JP4383213B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a charging unit for charging a photoconductor, an exposure unit for exposing the surface of the photoconductor to form an electrostatic latent image, and a development for supplying toner to the electrostatic latent image to form a toner image. Means, a transfer means for transferring the transfer material, a transfer means for transferring the toner image to the transfer material, a toner removal means for removing toner remaining on the photoconductor after transfer, and a charge removing light to the photoconductor The present invention relates to an image forming apparatus including a charge removing unit that removes charges charged by irradiating.

  As a photoreceptor on which an electrostatic latent image is formed in an electrophotographic image forming apparatus, an organic photoreceptor (OPC photoreceptor), an amorphous silicon photoreceptor, a selenium photoreceptor, and the like have been put into practical use. Among them, the amorphous silicon photoconductor has a characteristic that it has a high surface hardness, a high sensitivity to long-wavelength light such as a semiconductor laser, and almost no deterioration due to repeated use. Thus, since it is excellent in stability and durability, it is widely used as an electrophotographic photoreceptor.

  In recent years, image forming apparatuses such as copying machines and printers have been reduced in size, and along with this, the diameter of the photosensitive drum has also been reduced. Also, the speeding up is progressing, and the process time of image formation is shortened by the synergistic effect of speeding up the image processing time and reducing the diameter of the photosensitive drum. Therefore, there is a problem that the electrostatic latent image formed in the immediately preceding image forming process affects the next process and a so-called ghost image appears.

  The image forming process by the electrophotographic method is roughly as follows. A charging process for charging the photosensitive drum, an exposure process for exposing the surface of the photosensitive drum to form an electrostatic latent image, a developing process for supplying toner to the electrostatic latent image to form a toner image, and a toner A transfer process for transferring an image to a transfer material, a toner removal process for removing toner remaining on the photosensitive drum after transfer, and a photostatic discharge process for discharging the charged charge by irradiating the photosensitive drum with a discharge light. The toner image transferred to a transfer material such as paper in the transfer process is sequentially and repeatedly fixed on the transfer material semi-permanently in the fixing process to form an image.

  Amorphous silicon photoconductors have many dangling bonds called tangling bonds because of their non-crystalline composition. The unbonded hands are localized on the photosensitive drum, and a part of the optical carrier generated in the exposure process is captured. Further, when the mobility of the photocarrier is small, it remains in the photosensitive layer as a space charge even after the static elimination process. In the next charging process, this space charge works so as to cancel the charged charge. For the canceled portion, the surface potential of the photosensitive drum charged so as to be the same potential over the entire circumference is lowered.

  That is, of the exposed part of the surface of the photosensitive drum (hereinafter referred to as “exposed part”) and the unexposed part (hereinafter referred to as “unexposed part”) of the exposed part, The surface potential is lowered. Due to the lowered surface potential, the electrostatic latent image in the previous process emerges as if it was exposed in the next process, and appears as a so-called ghost image.

  Since this is caused by the supplement of the optical carrier in the exposure process, it is called an optical memory or an exposure memory. Hereinafter, in the present specification, such a memory effect is generically referred to as an “optical memory”, and a memory effect resulting from the difference between an exposed portion and an unexposed portion as described above is particularly referred to as an “exposure memory”. .

  Japanese Patent Laid-Open No. 2003-295563 proposes a method for suppressing the generation of a ghost image in an electrophotographic image forming apparatus using an amorphous silicon photosensitive drum.

  As a method for reducing the exposure memory, a method is known in which the time from the end of the photostatic process to the next charging process is defined to some extent. However, as the speed and size of the image forming apparatus increase, the grid voltage is applied from the charging device constituting the charging unit from the position where the charge is removed by receiving the charge removal light on the photoconductor (charge removal light incident position). The physical distance to the charged position (hereinafter referred to as “charging voltage application position”) is also shortened. Along with this, the time from the end of the photostatic process to the next charging process is also shortened, and it becomes difficult to sufficiently secure the above-mentioned specified time.

  Therefore, a toner removal process is performed between the photostatic process and the charging process so that the specified time can be sufficiently secured even if the size and speed are increased, and the time from the completion of the photostatic process to the charging process can be increased. Configure as follows. However, in this case, as shown in FIG. 4, the neutralizing light (irradiation light) E3, E4, and E5 irradiated is blocked by the untransferred toner (residual toner) D1 remaining on the photosensitive member 1 after the transfer. As a result, the amount of light reaching the surface of the photoreceptor 1 is reduced. That is, as shown in FIG. 4, the photosensitive member 1 is neutralized by the neutralizing light (incident light) E3, S4, E5 reduced with respect to the irradiation light.

