Patent Publication Number: US-7221446-B2

Title: Fluid dispenser and lens inspection device

Description:
This is a divisional of application Ser. No. 10/420,898 filed Apr. 23, 2003 now U.S. Pat. No. 7,027,144 which is a divisional of application Ser. No. 09/845,164 filed May 1, 2001 now U.S. Pat. No. 6,575,338. The entire disclosure of the prior application Ser. No. 10/420,898 is considered part of the disclosure of the accompanying divisional application and is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a fluid dispenser that dispenses liquid or fluid from a container, called a syringe, by rising internal pressure of the syringe by a piston. More particularly, the present invention relates to a fluid dispenser for a lubricant containing solid materials, especially for a lubricant sprayed on a reused shutter mechanism before inspecting the shutter speed. The present invention relates also to a lens inspection system, especially for use in recycling reused lenses. 
     2. Background Arts 
     An exemplar of a well-known dispenser is disclosed in Japanese Laid-open Patent Application No. 10-309456, that has a syringe partitioned by a piston into two chambers. By driving the piston to reciprocate inside the syringe, a liquid contained in the syringe is dispensed alternately from both chambers. While the liquid is being ejected from one of the chambers, the other chamber is being supplemented with the liquid. Thus, the dispenser of this type can dispense the liquid in continuous succession. Where the liquid to dispense is a lubricant that contains solid components, the lubricant must continually be mixed or agitated for keeping the liquid density constant, because the solid components would otherwise precipitate. For this reason, it is necessary to provide a mixing mechanism in the syringe in that case. 
     Japanese Laid-open Patent Application No. 10-146553 discloses an adhesive coating apparatus, wherein a mixing device is provided in a syringe for keeping the viscosity of a fluid adhesive material constant. The syringe has an ejection port on the bottom side. The fluid adhesive material is pushed by compressed air toward the ejection port, to be ejected from the ejection port. The mixing device is constituted of an agitating propeller mounted on one end of a drive shaft. The other end of the drive shaft protrudes outside the syringe through a top opening thereof, and is driven to rotate the propeller by an external driving force. 
     Introducing such a mixing device into the above mentioned dispenser involves a problem that the drive shaft would interfere with a piston rod. To avoid this problem, the drive shaft must be inserted into the syringe through a different position from where the piston rod is inserted. Then a complicated sealing device would be needed for closing a clearance between the drive shaft and the syringe, and thus increases the cost of the dispenser. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, an object of the present invention is to provide a fluid dispenser that can successively dispense a liquid while mixing the liquid continuously in a syringe, has a simple structure and may be manufactured at a low cost. 
     According to an aspect of the present invention, in a fluid dispenser having a syringe with ports on opposite ends thereof, a piston movable inside said syringe back and forth, and a supply tank being connectable alternately to one of said ports depending upon moving direction of said piston, said fluid dispenser dispensing a fluid from one of said ports that is located on the end of said syringe toward which said piston is moving, while sucking the fluid from said supply tank into said syringe through the other of said ports, the fluid dispenser is characterized by comprising: a pair of stirrers provided respectively in the chambers, the stirrers being rotatable on a rotary axis that extends parallel to the moving direction of the piston; and a pair of stirrer driving devices disposed on an outer periphery of the syringe in correspondence with the stirrers, for driving the stirrers to rotate each individually by a magnetic force. 
     Since the stirrers are rotated by the magnetic force, there is no problem about the interference of a drive shaft for the stirrer with a piston rod. 
     The stirrers have the same configuration, and have a plurality of magnets embedded therein symmetrically about the rotary axis of the stirrers, whereas the stirrer driving devices generate magnetic fields that cause the stirrers to rotate. At least one of the stirrers is continuously rotated on one side of the piston, into which the liquid is being sucked. 
     A piston rod that moves together with the piston extends from opposite end faces of the piston concentrically with the piston and the syringe, and the piston is moved by a piston driving device that is coupled to an end of the piston rod. According to a preferred embodiment, the stirrers are mounted on the piston rod so as to be able to rotate around and slide along the piston rod. In this embodiment, the stirrers are kept in the same axial positions in the syringe by the magnetic forces of the stirrer driving device, even while the piston rod is being moved back and forth together with the piston. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments when read in association with the accompanying drawings, which are given by way of illustration only and thus are not limiting the present invention. In the drawings, like reference numerals designate like or corresponding parts throughout the several views, and wherein: 
         FIG. 1  is a perspective view illustrating essential parts of a lubricant coating system provided with a fluid dispenser according to an embodiment of the present invention; 
         FIG. 2  is an explanatory diagram illustrating the lubricant coating system of  FIG. 1  in a position at the end of a forward movement of a piston; 
         FIG. 3  is an explanatory diagram illustrating the lubricant coating system of  FIG. 1  in a position at the start of dispensing operation by a backward movement of the piston; 
         FIG. 4  is a sectional perspective view of the fluid dispenser of  FIG. 1 ; 
         FIG. 5  is a sectional view of the fluid dispenser of  FIG. 1 ; 
         FIG. 6  is a perspective view of a stirrer provided in a syringe of the fluid dispenser; 
         FIG. 7  is a sectional perspective view of the stirrer; 
         FIG. 8  is a sectional view of the dispenser taken along a line VIII—VIII of  FIG. 5 ; 
         FIG. 9  is a flow chart illustrating an automatic operation sequence of the lubricant coating system; 
         FIG. 10  is a flow chart illustrating a sequence of a normal mode of the lubricant coating system; 
         FIG. 11  is a flow chart illustrating a piston turning operation of the lubricant coating system; 
         FIG. 12  is an explanatory diagram illustrating the lubricant coating system of  FIG. 1  in a drip prevention step of the piston turning operation; 
         FIG. 13  is an explanatory diagram illustrating the lubricant coating system of  FIG. 1  in a venting step of the piston turning operation; 
         FIG. 14  is a flow chart illustrating a sequence of a standby mode of the lubricant coating system; 
         FIG. 15  is a flow chart illustrating a sequence of a recovery operation from the standby mode to the normal mode; 
         FIG. 16  is a fragmentary sectional view of a stirrer and a stirrer driving device according to another embodiment of the present invention; 
