JP4610371B2 - Charger and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a charger used in an electrophotographic image forming apparatus represented by a copying machine or a printer. The present invention also relates to an image forming apparatus equipped with this charger.

  In an electrophotographic image forming apparatus typified by a copying machine or a printer, the surface of an image carrier is charged by a charger, and an electrostatic latent image of an original image is formed by partially attenuating the potential by light irradiation. Then, a visible toner image obtained by developing the electrostatic latent image with toner is transferred to a sheet. After the toner image is transferred, the remaining toner on the surface of the image carrier is cleaned by a cleaning device, and the charge is removed in preparation for forming a new electrostatic latent image.

  The charger for charging the surface of the image carrier includes a non-contact type using corona discharge and a contact type for contacting a brush, a roller, and the like. Among them, a scorotron charger using corona discharge is widely known. The scorotron charger includes a charge wire that is a discharge member and a grid that controls a discharge state. The charger is arranged so that the grid is positioned in the vicinity of the surface of the image carrier, and the image carrier surface is charged by applying a predetermined voltage to these discharge members.

In order to maintain the charged potential on the surface of the image carrier in a suitable state, it is necessary to clean the discharge members such as charge wires and grids. If these members are contaminated by toner, discharge products, etc., the corona discharge is adversely affected, and the surface potential of the image carrier is disturbed. For example, when the surface potential is uneven, the image density is also uneven. Furthermore, the contamination of the discharge member also has an adverse effect on the charger itself, which may lead to a shortened life of the charger. In order to solve such a problem, a charger including a cleaning member for cleaning a charge wire and a grid is proposed, and examples thereof can be seen in Patent Documents 1 and 2.
JP-A-8-62950 (page 4-7, FIG. 2) JP-A-9-73214 (page 3-5, FIG. 1 and FIG. 4)

  Here, the distance between the grid of the charger and the surface of the image carrier is generally as narrow as about 0.5 mm. Accordingly, when cleaning the grid, the cleaning member is likely to come into contact with the image carrier and the surface thereof is damaged. Therefore, as a charger provided with a cleaning member for cleaning a discharge member such as a grid, a charger that is designed so that the cleaning member does not contact the surface of the image carrier is desired.

  The scorotron charger described in Patent Document 1 includes a grid cleaning member that moves in the grid installation direction to clean the grid, and adjusts the tension of the grid so that the cleaning member is passed between the grid and the image carrier. Means are provided to relieve the tension of the grid as the cleaning member moves and to push the grid away from the image carrier. However, the tension adjusting means that can relieve the tension of the grid in accordance with the movement of the cleaning member requires sufficient consideration for the shape and arrangement of the constituent members, and the structure becomes very complicated, which causes an increase in cost. Also, since the grid tension is weakened or strengthened every time it is cleaned, there is a risk that the grid will be deformed by repeated such tension tension, and the grid will not be able to maintain the necessary tension during discharge. is there.

  The image forming apparatus described in Patent Document 2 uses a solenoid so that the charging means (charger) can be separated from or brought close to the image carrier. However, since it is necessary to newly provide a moving mechanism of the charging means using a solenoid, the structure becomes very complicated and there is a concern about an increase in cost as in the above-mentioned Patent Document 1. Furthermore, since it is necessary to incorporate the control means of the moving mechanism in the image forming apparatus, there is a possibility that the cost will be greatly increased.

  The present invention has been made in view of the above points, and in a charger provided with a cleaning member for cleaning a discharge member, the surface of the image carrier is prevented from being damaged by a simple structure without using a complicated structure. It is an object of the present invention to provide a charger capable of easily cleaning a discharge member. It is another object of the present invention to provide an image forming apparatus equipped with such a charger.

  In order to solve the above-described problems, the present invention charges a surface of an image carrier using a discharge member. The main body and the discharge member are provided on the main body and moved in the installation direction of the discharge member. And a cleaning member for cleaning the main body, wherein the main body can take both positions of approaching and retreating with respect to the image carrier, and the change in position moves the cleaning member. It was decided to be done by means.

  Further, the position change of the main body is performed simultaneously with the movement of the cleaning member.

  In addition, the cam mechanism is provided with a cam that rotates with the movement of the cleaning member, and the main body is moved to the retracted position by engaging the cam with a support member that supports the main body. .

  In addition, the position of the main body is changed by rotational movement about one end of the discharge member in the installation direction.

  Further, it is provided with urging means for urging a portion of the main body where the cam mechanism is provided in a direction to approach the image carrier.

  Further, the position of the main body is changed by rotating around the one end of the discharge member in the erection direction, and moving the main body end that is the center of the rotational movement toward and away from the image carrier. It was decided to be made.

  Further, the moving means includes a guide rail that engages with the cleaning member and retracts the main body end from the image carrier as the cleaning member moves away from the main body end serving as the center of the rotational movement. .

  In addition, a biasing means for biasing the end of the main body, which is the center of the rotational movement, in a direction in which it is retracted from the image carrier is provided.

  In the present invention, the charger is mounted on the image forming apparatus.

