Feeder for electronic chip components

An electronic chip component feeder is provided to prevent continued supply of electronic chip components for mounting which have surface discolorization, deteriorated electrode solderability, or cracks or chips produced by chip collisions. The electronic chip component feeder includes plural feeding units arranged in an array. Each feeding unit has a hopper for holding a plurality of components of a particular kind, and a guide path by which components are transferred from the hopper to a dispensing location. At the dispensing location, the components are picked up by a sucking chuck and then transferred to a substrate for mounting thereon. The plurality of feeding units are capable of being reciprocated in unison so that the dispensing location for the feeding units are successively moved to a fixed position. The electronic chip component feeder further includes a counting unit for counting the number of movements of the each feeding unit. This provides a measure of the degree of potential degradation of the electronic chip components in the hoppers caused by movement of their respective feeding unit. An alarm can be generated when the counted number reaches a predefined number, set individually for each feeding unit.

This application corresponds to Japanese Patent Application No. 10-13687
 filed on Jan. 27, 1998, which is hereby incorporated by reference in its
 entirety.
 BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to an electronic chip component feeder, and
 more specifically relates to an electronic chip component feeder in which
 a plurality of feeding units respectively supply each of a plurality of
 kinds of chip components and are reciprocated (e.g., moved back and forth)
 in the course of a feeding operation.
 2. Description of the Related Art
 Most electronic components capable of being surface-mounted, such as
 capacitors, resistors and inductors, are chip-shaped (e.g., have a small
 box-like, cylindrical or other shapes). In order to mount such electronic
 components on a substrate, a chip mounter is used. An electronic chip
 component feeder is built into the chip mounter.
 The electronic chip component feeder separately supplies a plurality of
 kinds of electronic chip components, respectively, through a plurality of
 feeding units disposed in parallel with each other. Each feeding unit has
 a hopper which accommodates and discharges a plurality of components of a
 specific kind. Further, each feeding unit has a guide path which guides
 the components discharged by the hopper in alignment to a predetermined
 dispensing location.
 The plurality of feeding units can be arranged in an array, such as a
 linear array. The feeding units can be reciprocated (e.g., moved back and
 forth) in unison in an "array direction," e.g., in a direction defined by
 the arrangement of the feeding units in the array. By this reciprocating
 transfer, the dispensing location through which the components are
 dispensed can be transferred to a predefined fixed position. The
 components located at the dispensing location, which is made coincident
 with the fixed position, are removed one by one using a pick-up mechanism.
 The pick-up mechanism may comprise, for example, a sucking chuck which
 picks up and holds components by exerting a vacuum sucking force. The
 pick-up mechanism is controlled so as to repeatedly reciprocate (e.g.,
 move back and forth) between the above-mentioned fixed position and a
 position at which a chip component is mounted during a mounting operation
 (referred to as the "mounting position").
 As described above, the mounting operation of the chip components is
 achieved by repeated reciprocation of the pick-up mechanism between the
 fixed position and the mounting position. The plurality of feeding units
 must be transferred in a desired direction and over a desired distance to
 make the dispensing location of a particular feeding unit coincident with
 the predefined fixed position. This operation is performed repeatedly, so
 as to pick-up components in a desired order and mount desired kinds of
 components using the pick-up mechanism.
 Accordingly, a feeding unit is generally moved and stopped several times in
 the course of mounting operations. Therefore, the chip components,
 accommodated in the hopper of the feeding unit, repeatedly collide with
 each other or with the hopper walls at every acceleration and deceleration
 of the unit (e.g., when the movement of the hopper starts and stops).
 Further, in order to speed up the mounting operation, the unit is moved
 quickly using rapid accelerations and decelerations (that is, movement
 starts and stops quickly). This can apply a substantial amount of
 mechanical shock to the electronic chip components during the
 above-described collisions.
