Reflective wetness detector

A reflective detector of a wetting event on a region of a test medium, the detector comprising:

• a solid state source of a beam of radiant energy wherein said beam is incident on the region at an angle less than ninety degrees;
• a solid state sensor of radiant energy reflected from the region wherein said sensor is oriented normal to at least a part of the region and wherein said sensor generates on electrical signal indicative of the detected, reflected, radiant energy;
• and
• an amplifier circuit coupled to said sensor wherein said amplifier has a first dynamic range and includes circuitry for expanding said first dynamic range to a second, greater, dynamic range.

A reflective apparatus for detecting a wetting event on a region of a test medium comprising:

• a hollow housing having first and second ends and defining an internal channel therebetween wherein said channel extends substantially perpendicular to the medium with one end closer to the medium than the other;
• a sensor coupled to said other end;
• a solid state source of radiant energy, oriented at an acute angle relative to the medium and on the same side thereof as said housing;
• conditioning circuitry for detecting a wetting event on the medium, indicated by a drop in reflected radiant energy wherein said circuitry includes threshold establishing circuitry with first and second establishing rates.

A media analysis system comprising:

• a media transport unit;
• an injection unit for depositing a wetting fluid on a portion of a medium being analyzed;
• a solid state source of radiant energy for directing a beam of radiant energy toward the medium at an acute angle;
• a solid state sensor of radiant energy reflect from the medium wherein said sensor is perpendicular to a line normal to the medium;
• and
• conditioning circuitry, coupled to said sensor, wherein said circuitry includes a comparator for comparing a signal indicative of reflected radiant energy to a variable threshold value wherein said value is established at first and second rates wherein said rates are different.

A method of detecting a wetting event on a medium comprising:

• directing radiant energy toward an analysis location;
• moving a medium to the location;
• detecting radiant energy reflected from the medium along a line normal to the medium;
• establishing a variable threshold value as the medium is moved to the location wherein the value is established, in part, at a first rate as the medium is moved to the location and at a second, lower rate, when the medium is at the location;
• producing a signal indicative of reflected radiant energy when the medium is at the location:
• depositing a fluid into at least a portion of the medium;
• comparing the signal to the variable threshold, and, in response to a drop in reflected radiant energy due to said deposited fluid, generating an output, wetting event indicating signal.