JP4344909B2 - Electrostatic latent image measuring apparatus and electrostatic latent image measuring method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charging device, an electrostatic latent image forming device, and an electrostatic latent image measuring device in an electrophotographic process, and is applicable to measurement of a sample surface potential distribution, a sample surface charge distribution, and the like. is there.
[0002]
[Prior art]
In order to obtain an output image in an electrophotographic image forming apparatus such as a copying machine or a laser printer, the following processes are usually performed. An example of an electrophotographic apparatus that obtains an output image by executing each process is shown in FIG. Hereinafter, a description will be given with reference to FIG.
1. Charging: The electrophotographic photosensitive member is uniformly charged.
2. Exposure: The photosensitive member is irradiated with light, and charges are partially released corresponding to the image to form an electrostatic latent image.
3. Development: A visible image is formed on the electrostatic latent image with charged fine particles (hereinafter referred to as “toner”).
4). Transfer: Move the developed and visualized toner image to paper or other transfer material.
5). Fixing: The toner forming the transfer image is fused to fix the image on the transfer material.
6). Cleaning: Cleans residual toner on the photoreceptor.
7. Static elimination: Eliminates residual charge on the photoreceptor.
[0003]
The process factor and process quality in each of the above steps greatly affect the final output image quality. In recent years, in addition to the demand for high image quality, there is a demand for high durability and high stability. Furthermore, there is a growing demand for the realization of environmentally friendly imaging processes such as energy saving, and it is desirable to improve the quality of each process. ing. For the image forming process, the electrostatic latent image on the surface of the photoreceptor accompanying exposure is a factor that directly affects the behavior of the toner particles, and it is necessary to grasp the behavior. For this reason, it is extremely important to evaluate the quality of the electrostatic latent image on the surface of the photoreceptor.
If the electrostatic latent image of the photoreceptor can be measured and fed back to the design, the process quality of each image forming process can be improved. As a result, high image quality, high durability, high stability, and energy saving can be expected.
[0004]
[Problems to be solved by the invention]
However, it is extremely difficult to measure an electrostatic latent image, and the actual situation is that it cannot be measured at all in actual use.
A well-known method for measuring an electrostatic latent image is to bring a sensor head such as a cantilever close to a sample having a potential distribution, and at that time, an electrostatic attractive force that occurs as an interaction between the electrostatic latent image and the cantilever or the like. Or an induced current is measured and converted into a potential distribution. The electrostatic attraction type is commercially available as SPM (scanning probe microscope), and the induced current type is described in Japanese Patent No. 3009179, Japanese Patent Application No. 11-184188, and the like.
[0005]
However, in order to use these methods, it is necessary to bring the sensor head close to the sample. For example, in order to obtain a spatial resolution of 10 μm, the distance between the sensor and the sample needs to be 10 μm or less. Under these conditions,
・ Absolute distance measurement is required.
• Measurement takes time, and the state of the latent image changes during that time.
・ Discharge and adsorption occur.
・ The sensor itself disturbs the electric field.
Even if it can be used for other purposes, an electrostatic latent image cannot be measured in actual use.
[0006]
Therefore, as a practical measurement method, a method of visualizing and measuring an electrostatic latent image is generally used. In other words, the toner, which is a colored fine powder, is charged, developed by a Coulomb force acting between the charged toner and the electrostatic latent image, and further transferred to a paper or a tape. The quality of the electrostatic latent image is determined. However, in this case, the electrostatic latent image itself is not measured because the development and transfer processes are performed.
[0007]
On the other hand, a method for measuring a potential pattern using an electron beam is known. This has already been put to practical use for LSI failure analysis. This measurement method is a case where the sample is a conductor, and a measurement object is completely different from a dielectric material such as a photoconductor intended by the present invention, and cannot be applied to measurement of a dielectric material such as a photoconductor. . If the object to be measured is a conductor, the potential distribution can be maintained for a long time by passing a constant current through the conductor, and the potential amount is a narrow range of 0 to 5 V at most, so that no charge-up phenomenon occurs. The potential state does not change by irradiation with the electron beam.
