JPH1120226A - Image forming unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming unit in which a good print quality is sustained by preventing the rotational upstream part of an insulation sheet from being wound around the circumferential surface of a toner carrying roller. SOLUTION: The rotational upstream part 28a of an insulation sheet 28 is prevented from being stuck to or wound around the circumferential surface of a toner carrying roller by making thick the rotational upstream part 28a thereby enhancing the rigidity thereat. Consequently, the toner particles are not pressed abnormally between the circumferential surface of the toner carrying roller and the rotational upstream part 28a of the insulation sheet 28 and since the insulation sheet 28 is constantly kept in stabilized state at the rotational upstream part 28a, uniform supply of toner to through holes 30 is not disturbed. According to the structure, toner is not shifted and a good print quality can be sustained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming unit, and more particularly, to controlling the passage of a charged material such as toner by controlling the voltage applied to a control electrode provided in a through-hole to form an image on an image recording medium with the charged material. The present invention relates to an image forming unit to be formed.

[0002]

2. Description of the Related Art Hitherto, as this type of image forming unit, for example, a configuration as shown in FIGS. 10 and 11 has been known (Japanese Patent Laid-Open No. 2-297570). Here, the insulating sheet 302 of the aperture electrode body 300 is disposed with respect to the toner transport roller 304 as illustrated. The rotation of the toner transport roller 304 in the direction of the arrow causes the peripheral surface 304 of the toner transport roller 304 to rotate.
a) toner particles 308 as a charged body carried on
Is supplied to the vicinity of the through hole 306 of the insulating sheet 302. At this time, when a predetermined positive voltage is applied to the control electrode 310 provided on the surface of the insulating sheet 302 opposite to the toner transport roller 304, the peripheral surface 304a of the toner transport roller 304 is negatively charged. The toner particles 308 that have passed through the through-hole 306 of the insulating sheet 302 fly toward a positive electrode (not shown) charged above the insulating sheet 302 at a high positive voltage. An image is formed by adhering to the surface of an image recording medium 312 such as recording paper conveyed between the sheet and the insulating sheet 302.

FIG. 11 is a perspective view showing only the aperture electrode body 300. Since the enlargement ratio is lower than that of FIG. 10, the arrangement of a large number of through holes 306 of the insulating sheet 302 is represented by a line. ing.

[0004]

However, the above-described conventional configuration has the following problems. That is, the potential difference between the control electrode 310 of the aperture electrode body 300 and the toner transport roller 304 is a voltage that can be directly controlled by a simple electronic circuit (the driving integrated circuit 311 in FIG. 11). This is the limit, and if the insulating sheet 302 is too thick, the toner particles 30
8 cannot be sufficiently peeled off from the peripheral surface 304 a of the toner conveying roller 304, so that the toner 8 cannot fly from the through hole 306 of the insulating sheet 302 toward the image recording medium 312. Therefore, the insulating sheet 3 of the aperture electrode body 300
02, for example, had a thickness of about 25 μm or less, which had to be adopted.

As the insulating sheet 302, a polyimide resin or the like is usually used. However, since the insulating sheet 302 must be thin as described above, its shape is affected by the surrounding conditions and deformed. It is inevitable that the sheet is so-called small in rigidity.

Particularly, in the case where the control electrode 310 is formed in the through hole 306 by extending the conducting wire 311a from the driving integrated circuit 311 existing on the downstream side of the rotation of the toner conveying roller 304 due to the necessity of the design or the restriction of the design. In general, since the conductive wire 311a and the control electrode 310 are usually metal layers, of the insulating sheet 302, the portion 302a on the downstream side of the rotation of the toner conveying roller 304 can secure the rigidity required to maintain the shape during use. . However, conductor 31
It is impossible to secure required rigidity in the rotation upstream portion 302b of the toner transport roller 304 in which 1a and the control electrode 310 are not present.

For this reason, as shown in the figure, due to the rotation of the toner transport roller 304 during use, electrostatic force, and other effects, the rotationally upstream portion 302b, which is easily deformed, adheres to the peripheral surface 304a of the toner transport roller 304 to transport the toner. A case such as winding around the roller 304 occurred.

