The cigarette package of this type comprises an inner pack and a parallelepiped outer box enclosing the inner pack. The inner pack includes a bundle of rod-shaped smoking articles, such as filter cigarettes, and an inner wrapper covering the bundle. The outer box includes a box body open at the upper end thereof, and a lid joined to the box body at a rear edge of the open end of the box body, which functions as a hinge. The outer box is formed by folding a blank around the inner pack.
The lid of the outer box can be a hinged lid in the shape of a box, or a tongue lid having a tongue. While the hinged lid is fitted on top of the open end of the box body, the tongue lid has an upper wall for covering the open end of the box body and a tongue extending from the upper wall designed such that when the upper wall closes the open end of the box body, the tongue overlies the front wall of the box body.
[Patent Document 1] Japanese Unexamined Patent Publication No. Hei 11-49134
It is desirable that at the time the above-described cigarette package is made, the lid of the outer box should be joined to the box body by a tearable separation line. The provision of such separation line is effective in deterring people from tampering with the cigarette package.
More specifically, when the lid is first opened, the lid is torn from the box body along the separation line, and the torn separation line leaves break marks to the box body as well as the lid, which marks indicate that the lid has already been opened.
Generally, the separation line is provided as a perforated line formed in the blank for the outer box in advance. The perforated line, i.e., the separation line has a lot of joins connecting the adjacent perforations. Thus, when the lid is first opened, first, a join at one end of the separation line suffers a break, and the adjacent joins suffer such break one after another, so that the separation line completely breaks. In other words, the separation line breaks in the manner that a crack spreads.
However, the crack does not infallibly spread along the separation line, but can spread deviating from the separation line. Such deviating crack can give an undesired break to the tongue lid and/or the box body, and therefore lead to a damaged appearance of the cigarette package opened.
Such trouble can be avoided by making the joins of the separation line shorter so that the joins can be broken easily. This can, however, cause a problem that in the process of making a cigarette package, specifically in folding the blank, the blank splits along the separation line so that the cigarette package fails to be made.