Image forming apparatus with change unit for changing temperature of fixing unit at time of actuating image forming unit

Abstract

An image forming apparatus capable of performing can perform an image forming operation together with temperature rise by heating of a heat fixing apparatus operation to ensure a good fixability and a shortest short first print out time and to prevent loss of while minimizing power consumption without and not over-burdening a constitutional member of the image forming apparatus (e.g., life-shortening shortening the life of the constitutional member)is provided. The image forming apparatus includes an image forming unit and a fixing apparatus unit for heat-fixing a toner image on a recording material and a detection member for detecting a toner of a fixing apparatus member and performs simultaneously temperature rise by heating of the fixing apparatus and an image forming operation including a pre-process and an image forming sequence. In the image forming apparatus, a start A fixing temperature of the pre-process and a start temperature of the image forming sequence with respect to the fixing apparatus member are unit is made variable depending on whether full-color image formation is performed or mono-color image formation is performed.

What is claimed is: 
     
       1. An image forming apparatus comprising:
 an image forming unit for forming a toner image of a plurality of colors and a toner image of a predetermined single color on a recording material; 
 a fixing unit for heat fixing the toner image formed on the recording material; 
 an actuation unit for actuating said image forming unit in a state in which a temperature of said fixing unit is lower than a toner image fixing temperature in a case of forming the toner image of the plurality of colors and in the a case of forming the toner image of the predetermined single color; and 
 a change unit for changing a the toner image fixing temperature of said fixing unit at the time of actuating said image forming unit in the case of forming the toner image of the plurality of colors and in the case of forming the toner image of the predetermined single color. 
 
     
     
       2. An apparatus according to  claim 1 , wherein a difference between the toner image fixing temperature of said fixing unit and the temperature of said fixing unit at the time of actuating said image forming unit is smaller in the case of forming the toner image of the predetermined single color than in the case of forming the toner image of the plurality of colors. 
     
     
       3. An apparatus according to  claim 1 , wherein the temperature of said fixing unit at the time of actuating said image forming unit is higher in the case of forming the toner image of the predetermined single color than in the case of forming the toner image of the plurality of colors. 
     
     
       4. An apparatus according to  claim 1 , wherein said image forming unit includes a plurality of photosensitive members on which a toner image is to be formed, and said change unit changes rotation start timing of a photosensitive member on which the toner image of the predetermined single color is to be formed. 
     
     
       5. An apparatus according to  claim 1 , wherein said image forming unit includes a photosensitive member and a plurality of image forming portions for forming a toner image on the photosensitive member, and said change unit changes rotation start timing of the photosensitive member. 
     
     
       6. An apparatus according to  claim 1 , wherein the predetermined single color is achromatic color. 
     
     
       7. An apparatus according to  claim 1 , wherein said image forming unit includes a conveyance unit for conveying the recording material toward said fixing unit, and said change unit changes actuation timing of said conveyance unit depending on a detection temperature of said fixing unit. 
     
     
       8. An apparatus according to  claim 1 , wherein said fixing unit is kept at different temperatures between the case of forming the toner image of the plurality of colors and the case of forming the toner image of the predetermined single color. 
     
     
       9. An image forming apparatus comprising:
 image forming means, including a plurality of image bearing members, capable of forming a full-color image and a monochromatic image on a recording material;   fixing means for fixing the image on the recording material by heating the image at a preset temperature;   temperature detecting means for detecting a temperature of said fixing means;   temperature control means for controlling the temperature of said fixing means on the basis of an output of said temperature detecting means;   image formation control means for controlling said image forming means so as to start an image forming step of forming, when an image forming signal is input, the image on at least one of the image bearing members on the basis of the input image forming signal after a pre-process is performed;   actuation means for actuating said image forming means so that (1) in a case that an image forming signal of a full-color image forming mode is input, the pre-process is started when the detected temperature reaches a first pre-process start temperature and the image forming step is started when the detected temperature reaches a first toner image fixing temperature, and (2) in a case that an image forming signal of a monochromatic image forming mode is input, the pre-process is started when the detected temperature reaches a second pre-process start temperature, which is higher than the first pre-process start temperature, and the image forming step is started when the detected temperature reaches a second toner image fixing temperature, which is lower than the first toner image fixing temperature; and   change means for changing the first pre-process start temperature, the first toner image fixing temperature, the second pre-process start temperature, and the second toner image fixing temperature,   wherein the first pre-process start temperature is lower than the first toner image fixing temperature, and the second pre-process start temperature is lower than the second toner image fixing temperature.    
     