In such a state, the toner particles 308 adhered to the peripheral surface 304 a of the toner transport roller 304 and transported to the through hole 306 are rotated upstream of the peripheral surface 304 a of the toner transport roller 304 and the insulating sheet 302. Unusually high pressure or strong friction between the side portion 302b and the side portion 302b disrupts uniform conveyance of the toner particles 308. When the uniform conveyance of the toner particles 308 is disturbed in this way, the toner particles 308 initially adhered uniformly to the peripheral surface 304a of the toner conveying roller 304.
Until the toner particles 308 are supplied, the density of the toner particles 308 is gradually deviated partially before reaching the through holes 306.
Large differences occur between the two. For this reason, there has been a problem in that the print density becomes uneven and the print quality is reduced.

[0009] It is an object of the present invention to prevent the rotation upstream portion of the insulating sheet from being wound around the peripheral surface of the charged material conveying roller in the image forming unit as described above, and to maintain good print quality. Is what you do.

[0010]

The image forming unit according to the present invention is characterized in that the rigidity of the insulating sheet in the portion on the upstream side of the rotation of the charged material conveying roller is higher than the position of the through hole. In this way, by increasing the rigidity, the shape of the insulating sheet during use is kept to a minimum,
The phenomenon of sticking or winding around the peripheral surface of the charged material transport roller can be prevented. As a result, the insulating sheet in the upstream rotation portion is always in a stable state, so that the charged body is not abnormally strongly pressed between the peripheral surface of the charged material transporting roller and the insulating sheet in the upstream rotation portion. The uniform supply of the body is not disturbed. Therefore, the charged material can be uniformly supplied to each through hole without bias, and good print quality can be maintained.

[0011] Examples of the charged body include toners used in printers and copiers. As a method to increase the rigidity of the insulation sheet on the upstream side of rotation,
For example, this can be realized by making the thickness of the insulating sheet in the portion on the rotation upstream side at least larger than the thickness of the insulating sheet in the portion around the through hole. Alternatively, it can be realized by attaching a reinforcing member to the insulating sheet on the rotation upstream side portion.

[0012] In this case, the rigidity of the insulating sheet at a position away from the through hole position by a distance corresponding to about 5% to about 15% of the diameter of the charged material transport roller toward the rotation upstream side of the charged material transport roller is increased. Preferably, it is increased. This is because in the part where the rigidity of the insulating sheet suddenly changes, the shape of the insulating sheet tends to have a step, but if the insulating sheet has a step near the through hole, uneven transfer of the charged body is likely to occur. This is to prevent from occurring.

As the reinforcing member, a single member may be used, or a part of a holder for fixing the insulating sheet may be modified and used as a reinforcing member. As another method of increasing the rigidity of the insulating sheet in the rotation upstream portion, the control electrode may be formed by extending the control electrode to the rotation upstream portion. In this case, in order to prevent the influence of the above-mentioned step, the length of the charged material transporting roller is about 5% to about 15% or more of the diameter of the charged material transporting roller from the position of the through hole. It is preferable to extend the control electrode to a position away from the control electrode. In this case, even if the control electrodes are formed in the same shape and extended to the rotation upstream side portion, since the interval between the control electrodes is very narrow, the distribution of the rigidity that affects the uniform conveyance of the charged body is obtained. The difference does not occur in the insulating sheet. However, in order to make the distribution of rigidity uniform even a little, the width of the extended control electrodes may be increased and the interval between the control electrodes may be reduced.

The extent to which the rigidity is increased depends on the design of the image forming unit and the image forming apparatus used.
For example, the longitudinal elastic modulus is increased by about 6 to 8 times the longitudinal elastic modulus of the insulating sheet around the through hole or on the downstream side of the rotation. In the case of a conventional film made of a polyimide resin of 25 μm, in terms of the longitudinal elastic modulus, about 700 to about 800 kg at a peripheral portion of a through hole or a downstream portion of rotation.
/ Mm ² and a insulating sheet, by the order of about 5000 kg / mm ^2, it is possible to obtain a necessary rigidity.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 is a sectional view showing a schematic configuration of an image forming unit 2 to which the above-mentioned invention is applied.