  In such a state, a large amount of space charge having the same polarity as the charged charge remains in the portion (static elimination portion) where the photostatic elimination process has been completed on the photoreceptor 1. The portion where the untransferred toner D1 exists is an exposed portion in the previous process. If the exposure memory described above is ignored, the surface potential on the photoreceptor 1 is higher in the exposed portion of the previous process in the next charging process than in the unexposed portion of the previous process. This is a memory effect having a polarity opposite to that of the aforementioned exposure memory, and is hereinafter referred to as an untransferred memory. The untransferred memory causes a ghost image having a density opposite to that of the exposure memory to appear in the formed image.

  The invention described in Patent Document 1 uses two optical memories (exposure memory and non-transfer memory) having such reverse polarities to suppress the appearance of a ghost image. A toner removal process is performed after the photostatic process, and an electrophotographic process for charging the photoreceptor 1 in the next charging process is used, and a time from the photostatic process to the next charging process is defined. In this way, the exposure memory and the untransferred memory are offset to prevent a ghost image due to the influence of the optical memory from appearing.

JP 2003-295563 A (paragraph numbers 0011 to 0012, Table 1)

  However, miniaturization has progressed, and in particular, in a copying machine or printer using a small-diameter photosensitive drum, another problem arises if an optical static elimination process is provided immediately after the transfer process. FIG. 5 is an enlarged view showing a transfer position sandwiched between the transfer roller 5 and the photosensitive member (photosensitive drum) 1. An arrow in the photoconductor 1 indicates the rotation direction of the photoconductor (photosensitive drum) 1. FIG. 5 shows a configuration in the case where the light neutralization process is executed by the static elimination lamp 7 after the transfer process to the paper 8 and before the toner removal means 6 removes the toner.

  As shown in FIG. 5, the neutralizing light E2 irradiated by the neutralizing lamp 7 is also irradiated to the paper 8 as the transfer material, and the reflected light R2 is received by the photosensitive member 1. Therefore, the light shielding film 7a is provided to prevent the charge removal light E2 from being applied to the transfer material (paper 8). However, there still exists an optical path through which the reflected light R0 of the neutralizing light E1 correctly irradiated on the surface of the photoconductor 1 is reflected again by the transfer material (paper 8) and the reflected light R1 enters the photoconductor 1. There is a physical limit to extending the light shielding film 7a to the photoreceptor 1, and this problem cannot be completely prevented.

  As described above, the amount of the neutralizing light received by the photoconductor 1 varies depending on the presence or absence of the transfer material (paper 8) at the transfer position between the transfer roller 5 and the photoconductor 1 (photosensitive drum 1). That is, the amount of charge removal light changes due to the paper passing, and uneven charging occurs in the next charging process. Since this phenomenon is a memory effect due to reflection of static elimination light, it will be referred to as static elimination memory (reflection memory) below.

When the static elimination memory is generated, the density of the image formed on the transfer material (paper 8) changes according to the principle described below. That is, as shown in FIG. 6, the surface position of the photoconductor 1 (transfer position on the photoconductor) when the transfer material (paper 8) reaches the transfer position reaches the charging voltage application position of the next process. The surface potential of the photosensitive member 1 charged after the lapse of time T2 is from the reference value V _ref to V _down of the photosensitive member surface potential at the developing position over a period during which the transfer material exists at the transfer position, that is, the paper passing period T1. Only voltage drop.

The influence at the development position appears during the paper passing period T1 after the time T5 when the sheet 8 reaches the transfer position and the surface of the photoreceptor 1 at the transfer position rotates to the development position. . The magnitude of V _down varies depending on the light amount of the static elimination lamp 7, the installation position of the static elimination lamp 7, the characteristics of the photosensitive member 1, the color and material of the paper transport belt 9, etc. The portion of the voltage drop caused by excessive exposure to the static elimination light is equivalent to a strongly exposed state, and the density of the formed image becomes high.

  The present invention has been made in view of the above problems, and improves optical memory such as an exposure memory, an untransferred memory, and a static elimination memory, and eliminates the appearance of ghost and charging unevenness in a formed image. An object of the present invention is to provide an electrophotographic image forming apparatus for forming an image.

  According to the first characteristic configuration of the present invention, a charging unit charges the photoconductor in accordance with a change in surface potential caused by the reflected light on a portion where the photoconductor is irradiated with reflected light from a transfer material for static elimination light. Therefore, a control means for changing the charging voltage to be applied is provided.

