Electronic component-mounting apparatus and mounting head device therefor

A component-mounting block of an electronic component-mounting apparatus has mounting heads installed thereon. Each mounting head has a nozzle-replacing device for replacing at least one selected sucking nozzle by at least one other sucking nozzle to be newly selected. The replacement is possible during travel of the component-mounting block between a mounting position and a sucking position effected by a X-Y moving stage. At least one mounting head carries at least one sucking nozzle rotatable about a vertical axis of a nozzle holder. The mounting head has the nozzle holder, and an engaging member holder. Sucking nozzles are circumferentially arranged about the vertical axis of the nozzle holder and vertically retractably held by the nozzle holder. The engaging member holder holds engaging members which engageably face the nozzles. The nozzles are engaged with the engaging members when the holders are relatively vertically moved toward each other, and are retracted when the holders are moved away from each other. The engagement can be prevented. A selected engaging member is prevented from engaging with a corresponding sucking nozzle by rotating the holders about the vertical axis. Alternatively, at least one nozzle is disengaged from a corresponding engaging member at a desired rotational angle of the holders.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an electronic component-mounting apparatus of 
multi-function type for mounting various kinds of electronic components on 
a circuit board, and a mounting head device installed on the electronic 
component-mounting apparatus. 
2. Prior Art 
Conventionally, an electronic component-mounting apparatus of this kind has 
been proposed by Japanese Laid-Open Patent Publication (Kokai) No. 
4-35095, which includes a sucking nozzle for sucking an electronic 
component, a mounting head carrying the sucking nozzle, an elevating 
device for vertically moving the sucking nozzle, and an X-Y stage for 
moving the mounting head in an X-axis direction and a Y-axis direction on 
a horizontal plane. Further, the electronic component-mounting apparatus 
includes a nozzle storage device for holding a plurality of kinds of 
sucking nozzles in stock for selective use to make the mounting head 
adapted to various kinds of electronic components. The mounting head 
carries a single sucking nozzle, which can be replaced at the nozzle 
storage device by one suitable for an electronic component to be mounted . 
FIG. 1 schematically shows operations of the electronic component-mounting 
apparatus constructed as above. The figure illustrates a case in which an 
electronic component sucked at a point A of a component-feeding block 101 
is mounted at a point P1 of a circuit board 102, and then an electronic 
component sucked at a point B of the component-feeding block 101 is 
mounted at a point P2 of the circuit board 102. First, the X-Y stage 103 
moves the mounting head 104 from its home position to a position exactly 
above the point A, and then the elevating device 105 lowers the sucking 
nozzle to suck the electronic component at the point A. After sucking the 
electronic component, the elevating device 105 lifts the sucking nozzle, 
and the X-Y stage moves the mounting head 104 from the point A to a 
position exactly above the point P1. Then, the sucking nozzle is lowered 
again to mount the same at the point P1. 
The mounting head 104 is then moved to the point B to suck an electronic 
component and mount the same at the point P2 of the circuit board 102. In 
doing this, if the same sucking nozzle as employed for the immediately 
preceding electronic component can suitably handle the present electronic 
component, the same procedure as described above is carried out to mount 
the electronic component. However, if the electronic component supplied at 
the point B cannot be handled by the same sucking nozzle, the mounting 
head 104 is once moved to the nozzle storage device 106, where the sucking 
nozzle is replaced by one suitable for the present electronic component. 
The mounting head 104 is then moved to the point B to thereafter carry out 
the same mounting operations as described above. 
On the other hand, Japanese Laid-Open Patent Publication (Kokai) No. 
5-226884 discloses an electronic component-mounting apparatus of rotary 
type, which includes mounting heads each carrying a plurality of sucking 
nozzles. The sucking nozzles of the mounting head are arranged along the 
circumference of the mounting head at equally-spaced intervals such that 
each of them is capable of projecting and retracting, and as a whole 
rotating about the vertical axis of the mounting head 104. The sucking 
nozzles are each urged by a coiled spring in a projecting direction, with 
an engaging member being arranged for an upper portion of each of the 
sucking nozzles for holding the same in a retracted position. Each 
engaging member is pivotally movable between a position for engagement 
with a sucking nozzle associated therewith and a position for 
disengagement therefrom, and urged by a spring in an engaging direction. 
That is, when each sucking nozzle is retracted against the urging force of 
the coiled spring, it is brought into engagement with the engaging member 
to be held in the retracted position. Inversely, when the sucking nozzle 
is disengaged from the engaging member, it is brought into a projected 
position by the coiled spring. Therefore, in changing (replacing) sucking 
nozzles, the mounting head is lowered to cause the sucking nozzle to 
strike against a flat stopper whereby all the sucking nozzles are once 
retracted, and then as the mounting head is lifted, an arm extending from 
the body of the apparatus prevents engagement of a selected sucking nozzle 
with an engaging member associated therewith. 
In the conventional electronic component-mounting apparatus, as more kinds 
of electronic components are to be mounted on one circuit board, sucking 
nozzles are changed more often. In other words, the mounting head 104 is 
more frequently moved to the nozzle storage device 106 for replacement of 
sucking nozzles. Particularly, it takes time to change sucking nozzles 
since it involves moving of the mounting head 104 before the sucking 
nozzle is removed therefrom and a new sucking nozzle is mounted thereon, 
so that, as a whole, the tact time of mounting electronic components on 
the circuit board 102 is increased. 
Further, in the mounting head used in the electronic component-mounting 
apparatus disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 
5-226884, the stopper is necessitated for changing sucking nozzles, and 
horizontal motion of the mounting head has to be interrupted so as to 
lower the mounting head and then lift it up. 
SUMMARY OF THE INVENTION 
It is a first object of the invention to provide an electronic 
component-mounting apparatus which is capable of reducing tact time of 
mounting a plurality of kinds of electronic components on a circuit board. 
It is a second object of the invention to provide a mounting head device 
which is capable of replacing sucking nozzles with ease during horizontal 
motion thereof. 
To attain the first object, according to a first aspect of the invention, 
there is provided an electronic component-mounting apparatus for sucking 
electronic components and mounting the electronic components on a circuit 
board, the electronic component-mounting apparatus comprising: 
a component-feeding block for feeding a plurality of electronic components 
to a sucking position; 
a component-mounting block for selectively sucking at least one of the 
electronic components at the sucking position of the component-feeding 
block, and mounting the at least one of the electronic components having 
been sucked, on a circuit board at a mounting position, 
the component-mounting block having a plurality of mounting heads installed 
thereon, 
each of the plurality of mounting heads having: 
a plurality of sucking nozzles for sucking a corresponding one of the 
electronic components, and 
a nozzle-replacing device for effecting replacement of at least one 
selected sucking nozzle of the plurality of sucking nozzles by at least 
one other sucking nozzle of the plurality of sucking nozzles to be newly 
selected; and 
an X-Y moving stage for moving the component-mounting block between the 
sucking position and the mounting position, wherein the nozzle-replacing 
device is capable of the replacement of the at least one selected sucking 
nozzle of the plurality of sucking nozzles by the at least one other 
sucking nozzle of the plurality of sucking nozzles to be newly selected, 
during travel of the component-mounting block between the mounting 
position and the sucking position effected by the X-Y moving stage. 
According to this electronic component-mounting apparatus of the first 
aspect of the invention, since the mounting head carries a plurality of 
sucking nozzles, it is possible to use the plurality of sucking nozzles 
adaptively for a plurality of kinds of electronic components, which leads 
to decrease in frequency of replacing sucking nozzles. Further, since the 
nozzle-replacing device is capable of selectively replacing at least one 
of the plurality of sucking nozzles during travel of the component-feeding 
block by the X-Y moving stage, time required replacement of sucking 
nozzles can be reduced. Moreover, since the component-mounting block has 
the plurality of mounting heads installed thereon, frequency of replacing 
sucking nozzles is further decreased. If as many mounting heads as 
possible (preferably all mounting heads) suck electronic components at the 
component-feeding block, the frequency of travel of the component-mounting 
blocks by the X-Y moving stage per number of electronic components to be 
mounted can be markedly decreased, whereby the whole tact time of mounting 
electronic components can be reduced. 
Preferably, the nozzle-replacing device lifts upward the at least one 
selected sucking nozzle and projects downward the at least one other 
sucking nozzle to be newly selected, to thereby replace the former by the 
latter. 
According to this preferred embodiment, it is possible to selectively 
replace sucking nozzles by vertical movement thereof, so that there is no 
fear of sucking nozzles interfering with other component parts of the 
apparatus during travel of the mounting head. This enables sucking nozzles 
to be selected or replaced in a simple manner in a short time period. 
Further, the whole mounting head can be vertically moved by the use of a 
device for vertically moving the sucking nozzles. 
Still preferably, the each of the mounting heads has a nozzle holder which 
has the plurality of sucking nozzles arranged circumferentially about a 
vertical axis thereof, and an electric motor for rotating the nozzle 
holder about the vertical axis thereof. 
According to this preferred embodiment, the mounting head is capable of 
rotating a plurality of sucking nozzles, by itself, i.e. by means of the 
motor and the nozzle holder both incorporated in the mounting head, 
whereby it is possible to effect fine correction of positions of the 
sucking nozzles before electronic components are sucked, so as to make the 
positions of the sucking nozzles suitable for actual positions of the 
electronic components to be sucked. Further, the rotation of the nozzle 
holder can be also utilized in selective replacement of the sucking 
nozzles. 
Preferably, the component-mounting block has elevating means for vertically 
moving each of the plurality of mounting heads such that the each of the 
mounting heads is vertically moved with reference to a level of a bottom 
surface of each of the respective electronic components having been sucked 
by the each of the mounting heads. 
According to this construction, since the mounting head is vertically moved 
with reference to a level of the bottom surface of each electronic 
component sucked, the bottom surface of each of electronic components can 
be always set to a fixed level even if they are different in thickness, 
whereby it is possible to recognize each component with accuracy by a 
component-sensing camera. 
Preferably, the component-feeding block has means for feeding the plurality 
of electric components in an aligned manner at intervals of an identical 
distance, thereby permitting a plurality of ones of the plurality of 
electronic components to be selectively simultaneously sucked, and the 
component-mounting block has the plurality of mounting heads installed 
thereon in parallel with the plurality of electronic components arranged 
in the aligned manner, in a manner such that a pitch of arrangement of the 
plurality of mounting heads is an integral multiple of the identical 
distance. 
