Patent Publication Number: US-7721510-B2

Title: Vial capping device and vial capping method

Description:
TECHNICAL FIELD 
   The present invention relates to a vial capping device endowed with a function by which rotation of a cap is locked through engagement of a cap engagement portion and a rotation restricting portion of a vial, and to a capping method. 
   BACKGROUND ART 
     FIG. 17  shows a filling device for filling a vial with tablets in which a cap  210  is put on a vial  220  to seal in tablets. A medicinal information label  221  for a patient is affixed to the side surface of the vial  220 . The vial  220 , which has been in use for a long period of time, is devised so as to prevent an infant from opening the vial easily. That is, to open it, it is necessary to press the upper surface of the cap against the vial while turning the cap, so even an adult cannot open the cap easily, which results in a bother. 
   As shown in  FIG. 18A , the cap  210  has an inner cover  211  on its inner side. A flange portion  212  of the inner cover  211  is held by engagement portions  213  protruding on the inner side of the cap  210 . As shown in  FIG. 18B , the engagement portions  213  is engaged with engagement grooves  223  of rotation restricting portions  222  of the vial  220 , whereby the cap  210  is locked to the vial  220 . The inner cap  211  is equipped with a tension protrusion  214 ; when the cap  210  is locked to the vial  220 , the tension protrusion  214  comes into contact with the inner surface of the cap  210  to raise the cap  210 , acting thereon so as to maintain the engagement of the engagement portions  213  and the engagement grooves  223 . A moisture-proof ring  215  provided on the inner cover  211  of the vial comes into contact with the inner wall of the vial  220 . Since it is equipped with an escape portion  216 , the moisture-proof ring  215  reliably comes into contact with the inner periphery of the vial  220 , so the tablets absorb no moisture and their quality is maintained. When the cap  210  is pressed against the vial  220 , the tension protrusion  214  is crushed, and the engagement portions  213  are detached from the engagement grooves  223  of the rotation restricting portions  222 . When, in this state, the cap  210  is turned counterclockwise, the cap  210  can be opened. 
   The cap  210  and the vial  220 , which are constructed as described above, involve a rather bothersome operation. As a result, in recent years, a combination of a vial  1  and a cap  2  as shown in  FIG. 19  has come to be sold and put into use. The vial  1  has a structure for preventing an infant from accidental swallowing. The vial  1  has a vial outer periphery thread  4  on the outer peripheral surface of a vial opening  3 , and an inner periphery thread  5  on the inner peripheral surface thereof. The cap  2  has a cap inner periphery thread  6  on the inner peripheral surface thereof which is to be threadedly engaged with the vial outer periphery thread  4  of the vial  1 . Further, in order to be capable of being threadedly engaged also with the vial inner periphery thread  5  provided at the opening  3  of the vial  1 , the cap  2  has a small diameter portion  8  whose diameter is smaller than that of a large diameter portion  7  on which the cap inner periphery thread  6  is provided, with a cap outer periphery thread  9  being provided on the outer peripheral surface thereof. 
   The vial  1  has a disc-like flange  10  which is partially cut-away so that it may substantially come into contact with the lower edge of the cap  2  when the cap inner periphery thread  6  of the cap  2  is threadedly engaged with the vial outer periphery thread  4 . Further, the vial  1  has, in the cut-away portion of the flange  10 , a lever  11  whose distal end can be pushed down, with the lever  11  being equipped with a rotation restricting member  12  formed of an elastic latch member protruding obliquely upwards. Further, the cap  2  has a protrusion-like engagement portion  13  at the lower end of the inner surface thereof; when the inner periphery thread  6  of the cap  2  is threadedly engaged with the vial outer periphery thread  4  of the vial  1 , the engagement portion  13  climbs over the rotation restricting member  12  while pushing it down and, afterwards, the rotation restricting member  12  protrudes upwardly again due to its elasticity. Even if an attempt is made to turn the cap  2  in the opening direction, the engagement portion  13  abuts the rotation restricting member  12  to restrict the rotation of the cap  2 . Thus, in order to detach the cap  2  from the vial  1 , it is necessary to turn the cap  2 , with the lever  11  being pushed down to downwardly retract the rotation restricting member  12  below the engagement portion  13 . Since an infant is incapable of performing such an operation, it is possible to prevent accidental swallowing. Further, when there is no fear of an infant touching the vial  1 , the cap  2  is turned upside down, and the outer periphery thread  9  of the cap  2  is threadedly engaged with the vial inner periphery thread  5  of the vial  1 . As a result, the rotation restricting member  12  is not engaged with the engagement member  13 , and the cap can close the vial so as to easily allow its detachment, so the user feels no bother. 
