JP2017211560A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of irradiating light outputted from a light guide member of a static elimination part to the outside on an image carrier without waste when each static elimination part of a plurality of image forming parts has each function of the static function after the transfer and the static function before the transfer.SOLUTION: An image forming device includes a charge eliminator 14 having a light source 141 and a rectangular light guide member 142. The light guide member 142 includes a transmission/reflection part 172 which transmits/reflects light incident from the light source 141 on one end of a longitudinal direction, and irradiating the light at each position between a developing roller of the downstream side of a belt rotation direction D1 of an intermediate transfer belt and a primary transfer roller and between a primary transfer roller of the upstream side of a belt rotation direction D2 and a cleaning device. The light guide member 142 is provided with a reflection part 41 which reflects the outgoing light from a transmission/reflection part 172B located at the most downstream side of an optical propagation direction D3 in the light guide member 142 to an inner part of the transmission/reflection part 172.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrophotographic image forming apparatus and a light guide member used therefor.

  In general, a tandem type image forming apparatus including a plurality of image forming units arranged at positions along a rotating endless intermediate transfer belt is known. In the tandem-type image forming apparatus, each of the image forming units includes a drum-shaped image carrier (photoconductor) and a charging unit, a developing unit, a transfer unit, a charge eliminating unit, and a cleaning disposed around the image bearing unit. . Each of the image forming units sequentially forms toner images of different colors on the surface of the intermediate transfer belt. Hereinafter, in the tandem type image forming apparatus, a direction in which the intermediate transfer belt rotates along the arrangement direction of the plurality of image forming units is referred to as a belt rotation direction.

  Further, in the tandem type image forming apparatus, it is known that the charge eliminating unit of each of the image forming units has both a function of irradiating post-transfer charge removal light and a function of irradiating pre-transfer charge removal light (for example, Patent Document 1).

  In addition, using a long light guide member in which a plurality of reflection surfaces are formed along the longitudinal direction, light incident from one end of the light guide member in the longitudinal direction is output in a direction intersecting the longitudinal direction. A line illumination device is known (see, for example, Patent Document 2).

  Conventionally, as an example of the charge removal unit of the image forming apparatus, the light guide member made of a transparent member is used to reflect light from a light source on the reflection surface and between the transfer unit and the cleaning unit. A configuration in which the first charge removal light traveling upstream in the belt rotation direction and the second charge removal light transmitted through the reflection surface and directed to another image carrier positioned downstream in the belt rotation direction are output separately. It has been known.

JP 2011-221405 A JP 2008-140726 A

  However, in a configuration in which a light source is provided at one end in the longitudinal direction of the light guide member, light transmitted through the reflecting surface located on the other end side opposite to the light source is inclined toward the other end side. To exit. In this way, the light emitted obliquely on the other end side is output to the outside unnecessarily without irradiating the area before charging on the image carrier. Further, a part of the light reflected by the reflecting surface located on the other end side is output to the outside without being irradiated to the charged area on the image carrier.

  An object of the present invention is to provide an image bearing member without waste of light output from the light guide member of the charge removal portion when the charge removal portion of each of the plurality of image forming portions also functions as post-transfer charge removal and pre-transfer charge removal. An object of the present invention is to provide an image forming apparatus capable of irradiating a laser beam.

An image forming apparatus according to one aspect of the present invention includes a plurality of image forming units and a charge eliminating unit. Each of the plurality of image forming units is disposed along a rotating endless belt. The image forming unit includes an image carrier, a transfer unit that transfers the toner image carried on the surface of the image carrier to the surface of the belt, and a cleaning unit that cleans the surface of the image carrier, respectively. Including. The plurality of image forming units transfer the toner image from the image carrier to the surface of the belt to form an image on the surface of the belt.
The charge eliminating unit is provided in each of the image forming units. Each of the static elimination units includes a long light guide member made of a transparent member, and a light source that is provided at one end in the longitudinal direction of the light guide member and emits light used for static elimination of the image carrier.
The light guide member has a transmission / reflection part. A plurality of the transmission / reflection portions are provided side by side in the longitudinal direction, and transmit and reflect the light incident on one end of the longitudinal direction from each of the light sources and guided to the other end, and the transfer portion, the cleaning portion, The first neutralization light that goes to the upstream side in the rotation direction of the transfer belt and the second static elimination light that goes to the downstream side in the rotation direction are output separately.
Moreover, the said static elimination part has a 1st reflection part. The first reflecting portion is, among the plurality of transmitting and reflecting portions, the second charge eliminating light that is directed to the downstream side in the rotational direction from an end transmitting and reflecting portion located on the other end side in the longitudinal direction of the light guide member. Is reflected in a direction toward the upstream side of the rotation direction.

