JP3332300B2 - Image forming device - Google Patents

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 for forming an image by controlling the amount of toner passing through a plurality of openings formed in a thin film-shaped aperture electrode body. The present invention relates to an image forming apparatus which can be mounted in a flat shape without "."

[0002]

2. Description of the Related Art A thin film-shaped aperture electrode body in which a large number of openings (apertures) are arranged in a row is used. The potential applied to the electrodes provided in the openings is controlled to pass through the openings. Various image forming apparatuses have been proposed in which recording is performed by attaching toner to a recording medium.

[0003] The present applicant has proposed the image forming apparatus in Japanese Application flat No. 6-32121. In this image forming apparatus, as shown in FIG. 9, a large number of minute openings (apertures) 16 are arranged at minute intervals in a direction orthogonal to the conveying direction of the recording medium 40 (indicated by C in the figure). In a row. The thin film-shaped aperture electrode body 10 in which the control electrode 14 is arranged around each of the large number of apertures 16 is attached to the rectangular fixed frame 20 at the support portions 10a and 10b at both ends parallel to the plurality of apertures 16. Fix each. By attaching the fixing frame 20 to the upper end of the toner case 31, a pair of upwardly projecting ridges (interposers) 26 and 27 formed integrally with the toner case 31 allow the aperture electrode body 10 to A uniform tension is applied to the aperture electrode body 10 so as to be supported between the plurality of apertures 16 and the support portions 10a and 10b. In this state, the toner carrying roller 34 of the toner supply mechanism is rotated while being brought into contact with the lower side to supply the toner to the large number of apertures 16 and individually control the potential applied to each control electrode 14. The amount of toner passing through the aperture 16 is controlled, and the passed toner is attached to the recording medium 40. Thereafter, the image is fixed by a fixing mechanism (not shown) to form an image.

In this image forming apparatus, a fixing frame 20 for fixing the aperture electrode body 10 is attached to a toner case 31.
When attaching to the upper end of the
By applying tension by the pair of first and second interposers 26 and 27, "wrinkles" are not applied to the aperture electrode body 10, and a uniform tension is applied to the whole.

[0005]

However, even with the above configuration, the first and second interposers 26 and 27 are required to attach the aperture electrode body to the toner supply mechanism.
However, when the aperture electrode body 10 is placed, "wrinkles" are easily formed, and it is difficult to make the tension uniform over the entirety of the aperture electrode body 10. For this reason, the contact state between the aperture electrode body 10 and the toner carrying roller 34 is deteriorated, and the aperture 16 is inclined in a portion having “wrinkles” or a portion where the tension is not uniform, and the amount of movement of the toner is reduced. Or the movement direction of the toner changes,
There is a problem that an image having density unevenness and distortion is recorded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to enable a thin film-shaped aperture electrode body to be accurately attached to a flat surface without "wrinkles". Another object of the present invention is to provide an image forming apparatus capable of forming a beautiful image without distortion.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising a sheet-like member having flexibility, and a plurality of openings are formed in a row in a direction perpendicular to a conveying direction of a recording medium. Aperture electrode body having an electrode at each of the plurality of openings, a toner supply mechanism for supplying toner to the aperture of the aperture electrode body, and a potential applied to each electrode of the aperture electrode body, respectively. A toner controlling means for controlling an amount of toner passing through each opening, and forming an image by attaching the toner passing through the opening to a recording medium, wherein an arrangement direction of the plurality of openings is provided. A pair of support portions, both ends of which are fixed in parallel with the aperture electrode body, and a support portion for applying tension to the aperture electrode body, and a uniform tension applied to the aperture electrode body. , Multiple openings In between the support portions, a protrusion for supporting the aperture electrode from the toner supply mechanism side,
Arrangement direction with substantially parallel to the arrangement of the opening, the bay
A ridge having a curved shape projecting in the direction of the music with respect to the recording medium direction.

According to a second aspect of the present invention, in the first aspect of the present invention, the projection is formed in a curved shape such that an end side of the ridge in the arrangement direction of the plurality of openings is close to the support. Consisting of

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a contact portion of the ridge with the aperture electrode body is formed to have a substantially rectangular cross section.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, a contact portion of the ridge with the aperture electrode body is formed to have a substantially circular cross section.