  According to the configuration of the present invention, the main body of the charger can take both the approaching and retreating positions with respect to the image carrier, and the position change is performed by a moving unit that moves the cleaning member. Therefore, it is not necessary to separately provide a means for moving the main body away from or approaching the image carrier. As a result, the charger can be retracted from the image bearing member with a simple structure with reduced cost without using a complicated structure. Therefore, it is possible to easily clean the discharge member while preventing damage to the surface of the image carrier. By reliably cleaning the discharge member, it is possible to realize high-quality image formation and long life of the charger.

  Further, in the charger having the above configuration, the position change of the main body is performed simultaneously with the movement of the cleaning member, so that the cleaning time can be shortened. Further, since a mechanism for separately changing the position of the main body and moving the cleaning member is not required, the structure can be further simplified and the increase in the cost of the charger can be suppressed.

  In addition, the charger having the above structure includes a cam mechanism provided with a cam that rotates with the movement of the cleaning member, and the cam is engaged with a support member that supports the main body, thereby moving the main body to the retracted position. Therefore, by using the cam mechanism, the force for moving the cleaning member in the direction in which the discharge member is installed can be used to retract the charger from the image carrier. Therefore, the charger can be easily retracted from the image carrier.

  Further, in the charger having the above configuration, the position of the main body is changed by a rotational movement around one end of the discharge member in the erection direction. Therefore, for example, using a functional member such as a solenoid, the image carrier There is no need for a complicated structure for sliding the charger body in a direction perpendicular to the axis. Therefore, the charger can be moved closer to and away from the image carrier by a simple mechanism of rotating around a predetermined fulcrum.

  Further, in the charger configured as described above, since the biasing means for biasing the portion of the main body provided with the cam mechanism in the direction of approaching the image carrier is provided, the charger retracted from the image carrier. Can be easily moved to the approach position, and can be accurately moved to a predetermined place to be located at the time of discharge. As a result, even if the charger main body is moved for cleaning the discharge member, when the image carrier is charged in the image forming operation, the main body is located at a predetermined position. Does not adversely affect properties.

  Further, in the charger having the above configuration, the position of the main body can be changed by rotating the discharge member around one end in the installation direction, and approaching and retracting the end of the main body, which is the center of the rotational movement, from the image carrier Therefore, the entire main body of the charger can be retracted from the image carrier. As a result, it is possible to prevent damage to the surface of the image carrier at the time of cleaning of the discharge member, and also to reliably clean the entire discharge member at the center of the rotational movement.

  Further, in the charger having the above configuration, the cleaning member moving means engages with the cleaning member, and retracts the main body end from the image carrier as the cleaning member moves away from the main body end serving as the center of the rotational movement. Since the guide rail is provided, there is no need to separately provide a means for moving the main body end, which is the center of the rotational movement, away from or close to the image carrier. As a result, the entire charger can be retracted from the image carrier with a simple structure that is reduced in cost without using a complicated structure.

  Further, in the charger configured as described above, since the main body end that is the center of the rotational movement is provided with an urging means that urges the main body end in the direction in which it is retracted from the image carrier, It is possible to easily retract the main body end from the image carrier. As a result, the entire charging device can be reliably retracted from the image carrier, so that safety against damage to the surface of the image carrier during cleaning of the discharge member is further enhanced.

  In the present invention, since the charger is mounted on the image forming apparatus, the discharge member can be easily cleaned by preventing damage to the surface of the image carrier with a simple structure without using a complicated structure. Thus, a high-performance image forming apparatus capable of achieving the above can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with a charger according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic vertical sectional front view showing an image forming apparatus. Note that solid line arrows in the figure indicate the sheet conveyance path and conveyance direction, and alternate long and short dash line arrows indicate the laser beam L.

  As shown in FIG. 1, a paper feeding unit 2 is disposed at the lower part of the image forming apparatus 1. Inside the sheet feeding unit 2, sheets P such as cut paper before printing are stacked and accommodated, and the sheets P are separated and sent out one by one.

  A paper transport unit 3 is provided inside the image forming apparatus 1 and on the left side of the paper feed unit 2. The paper P sent out from the paper supply unit 2 is conveyed vertically upward along the side surface of the image forming apparatus 1 by the paper conveyance unit 3 and reaches a transfer unit 30 described later.

  On the other hand, a document feeding unit 4 is provided on the upper surface of the image forming apparatus 1, and a document image reading unit 5 is provided below it. When a user copies a document, a document on which an image such as a character, a figure, or a pattern is drawn is stacked on the document feeding unit 4. The document feeding unit 4 separates the documents one by one and sends the document, and the document image reading unit 5 reads the image data. The information of the image data is sent to the laser irradiation unit 6 disposed above the paper feeding unit 2 and in the center of the image forming apparatus 1. The laser beam L controlled based on the image data is irradiated by the laser irradiation unit 6 toward the image forming unit 20 described later.

  An image forming unit 20 and a transfer unit 30 are provided above the paper transport unit 3 and to the left of the laser irradiation unit 6. In the image forming unit 20, an electrostatic latent image of the document image is created by the laser light L irradiated by the laser irradiation unit 6. A toner image is formed from the electrostatic latent image, and the toner image is transferred by the transfer unit 30 to the pre-printing paper P sent in synchronization by the paper transport unit 3.

  A fixing unit 7 is provided above the transfer unit 30. The paper P carrying the unfixed toner image in the transfer unit 30 is sent to the fixing unit 7 where the toner image is heated and melted by the heat roller and fixed.

