Head assembly for a component mounter

Provided is a component mounter having a plurality of revolving nozzle spindles, which can simultaneously pick up and mount two or more electronic components. A head assembly for the component mounter includes: a base frame; a rotary housing rotatably mounted on the base frame and having spindle receiving holes vertically formed at regular intervals at the same radius from a center thereof; a plurality of nozzle spindles having lower ends to which nozzles for picking up electronic components are coupled, and received in the spindle receiving holes such that the plurality of nozzle spindles rotate on the same axis when the rotary housing rotates; a housing rotating mechanism rotating the rotary housing; and a nozzle lifting mechanism including a nozzle lift driving unit, and a clutch part that moves according to the operation of the nozzle lift driving unit and can simultaneously press down and lower the plurality of nozzle spindles.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a component mounter, and more particularly to a head assembly for a component mounter.

2. Description of the Related Art

As is known in the surface mount technology (SMT) art, a component mounter receives various components from a component supplier, feeds the received components to certain positions of a printed circuit board (PCB), and mounts the components on the PCB.

In general a component mounter includes: a component supplying part that supplies electronic components to be mounted, a conveyor part that carries a PCB on which the electronic components are to be mounted, and a head assembly that successively picks up the electronic components from the component supplying part and mounts the electronic components on the PCB.

Recently, a plurality of nozzle spindles installed on a head assembly of the component mounter is provided to either successively or simultaneously pick up a plurality of electronic components, move the plurality of electronic components to a conveyor part simultaneously, and either successively or simultaneously mount the plurality of components on a PCB in an effort to improve the efficiency of a component mounter.

However, by increasing the component mounter's efficiency through increasing the number of nozzle spindles, the total size of the head assembly increases as well. Therefore, there is a trade-off in increasing the number of nozzle spindles installed on the head assembly.

Various known component mounters attempt to increase mounting efficiency without unduly increasing the size of the head assembly. For example, as illustrated inFIG. 1, a head part10disposed on a component mounter disclosed in Japanese Patent Laid-Open Publication No. hei 2003-273582 includes three revolving head assemblies11that are aligned. A number of nozzle spindles40are disposed in a generally circular arrangement in each head assembly11so that the spindles40of each head assembly11are rotated about a common vertical central axis by a corresponding nozzle rotating mechanism60. Pickup nozzles50are coupled to lower portions of the nozzle spindles40. The nozzle spindles40of the respective head assemblies11are selected by nozzle selecting mechanisms70, and lowered by nozzle lifting mechanisms80. The head assemblies11are fixed to a head frame12.

The head assemblies11of the component mounter10will be described in further detail with reference toFIG. 2. One head assembly11includes a plurality of nozzle spindles40installed in a circular orientation about a spline shaft35.

A nozzle holder50is coupled to the spline shaft35. The nozzle spindles40are disposed to move up and down in the same circle about the spline shaft35of the nozzle holder50.

The spline shaft35rotates according to the operation of a nozzle rotating mechanism60, which generally acts as a nozzle rotating motor, and accordingly, the nozzle spindles40and the nozzle holder50coupled to the spline shaft35rotate.

In the meantime, to individually select and lower one of the nozzle spindles40, the nozzle selecting mechanism70and the nozzle lifting mechanism80are disposed on the head assembly11. The nozzle selecting mechanism70includes a compressed air supply chamber71and a nozzle selecting valve72for controlling the injection of compressed air into a pressurized air supply chamber32corresponding to a selected nozzle spindle40. Here, the pressurized air supply chamber32is a space formed inside an air cylinder block30that is coupled to the head assembly11and disposed on the nozzle holder50, and can be connected to each of the nozzle spindles40.

Accordingly, if air under positive pressure is introduced into the pressurized air supply chamber32disposed on the selected nozzle spindle40, a piston52formed in the pressurized air supply chamber32and an air cylinder shaft53coupled under the piston52are lowered, such that a lower end53aof the air cylinder shaft53, an upper end50aof the selected nozzle spindle40attached to the lower end53a, and a top surface85aof a stepped portion of a spline nut85are positioned at the same level, resulting in making the air cylinder shaft53, the nozzle spindle40, and the spline nut85integrated into one body. Here, the spline nut85is coupled to the nozzle lifting mechanism80including a cam follower84, an eccentric cam82, and a driving motor81, such that the spline nut85can vertically move. Thus, the nozzle spindle40coupled to the spline nut85can be lowered.

