Abstract:
The present invention is to avoid an occurrence of an suction error caused by a deviation with respect to a component of an suction nozzle, namely, an accident of a failure in capturing a component. A deviation amount is detected between a center of a component absorbed by an suction nozzle and an suction position of the suction nozzle. Also, a value in which this deviation amount is multiplied by a sensitivity coefficient is added as a positional correction at a next time of suction by the suction nozzle. Accordingly, when the suction nozzle absorbs the component at the next time, the suction nozzle normally absorbs the component at the position substantially corresponding to the center.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]    The present document is based on Japanese Priority Document JP 2000-235816, filed in the Japanese Patent Office on Aug. 3, 2000, the entire contents of which being incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION 1. Field of the Invention  
         [0002]    The present invention relates to an apparatus for and a method of correcting a component holding position, and more particularly to an apparatus for and a method of correcting a component holding position in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined position.  
           [0003]    2. Description of the Related Art  
           [0004]    In an electronic circuit, electronic components are mounted in predetermined positions on a circuit board on which wiring patterns are formed in advance. Then, the electrical continuities are established between electrodes of those electronic components and the wiring patterns. Accordingly, the predetermined connections are attained.  
           [0005]    When the electronic circuit is formed in this way, the components must be mounted in turn on a circuit board made of insulation material, in which predetermined wiring patterns are formed on a surface thereof. Here, a position at which the component is mounted must be a position at which the electrode must be normally connected to a land for the connection of the wiring patterns. If the position at which the component is mounted is deviated or out of alignment, a desired connection is not attained, which may result in an occurrence of an erroneous wiring or a short-circuit trouble.  
           [0006]    A mount machine is used in order to automatically mount the circuit components on the insulation board. It is possible to avoid the above-mentioned problems by improving the mount accuracy of this mount machine.  
           [0007]    The supply of the components in such an automatically mounting apparatus is carried out in a manner that it is accommodated in a concave portion on a tape to be fed from a component tape feed reel of a part cassette, and the component in the concave portion of the tape located at the position from which the component is taken out is taken out by an suction nozzle, and automatically mounted.  
           [0008]    Japanese Laid Open Patent Application (JP-A-Heisei, 7-212095) discloses a component mount method for totaling a deviation amount in an inspection measurement result for each inspection unit of an inspection device at a step of mounting a component on a board, for each inspection unit, and estimating a deviation amount of the board from the totaled deviation amount for each inspection unit, and then estimating the deviation amount of the board or calculating a deviation amount from which the board deviation amount is subtracted for each inspection unit, on the basis of a difference between the estimated deviation amount for each inspection unit caused by the board deviation and the above-mentioned deviation amount for each inspection unit.  
           [0009]    In the conventional above-mentioned automatic mounting apparatus, when this mounting apparatus holds a target component, it is treated that this target component is always located in advance at a predetermined position of a concave portion of a tape. However, in association with the reduction and the miniaturization in the dimension of the component to be treated in the component mounting apparatus, when the suction nozzle absorbs the component from a constant position, a trouble is brought about such as an erroneous capturing, a slant holding, a displacement of a holder or the like.  
           [0010]    [0010]FIG. 12 shows a case where a center of an suction nozzle  2  is deviated with respect to a center of a component  1 . If image recognition is tried by a television camera in such condition, this try results in a problem that a shade of the nozzle  2  is erroneously recognized as a shade of the component  1 .  
           [0011]    Also, if the component  1  is absorbed at an offset state with respect to the center of the suction nozzle  2  as shown in FIG. 13, this results in a problem of a so-called standing suction at which an suction force causes the posture of the component  1  to be changed from a horizontal state to an oblique state. If the component  1  is obliquely absorbed in this way, the component  1  cannot be normally mounted on the circuit board, or the component  1  is fallen from the suction nozzle  2  in the course of the absorbing operation because of the lack of the suction force.  
           [0012]    The failure of the suction of the component  1  as shown in FIG. 12 or FIG. 13 directly leads to an occurrence of a defective sample or a drop in productivity. So, such situation must be unlimitedly reduced to zero. Accordingly, the predetermined position of the component  1  needs to be normally held by the suction nozzle  2 .  
