Patent Publication Number: US-2007094868-A1

Title: Electronic component mounting apparatus

Description:
CROSS-REFERENCE OF THE INVENTION  
      This application claims priority from Japanese Patent Application No. 2005-317304, the content of which is incorporated herein by reference in its entirety.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The invention relates to an electronic component mounting apparatus having a plurality of component feeding units feeding an electronic component to a component pickup position and a mounting head that has a suction nozzle picking an electronic component by suction from this component feeding unit and mounting this electronic component on a printed board and moves vertically, rotates, and moves in X and Y directions.  
      2. Description of the Related Art  
      This kind of electronic component mounting apparatus has been described, for example, the Japanese Patent Application Publication No. 2001-156498. For picking an electronic component fed from the component feeding unit by the suction nozzle, some of the apparatuses rotate the mounting head provided with the suction nozzle to adjust the nozzle at an angle in a θ direction where the electronic component is to be fed, and vertically move the mounting head to pick the electronic component up by suction. Between a rotation motor and a vertical movement motor of the mounting head, before the rotation motor of the mounting head is started, the operation pattern of the vertical movement motor, i.e., the start point of the vertical movement motor of the mounting head, that is the position the mounting head reaches by its rotation driven by the rotation motor, and the component feeding position of the feeding unit that is the target position of the mounting head moving for picking the electronic component by suction are set in a memory of a control device in advance. The current position of the mounting head during its rotation, the position of the mounting head during its movement in the X and Y directions, and the feeding state of the electronic component fed toward the feeding position by the component feeding unit are monitored by the control device. When the previously set start point and the current position of the suction head rotated by the rotation motor match, the mounting head reaches the component feeding position by moving in the X and Y directions, and further the electronic component is fed to the feeding position of the component feeding unit, the control device outputs a start signal to the vertical movement motor to start the vertical movement motor.  
      When an electronic component is to be picked up, the rotating position and the moving state in the X and Y directions of the mounting head are always monitored by the control device and the feeding state of the electronic component is monitored by the component feeding unit. At the time when all the conditions are satisfied, the control device outputs a start signal for the vertical movement motor to a drive circuit of that motor, and the drive circuit starts the vertical movement motor based on this start signal. Therefore, it takes time for the vertical movement motor to actually start driving from the time when the control device outputs the start signal for the vertical movement motor when all the conditions are satisfied. A mounting time per electronic component has not been reduced so far.  
     SUMMARY OF THE INVENTION  
      The invention is directed to reduction of a mounting time per electronic component by starting a vertical movement motor and so on as early as possible.  
      The invention provides an electronic component mounting apparatus, including: a plurality of component feeding units feeding an electronic component to a component pickup position; a mounting head having a suction nozzle picking an electronic component by suction from the component feeding unit and mounting the electronic component on a printed board; a rotation motor rotating the suction nozzle; a vertical movement motor vertically moving the suction nozzle; an X axis motor moving the mounting head in an X direction along a beam; a Y axis motor moving the beam in a Y direction perpendicular to a longitudinal direction of the beam; a control device outputting a start interlock signal for interlocking the vertical movement motor and outputting a start interlock canceling signal when judging that an interlock canceling condition is satisfied; and a motor control device starting the vertical movement motor based on the start interlock canceling signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a plan view of an electronic component mounting apparatus.  
       FIG. 2  is a front view of the electronic component mounting apparatus.  
       FIG. 3  is a right side view of the electronic component mounting apparatus.  
       FIG. 4  is a control block diagram of the electronic component mounting apparatus.  
       FIG. 5  is a longitudinal cross-sectional view of a front of a mounting head body holding a thin electronic component by suction.  
       FIG. 6  is a longitudinal cross-sectional view of a side of the mounting head body.  
       FIG. 7  is a plan view of a fixing support piece and a vertical movement support piece.  
       FIG. 8  is a schematic bottom view of the mounting head.  
       FIG. 9  is an enlarged longitudinal cross-sectional view of a front of a lower portion of the mounting head.  
       FIG. 10  is a view showing an operation screen displayed on a CRT.  
       FIG. 11  is a flowchart of detection by a line sensor unit.  
       FIG. 12  is a flowchart of detection by a component recognition camera.  
       FIG. 13  is a flow chart of picking an electronic component by suction. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      An embodiment of an electronic component mounting apparatus of the invention will be described with reference to the drawings.  FIG. 1  is a plan view of an electronic component mounting apparatus  1 ,  FIG. 2  is a front view of the electronic component mounting apparatus  1 , and  FIG. 3  is a right side view of the electronic component mounting apparatus  1 . A plurality of component feeding units  3  for feeding a variety of electronic components one by one to each of component feeding positions (component pickup positions) is attachably and detachably aligned and fixed on feeder bases  3 A,  3 B,  3 C, and  3 D on a base  2  in the apparatus  1 . A feed conveyer  4 , a positioning portion  5 , and a discharge conveyer  6  are provided between groups of the units  3  facing to each other. The feed conveyer  4  conveys a printed board P received from an upstream to the positioning portion  5 , an electronic component is mounted on the printed board P positioned by a positioning device (not shown) in the positioning portion  5 , and the printed board P is conveyed to the discharge conveyer  6 .  
      A numeral  8  designates a pair of beams extending in an X direction. Each of the beams  8  respectively moves in a Y direction above the printed board P on the positioning portion  5  or the component feeding positions (component pickup positions) of the component feeding units  3  as sliders  11  fixed to each of the beams  8  slide along a pair of left and right guides  10 , driven by each of linear motors  9  provided in the Y direction. Each of the linear motors  9  provided in the X direction has a pair of upper and lower stationary members  9 A fixed on the base  2  and a moving member  9 B fixed to a lower part of an attachment board  8 A provided on each end of the beam  8 .  
      Each of the beams  8  is provided with a mounting head body  7  which moves in a longitudinal direction, i.e., in the X direction along a guide  13  driven by the linear motor  14 . The linear motor  14  has a pair of front and back stationary members  14 A fixed to the beam  8  and a moving member  14 B provided on the mounting head body  7  and between the stationary members  14 A.  
      Each of the mounting head bodies  7  has a mounting head  16  having twelve suction nozzles  15  each fixed to and pulled down by each of twelve springs  12 . A board recognition camera  19  is provided on the mounting head  16  in each of the mounting head bodies  7  and takes an image of a positioning mark (not shown) on the printed board P positioned on the positioning portion  5 .  
      A vertical movement device for the mounting head  16  and the mounting head  16  will be described in detail with reference to  FIGS. 5 and 6 . A numeral  20  designates a board of the mounting head body  7  moving along the guide  13 , and a numeral  21  designates a beam side base fixed to this board  20 . A numeral  22  designates a mounting head side base fixed to upper and lower portions of the mounting head  16 ; A head vertical movement device  23  is provided between this mounting head side base  22  and the beam side base  21 .  
      The head vertical movement device  23  has a guide  24  guiding the mounting head  16  when the mounting head  16  vertically moves, a ball screw  25  attached to the beam side base  21 , a rotation motor (referred to as a head vertical movement motor, hereafter)  26  vertically moving the mounting head  16  by rotating the ball screw  25 , a vertical movement nut  27  engaged with the ball screw  25 , and a support body  28  attached to the head vertical movement motor  26  and rotatably supporting an upper portion of the ball screw  25 . The vertical movement nut  27  is fixed to the head side base  22 . Thus, rotation of the ball screw  25  by rotation of the head vertical movement motor  26  makes the vertical movement nut  27  vertically move, resulting in vertical movement of the mounting head  16 .  
