JP2004348124A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus constituted so that the influence of noise caused by spark discharge is restrained even when recording paper is removed by detaching a unit or an image carrier (photoreceptor) in a state where the image carrier (photoreceptor) is electrified due to paper jamming in the midst of forming an image as an image forming apparatus to/from which the unit or the image carrier (photoreceptor) can be attached/detached. <P>SOLUTION: The image forming apparatus is constituted so that the unit having the image carrier which has at least a conductive shaft and on which a toner image is formed by an electrophotographic system can be attached/detached. The apparatus has a guiding groove guiding both ends of the conductive shaft of the image carrier so as to position the unit at a specified position on a base frame, and is provided with a charge eliminating member eliminating charge stored in the image carrier through the conductive shaft on the upstream side of the position where the conductive shaft is positioned when the unit in the guiding groove is positioned at the predetermined position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine using the electrophotographic method, and more particularly, to an image forming apparatus in which at least a unit integrating a charging device and an image carrier is detachable. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus or an image forming apparatus in which only an image carrier can be attached and detached, and to an image forming apparatus having a mechanism for removing charges accumulated when the image carrier is detached.

  For image forming devices such as copiers, printers, facsimile machines, and multifunction devices for personal use, at least a unit that integrates at least a charging device and an image carrier composed of a photoreceptor can be attached to and detached from the main body of the image forming device. In this case, a unit in which operability is improved by performing maintenance by the user himself is used.

  However, in such an image forming apparatus in which only the unit or the image bearing member (photoreceptor) can be detached and mounted, the image forming apparatus may not be able to perform image formation during image formation due to a malfunction of the clutch, a poor paper feed due to a skew of the paper, or a slip of the paper. If a paper jam occurs while the recording paper is hung on the image carrier, the image carrier is charged because the charger for charging the image carrier has been moved to just before, and the user is in this state. To remove the jammed recording paper, remove the unit or image carrier from the image forming apparatus main body, remove the paper jam, and insert the unit or image carrier into the image forming apparatus main body again. When the shaft and the grounding member provided on the image forming apparatus main body come into contact with each other, a spark discharge occurs and noise occurs, and the initialization program of the image forming apparatus is operating. Ram there is a phenomenon that does not become printable state in an infinite loop occurs.

  This is because, for example, in a device in which the outer case for toner exchange of the housing of the image forming apparatus is configured to be openable and closable, a safety standard countermeasure function works by intentionally opening the outer case during image formation, and a motor, a clutch, The same occurs when the power supply to a DC high-voltage power supply that supplies a high voltage to the charging device of the drum is cut off. That is, when such a discharge phenomenon occurs, a noise signal generated by the discharge phenomenon directly enters a lead wire laid in the image forming apparatus or a circuit pattern of the main board, and the CPU of the control device executes the initialization program. This causes a state in which the ready signal, which is issued when the initialization program is normally executed, is not issued. These phenomena are likely to occur particularly when the resinification rate of the product is high and the countermeasures against static electricity are not perfect.

  For example, Japanese Patent Application Laid-Open No. H11-163873 discloses a method of removing electricity from a unit or an image carrier in an image forming apparatus. When a photosensitive drum unit or another unit is exchanged, a photosensitive drum or a developing sleeve is charged by electric charges generated for some reason. A process that includes a photoconductor drum to prevent a charged memory from being generated in the photoconductor due to a discharge between the photoconductor drum and a conductive member disposed close to the photoconductor drum when the photoconductor drum is charged. When a cartridge or a developing unit is mounted, the developing sleeve included in the photosensitive drum or the developing unit is brought into contact with an electrode provided in the image forming apparatus before the process cartridge reaches a predetermined position, and the charged charge is transferred to the main body. An image in which the same potential is supplied through the main body by releasing or dropping both the photosensitive drum and the developing sleeve to ground. Forming apparatus is shown.

JP-A-9-90690

  However, in the image forming apparatus disclosed in Patent Document 1, the photosensitive drum and the developing sleeve are charged by electric charges generated for some reason, and the conductive drum disposed in close proximity to the photosensitive drum. This is a mechanism for preventing charge memory from being generated on the photoconductor due to discharge between the members, and can prevent the charge memory.However, since noise during discharge is not taken into account, It is impossible to prevent the initialization program of the image forming apparatus from falling into an infinite loop due to such noise.