According to this preferred embodiment, a plurality of electronic 
components to be sucked and a plurality of mounting heads for sucking 
desired ones of the electronic components are positioned in a manner 
opposed to and parallel with each other, and a pitch of arrangement of the 
mounting heads proportionately agrees with a pitch of arrangement of the 
electronic components. Therefore, it is possible to simultaneously suck 
the plurality of desired electronic components by the plurality of 
mounting heads. Although the simultaneous sucking of a plurality of 
electronic components requires coincidence between the arrangement of 
electronic components to be mounted on a circuit board and that of 
electronic components to be sucked at the component-feeding block, the 
increased frequency of simultaneous sucking of electronic components 
contributes to reduction in tact time of mounting electronic components. 
Further preferably, the each of the mounting heads has a nozzle holder 
which has the plurality of sucking nozzles arranged circumferentially 
about a vertical axis thereof, and an electric motor for rotating the 
nozzle holder about the vertical axis, the sucking nozzles each rotating 
on a circular path of rotation having a diameter larger than the identical 
distance of the plurality of electronic components. 
According to this preferred embodiment, one mounting head is capable of 
rotating sucking nozzles thereof to thereby select and suck either of two 
electronic components. This makes it possible to further increase the 
possibility and hence frequency of simultaneous sucking of electronic 
components. 
Preferably, the component-feeding block feeds a plurality of kinds of 
electronic components, and the plurality of mounting heads each have a 
plurality of sucking nozzles corresponding to a plurality of selected 
kinds of the plurality of kinds of electronic components. 
To attain the first object, according to a second aspect of the invention, 
there is provided an electronic component-mounting apparatus for sucking 
electronic components and mounting the electronic components on a circuit 
board, the electronic component-mounting apparatus comprising: 
a component-feeding block for feeding a plurality of electronic components 
to a sucking position; 
a component-mounting block for selectively sucking at least one of the 
electronic components at the sucking position of the component-feeding 
block, and mounting the at least one of the electronic components having 
been sucked, on a circuit board at a mounting position, 
the component-mounting block each having a plurality of mounting heads 
installed thereon, 
at least one of the plurality of mounting heads having at least one sucking 
nozzle mounted thereon in a manner rotatable about a vertical axis of the 
mounting head; and 
an X-Y moving stage for moving the component-mounting block between the 
sucking position and the mounting position. 
According to this electronic component-mounting apparatus of the second 
aspect of the invention, the at least one mounting head is capable of 
decreasing frequency of replacing sucking nozzles carried thereon by other 
sucking nozzles. The apparatus is also capable of correcting positions of 
sucking nozzles relative to respective electronic components to be sucked 
and simultaneously sucking electronic components. 
To attain the first object, according to a third aspect of the invention, 
there is provided an electronic component-mounting apparatus for sucking 
electronic components and mounting the electronic components on a circuit 
board, the electronic component-mounting apparatus comprising: 
a component-feeding block for feeding at least one electronic component to 
a sucking position; and 
a mounting head for selectively sucking at least one of the at least one 
electronic component at the sucking position of the component-feeding 
block and then moving on a horizontal plane to mount the at least one 
electronic component having been sucked, on a circuit board at a mounting 
position, 
the mounting head having: 
a nozzle holder, 
a plurality of sucking nozzles arranged along an identical circle about a 
vertical axis of the nozzle holder and held by the nozzle holder in a 
manner capable of projecting and retracting vertically, 
an engaging member holder, 
a plurality of engaging members each held by the engaging member holder in 
a manner engageable with the plurality of sucking nozzles, respectively, 
rotating means for rotating the nozzle holder and the engaging member 
holder about the vertical axis of the nozzle holder, 
elevating means for vertically moving the nozzle holder and the engaging 
member holder away from each other, to thereby retract ones of the sucking 
nozzles in engagement with corresponding ones of the engaging members into 
the nozzle holder, and 
disengaging means for disengaging at least one of the plurality of sucking 
nozzles and a corresponding one of the engaging members from each other at 
an arbitrary desired rotational angle position of the nozzle holder and 
the engaging member holder. 
According to this electronic component-mounting apparatus, the nozzle 
holder holds a plurality of sucking nozzles arranged along the identical 
circle around the vertical axis thereof such that they are capable of 
projecting and retracting vertically, while the engaging member holder 
holds a plurality of engaging members in a manner each engageable with one 
of the plurality of sucking nozzles. The disengaging means disengages at 
least one of the plurality of sucking nozzles from an engaging member at 
an arbitrary desired rotational angle position of the nozzle holder and 
the engaging member holder. Accordingly, when the nozzle holder and the 
engaging member holder are vertically moved away from each other by the 
elevating means, in a state in which one of the nozzles has been 
disengaged from an corresponding engaging member by the disengaging means, 
the sucking nozzle disengaged from the engaging member moves to follow the 
movement of the nozzle holder to be held in a state projected from the 
nozzle holder, while the other sucking nozzles are prevented from moving 
by the engagement with the corresponding engaging members and hence 
retracted into the nozzle holder. 
As described above, it is possible to project only the sucking nozzle 
selectively disengaged from the engaging member from the nozzle holder by 
vertically moving the nozzle holder and the engaging member holder toward 
each other and away from each other by the elevating means, to thereby 
carry out sucking and mounting of electronic components. Further, the 
disengaging means enables a sucking nozzle to be instantly disengaged from 
a corresponding engaging member regardless of a rotational angle position 
of the nozzle holder and the engaging member holder. This makes it 
possible to shorten time required for disengagement between a sucking 
nozzle and an engaging member compared with a case where the disengagement 
is carried out by rotating and positioning the nozzle holder and the 
engaging member holder, so that tact time of mounting electronic 
components on a circuit board can be the further reduced. 
Moreover, since a plurality of sucking nozzles are arranged along an 
identical circle around the vertical axis about which the nozzle holder 
and the engaging member holder rotate, the disengaging means can have a 
relatively simple construction. 
Preferably, the disengaging means is capable of simultaneously disengaging 
at least two of the plurality of sucking nozzles from corresponding ones 
of the engaging members. 
According to this preferred embodiment, the disengaging means is capable of 
simultaneously disengaging more than one sucking nozzles from 
corresponding engaging members, so that particularly when electronic 
components are simultaneously sucked by a plurality of sucking nozzles, 
time required for selective projection or replacement of sucking nozzles 
is further shortened, and hence the tact time of mounting the electronic 
components can be also reduced. 
Preferably, the plurality of sucking nozzles comprise four sucking nozzles 
arranged circumferentially at intervals of an identical distance. 
According to this preferred embodiment, since the four sucking nozzles are 
arranged along an identical circle at angular intervals of 90 degrees 
about the vertical axis of the nozzle holder, it is possible to further 
simplify the arrangement of the disengaging means, and at the same time 
rotate the nozzle holder about the same vertical axis to thereby easily 
position and correct positions of the sucking nozzles before 
simultaneously sucking a plurality of electronic components by the 
plurality of sucking nozzles from component-feeding blocks arranged in 
parallel with each other. 
Preferably, each of the plurality of engaging members is held by the 
engaging member holder in a manner pivotally movable about a horizontal 
pivot thereof and urged in an engaging direction for engagement with a 
corresponding one of the sucking nozzles, the each of the engaging members 
having at least part of an outer surface thereof formed by a magnetic 
substance, the disengaging means having a plurality of electromagnets 
arranged circumferentially in a manner opposed to the magnetic substance 
of the each of the engaging members, for pivotally moving a selected one 
of the engaging members in a direction opposite to the engaging direction 
when one of the electromagnets corresponding to the selected one of the 
engaging members is excited, to thereby attract the selected one of the 
engaging members by way of the magnetic substance thereof, and 
electromagnet control means for controlling magnetization/demagnetization 
of the plurality of electromagnets independently of each other. 
According to this preferred embodiment, the electromagnet control means 
controls magnetization (excitation) and demagnetization of the plurality 
of electromagnets independently of each other, and an electromagnet 
excited (magnetized) by the electromagnet control means exerts magnetic 
force thereof on a magnetic substance of an engaging member opposed 
thereto, to thereby pivotally move the engaging member in a direction 
opposite to the engaging direction. This pivotal movement of the engaging 
member, i.e. attraction of the engaging member by the electromagnet 
disengages the engaging member from the corresponding sucking nozzle, and 
reliably maintains the disengaged state of the engaging member from the 
sucking nozzle. Thus, simply by exciting (magnetizing) an electromagnet 
corresponding to a sucking nozzle to be selected, the sucking nozzle can 
be easily disengaged from an corresponding engaging member, regardless of 
a rotational angle position of the nozzle holder and the engaging member 
holder, and the disengaged state of the sucking nozzle can be maintained. 
Further, it is possible to simultaneously disengage a plurality of sucking 
nozzles from corresponding engaging members by simultaneously exciting a 
plurality of electromagnets, respectively. 
Further preferably, the plurality of electromagnets are formed by 
electromagnets larger in number than a number of the plurality of sucking 
nozzles. 
According to this preferred embodiment, even when one engaging member is in 
a position opposed to two electromagnets at the same time depending on the 
rotational angle positions of the nozzle holder and the engaging member 
holder, it is possible to positively disengage the engaging member from a 
sucking nozzle by exciting (magnetizing) the two electromagnets 
simultaneously, and the other engaging members can also be disengaged from 
respective sucking nozzles independently of each other by exciting 
selected ones of the other electromagnets, if required. 
Preferably, each of the plurality of engaging members is held by the 
engaging member holder in a manner pivotally movable about a horizontal 
pivot thereof and urged in an engaging direction for engagement with a 
corresponding one of the sucking nozzles, the engaging members having a 
plurality of rotatable rollers, respectively, the disengaging means having 
a cam which is rotatable about the vertical axis of the nozzle holder in 
sliding contact with the plurality of rollers, the cam being formed with a 
plurality of protruding portions on a sliding surface thereof in sliding 
contact with the rollers, for pivotally moving selected one of the 
engaging members in a direction opposite to the engaging direction when 
one of the rotatable rollers of the selected one of the engaging members 
is brought into contact with one of the protruding portions of the cam, 
and cam-driving means for moving the cam to a desired rotational angle 
position. 
According to this preferred embodiment, the cam is rotated about the 
vertical axis of the nozzle holder in sliding contact with the plurality 
of rollers to bring one of the plurality of protruding portions formed on 
the sliding surface of the cam into contact with one of the plurality of 
rollers, whereby an engaging member having the roller is pivotally moved 
in the direction opposite to an engaging direction. This pivotal movement 
of the engaging member disengages the engaging member and the sucking 
nozzle from each other. Further, it is possible to simultaneously 
disengage a plurality of sucking nozzles from a plurality of engaging 
members with ease by bringing a plurality of protruding portions into 
contact with a plurality of rollers simultaneously. 
