formed on a surface of the electrostatic latent image carrier by applying a developing bias to the electrostatic latent image carrier through a thin layer of non-magnetic developer formed on a surface of the electrostatic latent image carrier; A developer carrier for adhering a developer to visualize an electrostatic latent image, a layer thickness regulating member for regulating the thickness of a thin layer of a non-magnetic developer formed on the developer carrier, and Non-magnetic one-component development using a developer supply / recovery member that contacts the developer carrier and rotates in the same direction to supply the non-magnetic developer to the developer carrier and recover the non-magnetic developer In the method, at least:
A non-magnetic one-component developing method, wherein a thin layer of a non-magnetic developer on a surface of the developer carrier is collected before the rotation of the developer carrier is completed. 2. The method according to claim 1, wherein at least one of the developer supply / recovery member and the layer thickness regulating member is provided with a developing bias in absolute value in order to recover a thin layer of non-magnetic developer on the surface of the developer carrier. The non-magnetic one-component developing method according to claim 1, wherein a lower recovery voltage is applied. 3. The non-magnetic one-component developing method according to claim 2, wherein the recovery voltage lower than the developing bias in the absolute value is 0V. 4. When the rotation of the developer carrier is completed, after the recovery voltage is applied, the developer carrier rotates at least once, and then the rotation of the developer carrier is stopped. The non-magnetic one-component developing method according to claim 2. 5. A recovery voltage lower than a developing bias in absolute value is applied to at least one of the developer supply / recovery member and the layer thickness regulating member at the start of rotation of the developer carrier. The non-magnetic device according to any one of claims 2 to 4, wherein after the recovery voltage is applied, the recovery voltage is applied until at least one rotation of the developer carrier to which the developing bias is applied. One-component development method. 6. The non-magnetic one-component developing method according to claim 1, wherein a cleaning blade is not provided around the electrostatic latent image carrier.