JP5993715B2 - Photoconductor characteristic evaluation method and image forming method - Google Patents

Description

  The present invention relates to a method for evaluating characteristics of an electrophotographic photoreceptor (hereinafter also simply referred to as “photoreceptor”), and more particularly to a method for evaluating image memory characteristics of the photoreceptor.

  The present invention also relates to an image forming method incorporating a method for evaluating image memory characteristics of a photoreceptor in an electrophotographic apparatus.

  The photoconductor is one of the most important components in an electrophotographic process such as a copying machine or a laser printer. In order to bring out the performance of the electrophotographic apparatus main body, it is necessary to satisfy various characteristics. is there. For this reason, various characteristics relating to the electrophotographic process are inspected before the photoreceptor is shipped. Further, when developing a new photoreceptor for a new electrophotographic apparatus, a process of making a prototype of the photoreceptor in the development process and evaluating various characteristics relating to the electrophotographic process is repeatedly performed.

  Above all, the presence or absence of image memory is important as the characteristics of the photosensitive member because it directly affects the image quality of the output image.

  Image memory is a phenomenon in which an afterimage of an image formed in the previous electrophotographic process step appears in the next electrophotographic process step. The generation of such an image memory greatly impairs the image quality of an electrophotographic image especially when a halftone image is copied like a photograph or when a color image is copied.

  Conventionally, evaluation of image memory characteristics (image memory characteristics) of an electrophotographic photosensitive member has been performed by evaluating the state of an image output using image output means such as a copying machine.

  Further, as a dedicated evaluation device, an evaluation device is disclosed in which measuring devices such as charging means, exposure means, and a potential sensor are arranged around a rotating photoreceptor. By using this evaluation device, the charged potential when the history of the previous circumference of the photoconductor is in the dark state and the charged potential when the photoconductor is in the bright state are measured and compared, thereby comparing the image of the photoconductor. A technique for evaluating memory characteristics is disclosed. (See Patent Document 1)

JP 2002-82572 A

  2. Description of the Related Art Amorphous silicon (hereinafter also referred to as “a-Si”) photoreceptors and organic photoreceptors are known as photoreceptors for digital electrophotographic devices and color electrophotographic devices that have been remarkably popular in recent years.

  When these photoconductors are used, there may be an image memory in which the exposure history of the previous circumference appears. Conventionally, the image memory characteristics have been evaluated by the photoconductor characteristic evaluation method disclosed in Japanese Patent Application Laid-Open No. 2004-151620, and simulation has been performed regarding the quality of the image memory of the output image. Based on the results, various improvements have been made and the generation of image memory has been reduced.

  However, in recent years, the specifications required for color copiers have become stricter, and the occurrence of a small amount of image memory that has not been a problem in the past has been seen as a problem.

  There is also an increasing interest in the output image security in the market. For example, when outputting an image, specific pattern information is embedded as invisible information in a halftone that cannot be visually recognized by the user, and the printing operation is stopped when the scanner or copier reads the pattern information. is there. When outputting a security image as described above, a normal security image may not be output due to the occurrence of a small amount of image memory that has not been a problem in the past.

  Further, depending on the environment in which the electrophotographic apparatus is installed, a slight image memory is generated, and the output image of the electrophotographic apparatus may be deteriorated.

  In the development of a-Si photoreceptors and organic photoreceptors that require the output of such high-quality images, evaluation of image memory characteristics that are more stringent than before is required. However, the photoconductor characteristic evaluation method disclosed in Patent Document 1 described above sometimes fails to evaluate image memory characteristics that sufficiently match the output image.

  As another problem, there is also a demand for an electrophotographic apparatus that can stably output high-quality images regardless of the use environment.

  The present invention has been made in view of the prior art as described above, and provides a photoconductor characteristic evaluation method capable of evaluating image memory characteristics of a photoconductor that matches an image output by an image forming apparatus. For the purpose. It is another object of the present invention to provide an image forming method capable of outputting a high quality image regardless of the use environment.

In order to achieve the above object, the invention according to the present application is
A rotating means for rotating a cylindrical photoconductor, a charging means for applying an electric charge to the surface of the photoconductor, a first exposure means for irradiating the surface of the photoconductor with a first exposure light, A surface potential measuring means for measuring the surface potential of the photoconductor; a second exposure means for irradiating the surface of the photoconductor with a second exposure light; and the charging means, the first Photoconductor characteristics for evaluating image memory characteristics of the photoconductor using a unit in which the exposure means, the surface potential measuring means, and the second exposure means are sequentially arranged along the outer peripheral surface of the photoconductor In the evaluation method,
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the first exposure means does not irradiate the surface of the photoconductor with the first exposure light. Then, the second exposure means irradiates the surface of the photoconductor with exposure light, then the charging means gives a charge to the surface of the photoconductor, and then the first exposure means uses the surface of the photoconductor. Irradiating the first exposure light, and then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the first exposure unit irradiates the surface of the photosensitive member with a first exposure light, Next, exposure light is irradiated to the surface of the photoconductor by the second exposure unit, and then a charge is applied to the surface of the photoconductor by the charging unit, and then the surface of the photoconductor is applied to the surface of the photoconductor by the first exposure unit. Measuring the surface potential Vd2 of the photoconductor by the surface potential measuring means without irradiating the first exposure light;
Obtaining a value of | Vd1 | − | Vd2 |;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photosensitive member, Next, the first exposure unit does not irradiate the surface of the photoconductor with the first exposure light, and then measures the surface potential Vd3 of the photoconductor by the surface potential measuring unit to obtain a value of | Vd3 | When,
And evaluating the image memory characteristics of the photoconductor from the value of | Vd1 |-| Vd2 | and the value of | Vd3 |.

In order to achieve the above object, another invention according to the present application
In order to form an electrostatic latent image on the photosensitive member, a rotating step by a rotating unit for rotating the cylindrical photosensitive member, a charging step by at least a charging unit for applying a charge to the surface of the photosensitive member, and An image exposing step by the image exposing unit, a surface potential measuring step by a surface potential measuring unit for measuring the surface potential of the photoreceptor, and a developing step by a developing unit for forming a toner image on the electrostatic latent image And an image forming method including a transfer step by a transfer unit for transferring the toner image from the photoconductor to a transfer material, and a pre-exposure step by a pre-exposure unit for discharging the photoconductor.
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the image exposure means does not irradiate the surface of the photoconductor with image exposure light, and then the front The exposure unit irradiates the surface of the photoconductor with exposure light, then the charging unit applies a charge to the surface of the photoconductor, and then the image exposure unit does not irradiate the surface of the photoconductor with image exposure light. And then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit irradiates the surface of the photosensitive member with image exposure light, and then performs the pre-exposure. Means for irradiating the surface of the photoconductor with exposure light, then applying a charge to the surface of the photoconductor with the charging means, and then the image exposure means without irradiating the surface of the photoconductor with image exposure light, Next, the step of measuring the surface potential Vd2 of the photoreceptor by the surface potential measuring means;
Obtaining a value of | Vd1 | − | Vd2 |;
While rotating the photosensitive member by the rotating unit, the transfer unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photosensitive member, Next, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light, and then the surface potential measurement means measures the surface potential Vd3 of the photoreceptor to obtain a value of | Vd3 |
When | Vd1 | − | Vd2 | and / or | Vd3 | exceed a predetermined value, the light amount of the pre-exposure unit is increased, or the voltage applied to the transfer unit is decreased so as to be equal to or less than the predetermined value. It is characterized by adjusting to.

