It is well known, for example, from U.S. Pat. No. 1,829,559, to form cigarettes of two or more different types of smoking materials, wherein one type of smoking material predominates in an inner core while another type of smoking material predominates in an outer annulus totally surrounding and enclosing the core.
It is also well known that a substantial proportion of the tobacco smoke entering a smoker's mouth results from the burning of tobacco in the peripheral regions of the cigarette. It is estimated that about 80% of the volume of smoke entering the smoker's mouth originates from only about 50% of the weight of tobacco in the cigarette.
It is further well known that, when a cigarette is first lit up, smoke from the burning of tobacco material in the whole cross-section of the cigarette is drawn into the smoker's mouth and not predominantly from the burning of annulus material, thereby producing a different taste for the smoker upon lighting up of such prior art composite cigarettes.
This particular problem of prior art composite cigarettes has been solved. In copending U.S. patent application Ser. No. 862,202 filed May 13, 1986, assigned to the assignee hereof and the disclosure of which is incorporated herein by references, there is described a cigarette in which additional quantities of the annulus material are provided in the lighting end of the cigarette, so that, upon the cigarette being lit, the smoke reaching the mouth of the smoker is derived mainly from annulus material. In this way, little or no change in the taste of the tobacco smoke is perceived by the smoker as the burning proceeds from light up to continued smoking.
In prior art composite cigarettes, the emphasis has been on using a core of poor quality tobacco and an annulus of higher quality tobacco. It is essential to the effectiveness of such composites for the poorer quality tobacco to be surrounded by and enclosed within the annulus of higher quality tobacco, in view of the poor smoking characteristics of the poorer quality tobacco contemplated for such cigarettes. While economies in tobacco usage are achieved, these structures do not, in any way, address questions of taste and tar content of the tobacco smoke.
Currently, the trend in cigarettes is towards cigarettes with lower tar levels in cigarette smoke. However, such lesser tar levels generally have also resulted in lower levels of flavour, which is considered undesirable by certain smokers. Prior attempts to increase flavour with lower tar cigarettes have included the use of flavouring additives.
USPTO Backgrounds
USPTO Backgrounds