Image Forming Apparatus Development Current Calculation
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately measuring the actual development current due to errors from reverse currents when measuring toner patch widths, which affects toner density and developability.
Innovation Solution
The apparatus includes a developing roller, a photosensitive drum, and measurement devices to calculate the actual development current by measuring blank and development currents, allowing for precise adjustment of development bias voltage and toner charge calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If development current is measured using conventional methods, then measurement is simplified, but measurement precision deteriorates due to reverse current errors
Solution Approach 1:
The measurement process is segmented into three distinct current measurements: blank portion current (without toner patch), toner patch current (with toner patch), and development current. By separating the measurement into these segments and calculating development current as the difference between toner patch current and blank portion current, the method eliminates reverse current errors and achieves accurate development current measurement.
2Measurement precision
If toner patch width is increased to improve measurement signal, then measurement precision improves, but manufacturing precision deteriorates due to toner density variations
Solution Approach 1:
The invention extracts and removes the reverse current component from the measurement by measuring blank portion current separately and subtracting it from the total current measurement. This extraction of the harmful reverse current signal allows for accurate development current measurement without requiring large toner patches, thereby maintaining both measurement precision and toner patch uniformity.
3Stability of the object's composition
If development bias voltage is adjusted to maintain toner density, then toner density consistency improves, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The system implements feedback control by continuously measuring the development current using the segmented measurement method and using this information to adjust the development bias voltage. The measured development current serves as feedback to maintain toner density within target ranges, achieving stable toner composition through closed-loop control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables accurate measurement of actual development current, maintaining consistent toner density and developability, and improving the accuracy of toner patch formation.
Implementation Method 1
a first measurement device 322 to measure a blank portion current Iw in a first line A on the photosensitive drum 33
Implementation Method 2
a second measurement device 323 to measure a measuring development current Id in a second line B on the photosensitive drum 33
Implementation Method 3
The first calculator 324 calculates an actual development current Io based on a developable width Wo of the photosensitive drum 33 in the scanning direction R3, the toner patch width W, the blank portion current Iw, and the measuring development current Id
Data Source
AI summary
An image forming apparatus includes: a developing roller; a photosensitive drum; a first measurement device that measures a blank portion current in a first line on the photosensitive drum which extends in a scanning direction of the photosensitive drum and on which no toner patch is formed; a second measurement device that measures a measuring development current in a second line on the photosensitive drum which extends in the scanning direction of the photosensitive drum and on which a toner patch is formed; and a control device that functions as a patch setter and a first calculator. The patch setter sets a patch width of the toner patch in the scanning direction of the photosensitive drum. The first calculator calculates an actual development current based on a developable width of the photosensitive drum in the scanning direction, the patch width, the blank portion current, and the measuring development current.