Image forming apparatus and image forming method

Abstract

An image forming apparatus and an image forming method are provided which form high-quality fixed images having no fogs and the like defects, in which apparatus and method a toner entering a pressure-contact area between rollers is prevented from scattering. A control is performed on preheating conditions for preheating an unfixed toner image on a recording medium, which unfixed toner image indicates a toner image transferred but not yet fixed, and a control is further performed such that an amount of toner attached to the recording medium at a coverage rate of 100% is 0.4 mg / cm2 or less, with the result that the toner is prevented from scattering when the recording medium carrying the unfixed toner image passes through a pressure-contact area formed between a heating roller and a pressurizing roller in a fixing step.

Description

Image forming apparatus and image forming method technical field The present invention relates to an image forming apparatus and an image forming method. Background technique In an electrophotographic image forming apparatus, a latent image formed on a photoreceptor is developed to form a toner image, and the image is transferred to a recording medium such as paper and fixed to form an image. As a fixing method, a pressure-bonding thermal fixing method is generally used. The pressure contact heat fixing method is a method in which the recording medium on which the unfixed toner image is transferred is pressure-bonded and heated by at least one pressure-contact portion between a pair of rollers that are heated and rotate in pressure contact with each other. The thermoplastic resin, which is a main component of the toner, melts and softens, adheres to the recording medium, and is fixed on the recording medium as a toner image. The desired performance of an image forming ...

AI Technical Summary

Problems solved by technology

In the technique disclosed in Japanese Patent Application Laid-Open No. 9-160408, the preheating temperature is maintained in the range of not less than 100°C and not more than the softening temperature of the toner, and the toner on the recording medium is also preheated to around the softening temperature. It is presumed that some toners are also fused with each other, but when the amount of toner adhered to the recording medium is large, toner scattering cannot be prevented.

In the technique disclosed in JP-A-2003-271007, the preheating temperature is as low as about 100°C or below, and toner fusion does not occur due to preheating, so the amount of toner adhered particularly on the recording medium is large. image quality degradation due to toner scattering

In the technology disclosed in Japanese Patent Laid-Open No. 2006-154244, since the amount of toner attached to the recording paper is not considered, when the amount of toner attached to the recording paper is large, the temperature cannot be transmitted to the toner during preheating. If the toner layer is complete, the fusion between the toners is insufficient, so the image quality deteriorates due to the prevention of toner scattering

In addition, the technology disclosed in Japanese Patent Application Laid-Open No. 2006-154244 is a polymerized toner, and the polymerized toner is substantially spherical, so the toner particles are easy to fall off from the toner layer before the preheating step, causing toner scattering. s reason

Images