Still preferably, the plurality of sucking nozzles are formed by four 
sucking nozzles arranged circumferentially at intervals of an identical 
distance, and the plurality of protruding portions of the cam are formed 
by two protruding portions formed at diametrically opposite locations 
thereof and one other protruding portion formed at a location other than 
locations circumferentially spaced from the two protruding portions by an 
angle of 90 degrees. 
According to this preferred embodiment, it is possible to position and/or 
correct positions of a plurality of sucking nozzles with ease when a 
plurality of electronic components are to be simultaneously sucked by 
corresponding ones of the sucking nozzles. Further, in the case where the 
two protruding portions formed at diametrically opposite locations on the 
cam are brought into contact with two engaging members engaged with two 
sucking nozzles at the diametrically opposite locations, it is possible to 
simultaneously disengage the two sucking nozzles from the two engaging 
members, while in the case where the one other protruding portion is 
brought into contact with a roller corresponding to one sucking nozzle, 
the two other protruding portions are moved out of contact with other 
rollers, and hence the one sucking nozzle alone is disengaged from the 
corresponding engaging member. Thus, it is possible to selectively carry 
out simultaneous disengagement of two sucking nozzles from corresponding 
engaging members and disengagement of one sucking nozzle from a 
corresponding engaging member. 
To attain the first object, according to a fourth aspect of the invention, 
there is provided an electronic component-mounting apparatus for sucking 
electronic components and mounting the electronic components on a circuit 
board, the electronic component-mounting apparatus comprising: 
a component-feeding block for feeding a plurality of electronic components 
to a sucking position; 
a component-mounting block for selectively sucking at least one of the 
electronic components at the sucking position of the component-feeding 
block, and mounting the at least one of the electronic components having 
been sucked, on a circuit board at a mounting position, the 
component-mounting block having a plurality of mounting heads installed 
thereon; and 
an X-Y moving stage for moving the component-mounting block between the 
sucking position and the mounting position, each of the mounting heads 
having: 
a nozzle holder, 
a plurality of sucking nozzles arranged along an identical circle about a 
vertical axis of the nozzle holder and held by the nozzle holder in a 
manner capable of projecting and retracting vertically, 
an engaging member holder, 
a plurality of engaging members each held by the engaging member holder in 
a manner engageable with the plurality of sucking nozzles, respectively, 
rotating means for rotating the nozzle holder and the engaging member 
holder about the vertical axis of the nozzle holder, 
elevating means for vertically moved the nozzle holder and the engaging 
member holder away from each other, to thereby retract ones of the sucking 
nozzles in engagement with corresponding ones of the engaging members into 
the nozzle holder, and 
disengaging means for disengaging at least one of the plurality of sucking 
nozzles and a corresponding one of the engaging members from each other at 
an arbitrary desired rotational angle position of the nozzle holder and 
the engaging member holder. 
The electronic component-mounting apparatus according to the fourth aspect 
of the invention provides the same effects as obtained by the apparatus 
according to the third aspect of the invention. In addition, since the 
component-mounting block of the present apparatus has the plurality of 
mounting heads installed thereon, it is possible to further decrease the 
frequency of replacing sucking nozzles. 
To attain the second object, according to a fifth aspect of the invention, 
there is provided a mounting head device for an electronic 
component-mounting apparatus comprising: 
a nozzle holder; 
a plurality of sucking nozzles arranged circumferentially about a vertical 
axis of the nozzle holder and held by the nozzle holder in a manner 
capable of projecting and retracting vertically; 
an engaging member holder; 
a plurality of engaging members each held by the engaging member holder in 
a manner engageable with the plurality of sucking nozzles, respectively; 
elevating means for relatively moving the nozzle holder and the engaging 
member holder in vertically opposite directions, to thereby engage the 
engaging members with the sucking nozzles, respectively, when the nozzle 
holder and the engaging member holder are moved toward each other, and 
retract the sucking nozzles into the nozzle holder when the nozzle holder 
and the engaging member holder are moved away from each other; 
disengaging means for preventing engagement between a selected one of the 
engaging members and a corresponding one of the sucking nozzles when the 
nozzle holder and the engaging member holder are moved toward each other, 
in a state of the disengaging means being opposed to the selected one of 
the engaging members; and 
rotating means for rotating the nozzle holder and the engaging member 
holder about the vertical axis of the nozzle holder to thereby move the 
selected one of the engaging members to a position opposed to the 
disengaging means. 
According to this mounting head device, the nozzle holder and the engaging 
member holder are rotated about the vertical axis of the nozzle holder to 
thereby bring an engaging member to be engaged with a sucking nozzle to be 
projected (selected) to a position opposed to the disengaging means, and 
thereafter the nozzle holder and the engaging member holder are moved 
vertically toward each other by the elevating means. Through this 
operation, all the sucking nozzles are once lifted up to a retracted 
position, with only the selected sucking nozzle being prevented from 
engagement with an engaging member corresponding thereto. Then, when the 
nozzle holder and the engaging member holder are relatively moved 
vertically away from each other, the selected sucking nozzle projects 
downward from the nozzle holder. Thus, the mounting head device is capable 
of selectively replacing sucking nozzles by itself without any help of a 
jig or the like. 
Preferably, the nozzle holder having a vertical shaft, the engaging member 
holder being in spline engagement with the vertical shaft of the nozzle 
holder, and the rotating means comprises an electric motor having the 
nozzle holder as a rotor. 
According to this preferred embodiment, it is possible to rotate the 
engaging member holder and the nozzle holder simultaneously in a state 
permitting relative vertical movement of the engaging member holder with 
respect to the nozzle holder. Further, since the rotating means comprises 
an electric motor having the nozzle holder as a rotor, it is possible to 
construct a mounting head device which is compact in size and capable of 
rotating smoothly without shaking. 
To attain the second object, according to a sixth aspect of the invention, 
there is provided a mounting head device for an electronic 
component-mounting apparatus, comprising: 
a nozzle holder; 
a plurality of sucking nozzles arranged along an identical circle about a 
vertical axis of the nozzle holder and held by the nozzle holder in a 
manner capable of projecting and retracting vertically; 
an engaging member holder; 
a plurality of engaging members each held by the engaging member holder in 
a manner engageable with the plurality of sucking nozzles, respectively; 
rotating means for rotating the nozzle holder and the engaging member 
holder about the vertical axis of the nozzle holder; 
elevating means for vertically moving the nozzle holder and the engaging 
member holder away from each other, to thereby retract ones of the sucking 
nozzles in engagement with corresponding ones of the engaging members into 
the nozzle holder; and 
disengaging means for disengaging at least one of the plurality of sucking 
nozzles and a corresponding one of the engaging members from each other at 
an arbitrary desired rotational angle position of the nozzle holder and 
the engaging member holder. 
The mounting head device according to the sixth aspect of the invention 
provides the same effects as obtained by the electronic component-mounting 
apparatus according to the third aspect of the invention. 
The above and other objects, features, and advantages of the invention will 
become more apparent from the following detailed description taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION 
The invention will now be described in detail with reference to the 
drawings showing embodiments thereof. 
Referring first to FIG. 1, there is shown an electronic component-mounting 
apparatus according to a first embodiment of the invention, which is a 
so-called multi-function chip mounter used for mounting various kinds of 
electronic components, such as surface-mounting components including chip 
capacitors, chip resistances, etc., and multilead components of flat 
package ICs. The electronic component-mounting apparatus 1 is comprised of 
a base 2, a conveyor 3 extending transversely on a central area of the 
base 2, a first electronic component-feeding block 4 provided on a 
left-hand end of the base 2 as viewed in FIG. 2, second and third 
electronic component-feeding blocks 5, 6, arranged side by side on a 
right-hand end of the base 2 as viewed in the same, and first and second 
X-Y stages 7, 8 arranged at respective left and right portions of the base 
2. The first X-Y stage 7 has a first head unit 9 installed thereon, and 
similarly, the second X-Y stage 8 has a second head unit 9 installed 
thereon, for sucking and mounting electronic components S. Further, 
component-sensing cameras 11, 11 are also arranged at locations on 
respective longitudinally opposite sides, i.e. on a left side and a right 
side, of the conveyer 3, while nozzle storage devices 12, 12 are arranged 
at locations on respective transversely-opposite sides of the 
component-sensing camera 11 on the left side of the conveyor 3. The 
component-sensing cameras 11, 11 on the left and right sides of the 
conveyor 3 respectively correspond to the first and second head units 9, 
10, and sense or recognize electronic components S sucked by these head 
units 9, 10, to thereby determine whether they are sucked as well as 
correct the angles of the electronic components relative to a horizontal 
plane before they are mounted on the circuit board. 
Further, each nozzle storage device 12 holds various kinds of sucking 
nozzles 41, referred to hereinafter, in stock, to supply sucking nozzles 
for replacing sucking nozzles 41 mounted on the head units 9 and 10 
therewith e.g. when the kind of a circuit board T is changed. The two 
nozzle storage devices 12, 12 may be arranged in axial symmetry with 
respect to the conveyor 3 or in point symmetry with the center of the 
same. In such a case, replacement of mounted sucking nozzles 41 by stored 
sucking nozzles can be simultaneously carried out for the first and second 
head units 9, 10. 
This electronic component-mounting apparatus 1 is supplied with electronic 
components S, which are small in size, such as surface-mounting 
components, at the first and second component-feeding blocks 4, 5, and 
electronic components S, which are large in size, such as multilead 
components, at the third component-feeding block 6. Circuit boards T are 
supplied from the rear side (the upper side as viewed in FIG. 2) and 
delivered forward (downward as viewed in the FIG. 2). For example, when 
the first X-Y stage 7 is operated to mount an electronic component S, the 
first head unit 9 thereon is brought to a selected one of the first, 
second, and third component-feeding blocks 4, 5, 6, from which a 
predetermined electronic component S is sucked thereat, and then the first 
head unit 9 is moved to a predetermined location above the circuit board 
T, from which the electronic component S is mounted on the circuit board 
T. The first X-Y stage 7 and the second X-Y stage 8 are alternately 
operated as circuit boards T are supplied one after another. 
