JP3098285B2 - Developing device for electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system using a laser, such as a printer, a copying machine, a facsimile, etc. (a system in which an image formed on a photoreceptor is transferred to a sheet such as paper or an envelope for recording). Thus, the present invention can be applied to an electrophotographic apparatus that performs recording on a sheet. Specifically, in such an electrophotographic apparatus, a supply roller is pressed against a developing roller to supply toner to the developing roller, and the developing roller is rotated to attach the toner to the photoconductor, and the latent image on the photoconductor surface is developed. Developing device.

[0002]

2. Description of the Related Art Conventionally, in a developing device of this type, as shown in FIG. 5, for example, a developing roller 1 and a replenishing roller 2 are rotated in a direction indicated by an arrow in FIG. While pressing with a certain bite amount δ, the toner is frictionally charged and supplied to the developing roller 1, while
The developing roller seal member 3 is pressed against the outer periphery of the end of the developing roller 1, and the roller shaft 2 a
There is a configuration in which a replenishing roller seal member 4 is pressed against the outer periphery to prevent toner leakage in the roller axial direction.

[0003]

By the way, in such a developing device, the thickness of the developing roller seal member 3 may be increased in order to prevent toner leakage and improve the toner sealing property. Further, in order to improve the triboelectrification of the toner, the outer diameter of the replenishing roller 2 may be increased to increase the biting amount δ. However, on the other hand, there is a demand for further miniaturization of the developing device. Therefore, it is desirable that the developing device be configured to achieve a good balance between the miniaturization of the developing device and the improvement of the developing function such as the toner sealing property and the frictional charging property of the toner. However, the conventional developing device described above has not been able to achieve the two objectives of reducing the size and improving the developing function in a well-balanced manner.

An object of the present invention is to achieve a good balance between miniaturization of a developing device and improvement of its developing function.

[0005]

Therefore, the invention according to claim 1 is, for example, as shown in the following illustrated embodiments.
The supply roller 45 is pressed against the developing roller 35 to supply the toner 32 thereto, while the developing roller seal member 40 is pressed against the outer periphery of the end of the developing roller 35 and the outer periphery of the roller shaft 45a of the supply roller 45 is supplied. The developing device 17 of the electrophotographic apparatus, which presses the roller seal member 46 to prevent toner leakage in the axial direction of the roller.
, The outer diameter of the supply roller 45 is B,
The outer diameter of the roller seal member 46 is C, and the seal for the developing roller is C.
T, and the supply roller 45 is
Let δ be the bite amount when pressed against the image roller 35
In this case, B ≧ 2 (t + C / 2 + δ) .

According to a second aspect of the present invention, for example, as shown in the following illustrated embodiment, the developing device 17 according to the first aspect is provided.
Wherein the supply roller 45 is formed of an elastic body.

According to a third aspect of the present invention, there is provided a developing device according to the first aspect, for example, as shown in the following embodiments.
In the above, the supply roller 45 is formed of a conductive material,
It is characterized by applying a bias voltage thereto.

[0008]

In the developing device according to the first aspect, the external device
Supply roller 4 whose diameter B is B ≧ 2 (t + C / 2 + δ)
5 is pressed against the developing roller 35 to replenish the toner 32, while the developing roller seal member 40 and the replenishing roller seal member 46 both prevent toner leakage from the roller axial direction.

In the developing device 17 of the present invention, the supply roller 45 is pressed against the developing roller 35 with a predetermined bite amount δ.

According to the third aspect of the present invention, a bias voltage is applied to the supply roller 45 during development.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows a laser printer provided with a developing device according to an embodiment of the present invention, and shows an overall schematic configuration of an internal mechanism thereof. What is indicated by reference numeral 10 in the drawing is the apparatus main body. The apparatus main body 10 removably mounts a sheet feeding tray 11 on the right side in the figure, and stores sheets S therein. Also,
The apparatus main body 10 has a drum-shaped photoreceptor 14 substantially at its center.
Is provided. Around the photoreceptor 14, a charging device 15, a light writing device 16, a developing device 17, a transfer device 18, and a cleaning device 19 are provided in this order in the rotation direction indicated by the arrow in the drawing. A fixing device 20 is provided on the left side of the cleaning device 19. As the photoreceptor 14 rotates, the surface thereof is uniformly charged by the charger 15, the optical writer 16 converts the video signal sent from the outside into an electronic signal, and performs exposure scanning using laser light to perform static scanning. An electrostatic latent image is formed, and this electrostatic latent image is visualized by a developing device 17 to be a toner image.

