JP5344280B2 - Electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically release electrostatic fatigue of a photoreceptor, to automatically reduce VL and VR increase, and to suppress the electrostatic fatigue more effectively than ever. <P>SOLUTION: In an image forming apparatus having the photoreceptor 12 and an optical antistatic device 17, optical quantity of 10 W/m<SP>2</SP>is radiated from the optical antistatic device to the photoreceptor. At this optical quantity, a reduction speed absolute value B or C of VL or VR when charging is not performed, the photoreceptor is driven at the photoreceptor speed, and light is radiated from the optical antistatic device to the photoreceptor is equal to or larger than increase speed absolute value A of VL or VR when the photoreceptor is driven, charging is performed, electricity is removed in an existing image forming condition where the photoreceptor speed is 630 mm/s, photoreceptor charging potential for image forming is -800 V, and antistatic light quantity after image forming is 1 W/m<SP>2</SP>. In this condition, continuous repetition of image forming increases residual potential in the photoreceptor. Alternatively, an image is formed in the existing image forming condition, and the electricity of the photoreceptor is removed at a predetermined timing and at photoirradiation mode light quantity of 30 W/m<SP>2</SP>. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called electrophotographic image forming apparatus in which image light is exposed to a charged photoreceptor to form an electrostatic latent image, which is developed and transferred to a sheet as a toner image. Although not intended to be limited, VL (photoconductor surface potential of a solid image portion when a photoconductor is exposed to form a solid image), VR (photosensitive after static elimination) of a photoconductor containing titanyl phthalocyanine as a charge generation material. The present invention relates to a technique for preventing an increase in body surface residual potential). The image forming apparatus of the present invention can be used in, for example, a printer, a copying machine, and a facsimile.

JP 2004-286887 A JP 2007-233116 A JP 2007-233348 A Japanese Patent Application Laid-Open No. 2008-122740.

  In electrophotographic image formation, the photoreceptor is fatigued by repeated use, and VL rises, resulting in abnormal images such as density reduction and background smearing. The higher the sensitivity of the photoconductor, the stronger the tendency, and this is remarkable in the high-sensitivity organic semiconductor including the charge generation material. Examples of the charge generation material include phthalocyanines, and titanyl phthalocyanine is often used (Patent Documents 1 to 4).

  In general, an electrophotographic photoreceptor used in an electrophotographic image forming apparatus is a so-called so-called electrophotographic photosensitive member in which a charge generation layer is formed directly or via an intermediate layer on a conductive support and a charge transport layer is provided thereon. The function-separated type laminated photoconductor is the mainstream. Furthermore, a surface protective layer is formed on the outermost surface of the photoreceptor as necessary to improve mechanical or chemical durability. In this function-separated laminated photoconductor, when a photoconductor whose surface is charged is exposed, light passes through the charge transport layer and is absorbed by the charge generation material in the charge generation layer. The charge generating material absorbs this light and generates charge carriers. The generated charge carriers are injected into the charge transport layer and move along the electric field generated by charging to neutralize the surface charge of the photoreceptor. As a result, an electrostatic latent image is formed on the surface of the photoreceptor. However, if the charge carriers are trapped in the trap generated in the bulk of the charge transport layer in the process of moving the charge carriers in the charge transport layer, not only can the surface charge of the photoreceptor be neutralized, but also the electric field strength is weakened. That is, it becomes difficult to neutralize the charge on the surface in the photosensitive member exposure portion, and thus VL and VR increase.

  When VL and VR rise, the developing potential, which is the potential difference between the developing bias applied between the developing device and the photosensitive member for developing the electrostatic latent image, becomes smaller, and the image density is lowered. For such a decrease in the development potential, a technique is used in which the increase amount of VL is detected, and the increase amount is added to the development bias and the photosensitive member charging potential to control the development potential to be constant.

  When VL rises, the VL rise amount is added to the charging potential as well as the developing bias. When only the developing bias is increased, the difference between the charging potential and the developing bias becomes small, and development to the non-exposed portion of the photoreceptor is likely to occur. This is because the fog density increases, but there is a limit in increasing the photosensitive member charging potential because there is a risk of dielectric breakdown due to the fact that the electric field strength becomes too strong when the photosensitive member charging potential is increased. Therefore, in the control in which the VL increase amount is added to the development bias and the charging potential, the limit value of the VL increase amount depends on the limit value of the charging potential. Therefore, when the VL increase amount exceeds the limit value, appropriate control cannot be performed. .

  Therefore, in Patent Document 3, an intermediate layer disposed between a conductive support and a charge generation layer in a photoreceptor contains rutile titanium oxide, which is a metal oxide that absorbs writing light, and an optical carrier is used in the intermediate layer. The VL rise is suppressed by generating. Patent Document 1 includes two or more fillers in the protective layer resin of the photoreceptor surface layer, and one of them is diamond-like carbon or amorphous carbon fine particles having an average particle size of 50 nm or less. Suppresses VL rise.

  Various techniques for reducing the increase in VL by changing the prescription and configuration of the photoconductor are disclosed, but the electrostatic fatigue of the photoconductor varies greatly depending on the photoconductor prescription or process conditions. From this point of view, it is necessary to deal with each process condition.

  SUMMARY OF THE INVENTION An object of the present invention is to automatically release electrostatic fatigue of a photoreceptor in an image forming apparatus, and specifically to reduce VL and VR rise automatically. In other words, the object is to more effectively suppress electrostatic fatigue than in the past.

  The present inventor repeated experiments aiming to reduce the increase in VL by automatic control in the main body of the image forming apparatus as well as the improvement of the photoreceptor, and in the process, increased by giving strong energy to the photoreceptor. The VL was successfully returned to the initial state. When strong energy is applied to the photoconductor, the potential carriers trapped in the charge transport layer causing the increase in VL react with the light energy to release the charge carriers and suppress the increase in VL. Therefore, the image forming apparatus of the present invention is configured as follows.

(1) In an electrophotographic image forming apparatus comprising a photoconductor (12) and a photostatic device (17) that neutralizes residual charges on the surface of the photoconductor by light irradiation.
When the image formation is repeated, a residual potential rises on the photoconductor (12), the photoconductor speed (630mm / sec), the photoconductor charge potential for image formation (-800V), and the static charge after image formation (1W / m ² ) When the photosensitive member (12) is driven and charged under the predetermined image forming conditions, and the static eliminator (17) is used for static elimination, charging is performed with respect to the absolute increase rate A of VL or VR. VL or VR decrease rate when the photosensitive member (12) is driven at the photosensitive member speed (630 mm / sec) without irradiating and the photosensitive member (12) is irradiated with light from the light neutralizing device (17). absolute value B or C, equal to or greater-than imaging of repetition is constant no increase between VL successive quantity (10 W / m ^2), the photosensitive member from said optical discharging device (17) (12) Electrophotographic image forming apparatus characterized by irradiating:
VL: Photoconductor surface potential of a solid image portion when the photoconductor is exposed to form a solid image VR: Photoconductor surface residual potential after static elimination.

  In the parentheses, symbols for corresponding elements or corresponding matters in the embodiments shown in the drawings and described later are added for reference. The same applies to the following.

  That is, the photocharger (17) increases the charge carriers trapped by repeated use of the photoconductor (12), increasing the residual potential of the photoconductor (12) and increasing VL and VR. The trapped charge carriers are released by applying light energy to the photoconductor (12), and increase in VL and VR due to long-term use of the photoconductor (12) is suppressed. Energy is continuously given to the photosensitive member (12) by the static elimination light, and the light static elimination device (17) gives the photosensitive member (12) a light amount in a range where VL and VR do not rise. There is no deterioration in image quality due to increase in VL and VR due to long-term use.

(2) In an electrophotographic image forming apparatus comprising: a photoconductor (12); and a photostatic discharger (17) having a variable irradiation light amount that discharges residual charges on the surface of the photoconductor by light irradiation.
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value (450 sec), the VL increase amount ΔVL = ∫A during the image formation completion time is set to , Based on the VL rising speed A (FIG. 4) at the light quantity of the light neutralizing device (17) under the predetermined image forming conditions and the integrated time at the end, and calculating the light under the predetermined image forming conditions. using the light intensity of the discharger ^{(17) (1W / m 2} ) VL decrease speed absolute value B of a larger light irradiation mode quantity (30W / m ²⁾ (Fig. 5), the light irradiation mode execution time T = .DELTA.VL / B is calculated, the photoconductor (12) is driven, the photoconductor (12) is not charged, and the photoconductor (12) is set to the light irradiation mode light amount (30 W / m ² ) as the light quantity of the light neutralization device (17). ), And when the time T has elapsed, the charge removal is stopped and the integrated time for image formation is initialized.

  According to this, since the amount of static elimination light is variable, the light irradiation mode is executed at a predetermined timing according to the predicted VL increase amount, the light irradiation mode is executed, and the VL is always reduced. Energy saving can be achieved as compared with the case where light irradiation is performed with a strong light amount, and image quality deterioration due to increase in VL due to long-term use of the photoconductor (12) does not occur.

