JP2001092220A - Device and method for measuring resistance value and distribution thereof with respect to conductive brush adopted for electrostatic photographic device or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and the method for measuring the resistance value distribution in the brush face of the conductive brush hair, in which a deviation of resistance value caused by the heat generation of a conductive brush hair can be prevented, with regard to a brush device of such as brush charging device and the brush transfer device. SOLUTION: The resistance value of a brush hair 11, coming in contact with a first electrode 21, is measured by making a specified current to flow between the first electrode 21 being in contact with the brush face 13 and the second electrode 23 being in contact with a conductive base body holding the brush face, and measuring the voltage value between these electrodes 21 and 23. Moreover, the measurement is performed by making the first electrode 21 shifted successively with regard to the brush face 13 by driving mechanisms 31 and 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device and a measuring method for measuring a resistance value and a distribution on a brush surface on which a large number of conductive brush bristles are erected, such as a brush charger and a brush transfer machine. About.

[0002]

2. Description of the Related Art As a brush device such as a charger in an electrophotographic image forming apparatus, a brush device having a large number of conductive brush bristles erected on a cylindrical or thin plate-shaped conductive substrate is used. .

When a rotary brush roll is used as a charger, there are the following problems (1) and (2).

[0004] 1. First, it is necessary to manage the resistance value of the brush roll.

[0005] For a brush on which a large number of conductive yarns are erected, a method is employed in which the average resistance value of the entire conductive yarn is measured and this resistance value is managed.

[0006] 2. Variations in the resistance value of the brush bristles in the rotation direction of the brush roll may cause variations in charging in the rotation direction. For this reason, a stripe pattern due to such variation in charging may appear on the obtained image, which has been a problem.

Also, when a flat fixed type brush device (flat type brush) is used as a charging device, it is necessary to manage the resistance value of the entire brush, and the photosensitive drum is exposed due to resistance unevenness in the longitudinal direction. There is a problem that image unevenness such as vertical streak unevenness occurs in an obtained image due to occurrence of charging unevenness in the body drum.

In recent image forming apparatuses, higher image quality is required even in black and white, and colorization is also desired. Therefore, it is necessary to suppress variation in charging by a charger. .

In view of this, it is conceivable to measure the distribution of resistance values on the brush surface of the brush device in advance and use only those having a resistance unevenness within a predetermined range. Alternatively, the measurement result of the resistance value distribution may be reflected in the manufacturing process of the brush device, or a process may be applied to the conductive brush in a predetermined area of the brush device.

Japanese Patent Application Laid-Open No. 6-29518 proposes a resistance value distribution measuring device for this purpose.

In the resistance value distribution measuring device disclosed in Japanese Patent Application Laid-Open No. Hei 6-29518, a moving electrode contacted with the tip of a conductive brush bristle for measuring a longitudinal resistance value distribution of a flat type brush is provided. A predetermined constant voltage is applied between the conductive electrode and the conductive substrate, and the current flowing while the moving electrode is sequentially moved in the longitudinal direction is measured.

[0012]

However, when the brush resistance value and the resistance value distribution are measured by such a conventional measuring device, the measured resistance value sometimes deviates greatly from the actual resistance value. The conductive brush bristles of the brush device
For example, since carbon black is spun after being dispersed in a thermoplastic resin, it reacts greatly to any deviation in measurement conditions.

[0013] That is, it was difficult to grasp the true resistance value of the brush. For example, the following problems are observed.

At the time of measuring the brush resistance, a method of calculating a resistance value by applying a constant voltage to the brush and calculating a current flowing through the brush is generally performed. However, the resistance value changes according to the applied voltage value.

When a resistance value is measured by applying a voltage, the resistance value itself changes, and a difference is seen in the resistance value between the measured brush and the brush not measured.

[0016] In the case of continuous measurement, the measured value changes over time.

The present inventors have conducted intensive studies on the causes of the above problems. As a result, when a constant voltage is applied, an excessive current flows through highly conductive brush bristle, and the resistance value is increased due to heat generation or the like. It was found that a major change was the cause. A conductive brush bristle generally used in a brush device such as a charger may have a resistance value shifted in a range of several orders of magnitude, so that a flowing current value and Joule heat due thereto may vary in a range of several orders of magnitude. That is, it has been found that the fluctuation of the current that causes a temperature change or the like, in particular, the excessive current that acts locally is a factor that hinders accurate measurement of the resistance value.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made in consideration of a brush device such as a brush charger and a brush transfer machine for measuring the resistance value and distribution of conductive brush bristles on a brush surface. In the apparatus and the measuring method,
Provided is a brush that can prevent deviation of a measured resistance value due to heat generation of a conductive brush bristle or the like.