  Therefore, in the present invention, in an image forming apparatus in which a unit or an image carrier (photoconductor) is detachable, the unit or the image carrier (photoconductor) is charged in a state where the image carrier (photoconductor) is charged by paper jam during image formation. An object of the present invention is to provide an image forming apparatus in which the influence of noise due to spark discharge can be suppressed even when the recording paper is removed by detaching the photosensitive member.

In order to solve the above problems, in the present invention,
An image forming apparatus in which a unit having an image carrier that forms a toner image by electrophotography with at least a conductive shaft is detachable,
The image forming apparatus has a guide groove that guides both ends of the conductive shaft of the image carrier in the base frame and positions the unit at a predetermined position, and when the unit is positioned at a predetermined position of the guide groove. A contact member that contacts the conductive shaft is provided, and a charge removing member that removes charges accumulated in the image carrier through the conductive shaft is provided upstream of the predetermined position. And

  As described above, when the unit having at least the image carrier is attached to and detached from the image forming apparatus, the charge accumulated in the image carrier is reduced by providing the discharging member for discharging the electric charge accumulated in the image carrier in the guide groove. At least two times, when removing and attaching, the charge is removed by discharging between the conductive shaft of the image carrier and the charge removing member, and the charge is reduced accordingly. For this reason, the unit is removed, and then mounted and positioned at a predetermined position (a position where the conductive shaft of the image carrier is arranged during image formation in the guide groove), so that the distance between the conductive shaft of the image carrier and the contact member is reduced. Even if noise is generated due to discharge, the noise is weak, so that the unit or the image carrier is detached while the image carrier is charged due to paper jam during image formation as described above. Even if the recording paper is removed, a discharge is generated when the conductive shaft and the contact member come into contact with each other, and the noise signal due to the discharge prevents the execution of the initialization program in the CPU of the control device. it can.

  The static elimination member is a static elimination brush, and is configured by bundling needle-like conductors having a volume resistivity of 1 to 0.01 Ω · cm, thereby efficiently removing a charge remaining on the image carrier by discharging. Becomes possible.

  The static elimination member is attached and detached by attaching the tip of the needle-shaped conductor to the conductive axis passing through the guide groove, for example, by a fixed distance of, for example, 1 to 2 mm. Also, since the static eliminator and the conductive shaft of the image carrier are not in contact with each other, the bundled conductors of the static eliminator are distorted and bent, or the broken tips fall into the image forming apparatus and are moved by the wind of the internal fan. It is possible to prevent the occurrence of defects on the substrate or the like, and even if the device is installed at a fixed distance in this manner, the charge is discharged by corona discharge. Hindering the execution of the initialization program.

  Further, the static elimination member is provided on a drive plate formed of a conductor and provided with a driving force transmission mechanism, and the width of the static elimination brush is larger than the diameter of the conductive shaft, and the guide groove is formed through a groove having a width of 10 mm or less. By facing the shaft end surface of the conductive shaft to be moved along, it is not necessary to construct a special grounding means, so that the image forming apparatus can be formed at low cost.

  Further, the static elimination member is a metal sheet metal member that is disposed so as to protrude into the guide groove, and contacts the conductive shaft when the conductive shaft is guided along the guide groove to detach the unit. Is also good.

  As described above, according to the present invention, at least when the unit having the image carrier is detached from the image forming apparatus, the charge removing member discharging the electric charge accumulated in the image carrier is made to peep into the guide groove, so that the image carrier is removed. The electric charge accumulated in the body is discharged between the conductive shaft of the image carrier and the charge eliminating member at least twice when the unit is removed and when the unit is attached, and the electric charge is reduced accordingly. Therefore, if the unit is removed and then mounted and positioned at a predetermined position, even if a discharge occurs between the conductive shaft of the image carrier and the abutting member and noise occurs, the noise is weak. Therefore, even if the unit or the image carrier is detached and the recording paper is removed in a state where the image carrier is charged due to a paper jam during image formation as described above, the initialization program in the CPU of the control device is generated by the noise signal. Execution can be prevented from being hindered.