  According to the first characteristic configuration, when the photosensitive member charges a portion where the static elimination memory is generated, the control means controls the charged surface voltage of the photosensitive member to be constant by changing the charging applied voltage. ing. As a result, it is possible to suppress the uneven charging of the photosensitive member caused by the static elimination memory, and it is possible to form a good image without causing disturbance due to the uneven charging in the formed image.

  The second characteristic configuration according to the present invention includes, in addition to the first characteristic configuration described above, a front end detection unit that detects the front end of the transfer material conveyed by the conveyance unit, and a rear end detection unit that detects the rear end. The control means controls the charging application voltage based on detection results from the leading edge detection means and the trailing edge detection means.

  According to the second feature configuration, the behavior of the transfer material that is a reflection of the charge removal light is grasped, and the charging application voltage is controlled based on the grasped information, so the timing for changing and returning the charging application voltage is accurately controlled. can do. Further, even when a plurality of transfer materials are continuously conveyed, the above-described control can be performed for each individual transfer material, so that the charging application voltage can be reliably and precisely controlled.

  The third characteristic configuration according to the present invention, in addition to the first and second characteristic configurations described above, remains on the photosensitive member by the toner removing unit after the charged charge of the photosensitive member is neutralized by the neutralizing unit. The point is to remove the toner.

  According to the third characteristic configuration, immediately after the transfer to the transfer material, the residual toner remaining on the photoconductor is not removed, but the photoconductor is first discharged, and then the residual toner is removed. As a result, it is possible to cancel the exposure memory generated due to the difference in space charge between the exposed portion and the unexposed portion of the photosensitive member and the untransferred memory generated by the charge removal light being a shadow of the remaining toner.

  The first and second characteristic configurations eliminate the static elimination memory, and the amorphous silicon photosensitive member often used for the small-diameter photosensitive drum (photosensitive member) can satisfactorily eliminate the problematic exposure memory. Therefore, various optical memories (exposure memory, untransferred memory, static elimination memory), which are major problems in the electrophotographic image forming process, especially in the electrophotographic image forming process using an amorphous silicon photoreceptor, are eliminated. Therefore, it is possible to realize an image forming apparatus that performs excellent image formation.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments when the present invention is applied to a tandem color image forming apparatus will be described below with reference to the drawings.

  FIG. 2 shows an example of a tandem color image forming apparatus 100 to which the present invention is applied. The image forming apparatus 100 includes a paper feed tray 15, a vertical conveyance path (feed conveyance path) 14, a registration roller pair 13, a registration detection sensor 12, an image forming unit 10, a paper conveyance belt 9, a fixing device 16, and a discharge conveyance path 17. And a paper discharge tray 18.

  The paper transport belt 9 is stretched over the drive roller 91 and the tension roller 92, and rotates at a speed substantially equal to the transport speed of the paper 8 as a transfer material while maintaining an appropriate tension. The paper 8 is taken out from the paper feed tray 15 one by one and is guided to the paper transport belt 9 through the vertical transport path 14. The surface of the paper transport belt 9 is charged by belt charging means (not shown) in order to electrostatically attract the paper 8.

  The image forming unit 10 is provided as image forming units 10k, 10c, 10m, and 10y having substantially the same structure from the right side of FIG. 2, corresponding to the color image formation of each color of black, cyan, magenta, and yellow. Yes. The image forming apparatus according to the present exemplary embodiment forms each color image in this order. FIG. 3 shows a schematic configuration of one image forming unit 10.

  As shown in FIG. 3, the image forming unit 10 in this embodiment includes a photoconductor 1 that is an amorphous silicon photoconductor, a scorotron type charging device 2 that constitutes a charging unit that charges the photoconductor 1, and a charged photoconductor 1. An exposure device 3 having an LED print head that constitutes an exposure means for exposing the surface of the substrate to form an electrostatic latent image, supplying toner to the exposed electrostatic latent image to form a toner image on the photoreceptor 1 The developing device 4 constituting the developing means, the transfer roller 5 constituting the transfer means for transferring the toner image developed on the photoconductor 1 to the paper 8 as a transfer material, and the toner remaining on the photoconductor 1 after the transfer. A toner removing device 6 having a rubbing roller 6a, a waste toner screw 6b, a cleaning blade 6c, and a toner receiver 6d constituting a toner removing means to be removed, and the photosensitive member 1 are irradiated with a charge removing light. Discharging lamp 7 constituting the charge removing means for removing the charged charge to the surface, a has. These units are assembled into a housing made of resin to form one unit, which is attached to the image forming apparatus 100 main body. The rotation direction of the photosensitive member 1 and the conveyance direction of the paper 8 are directions indicated by arrows in FIG.

