Abstract: A stream of filter tow which has been sprayed with atomized plasticizer is advanced past two detectors each of which monitors the density of the stream in a different way and generates corresponding signals which are processed by an evaluating circuit to generate modified signals which are indicative of the percentage of plasticizer. The modified signals are used to regulate the operation of a pump which controls the rate of admission of plasticizer to successive increments of the tow.

Abstract: The density of successive increments of a cigarette rod is measured by an apparatus which employs one or more photocells operating with ultraviolet, infrared or visible light. The radiation source of each photocell emits a beam of ultraviolet, infrared or visible light which penetrates through the wrapper and the filler of the rod and thereupon impinges upon one or more transducers which transmit signals denoting the density of the monitored portion of the rod to an evaluating circuit. The beams which are emitted by two or more discrete radiation sources are or can be angularly offset with reference to each other, and the evaluating circuit processes the signals from the photocells to generate a single signal which is indicative of the density of the monitored increment of the rod and is used to adjust the trimming device and/or the ejector for defective cigarettes.

Abstract: The density of successive increments of a cigarette rod is measured by an apparatus which employs one or more photocells operating with ultraviolet, infrared or visible light. The radiation source of each photocell emits a beam of ultraviolet, infrared or visible light which penetrates through the wrapper and the filler of the rod and thereupon impinges upon one or more transducers which transmit signals denoting the density of the monitored portion of the rod to an evaluating circuit. The beams which are emitted by two or more discrete radiation sources are or can be angularly offset with reference to each other, and the evaluating circuit processes the signals from the photocells to generate a single signal which is indicative of the density of the monitored increment of the rod and is used to adjust the trimming device and/or the ejector for defective cigarettes.