JP2013105008A - Photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoreceptor that notifies a user of the accurate life of the photoreceptor without using a measurement mechanism, a process cartridge, and an image forming apparatus.SOLUTION: A photoreceptor drum 2 having a surface on which an electrostatic latent image developed with a toner is formed includes a CTL layer 23 that includes a visible light region and a UV wavelength region as spectral sensitivity characteristics and the function of which as a photoreceptor is decreased as being scraped off with use over time. A light-shielding layer 24 that absorbs the light or shields the light by changing the color thereof upon receiving light of an ultraviolet wavelength region, is provided in at least part of the CTL layer 23.

Description

  The present invention relates to a photosensitive member on which a toner image is formed, a process cartridge using the photosensitive member, and an electrophotographic image forming apparatus.

  An image forming apparatus of the above type configured as an electronic copying machine, a printer, a facsimile machine, or a multifunction machine having at least two functions thereof is well known. In such an image forming apparatus, the basic structure of an organic photosensitive drum (OPC) for negative charging is an aluminum tube, UCL (Under Coat Layer) from the bottom layer, and CGL which is a functional layer of the photosensitive member. (A charge generation layer, Carrier Generation Layer) and CTL (a charge transport layer, Carrier Transport Layer). The CTL layer, which is the outermost layer, has a characteristic that it is gradually scraped as image formation proceeds.

  When the CTL layer, which is the outermost layer, is scraped off when used over time, the function of the photoreceptor deteriorates. When the function as the photoconductor is lowered, the predetermined image quality cannot be maintained or the image formation itself cannot be performed, and the photoconductor has reached the end of its life. For this reason, it is one of the important requirements for using the device to reliably know the life of the photoreceptor.

  Conventionally, the lifetime of an organic photoreceptor is determined in advance by performing a durability test in a standard environment and usage conditions to obtain the number of printed sheets and the number of rotations of the photoreceptor until the photoreceptor reaches the end of its life. It was set based on. However, since the life of the photoconductor greatly depends on the use environment and use conditions of the image forming apparatus, it is difficult to accurately predict this. For this reason, before reaching the number of prints as the expected life in the market, printed matter with serious quality defects may be output, or the photoconductor may be replaced even though it can be fully used. Sometimes it was done.

  Therefore, a method has been proposed in which the fatigue state of the photoreceptor is detected and the life of the photoreceptor is determined based on the detection result. For example, as a method of detecting the fatigue state of the photoconductor, there is a method of detecting the surface potential of the photoconductor and determining the lifetime of the photoconductor based on the detection result. And a method for determining the life of the photoreceptor by comparing the residual potential with a preset potential value. Patent Document 2 discloses a method for determining the life of a photoconductor according to a difference between a charged potential and a residual potential. Furthermore, in Patent Document 3, for the purpose of determining the lifetime of the organic photoreceptor, the organic photoreceptor, potential detecting means for detecting the residual potential of the organic photoreceptor, and the temperature of the organic photoreceptor are directly or indirectly set. There is disclosed a configuration comprising a temperature detecting means for detecting automatically, and a life judging means for judging the life of the organic photoconductor based on a detected value by the potential detecting means and a detected value by the temperature detecting means.

  With this configuration, it is possible to detect the life of the organic photoreceptor and notify the user, but there is a problem that the error due to the measurement and the cost and space due to the addition of the measurement mechanism increase.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a photoconductor, a process cartridge, and an image forming apparatus capable of notifying a user of an accurate photoconductor lifetime without using a measurement mechanism. It is said.

  In order to achieve the above object, the present invention provides a photosensitive member on which an electrostatic latent image developed with toner is formed on the surface, wherein the outermost layer of the photosensitive member has a visible light region and a UV wavelength region as light sensitivity characteristics. In addition to being a layer that is scraped over time and deteriorates its function as a photoreceptor, at least a part of the outermost layer is provided with a light shielding layer that shields the light when receiving light in the UV wavelength region. A photosensitive member is proposed.

  According to the present invention, the outermost surface layer that has the function of a photoconductor when used over time is provided with a light-shielding layer that shields the light when receiving light in the UV wavelength region, and the image is drawn on the photoconductor by light in the UV wavelength region. Therefore, the life of the photoreceptor can be easily and reliably known.

