Mechanism for cooling photosensitive materials in an electrophotographic copying machine

Abstract

A mechanism for cooling photosensitive materials in an electrophotographic copying machine, comprising cooling means for blowing a first air stream onto the surface of a photosensitive material, air directing means for producing a second air stream directed through a thermal fixing device, said second air stream directed through a thermal fixing device, said second air stream operating also to draw the first air stream into and through the fixing device, and ventilator means for collecting and discharging the air streams produced by the cooling means and the air directing means out of the copying machine after passing through the fixing device.

Description

BACKGROUND OF INVENTION

The present invention relates to a mechanism for cooling photosensitive materials in an electrophotographic copying machine. More precisely, it relates to a mechanism for cooling photosensitive materials in a copying machine by providing a cooling device for actively blowing air from outside the machine onto the surface of photosensitive material and a ventilating device for drawing the heated air generated by a thermofixing device away from the photosensitive materials and discharging it to the outside of the machine.

HAS ELECTROGRAPHIC COPY MACHINES USING PHOTOSENSITIVE MATERIALS EASILY DAMAGED BY HEAT IN COMBINATION WITH FIXING ARRANGEMENTS WHICH PRODUCE LARGE AMOUNTS OF HEAT IT HAS HERETOFORE BEEN REQUIRED TO PROVIDE SOME MEANS FOR MAINTAINING THE PHOTOSENSITIVE MATERIAL AT AN ACCEPTABLE TEMPERATURE. For this purpose, the photosensitive material in some prior art copy machines has been insulated from the thermofixing device by providing an air curtain therebetween or by directing air toward both the photosensitive materials and the thermofixing device from a blower located therebetween. In these prior art arrangements, however, it is difficult to select the direction and the strength of air flow. In addition, as the flow of cooling air is substantial, the efficiency of the thermofixing device is apt to decrease, and the heat emanating therefrom tends to be drawn in the direction of the photosensitive material.

OBJECTS AND SUMMARY OF THE INVENTION

The invention therefore has the primary object of providing an arrangement for cooling photosensitive materials to more effectively protect them from a heat generating fixing device in the environment of an electrophotographic copy machine.

This object and others is accomplished by providing a mechanism for cooling photosensitive materials in an electrophotographic copying machine, comprising cooling means for blowing a first air stream onto the surface of a photosensitive material, air directing means for producing a second air stream directed through a thermal fixing device, said second air stream operating also to draw the first air stream into and through the fixing device, and ventilator for collecting and discharging the air streams produced by the cooling means and the air directing means out of the copying machine after passing through the fixing device.

BRIEF DESCRIPTION OF THE DRAWING

The drawing is an illustrative side view of the cooling arrangement of the invention.

DETAILED DESCRIPTION

The invention will now be described in detail by reference to the drawing which is an illustrative side view of the cooling arrangement of the present invention. Referring to the drawing, there is illustratively shown an electrophotographic copy machine comprising an enclosure 30 in which is located adjacent one side thereof a photosensitive material 1 carried on an rotatable drum. By rotating the drum, the material 1 is processed through a pre-exposure charging station 2, exposure station 3 and a developing station 4 in conventional fashion to form a toner image on the surface of the photosensitive material 1. This toner image is then transferred from the photosensitive material 1 to a transfer or copy paper 6 by a transfer corotron 5 and fixed on the transfer paper 6 by a fixing device 7. The fixing arrangement 7 is spaced from the photosensitive material 1 in the direction of travel of the copy paper 6 and comprises a conventional thermal fuser which is open at opposite ends thereof to permit entrance and egress of the copy paper 6. After transfer of the toner image to the copy paper 6 the drum is successively expored to a preclean corotron station 21 and a cleaning station 9 which removes excess toner from the photosensitive material 1 prior to exposure to another image.

