Backside heating and fixing apparatus in an electronic photograph duplicator

Abstract

Contact fusing apparatus for fixing powder images to a substrate. The apparatus comprises a heated roll or cylinder to which the substrate is electrostatically tacked to improve heat transfer thereto. In order to prevent "trail-end flip up" of the substrate, means are provided to produce an attractive force between the substrate and means for guiding the substrate to the heated roll, but only after the substrate has been tacked to the heated roll.

Description

BACKGROUND OF THE INVENTION

This invention relates, in general, to apparatus for fusing powder images to a substrate and, more particularly, to a contact fuser which softens the powder images by means of heat conducted through the back of the substrate.

In the case of a backside heating and fixing apparatus in an electrophotographic duplicator, more specifically, in the case of such a backside heating and fixing apparatus that a heating roller with electric insulating material coated into a thin film on the surface of a grounded electroconductive roller is subjected to electrification by the application of a process of corona discharge for the purpose of fixing such a thermally plasticized resin material as is supported on duplication paper into an image pattern, i.e., so to speak, a toner, and an electric charge of such polarity as is reversed to that of said heating roller is applied on the duplication paper supporting the toner into an image pattern, the heating roller and the duplication paper are caused to come in contact with each other by virtue of the electrostatic force thereof, heat transmission is effected by conduction to thus heat the duplication paper, and the toner is concurrently welded until the toner is fixed upon the surface of the duplication paper, the rear end of the duplication paper is prone to pass by without being adapted to, hence without coming in contact with, the heating roller, thus resulting in no fixation at all.

The cause whereof lies in the fact that the section of the duplication paper 2 kept in contact with the heating roller 1 gives the said duplication paper such force as to revolve in the direction the heating roller 1 is revolving in, which is conjectured to take shape due to the relation between said force and the contact force of the duplication paper 2 with the heating roller 1 as shown in FIG. 1.

Accordingly, it is a primary object of this invention to provide a new and improved apparatus and method of fusing powder images to a substrate.

It is a more particular object of this invention to provide in a contact fusing device, means for preventing "trail-end flip up."

BRIEF DESCRIPTION OF THE INVENTION

Briefly, the above-cited objects are accomplished by providing a contact fuser in the form of a heated roll in combination with means for guiding a substrate into contact therewith wherein the substrate is electrostatically tacked to the heated roll to improve the fusing process and wherein an attractive force is provided between the substrate and the guide means. The attractive force is provided only after the leading portion of the substrate has been electrostatically tacked to the heated roll to thereby insure that the substrate can be moved from the guide to the heated roll.

Other objects and advantages will become apparent in view of the description of the specification as related to the drawings wherein:

FIGS. 1 and 2 are schematic plan views of a prior art contact fuser without the improvements contemplated;

FIG. 3 is a schematic plan view of a contact fusing device representing the invention;

FIG. 4 is a modified form of the improvement contemplated; and

FIG. 5 is another modified form of the improvement contemplated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Now that, in case the section of the duplication paper 2 backside heating and fixing apparatus is employed, a concrete description of an illustration of the present device will be given below, by making reference to the drawings, including FIGS. 3-5, attached hereto.

In the drawings, 1 is a heating roller; 2 is duplication paper; 3 is a corotron for effectuating electrification over said duplication paper 2; 4 is a corotron for effectuating electrification over said heating roller 1 and is of the reverse polarity to that of said corotron 3; 5 is a stripper for exfoliating the duplication paper 2 off the heating roller 1, and 6 is a conveying mechanism for the duplication paper 2.

7 is a guide plate (hereinafter to be termed as a feed-in chute) set in place between the conveying mechanism 6 and the heating roller 1, and this feed-in chute is set in place on the contact surface of the heating roller 1, so that the duplication paper 2 can be fed into the heating roller 1 from the conveying mechanism 6 in a smooth manner.

Shown in FIG. 3 is such a design that a corotron 8 is set in place as a means of giving proper force for causing the duplication paper 2 to be fed in contact with said feed-in chute 7, to thus cause the duplication paper 2 to be properly fed in contact with the feed-in chute 7 by corona discharge, and in this case, the feed-in chute 7 is required to be properly grounded. Now that, when the corotron 8 is subjected to corona discharge, starting from the time before the duplication paper 2 is fed into the feed-in chute 7, the duplication paper 2 might possibly keep staying in the feed-in chute 7, it is recommendable to subject the corotron 8 to corona discharge only after the duplication paper 2 is kept in contact with the heating roller 1 to thus have sufficient torque given by the heating roller 1, since this proves a requirement for obtaining a desirable result. The corotron 8 simply has to be subjected to such corona discharge as is sufficient to give the duplication paper 2 the minimum level of force required of the duplication paper 2 to run along the feed-in chute 7.

Shown in FIG. 4 is such a case that an electrostatically charging system is employed for said feed-in chute 7.sub.1, and a desirable result was obtained when the voltage in such a range as approximately 300 - 1,000V was applied on said feed-in chute.

Shown in FIG. 5 is such a case that an air suction system is employed for the feed-in chute 7.sub.2, wherein the duplication paper is caused to be fed in such a manner as to come in close contact with the feed-in chute 7.sub.2, and in this case a fairly large quantity of suction air is required; however, the result of an experimentation showed that a desirable effect could be obtained by the employment of a blower of 5 m.sup.3 /min.

The backside heating and fixing apparatus introduced in the present device is, at set forth above, furnished with such a flat plate-shaped feed-in chute as is set in place between the backside heating roller and the duplication paper conveying mechanism and causes the surface to be overlapped with the contact surface of the backside heating roller, and furnished with at least one measure for giving birth to physical absorption force between the said backside heating roller and the duplication paper and between the said feed-in chute and the duplication paper, respectively, therefore, this backside heating and fixing apparatus proves to be well capable of preventing in a secure manner such an unfixed section as is often or sometimes given birth in the rear end section of the duplication paper in case a conventional backside heating and fixing apparatus is employed.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

Claims

What is claimed is:

1. A method of fusing toner images to a substrate utilizing a heated member and guide means for directing the substrate into contact with the heated member and further utilizing first means for effecting intimate contact between said substrate and said heated member and second means for effecting intimate contact between the substrate and said guide means, said method comprising the steps of:

moving said substrate into contact with said guide means and said heated roll, in that order;

energizing said first means for affecting intimate contact between said substrate and said heated roll; and

subsequently energizing said second means for effecting intimate contact between said substrate and said guide means for preventing trail-end flip-up of said substrate.

2. Apparatus for fusing powder images to a substrate, said apparatus comprising:

a heated roll for contacting the side of said substrate opposite said powder images;

means for guiding said substrate into contact with said heated roll;

means for effecting intimate contact between said substrate and said heated roll once said substrate contacts said heated roll;

means for providing an attractive force between said guide means and said substrate subsequent to the energization of said means for effecting contact between said substrate and said heated roll; and

means for rendering said attractive force providing means operative only after intimate contact is established between said substrate and said heated roll.

3. Apparatus according to claim 2 wherein said means for providing an attractive force between said guide means and said substrate comprises means for creating a pressure differential across said substrate.

4. Apparatus according to claim 2, wherein said means for providing an attractive force between said guide means and said substrate comprises a source of electrical potential.

5. Apparatus according to claim 4, wherein said source of electrical potential comprises a corona discharge device.