JP2018004732A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can prevent a light guide member of a static elimination part from being contaminated by a scattered toner, and in turn suppressing a deterioration in print image quality caused by lack of elimination of static electricity on an image carrier.SOLUTION: An image forming apparatus comprises a static elimination part 5Y that irradiates, with rays of static elimination light L1 and L2, a first area 21Y on a surface of an image carrier 2Y of a first image forming part 11Y and a second area 22C on a surface of an image carrier 2C of a second image forming part 11C. The static elimination part 5Y includes a light guide member 52 that guides light emitted from a light source and made incident on its one end along its longitudinal direction and emits the light from its outer peripheral surface in a direction intersecting with the longitudinal direction. The light guide member 52 includes, on a side facing the second area 22C, a prism part 526 that reflects light traveling inside the light guide member 52 toward the first area 21Y. The prism part 526 has a first edge part on a side closer to an intermediate transfer belt 12 located closer to the second area 22C side than a second edge part on a side farther from the intermediate transfer belt 12.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electrophotographic image forming apparatus including a static elimination unit.

  An electrophotographic image forming apparatus includes a static eliminating unit that neutralizes the surface of an image carrier such as a photosensitive drum. The static elimination unit may include a long light guide member disposed along the rotation axis direction of the photosensitive drum and a light source that emits light toward an end of the light guide member.

  In the tandem image forming apparatus, the light guide member may irradiate the surface of two photosensitive drums adjacent to each other in the traveling direction of the lower surface of the intermediate transfer belt (for example, Patent Document 1). reference).

  The light guide member in this case includes two reflecting portions having a plurality of recesses, and one reflecting portion reflects light toward a position after transfer of the toner image on one surface of the two photosensitive drums, The other reflecting portion reflects light toward the position before transfer of the toner image on the other of the two photosensitive drums.

JP2013-113901A

  However, since the two reflecting portions are prism portions each having a plurality of concave portions, toner scattered from the developing portion or the like is likely to adhere to these reflecting portions. In particular, when the two reflecting portions are provided on the light guide member, the occupied area of the plurality of recesses on the outer surface of the light guide member is large, and the problem of scattered toner adhesion appears more remarkably.

  On the other hand, when the reflection part is contaminated by the adhesion of toner, the amount of light emitted from the light guide member decreases. For this reason, the surface of the image carrier is not sufficiently neutralized, which causes a deterioration in print image quality.

  An object of the present invention is to provide an image forming apparatus capable of preventing a light guide member of a charge eliminating portion from being contaminated by scattered toner, and thus preventing deterioration in print image quality due to insufficient charge removal of an image carrier. .

  An image forming apparatus according to one aspect of the present invention includes an intermediate transfer belt, two image forming units, and a charge eliminating unit. The intermediate transfer belt is a rotating belt-like member on which a toner image is transferred. The two image forming units each have an image carrier, a developing unit, and a cleaning unit. The image carrier rotates while contacting the lower surface of the intermediate transfer belt. The developing unit develops the electrostatic latent image formed on the surface of the image carrier into a toner image. The cleaning unit removes residual toner from the surface of the image carrier after the toner image is transferred to the intermediate transfer belt. The neutralization belt is the intermediate transfer belt on the surface of the image carrier of the first image forming section, which is one of the two image forming sections disposed on the upstream side in the traveling direction of the lower surface of the intermediate transfer belt. A first area between a first transfer position in contact with the first imaging section and a position of the first imaging section facing the cleaning section; and the image carrier of the second imaging section as the other of the two imaging sections. On the surface of the second image forming portion between the second region between the position facing the developing portion and the second transfer position in contact with the intermediate transfer belt, and the first region and the second region The second region is irradiated with static elimination light. The charge removal unit includes a light source and a light guide member. The light source emits light used for neutralizing the intermediate transfer belt. The light guide member is disposed along a rotation axis direction of the image carrier of the first image forming unit, guides light incident on one end from the light source along the longitudinal direction, and from the outer peripheral surface of the light guide member. The light is emitted in a direction crossing the longitudinal direction. The light guide member has a prism portion that reflects light traveling inside the light guide member toward the first region by a plurality of concave portions arranged in the longitudinal direction on the outer surface of the light guide member facing the second region. Have The first edge portion of the prism portion closer to the intermediate transfer belt is located closer to the second region than the second edge portion farther from the intermediate transfer belt.