The conveyor 3 includes a table 14 located in the center, a supply passage 
15 located on the rear side, and a delivery passage 16 located on the 
front side. Each circuit board T is supplied to the table 14 from the rear 
side, and set at a predetermined level on the table 14 to have electronic 
components mounted thereon. The circuit board T having the electronic 
components S mounted thereon is delivered forward by way of the supply 
passage 6. During this process, a new circuit board T to be supplied, not 
shown, is on standby in the supply passage 15, and the immediately 
preceding one having the electronic components mounted thereon, not shown, 
is on standby for delivery in the delivery passage 16. Thus, the circuit 
boards T are conveyed forward, one after another. 
On the first and second component-feeding blocks 4, 5, there are arranged a 
lot of tape cassettes 18 in parallel with each other. Each tape cassette 
18 contains a carrier tape, not shown, which carries thereon a large 
number of electronic components S of the same kind at equally-spaced 
intervals. The electronic components S are fed at a predetermined pitch, 
i.e. with predetermined space intervals, from a forward end of each of 
component-feeding blocks 4, 5, one by one. In other words, the electronic 
components S are supplied from the tape cassettes 18 in an aligned manner 
at intervals of an identical distance along a row of the tape cassettes. 
The third component-feeding block 6 has a large number of shelves 20, and 
two trays 21 placed on each of the shelves. Electronic components S are 
contained in each tray 21 in a state aligned with each other. In the case 
of the third component-feeding block 6, the trays 21 on the shelves 20 are 
moved by a transport device, not shown, whereby the electronic components 
S are moved to positions close to the conveyor 3, from which the mounting 
head sucks each of them. 
The first and second X-Y stages 7, 8 have respective X-direction movable 
tables 24, 24, each guided along a pair of guide rails 23, 23 extending 
longitudinally (in the X-axis direction) on the forward and backward ends 
of the base 2. The X-direction movable table 24 of the first X-Y stage 7 
is fitted on a ball screw 25 on the forward side, and an electric motor 26 
connected to the ball screw 25 operates to rotate the ball screw 25 in a 
normal or reverse direction to thereby move the X-direction movable table 
24 in the X-axis direction (in the longitudinal direction). Similarly, the 
X-direction movable table 24 of the second X-Y stage 8 is fitted on a ball 
screw 27 on the rear side, and an electric motor 28 connected to the ball 
screw 27 operates to rotate the ball screw 27 in a normal or reverse 
direction to thereby move the X-direction movable table 24 in the X-axis 
direction. 
The two X-direction movable tables 24, 24 have an identical construction, 
and each of them contains a Y-direction movable unit 29. The Y-direction 
movable unit 29 of the first X-Y stage 7 has the head unit 9 installed 
thereon, and the Y-direction movable unit 29 of the second X-Y stage 8 has 
the head unit 10 installed thereon, whereby as the Y-direction movable 
unit 29 operates, a corresponding one of the head units 9, 10 is moved in 
the Y-axis direction (in the transverse direction). Thus, the head units 
9, 10 are movable both in the X-axis direction and the Y-axis direction, 
i.e. on the horizontal plane. The Y-direction movable unit 29 may be 
embodied by a screw mechanism using a ball screw or the like and an 
electric motor associated therewith for rotating the same, or by a linear 
motor. Similarly, the X-direction movable table 24 may be moved by a 
linear motor. 
The head units 9, 10 each include a support frame 30 mounted on the 
Y-direction movable unit 29, four mounting heads 31, 31, 31, 31 mounted on 
the support frame 30, and one circuit board-sensing camera 32. The 
mounting heads 31, 31, 31, 31 and the circuit board-sensing camera 32 are 
collectively mounted on the support frame 30 at transversely 
equally-spaced intervals. The circuit board-sensing camera 32 senses a 
reference mark on the circuit board T, and a position of the reference 
mark on the circuit board T serves as a reference position with reference 
to which each electronic component is mounted on the circuit board T. The 
circuit board-sensing camera 32 may be used to sense the position of an 
electronic component S to be sucked from the tape cassette 18. 
Each mounting head 31 is, as shown in FIG. 3, comprised of five sucking 
nozzles 41 (only two of them are shown in the figure), a nozzle holder 42 
having the sucking nozzles 41 mounted thereon along the circumference at 
equally-spaced intervals such that each of the sucking nozzles 41 can be 
projected downward and retracted upward, a housing 43 enclosing the nozzle 
holder 42, five engaging hooks 44 for engagement with the sucking nozzles 
41, respectively, and a hook holder 45 holding the five engaging hooks 44. 
The nozzle holder 42 is comprised of a holder body 46, and a spline shaft 
47 extending upward from the holder body 46, with a vacuum passage 48 
which is formed through a central portion extending along the vertical 
axis of the holder body 46 and the spline shaft 47 and connected to a 
vacuum device, not shown. The vacuum passage 48 has branched end portions 
with which only a projected one of the sucking nozzles 41 is communicated. 
On the other hand, arranged between the nozzle holder 42 and the housing 43 
is a stepping motor PM which incorporates the nozzle holder 42 as a rotor 
and the housing 43 as a stator. Therefore, the nozzle holder 42 indexes in 
predetermined angular increments according to the number of steps of a 
pulse signal supplied to the stepping motor PM. This makes it possible to 
bring a projected one of the sucking nozzles 41 or one selected for 
projection to a predetermined position by rotation of the nozzle holder 
42. 
In place of the stepping motor PM, there may be used a servo motor which 
carries sucking nozzles 41 on the rotor thereof such that each of the 
sucking nozzles 41 can be lifted upward or lowered downward i.e. 
vertically moved. 
As described above, the sucking nozzles 41 are arranged in the nozzle 
holder 42 which serves as the rotor, and therefore the sucking nozzles 41 
can be rotated more accurately with less backlash through degrees of an 
angle instructed to the stepping motor PM than in the case of the spline 
shaft 47 being rotated by way of a belt by an electric motor arranged on a 
location of each of the head units 9, 10 other than a location of the 
stepping motor PM. Further, the above construction of the nozzle holder 42 
as the rotor is advantageous in that the head units 9, 10 can be 
constructed without increasing the weight thereof, and designed in 
compact. This advantage is more marked as the number of heads 31 mounted 
on the head units 9, 10 is increased. 
Each sucking nozzle 41 is comprised of a nozzle body 49, and a hook catch 
50 arranged on an upper end of the nozzle body 49. The nozzle body 49 is 
removably mounted on the hook catch 50. A guide rod 51 extends from the 
hook holder 45 through the hook catch 50, and has a coiled spring wound 
around the same. The sucking nozzle 41 is urged downward or in a 
projecting direction by the coiled spring 52. The guide rod 51 is fixed to 
the holder body 46, and at the same time inserted into a hole, not shown, 
formed through the hook holder 45, whereby as the holder body 46 moves 
upward and downward, the guide rod 51 slides in the hole. The hook catch 
50 has an engaging portion 50a formed at an upper end thereof in a manner 
protruded radially outward, for engagement with or disengagement from the 
engaging hook 44. The engaging hook 44 is pivotally mounted on the hook 
holder 45, and at the same time urged in an engaging direction by a spring 
53 interposed between the hook holder 45 and itself. 
Therefore, as the sucking nozzle 41 is moved upward against the urging 
force of the coiled spring 52, the engaging hook 44 is brought into 
engagement with the hook catch 50 by the urging force of the spring 53, 
whereby the sucking nozzle 41 is lifted into a retracted position. From 
this state, when the engaging hook 44 is pivotally moved outward to be 
disengaged from the hook catch 50, the sucking nozzle is moved downward by 
the urging force of the coiled spring 52 into a position projected from 
the nozzle holder 42. The hook holder 45 and the spline shaft 47 of the 
nozzle holder 42 are in spline engagement with each other, whereby as the 
hook holder 42 rotates, the spline shaft 47 rotates in an axially slidable 
manner. 
Now, referring to FIGS. 4A to 4C, the selective replacement of the five 
sucking nozzles 41 on the mounting head 31 will be described. This 
replacement is effected by retracting a projected one of the sucking 
nozzles 41 and at the same time projecting a newly-selected one of them to 
be projected. As shown in the figure, an actuator unit 33 is arranged on 
the support frame 30 in a manner associated with a corresponding one of 
the mounting heads 31, and a stopper arm 34 extends from a portion of the 
support frame 30 located above the actuator unit 33. The mounting head 31 
has its housing 43 fixed to a support block 35 of the actuator unit 33, 
and its hook holder 45 abut on the arm 34 from below whereby the mounting 
head is restricted in respect of an upward movement. The stopper arm has 
forked end portions between which a roller 34a is arranged. That is, the 
stopper arm 34 abuts on the hook holder 45, in a manner preventing the 
hook holder 45 from moving upward and permitting the same to rotate 
thereon. 
The actuator unit 33 contains a linear motor, no shown, and the mounting 
head 31 is moved upward and downward (in a Z-axis direction) by the 
actuator unit 33. Further, from the support block 35 extends upward a 
disengaging member 36 for causing the engaging hook 44 to be pivotally 
moved away (disengaged) from the hook catch 50. As the actuator unit 33 
moves upward and downward, the nozzle holder 42 moves upward and downward 
relative to the hook holder 45 which is prevented by the stopper arm 34 
from moving upward. That is, the mounting head 31, the actuator unit 33, 
the stopper arm 34, and the disengaging member 36 form the mounting head 
device. Further, the actuator unit 33, the stopper arm 34 and the 
disengaging member 36 form a nozzle-replacing device of the invention. 
FIGS. 4A to 4C show the process of causing a projected sucking nozzle 41 on 
the left-hand side as viewed in each of the figures to be retracted upward 
and causing a retracted one on the right-hand side as viewed in the same 
to be projected downward. More specifically, from a state of the mounting 
head where the left-hand sucking nozzle 41 has been selected for use 
(projected downward), with the remaining four sucking nozzles retracted, 
the left-hand sucking nozzle 41 is retracted and one of the remaining four 
sucking nozzles 41 to be selected for use (the right-hand sucking nozzle 
41) is projected. 
First, as shown in FIG. 4A, the nozzle holder 2 and the hook holder 45 are 
rotated to a position where the sucking nozzle 41 to be selected and an 
engaging hook 44 corresponding thereto are opposed to the disengaging 
member 36. Then, the actuator unit 33 is driven to move upward, thereby 
bringing the nozzle holder 42 toward the hook holder 45. The engaging 
portion 50a at the upper end of the left-hand sucking nozzle 41 abuts and 
pushes the engaging hook 44 on the hook holder 45 on the left-hand side in 
FIG. 4A, whereby this engaging hook 44 is once pivotally moved outward or 
in a clockwise direction to permit upward movement of the engaging portion 
50a until the engaging hook 44 is relatively moved over the engaging 
potion 50a and pivotally moved in a counter-clockwise direction to be 
engaged with the hook catch 50, whereupon the actuator unit 33 is stopped. 
