JPH04186258A - Scorotron charging device - Google Patents

Abstract

PURPOSE:To lower the cost of a scorotron charging device and heighten the performance by making an arrangement of multiple parallelogrammic openings in plural lines arranged on a charged grid the most suitable arrangement. CONSTITUTION:An arrangement of multiple parallelogrammic openings 6 forming in plural lines on a charged grid 5 is provided by shifting the arrangement in the direction of arbitrary sides of the parallelogram. By this arrangement, the number of progressive processes for press working can be reduced. That is to achieve low cost and high performance of a scorotron charging device because the charged grid can be machined at a low cost with high precision by the progressive press working method.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a scorotron charging device having a charging grid for use in electrophotographic equipment.

Prior Art In recent years, in scorotron charging devices for electrophotographic devices,
There is a strong demand for lower cost and higher performance.

An example of the conventional scorotron charging device described above will be described below with reference to the drawings.

FIG. 3 is a sectional view of the electrophotographic apparatus, showing only the photosensitive drum 1 and the scorotron charging device 2. FIG. In FIG. 3, a scorotron 2 includes an insulating base 3, a wire 4 made of tungsten, and a charging grid 5 made of a thin metal plate.
are each insulated and supported. Furthermore, the charging grid 5 is provided with an opening 6 between the photosensitive drum 1 and the wire 4.

The functions of the scorotron charging device 2 configured as described above will be explained below. A scorotron charging device 2 includes a photosensitive drum 1 that rotates at a constant speed in six directions of arrows.
The surface of the electrode is charged uniformly and at a constant potential.

For this purpose, a high voltage is applied to the wire 1, and the surface of the photosensitive drum 1 is charged with generated ions. Here, the charging grid 6 controls the charging grid 5 so that it can be charged uniformly to a target potential even if the surface potential of the photosensitive drum 1 before charging is uneven due to the grid effect. applies different high voltages.

FIG. 4 is a plan view showing only the charging grid 5 shown in FIG. 3, and the charging grid 5 has a relatively large opening hole 6.
is provided. However, the grid effect described above is greatly influenced by the size of the opening holes 6, so in recent years, performance has been improved by providing a large number of relatively small opening holes 6, as shown in part of a charging grid in FIG. There is a tendency to try to measure.

Problems to be Solved by the Invention However, in the configuration shown in FIG. 5, it is not possible to use the press processing method, which is inexpensive for processing costs, for the reasons shown below, and therefore, it is necessary to process the charged grid 5 by etching processing, which is expensive. As a result, there was a problem in that the scorotron charger itself became very expensive.

The reason why the press working method cannot be adopted is that problems remain in terms of both cost and precision, and this will be explained below from the perspective of the mold structure using FIGS. 6 and 7. 6th
The figure schematically shows a cross section of the entire structure when all open holes 6 are to be press-formed in the material 7 of the charging grid 5 at the same time.

In order to process all the opening holes 6 at the same time, an upper die 8. The material 7 may be pressed using the lower mold 9 having a recessed portion, but at this time, the width of the protrusion 10 of the lower mold 9 is very narrow, so the strength is reduced and the life of the lower mold 9 is extremely shortened.

On the other hand, if you try to widen the width of the protrusion 10 to increase the strength, the opening hole will inevitably become smaller and the performance as a charging grid will deteriorate (11). This is a presser foot to keep it in place.

In order to solve these problems, a progressive mold, the schematic cross-sectional configuration of which is shown in FIG. 7, is used for boat fishing. This is a method in which non-adjacent opening holes 6 are first pressed, and then non-adjacent opening holes 6 are further processed using another press.This widens the protrusion of the lower die 9 and extends the life of the die. Fig. 7 shows a mold for processing the remaining opening holes 6 on a material 7 in which a part of the non-adjacent opening holes 6 has been processed using another mold (not shown). Note that parts with the same function are indicated by the same numbers as in Fig. 6. In order to process the remaining opening hole 6, press with an upper die 8 having a corresponding convex part and a lower die 9 having a concave part. By machining, a fully open hole 6 will be formed.It goes without saying that at this time, the protrusion 10 of the lower mold 9 can also have a sufficient width.

However, with this progressive press processing method, problems remain in that the pitch of the opening holes is likely to shift due to errors in the feeding amount of the material 7, and the number of molds is large (which leads to an increase in cost). There was a problem that it was not possible to sufficiently reduce the cost and improve the performance of the scorotron charging device.Conversely, it is the arrangement of the opening holes 6 that can reduce the number of forward strokes that reduces the cost and improves the performance of the scorotron charging device. This will be a major point for improvement.