It is a schematic block diagram which shows the process cartridge which concerns on this invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present invention. FIG. 3 is an explanatory diagram showing a layer of a negatively charged photoreceptor in an embodiment of the present invention. FIG. 4 is an explanatory diagram showing a layer of a photoreceptor showing a modification of FIG. 3. It is explanatory drawing which shows the layer of the photoreceptor of the negative charging characteristic in another embodiment of this invention. FIG. 6 is an explanatory view showing a layer of a photoreceptor showing a modification of FIG. 5. It is a perspective explanatory view showing an example of a display layer. It is a perspective explanatory view showing other examples of a display layer. It is sectional explanatory drawing which shows a stepwise display layer. It is a figure explaining the charge-eliminating image of the charged charge of the photoreceptor which has the light absorption light shielding layer of UV wavelength range. It is a figure explaining the charge-eliminating image of the charged charge of the photoreceptor which has the light shielding layer discolored by the light of UV wavelength range. It is a figure explaining the image forming apparatus which has the light emitting element of UV wavelength range and visible region. It is a figure explaining the image forming apparatus which has the light emitting element of visible region, and the exposure apparatus of UV wavelength range. It is a figure explaining the example of the image pattern for surface layer film thickness confirmation.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing a process cartridge including a photoconductor according to the present invention.

  In FIG. 1, a process cartridge 1 shown here is a cartridge having a structure in which a photosensitive drum 2, a charging member, a developing means 4 and a cleaning means 5 are integrally coupled.

  The photosensitive drum 2 is rotationally driven in a clockwise direction, and a charging roller 3 as a charging member is pressed against the photosensitive drum 2 and is driven to rotate counterclockwise. The charging roller 3 includes a high voltage power source (not shown). A predetermined bias is applied to charge the surface of the photosensitive drum 2.

  The developing device 4 includes a developer storage chamber 40 that stores a developer, and a developer supply chamber 41 that is provided below the developer storage chamber 40. Below the developer supply chamber 41, a developing roller 42, a layer regulating member 43 provided in contact with the developing roller 42, and a supply roller 44 are provided. The developing roller 42 is disposed in contact with the photosensitive drum 2, and a predetermined developing bias is applied from a high voltage power source (not shown). A developer stirring member 45 is provided in the developer storage chamber 40. A developer supply port 46 is formed between the developer storage chamber 40 and the developer supply chamber 41 to supply the developer from the developer storage chamber 40 to the developer supply chamber 41 and to develop the developer. Is prevented from being excessively supplied to the developer supply chamber 41. An agitator 47 for preventing agglomeration of the developer is rotatably provided at the central portion in the developer accommodating chamber 40, and is rotated counterclockwise in the drawing.

The surface of the supply roller 44 is covered with a foam material having a structure having pores (cells), and the developer conveyed into the developer supply chamber 41 is efficiently adhered and taken in, and the development roller 42 The developer is prevented from being deteriorated due to pressure concentration at the contact portion. The foamed material is set to an electric resistance value of 10 ^{3 to} 10 ¹⁴ Ω. An offset voltage is applied to the supply roller 44 as a supply bias with the same polarity as the developer charging polarity with respect to the potential of the developing roller 42. This supply bias acts in a direction in which the precharged developer is pressed against the developing roller 42 at the contact portion with the developing roller 42. However, the polarity of the voltage applied to the supply roller 44 is not limited to this, and the same potential or polarity as the developing roller may be reversed depending on the type of developer. The supply roller 44 rotates counterclockwise to apply and supply the developer adhered on the surface to the surface of the developing roller 42.

A roller coated with an elastic rubber layer is used as the developing roller 42, and a surface coat layer made of a material that is easily charged to a polarity opposite to that of the developer is provided on the surface. The elastic rubber layer is set to a hardness of 50 degrees or less in accordance with JIS-A in order to keep the contact state with the photosensitive drum 2 uniform, and further has an electric resistance of 10 ^{3 to} 10 ¹⁰ Ω in order to act a developing bias. Set to a value. The surface roughness Ra is set to 0.2 to 2.0 μm, and a necessary amount of developer is held on the surface. The developing roller 42 rotates in the counterclockwise direction, and conveys the developer held on the surface to a position facing the layer regulating member 43 and the photosensitive drum 2.

