JPH1086434A - Image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming apparatus which can form images without fogging. SOLUTION: A row of apertures 6 is formed in a longitudinal direction in a polyimide insulating base 2 of a print head 1. A control electrode 4 is formed to surround an edge of each aperture 6. An elastic member 5 of a 10μm-thick silicon rubber coat is formed in the vicinity of the aperture row of a face of the print head 1 opposite to the face where the control electrodes 4 are formed. When a toner is transferred while held between a toner-holding roller and the base 2, the toner compressed and deformed between the holding roller and base 2 is recovered by the elastic member 5, so that the toner is supplied in a stable state under the apertures 6. The toner does not splash under the apertures 6 and therefore stable images without fogging are 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 applied to a copying machine, a printer, a facsimile, a plotter, and the like.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for controlling the passage of toner particles by applying an image signal to an electrode having a toner flow path to obtain an image on a recording medium is disclosed in Japanese Patent Laid-Open No. 6-25 / 1994.
Japanese Patent Application Laid-Open No. 5163/1993 discloses an apparatus using an opening (hereinafter referred to as an aperture) as a toner flow path.
No. 8, for example.

The conventional image forming apparatus includes a print head made of an insulating sheet having toner flow paths arranged in rows and having control electrodes corresponding to the toner flow paths, and a toner carrying roller for carrying toner. , One side of the print head is arranged so as to be in contact with the peripheral surface of the toner carrying roller in the vicinity of the toner flow channel, and the passage of the charged toner through the aperture is controlled by applying a voltage corresponding to image data to the control electrode Then, a toner image is formed on a recording medium disposed on the side opposite to the support roller with the print head interposed therebetween.

According to this image forming apparatus, since the toner on the toner carrying roller and the print head are in contact in the vicinity of the toner flow path, the toner that adheres to the vicinity of the toner flow path and hinders the flow of toner comes later. Rubbing with toner does not hinder the flow of toner.

[0005] Further, since the toner carried and supplied on the toner carrying roller adheres to the toner carrying roller by physical force such as van der Waals force as well as the mirror image force by the charging of the toner, the toner is controlled by the control electrode. A large voltage is required to separate them by the electric field due to. However,
In this image forming apparatus, the toner carried on the toner carrying roller slides on the print head in the vicinity of the toner flow path, receives a mechanical force, and is released from the adhesive force with the toner carrying roller. Therefore, the passage of the toner through the toner flow path can be controlled with a small voltage. In addition, arranging the print head and the toner on the toner carrying roller to be in contact makes the control electrode on the print head and the toner carrying roller extremely close to each other. This leads to high contrast being obtained with a small voltage.

[0006]

However, in the conventional image forming apparatus as described above, the toner on the toner carrying roller is pushed by the print head and is conveyed to the toner flow path. When the pressure is released from the pressure of the head, the toner jumps up from the toner carrying roller due to the elastic energy of the toner, flies over the control of the control electric field, and flies to the recording medium side.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide an image forming apparatus capable of forming an image without fogging.

[0008]

In order to achieve this object, an image forming apparatus according to a first aspect of the present invention comprises a charged material flow path through which a charged material passes and a control electrode for controlling the passage. Charge means for controlling the passage of the charged material supplied by the charged body flow control means, and supplying the charged body to the charged body flow control means. In an image forming apparatus for forming an image on a recording medium supported on the opposite side of the charged body flow control means with respect to the charged body flow control means, an elastic member is provided on the charged body flow control means side of the charged body flow control means. It is located near the road.

Further, the image forming apparatus according to the present invention is characterized in that:
The elastic member has a Young's modulus of 100 kg / mm ² or less.

[0010] In the image forming apparatus according to the third aspect, the elastic member has silicon rubber as a main component.

Further, the image forming apparatus according to claim 4 is
The upstream side of the elastic member in the charged body supply direction by the charged body holding means is inclined toward the charged body flow control means.

Further, the image forming apparatus according to the present invention is characterized in that:
A recess is provided near the charged body flow path of the charged body flow control means, and an elastic member is inserted and arranged in the recess.