  A branch portion 8 is provided above the fixing portion 7. The paper P discharged from the fixing unit 7 is discharged from the branching unit 8 to a paper discharge tray 9 provided in the cylinder of the image forming apparatus 1 when double-sided printing is not performed.

  The discharge port portion from which the paper P is discharged from the branch portion 8 toward the paper discharge tray 9 functions as the switchback portion 10. When performing duplex printing, the switchback unit 10 switches the conveyance direction of the paper P discharged from the fixing unit 7. Then, the paper P is sent downward through the left side of the fixing unit 7 and the left side of the transfer unit 30, and is sent again to the transfer unit 30 through the paper transport unit 3.

  Next, a detailed configuration around the image forming unit 20 of the image forming apparatus 1 will be described with reference to FIG. FIG. 2 is a schematic vertical sectional partial enlarged view showing the periphery of the image forming unit. The structure around the image forming unit 20 depicted in FIG. 2 is the same as that depicted in FIG. 1 redrawn so that the paper transport direction is horizontal, and can be omitted in describing the content of the invention. Drawing is omitted for such parts.

  As shown in FIG. 2, the image forming unit 20 includes a photosensitive drum 21 as an image carrier at the center thereof. In the vicinity of the photosensitive drum 21, a charger 40, a developing device 50, a cleaning device 60, and a charge removal device 70 are disposed in order along the rotation direction. The transfer unit 30 is provided between the developing device 50 and the cleaning device 60 along the rotation direction of the photosensitive drum 21.

  The photosensitive drum 21 includes a conductive roller-like base 22 made of aluminum or the like, and a photosensitive layer 23 provided on the outside thereof. The photosensitive layer 23 is provided with amorphous silicon, which is an inorganic photoconductive material, by vacuum deposition or the like. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is the same as the paper conveyance speed (for example, 175 mm / sec).

  The charger 40 is a scorotron charging device using a corona discharge charger. The charger 40 includes a metal shield case 41 that is a charger body. The shield case 41 has a bowl shape with an opening facing the photosensitive drum 21. The shield case 41 is provided with a charge wire 42 that is a discharge member made of tungsten, stainless steel, or the like, and a grid 43. The charge wire 42 is installed inside the shield case 41, and the grid 43 is installed on the surface of the opening of the shield case 41 along the axial direction of the photosensitive drum 21. The charger 40 uniformly charges the surface of the photosensitive drum 21 with a predetermined polarity and potential. The detailed configuration of the charger 40 will be described later.

  The developing device 50 is provided with a photosensitive member non-contact type developing roller 51 in the vicinity of the photosensitive drum 21. A bias having the same polarity as the charging polarity of the photosensitive drum 21 is applied to the developing roller 51. The developing roller 51 charges the toner, which is a developer, and causes it to fly to the electrostatic latent image on the surface of the photosensitive drum 21 to develop the electrostatic latent image. As the toner, a magnetic or non-magnetic one-component toner or a two-component toner obtained by mixing a magnetic carrier and an insulating toner is used. The developing roller may be a photoreceptor contact type.

  The transfer unit 30 is provided with a transfer roller 31 that contacts the photosensitive drum 21. The transfer roller 31 includes a cored bar 32 and a conductive elastic layer 33 provided outside the cored bar 32. The conductive elastic layer 33 is made of polyurethane rubber or the like in which a conductive material such as carbon is dispersed. The transfer roller 31 is in pressure contact with the photosensitive drum 21 to form a transfer nip portion through which the paper P is inserted. The transfer roller 31 is rotated by a driving device (not shown) so that the peripheral speed thereof is the same as the peripheral speed of the photosensitive drum 21. Further, a transfer bias is applied to the transfer roller 31 as necessary.

  The cleaning device 60 is disposed further downstream of the transfer nip portion along the rotation direction of the photosensitive drum 21. The cleaning device 60 includes a cleaning blade 61 that is a cleaning member, a housing 62, and a screw (not shown). The cleaning blade 61 has substantially the same axial length as the photosensitive drum 21 and is provided so as to contact the photosensitive drum 21. After the transfer, the cleaning blade 61 removes the toner remaining on the surface of the photosensitive drum 21 and cleans it. The toner removed from the surface of the photosensitive drum 21 is collected in the housing 62 and conveyed to the outside of the cleaning device 60 by a screw (not shown).

  The static eliminator 70 is composed of an LED (light emitting diode) 71 and irradiates the photosensitive drum 21 with light to neutralize the surface thereof. Instead of the LED 71, an EL (electroluminescence) light source, a fluorescent lamp, or the like can be used.

  Here, a series of operations of the image forming unit 20 and the transfer unit 30 will be described.

  First, in the charger 40, a predetermined voltage is applied to the charge wire 42 to generate corona discharge. Electrons generated by the corona discharge float in the air and travel toward the photosensitive drum 21. At this time, a voltage is applied to the grid 43 to control the amount of electrons. In this way, the charger 40 uniformly charges the surface of the photosensitive drum 21 with a predetermined polarity and potential. The charging potential at this time is usually about 200 to 1000V.