In order to achieve the above object, still another invention according to the present application is as follows:
In order to form an electrostatic latent image on the photosensitive member, a rotating step by a rotating unit for rotating the cylindrical photosensitive member, a charging step by at least a charging unit for applying a charge to the surface of the photosensitive member, and An image exposing step by the image exposing unit, a surface potential measuring step by a surface potential measuring unit for measuring the surface potential of the photoreceptor, and a developing step by a developing unit for forming a toner image on the electrostatic latent image A reverse polarity charging step by a reverse polarity charging means for applying a charge having a polarity opposite to the polarity used in the image forming apparatus to the surface of the photoconductor, and the toner image is transferred to the photoconductor In an image forming method comprising a transfer step by a transfer means for transferring from a transfer material to a transfer material, and a pre-exposure step by a pre-exposure means for discharging the photoreceptor.
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the image exposure means does not irradiate the surface of the photoconductor with image exposure light, and then the front The exposure unit irradiates the surface of the photoconductor with exposure light, then the charging unit applies a charge to the surface of the photoconductor, and then the image exposure unit does not irradiate the surface of the photoconductor with image exposure light. And then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit irradiates the surface of the photosensitive member with image exposure light, and then performs the pre-exposure. Means for irradiating the surface of the photoconductor with exposure light, then applying a charge to the surface of the photoconductor with the charging means, and then the image exposure means without irradiating the surface of the photoconductor with image exposure light, Next, the step of measuring the surface potential Vd2 of the photoreceptor by the surface potential measuring means;
Obtaining a value of | Vd1 | − | Vd2 |;
While the photoconductor is rotated by the rotating unit, the reverse polarity charging unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photoconductor. Then, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light, and then the surface potential measurement means measures the surface potential Vd3 of the photoreceptor to obtain a value of | Vd3 |
When | Vd1 | − | Vd2 | and / or | Vd3 | exceed a predetermined value, the light amount of the pre-exposure unit is increased and / or the voltage applied to the reverse polarity charging unit is decreased to a predetermined value or less. It is characterized by adjusting so that it may become.

  According to the present invention, it is possible to provide a photoreceptor characteristic evaluation method capable of evaluating an image memory characteristic that matches an image output by an image forming apparatus. In addition, it is possible to provide an image forming method capable of outputting a high-quality image regardless of the use environment.

Sectional drawing showing an example of the apparatus for enforcing the photoconductor characteristic evaluation method of this invention. (A) Explanatory drawing for demonstrating the method to measure Vd1. (B) Explanatory drawing for demonstrating the method to measure Vd2. Sectional drawing which shows the manufacturing apparatus for manufacturing the photoreceptor used for this invention. 1 is a cross-sectional view illustrating an example of an electrophotographic apparatus for carrying out an image forming method of the present invention. Explanatory drawing for demonstrating the test chart used by evaluation of the image memory characteristic. (A) Sectional drawing which shows the layer structure of the positively charged photoreceptor used for this invention. (B) Sectional drawing which shows the layer structure of the negatively charged photoreceptor used for this invention. The figure which shows the process of the measurement of Vd3.

The inventors of the present invention have made extensive studies on the evaluation of the image memory characteristics of the photoreceptor.
As a result, it is important to measure the surface potential of the photoconductor when a charge having a polarity opposite to the polarity used in the image forming apparatus (hereinafter referred to as a charging polarity) is applied. I found it.

The reason is considered as follows.
In a recent digital electrophotographic apparatus, a latent image is written by a laser or an LED array after uniform charging to a photoreceptor, and toner is applied to the surface of the photoreceptor on which the latent image is written by a developing unit. The In this case, there are two types of methods: a reversal development method in which a toner image is formed in a portion where a latent image is written by a laser or the like, and a normal development method in which a toner image is formed in a portion where a latent image is not written.

  In the digital electrophotographic apparatus, both the normal development method and the reverse development method can be used. However, from the viewpoint of the light emission intensity and life of the laser and LED array, it is advantageous to reduce the light emission time of the laser and LED array as much as possible, and the reverse development method is often used.

  When the reversal development method is used, for example, the charging polarity of the photoconductor and the charging polarity of the toner are the same polarity so that the polarity of the photoconductor is negative and the polarity of the toner is negative. In the electrophotographic process of the same polarity photoconductor and toner, after the toner image is formed on the photoconductor, an electric field having a polarity opposite to the charged polarity is applied by the transfer charger to transfer the toner image onto the transfer material. Will be applied. At this time, a charge having a reverse polarity may be applied to the surface of the photoreceptor.

  In such an electrophotographic process in which the photosensitive member is given a charge having a polarity opposite to the charged polarity, an image memory may be generated due to the charge having the opposite polarity. Therefore, the image memory finally generated in the image is a memory (hereinafter referred to as a reverse-charged memory) due to the addition of a charge having a reverse polarity to a memory due to image exposure (hereinafter referred to as an optical memory). This is considered to be a combination. Therefore, we inferred the difference in each memory generation mechanism.

  FIG. 6 is a cross-sectional view showing an example of the layer structure of the photoreceptor used in the electrophotographic process. FIG. 6A shows a layer structure of a positive charging photoconductor in which the polarity of the photoconductor is positive, and FIG. 6B shows a layer structure of a negative charging photoconductor in which the polarity of the photoconductor is negative. 6A and 6B, reference numeral 601 denotes a substrate, 602 denotes a lower blocking layer, 603 denotes a photoconductive layer, 604 denotes a surface layer, and 605 denotes an upper blocking layer.

Each layer of the photoconductor ideally has the following functions.
The lower blocking layer 602 has a function of blocking charge injection from the substrate 601 to the photoconductive layer 603. The photoconductive layer 603 has a function of generating charge and a function of transporting charge. Further, the surface layer 604 and the upper blocking layer 605 have a function of holding a charge of charged polarity.

  However, since the film quality of each layer is inferior to that of crystals in the a-Si photoreceptor or the organic photoreceptor, the complete function may not be exhibited. Therefore, a part of the generated charge may be trapped in the photoconductive layer 603, or a part of the charge that should be able to travel in the surface layer 604 may be trapped.

  From the above, the generation mechanism of the optical memory is that the charged charge charged on the photoconductor is partially trapped in the photoconductive layer 603 when the pre-exposure means erases, and the carrier is charged at the next charging. It is assumed that the charging ability increases and the optical memory is generated.

The generation mechanism of reversely charged memory is assumed as follows.
In the electrophotographic process, an electrostatic latent image is formed on a photoreceptor, and the formed latent image is developed as a toner image with toner. A voltage is applied to the formed toner image by a transfer charger, and the toner image is transferred onto a transfer material. At this time, in order to increase the transfer efficiency, a voltage may be applied to the pre-transfer charger to increase the charge amount of the toner.

  In the case of the reversal development method in the electrophotographic process as described above, an electric field having a polarity opposite to the charging polarity is applied by the transfer charger, and a charge having a polarity opposite to the charging polarity is applied to the photosensitive member. There is.

  On the other hand, in the case of the positive development method, an electric field having a polarity opposite to the charging polarity is applied by the pre-transfer charger, and a charge having a polarity opposite to the charging polarity may be applied to the photosensitive member.

  When a charge having a polarity opposite to the charge polarity is applied to the photoconductor, in the case of a negatively charged photoconductor, the positive charge is generally erased by combining with the charged charge in the non-exposed portion.