         FIG. 17  is a block diagram illustrating a taking lens inspection system according to another embodiment of the present invention; 
         FIG. 18  is a perspective view of a scratch detector of the taking lens inspection system of  FIG. 17 ; 
         FIG. 19  is a perspective view of an extraneous object detector of the taking lens inspection system of  FIG. 18 ; 
         FIG. 20  is a schematic diagram illustrating the scratch detector of  FIG. 18 ; 
         FIG. 21  is an explanatory diagram illustrating optical paths of inspection light projected onto a lens having no scratch in the scratch detector of  FIG. 18 ; 
         FIG. 22  is an explanatory diagram illustrating optical paths of inspection light projected onto a lens having a scratch in the scratch detector of  FIG. 18 ; 
         FIG. 23  is an explanatory diagram illustrating a light area in a dark field image of the lens; 
         FIG. 24  is an explanatory sectional diagram illustrating the extraneous object detector of  FIG. 19 ; 
         FIG. 25  is an explanatory diagram illustrating optical paths of inspection light projected onto a lens having no scratch in the extraneous object detector of  FIG. 19 ; 
         FIG. 26  is an explanatory diagram illustrating optical paths of inspection light projected onto a lens having a scratch in the extraneous object detector of  FIG. 19 ; 
         FIG. 27  is an explanatory diagram illustrating unit sections of an inspection range of an imaging device of the extraneous object detector of  FIG. 19 ; 
         FIG. 28  is a flow chart illustrating an overall sequence of a taking lens inspection process included in a process of recycling taking lenses of lens-fitted photo film unit; and 
         FIG. 29  is an explanatory diagram illustrating another pattern of unit sections of the inspection range of the imaging device of the extraneous object detector. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In  FIG. 1 , a lubricant coating system  10  is constituted of a collection tank  11 , a four-way switching valve  12 , two-way switching valves  13  and  14 , a supply tank  15 , a dispenser  16 , a needle valve  17  and other minor elements. The dispenser  16  makes a dispensing operation to put a constant amount of lubricant on an object to coat  18  through the needle valve  17 . In this instance, the lubricant is highly volatile and contains solid components. 
     The object to coat  18  is placed in a predetermined posture on a pallet  19  and conveyed along a conveyer line  20 . In a coating station, the pallet  19  is positioned by a positioning device, and the dispenser  16  is activated upon receipt of an end-of-positioning signal from the positioning device, to make the dispensing operation. The needle valve  17  is disposed with its nozzle  17   a  directed to a coating portion of the object  18 . After the coating of the object  18  is finished, the positioning device releases the object upon receipt of an end-of-coating signal, so the coated object  18  is conveyed to the next process, and the object to coat  18  is moved in the coating process. 
     As shown in  FIG. 2 , the needle valve  17  is provided with a on-off valve  17   b  for opening and closing the nozzle  17   a.  The on-off valve  17   b  is actuated by compressed air that is supplied from a compressor  21 . The on-off valve  17   b  is usually set open. A cleaning mechanism  22  is disposed in the vicinity of the nozzle  17   a.  The cleaning mechanism  22  uses the compressed air from the compressor  21 , for blowing off the lubricant that is stuck to the nozzle  17   a.    
     Referring back to  FIG. 1 , the dispenser  16  is provided with a rod driving actuator  24 , a piston rod  25  and a syringe  26 , and controls the amount of movement of the piston rod  25  in one or another direction, to decide the amount of lubricant to be ejected through the needle valve  17 . The rod driving actuator  24  consists of a driving device, such as a pulse motor, and a converter that converts a rotary force of the driving device into reciprocation. 
     As shown in  FIG. 2 , a piston  42  is securely mounted on the piston rod  25 , and is moved back and forth inside the syringe  26 , when the piston rod  25  is driven by the rod driving actuator  24 . Thus, the rod driving actuator  24  may be called a piston driving device. The syringe  26  is provided with first to fourth ports  28 ,  29 ,  30  and  31  that connect the inside of the syringe  26  to the outside. The first and second ports  28  and  29  are located on one side of the piston  42 , whereas the third and fourth ports  30  and  31  are located on the other side of the piston  42 . The first and third ports  28  and  30  are located on the top side of the syringe  26 , whereas the second and fourth ports  29  and  31  are located on the bottom side of the syringe  26  in opposition to the first and third ports  28  and  30  respectively. 
     The first and third ports  28  and  30  are connected to the two-way switching valves  13  and  14  respectively through Teflon tubes. The two-way switching valves  13  and  14  are connected to the collection tank  11  through Teflon tubes, and are switched over between an open position and a closed position by means of switching actuators  33  and  34  respectively. In the closed position, the two-way switching valves  13  and  14  respectively disconnect the first and third ports  28  and  30  from the collection tank  11 . The collection tank  11  is a hermetic tank with a pressure regulation valve, and accepts air bubbles together with the lubricant when they are ejected from the syringe  26  for venting the air out of the syringe  26 . Thus, the first and third ports  28  and  30  may be called venting ports. 
     The second and fourth ports  29  and  31  are connected to the four-way switching valve  12  through Teflon tubes. To the four-way switching valve  12  are also connected the supply tank  15  and the needle valve  17  through Teflon tubes. The four-way switching valve  12  is switched over between a forth movement position as shown in  FIG. 2 , and a back movement position as shown in  FIG. 3 . While the piston rod  25  is being moved forward, the four-way switching valve  12  is switched to the forth movement position where the fourth port  31  is connected to the supply tank  15 , and the second port  29  is connected to the needle valve  17 . While the piston rod  25  is being moved backward, the four-way switching valve  12  is switched to the back movement position, and connects the second port  29  to the supply tank  15  and connects the fourth port  31  to the needle valve  17 . The four-way switching valve  12  is switched by driving a four-directional switching actuator  35 . 
     The supply tank  15  is a hermetic tank with a pressure regulation valve, and contains the lubricant. A mixing mechanism  38  is provided inside the supply tank  15 , for mixing the lubricant to keep the density of the lubricant constant. The mixing mechanism  38  for the supply tank  15  has a magnet stirrer structure. The above described mechanisms, actuators and other elements are controlled totally by a control section  40 . It is to be noted that the Teflon tubes may be replaced by another type of tubes, such as plastic tubes or metal tubes, insofar as the tube material is suitable for the properties of the lubricant. The supply tank  15  is disposed in a higher position than the collection tank  11 . 
