JP2000266794A - Surface potential measuring method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect precisely a surface potential, even if the surface potential is a high potential. SOLUTION: In this measuring method of a potential on a sample surface by using a potential detecting probe, a probe P vibrating in parallel with the sample surface is used as the potential detecting probe. And a surface potential of the sample S is measured by the operation of an electrostatic force working between charges on the probe P and on the sample S, by utilizing the change of the vibrating state of the probe P. This device is equipped with such a potential detecting probe P that the probe P head facing to the sample S surface is supported vibratingly in parallel with the sample S surface, a vibration exciting device A for vibrating forcedly the probe P, and a vibration state detecting means (PD, K) for detecting the change of the vibrating state of the probe P, and the surface potential of the sample S is measured by utilizing the variation of the vibrating state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a surface potential of an object to be measured, and more particularly to a method and an apparatus suitable for measuring a sample having a high potential.

[0002]

2. Description of the Related Art An electrophotographic method used in a copying machine, an LBP (laser beam printer), or the like includes a step of uniformly charging the surface of an electrophotographic photosensitive member by corona discharge or the like; An exposure step of exposing the surface to form an electrostatic latent image on the photoreceptor surface, and contacting a developer with the formed electrostatic latent image to convert the electrostatic latent image into a toner image with toner contained in the developer. A developing process for developing a visible image, a transfer process for transferring the toner image to paper or the like, a fixing process for fixing the transferred toner image, and a cleaning process for removing the toner remaining on the photoconductor after the transfer process. Contains. The images in this process are based on an electrostatic latent image formed on a photoreceptor. Therefore, in order to obtain a high-definition image, a high-definition electrostatic latent image must be formed and developed.

[0003] However, the developed image may cause a decrease in resolution due to changes in environmental conditions such as temperature and humidity and the constituent materials of the photoreceptor. One of the causes of such a phenomenon is deterioration of a latent image. Therefore, in order to design a photosensitive member having excellent stability that does not depend on the environment or the like, it is necessary to directly measure an electrostatic latent image to grasp the state of the latent image. Generally, in order to measure the surface potential of a charged sample or the like, a means for bringing a measurement electrode close to the sample and measuring an induced charge induced on the measurement electrode at that time is used. That is, when a capacitance is formed between the sample and the measurement electrode by bringing the measurement electrode close to the sample, an induced charge corresponding to the electrostatic charge on the sample is induced on the measurement electrode. For example, the following technology (J0
1) and (J02) are known.

(J01) Technology shown in FIG. 19 FIG. 19 is an explanatory diagram of a conventional surface potential measuring method. FIG.
9, a transparent detection electrode 02 is provided in a shield case 01 having a light transmission hole 01a and a detection hole 01b.
From the light transmission hole 01a. The light L passes through the transparent electrode 02 and the detection hole 01b provided on the opposite wall surface,
The sample (measured object) S is irradiated. (J02) Technology described in Japanese Patent Application Laid-Open No. 6-88846. This publication proposes a method of installing an optical fiber around a detection electrode and measuring a surface potential of a light irradiation part.

[0005]

[Problems to be Solved by the Invention] ((J01), (J
Problem 2)) The above-mentioned prior arts (J01) and (J02) measure the amount of induced charge of the detection electrode. In this method, it is necessary to reduce the size of the measurement electrode in accordance with the minute portion. As the size of the measurement electrode decreases, the amount of induced charge induced in proportion to the area of the electrode decreases, so that the absolute value of the signal amount to be detected decreases. Therefore, in consideration of the characteristics of the signal processing system such as the S / N ratio, the size of the measurement electrode cannot be reduced infinitely but has a limit. Therefore, it is extremely difficult to measure a minute part by the method of measuring the amount of induced charge.

Therefore, the following technology (J03) has been proposed. (J03) Technique shown in FIG. 20 FIG. 20 is an explanatory view of another conventional technique for measuring the surface potential, which is disclosed in Japanese Patent Application Laid-Open Nos. Hei 5-1-19093 and Hei 5-149.
988, JP-A-6-3398, or the journal of the Society of Electrophotography, Vol. 32, No. 4, P62-66 (1993). In FIG. 20, the probe 06 is supported at the tip of a cantilever (cantilever) 07,
Laser light L from laser light source 08 on the back of cantilever 07
And the electrostatic force generated between the sample S and the cantilever 07 causes the mechanical displacement of the cantilever 07 or the cantilever 0
The surface potential is measured by detecting the change in the vibration of 7 by the light quantity sensor 09 by detecting the reflected light L ′ of the laser light L applied to the back surface of the cantilever 07.

However, in this case, when the voltage is on the order of several volts, the electrostatic force acting between the probe 06 at the tip of the cantilever 07 and the sample S is not so large.
The distance can be reduced to several μm or less. However, for a sample S such as a photoreceptor to which a high voltage of several hundreds to several kilovolts is applied, the probe 06 supported on the tip of a cantilever 07 displaced in a direction perpendicular to the sample S requires Then, the probe 06 and the sample 07 come into contact with each other due to a large electrostatic force. If the probe 06 and the sample S are separated to such an extent that they do not come into contact with each other, the resolution is reduced. Further, even if a material that does not easily bend the probe 06 is selected and contact with the sample due to the electrostatic force is avoided, the sensitivity decreases with the material that does not easily bend.

