JPH0531948A - Electrostatic recording head - Google Patents

Abstract

PURPOSE:To provide the above electrostatic recording head capable of enhancing the mechanical strength of the conductors formed on a wiring board in high density. CONSTITUTION:Conductors 12 are formed on a wiring board 10 by usual photolithographic technique. As the conductors 12, a copper foil is used and the thickness of each of the conductors is set to 5mum. The part having length of 5mm from each of the leading ends of the conductors 2 is used as a recording electrode 120. The width of the recording electrode 120 is set to 50mum and the width of the conductor 12 excepting the recording electrode 120 is set to about 60mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording head used for an electrostatic plotter or the like.

[0002]

2. Description of the Related Art An electrostatic printer or an electrostatic plotter forms an electrostatic latent image on an electrostatic recording sheet by an electrostatic recording head, visualizes it with toner, and fixes it to print. In electrostatic recording heads used in these devices, a side plate is attached to a wiring board having a large number of conductors (generally copper foil) formed on the front and back surfaces, and the tip is polished and finished. Obtained by

FIG. 3 is a diagram showing a wiring pattern formed on a wiring substrate of a conventional electrostatic recording head. Wiring board 50
Is formed of glass epoxy resin, and a large number of conductors 52 are formed of copper foil on both surfaces of the wiring board 50. The pitch interval of the conductors 52 formed on one surface of the wiring board 50 is set to about 127 μm or the like (200 dpi). The tip of the conductor 52 is used as a recording electrode.

[0004]

By the way, when an electrostatic latent image is formed on an electrostatic recording sheet, a high recording voltage is required,
The reality is that there is no margin in the breakdown voltage of the high voltage IC that drives this high voltage. Therefore, it is necessary to reduce the load on the high voltage IC as much as possible, and the thickness of the conductor 52 is reduced to 5 μm. Moreover, in the above electrostatic recording head, the width of the conductor 52 is narrowed to 50 μm in order to improve the recording density. Such a reduction in the width of the conductor and a reduction in the thickness of the conductor make the patterned copper itself, which is a recording electrode, extremely weak in mechanical strength, and the copper foil is easily damaged. Therefore, in the conventional electrostatic recording head, for example, when a side plate is bonded to a wiring board, a filler having a high hardness such as SiO ₂ is filled in the adhesive, so that when the side plate is bonded and pressed The foil was easily scratched, and the conductor was sometimes cut in the middle. In the electrostatic recording head, a large number of recording electrodes, for example, in the case of printing on A0 size paper, a total of about 7,000 or more recording electrodes are formed on both surfaces of the wiring board, and even if one of them is disconnected, It will not function properly. Moreover, it is extremely difficult to repair the broken conductor. Therefore, the conventional high-density electrostatic recording head has a problem that the yield is poor because the mechanical strength of the conductor is weak.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrostatic recording head capable of improving the mechanical strength of conductors formed in high density on a wiring board. It is a thing.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention comprises a wiring board having a large number of conductors whose tip portions are used as recording electrodes, and the conductors are spaced at intervals of 50.
In the electrostatic recording head having a thickness of up to 150 μm, the width of the portion of the conductor other than the tip portion used as the recording electrode is formed to be 1.2 to 1.5 times the width of the tip portion of the conductor. It is characterized by being.

[0007]

According to the present invention, due to the above-described structure, the conductor spacing is 5
Even if the density is as high as 0 to 150 μm, the width of the portion other than the tip of the conductor used as the recording electrode is formed to be 1.2 to 1.5 times the width of the tip. The width of the portion other than the tip of the conductor is wider than that of the conventional one, and therefore the mechanical strength of the conductor is improved as compared with the conventional one. The conductor interval is set to 50 to 150 μm because the conductor width can be formed sufficiently large if the conductor interval is 150 μm or more, and the conductor width is 25 μm or less when the conductor interval is 50 μm or less. This is because with the current technology, the yield at the time of etching becomes extremely poor and it becomes difficult to form a conductor. The reason why the conductor width other than the tip is 1.2 to 1.5 times the conductor width at the tip is that the width of the conductor other than the tip does not become so large at 1.2 times or less, and the mechanical strength of the conductor does not increase. This is because the improvement of the electric field cannot be expected so much, and if it is 1.5 times or more, the distance between the conductors becomes extremely small, which may cause discharge breakdown.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of an electrostatic recording head which is an embodiment of the present invention, and FIG. 2 is a diagram showing a wiring pattern formed on a wiring substrate of the electrostatic recording head.

The electrostatic recording head shown in FIG. 1 comprises a head half 2a and a head half 2b. The head half 2a includes a wiring board 10a having a large number of conductors 12a formed on one surface at a pitch of about 127 μm.
0a, and a side plate 20a provided to maintain the linearity of the tip portion of 0a. Similarly, head half 2
b is a wiring board 10b on which a large number of conductors 12b are formed,
The wiring board 10b is provided with a side plate 20b provided to maintain the linearity of the tip portion. A glass epoxy board is used as the wiring boards 10a and 10b.

The head half 2a and the head half 2b are, as shown in FIG. 1, the conductors 12a of the wiring boards 10a and 10b.
The surfaces on which 12b are not formed are pasted together. Usually, when forming a conductor or the like on a substrate, the substrate may be warped or bent. In such a case, the conductor 1
The linearity of the wiring board can be realized with high accuracy by bonding the two wiring boards 10a and 10b after polishing and flattening the surface of the wiring board on which 2a and 12b are not formed. Therefore, in the present embodiment, it is possible to obtain a highly accurate recorded image as compared with, for example, an electrostatic recording head in which recording electrodes are formed on both surfaces of one wiring board. Further, the head half 2a and the head half 2b are joined so that the conductor 12a of the wiring board 10a and the conductor 12b of the wiring board 10b are staggered.