  On the other hand, since the charged charge has already been erased by light irradiation in the exposed portion, the positive charge may be held. At this time, in order to erase the positive charge charged on the surface of the photoreceptor, it is necessary to inject a negative charge from the substrate 601 side and recombine. However, since this takes time, a part of the positive charge remains. It will be.

  For this reason, the positive charge remaining on the surface partially erases the charged charge applied to the photosensitive member by the charging means in the next step, and a reverse charge memory is generated.

  In addition, when a charge having a polarity opposite to the charge polarity is applied to the photoreceptor, in the case of a positively charged photoreceptor, the negative charge is generally erased by combining with the charged charge in the non-exposed portion.

  On the other hand, since the charged charge has already been erased by light irradiation in the exposed portion, negative charge may be retained. At this time, in order to erase the negative charge charged on the surface of the photosensitive member, it is necessary to inject the positive charge from the substrate 601 side and recombine. However, this takes time, so some of the negative charge remains. It will be.

  For this reason, the negative charge remaining on the surface partially erases the charged charge applied to the photosensitive member by the charging means in the next step, and a reverse charge memory is generated.

  This is presumed to be the generation mechanism of reversely charged memory.

  As described above, the image memory generated when the photoconductor is used in the image forming apparatus includes the optical memory generated by irradiating the photoconductor with light and the reverse charge memory generated by transfer charging or pre-transfer charging. It is thought that That is, since the conventional evaluation of the image memory characteristics of the photoconductor is based on the evaluation of only the optical memory, there is a case where it does not match the image memory of the output image. That is, in order to perform an evaluation that matches the image, a characteristic evaluation method that can evaluate both the optical memory and the reversely charged memory is required.

Since the reverse charging memory has the generation mechanism as described above, it is considered that the degree is determined by how much charge of the reverse polarity can be held by the photosensitive member.
Therefore, the reverse charge memory can be evaluated by measuring the surface potential of the photosensitive member when a charge having a reverse polarity to the charge polarity is applied.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of an apparatus for carrying out the photoreceptor characteristic evaluation method of the present invention. Reference numeral 101 denotes a cylindrical photosensitive member that rotates in the arrow X direction and is perpendicular to the paper surface. The charging unit 102, the first exposure unit 103, the surface potential measurement unit 105, and the second exposure unit 104 are arranged in order along the outer peripheral surface of the photoreceptor 101, and these are attached to the unit 106. It has been. The first exposure means 103 is for irradiating the surface of the photoconductor 101 with first exposure light and forming an electrostatic latent image on the surface of the photoconductor 101. The second exposure means 104 illuminates the surface of the photoconductor 101 with second exposure light and is continuously turned on in order to remove the charge from the photoconductor 101.

  The charging unit 102, the first exposure unit 103, the surface potential measurement unit 105, and the second exposure unit 104 can be attached at arbitrary angular positions in the unit 106, and are sensitive to the radial direction of the photoconductor 101. The structure is such that it can be attached to any position according to the diameter of the body 101. Further, the unit 106 is movable with respect to the bus bar direction of the photoconductor 101 and can measure the photoconductor characteristics at an arbitrary position in the bus bar direction of the photoconductor 101.

  Although a corotron charger is used as the charging unit 102, a contact-type charging roller, a magnetic brush, or a charging brush may be used.

  Further, although an LED is used as the exposure means, it may be configured to irradiate analog light such as a halogen lamp, analog light that has been converted into monochromatic light using a filter or a diffraction grating, laser light, or the like.

  Next, a method for evaluating photoreceptor characteristics using the apparatus shown in FIG. 1 will be described.

  Using a heating means (not shown), the measurement was performed in a state where the surface temperature of the photoconductor 101 was controlled to be constant at 42 ° C. ± 1 ° C. As the heating means, a sheet-like exothermic heater may be provided inside the photoreceptor, and an infrared heating means or a means for heating by contacting a heat source may be used.

  First, the second exposure unit 104 is turned on, the photosensitive member 101 is rotated by a motor (not shown), and the charging unit 102 is set so that a predetermined dark portion surface potential is Vd when the first exposure unit 103 is in a dark state. To determine the total current flowing through In the present invention, the surface potential of the photoreceptor when the first exposure means 103 is in the dark state as described above is referred to as the dark portion surface potential.

  Next, the first exposure unit 103 is set to a bright state, and the light amount of the first exposure unit is determined so that the surface potential becomes a desired value. The amount of light determined by the above procedure is E1.

  As shown in the process of FIG. 2A, the total current determined in the above procedure is supplied to the charging unit 102, the dark portion surface potential is set to Vd, and the first exposure unit 103 is set in the dark state and rotated once. The subsequent dark portion surface potential Vd1 is measured for one round.

  Thereafter, as shown in the process of FIG. 2B, the first exposure unit 103 is set in the bright state, the light exposure E1 is performed for one round, the first exposure unit 103 is set in the dark state, and the dark portion surface potential is set. Vd2 is measured for one round.

  In the above procedure, the dark area surface potential Vd1 when the first circumference of the photosensitive member makes the first exposure means 103 dark, and the first circumference of the photosensitive body 103 makes the first exposure means 103 bright. The dark portion surface potential Vd2 is measured. By comparing Vd1 and Vd2 thus obtained and calculating the difference (| Vd1 | − | Vd2 |), it becomes possible to evaluate the performance of the photoconductor 101 relating to the optical memory.

  That is, while rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the first exposing unit does not irradiate the surface of the photosensitive member with the first exposure light, and then The exposure means irradiates the surface of the photoreceptor with the second exposure means, then charges the surface of the photoreceptor with the charging means, and then the first exposure means irradiates the surface of the photoreceptor with the first exposure light. Next, the surface potential Vd1 of the photoreceptor is measured by the surface potential measuring means.

Thereafter, while rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, then the first exposing unit irradiates the surface of the photosensitive member with the first exposure light, and then the second exposing unit. The exposure means irradiates the surface of the photoreceptor with exposure light, and then the charging means imparts a charge to the surface of the photoreceptor, and then the first exposure means does not irradiate the surface of the photoreceptor with the first exposure light, Next, the surface potential Vd2 of the photoreceptor is measured by the surface potential measuring means. Then, the value of | Vd1 | − | Vd2 | is obtained.
There is a relationship that the larger the value of | Vd1 | − | Vd2 |, the worse the optical memory of the photoconductor 101.

  The dark state is a state in which the LED is turned off when the LED is used as the first exposure unit 103, and the laser beam is reduced to the minimum light amount when the laser beam is used as the first exposure unit 103. It is in the state.

  Moreover, said bright state is the state which lighted LED or the laser beam with the above-mentioned light quantity E1.

Next, the second exposure unit 104 was turned on, the photoconductor 101 was rotated by a motor (not shown), and a current having a polarity opposite to the charging polarity of the photoconductor 101 was passed through the charging unit 102. For example, when the charging polarity of the photoconductor 101 is negative, a positive current having a reverse polarity is caused to flow to the charging unit 102. As a result, a charge having a polarity opposite to the charged polarity of the photoreceptor 101 is applied to the surface of the photoreceptor 101. A predetermined total current is supplied to the charging unit 102, the first exposure unit 103 is set in the dark state, and the dark portion surface potential Vd3 is measured for one round. | Vd3 | obtained in this way is a numerical value representing how much charge of the reverse polarity can be held by the photosensitive member 101.
Therefore, by calculating | Vd3 |, it is possible to evaluate the performance of the reverse charging memory.