  According to the present invention, it is possible to irradiate the image carrier with light output to the outside from the light guide member of the static elimination unit without waste.

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of an image forming unit of the image forming apparatus illustrated in FIG. FIG. 3 is a diagram illustrating a charge removal unit of the image forming unit illustrated in FIG. 2. FIG. 4 is a diagram illustrating a light guide member of the static elimination unit illustrated in FIG. FIG. 5 is a diagram illustrating a cross-sectional shape of the light guide member illustrated in FIG. 4.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. Embodiment described below is only an example which actualized this invention, and does not limit the technical scope of this invention.

  As shown in FIG. 1, the image forming apparatus 10 includes a plurality of image forming units 1 to 4, an intermediate transfer belt 5 (an example of a belt of the present invention), an optical scanning device 6, a secondary transfer roller 7, a fixing device 8, A paper discharge tray 9, toner containers 21 to 24, a paper feed cassette 31, a transport path 32, 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 on a sheet-like sheet supplied from a sheet feeding cassette 31 along a conveyance path 32. A facsimile, a copier, a multifunction machine, and the like are also examples of the image forming apparatus according to the present invention.

  The image forming apparatus 10 is a so-called tandem type. The image forming units 1 to 4 are arranged in parallel along the belt rotation direction D <b> 1 of the intermediate transfer belt 5. A toner image corresponding to Y (yellow) in the image forming unit 1, M (magenta) in the image forming unit 2, C (cyan) in the image forming unit 3, and K (black) in the image forming unit 4 is formed.

  FIG. 2 is a schematic diagram illustrating a schematic configuration of the image forming unit 1 and the image forming unit 2. As shown in FIG. 2, the image forming unit 1 and the image forming unit 2 include a photosensitive drum 11 (an example of the image carrier of the present invention), a charging unit 12 provided corresponding to the photosensitive drum 11, and development. Part 13, a primary transfer roller 15 (an example of a transfer part of the present invention), and a cleaning device 16 (an example of a cleaning part of the present invention). Each of the image forming unit 1 and the image forming unit 2 is provided with a charge eliminating unit 14. Since the image forming unit 3 and the image forming unit 4 are configured in the same manner, description thereof is omitted here.

  Each of the photosensitive drums 11 is arranged in parallel along the belt rotation direction D <b> 1 of the intermediate transfer belt 5. The photosensitive drum 11 is an image carrier that carries an electrostatic latent image and a toner image. Each charging unit 12 includes a charging roller 121. The charging unit 12 uses the charging roller 121 to charge the photosensitive drum 11 to a predetermined potential with electric power supplied from a power source (not shown). The photosensitive drum 11 charged by the charging unit 12 is irradiated with laser light by the optical scanning device 6, and an electrostatic latent image based on the image data is formed on the outer peripheral surface of the photosensitive drum 11. Each developing unit 13 includes a developing roller 131. The developing unit 13 uses the developing roller 131 to develop the electrostatic latent image formed on the photosensitive drum 11 with toner (developer). For developing the electrostatic latent image by the developing unit 13, an external additive such as a lubricant or an abrasive is used together with the toner. Each developing unit 13 is supplied with toner from removable toner containers 21 to 24 corresponding to the respective colors.

  Each primary transfer roller 15 transfers the toner image formed on the photosensitive drum 11 to the intermediate transfer belt 5. The intermediate transfer belt 5 is a member to be transferred that travels above the photosensitive drums 11 of the image forming units 1 to 4 and to which toner images of respective colors formed on the photosensitive drums 11 are sequentially superimposed and transferred. . The toner image on the intermediate transfer belt 5 is transferred by the secondary transfer roller 7 to a sheet conveyed from the paper feed cassette 31 via the conveyance path 32. Thereafter, the toner image transferred to the paper is heated by the fixing device 8 and fixed on the paper. Each of the cleaning devices 16 includes a cleaning member 161 such as a cleaning roller or a cleaning blade for cleaning the photosensitive drum 11 after the toner image is transferred to the intermediate transfer belt 5 by the primary transfer roller 15.