   In conventional vial capping devices, it is necessary to rotate one of a mechanism for holding the vial and the other mechanism for holding the cap to lock or threadedly engage the cap to or with the vial, resulting in a rather complicated device structure. Further, in some cases, the holding of the cap is rather insufficient, and the cap spins, resulting in a rather insufficient tightening of the cap. In particular, in the case of a capping device for threadedly engaging the cap  2  with the vial  1  shown in  FIG. 19 , it is necessary to hold the cap  2 , which is of a complicated configuration due to the provision of the small diameter portion  8  equipped with the cap outer periphery thread  9 , resulting in problems such as a rather complicated device structure, a poor reliability in holding, and defective tightening due to spinning of the cap. 
   DISCLOSURE OF THE INVENTION 
   Problem to be Solved by the Invention 
   In view of the above-mentioned problems in the prior art, it is an object of the present invention to provide a vial capping device and a vial capping method allowing the cap to be reliably fastened to the vial with a simple construction. 
   Means for Solving the Problem 
   To solve the above-mentioned problems, a vial capping device according to the present invention relates to a vial capping device, in which a thread is provided respectively on an inner peripheral surface and an outer peripheral surface of a cap, a thread being provided on an outer peripheral surface of a vial opening, the cap being equipped with an engagement portion, the vial being equipped with a rotation restricting portion, the vial being closed by threadedly engaging the thread of the inner peripheral surface of the cap with the vial opening, rotation of the cap being locked through engagement of the engagement portion of the cap and the rotation restricting portion of the vial, the vial capping device including: a cap installation ring equipped with an inner periphery thread to be threadedly engaged with the thread of the outer peripheral surface of the cap; a holding device for holding the vial; a movement device for bringing at least one of the thread of the inner peripheral surface of the cap attached to the cap installation ring and the opening of the vial close to the other; and a tightening motor for rotating at least one of the cap and the vial. 
   Further, a plurality of cap installation rings may be provided, and a plurality of kinds of diameter sizes of the cap installation rings may be provided in correspondence with the kinds of diameters of vials. 
   Further, when a torque limiter is provided somewhere between the tightening motor for rotating at least one of the cap and the vial and the cap or the vial, it is possible to prevent damage of the motor. 
   Further, when there are provided below the cap installation ring a cap supply portion to which the cap is supplied so as to be substantially coaxial with the cap installation ring and an approach device for moving at least one of the cap supplied to the cap supply portion and the cap installation ring so as to bring them close to each other, it is possible to automatically attach the cap to the cap installation ring. 
   Further, when there is provided an installation motor which rotates at least one of the cap and the cap installation ring to threadedly engage the cap installation ring with the cap supplied to the cap supply portion, it is possible to attach the cap supplied to the cap supply portion through threaded engagement by rotating the installation motor. 
   Further, when there is provided a torque limiter in the rotation transmission route from the installation motor to the cap or the cap installation ring, it is possible to attach the cap to the cap installation ring with an appropriate torque, thereby preventing damage of the motor. 
   Further, when there is provided a retraction mechanism which causes the cap supply portion to retract from between the threadedly engaged cap and the vial opening after the cap supplied to the cap supply portion and the cap installation ring have been threadedly engaged with each other, it is possible to close (cap) the vial immediately after the cap supplied is threadedly engaged with the cap installation ring. 
   When there are provided a chute for supplying a stored cap to the cap supply portion, and a stopper for stopping the cap between the cap supply portion and the chute, and when the stopper is detached to supply a cap if there is no cap at the cap supply portion, it is possible to perform vial capping reliably one by one. 
   Further, according to the present invention, there is provided a vial capping method for a vial capping device in which a thread is provided on each of an inner peripheral surface and an outer peripheral surface of a cap, a thread being provided on an outer peripheral surface of a vial opening, the cap being equipped with an engagement portion, the vial being equipped with a rotation restricting portion, the vial being closed by threadedly engaging the thread of the inner peripheral surface of the cap with the vial opening, rotation of the cap being locked through engagement of the engagement portion of the cap and the rotation restricting portion of the vial, by which cap tightening can be reliably effected by the following procedures: 
   a) a procedure to threadedly engage the thread provided in the inner periphery of a cap installation ring and an outer periphery thread of the cap; 
   b) a procedure to bring the thread of the outer peripheral surface of the vial opening close to the thread portion of the cap inner peripheral surface; and 
   c) a procedure to rotate the cap installation ring in the closing direction by a motor. 
   Further, in the above-mentioned procedure a), when the cap installation ring is rotated until the cap engagement portion and the rotation restricting portion of the vial are engaged with each other to lock the cap, it is possible to exert a function by which accidental swallowing by an infant is prevented. 
   Further, when, after the cap has been locked, it is possible to successively perform capping on the next vial by performing the following procedure: 
   d) a procedure to rotate the cap installation ring in the reverse direction to cancel the threaded engagement of the thread of the cap installation ring and the outer periphery thread of the cap. 