     
       10. An apparatus according to claim 9, further comprising change means for changing the first pre-process start temperature or the second pre-process start temperature depending on the detected temperature during the input of the image forming signal so that the first pre-process start temperature or the second pre-process start temperature is lower with a higher detected temperature during the input of the image forming signal.  
     
     
       11. An apparatus according to claim 9, further comprising change means for changing the first toner image fixing temperature or the second toner image fixing temperature depending on the detected temperature during the input of the first toner image forming signal so that the first toner image fixing temperature or the second toner image fixing temperature is lower with a higher detected temperature during the input of the image forming signal.  
     
     
       12. An apparatus according to claim 9, further comprising change means for changing the first pre-process start temperature or the second pre-process start temperature depending on an image heating temperature so that the first pre-process start temperature or the second pre-process start temperature is higher with a higher image heating temperature.  
     
     
       13. An apparatus according to claim 9, further comprising change means for changing the first toner image fixing temperature or the second toner image fixing temperature depending on an image heating temperature so that the first toner image fixing temperature or the second toner image fixing temperature is lower with a higher image heating temperature.  
     
     
       14. An apparatus according to claim 9, further comprising change means for changing the first pre-process start temperature or the second pre-process start temperature depending on an image forming speed so that the first pre-process start temperature or the second pre-process start temperature is higher with a higher image forming speed.  
     
     
       15. An apparatus according to claim 9, further comprising change means for changing the first toner image fixing temperature or the second toner image fixing temperature depending on an image forming speed so that the first toner image fixing temperature or the second toner image fixing temperature is higher with a higher image forming speed.  
     
     
       16. An apparatus according to claim 9, wherein the first toner image fixing temperature at which a toner image is fixed on the recording material in the case of the full-color image forming mode is equal to the second toner image fixing temperature at which a toner image is fixed on the recording material in the case of the monochromatic image forming mode. 
     
     
       17. An apparatus according to claim 9, wherein the first toner image fixing temperature at which a toner image is fixed on the recording material in the case of the full-color image forming mode is higher than the second toner image fixing temperature at which a toner image is fixed on the recording material in the case of the monochromatic image forming mode.  
     
     
       18. An image forming apparatus comprising:
 image forming means, including a plurality of image bearing members, capable of forming a full-color image and a monochromatic image on a recording material;   fixing means for fixing the image on the recording material by heating the image at a preset temperature;   temperature detecting means for detecting a temperature of said fixing means;   temperature control means for controlling the temperature of said fixing means on the basis of an output of said temperature detecting means;   image formation control means for controlling said image forming means so as to start an image forming step of forming, when an image forming signal is input, the image on at least one of the image bearing members on the basis of the input image forming signal after a pre-process is performed;   actuation means for actuating said image forming means so that (1) in a case that an image forming signal of a full-color image forming mode is input, the pre-process is started when the detected temperature reaches a first pre-process start temperature and the image forming step is started when the detected temperature reaches a first toner image fixing temperature, and (2) in a case that an image forming signal of a monochromatic image forming mode is input, the pre-process is started when the detected temperature reaches a second pre-process start temperature and the image forming step is started when the detected temperature reaches a second toner image fixing temperature, which is higher than the first toner image fixing temperature; and   change means for changing the first toner image fixing temperature and the second toner image fixing temperature,   wherein the first and second pre-process start temperatures are lower than the first toner image fixing temperature and the second toner image fixing temperature.   
     
     
       19. An apparatus according to claim 18, wherein the first toner image fixing temperature at which a toner image is fixed on the recording material in the case of the full-color image forming mode is equal to the second toner image fixing temperature at which a toner image is fixed on the recording material in the case of the monochromatic image forming mode. 
     
