Electrostatic coating apparatus
View Patent ↗Intended is to enable an electrostatic coating apparatus including a plurality of needle electrodes formed in an annular shape and having a blot preventing function, to prevent the generation of a spark discharge reliably, in case an arbitrary needle electrode approaches an earth element, and to keep the intensity of a generated electrostatic field properly. A coating gun comprises a blot preventing device including a ring-shaped electrode unit having a plurality of needle electrodes protruding radially at a substantially equal spacing radially outward from an annular base member, and a high-voltage generator for applying a high voltage to the electrode unit. The needle electrodes are connected in parallel with the high-voltage generator through individual resistors, block-by-block resistors and built-in resistors.
1. An electrostatic coating apparatus, comprising:
a high voltage generator;
a bell cup directly electrically connected to the high voltage generator for electrostatic spraying; and
a ring electrode positioned adjacently behind the bell cup, the ring electrode comprising an insulating ring base and multiple needle electrodes radiating from the ring base, the needle electrodes being electrically connected to the high voltage generator in a parallel manner through resistors positioned between the high voltage generator and the multiple needle electrodes.
2. The electrostatic coating apparatus according to claim 1 , wherein the needle electrodes are connected in a parallel manner to the high voltage generator through individual resistors.
3. The electrostatic coating apparatus according to claim 2 , wherein the electric resistances of the individual resistors are more than 1 MΩ.
4. The electrostatic coating apparatus according to claim 1 , wherein the needle electrodes are divided into multiple blocks and in each block the multiple needle electrodes are connected in a parallel manner to the high voltage generator through block-by-block resistors.
5. The electrostatic coating apparatus according to claim 4 , wherein the electric resistances of the block-by-block resistors are more than 1 MΩ.
6. The electrostatic coating apparatus according to claim 1 , wherein each needle electrode is connected to an individual resistor having a resistance of greater than 1 MΩ, and wherein at least two adjacent needle electrodes are connected to a common resistor having a resistance of greater than 1 MΩ.