Auto-darkening filter of welding shield

An auto-darkening filter of a welding shield, the auto-darkening filter comprising:

• a brightness-sensing unit generating a first signal or a second signal, the first signal obtained from a base signal scaled by M time(s), the second signal obtained from the base signal scaled by N time(s), and N<M;
• wherein the brightness-sensing unit comprises
• an optical sensor generating the base signal directly proportional to environmental brightness sensed by the optical sensor;
• a signal amplifier connected to the optical sensor;
• and
• a gain controller connected to the signal amplifier;
• an optical shutter operating in a bright state or a dark state;
• and
• a processor connected to the signal amplifier, the gain controller, and the optical shutter, wherein
• the processor sends a control command to the gain controller, and the gain controller activates the signal amplifier to generate the first signal or the second signal according to the control command;
• when the processor operates in a higher-scaled-signal mode, the processor controls the brightness-sensing unit to generate the first signal, controls the optical shutter to operate in the dark state during a period that the first signal is higher than a threshold value, and controls the optical shutter to operate in the bright state during a period that the first signal is lower than the threshold value;
• and
• the processor changes to a lower-scaled-signal mode from the higher-scaled-signal mode when a change-mode command is received;
• in the lower-scaled-signal mode, the processor controls the brightness-sensing unit to generate the second signal, controls the optical shutter to operate in the bright state during a period that the second signal is lower than the threshold value, and changes to the higher-scaled-signal mode from the lower-scaled-signal mode when the second signal is higher than the threshold value and remains in the higher-scaled-signal mode after the first signal is no longer higher than the threshold value until the change-mode command is received.