The wiring boards 10a and 10b also include a high voltage IC (HVIC) 14 and a common board 16.
a and 16b are provided. High voltage IC
Reference numeral 14 is for applying a high voltage necessary for forming an electrostatic latent image on the electrostatic recording paper to the recording electrode. Conductors are formed in a matrix on the drive common power supply boards 16a and 16b and are connected to the conductors from the high voltage IC 14.

The conductor 12 shown in FIG. 2 is made of copper foil. The thickness of the conductor 12 is 5 μm in order to reduce the load on the high voltage IC 14. A portion having a length of 5 mm from the tip A of the conductor 12 is used as the recording electrode 120. The length of the recording electrode 120 is set to 5 mm is 5
This is because if the thickness is mm, the electrode portion remains sufficiently even if the head is polished and finished. Since the pitch interval of the recording electrodes 120 formed on each of the head halves 2a and 2b is 127 μm, a high density electrostatic recording head of 400 dpi (dots / inch) can be obtained in this embodiment.

Further, the width of the recording electrode 120 at the tip of the wiring substrate 10 is formed to be 50 μm, and the width of the conductor 12 excluding the recording electrode 120 is about 20% larger than the width of the recording electrode 120, that is, approximately. It is formed to 60 μm. Although the resolution of the recorded image is improved as the width of the recording electrode 120 is reduced, the width of the recording electrode is reduced as the width of the copper foil is reduced and the yield of products due to the etching work is reduced. The minimum limit is 50 μm. This wiring pattern can be formed by a normal photolithography technique. At the time of etching, conditions may be set so that only the recording electrode portion falls within a predetermined size.

When the conductor is formed to have a constant width of 50 μm as in the conventional case, the copper foil is easily cut due to over-etching or chipping. However, in the present embodiment, since the width of the conductor other than the recording electrode portion is formed to be as wide as 60 μm, the insufficient strength of the conductor due to the thickness of the conductor of 5 μm can be earned in the width direction, so that the disconnection or the like can be prevented. Defects can be significantly reduced.

Further, in the present embodiment, in order to inspect the formed conductor, it suffices to inspect whether or not it has a predetermined size mainly by the recording electrode portion which determines the drawing quality. Other conductor parts are
Only the shape such as disconnection or short circuit should be inspected. As described above, since the portion required as the recording electrode is formed only at the tip portion of the conductor, the inspection process is greatly simplified.
Further, when an etching defect occurs, repair is sufficiently possible in the case of short circuit, but in the case of disconnection, it is extremely difficult because the conductor thickness is very thin. However, in this embodiment, the number of conductor breakages in the manufacturing process can be reduced as compared with the conventional one, so that the yield can be improved.

In the above embodiments, the width of the conductor excluding the recording electrode was formed to be about 20% larger than the width of the recording electrode, but the present invention is not limited to this. The width of the conductor excluding the recording electrode may be 1.2 to 1.5 times the width of the recording electrode. If the width of the conductor is less than 1.2 times the width of the recording electrode, the width of the recording electrode and the width of the conductor do not change so much, and the mechanical strength of the conductor does not improve so much. If it is more than 0.5 times, the interval between the conductors becomes narrow, and there is a possibility that discharge breakdown may occur. By thus forming the width of the conductor excluding the recording electrode to be 1.2 to 1.5 times the recording electrode width, an electrostatic recording head having the same effect as that of the above-described embodiment is formed. be able to.

In the above embodiment, the case where the tip of the conductor is up to 5 mm is used as the recording electrode, but the present invention is not limited to this, and the length of the recording electrode is 1 mm. It may be between 10 mm. The shorter the length of the recording electrode is, the smaller the proportion of the narrow conductor portion is, so that the mechanical strength of the conductor is improved. Further, if the length of the recording electrode is too short, the recording electrode may be lost when the tip is polished. Therefore, the length of the recording electrode is preferably within the above range.

Furthermore, in the above embodiment, the case where two wiring boards are bonded together to form the electrostatic recording head has been described, but the present invention is not limited to this, and one wiring board is used. But it's okay. Further, even when two wiring boards are bonded together, the surfaces on which the conductors are formed may be bonded together via an insulator.

[0019]

As described above, according to the present invention, the width of the conductor other than the recording electrode is 1.2 to the width of the recording electrode.
Since it is formed to be 1.5 times larger, the mechanical strength of the conductors formed at a high density on the wiring board can be improved. Therefore, for example, even when the side plate is adhered and pressed onto the wiring board, It is possible to provide an electrostatic recording head that can reduce the number of conductor breakages and can improve the yield.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrostatic recording head that is an embodiment of the present invention.

FIG. 2 is a diagram showing a wiring pattern formed on a wiring substrate of the electrostatic recording head.

FIG. 3 is a diagram showing a wiring pattern formed on a wiring substrate of a conventional electrostatic recording head.

[Explanation of symbols]

 2a, 2b Head half body 10, 10a, 10b Wiring board 12, 12a, 12b Conductor 14 High voltage IC 16a, 16b Common board 20a, 20b Side plate 120 Recording electrode

Claims (1)

Claim: What is claimed is: 1. A wiring board having a large number of conductors, the tips of which are used as recording electrodes.
In the electrostatic recording head having a thickness of up to 150 μm, the width of the portion of the conductor other than the tip portion used as the recording electrode is formed to be 1.2 to 1.5 times the width of the tip portion of the conductor. An electrostatic recording head characterized by being provided.