     As shown in  FIGS. 4 and 5 , the syringe  26  is of a cylindrical shape, and is held horizontal. The syringe  26  has a symmetric internal structure about a center plane including center axes of the cylindrical ports  28  to  31 . The syringe  26  has an internal diameter that is approximately equal to an external diameter of the piston  42  at least in a range L in which the piston  42  is moved back and forth. An O-ring  43  is put around the piston  42  at a center position in the axial direction, so as to close the clearance between the outer periphery of the piston  42  and the inner periphery of the syringe  26 . Large diameter sections  44  and  45  having a larger diameter than the external diameter of the piston  42  are formed on opposite sides of the piston  42 . The large diameter sections  44  and  45  have an axial length that is shorter than the reciprocation range L of the piston  42 . The first and second ports  28  and  29  are formed on the top and bottom sides of the large diameter section  44  respectively. The third and fourth ports  30  and  31  are formed on the top and bottom sides of the large diameter sections  45  respectively. 
     The dispenser  16  is also provided with a mixing mechanism for mixing or stirring the lubricant in the syringe  26 , to keep ratio of components constant. The mixing mechanism is constituted of a pair of stirrers  47  and  48 , a pair of stirrer drive rings  49  and  50 , and a pair of stirring actuators  51  and  52 . The stirrers  47  and  48  have the same structure, each having three stirring blades  53  or  54  and internal magnets  55  or  56 , as shown in detail in  FIGS. 6 and 7 . The stirrers  47  and  48  are mounted on the piston rod  25  between the piston  42  and the large diameter sections  44  and  45 , such that the stirrers  47  and  48  may rotate around and slide along the piston rod  25  as well. Thus, the piston rod  25  is driven to move the piston  42  back and forth between the stirrers  47  and  48 . To avoid wearing the internal periphery of the syringe  26  by friction between the stirrer  47  or  48  and the syringe  26 , the stirrers  47  and  48  have a smaller external diameter than the internal diameter of the syringe  26 . 
     The stirrer drive rings  49  and  50  are disposed on the syringe  26  in those positions around the stirrers  47  and  48  respectively, and are mounted through bearings to a syringe holder  58 , such that the stirrer drive rings  49  and  50  may rotate around the syringe  26 . The stirrer drive rings  49  and  50  are driven to rotate when driving forces are transmitted from the stirring actuators  51  and  52  through gears  49   a  and  50   a  that are formed around the outer periphery of the stirrer drive rings  49  and  50  respectively. The stirrer drive rings  49  and  50  have internal magnets  59  or  60 , as shown in detail in  FIG. 8 , so that the stirrer drive rings  49  and  50  hold the stirrers  47  and  48  in those relative positions to the stirrer drive rings  49  and  50 , which are determined by the relative positions of the magnets  55  and  56  of the stirrers  47  and  48  to the magnets  59  and  60  of the stirrer drive rings  49  and  50 , even while the stirrer drive rings  49  and  50  are rotating. Thus, the stirrers  47  and  48  rotate following the stirrer drive rings  49  and  50 . 
     Referring to  FIG. 6 , each of the stirrers  47  and  48  has a hole  62  formed through along the axial direction thereof, for putting the piston rod  25  through the hole  62 . The stirring blades  53  or  54  are provided on one face end of the stirrers  47  or  48  to protrude in the axial direction of the stirrers  47  or  48 , that is, in parallel to the piston rod  25 . The three stirring blades  53  or  54  are arranged radially around the hole  62  at intervals of 120°. The stirrers  47  and  48  are mounted on the piston rod  25  in the opposite directions from each other, with their stirring blades  53  and  54  oriented to the large diameter sections  44  and  45  respectively. 
     As shown in  FIG. 7 , the magnets  55  and  56  are embedded in cavities  63  which are formed inside the stirrer  47  or  48  with their open ends oriented toward the center axis of the stirrer  47  or  48 . Each stirrer  47  or  48  has six cavities  63 , three of which are arranged radially around the center axis at intervals of 120°, and other threes are located on one side of these three cavities in the axial direction of the piston rod  25  in one-to-one alignment with the former three cavities. The magnets  55  and  56  are put into the cavities  63  through holes  64  which are formed through the outer peripheries of the stirrers  47  and  48  in diametrically opposite positions from the cavities  64 . The magnets  55  and  56  may be arranged in a different way from illustrated, insofar as they are arranged symmetrical about the rotary axis of the stirrer  47  or  48 . 
     The stirrer drive rings  49  and  50  have the same structure. As shown in  FIG. 8 , the magnets  59  and  60  are arranged in correspondence with the magnets  55  and  56  respectively. That is, there are six magnets  59  or  60  in each stirrer drive ring  49  or  50 , three of which are arranged radially at intervals of 120°, and other threes are located on one side of these three magnets in the axial direction of the piston rod  25  in one-to-one alignment with the former three magnets. Polarities of the magnets  55 ,  56 ,  59  and  60  are so arranged that the magnets  59  attract the magnets  55 , whereas the magnets  60  attract the magnets  56 . According to this configuration, the stirrer  47  or  48  is held stationary in the stirrer drive ring  49  or  50  while the stirrer drive ring  49  or  50  stops, and rotates along with the stirrer drive ring  49  or  50  as the stirrer drive ring  49  or  50  rotates. It is possible to arrange polarities of the magnets  55 ,  56 ,  59  and  60  such that the magnets  55  or  56  repel the magnets  59  or  60  respectively. 
     Now the operation of the above described lubricant coating system  10  will be briefly described. 
     The lubricant coating system  10  automatically operates according to a sequence stored in a memory  70  (see  FIG. 1 ) of the control section  40 . There are a normal mode and a standby mode in the sequence, as shown in  FIG. 9 , and these modes are automatically switched over appropriately depending upon traffic of the pallets  19  on the conveyer line  20 . Specifically, the normal mode is executed when the pallets  19  are successively smoothly conveyed, whereas the standby mode is executed when the pallets  19  on the conveyer line  20  get jammed upstream or downstream of the coating station, or when there are not any pallets  19  upstream the conveyer line  20 . Sensors  71  and  72  are disposed in upstream and downstream positions of the coating station, to detect the pallets  19  on the conveyer line  20 . 
