Abstract:
The present invention includes a component placement apparatus that can obtain information on the presence/absence of hold members inexpensively and easily, and a component placement method carried out by the component placement apparatus. A replacement hold member detector for detecting the presence/absence of replacement hold members at a hold member change part is installed at a placement head. The presence/absence is detected by moving an XY-robot so as to scan the hold member change part equipped with the replacement hold member detector. At the same time, type information attached to the replacement hold members is rendered readable by the replacement hold member detector. One replacement hold member detector is enough according to the apparatus and method of the present invention. The presence/absence information of the hold members can be obtained inexpensively and easily.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for placing electronic components onto circuit boards, and a component placement method executed by the apparatus. 
     2. Description of the Related Art 
     The variety of kinds of electronic components to be placed on circuit boards has increased recently. Accordingly, an apparatus that can handle various electronic components from micro-chip components to long connectors, etc. is strongly demanded. An example of a conventional apparatus of the above type will be described below with reference to FIG.  10 . FIG. 10 shows a total view of a conventional component placement apparatus  20 . In FIG. 10, reference numeral  1  indicates a transfer device for carrying in and out an electronic circuit board  2  with respect to the component placement apparatus  20  and positioning the circuit board  2  when electronic components are placed on the circuit board  2 . Reference numeral  3  indicates a reel-type component feed device including reels  4  to which a tape temporarily securely holding the electronic components is wound. The feed device sends the tape from the reel  4  thereby feeding the electronic components one by one. A tray-type component feed device  5  is also set in the apparatus  20  to feed electronic components, and the electronic components are aligned in a grid pattern on a tray  6 . Reference number  7  indicates a placement head having a component hold part  8  for holding a hold member  13  which sucks so as to hold the electronic components supplied from the reel-type component feed device  3  and the tray-type component feed device  5 . According to the component placement apparatus  20 , the hold member  13  is a nozzle that can suck the electronic component. Reference numeral  9  indicates an XY-robot for moving the placement head  7  in X, Y-directions orthogonal to each other with a plant to an optional position and positioning the placement head  7 . Reference numeral  10  indicates a component recognition camera for measuring a suction attitude of the electronic component held by the hold member  13 . Reference numeral  11  indicates a tool change part equipped with one or a plurality of hold members  13  replaced with the hold member  13  set at the component hold part  8 . Reference numeral  12  indicates a control device connected to the above transfer device  1 , reel-type component feed device  3 , tray-type component feed device  5 , placement head  7 , XY-robot  9 , component recognition camera  10 , and tool change part  11  for controlling operations of these devices and the entire component placement apparatus  20 . 
     In the above component placement apparatus  20 , the hold member  13  sucks so as to hold the electronic components. However, the apparatus may be adapted to hold the electronic components, for instance, mechanically by a chuck mechanism. Although only one component hold part  8  is shown at the placement head  7  in FIG. 10, actually, a plurality of component hold parts  8  are arranged which are omitted in the illustration. Needless to say, the placement head  7  may be designed to keep only one component hold part  8 . 
     The conventional component placement apparatus  20  of the above constitution operates in a manner as will be described below. 
     The hold members  13  of the placement head  7  are set as the component feed device  3  or component feed device  5  by the XY-robot  9 . Each of the hold members  13  is lowered by the component hold part  8  in a Z direction orthogonal to the X, Y-directions to suck an electronic component to be placed on the circuit board  2 . After the sucking, each hold member  13  is moved up by the component hold part  8 . A plurality of electronic components held by the hold members  13  are sequentially moved by the XY-robot  9  over the component recognition camera  10 . The component recognition camera  10  picks up the suction attitude of each electronic component at the hold member  13 . Information on the recognized images is sent to the control device  12 . The control device  12 , after taking the information on the recognized images, calculates an amount of correction for each electronic component on the basis of an amount of displacement of the suction attitude from a placement attitude on the circuit board  2 , and rotates the hold member  13  based on the correction amount about an axis in the Z direction. The control device  12  moves the XY-robot  9  to position the placement head  7  over the circuit board  2  and moves each component hold part  8  so that the electronic components are correctly placed sequentially at predetermined positions on the circuit board  2 . 