Further, a vacuum suction unit90helps the nozzle spindles40to pick up electronic components. The vacuum suction unit90causes air under negative pressure from a negative pressure air supply chamber91to be individually provided into the nozzle spindles40by picking up-and-mounting valves92installed outside the nozzle holder50, such that the nozzle spindles40can individually pick up the electronic components.

As can be appreciated from the foregoing, revolving head assemblies have a small size and can mount a plurality of electronic components. However, the conventional head assembly11for the component mounter employs the nozzle lifting mechanism80including the eccentric cam82, the cam follower84, and the spline nut85to lower the nozzle spindles40, thereby resulting in a complex lifting mechanism and a low mounting speed.

Furthermore, since the number of air cylinder shafts53directly corresponds with the number of nozzle spindles40, the size of the head assembly11is increased so that it may be difficult to pick up and mount a plurality of components simultaneously, thereby decreasing a mounting speed of the assembly11.

Moreover, since the head assembly11, which includes the eccentric cam82, the cam follower84, and the spline nut85, employs a number of picking up-and-mounting valves92in direct correspondence with the number of nozzle spindles40, the total weight of the head assembly11is increased, and the head assembly11occupies a considerable space so that the assembly11may be difficult to be applied to various work conditions.

SUMMARY OF THE INVENTION

The present invention provides a head assembly for a component mounter, which includes a plurality of revolving nozzle spindles for simultaneously picking up and mounting two or more electronic components.

The present invention also provides a head assembly that increases a mounting speed for a component mounter, the head assembly including: a nozzle lifting mechanism for lowering one or more of a plurality of nozzle spindles; a rotary housing mechanism for rotating the plurality of nozzle spindles about a common axis; and a nozzle rotation mechanism for rotating each of the plurality of nozzle spindles on its own axis.

The present invention also provides a head assembly for a component mounter, which includes fewer components to reduce a total weight and can be used as a module.

According to an aspect of the present invention, there is provided a head assembly for a component mounter, the head assembly comprising a base frame, a rotary housing, a plurality of nozzle spindles, a housing rotating mechanism, and a nozzle lifting mechanism.

The rotary housing is rotatably mounted on the base frame and has spindle receiving holes vertically formed at regular intervals at the same radius from a center thereof. Each spindle of the plurality of nozzle spindles includes a lower end having a nozzle for picking up electronic components. Each spindle is received in a spindle receiving hole such that the plurality of nozzle spindles has a circular arrangement and rotates about a common central axis when the rotary housing rotates. The housing rotating mechanism rotates the rotary housing. The nozzle lifting mechanism includes a nozzle lift driving unit, and a clutch part that moves according to the operation of the nozzle lift driving unit and can simultaneously press down and lower the plurality of nozzle spindles.

The clutch part may be operable to lower one or more of the plurality of nozzle spindles.

The clutch part may comprise: a clutch shaft moving up and down according to the operation of the nozzle lift driving unit; and a clutch plate disposed at one end of the clutch shaft and having a size for at least pressing down two adjacent nozzle spindles simultaneously and pressing down only one nozzle spindle.

The head assembly may further comprise a nozzle rotating mechanism that rotates each of the nozzle spindles on its own lengthwise axis, wherein the nozzle rotating mechanism comprises: a nozzle rotation driving unit mounted on the base frame; a nozzle driving gear connected to the nozzle rotation driving unit; and nozzle driven gears fitted around outer circumferences of the nozzle spindles and connected to the nozzle driving gear such that the nozzle driven gears rotate when the nozzle driving gear rotates. The nozzle rotating mechanism may further comprise a ring gear rotating relative to the rotary housing, wherein the ring gear has an outer circumferential surface having an outer gear part that engages with the nozzle driving gear, and an inner circumferential surface having an inner gear part that engages with each of the nozzle driven gears.

According to another aspect of the present invention, there is provided a head assembly for a component mounter, the head assembly comprising a base frame, a rotary housing, a plurality of nozzle spindles, a nozzle rotation driving unit, a nozzle driving gear, nozzle driven gears, and a ring gear.