In this example, the photosensitive member 1 is rotated at a peripheral speed of 116 mm / s using an amorphous silicon photosensitive drum having a diameter of 30 mm. The charging device 2 applies a high voltage to bring the potential of the grid 2g (grid voltage _Vgrid ) to about 450V, thereby positively charging the surface potential of the photoreceptor 1 to about 300V at the development position. This is called a charging process.

The exposure device 3 having an LED print head irradiates the charged surface of the photoreceptor 1 with LED light having a peak wavelength of 685 nm with a light amount of about 0.45 μJ / cm ² in accordance with image information. An image is formed. This is called an exposure process.

  In this embodiment, the developing device 4 develops the electrostatic latent image exposed in the exposure process using a developer in which positively charged toner and a carrier are stirred and mixed so as to have a predetermined density. A toner image is formed on the surface. In this example, the developing bias potential is about 200V. The surface potential of the photoreceptor 1 corresponding to the white part (unexposed part) of the exposed image is about 300 V at the development position. In the colored portion (exposed portion) of the exposure image, a potential difference, that is, a so-called contrast potential appears due to exposure with intensity according to the image information, and the color is developed with a developer corresponding to the contrast potential. This is called a development process.

  The toner image formed as described above is transferred onto the sheet 8 conveyed by the sheet conveying belt 9 to a transfer position that is a position sandwiched between the transfer roller 5 and the photoreceptor 1. A voltage having a polarity opposite to the surface potential of the photosensitive member 1 is applied to the transfer roller 5, whereby the toner image is transferred onto the paper 8. This is called a transfer process.

After the toner image is transferred, the photosensitive member 1 is irradiated with a neutralizing light having a light amount of about 7 μJ / cm ² by a neutralizing lamp 7 having an LED having a peak wavelength of 660 nm. By this irradiation, the photoreceptor 1 is neutralized, and the surface potential of the photoreceptor 1 is lowered uniformly. This is called a photostatic process. A shielding film 7 a that prevents the neutralizing light from irradiating the paper 8 is provided below the neutralizing lamp 7.

  Following the light neutralization process, toner remaining on the surface of the photoreceptor 1 without being transferred to the paper 8 is removed using the toner removing device 6. This is called a toner removal process.

  As described above, a series of image forming processes is constituted by the charging process, the exposure process, the developing process, the transfer process, the photostatic process, and the toner removing process, and the image forming apparatus is repeated. An image of the entire image information input to 100 is formed.

  The image forming apparatus 100 performs the image forming process in parallel with each image forming unit 10 with a predetermined time difference. In this example, the toner images formed on the photoreceptor 1 in the order of black, cyan, magenta, and yellow are transferred so as not to be shifted with respect to the paper 8 conveyed on the paper conveyance belt 9. A full color image is formed. In the present embodiment, as shown in FIG. 2, a microcomputer (hereinafter referred to as a microcomputer) as a control means is used to control the time difference at which each image forming means 10 forms a full-color image without deviation. 11 does. As the control means, a logic circuit or an integrated circuit of logic circuits may be used.

  The microcomputer 11 detects the leading edge of the paper 8 when the registration clutch provided in the registration roller pair 13 is turned on, and detects the trailing edge of the paper 8 when the registration switch provided in the registration sensor 12 is turned off. The full color image transferred to the paper 8 is not deviated by calculating from the physical arrangement distance of each image processing means 10 or the transport speed of the paper 8 transported on the paper transport belt 9. Each image processing means 10 is controlled.

  In this embodiment, the full-color image transferred onto the paper 8 is melted and fixed on the paper 8 by a fixing device 16 having a fixing roller. This is called a fixing process. When the fixing is completed, the paper 8 is discharged onto the paper discharge tray 18 via the discharge conveyance path 17. The above is the electrophotographic process in which the image forming apparatus 100 forms an image.

  In this example, following the transfer process, the charge charged on the photosensitive member 1 is discharged by the discharging lamp 7 constituting the discharging means, and then left on the photosensitive member 1 by the toner removing device 6 constituting the toner removing means. The toner is removed.