     In the case where the hold member  13  not corresponding to the electronic component to be placed on the circuit board  2  is accidentally set at the component hold part  8 , the XY-robot  9  is moved to move the placement head  7  over the tool change part  11  and this hold member  13  not corresponding to the electronic component to be placed is detached and retained at a vacant tool hold portion at the tool change part  11 . The component hold part  8  is then moved to a tool hold portion, where the other hold member  13  corresponding to the electronic component to be placed is caught. The hold member  13  corresponding to the electronic component to be placed is thus set to the component hold part  8 . 
     The component hold part  8  with the correct hold member  13  is moved to a feed position for the electronic component to be placed next and the above-described sequence of operations from suction to placement is repeated. 
     Electronic components of various kinds are sequentially placed in this manner on the circuit board  2 . 
     The tool change part  11  will be depicted with reference to FIGS. 11 and 12. The tool change part  11  includes a holding mechanism (not shown) capable of holding the hold members  13 . Each hold member  13  is inserted at a predetermined tool hold portion  14  corresponding to each hold member  13 . Sensors  15  are installed at the tool hold portions  14  to detect the presence/absence of the hold member  13 . Each sensor  15  is connected electrically to the control device  12 . Thus the control device  12  can recognize whether or not the predetermined hold members  13  are set at the tool hold portions corresponding to the predetermined hold members  13 . The sensor  15  is, specifically, a proximity sensor, a limit switch or the like known sensor. 
     The conventional tool change part  11  constituted as above has drawbacks. According to the related art, before starting the component placement apparatus  20 , necessary hold members  13  are on standby at the predetermined tool hold portions  14  at the tool change part  11 , and information on the presence/absence of the hold members  13  from the sensors  15  is recognized by the control device  12 . That is, the sensor  15  is installed for each of the tool hold portions  14 , thereby raising costs and making the wiring complicated. In order to distinguish the types of hold members  13  kept at the component hold parts  8 , an increasing number of sensors  15  or a plurality of expensive sensors are necessitated at the tool change part. 
     SUMMARY OF THE INVENTION 
     The present invention is devised to solve the above problems and has for its object to provide a component placement apparatus that can obtain information on the presence/absence of hold members inexpensively and easily, and a component placement method carried out by the component placement apparatus. 
     In order to achieve the aforementioned objective, a component placement apparatus is provided according to a first mode of the present invention. The apparatus includes a placement head having a hold member that is detachable and replaceable corresponding to a component to be held for placing the component held by the hold member at an object to be placed. A hold member change part has a replacement hold member that can be fitted to the placement head where the hold member and the replacement hold member are exchanged by the placement head. The replacement hold member holds another component to place the other component at the object. The placement head has a replacement hold member detector for detecting presence/absence of the replacement hold member at the hold member change part. 
     Further, the replacement hold member detector detects the type of replacement hold member (type information) in addition to detecting the presence/absence of the replacement hold member. 
     Further, the component placement apparatus comprises a control device for making a judgement whether or not the replacement hold member corresponding to the other component to be placed at the object to be placed is present at the hold member change part on the basis of the type information of the replacement hold member corresponding to the other component to be placed at the object to be placed. The type information is sent out from the replacement hold member detector. 
     The type information is attached to the replacement hold member in the form of a type information indicator, and the replacement hold member detector optically reads the type information indicator. 
     The control device further makes a location and a type of each replacement hold member at the hold member change part correspond to each other on the basis of the information sent out from the replacement hold member detector. 
     A component placement method according to a second mode of the present invention includes scanning a replacement hold member set at a hold member change part so as to detect the presence/absence of the replacement hold member. It is then decided whether or not a hold member is exchangeable with the replacement hold member corresponding to a component to be held on the basis of the scanning. The hold member is exchanged with the replacement hold member corresponding to the component to be held and the component to be held with the replacement hold member is held. The component held with the replacement hold member is placed at an object to be placed. 