The rotary housing is rotatably mounted on the base frame and has spindle receiving holes vertically formed at a predetermined arcuate spacing about a common circumference. The plurality of nozzle spindles include lower ends having nozzles for picking up electronic components, and the spindles are disposed in the spindle receiving holes for picking up and mounting the electronic components. The nozzle rotation driving unit is mounted on the base frame. The nozzle driving gear is connected to the nozzle rotation driving unit.

The nozzle driven gears are fitted around outer circumferences of the nozzle spindles. The ring gear rotates relative to the rotary housing and includes an outer circumferential surface having an outer gear part that engages with the nozzle driving gear, and an inner circumferential surface having an inner gear part that engages with each of the nozzle driven gears.

According to still another aspect of the present invention, there is provided a head assembly for a component mounter, the head assembly comprising: a base frame; a rotary housing rotatably mounted on the base frame and having spindle receiving holes vertically formed at regular intervals at the same radius from a center thereof; a plurality of vertically movable nozzle spindles, each including a first end having a nozzle for picking up electronic components, the spindles received in the spindle receiving holes such that the plurality of nozzle spindles rotate about a common central axis when the rotary housing rotates; and a housing rotating mechanism including a housing rotation driving unit mounted on the base frame, a housing driving gear connected to the housing rotation driving unit, and a housing driven gear mounted on the rotary housing and rotating in connection with the housing driving gear, the housing rotating mechanism adapted to rotate the rotary housing.

According to yet another aspect of the present invention, there is provided a head assembly for a component mounter, the head assembly comprising: a base frame; a rotary housing rotatably mounted on the base frame and having spindle receiving holes vertically formed therein at a regular spacing at the same radius from a center thereof; a plurality of nozzle spindles received in the spindle receiving holes such that the nozzle spindles revolve about the center thereof when the rotary housing rotates, and each spindle including a first end having a nozzle for picking up electronic components; a housing rotating mechanism including a housing rotation driving unit and a gear assembly comprising a plurality of gears that rotate according to the operation of the housing rotation driving unit for rotating the rotary housing; a nozzle rotating mechanism including a nozzle rotation driving unit mounted on the base frame and a gear assembly composed of a plurality of gears that rotate according to the operation of the nozzle rotation driving unit for rotating each of the nozzle spindles on it own lengthwise axis; and a nozzle lifting mechanism including a nozzle lift driving unit coupled to an upper portion of the rotary housing of the base frame, and a clutch part vertically moving according to the operation of the nozzle lift driving unit to selectively press down and lower one or a plurality of nozzle spindles.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings, in which various embodiments of the invention are shown.

FIG. 3is a plan view of a component mounter including a head assembly according to an embodiment of the present invention.FIG. 4is a perspective view of the head assembly shown inFIG. 3. Referring toFIGS. 3 and 4, a component mounter100includes head assemblies200, a bed101, and horizontally moving mechanisms103. The bed101may include a component supplying part102which supplies electronic components, and a conveyor part106which feeds a printed circuit board B in an X-axis direction. Here, each of the head assemblies200for the component mounter100includes a plurality of nozzle spindles, each spindle having a first end on which a nozzle is installed, for picking up the electronic components resting on the component supplying part102and mounting the picked-up components on the printed circuit board B.

The horizontally moving mechanisms103are coupled to the bed101. The horizontally moving mechanisms103horizontally move the plurality of head assemblies200(i.e., the mechanisms103move each of the assemblies200in the X and Y directions) generally between component pickup positions of the component supplying parts102and various positions on the printed circuit board B.

Each of the horizontally moving mechanisms103may include an X-axis moving mechanism104horizontally moving the head assembly200in the X-axis, and a Y-axis moving mechanism105horizontally moving the head assembly200in the Y-axis. For example, as known in the art, the X-axis and Y-axis moving mechanisms104,105may be linear servomotors or the like.

In this case, the head assemblies200may be coupled to the X-axis moving mechanisms104such that the head assemblies200can horizontally move along the X-axis moving mechanisms104. Here, the X-axis moving mechanisms104are mounted on the Y-axis moving mechanisms105to horizontally move, such that both ends of each of the X-axis moving mechanisms104intersect the Y-axis moving mechanisms105at right angles. Accordingly, if the X-axis moving mechanisms104move along the Y-axis moving mechanisms105, the head assemblies200mounted on the X-axis moving mechanisms104horizontally move in the Y-axis. Also, the head assemblies200horizontally move in the X-axis along the X-axis moving mechanisms104. The foregoing described coupling of the assemblies200to the mechanism104,105is exemplary and may be otherwise so long as the assemblies200move along the X-Y plane.

