Tape feeder, electronic component mounting apparatus using the same, and method of feeding electronic components

A tape feeder feeds electronic components by advancing a tape intermittently. The tape feeder comprises a motor controller for controlling a motor, which rotatively drives a sprocket to advance the tape, and a communication unit for receiving a control signal from a control unit of an electronic component mounting apparatus and transmitting a control parameter such as a rotating speed, an amount of rotation, and acceleration and deceleration pattern to the motor controller. The tape feeder has such a structure that a tape advancing speed and an amount of tape advancement are easily changeable according to a type of the electronic components by changing the control parameter of the rotating speed and the amount of rotation of the motor. In addition, the tape feeder is adaptable for correction of the amount of rotation according to a result of measurement of pin position of the sprocket, so as to properly interrupt turning of the sprocket at the correct stop position for accurate positioning of the electronic components into the right pick-up location all the time.

FIELD OF THE INVENTION

The present invention relates to a tape feeder for feeding electronic components borne on a tape by advancing them intermittently to a pick-up location in an electronic component mounting apparatus. The invention also relates to a method of advancing the tape.

BACKGROUND OF THE INVENTION

In an electronic component mounting apparatus, a tape feeder is used as a commonly known method of feeding electronic components into a pick-up location of a nozzle of transfer head. In this method, a tape bearing the electronic components is pulled out of a supply reel, and fed to the nozzle by advancing it intermittently in synchronization with mounting timing of the electronic components. This tape feeder intermittently advances the tape only a predetermined amount by rotating a sprocket, which is in engagement with feedholes perforated in the tape.

In using tape feeders, it is a general practice to prepare a number of tape feeders of the same kind, and any of these tape feeders are mounted to a plurality of electronic component mounting apparatuses as needed. In other words, when taking a certain feeder mounting base of the electronic component mounting apparatus as an example, a number of the tape feeders that are adaptable for installation are mounted to it. These tape feeders supply electronic components to the transfer head by advancing the tapes toward a pick-up location.

Because there are various types of electronic components having different sizes, it is necessary to prepare many kinds of tape feeders according to widths of the tapes that bear the electronic components as well as mount pitches of the electronic components along the tapes. However, the conventional tape feeder requires a complicated operation to change a distance of advancement of the sprocket, when the tape requires a different advancing pitch due to a difference in the type of electronic components even if the tape used has the same dimension widthwise. In addition, it is desirable to set an advancing speed and acceleration of the tape appropriately according to the type of electronic components, since there is a risk that the components will move out of their normal positions and result in a failure to stably pick-up the components depending on the type of electronic components and the operation during advancement of the tape. However, it is not possible to make such a setting of the tape advancing speed easily with the conventional tape feeders.

In many of these tape feeders, there are tape advancing errors due to individual instrumental errors, and a position of the advanced tape does not always come into alignment with the pick-up location of the transfer head. Mechanical adjustments are therefore necessary, such as alignment of a positioning dowel for each of the tape feeders in the prior art, and they require a great effort if many tape feeders are involved.

SUMMARY OF THE INVENTION

In an electronic component mounting apparatus, a tape feeder supplies electronic components to a pick-up location by intermittently advancing a tape bearing the electronic components. The tape feeder comprises: a sprocket in engagement with feedholes perforated at regular pitches in the tape, for advancing the tape; a drive mechanism including a motor as a driving force for rotatively driving the sprocket; and a motor controller for controlling the motor. The tape feeder further has any of the following features.A) The tape feeder is provided with a communication unit for receiving a control signal from an external device.B) The tape feeder draws data on an amount of rotation of the motor corresponding to a position where turning of the sprocket is interrupted, based on a result of measurement of a pin position of the sprocket.

In a method of feeding electronic components using the tape feeder provided with the above feature “A”, the tape feeder changes control parameter of the motor by communicating a control signal between the motor controller for controlling the motor and a control unit in the electronic component mounting apparatus during the step of advancing the tape intermittently by turning the sprocket with the drive mechanism having driving force of the motor.

A method of feeding electronic components using the tape feeder of the above feature “A” comprises measuring a pin position of the sprocket when the sprocket is interrupted from turning, as an electronic component is advanced to a pick-up location. Data on an amount of rotation of the motor corresponding to the position where turning of the sprocket is interrupted is drawn based on a result of measurement of the pin position.