  The layer regulating member 43 is made of a metal leaf spring material such as SUS304CSP, SUS301CSP, or phosphor bronze, and the free end is brought into contact with the surface of the developing roller 42 with a pressing force of 10 to 100 N / m. The developer that has passed through is thinned and charged by triboelectric charging. Further, a voltage offset to the same polarity as the charging polarity of the developer with respect to the potential applied to the developing roller 42 is applied to the layer regulating member 43 as a regulating bias in order to assist frictional charging.

  The photosensitive drum 2 rotates in the clockwise direction, and therefore, the surface of the developing roller 42 moves in the same direction as the traveling direction of the photosensitive drum 2 at a position facing the photosensitive drum 2. The thinned developer on the developing roller 42 is conveyed to a position facing the photosensitive drum 2 by the rotation of the developing roller 42, and the developing bias applied to the developing roller 42 and the static on the photosensitive drum 2. The electrostatic latent image formed on the surface of the photosensitive drum 2 is developed by moving to the surface of the photosensitive drum 2 in accordance with the latent image electric field formed by the electrostatic latent image.

  A sealing seal 48 is provided in contact with the developing roller 42 at a portion where the developer remaining on the developing roller 42 without being developed on the photosensitive drum 2 returns to the developer supply chamber 41 again. The developer is sealed so as not to leak out of the developing device.

  The process cartridge 1 is filled with toner manufactured by a pulverization method or a polymerization method. The toner can also use silica containing silicon oil as an external additive. The effect of using silica containing silicon oil as an external additive is that the life of the process cartridge 1 is extended, the cleaning property is improved, and the transfer efficiency is improved.

FIG. 2 is a schematic view of the entire color image forming apparatus using the process cartridge.
In FIG. 2, when the yellow, cyan, magenta, and black process cartridges 1Y, 1C, 1M, and 1Bk configured as described above are mounted on the apparatus main body 10, the photosensitive drum 2 is an intermediate formed by an endless belt by a stopper (not shown). The process cartridge is fixed at a position in contact with the upper running side of the transfer belt 11, and each process cartridge can be replaced by releasing the stopper.

  An image forming process by the image forming apparatus will be described. When the photosensitive drum 2 is driven to rotate clockwise, the surface of the photosensitive drum is uniformly charged to a predetermined polarity by the charging member 3. The charged surface is irradiated with light-modulated laser light emitted from an exposure device 6 disposed in the upper part of the apparatus main body 10, and an electrostatic latent image corresponding to the writing information is formed on the surface of the photosensitive drum 2Y. The In the example shown in FIGS. 1 and 2, a charging roller is used as the charging member 3. However, a charging member 3 including a corona discharger or a charging blade can also be used. Similarly, in the image forming apparatus shown in FIG. 1, an exposure apparatus 6 including a laser writing apparatus that emits laser light is used. However, an exposure apparatus having an LED array and an image forming unit can also be used.

  The electrostatic latent image formed on each process cartridge 1 is visualized as a toner image of each color when it passes through the developing means 4. The developing means 4 shown here is one-component contact development, and visualizes the electrostatic latent image on the photosensitive drum 2 as a toner image. A predetermined developing bias is supplied to the developing means 4 from a high voltage power source (not shown).

  On the other hand, inside the intermediate transfer belt 11 which is an endless belt, a transfer roller 7 is disposed as a primary transfer unit positioned opposite to the photosensitive drum 2 with the intermediate transfer belt 11 interposed therebetween. A transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the photosensitive drum 2 is applied to the transfer roller 7. As a result, a transfer electric field is formed between the photosensitive drum 2 and the intermediate transfer belt 11, and the toner image on the photosensitive drum 2 is rotated on the intermediate transfer belt 11 in synchronization with the photosensitive drum 2. Is electrostatically transferred to.

  The transfer residual toner adhering to the surface of the photosensitive drum 2 after the toner image is transferred to the intermediate transfer belt 11 is removed by the cleaning unit 5 and the surface of the photosensitive drum 2 is cleaned.