As best illustrated inFIG. 4, each of the head assemblies200includes a base frame210, a rotary housing220, and a plurality of nozzle spindles230. The base frame210, which horizontally moves when the X-axis moving mechanism104and the Y-axis moving mechanism105move, is generally coupled to the X-axis moving mechanism104. The rotary housing220is coupled to the base frame210and is rotated therein by a housing rotating mechanism240.

Spindle receiving holes222are formed vertically in the housing220and are spaced arcuately thereabout at regular intervals at the same radius from a center O (FIG. 5B) of the rotary housing220. The nozzle spindles230are disposed in the spindle receiving holes222. As shown inFIG. 4, there are eight spindles230disposed in the eight holes222so that adjacent spindles230are arcuately spaced apart by forty-five degrees. Fewer or additional holes222and/or spindles230may be provided as desired for a particular component mounting process.

Nozzles232are disposed at lower portions of the nozzle spindles230. The nozzles232move downward when disposed over the component supplying part102to pick up electronic components. The nozzles232then move upward, horizontally move, and move downward again when disposed over the printed circuit board B to mount the picked-up electronic components on the board B.

Accordingly, the nozzle spindles230move vertically to lower and raise the nozzles232. To this end, as shown inFIG. 4, a nozzle lifting mechanism250is disposed on the head assembly200. The nozzle lifting mechanism250may include a nozzle lift driving unit251and a clutch part255. The clutch part255is coupled to the nozzle lift driving unit251, which may include a motor such as a voice coil motor (VCM) or the like, such that the clutch part255can move down to either lower one nozzle spindle230or simultaneously lower more than one nozzle spindles. Indeed, although the clutch part255is illustrated and described herein as moving one or two nozzle spindles230, the clutch part255may be sized and shaped otherwise to simultaneously or sequentially lower two or more of the plurality of spindles230for mounting a plurality of electronic components on the printed circuit board B.

The clutch part255may include a clutch shaft256and a clutch plate258that are coupled together, but the shaft245and plate258may be integrally formed. The clutch shaft256vertically moves according to the operation of the nozzle lift driving unit251. The clutch plate258is disposed at one end of the clutch shaft256(e.g., the lower end as illustrated), and has a flat shape to press down either one nozzle spindle230or two adjacent nozzle spindles230based on the rotational orientation of the rotary housing220relative to the shaft256as will be explained in further detail hereafter.

As further illustrated inFIG. 4, the head assembly200includes a housing rotating mechanism240. The rotary housing220is rotated by the housing rotating mechanism240and the nozzle spindles230disposed in the rotary housing220accordingly revolve about a common vertical central axis (O inFIGS. 5B,6B). Thus, for example, after one nozzle spindle230picks up an electronic component, the rotary housing220is revolved through a predetermined angle by the housing rotating mechanism240so that one or more other nozzle spindles230are positioned over the component supplying part102to pick up electronic components, thereby enabling all the nozzle spindles230to pick up electronic components so that number of trips that the spindles make between the supplying part102and the PCB is minimized.

Further, the head assembly200includes a nozzle rotating mechanism260that rotates each of the nozzle spindles230on its own lengthwise (i.e., vertical) axis. As the nozzle spindle230is rotated by the nozzle rotating mechanism260, the nozzle spindle230can mount the electronic component on the most accurate position and most accurate orientation (e.g., rotation) on the printed circuit board B, which will be explained later.

The nozzle lifting mechanism250will be explained with reference toFIGS. 5A through 6B.FIGS. 5A and 5Billustrate arrangements of the nozzle spindles230of the nozzle lifting mechanism250when the clutch plate258simultaneously lower two adjacent nozzle spindles. Referring toFIGS. 5A and 5B, the nozzle lift driving unit251is mounted on the base frame210over the rotary housing220. The clutch part255is coupled to the nozzle lift driving unit251and is interposed between the nozzle lift driving unit251and the nozzle spindles230so that the spindles230move up and down according to the operation of the nozzle lift driving unit251.

