JP3417612B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be used for a copying machine, a printer, a plotter, a facsimile, and the like. 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 electrodes based on image data. U.S. Pat. No. 3,689,935 discloses a method for applying an image and controlling the toner particles to be able to pass through the aperture so that an image is formed on a support by the passed toner particles. This image forming apparatus comprises a flat plate made of an insulator, a continuous reference electrode formed on one surface of the flat plate, and a plurality of insulated control electrodes formed on the other surface. An aperture electrode body having at least one row of apertures formed through the three electrodes for each of the control electrodes; and a means for selectively applying a potential between the reference electrode and the control electrode. Means for supplying charged toner particles so that the flow of the toner particles passing through the aperture is modulated by an electric potential; means for positioning the support in the particle flow path by relatively moving the support and the aperture electrode body It is composed of Also, for example, US Pat. No. 4,743,926.
Nos. 4,755,837, 4,780,733, and 4,814,796 disclose an image forming apparatus in which an aperture electrode body is arranged with a control electrode on a support side and a reference electrode on a toner supply side. I have. [0005] In contrast, US Pat.
In the above-mentioned U.S. Patent, the voltage applied to the control electrode when the aperture electrode is turned off by disposing the aperture electrode body with the reference electrode facing the support and the control electrode facing the toner supply side is disclosed in the above U.S. It is described that it can be suppressed to about １ ／ as compared with the image forming apparatus to be used. [0006] Here, the off-time means the time when the toner particles are not adhered to the support, that is, the time when a blank portion of the image is formed. At the time when a toner image is formed. However, in the conventional image forming apparatus as described above, as shown in FIG. 5, the insulating substrate 200 of the aperture electrode body improves the efficiency of toner flow generation. Therefore, a very thin polyimide sheet is used, and further, since a tensile force is applied to the sheet in a certain direction, the sheet is stretched in the tensile direction, and the sheet is stretched along the arrangement row of the apertures 60. Innumerable wrinkles occurred, and the contact pressure with respect to the toner carrier 140 varied. 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 the toner flow is difficult to occur in the aperture 60 located in the portion where the contact pressure is low. , Uneven density occurred. In addition, aperture 6
The orientation of the “0” with respect to the support also changes, which causes displacement of formed dots and image scattering, thereby causing image distortion. However, if the toner control means is made completely rigid, it becomes difficult to adjust to the shape of the toner carrier, which also causes a lack of contact stability. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide an excellent image forming apparatus which does not cause uneven image density or distortion. In order to achieve the above object, an image forming apparatus according to the present invention has a toner flow control means having an aperture row composed of a plurality of apertures and controlling a toner flow of charged toner. And the toner flow control means
Contact with a predetermined pressure around the aperture row position
And a supply unit for supplying toner to the toner flow control unit. The toner flow control unit is tension-supported in a direction orthogonal to the aperture row, and the base of the toner flow control unit is direction-dependent on rigidity. And the rigidity of the toner flow control means in the direction of the aperture row is higher than the rigidity in the direction perpendicular to the aperture row. The image forming apparatus of the present invention having the above-described structure is
The toner flow control means pressed against the toner carrier is supported in tension in a direction perpendicular to the aperture row, and the base material of the toner flow control means is made of a material having a rigidity-dependent direction. The rigidity in the direction of the aperture row is set to be higher than the rigidity in the direction orthogonal to the aperture row, so that wrinkles do not occur in the toner flow control means, and the shape of the toner carrier is easy to follow. The contact is stable and there is no density unevenness or distortion in the image. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an outline of an image forming apparatus embodying the present invention. In FIG. 1, a 1 mm gap is provided above an aperture electrode body 1 as a toner flow control means. Are provided on a chassis (not shown). A pair of transport rollers 119 is disposed on the right side of the back electrode plate 22 so as to transport the support body 20 so that the support body 20 can be inserted into the 1 mm gap.
