Patent ID: 7858893

Claim:
A method of sorting object types comprising a population to be sorted into one of at least a first class and a second class, the method comprising: (1) determining a percent reflectance from each object type comprising the population to be sorted at light wavelengths across a spectrum of light wavelengths comprising wavelengths from about 400 nm to about 1700 nm, (2) calculating the difference in percent reflectance between each object type comprising the population to be sorted at light wavelengths across the spectrum of light wavelengths from about 400 nm to about 1700 nm, (3) selecting a light wavelength wherein the difference in percent reflectance between each object type comprising the population is greatest, thereby discovering a desired wavelength, (4) loading a population to be sorted which comprises the object types onto an apparatus for sorting objects, wherein the apparatus comprises: (i) a product feeding means, (ii) a light source, (iii) a sensing area, (iv) a light conducting means, (v) an optical bandpass filter centered at the desired wavelength and a photodiode which form an optical bandpass filter-photodiode combination centered at the desired wavelength, (vi) a decision circuit, and (vii) a diversion means wherein the product feeding means delivers an object to be sorted to the sensing area where the object is illuminated by the light source, and wherein light is reflected from the illuminated object, and the reflected light enters the light conducting means at an input end and travels toward an output end of the light conducting means where it is incident on an optical bandpass filter selected to have a passband centered at the desired wavelength of light, and wherein the optical bandpass filter transmits light to the photodiode in a band of wavelengths centered at the desired wavelength, and wherein the photodiode converts the light transmitted through the optical bandpass filter to an electric current, thereby generating a signal related to the desired wavelength that is input to the decision circuit, and wherein the decision circuit is an electronic circuit that does not require a microprocessor to evaluate signals and make decisions, and wherein the decision circuit drives the diversion means, (5) setting a threshold value for activation of the diversion means by the decision circuit, and (6) activating the apparatus for sorting objects, thereby sorting object types comprising a population to be sorted into one of at least a first class and a second class.