The rotary housing220is disposed under the clutch part255. As best illustrated inFIG. 5B, the plurality of spindle receiving holes222are formed at regular intervals (i.e., forty-five degrees apart) at the same radius R from the center O of the rotary housing220. The nozzle spindles230are received in the spindle receiving holes222such that each of the nozzle spindles230can rotate on its own lengthwise vertical axis (generally indicated by the + sign in the center of each spindle230). The rotary housing220is rotated by the housing rotating mechanism240(seeFIG. 4), and the nozzle spindles230connected to the rotary housing220accordingly revolve about the central axis O. In this case, a bearing (e.g., a bearing cone or the like) may be disposed between the rotary housing220and the base frame210as will be described later.

As shown inFIG. 5B, the clutch plate258is positioned directly above a circle defined by the centers of the plurality of nozzle spindles230. Thus, to lower two adjacent nozzle spindles230, both ends of the clutch plate258cooperate to press down the adjacent nozzle spindles230such that the two adjacent nozzle spindles230are simultaneously lowered as the clutch plate258moves down.

As shown inFIG. 5B, the clutch plate258may be generally rectangular in shape and have a length L that is greater than a distance K1 between closest ends of the adjacent nozzle spindles230and less than a distance K2 between farthest ends of the adjacent nozzle spindles230so that the clutch plate258has a small size but can simultaneously press down the two adjacent nozzle spindles230. Accordingly, the housing rotating mechanism240rotates the rotary housing220to place the two nozzle spindles230at half index positions, and then the clutch plate258moves down to simultaneously press down and lower the two nozzle spindles230. Although the clutch plate258is shown to be rectangular inFIGS. 4,5B and6B, the clutch plate258may be shaped otherwise. For example, as shown inFIGS. 5A and 7, the clutch plate258may be parallelogram-shaped, an annular-shaped arcuate portion, or the like to provide sufficient contact with the one or more spindles230therebelow.

Further as shown inFIGS. 6A and 6B, for the clutch plate258to lower one nozzle spindle230, the clutch plate258should have a length L that is selected so that the clutch plate258does not contact other adjacent nozzle spindles when contacting the one nozzle spindle230. Further, to prevent the clutch plate258from depressing more than one spindle230, the selected nozzle spindle230is oriented below a central portion of the clutch plate258. To this end, the housing rotating mechanism240rotates the rotary housing220to place the selected one nozzle spindle230at a full index position, and then the clutch plate258moves down to press down and lower the single, selected nozzle spindle230.

Accordingly, one clutch plate can simultaneously actuate (i.e., lower) two nozzle spindles as well as a single, selected nozzle spindle as desired without changing the structure of the clutch plate. In addition, since springs234can be fitted around outer circumferences of the nozzle spindles230so that when the clutch plate258does not press down the nozzle spindles230, the nozzle spindles230are lifted and return to their original positions via a spring bias.

Referring now toFIGS. 7 and 8, one can appreciate that the rotary housing220can be rotated using a driving motor and a gear assembly driven by the driving motor. As shown, the housing rotating mechanism240may include a housing rotation driving unit242, a housing driving gear244and a housing driven gear248. The housing rotation driving unit242(e.g., a motor with a rotating shaft) is mounted on the base frame210and the housing driving gear244is disposed at one end of the housing rotation driving unit242. Then, the housing driving gear244connected to the housing rotation driving unit242rotates accordingly when the housing rotation driving unit242rotates.

The housing driven gear248is coupled with the rotary housing220and rotates in response to the housing driving gear244. In this case, the housing driven gear248may be fitted around an outer circumferential surface of or otherwise coupled with the rotary housing220.

At least one connecting gear246may be disposed between the housing driving gear244and the housing driven gear248. The at least one connecting gear246may be selected to minimize the size of the head assembly200. Alternatively, the at least one connecting gear246may be substituted with a belt, chain or other suitable transmission means capable of coupling the gears244,248.

To ensure smooth rotation and prevent binding of the rotary housing220in the base frame210for preventing backlash between the connecting gear246and the housing driven gear248, at least one bearing212(e.g., a bearing cone) may be provided and disposed between the rotary housing220and the base frame210.

