JP2010160291A - Image forming apparatus, control method, control program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus stably forming a high-quality image over a long term by suppressing production of ozone and nitrogen oxide concurrently with preventing uneven discharge of a saw tooth and stabilizing potential by electrification on a surface of a photoreceptor, and also to provide a control method therefor, a control program and a recording medium. <P>SOLUTION: The image forming apparatus includes an image carrier, a potential detection means, a needle electrode, a cleaning member and a control means. The needle electrode is cleaned by the cleaning member, and then the potential by electrification of the electrified image carrier is detected by the potential detection means. The control means compares the potential by electrification with a set value, and selectively performs any one control operation out of first control operation, second control operation, third control operation and fourth control operation on the basis of the compared result. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a cleaning mechanism for cleaning contaminants adhering to a saw tooth with a cleaning member in a charging device for uniformly charging the surface of a photoreceptor used for electrophotographic image formation, and a control method therefor, The present invention relates to a control program and a recording medium.

  An electrophotographic image forming apparatus is equipped with a charging device that uniformly charges the surface of the photoreceptor. As a charging device, for example, there is a non-contact charging device that does not contact the surface of the photoconductor, and the non-contact charging device charges the surface of the photoconductor by discharging from an electrode to which a high voltage power source is applied.

  As the non-contact charging device, for example, there is a scorotron charging device including a sawtooth electrode, a grid electrode, and a shield case. In this method of charging the surface of the photoconductor with this charging device, in order to obtain a predetermined potential throughout the life of the photoconductor, a higher charging current is applied to the saw-tooth so that the film thickness of the photosensitive layer included in the photoconductor is reduced. Accordingly, by increasing the grid bias applied to the grid electrode, the charging potential on the surface of the photoreceptor is controlled to be constant. Ozone and nitrogen oxides are generated more as the charging current value applied to the sawtooth is larger. Therefore, in the above control method in which a higher charging current is applied to the sawtooth, ozone and nitrogen oxide are generated more. The photosensitive member and the grid electrode were damaged, and the deterioration of the sawtooth electrode was accelerated.

  As a problem when using a sawtooth electrode, toner, silica, and dust floating in the image forming apparatus are likely to be adsorbed at the tip of the sawtooth where a high-voltage electric field is generated. If these are left adsorbed, proper discharge is not performed, and so-called discharge failure occurs. Due to this discharge failure, the photoreceptor is not uniformly charged, and image defects occur. In recent years, HMDS (hexamethyldisilane), which is a hydrophobizing agent added to silica, which is an external additive for toner, is heated in the fixing process to generate TMS (trimethylsilanol) volatile gas, which is sawtooth. It becomes a big problem that defective discharge becomes conspicuous by adhering to and depositing on the tip of the metal.

  However, HMDS is used for the purpose of preventing electrification deterioration of the toner in a high temperature and high humidity environment, and it cannot be easily stopped. For example, it can be handled by periodically cleaning the tip of the saw tooth with a cleaning rubber roller. is doing.

  In Patent Document 1, a current larger than the current for forming an image is supplied to the wire after the cleaning of the charging unit by the cleaning unit is completed and before the charging process for forming the image is performed. An image forming apparatus is disclosed. According to Patent Document 1, it is possible to prevent discharge unevenness that occurs immediately after cleaning of the charging unit.

  Further, in Patent Document 2, after the charging device cleaning operation is completed, the charging current value is detected to check the contamination of the charging device. If the charging current value is equal to or less than a predetermined value, the charging device cleaning operation is performed again. An image forming apparatus that prompts the user to do so is disclosed. According to Patent Document 2, it is possible to prevent the charging abnormality from recurring immediately after the cleaning operation of the corona wire constituting the charger, and to maintain good image quality.

JP 2004-170474 A (released on June 17, 2004) JP 2006-184826 A (published July 13, 2006)

  However, the image forming apparatuses disclosed in Patent Document 1 and Patent Document 2 maintain the charged potential on the surface of the photoconductor at a predetermined potential throughout the life of the photoconductor, even if the discharge unevenness due to cleaning can be eliminated. It is not an effective means for solving the problems of ozone and nitrogen oxides generated by applying a current.

  The object of the present invention is to prevent uneven discharge of saw teeth and stabilize the charged potential of the surface of the photoreceptor, and suppress the generation of ozone and nitrogen oxides, and stably form high-quality images over a long period of time. An image forming apparatus that can perform the control, a control method thereof, a control program, and a recording medium are provided.

The present invention comprises an image carrier comprising a cylindrical substrate and a photosensitive layer formed on the surface of the substrate,
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A base portion having a base surface that holds the saw tooth perpendicular to the saw tooth, and a saw tooth holding member that holds the needle electrode in a holding portion that holds the saw tooth parallel to the saw tooth;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
Moving means for moving the cleaning member holder along the arrangement direction of the saw teeth;
After cleaning the needle electrode with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential is compared with a preset value that is a predetermined charged potential on the surface of the image carrier. And based on the results
(1) a first control operation of adjusting a voltage value applied to the grid electrode by the voltage applying means so that the charged potential on the surface of the image carrier becomes the set value;
(2) After changing the voltage value applied to the grid electrode by the voltage application means, the current value applied to the saw tooth by the current application means is adjusted so that the charged potential on the surface of the image carrier becomes the set value. Second control operation,
(3) a third control operation for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value;
(4) a fourth control operation that does not change the voltage value and the current value;
The image forming apparatus includes a control unit that selects and executes any one of the control operations.

  Further, the present invention is characterized in that the control means selects and executes the first control operation or the second control operation when the detected charging potential is lower than a set value.

  According to the present invention, in the second control operation, the voltage applied to the grid electrode is increased by the voltage applying means, and then the surface of the image carrier is charged. If it is low, the current value applied to the saw tooth by the current application means is adjusted.

  Further, the present invention is characterized in that the control means selects and executes a third control operation when the detected charging potential is higher than a set value.

The present invention also provides an image carrier comprising a cylindrical substrate and a photosensitive layer formed on the surface of the substrate,
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A base portion having a base surface that holds the saw tooth perpendicular to the saw tooth, and a saw tooth holding member that holds the needle electrode in a holding portion that holds the saw tooth parallel to the saw tooth;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
Moving means for moving the cleaning member holder along the arrangement direction of the saw teeth;
After cleaning the needle electrode with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential is compared with a preset value that is a predetermined charged potential on the surface of the image carrier. And based on the results
After changing the voltage value applied to the grid electrode by the voltage applying means, the surface of the image carrier is charged. If the charged potential of the image carrier surface at this time is lower than the set value, the charged potential of the surface of the image carrier is An image forming apparatus comprising: a control unit that adjusts a current value applied to the saw tooth by the current applying unit so as to be the set value.

  The present invention is characterized in that the current value before cleaning applied to the saw teeth by the current applying means is set according to the thickness of the photosensitive layer included in the image carrier at that time.

According to the present invention, the cleaning member holding body includes a pressure contact piece that presses the cleaning member against one end of the cleaning member holding body, and the shape of the base portion is changed as the saw blade moves along the arrangement direction of the saw teeth by the moving member. Accordingly, it moves in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth,
The base portion is curved in a direction parallel to the base surface.

According to the present invention, the moving means moves the cleaning member holding body along the screw shaft by rotation of a screw shaft provided along the longitudinal direction of the base portion. Depending on the shape of the base portion, it moves in a direction parallel to the base surface and orthogonal to the arrangement direction of the saw teeth,
The base part has a certain width,
The plurality of saw teeth are arranged in parallel to the screw axis and non-parallel to the central axis in the longitudinal direction of the base surface.

Further, in the invention, the moving means includes a screw shaft provided over the longitudinal direction of the base portion, and the cleaning member holder is moved along the screw shaft by rotation thereof.
The screw axis and the central axis in the longitudinal direction of the base surface are parallel,
The plurality of saw teeth are arranged non-parallel to the central axis and the screw axis.

The present invention also provides an image carrier comprising a cylindrical substrate and a photosensitive layer formed on the surface of the substrate,
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
In an image forming apparatus including a moving unit that moves the cleaning member holder along the arrangement direction of the saw teeth,
After cleaning the tip of the saw tooth with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential and a predetermined set value which is the charged potential of the surface of the image carrier are obtained. Compare and based on the result of the comparison,
(1) a first control operation for adjusting the voltage value applied to the grid electrode by the voltage applying means so that the charged potential on the surface of the image carrier becomes the set value;
(2) After changing the voltage value applied to the grid electrode by the voltage application means, the current value applied to the sawtooth by the current application means is adjusted so that the charged potential on the surface of the image carrier becomes the set value. Second control operation,
(3) a third control operation for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value;
(4) Do not change the voltage and current values,
A control method for an image forming apparatus, wherein one of the control operations is selected and executed.

  Further, the present invention is a program for operating the image forming apparatus, and is a control program for causing a computer to function as the control unit.

  The present invention is also a computer-readable recording medium on which the control program is recorded.

  According to the present invention, the needle electrode is cleaned by the cleaning member, and then the charged potential of the charged image carrier is detected by the potential detecting means. The control means compares the charged potential with the set value, and based on the result, (1) a voltage applied to the grid electrode by the voltage applying means so that the charged potential on the surface of the image carrier becomes the set value. A first control operation for adjusting the value; (2) after changing the voltage value applied to the grid electrode by the voltage applying means, the current applying means makes a sawtooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value. (3) Third control for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value. One of the control operations and the fourth control operation that does not change the voltage value and the current value is selected and executed. As a result, contaminants adhering to the tip of the sawtooth and discharge products such as ozone and nitrogen oxide can be cleaned, and the surface of the image carrier is not affected by the contaminant and discharge product on the sawtooth. Since the charging potential can be controlled to be a set value, a stable saw-tooth image carrier charge imparting performance without discharge unevenness can be realized. Accordingly, a high-quality image can be stably formed over a long period of time.