The image forming unit 2 is a unit in which a toner supply unit 4 as a charged body supply mechanism and an aperture electrode body 8 attached to an aperture holder 6 are unitized. The toner supply unit 4 includes a toner case 10
And a toner container 12 formed by a space inside the toner case 10, a toner supply roller 14, a toner transport roller 16, a toner stirring blade 18, and a toner regulating blade 20.

Toner case 10 made of metal or synthetic resin
Is formed in the main scanning direction (perpendicular to the plane of FIG. 1) so as to be several cm wider than the maximum width of the recording paper as an image recording medium. A toner supply roller 14 having a length equal to or longer than the maximum width of the recording paper, a toner conveying roller 16, a toner stirring blade 18, and a toner regulating blade 20 are incorporated therein.

The toner supply roller 14 is a cylindrical roller member made of a silicone foam, and is rotatably supported via its support shaft. This toner supply roller 1
Reference numeral 4 denotes a part of the cylindrical surface that is exposed to a toner storage part 12 partitioned by a regulating part 22 described later, contacts the toner transport roller 16, and is driven by a roller driving mechanism (not shown). And is rotated in the direction of the arrow in FIG. Then, the toner 24 as a charged body is frictionally charged to a negative polarity between the toner supply roller 14 and the toner transport roller 16 that slide in contact with each other, and is supplied to the surface of the toner transport roller 16.

On the right side of the toner storage section 12 in FIG. 1, the supply amount of the toner 24 to the toner supply roller 14 and the toner transport roller 16 is regulated, and at the same time, it functions as a partition between the toner storage section 12 and the toner supply section. The regulating portion 22 is arranged so as to approach or contact the peripheral surface of the toner supply roller 14.

The toner transport roller 16 is formed by covering the entire outer peripheral surface of a metal roller support member with a semiconductive layer or coating, and is rotatably supported via the support shaft while driving the roller. It is connected to a mechanism (not shown) and is driven to rotate in the direction of the arrow in synchronization with the toner supply roller 14.

As described above, the toner transport roller 16
Negatively charged toner 24 adhered in a layer on the peripheral surface of
Is regulated to have a predetermined layer thickness (about 40 to 50 μm) by a toner regulating blade 20 made of an insulating material. The toner stirring blade 18 is rotationally driven at a lower speed than the toner supply roller 14 or the like by a roller driving mechanism (not shown), and moves the toner 24 from the toner storage unit 12 toward the toner supply roller 14 little by little.

At the upper end of the toner case 10, a toner cassette 26 made of synthetic resin for replenishing the toner container 12 with the toner 24 is detachably mounted. Here, an aperture holder 6 and an aperture electrode body 8 as an electrode array which is held while being stretched over the aperture holder 6
Will be described with reference to FIGS. 2, 3, and 4. FIG.

The aperture electrode body 8 is made of a synthetic resin (for example,
An insulating sheet 28 made of polyimide resin) having a thickness of about 25 μm; a plurality of through holes 30 formed in the insulating sheet 28 as fine passage portions; and the through holes 30 adjacent to each other on the surface of the insulating sheet 28. A large number of control electrodes 32 formed therebetween, a large number of conductors 34 provided continuously on the surface of the insulating sheet 28 with the control electrode 32, and a control unit for protecting the large number of control electrodes 32 and the conductors 34. Insulating coating (not shown) covering the surfaces of the electrodes 32 and the conductive wires 34
And an antistatic coating (not shown) covering the surface of the insulating coating.

Each through hole 30 has a width W = 100 μ, for example.
m, and a length L = 100 μm, and is formed in a row in a direction orthogonal to the recording paper conveyance direction. A pitch between the through holes 30 is, for example, about 127 μm, and is A4 size. In the case of using the recording paper of
, That is, the number of control electrodes 32 is about 1700.

Since a large number of control electrodes 32 and conductive wires 34 are formed by etching a metal copper layer on the insulating sheet 28, a predetermined voltage for image formation is applied to these control electrodes 32. The driving integrated circuit 36 is mounted on the surface of the insulating sheet 28 and near the end of the insulating sheet 28 as shown in FIG.
Each of the output terminals 6 is connected to each of a number of conducting wires 34. FIG. 2 shows a case where all the conductors 34 are grouped into 19 groups, and 19 driving integrated circuits 36 are connected to these groups and connected. In FIG. 2, each through-hole 30, each control electrode 32, and each conductive wire 34 are drawn integrally because they are fine.