In this state, only the engaging hook 44 corresponding to the sucking 
nozzle 41 selected for use is moved away from the hook catch 50 by the 
disengaging member 36 (see FIG. 4B). Then, the actuator unit 33 is moved 
downward to move the nozzle holder 42 in a direction away from the hook 
holder 45. During this process, the sucking nozzle 41 selected for use 
moves downward without being engaged with the engaging hook 44 and the 
other sucking nozzles 41 are engaged with the engaging hooks 44 
corresponding thereto and prevented from moving downward. In short, only 
the right-hand sucking nozzle 41 as shown in the figure is brought to a 
projected position by the urging force of the coiled spring 52 (see FIG. 
4C). 
In this way, the mounting head 31, the actuator 33, and the stopper arm 34, 
and the disengaging member 36 cooperate to selectively replace sucking 
nozzles 41, whereby it is possible to replace or change sucking nozzles 41 
even during travel of the head units 9, 10. Although in the present 
embodiment, one mounting head 31 carries five sucking nozzles 41, this is 
not limitative, but so long as the head units 9, 10 each carry a plurality 
of mounting heads 31, the mounting head 31 may carry a single sucking 
nozzle. Further, so long as one mounting head 31 carries a plurality of 
sucking nozzles 41, each of the head units 9, 10 may has a single mounting 
head installed thereon. 
Although not shown in the figures, the spline shaft 47 of the nozzle holder 
42 is provided with a stopper, whereby the nozzle holder 42 is not 
permitted to move further upward relative to the hook holder from the 
states shown in FIGS. 4A and 4C. The position of the mounting head 31 
shown in FIGS. 4A to 4C is one for selecting (replacing) sucking nozzles 
41, but when an electronic component S is sucked or mounted, the whole 
mounting head 31 is moved further downward. That is, each mounting head 31 
replaces (selects) sucking nozzles 41 at a level higher than the reference 
level L at which the mounting head 31 having sucked an electronic 
component S is moved by the X-Y stage 7 or 8 to a mounting position where 
it is mounted on the circuit board T. 
Therefore, each engaging hook 44 cannot be brought into contact with the 
disengaging member 36 by an operation other than the above-described 
nozzle-replacing operation in which a sucking nozzle 41 corresponding 
thereto is selected for use, and further, the position of the engaging 
hook 44 is not adversely affected by rotation of the nozzle holder 42 
about its vertical axis for positioning or correcting angular position of 
the electronic component S sucked by the sucking nozzle 41. 
The reference level L is defined as a level in which the bottom surface of 
each electronic component S is above the component-sensing camera by a 
distance 1, as shown in FIGS. 5A and 5B. That is, even if electronic 
components S are different in thickness, each electronic component S 
sucked by the sucking nozzle is moved upward until the bottom surface 
thereof reaches the reference level L, and then moved by the X-Y stage 7 
or 8. This ensures that the bottom surface of the electronic component S 
is always set to a constant level, thereby dispensing with the need for 
adjusting the depth of focus of the component-sensing camera 11 and 
enabling the same to recognize the electronic component S with a clear 
image. Further, the top surface of the circuit board T is set to a level 
higher than the position of the component-sensing camera 11 by the 
distance 1, so that in the examples illustrated in FIGS. 5A and 5B, the 
bottom surface of each electronic component S sucked by the sucking nozzle 
41 is recognized at the same level at which the electronic component S is 
mounted in the circuit board S, thereby preventing the position of the 
electronic component S from being deviated horizontally from its proper 
position when it is mounted on the circuit board T due to a difference 
between a level of the sucking nozzle 41 assumed when the electronic 
component S is recognized by the component-sensing camera 11 and a level 
of the same assumed when the electronic component S is mounted. 
Further, after recognition of the electronic component S by the 
component-sensing camera 11, the sucking nozzle 41 is lifted by the 
actuator unit 33 to a level high enough to avoid interference with a 
structure (e.g. members for fixing the circuit board T or the like) of the 
electronic component-mounting apparatus and electronic components S 
already mounted on the circuit board T, and lowered when it is brought to 
a horizontal position where the sucked electronic component S is to be 
mounted. The mounting heads 31 each have its level adjusted by the 
actuator unit 33 provided therefor. Therefore, the electronic component S 
sucked by a sucking nozzle 41 of any of the mounting heads 31 does not 
strike against the electronic components already mounted on the circuit 
board T or the like, and the level of each mounting head can be set to a 
level as low as possible within a range of free of the interference. This 
makes it possible to reduce the lowering stroke of the mounting head 31 
and hence shorten a time period required for mounting each electronic 
component S on the circuit board T. 
Now, the basic operation of the electronic component-mounting apparatus 1 
will be described with reference to FIG. 6, which shows a case where the 
electronic component S is picked up from the second component-feeding 
block 5 and mounted on the circuit board T. In this case, the CPU, not 
shown in the figure, is supplied with data of a position of each tape 
cassette 18, kinds of electronic components S stored in the tape cassette 
18, a position of the circuit board T, various kinds of electronic 
components S to be mounted on the circuit board T and positions therefor 
(including angular positions). According to instructions delivered from 
the CPU, the operations of the X-Y stages 7, 8, the operation of each 
actuator unit 33, the rotation of each nozzle holder 42 (stepping motor 
PM), etc. are controlled. In the following, description of the recognition 
of the electronic component S by the component-sensing camera 11 is 
omitted. Further, in FIG. 6, only one mounting head 31 and only one 
sucking nozzle 41 thereof are shown, but the other mounting heads 31 and 
sucking nozzles 41 are omitted. 
In the example shown in FIG. 6, an electronic component S sucked at a point 
A of the second component-feeding block 5 is mounted at a point P1 of a 
circuit board T set on the table 14. Then, an electronic component S 
sucked at a point B of the second component-feeding block 5 is mounted at 
a point P2 of the circuit board T. In this procedure, first, a selected 
one of the X-Y stages 7 and 8 moves the mounting head 31 from its home 
position to a position exactly above the point A, and then the actuator 33 
lowers the mounting head 31 to suck the electronic component S at the 
point A. After sucking the electronic component S, the actuator unit 33 
lifts the mounting head 31 (to the reference level L), and then the X-Y 
stage 7 or 8 moves the mounting head 31 from the point A to a position 
exactly above the point P1. During the process, the nozzle holder 42 
(stepping motor PM) is rotated to bring the electronic component S to a 
predetermined angular position for mounting. Then, the mounting head 31 is 
lowered again to mount the electronic component S at the point P1. 
Then, the mounting head 31 is moved to the point B to suck another 
electronic component S, and then the electronic component sucked at the 
point B is mounted at the point P2 on the circuit board T. In doing this, 
when the electronic component S supplied at the point B can be handled by 
the same sucking nozzle 41, the electronic component S is mounted in the 
same manner as described above. However, if the electronic component S 
supplied at the point B cannot be handled by the same sucking nozzle 41, 
during the travel of the mounting head from the point P1 to the point B, 
the nozzle holder 42 of the mounting head 31 is rotated to select a 
sucking nozzle 41 (replace one in use by a newly selected one). When the 
mounting head 31 is moved to the point B, the new sucking nozzle 41 is 
operated to suck the electronic component, and then the mounting head 31 
is moved to the point P2 while adjusting the angular position of the 
electronic component S by slight rotation as described above to mount the 
same on the circuit board T. 
The above sucking and mounting operations are carried out by the four 
mounting heads 31 such that electronic components S are successively 
sucked at any of the component-feeding blocks 4, 5, 6, (simultaneously if 
predetermined sucking conditions are satisfied), and then the head unit 9 
or 10 is moved to the circuit board T to successively mount the sucked 
electronic components on the circuit board T, one after another. In doing 
this, to enable as many mounting heads 31 as possible (preferably all 
mounting heads 31) on the head unit 9 or 10 to suck electronic components 
S, replacement of sucking nozzles 31 within each mounting head 31 is 
carried out by rotation of the stepping motor PM (details of the operation 
will be described hereinafter) during travel of the head unit 9 or 10 made 
after the sucked electronic components are mounted and before new 
electronic components are sucked. 
If sucking nozzles 41 on a plurality of mounting units 31 are replaced by 
moving the head unit 9 or 10 which has the mounting heads 31 installed 
thereon and travels in the X-Y direction to the nozzle storage device 12, 
the mounting heads 31 which do not require replacement or exchange of 
sucking nozzles 41 are also moved to the nozzle storage device, since all 
the sucking nozzles 41 are not necessarily required to be replaced at the 
same time, which degrades the efficiency of operation of the electronic 
component-mounting apparatus (particularly when only one mounting head 31 
requires replacement of sucking nozzles thereof). On the other hand, if 
the replacement of sucking nozzles 41 is not carried out, it is not 
possible to take advantage of provision of the plurality of mounting heads 
31 on each head unit 9 or 10 (particularly when the number of mounting 
heads 31 requiring nozzle replacement is large). However, according to the 
present embodiment, if a plurality of sucking nozzles 41 are installed on 
each of the mounting heads 31 within each single unit of the head units 9, 
10, and the plurality of sucking nozzles 41 are constructed to be 
replaceable for use during travel of the head units 9, 10, the nozzle 
storage device 12 is less often used, and electronic components S can be 
sucked by the use of all mounting heads 31 provided on the head units 9, 
10. 
Further, the combination of kinds of sucking nozzles 41 carried by the 
mounting heads 31 within the head units 9, 10 can be determined as 
desired. For example, all the mounting heads 31 may carry an identical 
combination of sucking nozzles 41, or respective different combinations of 
sucking nozzles 41. To make as many kinds of sucking nozzles 41 
replaceable during travel of the head units 9, 10 to thereby suck as many 
kinds of electronic components S as possible, it is only required that 
different kinds of sucking nozzles 41 are provided on the different kinds 
of mounting heads 31. Further, if a lot of electronic components S which 
can be sucked by identical sucking nozzles 41 are to be mounted on a 
circuit board T, at least one such a sucking nozzle 41 may be arranged on 
each of as many mounting heads of the same head unit 9 or 10, whereby many 
of the electronic components S can be sucked by one travel of the head 
unit 9 or 10, and occurrence of one or more unavailable mounting heads 31 
can be made less frequent. In such a case, by providing tape cassettes 18 
supplying the electronic components S which can be sucked by the identical 
sucking nozzles 31, in the same number as the number of mounting heads 31 
carrying the identical sucking nozzles 41, it is possible to suck the 
electronic components S simultaneously, or at least reduce the distance of 
travel of the head unit 9 or 10 by successively sucking the electronic 
components S. 