In addition, a toner supply device 10 is provided below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, a support conveyed by the back electrode plate 22. A fixing device 26 is provided at the destination of the operation of the fixing device 20. Next, the components will be described in detail. The toner supply device 10 includes a toner case 11 also serving as a housing for the entire device, a toner 16 housed in the toner case 11, a supply roller 12 And a toner carrying roller 14 and a toner layer regulating blade 18. Here, the toner carrying roller 1
Reference numeral 4 denotes a member which carries the toner 16 and conveys the toner 16 toward the aperture electrode body 1. The supply roller 12 supplies the toner 16 to the toner carrying roller 14. The supply roller 12 and the toner carrying roller 14 are supported by the toner case 11 so as to be rotatable in the direction of the arrow shown in the figure. Further, the toner layer regulating blade 18
Is for adjusting the amount of 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 has a diameter of 1 μm on a polyimide insulating sheet 2 having a thickness of 25 μm.
A plurality of 00 μm apertures 6 are formed in one row, and a control electrode 4 having a thickness of 1 μm is formed for each aperture 6 on the upper surface. The apertures 6 are arranged in the longitudinal direction of the insulating sheet 2. I have. And the aperture electrode body 1
As shown in FIG. 1, is pressed against the toner carrying roller 14 at the position of the aperture 6 of the insulating sheet 2 with the control electrode 4 facing the support 20 side. As a pressure contact method, as shown in FIG. 1, the right end side of the aperture electrode body 1 is directly fixed to the case 11, and the left end side is fixed to the case 11 via the rubber sheet 27. The tension is applied in a direction perpendicular to the arrangement direction of the apertures 6. The insulating sheet 2 as a base material of the aperture electrode body 1 is formed of a polyimide film manufactured by a uniaxial stretching method, and the apertures 6 are arranged so that the stretching direction coincides with the arrangement direction of the apertures 6. 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 perpendicular thereto, even if tension is applied by the rubber sheet 27 in the direction perpendicular to the stretching direction of the insulating sheet 2, No wrinkles occur, and the aperture electrode body 1 easily follows the outer shape of the toner-carrying roller 14 exactly, so that the contact state between the two is stabilized. 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. Are arranged so as to pass through the uppermost portion of the peripheral surface and the central axis 32 of the toner carrying roller 14. According to this, each aperture 6
Based on the uppermost portion of the peripheral surface of the toner carrying roller 14,
By arranging the toner 16 uniformly on the left and right, the distribution of the toner 16 passing through each aperture 6 can be made uniform throughout the aperture. Also, the wall of the aperture 6 and the toner 16
Is in parallel with the flight direction, so that the toner can fly stably. Further, as shown in FIG. 3, the aperture electrode body 1 itself
Are pressed to the left and right with the same angle around the center. 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 uniformly pressed 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 an image signal. Further, a DC power supply 24 is connected between the back electrode plate 22 and the toner carrying roller 14, and the DC power supply can apply a voltage of +1 kV to the back electrode roller 22. It has become. 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 supply roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying roller 14 and is negatively charged. And is carried on the toner carrying roller 14. Carried toner 1
After the layer 6 is thinned and charged by the layer regulating blade 18, it 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 response to the image signal, the control electrode 4 corresponding to the image portion is supplied from the control voltage application circuit 8 with +
A voltage of 50 V is applied. As a result, in the vicinity of the aperture 6 corresponding to the image portion, electric force lines from the control electrode 4 toward the toner carrying roller 14 are formed 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 potential, passes through the aperture 6 from above the toner carrying roller 14, and is drawn out to the control electrode 4 side. The extracted toner 16 further flies toward the support 20 due to the electric field formed between the support 20 and the aperture electrode body 1 by the voltage applied to the back electrode plate 22, and Deposit on top to form pixels. A voltage of 0 V is applied from the control voltage application circuit 8 to the control electrode 4 corresponding to the non-image portion.
