Method and Apparatus for Drilling Holes With a Laser

One type of display panel described in copending application Ser. No. 051,313 of George E. Holz and James A. Ogle, filed June 22, 1979, includes a thin metal plate having a large number of small-diameter holes. At the present time, these holes are formed by means of a laser, and this hole-forming operation is generally satisfactory. However, one problem is that the material of the metal plate which is removed by the laser sometimes deposits on the surface of the plate near each hole as it is formed. This results in an uneven surface and non-uniform spacing of the plate from other associated structures in the panel. One solution which is employed comprises coating the metal plate with a protective insulating coating, but this requires extra steps. The present invention provides a solution to this problem.

FIG. 1 is a sectional, elevational view of apparatus embodying the invention; and

FIG. 2 is a sectional, elevational view of a modification of the apparatus of FIG. 1.

The principles of the invention are illustrated in the apparatus 10 shown in FIG. 1 which includes a support member 20 comprising a metal plate having a top support surface 30 in which a plurality of holes or slots 40 are formed.

According to the invention, in operation of the apparatus 10, a sheet 60 of insulating material such as paper, bond paper, tissue paper, filter paper, cardboard, or the like, hereinafter called paper, is seated on the top surface of member 20.

A metal plate 70 to be operated on, for example to form small holes therein, is seated on paper sheet 60 and is held down by suction, by clamping, or in any suitable manner. A laser 80 is movably disposed above the apparatus 10 in position to direct its energy onto the metal plate 70.

In operation of the apparatus 10, the laser 80 is adjusted and operated to direct a pulse of energy of the desired diameter onto the metal plate 70. This energy pulse penetrates the plate 70, and, as it penetrates, it renders a small cylinder of metal partly molten and partly vaporized, and the vaporized metal blows the molten metal out of the plate. When the energy pulse penetrates through the metal plate, the paper sheet receives energy at the end of the pulse, and the paper then operates like a jet to drive the molten metal out of the plate and to leave a neatly formed hole 90 with both surfaces of the plate, around the hole, clean. The laser pulse terminates as it reaches the paper sheet.

The laser is moved from place to place to form holes 90 in the desired locations in the plate 70.

It is noted that, if the paper sheet 60 is suitably porous so that air can pass through it, then suction force can be coupled to the holes or slots 40 in support plate 20 to hold plate 70 down on the plate 20.

With respect to the laser 80, it has been found that a YAG laser can be operated to provide a pulse of the optimum energy and length for the proper operation of the invention. The output pulse of a CO.sub.2 laser may not be controllable to terminate after the plate 70 has been penetrated, in which case, the paper sheet might be ruptured. In this case, a protective coating 94 of lacquer or the like may be provided on both upper and lower surfaces of the plate 70 to prevent metal from depositing thereon.

After all of the desired holes are formed in the plate 70 with the YAG laser, it is removed from the support apparatus, and it is ready for use as required without any special time consuming operations except perhaps for cleaning.