  Subsequently, based on the image data read by the document image reading unit 5 (see FIG. 1), the photosensitive drum 21 is irradiated with the laser light L controlled by the laser irradiation unit 6 (see FIG. 1), and the irradiated portion. The potential of the light is attenuated and an electrostatic latent image of the original image is formed. The toner charged by the developing device 50 is supplied to the surface of the photosensitive drum 21 by the developing roller 51, and a toner image is formed from the electrostatic latent image.

  On the other hand, the sheet P is synchronized with the toner image formation on the surface of the photosensitive drum 21 by the sheet conveying unit 3 (see FIG. 1), and is transferred to the transfer nip portion formed by the contact between the photosensitive drum 21 and the transfer roller 31. It is inserted. At this time, a negative transfer bias having a polarity opposite to that of the photosensitive drum 21 and the toner is applied to the transfer roller 31. As a result, the toner moves from the photosensitive drum 21 to the transfer roller 31, and the toner image is contact-transferred to the paper P.

  After the toner image is transferred, the toner remaining on the surface of the photosensitive drum 21 is removed by a cleaning blade 61 provided in the cleaning device 60 so as to be scraped off. The toner collected in the housing 62 is conveyed to the outside of the cleaning device 60 by a screw (not shown).

  After the toner on the surface of the photosensitive drum 21 is cleaned, the surface of the photosensitive drum 21 is neutralized by the static eliminator 70, thereby preparing for the next image forming operation.

  Next, a detailed configuration of the charger 40 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a left side view showing a state where the charger and the photosensitive drum are assembled. 4 is a perspective view of the charger, FIG. 5 is a partially enlarged perspective view, and FIG. 6 is a left side view of the charger with the shield case removed. FIG. 7 is a front view of a support member of the charger, and FIG. 8 is a perspective view of the same. 3 and 6, the right side is the front side of the image forming apparatus 1, and the left side is the back side.

  As shown in FIG. 3, the charger 40 is provided with a shield case 41, which is a main body thereof, so as to be substantially parallel to the axial direction of the photosensitive drum 21. The charger 40 is supported by two support members 11 provided in the image forming apparatus 1. In FIG. 3, only the support member 11 on the front side of the image forming apparatus 1 is drawn, and the support member 11 on the back side is not shown and is indicated by a two-dot chain line. In the assembled state of the charger 40 and the photosensitive drum 21, the gear case 44 of the charger 40 and the support member 11 on the front surface side of the image forming apparatus 1 are arranged close to each other (see FIG. 3). ). A spring 12, which is a biasing unit that biases the shield case 41 in a direction approaching the photosensitive drum 21, is provided at a place where the charger 40 is accommodated in the support member 11. The spring 12 is composed of a compression coil spring, but may be an elastic member such as a leaf spring, rubber, or sponge. The charger 40 can be pulled out to the front side of the support member 11, that is, to the right in FIG.

  As shown in FIGS. 4 and 5, synthetic resin insulating members 45 are provided at both ends of the bowl-shaped shield case 41. A charge wire 42 (see FIG. 2) is provided inside the shield case 41, and a grid 43 is provided between the two insulating members 45 in the opening. In the assembled state of the charger 40 and the photosensitive drum 21 shown in FIG. 3, the charger 40 is arranged with respect to the photosensitive drum 21 so that the distance between the grid 43 and the surface of the photosensitive drum 21 is 0.5 mm. Has been.

  As shown in FIG. 6, the shield case 41 includes a charge wire 42, a cleaning member 46 for the grid 43, and a screw rod 81. The screw rod 81 is passed between the insulating members 45 at both ends of the shield case 41 and passes through the support 46 a of the cleaning member 46. A thread groove is provided in the threaded portion 81 through portion of the support 46a, and the support 46a and the threaded rod 81 are engaged with each other by screws. A cleaning pad 46 b that contacts the charge wire 42 and the grid 43 is provided at the tip of the cleaning member 46. Therefore, by rotating the screw rod 81, the cleaning member 46 slides to the front side and the back side in the direction in which the charge wire 42 and the grid 43 are erected, and these can be cleaned. The cleaning member 46 does not rotate around the axis of the screw rod 81 when the screw rod 81 rotates.

  As shown in FIG. 4, a gear case 44 is provided at the front end of the shield case 41. Inside the gear case 44, a motor 82 for rotating a screw rod 81 (see FIG. 6) and a reduction gear 83 are provided. The reduction gear 83 is composed of a plurality of gear groups, and reduces the rotation of the motor 82 to a predetermined rotation and transmits it to the screw rod 81. The screw rod 81, the motor 82, and the reduction gear 83 constitute a moving unit 80 for the cleaning member 46.

  The charger 40 is supported by the image forming apparatus 1 by the support member 11 shown in FIGS. 7 and 8. 7 and 8, the position of the photosensitive drum 21 is indicated by a two-dot chain line in order to grasp the positional relationship between the charger 40 and the photosensitive drum 21. The support member 11 is provided with a square hole 13 into which the shield case 41 of the charger 40 is inserted. This square hole 13 is longer than the length of the shield case 41 in the radial direction of the photosensitive drum 21, that is, in the direction of approaching or retracting from the photosensitive drum 21. As a result, the shield case 41 can move in the retreating direction with respect to the photosensitive drum within the square hole 13, but as described above, the photosensitive drum 21 is driven by the spring 12 (see FIG. 3) that is a biasing means. It is urged in the direction approaching.