  The static elimination member is a static elimination brush, and a volume specific resistance of 1 to 0.01 Ω · cm is formed by bundling a needle-like conductor coated with copper sulfide, so that the charge remaining on the image carrier is efficiently stored. The charge can be removed by discharging.

  The static elimination member is attached and detached by attaching the tip of the needle-shaped conductor to the conductive axis passing through the guide groove, for example, by a fixed distance of, for example, 1 to 2 mm. Also, since the static eliminator and the conductive shaft of the image carrier are not in contact with each other, the bundled conductors of the static eliminator are distorted and bent, or the broken tips fall into the image forming apparatus and are moved by the wind of the internal fan. It is possible to prevent the occurrence of defects on the substrate or the like, and even if the device is installed at a fixed distance in this manner, the charge is discharged by corona discharge. Hindering the execution of the initialization program.

  Further, the static elimination member is provided on a drive plate formed of a conductor and provided with a driving force transmission mechanism, and has a width L larger than the width of the conductive shaft and faces the guide groove through a groove having a width of 10 mm or less. This eliminates the need to construct a special grounding means, so that the image forming apparatus can be configured at low cost.

  Furthermore, the static elimination member may be a metal sheet metal member that is disposed so as to protrude into the guide groove and that contacts the conductive shaft when the conductive shaft is installed at a predetermined position in the guide groove.

  Hereinafter, embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention to them, unless otherwise specified, and are merely mere descriptions. This is just an example.

  FIG. 1 is a conceptual diagram for explaining the main components of the image forming apparatus of the present invention and the conveyance path of the recording paper. FIG. 2 is a left guide for guiding at least a unit having an image carrier of the image forming apparatus according to the present invention. FIG. 3 is an enlarged view of the groove (A) and a perspective view (B) of the image forming apparatus according to the present invention excluding an outer cover. FIG. 3 is a right guide groove for guiding at least a unit having an image carrier in the image forming apparatus of the present invention. FIG. 4 is an enlarged view (A) of the image forming apparatus of the present invention and a perspective view (B) of the image forming apparatus without the outer cover, and FIG. It is a figure showing a position to be peeped from. FIG. 5 is a diagram (A) showing the mounting state (A) and the mounting position of the charge removing member for performing corona discharge of the charge accumulated on the image carrier in the image forming apparatus of the present invention, and FIG. 6 is an image forming apparatus of the present invention. FIG. 7 is a detailed view of a charge removing member for corona discharging the electric charge accumulated in the image bearing member in FIG. 7, and FIG. 7 shows an example of a unit having at least the image bearing member in the image forming apparatus of the present invention when viewed from the right (A) and left (B), respectively. FIG. 8 is a diagram showing a second embodiment (A) of a static elimination member for discharging electric charges accumulated on an image carrier in the image forming apparatus of the present invention and a state of attachment to a drive plate (B). FIG. 9 is a view showing a state in which a second embodiment of a charge removing member for discharging electric charges accumulated in the image carrier is positioned near the right guide groove, and FIG. 10 is an image carrier in the image forming apparatus of the present invention. Release the charge stored in FIG. 11 is a view showing a third embodiment of a static elimination member to be discharged, and FIG. 11 shows a state in which a third embodiment of a static elimination member for discharging electric charges accumulated on an image carrier in an image forming apparatus of the present invention is attached to a drive plate. FIG. 12 and FIG. 12 are views showing a fourth embodiment (A) of a charge removing member for discharging electric charges accumulated on an image carrier in an image forming apparatus of the present invention, and a state of attachment to a drive plate (B). is there.