[0019]

According to a first aspect of the present invention, there is provided a brush device such as a brush charger or a brush transfer device used in an electrophotographic apparatus, wherein the conductive material is provided on a brush surface on which a large number of conductive brush bristles are erected. In the measuring device for measuring the distribution of the resistance value of the conductive brush bristles, a first electrode in contact with the tip side of the conductive brush bristles and a rod-shaped or A second electrode that is in contact with the plate-shaped conductive substrate, a driving unit that relatively moves the brush surface and the first electrode, and a driving unit that moves the first electrode and the second electrode.
Constant current applying means for applying a constant current between the electrodes,
And a voltage measuring means for measuring a voltage value between the first electrode and the second electrode.

According to the above configuration, it is possible to prevent a deviation of the measured resistance value due to heat generation of the conductive brush bristles.

According to a second aspect of the present invention, in a brush device such as a brush charger or a brush transfer device used in an electrophotographic apparatus, the resistance value of the conductive brush bristles on a brush surface on which a large number of conductive brush bristles are erected. In a measuring device for measuring the distribution of the brush surface, a first electrode in contact with the tip side of the conductive brush bristles and a rod-shaped or plate-shaped conductive substrate holding the brush surface Second contact
An electrode, a driving unit that relatively moves the brush surface and the first electrode, a constant power applying unit that applies a constant power between the first electrode and the second electrode, And a measuring means for measuring a voltage value or a current value between the second electrode and the second electrode.

According to the above configuration, it is also possible to prevent a deviation of the measured resistance value due to heat generation of the conductive brush bristles.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A first embodiment of the present invention will be described below with reference to FIGS.

First, a brush device and an electrophotographic apparatus using the brush device according to the present embodiment will be described. In this embodiment, the electrophotographic apparatus is the printer shown in FIG. 1, and the brush apparatus is a rotary roll brush 10 used for a charger of the printer.

The printer is provided with a photosensitive drum 1 and is rotated counterclockwise by a driving device (not shown). Around the photosensitive drum 1, a brush charging device 2, an exposure device 3, a developing device 4, a transfer charger 5, and a separation charger 6 are sequentially arranged.

The brush charging device 2 is a contact charging device using a roll brush 10. This roll brush 10
The photosensitive drum is rotated in a clockwise or counterclockwise direction in contact with the photosensitive drum, and a DC voltage or a voltage obtained by superimposing a DC voltage on an AC voltage is applied by a power supply 8. The brush charging device 2 charges the surface of the photoconductor drum 1 negatively or positively in this manner.

As shown in FIG. 2, the roll brush 10 of this embodiment is formed by spirally winding a ribbon tape-like brush body 14 around a mandrel roller 12. Brush body 1
4 is a conductive yarn 18 constituting the brush bristles 11 on the base cloth 16.
Is made by pile weaving with a wide weave along the longitudinal direction.

Next, the resistance value measuring apparatus of this embodiment will be described with reference to the schematic diagram of FIG.

The flat first electrode 21 is brought into contact with the brush bristles 11 of the roll brush 10 so as to reach a certain depth,
The second electrode 23 is brought into contact with the mandrel roller 12 of the roll brush 10. A constant current I from a constant current source flows between the electrodes 21 and 23.

In the roll brush 10, the distribution density of the conductive brush bristles 11 is the same at any part, so that the number of the conductive brush bristles 11 in contact with the first electrode 21 is substantially equal.

Therefore, when measuring the resistance value, a constant current flows through each bristle 11.

On the other hand, the holding member 37a for holding the mandrel roller 12 is provided with a rotation drive mechanism 37 for sequentially rotating the roll brush 10. Therefore, it is possible to measure the distribution of the resistance values in the rotation direction of the roll brush 10 and the average value of the resistance values.

The personal computer 30 obtains the above-described resistance value distribution from the position data on the brush surface 13 based on the signal from the driving mechanism 37 and the resistance value measured in association with the data, and the standard deviation thereof is obtained. And so on.
Then, for example, it is possible to select only the roll brush 10 whose standard deviation value is equal to or less than a certain fixed value and use it for an electrophotographic apparatus or the like.

In this embodiment, the current value between the first and second electrodes 21 and 23, which are the measurement electrodes, is kept constant by the constant current source, and the current value flowing through each brush bristle 11 is set to a substantially constant small value. Thereby, the generation of Joule heat at the time of resistance value measurement can be suppressed, and the deviation of the resistance value due to the temperature rise can be suppressed. The magnitude of the current flowing during measurement is
According to the type, thickness, and distribution density of the brush bristles 11, an appropriate value for accurate measurement is set. For example, it can be set based on a value already experimentally obtained for the same kind of brush bristles 11.