In the operation of the illustrated housing rotating mechanism240, if the housing rotation driving unit242is driven, the housing driving gear244disposed at the one end of the housing rotation driving unit242begins to rotate. Accordingly, the at least one connecting gear246which engage with the housing driving gear244and the housing driven gear248which engage with the connecting gear246begin to rotate. Since the housing driven gear248is coupled to the outer circumference of the rotary housing220, the rotary housing220rotates.

In addition to the foregoing described rotation of the housing220and all of the nozzle spindles230, each of the nozzle spindles230rotates on its own lengthwise vertical axis to mount electronic components at accurate positions. To this end, as shown inFIGS. 9 and 10, the nozzle rotating mechanism260may be employed in the head assembly200.

The nozzle rotating mechanism260may comprise a plurality of gears that rotate in response to the operation of the nozzle rotation driving unit262. That is, the nozzle rotating mechanism260basically includes the nozzle rotation driving unit262(e.g., a motor with a rotating shaft or the like), a nozzle driving gear264, and a plurality of nozzle driven gears268, and may further include a ring gear266. Since the nozzle driving gear264is disposed at one end of the nozzle rotation driving unit262that is typically a driving motor, the nozzle driving gear264rotates according to the operation of the nozzle rotation driving unit262. Also, each of the plurality of nozzle driven gears268is fitted around an outer circumferential surface of each of the plurality of nozzle spindles230.

In one exemplary embodiment, the nozzle driving gear264may be positioned at a center of the nozzle driven gears268to engage directly with all of the nozzle driven gears268. Here, if the nozzle driving gear264rotates according to the operation of the nozzle rotation driving unit262, the nozzle driven gears268rotate, and as a result, the nozzle spindles230rotate.

In the illustrated embodiment ofFIGS. 9 and 10, the nozzle driving gear264and the nozzle driven gears268may be coupled together via the ring gear266that can rotate relative to the rotary housing220. The ring gear266has a generally annular shape and may be fitted around the outer circumferential surface of the rotary housing220. An outer gear part266aformed on an outer circumferential surface of the ring gear266couples with the nozzle driving gear264and an inner gear part266bformed on an inner circumferential surface of the ring gear266couples with each of the nozzle driven gears268.

Here, at least one connecting gear265may be employed to couple the ring gear266and the nozzle driving gear264. The number of the connecting gears265may be selected to reduce the total size of the head assembly200. The at least one connecting gear265transfers a rotational force of the nozzle driving gear264to the ring gear266. Alternatively, the at least one connecting gear265may be substituted with a belt, chain or other suitable transmission means capable of coupling the gears264,266.

Here, it is preferable that the nozzle driven gears268, the ring gear266, and the connecting gear265be structured not to cause backlash among gears engaging therewith.

In the operation of the exemplary illustrated nozzle rotating mechanism260, the nozzle driving gear264disposed at the one end of the nozzle rotation driving unit262and the connecting gear265engaging with the nozzle driving gear264rotate according to the operation of the nozzle rotation driving unit262. Accordingly, the ring gear266having the outer gear part266aengaging with the connecting gear265rotates, and as a result, the nozzle driven gears268rotates by engaging with the inner gear part266bof the ring gear266. Since the nozzle driven gears268may be fixed to the outer circumferential surfaces of the nozzle spindles230, the nozzle spindles230rotate as well.

According to the various embodiments discussed herein, one can appreciate that a plurality of components can be simultaneously picked up thereby increasing a mounting speed.

Furthermore, since in the various embodiments the nozzle spindles are lowered using the clutch shaft and the clutch plate, one can appreciate that the head assembly simplifies lowering and raising of the nozzle spindles, thereby reducing manufacturing costs and the total size of the head assembly.

Moreover, since the nozzle spindles rotate about a common axis and each spindle rotates on its own axis, the various embodiments of the head assembly provide for adjustment of the rotation and placement location for the picked-up components, thereby improving the quality of the PCB products made by the component mounter.

In addition, the weight and size are reduced of the various embodiments of the head assembly since the embodiments discussed herein are not pneumatic including a plurality of valves, nozzle plates and the like that are typically attached to the outside of the head assembly for lowering and raising of the nozzle spindles. Further, the total size is reduced for the various embodiments of the head assembly so that the head assembly can be adapted for use with various component mounters as a head assembly module.