  Thus, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are formed on the photosensitive drums 2 of the process cartridges 1Y, 1C, 1M, and 1Bk, respectively. The toner images of these colors are electrostatically transferred onto the intermediate transfer belt 11 in order by being transferred by a transfer unit constituted by the transfer roller 6. In this way, toner images of different colors formed on each of the plurality of image carriers are electrostatically transferred while being superimposed on the intermediate transfer belt 11, so that a full color image is formed. The formed full-color image is transferred to a sheet 9 as a transfer material by applying a predetermined voltage between the secondary transfer roller 8 and the intermediate transfer belt 11, and is applied onto the sheet 9 by the fixing device 12. The transferred developer image is fixed by heat and pressure and output. The developer remaining on the intermediate transfer belt 11 without being transferred by the secondary transfer roller 8 is removed by the transfer belt cleaning means 13 and collected.

  If the photosensitive drum 2 is a negatively charged organic photosensitive member, the structure thereof is as shown in FIG. 3, from the bottom layer to the aluminum base tube 20, a UCL layer 21 (undercoat layer, Under Coat Layer), A CTL layer 23 (charge transport layer, Carrier Transport Layer), which is a functional layer, is coated on a layer made of the CGL layer 22 (charge generation layer, Carrier Generation Layer). The CTL layer 23, which is the outermost layer, has a characteristic that it is gradually scraped as image formation proceeds. When this layer is almost lost or thinned to some extent (about 10 μm in the current model), it functions as a photoconductor. Cannot be obtained. That is, even if it is charged, no charge is charged on the photoreceptor.

Therefore, the present invention is configured as follows in order to inform the user of the proper life of the photoreceptor simply and reliably.
A light shielding layer 24 in which fine particles 25 that absorb light in the UV wavelength region are dispersed is provided on the CTL layer 23 that is the outermost layer. The light shielding layer 24 is shaved by use over time as in the case of the CTL layer 23. However, while remaining uncut, the light shielding layer 24 absorbs and shields light in the UV wavelength region, thereby forming an image drawing by light in the UV wavelength region. I can't. The light shielding layer 24 in which the fine particles 25 that absorb light in the UV wavelength region shown in FIG. 3 are dispersed is provided only in a specific region, but the light shielding layer 24 is formed on the entire surface of the photoreceptor surface as shown in FIG. May be provided.

  Thus, the light shielding layer 24 in which the fine particles that absorb light in the UV wavelength region are dispersed is provided in the entire region of the CTL layer 23 shown in FIG. 4 or a limited region of the printing region shown in FIG. The light shielding layer 24 has the same upper surface as the outermost CTL layer 23, and its layer thickness is slightly thinner than the CTL layer 23, and its lower surface is positioned slightly above the lower surface of the CTL layer 23. Therefore, the thickness is close to the limit at which the charging / exposure function as a photoreceptor stops functioning, and remains when the light-shielding layer 24 in which fine particles that absorb light in the UV wavelength region are dispersed is polished and disappears. It is desirable that the thickness of the CTL layer 23 is a limit at which a last-minute image can be drawn. That is, the thickness of the remaining CTL layer 23 is about 10 μm although it varies depending on the model and characteristics of the photoconductor used.

  The fine particles 25 dispersed in the light shielding layer 24 are particles that absorb and block light in the UV wavelength region, but transmit almost 100% of light in other wavelength regions (for example, visible light). As the manufacturing method, it can be formed by using a dip method, a spray method, or an ink jet method. The dip method is a method in which the photosensitive member is applied by being submerged in a coating solution and pulled up. The spray method is a method in which the photosensitive member is rotated and applied to the surface using a spray. For example, a CTL layer coating solution (CTL coating solution) in which the CTL layer is manufactured in a normal manufacturing process (existing process such as a dip method) and fine particles that absorb light in the UV wavelength range are further dispersed on the photoreceptor. A) except for the portion to be applied is masked, and the CTL coating solution A is applied using an existing film forming process such as a dip method or a spray method.

  As another method of applying the CTL coating solution A, there is also a method of applying using an inkjet. As another method, there is a method in which fine particles that absorb light in the UV wavelength region are driven into the CTL layer, which is the outermost layer of the photoreceptor manufactured up to the CTL layer, with an air gun or the like.

