Abstract: There is provided a medium transport device including a placement section on which a medium is placed, a transport path through which the medium is transported, a feeding roller that feeds the medium, a set guide configured to switch between a contact position where the medium and the feeding roller are brought into contact and a separation position where the medium and the feeding roller are separated, a restricting section configured to switch between a restricting position for restricting feeding of the medium by coming into contact with a leading end of the medium and an allowing position for allowing the feeding of the medium, and a drive source that generates power for switching of the set guide and switching of the restricting section. The set guide and the restricting section are provided below the transport path in a direction of gravity.

Abstract: An image fixing device for an electrophotographic copying apparatus and the like including a fixing roller and a pressing roller in pressing contact with each other. The fixing roller includes a metallic core, a resilient material layer and an offset preventing layer superposed one over another in the indicated order and having a heating member disposed therein for heating the metallic core. A copy sheet formed thereon with a toner image is passed between the two rolls so that the toner image will be fixed to the copy sheet by melt adhesion by being pressed between them while being heated. The offset preventing layer has a higher heat intake than the toner image so as to be highly responsive to heat. The offset preventing layer is formed of a material containing a synthetic resinous material, such as silicone rubber, silicone resin, etc., which is highly resistant to heat and which has a high parting property, added with over 1% by weight of metal powder of high thermal conductivity.

Abstract: A method is disclosed of protecting a rubber roller or roll which is supplied with oil during use, by coating its end faces. Unless the coating protects the end face in a satisfactory manner, the oil penetrates into the end face to degrade the rubber roller. In accordance with the invention, the end face is inwardly bevelled or tapered in the axial direction, and a protective layer for the end face is formed simultaneously as a protective layer for the peripheral surface of the roller.

Abstract: A photosensitive member is exposed to light prior to primary charging so that the surface potential applied by primary charging may always be maintained at a constant level to which the photosensitive member is always charged when it is repetitively used for some time, which may be predetermined by test. Until the surface potential reaches this level, the intensity of light for pre-exposure is gradually decreased and after the surface potential has reached this level, no pre-exposure is applied. But when the surface potential rises after a predeterminable period during which the photosensitive member is not used, the pre-exposure is applied again. All the copies may have the same density.

Abstract: Improved heat roller fixing apparatus comprising an inner cylinder having a heater therein, an outer cylinder, and a vacuum chamber which is formed between the inner cylinder and the outer cylinder and which contains a liquid heat transfer medium at low pressure is described. In particular, improvements obviating excessive heating of the inner cylinder are made by placing the heat transfer medium in the chamber so as to be in contact with the lower portion of the inner cylinder at least when said outer cylinder is stationary, or by mounting on the inner cylinder a member which serves to stir or pour the heating medium on the inner cylinder and also to transfer heat indirectly from the inner cylinder to the outer cylinder through the heating medium so that speedy evaporation of the heating medium and safe and stable fixing of images are accomplished.

Abstract: A device for fixing an image formed by electrostatic adhesion of toner particles on a copy sheet, wherein such copy sheet is passed between a pair of fixing rollers consisting of a fixing roller and a follower roller, the fixing roller having an offset preventing oil fed to its surface and being heated as required. The fixing roller and the follower roller each include a base material layer made of silicone rubber which is not caused to swell by the offset preventing oil and is swellable thereby. The fixing roller further include a thin surface layer formed on the outer surface of the base material layer and made of silicone rubber which has affinity with a silicone oil. The offset preventing oil may be a fluoroalkyl radical containing silicone oil or a mixture of such oil with an alkylpolysiloxane oil.

Abstract: A method of producing a heat pipe roller having a chamber for holding a heating medium therein is disclosed, wherein sealing means for sealing the heat pipe roller are connected to an upper end plate of the heat pipe roller through a hole formed in the upper end plate. The heat pipe roller containing a heating medium therein is heated at temperatures above the boiling point of the heating medium and finally the heat pipe roller is sealed by use of the sealing means after adjusting the degree of vacuum or pressure in the heat pipe roller to a predetermined degree.

