JPH03105265A - Measuring apparatus of amount of electrification of toner - Google Patents

Abstract

PURPOSE:To measure the amount of electrification of toner quickly and accurately by producing a gas flow from a gas producing means so as to prevent the toner from sticking to a Faraday cage when a prescribed amount of binary developer is put in the cage and discharged together with a high-pressure gas. CONSTITUTION:A gas producing means 16 is provided so as to prevent toner T from sticking to a Faraday cage 10 when the toner T is discharged from the cage 10 together with a high-pressure gas. The means 16 is constructed of an air gun 16a, and a pipe 16b for supply, which is connected to a high- pressure nitrogen gas source not shown in the figure, is connected thereto. When the toner T is discharged from the cage 10 together with the high-pressure gas, a high-pressure gas jet wave B is generated in the direction perpendicular substantially to the direction of discharge of the toner T so that it comes into contact with the annular lower surface of a fixation fitting 10c, and thereby the toner T sticking on the annular lower surface is removed. According to this constitution, the development, design, maintenance and control of an electrophotographic recording apparatus are facilitated very much.

Description

[Detailed Description of the Invention] [Summary] A two-part developer used in the development process of electrophotographic recording devices, that is, a developer component of a two-part developer consisting of a magnetic carrier and a toner. The present invention relates to a toner charge amount measuring device that measures the amount of charge on a toner, and is a toner charge amount measuring device that incorporates a blow-off method, which can prevent toner from adhering to a Faraday cage and achieve accurate and quick measurement. The purpose of this device is to introduce a predetermined amount of two-component developer into a Faraday cage, blow high-pressure gas into the Faraday cage, and remove toner from the two-component developer from the Faraday cage together with the high-pressure gas. In a toner charge measurement device that extracts and measures the charge of the magnetic carrier of the two-part developer left in the Faraday cage through the Faraday cage, the toner is discharged from the Faraday cage along with high-pressure gas. A toner charge amount measuring device is provided with a gas flow generating means for generating a gas flow so as to prevent toner from adhering to a Faraday cage when the toner is charged.

[Industrial Application Field] The present invention relates to a two-component developer used in the development process of an electrophotographic recording device, that is, a toner that uses a certain amount of the developer in the two-component developer consisting of a magnetic carrier and a toner. The present invention relates to a toner charge amount measuring device that measures the amount of charge on a toner.

In electrophotographic recording devices, the development process is one of the important processes that greatly affects the quality of recorded images.In this development process, the amount of charge on the toner is the most fundamental parameter that affects the quality of recorded images. be. Therefore, in the development, design, and maintenance of electrophotographic recording devices, it is necessary to accurately grasp the amount of charge on the toner, and there is a need to accurately and quickly measure the amount of charge on the toner.

[Conventional technology]

The blow-off method is known as one of the conventional toner charge amount measurement methods. In this blow-off method, high pressure gas (for example, nitrogen gas) is blown onto a predetermined amount of two-component developer.
The toner, which is small in size and lightweight, is blown away, and then the amount of charge on the magnetic carrier, which has a charge equivalent to that of the toner and opposite in polarity, is measured, and then the total mass of the magnetic carrier is measured. Since the total mass of the original two-component developer is known, the total mass of blown toner can be determined by subtracting the total mass of the magnetic carrier from it. Therefore, by dividing the amount of charge on the magnetic carrier by the total mass of the toner, the amount of charge on the toner per unit mass is measured.

Referring to FIG. 5, a conventional toner charge amount measuring device incorporating the above-described blow-off method is schematically shown, and this toner charge amount measuring device is equipped with a Faraday cage 10. As shown in FIG.

The Faraday cage 10 includes a metal casing 10a having an inverted funnel shape, a metal mesh 10b applied to the lower opening of the metal casing 10a, and a fixture 10c for the metal mesh 10b. Further, the toner charge amount measuring device includes a capacitor 12 having a previously known capacity, one end of the capacitor l2 is connected to the metal casing 12a of the Faraday cage 10, and the other end is grounded. Furthermore, the toner charge amount measuring device is equipped with a potentiometer 14, which is connected to both ends of the capacitor 12 so as to be able to measure the potential therebetween.