3, the rigidity of the rotation upstream portion 28a of the toner conveying roller 16 from the through hole 30 is smaller than the rigidity of the rotation downstream portion 28b. In order to increase the thickness, the thickness T2 of the rotation upstream portion 28a is made larger (T1 <T2) than the thickness T1 of the rotation downstream portion 28b. Specifically, for example, T1 = 25 μm, T2 =
It is set to 50 μm.

Further, the aperture electrode body 8 is fixed to the aperture holder 6 by a method such as adhesion so that a predetermined tension is uniformly and uniformly applied. The aperture holder 6 is made of iron or a synthetic resin, and has an upper surface in FIG.
8 and 40 to form a frame structure for fixing the aperture electrode body 8. Then, the aperture electrode body 8 is arranged so that the row of the through holes 30 is arranged near the center of the frame structure in the sub-scanning direction (perpendicular to the main scanning direction and the same as the recording paper conveyance direction). It is adhesively fixed to the aperture holder 6.

Rotation center holes 42 and 44 are provided at both ends of the aperture holder 6 in the main scanning direction. Rotation center pins (not shown) as a pair of mounting pins are inserted into the rotation center holes 42 and 44 from both sides, thereby maintaining a predetermined positional relationship integrally with the toner supply unit 4. It has become possible.

As described above, in the present embodiment, by increasing the rigidity of the rotation upstream portion 28a of the insulating sheet 28, which has conventionally been a problem of winding around the toner transport roller 16, the peripheral surface of the toner transport roller 16 Sticking,
A phenomenon such as winding can be prevented.

Therefore, the toner particles 24a are not abnormally strongly pressed between the peripheral surface 16a of the toner conveying roller 16 and the rotation upstream portion 28a of the insulating sheet 28.
Since the insulating sheet 28 of the rotation upstream side portion 28a is always in a stable state, the uniform supply of the toner 24 is not disturbed. Accordingly, the toner 24 is not biased, and good print quality can be maintained.

As shown in FIG. 4, here, the distance D1 from the through hole 30 to the boundary where the rigidity of the rotation upstream portion 28a becomes high is equal to the diameter R1 of the toner conveying roller 16.
Therefore, the rigidity of the insulating sheet 28 does not suddenly change with respect to the through hole 30 within a distance that adversely affects the conveyance of the toner 24, and uneven conveyance of the toner 24 is prevented. It can be prevented before it happens.

[Second Embodiment] FIGS. 5 and 6 show an example of an aperture electrode body 58 of the present embodiment. The difference between the aperture electrode body 58 and the aperture electrode body 8 of the first embodiment is that the thickness of the rotation upstream portion 78a and the rotation downstream portion 78b of the insulating sheet 78 is the same as the conventional one. However, the point is that the reinforcing member 95 is fixed to the rotation upstream side portion 78a on the surface opposite to the toner conveying roller 66 with an adhesive.

As described above, since the reinforcing member 95 is provided on the surface of the rotation upstream portion 78a, the insulating sheet 78 is provided.
The rotation upstream side portion 78a has sufficient rigidity, and the phenomenon of sticking or winding around the peripheral surface of the toner conveying roller 66 can be prevented. Therefore, the same effect as in the first embodiment can be obtained.

The reinforcing member 95 may be made of metal or plastics. The thickness T3 of the reinforcing member 95 is such that the recording paper 77 receiving the toner particles 74a flying from each through hole 80 is located at a position about 500 μm above the insulating sheet 78. , It suffices that T3 <about 500 μm.
The thickness given to the rotation upstream portion 78a of the insulating sheet 78 can be given.

In the present embodiment, the reinforcing member 95 is attached to the surface of the insulating sheet 78 opposite to the toner conveying roller 66 with respect to the rotation upstream portion 78a, but must contact the toner conveying roller 66. For example, it may be attached to the surface on the toner conveying roller 66 side.