      A numeral  30  designates a slip ring provided for communication between the mounting apparatus and the mounting head  16  and for power supply to a rotation motor of a nozzle support portion which will be described below. A numeral  31  designates a nozzle support body provided in a lower portion and supporting each of twelve nozzles  15  provided on a circumference thereof at predetermined intervals, which are vertically movable. A numeral  32  designates an outer cylinder in a lower portion, and a numeral  33  designates a nozzle rotation motor as a pulse motor for θ rotation provided between the outer cylinder  32  and the nozzle support body  31 . A rotor  34  of this nozzle rotation motor  33  is provided on an outer circumference surface of the nozzle support body  31 , being rotatable in a θ direction inside a stator  35  provided in the outer cylinder  32  together with the nozzle support body  31 .  
      A numeral  37  designates a line sensor unit for detecting presence or absence, an attached posture, and a lower end of the electronic component, protruding downward from a center of the head support body  31 . The line sensor unit  37  has a light emitting unit  45  and a light receiving unit  46 . The light emitting unit  45  is provided in a lower end of the support body  38  in the almost center position of the mounting head  16 , and has a light emitting element  42  such as an LED in an upper part of a cylindrical light emitting unit attachment body  41 , a lens  43  below the light emitting element  42 , and a reflector  44  having a conic reflective surface  44   a  provided below the lens  43 . A light receiving unit  46  is fixed to a bottom surface of the outer cylinder  32 , and has CCD elements as a plurality of light receiving elements for receiving light emitted from the light emitting element  42  through the reflector  44 .  
      This enables differentiating a case where the electronic component is picked up with a normal position as shown in  FIG. 5  from a case where the component is picked up with its wrong surface being attached to the suction nozzle, i.e., standing or slanting, since height of a lower end surface of the electronic component D can be detected by recognizing a border between the position receiving no light and the position receiving light in each of the CCD elements in each time when the nozzle support body  31  rotates after a pickup operation of the electronic component D is completed by the suction nozzle  15  provided on the mounting head  16  and selected for picking the component. In detail, after the suction nozzle  15  lowers, picks the electronic component D up from the component feeding unit  3  by suction, and rises up, the nozzle rotation motor  33  is driven to rotate the nozzle support body  31  and rotate the suction nozzle  15  holding the electronic component D by suction. When the electronic component D held by the suction nozzle  15  comes between the reflector  44  and the light receiving unit  46  during rotation of the suction nozzle  15 , presence or absence and an attached posture of the component can be detected by detecting height of the lower end surface of the electronic component D at plural positions. Although the detection is performed during rotation and movement of the nozzle support body  31  in this embodiment, alternatively the detection can be performed with the rotation being stopped when the electronic component D comes between the reflector  44  and the light receiving unit  46 .  
      In a case where the suction nozzle  15  does not hold the electronic component D by suction, light emitted from the light emitting element  42 , which should be shielded (by the held electronic component), is received by the light receiving unit  46 . Thus, a detection result is “absence” of the electronic component D, so that by an operation of a solenoid valve  82  as a vacuum valve switch effector, which will be described below, provided on a side of each of the nozzle axes  64 , a vacuum path is disconnected from a vacuum source to stop the vacuum suction, thereby preventing leakage. In a case where the electronic component is detected as being attached to the suction nozzle  15  at its wrong surface, i.e., with standing or slanting, the mounting head  16  and the suction nozzle  15  move to a position above an exhaust box  79 , drops the electronic component D therein, and performs a picking process of the electronic component D again.  
      Even in a case where the electronic component is detected as being attached normally, a lower end level (lower end position) of the electronic component D can be detected so that a CPU  90  controls and changes an amount of a lowering stroke of the suction nozzle  15  for mounting the component D on the printed board P, corresponding to the lower end level. This compensates dimensional variations of the components caused by different manufacturers and so on.  
      A numeral  50  designates a nozzle vertical movement device provided on the mounting head  6 . Description will be given on this nozzle vertical movement device, hereafter. A numeral  51  designates a motor for vertically moving a nozzle (referred to as a nozzle vertical movement motor, hereafter) attached to the head side base  22 , and a numeral  52  designates a ball screw connected with a rotation axis  511  of the nozzle vertical movement motor  51  through a connection member  59  and rotating driven by the nozzle vertical movement motor  51 , a numeral  53  designates a vertical movement body engaged with the ball screw  52  and vertically moving by rotation of the ball screw  52 , a numeral  55  designates a guide attached to the head side base  22  and guiding the vertical movement body  53  for vertical moving, and a numeral  56  designates a roller rotatably attached to a lower end of the vertical movement body  53 .  
      Furthermore, a numeral  57  designates a first cylinder where a center axis  60  of the mounting head  16  penetrates a center thereof, a roundel  58  formed on the first cylinder  57  is positioned on the roller  56 , the fist cylinder  57  being supported by the roller  56 . The first cylinder  57  is formed of a ball spline, for example, and pulled downward by a spring  61  of which a lower end is attached to an upper surface of the roundel  58 . This first cylinder  57  rotates by θ with θ rotation of a pulley which will be described below, and vertically moves together with a vertical movement of the vertical movement body  53  and a vertical movement of the roller  56 . A numeral  62  designates a nozzle support member fixed to a lower portion of the first cylinder  57  and rotates by θ with the first cylinder  57 . A support piece  63  is formed on a lower end of this nozzle support member  62 , horizontally lying in a circumference direction. This support piece (referred to as a vertical movement support piece)  63  vertically moves together with vertical movement of the first cylinder  57 . The lowering of the vertical movement support piece  63  makes a predetermined nozzle  15  among a plurality of nozzles lower.  
      In detail, a roller  65  is rotatably attached to an upper end of each of the nozzle axes  64  extending upward from each of the nozzles  15 . The roller  65  on the upper end of the nozzle axis  64  of the nozzle  15  selected by a nozzle selection device which will be described below lowers by lowering of the nozzle support member  62  and the vertical movement support piece  63  by lowering of the first cylinder  57 , the roller  65  being positioned on an upper surface of the vertical movement support piece  63 . In detail, when the vertical movement support piece  63  and the roller  65  lower to a position shown by the vertical movement support piece  63 A and the roller  65 A, for example, the predetermined nozzle  15  lowers with this lowering. Furthermore, by controlling a rotation amount of the nozzle vertical movement motor  51  and adjusting a height where the vertical movement body  53  should stop during lowering, the suction nozzle  15  can lower by a predetermined stroke.  
      A numeral  66  designates a third cylinder provided under the nozzle support member  62 , which is rotatable by θ. On an upper portion of this third cylinder  66 , a support piece (referred to as a fixing support piece, hereafter)  67 , which has a disk like shape, is formed at the same height as that of the vertical movement support piece  63  of the nozzle support member  62  before lowered. The fixing support piece  67  is formed with a notch  68  for the vertical movement support piece  63  as shown in  FIG. 7 . Each of the rollers  65  on the upper ends of the nozzle axes  64  of the nozzles  15  except the above-described nozzle  15  to be lowered is supported by the fixing support piece  67 . That is, the fixing support piece  67  has the notch  68  formed in a position of one of some-degree divided pieces thereof calculated by dividing the piece  67  equally into the same number of pieces as the number of the nozzles  15  in a circumference direction, for example, in a position of a 30-degree piece which is one of  12  divided pieces in this embodiment. The vertical movement support piece  63  of the nozzle support member  62  is positioned in this notch  68 .  
