Image forming apparatus

Claim 2

An image forming apparatus comprising: a delivery passage for copy paper on which an image is to be reproduced; first copy paper detector means disposed along said delivery passage; second copy paper detector means disposed downstream of said first copy paper detector means in said delivery passage and separated by a distance l from said first copy paper detector means; timer means for counting a period of time between the ON-operation of said first copy paper detector means by copy paper to be delivered and the ON-operation of said second copy paper detector means, said timer means being adapted to supply a signal if said second copy paper detector means does not supply an ON-signal within a preset time T; size data output means for supplying copy paper size data including the length L of the copy paper to be delivered; jam occurrence place judging means for: examining the status of said first copy paper detector means if said timer means supplies a signal, so as to judge that a copy paper jam has happened between said first copy paper detector means and said second copy paper detector means if said first copy paper detector means is OFF; and further comparing said distance l with the data of copy paper length L supplied from said size data output means if said first copy paper detector means is ON, so as to judge that a copy paper jam has happened upstream of said first copy paper detector means in said delivery passage if said distance l is equal to or greater than said length L, and judge that a copy paper jam has happened between said first copy paper detector means and said second copy paper detector means if said distance l is smaller than said length L; and, means for displaying the results of the jam occurrence place judging.

Claim 3

An image forming apparatus comprising: a delivery passage for copy paper on which an image is to be reproduced; an image forming processing section and a fixing processing section disposed, in this order, along said delivery passage; a first sensor disposed upstream of said image forming processing section in said delivery passage for detecting the passage of the copy paper; a second sensor disposed between said image forming processing section and said fixing processing section in said delivery passage and separated by a distance l 1 from said first sensor; a third sensor disposed downstream of said fixing processing section in said delivery passage and separated by a distance l 2 from said second sensor; a first timer for counting a period of time between the ON-operation of said first sensor by copy paper to be delivered to said image forming processing section in predetermined timing and the ON-operation of said second sensor, said first timer being adapted to supply a signal if said second sensor does not supply a signal within a preset time T1; a second timer for counting a period of time between the ON-operation of said second sensor and the ON-operation of said third sensor, said second timer being adapted to supply a signal if said third sensor does not supply an ON-signal within a preset time T2; size data output means for supplying copy paper size data including the length L of the copy paper to be delivered; first jam occurrence place judging means for: examining the status of said first sensor if said first timer means supplies a signal, so as to judge that a copy paper jam has happened in said image forming processing section if said first sensor is OFF; and further comparing said distance l 1 with the data of copy paper length L supplied from said size data output means if said first sensor is ON, so as to judge that a copy paper jam has happened upstream of said image forming processing section in said delivery passage if said distance l 1 is equal to or greater than said length L, and judge that a copy paper jam has happened in said image forming processing section if said distance l 1 is smaller than said length L; second jam occurrence place judging means for; examining the status of said first and second sensors if said second timer supplies a signal, so as to judge that a copy paper jam has happened in said fixing processing section if both said first and second sensors are OFF; further comparing said distance l 2 with said copy paper length L if said first sensor is OFF and said second sensor is ON, so as to judge that a copy paper jam has happened in said image forming processing section if said distance l 2 is equal to or greater than said length L; and judge that a copy paper jam has happened in said fixing processing section if said distance l 2 is smaller than said length L; further comparing said copy paper length L with said distance l 1 if said first sensor is ON, so as to judge that a copy paper overlap jam has happened upstream of said image forming processing section if said distance l 1 is equal to or greater than said length L, and judge that a copy paper jam has happened in said image forming processing section if said distance l 1 is smaller than said length L; and, means for displaying the results of the jam occurrence place judging.

Claim 4

An image forming apparatus comprising: a delivery passage for copy paper on which an image is to be reproduced; an image forming processing section and a fixing processing section disposed, in this order, along said delivery passage; a first sensor disposed upstream of said image forming processing section in said delivery passage for detecting the passage of the copy paper; a second sensor disposed between said image forming processing section and said fixing processing section in said delivery passage and separated by a distance l 1 from said first sensor; a third sensor disposed downstream of said fixing processing section in said delivery passage and separated by a distance l 2 from said second sensor; a first timer for counting a period of time between the ON-operation of said first sensor by copy paper to be delivered to said image forming processing section in predetermined timing and the ON-operation of said second sensor, said first timer being adapted to supply a signal if said second sensor does not supply a signal within a preset time T1; a second timer for counting a period of time between the ON-operation of said second sensor and the ON-operation of said third sensor, said second timer being adapted to supply a signal if said third sensor does not supply an ON-signal within a preset time T2; size data output means for supplying copy paper size data including the length L of the copy paper to be delivered; first jam occurrence place judging means for: examining the status of said first sensor if said first timer means supplies a signal, so as to judge that a copy paper jam has happened in said image forming processing section if said first sensor is OFF; and further comparing said distance l 1 with the data of copy paper length L supplied from said size data output means if said first sensor is ON, so as to judge that a copy paper jam has happened upstream of said image forming processing section in said delivery passage if said distance l 1 is equal to or greater than said length L, and judge that a copy paper jam has happened in said image forming processing section if said distance l 1 is smaller than said length L; second jam occurrence place judging means for; examining the status of said first and second sensors if said second timer supplies a signal, so as to judge that a copy paper jam has happened in said fixing processing section if both said first and second sensors are OFF; further comparing said distance l 2 with said copy paper length L if said first sensor is OFF and said second sensor is ON, so as to judge that a copy paper jam has happened in said image forming processing section if said distance l 2 is equal to or greater than said length L; and judge that a copy paper jam has happened in said fixing processing section if said distance l 2 is smaller than said length L; further comparing said copy paper length L with said distance l 1 if said first sensor is ON, so as to judge that a copy paper overlap jam has happened upstream of said image forming processing section if said distance l 1 is equal to or greater than said length L, and judge that a copy paper jam has happened in said image forming processing section if said distance l 1 is smaller than said length L; and, means for displaying the results of the jam occurrence place judging.