JP6509020B2 - Method of observing the surface shape of the object to be measured - Google Patents

Description

  The present invention relates to a method of observing the surface shape of an object to be measured when a contact member is brought into contact with the surface of an object to be measured provided with a resin layer having convex portions on the surface.

  There is known a charging member in which the discharge performance is stabilized by forming fine projections on the surface. Here, in the contact portion of the charging member with the object to be charged such as an electrophotographic photosensitive member, the convex portion of the charging member is deformed, and the degree of the deformation affects the charged state of the member to be charged. I know. However, so far, it has not been possible to accurately know the degree of deformation of the charging member at the contact portion. Therefore, in order to optimize the surface shape for the further improvement of the charging performance of the charging member, it is effective to accurately know the three-dimensional shape of the surface of the charging member in the contact state.

Heretofore, several methods for observing the contact state in two dimensions have been proposed, and Patent Document 1 observes the contact point at the contact portion between the generally observed object and the contact member. It is a method. The observation object and the prism are brought into contact with each other, and light is made incident from the prism side at an angle of total reflection with respect to the contact portion. At the contact portion, the luminance is reduced due to the absorption of light, and at the non-contact portion, the light is totally reflected from the back surface of the contact member.
Thereby, the contrast of the contact portion is improved, and the contact area can be observed. Further, Patent Document 2 discloses a method and apparatus for observing the contact portion between the observation object and the contact member in the liquid which is considered to be difficult by the method described in Patent Document 1. In the method and apparatus disclosed in Patent Document 2, coaxial illumination is employed to observe the contact portion, an antireflective film is attached to one surface of the contact member, and reflected light at the interface between the contact member and the liquid is detected. By reducing it, the contrast of the contact portion is improved.

  Although Patent Document 1 and Patent Document 2 are planar methods for evaluating the contact area and the contact point size as the contact state, both Patent Document 1 and Patent Document 2 apply the observation object and the contact member. When brought into contact, it is not possible to simultaneously observe non-contacting portions on the surface of the observation object. This is because the amount of reflected light from the non-contacting portion of the contact member is large. Therefore, it has been considered difficult to observe the three-dimensional shape in the contact state.

Patent No. 3381445 Unexamined-Japanese-Patent No. 2010-107467

  An object of the present invention is to provide a method of observing the surface shape of an object to be measured when the contact member is brought into contact with the surface of the object to be measured provided with a resin layer having convex portions on the surface.

According to the present invention, there is provided a method of observing the surface shape of an object to be measured when the contact member is brought into contact with the surface of the object to be measured provided with a resin layer having convex portions on the surface as the surface layer. A method of observing the surface shape of an object to be measured is provided, which comprises the following steps (1) to (3).
(1): A step of preparing a contact member satisfying the following conditions (i) to (iii):
(I) 90% or more of the transmittance of the entire visible light range based on Japanese Industrial Standard (JIS) R 3106 1998;
(Ii) The visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on at least one surface is the visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on the surface of the object to be measured Less than 80%;
(Iii) When the highest reflectance shown at wavelength λ1 in the visible light wavelength range is R1% and the lowest reflectance shown at wavelength λ2 in the visible light wavelength range is R2% on the surface, R1 And the difference between R2 and 0.5% or more;
(2) bringing the surface side of the contact member into contact with the surface of the object to be measured;
(3) A step of causing light containing the wavelength λ1 and the wavelength λ2 to be incident from the surface opposite to the surface of the contact member, and spectrally detecting the reflected light of the light from the object to be measured.

  According to the present invention, it is possible to observe the surface shape of the object to be measured when the contact member is brought into contact with the surface of the object to be measured provided with the resin layer having the convex portion on the surface as the surface layer. .

It is a schematic diagram for demonstrating the method to observe a contact state in three dimensions. It is a figure which shows the result of having observed the cross section of the to-be-measured object before contact | abutting in Example 1, and after contact | abutting. It is a figure which shows the result of having observed the surface of the to-be-measured object before contact | abutting in Example 1, and after contact | abutting. It is a figure which shows the result of having observed a contact state in the comparative example 1. FIG. It is a figure for demonstrating the reflected light from a contact part, and the reflected light from a non-contact part.