  In FIG. 1, the same components are denoted by the same reference numerals. In FIG. 1, reference numeral 1 denotes a paper feed cassette containing recording paper 2, 3 denotes a pickup roller for picking up the recording paper 2, and 4 denotes a picked-up recording paper 2. A separation / feed roller for separating and conveying the recording paper one by one; 5 an intermediate roller; 6 a second paper feeding roller for feeding out the recording paper placed in a manual paper feeding unit one sheet at a time; And a registration roller for sending the recording paper 2 to the transfer position in accordance with the timing of forming the toner image on the photoconductor (image carrier) 8, 8 is a photoconductor (image carrier), 9 is a transfer roller, 10 Is a fixing roller, 11 is a discharge roller, and 12 is a drive to these pickup roller 3, intermediate roller 5, second paper supply roller 6, registration roller 7, photoconductor (image carrier) 8, fixing roller 10, discharge roller 11, and the like. Power That the motor, the conveyance path of the recording paper from the paper feed cassette 1 is 13, 14 manual feed conveying path of the recording sheet from the manual sheet feeder, 15 is a conveying path from the intermediate roller 5 to the discharge roller 11. Around the photosensitive member (image carrier) 8, a charging device (not shown), an exposure opening, a developing device, a cleaning blade (cleaning means), and the like are arranged to constitute a process unit. From the roller 4 to the intermediate roller 5, from the intermediate roller 5 to the registration roller 7, from the photoconductor (image carrier) 8 to the fixing roller 10, from the fixing roller 10 to the discharge roller 11, a transport guide or a transport roller (not shown) is provided. Have been. The process unit includes not only the above-described photoconductor (image carrier), charging device, exposure opening, developing device, cleaning blade, but also at least the photoconductor (image carrier). It may be a unit integrated with some of the elements.

2, the apparatus body 20 to remove the outer cover of the image forming apparatus in FIG. 3, 21 _1, 21 ₂ is the image forming apparatus main body 20 provided with guide grooves 24, 26 for guiding the driving force transmission mechanism and said process unit A drive plate on which a driving force transmission mechanism and a motor 12 are mounted; 23, a control box of the image forming apparatus main body 20; and 24, 26, a shaft of an image carrier (photoconductor) of a process unit. Therefore, a guide groove provided in the base frame 21, 25 is a predetermined position in the guide groove 24 where the process unit is set, FIG. 2A is an enlarged view of the guide groove 24, and 27 is a charge removing member in the guide groove 26. 3 (A) is an enlarged view of the guide groove 26, and 30 is a position where the process unit is positioned at a predetermined position. A ground plate which is a plate spring as a contact member in contact with the conductive shaft of the image bearing member 8 when the. Although not shown, the conductive axis of the image carrier 8 is connected to a metal portion serving as a base of the image carrier layer of the image carrier inside the image carrier.

  3 to 6, reference numeral 40 denotes a discharging brush as a discharging member according to the first embodiment for performing corona discharge of charges accumulated in the image carrier (photoconductor) 8 in the image forming apparatus of the present invention, 41 denotes a brush holder, Reference numeral 42 denotes a spike formed of a bundle of conductors extruded into a thin thread (needle) by, for example, putting copper powder in a resin. Such a conductor bundle is, for example, such as Sanderon (trade name, manufactured by Tsuchiya Tisco Corporation). A brush having a volume resistivity of 1 to 0.01 Ω · cm by coating a fiber of polycarbonate with copper sulfide may be used, but any material having a similar effect may be used. 43 is a gear provided on the shaft of the motor 12, and 44 is a drive gear of the process unit. In FIG. 7, reference numeral 60 denotes an example of a process unit in which an image carrier (photoconductor), a charging device, a developing device, a cleaning blade (cleaning means), and the like are arranged. Reference numerals 61 and 62 denote conductivity of the image carrier (photoconductor). A shaft, 63 is a charging device, 64 is a developing device, 65 is an image carrier (photoconductor) drum unit, 66 is a toner container containing toner, 67 is an image carrier (photoconductor) 8 which is not transferred to recording paper. A toner collecting unit that collects toner remaining on the surface.