In view of the above circumstances, the present invention provides the following (O01)
Is the subject of the description. (O01) To be able to accurately detect the surface potential even if the surface potential is high.

[0009]

DISCLOSURE OF THE INVENTION The present invention aims at measuring a minute portion of a sample (S) having a high potential, and a probe (P) forcibly vibrated in parallel with a sample surface and the probe (P). Using the vibration state detection means (PD + K) for measuring the vibration state of (P),
This is possible and realized. When a potential detection probe (P) vibrated in parallel with the sample surface by an external force is forcibly brought close to the sample (S) having a potential distribution, an induced charge is induced in the probe (P). At this time, for example, if a probe (P) having a sharpened tip such as a needle is used, the induced charge is induced at the tip.

FIG. 1 is a diagram showing an example of a probe usable in the present invention, and FIGS. 1A to 1C are diagrams showing probes having different shapes. The probe (P) is induced by the induced charge induced on the probe (P) and the charge on the sample surface.
Since electrostatic force acts between the sample (S) and the probe (P)
Will be subjected to shear stress. As a result, the natural frequency, vibration amplitude or phase of the probe (P) changes. Since the amount of change in the natural frequency, vibration amplitude or phase changes according to the electrostatic force acting on the probe (P), measuring the natural frequency, vibration amplitude or phase reduces the electrostatic force, that is, the potential of that portion. You can know. Further, since the vibration direction of the probe (P) is parallel to the sample surface, measurement can be performed even at a high potential without contact between the probe (P) and the sample (S). As the shape of the probe (P), the shape shown in FIG. 1 can be used, but it is not necessarily limited to this. Further, the size of the tip of the probe (P) is 50 mm in diameter.
μm or less, preferably 10 μm or less in diameter, more preferably 5 μm or less.
It is more preferable to use m or less.

As a method for forcibly oscillating the probe (P), the probe (P) is connected to a piezoelectric element (A) or a quartz oscillator, and the frequency corresponds to the natural frequency of the piezoelectric element (A) or the quartz oscillator. A method of vibrating by applying a piezoelectric pulse at a frequency, or applying a heat pulse at a frequency corresponding to the natural frequency to a part of the probe (P) with a laser beam, a heating element, etc., to cause thermal expansion according to the frequency There is a method of causing vibration, but the method is not limited to this. As a means for detecting a change in vibration of the probe (P), a method of irradiating the probe (P) with light and detecting the interference light by a photodiode (PD), or a method using a quartz oscillator, There is a method of detecting a change in the natural frequency of the device, but the method is not limited to this. By using the above method, electrostatic charge, induced charge,
Sample with potential distribution due to dipole polarization (S)
If so, it can be a measurement target in the present invention.

[0012]

FIG. 2 is an explanatory view of a method of measuring the surface potential of a sample by vibrating a probe and changing the vibration state. In FIG. 2, the sample (S) is supported on a Z-direction moving device (Tz) that can be adjusted vertically (position in the Z-axis direction). The Z-direction moving device (Tz) is supported by an X-direction moving device (Tx) movable in an X-axis direction perpendicular to the Z-axis, and the X-direction moving device (Tx) is supported by the Z-axis and the X-axis. It is supported by a Y-direction moving device (Ty) that can move in the vertical Y-axis direction. The Z-direction moving device (T
Z), X direction moving device (Tx) and Y direction moving device (T
y) are the Z table drive (Dz), the X table drive (Dx), and the Y table drive (Dy), respectively.
Driven by The Z table drive (D
z) includes a device for driving the coarse movement table and a circuit for driving the fine movement table.

The tip of the probe (P) is arranged close to the surface of the sample (S), and the upper end of the probe (P) is oscillated in a direction perpendicular to the plane of FIG. It is possible that the probe (P) vibrates in a direction perpendicular to the plane of the paper. Light emitted from the light source (K) crosses the vibrating probe (P) and is detected by the optical sensor (PD). The detection signal of the optical sensor (PD) is input to the vibration state detection device (U1), and the vibration state detection device (U1) detects the vibration state of the probe (P).

If the sample (S) is in the form of a card, an X-direction moving device (Tx) and a Y-direction moving device (Ty)
Can use a piezoelectric element, an electromagnetic motor or the like as a drive source. If the sample (S) is disk-shaped, a rotating mechanism and a moving device toward the center of rotation can be used instead of the X-direction moving device (Tx) and the Y-direction moving device (Ty). If the sample (S) has a cylindrical shape such as a drum, the X-direction moving device (Tx) and the Y-direction moving device (T
Instead of y), a rotating mechanism and a moving device in a direction parallel to the rotation axis can be used. The Z-direction moving device (T
z) can be driven by a piezoelectric element, an electromagnetic motor or the like.

The X-direction moving device (Tx), the Y-direction moving device (Ty) and the Z-direction moving device (Tz) are an X-direction control device (Ux), a Y-direction control device (Uy), and a Z-direction control device (Uy), respectively. ) And drive-controlled. Note that the X-direction moving device (Tx), the Y-direction moving device (Ty), and the Z-direction moving device (Tz) can be constructed by assembling each of the divided devices, or integrally by a piezoelectric element or the like. It is possible. The X-direction moving device (Tx), the Y-direction moving device (Ty), and the Z-direction moving device (Tz) may be configured to move the probe (P) instead of moving the sample (S). It is possible. Further, for example, the sample (S) can be moved by the X-direction moving device (Tx) and the Y-direction moving device (Ty), and the probe (P) can be moved by the Z-direction moving device (Tz). It is.