           [0013]    The method of analyzing the deviation of the circuit board and mounting components thereon disclosed in Japanese Laid Open Patent Application (JP-A-Heisei, 7-212095), although firstly trying to set the offset, uses the above-mentioned trial result in its original state after the trial, and does not change the offset in the course of the absorbing operation. Thus, in a case of a sequential mounting of the components, even if the first setting of the offset amount is normally carried out, the disorder of the offset amount during the mounting results in a problem that the normal amount operation is not always carried out. That is, even if the offset amount is normally set, if the offset amount is out of order after that, an suction error is brought about, which results in a problem of an occurrence of a mounting error.  
           [0014]    The present invention is proposed in view of the above-mentioned circumstances and is to provide a component mounting apparatus which can solve a trouble caused by a deviation in a position of a component held by a holder, such as an suction nozzle or the like, and accordingly mount a component in position.  
         SUMMARY OF THE INVENTION  
         [0015]    An aspect of the present invention relates to a component holding position correcting apparatus in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined, said correcting apparatus comprising:  
           [0016]    a detector for detecting a deviation of a holding position of the holder with respect to a standard position of the component; and  
           [0017]    a controller for correcting a holding position at which the holder holds a next component, on the basis of the deviation detected by the detector.  
           [0018]    Here, the controller may correct the holding position, on the basis of a value in which the deviation detected by the detector is multiplied by a sensitivity coefficient. And, the standard position of the component is located at a substantial center of a plane held by the holder, or a position deviated by a predetermined direction and length with respect to the center.  
           [0019]    Another aspect of the present invention relates to a component holding position correcting apparatus in a component mounting apparatus for holding a component from a component pickup position of a part cassette with an suction nozzle, and mounting the component in a predetermined position on a circuit board, said correcting apparatus comprising:  
           [0020]    a detector for detecting a deviation of a holding position of the suction nozzle with respect to a standard position of the component; and  
           [0021]    a controller for correcting a holding position at which the suction nozzle holds a next component, on the basis of the deviation detected by the detector.  
           [0022]    Here, the detector may be an image recognition camera. And, it may be designed such that the components are accommodated in concave portions for component accommodation, in a one-to-one relation of a tape, and the tape is sequentially fed on the part cassette, and the component located at the component pickup position is held by the suction nozzle.  
           [0023]    Thus, according to such an apparatus for correcting a component holding position, the deviation amount of the holding position of the suction nozzle at a previous time can be used to carry out the correction for the holding position at which a next component is held. Thus, the holder can normally hold the next component. The sequential repetition of such operations enables the component to be always normally mounted on the predetermined position on the circuit board. Hence, it is possible to provide the component mounting apparatus having the high accuracy, the high stability and the high reliability.  
           [0024]    The invention with regard to a method of correcting a component holding position is a method of correcting a component holding position, characterized in that in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined position, in which:  
           [0025]    a detector detects a deviation of a holding position of the holder with respect to a standard position of the component, and  
           [0026]    a controller corrects a holding position at which the holder holds a next component, on the basis of the deviation detected by the detector.  
           [0027]    A preferable embodiment in the present invention is designed such that each time a mount head holds a component in turn, a deviation amount of an suction position with respect to a center of the component is recognized by a usual camera for a mount position correction, and its deviation amount is fed back to a movement amount of the mount head when a next component is held. Here, at a time of the feedback, 100% of the deviation amount is not used, and a value obtained by multiplying the deviation amount by a sensitivity coefficient is fed back. Also, when a portion other than the center of the component is held by the holder, the above-mentioned feedback is carried out by considering in advance an offset amount of an suction position with respect to the center of the component.  
           [0028]    If the correction operation via such feedback is repeated in turn, after a first component is normally held, a position of an suction head is automatically changed to an optimal position in turn each time a component is held. Not only the optimization of the holding position but also the optimization of the recognition position can be attained by using a mount position correction camera or a correction sensor as a camera for recognizing a holding position. That is, the component holding position of a robot is always stable. This stabilization enables the holding position to be located at the substantial center of the component. Thus, it can be recognized at the best sensitivity of the component recognition camera or sensor.  
           [0029]    According to such an embodiment, the mounting apparatus tries to automatically keep the component holding position at the optimal position, which results in the sharp decrease in the erroneous capturing of a component frequently occurring in the conventional technique, namely, the accident of the non-suction of a component. Also, the suction holder automatically maintains its holding position, which results in the sharp decrease in the suction error, such as the erroneous suction of a corner of a component or the lateral suction of a component.  