  Each of the neutralization units 14 neutralizes the photosensitive drum 11 at a position between the primary transfer roller 15 and the cleaning member 161 on the outer peripheral surface of the photosensitive drum 11 on the upstream side in the belt rotation direction D1 of the intermediate transfer belt 5. Irradiation light L1 is emitted. In other words, each of the static elimination units 14 irradiates the static elimination light L <b> 1 on the downstream side of the primary transfer roller 15 and the upstream side of the cleaning member 161 in the rotation direction of the photosensitive drum 11. Further, each of the static elimination units 14 places the photosensitive drum 11 at a position between the developing roller 131 and the primary transfer roller 15 on the outer peripheral surface of the photosensitive drum 11 on the downstream side of the intermediate transfer belt 5 in the belt rotation direction D1. Irradiation light L2 for neutralizing is irradiated. In other words, each of the static elimination units 14 irradiates the static elimination light L <b> 2 on the downstream side of the developing roller 131 and the upstream side of the primary transfer roller 15 in the rotation direction of the photosensitive drum 11. In this manner, the so-called memory image of the photosensitive drum 11 is suppressed by eliminating the charge of the photosensitive drum 11 before and after the transfer of the toner image on the photosensitive drum 11 to the intermediate transfer belt 5.

  In this embodiment, the neutralizing light L2 is not applied to the photosensitive drum 11 of the image forming unit 1 corresponding to yellow. This is because the yellow image is not conspicuous, and the problem of the image memory is not easily revealed even if the neutralizing light L2 is not irradiated to the photosensitive drum 11 corresponding to yellow. That is, in the image forming apparatus 10, the photosensitive drum 11 arranged on the most upstream side in the belt rotation direction D1 corresponds to yellow, and the downstream positions of the respective photosensitive drums 11 in the belt rotation direction D1. The static elimination part 14 is arrange | positioned. Of course, the image forming apparatus 10 may include another charge eliminating unit that irradiates the photosensitive drum 11 of the image forming unit 1 with the charge removing light L2.

  Next, the charge removal unit 14 will be described with reference to FIGS. 3 to 6.

  The neutralization unit 14 includes a photosensitive drum 11 disposed on the upstream side of the intermediate transfer belt 5 in the belt rotation direction D1 and a photosensitive drum 11 disposed on the downstream side of the intermediate transfer belt 5 in the belt rotation direction D1. Arranged between. The static eliminating unit 14 is attached to the upper surface of the housing of the cleaning device 16. The charge removal unit 14 includes a light source 141, a long light guide member 142, and a cover member 17 (see FIG. 3) that covers the light guide member 142.

  The light guide member 142 is a rod-like member extending along the axial direction D2 of the photosensitive drum 11, and is formed in a shape that is long in the axial direction D2. The light guide member 142 is longer than the photosensitive drum 11, and is arranged so that the longitudinal direction is parallel to the axial direction D <b> 2 of the photosensitive drum 11.

  The light source 141 is an LED light source that emits light for discharging the photosensitive drum 11. The light source 141 is provided at one end of the light guide member 142 in the longitudinal direction. Light emitted from the light source 141 enters a light incident surface 143 formed on one side of the light guide member 142 in the longitudinal direction. And in the inside of the light guide member 142, the light which injects from the light-incidence surface 143 repeats reflection, and is guide | induced to the light propagation direction D3 (refer FIG. 3) which goes to the end surface 144 of an other end.

  The light guide member 142 is formed of a material such as a transparent resin. As shown in FIG. 4, the light guide member 142 includes a columnar portion 151 having a substantially circular cross section orthogonal to the longitudinal direction, and a trapezoidal portion 152 having a trapezoidal cross section orthogonal to the longitudinal direction. The light guide member 142 is formed by integrally forming a cylindrical portion 151 and a trapezoidal portion 152.