The vibration excitation device (A) vibrates the probe (P) at its natural frequency. Use a piezoelectric element or the like as a means to vibrate, and use a probe (P)
Alternatively, the piezoelectric element is vibrated by connecting it to a probe fixing jig and applying a piezoelectric pulse to the piezoelectric element at a frequency corresponding to the natural frequency. Further, there is a method of applying a heat pulse at a frequency corresponding to the natural frequency to a part of the probe (P) with a laser beam, a heating element, or the like, and causing thermal expansion according to the frequency to cause vibration. Here, the material of the probe (P),
The form may be any as long as the induced charge is induced when the probe (P) is placed in a field where an electric field is present, and the vibration state is changed by the action of the charge on the sample (S) and the electrostatic force. For example, a conductive metal such as gold, tungsten, and nickel can be used. The shape may be, for example, a wire shape or a plate shape as shown in FIG. 1, but is not limited thereto.

When the sample (S) and the vibrating probe (P) are brought close to each other by the Z-direction moving device (Tz) and the probe (P) is brought close to a distance where the electrostatic force acts, the probe (P) The vibration state changes due to the electrostatic force. The change in the vibration state of the probe (P) includes a change in the natural frequency of the probe (P), a change in the amplitude of the vibration of the probe (P), a change in the phase of the probe (P), and the like. As the phase change, for example, a change in a phase difference between the cycle of the vibration driving voltage and the cycle of the vibration of the probe (P) can be used. The change in the vibration state is detected by the vibration state detection device (U1). For example, when the change in the vibration state is a change in the frequency, the change in the frequency is detected by the vibration state detection device (U1). The vibration state detection device (U1) uses the probe (P)
When the light is irradiated from an arbitrary side direction, the light interfered by the probe (P) can be constituted by a device for detecting the frequency of the probe (P) by an optical sensor (PD) or the like.

The signal detected by the vibration state detection device (U1) is sent to a signal processing device, and the potential distribution can be measured by converting the vibration state signal into a potential on the surface of the sample (S). With the X-direction moving device (Tx) and the Y-direction moving device (Ty), the potential at an arbitrary position on the sample (S) can be known. The signal processing device (U2)
For example, a recorder, a computer, or the like can be used.

After measuring at an arbitrary position, the potential distribution of the sample (S) is measured by scanning the sample (S) with the X-direction moving device (Tx) and the Y-direction moving device (Ty). Can be. As a scanning method, after measuring one point, move to the next position, measure after stopping,
In addition to the intermittent scanning method described above, a method of performing measurement in a state where the measurement is continuously performed without stopping is also possible.

In the embodiment of the present invention, the change in the natural frequency and the change in the amplitude of the probe due to the electrostatic force acting when approaching a sample having a potential distribution using the probe (P) for potential detection. Or the change of the phase, and the conventional induction from the control amount when controlling the distance between the probe and the sample and the bias voltage between the probe and the sample so that the state of the probe is not changed by the action of the electrostatic force. The surface potential can be measured with high resolution beyond the method of directly measuring the electric charge.

(Examples) Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples. (Embodiment 1) FIG. 3 is an explanatory view of Embodiment 1 of the surface potential measuring apparatus of the present invention. In FIG. 3, the sample S is supported on a Z table Tz (Z-direction moving device) that can be adjusted vertically (position in the Z-axis direction). The Z table Tz
Has a coarse movement Z table (not shown) that can be raised and lowered by a motor, and a fine movement Z table made of a piezoelectric material supported on the coarse movement Z table P, and the sample S is placed on the upper surface of the fine movement Z table. It is configured to be supported. The Z
The table Tz is supported by an X table (X direction moving device) Tx movable in the X axis direction perpendicular to the Z axis, and the X table Tx is movable in the Y axis direction perpendicular to the Z axis and the X axis. Supported by a simple Y table (Y-direction moving device) Ty. The Z table Tz, the X table Tx, and the Y table Ty are respectively Z table driving devices Dz, X
It is driven by a table driving device Dx and a Y table driving device Dy. Incidentally, the Z table driving device Dz
Comprises a device for driving the coarse Z table and a circuit for driving the fine Z table. Each of the driving devices Dz, Dx, Dy is controlled by a computer C.

The tip of the probe P is arranged close to the surface of the sample S, and the upper end of the probe P is supported by a piezoelectric body (vibration excitation device) A. The piezoelectric body A is driven by a piezoelectric body drive circuit DA, and can vibrate in a direction perpendicular to the plane of FIG. 3, and the probe P vibrates in a direction perpendicular to the plane of paper in response to the vibration of the piezoelectric body A. The light emitted from the laser diode LD passes through the vibrating probe P through the optical fiber Fb, and
Is detected by The detection signal of the photodiode PD is AM
The signal is amplified by P (amplifier) and input to the lock-in amplifier LA.

The amplitude value or phase value measured by the lock-in amplifier LA is input to the computer C. The computer C changes the frequency of the piezoelectric body drive circuit DA so that the amplitude value is returned to the maximum amplitude value or the phase is returned to 0 ° based on those values. The computer C
Stores the position coordinates of the X table Tx and the Y table Ty and the fixed frequency of the probe P corresponding to the position coordinates.