[0008]
  As an observation method of electrostatic latent image by electron beam,JPAlthough there are those described in Japanese Patent Laid-Open No. 03-49143, samples are limited to samples that can store and hold LSI chips and electrostatic latent images. That is, a normal photoconductor that causes dark decay cannot be measured.
  Since a normal dielectric can hold a charge semipermanently, even if measurement is performed over time after forming a charge distribution, the measurement result is not affected. However, in the case of a photoconductor, since the resistance value is not infinite, the charge cannot be held for a long time, dark decay occurs, and the surface potential decreases with time. The time that the photoconductor can hold the charge is at most several tens of seconds even in the dark room. Therefore, even if an attempt is made to observe in an electron microscope (SEM) after charging and exposure, the electrostatic latent image disappears at the preparation stage.
[0009]
The present invention has been made to solve the above-described problems of the prior art. In the measurement apparatus, the charged particle beam is irradiated to the sample to generate a charged charge on the sample, and further, the static charge is generated. A charging device, an electrostatic latent image forming device, and an electrostatic device, which have a means for forming an electrostatic latent image and can measure the electrostatic latent image distribution by performing measurement within a short time after the latent image is formed. An object of the present invention is to provide a latent image measuring device.
[0010]
[Means for Solving the Problems]
  According to the first aspect of the present invention, the charge cannot be held for a long time and dark decay occurs.For electrophotographyElectrons for photoconductor samplesbeamTo generate a charged charge on the sampleElectrificationapparatusWhen,An optical system for exposing the surface of the sample charged by the charging device to generate a charge distribution on the sample and forming an electrostatic latent image, and scanning the sample surface on which the electrostatic latent image is formed with an electron beam Measuring means for measuring the electrostatic latent image on the sample surface, and an installation part for installing the photoconductor sample in the chamber, and with respect to the photoconductor sample in a vacuum state in the chamber In order to generate a charged charge, form an electrostatic ray image, and measure an electrostatic ray image, the charging device, the optical system, and the measuring unit are arranged in a chamber.In order to charge the sample to the potential Vs when the acceleration voltage of the electron whose secondary electron emission ratio becomes 1 when the sample is switched from the positive charge to the negative charge as the acceleration voltage increases is E0.,oneFixed timeShootIn a range where the relationship between the acceleration voltage of the electron beam and the saturated charging potential can be linearly approximated,
  | E1-E0 | ≧ | Vs |
With an acceleration voltage E1 satisfying the following equation:The above photoreceptorIrradiate the sample with electronsRukoAnd features.
[0011]
  Claim 2In the invention described in claim 1, the invention described in claim 1,
  | Vs | ≦ | E1-E0 | ≦ | Vs | +2 kV
It is characterized by having means for charging the sample to the potential Vs by irradiating with the electron acceleration voltage E1 satisfying the above condition.
[0014]
  Claim2The described invention is claimed.1In the described invention, secondary electrons from a sample are detected.
  Claim3The described invention is claimed.1 or 2In the described invention, a semiconductor laser is used as an exposure light source.
  Claim4The described invention is claimed.1 to 3The invention described in the above is characterized in that it has a charge removing means for removing the electrostatic latent image formed by the optical system after the measurement by the measuring means.
  The inventions according to claims 5 to 8 correspond to claims 1 to 4 respectively as a technical idea, wherein the category of the invention is “electrostatic latent image measuring method”.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a charging device, an electrostatic latent image forming device, and an electrostatic latent image measuring device according to the present invention will be described below with reference to the drawings.
FIG. 1 shows an embodiment of a charging device, an electrostatic latent image forming device, and an electrostatic latent image measuring device according to the present invention. The charging device, the electrostatic latent image forming device, and the electrostatic latent image measuring device include a charged particle irradiation unit 10 that irradiates a charged particle beam, an exposure unit 20, a sample setting unit 16, and a secondary electron detection unit. 18. These are all placed in the same chamber, and the inside of the chamber is evacuated.
Here, the charged particles refer to particles that are affected by an electric field or a magnetic field, such as an electron beam or an ion beam.
[0016]
Hereinafter, the charged particle irradiation unit will be described as an embodiment including an electron beam irradiation unit.