  According to the present invention, it is possible to provide an image forming apparatus capable of preventing the light guide member of the charge removal unit from being contaminated by the scattered toner, and thus preventing the deterioration of the print image quality due to insufficient charge removal of the image carrier. It becomes.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram of an example of an image forming unit provided in the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a plan view of two image forming units. FIG. 4 is a cross-sectional view of two image forming units. FIG. 5 is a cross-sectional view of a portion surrounded by an imaginary line in FIG. FIG. 6 is a perspective view of an example of the light guide member of the static elimination unit. 7 is a cross-sectional view of a portion taken along the line VII-VII in the light guide member shown in FIG. FIG. 8 is a cross-sectional view of a portion taken along line VIII-VIII in the light guide member shown in FIG. FIG. 9 is a partially omitted perspective view of an example of the holding member. FIG. 10 is an enlarged cross-sectional view of the periphery of the charge removal portion and the holding member.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  As shown in FIGS. 1 and 2, the image forming apparatus 10 includes a plurality of image forming units 11 (11Y, 11C, 11M, and 11K), an intermediate transfer belt 12 that is a rotating belt-like member, an optical scanning device 13, and the like. A secondary transfer roller 14, a fixing device 15, a paper discharge tray 16, a paper feed cassette 17, a transport path 18 and the like are provided. The image forming apparatus 10 is a color printer that forms a color image or a monochrome image based on image data input from an information processing apparatus such as a personal computer on a sheet supplied from a sheet feeding cassette 17 along a conveyance path 18. . In addition, a facsimile machine, a copier, and a multifunction machine are examples of the image forming apparatus according to the present invention.

  The image forming units 11 are arranged in parallel along the traveling direction D1 of the intermediate transfer belt 12, and form an image on a sheet by a so-called tandem method. Specifically, a yellow toner image is formed in the image forming unit 11Y. In each of the image forming units 11C, 11M, and 11B, a cyan toner image, a magenta toner image, and a black toner image are formed. For example, the image forming unit 11Y for yellow, the image forming unit 11C for cyan, the image forming unit 11M for magenta, and the image forming unit 11K for black are sequentially arranged from the upstream side in the traveling direction D1 of the intermediate transfer belt 12. Are arranged in a line in that order. The traveling direction D1 is a direction in which the lower surface of the intermediate transfer belt 12 travels.

  The image forming unit 11 includes a photosensitive drum 2, a charging unit 3, a developing unit 4, a charge removing unit 5, a primary transfer roller 6, and a cleaning unit 7.

  The photosensitive drums 2 are arranged in parallel along the traveling direction D1 of the intermediate transfer belt 12. The photosensitive drum 2 is an image carrier that carries an electrostatic latent image and a toner image, and rotates with the intermediate transfer belt 12 while being in contact with the lower surface of the intermediate transfer belt 12.

  The charging unit 3 includes a charging roller 31 that charges the corresponding photosensitive drum 2 with power supplied from a power source (not shown). The photosensitive drum 2 charged by the charging unit 3 is irradiated with laser light by the optical scanning device 13, and an electrostatic latent image based on the image data is formed on the outer peripheral surface of the photosensitive drum 2.

  The developing unit 4 includes a developing roller 41 that develops the electrostatic latent image formed on the photosensitive drum 2 with toner (developer). The developing unit 4 is formed at a position below the neutralizing unit 5 as a whole. In the development of the electrostatic latent image by the developing unit 4, an external additive such as a lubricant or an abrasive may be used together with the toner. The developing unit 4 is supplied with toner from removable toner containers 19 (19Y, 19C, 19M, 19K) corresponding to the respective colors.

  The primary transfer roller 6 transfers the toner image formed on the photosensitive drum 2 to the lower surface of the intermediate transfer belt 12. The intermediate transfer belt 12 travels above the photosensitive drum 2 of the image forming unit 11. The toner images of the respective colors formed on the photosensitive drum 2 are sequentially superimposed and transferred onto the lower surface of the intermediate transfer belt 12.

  The toner image on the intermediate transfer belt 12 is transferred by the secondary transfer roller 14 to a sheet conveyed from the paper feed cassette 17 via the conveyance path 18. Thereafter, the toner image transferred to the sheet is heated and fixed on the sheet by the fixing device 15.