  The photosensitivity to the exposure of the photoreceptor is sensitive to both light in the visible light region and light in the UV wavelength region. With this configuration, while the light shielding layer 24 in which fine particles that absorb light in the UV wavelength region are dispersed is present, an image cannot be drawn when the light is drawn in the UV wavelength region. Drawing is possible only when drawing is performed with light in the light region. If printing is continued and the light-shielding layer 24 in which fine particles that absorb light in the UV wavelength region are dispersed is scraped and disappears, it becomes possible to draw an image with both light in the UV wavelength region and light in the visible light region.

  By utilizing these characteristics, it is possible to inform the user of the life of the photoreceptor. For example, when an attempt is made to draw a message such as “photosensitive element has a lifetime” with light in the UV wavelength region as a check image, the light shielding layer 24 in which fine particles that absorb light in the UV wavelength region are dispersed remains. In this case, the print image is printed as blank paper. On the other hand, in a state in which the light shielding layer 24 in which fine particles that absorb light in the UV wavelength range are dispersed is scraped, it is possible to print a message “photoconductor is at the end of life” on a printed image.

  FIG. 5 shows another embodiment of the present invention. The basic configuration and characteristics are the same as those of the photoconductor provided with the light shielding layer 24 described in FIG. Therefore, the description of the same configuration is omitted to avoid complicated description.

  The light shielding layer 24 in FIG. 3 disperses the fine particles 25 that absorb light in the UV wavelength region, but in FIG. 5 of the present embodiment, the color is changed by absorbing light in the UV wavelength region, and the visible light region used for exposure. It is characterized in that a part of the CTL layer 23 has a light shielding layer 24A in which fine particles 25A having a characteristic of shielding the light of 25 are dispersed.

  FIG. 6 shows another embodiment of the present invention, but the basic configuration and characteristics are the same as those of the photoconductor provided with the light shielding layer 24 described in FIG. Therefore, the description of the same configuration is omitted to avoid complicated description.

  The light shielding layer 24 in FIG. 4 disperses the fine particles 25 that absorb light in the UV wavelength region, but in FIG. 6 of this embodiment, the color changes by absorbing light in the UV wavelength region, and the visible light region used for exposure. The light-shielding layer 24 </ b> A in which the fine particles 25 </ b> A having the property of shielding the light is dispersed is provided over the entire area of the CTL layer 23.

  FIG. 7 is a perspective view showing light shielding layers 24 and 24A provided on a part of the CTL layer 23 on the surface of the photoreceptor. The light shielding layers 24 and 24A are distributed at least in the printing region. This print area is based on the maximum width paper that can be used in the image forming apparatus. In addition, although the shape of the light shielding layer 24 is represented by a rectangular patch pattern in the illustrated example, the shape can be arbitrarily changed. For example, the light shielding layer 24 may be a mark such as a circle, a triangle, or a belt, or a message having a message property such as “Good” or “NotEmpty”.

  FIG. 8 shows the light shielding layers 24 and 24A dispersed in almost the entire printing area of the photosensitive member. This print area is based on the maximum width paper that can be used in the image forming apparatus.

  Thus, when the photosensitive member has fine particles 25 and 25A that react to light in the UV wavelength region over the entire print image region, drawing with light in the UV wavelength region and light irradiation in the UV wavelength region are usually performed. By combining drawing with light in the wavelength range, it is possible to print an arbitrary message that conveys the deterioration state of the photoreceptor to the user.

  FIG. 9 is an explanatory view showing another embodiment of the present invention. In this example, light shielding layers 24a and 24b having different layer thicknesses are provided at different locations. Both the light shielding layer 24a and the light shielding layer 24b are in contact with the upper end of the CTL layer 23, but the lower portion is different from the thickness d1 and the thickness d2 in which the lower end of the CTL layer 23 is changed. That is, the thickness d1 is a thick layer provided with the fine particles 25 dispersed, the thickness d2 is a thin layer provided with the fine particles dispersed, and the light shielding layer 24 having a relationship of d1> d2 is provided on the photoreceptor. At least one set is provided.

  Thus, by providing the thickness of the light shielding layer 24 in two or more steps, a warning is given when the thickness of the layer in which fine particles that react to light in the UV wavelength region of the outermost layer are distributed is reduced. Can be shown. For example, it is possible to provide several stages of indicators (film thickness remaining amount meter) until the film thickness reaches the limit for maintaining the function of the photoconductor, It is possible to notify the user by printing the film thickness check pattern.

