JP4684688B2 - Discharge unevenness observation device and observation method for sheet member, resistance measurement device and measurement method - Google Patents

Description

  The present invention relates to a discharge unevenness observation apparatus and observation method for inspecting discharge unevenness and resistance unevenness of a sheet member in a non-contact manner, and a sheet member resistance measurement apparatus and measurement method.

In an image forming process in a copying machine, a printer or the like, a toner image developed on a photoreceptor is transferred onto a transfer belt or paper by a transfer electric field formed between the photoreceptor and a transfer belt (including an intermediate transfer belt). The Therefore, it is very important to grasp the electrical characteristics when the transfer belt is manufactured or mounted on the image forming apparatus.
The electric characteristics of such a belt are measured based on the JIS K 6911 method, and are most commonly evaluated using surface resistivity and volume resistivity. As shown in FIG. 7, the surface resistivity is calculated by pressing an electrode (probe) 22 against the surface of the sample 21 and detecting the current flowing through the surface, and the volume resistivity is calculated as shown in FIG. It is obtained by measuring the current flowing between the electrodes 22 and 23.

As another surface resistance measurement method, Patent Document 1 discloses that three contact terminals are brought into contact with a member to be measured and two of the terminals are electrically connected to each other. A method for obtaining surface resistivity by measuring the resistance between the two as a combined resistance in parallel is disclosed.
On the other hand, it is empirically known that there is a certain degree of correlation between the surface resistivity or volume resistivity of the transfer belt and the transferred image, and many belt members that actively control these values have been proposed. Yes. For example, Patent Document 2 discloses that a transfer belt is composed of an inner layer made of rubber having a medium resistance, a dielectric layer, and a surface layer made of a material having a lower specific resistivity than that of the dielectric layer. It is disclosed that a good image can be obtained stably and at the same time. Further, in Patent Document 3, a plurality of types of carbons having different conductivity are dispersed so as to be unevenly distributed in the film thickness direction with respect to the resin, and the unevenness of the image is prevented by making the resistance of the belt surface higher than that of the back surface. An intermediate transfer belt manufacturing method has been proposed.

Japanese Utility Model Publication No. 3-63866 JP 7-295391 A Japanese Patent Laid-Open No. 11-109761

However, surface resistivity and volume resistivity are evaluated using millimeter-order electrodes and show macro electric characteristics. Therefore, the measured values of surface resistivity and volume resistivity are sufficient to complete the electric characteristics of the belt. Has a problem that cannot be grasped. Further, in the transfer process of the image forming apparatus, since the discharge generated between the belt and the photoconductor or between the belt and the transfer roller is an important factor, not only the resistance but also the surface roughness of the belt is actually large. It is known to affect.
Therefore, even if the toner on the photoconductor is transferred to a transfer belt or paper under the same conditions using a belt with the same surface resistivity and volume resistivity in a macro sense, it occurs in a halftone image. As a result, there are many problems such as uneven density and the tendency of images to be whitened out in some places (hereinafter referred to as white spots). As a result, in the development stage of an image forming apparatus, many belt samples have various conditions. Thus, it is necessary to perform a toner image transfer experiment and to extract a preferable belt by looking at the output image. From this situation, it is desirable to establish a more microscopic evaluation method for discharge characteristics and electrical characteristics, and at the same time, based on the knowledge obtained there, development of a good transfer belt that does not cause density unevenness or white spots Was requested.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned demands, and the problem is that a discharge unevenness observation apparatus and observation method for a sheet member that can evaluate microscopic discharge characteristics and electrical characteristics of a transfer belt, and resistance measurement. It is to propose an apparatus and a measuring method.

