Abstract:
One embodiment of a chemiluminescent device, suitable for impact activation, has the external form of a spherical tube structure with a length to width ratio of 0.5:1 to 3:1 and an internal brittle ampoule floating freely within an external tough shell. This form of the chemiluminescent device is very suitable for use in throwing, especially for fixed point throwing and limited space throwing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of Chinese Patent Application No. 200720097116.7, filed Aug. 16, 2007, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The application relates to a chemiluminescent device suitable for impact activation and for use in throwing. 
       TECHNICAL BACKGROUND 
       [0003]    Chemiluminescence is a phenomenon in which light is generated and emitted by the chemical reaction of substances. 
         [0004]    The traditional chemiluminescent device is a thin long stick or tube, commonly known as a “light stick.” More recently, a variety of such products with different shapes, including a disk shape, have been made. 
         [0005]    The traditional chemiluminescent device has a flexible external shell in the form of a tube. In storage, the tube contains two liquid components separated from each other by a fragile barrier, a typical example of which is a glass ampoule in the form of an inner tube. When chemiluminescence in the chemiluminescent device is required, the glass ampoule is broken by snapping, and the separated chemical components in the device mix and react to generate chemiluminescence. Typically the ampoule is broken by bending the flexible tube with pressure until the ampoule snaps, then the tube is shaken to mix the components inside to produce chemiluminescence. 
         [0006]    However, in certain activities, it may be desired to throw an unactivated chemiluminescent device to a target area at a distance, in such a way that the chemiluminescent device is activated through the impact of hitting the ground or other hard surface to generate light. Under such circumstances, the chemiluminescent device cannot be activated by the traditional method of snapping the tube for activation. The current light stick, owing to the limitations of its structure, needs to be quite long in order to be reliably activated by impact. Such products are currently marketed with a length reaching 380 mm (15 inches). However, such length will adversely affect the use of the device in throwing, for example, such a long stick is not suitable for fixed point throwing, and is also inconvenient for throwing in a limited space. 
       SUMMARY OF THE INVENTION 
       [0007]    According to one embodiment of the invention, there is provided a chemiluminescent device suitable for impact activation and for use in throwing. It has an external form different from the traditional chemiluminescent stick, beneficial for use in throwing to a target area at a certain distance for activation; additionally this external form is also beneficial for throwing in a limited space. 
         [0008]    According to one embodiment of the invention, there is provided a chemiluminescent device suitable for impact activation and for use in throwing, having an external form adopting a spherical tube structure. The external form of the chemiluminescent device adopting a spherical tube structure mentioned above may be of a cylindrical, oblong, or polygonal shape with the “length to diameter ratio” lying between 0.5:1 and 3:1. Such a shape can give the device good throwing mechanics. 
         [0009]    The glass used as separation material for the ampoule within the chemiluminescent device suitable for impact activation and for use in throwing mentioned above can be made into shapes that are able to be fitted into the external shell which includes spherical, oblong and cylindrical shapes. 
         [0010]    One embodiment of a chemiluminescent device suitable for impact activation and use for throwing has an external shell of high polymer material, such as polyethylene, polypropylene, polyester, etc. 
         [0011]    The advantages made possible by embodiments of the devices described in the present application include the following: the traditional chemiluminescent stick usually has to be snapped by hand for activation. Even if the traditional chemiluminescent stick can be impact activated and used for throwing, it has to have a sufficient length to facilitate activation, thus detracting from its throwability. Chemiluminescent devices described in the present application can have an external shell that is very suitable for use in throwing, and that is very advantageous for fixed point throwing and throwing in a limited space. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
           [0013]      FIG. 1  is a cross section of a chemiluminescent device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Referring to the accompanying drawings, one example of a chemiluminescent device according to an embodiment of the present invention is indicated generally by the reference number  10 . The device  10  comprises an outer shell  12 . As shown in  FIG. 1 , the shell  12  comprises two hemispheres or half shells  14  and  16 , made of polypropylene or other suitable material, such as high polymer polyethylene or polyester, welded together at  18 . The outer shell  12  is of generally spherical tubular form, and may be, for example, spherical, oblate or prolate spheroidal or other oblong, polygonal (prismatic or polyhedral), or cylindrical. The length or maximum dimension of the shell  12  may be from about 0.5 to about 3 times the width, diameter, or minimum dimension of the shell  12 . The shell  12  may be of a convenient size to be held in the hand of a person intending to throw the device. For example, a device about 3 or 4 inches (7 to 10 cm) across may be suitable for many purposes. 
         [0015]    Inside the outer shell  12  is an inner shell that in the device  10  shown in  FIG. 1  is in the form of a sealed thin-walled hollow ball  20  of glass or other brittle material. As shown in  FIG. 1 , the ball  20  has a blow molding orifice  22 . The orifice  22  may be used for filling of the glass ball  20  and then sealed. 