(3) An electrophotographic apparatus having at least one light irradiation device (8) for irradiating light to the photoconductor (12) in the same manner as the photostatic device (17), in addition to the photoconductor (12) and the photostatic device (17). In the image forming apparatus,
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value (450 sec), the VL increase amount ΔVL = ∫A during the image formation completion time is set to The calculation is made based on the VL rising speed A (FIG. 4) at the light quantity (1 W / m ² ) of the light neutralization device (17) under the predetermined image forming conditions and the integration time at the end, and the predetermined image formation is performed. The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease speed B (FIG. 5) at a light irradiation mode light amount (30 W / m ² ) that is larger than the light amount of the light neutralization device under the image conditions. Then, the photosensitive member (12) is driven and the photosensitive member (12) is not charged, and the amount of light of the light irradiation device (8) is set to the light irradiation mode amount of light (30 W / m ² ). Then, when the time T elapses, the static elimination is stopped, and the integration time of the image formation is initialized.

  According to this, the light irradiation device (8) is provided in addition to the light neutralization device (17), and the light irradiation mode is executed at a predetermined timing by determining the light amount and time according to the predicted VL increase amount. Therefore, VL can be reduced even if the amount of light of the light neutralizing device (17) is not variable, and more energy can be saved than when light irradiation is always performed with a strong amount of light, and the photoconductor (12). The image quality is not deteriorated due to the increase in VL due to long-term use. .

(4) Except for the photoconductor (12), the photostatic device (17) having a variable irradiation light quantity, and the photostatic device (17), the photoconductor (12) is irradiated with light in the same manner as the photostatic device (17). In an electrophotographic image forming apparatus including at least one light irradiation device (8),
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value (450 sec), the VL increase amount ΔVL = ∫A during the image formation completion time is set to The calculation is made based on the VL rising speed A (FIG. 4) at the light quantity (1 W / m ² ) of the light neutralization device (17) under the predetermined image forming conditions and the integration time at the end, and the predetermined image formation is performed. the optical discharging device on the image condition (17) amount of (1W / m ²⁾ greater than the light amount of the light irradiation device and light intensity (30 W / m ²⁾ of said optical charge removing device (17) (30 W / m ²⁾ The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease rate B (FIG. 11) at the light irradiation mode light amount (60 W / m ² ) that is the sum of the above, and the photoconductor (12). The photoconductor (12) is not charged and the photostatic discharge device (17) and the light irradiation device (8) are used to discharge the photoconductor with the light irradiation mode light amount (60 W / m ² ), and the time T is When the time has elapsed, the static elimination is stopped and An electrophotographic image forming apparatus characterized by initializing an accumulated time.

  According to this, since the light irradiation in the light irradiation mode is performed by both the light neutralization device (17) and the light irradiation device (8), each of the light neutralization device (17) and the light irradiation device (8) The amount of light can be reduced or the irradiation time T can be shortened, and the image quality is not deteriorated due to the increase in VL due to the long-term use of the photoreceptor (12).

(5) The photoconductor (12), the surface potential detector (9) for detecting the surface potential of the photoconductor (12), the surface potential storage means (69) for storing the detected surface potential, and the amount of irradiation light is variable. In the electrophotographic image forming apparatus comprising the photostatic discharge device (17) of
The surface potential storage means (69) detects the VL and detects the detected value VLs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated value of the number of image formation exceeds the set value (1000). The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial time of the photosensitive member stored in the image is calculated, and from the light amount (1 W / m ² ) of the photostatic device (17) under the predetermined image forming conditions. The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease rate B (FIG. 5) at a large light irradiation mode light amount (30 W / m ² ), and the photoconductor 12 is driven. The photoconductor (12) is not charged, the photostatic device (17) neutralizes the photoconductor (12) with the light irradiation mode light amount (30 W / m ² ), and when the time T has elapsed, the static elimination is stopped. An electrophotographic image forming apparatus, wherein the integrated number of sheets is initialized.

  According to this, the image forming apparatus detects the VL increase amount at a predetermined timing, and determines the light amount and the irradiation time when executing the light irradiation mode based on the detected VL increase amount. The VL can be efficiently reduced in time, and image quality deterioration due to a decrease in sensitivity due to long-term use of the photoreceptor does not occur.

(6) a photoreceptor (12), a surface potential detector (9) for detecting the surface potential of the photoreceptor (12), a surface potential storage means (69) for storing the detected surface potential, and a photostatic device ( In addition to 17), an electrophotographic image forming apparatus provided with at least one light irradiating device (8) for irradiating the photoreceptor (12) with light in the same manner as the photostatic device (17).
The surface potential storage means (69) detects the VL and detects the detected value VLs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated value of the number of image formation exceeds the set value (1000). The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial time of the photosensitive member stored in the image is calculated, and from the light amount (1 W / m ² ) of the photostatic device (17) under the predetermined image forming conditions. The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease rate B (FIG. 5) at a large light irradiation mode light amount (30 W / m ² ), and the photoconductor 12 is driven. The photosensitive member (12) is not charged, and the light irradiation device (8) discharges the photosensitive member (12) with the light irradiation mode light amount (30 W / m ² ). An electrophotographic image forming apparatus, wherein the integrated number of sheets is initialized.

  According to this, in addition to the light neutralization device (17), the light irradiation device (8) for irradiating the photosensitive member (12) with light is provided in the same manner as the light neutralization device (17), and the VL increase amount is detected at a predetermined timing. Since the light irradiation mode execution time is determined based on the detected VL increase amount and the light irradiation mode is executed, an appropriate light amount can be obtained even if the light removal device (17) light amount is not variable. , The VL can be efficiently reduced by the irradiation time, and the deterioration of the image quality due to the sensitivity reduction due to the long-term use of the photoconductor (12) can be prevented.

(7) Photoconductor (12), surface potential detector (9) for detecting the surface potential of the photoconductor (12), surface potential storage means (69) for storing the detected surface potential, and the amount of irradiation light is variable In addition to the photostatic discharger (17), the photostatic discharger (17) is an electrophotographic type equipped with at least one light irradiation device (8) for irradiating the photosensitive member (12) in the same manner as the photostatic discharger (17). In the image forming apparatus,
The surface potential storage means (69) detects the VL and detects the detected value VLs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated value of the number of image formation exceeds the set value (1000). The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial time of the photosensitive member stored in the image is calculated, and from the light amount (1 W / m ² ) of the photostatic device (17) under the predetermined image forming conditions. Large VL at the light irradiation mode light amount (60 W / m ² ), which is the sum of the light amount (30 W / m ² ) of the light neutralization device (17) and the light amount (30 W / m ² ) of the light irradiation device (8) The light irradiation mode execution time T = ΔVL / B is calculated using the decrease speed absolute value B (FIG. 11), the photoconductor (12) is driven, and the photoconductor (12) is not charged. (17) and the light irradiation device (8) performs a photoreceptor static eliminating the irradiation mode quantity (60 W / m ^2), said stops該除conductive when the time T has elapsed, initializing the number accumulated value, Electrophotographic image forming apparatus according to claim and.

  According to this, since the light irradiation in the light irradiation mode is performed by both the light neutralization device (17) and the light irradiation device (8), each of the light neutralization device (17) and the light irradiation device (8) The amount of light can be reduced, or the irradiation time T can be shortened, and the deterioration of the image quality due to the decrease in sensitivity due to long-term use of the photoreceptor (12) can be prevented.

(8) The photoconductor (12), the surface potential detector (9) for detecting the surface potential of the photoconductor (12), the surface potential storage means (69) for storing the detected surface potential, and the amount of irradiation light is variable. In the electrophotographic image forming apparatus comprising the photostatic discharge device (17) of
The surface potential storage means (69) detects the VR and detects the detected value VRs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated number of images exceeds the set value (1000). The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial time of the photosensitive member stored in the image is calculated, and the light amount (1 W / m ² ) of the light neutralization device (17) under the predetermined image forming conditions is calculated. Using the VR decrease speed absolute value C at a large light irradiation mode light amount (30 W / m ² ), the light irradiation mode execution time T = ΔVR / C is calculated, and the photoconductor (12) is driven to drive the photoconductor (12 ) Is not charged, the photostatic device (17) neutralizes the photoconductor (12) with the light irradiation mode light amount (30 W / m ² ), and when the time T has elapsed, the static neutralization is stopped and the number of sheets is integrated. An electrophotographic image forming apparatus characterized by initializing a value.
Claim 8
The increase in VL is caused by a decrease in sensitivity due to an increase in the number of trapped charge carriers due to repeated use of the photoreceptor and a decrease in electric field strength between the photoreceptor surface and the charge generation position. The potential of the minute is approximately equal to the increase in VR. In order to detect VL, it is necessary to charge the surface of the photosensitive member and write a VL pattern. However, in order to detect VR, it is only necessary to remove the charge from the photosensitive member. Therefore, VR is detected instead of VL. Therefore, it is possible to detect a decrease in sensitivity of the photoconductor more easily and immediately.