Referring to FIG. 6, a magnetic carrier C and a toner T are shown in two parts in a developer. That is, the magnetic carrier C and the toner T rub against each other in the developer and are charged with opposite polarities, and the particle size of the magnetic carrier C is much larger than that of the toner T. , the toner T is electrostatically attached around the magnetic carrier C. At this time, the amount of charge held by the entire magnetic carrier C and the amount of charge held by the entire toner T are equivalent to each other and have opposite polarities. In addition, in the example of Fig. 6,
Although the magnetic carrier C is charged with a positive charge and the toner T is charged with a negative charge, there is also the opposite case where the magnetic carrier C is charged with a negative charge and the toner T is charged with a positive charge. .

To describe the operation of the conventional toner charge amount measuring device shown in FIG. 5, first, a predetermined amount of the two-component developer in which the magnetic carrier C and the toner T are in the state shown in FIG. 6 is placed in a Faraday cage. 10 into the metal casing 10a from its upper opening, and then the metal casing 1
High pressure gas (for example, nitrogen gas) is blown into the metal casing 10a from the upper opening of the metal casing 10a. When the magnetic carrier C and the toner T are separated by the blowing of such high-pressure gas against the electrostatic adsorption force acting on each other,
The toner T is entrained by the blown high-pressure gas and discharged to the outside of the metal casing 10a through the metal mesh 10b, while the magnetic carrier C having a large particle size remains inside the metal casing 10a. In addition, the metal mesh 10b
Needless to say, the diameter of the particles is sufficiently larger than the particle size of the toner T and also sufficiently smaller than the particle size of the magnetic carrier C.

Since the magnetic carrier C itself is conductive, the electric charge of the magnetic carrier C left in the metal casing 10a passes through the metal mesh 10b and the metal casing 10a, and is further transferred between the metal casing 10a and the capacitor 12. It is stored in the capacitor 12 via the conductive path between them. When the charge in the capacitor 12 is saturated, the measured value of the potentiometer 14 is read, and the total amount of charge on the magnetic carrier C left in the metal casing lOa is measured. This is equivalent to the total amount of charge of the opposite polarity that the toner T discharged from the casing 10a had. Note that the capacitance of the capacitor 12 is known as described above.

Next, the magnetic carrier C is removed from the metal casing 10a.
is taken out, its total mass is measured, the total mass of the toner T discharged from the metal casing 10a is calculated, and the 1·toner charge amount per unit mass is determined.

[Problems to be Solved by the Invention] By the way, the conventional toner charging as shown in FIG. 5! J
:/fl! In the J constant device, the metal mesh 10b
Since the toner T discharged through the toner T is lightweight and fine, it scatters, and a portion of it may adhere to the Faraday cage 10, particularly to the annular lower surface of the fixture 10c. Although some of the adhered toner T can be removed by blowing high-pressure gas, most of the toner T adhered to the annular lower surface of the fixture 10c is removed by the influence of the high-pressure gas blown out through the metal mesh 10b. without receiving
Therefore, the adhered toner T cannot be removed from the annular lower surface of the fixture 10c. If the toner T adheres to the Faraday cage 10 in this way, the rapid measurement of the charge amount of the magnetic carrier C as described above is hindered. Not only that, but the reliability of the measurement results is also impaired. This is because when some of the adhered toner T is being removed, the capacitor 12 has not yet been charged with electricity, and therefore it takes a long time until the capacitor 12 is completely charged. This is because the attached toner T interferes with measurement and cannot be removed.
This is because if there is a charge, the measurement will be incomplete due to the influence of the charge. Furthermore, Faraday cage 1
Although it is possible to remove the toner T adhering to the toner by wiping it with a brush or cloth, in that case, frictional charging will occur when wiping with a brush or cloth, which will seriously affect the measurement. Therefore, it is not possible to use a brush or cloth to remove the adhered toner T.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner charge amount measuring device incorporating the blow-off method, which can prevent toner from adhering to a Faraday cage and achieve measurement accurately and quickly. It is.