, Here, the relationship between the arrangement of the opening holes 6 and the number of progressive strokes will be considered. Even in the progressive press working method, it is of course meaningless if there is a protrusion 10 on the lower die 9 as shown in FIG.

Since this protrusion 10 corresponds to the crosspiece 12 of the charging grid 5, the number of sequential feeding strokes is determined by how many opening holes 6 are present around the intersection of the crosspieces 12. In the arrangement of the opening holes 6 in FIG. 5, since there are four opening holes 6 around the crosspiece 12, the number of forward strokes is necessarily four.

For this reason, the conventional arrangement of the opening holes 6 does not provide much advantageous effects in terms of cost and precision.

In view of the above problems, the present invention provides an inexpensive and highly accurate charging grid by arranging the opening holes 6 in an optimal arrangement for the press working method.

Means for Solving the Problems In order to solve the above-mentioned problems, the scorotron charging device of the present invention provides a charging grid with a large number of parallelogram-shaped opening holes arranged in rows in the direction of any side of the parallelogram. It has a structure that allows it to move forward.

Function: The present invention can reduce the number of progressive strokes during press working by arranging the opening holes as described above, so that a charging grid can be processed at low cost and with high accuracy.

EXAMPLE Hereinafter, a scorotron charging device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a portion of a charging grid of a scorotron charging device in a first embodiment of the present invention. Note that the same numbers are used for parts with the same functions as those in the conventional example. In FIG. 1, the charging grid 5 has four parallelogram-shaped opening holes 6.
The opening holes 6 are arranged in rows, and the rows of opening holes 6 are staggered in a direction perpendicular to the rotational direction A of the photosensitive drum.

The operation of the scorotron charging device configured as described above is the same as that of the conventional example, so a description thereof will be omitted. However, when the charging grid 5 configured in this manner is processed by a press working method, the number of sequential feeding steps can be reduced. Specifically, as is clear from the explanation of the conventional example, since there are only three opening holes 6 around the crosspiece 12 of the opening hole 6, the number of progressive strokes in press working is reduced from the conventional four strokes to three strokes. It can be shortened to Therefore, the number of press molds for progressive feeding can be reduced, and at the same time, the probability of occurrence of uneven feeding (uneven pitch of opening holes 6 of charging grid 5) due to feeding accuracy during progressive feeding can be reduced.

As described above, according to the present embodiment, the arrangement of the large number of parallelogram-shaped opening holes 6 arranged in rows on the charging grid 5 is shifted in the direction of an arbitrary side of the parallelogram. Since a low-cost, high-precision charging grid can be fabricated using the progressive pressing method, it is possible to achieve lower cost and higher performance of the scorotron charging device.

In the first embodiment, the parallelogram-shaped opening holes 6 are shifted in a direction perpendicular to the rotational direction A of the photosensitive drum, but as shown in FIG. You can change it every time. Alternatively, it may be shifted in another side direction of the parallelogram (in the direction of the row of four opening holes in the diagonal direction in FIG. 5 of the conventional example).

Effects of the Invention As described above, the present invention provides an arrangement in which a large number of parallelogram-shaped opening holes arranged in a row in parallel with the charging grid of a scorotron charging device are shifted in the direction of an arbitrary side of the parallelogram. By doing so, it is possible to achieve low cost and high accuracy of the charging grid, that is, low cost and high performance of the scorotron charging device.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a part of the charging grid of a scorotron charging device according to the first embodiment of the present invention, FIG. 2 is a plan view showing a modification of the first embodiment, and FIG. 3 is an electrophotograph. A sectional view showing only the positional relationship between the photosensitive drum and the scorotron charging device in the device, FIG. 4 is a plan view of a conventional first charging grid, and FIG. 5 is a plan view showing a part of a conventional second charging grid. FIGS. 6, 7, and 7 are cross-sectional views showing a schematic mold configuration for processing a charging grid by a press working method. 1...Photosensitive drum, 2...Scorotron charging device, 5...Charging grid, 6...
... Opening hole, 12... Crosspiece. Name of agent Patent attorney Akira Koeji Akira and two others Figure 1 G-11 Opening Chu t2-Oku 6 and Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In a scorotron charging device equipped with a charging grid for uniformly charging a photosensitive drum, a large number of parallelogram-shaped opening holes arranged in a row in parallel with the charging grid are arranged in an arbitrary manner in the parallelogram. A scorotron charging device characterized by being provided offset in the direction of the side.