In the image forming apparatus according to the present invention, the height of the end of the elastic member on the upstream side in the direction in which the charged body is supplied by the charged body carrying means coincides with the surface of the charged body flow control means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. A toner supply device 10 is provided below the image formation device, and a toner supply device 10 is provided above the toner supply device 10 for controlling toner flow. Print head 1 is provided. Incidentally, the print head 1 constitutes the charged material flow control means of the present invention. Above the print head 1, a back electrode, preferably a back electrode roller 22, is rotatably disposed with an interval of about 1 mm. In the gap between the print head 1 and the back electrode roller 22, the recording medium 20 is moved by the rotation of the back electrode roller 22 in the direction of arrow D shown in FIG. Is transported in the direction indicated by arrow C, and a thermal fixing device 26 comprising a pair of a pressure roller and a heating roller is provided at the transport destination. still,
The heat fixing device 26 can be replaced with any one of a heat fixing method and a pressure fixing method.

Next, the components will be described in detail. First, as shown in FIG. 1, the toner supply device 10 includes a toner case 1 which also serves as a housing of the entire device.
The toner case 11 includes a charged toner, preferably an insulative toner 16, and a cylindrical toner carrying roller for carrying the toner 16 and transporting the toner 16 toward the print head 1. 14 is provided rotatably in the direction of arrow B shown in FIG. Incidentally, the toner carrying roller 14 constitutes the charged body carrying means of the present invention. A cylindrical supply roller 12 that feeds the toner 16 contained in the toner case 11 to the toner carrying roller 14 is provided diagonally below and to the left of the toner carrying roller 14.
Are provided rotatably in the direction of arrow A shown in FIG. The supply roller 12 and the toner carrying roller 14 are arranged in parallel with each other such that the generatrix of their cylindrical surfaces is in contact with each other.

In the toner case 11, above the supply roller 12, the amount of toner 16 carried by the toner carrying roller 14 is adjusted so as to be uniform on the roller surface of the toner carrying roller 14. A toner layer regulating blade 18 for uniformly charging the toner 16 is provided, and one end of the toner layer regulating blade 18 is pressed against the toner carrying roller 14.

The print head 1 has, for example, a thickness 2
An insulating base 2 made of polyimide having a diameter of about 5 μm is formed. On the base 2, as shown in FIG. 2, apertures 6 serving as charged flow paths having a diameter of about 60 μm are arranged in a line in the longitudinal direction of the print head 1. Is formed. Also,
Around the aperture 6, a control electrode 4 made of a conductive metal pattern such as copper or gold having a thickness of about 8 μm is formed so as to surround an edge of each aperture 6.

The surface of the print head 1 opposite to the surface on which the control electrodes are formed (the surface on the side of the toner carrying roller).
In the vicinity of the aperture row, an elastic member 5 made of a silicon rubber coat having a thickness of 10 μm is formed so as to extend along the aperture row. The elastic member 5 is formed of a material having a Young's modulus of 100 kg / mm ² or less, and is sufficiently softer than the base 2 having a Young's modulus exceeding 500 kg / mm ² .

The print head 1 is attached to the toner case 11 with tension so that the elastic member 5 and the base 2 contact the toner 16 on the toner carrying roller 14. At this time, each aperture 6 of the print head 1 is positioned at a position facing each back electrode roller 22 on the peripheral surface of each toner carrying roller 14.

The control electrodes 4 of the print head are connected to drive elements 8 respectively. The drive element 8 applies 0 V, +30 V, or -30 V to the control electrode 4 based on an image signal sent from an image signal receiving unit (not shown).
V, and a voltage of +30 V is applied.
The image signal receiving means (not shown) is connected to an external computer, image reading device, image communication device, or the like.

Further, a DC power supply 24 is connected to the back electrode roller 22, and the DC power supply 24 can apply a voltage of +1 kV to each of the back electrode rollers 22.