[Means to solve the problem]

In the toner charge amount measuring device according to the present invention, as in the conventional case, a predetermined amount of two-part developer is introduced into the Faraday cage, and gas is blown into the Faraday cage under high pressure to remove the part of the two-part developer. The toner is discharged from the Faraday cage with a high pressure gas, and the charge on the magnetic carrier of the two-part developer remaining in the Faraday cage is extracted through the Faraday cage and measured. However, in the toner charge amount measuring device according to the present invention, a gas flow generating means is provided for generating a gas flow so as to prevent the toner from adhering to the Faraday cage when the toner is discharged from the Faraday cage together with the high-pressure gas. It is characterized by the fact that

[For production]

In the toner charge amount measuring device according to the present invention, a gas flow is generated from the gas flow generating means, and when the toner is discharged from the Faraday cage together with the high pressure gas, the toner is transferred to the Faraday cage. Adhesion will be prevented.

〔Example〕

Next, an embodiment of the toner charge amount measuring device according to the present invention will be described with reference to FIGS. 1 to 4 of the accompanying drawings.

First, referring to FIG. 1, one embodiment of a toner charge amount measuring device according to the present invention is shown, and many of its components are substantially the same as those shown in FIG. Therefore, in FIG. 1, the same reference numerals and symbols are used for the same components as those of the toner charge amount measuring device shown in FIG. I will refer to the explanation of

The toner charge amount measuring device shown in FIG. 1 is provided with a gas flow generating means 16 for preventing the toner T from adhering to the Faraday cage IO when the toner T is discharged from the Faraday cage IO together with high-pressure gas. It will be done. In this embodiment, the gas flow generating means 16 comprises an air gun 16a, and a high-pressure gas supplying vibrator 16b extends from the air gun 16a and is connected to a suitable high-pressure gas source (not shown).

Note that such a high-pressure gas source may be, for example, a high-pressure nitrogen gas source. As shown in FIG. 1, the air gun 16a is arranged to generate a high-pressure gas jet flow B in a direction substantially perpendicular to the direction in which the toner T is discharged from the Faraday cage 10 together with the high-pressure gas; At this time, the high-pressure gas jet stream B is brought into contact with the annular lower surface of the fixture 10c, so that the toner T adhering to the annular lower surface of the fixture 10c can be removed as shown in FIG.

The diameter of the annular lower surface of the fixture 10c is approximately 30 m+, and in order to remove the toner T at once from the annular lower surface of such size, the high-pressure jet nozzle of the air gun 16a is
It is preferable that the width is 0[111 or more. However, the high-pressure jet nozzle of the air gun 16a may be made smaller to form a beam-like high-pressure jet flow, and in this case, the air gun 16a may be attached to the fixture 10c.
If the air gun 16a can be moved tangentially with respect to the annular surrounding wall of the fixture 10c, or the air gun 16a can be rotated about a vertical axis, such a beam-shaped high-pressure jet stream can also cause the fixture 10c to It is possible to remove the toner T from the entire surface of the annular lower surface.

In the toner charge amount measuring device as shown in Fig. 1,
Measurements of the toner charge amount of the two-part developer were actually carried out under the conditions shown below.

(1) Sample: 0.8 g (carrier average particle size iooμ steel, toner average particle size 10μ) (2) Metal mesh: 500 mesh (3) Blowing high pressure gas:
0.8 kg/cd (4) Jet flow: 1.
0.8 g of a 5 kg/cd sample (two-component developer) was introduced into the metal casing 10a of the Faraday cage, and high pressure gas (0.8 kg/a) was applied for about 40 seconds.
ll) into the metal casing 10a, while a jet stream (1.5 kg/c
4) was ejected.