  That is, the residual toner remaining on the photoconductor 1 after the transfer to the paper 8 as a transfer material is not removed, the photoconductor 1 is first discharged, and then the residual toner is removed. As a result, the exposure memory and the untransferred memory, which are optical memories having opposite polarities, can be offset well. Both the exposure memory generated due to the space charge difference between the exposed portion and the unexposed portion of the photoconductor 1 and the untransferred memory generated by the charge removal light in the shadow of the residual toner remaining in the exposed portion are both exposed to the photoconductor 1. This occurs with respect to the parts, and their polarities are opposite to each other as already described. Therefore, the two optical memories can be offset well by appropriately setting the arrangement of the charge removal lamp 7 and the toner removal device 6 and the light quantity and wavelength of the charge removal lamp 7.

  Next, a method for improving the static elimination memory generated in the image forming apparatus 100 configured as described above will be described. Although the generation principle of the static elimination memory has already been described with reference to FIGS. 4 to 6, it will be briefly described again according to the present embodiment. In the present embodiment, a black or dark film is used as the light shielding film 7a for shielding the static elimination light E2 of the static elimination lamp 7. This is to prevent the amount of the neutralizing light irradiated to the photosensitive member 1 from changing due to the effect of the light shielding film 7a becoming soiled by the toner powder falling from the toner removing device 6 positioned above the neutralizing lamp 7. It is.

  As shown in FIG. 6, the static elimination memory is generated at a timing when the sheet 8 as a transfer material is in a transfer position between the transfer roller 5 and the photosensitive member 1 and is in contact with the photosensitive member 1. Almost synchronized. That is, the photosensitive member at the developing position is delayed by a time T5 when the surface of the photosensitive member 1 at the transfer position rotates to the developing position over a period substantially equal to the paper passing period T1 in which the sheet 8 exists at the transfer position. The surface potential of 1 drops. The change in the surface potential of the photoconductor 1 due to the static elimination memory is rectangular as shown in FIG. 6, and has a waveform shifted by time T5 from the timing when the paper 8 is present at the transfer position.

  Here, the microcomputer 11 can know the timing at which the sheet 8 exists at the transfer position of each of the image forming units 10k, 10c, 10m, and 10y. As already described, the microcomputer 11 detects the leading edge and the trailing edge of the paper 8 conveyed on the conveying belt 9 based on information sent from the registration roller pair 13 and the registration sensor 12.

  That is, as shown in FIG. 1, the paper 8 is transferred to the transfer position after a predetermined time T3 has elapsed since the leading edge of the paper 8 is detected, and the paper 8 is transferred after the predetermined time T4 has elapsed since the trailing edge has been detected. As it is unloaded from the position, the microcomputer 11 calculates. Times T3 and T4 vary depending on each of the four image forming units 10, and the microcomputer 11 calculates each numerical value.

  Similarly, the time T2 until the portion of the photosensitive member 1 where the paper 8 has reached the transfer position and generated the static elimination memory (the static elimination memory generation portion) reaches the charging position of the next process, and the development position of the next process is reached. The microcomputer 11 also calculates time T5. The time required to reach the charging position of the next process may be calculated as a time T6 with the leading edge detection timing of the paper 8 as a starting point. Note that these times T2, T5, and T6 are also different for each of the four image forming units 10, and the microcomputer 11 calculates the respective numerical values.

From these calculation results, the microcomputer 11, for example, after time T6 has elapsed from the leading edge detection of the sheet 8, the grid voltage charging unit 2 is applied to charge the photosensitive member 1 from the normal V _grid, V _ctrl only high value The charging device 2 is controlled to change to And after applying the grid voltage ( _Vgrid + _Vctrl ) changed over the paper passing period T1, it returns to the original grid voltage ( _Vgrid) . Alternatively, the original grid voltage _Vgrid may be restored after the time T7 has elapsed from the detection of the trailing edge of the paper 8. The time T7 is also a value that differs depending on each of the four image forming units 10.

When controlled by the microcomputer 11 as described above, the static elimination memory is canceled by the grid voltage control as shown in FIG. 1, and the surface potential of the photosensitive member 1 at the development position can hold a constant potential of V _ref . A portion indicated by a dotted line in the waveform of FIG. 1 is the surface potential of the photosensitive member 1 at the developing position when it is affected by the static elimination memory.

  As described above, the leading edge detecting means (registration clutch and registration roller pair 13) for detecting the leading edge of the transfer material (paper 8) conveyed by the conveying means (paper conveying belt 9) and the trailing edge detecting means for detecting the trailing edge. (Registration switch, registration sensor 12), and the control means (microcomputer 11) controls the charging application voltage (grid voltage) based on the detection results from the leading edge detection means and the trailing edge detection means. The influence of the static elimination memory at the position can be eliminated well.