That is, while rotating the photosensitive member by the rotating unit, the charging unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photosensitive member. In one exposure means, the surface of the photoreceptor is not irradiated with the first exposure light, and then the surface potential Vd3 of the photoreceptor is measured by the surface potential measurement means to obtain a value of | Vd3 |.
There is a relationship that as the value of | Vd3 | is larger, the reverse charge memory of the photoconductor 101 is worse.

  The current value at the time of measuring Vd3 is preferably selected to be approximately the same as the current value flowing through the photosensitive member 101 by the transfer charger or the pre-transfer charger in the image forming apparatus.

Therefore, the current value at the time of Vd3 measurement is preferably 0.25 μA / cm ^{2 to} 2.50 μA / cm ² .

  By measuring the two values (| Vd1 | − | Vd2 |, | Vd3 |), it is possible to evaluate the image memory characteristics that match the image output by the actual image forming apparatus.

  Further, when developing a new photoconductor, the performance of the reverse charge memory of the photoconductor 101 that cannot be evaluated by the conventional photoconductor characteristic evaluation method and cannot be separated by the image output by the image forming apparatus is represented by (| Vd3 |). Can be evaluated. This makes it easier to take measures to improve the memory with different mechanisms: reversely charged memory and optical memory. Accordingly, it is possible to shorten the development period of a new photoreceptor.

  The value of | Vd1 | − | Vd2 | can be controlled, for example, by adjusting the amount of atoms that control the conductivity contained in the photoconductive layer or by adjusting the power at the time of preparing the photoconductive layer. is there.

  Also, the value of | Vd3 | can be controlled by adjusting the gas mixture ratio at the time of surface layer preparation or the power at the time of surface layer preparation, for example.

Further, the image memory of the image output by setting the photoconductor on the image forming apparatus is digitized by a method described later, and the influence on the image with respect to the two values (| Vd1 | − | Vd2 |, | Vd3 |) is expressed. When the coefficients are α and β, respectively, the following equation (1) is established.
α (| Vd1 | − | Vd2 |) + β | Vd3 | = image memory (numerical value) (1)

  By clarifying the relationship of the expression (1) at the early stage of development of the photoreceptor, if α (| Vd1 | − | Vd2 |) + β | Vd3 | is calculated using the characteristic evaluation apparatus of the present invention, the output It becomes possible to carry out a simulation of the image memory of the processed image. Therefore, it becomes possible to evaluate the level of the image memory of the photoreceptor more accurately. Further, it can be used for determination of the image memory characteristics of the produced photoconductor when the photoconductor is continuously produced without outputting an image.

  As a method for calculating the coefficients α and β representing the influence on the image with respect to the two values (| Vd1 | − | Vd2 |, | Vd3 |), for example, a plurality of photoconductors having different prescriptions are prepared, and two of them are selected. It can be derived by selecting a photoconductor having only one of the values (| Vd1 | − | Vd2 |, | Vd3 |) and comparing it.

  Further, the following effects can be obtained by incorporating the means for measuring the two values (| Vd1 | − | Vd2 |, | Vd3 |) as described above in the image forming apparatus.

  The image forming conditions of the image forming apparatus are variously changed depending on the use environment. However, by using the method of the present invention, it is possible to optimize the image memory characteristics of the photoconductor under any environment.

  That is, two values (| Vd1 | − | Vd2 |, | Vd3 |) are measured in the image forming apparatus, and the image forming conditions are controlled according to | Vd1 | − | Vd2 | and | Vd3 | Environment makes it possible to optimize the image memory for output images.

  The image forming method will be described with reference to FIG.

  First, a normal image forming method using a photoconductor will be described.

  The photosensitive member 401 is rotated in the arrow X direction, and the surface of the photosensitive member 401 is uniformly charged by the charging unit 402. Thereafter, the surface of the photoconductor 401 is irradiated with light by the image exposure unit 403 to form an electrostatic latent image on the surface of the photoconductor 401. The surface potential of the photoreceptor 401 is measured by the surface potential measuring means 416. After the electrostatic latent image is formed, toner is supplied and development is performed. As a result, a toner image is formed on the surface of the photoreceptor 401.

  As a developing device for developing, a first developing device 404 for attaching black toner B, and a rotary second developing device 405 incorporating a developing device for attaching yellow toner Y, magenta toner M, and cyan toner C are provided. ing.

  Next, in order to perform stable transfer, a charge is further supplied to the toner forming the toner image by the pre-transfer charger 406. The toner image is applied to the primary transfer roller 408 from a bias power source (not shown) in the process of passing through the nip portion between the photosensitive member 401 and the intermediate transfer belt 407, whereby the outer periphery of the intermediate transfer belt 407 is Intermediate transfer is sequentially performed on the surface. In general, when the transfer voltage is increased, the transfer efficiency is increased. Therefore, a charge having a polarity opposite to the charge polarity may be applied to the photoconductor during the transfer process.

  Next, the recording material 411 is fed from the paper feed cassette 409 to the contact nip portion between the intermediate transfer belt 407 and the secondary transfer roller 410 at a predetermined timing. The secondary transfer roller 410 is brought into contact with the intermediate transfer belt 407, and a secondary transfer bias is applied to the secondary transfer roller 410 from a bias power source (not shown), whereby the image is transferred onto the intermediate transfer belt 407. The transferred toner image is transferred to the recording material 411. After the transfer of the toner image onto the recording material 411 is completed, the transfer residual toner on the intermediate transfer belt 407 is cleaned by the intermediate transfer belt cleaner 412. The recording material 411 onto which the toner image has been transferred is guided to a fixing device 413 where the toner image is heated and fixed on the recording material 411.

  On the other hand, the toner remaining on the surface of the photoreceptor 401 is removed by the photoreceptor cleaner 414. Thereafter, the surface of the photoconductor 401 is exposed by the pre-exposure unit 415, and the charged charge on the photoconductor 401 is neutralized. Image formation is continuously performed by repeating this series of processes.

  Next, a method for measuring and optimizing two values (| Vd1 | − | Vd2 | and | Vd3 |) using the image forming apparatus of FIG. 4 will be described.

  First, the pre-exposure unit 415 is turned on, the photoconductor 401 is rotated in the direction of the arrow X, and the image exposure unit 403 is in a dark state while observing the value of the surface potential measurement unit 416. The total current flowing through the charging unit 402 is determined so that

  Next, the image exposure unit 403 is set to a bright state, and the light amount of the image exposure unit 403 is determined so that the surface potential becomes a desired value. The amount of light determined by the above procedure is E1.

  The total current determined in the above procedure is supplied to the charging unit 402 to set the dark portion surface potential to Vd, the image exposure unit 403 is set in the dark state, and the dark portion surface potential Vd1 after one rotation is used by the surface potential measuring unit 416. Measure once.

  Next, the image exposure unit 403 is set to the bright state, and the light exposure E1 is performed for one round, and then the image exposure unit 403 is set to the dark state, and the surface potential measurement unit 416 is used to measure the dark portion surface potential Vd2. The Vd1 and Vd2 thus obtained are compared, and the difference | Vd1 | − | Vd2 | is calculated.

  That is, while rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit does not irradiate the surface of the photosensitive member with image exposure light, and then the pre-exposing unit exposes the photosensitive member. Then, the surface of the photosensitive member is irradiated with exposure light, and then a charge is applied to the surface of the photoconductor. Then, the image exposure unit does not irradiate the surface of the photoconductor with image exposure light, and then the surface potential measuring unit is used. The surface potential Vd1 is measured. Thereafter, while rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit irradiates the surface of the photosensitive member with image exposure light. Irradiate the surface with exposure light, and then apply a charge to the surface of the photoreceptor by charging means. Then, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light. The potential Vd2 is measured. Then, the value of | Vd1 | − | Vd2 | is obtained.