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

First, when the supply roller 12 rotates in the direction of arrow A shown in FIG. 1, the toner 16 accommodated in the toner case 11 is
Conveyed toward. An extra toner 16 supplied from the supply roller 12 is supplied with a certain amount of toner by the layer regulating blade 18 to the print head 1.
, And is carried as a thin and uniform toner layer, and is charged to a predetermined polarity, here negative (negative), while being rubbed by the layer regulating blade 18. The toner carrying roller 14 is guided between the print head 1 and the toner carrying roller 14.
The thinned toner 16 is conveyed toward the print head 1 as the toner carrying roller 14 rotates in the direction of arrow B while being carried on the toner carrying roller 14.

The toner 16 on the toner carrying roller 14
Is sandwiched between the toner carrying roller 14 and the base 2 of the print head 1, and the toner 16 rolls due to the sliding caused by this contact, and the adhesive force between the toner carrying roller 14 and the toner 16 is uniformly reduced in the width direction. In this state, it is supplied to the vicinity of the aperture row of the print head 1. Here, since the elastic member 5 is formed in the vicinity of the aperture row of the print head 1, a stable state in which the deformation of the toner 16 that has been compressed and deformed by being sandwiched between the toner carrying roller 14 and the base 2 is restored. Is supplied under the aperture 6, so that the toner 16 does not bounce under the aperture 6.

The control voltage is given as follows.

For example, in response to an image signal, the control drive element 8 applies +3 to the control electrode 4 corresponding to the image portion.
When a positive voltage of 0 V is applied, an electric force directed from the control electrode 4 to the toner carrying roller 14 near the aperture 6 corresponding to the control electrode 4 due to a potential difference between the control electrode 4 and the toner carrying roller 14. A line is formed. As a result, the negatively charged toner 16 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 is further applied to the recording medium 2 by a high voltage of +1 kV applied to the back electrode roller 22.
0 and the aperture electrode body 1 generate an electric field,
It flies toward the recording medium 20 and is deposited on the recording medium 20 to form dot-shaped pixels.

A negative voltage of 0 V or -30 V is applied from the driving element 8 to the control electrode 4 corresponding to the non-image portion. As a result, between the toner carrying roller 14 and the control electrode 4, the toner carrying roller 14
Is not formed, and the toner 16 cannot pass through the aperture 6. In addition, at this time, when a negative voltage of -30 V is applied, a voltage lower than that of the toner carrying roller 14 is applied to the control electrode 4, so that an electric field corresponding to the image portion is applied between them. Is formed, and even if the slightly compressed toner 16 is released under the aperture 6 and rebounds, the toner 16 can be effectively prevented from passing through the aperture 6. Therefore, an image with less fog is formed.

On the other hand, the recording medium 20 conveyed through the gap between the aperture electrode body 1 and the back electrode roller 22 has a structure in which one row of pixels is formed by the toner 16 on the surface of the recording medium 20. It is sent by one pixel in the direction orthogonal to the columns. Then, by repeating the above process, a toner image is formed on the entire surface of the recording medium 20. After that, the toner image formed on the recording medium 20 is fixed on the recording medium 20 by the heat fixing device 26.

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.

Further, in the above-described embodiment, the print head 1 having the circular apertures 6 arranged in a line is used as the charged body flow control means. However, for example, a rectangular aperture such as a triangle or a quadrangle is used. Maybe, Tokiohei 1
It is also possible to use a mesh-shaped electrode body as described in JP-A-503221. Also, JP-A-6-2
It is also applicable to an edge-shaped print head having no aperture as described in Japanese Patent No. 55163.

Further, in the above-mentioned embodiment, silicon rubber is used as the rubber elastic member, but any material having elasticity may be used. In the case of silicon rubber, there is an advantage that the adhesion to the toner is small due to the releasability of silicon, and cleaning of the print head is unnecessary.

In the present embodiment, the base 2 is coated with silicone rubber to form an elastic member 5 having a thickness of 10 μm.
Is formed near the aperture row, that is, both on the upstream side and the downstream side in the toner supply direction with respect to the aperture row, but the elastic member is formed only on the upstream side in the toner supply direction with respect to the aperture row. It may be.