In order to cool the photosensitive material 1, the present invention provides a cooling device 8 including a nozzle 10 for directing an air stream into contact with the surface of the photosensitive material 1, between the charging station 2 and a cleaning station 9. The nozzle 10 is connected to a blower 11 via a duct 12. The blower 11 has an intake opening exiting to the exterior of the machine and is designed to take air from outside of the copying machine and direct it onto the surface of the photosensitive material 1 via the nozzle 10.

A stream directing device 13 is also provided for directing a second air stream through the fuser 7 in the direction of paper travel. The second air stream emitted by the device 13 also serves to draw the air stream generated by the cooling device 8 around the drum photosensitive material 1 into the fuser 7. The stream-directing device 13 comprises a square tube 15 terminating in a nozzle 14 and connected to a blower 17 via a duct 16. The duct 16 is coupled to the exterior of the machine enclosure so that the blower 17 operates to draw air from outside the machine and direct it through the nozzle 14.

The nozzle 14 is located adjacent to the entrance opening in the fuser 7 and is oriented in a direction so as to direct air into the opening and through the fuser 7. The movement of the air from nozzle 14 also causes the air surrounding the photosensitive material 1, including the air emitted by nozzle 10, to be drawn toward, into and through the fuser 7. The velocity of the air exiting the nozzle 14 is relatively small compared with the velocity of the air stream from nozzle 10.

A ventilator 18 having its intake opening located adjacent to the exit opening of the fuser 7 is provided for withdrawing the air within the fuser 7 (including air provided by the nozzles 10 and 14) and discharging it to the exterior of the machine enclosure. The ventilator 18 includes a duct 19, a blower 20 and a discharge duct (not shown), which is coupled to the exterior of the machine enclosure

With the cooling arrangement as described above, a series of air streams are generated which reduce the influence of the heat generated by the fixing device 7 on the photosensitive material 1.

The cooling device 8, stream directing device 18 and ventilating device 20 also serve in combination to reduce the amount of ozone generated from the transfer corotron 5 and the pre-clean corotron 21 by drawing it into the fuser 7 by means of the above-described series of air streams, to thereby decompose this ozone by heating it.

By using the cooling arrangement of this invention, the temperature of the surface of the photosensitive material may be reduced from approximately 50.degree.C (as is the usual case in conventional copy machines) to a temperature below 40.degree.C. Similarly, the temperature around the photosensitive material may be reduced below 60.degree.C using the cooling arrangement of the present invention as compared with 80.degree.C in the conventional arrangements.

In addition, by introducing an air stream into the fuser, the temperature thereacross may be made more uniform than in prior art machines. For example, in conventional machines, the central portion of the fuser is ordinarily approximately 60.degree.C while the terminal or end portions thereof are approximately 100.degree.C, thus, a 40.degree.C variance. By employing the above-described cooling arrangement the temperature variation between these portions may be reduced to 30.degree.C.

Claims

What is claimed is:

1. A copy machine comprising an enclosure, a rotatable photosensitive material, means for creating a toner image on said material, copy paper, transfer means for transferring said image to said paper, fixing means having an entrance opening and an exit opening through which said paper is moved for permanently fixing said toner to said paper by application of heat thereto, first cooling means for blowing a first air stream onto the surface of said photosensitive material, said first cooling means comprising a blower, ducting, and a nozzle, said blower coupled by said ducting to said nozzle and the outside of said enclosure for drawing air into said enclosure by said blower and directing it through said nozzle toward the surface of said material, second air directing means for directing a second air stream into said entrance opening of said fixing means, said second air directing means comprising a blower, a nozzle, and duct means operating in conjunction with said blower and said nozzle to withdraw air from outside of said enclosure and to direct it into said fixing means in the general direction of travel of said copy paper through said fixing means, and ventilator means for withdrawing air from said exit opening of said fixing means and discharging said air to the outside of said machine.

2. The combination recited in claim 1 wherein said means for creating a toner image on said material comprises a preexposure corotron and a cleaning arrangement for removing excess toner from said photosensitive material subsequent to transfer thereof, said nozzle being located to direct air from said first cooling means into contact with the portion of said photosensitive surface intermediate said pre-exposure corotron and said cleaning arrangement.