Image forming apparatus having recycling of residual toner

An image forming apparatus capable of conveying toner collected by cleaning means to a preselected position, comprising:

• toner conveying means comprising air stream conveying means and air feeding means for conveying the toner to the preselected position in a form of an air-toner mixture;
• and
• a hopper portion positioned upstream of said toner conveying means in an intended direction of toner conveyance for causing the toner to accumulate in said hopper portion by dropping into the hopper portion by its own weight;
• said toner conveying means being operated when the toner accumulating in said hopper portion reaches a preselected amount, wherein on the elapse of a preselected period of time since a start of operation said toner conveying means stops an operation of said air stream conveying means and then stops an operation of said air feeding means.

An image forming apparatus capable of conveying toner collected by cleaning means to a preselected position, comprising:

• toner conveying means comprising air stream conveying means, wherein said air stream conveying means comprises a screw pump, and air feeding means for conveying the toner to the preselected position in a form of an air-toner mixture;
• and
• a hopper portion positioned upstream of said toner conveying means in an intended direction of toner conveyance for causing the toner to accumulate in said hopper portion by dropping into the hopper portion by its own weight;
• wherein when a number of recording media to which images have been transferred reaches a preselected number, said toner conveying means is caused to operate, regarding that the toner accumulating in said hopper portion has reached the preselected amount, wherein said toner conveying means is caused to operate for a preselected period of time and then stop operating, and wherein on the elapse of the preselected period of time since a start of operation said toner conveying means stops an operation of said screw pump and then stops an operation of said air feeding means.

An image forming apparatus capable of conveying toner collected by cleaning means to a preselected position, comprising:

• toner conveying means comprising air stream conveying means and air feeding means for conveying the toner to the preselected position in a form of an air-toner mixture;
• and
• a hopper portion positioned upstream of said toner conveying means in an intended direction of toner conveyance for causing the toner to accumulate in said hopper portion by dropping into the hopper portion by its own weight;
• said toner conveying means being operated when the toner accumulating in said hopper portion is regarded as having reached a preselected amount, wherein on the elapse of a preselected period of time since a start of operation said toner conveying means stops an operation of said air stream conveying means and then stops an operation of said air feeding means.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein said air stream conveying means comprises a hollow cylindrical holder, a female screw type stator affixed within said holder, and a male screw type rotor rotatably received in said stator.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein said controller causes said air feeding means to start operating before causing said air stream conveying means to start operating, and then stop operating after a stop of operation of said air stream conveying means.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein said control means causes said toner conveying means to start operating at a timing adjustable in accordance with a size of the recording medium.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein when the size of the recording medium is smaller than a reference size, said air stream conveying means is driven at a same period as when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein when the size of the recording medium is greater than the reference size, said air stream conveying means is driven at a shorter period than when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein when the size of the recording medium is greater than the reference size, said air stream conveying means is driven at a period one-half shorter than when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process by dropping into the hopper portion by its own weight, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount,
• wherein when a jam sensor senses a jam, said control means causes said air stream conveying means to start conveying the toner or adjusts the timing for starting a toner carrying operation.

An image forming apparatus capable of collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means;
• and
• a first branch path branching off a part of said mixture delivery path having an upwardly extending portion extending from a lower position to an upper position;
• and
• a second branch path extending downward from a bottom of said upwardly extending portion of said first branch path to collect impurities from the air-toner mixture.

An image forming apparatus capable of collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means;
• and
• a branch path branching off a part of said mixture delivery path extending from a lower position to an upper position;
• wherein said air introducing means is caused to start introducing air prior to an air-toner mixture conveying operation to occur in said mixture delivery path.

An image forming apparatus capable of conveying toner collected by cleaning means to a preselected position, comprising:

• toner conveying means comprising air stream conveying means and air feeding means for conveying the toner to the preselected position in a form of an air-toner mixture;
• and
• a hopper portion positioned upstream of said toner conveying means in an intended direction of toner conveyance for causing the toner to accumulate in said hopper portion,
• said toner conveying means being operated when the toner accumulating in said hopper portion reaches a preselected amount, and
• wherein on the elapse of a preselected period of time since a start of operation said toner conveying means stops an operation of said air stream conveying means and then stops an operation of said air feeding means.

An image forming apparatus capable of conveying toner collected by cleaning means to a preselected position, comprising:

• toner conveying means comprising air stream conveying means and air feeding means for conveying the toner to the preselected position in a form of an air-toner mixture;
• and
• a hopper portion positioned upstream of said toner conveying means in an intended direction of toner conveyance for causing the toner to accumulate in said hopper portion;
• said toner conveying means being operated when the toner accumulating in said hopper portion is regarded as having reached a preselected amount, and
• wherein on the elapse of a preselected period of time since a start of operation said toner conveying means stops an operation of said screw pump and then stops an operation of said air feeding means.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• and
• wherein said air stream conveying means comprises a hollow cylindrical holder, a female screw type stator affixed within said holder, and a male screw type rotor rotatably received in said stator.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein said controller causes said air feeding means to start operating before causing said air stream conveying means to start operating, and then stop operating after a stop of operation of said air stream conveying means.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein said control means causes said toner conveying means to start operating at a timing adjustable in accordance with a size of the recording medium.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein when the size of the recording medium is smaller than a reference size, said air stream conveying means is driven at a same period as when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein when the size of the recording medium is greater than the reference size, said air stream conveying means is driven at a shorter period than when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein when the size of the recording medium is greater than the reference size, said air stream conveying means is driven at a period one-half shorter than when said size is coincident with said reference size.

An image forming apparatus including a toner recycling mechanism for collecting toner left on an image carrier after image transfer during an electrophotographic process, and returning said toner to developing means for reuse in a form of an air-toner mixture or conveying said toner to a waste toner container, said image forming apparatus comprising:

• image transferring means for transferring a toner image formed on the image carrier to a recording medium;
• cleaning means for collecting the toner left on the image carrier;
• air stream conveying means for mixing the toner with air and conveying said toner in the form of the air-toner mixture;
• air feeding means for feeding air for fluidizing the toner to be conveyed by said air stream conveying means;
• a mixture delivery path comprising an elastic tubing for delivering the air-toner mixture to the developing means or the waste toner container;
• sensing means for determining an amount of toner images formed;
• and
• control means for causing said air stream conveying means to start conveying the toner when said sensing means determines that the amount of toner images has reached a preselected amount;
• wherein when a jam sensor senses a jam, said control means causes said air stream conveying means to start conveying the toner or adjusts the timing for starting a toner conveying operation.