      A numeral  70  is a nozzle selection device provided on the mounting head  16 , a numeral  71  designates a motor for selecting a nozzle to be lowered (referred to as a nozzle selection motor, hereafter), a numeral  72  designates a first pulley fixed to a rotation axis  73  of the nozzle selection motor  71 , a numeral  74  designates a second pulley rotatably supported by the center axis  60 , a numeral  75  designates a belt stretched between the first pulley  72  and the second pulley  74 , and a numeral  76  designates a cylindrical rotator provided on an outside of the center axis  60 , extending downward from a center of the second pulley  74 . The spring  61  is provided between the second pulley  74  and the roundel  58  of the first cylinder  57 .  
      The first cylinder  57  is formed on an outside of outer circumference of the lower portion of the rotator  76 . By the function of the first cylinder  57  as a ball spline, the first cylinder  57  rotates with rotation of the second pulley  74  and rotation of the rotator  76 . Furthermore, the first cylinder  57  vertically moves with vertical movement of the vertical movement body  53  along the rotator  76 .  
      In detail, when the nozzle for picking and mounting the electronic component D is to be selected, the nozzle selection motor  71  rotates, so that the first cylinder  57  rotates through the first pulley  72 , the belt  75 , the second pulley  74 , and the rotator  76 . Then, the nozzle support member  62  connected with the first cylinder  57  rotates together with the third cylinder  66 , so that the vertical movement support piece  63  of the nozzle support member  62  comes to the nozzle axis  64  extending from the selected nozzle  15 . With this state, the nozzle vertical movement motor  51  rotates, and the vertical movement body  53  lowers corresponding to the thickness of the electronic component to be picked up and mounted, so that the first cylinder  57  and the nozzle support member  62  lower and thus the vertical movement support piece  63  lowers, thereby lowering only the selected nozzle  15  by a predetermined stroke corresponding to the thickness of the electronic component.  
      A numeral  80  is an air switch valve switchable in each of the nozzles  15 , being provided for each of the nozzles  15  at predetermined intervals in the circumference direction on the outer side of the nozzles. This air switch valve  80  has a case  81  provided in an upper portion thereof, and a solenoid valve  82  of which the upper portion is positioned inside this case  81  and electrical conduction is controlled by a signal from the CPU  90 . The solenoid valve  82  has a circular electromagnet  83  provided on an inner surface of the case  81 , a path switch body  85  provided with a cylindrical permanent magnet  84  corresponding to the electromagnet  83  in its upper portion and vertically moving inside the case  81  according to electrical conduction and electrical non-conduction through the electromagnet  83 , and so on. An air blow path (referred to as an air path, hereafter)  86 , a nozzle connection path  87 , and a vacuum leading path (referred to as a vacuum path, hereafter)  88  are formed on an outer circumference surface of the path switch body  85  in due order from upper to lower sides. Furthermore, the nozzle axis  64  has a nozzle axis path  100  connected with an inner path  151  of the nozzle  15  and the nozzle connection path  87 . By the vertical movement of the path switch body  85 , the connection of the nozzle path  100  switches to between the vacuum path  88  and the air path  86 .  
      In detail, when the path switch body  85  rises by electrical conduction through the electromagnet  83 , the vacuum path  88  and the nozzle connection path  87  are connected to each other, and the nozzle connection path  87  and the air path  86  are disconnected from each other. Therefore, the inner path  151  of the suction nozzle  15  is connected to a vacuum source (not shown) through the nozzle axis path  100 , the nozzle connection path  87 , and the vacuum path  88 , so that the suction nozzle  15  keeps vacuum suction of the electronic component. On the other hand, when the connection switch body  85  lowers by electrical non-conduction through the electromagnet  83 , the vacuum path  88  connected with the vacuum source and the nozzle connection path  87  are disconnected from each other, and the nozzle connection path  87  and the air path  86  are connected to each other. Therefore, the vacuum suction of the electronic component D by the suction nozzle  15  stops, and air from an air supply source is blown in the inner path  151  of the suction nozzle  15  through the air path  86 , the nozzle connection path  87 , and the nozzle axis path  100 .  
      In this manner, the connection of the suction nozzle  15  with the vacuum source and the air supply source can be switched by electrical conduction and electrical non-conduction of the air switch valve  80  provided for each of the suction nozzles  15 . Thus, the air switch valve  80  for the selected suction nozzle  15  can be switched independently.  
      A numeral  89  designates a component recognition camera. The component recognition camera  89  is provided on each of attachment boards  99  of the base  2  so that there are four cameras  83  in total each corresponding to each of the mounting heads  16 . The camera  89  sequentially takes images of all the electronic components D picked up by the suction nozzles  15  to detect an amount of shifting from a proper position of the electronic component D on the suction nozzle  15  in X and Y directions and at rotating angles. The camera  89  can also take images of the plurality of the electronic components D at the same time. Furthermore, the component recognition camera  89  can recognize whether or not the electronic component D is held by suction by the suction nozzle  15  by taking an image.  
      Next, description will be given with reference to a block diagram showing a control of the electronic component mounting apparatus  1  in  FIG. 4 . A numeral  90  designates a CPU (main control device) as a control portion for controlling the mounting apparatus  1 . The CPU  90  is connected with a RAM (random access memory)  92  and a ROM (read only memory)  93  through buses. The CPU  90  controls all operation for component mounting of the electronic component mounting apparatus  1  according to programs stored in the ROM  93  based on data stored in the RAM  92 . In detail, the CPU  90  controls the driving of the linear motors  9  and  14  through an interface  94 , a first motor controller (a motor control device)  110  and an amplifier  111 . The CPU  90  also controls the driving of the nozzle rotation motor  33  and the nozzle vertical movement motor  51  through the interface  94 , a second motor controller  112  (a motor control device) and an amplifier  113 . The CPU  90  also inputs the state of the component feeding unit  3 , for example, the component feeding state through the interface  94  and an I/O  114 . Furthermore, the CPU  90  controls the driving of the head vertical movement motor  26 , the nozzle selection motor  71 , the solenoid valve  82  and so on through the interface  94  and a drive circuit  95 .  
      The first motor controller  110  is provided with a CPU  115  controlling the driving of the start and so on of the linear motors  9  and  14  based on a signal sent from the CPU  90 , and a RAM  116  storing setting data sent from the CPU  90 . The second motor controller  112  is provided with a CPU  117  controlling the driving of the start and so on of the nozzle rotation motor  33  and the nozzle vertical movement motor  51  based on a signal sent from the CPU  90 , and a RAM  118  storing data sent from the CPU  90 , that will be described below.  