The electron beam irradiation unit 10 includes an electron gun 11 for generating an electron beam, a condenser lens 12 for focusing the electron beam emitted from the electron gun 11, and a beam blanker 13 for turning on / off the electron beam. The scanning lens 14 for scanning the electron beam that has passed through the beam blanker 13 and the objective lens 15 for condensing the electron beam that has passed through the scanning lens 14 are provided. The scanning lens 14 is a so-called deflection coil. A driving power source (not shown) is connected to each of the other lenses.
In the case of an ion beam, a liquid metal ion gun or the like is used instead of an electron gun.
The secondary electron detector 18 uses a scintillator, a photomultiplier tube, or the like.
[0017]
The exposure unit 20 includes a light source 21 of a wavelength having sensitivity with respect to a photoconductor configured as described below, a collimate lens 22, an aperture 23, an imaging lens 25, and the like, and is placed on the sample setting unit 16. A desired beam diameter and beam profile can be generated on the sample 30. As the light source 21, a semiconductor laser (hereinafter referred to as “LD”) or the like can be used. Further, the light source 21 is controlled by LD control means or the like so that an appropriate exposure time and exposure energy can be irradiated. In order to form a line pattern composed of an electrostatic latent image on the sample 30, a scanning mechanism using a galvano mirror or a polygon mirror may be provided in the optical system of the exposure unit 20.
[0018]
As shown in FIG. 4, the structure of the photoconductor that is the actual condition of the sample 30 is formed by forming a charge generation layer (CGL) and a charge transport layer (CTL) on a conductive support. When the surface is exposed in a charged state, light is absorbed by the charge generation material (CGM) of the charge generation layer CGL, and positive and negative charge carriers are generated. One of the carriers is injected into the charge transport layer CTL and the other into the conductive support by an electric field. The carriers injected into the charge transport layer CTL move in the charge transport layer CTL to the surface of the charge transport layer CTL by an electric field, and are combined with charges on the surface of the photoreceptor to disappear. Thereby, a charge distribution is formed on the surface of the photoreceptor. That is, an electrostatic latent image is formed.
[0019]
Next, a method for charging a sample surface, a method for forming an electrostatic latent image, and a method for measuring an electrostatic latent image will be described together with the operation of the embodiment shown in FIG.
First, the charged particle beam irradiation unit 10 irradiates the photoconductor sample 30 with an electron beam. The relationship between the acceleration voltage and the secondary electron emission ratio δ at this time is shown in FIG. The acceleration voltage E1 is set to an acceleration voltage higher than the acceleration voltage E0 at which the secondary electron emission ratio δ is 1. Thereby, since the amount of incident electrons exceeds the amount of emitted electrons, electrons are accumulated in the sample 30 and charge up occurs. As a result, the sample 30 can be negatively charged uniformly. A desired charging potential can be formed by appropriately setting the acceleration voltage and the irradiation time.
Once the charged potential is formed, the electron beam is once turned off.
[0020]
Here, the secondary electron emission ratio δ is
Secondary electron emission ratio δ = emitted electron / incident electron
However, more strictly speaking, it is necessary to consider transmission electrons and reflection electrons,
Emission electron = transmission electron + reflection electron + secondary electron
It is good to do.
[0021]
The secondary electron emission ratio δ depends on the energy of the electron beam, that is, the acceleration voltage, and generally has a relationship as shown in FIG. As shown in FIG. 2, at the acceleration voltage E1 at which δ = 1, charging does not occur and the equilibrium state is maintained. In the case of the acceleration voltage E1> E0, δ <1, and the number of emitted electrons is smaller than the number of incident electrons, so that the charge is negative.
[0022]
FIG. 7 shows the relationship of the charging potential to the irradiation time for each acceleration voltage. As can be seen from FIG. 7, immediately after the electron beam irradiation, charges are rapidly accumulated, but incident electrons are decelerated due to the influence of the negatively charged potential of the sample as time elapses. V = {2e (E1-(− Vs))} where V is the velocity of electrons reaching the sample surface at the charging potential Vs (<0), m is the mass of the electrons, and m is the charge amount.^1/2Can be expressed as This means that the acceleration voltage E1 is relatively small. As a result, the charge accumulation amount per unit time decreases, and when the charging potential corresponding to E1 − (− Vs) = E0 is reached, the saturation charging potential is reached and the equilibrium is stabilized. For this reason, as shown in FIG. 7, immediately after electron beam irradiation, it rises rapidly, and as time passes, the change gradually decreases and becomes saturated.