  The cleaning unit 7 includes a cleaning roller 71 that removes residual toner from the surface of the photosensitive drum 2 after the toner image is transferred to the intermediate transfer belt 12 by the primary transfer roller 6.

  The neutralization unit 5 applies a neutralization light L1 for neutralizing the photosensitive drum 2 to a first region 21 between the transfer position 20 in contact with the intermediate transfer belt 12 on the outer peripheral surface of the photosensitive drum 2 and the cleaning unit 7. Irradiate.

  The details of the charge removal unit 5 will be described below with reference to FIGS. 3 to 10 by taking the charge removal unit 5Y of the image forming unit 11Y as an example. Since the static elimination units 5C and 5M of the image forming units 11C and 11M have the same configuration and operation as the static elimination unit 5Y, and the static elimination unit 5K of the image forming unit 11K has the same configuration as the static elimination unit 5Y, the static elimination units 5C and 5M , 5K will not be described.

  The image forming unit 11C is disposed downstream of the image forming unit 11Y in the traveling direction D1. Note that the configurations of the image forming unit 11Y and the image forming unit 11C described below excluding the charge removal units 5Y and 5C correspond to examples of the first image forming unit and the second image forming unit of the present invention, respectively.

  As shown in FIGS. 3 and 4, the charge removal portion 5Y is provided between the photosensitive drum 2Y of the image forming unit 11Y and the photosensitive drum 2C of the image forming unit 11C. Specifically, the charge removal portion 5Y is fixed to the cleaning portion 7Y via a holding member 8 described later. As a result, the charge removal portion 5Y is disposed between the first region 21Y on the outer peripheral surface of the photosensitive drum 2Y of the image forming unit 11Y and the second region 22C on the outer peripheral surface of the photosensitive drum 2C of the image forming unit 11C. ing.

  The first area 21 </ b> Y is an area between the first transfer position 20 </ b> Y that contacts the intermediate transfer belt 12 on the outer peripheral surface of the photosensitive drum 2 </ b> Y and the cleaning unit 7. That is, the first area 21Y is a charge eliminating area after the toner image is transferred on the outer peripheral surface of the photosensitive drum 2Y.

  The second area 22C is an area between the second transfer position 20C that contacts the intermediate transfer belt 12 on the outer peripheral surface of the photosensitive drum 2C and the developing unit 4C. That is, the second area 22C is a charge eliminating area before the transfer of the toner image on the outer peripheral surface of the photosensitive drum 2C.

  The neutralization unit 5Y irradiates the first region 21Y of the photosensitive drum 2Y with the neutralization light L1, and irradiates the second region 22C of the photosensitive drum 2C of the image forming unit 11C with the neutralization light L2. As described above, the charge removal unit 5Y performs charge removal after the transfer of the photosensitive drum 2Y of the image forming unit 11Y and charge removal before the transfer of the photosensitive drum 2C of the image forming unit 11C.

  In addition, as can be understood from FIG. 1, in the image forming units 11C and 11M, similarly, the charge removal units 5C and 5M, in addition to the charge removal after the transfer of the toner image to the photosensitive drums 2C and 2M, downstream in the traveling direction D1. The charge is removed before transferring the photosensitive drums 2M and 2K of the image forming units 11M and 11K on the side.

  Therefore, in the image forming units 11C, 11M, and 11K, the photosensitive drums 2C, 2M, and 2K are neutralized before and after the transfer of the toner images of the photosensitive drums 2C, 2M, and 2K to the intermediate transfer belt 12. Thereby, in the image forming apparatus 10, so-called memory images of the photosensitive drums 2C, 2M, and 2K are suppressed.

  Since the yellow image is not conspicuous, the problem of the image memory is not easily revealed even if the neutralizing light L2 is not applied to the photosensitive drum 2Y of the image forming unit 11Y corresponding to yellow. For this reason, in the image forming apparatus 10, the disposition of the neutralizing unit 5 that irradiates the photosensitive drum 2Y of the image forming unit 11Y provided on the most upstream side in the traveling direction D1 with the neutralizing light L2 is omitted.

