DESCRIPTION Title of Invention YARN WINDER. Technical Field [ 0001] The present invention relates to a yarn winder (yarn winding device). Background Art [ 0002] Patent Literature 1 recites a yarn winder that includes: a yarn supplying portion for unwinding a yarn from a yarn supplying bobbin; a winding section for winding the unwound yarn to form a package; a yarn jointing section that is provided between the yarn supplying portion and the winding section to perform yarn jointing when yarn breakage occurs/ a yarn defect is detected, or the yarn supplying bobbin runs out of the yarn; and a vessel that is formed between the yarn jointing section and the winding section to store the yarn. [ 0003] In this winding device, a yarn unwound from the yarn supplying bobbin is temporarily stored in the aforesaid vessel of the yarn storage section, and -he winding section draws out the yarn stored in the vessel and forms a package. This arrangement makes it possible to continue the winding of the yarn by the winding section while the yarn jointing section is performing yarn jointing. Citation List Patent Literatures [0004] Patent Literature 1: U.S. Patent NO. 3314621 Summary of Invention Technical Problem [0005] The yarn winder of Patent Literature 1, however, is disadvantageous in that the yarn stored in the vessel may be entangled. To solve this problem, the inventor cf the present invention hit on the idea that a yarn storage section storing the yarn in such a way that the yarn unwound from the yarn supplying bobbin was wound thereon was provided in place of the vessel for storing the yarn, and the yarn wound on the yarn storage section was unwound and a package was formed from the yarn by the winding section. [0006] This arrangement, however, involves a problem in that, when the yarn is unwound from the yarn storage section, the yarn swells and a balloon is formed. When such a balloon becomes large in size, the tension of the yarn may be fluctuated or a problem may occur as the yarn contacts a part of the yarn winder. [0007] In addition to the above, when a yarn unwound from a yarn supplying bobbin is wound into another package as discussed earlier, broken filaments of the yarn are preferably laid down before being wound into the package. Furthermore, as the yarn is wound while being traversedf a tension is preferably jmparv.ftc tc the yarn, when the yarn is wound, in order to ensure the traversing - [0008] An object of the present invention is to provide a yarm winder in. which a balloon generated when a yarn is unwound f rem a yarn storage section does not become large. Solution to Problem [0009] According to the first aspect cf the invention, a yarn winder includes: a yarn supplying pcrtion for unwinding a spun yarn from a yarn supplying bobbin; a winding section for winding the spun yarn so as to form a package; a yarn storage section which is provided between the yarn supplying portion and the winding section to wind and store the spun yarn; and a balloon regulator for regulating a balloon by contacting tha spun yarn unwound from the yarn storage section toward the winding section si.de. [0010] According to the present invention, because the balloon is regulated as the spun yarn unwound from the yarn storage section and running toward the winding section contacts the balloon regulator it is possible to prevent the unwinding tension from becoming great on account of the enlargement of the balloon. [ 0011] According to the second aspect, the yarn winder of the first aspect, is arranged so that the balloon regulator contacts and imparts resistance to the spun yarn that is unwound from the yarn storage section to the winding section side and tends to swell outward. [ 0012: According to the present invention, because the enlargement of the balloon occurring when the spun yarn is unwound Iiom Lhe ydxn S Luidye secLiun is -tea trained/ i I, XS possible to prevent the balloon from becoming large and contacting another component such as the main bedy of the yarn winder. [ 0013] According to the third aspect, the yarn winder of the second aspect is arranged so that the fcslloon regulator is composed of an annular component which is arranged to enclose the spun yarn unwound from the yarn storage sacticn. " [ 0 014] According to the presen- invention, because the balloon regulator is composed of the annular component which is arranged to enclose the spun yarn unwound from the yarn storage section and running toward the winding section, the enlargement of the balloon is certainly restrained. [ 0015] According to the fourth aspect, the yarn winder of the third aspect is arranged so that the annular component is made of an elastic material and arranged to contact the yarn storage section, and the spun yarn unwound from the yarn storage section is sandwiched between the annular component and the yarn storage section. [ 0016] According to the present invention, because the spun yarn unwound from the yarn storage section is sandwiched between the annular component made of an elastic material and the yarn storage section, the broken filaments of the spun yarn unwound from -the yarn storage section and running toward the winding section are laid down, and a tension is imparted to the spun yarn. [ 0017] According to the fifth aspect, the yarn winder of the fourth aspect is arranged so that the annular component is made of 5. rubber material. [ 0016; According to the present invention, because the annular component is made of a rubber material which is easily elastically deformed, the annular component is easily attached and replaced. [ 0019] According to the six~h aspect, the yarn winder of the fourth or fifth aspect is arranged so that, because the annular component contacts the yarn storage section while being elastically deformed, at least a part of the annular component surface-contacts, in its entire circumference, the yarn storage section. [ 002U] According to the present invention, because the annular component contacts the yarn storage section while being elastically deformed and hence at least a part of the component surface-contacts, in its entire circumference, the yarn storage section, it is possible tc certainly lay down the broken filaments of the spun yarn sandwiched between the annular component and the yarn storage section. [ 0021] According to the seventh aspect, the yarn winder of the sixth aspect is arranged so that an end portion of the yarn storage section on the unwinding side of the spun yarn has a circular curved surface narrowing toward the center of the spun yarn, and the annular component is arranged so that a difference between the radius at the outer circumference and -he radius at the inner circumference is longer than the thickness, and a part of the annular components which part is between the outer circumference and the inner circumference is elastically deformed along the circular curved surface of the yarn storage section so as to surface-contact the circular curved surface