[Third Embodiment] FIG. 7 shows an example of the aperture electrode body 108 according to the present embodiment. This aperture electrode body 1
08 differs from the aperture electrode body 8 of the first embodiment in that
The rotation upstream portion 128a and the rotation downstream portion 128b of the insulating sheet 128 have the same thickness as the conventional one, but the rotation upstream portion 128a has a surface opposite to the toner conveying roller. Aperture holder 10
6 is that the back side of the flange portion 138 is adhered.
Also, on the surface opposite to the toner transport roller,
Another flange 140 of the aperture holder 106
Is that the back surface is bonded. The flange 1
An elongated hole 129 in the main scanning direction is located immediately below the corner 140a of the forty.
Are formed, and the aperture electrode body 108
And the flange portions 138, 14
0 is adhered to the back surface.

Of the two flange portions 138 and 140 of the aperture holder 106, the flange portion 138 on the upstream side of the rotation of the toner conveying roller is formed wider than in the first embodiment, and is insulated over a sufficient width. The rigidity of the rotation upstream portion 128a of the seat 128 is increased.

Therefore, the flange portion 138 functions as a reinforcing member, and the same effects as those of the first embodiment are produced. [Embodiment 4] Aperture electrode body 158 of the present embodiment.
8 and 9 are shown in FIGS. This aperture electrode body 15
8 is different from the aperture electrode body 8 of the first embodiment in that the rotation upstream portion 178a and the rotation downstream portion 178b of the insulating sheet 178 have the same thickness as the conventional one, On the rotation upstream portion 178a of the transport roller 166, a conducting wire 184 from the driving integrated circuit 186 of the rotation downstream portion 178b of the insulating sheet 178 is provided.
The point is that the extension part 185 is further extended than the control electrode 182 portion.

The extension 185 is formed at the same time when the conductive wire 184 and the control electrode 182 are formed by etching. Since the extension 185 is formed of a metal layer, the rigidity of the rotation upstream portion 178a can be increased. Therefore, the same effect as in the first embodiment is obtained.

The extension portion 185 is formed by the structure shown in FIG.
Similarly to the case shown in FIG. 7, since it is an extension of the many conductive wires 184 extending from the driving integrated circuit 186 and the control electrode 182 which is the tip of the conductive wire 184, the wires are divided into many wires and are not integrated. However, since the distance between them is narrow, uniform rigidity can be given to the rotation upstream portion 178a, and the toner particles 174a are not biased.

Here, the distance D2 from the through hole 180 to the tip of the extension 185 is equal to the diameter R of the toner conveying roller 166.
It is set at about 5 to about 15% of 2. Therefore, the rigidity of the insulating sheet 178 does not change abruptly in the vicinity of the through hole 180, and uneven conveyance of the toner particles 174a can be prevented.

[Others] In the first embodiment, the rotational upstream portion 28a of the insulating sheet 28 is formed thick, but the material of the rotational upstream portion 28a of the insulating sheet 28 may be changed or processed to have high rigidity. Thereby, the rigidity of the rotation upstream portion 28a may be increased to achieve the above-described effect. For example, a crosslinking agent may be blended into the insulating sheet 28, and ultraviolet rays or radiation may be applied only to the rotation upstream portion 28a to cause a crosslinking reaction, thereby increasing the rigidity of the rotation upstream portion 28a.

In the fourth embodiment, a large number of conductors 184 and the control electrode 182 which is a tip portion thereof are extended to the rotation upstream portion 178a, so that the rotation upstream portion 178a is extended.
8a has been increased in rigidity, but the conductor 184 and the control electrode 18
The rigidity of the rotation upstream portion 178a may be increased by integrally forming the metal layer separated from the rotation layer 2 with the rotation upstream portion 178a.

In each of the embodiments described above, a toner is used as the charged body, but a liquid toner may be used as the charged body.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming unit according to a first embodiment.

FIG. 2 is a perspective view of an aperture holder and an aperture electrode body according to the first embodiment.

FIG. 3 is a partially enlarged perspective view of an aperture electrode body according to the first embodiment.

FIG. 4 is an explanatory diagram illustrating a positional relationship between an aperture electrode body and a toner transport roller according to the first embodiment;

FIG. 5 is a perspective view of an aperture electrode body according to a second embodiment.