           [0030]    Since the holding position of the component via the holder is always stable, the recognition position of the fixed camera is also stabilized. Accordingly, it is possible to always recognize the component near a center position of the camera, at which a distortion of a lens or the like is little. This contributes to the improvement of the mount accuracy. Moreover, the holding position of the component via the holder is stabilized and located at the substantially center of the component. So, when the component is mounted at a certain angle, a calculation error is not easily brought about. Also, the holding position of the component via the holder is stabilized and located at the substantial center. Thus, it is possible to protect the suction nozzle constituting the holder from being located outside the component, and erroneously recognized as the component at the time of image recognition.  
           [0031]    Thus, according to such a method of correcting a component holding position, the deviation amount of the holding position of the component detected by the detector is effectively used. Then, such a deviation amount is used to carry out the correction when the next component is held. Accordingly, the next component is normally held by the holder. Moreover, since this operation is infinitely repeated, the component can be mounted at the high stability and the high reliability. 
       
    
    
     BRIER DESCRIPTION OF THE DRAWINGS  
       [0032]    [0032]FIG. 1 is an external perspective view showing an entire structure of a component mounting apparatus of the present invention;  
         [0033]    [0033]FIG. 2 is a plan view showing a main portion of the component mounting apparatus of FIG. 1;  
         [0034]    [0034]FIG. 3 is a block diagram showing a control system of the component mounting apparatus;  
         [0035]    [0035]FIG. 4 is an external perspective view showing a part cassette;  
         [0036]    [0036]FIG. 5 is an external perspective view of a tape for feeding and supplying a component;  
         [0037]    [0037]FIG. 6 is a plan view showing the tape;  
         [0038]    [0038]FIG. 7 is a plan view showing image recognition of an absorbed component;  
         [0039]    [0039]FIG. 8 is a flowchart showing an operation for correcting an suction position;  
         [0040]    [0040]FIG. 9 is a perspective view showing a component having a concave portion in an upper portion;  
         [0041]    [0041]FIG. 10 is a plan view showing the component of FIG. 9;  
         [0042]    [0042]FIG. 11 is a plan view showing a state of image recognition of the component;  
         [0043]    [0043]FIG. 12 is a plan view showing an operation for absorbing a component, by using an suction nozzle in a conventional component mounting apparatus; and  
         [0044]    [0044]FIG. 13 is a side view showing a component absorbed by an suction nozzle.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    [0045]FIGS. 1, 2 show the entire configuration of a component mounting apparatus having a component holding position correcting apparatus, according to an embodiment of the present invention. This component mounting apparatus has a base  10  on a bottom side thereof. A pair of left and right frames  11  is disposed on the base  10 . Y-axis rails  12  are formed on a top surface of the frames  11  in the longitudinal direction. Then, so as to straddle the Y-axis rails  12  on both the sides, a carriage  13  is supported movably in the longitudinal direction of the Y-axis rails  12 .  
         [0046]    The carriage  13  has a pair of stays  17 ,  18  before and after it. This constitutes the structure straddling the Y-axis rails  12  on both the sides. Also, the carriage  13  has a pair of X-axis rails  19  in a square direction in the Y-axis direction, and supports a mount head  20  movably in the X-axis direction by using the X-axis rails  19 .  
         [0047]    An suction nozzle  21  is downwardly disposed in the mount head  20  so that a component is absorbed by a tip of the nozzle  21 , as described later. A board recognition camera  22  is disposed on a bottom surface of the mount head  20  so that this board recognition camera  22  recognizes a circuit board  23  that is inserted into and fixed to a lower side of the carriage  13  from a side direction. Also, in the movement direction of the carriage  13  moved along the Y-axis rail  12 , a component recognition camera  26  is fixedly disposed on the lower side of the movement direction, so as to recognize an image of the component absorbed by the suction nozzle  21 .  
         [0048]    [0048]FIG. 3 is a block diagram showing a control system of such a component mounting. This control system has a controller  30  including a computer. The controller  30  controls an X-axis motor  31  for moving the mount head  20  in the X-axis direction, a Y-axis motor  32  for moving the carriage  13  in the Y-axis direction, a Z-axis motor  33  for moving the suction nozzle  21  in its height direction, namely, in the Z-axis direction, and an R-axis motor  36  for rotating the suction nozzle  21  with an axis line as a center. By the way, position information fetched by encoders (not shown) of those motors  31 ,  32 ,  33  and  36  is fed back to the controller  30 . Also, the controller  30  controls an electromagnetic valve  34  for controlling the exhaust and the suction of the suction nozzle  21 , and an electromagnetic valve  35  for controlling the supply and the exhaust of air to and from an air cylinder for controlling a drive of a feed lever of a later-described part cassette. Moreover, the board recognition camera  22  and the component recognition camera  26  are connected to the controller  30 .  
