| 摘要 |
<p>A filter device for a smoking rod has a notch (ll) formed in a plug core (9) and plugwrap (l0). Air may be drawn into the core (9) through an air-permeable tipping wrapper (8). The filter efficiency, smoke dilution and draw resistance of the filter device can be controlled by varying the number and shape of the notches. The invention also provides for the smoke dilution to be variable under the control of the smoker by arranging for the air-permeable part of the tipping wrapper (8) to be rotatable into and out of alignment with the notch (ll), with the extent of rotation limited by a projection (l4) formed on the inner surface of the wrapper (8) and located in the notch (ll).</p> |