     
       20. An apparatus according to claim 18, wherein the first toner image fixing temperature at which a toner image is fixed on the recording material in the case of the full-color image forming mode is higher than the second toner image fixing temperature at which a toner image is fixed on the recording material in the case of the monochromatic image forming mode. 
     
     
       21. An image forming apparatus comprising:
 an image forming device configured to form a monochromatic toner image on a recording material in a monochromatic mode and a full-color toner image on the recording material in a full-color mode;   a fixing device configured to fix the toner image on the recording material;   a temperature detector configured to detect a temperature of said fixing device;   a temperature controller configured to control the temperature of said fixing device based on an output of said temperature detector, said temperature controller raising the temperature of said fixing device up to a target temperature in the monochromatic mode and the full-color mode when an image formation is started; and   an actuation controller configured to actuate said image forming device before the temperature of said fixing device reaches the target temperature,   wherein said actuation controller starts an actuation of said image forming device when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts an actuation of said image forming device when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       22. An apparatus according to claim 21, wherein said image forming device includes a plurality of photosensitive members, and said actuation controller controls a rotation start timing, as an actuation start timing, of said photosensitive members.  
     
     
       23. An apparatus according to claim 21, wherein said image forming device includes a single photosensitive member and a plurality of developing devices, and said actuation controller controls a rotation start timing, as an actuation start timing, of said single photosensitive member.  
     
     
       24. An apparatus according to claim 21, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion.  
     
     
       25. An apparatus according to claim 24, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       26. An apparatus according to claim 22, wherein said image forming device includes an intermediary transfer member,
 wherein in the monochromatic mode, the monochromatic toner image is formed on said intermediary transfer member by one of said photosensitive members, and then the monochromatic toner image on said intermediary transfer member is transferred to the recording material, and   wherein in the full-color mode, the full-color toner image is formed on said intermediary transfer member by said photosensitive members, and then the full-color toner image on said intermediary transfer member is transferred to the recording material.    
     
     
       27. An image forming apparatus comprising:
 an image forming device configured to form a monochromatic toner image on a recording material in a monochromatic mode and a full-color toner image on the recording material in a full-color mode;   a fixing device configured to fix the toner image on the recording material;   a temperature detector configured to detect a temperature of said fixing device;   a temperature controller configured to control the temperature of said fixing device based on an output of said temperature detector, said temperature controller raising the temperature of said fixing device up to respective target temperatures in the monochromatic mode and the full-color mode when an image formation is started; and   an actuation controller configured to actuate said image forming device before the temperature of said fixing device reaches the respective target temperatures,   wherein said actuation controller starts an actuation of said image forming device when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts an actuation of said image forming device when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       28. An apparatus according to claim 27, wherein said image forming device includes a plurality of photosensitive members, said actuation controller controls a rotation start timing, as an actuation start timing, of said photosensitive members. 
     
     
       29. An appaatus according to claim 27, wherein said image forming device includes a single photosensitive member and a plurality of developing devices, and said actuation controller controls a rotation start timing, as an actuation start timing, of said single photosensitive member. 
     
     
       30. An apparatus according to claim 27, wherein the target temperature of said fixing device in the full-color mode is higher than the target temperature of said fixing device in the monochromatic mode. 
     
     
       31. An apparatus according to claim 27, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion.  
     
     
       32. An apparatus according to claim 31, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       33. An apparatus according to claim 28, wherein said image forming device includes an intermediary transfer member,
 wherein in the monochromatic mode, the monochromatic toner image is formed on said intermediary transfer member by one of said photosensitive members, and then the monochromatic toner image on said intermediary transfer member is transferred to the recording material, and   wherein in the full-color mode, the full-color toner image is formed on said intermediary transfer member by said photosensitive members, and then the full-color toner image on said intermediary transfer member is transferred to the recording material.    
     