[0011]

In the image forming apparatus according to the first aspect, tension is applied to the aperture electrode body from the support portion, so that when the aperture electrode body is pressed against the ridge, the ridge is formed. The force to push back works. At the contact portion between the sheet-shaped member and the ridge, the ridge is formed in a curved shape, so that the force to push back is decomposed into a force in a normal direction of the curved surface of the ridge and a force in a tangential direction. Is done. This tangential component acts in a direction to prevent wrinkling of the aperture electrode body. Further, in order to attach the aperture electrode body to the toner supply mechanism, when placing the aperture electrode body on the ridge formed in a curved shape, since the aperture electrode body comes in contact sequentially from the most protruding central portion to the end portion, It is hard to wrinkle. Therefore, a uniform tension can be applied to the entire aperture electrode body, and the toner can be uniformly supplied to each opening, and a clear image without density unevenness or distortion can be formed.

Here, the image forming apparatus according to claim 2 is
Since the side edge of the ridge is curved so as to be close to the support portion, when the aperture electrode body is fixed, the tension on the end side in the arrangement direction of the aperture electrode body, which tends to be particularly loose, is large. That is, a uniform tension can be applied to the entire aperture electrode body. For this reason, the toner can be evenly supplied to each opening, and distortion of an image on the end side of the opening can be prevented.

[0013] In the image forming apparatus according to the third aspect,
Since the contact portion of the ridge with the aperture electrode body is formed in a substantially rectangular cross section, once the aperture electrode body is fixed, it does not slip, and the uniform tension when attached is permanently reduced. Can be kept.

[0014] In the image forming apparatus according to the fourth aspect,
Since the contact portion of the projection with the aperture electrode body is formed in a substantially circular cross section, the aperture electrode body is slid over the projection to clean the opening of the aperture electrode body. Also when moving a part to a cleaning device, it becomes possible to move smoothly.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings. FIG. 1 shows an image forming apparatus according to a first embodiment of the present invention. In the image forming apparatus, a toner supply device 30 is provided on the right side, and an aperture electrode body 10 for controlling toner flow is provided on the left side of the toner supply device 30. On the left side of the aperture electrode body 10, a back electrode plate 42 is provided so as to maintain a distance of 1 mm from the aperture electrode body 10. The image recording medium 40 is transported in the direction of arrow C by the rotation of the transport roller 69 in the direction of arrow D in the gap between the aperture electrode body 10 and the back electrode plate 42. An image is formed on the image recording medium 40 with the toner 36 as described later. Further, the image recording medium 40
A fixing device 46 for fixing an image to the image recording medium 40 is provided in the conveyance direction of the image recording medium 40. The fixing device 46 is a heat fixing type, and includes a pressure roller 46a having a surface layer of silicon rubber and a heat roller 46b having a halogen heater inside.

Next, each part of the image forming apparatus will be described in detail with reference to FIG. The toner supply device 30 includes:
A toner case 31 also serving as a housing of the entire toner supply device 30 is provided. In the toner case 31, toner 36 is stored, and the toner 36 is stirred by a toner stirring rod 37. Further, a cylindrical toner carrying roller 34 that carries the toner 36 and conveys it to the aperture electrode body 10 is supported in the toner case 31 so as to be rotatable in the direction of arrow B. In FIG. 1, a toner 36 stored in the toner case 31 is provided diagonally below and to the right of the toner carrying roller 34.
The supply roller 32 and the toner carrying roller 34 are arranged in parallel with each other, and contact the generatrix of the cylindrical surface.

In the toner case 31, above the carrying roller 34, the amount of toner 36 carried by the toner carrying roller 34 is adjusted so as to be uniform on the roller surface of the toner carrying roller 34. A toner layer regulating blade 38 for uniformly charging the toner 36 is provided, and one end of the toner layer regulating blade 38 is pressed against the toner carrying roller 34.