  The light guide member 142 includes a first optical surface 145 and a second optical surface 146 (an example of the optical surface of the present invention).

  The first optical surface 145 is an outer peripheral surface of the cylindrical portion 151 and is an arcuate curved surface. The second optical surface 146 is a part of the outer peripheral surface of the trapezoidal part 152 and is a flat surface at a position facing the first optical surface 145.

  In the present embodiment, the light guide member 142 has the first optical surface 145 directed to the upstream photosensitive drum 11 and the second optical surface 146 directed to the downstream photosensitive drum 11. It is installed on the upper surface of the housing of the cleaning device 16.

  The cover member 17 is provided so as to cover the upper surface of the light guide member 142 and the second optical surface 146. Since the cover member 17 needs to transmit light from the light guide member 142, the cover member 17 is formed of a material such as a transparent resin. The cover member 17 has a facing surface that faces the upper surface of the light guide member 142 and a facing surface that faces the second optical surface 146. The cover member 17 is disposed at a position where a minute gap is formed between each facing surface and the upper surface of the light guide member 142 and the second optical surface 146. The cover member 17 is attached to the upper surface of the housing of the cleaning device 16. Since the cover member 17 is provided, dust or toner is prevented from adhering to the light guide member 142 of the charge removal unit 14.

  The light guide member 142 includes a plurality of transmission / reflection portions 172. The plurality of transmission / reflection portions 172 are formed on the second optical surface 146. A plurality of transmission / reflection portions 172 are formed on the second optical surface 146 at a predetermined interval W1 in the longitudinal direction. That is, the plurality of transmission / reflection portions 172 are arranged on the second optical surface 146 on a straight line with an interval W1 equal to the longitudinal direction.

  The transmission / reflection part 172 is a groove having a triangular cross section formed on the second optical surface 146. In the following description, the flat surface excluding the transmission / reflection part 172 in the second optical surface 146 is referred to as a plane part 171. That is, the second optical surface 146 includes the flat surface portion 171 and the transmission / reflection portion 172. The transmission / reflection portion 172 is a groove that is recessed from the second optical surface 146 toward the inside of the light guide member 142. Specifically, the transmission / reflection portion 172 has a triangular cross section by two reflection surfaces having a predetermined inclination angle from the flat portion 171. The groove is formed in a shape and extends in the short direction of the light guide member 142. The transmission / reflection section 172 is a so-called triangular prism.

  As shown in FIG. 5, when the light traveling inside the light guide member 142 irradiates the reflection surface 173 on the light source 141 side in the transmission / reflection portion 172, a part of the light is reflected on the reflection surface 173 of the transmission / reflection portion 172. And is emitted from the first optical surface 145 as charge removal light L1 (an example of the first charge removal light of the present invention). Further, when the light traveling inside the light guide member 142 irradiates the reflection surface 173 of the transmission / reflection portion 172, a part of the light passes through the reflection surface 173 of the transmission / reflection portion 172 and passes through the second optical surface 146. The light is emitted as static elimination light L2 (an example of the second static elimination light of the present invention).

  Here, as shown in FIG. 3, in the photosensitive drum 11, an area where the electrostatic latent image is formed is an image forming area A <b> 1, and the electrostatic drums positioned at both ends in the axial direction D <b> 2 of the photosensitive drum 11. A region where no latent image is formed is defined as a non-image forming region A2. In this case, the transmission / reflection part 172 is also provided at positions P1, P2 corresponding to the non-image forming area A2 on the second optical surface 146. In the second optical surface 146, the position of the transmission / reflection part 172A provided closest to the light source 141 is the position P1, and the transmission / reflection part provided closest to the light source 141 (that is, the end face 144 side). The position of 172B (an example of the end transmission / reflection part of the present invention) is the position P2.

  In the present embodiment, the intervals between the transmission / reflection portions 172 are equal. However, in the light guide member 142, the amount of light gradually decreases while the light incident from the light source 141 is guided from one end to the other end. Therefore, in the light guide member 142, the interval W1 at which the transmission / reflection portion 172 is formed in the longitudinal direction may be shortened as the distance from the light source 141 increases. Accordingly, the light reflection amount and the light transmission amount by the transmission / reflection part 172 increase at a position far from the light incident surface 143 of the light guide member 142, and therefore, the static elimination light L <b> 1 and static elimination light L <b> 2 in the longitudinal direction of the light guide member 142. Can be made uniform.