  As shown in FIGS. 3, 4, 7, and 8, a cam mechanism 90 is provided between the gear case 44 of the adjacent charger 40 and the support member 11. The cam mechanism 90 includes a cam 91, a cam gear 92, and a cam engagement protrusion 93.

  The cam 91 and the cam gear 92 are provided in the gear case 44 of the charger 40 as shown in FIGS. 3, 4, and 5. The cam 91 is exposed on the surface of the gear case 44 on the support member 11 side, and is attached to be rotatable about an axis parallel to the axis of the screw rod 81 (see FIG. 6). The cam 91 is coupled to a cam gear 92 and is rotated by a motor 82 via a reduction gear 83 connected to the cam gear 92. As a result, the motor 82 rotates, and the cam 91 also rotates simultaneously with the movement of the cleaning member 46. As shown in FIGS. 7 and 8, the cam engagement protrusion 93 is provided on the surface of the support member 11 on the gear case 44 side. When the charger 40 is inserted into the square hole 13 of the support member 11 and attached to a predetermined position with respect to the photosensitive drum 21, the side surface 91 a of the cam 91 is engaged with the top portion 93 a of the cam engagement protrusion 93. Become. The cam 91 retracts the shield case 41 of the charger 40 to a position approaching the photoconductive drum 21 whenever the cross-sectional shape in a direction perpendicular to the axis of the photoconductive drum 21 rotates to a predetermined angle. It is shaped to move between positions.

  Subsequently, an operation at the time of cleaning of the charger 40 having the above-described configuration will be described with reference to FIGS. 9 to 11 in addition to FIGS. 3 and 6. FIG. 9 is a schematic rear view showing the positional relationship between the charger and the photosensitive drum, and shows the state where the charger is in the approaching position with respect to the photosensitive drum. FIG. The state in the retracted position is shown. FIG. 11 is a left side view showing the assembled state of the charger and the photosensitive drum similar to those in FIG. 3, and shows the state where the charger is in the retracted position with respect to the photosensitive drum. In FIGS. 9 and 10, the photosensitive drum 21 and the support member 11 are drawn by a two-dot chain line so that the configuration can be easily grasped.

  As shown in FIGS. 3 and 9, the shield case 41, which is the main body of the charger 40, is in an approach position with respect to the photosensitive drum 21 during the normal image forming operation of the image forming unit 20. At this time, the distance between the grid 43 and the surface of the photosensitive drum 21 is 0.5 mm. And the cleaning member 46 shown in FIG. 6 is located in the back side of the shield case 41, ie, the left end part in FIG.

  When the cleaning of the charge wire 42 and the grid 43 by the cleaning member 46 is started from this state, the screw rod 81 is rotated by the motor 82 and the cleaning member 46 moves toward the front side of the shield case 41. When the motor 82 is driven for cleaning, the cam 91 also rotates simultaneously via the reduction gear 83 and the cam gear 92. The cam 91 rotates while its side surface 91 a is engaged with the top portion 93 a of the cam engagement projection 93. As a result, the shield case 41 starts moving in the retraction direction with respect to the photosensitive drum 21 in the square hole 13 of the support member 11 against the elastic force of the spring 12.

  When the cleaning member 46 moves while cleaning the charge wire 42 and the grid 43 by driving the motor 82 and the cam 91 rotates to a predetermined angle, the shield case 41 is moved as shown in FIGS. Then, the photosensitive drum 21 moves to the retracted position. Since the cam mechanism 90 for moving the shield case 41 to the retracted position is provided on the front side of the shield case 41 as shown in FIG. 11, the position change of the shield case 41 is centered on the end A on the back side. Is made by the rotational movement (arrow B in FIG. 11).

  Note that the position change from the approach position of the shield case 41 to the retracted position with respect to the photosensitive drum 21 is completed when the cleaning member 46 advances about ¼ from the rear side end portion of the shield case 41 toward the front side end portion. To do. By using an overload prevention device such as a gear or a torque limiter with locally missing teeth on either the cam gear 92 or the reduction gear 83, cleaning can be performed after the position change of the shield case 41 is completed. Even if the motor 82 rotates, the cleaning member 46 can be moved without applying a load to the cam mechanism 90.

  When the cleaning member 46 is returned from the front side of the shield case 41 to the back side, the shield member 46 is returned from the back side end portion of the shield case 41 to about 1/4 of the front side end portion. The shield case 41 gradually moves toward the approach position by the action of the spring 12 (see FIG. 3) that biases the case 41 to the approach position and the cam mechanism 90.

  In this way, the shield case 41 which is the main body of the charger 40 can take both the approach and retreat positions with respect to the photosensitive drum 21 which is an image carrier. Therefore, there is no need to separately provide a means for moving the shield case 41 away from or close to the photosensitive drum 21. As a result, the charger 40 can be retracted from the photosensitive drum 21 with a simple structure with reduced cost without using a complicated structure. Therefore, it is possible to easily clean the charge wire 42 and the grid 43 which are discharge members by preventing damage to the surface of the photosensitive drum 21. By reliably cleaning the charge wires 42 and the grid 43, it is possible to achieve high-quality image formation and a longer life of the charger 40.

  Moreover, since the position change of the shield case 41 as the main body is performed simultaneously with the movement of the cleaning member 46, the cleaning time can be shortened. Further, since a mechanism for separately changing the position of the shield case 41 and the movement of the cleaning member 46 is not required, the structure can be further simplified and the increase in the cost of the charger 40 can be suppressed.