The sheet S in the paper feed tray 11 is fed out by a paper feed roller 21 and is fed by a registration roller 22 to the photosensitive member 1.
Send out to 4. Then, the toner image is transferred to the sheet S by the transfer device 18, and the sheet S is separated from the photoconductor 14 and is conveyed to the fixing device 20. Then, the transfer image is fixed by applying heat and pressure by the heating roller 23 and the pressure roller 24 in the fixing device 20, and then selectively sent to the paper output tray 27 or 28 by the paper output rollers 25 and 26 to be output. I do.

On the other hand, the surface of the photoreceptor 14 after image transfer is cleaned by a cleaning device 19.

The above-described developing device 17 has a configuration as shown in FIG. Reference numeral 30 in the drawing denotes a developing device main body case. On the developing device main body case 30,
A toner cartridge 33 for supplying the toner 32 into the toner chamber 31 is exchangeably mounted. In the toner chamber 31, an agitator 34 for stirring the toner 32 is provided with a shaft 34a.
Attach it so that it can be rotated clockwise in the figure. Further, in the developing device main body case 30, a developing roller 35 partially exposed from the opening 30a on the left side of the photoreceptor 14 in FIG.
Are provided rotatably about the roller shaft 35a. Further, the developing device main body case 30 is urged by a pressure spring 36 provided on the right side in the figure, and the developing roller 35 is
Press against. The developing device main body case 30 is provided with a blade support recess 30b above the developing roller 35, and urges the blade holder 38 by a spring 37 provided in the blade support recess 30b, and holds the blade holder 38 with the blade holder 38. The layer blade 39 is pressed against the outer periphery of the developing roller 35. The thin layer blade 39 is horizontally long along the length direction of the developing roller 35, and is made of a plate material such as a silicon-based resin or a fluorine-based resin.

The developing roller 35 is, as shown in FIG.
It is formed to have a predetermined outer diameter A by a conductive elastic body. The non-image areas on the outer periphery of both ends are covered with the developing roller seal member 40. The developing roller seal member 40 is formed with a predetermined thickness t in order to prevent toner leakage from the roller axis direction. And
It is provided in the developing device main body case 30 and is pressed against both ends of the developing roller 35. In the image area of the developing roller 35, a supply roller 4 having a shorter length than the developing roller 35 is provided.
5 with a predetermined bite amount δ. The replenishing roller 45 has a predetermined outer diameter B made of a conductive elastic body.
It is formed in the size of. Then, the developing roller 35 is rotatable about a roller shaft 45a provided at a predetermined distance L from the roller shaft 35a. Also, the developing device main body case 3 is provided on the outer periphery of both ends of the roller shaft 45a.
A cylindrical supply roller seal member 46 having an outer diameter C provided at 0 is pressed. Then, the configuration is such that toner leakage from the roller axis direction is prevented.

Next, as described above, the developing roller 3
The distance L between the shaft 5 and the supply roller 45, the developing roller 3
5, the outer diameter B of the supply roller 45, the outer diameter C of the supply roller seal member 46, the thickness t of the developing roller seal member 40, and the bite amount δ. Then, first, the center distance L
Can be obtained from the following formula unless the developing roller seal member 40 and the supply roller seal member 46 are taken into account. L = A / 2 + B / 2-δ...

Here, the outer diameter B of the supply roller 45 is changed to the outer diameter A of the developing roller 35, with emphasis placed on the miniaturization of the developing device.
Make it much smaller, tentatively A = 16mm, B = 13m
When the distance L between the axes is obtained by setting m and δ = 1 mm, L =
13.5 mm. However, when the inter-axis distance L is reduced in this way, the state shown in FIG. 2 results.
In other words, for example, a gap between the end of the developing roller 35 and the seal member 46 for the replenishing roller cannot be secured due to the thickness of the sealing member 40 for the developing roller and the wall of the developing device main body case where the sealing member 40 is provided. Would.
In this case, it is assumed that C = 10 mm and t = 2 mm.

Therefore, the developing roller seal member 40
Is calculated taking into account the thickness t of the roller and the outer diameter C of the supply roller sealing member 46,
Is derived from the following equation. L ≧ A / 2 + t + C / 2 ...

Therefore, a formula for obtaining the outer diameter B of the supply roller 45 by substituting the above formula into this formula is derived as shown in the following formula. B ≧ 2 (t + C / 2 + δ)...