      The RAM  92  is stored with mounting data on component mounting which include data on a position in the X and Y directions (indicated by X and Y respectively) indicating the pickup position of an electronic component or the mounting position of an electronic component on a printed board and an angle (indicated by Z) indicating an angle for picking or mounting the electronic component, data on the alignment numbers of the component feeding units  3 , data on the movement of the nozzle rotation motor  33  to reach a target position by its rotation based on the angle of the component when the nozzle is selected and the component is picked or mounted, data on the movement of a DD axis (a rotation axis of a nozzle) such as the speed of this movement, data on the movement of an NL axis (a vertical movement axis of a nozzle) that is the data on the movement of the nozzle  15  to reach the target position by its lowering driven by the nozzle vertical movement motor  51  when the suction nozzle lowers for picking the component or mounting the component on the printed board, and so on in order of component mounting (in order of step number). Furthermore, the RAM  92  is stored with component disposition data which include the type of the electronic component (component ID), the alignment coordinates of the component feeding units  3 , and so on corresponding to the alignment numbers of the component feeding units  3 .  
      A numeral  91  designates a component recognition processing device connected with the CPU  90  through the interface  94 . In the component recognition processing device  91 , images taken and stored by the component recognition camera  89  and the board recognition camera  19  undergo recognition processing.  
      The images taken by the component recognition camera  89  and the board recognition camera  19  are displayed on the CRT  96  as a display device. The CRT  96  is provided with various touch panel switches  97  and an operator operates the touch panel switches  97  for various settings including settings for informing.  
      The touch panel switches  97  include a glass substrate which is coated with a transparent conductive film on its whole surface and printed with electrodes on its four edges. When an operator touches one of the touch panel switches  97  in a state where minimal electric currents flow on the surface of the touch panel switches  97 , current flows change at the four electrodes and coordinates of a touched position are calculated by a circuit board connected with the electrodes. If the calculated coordinates correspond to one of coordinates originally stored in the RAM  92 , which will be described below, as a switch for executing a certain operation, the operation is executed.  
      Under the structure described above, a screen as shown in  FIG. 10  is displayed on the CRT  96 , and then selection is made from the line sensor unit  37  only, the component recognition camera  89  only, and both the line sensor unit  37  and the component recognition camera  89 , for use for detecting whether or not the suction nozzle  15  still holds the electronic component after the mounting operation of the electronic component on the printed board P. Suppose that the line sensor unit  37  only is selected for the detection, first. An operator pushes a switch portion  100 A and then a decision switch  100 D to set the detection by the line sensor unit  37  only. The set content is stored in the RAM  92 , and the CPU  90  controls a detecting operation according to a program corresponding to the set content stored in the ROM  93 .  
      This setting can be performed on each group of the electronic components having a same type or in mounting order in the mounting data of electronic components.  
      Hereafter, the picking and mounting operation of the electronic component D by the electronic component mounting apparatus  1  will be described in detail.  
      First, the printed board P is conveyed from upstream to the positioning portion  5  through the feed conveyer  4 , and the positioning device starts a positioning operation.  
      Next, the CPU  90  forms pickup sequence data from the mounting data stored in the RAM  92 . That is, the CPU  90  reads out data from the mounting data, decides a picking-up procedure of the suction nozzles  15 , detects the last component feeding unit  3  which feeds the last electronic component D in a sequential picking-up process ( 12  components can be picked up for one mounting head  16  at maximum) and stores coordinates of a last pickup position of the component feeding unit  3  in the RAM  92 , detects coordinates of a first mounting position of the component D after completing the sequential picking-up process (a position stored in mounting data before alignment) and stores the coordinates in the RAM  92 .  
      Then, the pickup operation of the electronic components D is performed.  
      In detail, the suction nozzles  15  corresponding to types of the electronic components pick up the electronic components to be mounted from the predetermined component feeding units  3  according to the mounting data and so on stored in the RAM  92  where a position of an X abscissa and a Y ordinate on the printed board to be mounted with the component, a position at a rotation angle around a vertical axis, an alignment number and so on are specified.  
      First, each of the predetermined component feeding units  3  is driven to start feeding the electronic component to the component pickup position, and the head vertical movement motor  26  rotates based on a signal outputted from the CPU  90  through the interface  94  and the drive circuit  95  to lower the mounting head  16  to a predetermined height along the guide  24 .  
      Hereafter, detail description will be given on interlock control for starting the nozzle vertical movement motor  51 , i.e., for starting the NL axis as the vertical movement axis of the suction nozzle  15  by the CPU  90  and the CPU  117  (control of other-axis dependent start), based on a flow chart shown in  FIG. 13 . The term “interlock” is used hereinafter to mean halting the operation of the nozzle vertical movement motor  51 , thereby stopping the vertical descent of the suction nozzle  15 .  
      First, data on a position in X and Y directions (indicated by X and Y respectively) indicating the pickup position of an electronic component to be picked and an angle (indicated by Z) indicating an angle for picking the component, data on the movement of the nozzle rotation motor  33  to reach a target position by its rotation based on the angle of the component when the nozzle is selected and the component is picked up, and data on the movement of the DD axis (the rotation axis of the nozzle) such as the speed of this movement are outputted from the CPU  90  to the first motor controller  110 , as the setting data, and stored in the RAM  116 .  
      Furthermore, data on the movement of the NL axis (the vertical movement axis of the nozzle) that are the data on the movement of the nozzle  15  to reach a target position by its lowering driven by the nozzle vertical movement motor  51  in order to pick the component are outputted from the CPU  90  to the second motor controller  112 , as the setting data, and stored in the RAM  118 .  
      Furthermore, data on the position of the nozzle rotation motor  33  (DD axis positional data: DDnL) that is a condition for starting the nozzle vertical movement motor  51  (for starting the NL axis) are outputted from the CPU  90  to the second motor controller  112 , as the setting data, and stored in the RAM  118 .  
      Furthermore, an ON signal (start interlock signal) for the interlock of the start of the nozzle vertical movement motor  51  depending on the position of the suction nozzle  15  on the X and Y axes and the feeding state of the electronic component on the component feeding unit  3  is outputted from the CPU  90  to the second motor controller  112 . The second motor controller  112  inputted with the ON signal for the start interlock of the nozzle vertical movement motor  51  stores this in the RAM  118 .  
      Then, for the pickup operation, by the linear motors  9  and  14  controlled by the CPU  90 , the suction nozzle  15  of the mounting head  16  in each of the mounting head bodies  7  moves toward the position above the first electronic component on the component feeding unit  3  which has the electronic components to be mounted. Each of the head bodies  7  moves in the Y direction by moving of the beam  8  along the pair of the guides  10  driven by the linear motor  9  and in the X direction along the guides  13  driven by the linear motor  14 , both the linear motors  9  and  14  being driven by the drive circuit  95 .  
      Since the suction nozzle  15  for picking the electronic component first (referred to as a first suction nozzle, hereafter) is on a position shifted from a pickup position, i.e., from a pickup position  101  (set this position as 0 degree) shown in  FIG. 8  which is a schematic bottom view of the mounting head  16 , the CPU  90  outputs a drive signal (ON signal) to the second motor controller  112  in order to move the suction nozzle  15  to the pickup position  101  shown in  FIG. 8  (in order to start the DD axis for the other axis start). The second motor controller  112  inputted with this signal judges that it receives a start command for the nozzle rotation motor  33  (a command to start the DD axis for the other axis start) (turns ON) and outputs a drive signal through the amplifier  113 , and the nozzle rotation motor  33  starts and rotates (the DD axis starts for the other axis start). By the drive of the nozzle rotation motor  33 , the nozzle support body  31  of the mounting head  16  rotates by θ around the center axis  60  (DD axis).  