  According to the eighth embodiment, since the VR detection is performed instead of the VL detection in the fifth embodiment, there is no need to perform the operation of charging the photosensitive member (12) and writing the VL pattern, and the downtime is shortened. In the same manner as in the fifth embodiment, it is possible to prevent deterioration in image quality due to a decrease in sensitivity due to long-term use of the photoreceptor.

(9) Photoconductor (12), surface potential detector (9) for detecting the surface potential of the photoconductor (12), surface potential storage means (69) for storing the detected surface potential, and a photostatic device ( In addition to 17), an electrophotographic image forming apparatus provided with at least one light irradiating device (8) for irradiating the photoreceptor (12) with light in the same manner as the photostatic device (17).
The surface potential storage means (69) detects the VR and detects the detected value VRs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated number of images exceeds the set value (1000). The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial time of the photosensitive member stored in the image is calculated, and the light amount (1 W / m ² ) of the light neutralization device (17) under the predetermined image forming conditions is calculated. Using the VR decrease speed absolute value C at a large light irradiation mode light amount (30 W / m ² ), the light irradiation mode execution time T = ΔVR / C is calculated, and the photoconductor (12) is driven to drive the photoconductor (12 ) Is not charged, and the light irradiation device (8) is used to discharge the photosensitive member with the light irradiation mode light amount (30 W / m ² ), and when the time T has elapsed, the discharge is stopped and the integrated number of sheets is initialized. An electrophotographic image forming apparatus characterized by comprising:

  According to this, since the VR is detected instead of the VL of the sixth embodiment, there is no need for the operation of charging the photosensitive member (12) and writing the VL pattern, and the downtime can be shortened. In the same manner as in the sixth embodiment, it is possible to prevent the deterioration of the image quality due to the sensitivity reduction due to the long-term use of the photoreceptor (12).

(10) The photoconductor (12), the surface potential detector (9) for detecting the surface potential of the photoconductor (12), the surface potential storage means (69) for storing the detected surface potential, and the amount of irradiation light is variable. In addition to the photostatic discharger (17), the photostatic discharger (17) is an electrophotographic type equipped with at least one light irradiation device (8) for irradiating the photosensitive member (12) in the same manner as the photostatic discharger (17). In the image forming apparatus,
The surface potential storage means (69) detects the VR and detects the detected value VRs at the end of the image formation when the image formation is performed under predetermined image formation conditions and the integrated number of images exceeds the set value (1000). The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial time of the photosensitive member stored in the image is calculated, and the light amount (1 W / m ² ) of the light neutralization device (17) under the predetermined image forming conditions is calculated. A large VR in the light irradiation mode light amount (60 W / m ² ) which is the sum of the light amount (30 W / m ² ) of the light neutralization device (17) and the light amount (30 W / m ² ) of the light irradiation device (9). The light irradiation mode execution time T = ΔVR / C is calculated using the decrease speed absolute value C, the photoconductor (12) is driven, and the photoconductor (12) is not charged. performed photoreceptor neutralization of the light irradiation mode amount in the light irradiation device ^{(8) (60W / m 2} ), to stop the該除conductive when the time T has elapsed, initializing the number accumulated value, that said Electrophotographic image forming apparatus.

  According to this, since the VR is detected instead of the VL of the seventh embodiment, there is no need for the operation of charging the photoreceptor 12 and writing the VL pattern, and the downtime can be shortened. In the same manner as in the seventh embodiment, it is possible to prevent the image quality from being deteriorated due to the increase in VR due to the long-term use of the photoreceptor (12).

  (11) The electrophotographic image forming apparatus according to any one of (1) to (10), wherein the photoconductor (12) is an organic photoconductor containing a charge generating material.

  (12) The electrophotographic image forming apparatus according to any one of (1) to (10), wherein the photoreceptor (12) is an organic photoreceptor containing a phthalocyanine as a charge generation material.

  (13) The electrophotographic image forming apparatus according to any one of (1) to (10), wherein the photoreceptor (12) is an organic photoreceptor containing titanyl phthalocyanine as a charge generation material.

(14) The predetermined image forming condition includes any one of the above (1) to (13), including the image forming photoconductor charging potential: −800 V, and the post-image forming light removal amount: 1 W / m ² . The electrophotographic image forming apparatus described.

  (15) The electrophotographic image forming apparatus according to (14), wherein the predetermined image forming condition includes a photosensitive member moving speed: 630 mm / sec.

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows an image forming apparatus for carrying out the present invention. This image forming apparatus is a copying machine including a laser printer 10, a document scanner 30, an automatic document feeder (ADF) 41, and a paper feed bank 43. The laser printer 10 includes a drum-shaped photoconductor 12. On the surface of the photoconductor 12, there is an organic semiconductor layer that is highly sensitive to laser light and contains titanyl phthalocyanine as a charge generation material. The thickness of the charge transport layer of the photoreceptor 12 is 38 μm, the charge generation layer is a 0.3 μm layer made of Y-type titanyl phthalocyanine and polyvinyl butyral, and the wavelength of the highest sensitivity is 780 nm. The linear velocity of the photoreceptor 12 is 630 mm / sec and the diameter is 100 mm.

  Around the photosensitive member 12, a charging device 13, a developing device 14, a transfer / conveying device 15, a cleaning device 16, a light neutralizing device 17, and the like are arranged.

  The light neutralizing device 17 is composed of an LED (light emitting diode) having a light energy peak wavelength of 680 nm, and the cleaning device 16 performs cleaning on the upstream side of the charging device 13 with respect to the moving direction of the surface of the photoreceptor 12. In the static eliminator that neutralizes the surface of the photoconductor by light irradiation, the distance between the surface of the photoconductor 12 and the front end surface of the photostatic device 17 is 13 mm. The light quantity of the light neutralizing device 17 was set or changed for each of the following embodiments.

  The cleaning device 16 includes a cleaning brush and a cleaning blade, and each performs contact with the photoreceptor 12 to perform cleaning. Above the cleaning device 16 is a laser writing device 18. The laser writing device 18 includes a light source 20 that is a laser diode having a peak wavelength of light energy of 780 nm, a scanning rotary polygon mirror 21, a polygon motor 22, a scanning optical system 23 such as an fθ lens, and the like. On the left side of the cleaning device 16 in the figure, there is a fixing device 25. The fixing device 25 includes a fixing roller 26 incorporating a heater and a pressure roller 27 that presses against the fixing roller 26 from below.

  A document scanner 30 is located above the laser printer 10. The document scanner 30 includes a light source 31, a plurality of mirrors 32, an imaging lens 33, an image sensor (CCD) 34, and the like.

  FIG. 2 shows an enlargement of the developing device 14 shown in FIG. The developer is applied by the brush roller 53, and the toner in the developer moves from the developing roller 51 to the photoconductor 12.

  FIG. 3 shows a schematic configuration of a control system of the image forming mechanism shown in FIG. First, a control unit using a microcomputer including CPU 60, RAM 61, ROM 62, EEPROM 67, nonvolatile memory 69, input / output port buffer amplifiers 63, 64, and the like, which are image forming control means, is provided and is an image forming control means. The CPU 60 controls the document scanner 30 by serial communication with the microcomputer of the document scanner 30. The microcomputer of the document scanner 30 reads the document in accordance with an instruction from the CPU 60.

  In synchronization with the rotation of the photosensitive member 12, the pulse generator 65 generates one synchronization pulse per minute rotation, and the CPU 60 is based on the count value of the pulses generated by the synchronization pulse generator 65. Then, transfer sheet feeding control, exposure control, and image forming processing (particularly timing control) are performed. The CPU 60 executes an interrupt process every time one pulse arrives, counts up the number of incoming pulses, and compares the count value with the count value of the timing table (the table storing the relationship between the count value and the event). If the count value matches one count value of the table, an event (image forming element on / off) addressed to the count value is executed.

  In this copying machine, the operator sets a document on the document table of the ADF 41 when making a copy. Alternatively, the ADF 41 is opened and a document is set on the contact glass 40 of the document scanner 30, and then the ADF 41 is closed and the document is pressed. Then, a start switch (not shown) is pressed. Then, the CPU 60 instructs the document scanner 30 to read the document image. In response to this, the document scanner 30 drives the ADF 41 and transfers the document toward the contact glass 40 when the document is set on the ADF 41. Then, the original image is read by the sheet through method and sent out to the paper output tray of the ADF 41. When a document is set on the contact glass 32, the document scanner 30 immediately starts driving the carriage. Then, the first carriage and the second carriage travel, and the light emitted from the light source of the first carriage is reflected by the document surface and then travels toward the second carriage. Further, after being reflected by the mirror of the second carriage, it reaches the image sensor 34 via the imaging lens 33, and the image sensor 34 reads it as image information.

