Defrosting grid system testing apparatus

An automated apparatus for continuity testing of windows provided with a resistance defrosting grid pattern having a plurality of electrically conducting, vertically spaced, parallel grid lines connected at each opposing end to an electrically conducting bus line, comprising in combination:

• (a) a base frame and supporting table;
• (b) means to support a window under test in a generally parallel spaced relationship on said table;
• (c) a first and second electrically conducting probe mounted on said base frame, each of said probes aligned to engage in electrically conducting relationship a different one of said bus lines at the opposing ends of said grid lines;
• (d) a third probe movably mounted on said base frame to travel at generally a right angle in electrically conducting relationship to each of said grid lines at a preselected position intermediate of said first and second probes to define a transverse pass of said third probe;
• (e) an electric power source operatively connected to said probes and said grid lines;
• (f) drive means mounted on said table and connected to said third probe to move said third probe across said grid lines;
• (g) control means operatively connected to said power source and said drive means including switch means to selectively alternate the polarity connection between said first and second probes relative to said third probe and to actuate said drive means to move said third probe in a preselected coordinated pattern related to the selected polarity of said probes;
• (h) sensing means operatively connected to said third probe for generating a signal responsive to a predetermined voltage range selected to indicate a non-defective grid line;
• and
• (i) means to count the signals generated by said sensing means to indicate the number of non-defective grid lines in said grid system operatively connected to said sensing means.

An improved testing apparatus for testing continuity of a defrosting window grid system of the type having a plurality of parallel disposed resistance grid lines extending between and connected to laterally spaced conducting bus lines provided on a window comprising, in combination;

• a base means including a support table;
• means for supporting a window above said table;
• first and second electrical conducting probes laterally spaced from one another and mounted on said base means, each of said probes disposed to contact a different one of said bus lines of a defrosting grid provided on the window supported above said support table;
• a third electrical conducting probe movably mounted on said base means for conducting engagement with said window grid in a transverse direction across the length of said grid lines;
• control means operatively connecting electrical power to said window grid and to said probes and including switch means to alternate the polarity of said first and second probes in a predetermined manner with respect to said third probe to obtain a voltage signal between said third probe and a selected one of said first or second probes as said third probe travels transversely at a preselected position across said grid lines intermediate of said bus lines;
• and sensing means operatively connected to said third probe and responsive to a predetermined voltage range associated with a predetermined standard value to provide a signal only when a voltage within said predetermined range is generated upon contact between said third probe and each of said grid lines.