Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2001-05-04
2003-04-29
Braun, Fred L (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S062000
Reexamination Certificate
active
06556795
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing apparatus using two-component developer in the electrophotographic process of a copying machine, printer, facsimile, etc., specifically, to a toner concentration control device using a toner concentration sensor which detects toner concentration magnetically.
2. Description of the Related Art
Generally, toner concentration detection in an image forming apparatus using a two-component developer is done by detecting the change in permeability of the developer. This is a method of determining the toner concentration by measuring the permeability of the developer for the permeability varies in accordance with the mixing ratio of toner and carrier. In the case of monochromatic developer a magnetic toner and a magnetic carrier are used and in the case of color developer a non-magnetic toner and a magnetic carrier are used.
For example, the output of a permeability sensor is compared with a predetermined reference value, and control is done for keeping the toner concentration constant by supplying toner so that the output of the permeability sensor is equal to the predetermined value.
However, it is difficult to stir the developer composed of toner and carrier, and stagnation of the developer in the proximity of the detecting face of the toner concentration detecting sensor or adhesion of the toner to the detecting face of the toner concentration detecting sensor occurs in a prolonged period of use, inducing erroneous detection of toner concentration. As a result, the control of the toner concentration is not performed properly resulting in varying concentration of toner in the developer to low or high value, and problems such as reduction in print density, scattering of toner, and carrier dragging are induced.
Several methods for evading the problems mentioned above are proposed in Japanese Unexamined Published Patent Application No. 63-106679 (U.S. Pat. No. 4,901,115), No. 1-261683 (U.S. Pat. No. 4,956,669), No. 2-64560 (U.S. Pat. No. 4,974,024), No. 3-256082 (U.S. Pat. No. 5,216,470), and No. 7-306592. In these methods, changes of condition of the developer residing on the detecting face of the sensor are produced by scraping down the developer accumulated on the detecting face positively and cyclically with a scraper to effect cyclic fluctuation of the output of the sensor, bottom of the fluctuation is detected, and toner concentration is determined by measuring the output in the stable range of the output after the bottom of the cyclic fluctuation; or cyclic fluctuation is produced by scraping the toner in the proximity of the detecting face of the sensor, the cyclic fluctuation is superimposed on the output when the scraping is not done to enable the control of the toner concentration over an extended period of time without stagnation of toner in the proximity of the detecting face of the sensor.
However, by these methods of detection of toner concentration, there may occur the case where the proper measurement of toner concentration is not obtained because of the distortion of the output of the toner concentration detecting sensor according as what shape the agitating mixer rib is formed and where the toner concentration detecting sensor is positioned, or the bottom of the cyclic fluctuation of the output of the sensor is not properly determined, resulting in erroneous control of toner concentration.
Further, developer is susceptible to variations of environment, particularly, the output of the toner concentration detecting sensor relatively shifts according to humidity, etc., so it is needed to make it possible to stably determine toner concentration, while excluding the influence of relative variations.
In addition, as the output of a toner concentration detecting sensor varies from one product to another depending on the accuracy of constituent parts and assembling tolerances and pulverulent body such as toner and carrier is susceptible to environment, which exert influences upon the output of the toner concentration detecting sensor, it is needed to make it possible to properly and stably determine the bottom of the fluctuating output of the toner concentration detecting sensor, while excluding these influences.
SUMMARY OF THE INVENTION
The present invention is made in the light of the problems cited above. An object of the invention is to provide a toner concentration control device which can work over an extended period of time, can stably measure the concentration of toner without being influenced by the shape of the stirring mixer of developer and location of the toner concentration detecting sensor, and accordingly can stably control the concentration of toner.
Another object of the invention is to provide a toner concentration device with high reliability which can determine the concentration of toner without being influenced by the variation of environment and variations of the accuracy of constituent parts and assembling.
A further object of the invention is to provide a toner concentration control device in which the face of the permeability sensor can be wiped without reducing the performance of stirring the toner to secure reliable measurement of toner concentration, uniform mixing of toner by stirring can be effected smoothly and in a short period of time, and a good image can be obtained.
To attain the objects cited above, a toner concentration control device according to the present invention is a device having a toner concentration detection means for detecting magnetically the information of concentration of the toner in a developer vessel storing developer composed of a carrier and toner; a toner supply means for supplying the developer based on the output of the toner concentration information; a wave-forming means for forming a wave of decreasing output of the toner concentration detection means reduced through periodically scraping off the toner on the detecting face of the toner concentration detection means with, for example, a mechanical means; and an about-minimum value detection means for detecting the minimum value or its vicinity of the descending output reduced by the wave-forming means; and so configured so that a toner concentration detection retarding means is actuated from the time the minimum value or its vicinity is detected, and the toner supply means is actuated based on the detected toner concentration information after the toner concentration detection retarding means is released of action; wherein
the toner concentration detection means comprises a waveform measuring means which measures the output of the toner concentration detection means over a predetermined period longer than the period of one cycle of the scraping cycle, and an about-minimum value judging means which determines the minimum value or its vicinity of the output value measured by the waveform measuring means; and the toner concentration detection means is actuated based on the value judged as the minimum value or its vicinity by the about-minimum judging means before the toner supply means is actuated.
By the configuration cited above, the output of the toner concentration sensor is measured over a period longer than one cycle to determine the minimum value or its vicinity before the control of toner supply is started. Succeeding detection of minimum or its vicinity is performed on the basis of the value determined as above. So, stable and reliable determination of minimum value or its vicinity is possible without being influenced by the shape of the stirring mixer of developer and the distortion of waveform owing to the location of the toner concentration sensor, and without depending on the variation of environment and variations in accuracy of constituent parts and assembling.
Further, the present invention is preferable to be configured so that a detection range determined from the minimum value or its vicinity detected by the about-minimum value detection means in the preceding cycle is provided beforehand, and the about-minimum value detection means determines t
Miyamura Hiroaki
Tanda Tetsuo
Toda Saeko
Braun Fred L
Hogan & Hartson LLP
Kyocera Corporation
LandOfFree
Apparatus for controlling toner concentration in an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for controlling toner concentration in an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for controlling toner concentration in an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3076266