Next, the aperture electrode body 10 will be described in detail with reference to the drawings. The aperture electrode body 10 includes:
As shown in FIG. 2, the insulating sheet 12 is composed of a polyimide insulating sheet 12 having a thickness of 25 μm. A plurality of apertures 16 having a diameter of 60 μm are printed on the insulating sheet 12 at intervals of about 127 μm, for example, when printing on A4 paper. , About 1700
The aperture electrodes 10 are formed in a line in the longitudinal direction of the aperture electrode body 10. In addition, a thickness of 8 μm is provided around the aperture 16.
An annular control electrode 14 made of copper foil of
Conducting wires 13 formed each time and extending from the control electrode 14 are formed on the insulating sheet 12. These conductors 13 are connected to the control voltage application circuit 68 shown in FIG.

Here, the support structure of the aperture electrode body 10 will be described with reference to FIGS. FIG. 3 is an enlarged sectional view of the aperture electrode body 10 shown in FIG. 1, and FIG.
FIG. 4 is a view on arrow F in FIG. 3. A rear end support portion 10 formed on the downstream side of the aperture electrode body 10 in the image recording medium transport direction.
a is fixed to the rear end of the rectangular fixed frame 20, and the front end support portion 10 b formed on the upstream side is fixed to the front end of the rectangular fixed frame 20. Before attaching the fixing frame 20 to the toner case 31, that is, when the aperture electrode body 10 is hung on the fixing frame 20, the fixing frame 20 applies a predetermined amount of tension to the aperture electrode body 10 by both the support portions 10 a and 10 b. We support in the state that added.

On the other hand, a left end portion of the toner case 31 corresponding to a position between the plurality of apertures 16 of the aperture electrode body 10 and the rear end support portion 10a supports the aperture electrode body 10 from the toner supply device 30 side. One interposer 26 is formed so as to protrude to the side. A second interposer 27 that supports the aperture electrode body 10 from the toner supply device 30 side is provided at the left end of the toner case 31 corresponding to between the plurality of apertures 16 of the aperture electrode body 10 and the front end support portion 10b. It is formed so as to protrude to the side. Figure 5 is a E arrow view of a first interposer 26 in Fig. As shown in FIG. 5, the first and second interposers 2
Reference numerals 6 and 27 are curved so as to protrude in the direction of the image recording medium, and have a radius of curvature of about 1,000 mm.

Here, the assembly of the aperture electrode body 10 to the toner supply device 30 will be described. Fixed frame 20
Is attached to a predetermined position on the left end of the toner case 31 from the left side. At this time, the central part of the aperture electrode body 10 is brought into contact with the toner carrying roller 34, the upper part of the aperture electrode body 10 is brought into contact with the first interposer 26, and the lower part of the aperture electrode body 10 is brought into contact with the second interposer 2.
7 Interposer 2 formed in a curved shape
When the aperture electrode body 10 is brought into contact with the apertures 6, 27, as shown in FIG.
The wrinkles are less likely to come in contact with the edges 26b in order. The upper part of the aperture electrode body 10 is pressed by the first interposer 26 and moves to the left as shown in FIG. 3, and the lower part of the aperture electrode body 10 is pressed by the second interposer 27 and similarly moves to the left. Is done.

At this time, since tension (tension) from the support portions 10a and 10b is applied to the aperture electrode body 10, it is attempted to push back the first interposer 26 at the contact portion P as shown in FIG. Force F works. At the contact portion P between the aperture electrode body 10 and the first interposer 26, since the aperture electrode body 10 is formed in a curved shape, the force F is equal to the force F2 in the normal direction of the curved surface of the interposer 26 and the tangential direction. It is decomposed into a force F1. The tangential component F1 acts in a direction to prevent “wrinkles” of the aperture electrode body 10.

As shown in FIG. 3, the toner carrying roller 34
The leftmost portion of the outer peripheral surface in the figure is located further to the left than the tips ( the left ends in the figure ) of the first and second interposers 26 and 27, so that the aperture electrode body 10 on which the plurality of apertures 16 are arranged. Is moved to the leftmost position in the figure . At this time, as described above, since the first and second interposers 26 and 27 fix the aperture electrode body 10 in a flat shape without wrinkles, each of the plurality of apertures 16 formed on the aperture electrode body 10 has a toner. The toner 36 from the carrying roller 34 can be evenly supplied. Also,
Since the distal end portions 26c and 27c of the first and second interposers 26 and 27 that are in contact with the aperture electrode body 10 are formed in a substantially rectangular cross section, they do not slip once the aperture electrode body 10 is fixed. Uniform tension at the time of attachment can be maintained forever.