 Moreover, a huge number of electronic chip components, from several
 hundreds up to several millions for example, are accommodated in the
 hopper of each feeding unit during mounting operations. Depending on the
 requirements of a particular mounting operation, some components have a
 comparatively short stay in the hopper, while other components remain in
 the hopper for a relatively long time. For example, most of the components
 which are consumed in small quantities in the mounting process remain in
 the hopper for a relatively long time.
 When the components remaining in the hopper for a long time undergo
 repeated collisions in the manner described above, the quality of the
 electronic chip components may degrade. For example, chipping and cracking
 of the electronic chip components may occur. Also, substantial discoloring
 of the outer surface or degradation in solderability of components having
 electrodes formed on the outer surface thereof may occur.
 The mounting of defective electronic chip components to a substrate results
 in the production of substandard circuit boards. This, in turn, may
 require replacement of defective components, which reduces productivity.
 SUMMARY OF THE INVENTION
 Accordingly, it is an object of the present invention to provide an
 electronic chip component feeder to solve at least the aforementioned
 problems.
 In accordance with one exemplary embodiment, an electronic chip component
 feeder is provided for feeding a plurality of kinds of electronic chip
 components, the components having electrodes on their respective outer
 surfaces. The electronic chip component feeder comprises a plurality of
 feeding units disposed in parallel with each other. Each of the feeding
 units includes a hopper for accommodating and discharging a plurality of
 electronic chip components of a specific kind, and a guide path for
 aligning and leading the electronic chip components discharged from the
 hopper to a predetermined dispensing location.
 A plurality of the feeding units are arranged in an array. The feeding
 units can be reciprocated in unison so that the dispensing location of a
 feeding unit for supplying the electronic chip components to be dispensed
 is transferred to a fixed position. The electronic chip component feeder
 further comprises a pick-up mechanism for picking-up the electronic chip
 components forwarded to the dispensing location.
 The electronic chip component feeder also includes a counting unit for
 counting the number of the reciprocating transfers of each feeding unit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 In FIG. 1, one exemplary feeding unit 2 of an electronic component feeder
 is illustrated. The feeding unit 2 has a hopper 4, which accommodates and
 discharges a plurality of electronic chip components 3 of a specific kind.
 The electronic chip components 3 have electrodes (not shown) formed on the
 outer surfaces thereof, for example, as in the case of conventional
 monolithic ceramic capacitors. The electronic chip components 3 discharged
 from the hopper 4 are led to a predetermined dispensing location 6 via a
 guide path 5. The electronic chip components 3 are aligned when passing
 through the guide path 5. The guide path 5 comprises a channel, indicated
 by broken lines in the drawing.
 The electronic chip components 3 led to the dispensing location 6 in an
 aligned state, as described above, are taken out from the dispensing
 location 6 as shown by arrow 8. The electronic chip components 3 are
 sucked and held by a sucking chuck 7, which functions as pick-up
 mechanism. The electronic chip components 3 held by the sucking chuck 7
 are then mounted at a desired position (i.e., a "mounting position") on a
 substrate (not shown) by moving the sucking chuck 7 to the desired
 mounting position.
 In one mounter, a plurality of feeding units 2, described above, are placed
 in an array on a transfer table 9. The presence of additional feeding
 units is indicated by the dots labeled 2'. One sucking chuck 7 is
 preferably provided to service one mounter and is controlled so as to
 repeatedly reciprocate between two positions during mounting operation,
 e.g., between the dispensing location and the mounting position. The
 transfer table 9 is controlled by a moving mechanism (not shown) so as to
 reciprocate in the directions shown by double-headed arrow 10 in order to
 dispense desired electronic chip components 3 in a desired order using the
 sucking chuck 7. This results in the plurality of feeding units 2
 reciprocating in unison in the array direction, e.g., in the direction in
 which feeding units are arranged in the array. In this reciprocating
 movement, a plurality of feeding units 2 are transferred in a desired
 direction over a desired distance so that the dispensing location 6 of a
 specific feeding unit 2 is brought to the fixed position. As described
 above, the fixed position corresponds to one end point position in the
 reciprocating movement of the sucking chuck 7.