  Then, the static elimination unit 14 reflects the light emitted from the light source 141 by the transmission / reflection unit 172, and the primary transfer roller 15 on the outer peripheral surface of the photosensitive drum 11 on the upstream side in the belt rotation direction D1 of the intermediate transfer belt 5. And the cleaning device 16 are irradiated with the static elimination light L1. Further, the static elimination unit 14 transmits the light emitted from the light source 141 through the transmission / reflection unit 172, and the developing roller 131 on the outer peripheral surface of the photosensitive drum 11 on the downstream side in the belt rotation direction D 1 of the intermediate transfer belt 5. The neutralizing light L <b> 2 is irradiated to the position between the primary transfer roller 15. In other words, the plurality of transmission / reflection portions 172 included in the light guide member 142 transmit and reflect light that is incident on the light incident surface 143 at one end in the longitudinal direction from the light source 141 and guided to the end surface 144 on the opposite side, Output is divided into a static elimination light L1 that is directed between the primary transfer roller 15 and the cleaning device 16 toward the upstream side in the belt rotation direction D1 of the intermediate transfer belt 5 and a static elimination light L2 that is directed toward the downstream side in the belt rotation direction D1. To do.

  The inclination angle of the reflection surface 173 (see FIG. 5) of the transmission / reflection part 172 is appropriately determined so that the transmission amount and reflection amount of the light emitted from the light source 141 by the transmission / reflection part 172 have a predetermined relationship. For example, the inclination angle of the transmission / reflection portion 172 is such that the amount of the neutralizing light L1 reaching the photosensitive drum 11 upstream in the belt rotation direction D1 of the intermediate transfer belt 5 and the downstream of the intermediate transfer belt 5 in the belt rotation direction D1. The ratio with respect to the light amount of the static elimination light L2 that reaches the photosensitive drum 11 on the side is determined to be 10: 1.

  As described above, in the present embodiment, the neutralization lights L1 and L2 for neutralizing the upstream and downstream photosensitive drums 11 are supplied by one light guide member 142. Thereby, the structure for performing static elimination before transfer and static elimination after transfer to photoconductor drum 11 can be simplified.

  By the way, in the structure in which the light source 141 is provided at one end portion in the longitudinal direction of the light guide member 142, the reflection surface of the transmissive reflection portion 172B located in the vicinity of the other end portion on the opposite side to the light source 141. The light transmitted through 173 is emitted obliquely toward the light propagation direction D3. As described above, the light emitted obliquely at the other end is not irradiated on the image forming area A1 before charging on the photosensitive drum 11, and is output to the outside unnecessarily. Further, part of the light reflected by the reflection surface 173 of the transmission / reflection part 172B located at the other end is not irradiated to the charged image forming area A1 on the photosensitive drum 11, and is wasted to the outside. Is output.

  For this reason, the reflection unit 41 (the first reflection of the present invention) so that the light output from the light guide member 142 of the charge removal unit 14 to the outside can be irradiated to the image forming area A1 of the photosensitive drum 11 without waste. Part) and the reflecting part 42 (an example of the second reflecting part of the present invention) are provided on the light guide member 142. That is, the static elimination unit 14 includes a reflection unit 41 and a reflection unit 42.

  Specifically, the reflection part 41 is directly attached to the second optical surface 146 so as to block the transmission / reflection part 172B on the second optical surface 146. The reflection unit 41 is, for example, a mirror. The reflecting portion 41 may be a metal foil capable of reflecting light or a reflecting plate coated with a coating that reflects light. Thus, since the reflection part 41 is provided, the reflection part 41 is the static elimination light which goes to the downstream of the said belt rotation direction D1 from the permeation | transmission reflection part 172B located in the other end side of the said light guide member 142 in the said longitudinal direction. L2 is reflected in a direction toward the upstream side of the belt rotation direction D1. As a result, the light transmitted through the reflection surface 173 of the transmission / reflection section 172B can be effectively utilized as the light L2a (see FIG. 5) that irradiates the image forming area A1 of the upstream photoconductor drum 11 and eliminates the charge. In the case where the reflection part 41 is not provided, the light transmitted through the reflection surface 173 of the transmission reflection part 172B is irregularly reflected on other members and irradiated to the image forming area A1 as flare light. However, in the present embodiment, it is possible to suppress the occurrence of the flare light by providing the reflecting portion 41.