For comparison, similar measurements were conducted under the same conditions except that the air gun 16a was not activated.

The measurement results are shown in FIG. In the figure, characteristic curve a is the case according to the present invention, and characteristic curve b is the case according to the comparative example (conventional). As is clear from the characteristic curve a, according to the present invention, the storage of electricity in the capacitor 12 ends approximately 14 seconds after the start of high-pressure gas injection, but in the case of the comparative example (characteristic curve b), the storage of electricity in the capacitor 12 ends. It takes about 40 seconds from the start of high pressure gas injection until the electricity storage is completed. This is clearly an effect of toner adhering to the Faraday cage 10. The difference between characteristic curve a and characteristic curve b at the end of charging capacitor l2 shows the inaccuracy of the measurement in the case of the comparative example.

Referring to FIG. 3, in this embodiment, a suction device 16c is used as the gas flow generating means 16, and this suction device 16c
has a funnel-shaped morphology. As is clear from Figure 3,
The opening of the suction device 16c is larger than the lower surface of the Faraday cage 10 and is arranged to receive the lower surface. The suction device 16c is a suitable vacuum device such as a suction pump (
(not shown), thereby generating a suction gas flow along substantially the same direction as the discharge direction of the toner T when the toner T is discharged from the Faraday cage 10 together with the high-pressure gas. Therefore, the high pressure gas and toner T discharged from the Faraday cage 10 are drawn into the suction device 16c, and as a result, the toner T is prevented from adhering to the Faraday cage IO.

Referring to FIG. 4, a variation of the embodiment shown in FIG. 3 is shown in which the aspirator 160' used is smaller than that shown in FIG. The width is somewhat larger than the radial width of the fixture 10c. The suction device 160' is also connected to a suitable vacuum device, such as a suction pump (not shown), as in the case of FIG. A suction gas flow is generated along approximately the same direction. The suction device 160' is the third
Unlike the case shown, it is moved along the annular lower surface of the fixture 10c, thereby removing the adhered toner T from the annular lower surface in a manner similar to a vacuum cleaner.

In the above embodiment, a capacitor and a potentiometer were used to measure the charge of the magnetic carrier left in the Faraday cage, but it goes without saying that the charge can also be measured with a galvanometer, etc. .

[Effects of the Invention] As is clear from the above description, in the toner charge amount measuring device according to the present invention, since toner is prevented from adhering to the Faraday cage, the toner charge amount can be measured quickly and accurately. This makes it possible to contribute to the development, design, and maintenance of electrophotographic recording devices.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the toner charge amount measuring device according to the present invention, and FIG. Graph showing measurement results; FIG. 3 is a schematic sectional view showing another embodiment of the toner charge amount measuring device according to the present invention; FIG.
The figure is a schematic sectional view showing a modification of the embodiment shown in FIG. 3, FIG. 5 is a schematic sectional view of a conventional toner charge amount measuring device, and FIG. 6 shows the magnetic carrier and toner present in the two-component developer It is a schematic diagram showing the state of and. DESCRIPTION OF SYMBOLS 10... Faraday cage, 10a... Metal casing, 10b... Metal mesh, 10c... Fixture, 12... Capacitor, l4... Potentiometric needle, 1
6... Gas flow generating means, 16a... Air gun, 16
c・160'...Suction device.

Claims (1)

[Claims] 1. A predetermined amount of two-component developer is introduced into a Faraday cage (10), and a high pressure gas is blown into the Faraday cage to transfer the toner (T) of the two-component developer to the Faraday cage. A toner charge amount measuring device that extracts and measures the electric charge of a magnetic carrier (C) of the two-component developer left in the Faraday cage through the Faraday cage. , a gas flow generating means (16) for generating a gas flow so as to prevent the toner from adhering to the Faraday cage when the toner is discharged from the Faraday cage together with the high-pressure gas;
) A toner charge amount measuring device.