  In FIG. 8, reference numeral 70 denotes a ground metal plate as a second embodiment of a static eliminator for discharging electric charges accumulated on an image carrier (photoreceptor), 71 is a tip, 72 is a peak, 73 is a screw hole, 74 is a locking portion, 75 is a hole provided in the drive plate 22, and 76 is a locking hole. In FIG. 10, reference numeral 80 denotes a ground metal plate as a third embodiment of a static elimination member that discharges electric charges accumulated on an image carrier (photoconductor). Reference numeral 81 denotes a protrusion 82 and a side plate 83 that relate to the drive plate 22. A side plate 84 for stopping is a ridge. In FIG. 12, reference numeral 90 denotes a ground metal plate as a fourth embodiment of a charge removing member for discharging electric charges accumulated on an image carrier (photoreceptor), and reference numerals 91, 92, and 93 denote openings 96 provided in the drive plate 22; A piece for fixing the ground sheet metal 90 by using the cut-and-raised 97, 94 is a tip of the piece 93, 95 is a crest, 96 is an opening, and 97 is a cut and raised.

First, an outline of the image forming apparatus main body 20 of the present invention will be described. As shown in FIGS. 2 and 3, the image forming apparatus main body 20 includes various mechanical parts on both sides of the main body of the image forming apparatus main body 20. the base frame ₂₁ 1, 21 ₂ for holding is provided with, on its base frame 21 _1, fitted with a motor 12 and a clutch as shown in FIG. 2 (B) on one side, FIG. 5 (B) (Fig. 2 (B) is a view from the mounting surface side of the motor 12 and the like, and FIG. 5 (B) is a view from the mounting surface of the gears and the like, showing the front and back of the drive plate 22.) A drive gear 44 of a process unit 60 (see FIG. 7) driven by a gear 43 attached to a motor shaft, and a drive plate 22 provided with a gear for driving a paper feed / transport system are provided. I have. The process unit 60 including the image carrier (photoconductor) 8, the charging device 63, the developing device 64, and a cleaning blade (cleaning unit, not shown) as shown in FIG. 7 is included in the process unit 60. The conductive shafts 61 and 62 of the image carrier (photoreceptor) 8 are guided by the guide grooves 24 and 26 shown in FIGS. 2 and 3 so that the process unit 60 can be located at a predetermined position. When the process unit 60 is located at a predetermined position, the ground plate (contact member) 30 of FIG. 2A provided at a predetermined position of the guide groove 24 is connected to the conductive shaft 61 of the image carrier (photoconductor) 8. , The image carrier (photoconductor) 8 is grounded.

As shown in FIG. 5A, the charge removing brush 40 as a charge removing member for corona discharge as shown in FIGS. 5 and 6 is provided on the drive plate 22 at the position shown in FIG. It is stuck with double-sided tape. The ears 42 of the brush 40 discharge the electric charge accumulated on the image carrier (photoconductor) 8 from the conductive shaft 61 in the process unit 60 when the process unit 60 is detached, and in this embodiment, cause corona discharge. As shown in FIGS. 3A and 4, the width of the conductive shaft 61 is made larger than the diameter of the conductive shaft 61 so that the charge removing brush 40 can be seen through the guide groove 26 having a width of 10 mm or less. That is, when mounting the drive plate 22 to the base frame 21 _1, Flip conductive units when ears 42 of the discharging brush 40 is removable in a manner crossing the substantially horizontal guide groove 26 which is inclined in the base frame 21 ₁ The neutralizing brush 40 is attached to the drive plate 22 so as to face the other end face. By doing so, the process unit 60 is manually inserted or removed along the guide groove 26, but due to its weight (about 4 kg), the conductive shaft 61 is placed under the guide grooves 24 and 26. The conductive shaft 61 is inserted along the guide grooves 24 and 26 in a state of contact with the side edge, and at this time, the charge removing brush 40 is provided so as to look through the guide groove 26 as shown in FIG. In the middle of insertion or removal from the guide groove, the brush faces the neutralizing brush 40 at a predetermined distance, and neutralization is performed.

  As shown in detail in FIG. 6, the static elimination brush 40 is formed by coating a fiber of polycarbonate such as Sandaron (trade name, manufactured by Tsuchiya Tisco Co.) with copper sulfide, and has a volume resistivity of 1 to 0.01 Ω. The brush holder 41 holds the ears 42 of a bundle of thin thread-like (needle-like) conductors of cm. By doing so, the electric charge transmitted to the charge removing brush 40 drops to the drive plate 22, so that the grounding can be reliably performed. Further, although not shown, the groove width of the guide groove 26 of the brush attachment portion is set to a width that does not allow a human finger to enter, that is, about 10 mm or less, so that a person accidentally touches the brush with a finger and touches the brush. It is configured not to break.