         [0049]    The component mounting apparatus shown in FIGS. 1, 2 has a plurality of, for example,  10  pieces of part cassettes  39  on the rear side thereof. It supplies the components at the condition that they are contained in tapes through those part cassettes  39 . The supplied components are absorbed by the suction nozzle  21  of the mount head  20 , one by one, and mounted on the circuit board  23 .  
         [0050]    The part cassette  39  has a base  40  made of aluminum die-cast, as shown in FIG. 4. A frame  41  formed by pressing and molding an aluminum plate is fixed to a portion of a back end of the base  40 . So, a component tape feed reel  43  is installed by using pins  42  protuberantly disposed so as to be horizontally extended on the side of this frame  41 . The feed reel  43  is pushed by a push arm  44 .  
         [0051]    The top surface of the base  40  serves as a guide plane  48 . The components are fed through this guide plane  48  from the feed reel  43 . An installation plate  49  is fixed to the side of the base  40 . A top tape take-up reel  51  is installed through a pin  50  to this installation plate  49 . A first feed lever  52  is rotatably installed on the side of the top tape take-up reel  51 . The rotation of the first feed lever  52  is converted into the rotational motion of the top tape take-up reel  51  through a ratchet nail  53 . This conversion enables the top tape to be reeled.  
         [0052]    An assistant plate  56  is installed above the guide plane  48  of the base  40  which is located on the side of the installation plate  49 . An assistant lever  58  is installed through a pin  57  by this assistant plate  56 .  
         [0053]    A cover  61  is installed through a pin  62  at a portion of a tip side of the base  40 , and a shutter  63  is slidably disposed on the back side of this cover  61 . So, a component pickup hole  64  is made before this shutter  63  so that the component packed in the form of the tape is taken out from this component pickup hole  64 .  
         [0054]    A second feed lever  65  is rotatably installed on a side of a front end of the base  40 . This feed lever  65  is linked through a linkage link  66  to the first feed lever  52 .  
         [0055]    The components fed by the above-mentioned part cassettes  39  are accommodated in concave portions  71  formed on a tape  70 , as shown in FIGS. 5, 6. Components  72  are covered by a top tape in the condition that each of the components  72  is accommodated in each corresponding concave portion  71 . Moreover, the components are fed in the wrapped state by the component tape feed reel  43 .  
         [0056]    The above-mentioned operation for mounting on the circuit board  23  the components  72  fed by the tape  70  will be schematically described below. When the electromagnetic valve  35  is switched in accordance with a command of the controller  30  shown in FIG. 3, an actuator (not shown) linked to the electromagnetic valve  35  is operated to accordingly operate the first feed lever  52  or the second feed lever  65  of the part cassette  39  shown in FIG. 4. By the way, the feed levers  52 ,  65  as the pair are linked to each other through the link  66 . Thus, the rotation of one feed lever enables the other feed lever to be rotated at the same time.  
         [0057]    The above-mentioned rotation of the feed levers  52 ,  65  causes an intermittently feeding mechanism for the tape  70  on the lower side of the cover  61  to be operated. Thus, the top tape is stripped. Then, when the tape  70  reeled by the top tape take-up reel  51  arrives at the position of the component pickup hole  64  of the base  40 , the component  72  in the concave portion  71  at that position faces to the component pickup hole  64 .  
         [0058]    The controller  30  in FIG. 3 controls so as to operate the Y-axis motor  32 , move the carriage  13  backward along the Y-axis rail  12 , and also move the mount head  20  in the X-axis direction along the X-axis rail  19  by using the X-axis motor  31 , and then move the suction nozzle  21  of the mount head  20  to a portion above the component draw position  64 .  
         [0059]    In a condition that the suction nozzle  21  is located on the component pickup hole  64  of the corresponding part cassette  39 , the controller  30  operates the Z-axis motor  33 . Accordingly, the suction nozzle  21  is lowered to then absorb the component  72  in the concave portion  71  of the tape  70 . By the way, at this time, vacuum suction is carried out in the suction nozzle  21  by switching the electronic circuit valve  34 . At this state, the Z-axis motor  33  is again operated in the opposite direction so that the suction nozzle  21  is moved upwardly in the Z-axis direction.  