  Of course, it is also conceivable that the image forming apparatus 10 includes the charge removing unit 5 that irradiates the photosensitive drum 2Y of the image forming unit 11T with the charge removing light L2. Further, since the image forming unit 11K is provided on the most downstream side in the advancing direction D1, the charge removing unit 5K is used only for discharging the first region 21K of the photosensitive drum 2K.

  As shown in FIG. 3, the static elimination unit 5Y includes a light source 51 such as an LED and a long light guide member 52 extending in the axial direction of the photosensitive drum 2Y.

  The light source 51 emits light used for neutralizing the photosensitive drum 2Y. The light source 51 is disposed in a direction in which the light emission surface 511 faces the first end surface 521 of the light guide member 52.

  The light emitted from the light source 51 enters the first end surface 521 that is one end of the light guide member 52 in the longitudinal direction D2. In the light guide member 52, light incident from the first end surface 521 is repeatedly reflected and guided toward the second end surface 522, which is the other end in the longitudinal direction D2, and intersects the longitudinal direction D2 from the outer peripheral surface. Emitted in the direction.

  In the present embodiment, a case where the light source 51 is provided facing the first end surface 521 of the light guide member 52 will be described as an example. However, the light source facing the first end surface 521 of the light guide member 52 is described. A configuration in which a light source is provided opposite to the second end surface 522 in addition to 51 and light enters from both the first end surface 521 and the second end surface 522 is also conceivable as another embodiment.

  As illustrated in FIGS. 5 to 7, the light guide member 52 includes a base portion 523 and a lens portion 524. The light guide member 52 is formed of a material such as resin, for example, in a substantially D-shaped cross section having a dimension in the longitudinal direction D2 larger than that of the photosensitive drum 2Y. The longitudinal direction D2 corresponds to a direction parallel to the rotation axis direction of the photosensitive drum 2Y.

  The base 523 is formed on the side of the light guide member 52 that faces the second region 22C (see FIG. 4). The side facing the second region 22C is the downstream side in the traveling direction D1. The base 523 is a portion having a certain thickness, and corresponds to a portion on the right side of the virtual line B in the light guide member 52 shown in FIG. The base 523 has an inclined surface 525 that is a long rectangular plane extending in the longitudinal direction D2. The inclined surface 525 is a portion on the side facing the second region 22C on the surface of the base 523.

  The inclined surface 525 is formed in a long rectangular shape having a long side along the longitudinal direction D2 of the light guide member 52 and a short side along a direction orthogonal to the longitudinal direction D2. Hereinafter, the direction along the short side perpendicular to the longitudinal direction D2 on the inclined surface 525 is referred to as a short direction D4.

  The inclined surface 525 is inclined with respect to the vertical direction D3. The inclination angle of the inclined surface 525 with respect to the vertical direction D3 is, for example, not less than 5 ° and not more than 15 °. The inclined surface 525 of the base 523 is formed with a prism portion 526 that reflects the light traveling inside the light guide member 52 toward the first region 21Y.

  The prism portion 526 has a plurality of concave portions 527 formed at intervals along the longitudinal direction D2. In the light guide member 52, a plurality of recesses 527 are formed at equal intervals. The prism portion 526 reflects the light traveling in the light guide member 52 along the longitudinal direction D2 toward the first region 21Y.

  Hereinafter, the edge portion forming the end near the intermediate transfer belt 12 in the prism portion 526 and the edge portion forming the end far from the intermediate transfer belt 12 are referred to as a first edge portion 528 and a second edge portion 529, respectively. Called. The first edge portion 528 and the second edge portion 529 correspond to the upper edge portion and the lower edge portion of the inclined surface 525, respectively.

  In the prism portion 526, the first edge portion 528 is located on the second region 22C side with respect to the second edge portion 529. That is, the prism part 526 faces obliquely downward. For this reason, for example, toner scattered from above the charge removal unit 5 such as toner scattered from the intermediate transfer belt 12 is suppressed from adhering to the prism unit 526. Thereby, it is possible to prevent the light guide member 52 from being contaminated by the scattered toner, and as a result, it is possible to prevent the print image quality from being deteriorated due to insufficient charge removal of the photosensitive drum 2.