  Corona discharge is a phenomenon in which when a needle-shaped electrode is opposed to a charged electrode, a weak discharge current flows while emitting faint light from near the needle tip at a voltage higher than a certain voltage.For example, conductive fibers are used. Products that discharge static electricity and release it, and can suppress the impact caused by spark discharge at a time like lightning. Therefore, when the accumulated electric charge is subjected to corona discharge, spark discharge does not occur even if it is brought into contact with the electrode and the conductor thereafter, or if it occurs, it becomes very weak. Therefore, when the process unit 60 is attached or detached, the conductive shaft 61 in the process unit 60 is brought close to the neutralization brush 40, and the charge accumulated in the image carrier (photoconductor) 8 is transferred between the neutralization brush 40 and the conductive shaft 61. If a corona discharge is caused between them, it is possible to prevent a phenomenon that the execution of the initialization program in the CPU of the control device is hindered by the above-described noise signal due to the spark discharge due to the accumulated electric charge.

  Next, the operation of the image forming apparatus main body 20 according to the present invention will be described with reference to FIG. 1. When an image forming instruction is received from a control device (not shown), an image carrier (photoconductor) 8) is exposed to form a latent image, and the latent image is also developed by a developing device (not shown) to form a toner image. On the other hand, the recording paper 2 stored in the paper feed cassette 1 is picked up by the pickup roller 3, sent to the intermediate roller 5 by the separation / feed roller 4, and further sent to the registration roller 7. Then, the toner is sent to a transfer position at the timing when a toner image is formed on the image carrier (photoconductor) 8 by the registration roller 7, and the image carrier (photoconductor) 8 is applied by the transfer roller 9 to which a bias is applied. The upper toner image is transferred. The recording paper 2 onto which the toner image has been transferred in this manner is sent to a fixing roller 10 to be fixed, and is discharged by a discharge roller 11. That is, the pickup roller 3 picks up the recording paper 2 stored in the paper feed cassette 1 when an image forming instruction is received, and the second paper feed roller 6 picks up the recording paper 2 placed on the manual feed path 14. When used, the recording paper 2 is rotated and sent out to the intermediate roller 5. On the other hand, the intermediate roller 5 sends the recording paper 2 to the registration roller 7 when the recording paper 2 is sent by the pickup roller 3 and the second paper supply roller 6, and the registration roller 7 is used for the image bearing member (photoconductor). The recording paper 2 is sent out at the timing when a toner image is formed on the transfer roller 9 and the leading end of the toner image comes to the position of the transfer roller 9.

  In the image forming apparatus main body 20 of the present invention configured as described above, as described above, the recording paper is moved to the image bearing member during image formation due to a malfunction of the clutch, a poor paper feed due to a skew of the paper, a slip of the paper, or the like. When a paper jam occurs in a state where the image carrier (photoconductor) 8 is hung, the charging device 63 for charging the image carrier (photoconductor) 8 has been moved immediately before, so that the image carrier (photoconductor) 8 is charged. In this state, the user removes the process unit 60 from the image forming apparatus 20, removes a paper jam, and inserts the process unit 60 into the image forming apparatus main body 20 again. At the time of attachment / detachment, a corona discharge is generated between the conductive shaft 61 of the image carrier (photoconductor) 8 and the charge removal brush 40 looking into the guide groove 26. Therefore, the electric charge accumulated in the image carrier (photoconductor) 8 is almost discharged, the process unit 60 is returned to a predetermined position, and the conductive shaft 61 of the process unit 60 and the contact member shown in FIG. When the grounding plate 30 contacts, the large discharge unlike the conventional case does not occur, and therefore, a malfunction of the initialization program of the image forming apparatus main body 20 due to noise can be avoided.