of the yarn storage section. [ 0022- According to the present invention, an end portion of the yarn storage section on the unwinding side of the spun yarn has a circular curved surface and the annular component is arranged so that a difference between the radius at the outer circumference and the radius at the inner circumference is longer than the thickness, and a part of the annular components which part is between the outer circumference and the inner circumference is elascically deformed along the circular curved surface of the yarn storage section so as to surface-contact the circular curved surface of the yarn storage section. For this reason, the area where the annular component surface-contacts the yarn storage section is large. This makes it possible to certainly lay down the broken filaments of the spun yarn unwound from the yarn storage section. [ 3023] According to the eighth aspect, the yarn winder of the fifth aspect is arranged so that the yarn storage section has a rotational storage drum which rotates so as to wind and store the spun yarn, and the annular component is smaller in diameter than the rotational storage drum and is attached to the rotational storage drum while being elongated. [ 0 024] According to the present invention, because the annular component which is shorter in diameter than the rotational storage drum and made of a rubber material is attached onto the rotational storage drum while being elongated, the rotational storage drum and the annular .component rotate together. This prevents the annular component from being worn away by the rotational storage drum. [ 0025] According to the ninth aspect, the yarn winder of the eighth aspect is arranged so that, at a part of the rotational storage drum which part is on the unwinding side of rhe spun yarn as compared to a part where the annular component is attached, an enlarged portion is formed to be widened toward the unwinding side. [ 0026] According to the present invention, as the annular component is caught on the enlarged portion, it is possible to prevent the annular component from being pulled by the unwound spun yarn and dropping off from the rotational storage drum. [ 0027] According to the tenth aspect, the yarn winder of the third aspect is arranged so that the annular component is distanced fxom the yarn storage section and encloses the spun yarn which is unwound from the yarn storage section and conveyed to the winding section. [ 0028] According to the present invention, because the annular component is positioned to be distanced from the yarn storage section, the spun yarn can easily pass through gap between the annular component and the yarn storage section at the time of yarn threading, and it is possible to restrain the cotton fly of the spun yarn from remaining in the gap between the annular component and the yarn storage section. [ 0029] According to the eleventh aspect, the yarn winder of the tenth aspect is arranged so that the annular component is hollow and has a triangular pyramid shape narrowing in diameter toward the winding section side. [ 0030] According to ~he present invention, because the annular component has a triangular pyramid shape, it is possible to certainly restrain the enlargement of the balloon. [ 0031] According to the twelfth aspect, ~he yarn winder of any one of the first to eleventh aspects is arranged so thar a yarn jointing section which is provided between the yarn supplying portion and the winding section to perform yarn jointing of the spun yarn; and a controller for controlling a winding operation performed by the winding section and the yarn jointing by the yarn jointing section, the controller conducting control so that the yarn jointing by the yarn jointing section and the yarn winding operation by the winding section are simultaneously performed, [ 0032] According to the present invention, the yarn jointing is performed without interrupting the winding of the spun yarn onto the winding section. [ 0033] According to the thirteenth aspect, the yarn winder of any one of first to twelfth aspects is arranged so that the yarn supplying portion is provided with a yarn unwinding assisting device which assists unwinding of the spun yarn from the yarn supplying bobbin by lowering the regulator covering the core of the yarn supplying bobbin in sync with the unwinding of the spun yarn from the yarn supplying bobbin. [ 0034] According to the present invention, because the transmission of the tension of the yarn is blocked by providing the yarn storage section between the yarn supplying bobbin and the winding section, it is possible to prevent a tension change due to the traversal of the winding section from being transferred to the part of the yarn unwound from the yarn supplying bobbin. Since the yarn unwinding from the yarn supplying bobbin is stably performed as the unwinding assist unit is additionally provided on the yarn supplying bobbin, it is possible to prevent yarn breakage and to accelerate the spaed of unwinding from the yarn supplying bobbin. The efficiency in the unwinding from the yarn supplying bobbin is therefore improved. Effects [ 0035] According to the present invention, because the balloon is regulated as the spun yarn unwound from the yarn storage section and running toward the winding section contacts the balloon regulator, it is possible to prevent the unwinding tension from becoming great on account of the enlargement of the balloon. Brief Description of Drawings [ 0036] Fig. 1 is a front elevation of a winding unit. Fig. 2 is a front elevation of an accumulator. Fig. 3 (a) is a plan view of an annular component provided on the yarn storage drum, Fig. 3(b) is an axial direction cross section of the annular component before the component is elastically deformed, and Fig. 3 (c) is an axial direction cross section of the annular component when the component is elastically deformed. Fig. 4 shows the electric configuration of the winding unit. Fig. 5 illustrates the movement of the spun yarn on the outer circumference of the accumulator. Fig. 6 shows the start of the drawing out of a spun yarn. Fig. 7 shows the completion of the drawing out of the spun yarn. Fig. 8 shows the drawing out of a yarn defect of a spun yarn. Fig. 9 is a control flow of normal winding. Fig. 10 is a control flow at the time of yarn breakage. Fig. 11 is a control flow for preventing yarn shortage. Fig. 12 is a control flow at the time of yarn cutting. Fig. 13 is a control flow at the time of bobbin change. Fig. 14 relates to a modification 1 of the present invention and corresponds to Fig. 2. Fig. 15 relates to a modification 2 of the present invention and corresponds to Fig. 2. Fig. 16 relates to a modification 3 of the present invention and corresponds to Fig. 2. Fig. 17 relates to a modification 4 of the present invention and corresponds to Fig. 2. Fig. 18 relates to a modification 5 of the present invention and corresponds to Fig. 2. Description of Embodiments [ 0037]