FIG. 10 is a diagram for explaining an image of charge removal on a photosensitive member having a light-absorbing light-shielding layer in the UV wavelength region.
The photoreceptor 2 charges the surface of the photoreceptor using a charging roller or the like in a charging process. A commonly used photoconductor has a function of removing charged charges at a place irradiated with laser light in the visible light region or light such as an LED. Therefore, as shown in FIG. 10A, even if the surface of the photoreceptor is irradiated with light in the UV wavelength region and is exposed to light in the visible light region, the light shielding layer changes color with UV light that has absorbed the light in the UV wavelength region. Since 24 changes color and blocks the light in the visible light region, the light cannot reach the CGL layer 22 that generates the counter charge, and it becomes impossible to remove the charged charges.

  When the light shielding layer 24 that absorbs light in the UV wavelength region on the surface of the photoconductor is scraped and disappears as shown in FIG. 10B, the state is the same as when the light in the UV wavelength region is not irradiated. Therefore, since the light in the visible light region reaches the CGL layer 22 and can generate a counter charge, the charged charge can be removed. The photosensitivity characteristics of the photoconductor in this case need to have exposure sensitivity only for light in the visible light region used for normal exposure.

FIG. 11 is a diagram for explaining an image of charge removal on a photosensitive member having a light shielding layer that changes color with light in the UV wavelength region.
The photosensitive member 2 charges the surface of the photosensitive member 2 using a charging roller or the like in a charging process. The photoconductor 2 that is generally used has a function of neutralizing charged charges at a place irradiated with laser light in the visible light region or light L1 such as an LED. Therefore, as shown in FIG. 11A, when the photosensitive member surface layer (CTL layer 23) is exposed without being irradiated with light L2 in the UV wavelength region, or when exposure is performed with light in the UV wavelength region, visible light is visible. Since the exposure light L1 in the light region reaches the CGL layer 22 and can generate a counter charge, it is possible to remove the charged charge.

  However, as shown in FIG. 11B, the light-shielding layer 24 that changes color with UV light that absorbs light in the UV wavelength region even when exposed to light in the visible light region immediately after irradiation with light in the UV wavelength region changes color. Since the light in the visible light region is shielded, the light cannot reach the CGL layer 22 that generates the counter charge, and it becomes impossible to remove the charged charges. The photosensitivity characteristics of the photoreceptor 2 in this case need to have exposure sensitivity only for light in the visible light region used for normal exposure.

FIG. 12 is a diagram illustrating an image forming apparatus having light emitting elements in the UV wavelength region and the visible light region.
In FIG. 12, when the photosensitivity characteristic of the photoconductor has sensitivity in both the UV wavelength region and the visible light region used for normal exposure, the light source for irradiating and exposing the polygon mirror is used for normal exposure. By having the laser diode LD30 in the visible light region and the laser diode LD31 in the UV wavelength region, the remaining amount of the photoreceptor film thickness is obtained by utilizing the principle that the layer that absorbs the UV wavelength region is polished and disappeared by printing. A message can be printed to notify the user.
In this case, in normal printing, an image is printed using the LD 30 in the visible light region, and when checking the film thickness of the photoreceptor, the film thickness check pattern is drawn using the LD 31 in the UV wavelength region. It becomes possible to judge.

FIG. 13 is a diagram showing a modification of FIG.
When the photosensitivity characteristic of the photoconductor is sensitive only to the visible light region used for normal exposure, the UV wavelength exposure device 32 and the photoconductor layer provided with the laser diode LD30 for drawing and the photoconductor layer have UV wavelengths. By combining the function of changing the color so as to block the light in the visible light region when receiving the light in the region, a message for notifying the user of the remaining amount of the photoreceptor film thickness can be printed.

  In this case, in normal printing, when light in the UV wavelength region is turned off to print an image using the LD 30 in the visible light region and the film thickness of the photoreceptor is checked, the light in the UV wavelength region is used. Is exposed to light by the exposure device 32, and a film thickness check pattern is drawn using an LD in the visible light region, so that the layer that changes color in response to UV light is polished by printing and disappears (has reached the end of its life). It becomes possible to judge whether it is.