   Further, it is possible to automatically attach the cap to the cap installation ring by performing the following procedures: 
   e) a procedure to mount the cap to a cap supply portion provided under the cap installation ring so as to be coaxial with the cap installation ring; 
   f) a procedure to bring the cap installation ring close to the cap supply portion; and 
   g) a procedure to rotate at least one of the cap mounted to the cap supply portion and the cap installation ring to threadedly engage the cap and the cap installation ring with each other. 
   Effects of the Invention 
   According to the vial capping device of the present invention, the cap outer periphery thread of the cap is threadedly engaged with the ring inner periphery thread of the cap installation ring, so it is possible to reliably hold the cap. Further, when engaging the cap threadedly engaged with the cap installation ring threadedly with the outer periphery thread of the vial, the torque of the cap or of the cap installation ring is exerted so as to threadedly engage the cap with the cap installation ring, so the cap holding state is stabilized, and it is possible to perform capping on the vial reliably with a simple configuration. 
   Further, in the vial capping device of the present invention, when a plurality of cap installation rings are provided, it is possible to perform capping on vials of different diameters, and when a torque limiter is provided, there is no fear of excessively tightening the cap to damage the cap or burning the motor. 
   As described above, according to the present invention, it is possible to provide a vial capping device and a vial capping method allowing a cap to be fastened to a vial reliably with a simple configuration. 

   BEST MODE FOR CARRYING OUT THE INVENTION 
   In the following, an embodiment of the present invention will be described with reference to the drawings. 
     FIGS. 1 and 2  show a tablet filling device  21  that is equipped with a vial capping device according to the present invention. The tablet filling device  21  is composed of three vial accommodating portions  22 , a cassette accommodating portion  23 , a cap accommodating portion  24 , vial discharge portions  25 , and a PC accommodating portion  26 . 
   Each vial accommodating portion  22  has a door  27  on one side thereof as shown in the drawing, which door is opened to accommodate vials  1 . The vials  1  accommodated in the vial accommodating portions  22  are extracted one by one and are conveyed to a robot arm (not shown). 
   The cassette accommodating portion  23  is provided on either side of the tablet filling device  21 ; a robot arm (not shown) directly moves the vial  1  to the back surface of the target tablet cassette, and imparts dispensing power to the drug cassette from the back side of the tablet cassette to introduce the requisite number of tablets into the vial  1 . The vial  1  filled with tablets is conveyed to a capping device described below by means of the robot arm. 
   The cap accommodating portion  24  is equipped with a cap supply unit  100  described below, and conveys caps  2  one by one to the capping device with their orientations aligned. The replenishment of the cap accommodating portion  24  with caps  2  is effected through a door  28 . 
   The vial discharge portions  25  are windows through which the vials  1  completely filled with tablets are discharged while classified into different groups for different patients. 
   The PC accommodating portion  26  accommodates a PC, which is connected to a pharmacy host computer through a LAN; it transmits prescription data that is received from the pharmacy host computer to a main body control portion, and displays operational information of the corresponding data through an operation monitor  29 . 
   The capping device is composed of a cap installation unit  31  and a robot arm  71 .  FIGS. 3 ,  4 , and  5  show the cap installation unit  31 . The caps  2  slide on a chute  32  by their own weight to a cap supply portion  33  in a state in which they are aligned with the openings of inner peripheral threads  6  provided on the caps  2  facing downwardly. The cap supply portion  33  is composed of a pair of L-shaped guides  34  opposed to each other and arranged substantially parallel to the direction in which the caps  2  are supplied. 
   Above the cap supply portion  33 , there is provided a cap installation ring  35  at a position where it is substantially coaxial with the cap  2  supplied to the cap supply portion  33 . One end portion of a support shaft  36  is inserted into a hole that is provided in the cap installation ring  35 , and the cap installation ring  35  is rotatable around the support shaft  36  and axially slidable along the support shaft  36 . The other end of the support shaft  36  is supported by a motor bracket  37 . Substantially in the middle of the support shaft  36 , there is provided a drive gear  39  that is supported by a bearing  38 . Since an E-ring is attached to the cap installation ring  35  side of the drive gear  39 , the drive gear  39  does not fall from the support shaft  36 . The drive gear  39  is driven by being in mesh with a motor gear  40 . The motor gear  40  is driven by a rotation motor (which serves as both tightening motor and installation motor)  42  via a speed reduction gear  41  and a torque limiter  41   a . The cap installation ring  35  is suspended from the drive gear  39  by a pair of ring support shafts  43  that are situated on both sides of the support shaft  36 . The ring support shafts  43  slidably extend through holes provided in the drive gear  39 ; their upper ends are larger than the holes of the drive gear  39 , and their lower ends are fixed to the upper surface of the cap installation ring  35  by screws. Further, a compression spring  44  is provided around the portion of the support shaft  36  which is between the cap installation ring  35  and the bearing  38  provided on the drive gear  39 , pressing the cap installation ring  35  downwardly. The cap installation unit  31  including the motor bracket  37  form a structure that is capable of ascending and descending, so they are mounted to a bracket  46  capable of ascending and descending along an ascent/descent slide shaft  45 , and the bracket  46  is caused to ascend and descend by a screw of an ascent/descent drive shaft  47  (approach device). The ascent/descent drive shaft  47  is equipped with a bevel gear  48 ; a bevel gear  49  of a motor  50  is in mesh with the above-mentioned bevel gear  48 , and the ascent/descent drive shaft  47  rotates through driving of the motor  50 , causing the bracket  46  to ascend and descend. Both end portions of the ascent/descent drive shaft  47  are rotatably supported by bearings, and the bearings and the ascent/descent slide shaft  45  are mounted to a structure  51 , whereby the cap installation unit  31  as a whole is supported. 