     According to the component placement apparatus in the first mode of the present invention and the component placement method in the second mode of the present invention, the replacement hold member detector is installed at the placement head to detect the presence/absence of replacement hold members at the hold member change part. The presence/absence of the replacement hold members is detected through scanning over the hold member change part. A sensor is thus eliminated from the hold member change part holding many kinds of components. A simple and inexpensive constitution is achieved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will become clear following description taken in conjunction with the preferred embodiment thereof with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a placement head and a tool change part of a component placement apparatus according to a preferred embodiment of the present invention; 
     FIG. 2 is a diagram explanatory of a state in which a replacement hold member at the tool change part is detected by a replacement hold member detector installed at the placement head of FIG. 1; 
     FIG. 3 is a diagram explanatory of a state in which information on the type of replacement hold member of the tool change part is detected by the replacement hold member detector installed at the placement head of FIG. 1; 
     FIG. 4 is a plan view of the replacement hold member of FIG. 3; 
     FIG. 5 is a diagram showing examples of type information marked at the replacement hold member of FIG. 3; 
     FIG. 6 is a perspective view of the entire component placement apparatus in the embodiment of the present invention; 
     FIG. 7 is a flow chart of the detection operation for the replacement hold member at the tool change part in the component placement apparatus of FIG. 6; 
     FIG. 8 is a perspective view showing in detail the structure of the tool change part of the component placement apparatus of FIG. 1; 
     FIG. 9 is a side view of the tool change part of FIG. 8; 
     FIG. 10 is a perspective view of a conventional component placement apparatus; 
     FIG. 11 is a perspective view of a tool change part shown in FIG. 10; and 
     FIG. 12 is a sectional view taken along the line I—I of FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A component placement apparatus in a preferred embodiment of the present invention, and a component placement method executed by the component placement apparatus will be described hereinbelow with reference to the drawings. The same parts in the drawings are denoted by the same reference numerals. In the embodiment, an electronic component is discussed by way of example to function as the “component” described in the above “SUMMARY OF THE INVENTION”. Likewise, a circuit board and a tool change part are exemplified, respectively, as the “object to be placed” and “hold member change part” 
     As shown in FIG. 6, an essential construction of a component placement apparatus  101  in the embodiment is similar to the above-described conventional apparatus  20 . More specifically, the component placement apparatus  101  includes a transfer device  111  for a circuit board  2 , a reel-type component feed device  113 , a tray-type component feed device  115 , a placement head  117 , an XY-robot  119 , a component recognition camera  120 , a hold member change part  121 , and a control device  130 . The transfer device  111  corresponds to the conventional transfer device  1 . Similarly, the reel-type component feed device  113  corresponds to the conventional reel-type component feed device  3 , the tray-type component feed device  115  corresponds to the conventional tray-type component feed device  5 , the XY-robot  119  corresponds to the conventional XY-robot  9 , and the component recognition camera  120  corresponds to the conventional component recognition camera  10 . These devices have the same constitution and function as the conventional corresponding ones. Therefore, the description of these devices will be omitted here. A characteristic part of the component placement apparatus  101  in the embodiment is the placement head  117 , hold member change part  121 , and control device  130  which will be detailed below. 
     The placement head  117  has hold members  151  for sucking, similar to the related art, so as to hold electronic components, has component hold parts  161  for holding the hold members  151  removably and replaceably, and has a replacement hold member detector  171 . The placement head  117  is loaded on the XY-robot  119  and made movable in X, Y-directions, similar to the conventional placement head  7 . The hold members  151  can be moved by the component hold parts  161  in the Z direction. According to the embodiment indicated in the drawing, the placement head  117  has four hold members  151  and four component hold parts  161  corresponding to the hold members  151 . However, the number of the hold members is not limited to this, and an optional count not smaller than one is possible. The hold members  151  can be driven independently separately by the corresponding component hold parts  161 , the operation of which is controlled by the control device  130 . 
     Although the electronic components are held through suction by the hold members  151  in the embodiment, a mechanical mechanism or the like may be adopted or the suction and mechanical operation may be mixedly executed at the placement head  117 . 
     For the sake of description, the hold member set at the placement head  117  will be designated as the hold member  151 , and the hold member kept at the hold member change part  121  to be described later will be denoted as a replacement hold member  191 . 
     Tool hold portions  181  in which the replacement hold members  191  are inserted are arranged in a grid pattern on a flat plate of the hold member change part  121 . Some of the tool hold portions  181  do not contain replacement hold members  191  so as to catch the hold members  151  from the placement head  117 . 
