Table 4-1 Corona Wire Specifications - Canon NP-70 Service Manual

4-24
NP•70
4.5 CORONA ASSEMBLIES
4.5-1
OUTLINE OF ASSEMBLY OPERATION
The NP-70 has five (5) corona assemblies which are used during the copy cycle. These as-
semblies contain an element for radiating an electromagnetic field, an insulated housing to hold
the radiator, and controls to set the radiator position. The five coronas and their functions are
as follows:
1) POSITIVE CORONA ASSEMBLY
Charges the surface of the sensitive drum initially with a positive charge until the surface po-
tential becomes approx. + 1800 ± 50 volts.
2) AC CORONA ASSEMBLY
Cancels the positive charges on the light (non-image) areas on the drum surface.
3)
NEGATIVE CORONA ASSEMBLY
Eliminates excessive dispersant adhering to the drum surface after immersion in the developer.
4)
TRANSFER CORONA ASSEMBLY
Emits positive ions to the paper to transfer the toner image from the drum to the paper. With
normal voltage more than 70% of the toner particles on the drum should be transferred.
5)
RESIDUAL CHARGE ELIMINATOR ASSEMBLY
Neutralizes any remaining charge on the paper after the fixing process.
4.5-2 ASSEMBLY MAIN COMPONENTS
As the five coronas similar in function (although individual in construction), the following
main components description are applicable to essentially all assemblies:
1) RADIATING ELEMENT
Each corona contains an element to which a high voltage is applied. This high voltage, either
AC or DC, is used in one of the distinct actions explained previously. The four (4) slip-out
coronas around the drum use a corona wire for radiation, while the residual charge eliminator
at the machine exit uses solid, plate-like radiators.
Specification
Pos.
Cor.
AC
Cor.
AC
Grid
Neg.
Cor.
Trans.
Cor.
Wire Diameter (mm) 0.06 0.06 0.06 0.06
0.10
Wire Length (mm)
782 ± 1 364 ± 10 4350 ± 10 748 ± 1 670 ± 1
Wire Separation (mm) 23.0 N/A 2.0 3.0 3.0
Standard Height (mm)
about 16.5
(refer to label)
about 9.5
(refer to label)
N/A 1 1.5 ± 1.0 10.0 ±0.3
Adjust. Leeway (mm) 3.0 3.0 N/A 4.0 4.0
Applied Voltage +6.4kVDC 7.OkVAC
OVDC(GND) —6.4kVDC +6.OkVDC
Breakdown Voltage IOkVDC IOkVAC N/A IOkVDC IOkVDC
Table 4-1
Corona Wire Specifications
Second Printing,lune, 1974
© CANON INC.