# US 9,519,246 B2 · Image forming apparatus having image forming units that vary pressure against developer image carrier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,519,246 B2 - Document ID: US9519246B2 - Status: Granted - Kind: B2 - Application number: 14/920,469 - Filed: 2015-10-22 - Published: 2016-08-04 - Granted: 2016-12-13 - Earliest claimed: 2015-01-29 - Assignees: Oki Data Corporation - Applicants: Oki Data Corporation - Inventors: Toshimasa Shiobara - Web page: https://patentgrep.com/patent/US9519246B2 ## CPC - G03G 15/1665: {by introducing the second base in the nip formed by the recording member and at least one transfer member, e.g. in combination with bias or heat} - G03G 15/1605: {using at least one intermediate support (G03G15/1625 takes precedence)} - G03G 2215/0129: horizontal medium transport path at the secondary transfer - G03G 2215/0193: transfer member separable from recording member - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus includes a developer image carrier, first and second image forming units and first and second transfer parts that are arranged sandwiching the developer image carrier with the first and second image forming units. One of the first image forming unit and the first transfer part moves away from the develop image carrier so that the one of the first image forming unit and the first transfer part has two different positions (an image forming position and a non-image forming position). The image forming apparatus further comprises a pressing force variable mechanism that increases the second pressing force between the second image forming unit and the second transfer part when the one of the first image forming unit and the first transfer part moves from the image forming position to the non-image forming position. ## Claims ### Claim 1 An image forming apparatus, comprising: a developer image carrier that rotates and carries developer images in a carrying direction, a first image forming unit and a second image forming unit that are disposed along the carrying direction of the developer image carrier, a first transfer part that is arranged sandwiching the developer image carrier with the first image forming unit to transfers a developer image formed in the first image forming unit to the developer image carrier, a first pressing force toward the developer image carrier being generated with the first image forming unit, a second transfer part that is arranged sandwiching the developer image carrier with the second image forming unit to transfers a developer image formed in the second image forming unit to the developer image carrier, a second pressing force toward the developer image carrier being generated with the second image forming unit, wherein one of the first image forming unit and the first transfer part moves away from the develop image carrier so that the one of the first image forming unit and the first transfer part has two different positions, one position being defined as an image forming position at which the first pressure force is generated therebetween and the developer image is transferred, the other position being defined as a non-image forming position at which no first pressing force is generated therebetween and the developer image is not transferred, the image forming apparatus further comprises a pressing force variable mechanism that increases the second pressing force between the second image forming unit and the second transfer part when the one of the first image forming unit and the first transfer part moves from the image forming position to the non-image forming position, and when the one of the first image forming unit and the first transfer part is at the non-image forming position that is a position separated from the developer image carrier, the pressing force variable mechanism causes the second pressing force between the second image forming unit and the second transfer part to be increased while moving another of the first image forming unit and the first transfer part in the direction to further stretch the developer image carrier. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein the developer image carrier is in a circular shape, and the first image forming unit and the second image forming unit are both disposed outside the developer image carrier. ### Claim 3 (depends on 1) The image forming apparatus according to claim 1, wherein the pressing force variable mechanism further comprises: a first bias part that biases the first transfer part toward the first image forming unit, and a second bias part that biases the second transfer part toward the second image forming unit. ### Claim 4 (depends on 3) The image forming apparatus according to claim 3, wherein the pressing force variable mechanism further comprises a link part that links the first transfer part and the second transfer part and adds an additional bias force to the second transfer part in the same direction as a first bias force by the first bias part is applied to the first transfer part. ### Claim 5 (depends on 4) The image forming apparatus according to claim 4, wherein the pressing force variable mechanism further comprises a fulcrum part that rotatably supports the link part. ### Claim 6 (depends on 4) The image forming apparatus according to claim 4, wherein the pressing force variable mechanism further comprises a cam that enhances the additional bias force that is added to the second transfer part through the link part in correspondence with a rotation of the cam. ### Claim 7 (depends on 6) The image forming apparatus according to claim 6, wherein the link part comprises a swing shaft provided between the first transfer part and the second transfer part in the carrying direction, the link part swinging around the swing shaft, and the cam is disposed to come into contact with the link part between the swing shaft and the second transfer part, swinging the link part around the swinging shaft in correspondence with a rotation of the cam so that the first transfer part is either in contact with or separated from the developer image carrier. ### Claim 8 (depends on 1) The image forming apparatus according to claim 1, wherein the second image forming unit is positioned in a downstream side of the first image forming unit in the carrying direction of the developer image carrier. ### Claim 9 (depends on 1) The image forming apparatus according to claim 1, further comprising: a drive part that drives the developer image carrier, and a driven part that stretches the developer image carrier together with the drive part, wherein the second image forming unit is positioned between the driven part and the first image forming unit. ### Claim 10 An image forming apparatus, comprising: a carrying member that rotates and carries a medium thereon in a carrying direction, a first image forming unit and a second image forming unit that are disposed along the carrying direction of the carrying member, a first transfer part that is arranged sandwiching the carrying member with the first image forming unit to transfers a developer image formed in the first image forming unit to the carrying member, a first pressing force toward the carrying member being generated with the first image forming unit, a second transfer part that is arranged sandwiching the carrying member with the second image forming unit to transfers a developer image formed in the second image forming unit to the carrying member, a second pressing force toward the carrying member being generated with the second image forming unit, wherein one of the first image forming unit and the first transfer part moves away from the carrying member so that the one of the first image forming unit and the first transfer part have two different positions, one position being defined as an image forming position at which the first pressure force is generated therebetween and the developer image is transferred, the other position being defined as a non-image forming position at which no first pressing force is generated therebetween and the developer image is not transferred, and the image forming apparatus further comprises a pressing force variable mechanism that increases the second pressing force between the second image forming unit and the second transfer part when the one of the first image forming unit and the first transfer part moves from the image forming position to the non-image forming position, and when the one of the first image forming unit and the first transfer part is at the non-image forming position that is a position separated from the developer image carrier, the pressing force variable mechanism causes the second pressing force between the second image forming unit and the second transfer part to be increased while moving another of the first image forming unit and the first transfer part in the direction to further stretch the developer image carrier. ### Claim 11 (depends on 10) The image forming apparatus according to claim 10, wherein the first image forming unit and the second image forming unit are both disposed at the same side of the carrying member. ### Claim 12 (depends on 10) The image forming apparatus according to claim 10, wherein the pressing force variable mechanism further comprises: a first bias part that biases the first transfer part toward the first image forming unit, and a second bias part that biases the second transfer part toward the second image forming unit. ### Claim 13 (depends on 12) The image forming apparatus according to claim 12, wherein the pressing force variable mechanism further comprises a link part that links the first transfer part and the second transfer part and adds an additional bias force to the second transfer part in the same direction as a first bias force by the first bias part is applied to the first transfer part. ### Claim 14 (depends on 13) The image forming apparatus according to claim 13, wherein the pressing force variable mechanism further comprises a fulcrum part that rotatably supports the link part. ### Claim 15 (depends on 13) The image forming apparatus according to claim 13, wherein the pressing force variable mechanism further comprises a cam that enhances the additional bias force that is added to the second transfer part through the link part in correspondence with a rotation of the cam. ### Claim 16 (depends on 15) The image forming apparatus according to claim 15, wherein the link part comprises a swing shaft provided between the first transfer part and the second transfer part in the carrying direction, the link part swinging around the swing shaft, and the cam is disposed to come into contact with the link part between the swing shaft and the second transfer part. ### Claim 17 (depends on 10) The image forming apparatus according to claim 10, wherein the second image forming unit is positioned in an upstream side of the first image forming unit in the carrying direction of the carrying member. ### Claim 18 (depends on 10) The image forming apparatus according to claim 10, further comprising: a drive part that drives the carrying member, and a driven part that stretches the carrying member together with the drive part, wherein the second image forming unit is positioned between the driven part and the first image forming unit.