Single Component Developing System - Kyocera KM-1650 Service Manual

2DA/2DB

(2) Single component developing system

This machine uses the single component developing system, and reversal processing is performed with a + charged
drum (a-Si) and a + charged magnetic toner.
With the single component developing system, toner is electrically charged by friction with the developing sleeve and +
charged when it passes through the magnetic doctor blade. The toner that has passed through the magnetic doctor blade
forms a uniform layer on the developing sleeve. When the toner layer comes to the location where the developing sleeve
is the nearest to the drum, toner moves between the drum and the developing sleeve by an electric field of the magnetic
pole. Then, when the developing sleeve rotates and passes through the nearest location to the drum, on the portion of the
drum that has been exposed to light, toner is attracted toward the drum by potential difference between the developing
bias and the drum surface and development is performed. On the other hand, on the portion of the drum that has not been
exposed to light, toner is attracted toward the sleeve and development is not performed. When toner comes to an area
where the gap between the drum and the developing sleeve is large, an electric field disappears and toner does not leave
the developing sleeve. Development is complete.
Magnetic toner blade
Toner
South pole
North pole
Drum
Developing sleeve
Figure 2-1-13 Single component developing system
Developing bias parameters
For the bias to the developing sleeve, an alternat-
ing current (AC) is applied. Parameters for the
developing bias are shown below.
V Duty
Vp-p: Difference between the maximum and the
minimum of applied voltage
1.6 kV (fixed)
Vf: Frequency
Typically 2.7 kHz. This value varies depending on
the preset value of the drive time and the environ-
Vo
mental correction. (Can be adjusted with the
Vdc
Vp-p
maintenance item U101.)
VL
Duty: Ratio of time where + voltage is applied in a 0
cycle
Typically 45%. (Can be adjusted with the mainte-
nance item U101.)
Vdc: Developing shift bias potential 290 V
Supplementation
Vf
Vo: Drum surface potential on non-image area
(area not exposed to light)
VL: Drum surface potential on image area (area
exposed to light)
Figure 2-1-14 Developing bias waveformsa
2-1-12