JP2005537648A - Multiple light source alignment sensor with improved optics - Google Patents

Abstract

The features of the present invention provide an optical layout that can accommodate the relatively tight enclosure requirements for compact component alignment sensors. In particular, certain aspects of the present invention reduce the degree of divergence, preferably a single optical that substantially collimates the light from the multiple divergent light sources (212, 214) before entering the component zone. Provide components. In this regard, the number of parts is kept low and the physical size of the optical train is relatively small.

Description

[Background of the invention]
The present invention relates to pick-and-place machines that move electrical components onto surfaces such as printed circuit boards, hybrid substrates including circuit traces, and other carriers of circuit traces. The control system is arranged at an accurate position. More particularly, the present invention is a non-contact light-based sensor system that accurately determines the angular orientation and position (x, y) of a component and allows the pick and place machine to The present invention relates to a non-contact light-based sensor system that enables the angular orientation of a part to be corrected to an appropriate position with respect to the coordinate system of the pick and place machine.

  The electronic device assembly industry uses a pick-and-place machine to automatically “pick up” parts from a standardized feeder mechanism and place such parts on a printed circuit board. “Place” on a suitable carrier such as A given printed circuit board can include a large number of such components, and thus automation of the placement of the components on the printed circuit board is essential for cost-effective manufacturing. An important aspect of a given pick and place machine is the method of detecting the orientation and position of a part prior to placement. Some pick and place machines transport the part to an inspection station, where the part is imaged by an inspection camera or the like (ie, off-head systems). The Once imaged, a controller or other suitable device calculates orientation and position information from the image of the part. One drawback with such a system is the additional time required to transfer the part to the imaging station, to image the part, and to transfer the part from the imaging station to the deployment location. . Another type of pick and place machine uses an “on-head” sensor to essentially image the part as it is transferred from the part feeder to the placement location. Thus, in contrast to the above case, on-head component inspection systems typically allow for higher component throughput and thus allow for lower cost manufacturing.

  Pick and place machines that incorporate on-head sensors are known. One such device is disclosed in U.S. Pat. No. 5,096,096 issued to Skunes et al. 5,278,634. U.S. Pat. No. 5,278,634 discloses an on-head component detector that uses a single light source to direct illumination to and through the component of interest. The part fits into a fixed size window in the housing of the Skunes et al. '634 sensor. When the light is activated, the part is rotated by a vacuum quill while the width of the shadow projected onto the detector is monitored. The minimum shadow width is registered when the sides of the rectangular part are aligned perpendicular to the detector. The associated electronics are sometimes present in the pick and place machine, but the associated electronics calculate the desired rotational movement of the nozzle (knowing the reference axis of the pick and place machine). . This allows the angular orientation of the part as well as the position of the part to be determined and corrected to the proper position.

Other pick and place machines employ sensors having multiple light sources within the sensor to accommodate various sized parts.
Even though the system taught by Skunes et al. Has provided a significant advance in the technology of electronic component placement in pick and place machines, efficient sensors adapted for use with components having a wide range of sizes are different. Replacing a sensor with a sized window will provide faster placement and less machine downtime.

[Summary of Invention]
The features of the present invention provide an optical layout that can accommodate the relatively tight enclosure requirements for compact component alignment sensors. In particular, certain aspects of the present invention preferably provide a single optical component that reduces the degree of divergence and substantially collimates light from multiple divergent light sources before entering the component zone. . In this regard, the number of parts is kept low and the physical size of the optical column itself is relatively small.

  For convenience, items having the same reference number in different drawings are the same, or provide the same or similar function, as appropriate.

[Detailed Description of Preferred Embodiments]
FIG. 1A is a plan view of a pick and place machine 150 in which embodiments of the present invention are particularly useful. Although the description of FIG. 1A will be provided with respect to pick and place machine 150, other types of pick and place machines such as split gantry designs can be used. . As shown in FIG. 1A, the pick and place machine 150 includes a transfer mechanism 152 adapted to transfer a workpiece, such as a printed circuit board. The transfer mechanism 152 includes a mounting section 154 and a conveyor 156. The transfer mechanism 152 is disposed on the base 158 so that the workpiece is conveyed by the conveyor 156 to the mounting section 154. The feeder mechanism 160 is generally disposed on both sides of the transfer mechanism 152 and supplies electronic components thereto. The feeder mechanism 160 can be any suitable device adapted to provide electronic components.

  The pick and place machine 150 includes a head 162 disposed on a base 158. The head 162 is movable between any of the plurality of feeder mechanisms 160 and the mounting section 154. As can be seen, the head support member 164 is movable on the rail 166, thereby allowing the head 162 to move on the base 158 in the y direction. Movement of the head 162 in the y direction occurs when the motor 170 rotates the ball screw 172 in response to the motor actuation signal, and the ball screw 172 engages with one of the head support members 164 to support the head. The member 164 is displaced in the y direction. Head 162 is also supported on rail 168 and allows movement of the head in the x direction relative to base 158. Movement of the head 162 in the x direction occurs when the motor 174 rotates the ball screw 176 in response to the motor actuation signal, and the ball screw 176 engages the head 162 and displaces the head 162 in the x direction. Other pick and place designs, such as pick and place designs that do not operate exclusively in movement in the x and y directions, can be adapted for use with the present invention.