(Operation of Embodiment 1) FIG. 4 is a graph showing an example of the relationship between the surface potential (V) of the sample and the natural frequency (Hz) of the probe P. Since the relationship in FIG. 4 differs depending on the configuration of the probe P and the piezoelectric body A, etc., the relationship as shown in FIG. The surface potential corresponding to the XY coordinate position can be obtained from the detected natural frequency of the probe P. When the sample S and the vibrating probe P are brought close to each other by the Z table (Z direction moving device) Tz, and the probe P is brought close to a distance where the electrostatic force acts, the natural frequency of the probe P becomes the surface potential of the sample S. (That is, the strength of the electrostatic force) (see FIG. 4). The change in the natural frequency is detected based on the vibration amplitude or phase input to the lock-in amplifier.
The computer C changes the frequency of the piezoelectric driving circuit so that the optimum natural frequency is obtained, and inputs the frequency to the computer. The computer C
Is capable of measuring the potential distribution on the sample surface by plotting the input natural frequency against the coordinate position on the sample surface.

(Embodiment 2) FIG. 5 is an explanatory view of Embodiment 2 of the surface potential measuring apparatus according to the present invention, in which the surface potential of a charged sample surface and the portion of the charged sample surface irradiated with light are shown. A device for measuring the surface potential of the portion (corresponding to the electrostatic latent image on the surface of the photoreceptor of the image forming apparatus) and the surface potential of the portion not irradiated with light (background portion of the electrostatic latent image) (deterioration of the charged latent image) FIG. In the description of the second embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The second embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 5, above the Z table Tz,
Charger CC for charging the surface of sample S on Z table Tz
And an exposure light source LD for exposing the charged surface of the sample S.
2 and a slit SL are arranged.

(Operation of Example 2) As a sample S, a plate-shaped aluminum substrate having a photosensitive layer formed thereon was used. The sample S was manufactured as follows. On a plate-shaped aluminum substrate, 10 parts of a zirconium compound (trade name: Organix ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) and 1 part of a silane compound (trade name: Al110, manufactured by Nippon Unicar Co., Ltd.), 40 parts of i-propanol and butanol 20 Part solution is applied by a dip coating method.
It was dried by heating at 50 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.1 μm. Next, 8 parts of a dibromoanthrone pigment and a carboxyl-modified vinyl chloride
A mixture of 2 parts of a vinyl acetate copolymer (trade name: VMCH, manufactured by Union Carbide Co., Ltd.) and 100 parts of butanol was subjected to dispersion treatment with glass beads for 1 hour by a sand mill, and the obtained coating solution was applied on the undercoat layer. The resultant was applied by a dip coating method and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of about 1 μm.

Next, as a charge transporting material, a coating solution obtained by dissolving 6 parts of a benzidine compound of the following structural formula (see Chemical Formula 1) and 9 parts of bisphenol (Z) polycarbonate in 85 parts of monochlorobenzene was used. Coated on the charge generation layer, dried by heating at 115 ° C. for 60 minutes,
A charge transport layer having a thickness of about 20 μm was formed. As described above, a photosensitive layer was formed on a plate-like aluminum substrate.

Embedded image

The sample S was charged to -8 in a dark place by a charger CC.
After being charged to 00 V, the X table Tx or the Y table Ty was moved, a part of the sample S charged by the exposure light source LD2 and the slit SL was irradiated in a line, and the electrostatic charge was removed to form an electrostatic latent image. . Subsequently, the X table Tx or the Y table Ty is moved so that the vicinity of the boundary between the exposed portion and the non-exposed portion is below the probe P. Subsequently, the distance between the sample S and the probe P is controlled by the Z table driving device Dz to perform measurement. A change in the natural frequency of the probe P is taken into the computer C, converted into a surface potential, and the surface potential is plotted with respect to position information on the XY plane of the sample S whose position is controlled by the computer C. The result as shown in FIG. 6 was obtained. FIG. 6 is a diagram showing the potential of the electrostatic latent image in the region of 50 μm in the X direction and 50 μm in the Y direction on the sample surface. As can be seen from FIG.
The surface potential of the sample S can be measured with high accuracy from a low potential to a high potential.

(Embodiment 3) FIG. 7 is an explanatory view of Embodiment 3 of the surface potential measuring apparatus of the present invention. The surface potential of a sample in a state where the surface of the sample is charged and the surface of the charged sample is irradiated with light. FIG. 5 is an explanatory diagram of a device (a device for measuring the deterioration of a charged latent image) for measuring a change in surface potential of a portion (corresponding to an electrostatic latent image on the surface of a photoconductor of an image forming apparatus). In the description of the third embodiment, components corresponding to the components of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The third embodiment differs from the second embodiment in the following points, but has the same configuration as the second embodiment in other points. In FIG. 7, above the Z table Tz, a charger CC for charging the surface of the sample S on the Z table Tz is arranged at the same position as in FIG. 5 of the second embodiment. Further, an exposure light source LD2 for exposing the charged surface of the sample S and a stop SB are arranged, and an exposure position of the light passing through the stop SB coincides with a measurement position of the sample surface by the probe P.

(Operation of Embodiment 3) As sample S, two kinds of samples, sample α and sample β, were used. (Sample α) Sample α is the same sample as sample S in which the photosensitive layer was formed on the plate-like aluminum substrate used in Example 2 above. (Sample β) Sample β is a sample in which a protective layer is formed on the surface of sample α.