  FIG. 1 is a schematic view showing a method of observing the three-dimensional shape of the surface of an object to be measured in the contact state according to the present invention. In the following, the elastic roller 1 having the rubber elastic layer 2 as the resin layer on the metal shaft (core metal 3) is described as an example of the object to be measured. However, known methods such as polishing and roughening particle addition are described. As long as it is a to-be-measured object provided with the resin layer which has a convex part on the surface by this as a surface layer, it is not the limitation. In the example shown in FIG. 1, the contact member 4 is composed of the transparent plate 5 and the anti-reflection film 6, and the anti-reflection film 6 is provided on the surface on which the elastic roller 1 is in contact.

<Abutment state observation method>
A method of observing the three-dimensional shape of the surface of the object in the contact state with respect to the elastic roller 1 will be described.
This observation method is
(1) preparing a contact member 4 to be brought into contact with the elastic roller 1;
(2) bringing the surface of the contact member 4 into contact with the surface of the elastic roller 1;
(3) Allowing light containing wavelength λ1 and wavelength λ2 to be incident from the surface of the contact member 4 on the opposite side to the elastic roller 1, and spectrally detecting the reflected light of the light from the elastic roller 1.

As shown in FIG. 5, “the reflected light from the non-contacting portion of the contact member 4 and the elastic roller 1” is transmitted through the non-contacting portion 52 of the anti-reflection film 6 and the rubber elastic layer 2 to prevent reflection. After passing through the space between the surface of the film 6 and the surface of the rubber elastic layer 2, the light reflected by the surface of the rubber elastic layer 2 is included in a large amount.
On the other hand, “the reflected light from the contact portion between the contact member 4 and the elastic roller 1” is transmitted through the non-contact portion 52 between the antireflective film 6 and the rubber elastic layer 2. After passing through the space between the surface of the rubber elastic layer 2, it hardly contains the light reflected by the surface of the rubber elastic layer 2.

<Step of preparing contact member>
First, the process of preparing the contact member 4 to be in contact with the elastic roller 1 will be described.
The abutting member 4 satisfies the conditions (i) to (iii).
(I) 90% or more of the transmittance of the entire visible light range based on Japanese Industrial Standard (JIS) R 3106 1998;
(Ii) The visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on at least one surface is the visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on the surface of the object to be measured Less than 80%;
(Iii) When the highest reflectance shown at wavelength λ1 in the visible light wavelength range is R1% and the lowest reflectance shown at wavelength λ2 in the visible light wavelength range is R2% on the surface, R1 The difference between R2 and R2 is 0.5% or more:

For example, the contact member 4 includes the transparent plate 5 and the anti-reflection film 6 on the surface of the transparent plate 5 on the side of the object to be measured.
The transparent plate 5 is a transparent plate having a transmittance of 90% or more over the entire visible region (including light of wavelength λ1 and wavelength λ2) based on Japanese Industrial Standard (JIS) R 3106 1998.

The reflection preventing film 6 is based on Japanese Industrial Standard (JIS) R 3106 1998, and the reflectance on the elastic roller (object to be measured) side of the contact member is visible light on the surface of the elastic roller 1 over the entire visible light range. It is 80% or less of the lowest reflectance among the area reflectances.
That is, assuming that the reflectance of the surface of the elastic roller 1 is 100%, the reflectance of the antireflective film 6 on the elastic roller 1 side is the highest reflectance in the visible light region. The rate is less than 80.

The reflectance of the contact member on the side of the object to be measured is the highest at the wavelength λ1 in the wavelength range of visible light, and the reflectance at this time is referred to as the reflectance R1.
The reflectance of the contact member on the side of the object to be measured is the lowest at the wavelength λ2 within the wavelength range of visible light, and the reflectance at this time is the reflectance R2,
The difference between the reflectance R1 and the reflectance R2 is 0.5% or more.

Examples of the material of the transparent plate 5 include glass, resin, and the like having a transmittance of 90% or more in the visible light wavelength range (wavelength 450 nm to 700 nm), and light of wavelength λ1 and wavelength λ2 of light used. It is not particularly limited as long as the transmittance is high.
With regard to the antireflective film 6, there are a film type, a single layer film type, a multilayer film type and the like, and any may be used.