 In one embodiment, each feeding unit 2 includes a counting mechanism 11 for
 counting the number of movements of each feeding unit 2. The collection of
 counting mechanisms 11 for all feeding units 2 can be generally referred
 to as a "counting unit." Each counting mechanism 11 includes a sensor (not
 shown) for sensing the movement of each respective feeding unit 2. The
 sensor may be of a type which responds to inertial changes, such as a
 sensor which senses the inertial force exerted on a plumb (e.g., like in a
 conventional pedometer). Alternatively, the sensor may use a pair of a
 mechanical or electrical contact switch and a contact piece to drive the
 switch disposed on the moving feeding unit 2 and a stationary position,
 respectively. Alternatively, the sensor can comprise a reflective or a
 translucent optical sensing mechanism. Those skilled in the art will
 appreciate that other types of sensors can be used. In general terms, the
 count generated by the counting mechanism 11 for each feeding unit 2 is
 representative of the amount of time the components have remained in the
 hopper 4 of the feeding unit 2, and thus is representative of the degree
 of potential degradation suffered by the components in the hopper 4.
 The counting mechanism 11 is also provided with a display 12 to display the
 counted number produced by the counting mechanism 11, and an alarm
 generating mechanism for generating an alarm when the counted number
 reaches a predetermined number. The alarm generating mechanism can include
 an alarm sound generator 13 and/or an alarm light generator 14. The alarm
 sound generator 13 is provided with, for example, an alarm generating
 circuit and a speaker, buzzer or other sound producing mechanism. The
 alarm light generator 14 can be formed by an incandescent lamp, an LED,
 LCD or other visual indication mechanism.
 The predetermined number which sets off the alarm generating mechanism is
 preferably individually selectable for respective feeding units 2. This is
 because the electronic chip components 3 are used at different rates in a
 series of mounting in a desired direction over a desired distance so that
 the dispensing location 6 of a specific feeding unit 2 is brought to the
 fixed position. As described above, the fixed position corresponds to one
 end point position in the reciprocating movement of the sucking chuck 7.
 In one embodiment, each feeding unit 2 includes a counting mechanism 11 for
 counting the number of movements of each feeding unit 2. The collection of
 counting mechanisms 11 for all feeding units 2 can be generally referred
 to as a "counting unit." Each counting mechanism 11 includes a sensor (not
 shown) for sensing the movement of each respective feeding unit 2. The
 sensor may be of a type which responds to inertial changes, such as a
 sensor which senses the inertial force exerted on a plumb (e.g., like in a
 conventional pedometer). Alternatively, the sensor may use a pair of a
 mechanical or electrical contact switch and a contact piece to drive the
 switch disposed on the moving feeding unit 2 and a stationary position,
 respectively. Alternatively, the sensor can comprise a reflective or a
 translucent optical sensing mechanism. Those skilled in the art will
 appreciate that other types of sensors can be used. In general terms, the
 count generated by the counting mechanism 11 for each feeding unit 2 is
 representative of the amount of time the components have remained in the
 hopper 4 of the feeding unit 2, and thus is representative of the degree
 of potential degradation suffered by the components in the hopper 4.
 The counting mechanism 11 is also provided with a display 12 to display the
 counted number produced by the counting mechanism 11, and an alarm
 generating mechanism for generating an alarm when the counted number
 reaches a predetermined number. The alarm generating mechanism can include
 an alarm sound generator 13 and/or an alarm light generator 14. The alarm
 sound generator 13 is provided with, for example, an alarm generating
 circuit and a speaker, buzzer or other sound producing mechanism. The
 alarm light generator 14 can be formed by an incandescent lamp, an LED,
 LCD or other visual indication mechanism.
 The predetermined number which sets off the alarm generating mechanism is
 preferably individually selectable for respective feeding units 2. This is
 because the electronic chip components 3 are used at different rates in a
 series of mounting operations so that the stay period in the hopper 4
 differs for each kind of electronic chip component 3.