Here, the positional relationship between the aperture 16 of the aperture electrode body 10 and the toner carrying roller 34 will be described in detail. As shown in FIG. 3, the center line 77 of each aperture 16 is aligned with the toner carrying roller. The toner carrying roller 34 is disposed so as to pass through the leftmost portion in the figure of the outer peripheral surface of the toner carrying roller 34 and the central axis 78 of the toner carrying roller 34. In this positional relationship, the apertures 16 are arranged uniformly up and down with reference to the leftmost portion of the peripheral surface of the toner carrying roller 34,
The distribution of the toner 36 passing through each aperture 16 can be made uniform throughout the aperture. Aperture 1
6 is parallel to the flying direction of the toner 36,
The toner can stably fly.

Further, as shown in FIG. 3, the aperture electrode body is attached to the toner carrying roller 34 with respect to the aperture 16.
Are pressed so as to bend left and right by the same angle with respect to the center. As a result, the contact area between the aperture electrode body 10 and the toner carrying roller 34 can be increased, and the periphery of the right portion of the aperture 16 can be pressed uniformly up and down. It can be suppressed as much as possible.

Next, a control device of the control electrode 14 will be described. As shown in FIG. 1, a control voltage application circuit 68 is connected between the control electrode 14 and the toner carrying roller 34. The control voltage application circuit 68 is configured to apply a voltage of −30 V or +30 V to the control electrode 14 based on an image signal sent from an image signal receiving unit (not shown). The image signal receiving means (not shown) is connected to an external computer, image reading device, image communication device, or the like.

Further, a back voltage application circuit 74 is connected between the back electrode plate 42 and the toner carrying roller 34, and the back voltage application circuit 74 is connected to the back electrode plate 4
2, a voltage of +1 kV can be applied.

Next, the operation of the image forming apparatus configured as described above will be described with reference to FIG. When an image signal receiving unit (not shown) receives an image signal from an external device, the supply roller 32 is rotated in the direction of arrow A by a control device (not shown), and the toner 3 stored in the toner case 31 is removed.
6 is conveyed toward the toner carrying roller 34. Then, the transported toner 36 is transferred to the toner carrying roller 34.
And is carried on the toner carrying roller 34 by being negatively charged. The toner 36 carried on the toner carrying roller 34 is conveyed while being carried on the cylindrical roller surface of the toner carrying roller 34 with the rotation of the toner carrying roller 34 in the direction of arrow B, and the toner layer regulating blade 3
After the toner is thinned by 8 and the charge is made uniform, it is conveyed toward the aperture electrode body 10 by the rotation of the toner carrying roller 34 in the direction of arrow B. Then, the toner 36 on the toner carrying roller 34 is
While being rubbed by the zero insulating sheet 12, the sheet is supplied beside the aperture 16. At this time, the first and second interposers 26,
27, the aperture electrode body 10 is given a uniform tension over the entirety.
Makes uniform contact with the surface of the toner carrying roller 34, and the toner 36 is evenly supplied to each aperture 16.

Next, an image forming operation will be described with reference to FIGS.
The description will be continued with reference to FIG. In response to an image signal sent from an image signal receiving means (not shown), the control voltage applying circuit 68 applies +30 to the control electrode 14 corresponding to the image portion.
A voltage of V is applied. As a result, electric force lines from the control electrode 14 to the toner carrying roller 34 are formed in the aperture 16 in the control electrode 14 to which the voltage is applied due to the potential difference between the control electrode 14 and the toner carrying roller 34.
As a result, the negatively charged toner receives an electrostatic force in the direction of higher potential, passes through the aperture 16 from the toner carrying roller 34, and is drawn out to the control electrode 14 side. The extracted toner 36 is applied to the image recording medium 40 by an electric field formed between the image recording medium 40 and the aperture electrode body 10 by the voltage of +1 kV applied to the back electrode plate 42 by the back voltage applying circuit 74. It flies toward and is deposited on the image recording medium 40 to form pixels. At this time,
Since the first and second interposers 26 and 27 apply uniform tension to the entire aperture electrode body 10 and the toner 36 is uniformly supplied to the aperture 16.
Pixels having a uniform density are formed in each aperture 16. Further, a uniform tension is applied to the aperture electrode body 10 so that the aperture 16 does not tilt and the image recording medium 40 is not tilted.
, Pixels are formed at appropriate positions on the image recording medium 40.