  In response to the event command of the CPU 60, the printer 10 rotates the photosensitive member 12, feeds the transfer paper from one tray 44 of the paper feed bank 43 by the paper feed roller 45, and sends it to the registration roller 48 through the transport roller. Thereafter, in accordance with the event command of the CPU 60, the photosensitive member 12 is charged by the charger 13, and the surface of the photosensitive member is irradiated with laser light modulated based on the image data read by the scanner 30, and the electrostatic latent image generated thereby is generated. The image is developed into a toner image by the developing device 14. The registration roller 48 is driven at the timing when the leading edge of the transfer paper overlaps the position corresponding to the start edge of the original of the toner image, and the transfer paper is fed to the photoreceptor 12. The transfer / conveyance device 15 transfers the toner image on the photoconductor 12 onto transfer paper and sends it to the fixing device 25. The fixing device 25 heats and presses the transfer paper to fix the toner image on the transfer paper to the transfer paper. After the fixing, the transfer paper is sent out of the machine.

Conventionally, in the configuration described above, printing is performed under predetermined image forming conditions in which the linear velocity of the photosensitive member 12 is 630 mm / sec, the photosensitive member charging potential is −800 V, and the light amount of the photostatic device 17 is 1.0 W / m ² ( However, since the light quantity of the photostatic device 17 is 1 W / m ² , the charge carrier is trapped in the charge transport layer of the photoconductor 12 and the VL rises due to repeated use of the photoconductor 12. There was a problem. The present inventor has found that VL decreases when light is continuously applied to the photoconductor having the increased VL. When light with a light amount of 20 W / m ² was irradiated by the light neutralizing device 17, the result that VL did not increase was obtained. It has been found that irradiating the photoconductor with a certain energy prevents the increase in VL and prevents the deterioration of the image quality due to the decrease in sensitivity due to long-term use of the photoconductor.

  Note that VL is a photoreceptor surface potential of a solid image portion when the photoreceptor 12 is exposed to form a solid image, and the potential is detected using the potential sensor 9. VR, which will be described later, is a photoreceptor surface residual potential after static elimination, and this potential is detected using the potential sensor 9.

Embodiment 1
In the first embodiment of the present invention, the light quantity of the light neutralizing device 17 of the copying machine described above is 10 W / m ² . The reason is as follows. When the VL increase amount per unit time, ie, the VL increase rate, was measured under the conditions of temperature: 23 ° C. and humidity: 50% under continuous image forming conditions, the VL increase rate per unit time was measured. As shown
(6.5-4.3) / (1500-1000) = 0.0044 (V / sec)
It was found that VL increased. This is the VL increase speed A.

The predetermined image forming conditions are, as described above, the linear velocity of the photosensitive member 12: 630 mm / sec, the photosensitive member charging potential: −800 V, and the light amount of the photostatic device 17: 1.0 W / m ² . In addition, the following continuous printing (continuous printing, continuous image formation) is A4 horizontal plate repeat printing, and during the continuous printing period, the charging of the photosensitive member and the exposure static elimination are performed continuously without interruption.

Next, using the photoconductor 12 having an increased VL, the photoconductor 12 is rotationally driven in an environment of temperature: 23 ° C. and humidity: 50% without charging, and the photostatic device 17 is applied to the rotating photoconductor 12. As a result of measuring the relationship between light irradiation time and VL for each light quantity of the light static elimination device when light was continuously irradiated by the above, it was found that the amount of decrease in VL was larger as the light quantity was larger, as shown in FIG. . The absolute value of the VL decrease amount per unit time, that is, the VL decrease speed, is B for each light quantity of the light static eliminating device 17. FIG. 6 is a graph showing the relationship between the light amount and the absolute value B of the VL reduction speed. From this graph, B ≧ A (1)
It turns out that the light quantity which satisfy | fills about 8.6 W / m < ² > or more. From this result, in Embodiment 1, the light quantity of the light neutralizing device 17 was set (fixed) to 10 W / m ² .

That is, in the first embodiment, the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, and printing (image formation) is performed on the condition that the photosensitive member charging potential is −800 V and the light neutralizing device 17 has a light amount of 10 W / m ² .

As a result, as shown in FIG. 7, the increase in VL can be suppressed even during long-term use of the photoconductor 12. Note that FIG. 7 is a comparative example the amount of light discharger 17 is 1.0 W / ^{m 2} 1 (the conventional example), and Comparative Example 2 the amount of light 5W / ^{m 2,} the embodiment 1, temperature: 23 ° C., Graph comparing photoreceptor rotation time and VL increase when printing is performed under the conditions of humidity: 50%, photosensitive member charging potential: -800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA It is. In the first embodiment, the increase in VL is eliminated.

Embodiment 2
In the second embodiment, the above-described copying machine performs image formation (printing) under the predetermined image forming conditions. That is, the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, and the charging and discharging of the photosensitive member 12 are continuously performed under the conditions of the photosensitive member charging potential: −800 V and the light neutralizing device 17 light amount: 1.0 W / m ^2. And do it. In addition, the amount of light of the light neutralizing device 17 is made variable, and the light irradiation mode is executed at the end of printing when the accumulated rotation time of the photosensitive member driving motor exceeds 450 seconds.

  The light irradiation mode is a static elimination mode in which only the photosensitive member 12 and the light static elimination device 17 are driven without performing charging, writing, development, transfer, and the like. During execution of the light irradiation mode, the light neutralization device 17 has a large amount of light. The photoconductor 12 is continuously irradiated with light. The accumulated rotation time is reset after execution of the light irradiation mode.

VL increase amount ΔVL = ∫A immediately before execution of the light irradiation mode (VL increase amount in the print period when the accumulated rotation time exceeds 450 seconds) is the print period of the VL increase speed A (FIG. 4). The light irradiation mode execution time T is calculated by the following equation (2). Note that B in the formula (2) is the absolute value of the VL decrease rate per unit time shown in FIG. In the second embodiment, the light amount when the light irradiation mode is executed is set to 30 W / m ² . Therefore, from FIG. 5, the VL decrease speed absolute value B in the second embodiment is 0.016.
T = ΔVL / B (2)
That is, in the second embodiment, printing (imaging) is performed under predetermined imaging conditions of the linear velocity of the photosensitive member 12: 630 mm / sec, the photosensitive member charging potential: −800 V, and the light amount of the photostatic device 17: 1.0 W / m ^2. I do. The CPU 60 executes the light irradiation mode at the end of printing when the accumulated time of such printing exceeds 450 seconds. That is, the amount of VL increase ΔVL = ∫A during the integration time at the end of printing is expressed as VL increase rate A when the light neutralizing device 17 has a light amount of 1.0 W / m ² under a predetermined image forming condition (FIG. 4). And the light irradiation mode execution using the absolute value B (FIG. 5) of the VL decrease speed at 30 W / m ² when the light irradiation mode is executed. Time T = ΔVL / B is calculated, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, which is a predetermined image forming condition. The photosensitive member 12 is not charged, and the light quantity of the photostatic device 17 is 30 W / m ^2. When the time T has elapsed, the charge removal is stopped and the print integration time is initialized (reset to 0).

  In the light irradiation mode, the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, which is a predetermined imaging condition. However, it is not necessarily the same as the linear speed of 630 mm / sec, which is a predetermined imaging condition. It can also be set at a lower speed or a higher speed than the linear speed of 630 mm / sec in the image forming conditions. The same applies to any of Embodiments 3 to 10 below.

  By adopting such a configuration, as shown in FIG. 8, an increase in VL is suppressed. In FIG. 8, printing is performed under the conditions of temperature: 23 ° C., humidity: 50%, photoconductor charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in the second embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount.

  In the light irradiation mode, the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, which is a predetermined imaging condition. However, it is not necessarily the same as the linear speed of 630 mm / sec, which is a predetermined imaging condition. It can also be set at a lower speed or a higher speed than the linear speed of 630 mm / sec in the image forming conditions. Corresponding to the light irradiation mode execution time T, the linear velocity of the photoconductor 12 can be changed to be more effective when T is large and at a low speed, and when the T is small, the increase in VL can be further effectively suppressed. These are the same in any of Embodiments 3 to 10 below.

Embodiment 3
In Embodiment 3, image formation (printing) is also performed under predetermined image formation conditions. That is, the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, and the charging and discharging of the photosensitive member 12 are continuously performed under the conditions of the photosensitive member charging potential: −800 V and the light neutralizing device 17 light amount: 1.0 W / m ^2. And do it. When the accumulated rotation time of the photosensitive member drive motor exceeds 450 seconds, the light irradiation mode is executed.