[0023]
The following relational expression is approximately established between the acceleration voltage E1 of the electron beam and the saturated charging potential Vs.
Saturation charging potential = − {(acceleration voltage E1 of electron beam) − (acceleration voltage E0 of electron beam at which δ = 1)} (1)
Although E0 may vary depending on the characteristics of the sample, it can be obtained by the following procedure.
[0024]
FIG. 8 shows the relationship between the acceleration voltage and the charging potential when the electron beam is irradiated for a certain time. Since it can be regarded as changing almost linearly,
When acceleration voltage E1 = 0.915 kV, Vs = 0
Therefore, E0 = 0.915 kV in this sample can be obtained.
According to the equation (1), when the sample is charged to −800 V, the saturation charging potential is −585 V when the acceleration voltage of the electron beam is 1.5 kV or less, and the charging potential reaches −800 V. do not do. At least the following formula (2)
| E1-E0 | ≧ | Vs | (2)
Therefore, an acceleration voltage of 1.715 kV or more is necessary.
[0025]
When the acceleration voltage is increased, the time to reach the target charged potential is shortened, so that it becomes difficult to control and damage to the sample cannot be ignored. Accordingly, it is desirable to have a condition that can form a desired charging potential with as small an acceleration voltage as possible. That is,
| Vs | ≦ | E1-E0 | ≦ | Vs | +2 kV (3)
Is appropriate.
[0026]
For example, in order to charge the sample to −800 V, for example, about 1.7 to 3.7 kV is considered appropriate. The electron beam irradiation time at that time is about 2 minutes or less. In order to charge in a short time, the current density of the electron beam may be increased.
[0027]
After the desired charging potential is formed, the photosensitive member sample 30 is exposed through the optical system of the exposure unit 20. The optical system is adjusted to form a desired beam diameter and beam profile. By controlling the light source 21 by the LD control means, it is possible to irradiate with appropriate exposure energy with an appropriate exposure time. Further, for example, by providing a scanning mechanism using a polygon mirror, an arbitrary latent image pattern including a line pattern can be formed in the generatrix direction of the photoconductor sample 30.
[0028]
After forming the electrostatic latent image, the mode is changed to the observation mode. In the observation mode, the photoconductor sample 30 is scanned with an electron beam, and the emitted secondary electrons are detected by the secondary electron detector 18 including a scintillator, a photomultiplier tube, etc., and converted into an electrical signal. Observe the potential contrast image.
[0029]
In order to convert a potential contrast image into a potential, a conversion table representing the correlation between the potential and the signal intensity may be prepared in advance, and the potential may be calculated from the signal intensity based on the conversion table. Further, a method of calculating a potential distribution by arranging a known reference potential in the electron beam scan region and comparing the secondary electron signal intensity with the reference potential may be used.
As a method of arranging the reference potential, as shown in FIG. 5, there is a method of arranging a plurality of conductive substrates 34 on an insulator 33 and setting a reference potential to each of the conductive substrates 34. Specifically, the voltage of the reference voltage source is divided by a resistor, and a reference potential is applied to each conductive substrate 34. In general, a portion having a lower potential than a portion having a high potential becomes brighter because the amount of secondary electrons emitted increases. In FIG. 5, a portion having a relatively low potential is displayed in white, and a portion having a high potential is displayed in black. In FIG. 5, reference numeral 30 denotes a sample, 31 denotes an electrostatic latent image, and 32 denotes an electron beam scan area. Secondary electrons are detected by the detector 18 while scanning the surface of the sample 30 with an electron beam. The state of change in the detection signal intensity at that time is shown in the lower part of FIG.
[0030]
The signal intensity on the detector 18 may be corrected when it changes depending on the setting conditions. Further, calibration may be performed in advance.
After the measurement is completed, the residual charge of the sample 30 can be removed by irradiating the entire surface of the sample 30 with light using the light source 17 shown in FIG.
