Tool carrying vehicle with laser control apparatus

In combination with a vehicle having a power supply and movable over a given land surface and having a tool attached to the vehicle and movable toward and away from a laser reference plane generated by a swinging laser beam, and further including a power device carried by the vehicle, energizable by the power supply, and operatively connected with said tool to move said tool toward and away from the laser reference plane, an apparatus for maintaining a predetermined distance between said tool and the laser reference plane comprising:

• a detector housing;
• a detector support frame carried by said detector housing and having an outer periphery facing outwardly from said housing in a plurality of directions;
• a laser reference plane detector carried by said detector support frame and energizable by the power supply, said detector including first and second laser beam detecting arrays, each said array including a plurality of light-sensitive devices attached to said outer periphery of said detector support frame and facing outwardly from said outer periphery in a plurality of directions, said light-sensitive devices of each array substantially centered on a common plane, with the common planes of said first and second arrays being generally parallel to and spaced from one another to define a zone therebetween, said first and second arrays producing first and second control signals, respectively, in response to detecting the laser reference plane;
• a mounting carried by said vehicle and supporting said detector housing such that said zone is said predetermined distance from said tool, said mounting being movable relative to said vehicle to move said detector housing in response to movement of said tool relative to said vehicle to thereby maintain said predetermined distance between said tool and said zone of said detector when said tool is moved relative to said vehicle;
• electrical control circuitry energizable by the power supply and operatively connected to said first and second detecting arrays to receive said first and second control signals from said arrays, said control circuitry connected to said power device and responsive to said first and second control signals to actuate said power device to move said tool relative to said vehicle, causing said detector housing to be moved relative to said vehicle by said mounting so said detector in said detector housing closely follows the laser reference plane to retain the reference plane between said arrays, thus assuring said tool is said predetermined distance from the laser reference plane;
• and
• said detector support frame including means for controlling the coarseness of grading comprising first and second carriages, said carriages being movably mounted relative to and wholly within said detector housing for converging and diverging simultaneous movement at the same rate of speed toward and away from one another, a said laser beam detecting array being carried on each of said carriages so that converging and diverging movement of said carriages decreases and increases, respectively, the distance separating said detecting arrays, said means for controlling the coarseness further including carriage drive means energizable from the power supply, carried by said detector housing and operatively, mechanically coupled to said first and second carriages to simultaneously move said carriages relative to said detector housing and toward and away from one another.