It is preferable that the antireflective film 6 be provided on both sides of the contact member, because the observation sensitivity is further improved. The reason why the observation sensitivity is better is as follows.
The anti-reflection film 6 applied to the surface of the contact member on the side to be irradiated with the light (the side on which the light is incident; the side opposite to the surface to be in contact with the object to be measured) It is possible to suppress the influence of the reflected light on the surface on the side of
The antireflection film 6 applied to the surface of the contact member on the side of reflecting light is
Intensity of light reflected from the contact portion between the contact member and the elastic roller;
The difference between the intensity of the reflected light from the non-contacting portion between the contact member and the elastic roller can be increased.

<Step of bringing the contact member into contact with the object to be measured>
Next, the process of bringing the surface side of the contact member into contact with the surface of the object to be measured will be described.
When the anti-reflection film 6 is provided on the side of the contact member 4 to be measured (elastic roller 1), the surface of the anti-reflection film 6 and the surface of the elastic roller 1 are brought into contact with each other.
For example, the metal shafts (core metal 3) at both ends of the elastic roller 1 are pressed in the direction of the contact member 4. Here, the contact load is not particularly limited, and is preferably a condition close to actual use conditions. For example, in the case of the elastic roller for electrophotography mentioned in the first embodiment, it may be 1000 g or less per side.

<Step of Distinguishing and Detecting the Reflected Light from the Contact Part and the Reflected Light from the Non-Contact Part>
Next, the elastic roller 1 is irradiated with light including the wavelength λ1 and the wavelength λ2 through the contact member 4 to make the light incident. Then, the reflected light from the contact portion between the contact member 4 and the elastic roller 1 and the light reflected by the surface of the elastic roller 1 after passing through the non-contact portion between the contact member 4 and the elastic roller 1 The process of distinguishing and detecting (spectral detection) will be described.

  First, the elastic roller 1 is irradiated with light including the wavelength λ1 and the wavelength λ2 through the contact member 4. The light transmitted through the contact member 4 is reflected light at the interface between the contact member 4 and the elastic roller, at the intensity of the wavelength λ1 and the wavelength λ2 corresponding to the reflectance R1 and reflectance R2 of the contact member on the elastic roller side. And transmitted light. The light transmitted through the contact member is reflected by the surface of the elastic roller 1, and then again reflected light and transmitted light with an intensity of wavelength λ1 and wavelength λ2 corresponding to the reflectance R1 and reflectance R2 by the anti-reflection film. It is divided.

According to the present invention, the surface of the elastic roller 1 can be observed by using an anti-reflection film in which the reflectance on the elastic roller side of the contact member is 80% or less of the reflectance of the surface of the elastic roller 1 did.
Further, by making the reflectance R1 and the reflectance R2 have a difference of 0.5% or more, the reflected light from the contact portion or non-contact portion between the surface of the elastic roller 1 and the surface of the contact member is included. An intensity difference is generated between the components of the wavelength λ1 and the wavelength λ2.

In particular,
The wavelength λ1 corresponding to the highest reflectance R1 is relatively long, and the wavelength λ2 corresponding to the lowest reflectance R2 is relatively short. That is, the wavelength λ1 is longer than the wavelength λ2.
The light incident on the non-contact portion repeats irregular reflection within the concave portion on the surface of the elastic roller 1 and attenuates. Relatively, the light of the wavelength λ1 is attenuated because the wavelength is long, and the light of the wavelength λ2 is not attenuated because the wavelength is short.
And when incident light which entered into a non-contacting part from a contact member enters into a contact member again as reflected light, reflectance R1 of light of wavelength λ1 is high, reflectance R2 of light of wavelength λ2 is low Therefore, it is difficult for the light of wavelength λ1 to be incident again, and the light of wavelength λ2 is likely to be incident again.
As a result, the reflected light from the non-contacting part contains λ2 having a short wavelength more than the λ1 having a long wavelength, and it is possible to observe the contacting part and the non-contacting part by spectral detection. .

  By observing the intensity difference between the wavelength λ1 and the wavelength λ2 by the wavelength separation and observation means 7 that detects the reflected light, it is possible to distinguish the contact portion and the non-contact portion between the elastic roller 1 and the contact member 4 It was possible. Here, it is preferable that the wavelength separation observation means 7 be an area camera capable of color imaging. For example, there is a 3CCD camera that separates the reflected light into three colors of red, green and blue.