In order to solve the above-mentioned problems, the discharge unevenness observation device for a sheet member of the present invention has a transparent or semi-transparent electrode on the surface, and the electrode surface is arranged in a non-contact manner facing the surface of the sheet member to be observed A potential difference is provided between the electrode substrate, the counter electrode disposed in contact with the surface of the sheet member to be observed opposite to the surface facing the transparent electrode substrate, and the transparent electrode substrate and the counter electrode. And means for generating discharge light between the transparent electrode substrate and the sheet member to be observed, and photographing means for photographing the discharge light through the transparent electrode substrate .
In this case, it is preferable that a photoelectron multiplying means for doubling the intensity of the discharge light photographed by the photographing means is provided. The photographing unit is disposed behind the photoelectron multiplying unit, for example.
A plurality of the photomultiplier means may be arranged in series.
Furthermore, the photomultiplier can be an image intensifier.
Further, the surface roughness of the transparent electrode substrate is preferably 0.5 mm or less in terms of arithmetic average height R a.

According to the discharge unevenness observation method for a sheet member of the present invention, the electrode surface of a transparent electrode substrate having a transparent or translucent electrode on the surface is disposed in a non-contact manner facing the surface of the sheet member to be observed. The counter electrode is disposed in contact with the surface opposite to the surface facing the transparent electrode substrate, and a potential difference is provided between the transparent electrode substrate and the counter electrode to provide the transparent electrode substrate and the observed sheet member. The discharge light generated between the two and the other is photographed by the photographing means through the transparent electrode substrate, and the discharge unevenness generated in the observation sheet member is observed based on the photographing result.
In this case, it is preferable that after the discharge light generated between the transparent electrode substrate and the sheet member to be observed is multiplied by the photomultiplier, the image is taken by the photographing means.
Further, an AC bias may be applied in a superimposed manner between the transparent electrode substrate and the counter electrode.

The sheet member resistance measuring device of the present invention comprises a transparent electrode substrate having a transparent or semi-transparent electrode on the surface thereof, the electrode surface being disposed in a non-contact manner facing the surface of the resistance measuring sheet member, and the substrate A counter electrode disposed in contact with a surface opposite to the surface facing the transparent electrode substrate of the resistance measurement sheet member, and a potential difference is provided between the transparent electrode substrate and the counter electrode to provide the transparent electrode substrate. And means for generating discharge light between the resistance measurement sheet member and photographing means for photographing the discharge light through the transparent electrode substrate .
In this case, it is preferable that a photoelectron multiplying means for doubling the intensity of the discharge light photographed by the photographing means is provided. The photographing unit is disposed behind the photoelectron multiplying unit, for example.
A plurality of the photomultiplier means may be arranged in series. By arranging a plurality of the photomultiplier means in series, it is possible to measure even a slight resistance unevenness.
Furthermore, the photomultiplier can be an image intensifier. By using an image intensifier as the photoelectron multiplication means, it is possible to measure resistance or resistance unevenness with high sensitivity and high time resolution.
Further, the surface roughness of the transparent electrode substrate is preferably 0.5 mm or less in terms of arithmetic average height R a.

According to the sheet member resistance measuring method of the present invention, the electrode surface of the transparent electrode substrate having a transparent or translucent electrode on the surface is disposed in a non-contact manner facing the resistance measuring sheet member surface, and the resistance measuring sheet member A counter electrode in contact with the surface opposite to the surface facing the transparent electrode substrate,
An electric potential difference is provided between the transparent electrode substrate and the counter electrode, and the discharge light generated between the transparent electrode substrate and the resistance measurement sheet member is photographed by the photographing means through the transparent electrode substrate, and the discharge light The resistance of the sheet member is obtained based on the strength of the sheet.

In this case, the resistance of the sheet member may be obtained on the basis of image data photographed by the photographing means and a relational expression between the brightness of the discharge light and the sheet member resistance prepared in advance. Further, the image data photographed by the photographing means may be subjected to image processing to obtain the resistance of the sheet member.
Further, it is preferable that after the discharge light generated between the transparent electrode substrate and the resistance measurement sheet member is multiplied by a photomultiplier, the image is taken by the photographing means.
Furthermore, an AC bias may be applied in a superimposed manner between the transparent electrode substrate and the counter electrode.