  In the third embodiment, instead of changing the light amount of the light neutralizing device 17 in the second embodiment, as shown in FIG. 9, light irradiation is performed between the developing device 14 and the transfer / conveying device 15 in the rotation direction of the photosensitive member 12. When the light irradiation mode is executed, light irradiation is performed by the light irradiation device 8 instead of the light neutralization device 17, thereby reducing the VL due to light irradiation even if the light amount of the light neutralization device 17 is not variable. Achieve. The driver for energizing the light irradiation device 8 is connected to the I / O & buffer 64 shown in FIG. 3, and is turned on / off by the CPU 60 via the I / O & buffer 64. The light irradiation device 8 is also composed of an LED having a peak wavelength of light energy of 680 nm, like the light neutralization device 17.

The light irradiation mode execution time T is calculated by the equation (2) as in the second embodiment. The amount of light and the VLB decrease speed absolute value B of the light irradiation device 8 are 30 W / m ² and 0.016, as in the second embodiment.

That is, in the third embodiment, printing (imaging) is performed under predetermined imaging conditions of the linear velocity of the photosensitive member 12: 630 mm / sec, the photosensitive member charging potential: −800 V, and the light amount of the photostatic discharger 17: 1.0 W / m ^2. I do. When the print integration time exceeds 450 seconds, the CPU 60 executes the light irradiation mode. That is, the CPU 60 sets the VL increase amount ΔVL = ∫A during the integration time at the end of printing to the VL increase rate A (when the predetermined amount of light is 17 W / m ² ). 4) and the integrated time at the end of printing, and using the light intensity of the light irradiation device 8 when the light irradiation mode is executed: VL decrease speed absolute value B (FIG. 5) at 30 W / m ² The irradiation mode execution time T = ΔVL / B is calculated, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, which is a predetermined imaging condition. The photosensitive member 12 is not charged, and the light neutralizing device 17 is not turned on. The photoconductor 12 is neutralized under the condition that the light intensity of the light irradiation device 8 is 30 W / m ^{2. When} the time T elapses, the neutralization is stopped and the print integration time is initialized (reset to 0).

  By adopting such a configuration, as shown in FIG. 10, the increase in VL can be suppressed as in the second embodiment. In FIG. 10, printing is performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in the third embodiment. 5 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount. By providing a plurality of light irradiation devices, it is possible to shorten the time required to lower the VL and shorten the downtime.

Embodiment 4
In Embodiment 4 as well, at the time of image formation (printing), the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, the photosensitive member charging potential is −800 V, and the light amount of the light neutralizing device 17 is 1.0 W / m ^2. Thus, the charging and discharging of the photoconductor 12 are continuously performed. That is, printing is performed under predetermined image forming conditions. The light irradiation mode is executed at the end of printing when the accumulated rotation time of the photosensitive member driving motor exceeds 450 seconds.

In the fourth embodiment, in addition to the third embodiment including the light irradiation device 8, the light amount of the light neutralization device 17 is variable, and the light neutralization device 17 and the light irradiation device 8 perform light irradiation when the light irradiation mode is executed. The light irradiation mode execution time is calculated by the expression (2) as in the second embodiment. The value of B is derived from the result of measuring the relationship between VL and the light irradiation time for each sum of the light amounts of the light neutralizing device 17 and the light irradiation device 8 shown in FIG. In the fourth embodiment, the light quantity of the light static elimination device 17 is 30 W / m ² , and the light quantity of the light irradiation device 8 is 30 W / m ² . Therefore, from FIG. 11, the VL decrease speed absolute value B in Embodiment 4 is 0.0345. Since the value of B is about twice as long as that in the second and third embodiments, the light irradiation mode execution time T can be about ½ that in the second and third embodiments.

That is, in the fourth embodiment, printing (imaging) is performed under predetermined imaging conditions such as the linear velocity of the photosensitive member 12: 630 mm / sec, the photosensitive member charging potential: −800 V, and the light amount of the photostatic discharger 17: 1.0 W / m ^2. I do. When the print integration time exceeds 450 seconds, the CPU 60 executes the light irradiation mode. In other words, the CPU 60 sets the VL increase amount ΔVL = ∫A during the integration time at the end of printing to the VL increase rate A at the light quantity of the light static elimination device 17 under a predetermined image forming condition: 1.0 W / m ² (FIG. 4) and the accumulated time at the end of printing, and the sum of the light amount of the light neutralization device 17 at the time of execution of the light irradiation mode: 30 W / m ² and the light amount of the light irradiation device 8: 30 W / m ² is 60 W / m. ² is used to calculate the light irradiation mode execution time T = ΔVL / B, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec as a predetermined image forming condition. The photoconductor 12 is not charged, and the photoconductor 12 is neutralized under the condition of the sum of the light amounts of the light neutralization device 17 and the light irradiation device 8: 60 W / m ^{2. When} the time T has elapsed, the neutralization is stopped, The print integration time is initialized (reset to 0).

  By adopting such a configuration, as shown in FIG. 12, the same effects as those of Embodiments 2 and 3 can be realized with a shorter downtime. In FIG. 12, printing is performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in the fourth embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount when performed.

Embodiment 5
In Embodiment 5 as well, at the time of image formation (printing), the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, the photosensitive member charging potential is -800 V, and the light amount of the light neutralizing device 17 is 1.0 W / m ^2. Thus, the charging and discharging of the photoconductor 12 are continuously performed. That is, printing is performed under predetermined image forming conditions.

  In the fifth embodiment, the light amount of the light neutralizing device 17 is variable. The CPU 60 has a function of storing the initial VL of the photoconductor in the nonvolatile memory 69, and detects and stores the initial VL of the photoconductor when the machine is installed, shipped, or when the photoconductor is replaced. To store the initial VL of the photosensitive member in the nonvolatile memory 69.

  In the “initial value setting mode”, charging and writing of a VL detection pattern are performed on the photosensitive member 12, and VL is detected and stored in the nonvolatile memory 69. The VL pattern is a rectangular solid pattern having a length of 40 mm in the circumferential direction of the photoconductor and a width of 30 mm, and is created at the center in the photoconductor longitudinal direction corresponding to the position of the potential sensor 9. This VL pattern is also created at the end of printing that exceeds 1000 prints and when the power is turned on, and detects the VL. Note that the counter that counts 1000 accumulated prints is reset after VL detection.

When the detected VL is higher than the stored initial VL (nonvolatile memory data), the light irradiation mode of time T = ΔVL / B corresponding to the difference ΔVL is executed. This ΔVL corresponds to ΔVL = ∫A in the embodiments 2 to 4. B is the absolute value of the VL decrease rate per unit time shown in FIG. The light irradiation mode here is also a mode in which only the photosensitive member 12 and the light neutralization device 17 are driven without performing charging, writing, development, transfer, and the like. Is changed to a large value, and the photoconductor 12 is continuously irradiated with light. The execution time T of this light irradiation mode is also calculated based on the equation (2). In the present embodiment, the light quantity of the light neutralizing device 17 when executing the light irradiation mode is set to 30 W / m ² . Therefore, from FIG. 5, the value of B in this embodiment is 0.016.

That is, in the fifth embodiment, the CPU 60 performs charging and writing of the VL detection pattern to the photoconductor 12 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced. Remember. This VL is represented as VLi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), Similarly to the case, charging and writing of a VL detection pattern are performed to detect VL. This VL is represented as VLs. Then, ΔVL = VLs−VLi is calculated, and when ΔVL is positive and equal to or greater than the set value, the light quantity of the light neutralizing device 17 when executing the light irradiation mode: VL decrease speed absolute value B at 30 W / m ² (FIG. 5) Is used to calculate the light irradiation mode execution time T = ΔVL / B, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec under a predetermined image forming condition. The photoconductor 12 is neutralized under the condition that the light quantity of the apparatus 17 is 30 W / m ^{2. When} the time T elapses, the neutralization is stopped, and the print number integrated value is initialized (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, the amount of VL increase can be measured rather than predicted, so even when there is a deviation between the VL increase rate A predicted in Embodiments 2 to 4 and the actual VL increase rate. Because the light irradiation mode can be executed with an appropriate irradiation time T according to the VL rising speed, the light irradiation mode is longer than necessary and the downtime becomes longer, or the light irradiation mode is short and the VL cannot be lowered. The VL can be reduced efficiently without any trouble. As an example of a case where a deviation occurs between the predicted VL increase speed and the actual VL increase speed, in the case where the photosensitive member drive motor integrated rotation time is used as the VL increase speed prediction timing in Embodiments 2 to 4, printing is performed. 22 is performed continuously or several times, even in the same accumulated rotation time, as shown in FIG. 22, the number of prints varies greatly, so the VL increase speed also varies greatly.