  According to this observation method, it is possible to distinguish and observe the contact portion and the non-contact portion between the elastic roller 1 and the contact member 4 according to the wavelength (color on the color image). Therefore, it becomes possible to clearly distinguish and observe the difference in the contact depending on the size of the roughening particles added to the rubber elastic layer 2 of the elastic roller 1, the difference in the surface roughness of the rubber elastic layer 2, etc. . That is, the contact state (contact area or three-dimensional shape in the nip) at the contact portion between the member to be charged and the elastic roller 1 can be optimized by the material to be added.

  Further, part of the light reaching the contact portion is absorbed by the surface of the elastic roller 1. For this reason, when the resin layer which is the surface layer of the elastic roller 1 contains a material excellent in the absorption of light having a short wavelength such as carbon black, the reflected light of the contact portion contains a lot of light having a long wavelength. . As a result, when the spectral detection is performed, the contrast between the contact portion and the non-contact portion becomes higher.

  Furthermore, when the white confocal microscope listed in Example 1 is used as the wavelength separation observation means 7, as described with reference to FIGS. 2 and 3, the three-dimensional shape of the contact portion is directly measured. It becomes possible. In addition to the conventional contact area, parameters such as in-nip roughness, space volume, and in-nip height can be measured, and the contact state at the contact portion between the member to be charged and elastic roller 1 (contact area) And the three-dimensional shape in the nip) can be optimized.

  As described above, according to the present observation method, the amount of light reflected from the contact member is reduced by the effect of the anti-reflection film, and the characteristics of the anti-reflection film against the reduction in contrast between the contact portion and the non-contact portion generated at this time The contrast can be added as a difference in color by selecting the observation wavelength and the observation wavelength. For example, when the wavelength λ1 is in the red band, as shown in FIG. 3B, it can be observed that the contact portion is red and the non-contact portion is bluish green. As a result, for example, in a charging member for electrophotography such as a charging roller having a convex portion derived from roughening particles on the surface, in the contact portion between the charging member such as an electrophotographic photosensitive member and the charging member The degree of deformation of the charging member can be accurately detected. Therefore, it is possible to optimize the surface shape for further improvement of the charging performance of the charging member.

Example 1
(Production of elastic roller)
The elastic roller as a to-be-measured object provided with the resin layer was produced in the following procedure.
An unvulcanized rubber composition containing NBR (acrylonitrile butadiene rubber) and spherical silica particles was prepared. Then, the unvulcanized rubber composition is coaxially formed into a cylindrical shape centering on a cylindrical stainless steel core metal 5 having a diameter of 5 mm and a length of 250 mm using an extrusion molding apparatus using a crosshead, It pushed out simultaneously with the core metal 3. Thus, an unvulcanized rubber roller having a diameter of 8.8 mm in which the unvulcanized rubber composition was coated on the outer periphery of the core metal 3 was produced.
Both ends in the width direction of the unvulcanized rubber composition layer of the molded unvulcanized rubber roller were cut, and the axial length of the unvulcanized rubber composition layer was 226 mm.

Thereafter, the layer was heated in an electric furnace to vulcanize the unvulcanized rubber composition layer to form a vulcanized rubber layer. Subsequently, the surface of the vulcanized rubber layer is polished with a plunge grinding type polishing machine, and a vulcanized rubber in which a part of crown-shaped spherical particles having an end diameter of 8.35 mm and a central diameter of 8.50 mm is exposed A vulcanized rubber roller having a layer was obtained.
The surface of the resulting vulcanized rubber roller after polishing was cured by irradiating it with an electron beam to obtain an elastic roller 1 having convex portions on the surface.

(Measurement of surface roughness)
The ten-point average roughness Rz of the surface of the elastic roller was measured. The measurement was performed based on JIS B0601: 1982 using a surface roughness measuring device (trade name: Surfcoder SE3400, manufactured by Kosaka Laboratory Ltd.). A diamond contact needle with a tip radius of 2 μm was used for the measurement. The measurement speed was 0.5 mm / sec, the cutoff frequency λc was 0.8 mm, the reference length was 0.8 mm, and the evaluation length was 8.0 mm. The measurement was carried out by measuring the roughness curve for each of six points at three points in the axial direction × two points in the circumferential direction to calculate the value of Rz, and the average value of Rz at these six points was determined to obtain the value of Rz. As a result, Rz was 15 μm.