FIG. 4 is a graph showing the relationship between the amount of current flowing at the time of measurement and the deviation of the resistance value. The horizontal axis represents the current per denier flowing through the filaments forming the brush bristles 11, and the vertical axis represents the difference between the resistance value immediately after the start of the resistance measurement and the resistance value after a certain time (after 1 minute). That is, the change amount of the resistance value is taken. The current flowing per denier is plotted on the abscissa because various yarns having different thicknesses are used for the yarns forming the brush hairs 11.

As can be seen from FIG. 4, when the current per denier is 0.2 × 10 ⁻³ μA or less, no deviation in the resistance value is observed, and as the current increases beyond this value, the resistance value increases. The amount of deviation increases.

Therefore, the electric current flowing through the conductive yarns constituting the brush device is set to a value of 0.1 per denier of each filament.
By measuring the resistance value using a measurement system of 2 × 10 ⁻³ μA or less, it is possible to accurately measure the resistance value without the difficulty of grasping the resistance value, which has conventionally been a problem.

In the measuring apparatus shown in FIG. 3, if the number of brush bristles 11 in contact with the first electrode 21 is 100,000 and the thickness of the monofilament yarn forming the brush bristles 6 is 6 denier, 0.2 × 10 ^{− 3} μA × 100,000 × 6 = 120 μ
A Therefore, in the case of the present embodiment, an accurate resistance value can be obtained by measuring using a constant current source of 120 μA or less.

<Second Embodiment> In the first embodiment, the first electrode 21 and the second electrode 21 are replaced with a constant current I by a constant current source.
A constant electric power is applied between the electrodes 23.

As shown in FIG. 5, the voltage between the electrodes 21 and 23 is measured by the voltmeter 52, and the voltage between the electrodes 21 and 23 is measured.
3 are measured by an ammeter 54,
It is converted to a digital value 28 by a / D converter and input to the personal computer 30. The personal computer 30 calculates a power value based on the product of the input current value and voltage value, and adjusts the power generation device 50 so that the power value becomes constant.

Even in such a method, by setting the amount of electric power flowing through the brush bristles 11 within an appropriate range, it is possible to prevent the heating of the brush bristles 11 and the deviation of the resistance value caused by the heating.

<Third Embodiment> As shown in FIG. 6, the resistance value distribution measuring device of the present embodiment measures the resistance value distribution in the flat brush 15. The flat type brush 15 is obtained by sticking a ribbon tape-shaped brush body 14 similar to that used for the roll brush 10 on an electrode base 17 made of aluminum or the like with a conductive adhesive or the like.

In the resistance value distribution measuring device of the present embodiment, instead of the rotary drive mechanism 37 for rotating the brush, an axial drive for sequentially moving the first electrode 21 along the longitudinal direction of the flat brush 15 is used. A mechanism 31 is provided.
In the example shown, the drive mechanism 31 includes a ball screw 35,
It is a combination of a nut and a servomotor.

Also, the first electrode 21 that contacts the brush surface
Has a front end surface having a ridge-like curved surface, that is, a convex curved surface extending in the width direction of the brush surface. The other points are completely the same as those of the resistance value distribution measuring apparatus of the first embodiment.

At the time of resistance value distribution measurement, the first electrode 21 that is in contact with the brush surface 13 is sequentially moved in the longitudinal direction by the axial driving mechanism 31.

Also in this embodiment, similarly to the first embodiment, by making the value of the current flowing through each brush bristle 11 a substantially constant small value, the generation of Joule heat during this measurement can be suppressed. The deviation of the resistance value due to the temperature rise can be suppressed.

Further, by the processing using the personal computer 30,
Resistance value distribution in the longitudinal direction of the flat type brush 15,
And a standard deviation can be calculated.

In the first embodiment, only the resistance and the distribution of resistance in the rotating direction of the roll brush 10 are measured. However, the first electrode 21 is reduced in size, and the driving mechanism 31 in the longitudinal direction is similar to that of the third embodiment.
Thus, the first electrode 21 can be moved in the axial direction of the roll brush 10 to measure the resistance value distribution of the roll brush 10 in the axial direction. By providing the drive mechanisms 31 and 37 in the axial direction and the rotation direction, the distribution of the resistance value on the entire brush surface 13 of the roll brush 10 can be measured. In this case, needless to say,
It is possible to obtain only the distribution of the resistance value in the rotation direction at a certain axial position, or to obtain only the distribution of the resistance value in the axial direction at a certain rotation position.

On the other hand, in the third embodiment, the resistance value can be measured by applying a constant power similarly to the second embodiment, instead of applying a constant current.