  6-8, the recessed part 527 comprises the groove | channel of the planar view rectangle extended in the transversal direction D4 of the inclined surface 525, and is open | released in the downstream of the advancing direction D1. The dimension of the long side of the recess 527 in plan view is smaller than the dimension of the short side of the inclined surface 525, and both end portions in the long side direction of the recess 527 are not open in the short direction D 4 of the inclined surface 525. The short side direction of the concave portion 527 corresponds to the long side direction of the inclined surface 525 and the long side direction D2 of the light guide member 52, and the long side direction of the concave portion 527 corresponds to the short side direction D4 of the inclined surface 525.

  In the example shown in FIG. 8, the cross section along the longitudinal direction D <b> 2 in each of the recesses 527 is uniformly V-shaped. Other embodiments in which the cross-sectional shape of the recess 527 is semicircular or the like are also conceivable.

  The light traveling inside the light guide member 52 is reflected at the interface 527A along the inner surface of each of the recesses 527 in the light guide member 52 and travels toward the first region 21Y. Here, as for the recessed part 527, the upper end part of the long side direction along the transversal direction D4 is not open | released in the transversal direction D4 side of the inclined surface 525. Therefore, the concave portion 527 can suppress the inflow of scattered toner from the upper end portion.

  As shown in FIGS. 4 and 5, the lens portion 524 is formed on the upstream side in the traveling direction D <b> 1 with respect to the base portion 523 of the light guide member 52. The lens portion 524 corresponds to the left portion of the imaginary line B in the light guide member 52 shown in FIG.

  The shape of the cross section along the direction orthogonal to the longitudinal direction D2 in the lens portion 524 is uniformly substantially semicircular. The lens unit 524 collects the light reflected by the prism unit 526 and irradiates the first region 21Y as the charge removal light L1. Thereby, the light guide member 52 emits uniform light along the longitudinal direction D2 toward the first region 21Y as charge removal light L1.

  The direction of the optical axis L0 of the lens portion 524 is a direction orthogonal or substantially orthogonal to the inclined surface 525 of the base portion 523. Here, “substantially orthogonal” means a range in which the inclination angle with respect to the orthogonal direction is ± 5 °. Therefore, the optical axis L0 of the lens unit 524 corresponds to the inclination angle of the inclined surface 525, and is inclined upward at, for example, 5 ° to 15 ° with respect to the traveling direction D1 of the intermediate transfer belt 12. That is, the neutralizing light L1 is emitted from the lens portion 524 slightly upward with respect to the traveling direction D1 of the intermediate transfer belt 12.

  The optical axis L0 intersects the first region 21Y. That is, the inclination angle of the optical axis L0 of the lens unit 524 with respect to the traveling direction D1 of the intermediate transfer belt 12 is set to an angle at which the optical axis L0 does not deviate from the first region 21Y. Therefore, of the static elimination light L1 emitted from the lens unit 524 toward the first area 21Y, the light having the highest intensity around the optical axis L0 is input to the first area 21Y of the photosensitive drum 2Y as the static elimination light L1. Direct irradiation. Thereby, the intensity | strength of the static elimination light L1 irradiated to the 1st area | region 21Y of the photoreceptor drum 2Y is fully ensured.

  It should be noted that the shape of the lens portion 524 is not limited to a semicircular cross section, and other shapes having a condensing function may be employed. It is also conceivable that the light guide member 52 is a member having a circular or elliptical cross section.

  As shown in FIGS. 9 and 10, the holding member 8 is a member that fixes the light guide member 52 to the cleaning unit 7Y. The holding member 8 has a pair of fixing pieces 81 and a holding portion 82. The pair of fixed pieces 81 and the holding portion 82 are integrally formed of a material such as resin.

  The pair of fixing pieces 81 are portions for fixing the holding member 8 to the cleaning unit 7Y. The pair of fixed pieces 81 are provided at an interval corresponding to the width of the cleaning unit 7Y (see FIG. 3). The width dimension of the cleaning unit 7Y is the dimension of the cleaning unit 7Y in the longitudinal direction D2 of the light guide member 52.

  Each fixing piece 81 is provided with a groove 811. The groove 811 extends in the vertical direction D3 and engages with a convex portion (not shown) of the cleaning portion 7Y. The holding member 8 is fixed to the cleaning unit 7Y by engaging the convex portion of the cleaning unit 7Y with the groove 811 of the fixing piece 81.