(Measurement of the three-dimensional shape of the object when the member is in contact with the surface of the object)
In the method of observing the shape of the contact state shown in FIG. 1, the contact member provided with the following anti-reflective film on both surfaces of the following glass plate was used.
Glass plate (BK7, manufactured by Sigma Kouki Co., Ltd.): A transmittance of 90% or more in a wavelength range of 450 nm to 700 nm.
Antireflection film (WBMA coat, Sigma light machine Co., Ltd.):
The reflectance on the elastic roller side of the contact member in the wavelength range of 450 to 700 nm is
The highest reflectance is 0.7% at a wavelength (λ1) of 700 nm,
The lowest reflectance is 0.1% at a wavelength (λ2) of 450 nm,
The difference between the highest reflectance and the lowest reflectance is 0.5% or more.
In the step of distinguishing and detecting the reflected light from the contact part and the reflected light from the non-contact part, the contact state was observed using a white confocal microscope (OPTELICS HYBRID, Lasertec Co., Ltd.).
The observation results are shown in FIG. 2 and FIG. The magnification of the image in FIG. 3 is 20 times for both (a) and (b).

Here, since the lowest reflectance in the visible light region of the surface of the elastic roller is about 1%, the reflection preventing film having a reflectance of about 0.7% on the elastic roller side in the abutting member at a wavelength of 700 nm is used. By using it, the value of following formula (1) is made into 80% or less.
(The reflectance of the contact member on the side of the object to be measured, which is the highest reflectance in the visible light region) / (the reflectance of the surface of the object to be measured, the lowest reflectance in the visible light region) × 100 [%] ... Formula (1)

FIG. 3A is a surface observation image of the elastic roller before the elastic roller and the contact member abut.
FIG. 2A is a shape profile showing an outline of a cross section of the elastic roller at the position of a line 31 shown at the center of the image of FIG. 3A before the elastic roller and the contact member abut.
FIG. 3B is a surface observation image of the elastic roller after the elastic roller and the contact member abut (in contact).
FIG. 2 (b) shows the cross-sectional profile of the elastic roller at the position of the line 32 shown in the center of the image of FIG. 3 (b) after the elastic roller and the contact member abut (during contact) It is a shape profile shown.

  On the observation image, the contact portion and the non-contact portion of the elastic roller and the contact member can be distinguished by the wavelength (corresponding to the color on the color image). In addition, comparing before and after the abutment, it can be confirmed that the convex portion on the surface of the elastic roller is deformed by the abutment and that many of the concave portions do not abut (do not deform).

The non-contacting part is a part that appears dark gray in a grayscale image and a part that appears bluish green or green in a color image.
The abutments are locations that appear light gray in gray scale images and locations that appear red in color images.
Moreover, a convex part is a white point surrounded by a black spot where it looks like wrinkles, wrinkles or irregular lines.
Recesses are all locations except for the protrusion.
Table 1 shows the results of whether or not the contact portion and the non-contact portion are observed, and whether or not the three-dimensional shape of the elastic roller in the contact portion can be measured.

Example 2
Evaluation was carried out in the same manner as in Example 1 except that the following antireflection films were used on both surfaces of the contact member of the contact mechanism.
Antireflective film:
The reflectance on the elastic roller side of the contact member in the wavelength range of 450 to 700 nm is
The highest reflectance is 0.7% at a wavelength (λ1) of 520 nm,
The lowest reflectance is 0.1% at a wavelength (λ2) of 450 nm,
The difference between the highest reflectance and the lowest reflectance is 0.5% or more.

Here, since the lowest reflectance in the visible light region of the surface of the elastic roller is about 1%, the reflection preventing film having a wavelength of 520 nm and the reflectance on the elastic roller side of the abutting member being about 0.7% is used. By using, the value of said Formula (1) is made into 80% or less.
It was confirmed that the contact portion and the non-contact portion between the elastic roller and the contact member were distinguished by the wavelength (color on the color image), and that the shape change before and after the load could be measured.
Table 1 shows the results of whether or not the contact portion and the non-contact portion are observed, and whether or not the three-dimensional shape of the elastic roller in the contact portion can be measured.