         [0016]    The glass ball  20  and the space between the outer shell  12  and the glass ball are partially filled with two liquids  24  and  26  that react to produce light when they are mixed. The liquids may be liquids that are already known as a two-component chemiluminescent system. Traditional chemiluminescent systems use components that are low-viscosity liquids, so that they can be easily mixed by shaking, and that are reasonably stable until they are mixed. 
         [0017]    The outer shell  12  is desirably sufficiently stiff and rigid that the shell does not distort appreciably in normal storage and handling and even when being thrown, thereby preventing crushing of the inner ball  20 . The inner ball  20  is sufficiently brittle to shatter during impact onto a hard surface when thrown. The cushioning provided by the outer shell  12  and the liquid  26  may reduce the impact loads on the inner ball and may call for a thinner or more brittle ball than would otherwise be appropriate. The person of ordinary skill in the art will have no difficulty in selecting the materials and thicknesses for the inner ball  20  and the outer shell  12 . For the inner ball  20  of the device shown in  FIG. 1 , a ball of ordinary glass with a thickness of 0.8 mm or less at the thinnest part of the ball has been found to be satisfactory. Factors to be taken into consideration include the size and intended use of the device  10 , the composition and amount of the liquids  24  and  26 . A principal objective is to produce the correct balance between robustness in storage and handling and reliable shattering of the inner ball  20  on impact. 
         [0018]    As shown in  FIG. 1 , the outer shell  12  and the inner ball  20  are only partially filled. The incomplete filling may impair the throwing characteristics of the device, by allowing the weight of the liquid to be unevenly distributed or to move around, but for a device intended to be thrown by hand the advantages of an incompletely filled device for impact activation are believed to outweigh any reduction in the ballistic properties. The ratio of the volume within the inner ball  20  to the volume between the outer shell  12  and the inner ball  20  may be in the range of from 10:1 to 1:10. 
         [0019]    In use, a person takes the chemiluminescent device  10  and throws the device against a hard surface. When there is an impact, the outer shell  12  will experience a slight change in shape, regardless of its strength. The inner ball  20  is floating loose within the outer shell. Without wishing to be limited to a specific theory, it is believed that when the device  10  hits a hard surface, the speed of the outer shell  12  drops rapidly to zero. However, the inner ball  20 , experiencing little resistance from the low-viscosity liquid surrounding it, continues to move quickly. The inner ball  20  eventually runs into the outer shell  12  and breaks. Continued movement of the liquid components  24 ,  26  after impact causes the two liquids become mixed, and chemiluminescence is generated. 
         [0020]    The outer shell  12  is made of a plastic that is tougher than the inner ball  20  of glass. As in a traditional chemiluminescent light stick, the outer shell  12  does not break when the inner ball  20  breaks. The outer shell  12  thus contains the chemiluminescent mixed liquid, ensuring a compact, bright, light and preventing contamination of the surroundings by the liquid. The outer shell  12  also contains the fragments of the ball  20 , avoiding the risk of injury if the fragments are sharp. 
         [0021]    Although it might seem in theory that (especially if the densities of the two liquids  24 ,  26  are similar) the outer liquid  26  will support the inner ball  20 , in practice that has not been found to be a problem. In particular if, as shown in  FIG. 1 , the level of liquid  24  in the inner ball  20  is higher than the level of liquid  26  in the outer shell  12 , the inner ball  20  will tend to sink to the bottom of the outer shell  12 . In that case, when the outer shell  12  is abruptly stopped by impact with a hard surface, the inner ball  20  will tend to continue moving until it strikes the part of the outer shell that is against the hard surface. Conversely, when the device  10  is thrown, the acceleration of the outer shell  12  typically results in the rear of the outer shell striking the inner ball  20 . If the level of liquid  24  in the inner ball  20  is lower than the level of liquid  26  in the outer shell  12 , the inner ball will tend to float in the outer liquid  26 , and to experience contrecoup impacts with the opposite side of the shell  12 . 
         [0022]    In any case, however, the acceleration when the device  10  is thrown by hand is less than the deceleration when the device hits a hard surface. It is thus possible to select the robustness of the inner ball  20  so that the device  10  will reliably activate on impact with a hard surface at the target, but will reliably not activate on throwing. Non-activation of the device  10  on throwing is important in some games to avoid revealing the location of the thrower, and in many other uses for esthetic or dramatic effect. 
         [0023]    The device  10  may be so constructed that the inner shell or ball  20  will break, permitting the two liquids to mix, if the device is dropped onto a flat hard surface from a height of 2 meters, but not if dropped from a lesser height, and the outer shell  12  will not break if the device is dropped onto a flat hard surface from a height of 10 meters. 
         [0024]    Although specific embodiments have been described, the skilled reader will understand how features of different embodiments may be combined and substituted, and such combinations are within the scope of the present invention.