[0031]
FIG. 6 shows an example of the control unit of the above embodiment. In FIG. 6, an LD control unit 36 that controls the light source 21, a charged particle control unit 37 that controls the scanning lens 14, an LED control unit 38 that controls the light source 17 for residual charge removal, and a sample that controls the movement of the sample stage 16. A table control unit 39 is provided, and the LD control unit 36, charged particle control unit 37, LED control unit 38, and sample table control unit 39 are controlled by the host computer 35. Further, the output of the detector 18 is detected by the secondary electron detector 41, and this detection signal is processed by the signal processing unit 42 so that the measurement result output unit 43 outputs the secondary electron measurement result. Yes.
[0032]
When positive charging is desired, irradiation with an accelerating voltage with a secondary electron emission ratio of 1 or more as shown in FIG. In general sample observation by SEM, it is known that observation is performed under the condition of δ = 1 in order to avoid the influence of charge-up, and other acceleration voltages are not used. One of the features of this embodiment is that the charged potential is formed by intentionally charging up.
[0033]
In the above method, it has been described that the electron beam is once turned off after the charged potential is formed. However, the reference current density is changed without turning it off, and the observation conditions are set so that charge-up does not occur, and exposure is performed in that state. But it ’s okay.
[0034]
Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, a cylindrical photoconductor sample can be measured under conditions close to those of an actual machine. An electrostatic latent image is formed within a short time after an electrostatic latent image is formed on the photoconductor sample. This makes it possible to measure the distribution and to measure the photoreceptor sample in a non-destructive manner.
In addition, the same code | symbol is attached | subjected to the same component as the above-mentioned embodiment.
[0035]
In FIG. 9, an electron beam irradiation unit 10, a sample 30 made of a cylindrical photoconductor, an electrostatic latent image forming unit for forming a charge distribution on the surface of the sample 30, and secondary electrons are included in one housing. A detector 18 is arranged. The electron beam irradiation unit 10 includes an electron gun 11 for generating an electron beam, a condenser lens 12 for focusing the electron beam emitted from the electron gun 11, and a beam blanker 13 for turning the electron beam on / off. And a scanning lens (deflection coil) 14 for scanning the electron beam that has passed through the beam blanker 13 and an objective lens 15 for refocusing the electron beam that has passed through the scanning lens 14. A driving power source (not shown) is connected to each lens. The detector 18 is a scintillator, a photomultiplier tube, or the like.
[0036]
The electrostatic latent image forming unit includes a charging unit 45, an exposure unit 46, and a charge removal unit 47 disposed around the cylindrical photoconductor sample 30. The charging unit 45 irradiates the surface of the sample 30 with an electric charge to uniformly charge, and the exposure unit 46 exposes the uniformly charged surface of the sample 30 with a predetermined pattern to form a charge distribution. The charge eliminating portion 47 is for erasing charges. The photosensitive member 30 is provided with a driving unit attached to the central axis of the photosensitive member, and the photosensitive member 30 is rotationally driven by the driving unit. As the driving means, a stepping motor, a DC servo motor, or the like can be used. Examples of the charging unit 45 include charging by electron beam irradiation, contact charging, and charge injection charging. The neutralization unit 47 can be configured by an LED or the like that irradiates light on the entire surface of the photoreceptor 30.
[0037]
The operation or measuring method of the embodiment shown in FIG. 9 is as follows.
1. The photoreceptor 30 is rotated.
2. In the charging unit 45, the photosensitive member 30 is uniformly charged so that the surface of the photosensitive member 30 has a desired potential.
3. In the exposure unit 46, the surface of the photoconductor 30 is irradiated with light to partially release the charges and form an electrostatic latent image.
4). In the measurement unit 18, the acceleration voltage of the electron beam irradiation unit 10 is set so that the secondary electron emission ratio is 1. The surface of the photoconductor sample 30 is scanned with an electron beam, and the emitted secondary electrons are detected by a detector 18 such as a scintillator and converted into an electric signal to observe a potential contrast image.
5). In the static eliminating unit 47, the residual charge on the photoconductor 30 is erased by irradiating light onto the surface of the photoconductor 30 from an LED or the like.
By using such a method, it is possible to dynamically measure the electrostatic latent image on the photoreceptor 30.