  According to the discharge unevenness observation apparatus and observation method for a sheet member of the present invention, discharge unevenness generated in the sheet member can be efficiently observed with high sensitivity. Further, according to the sheet member resistance measuring apparatus and measuring method of the present invention, it is possible to efficiently detect the resistance or resistance unevenness of the sheet member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic view showing a discharge unevenness observation apparatus for a sheet member of the present invention. This discharge unevenness observation device for a sheet member places a sample sheet 1 cut out from a transfer belt or the like to be observed on a counter electrode 2, and applies a voltage to the counter electrode 2 from the outside to ground the sample sheet 1 and the ground. A discharge light is generated between the ITO (Indium-Tin-Oxide) electrode 7 as a transparent electrode substrate short-circuited to the electrode, and this discharge light is imaged through a mirror 5 provided behind the ITO electrode 7. The discharge image introduced into the tensiifier 4 and multiplied here is captured by a video camera 3 having a built-in CCD as a photographing means.

  In this device, two image intensifiers 4 (V1366P manufactured by Hamamatsu Photonics Co., Ltd.) are arranged in series to capture minute light emission, and an image is formed on the entrance side of each image intensifier 4 For this purpose, a lens 9 (PENTAX, smc PENTAX-A DENTAL MACRO 1: 4 100 mm) and a lens 10 (PENTAX, smc PENTAX-FA 1: 2.850 mm MACRO) are provided. The distance between the sample sheet 1 and the transparent electrode 7 is controlled to the order of 1 μm by moving the stage 8 using the stepping motor 12, and the stepping motor 12 is a stepping motor controller 13 (stepping motor controller manufactured by Suruga Seiki Co., Ltd.). D70) is controlled by the personal computer 14. Note that the bias applied to the electrode 2 is also controlled by the personal computer 14 via the amplifier 11 (manufactured by Trek, MODEL677A).

In this device, image intensifiers 4 with a maximum luminance gain of 6 × 10 ⁴ (ft-L / ft-c) are arranged in series to obtain a luminance gain that theoretically exceeds 3 × 10 ^9. We succeeded in visualizing fine discharge unevenness on the sample sheet with high time resolution. As a matter of course, any image intensifier can be used as long as it has a performance equal to or higher than this, and moreover, when observing rough discharge unevenness, It is also possible to use a low luminance gain.
In such a case, it is possible to observe only one image without arranging a plurality of image intensifiers, but at least a luminance gain of 1 × 10 ⁴ (ft-L / ft-c) or more is required. It is desirable to use an image intensifier with. For observation conditions that do not require time resolution, instead of using an image intensifier, a normal silver circle camera, CCD, or cooled CCD (for example, ST-6 manufactured by Santa Barbara Instrument Group) is used. It is also possible to observe discharge unevenness by extending the exposure time.

In this embodiment, an ITO electrode is used as the transparent electrode 7, but the electrode is not limited to this as long as the electrode has transparency. For example, gold, silver, copper, aluminum on a transparent material such as glass or plastic, It is also possible to use a material obtained by depositing various metals such as platinum, indium, and carbon on the nanometer order. However, in order to prevent the surface roughness of the transparent electrode from affecting the discharge unevenness of the sample sheet, it is necessary to use a transparent electrode having a small surface roughness. In this example, the arithmetic average based on JIS B 0601 By using a material having a height Ra of 0.5 mm or less, good discharge light observation was realized.
In this embodiment, the sample sheet 1 is fixed to the counter electrode 2 with a conductive double-sided tape. However, it is also possible to fix the sample sheet 1 using a conductive adhesive (for example, Dotite manufactured by Fujikura Kasei Co., Ltd.) or silver paste. is there. Furthermore, when the adhesiveness between the sample sheet 1 and the electrode 2 is sufficient, it is not necessarily fixed.