     In the normal mode, the dispensing operation is performed while setting the on-off valve  17   b  of the needle valve  17  open. As shown in  FIG. 10 , at the start of the normal mode, it is checked whether the two-way switching valves  13  and  14  are set in the closed position, and if not, the valves  13  and  14  are switched to the closed position. Although it is not shown in the drawings, the position of the four-way switching valve  12  is also checked to confirm that the switching valve  12  is set in either the forth movement position or the back movement position. 
     Thereafter, upon receipt of the end-of-positioning signal, the rod driving actuator  24  is driven to move the piston rod  25  in one direction by a constant stroke. Then, a corresponding amount of lubricant is ejected through the needle valve  17 , and is put on the object to coat  18 . One of the stirrers  47  and  48  that is placed in the sucking side of the syringe  26 , e.g. the stirrer  48  in the forth movement of the piston rod  25 , is always rotated, whereas the other stirrer in the ejection side of the syringe  26  is not rotated. Because the stirrers  47  and  48  can slide on the piston rod  25 , the stirrers  47  and  48  are held in the same relative positions to the stirrer drive rings  49  and  50  by virtue of the magnets  55 ,  56 ,  59  and  60 , even while the piston rod  25  is moved in the axial direction. 
     The rod driving actuator  24  drives the piston rod  25  to move in one direction by one stroke each time it receives the end-of-positioning signal, to coat the object  18  with the constant amount of lubricant. When the piston rod  25  reaches a terminal of one moving direction, the control section  40  controls the rod driving actuator  24  to change the moving direction of the piston rod  25 . Correspondingly, the sucking side and the ejecting side of the syringe  26  are exchanged, and the stirrer  47  or  48  that has been rotating stops rotating, and the other stirrer  47  or  48  starts rotating continually 
     Before starting the dispensing operation in the opposite direction, a piston turning operation is executed. As shown in  FIG. 11 , the piston turning operation consists of a drip prevention step, a venting step, a valve switching step for the four-way valve  12 , a pre-stroking step, and a nozzle cleaning step. 
     In the drip preventing step, the switching values  12  to  14  stay in the same positions as in the preceding dispensing operation, but the piston rod  25  and thus the piston  42  are moved slightly in the opposite direction to the preceding moving direction. Since the piston rod  25  is first moved forward in the dispensing operation in this instance, the switching valve  12  is set in the forth movement position, and the switching valves  13  and  14  are set in the closed position, as shown in  FIG. 12 , and the piston rod  25  is moved slightly backward. Thereby, the lubricant is sucked through the second port  29  back to the syringe  26 , so the lubricant remaining in the nozzle  17   a  is prevented from driping. 
     The venting step follows the drip prevention step. In the venting step, the actuator  33  or  34  is driven to switch one of the two-way switching valves  13  and  14  that is on the sucking side in the preceding dispensing operation, i.e. the valve  14  in this instance, to the open position for a limited time, as shown in  FIG. 13 . While the valve  14  is turned open, the piston rod  25  is moved by a predetermined stroke in the opposite direction to the preceding movement, i.e. in the backward direction in this instance. Since the supply tank  15  is disposed above the collection tank  11 , the lubricant flows from the supply tank  15  into the syringe  26  by itself, as the lubricant flows through the open valve  14  out of the syringe  26  into the collection tank  11 , because of the difference in height between the supply tank  15  and the collection tank  11 . Thereby, bubbles that have been produced in the lubricant because of negative pressure inside the syringe  26  flow with the lubricant into the collection tank  11 , so the bubbles are eliminated from inside the syringe  26 . The stroke of the piston rod  25  propels venting the bubbles contained in the lubricant out to the collection tank  11 . The stroke of the piston rod  25  for the venting step is determined smaller than that for the dispensing operation, but may be equal to or larger than the stroke for the dispensing operation. 
     Since the first and third ports  28  and  30  are formed on the top sides of the large diameter sections  44  and  45 , and the air entering the syringe  26  or the bubbles generated in the syringe  26  tend to come together in the top sides of the large diameter sections  44  and  45 , the bubbles are efficiently exhausted. Venting or exhausting the bubbles prior to the dispensing operation prevents the bubbles from being increased by the dispensing operation, and thus facilitates making the dispensing operation in continuous succession. It is to be noted that the venting step may be executed only by opening one of the valves  13  and  14  that is in the sucking side in the preceding dispensing operation, without driving the piston rod  25 . 
     After the venting step, either of the two-way switching valves  13  and  14  is reset to the closed position, and the four-directional switching actuator  35  is driven to switch the four-way switching valve  12  to the other position than before, i.e., to the back movement position in this instance, as shown in  FIG. 3 . Thereby, the second port  29  that has functioned as an ejection port in the preceding dispensing operation is changed to a sucking port. 
     Thereafter, the pre-stroking step is executed by driving the rod driving actuator  24  to move the piston rod  25  and thus the piston  42  in the backward direction by a small amount. Thereby, bubbles generated by the switching of the four-way switching valve  12  are let out of the syringe  26 , and the lubricant is fed to the needle valve  17 , driving out the air that has been sucked into the needle valve during the drip prevention step. Simultaneously, the control section  40  drives a shift mechanism  70  to insert an anti-sprinkle plate  71  into front of the nozzle  17   a,  so that the lubricant from the nozzle  17   a  may not be sprinkled. After the shift mechanism  70  retracts the anti-sprinkle plate  71  from the front of the nozzle  17   a,  the cleaning mechanism  22  is activated to clear the lubricant off the nozzle  17   a.  Thereafter, the piston rod  25  is moved by the constant stroke in the backward direction to dispense the lubricant. As described so far, since the piston rod  25  is moved in the same direction in the piston turning operation as in the following dispensing operation, the lubricant coating system  10  can start the dispensing operation immediately. When the piston rod  25  and thus the piston  42  reach a terminal in the backward direction, the piston turning operation is executed in the same way as set forth above, while moving the piston rod  25  in the same direction as in the following dispensing operation. 
     As long as the normal mode is continued, the above described operations are repeated to put the lubricant on the objects to coat  18  successively. 