  Further, the shield case 41 includes a cam mechanism 90 provided with a cam 91 that rotates with the movement of the cleaning member 46, and the cam case 91 engages with the support member 11 that supports the shield case 41, thereby the shield case 41. Therefore, by using the cam mechanism 90, the force to move the cleaning member 46 in the direction in which the charge wire 42 and the grid 43 are installed is used to retract the charger 40 from the photosensitive drum 21. It can be used. Therefore, the charger 40 can be easily retracted from the photosensitive drum 21.

  The position of the shield case 41 is changed by rotational movement around one end of the charge wire 42 and the grid 43 in the erection direction. For example, using a functional member such as a solenoid, the axis of the photosensitive drum 21 can be changed. A complicated structure that slides the shield case 41 in a direction that forms a right angle is not required. Therefore, the charger 40 can be moved closer to and away from the photosensitive drum 21 by a simple mechanism of rotating around a predetermined fulcrum.

  Further, since the spring 12 is provided as an urging means for urging the portion of the shield case 41 where the cam mechanism 90 is provided in a direction to approach the photosensitive drum 21, the charger 40 retracted from the photosensitive drum 21. Can be easily moved to the approach position, and can be accurately moved to a predetermined place to be located at the time of discharge. As a result, even if the shield case 41 is moved for cleaning the charge wires 42 and the grid 43, the shield case 41 is positioned at a predetermined position when the photosensitive drum 21 is charged in the image forming operation. The charging characteristics of the surface of the photosensitive drum 21 are not adversely affected.

  In the present invention, since the charger 40 is mounted on the image forming apparatus 1, the charge wire 42 can be easily prevented by preventing damage to the surface of the photosensitive drum 21 with a simple structure without using a complicated structure. In addition, a high-performance image forming apparatus 1 that can clean the grid 43 can be obtained.

  Next, a charger 40 according to a second embodiment of the present invention will be described with reference to FIGS. 12 is a left side view showing the assembled state of the charger and the photosensitive drum, FIG. 13 is a left side view of the vertical section of FIG. 12, and FIG. 14 is a left side view of the vertical section similar to FIG. Shows a state in which is at the retracted position with respect to the photosensitive drum. Since the basic configuration of this embodiment is the same as that of the first embodiment, the description of the drawings and the description of the components common to the first embodiment will be omitted.

  As shown in FIGS. 12 and 13, the charger 40 according to the second embodiment includes a guide rail 84 in the moving means 80 of the cleaning member 46. The guide rail 84 is disposed on the outer side of the shield case 41 in the back direction with respect to the surface of the shield case 41 on which the grid 43 facing the photosensitive drum 21 is provided. The guide rail 84 is provided independently of the shield case 41. The guide rail 84 is provided so that its main portion is substantially parallel to the photosensitive drum 21, the charge wire 42, the grid 43, and the screw rod 81. In the vicinity of the rear side end A of the shield case 41, the guide rail 84 includes an inclined portion 84 a that is inclined away from the rear side end A, that is, in a direction away from the shield case 41 as it approaches the front side. . The inclined portion 84 a has a length of about 1/8 of the entire moving range of the cleaning member 46 in the guide rail 84.

  The cleaning member 46 includes an engaging portion 46c with the guide rail 84 on the support 46a. The engaging portion 46c is provided at a location on the opposite side of the support 46a where the cleaning pad 46b is provided with respect to the screw rod 81. The tip of the engaging part 46 c protrudes outside the shield case 41. A guide pin 46d is provided at the tip of the engaging portion 46c. The guide pin 46 d is engaged with a groove 85 of a guide rail 84 that extends in the front-rear direction of the charger 40.

  Next, an operation at the time of cleaning of the charger 40 having the above configuration will be described.

  As shown in FIGS. 12 and 13, during the normal image forming operation of the image forming unit 20, the shield case 41, which is the main body of the charger 40, is in an approach position with respect to the photosensitive drum 21. The cleaning member 46 is located at the rear end A of the shield case 41, that is, the left end in FIGS. From this state, when the cleaning of the charge wire 42 and the grid 43 by the cleaning member 46 is started, the screw rod 81 is rotated by the moving means 80 (see FIG. 4), and the cleaning member 46 faces the front side of the shield case 41. Move.

  At this time, the cleaning member 46 moves while cleaning the charge wire 42 and the grid 43, and the front side of the shield case 41 moves in the retracting direction with respect to the photosensitive drum 21 by the action of the cam mechanism 90. start. In this way, the position of the front surface side of the shield case 41 is changed by the rotational movement (arrow C in FIG. 14) about the rear surface side end A.

  On the other hand, in the vicinity of the rear side end portion A of the shield case 41, the cleaning member 46 that has started to move from this position moves to the front side of the shield case 41 according to the rotation of the screw rod 81, and the inclined portion of the guide rail 84 It is moved in the direction of retreating from the photosensitive drum 21 along the shape of 84a. As a result, the rear side end A of the shield case 41 is moved in the direction of the retracted position with respect to the photosensitive drum 21. When the cleaning member 46 reaches a predetermined position, the guide rail 84 becomes substantially parallel to the axis of the photosensitive drum 21, and the rear end A of the shield case 41 has a photosensitive drum as shown in FIG. The position is changed to the retracted position with respect to 21.