      During the nozzle support body  31  of the mounting head  16  is rotating by θ around the center axis  60  by the drive of the nozzle rotation motor  33 , the CPU  117  judges whether or not the nozzle rotation motor  33  passes the position of the nozzle rotation motor  33  (DD axis positional data: DDnL) that is the condition for starting the nozzle vertical movement motor  51  (for starting the NL axis) stored in the RAM  118 .  
      When the CPU  117  judges that the nozzle rotation motor  33  passes the position of the nozzle rotation motor  33  that is the condition for starting the nozzle vertical movement motor  51  (for starting the NL axis), i.e., that the roller  65  is already placed on the vertical movement support piece  63  and passes the above-mentioned position based on the rotation angle of the nozzle support body  31  and the angle of the side edge of the vertical movement support piece  63  (the position shifted by 15 degrees from the center of the vertical movement support piece), the CPU  117  judges whether or not the start interlock of the nozzle vertical movement motor  51 , i.e. all the start interlocks of the nozzle vertical movement axis turn off.  
      Then, when the suction nozzle  15  of the mounting head  16  of the mounting head body  7  already completes the movement to above the first electronic component on the component feeding unit  3  having the electronic components to be mounted by the linear motors  9  and  14  controlled by the CPU  90 , the CPU  90  judges that the condition for canceling the interlock where the suction nozzle  15  is to complete the movement in the X and Y directions is satisfied, and outputs a signal indicating the satisfaction of the canceling condition to the second motor controller  112 . The second motor controller  112  stores the data on the satisfaction of the canceling condition in the RAM  118 . Furthermore, when the CPU  90  judges that the feeding of the electronic component is completed based on the data on the completion of feeding the electronic component to the feeding position, that is sent from the component feeding unit  3  to the CPU through the I/O  114  and the interface  94 , the CPU  90  judges that the condition for canceling the interlock where the electronic component is to be fed on the electronic component feeding unit  3  is satisfied, and outputs a signal indicating the satisfaction of the canceling condition to the second motor controller  112 . Then, the second motor controller  112  stores this data on the satisfaction of the canceling condition in the RAM  118 .  
      The CPU  117  of the second motor controller  112  that receives the signals indicating the satisfaction of the canceling conditions about the movement of the suction nozzle  15  in the X and Y directions and the feeding of the electronic component on the electronic feeding unit  3  immediately outputs a start signal to the nozzle vertical movement motor  51  based on the data of the satisfaction of the canceling conditions stored in the RAM  118 .  
      The nozzle vertical movement motor  51  inputted with the start signal rotates in the direction of lowering the first suction nozzle  15 , the vertical movement body  53  and the vertical movement support piece  63  lower by the rotation of the ball screw  52 , and the first suction nozzle  15  lowers toward the predetermined height, i.e. the previously set height suitable for picking the electronic component from the feeding unit  3 . That is, by the θ rotation of the nozzle support body  31  and the lowering of the vertical movement support piece  63 , the first suction nozzle  15  rotates and lowers simultaneously, the roller  65  reaches the center of the vertical movement support piece  63 , and the first suction nozzle  15  reaches the pickup position  101  and lowers to the height suitable for picking the electronic component simultaneously.  
      In this manner, since the first suction nozzle  15  starts lowering during the first suction nozzle  15  is rotating toward the pickup position  101  and the rotation and lowering of the first suction nozzle  15  toward the pickup position  101  are performed simultaneously, the time for the pickup operation of the electronic component D can be reduced.  
      As described above, the data on the movement pattern of the nozzle vertical movement motor  51 , for example, the data on the vertical movement quantity and the velocity of the suction nozzle  15  is sent from the CPU  90  and stored in the RAM  118 , the interlock for the start of the nozzle vertical movement motor  51  is turned ON, and then the CPU  117  of the second motor controller  112  immediately outputs a start signal to the nozzle vertical movement motor  51  based on the satisfaction of the interlock canceling condition where the movement of the suction nozzle  15  in the X and Y directions is to be completed and the satisfaction of the interlock canceling condition where the electronic component is to be fed on the electronic component feeding unit  3 . Namely, the second motor controller  112  outputs the start signal to the nozzle vertical movement motor  51  based on the satisfaction of all interlock canceling conditions regarding to the nozzle vertical movement motor  51 .  
      Therefore, the start signal can be sent to the nozzle vertical movement motor  51  earlier than the conventional case where the CPU  90  sends a start signal to the nozzle vertical movement motor  51  through a motor drive circuit based on its judgment of the completion of the movement of the suction nozzle  15  in the X and Y directions and the completion of the feeding of the electronic component on the electronic component feeding unit  3 . As a result of this, the time for mounting the electronic component on the printed board can be reduced.  
      In the above operation, the CPU  90  simultaneously outputs a signal for moving the suction nozzle  15  to the pickup position  101  shown in  FIG. 8  that is the pickup position and a signal for placing the nozzle selection motor  71  in a position corresponding to the first suction nozzle  15  based on the signal from the CPU  90 . Therefore, driven by the nozzle rotation motor  33 , the nozzle support body  31  of the mounting head  16  rotates around the center axis  60  by θ, and the rotation of the nozzle selection motor  71  is transmitted to the nozzle support member  62  through the first pulley  70 , the belt  75 , the second pulley  74 , and the first cylinder  57  and the rotation of the nozzle support member  62  rotates the vertical movement support piece  63  to reach the position corresponding to the first suction nozzle  15  for the vertical movement.  
      Since the first suction nozzle  15  does not reach the pickup position  101  yet at this time, the nozzle support body  31  continues the θ rotation around the center axis  60 . The CPU  90  outputs a signal to rotate the vertical movement support piece  63  and keep it on the position corresponding to the first suction nozzle  15 , and by the rotation of the nozzle support member  62  the vertical movement support piece  63  rotates together with the θ rotation of the nozzle support body  31 .  
      Then, based on the start signal to the nozzle vertical movement motor  51 , the nozzle vertical movement motor  51  rotates in a direction of lowering the first suction nozzle  15 , the rotation of the ball screw  52  makes the vertical movement body  53  and the vertical movement support piece  63  lower, and the first suction nozzle  15  lowers toward the predetermined height, i.e., the height suitable for picking the electronic component from the predetermined feeding unit  3 . That is, by the θ rotation of the nozzle support body  31  and the lowering of the vertical movement support piece  63 , the first suction nozzle  15  rotates and lowers simultaneously to reach the pickup position  101  and lower to the height suitable for picking the electronic component simultaneously.  
      In this manner, the first suction nozzle  15  starts lowering at the time when the first suction nozzle  15  is on the position shifted from the pickup position  101  by 15 degrees or more during it is rotating toward the pickup position  101 , and the rotation and lowering of the first suction nozzle  15  toward the pickup position  101  are performed simultaneously, so that the start time of lowering the first suction nozzle  15  can be earlier and also the time for the pickup operation of the electronic component D can be reduced more.  
      When the first suction nozzle  15  reaches the pickup position  101  and lowers to the height suitable for picking the electronic component simultaneously as described above, the solenoid valve  82  corresponding to the first suction nozzle  15  rises by electrical conduction based on a signal from the CPU  90 , and the first suction nozzle  15  is connected to the vacuum source through the nozzle connection path  87  and the solenoid valve  82 , so that the first suction nozzle  15  picks and holds the electronic component D by suction.  