The protective layer was formed for the following purpose. Commercially available hard coat material KP-854 (Shin-Etsu Silicone Co., Ltd.) 20
The mixture was mixed with 10 parts of a charge transporting material represented by the following structural formula (see Chemical formula 2), 1 part of 1N hydrochloric acid, and 15 parts of isopropanol to prepare a coating solution. This coating solution was applied onto the sample α by a blade coating method, and dried at 120 ° C. for 1 hour to form a surface protective layer having a thickness of 3 μm.

Embedded image

First, the sample S (sample α) is held on the Z table Tz and charged to −800 V in a dark place by the charger CC, and then the sample S (sample α) is driven by the X table driving device Dx or the Y table driving device Dy. The X table Tx or the Y table Ty is moved so that the sample α) comes under the probe P. At that position, the surface potential of the sample S (sample α) is measured.

Next, the surface of the sample S (sample α) below the probe P is irradiated with laser light to eliminate the charge. The change in the potential of the charge eliminating section is detected from the change in the natural frequency of the probe P, taken into the computer C, converted into a surface potential, and the change with time is plotted. In addition, the sample β was measured in the same manner. FIG. 8 shows the results. FIG. 8 is a diagram showing changes with time of the surface potential of the charged state of sample α and sample β and the surface potential after exposure, and is a diagram showing a measurement example of latent image deterioration.

(Embodiment 4) FIG. 9 is an explanatory view of Embodiment 4 of the surface potential measuring device, showing an embodiment in which the probe P is vibrated and the potential distribution of the sample is measured from a change in the vibration amplitude. . In the description of the fourth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be omitted. The fourth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 9, an amplitude is detected from an input signal by an amplitude measuring device SS and output to the computer C. Further, the computer C directly outputs a control signal to the piezoelectric driving circuit DA.

(Operation of Embodiment 4) FIG. 10 is a graph showing an example of the relationship between the surface potential (V) of the sample and the oscillation amplitude voltage (V) of the probe P. Since the relationship in FIG. 10 differs depending on the configuration of the probe P, the piezoelectric body A, and the AMP, etc.,
By previously obtaining the relationship shown in FIG. 10 according to the probe P and the piezoelectric body A to be used, the sample S
The surface potential corresponding to the XY coordinate position of the surface
Can be obtained from the vibration amplitude voltage. When the sample S and the probe P in the vibrating state are approached by the Z table (Z direction moving device) Tz, and the probe P is brought close to a distance where the electrostatic force acts on the probe P, the vibration amplitude of the probe P depends on the strength of the electrostatic force. (See FIG. 10). The amplitude is measured by an amplitude measuring device S constituted by a lock-in amplifier.
Measured by S. The vibration amplitude information obtained by the amplitude measuring device (lock-in amplifier SS) is processed by a signal processing program of the computer C. Computer C
Converts the input signal (amplitude information) into the surface potential of the sample S, and plots the surface potential with respect to the position coordinates of the surface of the sample S, thereby measuring the potential distribution on the surface of the sample S.

(Embodiment 5) FIG. 11 is an explanatory view of Embodiment 5 of the surface potential measuring apparatus, showing an embodiment in which the probe P is vibrated and the potential distribution of the sample is measured from a change in the phase. In the description of the fifth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be omitted. The fifth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 11, output signals of the piezoelectric body drive circuits DA and AMP are input to a phase measurement device IS constituted by a lock-in amplifier,
Phase measuring device I constituted by the lock-in amplifier
S detects the phase difference between the two input signals and outputs it to the computer C. Further, the computer C directly outputs a control signal to the piezoelectric driving circuit DA.

FIG. 12 shows the phase difference between the surface potential (V) of the sample and the vibration of the probe (the phase difference between the vibration excitation signal for vibrating the probe and the vibration detection signal of the probe). It is a graph showing an example of the relationship with (degree). The relationship shown in FIG. 12 differs depending on the configuration of the probe P and the piezoelectric body A, etc.
By previously obtaining the relationship as shown in FIG. 12 in accordance with the above, the surface potential corresponding to the XY coordinate position of the surface of the sample S can be changed by the change in the phase of the detected vibration of the probe P (for example, when the probe is vibrated). (A change in the phase difference between the vibration excitation signal for causing the vibration and the vibration detection signal of the probe). When the sample S and the probe P in a vibrating state are brought close to each other by the Z-direction moving device Tz and approached to a distance where the electrostatic force acts on the probe P, the phase change amount of the probe P (for example, vibration excitation for vibrating the probe P) The amount of change in the phase difference between the signal and the vibration detection signal of the probe differs depending on the strength of the electrostatic force (see FIG. 12). A phase measurement device I constituted by a lock-in amplifier
Measured by S. The phase information obtained by the phase measuring device IS is processed by a signal processing program of the computer C. The computer C receives the input signal (phase difference information)
Is converted into the surface potential of the sample S, and the surface potential is plotted with respect to the position coordinates of the surface of the sample S.
The potential distribution on the surface can be measured.