  Even if the static elimination brush 40 is installed so as to be in contact with the conductive shaft 61 of the process unit 60, corona discharge occurs when the conductive shaft 61 and the static elimination brush 40 come close to each other before contact, and the charge is reduced. Thereafter, the electric charge is completely discharged by the contact between the two, so that the above-mentioned large spark discharge can be prevented. However, when the static elimination brush 40 is made of the above-described polycarbonate or the like, the brush contacts may be disturbed and broken or fall off due to the contact between the brushes, and a part of the ears may fall down, and the fan may cause air blown by the machine. It is transported and falls on the engine board to short-circuit the wiring of the engine board, thereby causing a failure in the engine board. Therefore, as shown in FIG. 5A, the tip of the spike 42 and the conductive shaft 61 of the process unit 60 are separated from each other by, for example, about 1 to 2 mm, preferably about 1 mm, and the spike at the tip of the neutralization brush 40 is disturbed or broken. Failure of the substrate due to falling ears may be prevented. Further, by using the charge removing brush 40 as the charge removing means, there is no need to raise a mold or the like when a leaf spring or the like is used, and the cost can be reduced accordingly.

  In the above description, the charge elimination brush 40 is used as the charge elimination member for removing the charge accumulated on the image carrier (photoconductor) 8 of the process unit 60. 8 and the leaf-spring springs according to the third and fourth embodiments shown in FIGS. 10 and 12A, which can be attached to the drive plate 22 as shown in FIGS. It may be a member.

That is, the leaf spring-like static elimination member 70 of the second embodiment shown in FIG. 8 has a tip 73 that is inserted into a hole 73 for stopping the ridge 72 and the drive plate 22 with screws, and a hole 75 provided in the drive plate 22. 71, a locking portion 74 for locking into a locking hole 76 provided in the drive plate 22 for stopping rotation, and the like. The locking portion 74 is inserted into the locking hole 76 and the tip portion 71 is inserted into the hole 75. , 73 are attached to the drive plate 22 in the form shown in FIG. And when fitted with a drive plate 22 to the base frame 21 _1, when the crests 72 of the grounding plate 70 so as to project into the guide groove 26 as shown in FIG. 9, and to desorb the process unit 60, the conductive When the shaft end face of the sex shaft 61 hits the peak 72 of the ground plate 70, part of the peak 72 escapes into the hole 75 into which the tip 71 is inserted, so that the conductive shaft 61 can pass smoothly. It has become. Thereby, the charges accumulated from the conductive shaft 61 of the process unit 60 are discharged.

  Next, in the third embodiment shown in FIG. 10, the side plate 81 is passed through the hole 85 provided in the drive plate 22 as shown in FIG. 11, and the projection 82 is engaged with the edge of the drive plate 22. Thus, the conductive shaft is fixed by the side plate 81, the side plate 83, and the protruding portion 82 so that the peak portion 84 projects into the guide groove 26 as in the second embodiment shown in FIG. 61. In the fourth embodiment shown in FIG. 12, the pieces 91, 92, and 93 are inserted from the openings 96 provided in the drive plate 22, and the pieces 91, 92 are stretched in the openings 96 by the elasticity of the pieces 91. At the same time, the piece 93 is brought into close contact with the cut-and-raised portion 97 by utilizing the elasticity of the tip 94 and is fixed, so that the peak portion 95 projects into the guide groove 26 as in the second embodiment shown in FIG. Thus, the conductive shaft 61 is brought into contact with the conductive shaft 61. Since the effect of electromagnetic noise is reduced in inverse proportion to the square of the distance, the effect of electric discharge can be eliminated by disposing a leaf spring-like static elimination member at a location away from the wiring and circuit board as described above. it can. By doing so, the grounding plates of the second, third, and fourth embodiments allow the conductive shaft 61 to come into contact with these grounding plates when the process unit 60 is attached and detached, so that the image bearing member (photoconductor) 8 The accumulated charges are discharged, and the malfunction of the initialization program of the image forming apparatus main body 20 due to noise as described above can be avoided.

