JPH02209263A - image forming head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an image forming head used for image forming in an electrostatic image forming apparatus.

The present invention particularly relates to an image forming head that is used with electrodes in contact with an image forming member.

The present invention is particularly applicable to Japanese Patent Publication No. 55-30228 and Japanese Patent Application No. 63-3028.
The present invention relates to an image forming head that forms images by injecting charges from electrodes used in image forming apparatuses such as No. 11923.

[Prior Art] A first example of a conventional image forming head using charge injection from an electrode is a needle-like conductor made of an insulating resin as shown in Japanese Patent Publication No. 43746/1983. In the second example, a conductive film is formed by printing on an insulating planar substrate, or a conductive thin film is formed by a vacuum thin film forming method such as vacuum sputtering. It had a structure in which the electrodes were formed by etching.

[Problems to be Solved by the Invention] However, with the first conventional technology, it is difficult to achieve high resolution due to the size limitations of the needle electrodes, and high resolution cannot be achieved unless they are arranged in multiple rows. The wiring technology is also complicated, making it very expensive.

Further, as shown in Japanese Patent Publication No. 63-43746, the charge latent image is likely to be disturbed due to the occurrence of frictional electrification with the image forming member at the end face portion other than the electrode.

In addition, in the second conventional technology, although it is easy to increase the resolution of the electrode, it is difficult to ensure stable contact with the image forming member with a relatively low pressure, resulting in warping of the substrate and the possibility of the image forming head being attached to the image forming member. Image quality easily deteriorates due to fluctuations in pressure, etc. This problem is especially true when the image forming member is a flexible film such as PET film, PPS film, polyimide film, or aramid film, and the image quality is mainly affected by film tension. This poses a major problem when attempting to ensure contact between the forming head and the image forming member. In other words, if the tension is increased, wrinkles will easily occur in the film even though sufficient contact with the film cannot be ensured, making it impossible to ensure stable contact.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and more specifically, to provide an image forming head with an improved structure at the tip end.

[Means for Solving the Problems] In order to solve the above problems, the image forming head of the present invention has the following features:
At least an insulating substrate, a plurality of mutually separated electrodes formed on the insulating substrate, and a circuit that independently applies a voltage to each of the plurality of electrodes as a component,
A plurality of convex portions are formed on the substrate at the tip of the substrate, the electrode is formed correspondingly on each of the convex portions, and the convex portion contacts the image forming member. do.

As the insulating substrate, ceramic, glass, resin, ceramic particle dispersed resin, or a substrate in which an insulating resin (eg, polyimide resin) is coated on a conductive substrate (eg, metal) can be used. Specific materials include forsterite, borosilicate glass, glass-filled epoxy resin, and polyimide coated stainless steel substrate.

The electrode material is not particularly limited as long as it is a conductive material with good sliding wear resistance and electric field wear resistance.

For example, titanium metal, titanium alloy, molybdenum metal, molybdenum alloy, tungsten metal, tungsten alloy, chromium metal, chromium alloy, tantalum metal, tantalum alloy, etc. are recommended.

There is no particular restriction on the convex part as long as it is made of an insulating material, for example, 5
It may be formed with a dielectric film such as iCh, A102, or SiN, a glaze layer made of glass, or an organic insulating film such as polyimide or photosensitive resist.

[Function] In the image forming head configured as described above, only the electrodes protrude when viewed from the image forming member, and as a result, the pressure of the electrodes against the image forming member is effectively increased.
The contact state between the image forming member and the electrode becomes better. Further, since the area in which constituent materials other than the electrodes of the image forming head come into contact with the image forming member can be reduced, unnecessary frictional electrification can be prevented and image disturbance can be minimized. Furthermore, since the present invention can effectively utilize thin film technology, it is easy to increase the resolution and reduce costs.

Hereinafter, the details of the present invention will be shown by examples.

[Example] Example 1 FIG. 1 and FIG. 2 show an example of the image forming head of the present invention. Figure 1 is a schematic diagram of the head viewed from the top of the board, Figure 2
The figure is an enlarged view showing the structure of the tip of the head taken along the line a-a' in FIG. 1. A method of manufacturing the head tip will be described below. First, a photoresist is coated on a substrate 1 made of borosilicate glass and patterned so as to remain at the electrode position at the tip of the head, and then baked at a high temperature to smooth the pattern periphery to form a convex pattern 9. The sloping of the periphery of the convex pattern causes an inclined portion in the convex pattern. The angle of inclination of the inclined part with respect to the substrate is the baking temperature of high temperature baking,
This is possible by controlling the baking time. The appropriate angle of inclination with respect to the substrate is 20 degrees to 45 degrees. The height of the obtained convex pattern 9 is about 10 microns to 100 microns. After that, an insulating hard film 10 such as a SiO2 film or a SiN film is formed by sputtering or CV.
Form by method D. The thickness of the hard film 10 is approximately 1 to 3 microns. A conductive film of chromium metal is patterned by photoetching so that electrodes 2 are formed corresponding to each of the protrusions 3 thus obtained, and the tips of the obtained electrodes are formed on the protrusions 3.

The chromium metal film was created by vacuum sputtering and had a thickness of 1 to 4 microns. Thereafter, an insulating protective film 4 is formed on the substrate except for the portion where the convex electrode contacts the image forming member. In order to maintain good contact between the electrode and the image forming member at all times, the protective film material is 5i02, borosilicate glass, polyimide film, etc., and is preferably a film that wears more easily than the electrode material. Not only is it useful for preventing electrical leakage at high temperatures, but it also serves to define the area of the electrode in contact with the imaging member.