  In the drawing, only the groove 811 formed in one fixed piece 81 is shown, but the other fixed piece 81 is also provided with a similar groove 811. The method of fixing the holding member 8 to the cleaning unit 7Y may be other than the method of fixing the groove 811 of the fixing piece 81 to the convex portion of the cleaning unit 7Y.

  The holding portion 82 is a portion that holds the light guide member 52, and includes a pair of holding pieces 83, a substrate portion 84, and a wall portion 85. The pair of holding pieces 83 are provided at an interval corresponding to the width of the cleaning unit 7Y (see FIG. 3). Each of the pair of holding pieces 83 is formed with a D-shaped through hole 831 corresponding to the cross-sectional shape of the light guide member 52. The light guide member 52 is held by the holding member 8 by inserting both end portions of the light guide member 52 into the through holes 831.

  The substrate portion 84 is a flat portion that extends along the longitudinal direction D2 of the light guide member 52 and connects the pair of holding pieces 83. In a state in which the holding member 8 is fixed to the cleaning unit 7Y, the substrate unit 84 contacts the upper surface of the cleaning unit 7Y. Thereby, the holding member 8 is fixed to the cleaning unit 7Y in a stable posture.

  It is also conceivable that the substrate portion 84 supports the lower edge of the light guide member 52 in a state where the pair of holding pieces 83 hold the light guide member 52. The substrate portion 84 along the longitudinal direction of the light guide member 52 supports the light guide member 52, whereby the light guide member 52 can be prevented from bending.

  The wall portion 85 extends from the edge of the substrate portion 84 on the second region 22C side toward the upper side in a range extending from one side of the pair of holding pieces 83 to the other, and is integrated with the holding portion 82 of the holding member 8. Is formed. In a state where the pair of holding pieces 83 hold the light guide member 52, the wall portion 85 faces the prism portion 526 of the light guide member 52 on the second region 22C side through a gap.

  Further, the facing surface 851 facing the prism portion 526 in the wall portion 85 is formed in parallel or substantially parallel to the inclined surface 525 of the prism portion 526 along the longitudinal direction D2. That is, the facing surface 851 of the wall portion 85 is inclined with respect to the up-down direction D3, like the base portion 523 of the light guide member 52.

  As described above, the developing unit 4Y is positioned relatively below the static eliminating unit 5Y. Therefore, the wall portion 85 has a facing surface 851 inclined in the vertical direction D3 and faces the prism portion 526, so that the light guide member is made of toner scattered from the developing portion 4C of the image forming unit 11C on the downstream side in the traveling direction D1. This prevents the prism portion 526 of 52 from being contaminated.

  Further, since the wall portion 85 is formed integrally with the holding member 8, the number of parts can be reduced. Therefore, the wall portion 85 integrally formed as a part of the holding member 8 is advantageous in terms of cost as compared with a wall-like member provided separately from the holding member 8.

  A reflection member 86 is provided on the facing surface 851 of the wall portion 85. The reflecting member 86 is formed, for example, by attaching a reflecting film such as an aluminum vapor deposition film or a white film, or applying a white paint. The reflection member 86 on the facing surface 851 reflects light emitted from the prism portion 526 of the light guide member 52 toward the wall portion 85.

  A part of the light reflected by the reflecting member 86 passes through the prism portion 526 and returns to the inside of the light guide member 52, and a part of the light is repeatedly reflected between the prism portion 526 and the reflecting member 86. A portion of the light that is repeatedly reflected and reflected between the prism portion 526 and the reflecting member 86 is emitted from the opening 53 formed between the first edge portion 528 of the prism portion 526 and the top portion 852 of the wall portion 85. .

  Part of the light emitted from the opening 53 travels downstream in the traveling direction D1, and reaches the second region 22C of the photosensitive drum 2C on the downstream side. That is, the light emitted from the opening 53 is used as the charge removal light L2 for the second region 22C. Further, not only the light emitted from the opening 53 but also the light emitted from the lens portion 524 and the base portion 523 to the downstream side in the traveling direction D1 is irradiated to the second region 22C as the charge removal light L2.

  It is also conceivable that the entire holding member 8 or the wall portion 85 is formed of a white member such as a white resin. Thereby, the opposing surface 851 of the wall part 85 comprises a reflective surface.