     The hold member change part  121  is constructed as shown in detail in FIG.  8 . Specifically, the hold member change part  121  has a holding mechanism  201  for each array of the tool hold portions  181 . The holding mechanism detaches the hold members  151  set at the placement head  117  and keeps them at the tool hold portions  181 . In the holding mechanism  201 , a pair of opening levers  204  are opened or closed in response to an up or down movement of a wedge-shaped cam  202  by a cylinder  203  which has an open sensor  209  to indicate the opening or closure of the opening levers  204 . The cylinder  203  is controlled in operation by the control device  130  and the open or closure signal sent from the open sensor  209  is supplied to the control device  130 . 
     The above holding mechanism  201  operates in a manner as follows. Generally, the cam  202  is at an up position, with the opening levers  204  opened as shown in FIG.  8 . When the cam  202  is lowered by the cylinder  203  after the hold member  151  is installed in the tool hold portion  181  of the tool change part  121  so as to be exchanged with the replacement hold member  191 , the pair of opening levers  204  are closed. In consequence, as indicated in FIG. 9, the opening levers  204  are engaged with a groove  205  formed in the loaded hold member  151 , thereby holding the groove  205  between the opening levers  204 . The placement head  117  is raised in a state while the groove  205  is caught between the opening levers  204 , whereby a ball plunger  206  is disengaged from a groove  207  of the hold member  151 . Only the placement head  117  is allowed to move up while the hold member  151  is retained at the tool hold portion  181 . Incidentally, the ball plunger  206  is set at a hold part  210  of the component hold part  161  of the placement head  117  for holding the hold member  151 , which is engaged with the groove  207  of the hold member  151  when the hold member  151  is held with the hold part  210 . 
     The replacement hold member detector  171  has a sensor part installed at a casing of the placement head  117  to confront X, Y-planes. As indicated in FIG. 2, when the placement head  117  is moved in the X, Y-directions above the tool change part  121  by the XY-robot  119 , the detector  171  detects whether or not the replacement hold member  191  which is to replace the above hold member  151  is present at the tool hold portion  181  of the tool change part  121 . Moreover, according to the embodiment as shown in FIG. 3, the replacement hold member detector  171  detects type information attached to the replacement hold member  191  correspondingly to the electronic component to be held with the replacement hold member  191 . The replacement hold member detector  171  is arranged at a set position of the placement head  117  to make a movement distance of the placement head  117  as small as possible in view of the placement operation for the electronic components to the circuit board  2 . The replacement hold member detector  171  of the embodiment is a reflecting type detector that irradiates light to a part to be detected and optically recognizes the part from the reflecting wave of the irradiated light. Although the presence/absence of the replacement hold member  191  and the type information are both detected by one replacement hold member detector  171  according to the embodiment, this information may be detected separately by different detectors. 
     Position information obtained by the XY-robot  119 , presence/absence information of the replacement hold member  191 , and type information obtained from the replacement hold member detector  171  are fed to the control device  130 . Before the electronic component is started to be placed on the circuit board  2 , the control device  130  stores in a memory part  131  the presence/absence information and type information correspondingly for each tool hold portion  181  of the holding member change part  121  based on the above position information. 
     Referring to FIGS. 3 and 4, the above type information indicator  212 , which represents the type of hold member  151  and the type of replacement hold member  191 , is a mark of five spots formed in the same configuration as a five of a die on flange parts  211  of the hold member  151  and the replacement hold member  191 . As shown in FIG. 5, each spot is colored with white or black so that the type information indicator  212  can represent  32  types of information in combination of white and black spots. Every replacement hold member  191  is stored at the hold member change part  121  such that the type information indicators of each replacement hold member  191  are arranged at the same position. For instance, every replacement hold member  191  is stored at the tool hold portion  181  so that the type information indicator assumes an angle of  30 o in the counterclockwise direction to a center line  213  passing through the center of the replacement hold member  191  aligned in the X-direction and extending in the X-direction. 
     The operation of the component placement apparatus  101  constituted as above will be discussed now. 