Note that the voltage drop of the surface potential appearing at the development position due to the charge removal memory is about 5 to 10 V experimentally when the surface potential V _ref of the photoreceptor 1 at the development position is 300V. In addition, the control range of the grid voltage is preferably controlled according to the rate at which the surface potential V _ref changes. For example, if the surface potential V _ref drops by 10 V, the drop is about 3.3%. If the normal grid voltage ( _Vgrid ) is 450V, a voltage of 465V, which is about 3.3% higher, is applied as the grid voltage ( _Vgrid + _Vctrl ).

  That is, the surface potential of the photoconductor 1 at the development position where the developing unit supplies toner to the electrostatic latent image on the photoconductor 1 to form a toner image, and the change in which the surface potential drops or rises due to the effect of static elimination light. Depending on the ratio to the voltage, the control means controls the charging means to charge the photosensitive body 1 by raising or lowering the charging applied voltage before the photosensitive body 1 reaches the development position, and at the development position. The surface potential of the photosensitive member 1 is prevented from dropping or rising due to the influence of static elimination light.

  Although not shown in the present embodiment, some image forming apparatuses of this type have a paper discriminating unit. For example, paper discriminating means for discriminating whether a film such as an OHP sheet, high-quality paper exclusively for color printing, general plain paper, or recycled paper from the output of a reflection type optical sensor using a blue LED or the like Some have

  Reflection of the static elimination light by the transfer material (paper 8) present at the transfer position differs depending on the material of the transfer material. Therefore, the influence on the surface potential of the photosensitive member 1 at the development position given by the static elimination memory differs depending on the material of the transfer material. Therefore, for example, the surface of the photosensitive member 1 at the development position is determined by determining the type of the transfer material by the sheet determination unit or the sheet determination unit as described above and the control unit that determines the sheet type from the output of the sheet determination unit. More preferably, the control means controls the grid voltage so that the potential does not drop or rise due to the influence of the static elimination light.

  Note that in this embodiment, the sheet determination unit is the first-stage image formation unit such as the sheet feed tray 15 or the sheet feed conveyance path (vertical conveyance path) 14 so that the sheet determination is completed before the start of the image forming process. 10 (in this embodiment, the image forming unit 10k) is preferably installed.

  As described above, the present invention improves the optical memory such as an exposure memory, an untransferred memory, and a static elimination memory, eliminates the appearance of ghosts and uneven charging in the formed image, and forms an excellent image. A photographic image forming apparatus can be provided.

FIG. 4 is a waveform diagram showing the photoreceptor surface potential and the like during charging voltage control according to an embodiment of the present invention. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a schematic diagram showing a schematic configuration of image forming means constituting the image forming apparatus of FIG. Conceptual diagram explaining the principle of untransferred memory generation Conceptual diagram explaining the generation principle of static elimination memory Waveform diagram showing photoreceptor surface potential, etc. when static elimination memory is generated

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging apparatus 3 Exposure apparatus 4 Developing apparatus 5 Transfer roller 6 Toner removal apparatus 7 Static elimination lamp 8 Paper 9 Paper conveyance belt 10 Image formation means 11 Microcomputer 12 Registration sensor 13 Registration roller pair

Claims (3)

Charging means for charging the photosensitive member; exposure means for exposing the surface of the photosensitive member to form an electrostatic latent image; developing means for supplying toner to the electrostatic latent image to form a toner image; and transfer A transfer means for transferring the material, a transfer means for transferring the toner image to the transfer material, a toner removal means for removing the toner remaining on the photoconductor after the transfer, and a discharge light to the photoconductor. In an image forming apparatus provided with a static elimination means for neutralizing a charged charge,
A charging voltage applied by the charging means to charge the photoconductor in accordance with a change in surface potential caused by the reflected light on a portion of the static light reflected by the transfer material on the photoconductor. An image forming apparatus provided with a control means for changing the angle.   A leading edge detecting means for detecting the leading edge of the transfer material conveyed by the conveying means; and a trailing edge detecting means for detecting a trailing edge, based on detection results from the leading edge detecting means and the trailing edge detecting means. The image forming apparatus according to claim 1, wherein the control unit controls the charging application voltage.   3. The image forming apparatus according to claim 1, wherein the charge remaining on the photosensitive member is removed by the charge removing unit, and then the toner remaining on the photosensitive member is removed by the toner removing unit.

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