   A protrusion  52  for position detection is provided on the bracket  46 , and the structure  51  is equipped with a position detecting sensor  53  for detecting a protrusion  62  at an upper limit position and a lower limit position of the bracket  46 . The position detecting sensor  53  is a transmitted-light detecting sensor; when the protrusion  52  reaches a gap portion of the main body of the sensor  53 , light is intercepted, whereby the position of the bracket  46  is detected. The upper limit position is of a height not hindering the charging of the cap  2  to the cap supply portion  33 , and the lower limit position is of a height allowing the thread portions  4 ,  6  of the cap  2  and the vial  1  to come into contact with each other when they are to be threadedly engaged with each other. 
   Further, in the present invention, the drive gears  39  are provided on each side of the motor gear  40  being centered, and the cap installation rings  35  of different diameters are provided on the drive gears  39  so as to be in conformity with the kinds of vial  1  to be treated by the cap installation unit  31 . The structures on both sides, however, are as described above except that they differ from each other in diameter. 
   Further, a solenoid  54  is provided above the cap supply portion  33  and on the front side thereof with respect to the cap supply direction, and the plunger of the solenoid  54  is connected to a lever  55   a , and a stopper  55  is mounted to the forward end of the lever  55   a . In order that the next cap  2  that is on standby on the chute  32  may not move to the cap supply portion  33  at the time of cap installation to hinder the cap tightening, the stopper  55  abuts the upper portion of the next cap  2  to cause it to stop at that position. The chute  32  is equipped with a sensor  32   a , which detects whether there are any cap  2  at the cap supply portion  33 . When there is no more cap  2  at the cap supply portion  33 , an electric current flows through the solenoid  54 , and the stopper  55  ascends, canceling the abutment of the cap  2  and causing the cap  2  to move to the cap supply portion  33 . 
     FIG. 6  is a perspective view, as viewed from below, of the vial  1 , the cap  2 , and the cap installation ring  35 . An installation ring inner periphery thread  56  is provided in the inner periphery of the cap installation ring  35 . The installation ring inner periphery thread  56  is to be threadedly engaged with a cap outer periphery thread  9  provided on a small diameter portion  8  of the cap  2  which is of a smaller diameter than a large diameter portion  7  thereof. 
     FIGS. 7A and 7B  show the construction of L-shaped guides  34  (retraction mechanism) on which the cap  2  is mounted. The L-shaped guides  34  are rotatable around guide rotation shafts  57 , and are equipped with transmission gears  58  for equalizing the rotation angles of the opposing L-shaped guides. Further, springs  59  are stretched between the opposing L-shaped guides  34 , urging them toward each other, with the parallel position being the limit. A transmitting protrusion  60  is provided on one of each pair of L-shaped guides  34 , and, a slide transmission rail  61  is provided under the same; at one end of the slide transmission rail  61 , there is provided a bearing  62  in contact with the transmitting protrusions  60 ; the other end thereof is coupled to an arm  64  connected to a solenoid  63 . 
   The slide transmission rail  61  is mounted so as to extend through a structure support plate  51 , and is provided so as to be longitudinally slidable along a guide (not shown). Substantially at the center of the slide transmission rail  61 , there is provided an elongated hole  66  engaged with a position regulating bearing  65  supported by the structure support plate  51 . When no power is being supplied to the solenoid  63 , the position regulating bearing  65  is in contact with the arm  64  side of the elongated hole  66  a shown in  FIG. 7A . When power is supplied, the position regulating bearing  65  comes into contact with the L-shaped guide  34  side of the elongated hole  66  as shown in  FIG. 7B . The L-shaped guides  34  are adjusted so as to be substantially parallel when the position regulating bearing  65  is in contact with the arm  64  side of the elongated hole  66 . Above each pair of L-shaped guides  34 , there is provided a stopper  33   b  at the forward ends of a pair of support arms  33   a  extending from the structure support member  51 . The cap  2 , which comes sliding from the chute  32 , abuts the stopper  33   b , and is correctly stopped at the cap supply portion  33 . 