 It is preferable to stop the movement of the feeding unit 2 when the
 counted number produced by the counting mechanism 11 reaches the
 predetermined number. Then, when the feeding unit 2 which generated the
 alarm is stopped, the electronic chip components 3 accommodated in its
 hopper 4 may be replaced by new components. The countering mechanism 11
 can be reset by a resetting mechanism (not shown).
 While the present invention has been described with reference to the
 embodiment shown in the drawing, various modifications can be made. For
 example, although the counting mechanism 11 is shown positioned on the
 feeding unit 2, along with all its components (including the display 12,
 the alarm sound generator 13, and the alarm light generator 14), it may
 also be preferable to place the display 12 and/or the alarm generating
 mechanism in another position such as a central control panel. In this
 embodiment, only the sensor which detects the movement of the feeding unit
 2 would be located at the feeding unit 2.
 Any of the alarm sound generator 13 and the alarm light generator 14 may be
 provided alone. Without these alarm generators, the replacing time of the
 electronic chip components 3 accommodated in the hopper 4 can be
 determined by checking the display 12 or by recognizing the stopping of
 the feeding unit 2.
 When the counted number produced by the counting mechanism 11 reaches a
 predetermined number, the feeding unit 2 may be manually or automatically
 stopped. To this end, a manual or automatic stopping mechanism can be
 used.
 As described above, in accordance with the present invention, due to the
 counting mechanism for counting the number of movements of the feeding
 unit of the electronic chip component feeder, the replacing time of the
 electronic chip components in the hopper can be easily determined by
 monitoring the counted number produced by the counting mechanism.
 Accordingly, the components are less likely to degrade prior to being
 mounted. More specifically, there is a reduced chance of discoloration of
 electronic chip components, degradation in solderability of electrodes,
 chipping and cracking. This results in improvements in productivity,
 eliminating losses in processing such as would result in producing a
 substandard circuit board and then having to replace the defective
 electronic chip components mounted on the circuit board. Also, reduction
 of production cost, increase in the amount of production, and reduction of
 labor cost may be achieved, simultaneously.
 In one embodiment, a conventional type of electronic chip component feeder
 can be adapted by providing each feeder unit with a counting mechanism.
 This has the advantage of quickly and efficiently implementing the
 invention with low cost. The counting mechanisms can be fed by a common or
 local power source (e.g., "local" with respect to each feeding unit). A
 battery power source (not shown) is preferably used, one for each feeding
 unit.
 By virtue of the use of the alarm generating mechanism, the feeding unit
 requiring replacement of its electronic chip components can be easily
 identified, among a plurality of the feeding units.
 By virtue of the fact that the alarms can be set to go off for different
 predetermined numbers for different respective feeding units, the alarm
 timings can be adjusted to reflect different rates at which the electronic
 chip components are consumed. Further, there may be some cases in which
 the required quality level or tolerance for degradation caused by the
 collisions differs for respective kinds of the electronic chip components.
 The alarm setting can be appropriately adjusted to account for this.
 In the electronic chip component feeder in accordance with the present
 invention, if a stopping mechanism is provided for stopping the movement
 of the feeding unit when the counted number produced by the counting
 mechanism reaches a predetermined number, the timing for replacing the
 electronic chip components can be detected by noting the stoppage.
 Continued supply of electronic chip components after the predetermined
 number has been reached (indicating that the components should be
 replaced) is also definitely avoided. In this case, if the alarm
 generating mechanism described above is further provided, when the feeding
 units stop, the feeding unit requiring replacement of the electronic chip
 components can be instantly known.
 The above-described exemplary embodiments are intended to be illustrative
 in all respects, rather than restrictive, of the present invention. Thus
 the present invention is capable of many variations in detailed
 implementation that can be derived from the description contained herein
 by a person skilled in the art. All such variations and modifications are
 considered to be within the scope and spirit of the present invention as
 defined by the following claims.