A collapsible frame for use in erecting tents, canopies and the like at outdoor venues includes a plurality of telescopic legs for providing vertical structural support, and a plurality of top corner joints each fixedly mounted upon a top end of a corresponding telescopic leg. Baffles are provided to direct solids to the outlet and minimize the time that solids spend in the concentration tank. This feature may help make electronic pens or styli thinner and dimensioned more consistent with their non-electronic counterparts. Additionally portions of the overflow from the thickener are returned to the feed tank and fed to the autoclave discharge tank. A capacitor, a resistor and a diode are connected in series with each other between the DC power supply lines. The detected information processing unit is configured to detect gray contamination of the paper sheet from an image detected by simultaneously turning on the plurality of light sources and to detect wrinkles or folds of the paper sheet from an image detected by turning on one of the plurality of light sources.