FIG. 2 is a schematic diagram showing the result of observing the discharge unevenness of the transfer belt samples A, B, and C using the sheet member discharge unevenness observation apparatus of this example. Samples A and B are polyimide belts in which conductive carbon is dispersed, and sample C is an ion conductive PVDF (polyvinylidene difluoride) belt. The distance between each sample sheet and the ITO electrode is constant at 20 μm, and the applied bias is Observations were made while changing. The white part is the region where strong discharge light was observed. As shown in the figure, it can be seen that by using the discharge unevenness observation apparatus of the present embodiment, the difference in electric field dependence of the discharge unevenness and its generation tendency can be clearly confirmed.
In the case where there is a region having a high resistance in the sample sheet or a layer having a high resistance on the back surface layer of the sheet and a continuous discharge does not occur with a DC bias, the counter electrode 2 By continuously generating a discharge by superimposing an AC bias having a large amplitude, it becomes possible to see the tendency of discharge unevenness. Therefore, it is very effective to use an AC bias when observing discharge unevenness. When observing discharge unevenness, it is desirable to measure the offset value of the DC bias component, the amplitude and frequency of the AC component under various conditions. Furthermore, by using optical filters such as various long-wavelength cut filters and bandpass filters, observation with reduced noise can be realized.

FIG. 3 is a diagram showing a sheet material resistance measurement method for obtaining the resistance of the sheet member based on the discharge light observation image photographed using the discharge unevenness observation apparatus for the sheet member shown in FIG. In a situation where a uniform electric field acts on the air gap between parallel plates, discharge occurs when the potential difference between the air gaps exceeds the discharge limit. Such discharge occurs between the sample sheet having a certain resistance and the electrode. In this case, the amount of discharge generated per unit time varies depending on the resistance, and the material having a higher resistance becomes smaller. That is, if the relationship between the light intensity of the discharge light generated in a constant electric field and the resistance is known in advance, the resistance of the sample sheet can be obtained from the observed intensity of the discharge light.
In the present embodiment, the discharge light generated on the sample sheet was observed using the discharge unevenness observation apparatus of FIG. 1, and the resistance of the sample sheet was calculated based on this. Note that image data taken by the video camera 3 shown in FIG. 1 is taken into the personal computer 14 in this embodiment. FIG. 4 is a diagram for explaining the operation flow of the sheet member resistance measuring apparatus employing the method of the present invention.

  In FIG. 4, first, information such as the thickness of the sample sheet, the distance from the ITO electrode, and the applied bias is input from the user via the keyboard of the personal computer attached to the sheet member resistance measuring device (step S1). When data is input from the user, the distance between the sample sheet and the ITO electrode is adjusted based on the input data (step S2). Next, a voltage is applied to the counter electrode in contact with the sample sheet to generate a discharge (step S3), a discharge image is captured by the CCD (step S4), and the captured discharge image data is transferred to a personal computer (step S5). ). The data transferred to the personal computer is converted into gray scale by image processing and converted into lightness information (step S6). Next, the resistance and resistance unevenness of the sample sheet are calculated from the obtained brightness value and a resistance-lightness curve prepared in advance (step S7).

According to this embodiment, the discharge unevenness of the sample sheet 1 can be observed with high sensitivity. In addition, since an AC bias is superimposed and applied between the transparent electrode substrate 7 and the counter electrode 2, discharge unevenness generated on the surface of the sheet member is observed even with respect to a sheet member that does not generate continuous discharge with the DC bias. be able to.
Further, according to the present embodiment, since a plurality of image intensifiers 4 are arranged in series, it is possible to observe even weak discharge unevenness and accurately observe discharge unevenness generated on the surface of the sheet member.
Furthermore, since the surface roughness of the transparent electrode substrate has an arithmetic average height Ra of 0.5 mm or less and has a smooth surface, it is possible to observe unevenness in the resistance of the sheet member and unevenness in discharge due to the shape alone. It becomes.

