JPH0781129A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device which does not generate the density unevenness or distortion of an image by constituting the base of a toner stream-control means of a material of which the rigidity has a directional dependency. CONSTITUTION:The insulating sheet for an aperture electrode unit 1 is formed of a polyimide film which is manufactured by the uniaxial orientation method, and an aperture 6 is formed in such a manner that the orientation direction may meet the orientation direction of the aperture 6. Since the Young's modulus of the stretching direction of the insulating sheet is larger than the Young's modulus of the direction which is orthogonal to the stretching direction, even if a tension is applied in the stretching direction of the insulating sheet by a rubber sheet 27, wrinkles do not generate on the insulating sheet. Also, the aperture electrode unit 1 is easy to go along faithfully the outer shape of a toner carrying roller 14. Therefore, the contact condition of both parts is stabilized, and a beautiful image without a density unevenness or distortion can be formed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses, an electrode having a plurality of openings (hereinafter referred to as apertures) is used, and a voltage is applied to the electrode based on image data. U.S. Pat. No. 3,689,935 discloses controlling toner particles so that they can pass through the aperture and forming an image on a support by the toner particles that have passed.

This image forming apparatus comprises a flat plate made of an insulating material, a continuous reference electrode formed on one surface of the flat plate, and a plurality of control electrodes insulated from each other formed on the other surface. , An aperture electrode body having at least one row of apertures formed through each of the control electrodes, and a means for selectively applying a potential between the reference electrode and the control electrode. A means for supplying the charged toner particles so that the flow of the toner particles passing through the aperture is modulated by the electric potential, and a means for relatively moving the support and the aperture electrode body to position the support in the particle flow path. It consists of and.

Also, for example, US Pat. No. 4,743,926.
Nos. 4,755,837, 4,780,733, and 4,847,796 disclose an image forming apparatus in which an aperture electrode body is arranged with a control electrode on the support side and a reference electrode on the toner supply side. There is.

In contrast, US Pat. No. 4,912,489
In the specification of the above U.S. Pat. It is described that it can be suppressed to about 1/4 as compared with the image forming apparatus.

Here, the "off" means a time when the toner particles are not attached to the support, that is, a time when a blank portion of an image is formed, and conversely, "on" means that the support is on the support. It means a time point when a toner image is formed on.

[0007]

However, in the conventional image forming apparatus as described above, as shown in FIG. 5, the insulating substrate 200 of the aperture electrode body is used as an insulating substrate 200 to improve the toner flow generation efficiency. Since a thin polyimide sheet is used for the sheet, and a tensile force is applied to the sheet in a certain direction, the sheet stretches in the tensile direction and countless wrinkles are formed along the arrangement row of the apertures 60. Occurs, and the contact pressure with respect to the toner carrier 140 varies. Therefore, a large amount of toner flow is likely to occur in the aperture 60 located in the portion where the contact pressure is high, and a toner flow is less likely to occur in the aperture 60 located in the portion where the contact pressure is low. There was unevenness in density. In addition, aperture 6
The orientation of 0 with respect to the support also changed, which caused positional deviation of formed dots and image scattering, resulting in image distortion.

However, if the toner control means is made completely rigid, it becomes difficult to adapt to the shape of the toner carrier, which also causes a lack of contact stability.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an excellent image forming apparatus in which uneven density or distortion of an image does not occur.

[0010]

To achieve this object, the image forming apparatus of the present invention is characterized in that the base material of the toner flow control means is made of a material whose rigidity has a direction dependency.

[0011]

The image forming apparatus of the present invention having the above structure is
Since the base material of the toner flow control means is made of a material whose rigidity has direction dependency, wrinkles do not occur in the toner flow control means and the shape of the toner carrier is easily followed, so that both are stable. Contact with each other to prevent uneven density or distortion in the image.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of an image forming apparatus embodying the present invention. A rear electrode plate 22 has a gap of 1 mm above an aperture electrode body 1 as a toner flow control means. Are arranged on a chassis (not shown). A pair of conveying rollers 119 are arranged on the right side of the back electrode plate 22 so that the supporting body 20 can be conveyed and inserted into the gap of 1 mm.
A toner supply device 10 is arranged below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, a support body conveyed by the back electrode plate 22. A fixing device 26 is disposed at the destination of the movement of 20.

Next, the respective components will be described in detail. In the toner supply device 10, the toner case 11 also serving as a housing of the entire device, the toner 16 housed in the toner case 11, and the supply roller 12 are provided. And a toner carrying roller 14 and a toner layer regulating blade 18. Here, the toner carrying roller 1
Reference numeral 4 is for carrying the toner 16 and carrying it toward the aperture electrode body 1, and the supply roller 12 is for supplying the toner 16 to the toner carrying roller 14.