  In the fifth embodiment, the VL increase speed during execution of the light irradiation mode is predicted from the relationship between the photosensitive member rotation time and the VL increase speed in the case of continuous printing. In a case where printing is repeated, the number of printed sheets is reduced with respect to the rotation time of the photosensitive member driving motor, and the actual VL increase amount becomes smaller than the predicted VL increase speed. That is, although the light irradiation mode execution time T may be short, the light irradiation mode is executed unnecessarily, resulting in wasteful use of energy and a longer downtime than necessary. Further, even when the number of prints is the same, if the image area ratios of the print images are greatly different, the amount of charge passing through the photoconductor 12 is also greatly different, so that a difference occurs in the VL increase speed. Furthermore, even when the temperature and humidity conditions fluctuate, a deviation occurs between the predicted value and the actual value. However, since the VL is detected in the fifth embodiment, the increase in the VL can be suppressed with an appropriate irradiation time T as shown in FIG. FIG. 14 shows printing in the fifth embodiment under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA. It is a graph showing the relationship between the travel time and the VL increase amount in the case of.

Embodiment 6
In Embodiment 6 as well, at the time of image formation (printing), the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, the photosensitive member charging potential is −800 V, and the light amount of the light neutralizing device 17 is 1.0 W / m ^2. Thus, the charging and discharging of the photoconductor 12 are continuously performed. That is, printing is performed under predetermined image forming conditions.

In the sixth embodiment, instead of changing the light quantity of the light neutralizing device 17 in the fifth embodiment, as shown in FIG. 9, the light is removed between the developing device 14 and the transfer / conveying device 15 in the rotation direction of the photosensitive member 12. When the light irradiation mode is executed, light irradiation is performed by the light irradiation device 8 instead of the light neutralization device 17, so that the VL lowering due to light irradiation can be achieved without changing the light amount of the light neutralization device 17. Can be achieved. The light irradiation mode execution time T is calculated from the equation (2) as in the fifth embodiment. The amount of light and the value of B are 30 W / m ² and 0.016, as in the fifth embodiment.

That is, in the sixth embodiment, the CPU 60 performs charging and writing of the VL detection pattern to the photoconductor 12 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced, and VL is detected and stored in the nonvolatile memory 69. Remember. This VL is represented as VLi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), Similarly to the case, charging and writing of a VL detection pattern are performed to detect VL. This VL is represented as VLs. Then, ΔVL = VLs−VLi is calculated, and when ΔVL is positive and equal to or larger than the set value, the light amount of the light irradiation device 8 when the light irradiation mode is executed: VL decrease speed absolute value B at 30 W / m ² (FIG. 5) Is used to calculate the light irradiation mode execution time T = ΔVL / B, the photosensitive member 12 is rotated at a linear velocity of 630 mm / sec, and the photosensitive member 12 is not charged. Then, the light neutralization device 17 is turned off, but the photoconductor 12 is neutralized under the condition that the light irradiation device 8 has a light quantity of 30 W / m ^{2. When} the time T has elapsed, the neutralization is stopped, and the print number integrated value is obtained. Initialize (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, it is possible to suppress an increase in VL as in the fifth embodiment as shown in FIG. In FIG. 16, printing was performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in Embodiment 6. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount. In addition, by providing a plurality of light irradiation devices, it is possible to shorten the time required to reduce VL and to reduce downtime.

-Embodiment 7-
In Embodiment 7 as well, at the time of image formation (printing), the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, the photosensitive member charging potential is −800 V, and the light amount of the light neutralizing device 17 is 1.0 W / m ^2. Thus, the charging and discharging of the photoconductor 12 are continuously performed. That is, printing is performed under predetermined image forming conditions.

The embodiment 7 further includes a configuration in which the amount of light of the light neutralization device 17 is variable in the sixth embodiment including the light irradiation device 8 and light irradiation is performed by the light neutralization device 17 and the light irradiation device 8 when the light irradiation mode is executed. ing. The light irradiation mode execution time is calculated from the equation (2) as in the fifth embodiment. Further, the value of B is derived from the result of measuring the relationship between the light irradiation time and the VL for each sum of the light amounts of the light neutralization device 17 and the light irradiation device 8 shown in FIG. In this Embodiment 7, the light quantity of the light static elimination apparatus 17 was set to 30 W / m ² , and the light quantity of the light irradiation apparatus 8 was set to 30 W / m ² . Therefore, from FIG. 11, the value of B in the present embodiment 7 is 0.0345. Since the value of B is about twice that of the fifth and sixth embodiments, the light irradiation mode execution time is about ½ that of the fifth and sixth embodiments.

That is, in the seventh embodiment, the CPU 60 performs charging and writing of the VL detection pattern to the photoconductor 12 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced. Remember. This VL is represented as VLi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), Similarly to the case, charging and writing of a VL detection pattern are performed to detect VL. This VL is represented as VLs. Then, ΔVL = VLs−VLi is calculated, and when ΔVL is positive and equal to or larger than the set value, the light amount sum of the light neutralization device 19 and the light irradiation device 8 when the light irradiation mode is executed: the VL decrease speed absolute at 60 W / m ² Using the value B (FIG. 11), the light irradiation mode execution time T = ΔVL / B is calculated, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, which is a predetermined image forming condition. However, the photoconductor 12 is neutralized under the conditions of the light quantity of the light static elimination device 17: 30 W / m ² and the light quantity of the light irradiation device 8: 30 W / m ^{2. When} the time T elapses, the static elimination is stopped, and the print The total number of sheets is initialized (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, as shown in FIG. 17, the same effects as those of Embodiments 5 and 6 can be realized with a shorter downtime. In FIG. 17, printing was performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in this embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount.

-Embodiment 8-
In Embodiment 8, the photosensitive member 12 is rotated at a linear speed of 630 mm / sec, the photosensitive member 12 is charged on the condition that the photosensitive member charging potential is −800 V, and the light quantity of the light neutralizing device 17 is 1.0 W / m ^2. And static elimination is performed continuously. That is, printing is performed under predetermined image forming conditions.

  In the eighth embodiment, the light quantity of the light neutralizing device 17 is variable. The CPU 60 has a function of storing the initial VR of the photoconductor in a non-volatile memory, and detects and stores the initial VR of the photoconductor when the machine is installed, shipped, or when the photoconductor is replaced. To store the initial VR of the photosensitive member.

  Further, VR detection is performed at the end of printing when the accumulated number of prints exceeds 1000 and when the power is turned on. Note that the counter that counts 1000 accumulated prints is reset after VR detection. If the detected VR is higher than the initial VR stored in the non-volatile memory 69, the light irradiation mode is executed according to the difference ΔVR.

The light irradiation mode here is also a static elimination mode in which only the photosensitive member 12 and the light static elimination device 17 are driven without performing charging, writing, development, transfer, etc. During the light irradiation mode, the light quantity of the light static elimination device 17 is driven. Is changed to a large value, and the photoconductor 12 is continuously irradiated with light. The execution time T of this light irradiation mode is calculated based on the following equation (3). Note that C in the formula (3) is the VR reduction amount absolute value per unit time, that is, the VR reduction speed absolute value shown in FIG. In the eighth embodiment, the light quantity of the light neutralizing device 17 when the light irradiation mode is executed is set to 30 W / m ² . Therefore, the value of C in this embodiment is 0.016 from FIG.
T = ΔVR / C (3)
That is, in the eighth embodiment, the CPU 60 detects the VR of the photoconductor 12 and stores it in the nonvolatile memory 69 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced. This VR is represented as VRi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), As with time, VR is detected. This VR is expressed as VRs. Then, ΔVR = VRs−VRi is calculated, and when ΔVR is positive and equal to or larger than the set value, the VR discharge speed absolute value C at 30 W / m ² in the light quantity of the light static elimination device 17 when the light irradiation mode is executed (FIG. 15). Is used to calculate the light irradiation mode execution time T = ΔVR / C, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec under a predetermined image forming condition. 17 the amount of light: and discharges the photoreceptor 12 with the proviso that 30 W / m ^2, to stop the該除conductive when said time T has passed, the print number integrated value initialized (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, it is not necessary to create a VL pattern for each detection timing at the end of printing exceeding the cumulative 1000 prints and when the power is turned on as in the fifth embodiment, so that downtime can be reduced. As shown in FIG. 18, the increase in VR can be suppressed. In FIG. 18, printing is performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in the eighth embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VR increase amount.

-Embodiment 9-
In Embodiment 9 as well, at the time of image formation (printing), the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec, the photosensitive member charging potential is −800 V, and the light amount of the light neutralizing device 17 is 1.0 W / m ^2. Thus, the charging and discharging of the photoconductor 12 are continuously performed. That is, printing is performed under predetermined image forming conditions.

In the ninth embodiment, instead of changing the light quantity of the light neutralizing device 17 in the eighth embodiment, a light irradiation device is provided between the developing device 14 and the transfer / conveying device 15 in the rotation direction of the photosensitive member 12 as shown in FIG. 8, when the light irradiation mode is executed, light irradiation is performed by the light irradiation device 8 instead of the light charge removal device 17, thereby achieving a reduction in VR due to light irradiation without changing the light amount of the light discharge device 17. It is the composition to do. The light irradiation mode execution time T is calculated from the expression (3) as in the eighth embodiment. The light irradiation device 8k light quantity and the value of C are 30 W / m ² and 0.016, as in the eighth embodiment.