[Example 3]
Evaluation was carried out in the same manner as in Example 1 except that the following antireflection films were used on both surfaces of the contact member of the contact mechanism.
Antireflective film:
Among the reflectances on the elastic roller side of the contact member in the wavelength range of 450 to 700 nm,
The highest reflectance is 0.7% at a wavelength (λ1) of 470 nm,
The lowest reflectance is 0.1% at a wavelength (λ2) of 700 nm,
The difference between the highest reflectance and the lowest reflectance is 0.5% or more.

Here, since the lowest reflectance in the visible light region of the surface of the elastic roller is about 1%, an antireflection film having a reflectance of about 0.7% on the elastic roller side in the abutting member at a wavelength of 470 nm is used. By using, the value of said Formula (1) is made into 80% or less.
It was confirmed that the contact portion and the non-contact portion between the elastic roller and the contact member were distinguished by the wavelength (color on the color image), and that the shape change before and after the load could be measured.
Table 1 shows the results of whether or not the contact portion and the non-contact portion are observed, and whether or not the three-dimensional shape of the elastic roller in the contact portion can be measured.

Comparative Example 1
Evaluation was performed in the same manner as in Example 1 except that a glass plate having a transmittance of 90% or more in the wavelength range of 400 nm to 700 nm without using the anti-reflection film on either of the two surfaces was used.
As a result, as shown in FIG. 4, since the amount of light reflected from the contact portion is larger than the amount of light reflected from the non-contact portion, the contact portion can be observed. It was confirmed that observation of the contact area and shape measurement could not be performed.
Table 1 shows the results of whether or not the contact portion and the non-contact portion are observed, and whether or not the three-dimensional shape of the elastic roller in the contact portion can be measured.

1. Elastic roller 2. Rubber elastic layer 3. Core metal 4. Abutment member 5. Transparent plate 6. Anti-reflection film 7. Means of wavelength separation observation

Claims (9)

A method for observing the surface shape of an object to be measured when a contact member is brought into contact with the surface of an object to be measured having a resin layer having convex portions on the surface as a surface layer,
A method of observing the surface shape of an object to be measured, which comprises the following steps (1) to (3):
(1): A step of preparing a contact member satisfying the following conditions (i) to (iii):
(I) 90% or more of the transmittance of the entire visible light range based on Japanese Industrial Standard (JIS) R 3106 1998;
(Ii) The visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on at least one surface is the visible light reflectance based on Japanese Industrial Standard (JIS) R 3106 1998 on the surface of the object to be measured Less than 80%;
(Iii) When the highest reflectance shown at wavelength λ1 in the visible light wavelength range is R1% and the lowest reflectance shown at wavelength λ2 in the visible light wavelength range is R2% on the surface, R1 And the difference between R2 and 0.5% or more;
(2) bringing the surface side of the contact member into contact with the surface of the object to be measured;
(3) A step of causing light containing the wavelength λ1 and the wavelength λ2 to be incident from the surface opposite to the surface of the contact member, and spectrally detecting the reflected light of the light from the object to be measured. In the step (3),
The method for observing the surface shape of the object to be measured according to claim 1, comprising the step of measuring the three-dimensional shape of the object to be measured with a confocal microscope using the light of the wavelength λ2.   The observation method of the surface shape of the to-be-measured object of Claim 1 or 2 in which the said resin layer contains carbon black.   The method of observing the surface shape of the object to be measured according to any one of claims 1 to 3, wherein the contact member has an antireflective film on at least one surface.   The method according to claim 4, wherein the contact member has an anti-reflection film on both sides.   The wavelength range of the said visible light is 450 nm or more and 700 nm or less, The observation method of the surface shape of the to-be-measured object as described in any one of Claims 1-5.   The method according to any one of claims 1 to 6, wherein the wavelength λ1 is longer than the wavelength λ2.   The process according to any one of claims 1 to 7, wherein the step (3) includes the step of spectrally detecting the reflected light of the light from the object to be measured using a 3 CCD camera that separates the light into three colors of red, green and blue. The observation method of the surface shape of the to-be-measured object as described in one term.   9. The method of observing the surface shape of the object to be measured according to any one of claims 1 to 8, wherein the object to be measured is a charging member for electrophotography having a convex portion on the surface.