Next, the correction of position of the mounting head 31 (or sucking 
nozzles 41) for sucking electronic components S will be described with 
reference to FIGS. 7A to 8C. For example, at the tape cassette 18, an 
electronic component held in a recess of the carrier tape is sucked. The 
CPU carries out control such that the sucking nozzle 41 is brought to a 
position facing the center of the recess. Therefore, a slight error in 
operation of feeding the carrier tape, improper position of an electronic 
component S within the recess, a shape of the electronic component S 
difficult to handle, etc. can cause failure of sucking the electronic 
component S. To eliminate this inconvenience, in the present embodiment, 
it is made possible to correct the position of each sucking nozzle 41 in 
which the electronic component S is sucked. Although the recognition of 
the position of the electronic component S to be sucked is carried out 
based on results of recognition by the component-sensing camera 11 
supplied in a feedback manner, this is not limitative, but it may be 
carried out by the circuit board-sensing camera 32 installed on the 
support frame 30. 
FIGS. 7A to 7C show cases where the electronic component S is liable to 
deviate from its proper position along the longitudinal axis of the tape 
cassette 18 due to the shape thereof. That is, when the size of the 
electronic component along the feeding direction (i.e. along the 
longitudinal axis of the tape cassette 18) is short, it is necessary to 
accurately correct the position of the sucking nozzle 41 in this direction 
since the deviation of the sucking nozzle in this direction tends to cause 
failure of sucking the electronic component S. As shown in FIG. 7B, if the 
electronic component S deviates backward from its proper position (shown 
in FIG. 7A), the mounting head 31 (i.e. the nozzle holder 42) is slightly 
rotated counterclockwise from the position shown in FIG. 7A to thereby 
correct the position of the sucking nozzle 41. If the electronic component 
S deviates forward from its proper position as shown in FIG. 7C, the 
mounting head 31 is slightly rotated clockwise from the position shown in 
FIG. 7A to thereby correct the position of the sucking nozzle 41. 
If the head unit 9 or 10 has only one mounting head 31 installed thereon, 
the above correcting operation is not particularly required, since the 
correction of the position of the sucking nozzle 41 can be effected by 
merely moving the X-Y stage 7 or 8. However, if the head unit 9 or 10 
carries a plurality of mounting heads 31, the above correction is very 
useful, since cases are increased where it is possible to suck a plurality 
of electronic components simultaneously. 
Similarly, FIGS. 8A to 8C show cases where the electronic component S is 
liable to deviate from its proper position transversely with respect to 
the longitudinal axis of the tape cassette 18 due to the shape thereof. As 
shown in FIG. 8B, if the electronic component S deviates leftward as 
viewed in the figure from its proper position (shown in FIG. 8A), the 
mounting head 31 (i.e. the nozzle holder 42) is slightly rotated 
counterclockwise from the position shown in FIG. 8A to thereby correct the 
position of the sucking nozzle 41. If the electronic component S deviates 
rightward as viewed in the figure from its proper position as shown in 
FIG. 8C, the mounting head 31 is slightly rotated clockwise from the 
position shown in FIG. 8A to thereby correct the position of the sucking 
nozzle 41. 
It should be noted that even if the mounting head 31 carries only one 
sucking nozzle 41, so long as the sucking nozzle 41 is arranged at a 
location remote form the center of rotation of the mounting head 31 
(rotational position about the axis of the mounting head 31), the above 
correction can be effected. 
Thus, according to the present embodiment, the mounting head 31 is rotated 
by the stepping motor PM incorporated in the mounting head 31 to correct 
the position of the sucking nozzle 41. Therefore, the electronic component 
S can be sucked by a central portion thereof, which minimizes the 
possibility of failure of sucking of the electronic component S. 
Next, referring to FIGS. 9A to 9D, special methods of sucking electronic 
components S by the electronic component-mounting apparatus according to 
the present embodiment will be descried. As described above, each X-Y 
stage carries four mounting heads 31 thereon. Therefore, it is possible to 
simultaneously suck a plurality of electronic components S from the 
component-feeding block 4, 5 or 6 by using the plurality of mounting heads 
31. Further, even if the electronic components S are not sucked 
simultaneously, all the mounting heads may be successively caused to suck 
an electronic component at the component-feeding block 4, 5 or 6, and 
thereafter brought to the circuit board T. 
FIGS. 9A to 9D show cases where two of the mounting heads 31, 31 are used 
to simultaneously suck electronic components S at the second 
component-feeding block 5 (or the first component-feeding block 4). The 
tape cassettes 18 on the second component-feeding block 5 are all 
constructed to have an identical width, and arranged side by side 
immediately close to each other. On the other hand, the mounting heads 31 
are arranged at a pitch (distance d2 between the mounting heads) twice as 
large as a pitch of the tape cassettes (distance d1 between the tape 
cassettes). Further, the diameter of a circular path of rotation of the 
sucking nozzles 31 is equal to the pitch (distance d1) at which the tape 
cassettes 18 are arranged. 
Therefore, when the sucking nozzles 41, 41 of the two mounting heads 31, 31 
adjacent to each other are rotated such that they are closest to each 
other, the distance between the sucking nozzles 41, 41 becomes equal to 
the distance d1, and therefore it is possible to simultaneously suck 
electronic components S by the use of the mounting heads 31, 31 adjacent 
to each other (see FIGS. 9A and 9B). Further, when the sucking nozzles 41, 
41 of the mounting heads 31, 31 adjacent to each other are rotated to 
respective left-hand or right-hand positions with respect to a row of the 
tape cassettes 18, the distance between the two sucking nozzles 41, 41 
become equal to the distance d2 (2.times.d1), and therefore it is possible 
to suck electronic components S from respective tape cassettes 18, 18 on 
opposite sides of one tape cassette 18 (see FIGS. 9A and 9C). Further, by 
rotating the sucking nozzles 41, 41 of the mounting heads 31, 31 adjacent 
to each other such that they become most distant from each other, the 
distance between the sucking nozzles 41, 41 becomes equal to a distance d3 
(=3.times.d1), and therefore it is possible to suck electronic components 
S from two tape cassettes 18, 18 at respective locations spaced by two 
tape cassettes (see FIGS. 9A and 9C). 
Even if the diameter of a circular path of rotation of the sucking nozzles 
about the axis of each mounting head 31 is not equal to the distance of 
the pitch of arrangement of the tape cassettes 18 (distance d1), so long 
as the diameter of a circular path of rotation of sucking nozzles 41 about 
the axis of the mounting head is larger than the pitch (distance d1), it 
is possible to rotate selected sucking nozzles 41 of mounting heads 31 to 
respective positions where they can suck electronic components 
simultaneously from tape cassettes 18. 
Thus, it is possible not only to simply suck electronic components S 
simultaneously by the use of a plurality of mounting heads 31, but also to 
select tape cassettes 18 from which electronic components S are sucked by 
rotating the sucking nozzles 41 about the vertical axis of each mounting 
head 31 and thereby changing positions of the sucking nozzles 41 in a 
suitable manner. Therefore, although it is not always possible to mount 
electronic components S by sucking them simultaneously, simultaneous 
sucking of electronic components can be carried out more often by 
selecting the electronic components to be simultaneous sucked. The 
increased frequency of simultaneous sucking is particularly useful for a 
divisible circuit board having a plurality of identical circuit boards 
arranged side by side. 
Next, referring to FIGS. 10A to 10D, a variation of the present embodiment 
using another method of simultaneous sucking of electronic components will 
be described. In this variation, two sucking nozzles 41, 41 positioned 
along the circumference of each mounting head 31 are used to suck 
electronic components S from the four tape cassettes 18, 18, 18, 18. In 
this case, although not particularly shown, a pair of disengaging members 
36 are provided on each mounting head 31, and one of them is constructed 
such that it can move to or back from an engaging hook 44 corresponding 
thereto and the other is constructed as described hereinabove. Further, 
the vacuum passage 48 is formed such that it is communicated with the two 
sucking nozzles projected simultaneously. That is, the mounting head with 
the two sucking nozzles 41, 41 projected out is used to suck electronic 
components S simultaneously. 
FIG. 10B shows a case where the two sucking nozzles 41, 41 positioned at 
diametrically opposite locations are used. In this variation, the pair of 
disengaging members are arranged on diametrically opposite locations of 
the mounting head 31. First, a total of four sucking nozzles 41, 41, 41, 
41 of mounting heads 31, 31 adjacent to each other are rotated such that 
they are aligned on a row of four tape cassettes parallel with each other. 
In this state, the four sucking nozzles 41, 41, 41, 41 are spaced from 
each other by the distance d1, and electronic components S are 
simultaneously sucked from C1 to C4 cassettes 18, 18, 18, 18. 
On the other hand, FIGS. 10C and 10D show a case where two sucking nozzles 
arranged at respective locations of each mounting head 31 shifted from 
each other by an angle of 90 degrees about the vertical axis thereof. In 
this variation, the aforementioned pair of disengaging members are 
arranged at respective locations of the mounting head 31 shifted from each 
other by an angle of 90 degrees about the vertical axis thereof. First, 
one sucking nozzle 41 of each of the mounting heads 31 is rotated to a 
left-hand position as viewed in FIG. 10C whereby electronic components S 
are simultaneously sucked from C1 and C3 tape cassettes 18, 18. Then, the 
other sucking nozzle 41 of each of the mounting heads is rotated to a 
right-hand position as viewed in FIG. 10D whereby electronic components 
are simultaneously sucked from C2 and C4 tape cassettes 18, 18. In this 
case, when one sucking nozzle 41 of each mounting head 31 sucks an 
electronic component S, the other sucking nozzle 41 is positioned away 
from the tape cassettes so as not to interfere with same, whereby 
simultaneous sucking of electronic components can be carried out by 
two-step simultaneously-sucking operations. 