     Although the stirring blades  53  and  54  protrude in parallel to the piston rod  25  in the present embodiment, it is possible to incline the stirring blades  53  and  54  to the axial direction of the piston rod  25 , so as to cause the lubricant to whirl in the axial direction. The stirring blades may be oriented in a perpendicular direction to the axis of the piston rod  25 . The number of stirring blades  53  and  54  and the number of magnets  55 ,  56 ,  59  and  60  are not limited to the above embodiment, but may be modified appropriately. The arrangement of the stirring blades as well as the magnets in the stirrer may be modified appropriately. 
     Now the operations in the standby mode will be described. In the standby mode, the control section  40  keeps on monitoring the sensors  71  and  72 , so that the lubricant coating system  10  may return to the normal mode as soon as it is allowed. 
     In the standby mode, as shown in  FIG. 14 , the stirring actuators  51  and  52  are driven to rotate both of the stirrers  47  and  48  for a time intermittently at regular intervals. One of the stirrers  47  and  48  that is on the sucking side of the syringe  26  at the start of the standby mode continues rotating during the standby mode as in the normal mode. Therefore, strictly speaking, the other stirrer  47  or  48  is driven to rotate intermittently during the standby mode. Thus, the density of the lubricant is maintained constant in the syringe  26 . 
     When a predetermined long time has elapsed from the start of the standby mode, the piston rod  25  is moved in the opposite direction to the preceding moving direction for the sake of making the same drip preventing operation as described before with respect to the piston turning operation. Thereafter, the valve member  17   a  of the needle valve  17  is closed, for preventing the lubricant from evaporating. 
     When the lubricant coating system  10  returns to the normal mode from the standby mode after the valve member  17   a  is closed, a recovery operation is executed. In the recovery operation, as shown in  FIG. 15 , the on-off valve  17   b  is opened, and the piston rod  25  is moved by several strokes, to supply the lubricant to the needle valve  17 , thereby to drive the air out of the needle valve  17 . The number of strokes for this operation is determined such that the lubricant is ejected from the nozzle  17   a  without fail. The shift mechanism  70  is activated during the recovery operation, to insert the anti-sprinkle plate  71  in front of the nozzle  17   a.  After the shift mechanism  70  retracts the anti-sprinkle plate  71  from the front of the nozzle  17   a,  the cleaning mechanism  22  is activated to clear the lubricant off the nozzle  17   a.  Thereafter, the piston rod  25  is moved by the constant stroke in the backward direction to dispense the lubricant. 
     In the above embodiment, the stirrers  47  and  48  are mounted rotatable on the piston rod  25 . According to another embodiment, as shown in  FIG. 16 , a ring-like stirrer  83  is fitted in a groove  84  that is provided around an inner periphery of a syringe  82 , such that the stirrer  83  may turn around a piston rod  87  while being guided along the groove  84 . The groove  84  is formed by a recessed inner peripheral portion of the syringe  82  and a sleeve  88  that is fit in the syringe  82  from its one end. In this embodiment, a number of stirring blades  86  are provided at regular intervals on an inner periphery of the stirrer  83  and are protruded radially inward to an extent that the stirring blades  86  will not interfere with the piston rod  87 . As shown in  FIG. 16 , it is preferable to incline the stirring blades  86  to the axial direction of the piston rod  87 , so as to cause the fluid to whirl in the axial direction in the syringe  82 . 
     Although the stirrer drive rings  49  and  50  that are rotated around the syringe  26  by the stirring actuators  51  and  52  are provided as a stirrer driving device for rotating the stirrers  47  and  48  in the above embodiment, a stirrer driving device of the present invention may be configured differently. For example, according to the second embodiment shown in  FIG. 16 , a magnetic coil  80  and a control circuit  81  constitute the stirrer driving device. The magnetic coil  80  is constituted of a plurality of coils that generate rotary magnetic fields at three or four regularly spaced positions around the syringe  82 . The stirrer  83  has at least two magnets  85  in diametrically opposite circumferential positions thereof, the magnets  85  generating magnetic fields in the radial directions of the stirrer  83 . The control circuit  81  generates electric current for exciting the magnetic coils  80  in those phases necessary for rotating the stirrer  83 . 
     EXAMPLE 
     The syringe  26  is preferably formed from a non-magnetic material, such as resin, ceramic or glass. As the resin, transparent PFA (perfluoro-alkoxy fluoroplastics) is preferable. The stirrers  47  and  48  are preferably formed from a resin or a ceramic. The stirrer drive rings  49  and  50  are preferably formed from a non-magnetic material, such as resin or brass. 
     The lubricant coating system  10  of the above embodiment is preferably applicable to a recycling system of a lens-fitted photo film unit. In that case, a shutter mechanism of a used lens-fitted photo film unit is assumed to be the object to coat  18 . The lens-fitted photo film unit is constituted of a main body that contains a photo filmstrip therein and has exposure mechanisms mounted thereon, and front and rear covers that cover the main body portion from the front and rear sides. The exposure mechanisms include a taking lens, the shutter mechanism, and a winding lock mechanism, and are expected to be reused. As well-known in the art, the shutter mechanism consists of a shutter drive lever, a shutter blade, a shutter charging spring, and a returning spring. The shutter blade usually closes a shutter opening that is located behind the taking lens, and may swing in a plane perpendicular to an optical axis of the taking lens. The shutter drive lever may rotate on an axis that extends in a vertical direction of the lens-fitted photo film unit, and kicks the shutter blade as it rotates from a charged position to a released position, causing the shutter blade to swing in a direction to open the shutter opening. The shutter charging spring is hooked at one end on a spring holding portion of the shutter drive lever, and at the other end on a portion other than the shutter drive lever, such that the shutter charge spring urges the shutter drive lever to the released position. The returning spring urges the shutter blade to return to the initial position closing the shutter opening. 