  According to the invention, the control means selects and executes the first control operation or the second control operation when the detected charging potential is lower than the set value, so that the current applied to the saw tooth is minimized. In addition, since the generation of discharge products can be suppressed, the degradation of the saw teeth and the adhesion of the discharge products at the tips of the saw teeth can be suppressed. Therefore, the frequency of cleaning can be reduced, and a high-quality image can be stably formed over a long period of time.

  According to the invention, in the second control operation, the voltage applied to the grid electrode is increased by the voltage applying means, and then the surface of the image carrier is charged, and the charged potential on the surface of the image carrier at this time is set. If it is lower than the value, the current value applied to the saw tooth by the current application means is adjusted, so even if the difference between the charged potential of the image carrier surface after increasing the voltage value and the set value is relatively large, The current applied to the saw tooth can be kept to a minimum, and the deterioration of the saw tooth and the attachment of the discharge product at the tip of the saw tooth can be suppressed.

  Further, according to the present invention, when the detected charging potential is higher than a set value, the control means selects and executes the third control operation, so that the current applied to the saw tooth can be reduced, and the discharge product Therefore, it is possible to suppress the degradation of the sawtooth and the attachment of the discharge product at the tip of the sawtooth. Therefore, the frequency of cleaning can be reduced, and a high-quality image can be stably formed over a long period of time.

  According to the invention, the needle electrode is cleaned with the cleaning member, and then the charged potential of the charged image carrier is detected by the potential detecting means. The control means compares the charged potential with the set value, changes the voltage value applied to the grid electrode by the voltage applying means based on the result, and then charges the surface of the image carrier, and the image carrier at this time If the charging potential on the surface of the body is lower than the set value, the current value applied to the saw teeth by the current applying means is adjusted so that the charging potential on the surface of the image carrier becomes the set value. As a result, contaminants adhering to the tip of the sawtooth and discharge products such as ozone and nitrogen oxide can be cleaned, and the sawtooth is applied to the sawtooth without being affected by the contaminant and the discharge product. Since the charging potential on the surface of the image carrier can be controlled to be a set value while keeping the current to a minimum, stable saw-tooth photoconductor charging performance can be realized. Accordingly, a high-quality image can be stably formed over a long period of time.

  According to the invention, the current value before cleaning applied to the saw teeth by the current applying means is set according to the thickness of the photosensitive layer included in the image carrier at that time. Even when the same current value is applied to the saw-tooth, the charged potential on the surface of the image carrier changes depending on the thickness of the photosensitive layer, so that the current value to be applied is set according to the thickness of the photosensitive layer. The applied current can be surely kept to a minimum, and the degradation of the sawtooth and the adhesion of the discharge product at the sawtooth tip can be further suppressed.

  According to the invention, the cleaning member holder includes a pressure contact piece that presses the cleaning member against one end of the cleaning member holder. The cleaning member holding body moves in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth according to the shape of the base portion as the moving means moves along the arrangement direction of the saw teeth. The base portion is curved in a direction parallel to the base surface. Accordingly, as the cleaning member holder is moved by the moving means, the cleaning member holder is surely moved in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth. The entire area can be brought into contact with the saw tooth. Therefore, since the saw teeth can be reliably cleaned using the entire outer peripheral surface of the cleaning member, it is possible to maintain a stable cleaning property of the needle electrode, and it is possible to provide uniform charging without uneven discharge over a long period of time. A high-quality image can be obtained more stably. In addition, since it is possible to prevent only a part of the cleaning member from being in contact with the sawtooth during cleaning, it is possible to extend the life of the cleaning member and the sawtooth.

  According to the invention, the cleaning member holder includes a pressure contact piece that presses the cleaning member against one end of the cleaning member holder. The cleaning member holding body moves in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth according to the shape of the base portion as the moving means moves along the arrangement direction of the saw teeth. The moving means moves the cleaning member holder along the screw shaft by rotation of a screw shaft provided in the longitudinal direction of the base portion, the base portion has a certain width, and the plurality of saw teeth They are arranged parallel to the axis and non-parallel to the central axis in the longitudinal direction of the base surface. Accordingly, the saw teeth can be reliably cleaned using the entire outer peripheral surface of the cleaning member. Therefore, uniform charging without unevenness of discharge can be performed over a long period of time, and a high-quality image can be obtained more stably. In addition, since it is possible to prevent only a part of the cleaning member from being in contact with the sawtooth during cleaning, it is possible to extend the life of the cleaning member and the sawtooth.

  According to the invention, the moving means includes a screw shaft provided over the longitudinal direction of the base portion, and the cleaning member holder is moved along the screw shaft by the rotation thereof, and the longitudinal direction of the screw shaft and the base surface Is parallel to the central axis. Since the plurality of saw teeth are arranged non-parallel to the central axis and the screw axis, when the cleaning member holder is moved along the screw axis, the entire outer peripheral surface of the cleaning member may be brought into contact with the needle electrode. it can. Therefore, since the saw-tooth can be reliably cleaned using the entire outer peripheral surface of the cleaning member, a stable cleaning property of the needle electrode can be maintained, and a charging device capable of uniformly charging without uneven discharge over a long period of time is provided. can do. In addition, since it is possible to prevent only a part of the cleaning member from being in contact with the sawtooth during cleaning, it is possible to extend the life of the cleaning member and the sawtooth.

  According to the invention, in the control method of the image forming apparatus, the needle electrode is cleaned by the cleaning member, and then the charged potential of the charged image carrier is detected by the potential detecting means. Based on the result of the comparison, the control means adjusts the voltage value applied to the grid electrode by the voltage application means so that the charged potential on the surface of the image carrier becomes the set value, the voltage application means A second control operation for adjusting the current value applied to the sawtooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value after the voltage value applied to the grid electrode is changed by Any one of the third control operation for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the carrier becomes the set value, and the voltage value and the current value are not changed. Select and execute. As a result, contaminants adhering to the tip of the sawtooth and discharge products such as ozone and nitrogen oxide can be cleaned, and the surface of the image carrier is not affected by the contaminant and discharge product on the sawtooth. Since the charging potential can be controlled to be a set value, a stable saw-tooth photoreceptor charging performance can be realized. Accordingly, a high-quality image can be stably formed over a long period of time.

  According to the invention, the control program is a program for operating the image forming apparatus of the invention, and causes the computer to function as the control means, so that the potential on the surface of the image carrier detected by the potential detection means. The control means can read and execute a method of controlling the charged potential on the surface of the image carrier by the voltage applied to the grid electrode and the current applied to the saw tooth by comparing the set value with the set value. Can be general purpose.

  According to the invention, since the control program is recorded on the recording medium and can be read by a computer, the potential of the surface of the image carrier detected by the potential detecting means is compared with the set value and applied to the grid electrode. The program for controlling the charging potential on the surface of the image carrier by the voltage to be applied and the current applied to the saw tooth can be easily supplied to the computer.

1 is a diagram schematically illustrating a configuration of an image forming apparatus 100 according to a first embodiment of the present invention. FIG. 2 is an explanatory view showing a structure around a photoconductor 11 shown in FIG. 1. 3 is a side view schematically showing a configuration of a first charging device 301. FIG. 3 is a bottom view schematically showing a configuration of a first charging device 301. FIG. FIG. 5 is a cross-sectional view of the first charging device 301 shown in FIG. 4 as viewed from a cutting plane line S357-S357. FIG. 6 is an enlarged view around the cleaning rubber roller 66 shown in FIG. 5. It is sectional drawing which looked at the charging device 301 shown in FIG. 6 from cut surface line S309-S309. FIG. 8 is an enlarged view around the cleaning member holder 394 shown in FIG. 7. FIG. 4 is a bottom view schematically showing the configuration of the second charging device 1. It is sectional drawing which looked at the 2nd charging device 1 shown in FIG. 9 from cut surface line S5-S5. FIG. 11 is an enlarged view around the cleaning rubber roller 66 shown in FIG. 10. It is sectional drawing which looked at the charging device 1 shown in FIG. 11 from cut surface line S50-S50. FIG. 10 is a bottom view showing a state in which the cleaning member holding body 94 has moved to the longitudinal center of the saw-tooth holding member 62. It is sectional drawing which looked at the charging device 1 shown in FIG. 13 from cut surface line S55-S55. 10 is a bottom view showing a state where the cleaning member holding body 94 has moved to the end of the saw-tooth holding member 62. FIG. It is sectional drawing which looked at the charging device 1 shown in FIG. 15 from cut surface line S57-S57. FIG. 6 is a bottom view schematically showing a configuration of a third charging device 93. FIG. 10 is a bottom view schematically showing configurations of a cleaning rubber roller 66 and guide means included in a fourth charging device 95. FIG. 6 is a bottom view schematically showing a configuration of a fifth charging device 101. It is sectional drawing which looked at the 5th charging device 101 shown in FIG. 19 from cut surface line S105-S105.

It is sectional drawing which looked at the 5th charging device 101 shown in FIG. 20 from cut surface line S150-S150. 10 is a bottom view showing a state where the cleaning member holding body 194 has moved to the center in the longitudinal direction of the saw-tooth holding member 162. FIG. It is sectional drawing which looked at the charging device 101 shown in FIG. 22 from cut surface line S155-S155. 10 is a bottom view showing a state where the cleaning member holding body 194 has moved to the end of the saw-tooth holding member 162. FIG. FIG. 25 is a cross-sectional view of the charging device 101 shown in FIG. 24 when viewed from a cutting plane line S157-S157. 6 is a flowchart showing a control method for adjusting the charged potential on the surface of the photoreceptor after the saw-tooth cleaning. 6 is a graph showing the relationship between the charging current of the sawtooth and the charging potential Vo on the surface of the photosensitive member due to the difference in the thickness of the photosensitive layer when the grid bias Vg is fixed to −620V. It is a graph which shows the relationship between the grid bias Vg and the charging potential Vo of the photoreceptor surface when the charging current value of the sawtooth is fixed to -700 μA. 7 is a graph showing the relationship between the grid bias Vg and the charging potential Vo on the surface of the photoreceptor when the sawtooth charging current value is fixed at −350 μA. 6 is a graph showing the relationship between the grid bias Vg and the charging potential on the surface of the photosensitive member according to the photosensitive member film thickness and the charging current value applied to the saw-tooth.