         [0060]    After that, the controller  30  instructs the Y-axis motor  32  to move the carriage  13  forwardly along the Y-axis rail  12 , and further instructs the X-axis motor  31  to move the mount head  20  along the X-axis direction. Also, it instructs the R-axis motor  36  to rotate the suction nozzle  21  so that the component  72  is located in a normal orientation. Then, it instructs the suction nozzle  21  to be located above the component recognition camera  26 , and it recognizes the image of the component  72  absorbed by the suction nozzle  21 .  
         [0061]    After the completion of the image recognition of the component  72  absorbed by the suction nozzle  21 , the controller  30  instructs the Y-axis motor  32  to again move the carriage  13  to the front side in the Y-axis direction. Also, it instructs the X-axis motor  31  to move the mount head  20  in the X-axis direction. Then, the suction nozzle  21  is moved so as to be located at a position above a predetermined mount position of the circuit board  23  whose image is recognized by the board recognition camera  22  in advance. The suction nozzle  21  is rotated by the R-axis motor  36 , so as to adjust an angle of the component  72 . At this state, the Z-axis motor  33  is operated to lower the suction nozzle  21 . Accordingly, the component  72  absorbed at the predetermined position on the circuit board  23  by the suction nozzle  21  is mounted.  
         [0062]    The sequential repetition of such operations enables the various components respectively accommodated in the plurality of part cassettes  39  to be normally mounted at the respective mount positions. By the way, the circuit board  23  is accommodated and fixed between the pair of frames  11  from the side of the frames  11 . Then, if the mount of the predetermined components is completed, it is again taken out from between the frames  11 .  
         [0063]    The component mounting apparatus provided with the mount machines shown in FIGS. 1, 2 constitutes a unit for mounting chip components. It is designed such that the component  72  supplied at the condition at which it is accommodated in the concave portion  71  of the tape  70  shown in FIGS. 5, 6 is absorbed by the suction nozzle  21  of the mount head  20 , and the component image is recognized by the component recognition camera  26 , and it is mounted on the target circuit board  23  at the accurate position and posture. By the way, the component  72  is usually referred to as a tape type component. Accordingly, the components  72  are supplied in series at the condition that they are accommodated in the concave portions  71  composed of cavities, in the one-to-one relation, as shown in FIGS. 5, 6.  
         [0064]    The concave portions  71  are formed on the tape  70 , as mentioned above. When the first feed lever  52  or the second feed lever  65  of the part cassette  39  shown in FIG. 4 is rotated, the concave portions  71  are always located at the predetermined positions by feeding the concave portions  71  of the tape  70  at a constant interval. By the way, minute gap exists between the feed hole  73  made on the side of the concave portion  71  of the tape  70  so as to feed this tape  70  via the rotation of the feed lever  52  or  65  and the pin of the tape feed mechanism of the part cassette  39 . Also, a predetermined clearance is disposed between the component  72  and the concave portion  71  of the tape.  
         [0065]    Also, the mount machine shown in FIGS. 1, 2 employs the method in which the component supply device itself composed of the combination of the part cassettes  39  can be detached from this mount unit, in order to improve the operational performance when the component is replaced. Thus, there may be a possibility that the detachment of the part cassette  39  results in an installation error between it and this mount machine, and this installation error leads to the suction error. Also, when one part cassette  39  is replaced with another part cassette  39 , an error of a manufacturing accuracy is brought about.  
         [0066]    Such clearance, error, tolerance and the like cause the error to be brought about in the suction position with regard to the component  72  of the suction nozzle  21 . So, in this mount unit, the solution of the trouble is tried by carrying out the correction for the suction position with regard to the component  72  of the suction nozzle  21  on the basis of the error so that the substantial center of the component  72  is always absorbed and held by the suction nozzle  21 .  
         [0067]    This operation will be described below with reference to a flowchart shown in FIG. 8. An suction position is set on the basis of a design value or a simple indication under an assumption of a predetermined error. Then, a first component  72  is absorbed and held by the suction nozzle  21 . The absorbed and held component  72  is accurately mounted on the circuit board  23 . Thus, its component image is recognized by the component recognition camera  26  constituted by a fixed camera shown in FIGS. 1, 2. A position in a visual field of the camera shown in FIG. 7 for which the held position of the suction nozzle  21  is set at this time is already known. Thus, data for the mount is an offset amount of the absorbed component  72  with respect to the suction nozzle  21 . This data is used not only for the correction for the mount position with respect to the circuit board  23  but also for the correction for the suction position via the suction nozzle  21 .  