That is, in the ninth embodiment, the CPU 60 detects the VR of the photoconductor 12 and stores it in the nonvolatile memory 69 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced. This VR is represented as VRi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), As with time, VR is detected. This VR is expressed as VRs. Then, ΔVR = VRs−VRi is calculated, and when ΔVR is positive and equal to or larger than the set value, the VR irradiation speed absolute value C at 30 W / m ² when the light irradiation mode is executed: 30 W / m ² (FIG. 15) Is used to calculate the light irradiation mode execution time T = ΔVR / C, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec under a predetermined image forming condition. 8 the amount of light: and discharges the photoreceptor 12 with the proviso that 30 W / m ^2, to stop the該除conductive when said time T has passed, the print number integrated value initialized (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, unlike the embodiment 6, it is not necessary to create a VL pattern for each detection timing at the end of printing exceeding 1000 prints and when the power is turned on, so that downtime can be reduced, And as shown in FIG. 19, the rise of VR can be suppressed similarly to the eighth embodiment. In FIG. 19, printing was performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in this embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount. In addition, by providing a plurality of light irradiation devices, it is possible to shorten the time required to lower the VR and shorten the downtime.

-Embodiment 10-
In the tenth embodiment, the photosensitive member 12 is charged under the conditions that the photosensitive member 12 is rotated at a linear speed of 630 mm / sec, the charging potential of the photosensitive member is −800 V, and the light amount of the photostatic discharger 17 is 1.0 W / m ^2. And static elimination is performed continuously. That is, printing is performed under predetermined image forming conditions.

In the embodiment 10, the light neutralization device 17 is made variable in the light emission device 8 in the ninth embodiment, and light irradiation is performed by the light neutralization device 17 and the light irradiation device 8 when the light irradiation mode is executed. The light irradiation mode execution time T is calculated from the expression (3) as in the eighth embodiment. Further, the value of C is derived from the result of measuring the relationship between the light irradiation time and the VR for each sum of the light amounts of the light neutralization device 17 and the light irradiation device 8 shown in FIG. In the present embodiment 10, the light quantity of the light neutralization device 17 is 30 W / m ² , and the light quantity of the light irradiation device 8 is 30 W / m ² . Therefore, from FIG. 20, the value of C in the present embodiment 10 is 0.0345. Since the value of C is about twice that of the eighth and ninth embodiments, the light irradiation mode execution time is about ½ that of the eighth and ninth embodiments.

That is, in the tenth embodiment, the CPU 60 detects the VR of the photoconductor 12 and stores it in the nonvolatile memory 69 at an initial time such as when the machine is installed, shipped, or when the photoconductor is replaced. This VR is represented as VRi. Then, the print number integrated value is initialized (reset to 0). Thereafter, the CPU 60 counts up the print number integrated value every time printing (image formation), and at the end of printing when the integrated value exceeds 1000 (immediately after the end) and when the power is turned on (immediately after the input), As with time, VR is detected. This VR is expressed as VRs. Then, ΔVR = VRs−VRi is calculated, and when ΔVR is positive and equal to or larger than the set value, the sum of the light amounts of the light static elimination device 17 and the light irradiation device 8 at the time of executing the light irradiation mode: absolute VR reduction speed at 60 W / m ² Using the value C (FIG. 20), the light irradiation mode execution time T = ΔVR / C is calculated, and the photosensitive member 12 is rotationally driven at a linear speed of 630 mm / sec as a predetermined image forming condition. Without removing the charge on the photosensitive member 12 under the condition that the light quantity of the light static elimination device 17 is 30 W / m ² and the light quantity of the light irradiation device 8 is 30 W / m ² , the static elimination is stopped when the time T elapses, and the print The total number of sheets is initialized (reset to 0). Thereafter, the print number integrated value is counted up every time printing (image formation), and the above-mentioned light irradiation mode is set at the end of printing (immediately after the completion) when the integrated value exceeds 1000 and when the power is turned on (immediately after being turned on). Run.

  By adopting such a configuration, as shown in FIG. 21, the same effects as those of Embodiments 8 and 9 can be realized with a shorter downtime. In FIG. 21, printing was performed under the conditions of temperature: 23 ° C., humidity: 50%, photosensitive member charging potential: −800 V, writing light quantity: 110 μW, writing pattern: black solid, transfer current: 130 μA in this embodiment. 6 is a graph showing the relationship between the photosensitive member rotation time and the VL increase amount.

1 is a longitudinal sectional view of a copier that is a first embodiment of the present invention. FIG. 2 is an enlarged vertical sectional view of the developing device shown in FIG. 1. FIG. 2 is a block diagram showing an outline of a mechanism control system of the copying machine shown in FIG. 1. 2 is a graph showing the amount of increase in potential after static elimination with respect to the repetition duration of image formation under predetermined image formation conditions of the photoconductor 12 shown in FIG. 2 is a graph showing the amount of decrease in VL with respect to the charge removal light irradiation time of the photoreceptor 12 shown in FIG. 2 is a graph showing an absolute value B of a VL decrease speed with respect to a charge removal amount of the photoreceptor 12 shown in FIG. 3 is a graph showing the amount of VL increase with respect to the repetition duration of image formation of the photoconductor 12 shown in FIG. 6 is a graph showing the amount of increase in VL with respect to the repetition duration of image formation in Embodiment 2 in which the light irradiation mode is executed at a predetermined timing of the photoconductor 12 shown in FIG. 1. FIG. 6 is an enlarged cross-sectional view of a developing device 14 portion of a copying machine according to a second embodiment in which a light irradiation device 8 is further added to the copying machine shown in FIG. 1. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 3 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine as the second embodiment. It is a graph which shows the amount of VL fall with respect to the static elimination light irradiation time of the photoconductor 12 of the copying machine which is 2nd Example. 12 is a graph showing the amount of increase in VL with respect to the repetition duration of image formation in Embodiment 4 in which the photoconductor 12 of the copying machine according to the second embodiment executes the light irradiation mode at a predetermined timing. FIG. 10 is a cross-sectional view showing the developing device 14 shown in FIG. 9 more simply. It is a graph which shows the VL raise amount with respect to the repetition continuation time of image formation in Embodiment 5 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine of the first embodiment. 2 is a graph showing a VR reduction amount C with respect to the static elimination light irradiation time of the photoreceptor 12 shown in FIG. 1. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 6 which performs light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine which is 2nd Example. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 7 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine as the second embodiment. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 8 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine of the first embodiment. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 9 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine as the second embodiment. It is a graph which shows VR fall amount C with respect to the static elimination light irradiation time of the photoconductor 12 of the copying machine which is 2nd Example. It is a graph which shows the amount of VL raise with respect to the repetition continuation time of image formation in Embodiment 10 which performs the light irradiation mode at the predetermined timing of the photoconductor 12 of the copying machine as the second embodiment. 3 is a graph showing a relationship between a rotation time of a motor for driving the photosensitive member 12 shown in FIG. 1 and a print mode and the number of prints.

Explanation of symbols

8: Light irradiation device 9: Potential sensor 10: Printer 12: Photoconductor 13: Charging device 14: Development device 15: Transfer / conveyance device 16: Cleaning device 17: Photostatic device 18: Laser writing device 20: Light source 21: Scanning Rotating polygon mirror 22: polygon motor 23: scanning optical system 25: fixing device 26: fixing roller 27: pressure roller 30: document scanner 31: light source 32: mirror 33: imaging lens 34: image sensor 51: developing roller 53: Brush roller

Claims (15)