That is, the protective film 4 is not formed on the electrode portion that contacts the image forming member, and only the electrode portion on which the protective film is not formed can come into contact with the image forming member. A part of the electrode portion of the sloped portion of the convex portion 3 on the front end side of the image forming head is not protected by the protective film 4 . This allows the head to be positioned at an angle with respect to the imaging member.

In addition to this, since the protrusions are formed separately for each electrode, only the electrodes can be made to protrude when viewed from the image forming member, making it possible to easily apply pressure to the image forming member. enable contact. Further, since it is possible to minimize the contact of parts other than the electrode portions with the image forming member, image disturbance can be minimized.

The electrode 2 is connected to the IC driver 6 on the circuit board 5 through the connection 7.
0 image signal connected to, power for driver operation,
The voltage for applying the electrodes is sent from the outside to the IC driver 6 through the connector 8. In this embodiment, the head is composed of two boards, a board 1 and a circuit board 5 on which the IC driver is mounted. This is a measure to reduce the area of the substrate 1 that requires etching, increase manufacturing efficiency, and realize cost reduction. There is no problem even if the electrode portion and the IC driver are arranged on the same substrate, and a portion of the driver may be formed on the same substrate as the electrode portion using thin film transistor technology. The tip of the electrode on the substrate 1 is polished to have a smooth end face, making it difficult to damage the image forming member.

In order to observe the difference in image formation between the head with the protrusions of the present invention and the conventional head without the protrusions, the third
Images were compared using the image forming apparatus shown in the figure. Third
The image forming apparatus shown in the figure uses PET as the image forming member 14.
Using a film, a charge image is formed on one side of the PET film by an image forming device 11, and at the same time, a conductive toner 13 is formed by a developing device 12 placed on the other side of the PET film.
is conveyed to the image forming member 14 and developed with conductive toner to visualize it. After this development, the developed toner 17 on the PET film is fixed and the image is fixed. Of course, it is also possible to obtain an image by transferring and fixing it to another recording member, and the image forming apparatus shown in this example is only one example to which the image forming head of the present invention is applied. The inventor evaluated the effect of the convex portions by comparing toner images after development. In images produced by heads that do not form convex portions, significant toner scattering is observed at the edges of the images, whereas in images produced by heads that form convex portions, the degree of toner scattering is slight. With the head that does not form protrusions, clear density unevenness was observed in the images obtained even when the tension of the PET film was increased, whereas with the head that formed the protrusions, no obvious image density unevenness was observed. Sufficiently uniform image quality was obtained over the entire image forming area.

Further, when an image forming experiment was conducted using a head having continuous convex portions without separating the convex portions for each electrode, uniformity of image density could be ensured, but the image was particularly disturbed at the edges.

Further, since the image head of the present invention makes surface contact with the image forming member rather than line contact or point contact, the wear rate of the electrodes can be greatly reduced.

Embodiment 2 FIG. 4 shows another embodiment of the image forming head of the present invention.
FIG. 4 is a sectional view of the tip of the image forming head viewed from the side. In this embodiment, a convex portion is further formed partially on the convex portion, an electrode is formed on the partial convex portion 11, and a protective film is formed on a portion outside the partial convex portion. The height of the partial convex portion is adjusted so that the electrode protrudes from the surface of the protective film. By doing this, the contact between the electrode and the image-forming body is better, and the disturbance of the written image is reduced, resulting in higher image quality. Various methods can be used to form the 0-part molar part. As an example, after forming the protective film 5 in Example 1, a film of partially convex material is formed and etched. The partially convex material may be an insulator or a conductor.

The height of the 0-part mortar, which may be made of the same material as the electrode, ie, the film thickness of the partial convex part, is effective if it is 4 to 5 microns or more, and is preferably 10 microns or more.

[Effects of the Invention] As described above, the image forming head of the present invention can stabilize the contact with the image forming member and prevent unnecessary charging, so it can greatly contribute to improving image quality. In particular, the image forming head of the present invention can form high-quality images on flexible films with low tension, so it can be used in image forming devices such as new electrostatic printers and other devices that require image output, such as fax machines and word processors. Furthermore, it is possible to apply it to image displays using toner, and the field of application is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the image forming head of the present invention. FIG. 2 is a sectional view of the tip of the image forming head taken along line aa' in FIG. 1. Third drawing: A configuration diagram of an image forming apparatus used for image formation quality evaluation. FIG. 4 is a sectional view of the head tip of another embodiment of the image forming head of the present invention. 1...Substrate 2...Electrode 3...Protrusion 4...Protective film 5...Circuit board 6...IC driver 7...Wire connection 8 ・Connector convex pattern Insulating hard film Image forming head Developing device Conductive Toner image forming member fixing device Moving direction of image forming member Developed toner fixed toner portion Convex portion Figure 1 and above Applicant Seiko Epson Corporation Agent Patent attorney Kizobe Suzuki (1st name) Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an image forming head that includes at least an insulating substrate, a plurality of mutually separated electrodes formed on the insulating substrate, and a circuit that applies a voltage independently to each of the plurality of electrodes as a component. , a plurality of convex portions are formed on the substrate at the tip of the substrate, the electrode is formed correspondingly on each of the convex portions, and the convex portion contacts the image forming member. image forming head.