     FIG. 8  is a perspective view of the robot arm (which serves both as a holding device and a movement device)  71  provided under the cap installation unit  31 . The robot arm  71  serves to perform cap tightening on the vial  1  that has completed filling, and to convey the vial  1  to the vial discharge portion  6  shown in  FIG. 1 . In the robot arm  71 , rail members  73  are provided upright at both longitudinal ends of a unit casing portion  72 , with the robot arm ascending and descending along the rail members  73 . The drive source for the ascent and descent is provided as follows: shafts (not shown) that are substantially parallel to the unit casing portion  72  are provided at the upper and lower ends of the ascent/descent range, and two timing belts (not shown) are stretched between pulleys (not shown) provided on the shafts, with one side of each timing belt being fixed to the unit casing portion  72 ; the drive source is provided by running these timing belts. Sensors (not shown) are provided at the upper and lower ends of the ascent/descent range, preventing overrunning of the robot arm beyond the ascent/descent range. 
   On the unit casing portion  72 , there is provided a horizontal rotation gear  74  horizontally rotatable around a rotation shaft (not shown). The horizontal rotation gear  74  is engaged with a horizontal rotation drive gear  75 ; when a horizontal rotation drive motor  76  rotates, the horizontal rotation gear  74  is rotated via the horizontal rotation drive gear  75  owing to a drive force thereof. Further, the horizontal rotation gear  74  has an encoder (not shown) on its rotation shaft, and an origin protrusion  74   a  on the back surface thereof; the rotating position where a sensor (not shown) provided in the unit casing portion  72  detects the origin protrusion is used as the origin. By using the encoder, it is possible to control the stop position, etc. according to the number of slits and blinds as counted from the origin. Further, on the planar rotation gear  74 , there is provided a slide rail support plate  77 , and a slide rail (not shown) is provided between the slide rail support plate  77  and an arm unit support plate  78 . Further, on the slide rail support plate  77 , there is arranged a rack gear  79  so as to be substantially parallel to the slide rail; the slide rail is expanded and contracted by an expansion/contraction gear  80  in mesh with the rack gear  79 , and an expansion/contraction drive motor  81  supported on the arm unit support plate  78  side, causing the slide rail support plate  78  to move. Further, the robot arm  71  is equipped with a sensor  82  for detecting the slide limit. 
     FIG. 9  is a plan view of the robot arm  71 . A pair of arm members  83  are supported by the arm unit support plate  78  so as to open and close around an arm shaft  84 , and a grasping drive shaft  85  is provided so as to extend through the central portion of the arm members  83 , and both ends thereof are supported on the arm unit support plate  78  by means of bearings. 
     FIG. 10  is a perspective view, as viewed from the front side, of the robot arm  71 . The grasping drive shaft  85  has on the right-hand and left-hand sides of substantially the center thereof a left-handed screw and a right-handed screw, respectively. When the grasping drive shaft  85  rotates in one direction, the pair of arm members  83  move toward or away from each other. At the portions where it crosses the arm members  83 , the grasping drive shaft  85  is threadedly engaged with nuts  86  as the left-handed screw and the right-handed screw. As shown in  FIG. 9(B) , each nut  86  has an attitude correction shaft  87 , the upper end of which is rotatably supported by the corresponding arm member  83 . As a result, regardless of the open/closed state of the arm members  83 , the nuts  86  are matched with the axial direction of the left-handed screw and the right-handed screw of the drive shaft  85 . At the one end of the grasping drive shaft  85 , there is provided a grasping drive pulley  88 , which is connected to a grasping motor pulley  90  by a drive belt  89 . The grasping drive pulley  90  is driven by a grasping drive motor  91 . In order that it may not move in the lateral direction but move in the expanding/contracting direction during the opening/closing operation, the arm shaft  84  is mounted to the arm unit support plate  78  by means of an elongated hole  92  extending in the expanding/contracting direction. As a result, when the pair of arm members  83  move toward and away from each other, the right and left attitude correction shafts  87  make relative rotation with respect to the arm members  83 , and, while the arm shaft  84  moves its axis in the expanding/contracting direction, grasping members  93  mounted to the forward ends of the arm members  83  grasp or release the vial  1 . 