In the present embodiment, the light intensity of the actually generated discharge light needs to be proportional to the brightness of the captured image, so the luminance gain of the image intensifier must be constant. Therefore, it is difficult to apply the method of the present embodiment under the condition that the image intensifier automatically adjusts the luminance gain. For measurement conditions that do not require time resolution, use an ordinary silver circle camera, CCD, or cooled CCD instead of an image intensifier to observe discharge unevenness by increasing the exposure time. It is also possible to do.
In the present embodiment, if the surface roughness of the sample sheet at the time of resistance measurement is large, local discharge occurs at the convex portion of the sheet surface, making it difficult to correlate light intensity with resistance. The surface roughness of the sample sheet is desirably small, and the arithmetic average height based on JIS B 0601 is desirably 1.5 mm or less in terms of Ra. In this embodiment, it is also effective to suppress measurement noise other than the discharge light by using various optical filters such as a long wavelength cut filter and a band pass filter.

FIG. 5 is a view showing a modification of the discharge unevenness observation apparatus for sheet members in the present invention. In FIG. 5, this apparatus is not provided with a mirror, and space is saved by placing a lens 109, an image intensifier 104, a CCD camera 103, etc. perpendicular to the belt.
FIG. 6 is a view showing another modification of the discharge unevenness observation apparatus for sheet members in the present invention. In FIG. 6, this apparatus is provided with a roller for holding the belt so that discharge unevenness can be observed without cutting the sample sheet from the endless belt. The observation position can be changed by driving the roller. The distance between the belt and the ITO electrode 207 is adjusted by moving the position of the ITO electrode 207 with the stepping motor 212.

It is the schematic which shows the discharge nonuniformity observation apparatus of the sheet | seat member which concerns on this invention. It is a schematic diagram showing discharge unevenness observation results of transfer belt samples A, B, and C. It is a figure which shows the resistance measurement method of the sheet | seat material which calculates | requires resistance of a sheet | seat member based on the discharge light observation image image | photographed with the discharge nonuniformity observation apparatus. It is a figure explaining the operation | movement flow of the resistance measuring apparatus of the sheet | seat member which concerns on this invention. It is a figure which shows the modification of the discharge nonuniformity observation apparatus of the sheet | seat member in this invention. It is a figure which shows another modification of the discharge nonuniformity observation apparatus of the sheet | seat member in this invention. It is a figure which shows the surface resistivity measuring apparatus based on JISK6911 method. It is a figure which shows the volume resistivity measuring apparatus based on JISK6911 method.

Explanation of symbols

1, 101, 201: Sample sheet 2, 102, 202: Counter electrode 3, 103, 203: Video camera 4, 104, 204: Image intensifier 5: Mirror 6, 106: Fixing base 7, 107, 207: Transparent Electrode substrate (ITO electrode)
8, 108: Stage 9, 109, 209: Lens 10: Lens 11, 111, 211: Amplifier 12, 112, 212: Stepping motor 13, 113, 213: Stepping motor controller 14, 114, 214: Personal computer 21: Sample 22 : Front electrode 23: Back electrode 24: Guard electrode

Claims (18)