  The movement of the front side and the rear side of the shield case 41 as described above is simultaneously performed according to the movement of the cleaning member 46. As a result, when the cleaning member 46 moves by a predetermined amount, the shield case 41 finishes changing its position to the retracted position substantially parallel to the axis of the photosensitive drum 21 as shown in FIG.

  In addition, when the cleaning member 46 advances about 1/8 from the rear side end A of the shield case 41 toward the front side end, the position change from the approach position on the rear side of the shield case 41 to the retracted position is completed. . And when the cleaning member 46 advances about 1/4, the position change of the front side of the shield case 41 is completed.

  When the cleaning member 46 is returned from the front side to the back side of the shield case 41, the cleaning member 46 is returned from the back side end A to the front side end of the shield case 41 to about a quarter. Due to the action of the spring 12 (see FIG. 3) urging the shield case 41 to the approach position and the cam mechanism 90, the front side of the shield case 41 gradually moves toward the approach position. The cleaning member 46 is exposed to light by the action of the inclined portion 84a of the guide rail 84 from when the cleaning member 46 returns from the back side end portion of the shield case 41 to about 1/8 of the position toward the front side end portion. It is moved in the direction approaching the body drum 21, and the back side of the shield case 41 gradually moves toward the approach position.

  In this way, the position change of the shield case 41 which is the main body of the charger 40 is performed by rotating the charge wire 42 and the grid 43 around one end in the erection direction and the shield case 41 serving as the center of the rotation movement. Since the rear end A is moved toward and away from the photosensitive drum 21, the entire shield case 41 can be retracted from the photosensitive drum 21. As a result, the rear end A of the shield case 41, which is the center of the rotational movement, can also prevent damage to the surface of the photosensitive drum 21 during cleaning of the charge wires 42 and the grid 43, and charging. It becomes possible to clean the entire wire 42 and the grid 43 reliably.

  Further, the moving means 80 of the cleaning member 46 engages with the cleaning member 46, and this end is moved away from the photosensitive drum 21 as the cleaning member 46 moves away from the rear side end A which is the center of the rotational movement of the shield case 41. Since the guide rail 84 to be retracted is provided, it is not necessary to separately provide means for moving the back side end A of the shield case 41 away from or close to the photosensitive drum 21. As a result, the entire charger 40 can be retracted from the photosensitive drum 21 with a simple structure with reduced cost without using a complicated structure.

  Next, a charger 40 according to a third embodiment of the present invention will be described with reference to FIGS. 15 is a left side view showing the assembled state of the charger and the photosensitive drum, FIG. 16 is a left side view of the vertical section of FIG. 15, and FIG. 17 is a left side view of the vertical section similar to FIG. Shows a state in which is at the retracted position with respect to the photosensitive drum. Since the basic configuration of this embodiment is the same as that of the first and second embodiments, the components common to the first and second embodiments are described in the drawings, and The explanation will be omitted.

  As shown in FIGS. 15 and 16, the charger 40 according to the third embodiment includes a guide rail 84 in the moving means 80 of the cleaning member 46. On the back side of the guide rail 84, a housing 87 provided with a spring 86 is provided. The spring 86 has one end attached to the housing 87 and the other end attached to the insulating member 45 on the back side of the shield case 41. The spring 86 is a biasing means that biases the rear side end A of the shield case 41 in the direction in which it is retracted from the photosensitive drum 21, that is, upward in FIGS. 15 and 16. The spring 86 is composed of a tension coil spring, but may be an elastic member such as a leaf spring, rubber, or sponge. The housing 87 is formed integrally with the guide rail 84, and is independent of the shield case 41 like the guide rail 84.

  Next, an operation at the time of cleaning of the charger 40 having the above configuration will be described.

  As shown in FIGS. 15 and 16, the shield case 41, which is the main body of the charger 40, is in an approach position with respect to the photosensitive drum 21 during the normal image forming operation of the image forming unit 20. The cleaning member 46 is located at the rear end A of the shield case 41, that is, at the left end in FIGS. From this state, when the cleaning of the charge wire 42 and the grid 43 by the cleaning member 46 is started, the screw rod 81 is rotated by the moving means 80 (see FIG. 4), and the cleaning member 46 faces the front side of the shield case 41. Move.

  At this time, the cleaning member 46 moves while cleaning the charge wire 42 and the grid 43, and the front side of the shield case 41 is rotated around the rear side end A by the action of the cam mechanism 90 ( The position is changed by the arrow D) in FIG.

  On the other hand, in the vicinity of the rear side end portion A of the shield case 41, the cleaning member 46 that has started to move from this location moves to the front side of the shield case 41 and follows the shape of the inclined portion 84a of the guide rail 84. It is moved in a direction to retract from the photosensitive drum 21. In addition, the rear end A of the shield case 41 is moved in the direction of the retracted position with respect to the photosensitive drum 21 by the action of a spring 86 provided at this location. When the cleaning member 46 reaches a predetermined position, the guide rail 84 becomes substantially parallel to the axis of the photosensitive drum 21, and the rear side end A of the shield case 41 has a photosensitive drum as shown in FIG. The position is changed to the retracted position with respect to 21.