Next, as an example, the outer diameter B of the replenishing roller 45 of this embodiment will be obtained based on an equation . here
For both t and δ, from the demand for miniaturization
Although relatively minor is desirable, in order to improve the triboelectric chargeability of the toner sealing property and the toner is preferably set relatively large. Therefore, for t, the toner
At least 2 mm is necessary in consideration of sealing properties.
2 mm or more is also desirable in the creation of
For δ, based on past experimental data,
Considering triboelectric charging, set the optimal value to 1 mm
Was. Furthermore, for the C, and increase the strength of the supply roller 45 by thickening the shaft diameter is better for large is Tonashi
In order to maintain the lubricity, the core metal diameter of the supply roller 45 (normally 5
~ 6mm) larger than 4-6mm
Therefore, it was set to 10 mm. When these specific values of t, δ and C are substituted into the formula and calculated, the replenishment roller 4
The outer diameter B of No. 5 is B ≧ 16 mm . On the other hand, this embodiment
Then, the outer diameter A of the developing roller 35 can be reduced by reducing the size of the developing device.
Use in small developing units based on our experience
The smallest diameter of the developing roller 35 is 16 mm.
Set.

That is, in this embodiment, the supply roller 4
The outer diameter B of No. 5 is equal to or larger than the outer diameter A of the developing roller 35. However, the developing roller 35
Even though the outer diameter A value greater than the in <br/> wear much the better for small et al for miniaturization, in the embodiment shown in Figure 1,
With little emphasis on toner sealing properties and toner triboelectric charging properties, the outer diameter B of the supply roller 45 is actually formed slightly larger than the outer diameter A of the developing roller 35 , where A = 16 mm, B = 18
mm . For others, C = 10 mm, t = 2 m
m, δ = 1 mm, and L = 16 mm . This
Therefore , in this embodiment, unlike the case shown in FIG.
The thickness t of the developing roller seal member 40 is provided between the end of the developing roller 35 and the supply roller seal member 46 as shown in FIG.
And a gap g corresponding to the thickness of the developing device main body case 30 can be secured.

When the electrostatic latent image on the photoreceptor 14 is visualized by the developing unit 17, the developing roller 35 is replenished with the developing roller 35 in order to balance the photoreceptor potential and the toner potential. A bias voltage is applied to the roller 45. Then, as shown in FIG. 3, the agitator 34 is rotated to supply the toner 32 to the supply roller 45. Then, both the replenishing roller 45 and the developing roller 35 rotate counterclockwise in the figure, and the toner 32 is frictionally charged and replenished onto the developing roller 35. The toner 32 adhered on the developing roller 35 forms a uniform thin layer on the surface of the developing roller 35 by the thin layer blade 39. Then, the toner 32 is adhered to the surface of the photoconductor 14 by the developing roller 35 to visualize the electrostatic latent image.

[0023]

Therefore, according to the first aspect of the present invention, the value of the outer diameter of the replenishment roller is expressed by the above equation.
None, by making the above equation as close as possible to the value in the case of the equation, it is possible to reduce the size of the developing device and improve the developing function such as the toner sealing property and the triboelectric charging property of the toner. Achieve a good balance with a little emphasis.

Further, according to the second and third aspects of the present invention, the toner can be satisfactorily triboelectrically charged to improve the developing function of the developing device.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a developing device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an inconvenience when the distance between the supply roller and the developing roller in the developing device is considerably reduced.

FIG. 3 is a sectional view showing an internal mechanism of the developing device.

FIG. 4 is an overall schematic configuration diagram showing an internal mechanism of a laser printer including the developing device.

FIG. 5 is a partial side view of a conventional developing device.

[Explanation of symbols]

 Reference Signs List 17 developing device 32 toner 35 developing roller 40 developing roller seal member 45 supply roller 45a supply roller roller shaft 46 supply roller seal member A outside diameter of development roller B outside diameter of supply roller

Claims (3)

(57) [Claims] A supply roller is pressed against a developing roller to supply toner thereto, while a developing roller seal member is pressed against an outer periphery of an end of the developing roller, and a supply roller is pressed against an outer periphery of a roller shaft of the supply roller. In a developing device of an electrophotographic apparatus, which presses a seal member and prevents toner leakage from both in the roller axis direction , the outside of the supply roller
The diameter is B, the outer diameter of the supply roller sealing member is C,
The thickness of the developing roller seal member is t, and the supply roller is
Let δ be the bite amount when pressing against the developing roller.
A developing device of an electrophotographic apparatus , wherein B ≧ 2 (t + C / 2 + δ) . 2. The developing device for an electrophotographic apparatus according to claim 1, wherein said supply roller is formed of an elastic body. 3. The supply roller is formed of a conductive material,
2. The developing device for an electrophotographic apparatus according to claim 1, wherein a bias voltage is applied thereto.