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An image-forming apparatus includes a movable lever which functions as a recording medium detector for detecting the passage of a recording medium and a temperature detecting portion provided on the movable lever. The temperature of the recording medium is detected without providing an additional sp

An image-forming apparatus includes a movable lever which functions as a recording medium detector for detecting the passage of a recording medium and a temperature detecting portion provided on the movable lever. The temperature of the recording medium is detected without providing an additional space for a sensor for detecting the temperature of the recording medium.

대표청구항 ▼

What is claimed is: 1. An image-forming apparatus comprising: an image-forming unit which forms an image on a recording medium; a temperature detector which detects a temperature of the recording medium; and a recording medium detector which detects a passage of the recording medium, said recording

What is claimed is: 1. An image-forming apparatus comprising: an image-forming unit which forms an image on a recording medium; a temperature detector which detects a temperature of the recording medium; and a recording medium detector which detects a passage of the recording medium, said recording medium detector including a moving member which moves when the recording medium comes into contact with said moving member, wherein a temperature detecting portion of said temperature detector is disposed on said moving member. 2. The apparatus according to claim 1, further comprising a fixing unit which fixes the image on the recording medium by applying heat, said fixing unit including a fixing nip portion which nips and conveys the recording medium, wherein said recording medium detector is disposed downstream of the fixing nip portion in a moving direction of the recording medium. 3. The apparatus according to claim 2, wherein the temperature detecting portion is disposed so as to come into contact with a surface of the recording medium opposite to a surface on which the image is formed in single-sided printing. 4. The apparatus according to claim 2, further comprising a conveying unit which conveys the recording medium, the conveying unit being disposed downstream of the fixing nip portion in the moving direction of the recording medium and being driven by a drive source, wherein said moving member comes into contact with the recording medium in a region between the fixing nip portion and a portion of said conveying unit nearest to the fixing nip portion in the moving direction of the recording medium. 5. The apparatus according to claim 4, further comprising a recording-medium guide member disposed between said fixing unit and said conveying unit, wherein a speed at which said conveying unit conveys the recording medium is higher than a speed at which said fixing unit conveys the recording medium, and wherein the recording medium does not comes into contact with said recording-medium guide member while the recording medium is retained by both said fixing unit and said conveying unit. 6. The apparatus according to claim 4, further comprising a recording-medium guide member disposed between said fixing unit and said conveying unit, wherein the temperature detecting portion is disposed so as to oppose said recording-medium guide member across an imaginary line connecting the fixing nip portion and a nip portion included in said conveying unit at least in a state in which a front end of the recording medium is not yet output from the fixing nip portion. 7. The apparatus according to claim 1, wherein said moving member moves from a home position to a temperature detection position when the recording medium comes into contact with said moving member, and returns to the home position when the recording medium separates from said moving member. 8. The apparatus according to claim 1, wherein said moving member tilts in a moving direction of the recording medium when the recording medium comes into contact with said moving member. 9. The apparatus according to claim 7, wherein electrodes of the temperature detecting portion are attached to said moving member, the electrodes serving a function of returning said moving member to the home position. 10. The apparatus according to claim 7, further comprising an urging member which urges said moving member toward the home position, wherein the temperature detecting portion is provided with electric wires which extend from the temperature detecting portion and disposed near a rotating shaft of said moving member. 11. The apparatus according to claim 2, further comprising a conveying unit which conveys the recording medium, said conveying unit being disposed downstream of the fixing nip portion in the moving direction of the recording medium and being driven by a drive source, wherein the temperature detecting portion is at an approximately the same position as a nip portion included in said conveying unit in the moving direction of the recording medium when said moving member is moved to a temperature position at which the temperature is detected. 12. The apparatus according to claim 1, wherein the temperature detecting portion includes a heat transmit plate which comes into contact with the recording medium at one side of the heat transmit plate and a temperature-detecting element disposed on the other side of the heat transmit plate. 13. The apparatus according to claim 12, wherein the heat transmit plate comprises metal. 14. The apparatus according to claim 12, wherein said moving member includes a resin base and the heat transmit plate is attached to the resin base. 15. The apparatus according to claim 2, wherein said fixing unit includes a heating unit and a back-up unit, said heating unit being disposed so as to face a surface of the recording medium on which the image is formed in single-sided printing. 16. The apparatus according to claim 2, wherein the apparatus determines a set temperature of said fixing unit on the basis of the temperature detected by said temperature detector. 17. The apparatus according to claim 15, wherein said heating unit includes a flexible sleeve and a heater which is in contact with an inner peripheral surface of said flexible sleeve and which is controlled so as to maintain a set temperature, wherein said back-up unit includes a pressure roller which is in contact with an outer peripheral surface of said flexible sleeve, said heater and said pressure roller defining the fixing nip portion with said flexible sleeve provided therebetween, and wherein the apparatus determines the set temperature of said heater on the basis of the temperature detected by the temperature detector. 18. A recording-medium-temperature detector unit for use in an image-forming apparatus which forms an image on a recording medium, said unit comprising: a movable lever which is composed of resin and which moves when the recording medium comes into contact with said movable lever; a temperature-detecting element provided on said movable lever; and an elastic conductive member provided on said movable lever and electrically connected to said temperature-detecting element, wherein said conductive member defines a signal path for said temperature-detecting element and applies an elastic force for urging said movable lever against the recording medium. 19. The detector unit according to claim 18, wherein said conductive member is formed integrally with said movable lever. 20. The detector unit according to claim 18, wherein said conductive member is a plate spring. 21. The detector unit according to claim 18, wherein said conductive member is a torsion coil spring. 22. The detector unit according to claim 18, wherein said conductive member has a crank shape. 