  The movement of the front side and the rear side of the shield case 41 as described above is simultaneously performed according to the movement of the cleaning member 46. Accordingly, when the cleaning member 46 moves by a predetermined amount, the position change of the shield case 41 to the retracted position in a state substantially parallel to the axis of the photosensitive drum 21 is completed as shown in FIG.

  When the cleaning member 46 is returned from the front side to the back side of the shield case 41, the cleaning member 46 is returned from the back side end A to the front side end of the shield case 41 to about 1/4. Therefore, the front side of the shield case 41 gradually moves toward the approach position by the action of the spring 12 (see FIG. 3) for biasing the shield case 41 to the approach position and the cam mechanism 90. When the cleaning member 46 returns from the back side end portion of the shield case 41 to a position about 1/8 toward the front side end portion, the spring 86 is elastically moved by the action of the inclined portion 84a of the guide rail 84. The cleaning member 46 is moved in the direction approaching the photosensitive drum 21 against the force, and the back side of the shield case 41 gradually moves toward the approach position.

  In this manner, since the rear end A, which is the center of the rotational movement of the shield case 41, is provided with the spring 86 that biases the back end A in the direction in which it is retracted from the photosensitive drum 21, the movement of the cleaning member 46 is performed. At the same time, the rear end A of the shield case 41 can be easily retracted from the photosensitive drum 21. As a result, the entire charger 40 can be reliably retracted from the photosensitive drum 21, so that safety against damage to the surface of the photosensitive drum 21 during cleaning of the charge wires 42 and the grid 43 is further enhanced.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a charger that cleans the discharge member by moving in the installation direction of the discharge member.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with a charger according to an embodiment of the present invention. It is a model vertical cross-section part enlarged view which shows an image formation part periphery. FIG. 3 is a left side view illustrating a state where the charger and the photosensitive drum according to the first embodiment of the present invention are assembled. It is a perspective view of a charger. It is a partial expansion perspective view of a charger. It is a left view which shows the charger of the state which removed the shield case. It is a front view of the supporting member of a charger. It is a perspective view of the supporting member of a charger. The model rear view showing the positional relationship between the charger and the photosensitive drum shows a state where the charger is in an approaching position with respect to the photosensitive drum. The model rear view showing the positional relationship between the charger and the photosensitive drum shows a state where the charger is in the retracted position with respect to the photosensitive drum. FIG. 5 is a left side view showing a state in which the charger and the photosensitive drum similar to those in FIG. 3 are assembled, and shows a state in which the charger is in a retracted position with respect to the photosensitive drum. FIG. 6 is a left side view illustrating a state where a charger and a photosensitive drum according to a second embodiment of the present invention are assembled. FIG. 13 is a left side view of the vertical cross section in a state where the charger and the photosensitive drum of FIG. 12 are assembled. FIG. 14 is a left side view of a vertical section showing a state where the charger and the photosensitive drum are assembled as in FIG. 13, and shows a state where the charger is in a retracted position with respect to the photosensitive drum. It is a left view which shows the state which assembled the charging device and photoconductor drum which concern on the 3rd Embodiment of this invention. FIG. 16 is a left side view of the vertical cross section in a state where the charger and the photosensitive drum of FIG. 15 are assembled. FIG. 17 is a left side view of a vertical section showing a state where the charger and the photosensitive drum are assembled as in FIG. 16, and shows a state where the charger is in a retracted position with respect to the photosensitive drum.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Support member 13 Spring (biasing means)
14 square hole 20 image forming part 21 photoconductor drum 40 charger 41 shield case 42 charge wire 43 grid 44 gear case 45 insulating member 46 cleaning member 46c engaging part 80 moving means 81 screw rod 82 motor 83 speed reduction gear 84 guide rail 84a Inclined part 86 Spring (biasing means)
90 Cam mechanism 91 Cam 92 Cam gear 93 Cam engagement protrusion

Claims (8)

A charger comprising a main body and a cleaning member that is provided on the main body and moves in a direction in which the discharge member is installed to clean the discharge member. ,
The main body can take both approach and retreat positions with respect to the image carrier, and this position change is made by a moving means for moving the cleaning member ,
Provided with a cam mechanism having a cam that rotates together with the movement of the cleaning member, and wherein Rukoto the body is moved to the retracted position by the cam engages the supporting member supporting the main body Charger.   The charger according to claim 1, wherein the position change of the main body is performed simultaneously with the movement of the cleaning member. 3. The charger according to claim 1, wherein the position of the main body is changed by rotational movement about one end of the discharge member in the erection direction. 4. The urging means for urging a portion of the main body where the cam mechanism is provided in a direction to approach the image carrier. 5. Charger. The position of the main body is changed by rotating around the one end of the discharge member in the erection direction and moving the end of the main body that is the center of the rotating movement toward and away from the image carrier. The charger according to claim 3 or 4, wherein The moving means includes a guide rail that engages with the cleaning member and retracts the main body end from the image carrier as the cleaning member moves away from the main body end serving as the center of the rotational movement. The charger according to claim 5. The charger according to claim 6, further comprising: an urging unit that urges an end of the main body that is the center of the rotational movement in a direction in which the main body is retracted from the image carrier. An image forming apparatus comprising the charger according to any one of claims 1 to 7.

Images