      When the pickup operation of the electronic component by the first suction nozzle  15  is completed as described above, the CPU  90  outputs a signal to the nozzle vertical movement motor  51  through the second motor controller  112 , the nozzle vertical movement motor  51  rotates to a rising direction of the first suction nozzle  15  based on this signal, and the vertical movement body  53  rises to the predetermined height, i.e., the height before its lowering by the rotation of the ball screw  52 .  
      Then, the CPU  90  simultaneously outputs a signal to the nozzle vertical movement motor  51  and outputs a signal to pick an electronic component up by a second suction nozzle  15  next to the first suction nozzle  15 .  
      Hereafter, description will be given on the detection of presence or absence and an attached posture of the electronic component by the line sensor unit  37 , which follows the pickup operation of the electronic component by each of the suction nozzles  15 , with reference to  FIG. 8 .  
      The light receiving unit  46  of the line sensor unit  37  is provided in a position shifted by 45 degrees from the pickup position  101  shown in  FIG. 8 , for example. When the suction nozzle  15  holding the electronic component by suction passes a detection position  102  shown in  FIG. 8  by intermittent rotation of the nozzle support body  31  in a direction shown by an arrow, the detection of presence or absence and an attached posture of the electronic component is performed at a lower end of the suction nozzle  15  by the line sensor unit  37  as described above.  
      In a case where the electronic component is detected as being attached to the suction nozzle  15  at its wrong surface, i.e., with standing or slanting, the mounting head  16  and the suction nozzle  15  move to a position above an exhaust box  79 , drops the electronic component D therein, and performs a picking process of the electronic component D again. In a case where the electronic component is detected as being attached normally, the vacuum suction is kept and a lower end level (lower end position) of the electronic component D can be detected, so that the CPU  90  controls the nozzle vertical movement motor  51  so as to change an amount of a lowering stroke of the suction nozzle  15  for mounting the component D on the printed board P corresponding to the lower end level. This can compensate dimensional variations of the components caused by different manufacturers and on.  
      By controlling the drive of the nozzle vertical movement motor  51 , the ball screw  52  is rotated by predetermined angles to lower the vertical movement body  53 , and then the vertical movement support piece  63  lowers, thereby lowering the suction nozzle  15  by a predetermined stroke for mounting the electronic component D.  
      At the time when a last suction nozzle, for example, a twelfth suction nozzle  15  among the twelve suction nozzles  15  picks the electronic component by suction, this twelfth suction nozzle  15  is positioned in the pickup position  101  and the previous eleventh suction nozzle is positioned in a stop position  103  next to the pickup position  101 . Therefore, the CPU  90  outputs a signal to the nozzle rotation motor  33  to intermittently rotate the nozzle support body  31  by 30 degrees two times. Then, first the electronic component held by the eleventh suction nozzle  15  passes the detection position  102 , and the detection of presence or absence and an attached posture of the electronic component is performed by the line sensor unit  37 . Then, the electronic component held by the twelfth suction nozzle  15  passes the detection position  102 , and the detection of presence or absence and an attached posture of the electronic component is performed by the line sensor unit  37  similarly, thereby completing the detection of presence or absence and an attached posture of all the electronic components held by the suction nozzles  15 .  
      When the pickup operation of the electronic component by each of the suction nozzles  15  and the detection of presence or absence and an attached posture of the electronic component on each of the suction nozzles  15  are completed, the CPU  90  forms a mounting sequence data. In a case where the electronic component held by each of the suction nozzles  15  is thick, for example, the CPU  90  outputs a signal to raise the mounting head  16 , i.e. the mounting head body  7  so as to position the electronic component within a focus range of the component recognition camera  89  when the component recognition camera  89  performs component recognition processing. Based on this signal, the head vertical movement motor  26  rotates in a reverse direction to the direction for lowering. As a result, by actions of the ball screw  25  and the vertical movement nut  28 , the mounting head body  7  starts rising to a predetermined height, i.e. a height where the electronic component can be positioned within the focus range of the component recognition camera  89 .  
      In a case where the electronic component held by each of the suction nozzles  15  is thin, for example, and the electronic component can be positioned within the focus range of the component recognition camera  89  when each of the suction nozzles  15  of the nozzle support body  31  rises, the raising operation of the mounting head body  7  is not performed.  
      Accordingly, in the electronic component mounting apparatus  1 , the height where the suction nozzle  15  picks the electronic component can be adjusted not only by the vertical movement of the suction nozzle  15  by the nozzle support body  31  but also by the vertical movement of the mounting head body  7  by the operation of the head vertical movement device  23 , so that an adjusting range can be increased. This can increase a range of the electronic components to be picked up by the suction nozzle  15  of the mounting head  7  and mounted on the printed board.  
      At the same time when the raising operation starts in a case where the raising operation is performed, or after the set last suction nozzle  15  picks the electronic component in a case where the raising operation is not performed, the CPU  90  outputs a signal so that the mounting head  16  passes above the component recognition camera  89  and moves to a position of mounting coordinates on the printed board P positioned by the positioning portion  5 . Based on the signal from the CPU  90 , the linear motors  9  and  14  are controlled, and each of the mounting head bodies  7  moves in the Y direction by moving of the beam  8  along the pair of the guides  10  driven by the linear motor  9  and in the X direction along the guides  13  driven by the linear motor  14 , both the linear motors  9  and  14  being driven by the drive circuit  95 .  
      During the movement of the head body  7 , the mounting head  16  passes above the component recognition cameras  89 , and the component recognition cameras  89  simultaneously take and store images of all the electronic components D picked up by the suction nozzles  15  of the mounting head  16  by “on the fly recognition without stopping of the beam  8 ”. Then, the component recognition processing device  91  starts a component recognition process.  
      After a recognition result for the first component to be mounted is calculated by the component recognition processing device  91 , the CPU detects whether the suction nozzle  15  is positioned on a first mounting position (a position in mounting data before alignment of a pickup position) which is set as the coordinate value of the moving target position. If positioned, the CPU resets the coordinate value into a coordinate value of a moving target position calculated with the recognition (alignment) result and moves the beam  8  for positioning the suction nozzle  15  on a position of the reset target value. If not positioned, the set coordinate value of the moving target position is dynamically changed to the coordinate value calculated with the recognition (alignment) result.  
      Furthermore, based on the recognition result of the component recognition processing device  91 , the CPU  90  calculates a pickup angle of the electronic component on each of the suction nozzles  15 . Then, the CPU  90  compares a calculation result and a mounting angle in the mounting data stored in the RAM  92 . In a case where there is a difference between the calculated pickup angle and the mounting angle, the CPU  90  outputs a signal to correct the pickup angle to the mounting angle, to the nozzle rotation motor  33 . Then, the nozzle rotation motor  33  starts rotating during the mounting head body  7  is moving toward above the printed board, and this rotation makes the pickup angle of the electronic component on the suction nozzle corrected to the mounting angle.  
      The mounting head body  7  continues its movement even after passing above the component recognition camera  89 . In a case where the mounting head body  7  rises as described above, the CPU  90  outputs a signal to lower the mounting head body  7  during the movement. Then, the head vertical movement motor  26  rotates based on this signal, and by the rotation of the ball screw  25  the mounting head body  7  lowers to a height where the mounting head body  7  has been before it rises and reaches above the printed board. Then, the first electronic component D among the electronic components D is mounted on the printed board D.  
      Hereafter, description will be given on the mounting operation of the electronic component on the printed board by the suction nozzle  15 . In the following description, the order of suction nozzles for mounting is the same as those for picking described above.  