     The used lens-fitted photo film unit is collected and disassembled in a factory for recycling. In the recycling system, some parts are sorted to be recycled as materials, and other parts are reused as it is for assembling a new product. As for the lens-fitted photo film unit, since the main body is covered with the front and rear covers, the main body is little stained or damaged in most cases, so the main body is expected to be reused. Before reusing the main body, the exposure mechanisms are inspected to check if these mechanisms operate properly. According to the inspection, the speed of movement of the shutter blade tends to be changed depending upon under what conditions the collected lens-fitted photo film unit has been used. But it has been found that the variations in the shutter speed can be reduced to a predetermined tolerable range, without exchanging the parts, if only a lubricant is put on the engagement between the one end of the charging spring and the spring holding portion of the shutter drive lever. The lubricant coating system  10  of the present invention is effectively usable for this purpose. After being coated with the lubricant, the speed of the shutter blade is measured a number of times, to check if the speed variation is in the tolerable range. 
     As the lubricant, a liquid type lubricant that is composed of an oil component with a high fluidity at a low temperature, and an ultrafine fluoroplastic is suitable for the shutter mechanism. Exemplary of such liquid type lubricant is Dry Surf HF-1800 (trade name), produced by Herves Ltd. This lubricant is called a dry coating lubricant, looks opaque white, has no flash point in the open-cup flash point test, is usable in a range from −30° C. to 120° C., and has a specific gravity of 1.25 at 25° C. After the coating, the surface of this lubricant is half-wet. Also, this lubricant includes no factor of destroying the ozone, lasts for 4.1 years in the atmosphere, and the GWP is 500 (CO 2 =1). Accordingly, this type of lubricant is highly volatile and contains solid components, so the density will change while it is stored in a hermetic container. To keep the density constant, the above described lubricant coating system  10  provided with the mixing devices is preferable. The amount of lubricant to put on the individual main body of the lens-fitted photo film unit is preferably 0.001 cc to 0.01 cc. 
     Since the piston rod  25  is moved back and forth in the lubricant coating system  10 , the lubricant may be dispensed successively. Because the lubricant contains the solid components, the lubricant is being stirred in the sucking side of the syringe  26  even during the dispensing operation. Since the lubricant is highly volatile, the on-off valve  17   b  of the needle valve  17  is closed when the standby mode continues for a long time. However, the present invention is applicable not only to dispensing the above described lubricant, but any kind of fluid may be dispensed by the dispenser of the present invention. 
     Meanwhile, it is very important to clear optical members off of dusts, sands and stains, since these extraneous objects remarkably lower the optical performances. Because optical members of the lens-fitted photo film unit, such as a taking lens and a finder lens, are more likely to get stained or scratched, it is necessary to inspect the optical members each individually before reusing them. 
     For this purpose, these lenses have conventionally been inspected by naked-eyes on the basis of a limit sample, but this conventional method is inefficient and is inferior in reliability. To solve this problem, Japanese Laid-open Patent Application No. 8-304052 discloses a lens inspection device that scans the lens surface with a spot light beam across a constant direction, and photo-electrically detects light that is transmitted and scattered through the lens. Because the transmitted light is scattered if the lens has any defect, e.g. get scratched or stained, the lens inspection device generates a defect signal when the detected signal goes above a preset level. This inspection device makes it possible to detect strains or scratches on the lens through comparison of the signal level with the preset level, and thus accomplish efficient and quantitative evaluation. 
     Since the above conventional inspection device scans a spot light beam along a line, the inspection cannot be so speedy. Besides, where the lens has a scratch or a strain in the scanning direction, the transmitted light is little scattered so it is difficult to detect them accurately. 
     Moreover, because the stain on the lens surface reflects or deflects some fragment of the incident light, so the intensity of the transmitted light is decreased. Therefore, an optimum photo-sensitivity for detection of the stains is considered to be different from that for detection of the scratches. However, since the above conventional inspection device inspects any kinds of defects of the lens in the same way, the reliability is unsatisfactory. 
       FIGS. 17 to 29  show a lens inspection system that permits detecting scratches, extraneous objects, such as stains, and other kinds of defects of an optical member with high accuracy. That is, according to the following embodiment, a light beam is projected from one side onto a lens to inspect, and a light transmitted and scattered through the lens is photo-electrically detected as a dark field image of the lens on the other side of the lens, and when the intensity of the photoelectric signal detected from an inspection range of a photoelectric imaging device goes above a preset level, the lens is judged to be defective. 
     In the present embodiment, the light is projected onto the entire surface of the lens at once and a dark field image of the lens is photographed through a photoelectric element. Therefore, the inspection becomes speedy. Since the defection sensitivity would not fluctuate depending upon the direction of existence of the defects, any kinds of defects are detected without fail. 
     The lens inspection system according to the present embodiment is adapted to inspecting the taking lenses of the lens-fitted photo film units. As shown in  FIG. 17 , the lens inspection system for the lens-fitted photo film unit, hereinafter referred to as the inspection device  110 , is mainly constituted of a lens cleaner  111 , a scratch detector  112 , an extraneous object detector  113  and a focus examiner  117 . 
     As shown in  FIGS. 18 and 19 , the scratch detector  112  and the extraneous object detector  113  are each provided with a light projector  115  or  116  for projecting inspection light onto a taking lens  114 , and an imaging device  120  or  121  that picks up electric signals from an optical image of a convex surface  114   a  of the taking lens  114 , respectively. The taking lens  114  to inspect is held in a recess that is formed in a top surface of a specific pallet  122 . The pallet  122  is successively conveyed by a not-shown pallet conveyer mechanism from the scratch detector  112  to the extraneous object detector  113 . 
     Referring to  FIG. 20  showing the scratch detector  112 , the pallet  122  holding the taking lens  114  is positioned in between the light projector  115  and the imaging device  120 , with the convex surface  114   a  of the taking lens  114  oriented upward. A substantially cylindrical aperture  123  is formed from the bottom of the recess through the bottom surface of the pallet  122 , so the inspection light from the light projector  115  is projected from the bottom side onto the taking lens  114 . To prevent eclipse of the inspection light from the light projector  115 , the aperture  123  has a smaller diameter on the side of the taking lens  114 . In this instance, on condition that the pallet  122  has a thickness of 8 mm, the aperture  123  has a diameter of 7.5 mm in on the side of the taking lens  114 , and a diameter of 13 mm on the side of the light projector  115 . 
