Photoelectric device with capability to change threshold levels in response to changing light intensities

A photoelectric sensor, comprising:

• a light source;
• a light sensitive device, said light sensitive device providing a first signal representative of an intensity of light imposed on said light sensitive device, said light sensitive device being disposed to receive a beam of light from said light source;
• means for comparing said first signal to a first threshold magnitude in order to detect the presence of an object in the path of said beam of light;
• first means connected in signal communication with said light sensitive device for determining an updated value of said first threshold magnitude as a function of the maximum value of a magnitude of said intensity of light imposed on said light sensitive device during a first preselected period of time;
• means for deactivating said first determining means during a second preselected period of time;
• means for replacing a previous value of said first threshold magnitude with said updated value of said first threshold magnitude upon the detection of said object in the path of said beam of light;
• and
• means for providing a second signal when said first signal achieves a first relationship with said first threshold magnitude.

A photoelectric sensor, comprising:

• a light source;
• a light sensitive device, said light sensitive device providing a first signal representative of an intensity of light imposed on said light sensitive device, said light sensitive device being disposed to receive a beam of light from said light source;
• means for comparing said first signal to a first threshold magnitude in order to detect the presence of an object in the path of said beam of light;
• first means connected in signal communication with said light sensitive device for determining an updated value of said first threshold magnitude as a function of the maximum value of a magnitude of said intensity of light imposed on said light sensitive device during a first preselected period of time;
• means for deactivating said first determining means during a second preselected period of time;
• means for replacing a previous value of said first threshold magnitude with said updated value of said first threshold magnitude upon the detection of said object in the path of said beam of light;
• means for providing a second signal when said first signal achieves a first relationship with said first threshold magnitude;
• and
• second means for determining a second threshold magnitude as a function of said first threshold magnitude.