1. Image Forming Apparatus (1) Configuration of Image Forming Apparatus FIG. 1 is a diagram schematically showing a configuration of an image forming apparatus 100 according to the first embodiment of the present invention. The image forming apparatus 100 according to the present embodiment is an electrophotographic full-color image forming apparatus. For example, based on image data transmitted from the outside via a network or image data read by the reading unit 206, a recording paper ( A multi-color or single-color image is formed on the transfer medium.

  As shown in FIG. 1, the image forming apparatus 100 includes a visible image forming unit 10, a supply tray 20, a recording paper transport unit 30, and a fixing device 40. Here, the image (toner image) developed by the visible image forming unit 10 is directly transferred to the recording paper P, but may be transferred to an intermediate transfer medium such as an intermediate transfer belt. .

  The visible image forming unit 10 includes four visible image forming units 10Y, 10M, 10C, and 10B corresponding to yellow (Y), magenta (M), cyan (C), and black (B). It is installed side by side. In other words, the visible image forming unit 10 includes four visible image forming units 10Y, 10M, 10C, and 10B. The visible image forming unit 10Y forms an image using yellow (Y) toner, and a visible image is formed. The forming unit 10M forms an image using magenta (M) toner, the visible image forming unit 10C forms an image using cyan (C) toner, and the visible image forming unit 10B is black (B). An image is formed using the toner. As a specific arrangement, four sets of visible image forming units 10Y, 10M, 10C, and 10B are arranged along the conveyance path for conveying the recording paper P from the supply tray 20 to the fixing device 40. The toner of each color is multiplex-transferred onto the recording paper P to be printed. As shown in FIG. 2, the visible image forming units 10Y, 10M, 10C, and 10B have substantially the same configuration. That is, the photoconductor 11, the surface potential meter 313, the first charging device 301, the laser beam irradiation means 13, the developing device 14, the transfer roller 15, the cleaner unit 16, and the charge eliminating device 17 are provided.

  FIG. 2 is an explanatory view showing the structure around the photoconductor 11 shown in FIG. The first charging device 301, the surface potential meter 313, the laser light irradiation means 13, the developing device 14, the transfer roller 15, the cleaner unit 16 and the charge eliminating device 17 are arranged in this order so as to face the surface of the photoconductor 11 as an image carrier. Is done.

  The photoreceptor 11 includes a cylindrical photoreceptor support base (not shown) and a photosensitive layer formed on the surface of the photoreceptor support base. The photoreceptor support base is formed of a conductive material. The photoreceptor support substrate of this embodiment uses an aluminum base tube using aluminum as a conductive material. The photosensitive layer is formed, for example, by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. Examples of the charge generating substance include perylene pigments such as perylene imide and perylene acid anhydride. Examples of the charge transport material include poly-N-vinylcarbazole and derivatives thereof.

  The first charging device 301 is for uniformly charging the surface of the photoconductor 11 to a predetermined potential. A non-contact charging method in which the surface of the photoconductor 11 is brought close to the surface of the photoconductor 11 in a non-contact manner and charged by corona discharge and grid bias control. The corona charging system charging device is used.

  A surface potential meter 313 serving as a potential detection unit is a device that measures the charged potential on the surface of the photoconductor 11.

  The laser beam irradiation unit 13 exposes the surface of the photoconductor 11 charged by the first charging device 301 according to image data, and forms an electrostatic latent image on the surface of the photoconductor 11.

  The developing device 14 supplies toner to the electrostatic latent image formed on the surface of the photoconductor 11 and develops it to form a visible toner image. When supplying toner to the surface of the photoreceptor 11, a potential having a polarity opposite to the toner charging potential is applied to the developing device 14 as a developing bias voltage. As a result, the toner is smoothly supplied to the electrostatic latent image.

  The transfer roller 15 is applied with a bias voltage having a polarity opposite to that of the toner, and transfers the toner image formed on the photoconductor 11 onto the recording paper P conveyed by the recording paper conveyance means 30.

The cleaner unit 16 removes and collects the toner remaining on the surface of the photoconductor 11 after the transfer process by the transfer roller 15. The cleaner unit 16 includes a case 54 and a cleaning blade 51. The cleaning blade 51 is for collecting toner remaining on the surface of the photoconductor 11 and is formed of a long rubber member whose longitudinal direction is the axial direction of the photoconductor 11.
The neutralization device 18 is a device that neutralizes the surface of the photoreceptor 11.

  In each visible image forming unit having the above-described configuration, the surface of the photoconductor 11 is charged by the first charging device 301 after being neutralized by the static eliminator 17, and the surface of the charged photoconductor 11 is irradiated by the laser light irradiation means 13. An electrostatic latent image is formed by exposure, the electrostatic latent image is developed by the developing device 14, and the developed toner image is transferred onto the recording paper P by the transfer roller 15. The toner image remaining on the surface of the photoconductor 11 after the transfer process is removed and collected by the cleaner unit 16. Then, the transfer of the toner image onto the recording paper P is sequentially performed in the visible image forming unit 10 of each color, so that the toner images of the respective colors are transferred onto the recording paper P in a multiple manner.

  Returning to FIG. 1, the recording paper conveyance means 30 includes a driving roller 31, an idling roller 32 and a conveyance belt 33, and the recording paper is transferred to the recording paper P by each visible image forming unit 10. Transport P. The drive roller 31 and the idling roller 32 stretch an endless conveyance belt 33, and the conveyance belt 33 rotates when the drive roller 31 is rotationally driven at a predetermined peripheral speed. Further, the outer surface of the conveying belt 33 is charged to a predetermined potential, and conveys the recording paper P while being electrostatically attracted.

  The recording paper transported by the recording paper transporting means 30 and passed through each visible image forming unit 10 and having the toner image (unfixed toner image) transferred thereon is peeled off from the transport belt 33 by the curvature of the driving roller 31 and fixed. It is conveyed to the device 40.

  The fixing device 40 applies appropriate heat and pressure to the recording paper P, dissolves the toner transferred onto the recording paper P and fixes it on the recording paper P, and discharges the recording paper to a paper discharge tray (not shown). To discharge. The configuration of the fixing device 40 is not particularly limited. For example, a configuration in which a heating roller 41 and a pressure roller 42 are provided, and the recording paper P is conveyed while being sandwiched between these rollers can be used. By these operations, an image is formed on the recording paper P.

  The operation of each member provided in the image forming apparatus 100 is controlled by a main control unit (a control integrated circuit board (not shown) or a computer (not shown)) which is a control means.

(2) Charging Device Hereinafter, the configuration of the first charging device 301 will be described in detail.

(First charging device 301)
FIG. 3 is a side view schematically showing the configuration of the first charging device 301. FIG. 4 is a bottom view schematically showing the configuration of the first charging device 301. FIG. 5 is a cross-sectional view of the first charging device 301 shown in FIG. 4 as viewed from the cutting plane line S357-S357.

  Although omitted in FIGS. 3 and 4, the first charging device 301 (hereinafter referred to as “charging device 301”) is surrounded by a charging case 300 as shown in FIG. The tooth holding member 362, the cleaning rubber roller 66, the cleaning member holding body 394, the moving means 303, the screen grid 64, and the terminal portion 350 are included.

  The needle electrode 363 is made of a thin band-shaped metal material, and a plurality of saw teeth 53 extend downward at regular intervals over the entire length thereof. The plurality of saw teeth 53 are arranged in one direction along arrows B 1 and B 2 parallel to the length direction of the needle electrode 363. Due to the discharge from the needle electrode 363, the surface of the photoreceptor 11 described later is charged to a uniform potential. The plurality of saw teeth 53 are arranged in the longitudinal direction of the photoconductor 11, and there is a certain distance between the tip of the saw teeth 53 and the photoconductor 11. The length of the needle electrode 363 is longer than the axial length of the peripheral surface of the photoreceptor 11. A constant current power source is connected to the saw tooth 53. A constant voltage power source is connected to the screen grid 64.

  A saw tooth holding member 362 that holds a plurality of saw teeth includes a base portion 306 having a base surface 308 that holds the saw teeth 53 perpendicular to the saw teeth 53, and the saw teeth 53 parallel to the saw teeth 53. The needle electrode 363 is held by the holding portion 307 to be held. The length of the saw-tooth holding member 362 is longer than the length of the needle electrode 363. The base portion 306 is formed by integrally forming non-existing portions 362b where the saw teeth 53 are not present at both ends of the existing portions 362a where the saw teeth 53 are present. In the present embodiment, the longitudinal length 383 of the existence portion 362a is (328) mm, and the lateral length 384 is 10 mm. The saw-tooth holding member 362 is fixed to the charging case 300 of the charging device 301 at both ends in the longitudinal direction. The saw-tooth holding member 362 is made of an insulating material such as synthetic resin.

  The cleaning rubber roller 66 as a cleaning member is formed between the two rotating rollers (the first rotating roller 67a and the second rotating roller 67b) on the outer periphery of the shaft 65. The cleaning rubber roller 66 is disposed so as to move along the arrangement direction of the saw teeth 53 between the tip portion of the saw teeth 53 and the photosensitive member 11, and the outer periphery of the cleaning rubber roller 66 sequentially extends to the tip portions of the plurality of saw teeth 53 during the movement. The needle electrode 363 is cleaned by the contact of the surfaces.