A transparent electrode substrate having a transparent or semi-transparent electrode on the surface, the electrode surface facing the surface of the observation sheet member and arranged in a non-contact manner, and the surface of the observation sheet member facing the transparent electrode substrate; Produces a discharge light between the transparent electrode substrate and the observed sheet member by providing a potential difference between the counter electrode arranged in contact with the opposite surface and the transparent electrode substrate and the counter electrode. A discharge unevenness observation apparatus for a sheet member, characterized in that the discharge member has a photographing means for photographing the discharge light through the transparent electrode substrate . 2. The discharge unevenness observation apparatus for a sheet member according to claim 1, further comprising photoelectron doubling means for doubling the intensity of the discharge light photographed by the photographing means. The discharge unevenness observation apparatus for a sheet member according to claim 2, wherein a plurality of the photomultiplier means are arranged in series. 4. The discharge unevenness observation apparatus for a sheet member according to claim 2, wherein the photomultiplier is an image intensifier. The surface roughness of the transparent electrode substrate is 0.5 m in terms of arithmetic average height R a.
The discharge unevenness observation device for a sheet member according to any one of claims 1 to 4, wherein m is 1 or less. The electrode surface of the transparent electrode substrate having a transparent or translucent electrode on the surface is disposed in a non-contact manner facing the surface of the observation sheet member, and is opposite to the surface of the observation sheet member facing the transparent electrode substrate the counter electrode was placed in contact with the surface, the transparent electrode discharge light generated between the object to be observed sheet member and the transparent electrode substrate provided with a potential difference between the counter electrode and the transparent electrode substrate A discharge unevenness observation method for a sheet member, characterized in that the discharge unevenness generated in the observed sheet member is observed based on the result of the image pickup by a photographing means through a substrate . The discharge of the sheet member according to claim 6, wherein the discharge light generated between the transparent electrode substrate and the observation sheet member is multiplied by the photomultiplier and then photographed by the photographing means. Unevenness observation method. The method for observing discharge unevenness of a sheet member according to claim 6 or 7, wherein an alternating current bias is applied in a superimposed manner between the transparent electrode substrate and the counter electrode. A transparent electrode substrate having a transparent or semi-transparent electrode on the surface, the electrode surface facing the surface of the resistance measurement sheet member and arranged in a non-contact manner, and the surface of the resistance measurement sheet member facing the transparent electrode substrate A counter electrode disposed in contact with the surface opposite to the surface to be connected, and a potential difference between the transparent electrode substrate and the counter electrode, and between the transparent electrode substrate and the resistance measurement sheet member An apparatus for measuring resistance of a sheet member, comprising: means for generating discharge light; and photographing means for photographing the discharge light through the transparent electrode substrate . 10. The sheet member resistance measuring device according to claim 9, further comprising photoelectron multiplying means for doubling the intensity of the discharge light photographed by the photographing means. 11. The sheet member resistance measuring apparatus according to claim 11, wherein a plurality of the photomultiplier means are arranged in series. 12. The sheet member resistance measurement apparatus according to claim 10, wherein the photomultiplier is an image intensifier. The surface roughness of the transparent electrode substrate is 0.5 m in terms of arithmetic average height R a.
The sheet member resistance measuring device according to any one of claims 9 to 12, wherein m or less. The electrode surface of the transparent electrode substrate having a transparent or translucent electrode on the surface is disposed in a non-contact manner facing the resistance measurement sheet member surface, and the surface of the resistance measurement sheet member facing the transparent electrode substrate is Disposing a counter electrode in contact with the opposite surface, providing a potential difference between the transparent electrode substrate and the counter electrode, and generating discharge light generated between the transparent electrode substrate and the resistance measurement sheet member A sheet member resistance measuring method, wherein the sheet member is photographed through the transparent electrode substrate and the resistance of the sheet member is obtained based on the intensity of the discharge light. 15. The sheet member according to claim 14, wherein the resistance of the sheet member is obtained based on image data photographed by the photographing means, and a relational expression between lightness of discharge light and sheet member resistance prepared in advance. Resistance measurement method. The sheet member resistance measurement method according to claim 14, wherein image data captured by the imaging unit is subjected to image processing to determine the resistance of the sheet member. After multiplied by the photomultiplier means the discharge light generated between the target resistance measurement sheet member and the transparent electrode substrate, any one of claims 14 to 16, characterized in that captured by the imaging unit 1 The sheet member resistance measurement method according to the item. Resistance measurement method of the sheet member according to any one of claims 14 to 17, characterized in that superimposed applying an AC bias between the counter electrode and the transparent electrode substrate.

Images