In addition, an electronic component mounting apparatus includes the tape feeder provided with any of the above features “A” and “B”.

DETAILED DESCRIPTION OF THE INVENTION

First of all, a structure of an electronic component mounting apparatus is described with reference to FIG.1. InFIG. 1, the electronic component mounting apparatus1(hereinafter referred to as “mounting apparatus”) comprises component feeder unit2for supplying electronic components. The component feeder unit2has a plurality of tape feeders4mounted to a top surface of feeder base3. Any of the tape feeders4pulls out carrier tape7bearing electronic components from supply reel6installed on truck5placed under the feeder base3. The tape feeder4delivers the electronic components borne thereon to a pick-up location of transfer head8.

Head drive unit11actuates the transfer head8, which then mounts an electronic component picked up from the tape feeder4onto substrate10placed on conveyor track9. Control unit14controls the head drive unit11. Storage unit15stores various data necessary for the transfer head8to perform mounting operation and the tape feeder4to perform advancing operation of the tape.

The data include tape data15A, stop position data15B, pick-up location data15C, and mounting position data15D, as shown in FIG.3.

The tape data15A represent such data as an advancing pitch and an advancing speed for intermittent advancement of the carrier tape7, an acceleration and deceleration pattern during the intermittent advancement, and the like. This data is pre-set individually for each kind of the carrier tapes7.

The stop position data15B is correction data used to alleviate deviation or displacement of a stop position of the tape during the intermittent advancement due to instrumental error inherent in each of the tape feeders. The electronic components borne on the carrier tape7are precisely aligned with the pick-up location by making a correction with this data. In this exemplary embodiment, this correction is made on deviation of the pin position of the sprocket that forwards the tape in a direction of the tape advancement.

The pick-up location data15C is data representing a pick-up location of the tape feeder4where the transfer head8sucks and picks up the electronic components. The pick-up location data is prepared in advance for each of the tape feeders, so as to make a correction of the instrumental error inherent in each of the tape feeders. In this exemplary embodiment, the correction is made due to deviation or displacement in a direction orthogonal to the direction of the tape advancement (among deviations in various directions) of the pin position of the sprocket, by aligning a pick-up location of the transfer head8.

The mounting position data15D is data relating to coordinates of a mounting position of the electronic component in the substrate10.

Camera12is installed above the pick-up location of the tape feeder4. The camera12takes a photographic image of the pick-up location and the vicinity thereof, and recognition unit13performs a recognition process of the photographic image data. Through this process, the recognition unit13discerns a location of a feedhole of the carrier tape7, a pin position of the sprocket for advancing the tape, and the like, so as to detect an extent of deviation, or displacement, from the regular position. The control unit14calculates stop position data and pick-up location data based on the amount of deviation of each of the pin positions as a result of the detection transferred to the control unit14.

Referring now toFIG. 2, FIG.3andFIG. 4, tape feeder4will be described next. As shown inFIG. 2, the tape feeder4comprises main body4A having a rectangularly slender shape and fixture unit4B installed under the main body4A. The main body4A is mounted parallel to an upper surface of the feeder base3, and the fixture unit4B is positioned securely by engaging it to one end of the feeder base3. Feeder control unit24built into the main body4A is connected with the control unit14of the mounting apparatus1through connector28provided in the fixture unit4B. The storage unit15transfers data to the feeder control unit24via the control unit14, including data such as the tape data15A and the stop position data15B that are necessary for controlling operation of the tape feeder4.

The tape feeder4is provided with sprocket21at the forward end. The sprocket21has pins21A at regular pitches around its periphery for engaging feedholes7B (refer toFIG. 7) provided also at regular pitches along the carrier tape7for advancement of the tape. In addition, the sprocket21is provided with toothed surface21B on its side (refer toFIG. 4) engaging a bevel gear23attached to a drive shaft of motor22. The bevel gear23and the toothed surface21B compose a drive mechanism that drives sprocket21.

The motor22, when rotatively driven, turns the sprocket21, which advances the carrier tape7. This advancement pulls out the carrier tape7from the supply reel6. The pulled-out carrier tape7is guided into the tape feeder4from its rear end, and moved forward along a tape-feeding passage.