  Based on | Vd1 | − | Vd2 | obtained by the above means, for example, by adjusting the light quantity of the pre-exposure means 415, adjustment is made so that | Vd1 | − | Vd2 | does not exceed a predetermined value. . For example, such an adjustment does not have to be performed every time an image is formed, and may be performed in the morning or after a certain time has elapsed.

  Next, the pre-exposure unit 415 was turned on, the photosensitive member 401 was rotated in the direction of arrow X, and a current having a polarity opposite to the charging polarity of the photosensitive member 401 was supplied to the pre-transfer charger 406 or the primary transfer roller 408. In the case of the reversal development method, the primary transfer roller 408 flows to the pre-transfer charger 406 in the case of the positive development method.

  As a result, a charge having a polarity opposite to the charged polarity of the photoreceptor 401 is applied to the surface of the photoreceptor 401.

And Vd3 was measured by the process as shown in FIG.
In FIG. 7, the time during which a predetermined voltage is applied to the pre-transfer charger 406 or the primary transfer roller 408 is set to zero. Then, the time taken to rotate from the pre-transfer charger 406 or the primary transfer roller 408 to the pre-exposure means 415 is t1, and the time taken to rotate from the pre-transfer charger 406 or the primary transfer roller 408 to the surface potential measuring means 416 Was t2, and the time taken for one rotation was t.

  First, the pre-exposure unit 415 is turned on, the image exposure unit 403 is in a dark state, the photoconductor 401 is rotated in the arrow X direction by one or more rotations, and then a predetermined voltage is applied to the pre-transfer charger 406 or the primary transfer roller. 408. Then, after t1 sec, the pre-exposure unit 415 is set in the dark state, and after t2 sec, the surface potential measuring unit 416 is used to measure the dark portion surface potential Vd3 for one round to calculate | Vd3 |.

  At this time, the voltage applied to the pre-transfer charger 406 or the primary transfer roller 408 was turned off after tsec, and the pre-exposure means 415 was turned on after t + t1 sec.

  That is, while rotating the photoconductor by the rotating means, the transfer means or the reverse polarity charging means gives the surface of the photoconductor the polarity opposite to the charge applied to the surface in the electrophotographic apparatus. Then, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light, and the surface potential measurement means measures the surface potential Vd3 of the photoreceptor to obtain the value of | Vd3 |.

  Based on | Vd3 | obtained by the above means, for example, by controlling the voltage applied to the pre-transfer charger 406 or the primary transfer roller 408, adjustment is made so that | Vd3 | does not exceed a predetermined value. . For example, such an adjustment does not have to be performed every time an image is formed, and may be performed in the morning or after a certain time has elapsed.

The image memory for the output image can be optimized by forming an image using the light amount of the pre-exposure means 415 controlled by the above method and the applied voltage of the pre-transfer charger 406 or the primary transfer roller 408. It becomes possible.
The materials used for each layer constituting the photoreceptor will be described below.

(Substrate)
Examples of the photoreceptor substrate used in the present invention include metals such as Al, Cr, Mo, Au, In, Nb, Te, V, Ti, Pt, Pd, and Fe, and alloys thereof such as Al. An alloy and stainless steel are mentioned.

(Lower blocking layer)
As the photoreceptor used in the present invention, it is effective to provide a lower blocking layer having a function of blocking charge injection from the substrate side between the substrate and the photoconductive layer. That is, the lower blocking layer has a function of blocking the injection of charges from the substrate to the photoconductive layer when the free surface of the photoreceptor is charged with a certain polarity. In order to provide such a function, the lower blocking layer contains silicon atoms as a base and a relatively large amount of atoms for controlling conductivity compared to the photoconductive layer.

  Examples of atoms contained in the lower blocking layer for controlling conductivity include so-called impurities in the semiconductor field. Depending on the charge polarity, atoms belonging to Group 13 of the Periodic Table giving p-type conduction characteristics (hereinafter also referred to as “Group 13 atoms”) or atoms belonging to Group 15 of the Periodic Table giving n-type conduction characteristics (hereinafter referred to as “group 13 atoms”) (Also referred to as “Group 15 atom”) can be used. In the case of a negatively charged photoconductor, the lower blocking layer does not necessarily need to be doped with an impurity element, and it has a charge injection blocking capability by optimally containing nitrogen (N) and oxygen (O). May be.

  In the case of a positively charged photoreceptor, the group 13 atoms contained in the lower blocking layer are specifically boron (B), aluminum (Al), gallium (Ga), indium (In), thallium. (Tl) etc. can be mentioned. Boron (B) is particularly preferable.

  Specific examples of the Group 15 atom contained in the lower blocking layer for negative charging include P (phosphorus), As (arsenic), Sb (antimony), and Bi (bismuth). In particular, P (phosphorus) and As (arsenic) are preferable.

(Photoconductive layer)
The photoconductive layer of the photoreceptor used in the present invention preferably contains a silicon atom as a base and further contains a hydrogen atom and / or a halogen atom.
Furthermore, you may make the photoconductive layer contain the atom which controls conductivity as needed.
Examples of the atoms that control conductivity include so-called impurities in the semiconductor field. That is, a Group 13 atom that provides p-type conductivity or a Group 15 atom that provides n-type conductivity can be used.
Specific examples of the Group 13 atom include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), and the like. Boron (B) is particularly preferable.
Specific examples of the Group 15 atom include P (phosphorus), As (arsenic), Sb (antimony), and Bi (bismuth). In particular, P (phosphorus) and As (arsenic) are preferable.
Note that the photoconductive layer may be formed of a single layer, or may have a plurality of structures in which the charge generation layer and the charge transport layer are separated.

(Upper blocking layer)
The upper blocking layer of the photoreceptor used in the present invention is based on silicon atoms and may contain carbon (C), nitrogen (N), and oxygen (O). Furthermore, it has a function of blocking charged charges by containing atoms that control conductivity.
Examples of the atoms that control conductivity include so-called impurities in the semiconductor field. In the case of a negatively charged photoconductor having a negative polarity, it is possible to use a group 13 atom that provides p-type conductivity.
Specific examples of the Group 13 atom include boron (B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), and the like. Boron (B) is particularly preferable.

(Surface layer)
The surface layer of the photoreceptor used in the present invention is provided in order to obtain good characteristics with respect to resistance to continuous repeated use, moisture resistance, use environment resistance, and the like.
In terms of electrical characteristics, it is desirable to have a rectifying property that retains charges of charged polarity and allows charges of opposite polarity to pass.
For the surface layer, for example, an amorphous silicon carbide-based material or an amorphous carbon-based material is used.

  Next, an apparatus and a film forming method for producing the photoreceptor used in the present invention will be described. The apparatus shown in FIG. 3 is an example of a photoconductor manufacturing apparatus by RF plasma CVD using a 13.56 MHz high frequency power source.

  This manufacturing apparatus includes a reaction vessel 301 having a reaction space capable of being vacuum-tight and an exhaust device 308 for decompressing the inside of the reaction vessel 301. In the reaction vessel 301, a substrate heating heater 303, a substrate receiving base 314 connected to the ground, and a source gas introduction pipe 305 are installed. The cylindrical electrode 306 that also serves as the side wall of the reaction vessel 301 is made of a conductive material and is insulated by an insulator 313. A high frequency power supply 312 of 13.56 MHz is connected to the cylindrical electrode 306 via a matching box 311. A cylinder (not shown) of the source gas supply device is connected to a source gas introduction pipe 305 in the reaction vessel 301 via a source gas introduction valve 309.