     In FIG. 7, when an automatic operation is ordered in step (denoted by “S” in the drawing)  1 , the placement head  117  is moved by the XY-robot  119  so as to be positioned over the tool change part  121  in step  2 . In steps  3 - 6 , while the placement head  117  is moved in the X, Y-directions, the replacement hold member detector  171  installed at the placement head  117  scans the hold member change part  121  and detects whether the replacement hold members  191  are stored at the tool hold portions  181  of the tool change part  121 , and scans the type information indicator attached to each replacement hold member  191 . 
     Through the scanning, information on a movement amount in the X, Y-directions of the XY-robot  119 , and the presence/absence information and type information of the replacement hold members are supplied to the control device  130  via a generated information signal. Based on the supplied information, the control device  130  stores position information of each tool hold portion  181  of the hold member change part  121  correspondingly to the presence/absence information and type information of the replacement hold member  191  at each tool hold portion  181  into the memory part  131 . 
     According to the above operation, recognition is executed for each tool hold portion  181  (step  6 ). The control device  130  controls the placement of the electronic components on the basis of the recognized and stored information. Meanwhile, when the replacement hold members  191  are to be aligned beforehand at the hold member change part  121  to meet the order of types of electronic components to be placed, the control device  130  checks in step  7  whether or not the replacement hold members  191  are aligned in an order agreeing with the order of types of the electronic components. If the replacement hold members  191  are arranged wrong, the sequence from step  1  is tried again, after the arrangement is corrected. On the other hand, when the arrangement is correct, the placement of electronic components is started. 
     In executing the placement operation for the electronic components, information in which a placement position of the electronic component on the circuit board  2  and the electronic component to be placed are made to correspond to each other is supplied preliminarily to the control device  130 , and information on the hold member  151  that can hold the electronic component to be placed is supplied as well. Therefore, the control device  130  automatically fits the hold member  151  that can hold the electronic component to be placed to the placement head  117  in the order of placement. When the need for replacing the hold member  151  of the placement head  117  arises, the control device  130  moves the placement head  117  to above the hold member change part  121 , moves the component hold part  161  in the Z-direction, drives the holding mechanism  201  as depicted earlier to retreat the hold member  151  to a predetermined tool hold portion  181 , and attaches the required replacement hold member  191  to the component hold part  161 . 
     The electronic components are sucked from the component feed device  113  or  115  and placed on the circuit board  2  by using the hold members  151  corresponding to the electronic components placed on the circuit board  2  in the same manner as in the related art. 
     In the present embodiment as above, the replacement hold member detector  171  installed at the placement head  117  scans over the hold member change part  121  before the electronic components are started to be placed on the circuit board  2 , thereby recognizing the presence/absence of the replacement hold members  191 . When the hold members  151  are to be exchanged with the replacement hold members, they are prevented from being interfered with or forgotten to be replaced, etc. The location and type of the replacement hold members  191  at the tool change part  121  can be recognized by reading the type information attached to the replacement hold members by means of the scanning of the replacement hold member detector, thus enabling automatic exchange of the hold members. 
     Although the replacement hold member detector is adapted to recognize even the type information of the replacement hold members  191  according to the embodiment, it may be enough to detect at least the presence/absence of the replacement hold members  191 . 
     As described herein, every time the automatic operation is ordered (that is, every time a circuit board is started to be produced), the presence/absence of the replacement hold members  191  and the type of the members  191  are confirmed in steps  3  through  6 . 
     However, productivity might decrease sometimes when the above confirmation is conducted at every start time of the production. For solving this, the presence/absence of the replacement hold members  191  and the type of replacement hold members  191  may be adapted to be recognized only when any one of the following events (i)-(iv) occurs, whereby an amount of time necessary for the confirmation is saved and production efficiency is improved accordingly. 
     (i) Turning on the component placement apparatus  101 ; 
     (ii) Sending the open or closure signal from the open sensor  209  of the hold member change part  121 ; 
     (iii) Artificially exchanging the hold member  151 , which leads to disagreement between the information stored in the memory part  131  of the control device  130  showing at which of the four points in the embodiment of the placement head  117  the hold member  151  is loaded and which type of hold member  151  is loaded and, the information on the location and type of hold member  151  actually fitted to the placement head  117 ; and 
     (iv) Causing a malfunction of the component placement apparatus  101 . 
     Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims unless they depart therefrom.