  FIG. 6 is an enlarged view around the cleaning rubber roller 66 shown in FIG. FIG. 7 is a cross-sectional view of the charging device 301 shown in FIG. 6 as seen from the cutting plane line S309-S309. The cleaning rubber roller 66 is a roll-shaped member having a three-layer structure in which a columnar shaft 65, a cylindrical cored bar 67, and an elastic layer 96 are formed in order from the inside. Examples of the material of the shaft 65 include polycarbonate and SUS (Stainless Used Steel). Examples of the material of the cored bar 67 include polycarbonate and SUS material. Examples of the material of the elastic layer 96 include EPDM (ethylene propylene diene rubber). The diameter of the cleaning rubber roller 66 can be made as large as possible without touching the peripheral surface of the screen grid 64. For example, the diameter is 6 mm and the length in the axial direction is 4 mm. The cleaning rubber roller 66 uses a shaft 65 made of polycarbonate as a material, has an outer diameter of 2 mm, uses a cored bar 67 made of polycarbonate as a material, has a thickness of 1.5 mm, and an axial length of 4 mm. The elastic layer 96 is made of ethylene propylene diene rubber. Note that both the shaft 65 and the core metal 67 may be integrally molded using polycarbonate as a material.

  As shown in FIG. 7, the floating toner adhered to the tip of the saw tooth 53 by the dust collecting action of electrostatic force accompanying corona discharge by sequentially contacting the tip of the saw tooth 53 so as to be buried in the cleaning rubber roller 66. Volatile TMS and dust are cleaned. The cleaning rubber roller 66 moves along the arrows B <b> 1 and B <b> 2 while being rotated by the resistance acting on the peripheral surface from the plurality of saw teeth 53. A cleaning member holding body 394, which will be described later, holds the cleaning rubber roller 66 so that the tip of the saw-tooth 53 is embedded in the circumferential surface of the cleaning rubber roller 66 with a length of about 0.5 mm.

  Returning to FIGS. 3, 4, and 5, the cleaning member holder 394 includes a rubber roller holder 302, a shaft 65, two rotating rollers 67 a and 67 b, and projecting pieces 302 a and 302 b. The cleaning member holder 394 rotatably supports the cleaning rubber roller 66 by fixing both end portions of the shaft 65 to the rubber roller holder 2 so as to be rotatable. The protruding pieces 302 a and 302 b are formed on the inner surface side of the cleaning member holder 394. The cleaning member holding body 394 sandwiches the saw-tooth holding member 362 in the vertical direction between the upper surface 302c on the inner surface and the protrusions 302a and 302b, and sandwiches the saw-tooth holding member 362 in the left-right direction on the side surfaces 302d and 302e on the inner surface. . For this reason, the cleaning member holding body 394 is restricted from moving including rotation in a direction parallel to the base surface 308 and perpendicular to the arrows B1 and B2. After cleaning the needle electrode 363, the cleaning member holder 394 moves to a position where there is no saw tooth 53 that does not hinder printing, that is, to one of the two non-existing portions 362b.

  FIG. 8 is a cross-sectional view of the charging device 301 shown in FIG. 4 as viewed from the section line S350-S350. As shown in FIG. 8, the moving means 303 includes a screw screw 70 and a moving member 371. The moving member 371 has a screw hole 82 that is screwed into the screw screw 70 that is a screw shaft. The screw screw 70 is provided over the longitudinal direction of the base portion 306, and the cleaning member holder 394 is moved along the screw screw 70 by the rotation thereof. The screw screw 70 is rotated by a motor (not shown). The motor can rotate forward and reverse. When the screw screw 70 rotates in the direction of the arrow A1, the cleaning member holding body 394 moves in the direction of the arrow B1 by the rotation, and when the screw screw 70 rotates in the direction of the arrow A2, the rotation holds the cleaning member. The body 394 moves in the direction of the arrow B2. The screw 70 is configured in parallel with the arrangement direction of the saw teeth 53 and the axial direction of the photoreceptor 11.

  The terminal part 350 accommodates a terminal (not shown). The terminal connects the high voltage power source and the needle electrode 363. When a high voltage power source is applied to the needle electrode 363 via the terminal, the applied electric field is concentrated on the tip of the saw tooth 53, and this portion is easily discharged. As a result, the surface of the photoreceptor 11 is discharged from the plurality of saw teeth 53, and the surface of the photoreceptor 11 is charged to a predetermined potential by this discharge.

  Hereinafter, in addition to the first charging device 301, a plurality of configuration examples of charging devices that can be used in the image forming apparatus 100 of the present embodiment will be given.

(Second charging device 1)
FIG. 9 is a bottom view schematically showing the configuration of the second charging device 1. FIG. 10 is a cross-sectional view of the second charging device 1 shown in FIG. 9 as seen from the cutting plane line S5-S5. As shown in FIGS. 9 and 10, the second charging device 1 (hereinafter referred to as “charging device 1”) includes a needle electrode 63, a saw tooth holding member 62, a cleaning rubber roller 66, and a cleaning member holding body 94. The moving means 3, the guiding means, a screen grid (not shown), and a terminal portion (not shown) are included. Since the screen grid and the terminal portion have the same configuration as that of the charging device 301, description thereof is omitted.

  The needle electrode 63 has a plurality of saw teeth 53 arranged in one direction. Due to the discharge from the needle electrode 63, the surface of the photoreceptor 11 described later is charged to a uniform potential. The plurality of saw teeth 53 are arranged in the longitudinal direction of the photoreceptor, and there is a certain distance between the tip of the saw teeth 53 and the photoreceptor 11.

A saw tooth holding member 62 that holds a plurality of saw teeth includes a base portion 6 having a base surface 8 that holds the saw teeth 53 perpendicular to the saw teeth 53, and the saw teeth 53 parallel to the saw teeth 53. The needle electrode 63 is held by the holding portion 7 to be held. As shown in FIG. 9, the saw-tooth holding member 62 has a certain width and is curved in a direction parallel to the base surface 8, that is, in the direction of the arrow A3. The saw-tooth holding member 62 is formed by integrally forming a non-existing portion 62b where the saw-tooth 53 is not present at both ends of the presence portion 62a where the saw-tooth 53 is present. In the present embodiment, the length 83 in the longitudinal direction of the existence portion 62a is 328 mm, and the length 84 in the short direction is 10 mm. The curvature of the saw-tooth holding member 62 is 1.481 × 10 ⁻¹ (1 / m). The curvature is a value indicating the degree of curving of the curve or curved surface at each point on the curve or curved surface. The curvature is indicated by the reciprocal of the radius of curvature. For example, the curvature of a curvature circle with a radius of curvature r is 1 / r, and the greater the degree of curling, the greater the value of curvature. In the present embodiment, the curvature of the saw-tooth holding member 62 is set by an arc BC formed by the central axis 99 in the existence part 62 a and both end portions B and C of the central axis 99. The length of the arc BC is 329.8 mm, the length of the chord of the arc BC is equal to the length 83 in the longitudinal direction of the existence portion 62a, and the curvature radius of the curvature circle including the arc BC is 6752 mm. The angle formed by both ends B and C of the central axis 99 and the center of curvature is 2.8 °. The saw-tooth holding member 62 is fixed to a charging case (not shown) of the charging device 1 at both ends in the longitudinal direction.

  The cleaning rubber roller 66 as a cleaning member is formed between the two rotating rollers (the first rotating roller 67a and the second rotating roller 67b) on the outer periphery of the shaft 65. The cleaning rubber roller 66 is disposed so as to move along the arrangement direction of the saw teeth 53 between the tip portion of the saw teeth 53 and the photosensitive member 11, and the outer periphery of the cleaning rubber roller 66 sequentially extends to the tip portions of the plurality of saw teeth 53 during the movement. The needle electrode 63 is cleaned by contacting the surface.

  FIG. 11 is an enlarged view around the cleaning rubber roller 66 shown in FIG. The configuration of the cleaning rubber roller 66 is the same as the configuration of the cleaning rubber roller 66 in the charging device 301.

  9 and 10, the cleaning member holder 94 includes a rubber roller holder 2, a shaft 65, and two rotating rollers 67a and 67b. The cleaning member holding body 94 rotatably supports the cleaning rubber roller 66 by fixing both ends of the shaft 65 to the rubber roller holding body 2 in a rotatable manner. After cleaning the needle electrode 63, the cleaning member holder is moved by the moving means to a position without the saw tooth 53 that does not hinder printing, that is, one of the two non-existing portions 62b. As shown in FIG. 11, when the rubber roller holder 2 is present at one end of the saw-tooth holding member 62, the tip end of the saw-tooth 53 is in contact with the end of the cleaning rubber roller 66 on the first rotating roller 67 a side.

  FIG. 12 is a cross-sectional view of the charging device 1 shown in FIG. 9 as viewed from the cutting plane line S50-S50. As shown in FIG. 14, the moving means 3 includes a screw screw 70 and a moving member 71. The moving member 71 is integrally formed with a base 80 and an inverted T-shaped guide rail 81 on the lower surface of the base 80. A screw hole 82 that is screwed from a screw screw 70 that is a screw shaft passes through the base portion 80. The screw screw 70 is provided over the longitudinal direction of the base portion 6, and the cleaning member holding body 94 is moved along the screw screw 70 by the rotation thereof. The screw screw 70 is rotated by a motor (not shown). The motor can rotate forward and reverse. When the screw screw 70 rotates in the direction of the arrow A1, the cleaning member holder 94 moves in the direction of the arrow B1 by the rotation, and when the screw screw 70 rotates in the direction of the arrow A2, the rotation holds the cleaning member. The body 94 moves in the direction of the arrow B2. The screw 70 is configured in parallel with the arrangement direction of the saw teeth 53 and the axial direction of the photoreceptor 11.