The elastic member may be as shown in FIG. 3 or FIG.

The elastic member 30 shown in FIG. 3 is configured such that both ends in the supply direction of the toner 16 are inclined toward the base 2.

The elastic member 32 shown in FIG. 4 is configured to be inserted and arranged in a concave portion 34 formed near the aperture row of the base 2.

With this configuration, the ends of the elastic members 32 and 34 on the upstream side in the supply direction of the toner 16 and the base surface can be made flat (having the same height). Toner 1 at the boundary between members 32 and 34
6 can be carried smoothly.

[0038]

As is apparent from the above description, the image forming apparatus according to the first aspect of the present invention includes the elastic member on the side of the charged body carrying means of the charged body flow control means, so that the charging current is reduced. The charged body compressed by the contact pressure with the control means does not jump in the charged body flow path due to its elastic energy,
An image without fog can be formed.

Further, according to the image forming apparatus of the present invention,
Since the elastic member has a Young's modulus of 100 kg / mm ² or less, it is possible to further prevent the charged body from jumping up, and to form an image without fogging.

Further, in the image forming apparatus according to the third aspect, since the elastic member is mainly composed of silicon rubber, it is possible to prevent the charged member from adhering to the elastic member due to the releasability of the silicon rubber. Thus, the cleaning of the vicinity of the charged material flow path is unnecessary or the number of times can be reduced.

Further, in the image forming apparatus according to the present invention,
Since the upstream side of the elastic member in the charged body supply direction by the charged body carrying means is inclined toward the charged body flow control means, it is possible to smoothly carry the charged body at the boundary between the charged body flow control means and the elastic body. it can.

Further, according to the image forming apparatus of the present invention,
Since the concave portion is provided near the charged material flow path of the charged material flow control means, and the elastic member is inserted and arranged in the concave portion, the transfer of the charged material at the boundary between the charged material flow control means and the elastic body can be smoothly performed. Can do it.

In the image forming apparatus according to the present invention, the height of the end of the elastic member on the upstream side in the direction in which the charged material is supplied by the charged material carrying means coincides with the surface of the charged material flow control means. In addition, it is possible to smoothly carry the charged body at the boundary between the charged body flow control means and the elastic body.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a print head mounted on the image forming apparatus.

FIG. 3 is a sectional view of a print head according to a modified embodiment of the present invention.

FIG. 4 is a sectional view of a print head according to another modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 2 Base 4 Control electrode 5 Elastic member 6 Aperture 8 Drive element 14 Toner carrying roller 16 Toner 30 Elastic member 32 Elastic member 34 Depression

Claims (6)

[Claims] 1. A charged body flow control means having a charged body flow path through which a charged body passes and a control electrode for controlling the passage of the charged body, and a charged body carrying means for supplying a charged charged body to the charged body flow control means. Forming an image on a recording medium supported on the opposite side of the charged body carrying means with respect to the charged body carrying means by controlling the passage of the charged body supplied by the charged body carrying means. An image forming apparatus, comprising: an elastic member disposed in the vicinity of a charged material flow path on the charged material carrying means side of the charged material flow control means. 2. The elastic member has a Young's modulus of 100 kg /
The image forming apparatus according to claim 1, wherein the diameter is equal to or less than mm ² . 3. The image forming apparatus according to claim 1, wherein the elastic member contains silicon rubber as a main component. 4. The image forming apparatus according to claim 1, wherein the elastic member has an upstream side in a charged body supply direction by the charged body holding unit inclined toward the charged body flow control unit. 5. The image according to claim 1, wherein a recess is provided near the charged body flow path of the charged body flow control means, and the elastic member is inserted and arranged in the recess. Forming equipment. 6. The apparatus according to claim 1, wherein a height of an end of said elastic member on an upstream side in a charged body supply direction by said charged body carrying means coincides with a surface of said charged body flow control means. The image forming apparatus as described in the above.