   Further, an auxiliary guide pin  94  is provided substantially parallel to the grasping shaft  85 . This guide pin performs auxiliary guide so that the arm members  83  may not be vertically inclined around the arm shaft  84  portion. The range of the vertical inclination can be adjusted by an E-ring fixed to the elongated hole  92  in the expanding/contracting direction. At the forward ends of the arm members  83 , there are supported grasping members  93  so as to be rotatable around rotation shafts  95 , and are urged by arm urging springs  96  such that the forward ends of the grasping members  93  are urged toward each other. When no vial  1  is being grasped, the rear ends of the grasping members  93  are in contact with the wall surfaces of the arm members  83 . When the vial  1  is grasped, the rear ends of the grasping members  93  are separated from the surface portions of the arm support portions, and can hold the vial  1  by virtue of the urging force of the arm urging springs  96 . 
   In the robot arm  71 , the nuts  86  of the left-handed screw and the right-handed screw provided on the grasping drive shaft  85  are supported by the right and left attitude correction shafts  87 , and are constructed to be supported by the arm shaft  84 , so the robot arm  71  can be produced at lower cost than the slide unit. Further, in the support by the arm shaft  84  alone, grasping operation is effected along the arc during the grasping operation of the grasping members  93 . However, the grasping members  93  support the nuts  86  of the left-handed screw and the right-handed screw provided on the grasping drive shaft  85  by the right and left attitude correction shafts  87 . As a result, the arm  84  moves along the elongated hole  92  extending in the expanding/contracting direction, and the grasping embers  93  move to the right and left substantially linearly. 
     FIG. 11  shows a front outward view of the cap supply unit  100 . In the cap supply unit  100 , a large cap supply unit  100   a  and a small cap supply unit  100   b  are arranged horizontally adjacent to each other. A large cap introduction duct  101  is mounted to the left-hand side as shown in the drawing of the large cap supply unit  100   a . The large cap introduction duct  101  extends to a front side from an introduction port  101   a  formed in the left-hand wall of the large cap supply unit  100   a , and a front opening  101   b  thereof is opposed to the door  28 . A small cap introduction duct  102  is mounted to the front side of the small cap supply unit  100   b . The small cap introduction duct  102  is formed integrally with a cover  103  of the small cap supply unit  100   b , and extends to the left from an introduction port  102  a formed in the cover  103 . The small cap further extends to the front side from the left-hand side of the large cap supply unit  100   a  beyond the front side of the large cap supply unit  100   a , with an opening  102   b  of the front side thereof being opposed to the door  28 .  FIG. 12  shows a state where the small cap installation duct  102  is removed. The large cap supply unit  100   a  and the small cap supply unit  100   b  are of the same construction except for the cap introduction ducts  101 ,  102 . Therefore, in the following, a description will be given without distinguishing them from each other. 
     FIG. 13  shows a side view of the cap supply unit  100 . The cap supply unit  100  is composed of a cap accommodating portion  104 , a discharge unit  105 , and an agitation unit  106 . 
   The accommodating portion  104  is a rectangular box-shaped container accommodating at random a large number of caps charged through the cap introduction duct  101 ,  102 . 
   The discharge unit  105  has an endless belt  108  stretched between two rollers  107   a ,  107   b  from the rear side wall to the bottom wall of the accommodating portion  104 , with support members  109  being provided at fixed intervals in the endless belt  108 . The endless belt  108  is composed of a vertical portion  108   a  and an inclined portion  108   b  extending obliquely downwards from the lower end of the vertical portion  108   a . Between the vertical portion  108   a  and the inclined portion  108   b  of the endless belt  108 , a tension roller  110  is held in contact with the back side of the endless belt from the inside. By driving the upper roller  108   a  by a motor  111  via gears  111   a ,  112 , the front side of the endless belt  108  ascends obliquely upwards from the lower end, and further ascends in the vertical direction to be turned back at the upper end. As shown in  FIG. 14 , the support members  109  protrude from the endless belt in a dimension somewhat larger than the thickness of the cap  2 , and a cutout  109   a  is formed at the center of each support member so that the cap  2  may be supported in a stable manner. As shown in the upper portion of  FIG. 15 , when the opening of the cap  2  is directed to the side opposite to the endless belt  108 , the cap  2  can be supported by the support members  109  in a stable manner, while, as shown in the lower portion of  FIG. 15 , when the opening of the cap  2  is opposed to the endless belt  108 , the cap is detached from the support member  109 . This is because the center of gravity of the vertically set cap  2  is not at the center of the thickness of the cap  2  but on the side opposite to the opening, that is, on the closed side. 
   In the vicinity of the upper end of the endless belt of the discharge unit  105 , there are provided a detection lever which operates when the cap  2  supported by the support member  109  is turned back, and a sensor  114  which is turned on and off according to the operation of the detection lever  113 . 
   Behind the discharge unit  105 , there is formed a discharge path  115  so as to be parallel to the vertical portion  108   a  of the endless belt  108 . The discharge path  115  receives the cap  2  having been conveyed by the discharge unit  105  to reach the turn-back portion at the upper end, and guides it downwards. At the upper end of the discharge path  115 , there is provided a guide plate  116  for guiding the cap  2  to the discharge path  115 . 