      In the mounting operation, the first electronic component D held by suction by the first suction nozzle reaches the position of mounting coordinates by the movement of the mounting head body  7 , and the first electronic component D is mounted on the printed board P by lowering the suction nozzle  15  by a predetermined stroke corresponding to the thickness of the electronic component D and the detection value of the lower end level of the electronic component D by the line sensor unit  37 .  
      In this mounting operation, the CPU  90  outputs a signal to lower the suction nozzle  15  in the similar manner to the case of the pickup operation of the electronic component described above. Based on this signal, the nozzle vertical movement motor  51  rotates in the direction for lowering the first suction nozzle  15  and the ball screw  52  rotates, and thus the vertical movement body  53  lowers corresponding to the thickness of the electronic component D and the detection value of the lower end level of the electronic component D detected by the line sensor unit  37 , so that the suction nozzle  15  lowers by a predetermined stroke and mounts the electronic component D on the printed board P.  
      When the suction nozzle  15  lowers, the solenoid valve  82  corresponding to the first suction nozzle  15  lowers by switching from electrical conduction to electrical non-conduction based on the signal from the CPU  90  and disconnects the first suction nozzle  15  from the vacuum source, so that the first suction nozzle  15  stops the vacuum suction operation. Then, air from the air supply source is blown in the inner path  151  of the first suction nozzle  15  through the air path  86  and the nozzle connection path  87 .  
      The CPU  90  calculates next mounting operation of the electronic component D and repeats the mounting operation until all the picked electronic components D are mounted. In detail, the CPU  90  receives a recognition result calculated by the component recognition processing device  91 , calculates a coordinate value of a moving target position in X, Y, and θ. Then, the CPU  90  drives the linear motor  9  to move the beam  8  in the Y direction to a target coordinate value calculated with the recognition result, drives the linear motor  14  to move the mounting head  16  in the X direction, drives the nozzle rotation motor  33  to rotate the nozzle support body  31  by θ, and rotates the suction nozzle  15 . The CPU  90  also rotates the nozzle vertical movement motor  51 , lowers the suction nozzle  15  by a predetermined stroke corresponding to the thickness of the component D, mounts the electronic component D on the printed board P, and then raises the suction nozzle  15  up. The CPU repeats this operation until all the electronic components D picked up by the suction nozzles  15  of the mounting head  16  are mounted on the printed board.  
      When the electronic component is mounted as described above, in a case where the mounting angle does not differ in each of the mounting operations, the nozzle support body  31  rotates by a predetermined angle, i.e. by 30 degrees in each time when the mounting operation is completed, so that the suction nozzles  15  are sequentially positioned at a predetermined angle, that is, in the same position as the pickup position  101  shown in  FIG. 8 , and the vertical movement of the suction nozzle  15  is performed in this position. On the other hand, in a case where the pickup angle of the electronic component on the suction nozzle  15  differs from the mounting angle of the electronic component in the electronic component mounting operation, or in a case where the pickup angle is shifted from the set mounting angle by recognizing the electronic component by the component recognition camera  89 , the nozzle support body  31  is rotated by a shifting amount from the predetermined angle calculated from a relation between the pickup angle of the component on the suction nozzle  15  and the mounting angle. Furthermore, in a case where the position of the suction nozzle  15  is shifted from the pickup position  101 , the CPU  90  outputs a signal to the nozzle selection motor  71  corresponding to a shifting amount of angle. Therefore, the vertical movement support piece  63  rotates by the rotation of the nozzle support body  31  when the component is to be mounted, and stops at a position corresponding to the suction nozzle  15  to be vertically moved. The suction nozzle  15  vertically moves in this position.  
      In detail, in a case where the pickup angle of the electronic component held by the suction nozzle  15  by suction differs from the mounting angle and thus the nozzle support body  31  is rotated, the nozzle selection motor  71  is rotated according to the rotation of the nozzle support body  31 , and then the vertical movement support piece  63  is rotated and comes to the position corresponding to the suction nozzle  15  to be vertically moved. Thus, by vertically moving the suction nozzle  15 , the electronic component can be mounted on the printed board without fail, thereby improving accuracy in the mounting operation.  
      Although the description of the pickup and the mounting of the electronic component D is given on the picking and mounting operation by one mounting head body  7  among four mounting head bodies  7  provided in the electronic component mounting apparatus  1 , other mounting head bodies  7  also perform the picking and mounting operations of the electronic components similarly.  
      Then, the CPU  90  checks whether or not the brought-back component checking function is set. When the brought-back component checking function is not set, that is, the RAM  92  does not have a setting content of the brought-back component checking function, the electronic component pickup operation according to the next mounting data, which is described above, will be performed.  
      Here, when the RAM  92  has the setting content of the brought-back component checking function, the CPU  90  checks whether or not a component checking function by the line sensor unit  37  is set. When the RAM  92  does not have a setting content of the component checking function by the line sensor unit  37 , the electronic component pickup operation according to the next mounting data, which is described above, will be performed. When the RAM  92  has the setting content of the component checking function by the line sensor unit  37 , the line sensor unit  37  performs detection of presence or absence of the electronic component by rotating the nozzle support body  31  as described above while the suction nozzle  15  of the mounting head  16  is moving to each of the component feeding units  3  storing the electronic component for next mounting.  
      When a result of the detection of presence or absence of the electronic component performed by the line sensor unit  37  is “absence”, the pickup operation of the electronic component for next mounting starts. When the result is “presence”, the CPU  90  checks whether or not the RAM  92  has a setting content of an error stop function. When the RAM  92  has the setting content of the error stop function, the CPU  90  controls the electronic component mounting apparatus  1  to stop the operation. When the RAM  92  does not have the setting content of the error stop function, the CPU  90  controls the suction nozzle  15  to move to a position above the exhaust box  79  and perform a discharging operation of the electronic component D.  
      After the discharging operation, the CPU  90  checks whether or not a setting content of a nozzle skip function is stored in the RAM  92 . When the nozzle skip function is not stored in the RAM  92 , a pickup operation of a next electronic component to be picked up starts. When the nozzle skip function is stored in the RAM  92 , a skip process is performed to the appropriate suction nozzle  15  and the pickup operation of the next electronic component to be picked up starts.  
      There are twelve suction nozzles  15  attached to the mounting head  16  and some of the suction nozzles  15  are of same type. In the skip process, the CPU  90  controls so that the suction nozzle  15  which brings back the electronic component is not used but the other suction nozzle  15  of same type is used instead.  
      When all the electronic components D specified in the mounting data are not mounted on the printed board P, the pickup sequence data is formed again as described above, and the pickup operation, the component recognition processing, and the mounting operation of the electronic components D are performed. When all the electronic components D specified in the mounting data are mounted on the printed board P, the beam  8  is returned to an original position, and the printed board P completing component mounting is mounted on the discharging conveyer  6 , completing the mounting operation.  
      In the next case, the screen as shown in  FIG. 10  is displayed on the CRT  96 , and then the component recognition camera  89  only is selected for use for detecting whether or not the suction nozzle  15  still holds the electronic component after the component mounting operation on the printed board P. An operator pushes a switch portion  100 B and then the decision switch  100 D to set the detection by the component recognition camera  89  only. The CPU then controls a detecting operation according to a program corresponding to the set content stored in the ROM  93 .  