     The imaging device  120  is constituted of a CCD image sensor  124  having photo sensor cells, called pixels, arranged in a two-dimensional matrix, a close-up ring  125  and an image forming lens  126  that are attached to the front of the CCD image sensor  124 . The taking lens  114  is positioned such that an optical axis C of the taking lens  114  coincides with an optical axis of the image forming lens  126  and centers of the close-up ring  125  and the CCD image sensor  124 . An optical image of the taking lens  114  is formed through the image forming lens  126  on a photoelectric conversion surface of the CCD image sensor  124 , so photoelectric signals whose intensities are proportional to the intensities of the incident light on the individual pixels are sent from the imaging device  120  to a scratch discriminator  130 . 
     It is to be noted that the focal length of the image forming lens  126  may be set in a range from 16 mm to 50 mm, and that the close-up ring  125  is adjustable in a range from 6 mm to 40 mm. Also, a spacing L 1  between the top surface of the pallet  122  and the CCD image sensor  124  may be set in a range from 30 mm to 200 mm. In this instance, the focal length of the image forming lens  126  is set at 50 mm, and the close-up ring  125  is set at 30 mm, whereas the spacing L 1  is set at 130 mm. 
     The close-up ring  125  is fixed in a distance L 2  from the bottom surface of the pallet  122 . A not-shown red LEDs are built in the close-up ring  125  to project the inspection light uniformly onto the taking lens  114 . A blinding mask  131  is mounted on a center of the light projector  115  so as to prevent inclusion of the light projector  115  in the photographic field of the imaging device  120 . That is, as shown in  FIG. 5 , direct rays of the inspection light which are projected in the axial direction from the light projector  115  are prevented from falling on the photoreceptive surface of the CCD image sensor  124 . Only indirect rays which are scattered through the taking lens  114  may fall on the photoreceptive surface. Accordingly, a dark field image of the taking lens  114  is formed on the CCD image sensor  124 . Therefore, where the taking lens  114  has no scratch, as shown in  FIG. 21 , the intensities of the photoelectric signals are lower than a predetermined level. 
     On the contrary, if there is a scratch  132  on the taking lens  114 , as shown in  FIG. 22 , some rays of the inspection light are scattered at the scratch  132 , and is projected onto the CCD image sensor  124 . In that case, the intensities of the photoelectric signals from those pixels of the CCD image sensor  124 , onto which the scattered light rays fall are raised. Based on the photoelectric signals from the CCD image sensor  124 , the scratch discriminator  130  determines whether the taking lens  114  gets any scratches or not. As shown for example in  FIG. 23 , the scratch  132  is detected by the scratch discriminator  130  as a light area  133  having a corresponding size to the scratch  132 . For the sake of showing the light area  133  conspicuously, it is drawn in black in  FIG. 23 , whereas other dark area  34  is drawn in white. The blinding mask  131  may have a diameter L 3  in a range from 10 mm to 20 mm insofar as it prevent the direct projection of the inspection light onto the CCD image sensor  124 . In this instance, the diameter L 3  is 12 mm. 
     In the scratch discriminator  130 , a round range on the photoreceptive surface of the CCD image sensor  124 , that is formed with a diameter of 6 mm about the optical axis C of the taking lens  114 , is defined to be an inspection range  138 , and the signal intensities from those pixels which are included in the inspection range  138  are represented by 8-bit tonal levels (0 to 255). The scratch discriminator  130  defines those pixels whose signal intensities are not less than “140” in the tonal level as light pixels, and checks if there is at least a light area consisting of the light pixels of a predetermined number, e.g. 110 or more, in the inspection range. If there is, the scratch discriminator  130  judges that the taking lens  114  gets scratched. If not, the scratch discriminator  130  judges that there is no scratch on the taking lens  114 . 
     In the present embodiment, the threshold tonal level for the light pixel is set at “140”, and the threshold pixel number for the light area is set at “110”. But these threshold values may be modified appropriately according to the required inspection accuracy. Even if an individual scratch is so fine that it cannot be detected on the basis of the threshold values of the above embodiment, if there are a number of scratches, the optical performance is lowered below a reusable level. Therefore, in order to improve the inspection accuracy, it is preferable to set up the scratch discriminator  130  such that  130  judges the taking lens  114  to be defective when there are more than a predetermined number of fine scratches on the taking lens  114 , as well as when there is a large scratch on the taking lens  114 . 
     As shown in  FIGS. 19 and 24 , the imaging device  121  of the extraneous object detector  113  is constituted of a CCD image sensor  135 , a close-up ring  136  and an image forming lens  137  in the same way as for the imaging device  120  of the scratch detector  112 . The light projector  116  of the extraneous object detector  113  is substantially circular, and is disposed above the taking lens  114  with its center on the optical axis C of the taking lens  114 , when the pallet  122  holding the taking lens  114  is positioned in the extraneous object detector  113 . That is, the light projector  116  is disposed between the pallet  122  and the imaging device  121 . Not shown LEDs are built in the light projector  116 , and inspection light is projected from a projection surface  116   a  that is formed around an inner periphery of the light projector  116  and is oriented toward the taking lens  114  when it is positioned in the extraneous object detector  113 . Thus, the inspection light from the light projector  116  is not directly projected onto the close-up ring  125 , but only indirect rays scattered at the taking lens  114  can fall on the close-up ring  125 . So the close-up ring  125  also takes a dark field image of the taking lens  114 . 
     If there is not an extraneous object on the taking lens  114 , the inspection light passes through the taking lens  114 , as shown in  FIG. 25 , so the intensities of photoelectric signals from respective pixels of the CCD image sensor  135  are low. On the contrary, if an extraneous object  141  is on the taking lens  114 , as shown in  FIG. 26 , some rays of the inspection light from the light projector  116  are scattered at the taking lens  114  and fall on the photoreceptive surface of the CCD image sensor  135 . As a result, the intensities of the photoelectric signals from those pixels corresponding to the position of the extraneous object  141  on the taking lens  114  are increased. The photoelectric signals are sent from the imaging device  121  to an extraneous object discriminator  140 , so the extraneous object discriminator  140  determines based on the photoelectric signals whether there is any extraneous object on the taking lens  114  or not. 