  In the rubber roller holder 2 constituting the cleaning member holder 94, a guide groove 89 and a pair of holders 88 on the lower surface of the guide groove 89 are integrally formed. The pair of holding portions 88 are integrally formed at intervals in the directions of C1 and C2 so that the saw-tooth holding member 62 is accommodated. The guide groove 89 has an inverted T-shaped cross section and forms a guide groove 90. The guide groove 90 has an inverted T-shaped cross section, and a guide rail 81 is fitted therein, and guides the guide rail 81 so that it can move in the directions of C1 and C2. A shaft 65 is rotatably fixed to each holding portion. End walls (not shown) exist at both ends in the C direction of the guide groove 89. Therefore, the guide rail 81 moves in the direction C between the end walls. When the charging device 1 shown in FIG. 11 is viewed from the side, the guide groove 90 is not visible, and the rubber roller holder 2 and the moving member 71 appear to be formed integrally. Since the rubber roller holder 2 and the moving means 3 are configured as described above, the cleaning member holder 94 is parallel to the base surface 8 and perpendicular to the arrangement direction of the saw teeth 53, that is, in the direction C. It becomes possible to move. The structure of the cleaning member holder 94 and the moving means 3 is not limited to the above structure as long as it can move in the direction C.

  The guide means moves the cleaning member holding body 94 in a direction parallel to the base surface 8 and perpendicular to the arrangement direction of the saw teeth 53, that is, in the direction of C in accordance with the movement of the cleaning member holding body 94 by the moving means 3. Let In the present embodiment, the base portion 6 corresponds to the guide means.

  Returning to FIG. 10, one of the inner surfaces of the pair of holding portions 88 facing each other is fixed integrally with the holding portion 88 and one of the saw-tooth holding members 62 inserted between the holding portions. It has a pressure contact piece 4 that elastically contacts the side surface. The pressure contact piece 4 presses the saw tooth holding member 62 with resin elasticity. As described above, the base portion 6 is curved in a direction parallel to the base surface 8, and the cleaning member holding body 94 moves smoothly along the saw-tooth holding member 62 including the curved base portion 6. For this, a certain amount of gap 52 is required in a direction parallel to the base surface 8 between the saw-tooth holding member 62 and the rubber roller holder 2. However, if there is a gap 52, the cleaning member holder 94 can move freely in a direction parallel to the base surface 8 and perpendicular to the direction in which the saw teeth 53 are arranged. By providing the pressure contact piece 4 so that the cleaning rubber roller 66 is always in contact with one end of the rubber roller holder 2, the cleaning member holder 94 can smoothly move along the curved saw-tooth holding member 62, and cleaning is performed. The member holding body 94 can be reliably moved in the desired directions of the arrows A4 and A5. In the present embodiment, the width of the gap 52 is 2 mm. Although the material of the press-contacting piece 4 will not be specifically limited if it has a certain amount of elasticity, In this embodiment, it is a polycarbonate resin. The shape of the pressure contact piece 4 is not limited to the shape shown in FIG. 2 as long as the saw tooth holding member 62 can be pressed against one end of the rubber roller holder 2, but the friction coefficient with the saw tooth holding member 62 is small, and the cleaning is performed. A shape that does not hinder the movement of the member holder 94 is preferable.

  FIG. 13 is a bottom view showing a state in which the cleaning member holding body 94 has moved to the longitudinal center of the saw-tooth holding member 62. FIG. 14 is a cross-sectional view of the charging device 1 shown in FIG. 13 as seen from the section line S55-S55. As shown in FIG. 14, when the rubber roller holder 2 is at the center of the saw tooth holding member 62, the tip of the saw tooth 53 is in contact with the second rotating roller 67 b side of the cleaning rubber roller 66. This is due to the movement of the rubber roller holder 2 along the arrangement direction of the saw teeth 53, in a direction parallel to the base surface 8 and perpendicular to the arrangement direction of the saw teeth 53 according to the shape of the base portion 6. This is because the cleaning member holder 94 has moved. Until the cleaning member holder 94 moves to the center of the saw tooth holding member 62, the saw tooth 53 extends from the end on the first rotating roller 67a side to the end on the second rotating roller 67b side on the outer peripheral surface of the cleaning rubber roller 66. The position in contact with the tip of the is moved.

  FIG. 15 is a bottom view showing a state where the cleaning member holding body 94 has moved to the end of the saw-tooth holding member 62. FIG. 16 is a cross-sectional view of the charging device 1 shown in FIG. 15 as viewed from the section line S57-S57. As shown in FIG. 15, when the cleaning member holder 94 is present at one end of the saw tooth holding member 62, the tip of the saw tooth 53 is in contact with the first rotating roller 67 a side on the outer peripheral surface of the cleaning rubber roller 66. . This is a direction parallel to the base surface 8 and perpendicular to the arrangement direction of the saw teeth 53 according to the shape of the base portion 6 as the cleaning member holder 94 moves along the arrangement direction of the saw teeth 53. This is because the cleaning member holder 94 has moved. Until the rubber roller holder 2 moves to the end of the saw-tooth holding member 62, the saw-tooth 53 of the cleaning rubber roller 66 extends from the end on the second rotating roller 67b side to the end on the first rotating roller 67a side. The position in contact with the tip moves. That is, the entire outer peripheral surface of the cleaning rubber roller 66 is surely in contact with the tip of the saw tooth 53.

  Thus, in the present embodiment, as the cleaning member holder 94 is moved by the moving means, the cleaning member holder 94 is parallel to the base surface 8 according to the shape of the base portion 6 and the saw tooth 53 Since it moves in the direction orthogonal to the arrangement direction, the entire outer peripheral surface of the cleaning rubber roller 66 can be brought into contact with the saw tooth 53. Accordingly, since the saw-tooth 53 can be reliably cleaned using the entire outer peripheral surface of the cleaning rubber roller 66, stable cleaning of the needle electrode 63 can be maintained, and uniform charging without uneven discharge can be performed over a long period of time. The charging device 1 can be obtained. Further, since it is possible to prevent only a part of the cleaning rubber roller 66 from being kept in contact with the saw tooth 53 at the time of cleaning, the life of the cleaning rubber roller 66 and the saw tooth 53 can be extended.

(Third charging device 93)
FIG. 17 is a bottom view schematically showing the configuration of the third charging device 93. The third charging device 93 (hereinafter referred to as “charging device 93”) has the same configuration as the charging device 1 except that the shape of the saw-tooth holding member 92 is different. As shown in FIG. 17, in the present embodiment, the saw-tooth holding member 92 has a certain width, and the arrangement direction of the plurality of saw teeth 53 and the central axis 91 in the longitudinal direction of the base surface are non-parallel. Even if the saw-tooth holding member 92 having such a shape is used, the saw-tooth 53 can be reliably cleaned over the entire outer peripheral surface of the cleaning rubber roller 66, so that stable cleaning performance and image quality can be maintained. Further, the life of the cleaning rubber roller 66 and the saw tooth 53 can be extended.

(Fourth charging device 95)
FIG. 18 is a bottom view schematically showing the configuration of the cleaning rubber roller 66 and guide means included in the fourth charging device 95. The fourth charging device 95 (hereinafter referred to as “charging device 95”) is different from the charging device 1 and the charging device 93 in that the guide means is the guide 68. Further, the shape of the saw-tooth holding member is different from that of the charging device 1 and the charging device 93, and the central axis in the longitudinal direction of the base surface having a certain width is parallel to the arrangement direction of the screw screw 70 and the saw-tooth 53. Since other configurations are the same as those of the charging device 1 and the charging device 93, description thereof is omitted.

  The guide 68 includes a first guide member 68a and a second guide member 68b. The first rotating roller 67a moves along the first guide member 68a, and the second rotating roller 67b moves along the second guide member 68b. The pair of guide members are parallel to the base surface and curved in a direction perpendicular to the arrangement direction of the saw teeth 53, whereby the cleaning member holder is moved along with the movement of the cleaning member holder by the moving means. Depending on the shape of the base portion, it moves in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth 53, so that the entire outer peripheral surface of the cleaning rubber roller 66 can be brought into contact with the saw teeth 53. Accordingly, since the saw-tooth 53 can be reliably cleaned using the entire outer peripheral surface of the cleaning rubber roller 66, the stable cleaning of the needle electrode can be maintained, and charging that can provide uniform charging without uneven discharge over a long period of time is possible. The device 1 can be obtained. Further, since it is possible to prevent only a part of the cleaning rubber roller 66 from being kept in contact with the saw tooth 53 at the time of cleaning, the life of the cleaning rubber roller 66 and the saw tooth 53 can be extended.

(Fifth charging device 101)
FIG. 19 is a bottom view schematically showing the configuration of the fifth charging device 101. FIG. 20 is a cross-sectional view of the fifth charging device 101 shown in FIG. 19 as viewed from the section line S105-S105. FIG. 21 is a cross-sectional view of the fifth charging device 101 shown in FIG. 19 as viewed from the cutting plane line S150-S150. 19 and 20, the fifth charging device 101 (hereinafter referred to as “charging device 101”) includes a needle electrode 163, a saw-tooth holding member 162, a cleaning rubber roller 66, a cleaning member holding body 194, and the like. , Moving means 103. The charging device 101 is different from the charging device 93 in that it does not include guide means. The structures of the saw-tooth holding member 162, the rubber roller holding member 102 and the moving member 171 included in the cleaning member holding body 194 are also different. Since the other configuration is the same as that of the charging device 93, the description is omitted and the same reference numerals are used in the drawings.

  The saw tooth holding member 162 has a base portion 106 having a base surface 108 that holds the saw tooth 53 perpendicular to the saw tooth 53, and a holding portion 107 that holds the saw tooth 53 parallel to the saw tooth 53. The electrode 163 is held. The moving means 103 includes a screw screw 70 that is a screw shaft provided along the longitudinal direction of the base portion 106, and moves the cleaning member holder 194 along the screw screw 70 by its rotation. The cleaning member holder 194 rotatably supports the cleaning rubber roller 66 that is a cleaning member. As shown in FIG. 21, the moving member 171 does not include the guide rail 81 having the inverted T-shaped cross section shown in FIG. 12, and the cleaning member holder 194 does not include the guide groove portion 89, and A rubber roller holding member 102 is integrally formed on the lower surface. Therefore, in this embodiment, the rubber roller holding member 102 does not move in the direction C, and the pressure contact piece 4 that presses the rubber roller holding member 102 against one side surface of the saw tooth holding member 162 is not included.

