Chemistry: electrical and wave energy – Apparatus – Vacuum arc discharge coating
Patent
1993-12-13
1995-09-19
Weisstuch, Aaron
Chemistry: electrical and wave energy
Apparatus
Vacuum arc discharge coating
20419238, C23C 1432
Patent
active
054513081
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The field of this invention is electric arc metal evaporators.
PRIOR ART
An electric arc metal evaporator having a cathode, which is made of evaporating metal and which has an evaporation surface, and a direct current power supply connected to cathode and anode is known (U.S. Pat. No. 3,793,179).
In the above mentioned evaporator, the surface of a substrate is coated with material evaporated by the action of a cathode spot of an electric vacuum arc which moves chaotically over a cathode surface. Active evaporation of cathode material from its surface and deposition of evaporated metal on substrates, which are placed opposite to cathode evaporation surface, occurs due to the high concentration of energy in the cathode spot of the electric arc.
When long objects are processed it is necessary to use several evaporators placed along the length of the objets. This results in difficulties when this type of evaporator is used.
Another known electric arc metal evaporator (SU, A, 461,163) has a cathode, which is extended along its longitudinal axis and in which the evaporation surface is placed along its longitudinal axis, and connecting leads, which are placed on the opposite sides of the cathode and are connected to controllable switches, which are connected to each other through separate turn-on members. These members have a control unit and are connected to a direct current power supply, which is also connected to the anode. This device also has a unit for determination of the cathode spot position on the cathode evaporation surface. This unit is connected to a control unit.
The unit for determination of the cathode spot position on the cathode evaporation surface is constructed using detectors of the final position of the cathode spot. The cathode spot movement under the influence of the magnetic field of the current passing through cathode moves always in direction of the connecting wire. When the cathode spot reaches the end the cathode, the unit for determination of cathode spot position sets the level of an electric signal which enters the control unit. The control unit switches on a control switch placed near the cathode end opposite the cathode spot and simultaneous switching-off of another switch. Because the cathode spot moves over the cathode surface with uniform speed in the space between the detectors of the final position of the cathode spot, the uniformity of movement does not allow control of the time of plasma flow on some parts of substrate to be coated. This results in coating thicknesses which differ at the substrate ends from its central zone.
SUMMARY OF THE INVENTION
The described invention is based on the object of making a metal evaporator in which the unit for determination of cathode spot position on the cathode evaporation surface allows control of cathode spot movement according to a given program. This results in uniform coating over the whole surface of the substrate.
The object is accomplished by construction of a unit for determination of the cathode spot position on a cathode evaporation surface which detects the current position of the cathode spot on the cathode evaporation surface. The device also has a cathode, which is extended along its longitudinal axis, made of evaporating material and having its evaporation surface placed along its longitudinal axis, and connecting lead wires which are placed on the opposite sides of the cathode and connected to control switches which are connected to each other and to a direct current power supply. The direct current power supply is also connected to an anode. A unit for determination of the cathode spot position on the cathode evaporation surface is connected to the control unit.
The cathode can serve as detector of the current position of the cathode spot on the cathode evaporation surface. The connecting leads of the cathode can serve as connecting leads of the detector.
The detector of the current position of the cathode spot is shaped as an extended conductor which is made of high resistivity, which le
REFERENCES:
patent: 3793179 (1974-02-01), Sablev et al.
patent: 4734178 (1988-03-01), Gavrilov et al.
patent: 5037522 (1991-08-01), Vergason
patent: 5269898 (1993-12-01), Welty
Andreev Anatoly A.
Crigoriev Sergei N.
Sablev Leonid P.
Novatech
Weisstuch Aaron
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