As shown in FIGS. 4A and 4C, even when the sucking nozzles are retracted, 
tips thereof are slightly protruded from the nozzle holder 41. Therefore, 
by constructing the vacuum passage 48 such that a desired sucking nozzle 
can be selectively communicated therewith, a sucking nozzle having an 
electronic component sucked thereat can be retracted without releasing the 
sucked electronic component. Therefore, when one sucking nozzle carries 
out sucking of an electronic component, the other may be retracted to a 
position away from the tape cassettes to thereby avoid interference with 
the tape cassettes 18. That is, in FIG. 10B, the sucking nozzles at the 
left-hand positions of the mounting heads 31 are projected, and at the 
same time the sucking nozzles at the right-hand positions of the same are 
retracted. In this state, first, electronic components S are 
simultaneously sucked from the C1 and C3 tape cassettes 18, 18, and then 
the sucking nozzles 41 at the left-hand positions are retracted and at the 
same time the sucking nozzles 41 at the right-hand positions are 
projected, whereby electronic components S are simultaneously sucked from 
the C2 and C4 tape cassettes 18, 18. Thus, simultaneous sucking of 
electronic components can be carried out by two-step 
simultaneously-sucking operations. 
As described above, by employing not only the method of simultaneously 
sucking electronic components but also the method of sucking them by 
divisional simultaneously-sucking operations, it is possible to markedly 
reduce the times of traveling of the head units 9, 10 between the tape 
cassettes 18 and the circuit board T to thereby reduce the tact time of 
mounting electronic components S. 
Next, a second embodiment of the invention will be described with reference 
to FIG. 11. This embodiment is distinguished from the first embodiment in 
construction of the mounting head 31. The remainder of the arrangement of 
the present embodiment is identical with the first embodiment, and hence 
description thereof is omitted. Reference numeral 35 designates a support 
block of the actuator unit 33 on which a first stepping motor M1 is 
mounted. The first stepping motor M1 has a housing 61 as a stator, and a 
rotary arm 62 as a rotor. The rotary arm 62 is rotated about the vertical 
axis thereof. The rotary arm 62 has lower part formed into two forked 
portions between which a horizontal shaft 64 rotatably extends with a 
nozzle holder 63 arranged thereon. 
The nozzle holder 63 has a peripheral surface on which a plurality of 
sucking nozzles 65, 65 are arranged in a manner projecting in radial 
directions. Arranged between one end of the horizontal shaft 64 of the 
nozzle holder 63 and a lower end of one of the forked portions of the 
rotary arm 62 is a second stepping motor M2 which includes the one end of 
the horizontal shaft 64 as a rotor and the lower end of one of the forked 
portions of the rotary arm 62 as a stator. Therefore, the nozzle holder 63 
is rotated about the longitudinal axis of the horizontal shaft 64 through 
a predetermined rotational angle according to the number of pulses of a 
pulse signal supplied to the second stepping motor M2. This enables the 
mounting head 31 to selectively replace one sucking nozzle 65 by another 
for use, independently, i.e. without being driven by an external device. 
Further, the rotary arm 62 has a vacuum passage 67 formed therethrough for 
communication with only a sucking nozzle 65 selected and facing downward 
to thereby enable the sucking nozzle to suck an electronic component by 
vacuum. In the first embodiment, selection of a sucking nozzle and setting 
of an angular position of the sucking nozzle 41 can be effected by one 
motor. In the second embodiment, however, the two kinds of rotating 
operations require respective motors. Therefore, when each motor has a 
large weight, the first embodiment is advantageous over the second 
embodiment. 
As described above, according to the second embodiment, even when the 
mounting head 31 (head units 9, 10) are in motion, it is possible to carry 
out selective replacement of sucking nozzles, and hence reduce time for 
replacement of sucking nozzles. As a result, it is possible to minimize 
the tact time of mounting electronic components S on the circuit board T, 
and markedly reduce the tact time of the whole process carried out by the 
electronic component-mounting apparatus 1 of multi-function type. 
Next, a third embodiment of the invention will be described with reference 
to FIGS. 12 to 14. 
This embodiment is distinguished from the first and second embodiments in 
constriction of the mounting head. The remaining arrangement is identical 
with the preceding embodiments, and hence detailed description thereof is 
omitted. 
As shown in FIG. 12, each mounting head 31 is comprised of a nozzle holder 
42 having four sucking nozzles 41 arranged at circumferentially spaced 
intervals such that each of them can project downward and retract upward, 
a housing 43 enclosing the nozzle holder 42, four engaging hooks (engaging 
member) 44 engageable with the sucking nozzles 41, respectively, a hook 
holder 45 (engaging member holder) supporting the engaging hooks 44, and a 
disengaging mechanism 161 (disengaging means) for disengaging the engaging 
hook 44 from the sucking nozzle 41 associated therewith. 
The nozzle holder 42 is comprised of a holder body 46, and a spline shaft 
47 integral with and extending upward from the holder body 46. A vacuum 
passage 48 extends through the central portions of the holder body 46 and 
the spline shaft 47 along the vertical axis. Further, the vacuum passage 
48 has four branched end portions extending radially outward for 
communication with the inside of each sucking nozzle 41 only when it is 
projected outward or downward. 
On the other hand, between the nozzle holder 42 and the housing 43, there 
is arranged a stepping motor PM (rotating means) which includes the nozzle 
holder 42 as a rotor and the housing 43 as a stator. Therefore, the nozzle 
holder 42 rotates relative to the housing 43 through a predetermined angle 
according to the number of steps of a pulse signal supplied thereto. This 
enables a selected sucking nozzle 41 to be brought to a desired position. 
Further, since the spline shaft 47 of the nozzle holder 42 is in spline 
engagement with the hook holder 45, the hook holder 45 is rotated in 
unison with the nozzle holder 42 and at the same time the two members 42, 
45 are vertically movable relative to each other. 
It should be noted that in place of the stepping motor PM, there may be 
used a servo motor which carries sucking nozzles 41 on the rotor thereof 
such that each of them can be lifted upward or lowered downward. 
As described above, the sucking nozzles 41 are arranged in the nozzle 
holder 42 which serves as the rotor, and therefore the sucking nozzles 41 
can be rotated more accurately with less backlash through degrees of an 
angle instructed to the stepping motor PM than in the case of the spline 
shaft 47 is rotated by way of a belt by an electric motor arranged on a 
location of each of the head units 9, 10 other than a location of the 
stepping motor PM. Further, the above construction of the nozzle holder 42 
as the rotor is advantageous in that the head units 9, 10 can be 
constructed without increasing the weight thereof, and designed in 
compact. This advantage is more marked as the number of heads 31 mounted 
on the head units 9, 10 is increased. 
Each sucking nozzle 41 is comprised of a nozzle body 49, and a hook catch 
50 arranged on an upper end of the nozzle body 49. The nozzle body 49 is 
removably mounted on the hook catch 50. A guide rod 51 extends from a rod 
holder 162 fixed to the spline shaft 47 through the hook catch 50. Between 
the hook catch 50 and the rod holder 162, a coiled spring is interposed 
such that it is wound around the guide rod 51. The sucking nozzle 41 is 
urged downward or in a projecting direction by the coiled spring 52. The 
bottom of the hook catch 50 abuts on the top of the holder body 46 when it 
is brought to a lower most position, whereby the downward motion of the 
sucking nozzles 41 relative to the holder body 46 is restricted. 
The hook catch 50 has an engaging portion 50a formed at an upper end 
thereof in a manner protruded radially outward, for engagement with or 
disengagement from the engaging hook 44. The engaging hook 44 is pivotally 
mounted on the hook holder 45, and at the same time urged in an engaging 
direction by a spring 53 interposed between the hook holder 45 and itself. 
As shown in FIGS. 12 and 13, the disengaging mechanism 161 is arranged such 
that it encloses the engaging hooks 44. The disengaging mechanism 161 is 
comprised of eight electromagnets 163 arranged at circumferentially spaced 
intervals. Each electromagnet 163 has a ring portion 163a formed of 
magnetic material, such as iron, a core portion 163b protruded radially 
outward from the ring portion 163a, and a coil 163c wound around the core 
portion 163b. The energization of electromagnets 163 is controlled by an 
electromagnet control device, not shown, whereby they are excited 
(magnetized) and degaussed (demagnetized) independently of each other. On 
the other hand, on an outer surface of the engaging hook 44, an attracting 
member 164 formed of magnetic material, such as iron, is mounted at a 
location opposed to a corresponding one of the electromagnets 163. 
According to the above arrangement, when one of the electromagnets 163 is 
excited by energization of the coil 163c, the magnetism of the 
electromagnet 163 attracts the attracting member 164 opposed thereto to 
thereby cause the engaging hook 44 to be pivotally moved to the 
electromagnet 163. Thus, the engaging hook can be disengaged from the 
engaging portion 50a of the hook catch 50. 
Although in the present embodiment, the disengaging mechanism 161 is formed 
of eight electromagnets, this is not limitative, but assuming that four 
sucking nozzles 41 are used, the minimum five electromagnets 163 
surrounding the engaging hooks 44 can disengage even one of the engaging 
hooks 44 positioned to face a boundary between the two electromagnets 163. 
Further, it is possible to prevent other engaging hooks from being 
unnecessarily disengaged. 
The mounting head 31 constructed as above is mounted on the support arm 30 
as shown in FIGS. 14A to 14C. That is, in a manner corresponding to each 
mounting head 31, on the support frame 30, there are arranged an actuator 
unit 33 (elevating means) incorporating a linear motor, not shown, a 
stopper arm 134, and a support block 35. The support block 35 is lifted or 
lowered by the actuator unit 33 along a guide 136. The mounting head 31 is 
fixed to the support block 35 at a portion of the housing 43, and hence it 
is moved in unison with the support block 35 by the actuator unit 33. The 
stopper arm 134 restricts the upward movement of the mounting head 31 of 
the hook holder 45. 
Next, referring to FIGS. 13A, 13B, and FIGS. 14A to 14C, the operation of 
the mounting head 31 constructed as above will be described. FIGS. 14A to 
14C show a sequence of operations of the mounting head from a step of 
sucking an electronic component S by a sucking nozzle 41 thereof from the 
second component-feeding block 5, to a step of mounting the electronic 
component on the circuit board T. FIG. 14A shows a state of the mounting 
head 31 immediately after an electronic component S is sucked by 
projecting a sucking nozzle 41 on a right-hand side as viewed in the 
figure. In doing this, first, the nozzle holder 42 is held in a lifted 
position (as shown in FIG. 14B) by the actuator unit 33 whereby all the 
sucking nozzles 41 are projected from the nozzle holder 42. 