  In the charging device 93, the plurality of saw teeth 53 are arranged in parallel to the screw screw 70 and non-parallel to the central axis in the longitudinal direction of the base surface, but in the charging device 101, the screw screw 70 is arranged. Are parallel to the central axis 191 in the longitudinal direction of the base surface 108, and the plurality of saw teeth 53 are arranged non-parallel to the central axis 191 and the screw screw 70. Specifically, the angle formed by the arrangement direction of the saw-tooth 53 and the central axis 191 is 0.5 °, and the saw-tooth 53 is arranged on the diagonal line of the rectangular existence portion 162 a of the saw-tooth holding member 162. The For the purpose of cleaning the entire outer peripheral surface of the cleaning rubber roller 66, the angle between the arrangement direction of the saw teeth 53 and the central shaft 191 is adjusted, so that the angle is the length in the axial direction of the cleaning rubber roller 66 and the existence portion 162a. It is determined by the length in the longitudinal direction.

  As shown in FIG. 20, when the cleaning member holder 194 is present at one end of the saw tooth holding member 162, the tip of the saw tooth 53 is located on the outer peripheral surface of the cleaning rubber roller 66 with the end on the first rotating roller 67 a side. It touches.

  FIG. 22 is a bottom view showing a state where the cleaning member holding body 194 has moved to the center in the longitudinal direction of the saw-tooth holding member 162. FIG. 23 is a cross-sectional view of charging device 101 shown in FIG. 22 as viewed from section line S155-S155. As shown in FIG. 23, when the rubber roller holder is at the center of the saw tooth holding member 162, the tip of the saw tooth 53 is in contact with the center of the cleaning rubber roller 66 shaft on the outer peripheral surface of the cleaning rubber roller 66. This is because the rubber roller holding member 102 moves along the arrangement direction of the saw teeth 53, but the central axis 191 and the arrangement direction of the saw teeth 53 are not parallel. While the cleaning member holding body 194 moves to the center in the longitudinal direction of the saw tooth holding member 162, on the outer peripheral surface of the cleaning rubber roller 66, the end of the cleaning rubber roller 66 on the side of the first rotating roller 67a extends to the center of the cleaning rubber roller 66 shaft. The position in contact with the tip of the tooth 53 moves.

  FIG. 24 is a bottom view showing a state in which the cleaning member holder 194 has moved to the end of the saw-tooth holding member 162. FIG. 25 is a cross-sectional view of the charging device 101 shown in FIG. 24 as seen from the cutting plane line S157-S157. As shown in FIG. 25, when the cleaning member holding body 194 is present at one end of the saw-tooth holding member 162, the tip of the saw-tooth 53 is in contact with the end of the cleaning rubber roller 66 on the second rotating roller 67b side. This is because the cleaning member holder 194 moves along the arrangement direction of the saw teeth 53, but the central axis 191 and the arrangement direction of the saw teeth 53 are not parallel. While the cleaning member holding body 194 moves to the end of the saw-tooth holding member 162, the saw-tooth 53 of the cleaning rubber roller 66 from the center of the cleaning rubber roller 66 shaft to the end of the cleaning rubber roller 66 on the second rotating roller 67b side. The position in contact with the tip moves. That is, the entire outer peripheral surface of the cleaning rubber roller 66 is surely in contact with the tip of the saw tooth 53. Therefore, it is possible to provide a charging device 101 that can maintain a stable cleaning property of the needle electrode 163 and can provide uniform charging without uneven discharge over a long period of time. Further, since it is possible to prevent only a part of the cleaning rubber roller 66 from being kept in contact with the saw tooth 53 at the time of cleaning, the life of the cleaning rubber roller 66 and the saw tooth 53 can be extended.

(3) Control by Control Unit A control method using the image forming apparatus of the present invention as described above will be described with reference to FIG. FIG. 26 is a flowchart showing a control method for adjusting the charged potential on the surface of the photosensitive member after the sawtooth cleaning.

  The control shown in this flowchart is performed, for example, when a sawtooth stain is detected during image printing or immediately after printing is completed. The sawtooth charging current applied to the sawtooth in the printing operation prior to this control is called the initial charging current, and the voltage applied to the grid electrode is called the initial grid bias. In the printing operation before this control is performed, the charged potential on the surface of the photoconductor is adjusted to be a predetermined charged potential. The predetermined charging potential (hereinafter also referred to as “predetermined potential”) is a value that is set with a certain width from a set value that is a predetermined charging potential on the surface of the photoreceptor. The set value and the predetermined potential are not particularly limited as long as they can form a high-quality image, but in the present embodiment, the set value is −620 V, and the predetermined potential is −615 V or more and −625 V or less.

  In step S1, the needle electrode is cleaned. If the saw teeth are contaminated, the discharge from the saw teeth will vary, which may cause uneven charging on the surface of the photoconductor, resulting in poor printing, but the contaminants that have adhered to the saw teeth by regular cleaning As well as discharge products such as ozone and nitrogen oxides. However, when cleaning is performed, the discharge from the saw teeth changes due to the absence of the influence of contaminants and discharge products, and the charged potential on the surface of the photoreceptor changes. Therefore, the control means adjusts the charging potential on the surface of the photosensitive member to a predetermined potential in the following steps.

  After cleaning the needle electrode, the surface of the photoreceptor is charged in step S2, and the charged potential on the surface of the photoreceptor is measured in step S3.

  In step S4, it is determined whether the measured charging potential is a predetermined potential. If the measured charging potential is a predetermined potential, this control is terminated. For example, when printing is interrupted and this control is started, the surface of the photosensitive member is exposed and printing is resumed. If this control is started, the image forming apparatus is stopped. If the measured charging potential is not the predetermined potential, the process proceeds to step S4a.

  In step S4a, it is determined whether the measured charging potential is lower than a predetermined potential. If it is lower than the predetermined potential, the process proceeds to step S5. If it is not lower than the predetermined potential, that is, higher than the predetermined potential, the process proceeds to step S13.

  In step S5, the grid bias applied by the voltage application unit is raised above the initial grid bias. In the present embodiment, the grid bias is increased only once, but the same increase width as that in a case where the grid bias is increased may be divided into a plurality of times. Thereafter, the surface of the photoreceptor is charged in step S6, and the charged potential on the surface of the photoreceptor is measured in step S7. The charging potential at this time is higher than the charging potential measured in step S4.

  In step S8, it is determined whether the charging potential measured in step S7 is a predetermined potential. If it is a predetermined potential, this control is terminated. The subsequent image forming operation is performed with the corrected grid bias value. If not, the process proceeds to step S9.

  In step S9, the current applied to the saw tooth is increased from the initial charging current. In step S10, the surface of the photoconductor is charged, and in step S11, the charged potential of the surface of the photoconductor is measured.

  In step S12, it is determined whether the measured charging potential is a predetermined potential. If it is a predetermined potential, this control is terminated. The subsequent image forming operation is performed using the corrected grid bias and charging current value. If it is not a predetermined electric potential, it will return to step S9 and will raise the electric current applied to a saw-tooth further from the present electric current value. The operation of steps S9 to S12 is repeated until it is determined in step S12 that the charging potential is a predetermined potential. When the charging potential becomes a predetermined potential, this control is terminated.

  In step S4a, when the measured charging potential is not lower than the predetermined potential, that is, when it is higher than the predetermined potential, the process proceeds to step S13, and the current applied to the saw tooth is lowered from the initial charging current. Thereafter, the surface of the photoreceptor is charged in step S14, and the charged potential on the surface of the photoreceptor is measured in step S15.

  In step S16, it is determined whether the measured charging potential is a predetermined potential. If it is a predetermined potential, this control is terminated. Subsequent image forming operations are performed using the corrected charging current value. If it is not the predetermined potential, the process returns to step S13, and the operations of steps S13 to S16 are repeated until it is determined in step S16 that the charging potential is the predetermined potential. Become.

  As described above, as a control operation of the image forming apparatus of the present invention, after cleaning the needle electrode with the cleaning member, the surface of the photosensitive member is charged with the cleaned needle electrode, and the charged potential is detected with the potential detecting means. The detected charging potential is compared with a preset value which is a predetermined charging potential on the surface of the photoreceptor, and the control unit selects and executes the following first to fourth control operations based on the result. In the first control operation through steps S4 to S8, the voltage value applied to the grid electrode by the voltage application unit is adjusted so that the charged potential on the surface of the photoconductor becomes the set value. In the second control operation through steps S4 to S12, after the voltage value applied to the grid electrode by the voltage application unit is changed, the current application unit applies a sawtooth to the sawtooth potential so that the charged potential on the surface of the photosensitive member becomes the set value. The applied current value is adjusted. In the third control operation through steps S4 to S16, the current value applied to the saw tooth by the current application unit is adjusted so that the charged potential on the surface of the photosensitive member becomes the set value. In the fourth control operation through step S4, the voltage value and the current value are not changed.

  By selecting and executing these control actions, contaminants attached to the tip of the sawtooth, and discharge products such as ozone and nitrogen oxides can be cleaned, and the influence of the contaminant and discharge product on the sawtooth. Since the charging potential on the surface of the image bearing member can be controlled to be a set value in a state where there is no discharge, it is possible to realize a stable saw-tooth photoconductor charging performance without uneven discharge. In addition, since the current applied to the saw teeth can be kept to a minimum and the generation of discharge products can be suppressed, the deterioration of the saw teeth and the adhesion of the discharge products at the tips of the saw teeth can be suppressed. Therefore, the frequency of cleaning can be reduced, and a high-quality image can be stably formed over a long period of time. In addition, by suppressing the degradation of saw teeth accompanying an increase in the discharge amount, and adhesion of volatile components added to the toner and dust floating in the image forming apparatus, particularly silica, which is an external additive of the toner, Longer life of the charging device can be realized.