FIG. 6 is an explanatory diagram of a positional relationship between an aperture electrode body and a toner conveying roller according to a second embodiment.

FIG. 7 is a perspective view of an aperture holder and an aperture electrode body according to a third embodiment.

FIG. 8 is a perspective view of an aperture electrode body according to a fourth embodiment.

FIG. 9 is a diagram illustrating an arrangement relationship between an aperture electrode body and a toner transport roller according to a fourth embodiment.

FIG. 10 is an explanatory diagram illustrating a positional relationship between an aperture electrode body and a toner transport roller according to a conventional example.

FIG. 11 is a perspective view of a conventional aperture electrode body.

[Explanation of symbols]

2. Image forming unit 4. Toner supply unit 6. Aperture holder 8. Aperture electrode body 10. Toner case 12. Toner storage unit 14.
Toner supply roller 16: Toner transport roller 16a: Peripheral surface 18:
Toner stirring blade 20: toner regulating blade 22: regulating section 24:
Toner 24a: toner particles 26: toner cassette 28
... Insulation sheet 28a ... Rotation upstream side part 28b ... Rotation downstream side part
DESCRIPTION OF SYMBOLS 30 ... Through-hole 32 ... Control electrode 34 ... Conductor 36 ... Driving integrated circuit 38, 40 ... Flange part 42, 44 ... Rotation center hole 58 ... Aperture electrode body 66 ... Toner transport roller 74a ... Toner particles 77 ... Recording paper 78 … Insulation sheet 78a… rotation upstream side part 78b… rotation downstream side part
80 ... through hole 82 ... control electrode 84 ... lead wire 95 ... reinforcing member 106 ... aperture holder 108 ...
Aperture electrode body 128 ... Insulating sheet 128a ... Rotation upstream side part 12
8b: Rotational downstream portion 129: Slot 132: Control electrode 134: Conductor 138, 140 Flange 158: Aperture electrode body 166: Toner transport roller 174a: Toner particles
178: Insulating sheet 178a: Rotation upstream part 178b: Rotation downstream part 180: Through hole 182 ... Control electrode 184 ... Conducting wire 185 ... Extension part 1
86 ... Drive integrated circuit

Claims (7)

[Claims] An insulating sheet for forming a plurality of through-holes in a row in a direction intersecting a conveying direction of the image recording medium; and a row direction of the plurality of through-holes by attaching a charged body to a peripheral surface. A charging member supply mechanism configured to include a charging member transport roller that rotates in an intersecting direction, and to transfer a charging member to a through hole of the insulating sheet by rotation of the charging member transport roller; A control electrode extending from the rotation downstream side of the body transport roller to each of the plurality of through-holes; and an electrode drive circuit for performing voltage control on the control electrode for each of the through-holes; and the electrode drive circuit for the control electrode By controlling the passage of the charged body supplied from the charged body supply mechanism in the through hole by the voltage control, an image is formed on the image recording medium by the charged body passing through the through hole. A forming unit than said through-hole positions, the image forming unit, characterized in that an increased rigidity of the insulating sheet of rotating upstream portion of the charged member transport rollers. 2. The rigidity of the insulating sheet on the upstream rotation side portion is increased by making the thickness of the insulating sheet on the upstream rotation side portion at least larger than the thickness of the insulating sheet around the through hole. The image forming unit according to claim 1, wherein: 3. The image forming unit according to claim 1, wherein the rigidity of the rotation upstream side portion is increased by attaching a reinforcing member to the insulating sheet of the rotation upstream side portion. 4. A distance corresponding to about 5% to about 15% of a diameter of the charged material transporting roller from a position of the through hole,
3. The rigidity of the insulating sheet at a position away from the charged material transporting roller toward a rotation upstream side is increased.
Or the image forming unit according to 3. 5. The image forming unit according to claim 1, wherein the rigidity of the rotation upstream portion is increased by extending the control electrode to the rotation upstream portion. 6. The control electrode is moved from the position of the through hole to a position at least about 5% to about 15% of the diameter of the charged material transport roller and away from the charged material transport roller to the rotation upstream side of the charged material transport roller. 6. The image forming unit according to claim 5, wherein the image forming unit is extended. 7. The image forming unit according to claim 1, wherein said charged body is a toner.