The motor22used in this preferred embodiment is a type that is capable of controlling a rotation speed and an amount of rotation, such as a servomotor. An advancing speed and an advancing pitch for intermittent advancement of the carrier tape, a stop position during the intermittent advancement, and the like can be set freely as desired by controlling the rotation speed and the amount of rotation of the motor22. The motor22is also provided with an encoder with the capability of detecting an absolute position, and it can detect individually a rotational displacement of each of the pins21A on the sprocket21.

There is a pick-up location at the forward end of the tape feeder4, where the transfer head8picks up electronic components. The carrier tape7guided here is advanced intermittently under cover plate29placed on the upper surface of the forward end. The transfer head8picks up an electronic component16disposed in a recess7A of the carrier tape7through a cutout portion29A in the cover plate29(refer toFIG. 5A) between the intermittent advancements. Prior to picking up of the electronic component16, a cover tape (not show in these figures) is peeled away from an upper surface of the carrier tape7, pulled backward, and stored into a storage container (not show in the figures) housed in the main body4A.

A control system of the tape feeder4is constructed as described next with reference to FIG.3. The tape feeder4contains feeder control unit24. The feeder control unit24is provided with motor controller25, communication unit27and data storage unit26. The motor controller25controls motor22for driving the sprocket21. The communication unit27receives a control signal from the control unit14in the mounting apparatus1, and transfers to the motor controller25such control parameters as a rotation speed, an amount of rotation and the like of the motor22. Accordingly, the motor controller25changes advancing speed, advancing pitch, and so forth of the tape feeder4from time to time according to the kind of carrier tape7used, as directed by the control unit14.

In addition, the communication unit27performs a process of writing the data sent from the control unit14into the data storage unit26. Therefore, when sending a command regarding control parameters to the motor controller25, all that is needed is a simple command indicating the kind of carrier tape used, so that the motor controller25can change the advancing speed and the advancing pitch, if the data storage unit26stores tape data15A of that particular carrier tape.

According to this exemplary embodiment as described above, a control signal is transmitted from the external device to the motor controller which controls the motor, in the process of turning the sprocket and advancing the tape intermittently by the drive mechanism capable of controlling the rotation speed and amount of rotation using a motor as the driving force. This structure makes it possible to easily change the advancing speed and advancing distance of the tape by changing the control parameters such as the rotating speed and the amount of rotation of the motor according to the electronic components to be mounted. Therefore, the mounting apparatus is flexibly adaptable to the change of a type of electronic components it handles.

The stop position data15B will be described next. In order to deliver electronic components16borne on the carrier tape7to the correct position, the pin21A is required to stop at the proper position during intermittent turning of the sprocket21. However, there are certain deviations in positions of the individual pins21A of the sprocket21due to manufacturing error. It is therefore necessary to correct the deviations to bring each of the pins21A to a stop at the right position. In this exemplary embodiment, the necessary correction is made by using camera12to discern a position of each of the pins21A on the sprocket21, and to obtain an amount of deviation in the position.

The deviation in position of each of the pins21A is measured in a manner as described hereinafter.FIG. 5Ashows an upper surface of the cover plate29disposed above the sprocket21. InFIG. 5A, dotted lines illustrate a tape bearing an electronic component in the delivered position. When the camera12takes a photographic image of the cutout portion29A without the carrier tape7set in position, it catches an image of one of the pins21A located at or near a top area of the sprocket21, and thus a position of this pin21A is measurable.

The measurement gives pin offset data Δx and Δy representing a deviation of the pin21A in the directions of the X-coordinate and the Y-coordinate, respectively, from the regular position, as shown in FIG.5B. Offset data indicating a deviation of every one of the pins21A from the regular position can be obtained in the same manner by measuring the deviation of each pin one after another while turning the sprocket21intermittently at intervals of a predetermined pitch. This can thus provide a proper position of each of the pins21A, that is, a stop position where a turning motion of the sprocket21is to be interrupted (stopped) during the intermittent advancement of the tape, when each of the electronic components comes to the correct pickup location. Calculation is now made to obtain data for an amount of rotation of the motor22corresponding to each of the stop positions, as stop position data, and this stop position data obtained here is stored as offset data peculiar to the particular tape feeder4. Accordingly, the motor22is controlled and its rotation interrupted based on the offset data, so as to stop the pins21A at the correct stop position all the time when the tape feeder4is under operation.