  Formation of the deposited film using this apparatus can be performed as follows, for example.

  The cylindrical substrate 302 and the cylindrical auxiliary substrate 307 held by the substrate holder 304 are installed on the substrate receiving base 314 so as to include the substrate heater 303 in the reaction vessel 301.

Next, also serving as exhaust in the source gas supply device, the source gas introduction valve 309 is opened, the main valve 315 is opened, and the reaction vessel 301 and the source gas introduction pipe 305 are exhausted. When the reading of the vacuum gauge 310 becomes 0.67 Pa or less, an inert gas for heating (for example, argon) is introduced into the reaction vessel 301 from the source gas introduction pipe 305. Next, the flow rate of the heating gas and the opening amount of the main valve 315 or the exhaust speed of the exhaust device 308 are adjusted so that the inside of the reaction vessel 301 has a desired pressure. Thereafter, a temperature controller (not shown) is operated to heat the cylindrical substrate 302 by the substrate heater 303, and the temperature of the cylindrical substrate 302 is controlled to a predetermined temperature of 150 ° C. to 450 ° C., for example. When the cylindrical substrate 302 is heated to a predetermined temperature, the inert gas is gradually stopped, and at the same time, a gas for forming a deposited film, such as SiH ₄ , Si ₂ H ₆ , CH ₄ , C ₂ H _6, etc. A material gas, a diluent gas such as H ₂ and He, and a doping gas such as B ₂ H ₆ and PH ₃ are mixed by a mixing panel (not shown) and then gradually introduced into the reaction vessel 301. Next, each raw material gas is adjusted to a desired flow rate by a mass flow controller (not shown). At that time, the opening amount of the main valve 315 or the exhaust speed of the exhaust device 308 is adjusted while looking at the vacuum gauge 310 so that the inside of the reaction vessel 301 is maintained at a pressure of 0.1 Pa to several hundreds Pa.

  After completing the preparation for forming the deposited film by the above procedure, the deposited film is formed on the surface of the cylindrical substrate 302. After confirming that the internal pressure is stable, the high-frequency power source 312 is set to a predetermined power and high-frequency power is supplied to the cylindrical electrode 306 to cause high-frequency glow discharge. At this time, by adjusting the matching box 311 so that the reflected wave is minimized, a value obtained by subtracting the reflected power from the high frequency incident power is set to a predetermined value. The gas for forming each deposited film introduced into the reaction vessel 301 is decomposed by this discharge energy, and a deposited film is formed on the surface of the cylindrical substrate 302. During the formation of the deposited film, the cylindrical substrate 302 may be rotated at a predetermined speed by a driving device (not shown).

  The formation of the deposited film is completed as described above. However, when a plurality of deposited films (for example, a lower blocking layer, a photoconductive layer, an upper blocking layer, a surface layer, etc.) are formed, it may be continuously formed by changing conditions. it can. After the formation of all the deposited films is completed, the main valve 315 is closed, an inert gas is introduced into the reaction vessel 301, and after returning to atmospheric pressure, the cylindrical substrate 302 on which the deposited films are formed is taken out.

〔Example〕
Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to these examples.

[Example 1]
Using the photoreceptor manufacturing apparatus shown in FIG. 3, a negatively charged photoreceptor having the layer structure shown in FIG. 6B was prepared on the surface of the cylindrical substrate.
The lower blocking layer 602, the photoconductive layer 603, and the upper blocking layer 605 form a deposited film under the conditions shown in Table 1, and the surface layer 604 forms a deposited film under the conditions shown in Table 2. One was prepared under each condition. The produced negatively charged photoconductors are designated as photoconductors 1 to 3.
The cylindrical substrate 601 was made of aluminum and had an outer diameter of 84 mm, a length of 381 mm, and a wall thickness of 3 mm.
The produced photoconductors 1 to 3 were evaluated for image memory characteristics by the method described later.
The prepared photoreceptors 1 to 3 were installed in the photoreceptor evaluation apparatus shown in FIG. 1, and two values (| Vd1 | − | Vd2 | and | Vd3 |) were calculated.
Details of each evaluation are shown below.

(Image forming method and numerical method)
After the photoconductor is installed in an electrophotographic apparatus as shown in FIG. 4 (a Canon copier iRC6800, modified to a negative charging method for experimentation, and modified to a reversal development method and an image exposure method), A potential sensor (not shown) is installed at a position corresponding to the central position in the longitudinal direction of the photoreceptor at the cyan toner developing unit position in the two developing unit 405.
First, a photoconductor heater (not shown) was turned on, and the surface temperature of the photoconductor 401 was controlled to be constant at 42 ° C. ± 1 ° C.
Next, the pre-exposure unit 415 is turned on, the image exposure unit 403 is set in the dark state, the current flowing through the charging unit 402 is set to −1800 μA, the grid potential is adjusted, and the surface potential of the dark portion of the photosensitive member 401 at the potential sensor position is adjusted. Was set to −450V.
Next, light was irradiated by the image exposure means 403 and the surface energy of the photosensitive member 401 at the potential sensor position was set to −100 V by adjusting the irradiation energy. Thereafter, a potential sensor (not shown) is taken out and a cyan toner developing device is installed.

And the image of the test chart as shown in FIG. 5 was output.
The test chart has a black square with a reflection density of 1.4 in the range of 40 mm □ around the center position of the short side of the A3 chart and the position of 40 mm from the upper end on the upper end side of the image. A halftone (HT) having a reflection density of 0.4 is provided from a position 80 mm from the upper end to a position 5 mm from the lower end.
Using the above test chart, the upper end side of the test chart was placed on the document table, the development bias was adjusted so that the halftone had a reflection density of 0.4, and an A3 electrophotographic image was output.
The output image is read by a scanner (Canon 9900F manufactured by Canon), and the density of the read image is decomposed into 256 gradations using Photoshop. The difference was determined.
The results are shown in Table 5.

(| Vd1 |-| Vd2 |, | Vd3 | measuring method)
In the photoreceptor evaluation apparatus shown in FIG. 1, when the position where the charging means 102 is attached to the unit 106 is 0 ° and the clockwise direction is positive, the second exposure means 104 is at the −30 ° position, The exposure means 103 was attached at a 30 ° position, and the surface electrometer 105 was attached at a 90 ° position.

  As the charging means 102, a corotron charger having an opening of 60 mm and a width of 33 mm was used. The first exposure means 103 and the second exposure means 104 both use LEDs having a wavelength spectrum peak wavelength of 655 nm and a half-value width of 30 nm.

  Using a heating means (not shown), the measurement was performed in a state where the surface temperature of the photoreceptor was controlled to be constant at 42 ° C. ± 1 ° C.

First, the second exposure unit 104 is turned on, the photosensitive member 101 is rotated at 273 mm / sec by a motor (not shown), and the dark portion surface potential Vd of the photosensitive member 101 is − when the first exposure unit 103 is in a dark state. The total current flowing through the charging means 102 was determined to be 450V. At this time, the exposure light quantity of the second exposure means 104 was 4 μJ / cm ² .

  Next, the light quantity of the first exposure unit 103 was determined so that the first exposure unit 103 was in a bright state and the surface potential of the photoconductor 101 was −100V. The amount of light determined by the above procedure is E1.