In an electrophotographic image forming apparatus provided with a photoconductor and a photostatic device that neutralizes residual charge on the surface of the photoconductor by light irradiation,
When the repetition of image formation continues, the residual potential rises in the photosensitive member. The photosensitive member is driven under predetermined image forming conditions consisting of the photosensitive member speed, the photosensitive member charging potential for image formation, and the amount of charge removed after image formation. When charging and neutralizing with the photostatic device, the photosensitive member is driven at the photoconductor speed without charging the VL or VR rising speed absolute value A, and light is emitted from the photostatic device. dropping speed absolute value B or C of the VL or VR when irradiated in the body, a constant amount of light is not increased between VL repeated equal to or greater-than imaging is continuous, the photoreceptor from the optical charge removing device Electrophotographic image forming apparatus characterized by irradiating:
VL: Photoconductor surface potential of a solid image portion when the photoconductor is exposed to form a solid image VR: Photoconductor surface residual potential after static elimination. In an electrophotographic image forming apparatus provided with a photoconductor and a photostatic device with a variable amount of irradiation light that neutralizes residual charge on the surface of the photoconductor by light irradiation,
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value, the VL increase amount ΔVL = ∫A during the image formation completion time is set to a predetermined value. A light irradiation mode light amount that is calculated based on the VL increase speed A with the light amount of the light neutralizing device under the image forming condition and the integrated time at the end, and is larger than the light amount of the light static eliminating device with the predetermined image forming condition The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease speed at, and the photoconductor is driven and the photoconductor is not charged. An electrophotographic image forming apparatus, wherein the photosensitive member is discharged as a light amount, and when the time T elapses, the discharging is stopped and the integrated time for image formation is initialized. In the electrophotographic image forming apparatus provided with at least one light irradiation device for irradiating light to the photoconductor in the same manner as the photostatic discharge device other than the photostatic discharge device,
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value, the VL increase amount ΔVL = ∫A during the image formation completion time is set to a predetermined value. A light irradiation mode light amount that is calculated based on the VL increase speed A with the light amount of the light neutralizing device under the image forming condition and the integrated time at the end, and is larger than the light amount of the light static eliminating device with the predetermined image forming condition The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease speed at, and the photoconductor is driven and the photoconductor is not charged, and the light amount of the light irradiation device is set to the light irradiation mode. An electrophotographic image forming apparatus, wherein the photosensitive member is discharged as a light amount, and when the time T elapses, the discharging is stopped and the integrated time for image formation is initialized. In an electrophotographic image forming apparatus provided with at least one light irradiating device that irradiates light to the photosensitive member in the same manner as the light static eliminator, in addition to the photo static eliminator and the photo static eliminator with a variable amount of irradiation light
When image formation is performed under predetermined image formation conditions, and when the image formation integration time exceeds the set value, the VL increase amount ΔVL = ∫A during the image formation completion time is set to a predetermined value. Calculated based on the VL rising speed A with the light quantity of the light static eliminator under the image forming condition and the integrated time at the end, and larger than the light quantity of the light static eliminator with the predetermined image forming condition The light irradiation mode execution time T = ΔVL / B is calculated using the absolute value B of the VL decrease speed at the light irradiation mode light amount that is the sum of the light amount of the device and the light amount of the light irradiation device, and the photosensitive member is driven. The photoconductor is not charged, and the photostatic discharge device and the light irradiation device are used to discharge the photoconductor in the light irradiation mode light amount. When the time T has elapsed, the charge removal is stopped, and the image forming integration time is initialized. An electrophotographic image forming apparatus characterized by that. In an electrophotographic image forming apparatus comprising: a photoconductor; a surface potential detection device that detects the surface potential of the photoconductor; a surface potential storage unit that stores the detected surface potential;
Image formation is performed under predetermined image formation conditions, and at the end of the image formation when the integrated number of images exceeds the set value, VL is detected and the detected value VLs is stored in the surface potential storage means. The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial stage of the body is calculated, and the VL decrease speed absolute value B is used for the light irradiation mode light amount larger than the light amount of the light static elimination device under the predetermined imaging conditions. Then, the light irradiation mode execution time T = ΔVL / B is calculated, the photosensitive member is driven and the photosensitive member is not charged, and the photosensitive member is discharged with the light irradiation mode light amount by the light discharging device. An electrophotographic image forming apparatus characterized in that, after the elapse of time, the static elimination is stopped and the integrated number of sheets is initialized. Photoconductor, surface potential detector for detecting the surface potential of the photoconductor, surface potential storage means for storing the detected surface potential, and light for irradiating the photoconductor with light in the same manner as the photostatic device other than the photostatic device In an electrophotographic image forming apparatus including at least one irradiation device,
Image formation is performed under predetermined image formation conditions, and at the end of the image formation when the integrated number of images exceeds the set value, VL is detected and the detected value VLs is stored in the surface potential storage means. The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial stage of the body is calculated, and the VL decrease speed absolute value B is used for the light irradiation mode light amount larger than the light amount of the light static elimination device under the predetermined imaging conditions. The light irradiation mode execution time T = ΔVL / B is calculated, the photosensitive member is driven and the photosensitive member is not charged, and the photosensitive member is neutralized with the light irradiation mode light amount by the light irradiation device. An electrophotographic image forming apparatus characterized in that, after the elapse of time, the static elimination is stopped and the integrated number of sheets is initialized. A photoconductor, a surface potential detection device for detecting the surface potential of the photoconductor, a surface potential storage means for storing the detected surface potential, a photostatic device with a variable amount of irradiation light, and a photostatic device other than the photostatic device, Similarly, in an electrophotographic image forming apparatus provided with at least one light irradiation device for irradiating light to a photoconductor,
Image formation is performed under predetermined image formation conditions, and at the end of the image formation when the integrated number of images exceeds the set value, VL is detected and the detected value VLs is stored in the surface potential storage means. The amount of increase ΔVL = VLs−VLi with respect to the VL detection value VLi at the initial stage of the body is calculated, and the light quantity of the light static eliminator and the light quantity of the light irradiator are larger than the light quantity of the light static eliminator under the predetermined imaging conditions. The light irradiation mode execution time T = ΔVL / B is calculated by using the absolute value B of the VL decrease rate at the light irradiation mode light amount which is the sum of the above, and the photoconductor is driven without charging the photoconductor. An electrophotographic image forming apparatus characterized in that static elimination of the light amount in the light irradiation mode is performed by an apparatus and a light irradiating apparatus, and when the time T elapses, the neutralization is stopped and the integrated number of sheets is initialized. . In an electrophotographic image forming apparatus comprising: a photoconductor; a surface potential detection device that detects the surface potential of the photoconductor; a surface potential storage unit that stores the detected surface potential;
When image formation is performed under predetermined image formation conditions, and VR is completed when the integrated number of images exceeds the set value, VR is detected and the detected value VRs is stored in the surface potential storage means. The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial stage of the body is calculated, and the VR decrease speed absolute value C at the light irradiation mode light amount larger than the light amount of the light neutralizing device under the predetermined image forming condition is used. Then, the light irradiation mode execution time T = ΔVR / C is calculated, the photosensitive member is driven and the photosensitive member is not charged, and the photosensitive member is discharged with the light irradiation mode light amount by the light discharging device. An electrophotographic image forming apparatus characterized in that, after the elapse of time, the static elimination is stopped and the integrated number of sheets is initialized. Photoconductor, surface potential detector for detecting the surface potential of the photoconductor, surface potential storage means for storing the detected surface potential, and light for irradiating the photoconductor with light in the same manner as the photostatic device other than the photostatic device In an electrophotographic image forming apparatus including at least one irradiation device,
When image formation is performed under predetermined image formation conditions, and VR is completed when the integrated number of images exceeds the set value, VR is detected and the detected value VRs is stored in the surface potential storage means. The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial stage of the body is calculated, and the VR decrease speed absolute value C at the light irradiation mode light amount larger than the light amount of the light neutralizing device under the predetermined image forming condition is used. The light irradiation mode execution time T = ΔVR / C is calculated, the photosensitive member is driven and the photosensitive member is not charged, and the photosensitive member is discharged with the light irradiation mode light amount by the light irradiation device. An electrophotographic image forming apparatus characterized in that, after the elapse of time, the static elimination is stopped and the integrated number of sheets is initialized. A photoconductor, a surface potential detection device for detecting the surface potential of the photoconductor, a surface potential storage means for storing the detected surface potential, a photostatic device with a variable amount of irradiation light, and a photostatic device other than the photostatic device, Similarly, in an electrophotographic image forming apparatus provided with at least one light irradiation device for irradiating light to a photoconductor,
When image formation is performed under predetermined image formation conditions, and VR is completed when the integrated number of images exceeds the set value, VR is detected and the detected value VRs is stored in the surface potential storage means. The amount of increase ΔVR = VRs−VRi with respect to the VR detection value VRi at the initial stage of the body is calculated, and the light quantity of the light static eliminator and the light quantity of the light irradiator are larger than the light quantity of the light static eliminator under the predetermined imaging conditions. The light irradiation mode execution time T = ΔVR / C is calculated using the absolute value C of the VR decrease rate at the light irradiation mode light amount that is the sum of the above, and the photoconductor is driven without being charged. An electrophotographic image forming apparatus characterized in that static elimination of the light amount in the light irradiation mode is performed by an apparatus and a light irradiating apparatus, and when the time T elapses, the neutralization is stopped and the integrated number of sheets is initialized. .   The electrophotographic image forming apparatus according to claim 1, wherein the photoconductor is an organic photoconductor containing a charge generating material.   The electrophotographic image forming apparatus according to claim 1, wherein the photoconductor is an organic photoconductor containing phthalocyanines as a charge generating material.   The electrophotographic image forming apparatus according to claim 1, wherein the photoreceptor is an organic photoreceptor containing titanyl phthalocyanine as a charge generation material. 14. The electrophotographic image according to claim 1, wherein the predetermined image forming conditions include: an image forming photoconductor charging potential: −800 V, and a post-image forming charge removal amount: 1 W / m ² . Forming equipment.   The electrophotographic image forming apparatus according to claim 14, wherein the predetermined image forming condition includes a photosensitive member moving speed: 630 mm / sec.

Images