  In the present invention, the time to examine the life of the photosensitive member by irradiating with light in the UV wavelength range is arbitrary, but it is set, for example, when the main switch is turned on or whenever the number of printed sheets reaches a predetermined number. Can do.

FIG. 14 is a diagram for explaining an example of the surface layer thickness confirmation image pattern.
A reference image pattern 33 that is exposed and drawn with light in a normal visible light region is configured by printing solid to white densities at several density levels. The density level can be used without any problem regardless of whether it is constituted by either an analog development system using bias control or a digital development system using a gradation pattern.

  The image pattern for check 34 is a film whose surface density is solid when a solid image is printed with light in the UV wavelength region, depending on the remaining amount of the layer that absorbs light in the UV wavelength region on the surface of the photoconductor. The characteristic that the density is reduced depending on the thickness is obtained. Therefore, a reference image pattern 33 drawn by exposure with light in a normal visible light region and a check image pattern 34 drawn with light in the UV wavelength region are printed, and both print patterns are compared for checking. The density of the image pattern 33 and the reference image pattern 34 at the same level can be determined as the film thickness state of the photoreceptor 2.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited only to the said embodiment, Various modifications can be made.
For example, in the above-described embodiment, the photosensitive drum has been described as the photosensitive member. However, the photosensitive member is not limited to the drum-shaped member, and may be a belt shape, for example, an endless belt. Furthermore, the present invention is not limited to the one-component type developing device, and can be applied to a two-component type developing device. Furthermore, the present invention can be applied even if the developing means is an apparatus that employs reversal development.

  Furthermore, in the above embodiment, the negatively charged organic photoconductor has been described. However, the photoconductor of the present invention is a single layer in which a CGL layer and a CTL layer, which are functional layers, are integrated with a UCL layer on an aluminum base tube, for example. The present invention can also be applied to an organic photoreceptor for positive charging provided with a certain charge generation / transport layer.

DESCRIPTION OF SYMBOLS 1 Process cartridge 2 Photosensitive drum 4 Developing means 11 Intermediate transfer belt 23 CTL layer 24, 24A Light shielding layer 25, 25A Fine particle

JP-A-9-190120 JP 2010-128012 A

Claims (12)

In the photoreceptor on which an electrostatic latent image developed with toner is formed on the surface,
The outermost layer of the photoconductor has a visible light region and a UV wavelength region as photosensitivity characteristics, and is a layer whose function as the photoconductor is reduced by being worn over time,
A photoreceptor having a light-shielding layer that shields light when receiving light in a UV wavelength region on at least a part of the outermost layer.   2. The photoreceptor according to claim 1, wherein when the light shielding layer receives light in a UV wavelength region, the photoreceptor is discolored and shielded.   2. The photosensitive member according to claim 1, wherein when the light shielding layer receives light in a UV wavelength region, the light shielding layer absorbs the light and shields it.   3. The photosensitive member according to claim 1, wherein the light shielding layer is a layer in which fine particles that change color when receiving light in the UV wavelength range are dispersed.   4. The photoreceptor according to claim 1, wherein the light shielding layer is a layer in which fine particles that absorb light when receiving light in a UV wavelength region are dispersed.   6. The photoreceptor according to claim 1, wherein a plurality of the light shielding layers are provided on the outermost layer, and the thickness of the light shielding layers is different in two or more steps.   7. The photosensitive member according to claim 6, wherein the light shielding layers having different layer thicknesses are arranged so that a distance from a lowermost part of the layer to a lowermost part of the outermost layer is different.   8. The photoreceptor according to claim 1, wherein the light shielding layer forms a design in which the fine particles provided have a message property.   9. The photosensitive member according to claim 1, wherein the light shielding layer is formed over the entire printing area.   A process cartridge using the photosensitive member according to claim 1.   10. An image forming apparatus using the photosensitive member according to claim 1, wherein the photosensitive member is exposed to a UV wavelength region in addition to a visible light region laser diode for forming an electrostatic latent image. An image forming apparatus comprising a light emitting device for irradiating a charged photoreceptor with light.   10. An image forming apparatus using the photosensitive member according to claim 1, wherein a laser diode in a visible light region and a laser diode in a UV wavelength region for exposing the photosensitive member to form an electrostatic latent image. An image forming apparatus comprising the two types of exposure light sources.

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