[0038]
The rotation driving mechanism may be a means for driving the photosensitive member 30 once. By attaching driving means capable of rotating once, it is possible to dynamically measure the electrostatic latent image over the entire circumference of the photoreceptor 30.
When evaluating the change of the photoconductor 30 over time, the photoconductor 30 may be continuously rotated, and the above operations 1 to 5 may be repeated and measured.
According to this embodiment, since the photoconductor 30 as a sample is the same as the cylindrical photoconductor used in the electrophotographic apparatus, the photoconductor used in the actual machine or the photoconductor used in the actual machine is used as it is. That is, it can be measured as a sample without destruction. Therefore, a photoconductor used over the years can also be easily measured.
[0039]
FIG. 10 shows another example of the exposure apparatus. This exposure apparatus is configured in the same manner as the general scanning optical system described above. In FIG. 10, from a light source 61 composed of an LD or the like having a sensitivity with respect to the cylindrical photosensitive member 30, a collimate lens 62, a cylinder lens 63, an aperture, a polygon mirror 65 as a deflector, scanning lenses 66 and 67, and the like. Become. An electrostatic latent image can be generated by irradiating the surface of the photoreceptor 30 as a sample with a light beam having a desired beam diameter and beam profile. Reference numerals 64 and 68 denote mirrors. The light source 61 is controlled by LD control means (not shown) so that the photoconductor 30 can be irradiated with an appropriate exposure time and exposure energy. In this manner, by adding a scanning mechanism using the polygon mirror 65, an arbitrary latent image pattern including a line pattern can be formed with respect to the generatrix direction of the photoreceptor 30.
[0040]
【The invention's effect】
  According to the first aspect of the present invention, there is provided a photosensitive member sample in which the charge cannot be held for a long time and dark decay occurs.Place this photoconductor sample in a vacuum chamberAgainstBy an electron beam charging device placed in the chamberElectron irradiationShiIn order to charge the sample to the electric potential Vs when the acceleration voltage of the electron whose secondary electron emission ratio becomes 1 when the sample is switched from the positive charge to the negative charge as the acceleration voltage increases is E0, In a range where the relationship between the acceleration voltage of the electron beam irradiated when the beam is irradiated for a certain period of time and the relationship between the saturated charging potential can be linearly approximated
  | E1-E0 | ≧ | Vs |
The sample is irradiated with electrons at an acceleration voltage E1 satisfying the equationRukoThus, a desired negative charging potential can be formed.
  In addition, by having an optical system in the vacuum chamber that exposes the surface of the charged sample to form a charge distribution on the sample and forms an electrostatic latent image, it is less susceptible to environmental fluctuations and is stable. An electrostatic latent image can be formed.
[0042]
  Claim2According to the invention described in claim 1, in the invention according to claim 1, the sample is irradiated with the acceleration voltage E1 of electrons satisfying the condition of | Vs | ≦ | E1−E0 | ≦ | Vs | +2 kV. By having a means for charging to a potential Vs, the sample can be efficiently charged to a desired potential.
[0044]
  Claim2According to the described invention, the claims1In the described invention, a signal corresponding to the potential distribution of the photoreceptor sample can be detected by detecting secondary electrons from the sample. In addition, real-time measurement is possible.
[0045]
  Claim3According to the described invention, the claims1 or 2In the described invention, by using a semiconductor laser as an exposure light source, it can be efficiently stored in a limited installation space. Also, the exposure time can be easily controlled.
[0046]
  Claim4According to the described invention, the claims1 to 3In the described invention, by having a means for removing the residual charge of the sample, the residual charge can be efficiently removed, and repeated measurement is easy.
[Brief description of the drawings]
FIG. 1 is an optical layout diagram showing an embodiment of a charging device, an electrostatic latent image forming device, and an electrostatic latent image measuring device according to the present invention.
FIG. 2 is a graph showing a relationship between an acceleration voltage and a secondary electron emission ratio δ in the charged particle beam irradiation unit of the embodiment.
FIG. 3 is a front view schematically showing an example of an image forming apparatus using a photoconductor as a measurement object of the present invention.
FIG. 4 is an enlarged cross-sectional view showing the structure of a photoconductor that is a measurement target of the present invention.