Then, the head unit 9 is moved by the first X-Y stage 7 to bring the 
sucking nozzle 41 on the right-hand side selected for sucking to a 
position exactly above a predetermined tape cassette 18 at the second 
component-feeding block 5. If the sucking nozzle 41 deviates from its 
proper position slightly, the nozzle holder 42 can be rotated through a 
small angle to correct the position of the sucking nozzle 41. Then, only 
the electromagnet corresponding to the sucking nozzle 41 (one 163 on the 
right-hand side appearing in FIG. 14A) is excited by the electromagnet 
control device, not shown. The magnetism of the electromagnet 163 attracts 
the attracting member 164 thereto, whereby the engaging hook 44 is 
pivotally moved to the electromagnet 163 and attached thereto. This 
disengages the engaging hook 44 on the right-hand side from the engaging 
portion 50a of the hook catch 50. 
Then, the actuator unit 33 is operated to lower the nozzle holder 42. The 
sucking nozzle 41 on the right-hand side disengaged from the engaging hook 
44 corresponding thereto is lowered by the urging force of the coiled 
spring 52 to move after the nozzle holder 42 whereby it maintains a state 
projected from the nozzle holder 42. On the other hand, the other sucking 
nozzles 41 are prevented from lowering by the engaging hooks 44 
respectively in engagement therewith, and held at respective lifted 
positions. As a result, they are retracted into the nozzle holder 41 (see 
FIG. 14A). This causes only the sucking nozzle 41 on the right-hand side 
to be projected, and thereafter, the nozzle holder 42 is further lowered 
to suck an electronic component S by the projected sucking nozzle 41 (see 
FIG. 14A). As is clear from the above operations of the mounting head 31, 
the coiled spring 52 interposed between the hook catch 50 and the rod 
holder 62 does not directly cause the sucking nozzle 41 to be projected 
from the nozzle holder 42, but causes the same to follow or move after the 
downward motion of the nozzle holder 42, and serves as a cushion for 
absorbing a shock which can occur when each sucking nozzle 41 sucks an 
electronic component or mounts the sucked electronic component S on the 
circuit board T. 
Then, when the sucking of another electronic component by another sucking 
nozzle 41 is carried out, first, the exited or magnetized electromagnet 
163 is demagnetized, and at the same time, the nozzle holder 42 is moved 
upward. As the nozzle holder 42 is moved upward, the hook catch 50 on the 
right-hand side causes the engaging hook 44 to be pivotally moved 
counterclockwise against the urging force of the spring 53, and then the 
hook catch 50 engages with the engaging hook 44. From this state, when 
sucking is carried out by a sucking nozzle 41 on a left-hand side as 
viewed in the figure, for example, similarly to the above, this sucking 
nozzle 41 is brought to a position exactly above a selected tape cassette 
18 and then a corresponding electromagnet 163 (one 163 on the left-hand 
side appearing in FIG. 14C) alone is excited, followed by lowering the 
nozzle holder 42. By repeatedly carrying out the above operations, it is 
possible to cause all the four sucking nozzles 41 to suck selected 
electronic components S thereat. 
In the example illustrated in FIG. 13A, the engaging hook 44 engaged with 
the sucking nozzle 42 selected for use is opposed to one electromagnet 
163, so that the former 44 is magnetized by the latter 163 alone. 
Depending on the rotational position of the nozzle holder 42 and the 
engaging hooks 44, as shown in FIG. 13B, one engaging hook 44 can be 
opposed to two electromagnets 163, 163 in a manner spreading across a gap 
between them. In such a case, the two electromagnets 163, 163 may be 
simultaneously excited to thereby disengage the engaging hook 44 from the 
hook catch 50 corresponding thereto with ease. 
Further, as shown in FIG. 14A, if conditions of simultaneously sucking 
electronic components S by two sucking nozzles 41, 41 are fulfilled, e.g. 
if the distance between the sucking nozzles 41, 41 is equal to a pitch or 
distance between tape cassettes 18, 18 containing electronic components S 
to be sucked, the engaging hooks 44, 44 can be simultaneously disengaged 
by simultaneously magnetizing the electromagnets 163, 163 corresponding to 
these sucking nozzles 41, 41, to thereby enable these sucking nozzles 41, 
41 to carrying simultaneous sucking. 
After sucking electronic components S by all the sucking nozzles 41, the 
mounting head or the head unit is moved on a horizontal plane with the 
nozzle holder 42 held in a lifted state to bring the sucking nozzles to a 
position exactly above a position for mounting one of the electronic 
components on the circuit board T. In this case as well, the deviation of 
the position of each sucking nozzle 41 can be corrected by a slight 
rotation of the nozzle holder 42. 
FIGS. 14B, 14C show a case where the sucking nozzle 41 on the left-hand 
side mounts an electronic component sucked thereat on a circuit board T. 
After positioning of the sucking nozzle 41, similarly to the case of 
sucking, the electromagnet 163 corresponding thereto is excited or 
magnetized to thereby disengage the engaging hook 44 (see FIG. 14B) from 
the hook catch 50, and then the nozzle holder 42 is lowered to thereby 
retract the other sucking nozzles 41. Then, the projected sucking nozzle 
41 on the left-hand side is operated to mount the electronic component S 
on the circuit board T. Thereafter, the same operation is repeatedly 
carried out to cause the other sucking nozzles 41 to mount the remaining 
electronic components S on the circuit board T, thereby completing the 
mounting of the electronic components S on the circuit board T. 
As described above, according to the electronic component-mounting 
apparatus 1 of the present embodiment, by lowering the nozzle holder 42, 
only a sucking nozzle 41 which is disengaged from an corresponding 
engaging hook 44 is caused to be projected out to thereby suck and mount 
an electronic component S. The disengagement of the sucking nozzle 41 from 
the engaging hook 44 corresponding thereto can be carried out instantly by 
exciting (magnetizing) selected one of eight electromagnets 163 regardless 
of the rotational angle of the nozzle holder 42 and the hook holder 45. 
Therefore, compared with the case of rotating the nozzle holder 44 and the 
hook holder 45 to disengage the sucking nozzle 41 from the engaging hook 
44 corresponding thereto, a time period required in disengaging the 
sucking nozzle 41 from the engaging hook 44 can be shortened, to thereby 
reduce the tact time of mounting electronic components S. 
Further, when simultaneous sucking of electronic components by a plurality 
of sucking nozzles 41 is carried out, it is possible to instantly 
disengage the plurality of sucking nozzles 41 from the engaging hooks 44 
by simultaneously magnetizing a plurality of corresponding electromagnets 
163. Therefore, the time period required in the disengagement of the 
engaging hooks 44 can be further reduced, to thereby further reduce the 
tact time of mounting electronic components. 
FIG. 15B shows essential parts of an electronic component-mounting 
apparatus according to a fourth embodiment of the invention. This 
embodiment is distinguished from the third embodiment in that as the 
disengaging mechanism for disengaging a sucking nozzle 41 from an engaging 
hook 44 corresponding thereto, a cam mechanism is employed in place of the 
electromagnet 163. More particularly, a disengaging mechanism 72 
(disengaging means) is comprised of a hollow cylindrical cam 73 which is 
rotatable about its vertical axis common to a nozzle holder 42, and a cam 
drive mechanism 74 (cam drive means) for rotating the hollow cylindrical 
cam 73 to a desired rotational angle position. 
The hollow cylindrical cam 73 is placed on a roller 76 which is rotatably 
mounted on the inside of each engaging hook 44 by a pin 75, and as shown 
in FIG. 15A, it has its bottom formed with three protruding portions 77a, 
77b, 77c. The protruding portions 77a and 77b are arranged at 
diametrically opposite locations, and the remaining protruding portion 77c 
is located at a location other than one remote from the protruding 
portions 77a and 77b by an angle of 90 degrees about the vertical axis of 
the hollow cylindrical cam 73. 
The cam drive mechanism 74 is comprised of a belt 79 stretching between a 
pulley 78 integrally formed with the hollow cylindrical cam 73 and a 
stepping motor, not shown, for driving the belt 79. Therefore, by 
controlling the number of steps of a pulse signal supplied to the stepping 
motor, the hollow cylindrical cam 73 can be rotated to a desired angular 
position. The remaining arrangement of the electronic component-mounting 
apparatus is identical with that of the first embodiment. 
According to the above arrangement, by operating the stepping motor, the 
rotation of the hollow cylindrical cam 73 can be controlled, whereby at 
least one of the protruding portions 77a, 77b, and 77c can be brought into 
contact with the roller 76 of a desired engaging hook 44. Accordingly, the 
engaging hook 44 mounted on the roller 76 abutting on the protruding 
portion 77a, 77b or 77c is pivotally moved in a direction opposite to an 
engaging direction, whereby the sucking nozzle 41 corresponding thereto is 
disengaged from the engaging hook 44. 
Further, as is apparent from the arrangement of the protruding portions 
77a, 77b, and 77c, the protruding portion 77c is used for disengaging only 
one sucking nozzle, while the protruding portions 77a and 77b are used for 
simultaneously disengaging two sucking nozzles 41. That is, when the 
protruding portion 77c is brought into contact with a roller 76 
corresponding to a single sucking nozzle 41, the other protruding portions 
77a and 77b are away from the other rollers 76, whereby the single sucking 
nozzle 41 and the corresponding engaging hook 44 alone can be disengaged 
from each other. FIG. 15B shows a state in which the protruding portion 
77c is brought into contact with the roller 76 corresponding thereto to 
cause only the left-hand sucking nozzle 41 to be projected out. 
On the other hand, when two protruding portions 77a, 77b are brought into 
contact with rollers 76, 76 of two engaging hooks 44, 44 in engagement 
with two sucking nozzles 41, 41 at diametrically opposite locations, the 
protruding portion 77c is made away from the other rollers 76, whereby the 
two sucking nozzles 41 and the corresponding engaging hooks 44 can be 
disengaged from each other. 
As described above, according to the present embodiment, by rotating the 
hollow cylindrical cam 73, one or a plurality of sucking nozzles can be 
disengaged instantly from corresponding engaging hook(s) regardless of 
rotational angular positions of the nozzle holder 42 and the hook holder 
45 relative to each other. Therefore, in the same manner as the first 
embodiment, time required for disengagement can be reduced and the tact 
time of mounting electronic components S on the circuit board T can be 
shortened. 
The present invention is not limited to the above embodiments, but it can 
be practiced in various ways. For example, although in the third and 
fourth embodiments, one mounting head carries four sucking nozzles, this 
is not limitative, but the number of sucking nozzles can be increased or 
decreased as required. In such a case, according to the increased or 
decreased number of sucking nozzles, the number of electromagnets in the 
third embodiment, and the number of protruding portions of the hollow 
cylindrical cam in the fourth embodiment can be increased or decreased. 
It is further understood by those skilled in the art that the foregoing are 
preferred embodiments of the invention, and that various changes and 
modification may be made without departing from the spirit and scope 
thereof.