On the other hand, the control electrode 14 corresponding to the non-image portion
Is applied with a voltage of -30 V from the control voltage application circuit 68, an electric field is not formed between the toner carrying roller 34 and the control electrode 14, and the toner 36 on the toner carrying roller 34 receives an electrostatic force. Therefore, no pixel is formed on the portion of the image recording medium 40 facing the control electrode 14.

Here, when one line of pixels is formed on the surface of the image recording medium 40 by the toner 36, the image is then conveyed by the conveying roller 69 by one pixel in a direction perpendicular to the aperture line. Then, a toner image is formed on the entire surface of the image recording medium 40 by repeating the above image forming process. Thereafter, the formed toner image is transported to the fixing device 46 by the transport roller 69, and is fixed on the image recording medium 40 by the fixing device 46.

In the image forming apparatus of the first embodiment, since the insulating sheet 12 of the aperture electrode body 10 is directed toward the toner carrying roller 34, the toner 36 exists on the toner carrying roller 34 due to a problem in the toner supply system. If not,
The control electrode 14 and the toner carrying roller 34 do not come into contact with each other and short-circuit electrically, so that the control voltage application circuit 68 is not broken.

Next, an image forming apparatus according to a second embodiment of the present invention will be described with reference to FIGS. The configuration for forming an image in the image forming apparatus of the second embodiment is the same as that of the first embodiment described with reference to FIGS.
Since this embodiment is the same as the embodiment, the same reference numerals are used for the same members, and illustration and description thereof are omitted.

FIG. 6 is an enlarged sectional view of the aperture electrode body 10, and FIG. 7 is a view taken in the direction of arrow G in FIG. The first mentioned above
In the embodiment, the first and second interposers 26 and 27 are formed in parallel to the arrangement direction of the apertures 16 as shown in FIG. 4, but in the second embodiment, as shown in FIG. The end portions 126b and 127b of the first and second interposers 126 and 127 are formed in a curved shape close to the support portions 10a and 10b. Further, as shown in FIG. 3, the first and second interposers 26 and 27 of the first embodiment are used.
Of the first and second interposers 126 and 127 in the second embodiment, as shown in FIG.
c and 127c are formed in a substantially circular cross section.

In the second embodiment, as described above, the end portions 12 of the first and second interposers 126 and 127 are used.
When the aperture electrode body 10 is fixed to the toner case 31, the arrangement direction of the aperture electrode body 10 tends to be particularly loose because the apertures 6b and 127b are formed in a curved shape so as to approach the support portions 10a and 10b. , The tension on the end side increases, and uniform tension can be applied to the entire aperture electrode body 10. For this reason, the toner 36 can be evenly supplied to each of the apertures 16, and distortion and “smearing” of an image at the end of the aperture 16 can be prevented.

In the second embodiment, the distal end portions 126c, 1c of the first and second interposers 126, 127 are provided.
Since the aperture 27c is formed in a substantially circular shape, the aperture 16
When the first and second interposers 12 are removed,
When the aperture electrode body 10 is slid over the upper and lower surfaces 6 and 127 and the aperture 16 is moved to a cleaning device (not shown), the aperture 16 can be moved smoothly.

The present invention is not limited to the embodiments described in detail above, but may be modified without departing from the scope of the invention.
Various changes can be made. For example, in the first embodiment, the tip portions 26c and 27c of the first and second interposers 26 and 27 are formed in a substantially rectangular shape, and in the second embodiment, the tip portions of the first and second interposers 126 and 127 are provided. Although 126c and 127c are formed in a substantially circular shape,
Various shapes can be adopted for the tip shape of the interposer.
For example, it may be formed in a trapezoidal shape as shown in FIG. 8A, or may be formed in a triangular shape as shown in FIG. 8B.