     
       34. An image forming apparatus comprising:
 four image forming units configured to form a yellow toner image, a magenta toner image, a cyan toner image and a black toner image, respectively;   an intermediary transfer member configured to receive (i) a full-color image including the yellow toner image, the magenta toner image, the cyan toner image and the black toner image transferred from said four image forming units to transfer the full-color image onto a recording material in a full-color mode, and (ii) a monochromatic image including the black toner image transferred from one of said four image forming units to transfer the monochromatic image on the recording material in a monochromatic mode;   a fixing device configured to (i) fix the full-color image on the recording material in the full-color mode, and (ii) fix the monochromatic image on the recording material in the monochromatic mode;   a temperature detecting portion configured to detect a temperature of said fixing device;   a temperature controlling portion configured to control the temperature of said fixing device based on an output of said temperature detecting portion, said temperature controlling portion raising the temperature of said fixing device up to a target temperature in the full-color mode and the monochromatic mode when an image formation is started; and   an actuation controlling portion configured to actuate said four image forming units before the temperature of said fixing device reaches the target temperature,   wherein said one of said four image forming units is disposed at a most downstream position relative to the other three image forming units in a moving direction of said intermediary transfer member, and   wherein said actuation controlling portion starts an actuation of said four image forming units when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts an actuation of one of said four image forming units when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       35. An apparatus according to claim 34, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion. 
     
     
       36. An apparatus according to claim 35, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       37. An apparatus according to claim 35, wherein said temperature detecting portion detects a temperature of said endless belt as the temperature of said fixing device.  
     
     
       38. An apparatus according to claim 34, wherein said fixing device includes a roller configured to heat the toner image on the recording material in a nip portion.  
     
     
       39. An apparatus according to claim 38, wherein said temperature detecting portion detects a temperature of said roller as the temperature of said fixing device.  
     
     
       40. An image forming apparatus comprising:
 a first image forming unit, provided with a first photosensitive member, configured to form a yellow toner image on said first photosensitive member;   a second image forming unit, provided with a second photosensitive member, configured to form a magenta toner image on said second photosensitive member;   a third image forming unit, provided with a third photosensitive member, configured to form a cyan toner image on said third photosensitive member;   a fourth image forming unit, provided with a fourth photosensitive member, configured to form a black toner image on said fourth photosensitive member;   an intermediary transfer member configured to receive (i) a full-color image including the yellow toner image, the magenta toner image, the cyan toner image and the black toner image transferred from said first, second, third and fourth photosensitive members to transfer the full-color image onto a recording material in a full-color mode, and (ii) a monochromatic image including the black toner image transferred from said fourth photosensitive member to transfer the monochromatic image on the recording material in a monochromatic mode;   a fixing device configured to (i) fix the full-color image on the recording material in the full-color mode, and (ii) fix the monochromatic image on the recording material in the monochromatic mode;   a temperature detecting portion configured to detect a temperature of said fixing device;   a temperature controlling portion configured to control the temperature of said fixing device based on an output of said temperature detecting portion, said temperature controlling portion raising the temperature of said fixing device up to a target temperature in the full-color mode and the monochromatic mode when an image formation is started; and   an actuation controlling portion configured to actuate said first, second, third and fourth photosensitive members before the temperature of said fixing device reaches the target temperature,   wherein said fourth photosensitive member is disposed at a most downstream position relative to said first, second, and third photosensitive members in a moving direction of said intermediary transfer member, and   wherein said actuation controlling portion starts rotation of said first, second, third and fourth photosensitive members when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts rotation of said fourth photosensitive member when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       41. An apparatus according to claim 40, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion.  
     
     
       42. An apparatus according to claim 41, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       43. An apparatus according to claim 41, wherein said temperature detecting portion detects a temperature of said endless belt as the temperature of said fixing device.  
     
     
       44. An apparatus according to claim 40, wherein said fixing device includes a roller configured to heat the toner image on the recording material in a nip portion.  
     
     
       45. An apparatus according to claim 44, wherein said temperature detecting portion detects a temperature of said roller as the temperature of said fixing device.  
     
