Abstract:
A toner quantity measuring apparatus in which an input offset voltage is applied to the output side of an irradiation quantity monitoring light receiving element, so that a light emitting element remains turned off unless a light quantity control signal exceeds a predetermined signal level. Prior to irradiation of light upon an intermediate transfer belt and measurement of a toner quantity, a light quantity control signal below the predetermined signal level is supplied to an irradiation quantity adjusting unit and the light emitting element is turned off without fail. A memory stores, as a dark output voltage, an output voltage from a reflection quantity detecting unit upon the turning off. Light reflected from the intermediate transfer belt is split into p-polarized and s-polarized light to detect a toner quantity and colors of the toner. In actual measurement of the toner quantity, with light irradiated upon the intermediate transfer belt, the dark output voltage is subtracted from the output voltage outputted from the reflection quantity detecting unit, whereby an influence of the dark output voltage is eliminated.
Abstract:
In an apparatus, first and second processing modes are prepared to determine an optimal development bias. Either one of the first processing mode and the second processing mode is selected as a processing mode in accordance with an operation status of the apparatus. Hence, it is possible to select and execute the most appropriate processing mode in accordance with an operation status to thereby efficiently and highly accurately determine an optimal value of a development bias which is one density controlling factor.
Abstract:
In an apparatus, first and second processing modes are prepared to determine an optimal development bias. Either one of the first processing mode and the second processing mode is selected as a processing mode in accordance with an operation status of the apparatus. Hence, it is possible to select and execute the most appropriate processing mode in accordance with an operation status to thereby efficiently and highly accurately determine an optimal value of a development bias which is one density controlling factor.
Abstract:
An image It is formed as a patch image which includes a header image portion Ih of a solid image having a length of a circumferential length of a developing roller or more, and a gradation image portion Ig progressively varied in the tone level thereof from the maximum level to the minimum level. The densities of the patch image on an intermediate transfer belt are sampled. However, the sampling results contain errors resulting from noises or variations and hence, are subjected to a noise removal process, a periodical variation correction process and a reverse correction process. The results detected on the intermediate transfer belt do not always coincide with image densities (OD values) on a recording material. Therefore, the detection results are converted into the OD values, based on which tone characteristics of an apparatus is estimated. Then a tone correction table is updated in a manner to compensate for the tone characteristics. This approach is taken to improve image quality on the recording material.
Abstract:
An image It is formed as a patch image which includes a header image portion Ih of a solid image having a length of a circumferential length of a developing roller or more, and a gradation image portion Ig progressively varied in the tone level thereof from the maximum level to the minimum level. The densities of the patch image on an intermediate transfer belt are sampled. However, the sampling results contain errors resulting from noises or variations and hence, are subjected to a noise removal process, a periodical variation correction process and a reverse correction process. The results detected on the intermediate transfer belt do not always coincide with image densities (OD values) on a recording material. Therefore, the detection results are converted into the OD values, based on which tone characteristics of an apparatus is estimated. Then a tone correction table is updated in a manner to compensate for the tone characteristics. This approach is taken to improve image quality on the recording material.
Abstract:
A light emitting element irradiates light upon a surface area of an intermediate transfer belt which is wound around a roller, i.e., upon a wind area, and light receiving units receive light reflected at the wind area. Based on a signal outputted from a sensor, the quantity of toner is measured. In the wind area, the intermediate transfer belt does not flap in a direction which is approximately perpendicular to a direction in which the belt travels. This suppresses a change in distance (sensing distance) between the sensor and the intermediate transfer belt.
Abstract:
When the remaining toner amount within a developer is relatively large, a control target value of a toner amount is set to Ttgt1 and a lower limit value of a toner amount which can regarded proper is set to TL1. When the density of a patch image formed under a predetermined condition is smaller than a minimum guaranteed density Dma, it is determined abnormality has occurred in the apparatus. Since the characteristic of toner within the developer changes as the remaining toner amount decreases, the control target value is changed to Ttgt2 and the lower limit value is set to TL2 in light of this. In this fashion, regardless of whether the toner characteristic has changed, abnormality in the apparatus is detected without fail.
Abstract:
Output signals Vp from a density sensor are sampled for plural positions on an intermediate transfer belt and an amount of toner adhesion is determined based on the results of sampling. Since these sample data pieces may contain noises, each predetermined number of data pieces of higher order and of lower order are removed from the resultant sample data string. The removed data pieces are each replaced by an average value Vpavg of the other sample data pieces. The amount of toner adhesion is calculated based on the data string thus replaced.
Abstract:
A development bias calculation and an electrifying bias calculation are executed in this order. In the development bias calculation, a plurality of toner images are formed as first patch images while changing the development bias. An optimal development bias, which is necessary to obtain the target density, is determined based on densities of the first patch images. In the electrifying bias calculation, toner images are formed as second patch images while changing the electrifying bias with the development bias fixed to the optimal development bias. An optimal electrifying bias, which is necessary to obtain the target density, is determined based on densities of the second patch images.
Abstract:
A development bias calculation and an electrifying bias calculation are executed in this order. In the development bias calculation, a plurality of toner images are formed as first patch images while changing the development bias. An optimal development bias, which is necessary to obtain the target density, is determined based on densities of the first patch images. In the electrifying bias calculation, toner images are formed as second patch images while changing the electrifying bias with the development bias fixed to the optimal development bias. An optimal electrifying bias, which is necessary to obtain the target density, is determined based on densities of the second patch images.