In the first and second embodiments described above, the interposers 26 and 27 are formed integrally with the toner case 31. However, the interposers may be provided separately. In this case, after the fixed frame 20 on which the aperture electrode body 10 is stretched is attached to the toner case 31, the interposer is moved in parallel in the thickness direction of the aperture electrode body 10 (left direction shown in FIG. 1). The body 10 is tensioned. At this time, since the contact is made to the end portion in order from the convex tip portion of the interposer, generation of "wrinkles" can also be prevented by this method.

Further, in the above embodiment, the aperture electrode is used as the toner flow control means. However, for example, a stitched electrode as described in US Pat. No. 5,036,341 may be used. It is.

[0040]

As is apparent from the above description,
In the image forming apparatus according to the first aspect of the present invention, at a contact portion between the aperture electrode body and the protrusion, the protrusion is formed in a curved shape protruding with respect to the recording medium direction. Is applied in a direction to prevent wrinkles of the sheet-like member. Further, in order to attach the aperture electrode body to the toner supply mechanism, when the aperture electrode body is put on the projection formed in a curved shape, the aperture electrode body comes into contact sequentially from the most protruding center portion to the end portion. "Wrinkles" are hard to come by. For this reason,
The aperture electrode body can be accurately mounted on a flat surface without "wrinkles" and uniform tension can be applied to the whole, so that toner can be supplied evenly to each opening and a clear image without density unevenness and distortion can be obtained. It can be formed.

Further, in the image forming apparatus according to the second aspect, since the protruding side end portion is curved so as to be close to the support portion, particularly when the aperture electrode body is fixed, slackness occurs. The tension at the end of the aperture electrode body in the arrangement direction is increased, so that a uniform tension can be applied to the entire aperture electrode body. Therefore, the toner can be uniformly supplied to each of the openings, and it is possible to prevent the image from being distorted particularly at the end of the opening.

Further, in the image forming apparatus according to the third aspect,
Since the contact portion with the projecting aperture electrode body is formed in a substantially rectangular cross section, it is possible to prevent the aperture electrode body from slipping from the projecting shape. Further, in the image forming apparatus according to the fourth aspect, since the contact portion with the projecting aperture electrode body is formed in a substantially circular cross section, the aperture electrode body can slide on the projecting shape. Become.

[Brief description of the drawings]

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

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

FIG. 3 is an enlarged cross-sectional view of the aperture electrode body shown in FIG.

FIG. 4 is a view on arrow F of FIG. 3;

FIG. 5 is a view as seen from an arrow E in FIG. 3;

FIG. 6 is an enlarged sectional view of an aperture electrode body according to a second embodiment.

FIG. 7 is a view on arrow G of FIG. 6;

FIG. 8 is a side view showing a modified example of the tip shape of the interposer of the present invention.

FIG. 9 is a cross-sectional view of an aperture electrode body according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Aperture electrode body 12 Insulating sheet 14 Control electrode 16 Aperture 20 Fixed frame 26 Interposer 27 Interposer 30 Toner supply device

Claims (4)

(57) [Claims] 1. A sheet-like member having flexibility,
A plurality of openings are formed in a row in a direction perpendicular to the transport direction of the recording medium, and an aperture electrode body having an electrode in each of the plurality of openings, and toner is supplied to the openings of the aperture electrode body A toner supply mechanism, and a toner control unit for controlling an amount of toner passing through each opening by controlling a potential applied to each electrode of the aperture electrode body, respectively. An image forming apparatus configured to form an image by adhering a plurality of openings, wherein a pair of support portions to which both ends of the aperture electrode body are fixed are parallel to an arrangement direction of the plurality of openings,
A support section for applying tension to the aperture electrode body; and an aperture electrode body supported from the toner supply mechanism side between the plurality of openings and each support section to apply uniform tension to the aperture electrode body. A ridge, which is arranged substantially parallel to the arrangement direction of the openings, and has a curved direction.
And a projection formed in a curved shape protruding in the direction of the recording medium. 2. The image forming apparatus according to claim 1, wherein an end side of the ridge in the arrangement direction of the plurality of openings is formed in a curved shape so as to approach the support portion. 3. The image forming apparatus according to claim 1, wherein a contact portion of the ridge with the aperture electrode body is formed in a substantially rectangular cross section. 4. The image forming apparatus according to claim 1, wherein a contact portion of the ridge with the aperture electrode body is formed in a substantially circular cross section.