As shown in the process of FIG. 2A, the total current determined in the above procedure is supplied to the charging unit 102 to set the dark portion surface potential Vd to −450 V, and the first exposure unit 103 is in a dark state. The dark portion surface potential Vd1 after one rotation was measured for one round.
Thereafter, as shown in the process of FIG. 2B, the first exposure unit 103 is set in the bright state, the light exposure E1 is performed for one round, the first exposure unit 103 is set in the dark state, and the dark portion surface potential is set. Vd2 was measured for one round.
| Vd1 | − | Vd2 | was calculated from Vd1 and Vd2 thus obtained.

Further, the second exposure unit 104 is turned on, and a total current is supplied to the charging unit 102 so that the current flowing from the charging unit 102 to the photoconductor 101 becomes +1.75 μA / cm ^2. The dark portion surface potential Vd3 after one rotation was measured in a dark state for one round. The results are shown in Table 5.

[Example 2]
A positively charged photoreceptor having a layer structure shown in FIG. 6A was formed on the surface of the cylindrical substrate.
The lower blocking layer 602 and the photoconductive layer 603 form a deposited film under the conditions shown in Table 3, and the surface layer 604 forms a deposited film under the conditions shown in Table 4. One by one was produced. The produced positively charged photoconductors are designated as photoconductors 4 to 6.
The produced positively charged photoconductors 4 to 6 were evaluated for image memory characteristics by the method described later.
Further, the prepared positive charging photoconductors 4 to 6 were installed in the photoconductor evaluation apparatus shown in FIG. 1, and two values (| Vd1 | − | Vd2 | and | Vd3 |) were calculated.
Details of each evaluation are shown below.

(Image forming method and numerical method)
The current flowing through the charging unit 402 was set to +1800 μA, and the grit potential was adjusted to set the dark portion surface potential of the photosensitive member 401 at the potential sensor position to + 450V.
Further, the surface potential of the photosensitive member 401 at the potential sensor position is set to +100 V by irradiating light by the image exposure unit 403 and adjusting the irradiation energy. Except for the above, the density of the memory portion was calculated in the same manner as in Example 1. The results are shown in Table 5.

(| Vd1 |-| Vd2 |, | Vd3 | measuring method)
The dark portion surface potential of the photosensitive member 101 at the time of measuring Vd1 and Vd2 was set to + 450V. Further, the exposure light amount of the first exposure means 103 at the time of measuring Vd2 was set to the light amount E1 at which the surface potential of the photoconductor 101 becomes + 100V. Further, the total current flowing through the charging unit at the time of Vd3 measurement was set such that the current flowing from the charging unit 102 to the photosensitive member 101 was −1.75 μA / cm ² . Other than that, | Vd1 | − | Vd2 | and | Vd3 | were calculated in the same manner as in Example 1. The results are shown in Table 5.

  As shown in Table 5, the potentials (| Vd1 | − | Vd2 |) representing the optical memories of the photoconductors 1 to 3 are substantially the same, and this alone cannot be evaluated to match the image output by the image forming apparatus.

  In the photoconductor characteristic evaluation apparatus of the present invention, since the potential (| Vd3 |) representing the reverse charge memory is also evaluated, it is possible to evaluate the image memory characteristics of the photoconductor that matches the output image.

  Further, since the potential (| Vd3 |) representing the reverse charge memory that cannot be evaluated by the conventional photoconductor characteristic evaluation method and cannot be separated by the image output by the image forming apparatus can be evaluated independently, each of the reverse charge memory and the optical memory It becomes easy to take improvement measures against. Accordingly, it is possible to shorten the development period of a new photoreceptor.

In the first embodiment, if the coefficients representing the influence on the image with respect to the two values (| Vd1 | − | Vd2 | and | Vd3 |) are α and β, respectively, the potential (| Vd1 | − From the results of the photoreceptors 1 and 3 having the same | Vd2 |), the following expressions (2) and (3) are established.
0.8α + 10β = 6 (2)
0.8α + 20β = 8 (3)

  From now on, the influence α on the image with respect to the potential representing the optical memory (| Vd1 | − | Vd2 |) = 5, and the influence on the image β against the potential representing the reverse charging memory (| Vd3 |) = 0.2. I understand.

  Therefore, if α and β are calculated as described above at the initial stage of development of the photoreceptor, 5 (| Vd1 | − | Vd2 |) +0.2 | Vd3 | is calculated using the characteristic evaluation apparatus of the present invention. By doing so, it becomes possible to carry out a simulation on the quality of the image memory. Therefore, it becomes possible to evaluate the level of the image memory of the photoreceptor more accurately. Further, it can be used for determination of the image memory characteristics of the produced photoconductor when the photoconductor is continuously produced without outputting an image.

Example 3
As in Example 1, according to the conditions of the photoreceptor 3 in Tables 1 and 2, only the amount of B ₂ H ₆ at the time of preparing the photoconductive layer was changed to the conditions shown in Table 6 to form a deposited film, and minus Three charging photoreceptors were produced. The produced negatively charged photoconductors are designated as photoconductors 7 to 9.
The produced photoconductors 7 to 9 were subjected to image output for evaluating the image memory characteristics of the photoconductor in the same manner as in Example 1, and the output images were digitized.
Further, in the same manner as in Example 1, two values (| Vd1 | − | Vd2 | and | Vd3 |) of the created photoreceptors 7 to 9 were calculated.
Further, the two calculated values (| Vd1 | − | Vd2 |, | Vd3 |) are expressed by the equation (5 (| Vd1 | − | Vd2 |) +0.2 obtained from the results of the photoconductors 1 and 3 of Example 1. | Vd3 |) was substituted, and simulation was performed for the quality of the image memory.
The results are shown in Table 7.

  As shown in Table 7, if α and β are calculated in the initial stage of development of the photoreceptor, 5 (| Vd1 | − | Vd2 |) +0.2 | Vd3 | is calculated using the characteristic evaluation apparatus of the present invention. By calculating, it becomes possible to carry out a simulation about the quality of the image memory.

Example 4
The photoconductor 1 produced in Example 1 is an electrophotographic apparatus as shown in FIG. 4 (a Canon copier iRC6800, modified to a negative charging system for experiments, and modified to a reversal developing system for image exposure) ). As described above, this electrophotographic apparatus has been modified so that two values (| Vd1 | − | Vd2 | and | Vd3 |) can be measured in the electrophotographic apparatus. The light quantity of the exposure means 415 and the applied voltage of the primary transfer roller 408 can be controlled. However, during the measurement of | Vd3 |, a predetermined voltage was applied to the primary transfer roller 408.
The electrophotographic apparatus was placed in a high temperature and high humidity environment (temperature: 30 ° C., humidity: 85%), and | Vd1 | − | Vd2 | and | Vd3 | were measured. When | Vd1 | − | Vd2 | exceeded a predetermined value, the amount of light of the pre-exposure unit 415 was controlled so that | Vd1 | − | Vd2 |
Further, when | Vd3 | exceeded a predetermined value, the voltage applied to the primary transfer roller 408 was controlled to adjust | Vd3 | to be equal to or lower than the predetermined value.
After completion of the adjustment, image formation was performed. As a result, a very good image with little image memory was obtained.
Also, when the electrophotographic apparatus is installed in a low-temperature and low-humidity environment (temperature: 13 ° C., humidity: 5%), | Vd1 | − | Vd2 | and | Vd3 | By adjusting, a very good image with little image memory was obtained.