  The reflecting portion 42 is directly attached to the end surface 144 on the other end side in the longitudinal direction of the light guide member 142. The reflection unit 42 is, for example, a mirror. The reflecting portion 42 may be a metal foil capable of reflecting light or a reflecting plate coated with a coating that reflects light. Since the reflection part 42 is provided in this way, the reflection part 42 is incident on the light guide member 142 after being reflected by the light reflected by the light reflection member 41 or reflected by the light reflection member 172B. The transmitted light is prevented from being transmitted from the end surface 144 to the outside, and the light is reflected to the inside of the light guide member 142. As a result, the light reaching the end surface 144 can be effectively used as the light L2b and L2c (see FIG. 5) for irradiating the image forming area A1 of the photosensitive drum 11 and eliminating the light without transmitting the light to the outside. In addition, when the reflection part 42 is not provided, the light transmitted through the end surface 144 is irradiated as the flare light to the image forming area A1, but in the present embodiment, the reflection part 42 is provided, thereby It is possible to suppress the generation of flare light.

  In the above-described embodiment, the configuration in which the light guide member 142 is provided with the reflection portion 41 and the reflection portion 42 is exemplified. However, the present invention may be configured such that only the reflection portion 41 is provided on the light guide member 142. Further, in the above-described embodiment, the configuration in which the reflection portion 41 and the reflection portion 42 are directly attached to the light guide member 142 is exemplified. However, the present invention may have a configuration in which the reflective portion 41 is attached to the facing surface of the cover member 17 that faces the second optical surface 146.

1-4: image forming unit 5: intermediate transfer belt 6: optical scanning device 7: secondary transfer roller 8: fixing device 9: paper discharge tray 10: image forming device 11: photosensitive drum 12: charging unit 13: developing unit 14: Static elimination part 15: Primary transfer roller 16: Cleaning device 17: Cover member 41: Reflection part 42: Reflection part 121: Charging roller 131: Development roller 141: Light source 142: Light guide member 145: First optical surface 146: First 2 Optical surface 172: Transmission / reflection part

Claims (4)

An image carrier, a transfer unit for transferring the toner image carried on the surface of the image carrier to the surface of the belt, and the surface of the image carrier are respectively arranged at positions along the rotating endless belt. A plurality of image forming units for forming an image on the surface of the belt by transferring the toner image from the image carrier to the surface of the belt;
A long light guide member made of a transparent member provided in each of the image forming units; and a light source that emits light used for charge removal of the image carrier provided at one end in the longitudinal direction of the light guide member. A static elimination unit,
The light guide member is
A plurality of light sources are arranged side by side in the longitudinal direction, and transmit and reflect light incident on one end of the longitudinal direction from each of the light sources and guided to the other end, and between the transfer unit and the cleaning unit, A transmission / reflecting section that outputs the first charge removal light going upstream in the rotation direction and the second charge removal light going downstream in the rotation direction;
The neutralization unit is configured to transmit the second static elimination light from the end transmission / reflection unit positioned on the other end side in the longitudinal direction of the light guide member to the downstream side in the rotation direction among the plurality of transmission / reflection units. An image forming apparatus including: a first reflection unit configured to reflect in a direction toward an upstream side in a rotation direction.   2. The image formation according to claim 1, wherein the static elimination unit includes a second reflection unit configured to reflect light transmitted to the outside from an end surface on the other end side in the longitudinal direction of the light guide member to the inside of the light guide member. apparatus.   3. The image forming apparatus according to claim 1, wherein the end transmission / reflection portion is provided at a position corresponding to a non-image forming region on the image carrier in the light guide member. The light guide member has a flat optical surface through which the second static elimination light that passes through the transmission and reflection portion and travels downstream in the rotation direction is emitted;
4. The image forming apparatus according to claim 1, wherein the transmission / reflection portion is a groove having a triangular cross section formed from the optical surface toward the inside. 5.

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