IR flame amplifier

A flame detector for use with a photocell which produces a flame signal when exposed to a flame, the flame detector comprising:

• input means, coupled to the photocell, for receiving and buffering the flame signal thereby providing a buffered signal;
• filter means, coupled to the input means, for filtering and amplifying the buffered signal thereby providing a filtered flame signal;
• output means, coupled to the filter means, for further amplifying the filtered flame signal thereby providing an output flame signal;
• switch means, coupled to the photocell, for selectively, substantially short circuiting the flame signal to a known voltage value;
• and
• hot refractory detection means, coupled to the photocell for detecting a flame-out condition and generating an HRD signal causing the flame signal to be substantially short circuited to a known voltage value thereby eliminating a false flame signal caused by hot refractory shimmering.

A flame signal amplifier for use with a flame detector that produces a flame signal, having an AC component and a DC component, when exposed to a flame, the flame signal amplifier comprising:

• input means, coupled to the flame detector, for receiving and buffering the AC component of the flame signal, thereby providing an AC buffered flame signal;
• filter means, coupled to the input means, for filtering the AC buffered flame signal, thereby providing an AC filtered flame signal;
• and
• output means, coupled to the filter means, for full wave rectifying the AC filtered flame signal, amplifying the AC filtered flame signal, and converting the AC filtered flame signal into a flame output signal that is substantially a DC signal.

A flame detector, comprising:

• a photocell for producing a flame signal having an AC and a DC component, when exposed to a flame, the photocell producing the flame signal across a first and a second terminal where the first terminal is substantially at ground potential to facilitate bypassing noise to ground;
• input means, coupled to the photocell, for receiving and buffering the AC component of the flame signal thereby providing an AC buffered flame signal;
• filter means, coupled to the input means, for filtering the AC buffered flame signal thereby producing an AC filtered flame signal;
• output means, coupled to the filter means, for amplifying the AC filtered flame signal to provide a flame output signal;
• and
• switch means coupled to the input means, for substantially short circuiting the AC component of the flame signal to a known voltage level upon receiving a switch-close signal.