     
       46. An image forming apparatus comprising:
 four image forming units configured to form a yellow toner image, a magenta toner image, a cyan toner image and a black toner image, respectively;   an intermediary transfer member configured to receive (i) a full-color image including the yellow toner image, the magenta toner image, the cyan toner image and the black toner image transferred from said four image forming units to transfer the full-color image onto a recording material in a full-color mode, and (ii) a monochromatic image including the black toner image transferred from one of said four image forming units to transfer the monochromatic image on the recording material in a monochromatic mode;   a fixing device configured to (i) fix the full-color image on the recording material in the full-color mode, and (ii) fix the monochromatic image on the recording material in the monochromatic mode;   a temperature detecting portion configured to detect a temperature of said fixing device;   a temperature controlling portion configured to control the temperature of said fixing device based on an output of said temperature detecting portion, said temperature controlling portion raising the temperature of said fixing device up to respective target temperatures in the full-color mode and the monochromatic mode when an image formation is started; and   an actuation controlling portion configured to actuate said four image forming units before the temperature of said fixing device reaches the respective target temperature,   wherein said one of said four image forming units is disposed at a most downstream position relative to the other three image forming units in a moving direction of said intermediary transfer member, and   wherein said actuation controlling portion starts an actuation of said four image forming units when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts an actuation of one of said four image forming units when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       47. An apparatus according to claim 46, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion.  
     
     
       48. An apparatus according to claim 47, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       49. An apparatus according to claim 47, wherein said temperature detecting portion detects a temperature of said endless belt as the temperature of said fixing device.  
     
     
       50. An apparatus according to claim 46, wherein said fixing device includes a roller configured to heat the toner image on the recording material in a nip portion.  
     
     
       51. An apparatus according to claim 50, wherein said temperature detecting portion detects a temperature of said roller as the temperature of said fixing device.  
     
     
       52. An image forming apparatus comprising:
 a first image forming unit, provided with a first photosensitive member, configured to form a yellow toner image on said first photosensitive member;   a second image forming unit, provided with a second photosensitive member, configured to form a magenta toner image on said second photosensitive member;   a third image forming unit, provided with a third photosensitive member, configured to form a cyan toner image on said third photosensitive member;   a fourth image forming unit, provided with a fourth photosensitive member, configured to form a black toner image on said fourth photosensitive member;   an intermediary transfer member configured to receive (i) a full-color image including the yellow toner image, the magenta toner image, the cyan toner image and the black toner image transferred from said first, second, third and fourth photosensitive members to transfer the full-color image onto a recording material in a full-color mode, and (ii) a monochromatic image including the black toner image transferred from said fourth photosensitive member to transfer the monochromatic image on the recording material in a monochromatic mode;   a fixing device configured to (i) fix the full-color image on the recording material in the full-color mode, and (ii) fix the monochromatic image on the recording material in the monochromatic mode;   a temperature detecting portion configured to detect a temperature of said fixing device;   a temperature controlling portion configured to control the temperature of said fixing device based on an output of said temperature detecting portion, said temperature controlling portion raising the temperature of said fixing device up to respective target temperatures in the full-color mode and the monochromatic mode when an image formation is started; and   an actuation controlling portion configured to actuate said first, second, third and fourth photosensitive members before the temperature of said fixing device reaches the respective target temperature,   wherein said fourth photosensitive member is disposed at a most downstream position relative to said first, second, and third photosensitive members in a moving direction of said intermediary transfer member, and   wherein said actuation controlling portion starts rotation of said first, second, third and fourth photosensitive members when the detected temperature of said fixing device reaches a first temperature in the full-color mode, and starts rotation of said fourth photosensitive member when the detected temperature of said fixing device reaches a second temperature, which is higher than the first temperature, in the monochromatic mode.    
     
     
       53. An apparatus according to claim 52, wherein said fixing device includes an endless belt configured to heat the toner image on the recording material in a nip portion.  
     
     
       54. An apparatus according to claim 53, wherein said fixing device includes a heating member configured to heat the toner image on the recording material through said endless belt in the nip portion.  
     
     
       55. An apparatus according to claim 53, wherein said temperature detecting portion detects a temperature of said endless belt as the temperature of said fixing device.  
     
     
       56. An apparatus according to claim 52, wherein said fixing device includes a roller configured to heat the toner image on the recording material in a nip portion.  
     
     
       57. An apparatus according to claim 56, wherein said temperature detecting portion detects a temperature of said roller as the temperature of said fixing device.