JPS6067867A - Electric field forming apparatus - Google Patents

Abstract

PURPOSE:To generate a uniform electric field over a considerable range in a cylindrical tube, by arranging a pair of electrode plates, to which positive and negative voltages are applied, to the inner wall of the cylindrical tube at positions synmetric around the center of said tube so as to have a circular arc cross- sectional area shape. CONSTITUTION:In an experiment conducted by changing the string length of an electrode plate to 0.4D, 0.5D and 0.6D, at the time of 0.5D, the electric field in a cylindrical tube is most stable. It is experimentally cleared that the electrode plate, which can obtain a uniform electric field within a difference range of about 5% or less with respect to a range of + or -0.05D in left and right X-directions and + or -0.3D in before and behind Y-directions around the center axis 10A of the cylindrical tube 10, has pref. a string of which the length is present in a range of 0.45D<X<0.55D. By using the electrode plate having this range, a considerably stable electric field is obtained in the vicinity of the center axis 10A of the cylindrical tube 10.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to generating a uniform electric field inside a cylinder, which is necessary when measuring the charge distribution of toner particles used in an electrostatic recording device, for example. This invention relates to an improvement of an electric field forming device that generates electric fields.

[Prior art]

For example, Japanese Patent Laid-Open No. 57-79958 proposes a method and apparatus for measuring the charge distribution of toner particles used in an electrostatic recording device. Toner particles are introduced into a chamber by generating a laminar flow of air at various speeds, and the charge distribution of the toner particles is measured. Generating a uniform electric field within such a chamber has conventionally required a large electric field generating device.

Figure 1 shows this, and the structure of the electrode plates that generate a uniform electric field inside the cylindrical tube 1 consists of a pair of parallel electrode plates 2A that are sufficiently wider than the desired uniform electric field area. , 2B, and a voltage is applied to the parallel polar plates 2A, 2B.

Such an electric field forming device has the following drawbacks.

(1) Since the parallel electrode plates 2A and 2B are very wide, a large space is used.

(2) Since the parallel electrode plates 2A and 2B are located outside the cylindrical tube 1, there is a danger if a high voltage is applied to the parallel electrode plates 2A and 2B.

[Purpose of the invention]

It is an object of the present invention to provide an electric field forming device that generates a uniform electric field over a considerable range within a cylindrical tube by safe and simple electrode arrangement.

[Structure of the invention]

The present invention aims to achieve the above object, and includes a pair of electrode plates centered on the center of the cylindrical tube on or near the inner wall of the cylindrical tube. A uniform electric field is obtained over a range, and a pair of polar plates that apply positive and negative voltages are placed at symmetrical positions around the center of the cylindrical tube, and are applied to the inner wall or inner wall of the cylindrical tube. This is achieved by an electric field forming device which is arranged closely in an arcuate cross-sectional shape and whose chord length X of the plates is in the range 0.45D<X (0.55D).

Here, D is the inner diameter of the cylindrical tube.

〔Example〕

FIG. 2 shows a pair of arc-shaped electrode plates placed along the inner wall of an insulating cylindrical tube 1o, with the cylindrical tube center 10A as the center.
The results of an experiment were conducted by changing the direction (the size of the large circular arc of the electrode).

When the inner diameter of the cylindrical pipework 0 is DQ, the chord length of the pair of electrodes 21A, 21B in Fig. 2(a) is 0.
．． 4D, a pair of electrodes 22A in FIG. 2(b)
, 22B have electrodes with a string length of 0.5D, and the pair of electrodes 23A and 23B in FIG. 2(e) have electrodes with a chord length of 0.6D. .

Here, the experiment was conducted with the voltage (2) applied to the electrode plate at ±500 V, and the inner diameter of the cylindrical tube (10) was 50 mm.

The graphs on the right side of FIGS. 2(a) to (c) show the center 10A of the cylindrical tube 10 and the center 1
The electric field strength in the front-rear (7) direction on the gauze spaced 0.05D (2.5 mm) from 10A in the left-right direction is shown by a solid line and a broken line, respectively.

It can be seen that the electric field within the cylindrical tube 10 formed by a pair of positive and negative electrode plates varies considerably depending on the length of the chord of the electrode plate.If the chord length of the electrode plate is 0.4D, 0.5
In the experiment shown in FIG. 2 where D and 0.6D were changed, the electric field within the cylindrical tube 10 was most stable when the chord length of the electrode plate was 0.5D.

±0 in the left and right direction around the central axis 10A of the cylindrical tube 10
．． 05D, for an electrode plate that can obtain a uniform electric field with a difference range of within about 5% in the range of ±0.3D in the longitudinal (A) direction, it is preferable that the chord length X of the electrode plate is in the following range. This was experimentally clarified.

0.45D <
A fairly stable electric field can be obtained near IIOA.

FIG. 3 shows an example in which the electric field generating device of the present invention is applied to measuring the charge distribution of toner particles. A pair of arc-shaped electrode plates 22 forming a chord of 0.5D.
A and 22B are provided to form an electric field of EV/, L, and air A is introduced into the cylindrical tube 10 through a honeycomb-shaped filter 33 on the upper end surface of the enclosed cylindrical tube 10, and the air A is introduced into the cylindrical tube 10 at a parallel flow rate of V&. Since there is a laminar flow, the toner T separated into 1 particles is naturally sucked in from the introduction tube 31 at the upper end of the central axis 10A of the cylindrical tube 10 and falls. Here, if the amount of charge on the toner particles is q, then the Coulomb force of Fe''qE acts.

Furthermore, if the viscosity coefficient of air is η, the toner particle radius is r, and the lateral velocity is V, then the Stokes equation Fr = 6πηrV holds true, and the toner T falls by a length e and falls onto the filter 32 with the center axis 10A. Assuming that it falls at a distance d from , the relationship is V: Va = d: d j Fr = Fe, so it becomes 6E.

Therefore, the toner collected on the filter 32 is taken out of the apparatus and analyzed by an electromagnetic analyzer.

FIG. 4 is a toner charge spectrogram showing an example of the above analysis results.

〔Effect of the invention〕

As is clear from the above description, the present invention makes it possible to generate a uniform electric field over a wide range within a cylindrical tube by using a safe and simple electrode arrangement.

[Brief explanation of drawings]

, FIG. 1 shows a conventional electric field forming device that generates a uniform electric field within a cylindrical tube. Figure 2 (a), (b), (c)
is a graph showing the cross section of a cylindrical tube and its electric field strength distribution when the shape of the electrode provided inside the cylindrical tube is changed. FIG. 3 is an example of application of the present invention to a toner particle charge distribution measuring device. Figure 4 is the third
A toner charge spectrogram showing an example of graphical analysis results. 10... Cylindrical tube 10A-°° central axis (21A, 21
B), (22A, 22B), (23A, 21)・
...Paired electrode plate D...Cylindrical tube inner diameter agent Yoshimi Kuwahara

Claims (1)

[Scope of Claims] A pair of positive and negative electrode plates for applying voltages are disposed at symmetrical positions about the center of the cylindrical tube and have an arcuate cross-sectional shape on or near the inner wall of the cylindrical tube. and the chord length X of the electrode plate is within the range of 0.45D < x (0.55D), where D is the inner diameter of the cylindrical tube.