As a result, no electric field is formed between the toner carrying roller 14 and the control electrode 4, so that the toner carrying roller 1
Since the toner 16 on the sheet 4 does not receive electrostatic force, the aperture 6
Do not pass. Further, the support 20 is fed by one pixel in a direction perpendicular to the aperture row while one row of pixels is formed by the toner 16 on the surface thereof. Then, by repeating the above process, a toner image is formed on the entire surface of the support 20. Thereafter, the formed toner image is fixed on the support 20 by the fixing device 26. At this time, in this embodiment, the aperture electrode 1
Since the insulating sheet 2 has six rows of apertures formed in its extending direction, no wrinkles are generated, and the aperture electrode body 1 easily follows the outer shape of the toner-carrying roller 14 faithfully. It is stable and therefore has no density unevenness, resulting in a beautiful formed image. In the image forming apparatus configured as described above, if the insulating toner is used, the toner carrying roller 14
The insulation between the electrode and the control electrode 4 is maintained, and the dielectric breakdown of the aperture 6 does not occur. 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 facing the aperture. 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 due to sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, the inside of the aperture 6 is not affected. Since the electric field can be controlled so as not to pass through the aperture 6, the controllability of the toner is good. Further, since the toner carrying roller 14 and the aperture electrode body 1 are opposed to each other with the toner layer interposed therebetween, they can be disposed at a relatively short distance, so that the control voltage can be reduced and an inexpensive driving element can be provided. Can be used. The insulating sheet 2 of the aperture electrode body 1
Is directed to the toner carrying roller 14 side, so that the toner 1
Even when the control electrode 6 does not exist, the control electrode 4 and the toner carrying roller 14 come into contact with each other, causing an electric short circuit, and the driving element is not broken. Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact at the entrance of the aperture 6, the toner 16 deposited at the entrance of the aperture 6 is As a result, the toner 16 is not washed out and clogged with the toner 16, thereby blocking the aperture 6. The present invention is not limited to the embodiment described in detail above, and various changes can be made without departing from the gist of the present invention. For example, in the above embodiment, the control voltage of the aperture corresponding to the non-image portion was set to 0 V, but this may be a negative voltage. In this case, an image with less fog can be obtained. Further, in the above embodiment, the aperture electrode body is used as the toner flow control means. However, for example, a stitch-shaped electrode body as described in the specification of US Pat. No. 5,036,341 may be used. As shown in FIG. 4, the reinforcing member 28 is divided and bonded or coated in a direction parallel to the direction in which the apertures 6 are arranged, so that the Young's modulus in the direction in which the apertures 6 are arranged can be reduced. If the value is larger than the Young's modulus, the same effect as in the above-described embodiment can be obtained. The reinforcing member may be formed on any surface of the aperture electrode body 1. However, when the reinforcing member 28 is formed by a conductive member on the surface on the control electrode 4 side, a coating layer or the like for insulating both is provided. There is a need. Further, cloth such as glass fiber or carbon fiber having different Young's modulus in the vertical and horizontal directions is impregnated with an insulating resin or the like to be used as the insulating sheet 2, or a filler such as glass fiber or carbon fiber is used in the fiber direction. May be mixed with the polyimide film in the arrangement direction of the apertures 6 and used. As is apparent from the above description, the image forming apparatus of the present invention can form a high-definition image free from uneven density and distortion.

BRIEF DESCRIPTION OF THE 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 view showing another embodiment of the image forming apparatus of the present invention. FIG. 5 is a sectional view showing an aperture electrode body used in a conventional image forming apparatus. [Description of Signs] 1 Aperture electrode body 2 Insulating sheet 4 Control electrode 6 Aperture 8 Control voltage application circuit 14 Toner carrying roller 22 Back electrode plate 24 DC power supply

Claims (1)

(57) [Claim 1] A toner flow control means having an aperture row composed of a plurality of apertures and controlling a toner flow of charged toner, and an aperture for the toner flow control means.
Contact with a predetermined pressure around the position of the
Serial comprising a supply means for supplying toner to the toner flow controlling means, with the tensile supporting the toner flow controlling means in a direction perpendicular to the aperture columns, there is a directional dependence on the rigidity of the base material of the toner flow controlling means An image forming apparatus comprising a material, wherein the rigidity of the toner flow control means in the direction of the aperture row is higher than the rigidity in a direction orthogonal to the aperture row.