(About steps S5-12)
In step S4a, when the charged potential Vo on the surface of the photosensitive member becomes lower than a predetermined potential, for example, when the sawtooth is deteriorated due to discharge, contaminants attached to the sawtooth even if cleaning is performed in step S1. Examples include a case where the photosensitive layer cannot be completely removed, and a case where the photosensitive layer of the photosensitive member is thinned by friction with the cleaning blade 51 included in the cleaner unit 16 in the life, and the photosensitive layer becomes thin.

  FIG. 27 is a graph showing the relationship between the sawtooth charging current and the charging potential Vo on the surface of the photosensitive member due to the difference in the thickness of the photosensitive layer when the grid bias Vg is fixed to -620V. In this graph, the case where the thickness of the photosensitive layer (hereinafter also referred to as “photoconductor film thickness” or “film thickness”) is 25 μm, 21 μm, and 18 μm is shown. The photosensitive member film thickness of 25 μm is the thickness at the initial stage when the photosensitive member is used for image formation, and the photosensitive member film thickness of 18 μm is the thickness of the photosensitive layer in the life of the photosensitive member after printing 150K sheets. is there. The thickness of the photosensitive layer is calculated from the number of rotations of the photoreceptor. A lot of data on the number of rotations of the photosensitive member and the photosensitive layer thickness at that number of rotations are accumulated in advance to find the relationship between them, and the data created based on the found relationship is used as a correction table in advance. By registering in the program and counting the number of rotations of the photosensitive member with an actual machine, the thickness of the photosensitive layer for a certain number of printed sheets is calculated. Since the photosensitive layer is scraped little by little by the cleaning blade every time the photosensitive member rotates, the thickness of the photosensitive layer decreases from the initial stage to the life of the photosensitive member. The grid bias Vg was fixed to -620 V, the sawtooth charging current was changed, and the charging potential Vo on the surface of the photoreceptor at that time was measured.

  From FIG. 27, it can be seen that the thicker the film thickness, the larger the charging potential Vo on the surface of the photosensitive member when the sawtooth charging current value is the same. It can also be seen that as the film thickness increases, the amount of decrease in the charging potential Vo on the surface of the photoreceptor decreases with respect to the decrease in the charging current value of the sawtooth. Specifically, when the film thickness is 25 μm, the charging potential Vo on the surface of the photoreceptor is maintained at −620 V while the charging current of the sawtooth is −350 to −700 μA, and the charging potential Vo is set to −620 V. The minimum value of the charging current required to achieve this (hereinafter referred to as “minimum required value”) is −350 μA, but when the film thickness is reduced to 21 μm, a charging current of about −460 μA or more is applied to the saw tooth. Otherwise, the charging potential Vo will not be -620V. When the film thickness is further reduced to 18 μm, the charging potential Vo cannot be −620 V even if the sawtooth charging current is −700 μA.

  For the creation of this graph and the graphs shown in FIGS. 28 to 30 below, an image forming apparatus (manufactured by Sharp Corporation) whose product name is full-color machine MX4501 was used. From the initial stage to the end of the life, the real shot aging is carried out with 5 multi-sheets, and the needle electrodes are cleaned every 1000 printed sheets. EPDM (hardness: JIS A90) is used for the cleaning rubber roller, the outer diameter is 6 mm, the length in the axial direction is 4 mm, and the inner diameter of the elastic layer is 3 mm. Even when an image forming apparatus other than this image forming apparatus is used, the same tendency as in FIGS.

  Here, a conventional control method will be described. Conventionally, there is a method of recording the number of rotations of a photoreceptor in an image forming apparatus that does not have a surface electrometer, and correcting the grid bias Vg based on the data to make the charged potential Vo on the surface of the photoreceptor constant. . In this method, in order to reduce the grid bias Vg correction amount and the difference between the predetermined potential and the actual charging potential Vo as much as possible, the sawtooth charging current value is set at the initial stage of the photoconductor having a film thickness of 25 μm. The minimum required value is set to −350 μA, and is increased to −700 μA throughout the life of the photoreceptor.

  FIG. 28 is a graph showing the relationship between the grid bias Vg and the charging potential Vo on the surface of the photoreceptor when the sawtooth charging current value is fixed at −700 μA. When the charging current is fixed at −700 μA in the life of the photosensitive member whose film thickness is reduced to 18 μm, the relationship between the grid bias Vg and the charging potential Vo on the surface of the photosensitive member becomes as shown in FIG. It can be seen that even when the bias value is the same, the charging potential Vo on the surface of the photoreceptor decreases. This tendency becomes more prominent as the grid bias value increases.

  As shown in FIG. 28, by fixing the sawtooth charging current value to −700 μA and raising the grid bias value from −620 V to −645 V, a predetermined potential of −620 V is obtained. The charging potential Vo can be maintained at a predetermined potential by such a method. However, since the generation amount of discharge products such as ozone and nitrogen oxide increases as the current value applied to the saw tooth increases, In the control method, the adhesion of the discharge product to the saw-tooth is accelerated in the life.

  A conventional control method different from the above-described control method will be described with reference to FIG. In this control, the charging current of the saw tooth is fixed at −700 μA from the initial stage over the life. The number of rotations of the photosensitive member is recorded, and the applied voltage of the grid bias Vg is corrected based on the result of the correction table and process control corresponding to the film thickness reduction of the photosensitive layer. Specifically, in the initial stage when the film thickness is 25 μm, the grid bias Vg is set to −620 V, and gradually increases over the life, and in the life where the film thickness decreases to 18 μm, the grid bias Vg is set to −645 V. As a result, the charging potential Vo on the surface of the photoreceptor is kept at -620V. However, in this control method, since the current applied to the saw tooth is high from the beginning and the amount of discharge products such as ozone and nitrogen oxides is large, the adhesion of the discharge product to the saw tooth cannot be suppressed.

  The description returns to the control method of the present invention. FIG. 29 is a graph showing the relationship between the grid bias Vg due to the difference in the thickness of the photosensitive layer and the charging potential Vo on the surface of the photosensitive member when the sawtooth charging current value is fixed at −350 μA. In the initial stage where the film thickness is 25 μm, as shown in FIG. 29, by setting the initial charging current to −350 μA and the initial grid bias Vg to −620 V, −620 V is obtained as the charging potential Vo on the surface of the photoreceptor. .

  In this embodiment, the initial charging current before the first control is performed at the initial stage of the photosensitive member is set according to the thickness of the photosensitive layer included in the image carrier at that time. As can be seen from FIG. 27, even when the same current value is applied to the saw-tooth, the charged potential on the surface of the image carrier varies depending on the thickness of the photosensitive layer. The smaller the current applied to the saw tooth, the smaller the amount of discharge product generated. Therefore, in this embodiment in which the initial photoreceptor film thickness is 25 μm and the predetermined potential is set to −620 V, the initial charging current is − By setting it to 350 μA, the current applied to the saw-tooth can be surely kept to a minimum.

  Returning to FIG. 29, at the time of printing 85K sheets when the film thickness is reduced to 21 μm, the charged potential Vo on the surface of the photoreceptor after cleaning is −605 V when monitored by a surface electrometer as a potential detecting means. The shortage of the surface potential Vo in this case can be adjusted to the same surface potential Vo of −620V as in the initial stage by increasing the grid bias Vg to −640V. As described above, when the difference between the surface potential Vo in the life and the predetermined value is relatively small, the desired charging potential Vo can be obtained only by controlling the grid bias Vg shown in steps S1 to S8 in FIG. . This control method corresponds to the first control operation.

  As shown in steps S5 to S12 in FIG. 26, correction is performed to increase the grid bias Vg, and when the predetermined potential is not reached, only the difference between the charging potential Vo on the surface of the photosensitive member and the predetermined charging potential is sawtooth. Increase the charging current applied to.

  FIG. 30 is a graph showing the relationship between the grid bias Vg and the charging potential on the surface of the photosensitive member according to the photosensitive member film thickness and the charging current value applied to the saw-tooth. In the initial stage when the film thickness is 25 μm, by setting the grid vise Vg to −620 V and the sawtooth charging current to −350 μA, −620 V is obtained as the charging potential Vo on the surface of the photoreceptor.

  When the film thickness is reduced to 18 μm in the life after printing 150K sheets, the charging potential Vo decreases to about −580 V at the grid bias Vg−620 V when the sawtooth charging current is −350 μA. At this time, even if the grid bias Vg is raised to -700 V, the charging potential Vo is -600 V, does not reach the predetermined potential of -620 V, and cannot be dealt with only by correcting the grid bias value. Therefore, in the life in which the film thickness is 18 μm and the grid bias Vg is increased to −700 V, the charging potential Vo can be adjusted to −620 V by increasing the sawtooth charging current to −450 μA. In the present embodiment, the operations in steps S9 to S12 are repeated four times, and the charging current is increased by -25 μA each time. By increasing the charging current within −25 μA at a time, the current flowing into the grid electrode (loss current) can be reduced and a predetermined charging potential can be obtained. Since the grid bias Vg in steps S9 to S12 is not too high as -700 V, even if the charging current value to be increased once is set to a value much higher than -25 μA, the grid bias Vg is applied to the grid electrode accordingly. Only the loss current increases, and the charging potential Vo on the surface of the photoreceptor does not exceed the predetermined charging potential of −615 V or more and −625 V or less. This control method corresponds to the second control operation, and even when the difference between the charged potential on the surface of the image carrier and the set value after increasing the voltage value is relatively large, the current applied to the saw tooth is minimized. It is possible to suppress the deterioration of the sawtooth and the adhesion of the discharge product at the tip of the sawtooth.