(Embodiment 6) FIG. 13 is an explanatory view of Embodiment 6 of the surface potential measuring apparatus. A change in the natural frequency of the probe P is detected, and a change between the sample and the probe is maintained so as to keep the value constant. FIG. 5 is a diagram showing an embodiment in which the bias voltage is controlled and the potential distribution is measured from the control amount. In the description of the sixth embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The sixth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points. In FIG. 13, the output signal of the lock-in amplifier LA of the first embodiment is input to the computer C, and is input from the computer C to the bias voltage control device BD. The bias voltage control device BD includes a probe P and a sample S
During this time, a bias voltage is applied.

(Effect of Embodiment 6) The natural frequency of the probe P changes due to the electrostatic force caused by the interaction between the probe P and the sample S, and the amount of this change applies a bias voltage between the probe P and the sample S. It is also caused by things. That is, even if the surface potential of the sample S is the same, the magnitude of the electrostatic force acting on the probe differs depending on the external bias voltage. In the bias voltage control device BD, when a frequency different from the initially set natural frequency is input from the lock-in amplifier LA to the computer C, the probe P and the sample S are set so as to have the initially set natural frequency. Is controlled. This control amount corresponds to the surface potential of the sample S. The control amount signal is sent to the computer C,
Here, it is converted into the surface potential of the sample S.

(Embodiment 7) FIG. 14 is an explanatory view of Embodiment 7 of the surface potential measuring device. A change in the vibration amplitude of the probe P is detected, and the change between the sample and the probe is maintained so that the value is kept constant. FIG. 9 is a diagram showing an embodiment in which a bias voltage is controlled and a potential distribution is measured from the control amount. In the description of the seventh embodiment, components corresponding to the components of the sixth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The seventh embodiment differs from the sixth embodiment in the following points, but is otherwise the same as the sixth embodiment. In FIG. 14, an output signal of the AMP is input to an amplitude measuring device SS configured by a lock-in amplifier,
The amplitude measuring device SS detects the amplitude from the input signal and outputs it to the computer C and the bias voltage control device BD. The computer C directly outputs a control signal to the piezoelectric driving circuit DA and the bias voltage control device BD.

(Operation of the Seventh Embodiment) The vibration amplitude of the probe P changes due to the electrostatic force caused by the interaction between the probe P and the sample S. The amount of this change is determined by applying a bias voltage between the probe P and the sample S. It is also caused by That is, even if the potential is the same on the sample S, the magnitude of the electrostatic force acting on the probe P differs depending on the external bias voltage. In the bias voltage control device BD, the amplitude different from the initially set vibration amplitude is supplied from the vibration amplitude measurement device SS constituted by the lock-in amplifier to the computer C.
, The bias voltage between the probe P and the sample S is controlled so that the vibration amplitude set at the beginning is obtained.
This control amount corresponds to the surface potential of the sample S. The control amount signal is sent to the computer C, where it is converted into a potential on the sample surface.

(Embodiment 8) FIG. 15 is an explanatory view of an embodiment 8 of the surface potential measuring device. A change in the phase of the probe P is detected, and the bias voltage between the sample and the probe is maintained so as to keep the phase constant. FIG. 6 is a diagram showing an embodiment in which the control is performed and the potential distribution is measured from the control amount. In the description of the eighth embodiment, the same reference numerals are given to the components corresponding to the components of the seventh embodiment, and the detailed description thereof will be omitted. The eighth embodiment differs from the seventh embodiment in the following points, but has the same configuration as the seventh embodiment in other points.
In FIG. 15, each output signal of the piezoelectric body driving circuits DA and AMP is input to a phase measurement device IS constituted by a lock-in amplifier, and the phase measurement device IS detects a phase difference between the input signals and outputs the signals to the computer C. And to the bias voltage control device BD. Further, the computer C directly outputs a control signal to the piezoelectric driving circuit DA.

(Operation of Embodiment 8) The phase of the probe P is displaced by the electrostatic force due to the interaction between the probe P and the sample S. The amount of this displacement is determined by applying a bias voltage between the probe P and the sample S. It is also caused by That is, even if the surface potential of the sample S is the same, the magnitude of the electrostatic force acting on the probe P differs depending on the external bias voltage. In the bias voltage control device BD, when a phase different from the initially set phase is input to the computer C from the phase measurement device IS, the bias voltage between the probe P and the sample S is controlled so as to be the initially set phase. I do. This control amount corresponds to the potential of the sample surface. The control amount signal of the bias voltage control device BD is sent to the computer C, where it is converted into the potential of the sample surface. As the initially set phase, for example, the phase of the vibration drive voltage can be used.

(Embodiment 9) FIG. 16 is an explanatory view of Embodiment 9 of the surface potential measuring device. A change in the natural frequency of the probe P is detected, and a change between the sample and the probe is maintained so that the value is kept constant. FIG. 6 is a diagram showing an embodiment in which the interval of the control is controlled and the potential distribution is measured from the control amount. In the description of the ninth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be omitted. The ninth embodiment differs from the first embodiment in the following points, but has the same configuration as the first embodiment in other points.
FIG. 16 of the ninth embodiment is similar to FIG. 3 of the first embodiment, but in the ninth embodiment shown in FIG. 16, the Z table Tz is set so that the natural frequency of the probe P is constant. This embodiment is different from the first embodiment in that the distance between the sample S and the probe P is controlled by being moved.