Abstract: A heat pipe roller comprising an inner pipe, an outer pipe, and a chamber formed by the inner pipe and the outer pipe, containing a heating medium, wherein the inner pipe and the outer pipe are sealed above one portion of each end of the heat pipe roller.

Abstract: Improved heat roller fixing apparatus comprising an inner cylinder having a heater therein, an outer cylinder, and a vacuum chamber which is formed between the inner cylinder and the outer cylinder and which contains a liquid heat transfer medium at low pressure is described. In particular, improvements obviating excessive heating of the inner cylinder are made by placing the heat transfer medium in the chamber so as to be in contact with the lower portion of the inner cylinder at least when said outer cylinder is stationary, or by mounting on the inner cylinder a member which serves to stir or pour the heating medium on the inner cylinder and also to transfer heat indirectly from the inner cylinder to the outer cylinder through the heating medium so that speedy evaporation of the heating medium and safe and stable fixing of images are accomplished.

Abstract: A fixing roller which is constructed by bonding in layers a heat resistant adhesive layer, a heat and oil resistant layer, a heat and oil resistant adhesive layer and an offset preventing layer to a core, wherein the offset preventing layer is formed before the solvent of the heat and oil resistant adhesive layer has been completely evaporated, and at least one component material of the heat and oil resistant adhesive layer is of a kind similar to the component materials of both the heat and oil resistant elastic layer and the offset preventing layer so that the peeling off of the offset preventing layer is obviated.

Abstract: A copy sheet is fed between a heated fixing roller and a nip roller to fix a toner image to the sheet. An applicator applies an offset preventing liquid to a transfer roller which transfers the liquid to the fixing roller. A spring arrangement presses the applicator against the transfer roller and another spring arrangement presses the transfer roller against the fixing roller in such a manner that the transfer roller is normally held against rotation and is caused to rotate when the liquid thickness on the fixing roller drops below a predetermined value at which the coefficient of friction between the transfer roller and the fixing roller becomes greater than the ratio of the tangential to the normal forces therebetween. The transfer roller through rotation applies the liquid to the fixing roller to increase the liquid thickness thereon.

Abstract: An image fixing roller having a comparatively long service life and tending to resist the so-called "offset phenomenon" in which portions of the toner image on one sheet adhere to the roller and are transferred onto the next sheet bearing a toner image. The roller has a radially outer layer made of silicon rubber impregnated with silicon oil which is non-tacky, heat resistant and resilient and has hardness of 20 to 70, tear strength of 10 to 15 kg/cm and tensile strength of below 70 kg/cm.sup.2.

Abstract: A roll for fixing a toner image formed on a support sheet in electrophotography comprising a plurality of layers made of a resilient material and arranged around a core disposed about the center axis of the roll. The resilient material layer disposed nearer to the core is electrically conductive and serves to make the roll function as a heating roll. It has a higher hardness than the resilient material layers remote from the core.

Abstract: A device comprising an offset preventing liquid supply roller of a novel construction which is capable of supplying a suitable amount of offset preventing liquid in one operation to a fixing roller of an electrophotographic copying apparatus and remaining in sevice over a prolonged time by merely being maintained in contact with the fixing roller with a low force. The supply roller comprises a reservoir disposed in its central portion for containing therein a substantial amount of offset preventing liquid, and a liquid permeable material layer disposed outwardly of the reservoir and capable of being permeated with the offset preventing liquid for supplying to the fixing roller the offset preventing liquid which oozes therethrough.

Abstract: A toner image formed on a support sheet by toner particles adhering to selected areas of the sheet is fused either by simply disposing the sheet in with a heating surface, or by additionally pressing the sheet. After the toner image particles are fused, the sheet is cooled while maintaining its image bearing side in contact with the surface previously used for heating, so that the toner particles solidify and the toner image is stiffened. The sheet is then separated from the surface with which it was previously in contact. In the course of heating, some toner particles of the image may temporarily adhere to the heating surface, but in the course of the cooling step, these toner particles develop a stronger adhesion to the remainder of the image and to the sheet. Thus, after the cooling step, no toner particles remain on the surface contacted by the sheet, and the so-called "offset phenomenon" does not occur.