  By such a control method, a predetermined potential Vo-620V can be obtained with a minimum charging current throughout the life. With this control, there is no effect on the image due to defective discharge, and the amount of ozone generated can be reduced by 50% in the initial stage compared to the case where the charging current value is fixed to -700 μA from the beginning, and 35% can be reduced throughout the life. Can do. Since the amount of ozone generated is proportional to the charging current value, these ratios are -350 μA, which is the initial charging current value with respect to -700 μA, and -450 μA, which is the charging current value in life with respect to -700 μA. Calculated from the ratio. By suppressing the generation of ozone, damage to other parts such as the photosensitive member, the grid electrode, and further the cleaning blade can be suppressed, so that the life of the member can be extended.

(About steps S13-16)
In step S4a, a factor causing the charged potential Vo on the surface of the photoreceptor to be higher than a predetermined potential is, for example, a change in humidity. Specifically, when the image forming apparatus is left without being used for a long period of time, if the left period is from summer to autumn, the environment in the charge potential control correction of the image forming apparatus is under high temperature and high humidity ( The temperature changes from room temperature 30 ° C. and humidity 85%) to room temperature and normal humidity (air temperature 22 ° C., humidity 55%). In such a case, the influence of humidity is reduced, the resistance of the surface of the photoreceptor is increased, and the loss of charge on the surface of the photoreceptor due to the flow of charge into the aluminum tube that is the photoreceptor support base is reduced. The chargeability of the photoreceptor is improved, and the charging potential Vo measured after cleaning is increased.

  In the present embodiment, the charging current value is decreased within a range of −25 μA or less per operation of Steps S9 to S12. If the amount of change in charging current at one time is within −25 μA, the charging potential Vo on the surface of the photoconductor does not become smaller than the predetermined charging potential ranging from −615 V to −625 V.

  When the detected charging potential is higher than the set value by the control means, by selecting and executing the third control operation, the current applied to the saw tooth can be reduced, and the generation of discharge products can be reduced. Deterioration of the sawtooth and adhesion of discharge products at the tip of the sawtooth can be suppressed. Therefore, the frequency of cleaning can be reduced, and a high-quality image can be stably formed over a long period of time. This control method corresponds to the third control operation.

  The operating frequency, material, and set value of the cleaning rubber roller can be arbitrarily set for each image forming apparatus.

  As described above, when the charging potential Vo on the surface of the photoreceptor is increased, the grid bias is first increased. If the charging potential Vo on the surface of the photoconductor does not reach a predetermined charging potential even if the grid bias is increased, the sawtooth charging current is increased. When the charging potential Vo on the surface of the photoreceptor is lowered, the value of the grid bias is not changed, and the sawtooth charging current is lowered. The generation of discharge products can be reduced by controlling the sawtooth charging current as low as possible.

2. Program and Recording Medium The control unit of the image forming apparatus 100 according to the first embodiment of the present invention may be configured by hardware logic, or realized by software using a CPU as follows. Also good. When the control means is realized by software using a CPU, the control means is a CPU (Central Processing CPU) that executes instructions of a control program for realizing each function.
Unit), a ROM (Read Only Memory) storing the program, a RAM (Random Access Memory) expanding the program, and a storage device (recording medium) such as a memory storing the program and various data.

  A recording medium in which a program code (execution format program, intermediate code program, source program) of a fixing control program of a fixing device, which is software that realizes the above-described function, is recorded in a computer-readable manner is supplied to the control unit of the fixing device. Then, the computer (or CPU or MPU) reads out and executes the program code recorded on the recording medium, whereby a fixing device that can prevent the surface of the fixing roller from being damaged can be realized.

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The image forming apparatus may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication network. Etc. are available.

  Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  As described above, the control program is a program for operating the image forming apparatus 100 of the present invention, and causes the computer to function as the control unit. Therefore, the potential of the image carrier surface detected by the potential detection unit and the set value are detected. The control means can read and execute a method of controlling the charged potential on the surface of the image carrier by the voltage applied to the grid electrode and the current applied to the saw tooth. Can be a thing.

  Further, since the control program is recorded on the recording medium and can be read by a computer, the voltage applied to the grid electrode by comparing the set potential with the potential of the surface of the image carrier detected by the potential detecting means, A program for controlling the charging potential on the surface of the image carrier by the current applied to the teeth can be easily supplied to the computer.

3 moving means 53 saw tooth 66 cleaning rubber roller 301 first charging device 302 rubber roller holder 306 base portion 307 holding portion 308 base surface 362 saw tooth holding member 362a existing portion 362b non-existing portion 363 needle electrode 394 cleaning member holder

Claims (12)

An image carrier including a cylindrical substrate and a photosensitive layer formed on the surface of the substrate;
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A base portion having a base surface that holds the saw tooth perpendicular to the saw tooth, and a saw tooth holding member that holds the needle electrode in a holding portion that holds the saw tooth parallel to the saw tooth;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
Moving means for moving the cleaning member holder along the arrangement direction of the saw teeth;
After cleaning the needle electrode with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential is compared with a preset value that is a predetermined charged potential on the surface of the image carrier. And based on the results
(1) a first control operation of adjusting a voltage value applied to the grid electrode by the voltage applying means so that the charged potential on the surface of the image carrier becomes the set value;
(2) After changing the voltage value applied to the grid electrode by the voltage application means, the current value applied to the saw tooth by the current application means is adjusted so that the charged potential on the surface of the image carrier becomes the set value. Second control operation,
(3) a third control operation for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value;
(4) a fourth control operation that does not change the voltage value and the current value;
An image forming apparatus comprising: control means for selecting and executing any one of the control operations.   The image forming apparatus according to claim 1, wherein the control unit selects and executes a first control operation or a second control operation when the detected charging potential is lower than a set value.   In the second control operation, the voltage applied to the grid electrode is increased by the voltage applying means, and then the surface of the image carrier is charged. If the charged potential of the surface of the image carrier at this time is lower than the set value, the current is applied. The image forming apparatus according to claim 2, wherein a current value applied to the saw tooth is adjusted by the means.   The image forming apparatus according to claim 1, wherein the control unit selects and executes a third control operation when the detected charging potential is higher than a set value. An image carrier including a cylindrical substrate and a photosensitive layer formed on the surface of the substrate;
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A base portion having a base surface that holds the saw tooth perpendicular to the saw tooth, and a saw tooth holding member that holds the needle electrode in a holding portion that holds the saw tooth parallel to the saw tooth;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
Moving means for moving the cleaning member holder along the arrangement direction of the saw teeth;
After cleaning the needle electrode with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential is compared with a preset value that is a predetermined charged potential on the surface of the image carrier. And based on the results
After changing the voltage value applied to the grid electrode by the voltage applying means, the surface of the image carrier is charged. If the charged potential of the image carrier surface at this time is lower than the set value, the charged potential of the surface of the image carrier is An image forming apparatus comprising: a control unit that adjusts a current value applied to the saw tooth by the current applying unit so as to be the set value.   6. The current value before cleaning applied to the saw tooth by the current applying means is set in accordance with the thickness of the photosensitive layer included in the image carrier at that time. The image forming apparatus according to one. The cleaning member holding body includes a pressure contact piece that presses the cleaning member against one end of the cleaning member holding body, and the base surface according to the shape of the base portion according to the movement along the arrangement direction of the sawtooth by the moving member. In parallel to the sawtooth and in a direction perpendicular to the sawtooth arrangement direction,
The image forming apparatus according to claim 1, wherein the base portion is curved in a direction parallel to the base surface. The moving means moves the cleaning member holding body along the screw shaft by rotation of a screw shaft provided in the longitudinal direction of the base portion, and the cleaning member holding body changes to the shape of the base portion along with the movement. Accordingly, it moves in a direction parallel to the base surface and perpendicular to the arrangement direction of the saw teeth,
The base part has a certain width,
The plurality of saw teeth are arranged parallel to the screw axis and non-parallel to the central axis in the longitudinal direction of the base surface. Image forming apparatus. The moving means includes a screw shaft provided over the longitudinal direction of the base portion, and the cleaning member holder is moved along the screw shaft by rotation thereof.
The screw axis and the central axis in the longitudinal direction of the base surface are parallel,
The image forming apparatus according to claim 1, wherein the plurality of saw teeth are arranged non-parallel to the central axis and the screw axis. An image carrier including a cylindrical substrate and a photosensitive layer formed on the surface of the substrate;
A potential detecting means for detecting a charged potential on the surface of the image carrier;
A needle electrode in which a plurality of saw teeth are arranged in one direction;
A current applying means for applying a current to the saw tooth and discharging the image carrier;
A grid electrode provided between the needle electrode and the image carrier to control the charging potential on the surface of the image carrier;
Voltage applying means for applying a voltage to the grid electrode;
A cleaning member that is arranged so as to move along the arrangement direction of the saw teeth, and that cleans the needle electrode by sequentially contacting the tips of the plurality of saw teeth during the movement;
A cleaning member holder for supporting the cleaning member;
In an image forming apparatus including a moving unit that moves the cleaning member holder along the arrangement direction of the saw teeth,
After cleaning the tip of the saw tooth with the cleaning member, the charged potential on the surface of the image carrier is detected by the potential detecting means, and the detected charged potential and a predetermined set value which is the charged potential on the surface of the image carrier are obtained. Compare and based on the result of the comparison,
(1) a first control operation of adjusting a voltage value applied to the grid electrode by the voltage applying means so that the charged potential on the surface of the image carrier becomes the set value;
(2) After changing the voltage value applied to the grid electrode by the voltage application means, the current value applied to the saw tooth by the current application means is adjusted so that the charged potential on the surface of the image carrier becomes the set value. Second control operation,
(3) a third control operation for adjusting the current value applied to the saw tooth by the current applying means so that the charged potential on the surface of the image carrier becomes the set value;
(4) Do not change the voltage and current values,
A control method for an image forming apparatus, wherein one of the control operations is selected and executed.   A program for operating the image forming apparatus according to any one of claims 1 to 9, wherein the program causes a computer to function as the control unit.   A computer-readable recording medium on which the control program according to claim 11 is recorded.

Images