FIG. 5 is a plan view showing a measurement example according to the present invention and an example in which a known reference potential is arranged in an electron beam scan region.
FIG. 6 is a block diagram showing an example of each part control system applied to the embodiment of the present invention.
FIG. 7 is a graph showing the relationship of the charging potential with respect to the irradiation time in the photosensitive member sample for each acceleration voltage.
FIG. 8 is a graph showing a relationship between an acceleration voltage and a charging potential when a photoconductor sample is irradiated with an electron beam for a certain period of time.
FIG. 9 is an optical layout diagram showing another embodiment of the charging device, the electrostatic latent image forming device, and the electrostatic latent image measuring device according to the present invention.
FIG. 10 is a front view showing an example of an exposure optical system that can be used in the embodiment.
[Explanation of symbols]
10 Electron beam irradiation unit
11 Electron gun
12 condenser lens
13 Beam Blanker
14 Scanning lens
16 Sample installation part
18 Detector
20 exposure area
30 samples (photoconductor)

Claims (8)

By irradiating an electron beam to an electrophotographic photoreceptor sample is dark decay can not occur to hold a long time charges, a charging device for generating a charge on the specimen,
An optical system for exposing the surface of the sample charged by the charging device to generate a charge distribution on the sample and forming an electrostatic latent image;
Measuring means for measuring the electrostatic latent image on the sample surface by scanning the sample surface on which the electrostatic latent image is formed with an electron beam;
An installation unit for installing the photoconductor sample in the chamber;
The charging device, the optical system, and the measuring means are disposed in the chamber in order to generate a charged charge, form an electrostatic latent image, and measure an electrostatic latent image on the photoconductor sample in a vacuum state in the chamber. Placed in
The charging device charges the sample to the potential Vs when the acceleration voltage of the electrons with which the secondary electron emission ratio becomes 1 when the sample is switched from the positive charge to the negative charge as the acceleration voltage increases is E0. to the extent that the relationship can be linearly approximated acceleration voltage and the charge acceptance of the electron beam that shines one scheduled HazamaTeru,
| E1-E0 | ≧ | Vs |
At an acceleration voltage E1 which satisfies the equation, the measurement apparatus of an electrostatic latent image, wherein the benzalkonium be irradiated electrons to the photoreceptor sample. A measuring apparatus of an electrostatic latent image having a charging device according to claim 1, wherein the measuring means, the measuring apparatus of the electrostatic latent image and detecting secondary electrons from the sample. 3. The apparatus for measuring an electrostatic latent image according to claim 1 , wherein the exposure light source is a semiconductor laser . Wherein after measuring with measuring means, the measuring apparatus of the electrostatic latent image according to any one of claims 1 to 3, characterized in that a charge removing means for removing an electrostatic latent image formed by the optical system. A photoconductor sample that cannot hold charge for a long time and causes dark decay is placed in a vacuum chamber,
By irradiating the photoreceptor sample with an electron beam in the vacuum chamber, a charged charge is generated on the sample,
The surface of the charged sample is exposed to generate a charge distribution on the sample to form an electrostatic latent image,
An electrostatic latent image measurement method for measuring an electrostatic latent image on a sample surface by scanning the sample surface with an electron beam in the vacuum chamber,
The charging device charges the sample to the electric potential Vs when the acceleration voltage of the electrons at which the secondary electron emission ratio becomes 1 when the sample is switched from the positive charge to the negative charge as the acceleration voltage increases is E0. Therefore, in a range where the relationship between the acceleration voltage of the electron beam irradiated for a certain time and the saturated charging potential can be linearly approximated,
| E1-E0 | ≧ | Vs |
A method for measuring an electrostatic latent image, comprising irradiating a sample with electrons at an acceleration voltage E1 satisfying the formula: 6. A method for measuring an electrostatic latent image comprising the charging device according to claim 5, wherein the measuring means detects secondary electrons from the sample. 8. The method for measuring an electrostatic latent image according to claim 6, wherein the exposure light source is a semiconductor laser. 8. The method for measuring an electrostatic latent image according to claim 6, further comprising charge removing means for removing the electrostatic latent image formed by the optical system after measurement by the measuring means.

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