(Effect of Embodiment 9) The natural frequency of the probe P changes due to the electrostatic force caused by the interaction between the probe P and the sample S, and the amount of this change is changed by changing the interval between the probe P and the sample S. Also change. That is, even if the potential of the sample surface is the same, the magnitude of the electrostatic force that varies depending on the distance from the probe P differs. When a frequency different from the initially set natural frequency is input from the lock-in amplifier LA, the computer C uses the Z table (Z-direction moving device) Tz to set the probe P-sample so that the initially set frequency becomes the initially set frequency. Control the interval between S. This control amount corresponds to the amount of static electricity acting between the probe P and the sample S. What is moved at this time can be the sample S, the probe P, or both. Then, the control amount signal of the Z table Tz is converted into the surface potential of the sample S.

(Embodiment 10) FIG. 17 is an explanatory view of an embodiment 10 of the surface potential measuring apparatus. A change in the vibration amplitude of the probe P is detected, and the change between the sample and the probe is maintained so as to keep the value constant. It is a figure which shows the Example which controls an interval and measures an electric potential distribution from the control amount. In the description of the tenth embodiment, the same reference numerals are given to the components corresponding to the components of the fourth embodiment, and the detailed description is omitted.
The tenth embodiment differs from the fourth embodiment in the following points, but has the same configuration as the fourth embodiment in other points. FIG. 17 of the tenth embodiment is similar to FIG. 9 of the fourth embodiment, but in the tenth embodiment shown in FIG. 17, the Z table Tz is set so that the vibration amplitude of the probe P is constant.
Is different from that of the fourth embodiment in that the distance between the sample S and the probe P is controlled by moving.

(Operation of Embodiment 10) Probe P and Sample S
The vibration amplitude of the probe P changes due to the electrostatic force caused by the interaction between the probe P and the sample S. The amount of the change also changes by changing the distance between the probe P and the sample S. That is, even if the potential of the sample surface is the same, the magnitude of the electrostatic force that varies depending on the distance from the probe P differs. When an amplitude different from the initially set vibration amplitude is input from the vibration amplitude measurement device SS, the computer C controls the position of the Z table Tz so that the amplitude becomes different from the initially set vibration amplitude. Control the interval. This control amount corresponds to the amount of static electricity acting between the probe P and the sample S.
What is moved at this time can be the sample S, the probe P, or both. Then, the computer C converts the control amount signal into a surface potential of the sample S.

(Embodiment 11) FIG. 18 is an explanatory view of an eleventh embodiment of the surface potential measuring device. A change in the phase of the probe P is detected, and the distance between the sample and the probe is adjusted so as to keep the phase constant. FIG. 6 is a diagram showing an embodiment in which the control is performed and the potential distribution is measured from the control amount. In the description of the eleventh embodiment, the same reference numerals are given to the components corresponding to the components of the fifth embodiment, and the detailed description will be omitted. The eleventh embodiment differs from the fifth embodiment in the following points, but has the same configuration as the fifth embodiment in other points. FIG. 18 of the eleventh embodiment is similar to FIG. 11 of the fifth embodiment, but in the eleventh embodiment shown in FIG. 18, the Z table Tz is moved so that the phase of the probe P is constant. This embodiment differs from the fifth embodiment in that the distance between the sample S and the probe P is controlled.

(Operation of Embodiment 11) Probe P and Sample S
The phase of the probe P changes due to the electrostatic force caused by the interaction with the probe P. The amount of change also changes by changing the distance between the probe P and the sample S. That is, the sample S
This is because the magnitude of the electrostatic force that works differs depending on the distance from the probe P even if the surface potential of the probe is the same. When a phase different from the initially set phase is input from the phase measurement device IS, the computer C controls the interval between the probe P and the sample S by moving the Z table Tz such that the phase becomes the initially set phase. . This control amount is determined by the probe P-
It corresponds to the amount of static electricity acting between the samples S. What is moved at this time can be the sample S, the probe P, or both. And computer C
Converts the control amount signal into a surface potential of the sample S.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention utilizes an electrostatic force between a sample and a probe. The present invention is not limited to the electric potential distribution, and can be used to generate an electric field outside a recording medium such as an electrostatic charge distribution, an induced charge distribution, a polarization state distribution, and a dielectric constant distribution. Anything that can be changed can be measured. (H02) The present invention can also be used as a reading device of a recording system using a change in the electric field as a memory.

[0051]

The above-described method and apparatus for measuring a surface potential according to the present invention have the following effects. (E01) Even if the surface potential is high, the surface potential can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a probe that can be used in the present invention, and FIGS. 1A to 1C are diagrams showing probes having different shapes, respectively.

FIG. 2 is an explanatory view of a method of vibrating a probe and measuring a surface potential of a sample from a change in the vibration state.

FIG. 3 is a first embodiment of a surface potential measuring apparatus according to the present invention;
FIG.

FIG. 4 is a graph showing an example of the relationship between the surface potential (V) of the sample and the natural frequency (Hz) of the probe P.

FIG. 5 is a second embodiment of the surface potential measuring device of the present invention.
In FIG. 1, the surface potential of a charged sample surface, the surface potential of a portion of the charged sample surface irradiated with light (a portion corresponding to an electrostatic latent image on the surface of a photoconductor of an image forming apparatus), and Unirradiated part (background part of electrostatic latent image)
FIG. 4 is an explanatory diagram of a device for measuring the surface potential of the device (device for measuring the deterioration of a charged latent image).