   The agitation unit  106  has an agitation plate  118  provided so as to be capable of vertically reciprocating along the inner side wall of the accommodating portion  104  by means of a plurality of guides  117 . In the lower portion of the agitation plate  118 , a plurality of lock holes  118   a  to which the caps  2  accommodated in the accommodating portion  104  are locked and which extend in the horizontal direction are formed at fixed intervals in the vertical direction. Instead of forming the lock holes  118   a  of the agitation plate  118  as holes, it is also possible to form them as protrusions. The lock holes  118   a  are preferable in that they do not decrease the capacity of the accommodating portion  104 . In the side edge of the upper portion of the agitation plate  118 , there is formed a cutout  118   b ; a roller  121  at the forward end of a cam  120  provided integrally with a gear  119  in mesh with the drive gear  111   a  of the motor  111  of the discharge unit  105  abuts the upper side edge of the cutout  118   b . As a result, the agitation plate is interlocked with the endless belt  108  of the discharge unit  105  and periodically reciprocates in the vertical direction. 
   Next, the operation of the vial capping device will be described. 
     FIGS. 16A through 16F  show side views of the cap installation unit  31  and the robot arm  71 , illustrating the operation of the robot arm  71 . The robot arm  71  moves the vial  1  from the delivery position to the cap installation unit  31 . After the cap installation unit  31  tightens the cap  2 , the robot arm  71  further moves the vial  1  to the vial discharge portion  6 . 
     FIG. 16A  shows the state in which the robot arm  71  is at the vial delivery position, with the robot arm  71  reaching a position near the slide limit through expansion of the slide rail. For enabling to adjust this position, a pulse motor may be adopted as the expansion/contraction drive motor  81 , effecting feedback by an encoder or effecting stop by a position detecting sensor. When the position of the grasping members  93  at the forward end of the arm is matched with vial delivery position, the grasping drive motor  91  is driven. Then, the grasping drive pulley  90  rotates and force generated therefrom is transmitted through the drive belt  89  to rotate the grasping drive pulley  88 , and this rotation causes the grasping drive shaft  85  supported by a bearing to rotate. When the grasping drive shaft  85  rotates, the right and left screws rotate, and the two nuts  86  threadedly engaged with the left-handed screw and the right-handed screw are brought close to each other. As a result, the pair of arm members  83  are brought close to each other, and the grasping members  93  at the forward end grasps the vial  1 . Programming is effected such that, at this time, when the operation of the drive motor  91  is continued while the urging force and the repulsive force of the arm urging springs  96  are balanced, the electric current value increases upon reception of the repulsive force of the arm urging springs  96 , the operation being stopped when a preset electric current value is exceeded. This means that, even if vials  1  of different diameters are used together, it is possible to grasp the vials with a fixed grasping force. That is, there is advantage of no need to set the control and the detecting portion in conformity with the kind of vial  1 . 
   When the robot arm  71  grasps the vial  1 , a robot arm ascent/descent motor (not shown) is driven to raise the robot arm along the rail members  73 . Subsequently, the expansion/contraction drive motor  81  is rotated to contract the arm unit support plate  78  along the slide rail. In the example shown in the drawing, the vial  1  being grasped is of a large diameter, so the expansion contraction motor  81  is stopped when the vial reaches the cap supply portion  33  directly below the cap installation ring  35  of the cap installation unit  31 , which maches the large diameter caps  2 . The robot arm ascent/descent motor (not shown) is stopped when the standby position shown in  FIG. 16B  is reached, and cap tightening will be started. 
     FIG. 16B  shows a process in which the motor bracket  37  is lowered by the screw of the ascent/descent drive shaft  47  to lower the cap installation unit  31  while rotating the cap rotating motor  42 . While the cap installation ring  35  rotates, the cap  2  prepared at the cap supply portion  33  stops due to the frictional force between it and the L-shaped guides  34  under the depression pressure of the cap installation ring  35 , and the ring inner periphery thread  56  of the cap installation ring  35  is threadedly engaged with the cap outer periphery thread  9  of the cap  2 . 
   When the cap installation ring  35  is lowered to a predetermined height, the cap  2  is completely threadedly engaged with the cap installation ring  35  as shown in  FIG. 16C , and here, the cap setting torque limiter  41   a  operates. In this stage, the L-shaped guides  34  are opened as shown in  FIG. 7B , and the robot arm  71  is raised from the standby position to the closing position. The cap  2  threadedly engaged with the cap installation ring  35  rotates together with the cap installation ring  35 , and the cap inner periphery thread  6  of the cap  2  is threadedly engaged with the vial outer periphery thread  4  of the vial  1 . Here, the torque limiter  41   a  operates to prevent excessive tightening of the cap  2 . When the cap inner periphery thread  6  of the cap  2  threadedly engaged with the cap installation ring  35  is threadedly engaged with the outer periphery thread  4  of the vial, the torque of the cap  2  is exerted such that the cap  2  is threadedly engaged with the cap installation ring  35 , so the holding of the cap  2  by the cap installation ring  35  is stabilized, making it possible to effect capping reliably with a simple construction. 