     It is to be noted that the light projector  116  must have a large enough internal diameter L 4  for preventing inclusion of the light projector  116  in a photographic field of the imaging device  121 . However, too large internal diameter L 4  lowers the illuminance on the taking lens  114  so much that the inspection accuracy is lowered. For this reason, the internal diameter L 4  is preferably set in a range from 130 mm to 180 mm. In this instance, the value L 4  is set at 130 mm. For the same reason, a spacing L 5  between the top surface of the pallet  122  and the light projector  116  is preferably set in a range from 10 mm to 30 mm. In this instance, the value L 5  is set at 16 mm. 
     In the extraneous object discriminator  140 , as shown in  FIG. 27 , a plurality of zones  142  having a width of 0.5 mm and extending in different diametrical directions are defined in an inspection range  144  that corresponds to the lens surface and thus the dark field image of the lens surface, and each zone  142  are sectioned into a number of rectangular segments  143  aligned in the diametrical direction. Each segment  143  has a length of 0.1 mm in the diametrical direction. The signal intensities from the pixels of the CCD image sensor  135  are also converted into 8-bit data representative of “0” to “255” tonal levels in the extraneous object discriminator  140 . The extraneous object discriminator  140  calculates a mean value of tonal levels (an average tonal level) of those pixels which belong to the same segment  143 . Thus, each segment  143  severs as an unit section of the inspection range  144 . If a difference between the average tonal levels of adjacent two of the segments  143  is above “120”, the extraneous object discriminator  140  judges that some extraneous object is put on the taking lens  114 . When the difference in the average tonal level between the adjacent segments  143  is less than “120” with respect to every segment, the extraneous object discriminator  140  judges that there is no extraneous object on the taking lens  114 . 
     Although the threshold value of the difference between the average tonal levels of the adjacent segments  143  for judgement in the extraneous object discriminator  140  is set at “120” in the present embodiment, the threshold value may be modified appropriately according to the required inspection accuracy. The size of the segments  143  may also be modified appropriately according to the fineness of the extraneous objects to detect. 
     Next, the operation of the lens inspection device  110  will be described with reference to the flow chart of  FIG. 28 . Unit bodies of used lens-fitted photo film units are disassembled and sorted into respective components in an inspection factory. The taking lens  114  is separated from the unit main body, and is subjected to a cleaning and blowing process, for removing dusts and fats off of the surface of the taking lens  114 . 
     After the cleaning and blowing process, the taking lens  114  is placed on the pallet  122 , to be conveyed to the scratch detector  112 . In the scratch detector  112 , the light projector  115  projects the inspection light from the bottom side of the pallet  122  onto the entire surface of the taking lens  114  but diagonally to the optical axis C of the taking lens  114 , so the imaging device  120  disposed above the taking lens  114  takes a dark field image of the taking lens  114 . If there is any scratch on the taking lens  114 , the inspection light is scattered at the scratch, so some rays fall on the CCD image sensor  124 . The photoelectric signals obtained by the CCD image sensor  124  are sent to the scratch discriminator  130 . The scratch discriminator  130  discriminates the light pixels whose tonal levels are not less than “140”, and judges that the taking lens  114  has a scratch when there is an area consisting of not less than 110 successive light pixels. The taking lens  114  having any scratch may not be reused, so it is melted and pelletized. If the taking lens  114  is judged to have no scratch, it is conveyed to the extraneous object detector  113 . 
     In the extraneous object detector  113 , the circular light projector  116  projects the inspection light from above and around the convex surface  114   a  of the taking lens  114 , and the imaging device  121  takes a dark field image of the taking lens  114 . If there is any extraneous object on the taking lens  114 , the inspection light is reflected from the extraneous object and falls on the CCD image sensor  135 . The photoelectric signals obtained by the CCD image sensor  135  are sent to the extraneous object discriminator  140 . The extraneous object discriminator  140  detects differences in average tonal level between every couple of adjacent segments  143 , and judges that there is an extraneous object on the taking lens  114  when any of the differences is above  120 . 
     The taking lens  114  that is judged to have any extraneous object is melted to be pelletized, or sent back to the cleaning and blowing process, and is inspected again. The taking lens  114  that is judged to have no extraneous object is conveyed to the focus inspector  117 . After passing the inspection by the focus inspector  117 , the taking lens  114  is allowed to be reused. 
     In the above embodiment, the extraneous object discriminator  140  defines the segments  143  in the diametrically extending zones  142  of the inspection range  144 , as shown in  FIG. 27 . It is alternatively possible to section the inspection range  144  into concentrically and radially into sectors  145 , as shown in  FIG. 29 , and calculate average tonal levels of the respective sectors  145 . That is, each sector  145  constitutes an unit section of the inspection range  144  in this embodiment. The light source of the light projector  115  or  116  is not limited to the LEDs, but may be another kind of light source, such as a halogen lamp, insofar as it is able to project light uniformly onto the optical member to inspect. 
     Projecting the inspection light simultaneously onto the entire objective or image side surface of the lens achieves a quick inspection on the lens defects as compared to the conventional method where the inspection light is scanned linearly across the lens. Also the inspection accuracy becomes independent of the direction the defect exits. 
     Doing inspection for scratches separately from inspection for extraneous objects permits setting up an optimum inspection sensitivity for each kind of inspection. Since the inspection light is projected onto the lens from either side, if a defect cannot be detected when the inspection light is projected from the bottom side, the defect may be detected when the inspection light is projected from the top side. Especially because extraneous objects or stains are more likely to put on the objective side of the lens, inspection accuracy is remarkably improved by projecting the inspection light onto the objective side to detect extraneous objects or stains based on the reflected light from the objective side. 
     However, it is possible to execute either the inspection for scratches or the inspection for extraneous objects alone. Although the inspection for scratches is executed before the inspection for extraneous objects in the above embodiment, the sequence may be reversed. Covering the periphery of the scratch detector  112  and the extraneous object detector  113  with black light-shielding curtains protects the CCD image sensors  124  and  135  from ambient light, and thus contributes to increasing the inspection accuracy. 
     The present invention has been described with respect to the taking lens inspection device that inspects single-element convex lenses, the present invention is applicable also for inspection on concave lenses or on lens systems composed of a plurality of lens elements, if only the optics are arranged to make it possible taking the dark field image. 
     Thus, the present invention is not to be limited to the above embodiments but, on the contrary, various modifications are possible to those skilled in the art without departing from the scope of claims appended hereto.