In the above, the case where the conductive brush is used for charging has been described.
In an electrophotographic apparatus, it is used for transfer, static elimination, cleaner, etc. in addition to charging. The resistance value management of the present invention is also useful for conductive brushes for these applications.

[0051]

According to the present invention, there is provided an apparatus and method for measuring a resistance value and a resistance value distribution of a conductive brush bristle on a brush surface of a brush device such as a brush charger and a brush transfer machine.
Provided is a brush that can prevent deviation of a measured resistance value due to heat generation of a conductive brush bristle or the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a printer.

FIG. 2 is an explanatory view of a roll brush in which a brush body is spirally wound around a mandrel roll.

FIG. 3 is a schematic diagram of a measuring apparatus according to a first embodiment.

FIG. 4 is a graph showing the relationship between the amount of current flowing during measurement and the amount of change in resistance.

FIG. 5 is a circuit diagram between electrodes of a second embodiment.

FIG. 6 is a schematic diagram of a measuring apparatus according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Roll brush 11 Brush bristles 12 Mandrel roll 21 1st electrode 23 2nd electrode 26 Voltmeter 31 Axial drive mechanism 37 Rotation drive mechanism

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor: Pawaji 1723 Kitadawara-cho, Ikoma City, Nara Prefecture Toei Sangyo Co., Ltd. F-term (reference) 2G028 AA01 CG02 DH13 FK01 HN09 JP01 MS03 2G060 AA09 AE01 AF09 EA04 EA06 EA06 EA07 2H003 BB11 BB16 CC06 EE11 EE12 2H032 AA05

Claims (7)

[Claims] In a brush device such as a brush charger or a brush transfer device used in an electrophotographic apparatus, a resistance value and a resistance value distribution of the conductive brush bristles on a brush surface on which a large number of conductive brush bristles are erected are determined. In the measuring device for measuring, for each partial area of the brush surface, a first electrode contacting the tip side of the conductive brush bristle, and a first electrode contacting a rod-shaped or plate-shaped conductive base holding the brush surface. Two electrodes; a driving unit that relatively moves the brush surface and the first electrode; a constant current applying unit that applies a constant current between the first electrode and the second electrode; A voltage measuring means for measuring a voltage value between the first electrode and the second electrode. 2. A brush device such as a brush charger or a brush transfer device for use in an electrophotographic apparatus, wherein a resistance value and a resistance value distribution of the conductive brush bristles on a brush surface on which a large number of conductive brush bristles are erected are determined. In the measuring device for measuring, for each partial area of the brush surface, a first electrode contacting the tip side of the conductive brush bristle, and a first electrode contacting a rod-shaped or plate-shaped conductive base holding the brush surface. Two electrodes; a driving unit that relatively moves the brush surface and the first electrode; a constant power applying unit that applies a constant power between the first electrode and the second electrode; and the first electrode. A measuring device for measuring a voltage value or a current value between the first electrode and the second electrode. 3. The measuring device according to claim 1, wherein a current of 0.2 × 10 ⁻³ μA or less per denier is applied to the yarn forming the conductive brush hair. 4. The measuring device according to claim 1, wherein a surface of the first electrode that contacts the conductive brush bristles is a flat surface or a curved surface protruding toward the brush surface. 5. The measurement according to claim 1, wherein the brush device is a rotary roll brush, and the driving means has a rotation driving function for driving the brush surface along a rotation direction. apparatus. 6. A brush device such as a brush charger or a brush transfer device for use in an electrophotographic apparatus, wherein a resistance value and a resistance value distribution of the conductive brush bristles on a brush surface on which a large number of conductive brush bristles are erected are determined. In the measuring method for measuring, for each partial area of the brush surface, a first electrode contacting a tip side of the conductive brush bristle, and a first electrode contacting a rod-shaped or plate-shaped conductive base holding the brush surface. Applying a constant current between the two electrodes and measuring a voltage value between the first electrode and the second electrode while relatively moving the brush surface and the first electrode. Measurement method to be performed. 7. In a brush device such as a brush charger or a brush transfer device used in an electrophotographic apparatus, a resistance value and a resistance value distribution of the conductive brush bristles on a brush surface on which a large number of conductive brush bristles are erected are determined. In the measuring method for measuring, for each partial area of the brush surface, a first electrode contacting a tip side of the conductive brush bristle, and a first electrode contacting a rod-shaped or plate-shaped conductive base holding the brush surface. Measuring a voltage value or a current value between the first electrode and the second electrode while applying a constant power between the two electrodes and relatively moving the brush surface and the first electrode; A measuring method characterized by the following.