The supply roller 12 and the toner carrying roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in FIG. Further, the toner layer regulating blade 18
Is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14. .

As shown in FIG. 2, the aperture electrode body 1 includes a 25 μm thick insulating sheet 2 made of polyimide and having a diameter of 1 μm.
A plurality of apertures 6 having a size of 00 μm are formed in one row, and a control electrode 4 having a thickness of 1 μm is formed on each of the apertures 6 on the upper surface. The apertures 6 extend in the longitudinal direction of the insulating sheet 2. . As shown in FIG. 1, the aperture electrode body 1 is pressed against the toner carrying roller 14 at the aperture 6 position of the insulating sheet 2 with the control electrode 4 facing the support body 20 side. . As a pressure welding method, as shown in FIG. 1, the right end side of the aperture electrode body 1 is
It is directly fixed to the case 11 and its left end side is fixed to the case 11 via a rubber sheet 27, whereby tension is applied in a direction orthogonal to the arrangement direction of the apertures 6.

The insulating sheet 2 which is a base material of the aperture electrode body 1 is formed of a polyimide film manufactured by a uniaxial stretching method, and the aperture 6 is arranged so that the stretching direction and the arrangement direction of the apertures 6 coincide with each other. Are formed.
Since the Young's modulus in the stretching direction of the insulating sheet 2 is larger than the Young's modulus in the direction orthogonal thereto, even if tension is applied in the stretching direction of the insulating sheet 2 by the rubber sheet 27, wrinkles are generated in the insulating sheet 2. Without doing
In addition, the aperture electrode body 1 easily conforms to the outer shape of the toner carrying roller 14, so that the contact state between the two is stable.

Here, the positional relationship between the aperture 6 of the aperture electrode body 1 and the toner carrying roller 14 will be described in detail. As shown in FIG. 3, each center line 30 of each aperture 6 has a toner carrying roller 14. It is arranged so as to pass through the uppermost portion of the peripheral surface of and the central shaft 32 of the toner carrying roller 14. According to this, each aperture 6
Based on the uppermost part of the peripheral surface of the toner carrying roller 14,
By arranging them evenly on the left and right, the distribution of the toner 16 passing through each aperture 6 can be made uniform over the entire area of the aperture. In addition, the wall surface of the aperture 6 and the toner 16
Since the flying direction of the toner is parallel to the flying direction of the toner, it is possible to stably fly the toner.

Further, the aperture electrode body 1 itself has an aperture 6 with respect to the toner carrying roller 14 as shown in FIG.
It is pressed so that it bends to the left and right about the same angle. As a result, the contact area between the aperture electrode body 1 and the toner carrying roller 14 can be increased, and the lower periphery of the aperture 6 can be pressed uniformly to the left and right, so that uneven toner concentration is minimized. Can be suppressed.

A control voltage application circuit 8 is connected between the control electrode 4 and the toner carrying roller 14.
The control voltage application circuit 8 is configured to apply a voltage of 0 V or +50 V to the control electrode 4 based on the image signal.

Further, a DC power source 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power source is + with respect to the back electrode roller 22.
A voltage of 1 kV can be applied.

Next, the operation of the image forming apparatus configured as described above will be described.

First, by rotating the toner carrying roller 14 and the supplying roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supplying roller 12 is rubbed against the toner carrying roller 14 to be negatively charged. The toner is carried on the toner carrying roller 14. Toner 1 carried
The layer 6 is thinned by the layer regulation blade 18 and charged, and then is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied under the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

Here, in accordance with the image signal, the control voltage applying circuit 8 adds + to the control electrode 4 corresponding to the image portion.
A voltage of 50V is applied. As a result, a line of electric force directed from the control electrode 4 to the toner carrying roller 14 is formed in the vicinity of the aperture 6 corresponding to the image portion due to the potential difference between the control electrode 4 and the toner carrying roller 14. As a result, the negatively charged toner receives an electrostatic force in the direction of higher electric potential, passes through the aperture 6 from the toner carrying roller 14 and is drawn to the control electrode 4 side. The extracted toner 16 further flies toward the support body 20 due to an electric field formed between the support body 20 and the aperture electrode body 1 by the voltage applied to the back electrode plate 22, and the support body 20 is supported. Deposit on top to form pixels.