  In addition to such a leaf spring-shaped member, a metal mesh in which a needle-shaped metal is woven like a non-woven fabric is formed by sandwiching a conductive rubber in order to have elasticity. It may be installed so as to hit the sex axis 61. However, the metal mesh is acicular but thicker than the neutralizing brush 40, and unlike the neutralizing brush 40, its tip is not uniformly oriented in the direction of the conductive shaft 61, so that the neutralizing ability by the corona is small. However, because of the metal mesh shape, the static elimination ability at the time of contact can be larger than that of a leaf spring. In the case of a metal mesh, a contact type and a non-contact type are possible. However, the non-contact type has a large dependence on distance, and a contact type is preferable.

  The position of the contact member is not limited to the above embodiment, and a grounded conductive bearing or the like, which is in contact with the conductive shaft of the image carrier and supported by a member having a spring property, may be used. Alternatively, a member such as a bearing or a bearing that is in contact with the conductive shaft of the image carrier is provided in the process unit 60, and the bearing or the bearing is connected to an earth line provided in the process unit 60, and further the earth line (ground) is provided. Line) may be connected to the ground line of the image forming apparatus.

FIG. 2 is a conceptual diagram for describing main components and a recording paper transport path in the image forming apparatus of the present invention. 3A and 3B are an enlarged view (A) of a left guide groove for guiding at least a unit having an image carrier of the image forming apparatus according to the present invention, and a perspective view (B) of the image forming apparatus according to the present invention excluding an outer cover. FIG. 2A is an enlarged view of a right guide groove for guiding at least a unit having an image carrier in the image forming apparatus of the present invention, and FIG. 2B is a perspective view of the image forming apparatus of the present invention, excluding an outer cover. FIG. 5 is a diagram illustrating a position where the static elimination member of the first embodiment in the image forming apparatus of the present invention attached to a drive plate can be viewed through a guide groove of a base frame. FIG. 7B is a diagram showing a mounting state (A) of a charge removing member for corona discharging an electric charge accumulated on an image carrier in an image forming apparatus of the present invention to a drive plate of the first embodiment and a mounting position of the drive plate; is there. FIG. 3 is a detailed view of a charge removing member that causes corona discharge of the charge accumulated on the image carrier in the image forming apparatus of the present invention. FIG. 2 is a perspective view of an example of a unit having at least an image carrier in the image forming apparatus of the present invention as viewed from a right side (A) and a left side (B). FIG. 8B is a diagram illustrating a second embodiment (A) of a charge removing member that discharges electric charges accumulated on an image carrier in the image forming apparatus of the present invention and a state of attachment of the charge removing member to a drive plate. FIG. 11 is a diagram illustrating a state in which a second embodiment of the charge removing member that discharges the charges accumulated in the image carrier is located near the right guide groove. FIG. 10 is a diagram illustrating a third embodiment of the charge removing member that discharges the charge accumulated on the image carrier in the image forming apparatus of the present invention. FIG. 10 is a diagram illustrating a state in which a third embodiment of a charge removing member that discharges charges accumulated on an image carrier in the image forming apparatus of the present invention is attached to a drive plate. FIG. 9 is a diagram illustrating a fourth embodiment (A) of a charge removing member for discharging electric charges accumulated on an image carrier in the image forming apparatus of the present invention and a state of attachment to a drive plate (B).

Explanation of reference numerals

22 Drive plate 40 Static elimination brush 41 as static elimination member Brush holder 42 Spikes 61, 62 Conductive shaft

Claims (5)

An image forming apparatus in which a unit having an image carrier that forms a toner image by electrophotography with at least a conductive shaft is detachable,
The image forming apparatus has a guide groove that guides both ends of the conductive shaft of the image carrier on the base frame and positions the unit at a predetermined position, and when the unit is positioned at a predetermined position of the guide groove. An image forming apparatus, further comprising a discharging member provided upstream of the predetermined position for discharging charges accumulated in the image carrier through the conductive shaft.   The image forming apparatus according to claim 1, wherein the discharging member is a discharging brush.   The image forming apparatus according to claim 2, wherein the static elimination brush is configured by bundling needle-shaped conductors.   4. The image forming apparatus according to claim 3, wherein a tip of the bundle of the needle-shaped conductors is installed at a predetermined distance from a conductive axis passing through the guide groove. 5. The image forming apparatus according to claim 1, wherein the static elimination member is provided on a drive plate formed of a conductor and provided with a driving force transmission mechanism.

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