The control unit14performs a process of computing this data in the mounting apparatus1. Thus, the control unit14serves as a stop position datacomputing unit. A result of the computation is stored in the storage unit15of the mounting apparatus1as the offset data representing amounts of positional deviations. At the same time, these amounts of positional deviations are converted into another form of offset data with a number of pulses representing the amounts of rotation of the motor22, and are sent to each of the tape feeders4. The data is hence written into the data storage unit26via the communication unit27in each of the tape feeders4. Accordingly, the storage unit15of the mounting apparatus1and the data storage units26of the individual tape feeders4serve as stop position data storage units.

With reference to FIG.5A throughFIG. 6B, the feature described next pertains to modes of the stop position data and the pick-up location data. As described here, offset data in the direction of the Y-coordinate corresponds to the stop position data, and offset in the direction of the X-coordinate corresponds to the pick-up location data. InFIG. 6A, measurement is made on positions of all the pins21A of the sprocket21in the tape feeder, for which the data is to be prepared, and the measured pin positions are processed statistically to obtain mean positional data of the pin positions. In other words, mean values ΣΔx/n and ΣΔy/n of the offset data Δx and Δy of the individual pins are obtained, and a mean value of the offset data is used as a single offset data peculiar to this particular tape feeder. Thus, the data processing can be made easily by taking statistical process of the pin positional data and obtaining only one set of offset data peculiar to that tape feeder.

FIG. 6Bshows an example in which offset data is stored for each of the pins21A of the sprocket21. That is, the offset data Δx and Δy are stored exactly as they are measured, in the storage unit15as the offset data (i.e. stop position data15B and pick-up location data15C) peculiar to these particular pins21A in this example. In the illustrated instance, the stop position data is produced for the individual pins21A with their deviations reflected as they are. Therefore, these deviations are corrected in order to make the carrier tape7stop at the right position at all times even if there are large deviations in the pin positions of the sprocket21due to manufacturing error.

What has been discussed in this preferred embodiment is an example which uses distances of deviations of the pins21A as the stop position data. However, the stop position data can also be obtained by taking a photographic image of an area in the cutoff portion29A with the carrier tape7set in position, and measuring either a position of the recess7A or a position of the electronic component16disposed in the recess7A. Offset data sets Δx and Δy obtained in this case are distances of deviations of the electronic component16from the regular pick-up location.

FIG. 7shows a method of correcting the stop position of the carrier tape7based on the stop position data and the pick-up location data, as discussed above, with the tape feeder4in operation. To stop the pins21A of the sprocket21at the right position during intermittent advancing, the motor22is controlled according to the above-mentioned stop position data for proper positioning. In other words, the motor22is stopped at a stop position corresponding to the position where the correction is made only by a distance of the offset data Δy in the direction of Y-coordinate from the regular position in the data (shown with a dashed line in the figure), when interrupting rotation of the motor22.

Following the above process step, the transfer head8is activated for a pick-up operation according to the pick-up location data when the electronic component in the recess7A is picked up with the transfer head8. That is, the transfer head8is lowered after completing the positioning by correcting the position of the transfer head8only by a distance of the offset data Δx in the direction of X-coordinate from the regular pick-up location in the data. Accordingly, displacement of the pick-up location due to the deviations in the pin positions of the sprocket21can be corrected effectively. The invention accomplishes positioning of the electronic component16into the correct pickup location, thereby decreasing pick-up errors by the transfer head8.

According to this preferred embodiment, the tape feeder draws data on an amount of rotation of the motor corresponding to the right position where turning of the sprocket is to be interrupted, based on the result of measurement of pin positions of the sprocket, stores the data as the stop position data, and controls the motor based on the above stop position data when the tape feeder is in operation. This structure allows the sprocket to stop at the right stop position at all times, thereby achieving accurate positioning of the electronic components into the right pick-up location, alleviating difficulties in the positioning of the tape feeder, and improving the work efficiency.