A voltage of 0V is applied from the control voltage applying circuit 8 to the control electrode 4 corresponding to the non-image portion.
As a result, since no electric field is formed between the toner carrying roller 14 and the control electrode 4, the toner carrying roller 1
Toner 16 on 4 is not subjected to electrostatic force, so aperture 6
Do not pass through.

Further, the support 20 is fed by one pixel in the direction perpendicular to the aperture row while the toner 16 forms one row of pixels on the surface thereof. Then, the toner image is formed on the entire surface of the support 20 by repeating the above process. Then, the formed toner image is fixed on the support 20 by the fixing device 26.

At this time, in this embodiment, the aperture electrode body 1
Since the insulating sheet 2 of 6 has 6 rows of apertures formed in the extending direction thereof, wrinkles are not generated, and the aperture electrode body 1 easily follows the outer shape of the toner carrying roller 14, so that the contact state is The image is stable and therefore has no uneven density, resulting in a beautiful formed image.

If an insulating toner is used in the image forming apparatus constructed as described above, the toner carrying roller 14 is used.
The insulation between the control electrode 4 and the control electrode 4 is maintained, and the aperture 6 does not cause dielectric breakdown.

In the above process, the control electric field generated by the control electrode 4 is formed between the control electrode 4 and the inside of the aperture 6, and between the aperture 6 and the toner carrying surface of the toner carrying roller 14 which faces the aperture 6. Toner 1
Since the control electric field can be directly applied to 6, the control efficiency is good.

Further, even if a part of the supplied toner 16 receives a mechanical force or the like by sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, inside the aperture 6 Since it can be controlled so as not to pass through the aperture 6 by the electric field, the toner controllability is good.

Further, since the toner carrying roller 14 and the aperture electrode body 1 are opposed to each other with the toner layer in between, the control voltage can be lowered and the inexpensive drive element can be provided because they can be arranged at a relatively short distance. Can be used.

In addition, the insulating sheet 2 of the aperture electrode body 1
Is directed toward the toner carrying roller 14 side, so that the toner
Even if 6 is not present, the control electrode 4 and the toner carrying roller 14 do not come into contact with each other and electrically short-circuit, and the drive element is not destroyed.

Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact with each other at the entrance portion of the aperture 6, the toner 16 accumulated at the entrance portion of the aperture 6 is not supported. Since the toner 16 is pushed away by the toner sequentially supplied, the toner 16 does not accumulate and bridge to block the aperture 6.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, in the above embodiment, the control voltage of the aperture corresponding to the non-image portion is set to 0V, but this may be a negative voltage. In this case, an image with less fogging can be obtained. Further, in the above embodiment, the aperture electrode body is used as the toner flow control means, but it is also possible to use, for example, a knitted electrode body as described in the specification of US Pat. No. 5,036,341.

Further, as shown in FIG. 4, the reinforcing material 28 is divided and adhered or coated in a direction parallel to the arrangement direction of the apertures 6, and the Young's modulus in the arrangement direction of the apertures 6 in the direction orthogonal to that. If the Young's modulus is larger than the Young's modulus, the same effect as that of the above-described embodiment can be obtained. The reinforcing member may be formed on either surface of the aperture electrode body 1, but when the reinforcing material 28 is formed on the surface of the control electrode 4 side by the conductive member, a coat layer or the like for insulating the both is provided. There is a need.

Further, a cloth such as glass fiber or carbon fiber having a different Young's modulus in length and width is used as the insulating sheet 2 by impregnating an insulating resin or the like, or a filler such as glass fiber or carbon fiber is used in the fiber direction. May be mixed with the polyimide film so as to be aligned with the arrangement direction of the apertures 6 and used.

[0038]

As is apparent from the above description, the image forming apparatus of the present invention is characterized in that the base material of the toner flow control means has a direction dependency in bending rigidity, and there is no density unevenness or distortion. Therefore, a high-definition image can be formed.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a perspective view showing a configuration of an aperture electrode body used in the image forming apparatus of the present invention.

FIG. 3 is a diagram schematically showing a configuration of an aperture electrode body and a toner carrying roller used in the image forming apparatus of the present invention.

FIG. 4 is a diagram showing another embodiment of the image forming apparatus of the invention.

FIG. 5 is a sectional view showing an aperture electrode body used in a conventional image forming apparatus.

[Explanation of symbols]

 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 8 Control voltage application circuit 14 Toner carrier roller 22 Rear electrode plate 24 DC power supply

Claims (1)

[Claims] 1. A material which has a toner flow control means for controlling the toner flow of charged toner and a supply means for supplying the toner to the control means, and a base material of the toner flow control means is a material whose rigidity depends on a direction. An image forming apparatus comprising: