# US 4,378,158 A · Developing apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,378,158 A - Document ID: US4378158A - Status: Granted - Kind: A - Application number: 06/167,346 - Filed: 1980-07-10 - Granted: 1983-03-29 - Earliest claimed: 1979-07-16 - Assignees: Canon Kabushiki Kaisha - Inventors: Junichiro Kanbe - Web page: https://patentgrep.com/patent/US4378158A ## CPC - G03G 15/0808: {characterised by the developer supplying means, e.g. structure of developer supply roller} - G03G 15/0806: {on a donor element, e.g. belt, roller (complete developer unit G03G15/0896)} - G03G 2215/0617: contact development (i.e. the developer layer on the donor member contacts the latent image carrier) - G03G 2215/0636: Specific type of dry developer device - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A developing apparatus used to develop the latent image on the latent image holding body, which has a developing agent holding roller established in proximity or in contact with the latent image holding body and a developing agent supplying roller which supplies the developing agent to the developing agent holding roller. The developing agent supplying roller is arranged with a gap against the developing agent holding roller and to this gap an electric field is applied to deliver the developing agent from the one to the other. ## Claims ### Claim 1 A developing apparatus for developing a latent image by applying one component developing agent to a latent image holding body comprising: developing agent holding means for holding the developing agent on the surface thereof and carrying it to a developing station; developing agent supply means for supplying the developing agent to said developing agent holding means, said developing agent supplying means being positioned to face said developing agent holding means with a gap therebetween; means for limiting the thickness of the layer of developing agent formed on said developing agent supplying means to be less than the gap between said developing agent holding means and said developing agent supplying means so as to form a clearance between said developing agent holding means and the layer of developing agent; and means for applying an AC voltage across the gap between said developing agent holding means and developing agent supplying means to cause the developing agent to fly from said developing agent supplying means to said developing agent holding means across the clearance. ### Claim 2 (depends on 1) A developing apparatus as set forth in claim 1 in which said applying means applies an AC voltage on which a DC voltage is superimposed. ### Claim 3 (depends on 1) A developing apparatus as set forth in claim 1, further comprising coating means to apply the developing agent to said developing agent supplying means. ### Claim 4 (depends on 3) A developing apparatus as set forth in claim 3 in which said coating means is an elastic blade made to contact with said developing agent supplying means. ### Claim 5 (depends on 1) A developing apparatus as set forth in claim 1, further comprising means for forming an electric field to prevent fogging between the latent image holding body and said developing agent holding means. ### Claim 6 (depends on 1) A developing apparatus as set forth in claim 1 in which said developing agent holding means has at least the surface composed of an elastic body and is made to contact with the latent image holding body. ### Claim 7 (depends on 1) A developing apparatus as set forth in claim 1 in which said developing agent holding means is formed with conductive material. ### Claim 8 (depends on 1) A developing apparatus as set forth in claim 1 further comprising means for removing the developing agent which remains on said developing agent holding means after developing the latent image. ### Claim 9 (depends on 8) A developing apparatus as set forth in claim 8 in which said developing agent removing means is an elastic plate made to contact with said developing agent holding means. ### Claim 10 (depends on 8) A developing apparatus as set forth in claim 8 in which said developing agent removing means is a conductive roller placed close to said developing agent holding means, and further including means for applying an electric field across said developing agent holding means and said conductive roller to attract the developing agent from said developing agent holding means to said conductive roller. ### Claim 11 (depends on 10) A developing apparatus as set forth in claim 10 in which the above-mentioned conductive roller is rotatable at the proximity section against said developing agent holding means in the same direction and at the same speed as said holding means. ### Claim 12 (depends on 10, 11) A developing apparatus as set forth in claim 10 or 11, further comprising an elastic plate used to scrape off the developing agent which has moved to said conductive roller. ### Claim 13 A developing apparatus for developing a latent image by applying one component developing agent to a latent image holding body comprising: developing agent holding means for holding the developing agent on the surface thereof and carrying it to a developing station; developing agent supplying means for supplying developing agent to said developing agent holding means, said developing agent supplying means being positioned to face said developing agent holding means with a gap therebetween; means for limiting the thickness of the layer of developing