Patent Grant
11311092
The present invention relates to a container for housing a stick product, such as lipstick.
A well known type of container (100) for an stick product features a base (3) that is connected to a cylindrical inner body (4), and a cam sleeve (1′) placed around the inner body, such that the cam sleeve and body can rotate with respect to each other. The inner body is hollow, and has a wall with at least one longitudinal slot that extends through the wall. The cam sleeve has an inner wall that features at least one helical groove that extends along a substantial length of the inner wall. A product holder cup (5) is provided with at least one cam follower in the form of a lug. When the holder cup is fitted into the inner body, the lug extends through the longitudinal slot of the inner body to engage the helical groove of the cam sleeve. In this arrangement, when the inner body is rotated (by rotating the base) relative to the cam sleeve, then the helical groove of the cam sleeve applies pressure to the lug of the holder cup, which drives the holder cup up or down in the longitudinal slot of the inner body, thereby moving the stick product between an advanced and a retracted position. As is commonly done, a cylindrical A-shell member is positioned over the cam sleeve, and glue is used between the A-shell and cam sleeve to ensure that these two members move as one. Because the base is connected to the inner body, and the A-shell is connected to the cam sleeve by glue, raising and lowering of the holder cup is achieved by rotating the A-shell relative to the base.
In assembly, some amount of glue is applied to the inner surface of the A-shell. The use of glue between the A-shell and cam sleeve is problematic. For example, after glue is applied to the inner surface of the A-shell, and while the glue is still wet, the cam sleeve is slid into the A-shell. This may force some of the glue toward the end of the cam sleeve where it will escape from between the cam sleeve and A-shell. This makes assembly messy, and incurs unwanted costs for cleaning and extra time to assemble. Also, the glue may contact the stick product, thus contaminating it. In this case, the product has to be discarded. Also, the amount and positioning of the of glue may no longer be suitable to ensure that the cam sleeve and A-shell will move as one over the life of the container.
To avoid these problems, U.S. Pat. No. 9,603,434 describes a lipstick tube assembly that does not use glue. That lipstick tube includes two different structural features that fix the A-shell to the spiral (i.e. cam sleeve). The key-slot structure is used for the circumferential fixation of the spiral and the A-shell. The clasp-clamping-groove structure is used for the axial fixation of the spiral and the A-shell. During the assembly, the spiral and the A-shell must be fixedly matched with each other by the two structures. The greatest disadvantage of this, and other mechanisms, is the need for a relatively complicated A-shell design. The A-shell, which in its simplest form is a thin-walled tube, becomes rather more complex, requiring a multiplicity of axial splines formed on the inner surface, and an edged that is curled back on itself. The cam sleeve also requires extensive customization, such as 90 longitudinal grooves on its outer surface to engage the splines of the A-shell. While glue is not used, the design is complicated and relatively costly. In contrast, the present invention requires minor customization of the cam sleeve and no alteration of the conventional A-shell.
A main object of the present invention is to provide a mechanism for a stick product wherein the A-shell-to-cam sleeve assembly is simple and does not use glue.
A glue-free lipstick case according to the present invention comprises an A-shell and cam sleeve with no glue in between. Rather, the cam sleeve is provided with one or more flexible tabs on its outer surface. The flexible tabs bias in a radially outward direction. The A-shell member fits snugly over the cam sleeve and flexible tabs, such that the outward pressure exerted by the tabs on the inner surface of the cam sleeve helps to ensure that the two members move as one. Optionally, an anti-slip varnish may be applied between the A-shell inner surface and an inner surface of the cam sleeve, such as on the flexible tabs of the cam sleeve. This would further ensure that the A-shell and cam sleeve move as one.
Containers according to the present invention may be useful for all types of stick products that are applied to a surface by drawing the product across a surface. These include lipsticks, lip balms, deodorant sticks, anti-perspirant sticks, glue sticks, etc.
Throughout the specification, the term “comprises” means that a collection of objects is not necessarily limited to those explicitly recited, but may or may not include additional objects.
Herein, the term “glue” refers to any type of adhesive that bonds two surfaces together such that a significant non-zero tensile force is required to break the bond. Glues include solvent-based and polymer dispersion adhesives, pressure-sensitive adhesives and contact and hot melt adhesives that join two surfaces together.
For purposes of the present invention, a stick product is an elongated mass of solid or semi-solid product that is able to support its own weight when the elongated mass is suspended by one end.
Cam Sleeve
A cam sleeve (1) according to the present invention is shown in
Referring to
In general, all of the recessed tabs (1d) do not need to be located at the same height along the cam sleeve (1). However, it may be preferable to have all of the recessed tabs located at the same height along the cam sleeve. Preferably, there are at least two recessed tabs (1d) symmetrically located around the cam sleeve. Preferably, the total annular extent of the flexible tabs is at least 25% of the circumference of the cam sleeve, more preferably at least 50%, and even more preferably at least 75% of the circumference of the cam sleeve. Preferably, when the flexible tabs (1d) are resting against the recessed walls (lf), at least some portion of the flexible tabs will extend beyond the outer surface (la) of the cam sleeve. In other words, the diameter of the cam sleeve measured over the flexible tabs is greater than the diameter of the cam sleeve measured away from the flexible tabs.
A-Shell
As shown in
To achieve a sufficient amount of static friction, the diameter of the cam sleeve (1) measured over the flexible tabs (1d) and the diameter of the inner surface of the A-shell (2) are sized for a minimum amount of interference. For example, the diameter of the cam sleeve (1) measured over the flexible tabs should be at least 0.02 mm greater than the diameter of the inner surface of the A-shell; preferably at least 0.05 mm greater, more preferably at least 0.08 mm greater than the diameter of the inner surface of the A-shell.
The frictional force between the A-shell and the flexible tabs acts in any direction, (i.e. axially or circumferentially), therefore, two separate mechanisms are not required (as in U.S. Pat. No. 9,603,434). Optionally, an anti-slip varnish (1g) may be applied between the A-shell inner surface and an outer surface of the cam sleeve. If an anti-slip varnish is used, then preferably the anti-slip varnish is applied to the flexible tabs of the cam sleeve. The anti-slip varnish would increase static friction between the A-shell and cam sleeve, without creating a permanent bond therebetween. Because the tabs are relatively small, and anti-slip varnish is relatively thin, and because the varnish is dried prior to the assembly of the A-shell and the cam sleeve, there is no concern that the varnish will smear in the way that glue does, as explained above.
| Number | Name | Date | Kind |
|---|---|---|---|
| 9603434 | Zhu et al. | Mar 2017 | B2 |
| 10881184 | Yan | Jan 2021 | B1 |
| Number | Date | Country |
|---|---|---|
| WO-2021128657 | Jul 2021 | WO |
