# US 7,746,372 B2 · Beam deflector, light scanning unit and image forming apparatus having the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,372 B2 - Document ID: US7746372B2 - Status: Granted - Kind: B2 - Application number: 12/136,960 - Filed: 2008-06-11 - Published: 2009-01-29 - Granted: 2010-06-29 - Earliest claimed: 2007-07-06 - Assignees: Samsung Electronics Co., Ltd. - Inventors: Jae-hwan Yoo - Web page: https://patentgrep.com/patent/US7746372B2 ## CPC - G03G 15/0409: {Details of projection optics (for projection printing apparatus G03B27/522)} - G02B 26/121: {Mechanical drive devices for polygonal mirrors} - G03G 15/0435: {by introducing an optical element in the optical path, e.g. a filter} - G03G 2215/0404: Laser - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A beam deflector having a base, the beam deflector including a polygon mirror to reflect a light beam, a mirror driving unit including a rotor shaft erected from the base and a rotor to support the polygon mirror and to rotate about the rotor shaft, a friction member to contact with and be separated from the rotor so as to obstruct and release rotation of the rotor, respectively, and a friction member driving unit to drive the friction member. ## Claims ### Claim 1 A beam deflector, comprising: a base; a polygon mirror to reflect a light beam; a mirror driving unit comprising a rotor shaft erected from the base, and a rotor to support the polygon mirror and to rotate about the rotor shaft; a friction member to selectively contact and be separated from the rotor to obstruct and release rotation of the rotor, respectively; and a friction member driving unit to drive the friction member. ### Claim 2 (depends on 1) The beam deflector of claim 1, further comprising a control unit to control the friction member driving unit to selectively contact and separate the friction member to and from the rotor if a rotor decelerating signal and a rotor driving signal are received from an outside control source. ### Claim 3 (depends on 2) The beam deflector of claim 2, wherein the friction member driving unit comprises: a lever to support the friction member and to move so that the friction member can contact to and be separated from the rotor, and an electromagnetic unit to drive the lever by means of a magnetic force. ### Claim 4 (depends on 3) The beam deflector of claim 3, wherein the friction member driving unit further comprises: an elastic member to elastically bias the lever away from the rotor, wherein the lever is formed of a metallic material. ### Claim 5 (depends on 4) The beam deflector of claim 4, wherein the friction member driving unit further comprises: a hinge pivot erected from the base, wherein the lever rotates about the hinge pivot. ### Claim 6 (depends on 3) The beam deflector of claim 3, wherein the friction member driving unit further comprises a permanent magnet coupled to the lever away from the friction member so as to cooperate with the electromagnetic unit to contact and separate the friction member to and from the rotor by means of magnetic attraction and repulsion. ### Claim 7 (depends on 6) The beam deflector of claim 6, wherein the friction member driving unit further comprises: a switching unit to switch an electric power supplied to the electromagnetic unit from an outside power supply to change a polarity of the electromagnetic unit; and wherein the control unit controls the switching unit so that the magnetic attraction and repulsion can be generated in response to the rotor decelerating signal and the rotor driving signal. ### Claim 8 (depends on 1) A light scanning unit, comprising: a beam deflector according to claim 1. ### Claim 9 An image forming apparatus, comprising: a light source; an image forming unit comprising a photosensitive body to form an image on a printing medium; and a beam deflector comprising: a base; a polygon mirror to reflect a light beam emitted from the light source toward the photosensitive body; a mirror driving unit comprising a rotor shaft erected from the base, and a rotor to support the polygon mirror and to rotate about the rotor shaft; a friction member to selectively contact and be separated from the rotor to obstruct and release rotation of the rotor, respectively; and a friction member driving unit to drive the friction member. ### Claim 10 (depends on 9) The image forming apparatus of claim 9, further comprising: a sensor to sense whether a printing operation of the image forming unit is complete; and a control unit to control the friction member driving unit so that the friction member contacts the rotor if the printing operation is complete and separates from the rotor during performance of the printing operation. ### Claim 11 (depends on 10) The image forming apparatus of claim 10, wherein the sensor comprises a medium discharge sensor to sense whether the printing medium is discharged. ### Claim 12 (depends on 10) The image forming apparatus of claim 10, wherein the friction member driving unit comprises: a lever to support the friction member and to move so that the friction member can contact to and be separated from the rotor, and an electromagnetic unit to drive the lever by means of a magnetic force. ### Claim 13 (depends on 12) The image forming apparatus of claim 12, wherein the friction member driving unit further comprises an elastic member to elastically bias the lever away from the rotor, wherein the lever is formed of a metallic material. ### Claim 14 (depends on 13) The image forming apparatus of claim 13, wherein the friction member driving unit further comprises a hinge pivot erected from the base, wherein the lever rotates about the hinge pivot. ### Claim 15 (depends on 12) The image forming apparatus of claim 12, wherein the friction member driving unit further comprises: a permanent magnet coupled to the lever away from the friction member so as to cooperate with the electromagnetic unit to contact and separate the friction member to and from the rotor by means of magnetic attraction and repulsion. ### Claim 16 (depends on 15) The image forming apparatus of claim 15, further comprising: a power supplying unit to supply an electric power to the electromagnetic unit; wherein the friction member driving unit further comprises a switching unit to switch the electric power supplied to the electromagnetic unit to change a polarity of the electromagnetic unit; and wherein the control unit controls the switching unit so that the magnetic attraction and repulsion can be respectively generated based on whether the printing operation is complete. ### Claim 17 An image forming apparatus to perform a printing operation, the image forming apparatus comprising: a light source to emit a light beam; a polygon mirror to reflect the light beam to a photosensitive body; a rotor to rotate the polygon mirror; and a friction member to contact the rotor to obstruct rotation of the rotor when the printing operation is complete, and to separate from the rotor during performance of the printing operation. ### Claim 18 (depends on 17) The image forming apparatus of claim 17, wherein the friction member contacts the rotor only after the last medium of a plurality of mediums has been printed thereon. ### Claim 19 (depends on 17) The image forming apparatus of claim 17, wherein the friction member absorbs vibrations from the rotor when the friction member contacts the rotor. ### Claim 20 A beam deflector, comprising: a polygon mirror to reflect a light beam; a mirror driving unit comprising a rotor shaft disposed through a central opening of the polygon mirror and a rotor to rotate the polygon mirror with respect to the rotor shaft; and a friction member to selectively contact or separate from the rotor to obstruct and release rotation of the rotor.