agent formed on said developing agent supplying means to be less than the gap between said developing agent holding means and said developing agent supplying means so as to form a clearance between said developing agent holding means and the layer of developing agent; means for forming an AC electric field in the gap between said developing agent holding means and developing agent supplying means to cause the developing agent to fly from said developing agent supplying means to said developing agent holding means across the clearance; and means for controlling the thickness of the developing agent layer on said developing agent holding means. ### Claim 14 (depends on 13) A developing apparatus as set forth in claim 13 in which said control means for the thickness of the developing agent layer is a means for controlling the applied voltage used to form the electric field. ### Claim 15 (depends on 13) A developing apparatus as set forth in claim 13 in which said control means for the thickness of the developing agent layer is a means of controlling the relative movement speed of said developing agent holding means and said developing agent supplying means. ### Claim 16 (depends on 13) A developing apparatus as set forth in claim 13 in which said electric field forming means forms an AC electric field by an AC voltage to which a DC voltage is superimposed. ### Claim 17 (depends on 13) A developing apparatus as set forth in claim 13, further comprising coating means to coat the developing agent on said developing agent supplying means. ### Claim 18 (depends on 17) A developing apparatus as set forth in claim 17 in which said coating means is an elastic blade made to contact with said developing agent supplying means. ### Claim 19 (depends on 13) A developing apparatus as set forth in claim 13, further comprising means for forming an electric field between the latent image holding body and said developing agent holding means for prevention of fog formation. ### Claim 20 (depends on 13) A developing apparatus as set forth in claim 13 in which at least the surface of said developing agent holding means is formed with an elastic body which is made to contact with the latent image holding body. ### Claim 21 (depends on 13) A developing apparatus as set forth in claim 13 in which said developing agent holding means is formed with conductive material. ### Claim 22 (depends on 13) A developing apparatus as set forth in claim 13, further comprising means for removing the developing agent remaining on said developing agent holding means after developing the latent image. ### Claim 23 (depends on 22) A developing apparatus as set forth in claim 22 in which said developing agent removing means is a elastic plate made to contact with said developing agent holding means. ### Claim 24 (depends on 22) A developing apparatus as set forth in claim 22 in which said developing agent removing means is a conductive roller arranged in proximity to said developing agent holding means and further comprising means for applying an electric field across said developing agent holding means and conductive roller to attract the developing agent from said developing agent holding means to said conductive roller. ### Claim 25 (depends on 24) A developing apparatus as set forth in claim 24 in which said roller is rotatable in the same direction and at the same speed as said holding means at the proximity section to said developing agent holding means. ### Claim 26 (depends on 24, 25) A developing apparatus as set forth in claim 24 or 25, further comprising an elastic plate used to scrape off the developing agent which has been transferred to said conductive roller. ### Claim 27 A developing apparatus for developing a latent image by applying developing agent to a latent image holding body comprising: developing agent holding means for holding a developing agent layer on its surface and which is movable; developing agent supplying means for supplying the developing agent to said developing agent holding means, the developing agent supplying means being made to face said developing agent holding means with a gap therebetween; and means of forming an alternating electric field in the gap between said developing agent holding means and developing agent supplying means to deliver the developing agent from one to the other. ### Claim 28 (depends on 27) A developing apparatus as set forth in claim 27 in which said electric field forming means forms an AC electric field by an AC voltage on which a DC voltage is superimposed. ### Claim 29 A developing apparatus for developing a latent image by applying developing agent to a latent image holding body comprising: developing agent holding means for holding a developing agent layer on its surface and which is movable; developing agent supplying means for supplying developing agent to said developing agent holding means and which is made to face said developing agent holding means with a gap therebetween; means for forming an alternating electric field in the gap between said developing agent holding means and developing agent supplying means to deliver the developing agent from one to the other; and means for controlling the thickness of the developing agent layer on said developing agent holding means. ### Claim 30 (depends on 13) A developing apparatus as set forth in claim 13 in which said electric field forming means forms an AC electric field by an AC voltage to which a DC voltage is superimposed.