Example 5
The photoconductor 4 produced in Example 2 was installed in an electrophotographic apparatus (Canon copier iRC6800 modified machine) as shown in FIG. As described above, this electrophotographic apparatus has been modified so that two values (| Vd1 | − | Vd2 | and | Vd3 |) can be measured in the electrophotographic apparatus. The amount of light of the exposure unit 415 and the voltage applied to the pre-transfer charger 406 which is a reverse polarity charging unit can be controlled. However, during the measurement of | Vd3 |, a predetermined voltage was applied to the pre-transfer charger 406.
The electrophotographic apparatus was placed in a high temperature and high humidity environment (temperature: 30 ° C., humidity: 85%), and | Vd1 | − | Vd2 | and | Vd3 | were measured. When | Vd1 | − | Vd2 | exceeded a predetermined value, the amount of light of the pre-exposure unit 415 was controlled so that | Vd1 | − | Vd2 |
Also, when | Vd3 | exceeded a predetermined value, the voltage applied to the pre-transfer charger 406 was controlled so that | Vd3 |
After completion of the adjustment, image formation was performed. As a result, a very good image with little image memory was obtained.
Also, when the electrophotographic apparatus is installed in a low-temperature and low-humidity environment (temperature: 13 ° C., humidity: 5%), | Vd1 | − | Vd2 | and | Vd3 | By adjusting, a very good image with little image memory was obtained.

DESCRIPTION OF SYMBOLS 101 Photoconductor 102 Charging means 103 First exposure means 104 Second exposure means 105 Unit 106 Surface potential measurement means

Claims (3)

A rotating means for rotating a cylindrical photoconductor, a charging means for applying an electric charge to the surface of the photoconductor, a first exposure means for irradiating the surface of the photoconductor with a first exposure light, A surface potential measuring means for measuring the surface potential of the photoconductor; a second exposure means for irradiating the surface of the photoconductor with a second exposure light; and the charging means, the first Photoconductor characteristics for evaluating image memory characteristics of the photoconductor using a unit in which the exposure means, the surface potential measuring means, and the second exposure means are sequentially arranged along the outer peripheral surface of the photoconductor In the evaluation method,
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the first exposure means does not irradiate the surface of the photoconductor with the first exposure light. Then, the second exposure means irradiates the surface of the photoconductor with exposure light, then the charging means gives a charge to the surface of the photoconductor, and then the first exposure means uses the surface of the photoconductor. Irradiating the first exposure light, and then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the first exposure unit irradiates the surface of the photosensitive member with a first exposure light, Next, exposure light is irradiated to the surface of the photoconductor by the second exposure unit, and then a charge is applied to the surface of the photoconductor by the charging unit, and then the surface of the photoconductor is applied to the surface of the photoconductor by the first exposure unit. Measuring the surface potential Vd2 of the photoconductor by the surface potential measuring means without irradiating the first exposure light;
Obtaining a value of | Vd1 | − | Vd2 |;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photosensitive member, Next, the first exposure unit does not irradiate the surface of the photoconductor with the first exposure light, and then measures the surface potential Vd3 of the photoconductor by the surface potential measuring unit to obtain a value of | Vd3 | When,
And a step of evaluating image memory characteristics of the photoconductor from the value of | Vd1 | − | Vd2 | and the value of | Vd3 |. In order to form an electrostatic latent image on the photosensitive member, a rotating step by a rotating unit for rotating the cylindrical photosensitive member, a charging step by at least a charging unit for applying a charge to the surface of the photosensitive member, and An image exposing step by the image exposing unit, a surface potential measuring step by a surface potential measuring unit for measuring the surface potential of the photoreceptor, and a developing step by a developing unit for forming a toner image on the electrostatic latent image And an image forming method including a transfer step by a transfer unit for transferring the toner image from the photoconductor to a transfer material, and a pre-exposure step by a pre-exposure unit for discharging the photoconductor.
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the image exposure means does not irradiate the surface of the photoconductor with image exposure light, and then the front The exposure unit irradiates the surface of the photoconductor with exposure light, then the charging unit applies a charge to the surface of the photoconductor, and then the image exposure unit does not irradiate the surface of the photoconductor with image exposure light. And then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit irradiates the surface of the photosensitive member with image exposure light, and then performs the pre-exposure. Means for irradiating the surface of the photoconductor with exposure light, then applying a charge to the surface of the photoconductor with the charging means, and then the image exposure means without irradiating the surface of the photoconductor with image exposure light, Next, the step of measuring the surface potential Vd2 of the photoreceptor by the surface potential measuring means;
Obtaining a value of | Vd1 | − | Vd2 |;
While rotating the photosensitive member by the rotating unit, the transfer unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photosensitive member, Next, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light, and then the surface potential measurement means measures the surface potential Vd3 of the photoreceptor to obtain a value of | Vd3 |
When | Vd1 | − | Vd2 | and / or | Vd3 | exceed a predetermined value, the light amount of the pre-exposure unit is increased, or the voltage applied to the transfer unit is decreased so as to be equal to or less than the predetermined value. An image forming method characterized in that the adjustment is performed. In order to form an electrostatic latent image on the photosensitive member, a rotating step by a rotating unit for rotating the cylindrical photosensitive member, a charging step by at least a charging unit for applying a charge to the surface of the photosensitive member, and An image exposing step by the image exposing unit, a surface potential measuring step by a surface potential measuring unit for measuring the surface potential of the photoreceptor, and a developing step by a developing unit for forming a toner image on the electrostatic latent image A reverse polarity charging step by a reverse polarity charging means for applying a charge having a polarity opposite to the polarity used in the image forming apparatus to the surface of the photoconductor, and the toner image is transferred to the photoconductor In an image forming method comprising a transfer step by a transfer means for transferring from a transfer material to a transfer material, and a pre-exposure step by a pre-exposure means for discharging the photoreceptor.
While rotating the photoconductor by the rotating means, the charging means applies a charge to the surface of the photoconductor, and then the image exposure means does not irradiate the surface of the photoconductor with image exposure light, and then the front The exposure unit irradiates the surface of the photoconductor with exposure light, then the charging unit applies a charge to the surface of the photoconductor, and then the image exposure unit does not irradiate the surface of the photoconductor with image exposure light. And then measuring the surface potential Vd1 of the photoreceptor by the surface potential measuring means;
While rotating the photosensitive member by the rotating unit, the charging unit applies a charge to the surface of the photosensitive member, and then the image exposing unit irradiates the surface of the photosensitive member with image exposure light, and then performs the pre-exposure. Means for irradiating the surface of the photoconductor with exposure light, then applying a charge to the surface of the photoconductor with the charging means, and then the image exposure means without irradiating the surface of the photoconductor with image exposure light, Next, the step of measuring the surface potential Vd2 of the photoreceptor by the surface potential measuring means;
Obtaining a value of | Vd1 | − | Vd2 |;
While the photoconductor is rotated by the rotating unit, the reverse polarity charging unit applies a charge having a polarity opposite to the polarity of the charge applied to the surface in the electrophotographic apparatus to the surface of the photoconductor. Then, the image exposure means does not irradiate the surface of the photoreceptor with image exposure light, and then the surface potential measurement means measures the surface potential Vd3 of the photoreceptor to obtain a value of | Vd3 |
When | Vd1 | − | Vd2 | and / or | Vd3 | exceed a predetermined value, the light amount of the pre-exposure unit is increased and / or the voltage applied to the reverse polarity charging unit is decreased to a predetermined value or less. An image forming method characterized by adjusting to be.