         [0068]    As its principle, the offset amount with respect to the absorbed component  72  of the suction nozzle  21  is added to the suction position of the component  72  via the suction nozzle  21 . Here, if the offset amount in its original state, namely, at 100%, is added to the suction position to then correct a next offset amount, this may result in an excessive susceptibility to a random error induced for each component  72 . Thus, in this case, an offset amount multiplied by a sensitivity coefficient “a” smaller than 1 is added to the suction position. This is given by the following equation:  
                 [         Xp           Yp         ]       n   +   1       =         [         Xp           Yp         ]     n     +     a        [         Xo           Yo         ]                 (   1   )                               
 
         [0069]    Here, (Xp, Yp) indicates a component suction position, and (Xo, Yo) indicates an offset amount at a center of the component  72  with respect to a center of the suction nozzle  21 . Also, “a” is a sensitivity coefficient of 0&lt;a≦1.  
         [0070]    By the way, if a target component  72  for the mount is already rotated to a mount angle and its component image is recognized by the component recognition camera  26 , it needs to be reversibly rotated by its angular recognition error and returned back prior to the above-mentioned calculation. This is because the machine shown in FIGS. 1, 2, when being rotated to mount the component  72  after absorbing it with the suction nozzle  21 , recognizes the component  72  with the component recognition camera  26  after the rotation. Thus, if the suction nozzle  21  is rotated, the recognized result need to be returned back to the original angle. Hence, if a rotation of θ degrees is applied to the suction nozzle  21  prior to the recognition of the component  72 , the above-mentioned equation is modified to be the following equation:  
                 [         Xp           Yp         ]       n   +   1       =         [         Xp           Yp         ]     n     +       a        (             cos                 θ                          sin                 θ                                -   sin                   θ                          cos                 θ                        )            [         Xo           Yo         ]                 (   2   )                               
 
         [0071]    In this equation, the coefficient including sin θ and cos θ in a second term on a right side is a coefficient to return the rotational amount back to the original value.  
         [0072]    Due to the introduction of the control operation for the correction as shown in FIG. 8, the suction nozzle  21  always repeats the operation for automatically keeping the component holding position at the optimal state. Accordingly, it is possible to suppress the suction trouble caused by the deviation between the center of the component  72  and the suction nozzle  21 , namely, the failure of the capture and the non-suction. Moreover, the value in which the offset amount is multiplied by the sensitivity coefficient “a” is added in this case. Thus, even if a particular component  72  is offset to an extreme position, it is not necessary to carry out the correction so that a next component is sensitively reactive to that case. Hence, the addition of the correction suitable for the deviation amount enables the mount operation of the stable repetition of the component  72 .  
         [0073]    Another embodiment will be described below with reference to FIGS.  9  to  11 . In a case where a concave portion  74  exists in a substantial center of a top surface constituting a surface to be absorbed of the component  72  as shown in FIG. 9, such a concave portion  74  disables the center of the component  72  to be absorbed by the suction nozzle  21 . Thus, in this case, as shown in FIG. 10, the peripheral portion other than the concave portion  74  of the component  72  is absorbed by the suction nozzle  21 . Hence, in this case, a correction may be added in which an offset amount at an suction position with respect to the center of the component  72  is considered in advance. That is, the correction is carried out in accordance with the following equation:  
                 [         Xp           Yp         ]       n   +   1       =         [         Xp           Yp         ]     n     +     [         Xn           Yn         ]     +     a        [         Xo           Yo         ]                 (   3   )                               
 
         [0074]    Here, (Xn, Yn) indicates the normal suction position of the suction nozzle  21  with respect to the center of the component  72 . The addition of such correction enables the correction for the case of the suction at the position when the suction nozzle  21  is deviated by a predetermined amount in a predetermined direction with respect to the center of the component  72 .  
         [0075]    As mentioned above, the present invention has been explained by using one embodiment. However, the present invention is not limited to the above-mentioned embodiment. Various modifications can be made thereto within the range of the technical spirit of the present invention included in this application.  
         [0076]    For example, the mount unit in the above-mentioned embodiment has the structure in which the CCD camera is used as the component recognition camera  26 . However, even a line sensor using an LED as the component recognition camera  26  can attain the same functions. Also, in addition to them, the component recognition can be attained by using a method of a non-contact sensor, an X-ray or the like. Here, the mount machine using the part cassettes  39  is indicated as a component feeder. However, it can be widely applied to a component mounting apparatus using a bulk feeder cassette, a stick type component supply cassette, or a tray type component feeder.