23. The detector unit according to claim 18, further comprising a heat transmit plate provided on one side of said movable lever at a position such that said heat transmit plate comes into contact with the recording medium, wherein said temperature-detecting element is provided on the other side of said heat transmit plate. 24. The detector unit according to claim 18, wherein said detector unit serves a flag function for detecting the passage of the recording medium. 25. An image-forming apparatus comprising: an image-forming unit which forms an image on a recording medium; a movable lever which is composed of resin and which moves when the recording medium comes into contact with said movable lever; a heat transmit plate provided on said movable lever such that said heat transmit plate comes into contact with the recording medium at one side of said heat transmit plate; a temperature-detecting element provided on the other side of said heat transmit plate; and a conductive part which is electrically connected to a grounding path, said conductive part being positioned so as to prevent an electric discharge to said temperature-detecting element. 26. The apparatus according to claim 25, wherein said conductive part is electrically connected to said heat transmit plate. 27. The apparatus according to claim 25, further comprising a spring which electrically connects said conductive part to the grounding path. 28. The apparatus according to claim 27, wherein one end of the spring is connected to the grounding path so as to press the grounding path and the other end of the spring urges said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 29. The apparatus according to claim 25, wherein said conductive part comprises a spring, one end of the spring being connected to the grounding path so as to press the grounding path and the other end of the spring urging said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 30. The apparatus according to claim 25, wherein said heat transmit plate is disposed so as to come into contact with a surface of the recording medium opposite to a surface on which the image is formed in single-sided printing. 31. The apparatus according to claim 25, further comprising a fixing unit which fixes the image on the recording medium by applying heat, said fixing unit including a fixing nip portion which nips and conveys the recording medium, wherein said movable lever is disposed downstream of the fixing nip portion in a moving direction of the recording medium. 32. The apparatus according to claim 25, wherein said movable lever moves from a home position to a temperature detection position when the recording medium comes into contact with said movable lever, and returns to the home position when the recording medium separates from said movable member. 33. The apparatus according to claim 32, wherein electrodes of the temperature detecting portion are attached to said moving member, the electrodes serving a function of returning said moving member to the home position. 34. The apparatus according to claim 32, further comprising an urging member which urges said movable lever toward the home position, wherein said temperature-detecting element is provided with electric wires which extend from said temperature-detecting element and disposed near a rotating shaft of said moving member. 35. The apparatus according to claim 31, wherein said fixing unit includes a heating unit and a back-up unit, said heating unit being disposed so as to face a surface of the recording medium on which the image is formed in single-sided printing. 36. An image-forming apparatus comprising: an image-forming unit which forms an image on a recording medium; a movable lever which is composed of resin and which moves when the recording medium comes into contact with said movable lever; a heat transmit plate provided on said movable lever such that the heat transmit plate comes into contact with the recording medium at one side of said heat transmit plate; a temperature-detecting element provided on the other side of said heat transmit plate; and a conductive part electrically connected to both said heat transmit plate and a grounding path. 37. The apparatus according to claim 36, further comprising a spring which electrically connects said conductive part to the grounding path. 38. The apparatus according to claim 37, wherein one end of the spring is connected to the grounding path so as to press the grounding path and the other end of the spring urges said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 39. The apparatus according to claim 36, wherein said conductive part comprises a spring, one end of the spring being connected to the grounding path so as to press the grounding path and the other end of the spring urging said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 40. The apparatus according to claim 36, wherein said heat transmit plate is disposed so as to come into contact with a surface of the recording medium opposite to a surface on which the image is formed in single-sided printing. 41. A recording-medium-temperature detector unit for use in an image-forming apparatus which forms an image on a recording medium, the detector unit comprising: a movable lever which is composed of resin and which moves when the recording medium comes into contact with said movable lever; a heat transmit plate provided on said movable lever such that said heat transmit plate comes into contact with the recording medium at one side of said heat transmit plate; a temperature-detecting element provided on the other side of said heat transmit plate; and a conductive part which is electrically connected to a grounding path, said conductive part being positioned so as to prevent an electric discharge to said temperature-detecting element. 42. The detector unit according to claim 41, wherein said conductive part is electrically connected to said heat transmit plate. 43. The detector unit according to claim 41, further comprising a spring which electrically connects said conductive part to the grounding path. 44. The detector unit according to claim 43, wherein one end of the spring is connected to the grounding path so as to press the grounding path and the other end of the spring urges said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 45. The detector unit according to claim 41, wherein said conductive part comprises a spring, one end of the spring being connected to the grounding path so as to press the grounding path and the other end of the spring urging said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 46. A recording-medium-temperature detector unit for use in an image-forming apparatus which forms an image on a recording medium, the detector unit comprising: a movable lever which is composed of resin and which moves when the recording medium comes into contact with said movable lever; a heat transmit plate provided on said movable lever such that said heat transmit plate comes into contact with the recording medium at one side of said heat transmit plate; a temperature-detecting element provided on the other side of said heat transmit plate; and a conductive part electrically connected to both said heat transmit plate and a grounding path. 47. The detector unit according to claim 46, further comprising a spring which electrically connects said conductive part to the grounding path. 48. The detector unit according to claim 47, wherein one end of the spring is connected to the grounding path so as to press the grounding path and the other end of the spring urges said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever. 49. The detector unit according to claim 46, wherein said conductive part comprises a spring, one end of the spring being connected to the grounding path so as to press the grounding path and the other end of the spring urging said movable lever in a direction opposite to the direction in which said movable lever moves when the recording medium comes into contact with said movable lever.