   While in the example described above the robot arm  71  is raised to the closing position, it is also possible to further lower the cap installation unit  31  with the robot arm  71  remaining stationary at the standby position and capping the vial, or to bring both units close to each other. 
   When the cap  2  is completely tightened, the operation stops in the state as shown in  FIG. 16D . The cap rotating motor  42  is rotated for a fixed period of time, and when a period of time long enough to attain the closed state elapses, the cap rotating motor  42  is rotated in the reverse direction, and the cap installation unit  31  is raised to restore it to the origin as shown in  FIG. 16E . At this time, the engagement portion  13  of the cap  2  is engaged with the rotation restricting portion  12  of the vial  1  to prevent rotation of the cap  2 , so the threaded engagement of the cap installation ring  35  and the cap  2  is canceled, and the cap  2  is attached to the vial  1 . Next, the L-shaped guides  34  are closed, and the robot arm  71  is lowered to the movement position as shown in  FIG. 16F , with the capped vial  1  being conveyed to the corresponding one of the vial discharge portions  6  shown in  FIG. 1 . 
   A remarkable feature of the present invention is that, before attaching the cap  2  to the vial  1 , the cap  2  is firmly held through threaded engagement of the cap outer periphery thread  9  of the cap  2  and the ring inner periphery thread  56  of the cap installation ring  35 . While in the above embodiment the cap installation unit  31  is lowered onto the cap  2  on the L-shaped guides  34 , it is also possible to provide the L-shaped guides  34  with an ascent/descent means and to press the cap  2  against the cap installation ring  35 , or to move both to attach the cap  2  to the cap installation ring  35 . Further, while in the above embodiment the cap  2  is rotated when attaching the cap  2  to the vial  1 , it is also possible to rotate the vial  1 , or to rotate both the vial  1  and the cap  2 . 
   BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1  is a perspective view of a tablet filling device equipped with a vial capping device according to the present invention. 
     FIG. 2  is a front elevation view of the vial capping device of  FIG. 1 . 
     FIG. 3  is a perspective view of the cap installation unit of the vial capping device of the present invention. 
     FIG. 4  is a front view of the cap installation unit of  FIG. 3 . 
     FIG. 5  is a side view of the cap installation unit of  FIG. 3 . 
     FIG. 6  is a perspective view showing the relationship between the cap installation ring of the cap installation unit and the cap and the vial of  FIG. 3 . 
     FIG. 7A  is a plan view of the L-shaped guides of the cap installation unit of  FIG. 3  in the closed state. 
     FIG. 7B  is a plan view of the L-shaped guides of  FIG. 7A  in the open state. 
     FIG. 8  is a perspective view of the robot arm of the vial capping device of the present invention. 
     FIG. 9A  is a plan view of the robot arm of  FIG. 8 . 
     FIG. 9B  is a partial enlarged view of the robot arm of  FIG. 9A . 
     FIG. 10  is a perspective view, as taken in a different direction of the robot arm of  FIG. 8 . 
     FIG. 11  is a front view of the cap supply unit. 
     FIG. 12  is a front view of the cap supply unit with the small cap introduction duct removed therefrom. 
     FIG. 13  is a sectional view of the cap supply unit. 
     FIG. 14  is a perspective view of a support member of an endless belt. 
     FIG. 15  is a side view showing how caps are supported by support members of the endless belt. 
     FIG. 16A  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  prior to capping start. 
     FIG. 16B  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  at the time of capping start. 
     FIG. 16C  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  at the stage next to that of  FIG. 16B . 
     FIG. 16D  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  at the stage next to that of  FIG. 16C . 
     FIG. 16E  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  at the time of the completion of capping. 
     FIG. 16F  is a side view showing the positional relationship between the cap installation unit of  FIG. 3  and the robot arm of  FIG. 8  after the completion of capping. 
     FIG. 17  is a perspective view of a conventional vial and a cap. 
     FIG. 18A  is a side view of the conventional vial and the cap. 
     FIG. 18B  is a sectional view of the conventional vial and the cap. 
     FIG. 19  is a perspective view of a vial and a cap recently in use. 
   DESCRIPTION OF REFERENCE NUMERALS 
     1 : vial 
     2 : cap 
     31 : cap installation unit 
     33 : cap supply portion 
     34 : L-shaped guide 
     35 : cap installation ring 
     42 : rotating motor (as both tightening motor and installation motor) 
     56 : ring inner periphery thread 
     71 : robot arm (as both holding device and movement device)