  The wall portion 85 has a height dimension such that a gap G1 between the top portion 852 and the lower surface of the intermediate transfer belt 12 is larger than a gap G2 between the first edge portion 528 of the prism portion 526 and the lower surface of the intermediate transfer belt 12. . That is, a relatively large gap G1 between the top portion 852 of the wall portion 85 and the lower surface of the intermediate transfer belt 12 is secured. Therefore, not only the light emitted from the opening 53 but also a part of the light emitted from the base 523 is directly irradiated to the second region 22C as the static elimination light L2. Thereby, the light quantity of the static elimination light L2 irradiated to the 2nd area | region 22C is ensured large. Therefore, even if the holding member 8 has the wall portion 85 that faces the prism portion 526, the neutralizing light L2 having sufficient intensity for performing static neutralization before transfer of the toner image is applied to the photosensitive drum 2C. The two regions 22C are irradiated.

  As described above, the image forming apparatus 10 prevents the light guide member 52 of the static elimination unit 5 from being contaminated by the scattered toner, and as a result, has a print image quality due to insufficient static elimination of the image carrier such as the photosensitive drum 2. Deterioration can be prevented.

10: image forming apparatus 11: image forming unit 12: intermediate transfer belt 2: photoconductor drum 20: transfer position 21: first region 22: second region 3: charging unit 4: developing unit 5: neutralizing unit 51: light source 52 : Light guide member 521: First end surface 522: Second end surface 523: Base portion 524: Lens portion 525: Inclined surface 526: Prism portion 527: Concave portion 528: First edge portion 529: Second edge portion 6: Primary transfer roller 7 : Cleaning part 8: Holding member 85: Wall part 851: Opposing surface 852: Top part 86: Reflecting member

Claims (8)

An intermediate transfer belt which is a rotating belt-like member on which a toner image is transferred;
An image carrier that rotates while contacting the lower surface of the intermediate transfer belt, a developing unit that develops an electrostatic latent image formed on the surface of the image carrier into a toner image, and the toner image transferred to the intermediate transfer belt Two image forming units each having a cleaning unit for removing residual toner from the surface of the image carrier after being formed,
The first transfer in contact with the intermediate transfer belt on the surface of the image carrier of the first image forming portion which is one of the two image forming portions arranged on the upstream side in the traveling direction of the lower surface of the intermediate transfer belt. A first region between a position and a position of the first imaging unit facing the cleaning unit, and a surface of the image carrier of the second imaging unit that is the other of the two imaging units, The second image forming unit is disposed between the second region between the position facing the developing unit and the second transfer position in contact with the intermediate transfer belt, and is excluded from the first region and the second region. A static elimination unit that emits lightning,
The neutralization unit is disposed along a light source that emits light used for neutralization of the intermediate transfer belt and a rotation axis direction of the image carrier of the first imaging unit, and is incident on one end from the light source. A light guide member that guides light along its longitudinal direction and emits light from its outer peripheral surface in a direction crossing the longitudinal direction;
The light guide member has a prism portion that reflects light traveling inside the light guide member toward the first region by a plurality of concave portions arranged in the longitudinal direction on the outer surface of the light guide member facing the second region. Have
An image forming apparatus in which a first edge portion closer to the intermediate transfer belt in the prism portion is located closer to the second region than a second edge portion far from the intermediate transfer belt.   The image forming apparatus according to claim 1, wherein the prism portion is formed on an inclined surface that is inclined toward the second region with respect to a vertical direction. The light guide member has a lens portion through which light reflected by the prism portion passes,
The image forming apparatus according to claim 1, wherein an optical axis of the lens unit intersects the first region.   The image forming apparatus according to claim 1, wherein an inclination angle of a plane including the first edge portion and the second edge portion of the prism portion with respect to a vertical direction is 5 ° or more and 15 ° or less.   The image forming apparatus according to claim 1, further comprising a wall portion facing the second region side through the gap with the prism portion. A holding member fixed to the cleaning unit of the first image forming unit and holding the light guide member;
The image forming apparatus according to claim 5, wherein the wall portion is formed integrally with the holding member.   The image forming apparatus according to claim 5, wherein a reflection surface that reflects light emitted from the prism portion toward the light guide member is formed on a surface of the wall portion that faces the prism portion. .   8. The gap between the top of the wall and the lower surface of the intermediate transfer belt is greater than the gap between the first edge of the prism and the lower surface of the intermediate transfer belt. Image forming apparatus.

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