FIG. 6 is a diagram showing the potential of an electrostatic latent image in a region of 50 μm in the X direction and 50 μm in the Y direction on the surface of the sample.

FIG. 7 shows a third embodiment of the surface potential measuring apparatus according to the present invention.
FIG. 3 is a diagram illustrating a surface potential of a sample in a state where the surface of the sample is charged, and a surface of a portion where the charged surface of the sample is irradiated with light (a portion corresponding to an electrostatic latent image on a photosensitive member surface of an image forming apparatus). FIG. 4 is an explanatory diagram of a device for measuring a change in potential (a device for measuring deterioration of a charged latent image).

FIG. 8 is a diagram showing changes over time of the surface potential of the charged state of sample α and sample β and the surface potential after exposure, and is a diagram showing a measurement example of latent image deterioration.

FIG. 9 is an explanatory view of Embodiment 4 of the surface potential measuring device, showing an embodiment in which the probe P is vibrated and the potential distribution of the sample is measured from a change in the vibration amplitude.

FIG. 10 is a graph showing an example of the relationship between the surface potential (V) of the sample and the oscillation amplitude voltage (V) of the probe P.

FIG. 11 is an explanatory view of Embodiment 5 of the surface potential measuring device, showing an embodiment in which the probe P is vibrated and the potential distribution of the sample is measured from a change in the phase thereof.

FIG. 12 shows a phase difference between the surface potential (V) of the sample and the vibration of the probe (the phase difference between the vibration excitation signal for vibrating the probe and the vibration detection signal of the probe).
It is a graph showing an example of the relationship with (degree).

FIG. 13 is an explanatory diagram of Embodiment 6 of the surface potential measuring device, in which a change in the natural frequency of the probe P is detected, and a bias voltage between the sample and the probe is adjusted so as to keep the value constant. It is a figure which shows the Example which controls and measures electric potential distribution from the control amount.

FIG. 14 is an explanatory view of a seventh embodiment of the surface potential measuring device, in which a change in the vibration amplitude of the probe P is detected, and the bias voltage between the sample and the probe is controlled so as to keep the value constant. FIG. 7 is a diagram showing an embodiment in which a potential distribution is measured from the control amount.

FIG. 15 is an explanatory diagram of Embodiment 8 of the surface potential measuring device, in which a change in the phase of the probe P is detected, and a bias voltage between the sample and the probe is controlled so as to maintain the phase at a constant value. It is a figure showing an example which measures a potential distribution from the control quantity.

FIG. 16 is an explanatory view of a ninth embodiment of the surface potential measuring device, in which a change in the natural frequency of the probe P is detected, and the interval between the sample and the probe is controlled so as to keep the value constant. FIG. 7 is a diagram showing an embodiment in which a potential distribution is measured from the control amount.

FIG. 17 is an explanatory view of Embodiment 10 of the surface potential measuring device, in which a change in the vibration amplitude of the probe P is detected, and the interval between the sample and the probe is controlled so as to keep the value constant. FIG. 4 is a diagram showing an embodiment for measuring a potential distribution from the control amount.

FIG. 18 is an explanatory diagram of an eleventh embodiment of the surface potential measuring device, in which a change in the phase of the probe P is detected, and the interval between the sample and the probe is controlled so as to keep the phase constant. It is a figure showing an example which measures a potential distribution from the control quantity.

FIG. 19 is an explanatory diagram of a conventional surface potential measuring method.

FIG. 20 is an explanatory diagram of another conventional technique for measuring a surface potential, which is disclosed in Japanese Patent Application Laid-Open Nos. 5-119093, 5-149988, 6-3398, or Journal of the Electrophotographic Society. Vol. 32, No. 4, P62-66 (1
993).

[Explanation of symbols]

A: vibration excitation device (piezoelectric element), K: light source, Dx: X table drive device, Dy: Y table drive device, Dz: Z table drive device, P: probe, PD + K: vibration state detection means, S: sample , Tx: X direction moving device, Ty: Y direction moving device, Tz: Z direction moving device, U1: Vibration state detecting device, U2: Signal processing device.

Claims (5)

[Claims] 1. A method for measuring a potential on a sample surface using a potential detection probe, wherein a probe vibrating in parallel with the sample surface is used as the potential detection probe, and a potential between the probe and the charge on the sample is used. A surface potential measuring method for measuring a surface potential of the sample by using a change in a vibration state of the probe by an action of a working electrostatic force. 2. The change in the vibration state of the probe is a change in a natural frequency of the probe, a change in a vibration amplitude of the probe, or a change in a phase of the probe. 2. The method for measuring surface potential according to 1. 3. A voltage source for applying a voltage between the probe and the sample so that a change in the vibration state of the probe is constant (including no change), and a voltage control unit for controlling the voltage source, 3. The surface potential measuring method according to claim 1, wherein the potential of the sample is measured from a control amount by the control means. 4. A distance control means for controlling a distance between the probe and the sample such that a change in a vibration state of the probe is constant (including no change), and the sample is controlled based on a control amount by the distance control means. 3. The method according to claim 1, wherein the surface potential is measured. 5. A potential detecting probe whose tip facing a sample surface is vibratably supported in parallel with the sample surface, a vibration excitation device for forcibly vibrating the probe, and detecting a change in the vibration state of the probe. A surface potential measuring device comprising: a vibration state detecting means for measuring a surface potential of a sample by using a change amount of the vibration state.