      That is, control shown in a flow chart shown in  FIG. 12  is performed. In this control, detection processing of the brought-back electronic component as shown in  FIG. 11  is performed by the component recognition camera  89  and the component recognition processing device  91  only, instead of by the line sensor unit  37 .  
      In the explanation below, some features of the mounting operation that have been already explained with respect to the line sensor unit only detection will be omitted. First, the printed board P is conveyed to the positioning portion  5  and positioned there, and the CPU  90  forms pickup sequence data from the mounting data stored in the RAM  92 . Then, the cameras  89  can simultaneously take images of all the electronic components picked up by the suction nozzles  15  of the mounting head  16  by “on the fly recognition without stopping of the beam  8 ” at the time when the beam  8  is moving from the last pickup position to the first mounting position which will be described below.  
      Then, the suction nozzle  15  corresponding to type of the electronic component picks up the electronic component to be mounted from the predetermined component feeding unit  3  according to the mounting data and so on. After picking up the electronic component D, the suction nozzle  15  rises up by the rotation of the nozzle vertical movement motor  51 , and the nozzle rotation motor  33  is driven to rotate the nozzle support body  31  and the suction nozzle  15 . The picked electronic component D is positioned between the reflector  44  and the light receiving unit  46  during this rotation, so that detection of presence or absence and an attached posture of the electronic component D is performed by the line sensor unit  37 .  
      When the electronic component D is detected as being attached normally, while keeping vacuum suction, a lower end level of the electronic component D can be detected so that the CPU  90  controls the nozzle vertical movement motor  51  to change an amount of a lowering stroke of the suction nozzle  15  for mounting the component D on the printed board P corresponding to the lower end level. This compensates dimensional variations of the components caused by different manufacturers and so on.  
      After that, multiple picking (sequential pickup of the components as much as possible) is performed, similarly. When completing this multiple pickup operation, the CPU  90  forms mounting sequence data and moves the beam  8  and the mounting head body  7  to a first mounting position where the component D is mounted on the printed board P first.  
      Then, when the CPU  90  detects timing for the component recognition cameras  89  to take images, the CPU makes the cameras  89  simultaneously take and store images of all the electronic components D picked up by the suction nozzles  15  of the mounting head  16  by “on the fly recognition without stopping of the beam  8 ” while the beam  8  is moving from the last pickup position to the first mounting position. Then, the component recognition processing device  91  starts a component recognition process.  
      When moving of the beam  8  is completed, the first electronic component D among the components D sequentially picked up is mounted on the printed board P. The CPU  90  calculates a next mounting operation of the other electronic component D, and repeats the mounting operation until all the picked electronic components D are mounted.  
      Then, the CPU  90  checks whether or not the brought-back component checking function is set. When the brought-back component checking function is not set, that is, the RAM  92  does not have a setting content of the brought-back component checking function, the electronic component pickup operation according to the next mounting data, which is described above, will be performed.  
      When the RAM  92  has the setting content of the brought-back component checking function, the CPU  90  checks whether or not a component checking function by the component recognition camera  89  and the component recognition processing device  91  is set. When the RAM  92  does not have a setting content of the component checking function by the component recognition camera  89  and the component recognition processing device  91 , the electronic component pickup operation according to the next mounting data, which is described above, will be performed. When the RAM  92  has the setting content of the component checking function by the component recognition camera  89  and the component recognition processing device  91 , the component recognition camera  89  takes an image and the component recognition processing device  91  performs recognition processing based on the image taken to perform the detection of presence or absence of the electronic component while the suction nozzle  15  of the mounting head  16  is moving to the component feeding unit  3  storing the electronic component for next mounting.  
      When a result of the detection of presence or absence of the electronic component D performed by the component recognition camera  89  and the component recognition processing device  91  is “absence”, the pickup operation of the electronic component for next mounting starts. On the contrary, when the result is “presence”, the CPU  90  checks whether or not the RAM  92  has the setting content of the error stop function. When the RAM  92  has the setting content of the error stop function, the CPU  90  controls the electronic component mounting apparatus  1  to stop the operation. When the RAM  92  does not have the setting content of the error stop function, the CPU  90  controls the suction nozzle  15  to move to a position above the exhaust box  79  and perform a discharging operation of the electronic component D.  
      After the discharging operation, the CPU  90  checks whether or not the setting content of the nozzle skip function is stored in the RAM  92 . When the nozzle skip function is not stored in the RAM  92 , a pickup operation of a next electronic component to be picked up starts. When the nozzle skip function is stored in the RAM  92 , the skip process is performed to the appropriate suction nozzle  15  and the pickup operation of the next electronic component to be picked up starts.  
      That is, there are twelve suction nozzles  15  attached to the mounting head  16  and some of the suction nozzles  15  are of same type. In the skip process, the CPU  90  controls so that the suction nozzle  15  which brings back the electronic component D is not used but the other suction nozzle  15  of same type is used instead.  
      When all the electronic components D specified in the mounting data are not mounted on the printed board P, the pickup sequence data is formed again as described above, and the pickup operation, the component recognition processing, and the mounting operation of the electronic component D are performed. When all the electronic components D specified in the mounting data are mounted on the printed board P, the beam  8  is returned to an original position, and the printed board P completing component mounting is mounted on the discharging conveyer  6 , completing the mounting operation.  
      In the next case, the screen as shown in  FIG. 10  is displayed on the CRT  96 , and then the line sensor unit  37  and the component recognition camera  89  are selected for use for detecting whether or not the suction nozzle  15  still holds the electronic component for mounting, which is small, after the component mounting operation on the printed board P. An operator pushes a switch portion  100 C and then the decision switch  100 D to set the detection by the line sensor unit  37  and the component recognition camera  89 . The CPU  90  then controls a detecting operation according to a program corresponding to the set content stored in the ROM  93 . This selection increases certainty in detection of presence or absence of an electronic component, since the detection result is “error” when either the line sensor unit  37  or the component recognition camera  89  detects the electronic component.  
      During the mounting head body  7  is moving to the component mounting position, the lowering amount of the mounting head body  7  when lowering to the height where the mounting head body  7  has been before it rises for the component recognition differs based on the thickness of the electronic component D held by the suction nozzle  15 , the height of the chute of the positioning portion  5 , and the height of the electronic component D already mounted on the printed board P. For example, when the electronic component held by the suction nozzle  15  is thick, the lowering amount is controlled to be small. Accordingly, in addition to the capability of adjusting the lowering amount of the mounting head body  7 , the rising amount of the electronic component held by the suction nozzle  15  can be increased by raising the suction nozzle  15  and the mounting head body  7  when the electronic component held by the suction nozzle  15  need be raised because of the height of the electronic component D already mounted on the printed board. This can broaden the range of thicknesses of the mountable electronic components, compared with the case where only the suction nozzle  15  is vertically moved.  
      In the above embodiment, the description is given on the electronic component mounting apparatus where two mounting head bodies  7  are slidably provided on each of the two beams  8  each being independently slidable. However, the same effect can be obtained in the electronic component mounting apparatus where a beam is provided on each of front, back, left, and right sides, being independently slidable, and a mounting head body is provided in each of the four beams, for example, as long as the mounting head body has the same structure as that of the embodiment described above.  
      Although particular preferred embodiment of the invention has been disclosed in detail, it will be recognized that variations or modifications of the disclosed apparatus are possible based on the disclosure for those skilled in the art and lie within the scope of the present invention.