  The head 162 generally includes a main body 178, a nozzle mounting portion 180, a nozzle 182, and a sensor 184. The nozzle mounting portion 180 is disposed in the main body 178 and mounts each of the nozzles 182 in the main body 178. As used herein, “nozzle” is intended to mean any device capable of releasably holding a part. Each of the nozzles 182 is movable in the z-direction (up-down direction), the x-direction, and the y-direction, and can be rotated about the z-axis by any suitable actuating member such as a servo motor. Sensor 184 is adapted to obtain shadow information associated with a component held by nozzle 182. The sensor 184 includes appropriate illumination and detection devices so that the sensor 184 can provide shadow information that changes based on component orientation and offset. The sensor 184 can be mounted on the head 162, or alternatively, the sensor 184 can be mounted in a fixed position relative to the head 162. Information provided to the processing electronics 34 by the sensor 184 can be used to calculate the orientation and offset of each component. Such information includes calculating x and y axis offsets, as well as rotational offsets.

  FIG. 2 is a diagram of a component orientation and position detection system 10 according to one embodiment of the present invention. The component orientation and position detection system 10 includes light sources 12, 14 that are configured to direct the illumination 16 onto the component 18 from at least two different angles. The light sources 12 and 14 can be any suitable light source as long as the light sources 12 and 14 provide sufficient intensity of illumination for each light source. Thus, the light sources 12, 14 can be incoherent or coherent illumination. The light sources 12, 14 are preferably laser diodes, but in some embodiments, the light sources 12, 14 are light emitting diodes (LEDs). The light sources 12, 14 may be arranged to provide illumination in substantially the same plane defined by one of the light sources and two points on the detector (first and last pixels on the detector). it can. Although a pair of light sources 12, 14 are shown, any suitable number of light sources can be used, such as three light sources. Illumination 16 from the light sources 12, 14 is blocked to some extent by the part 18, thereby generating respective shadows 20, 22 on the detector 24. The detector 24 is preferably a linear charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor. The detector 24 includes a certain number of photoelectric elements or pixels. The detector 24 essentially captures the shadows 20, 22 in a short instant, and data associated with the captured shadow image (eg, detector output) via the link 28 to the detector electronics 26. Give. If desired, additional optical components (e.g., lenses, prisms, etc.) can be placed in front of the detector 24, thereby imaging the component (imaged or focused). Shadow) is incident on detector 24, which then provides a detector output that represents an image of the shadow rather than a shadow. As used herein, “shadow” is intended to mean any indication that is partially generated by the intensity of light changing based on at least partial blockage by the part of interest. Thus, the shadow may or may not be focused before falling on the detector.

  Since component 18 is held by nozzle 30 or otherwise attached to nozzle 30, component 18 is rotated as indicated by arrow 32 while light sources 12, 14 are selectively excited. As can be seen, during rotation of the part 18, the shadows 20, 22 will vary in size and position based on the cross-sectional area of the part 18 that blocks a given beam 16 of illumination. The signal from the detector 24 is read and / or stored during the rotation of the part 18 so that the data from the detector 24 is used to determine the direction of rotation of the part 18 relative to the nozzle 30 and the position of the part 18. Calculate (x, y). Detector electronics 26 provides this data to processing electronics 34 via link 36. As shown in FIG. 2, processing electronics 34 are preferably coupled to light source control electronics 38 to control the excitation of light sources 12, 14 during rotation of component 18. Light source control electronics 38 or excitation electronics 38 are mounted within sensor 184 in some embodiments. The processing electronics 34 can reside in a suitable personal computer and includes appropriate software for calculating angular orientation and offset. Processing electronics 34 is also coupled to encoder 40, whereby processing electronics 34 is provided with a signal from encoder 40 that indicates the angular orientation of nozzle 30. Thus, essentially knowing which light source is being excited, knowing the angular orientation of the nozzle 30 as indicated by the encoder 40, and detecting the shadow image projected by the part 18 while it is rotated. Thus, the processing electronics 34 calculates the orientation and position of the part given the appropriate knowledge of the internal geometry of the sensor.

  FIG. 2 shows a double end measurement when considering either one of the light sources 12, 14 because the shadow of the two ends of the part 18 falls on the detector 24.

  Various embodiments of the present invention use single end or double end measurements of a part under inspection to provide part information (part size, center offset, angular orientation, etc. ) Is designed to be extracted. Typically, double-ended measurements are performed as shown in FIG. 2, during the measurement time of the same part, without the shadows at both ends of the part overlapping due to part dimensions. Used when it is possible to fall down. Thus, at least two ends of the part can be shaded on the detector by different light sources within the same part measurement time. The difference between single-ended and double-ended measurements is that during the single-ended measurement process, only one end of the part will not cause the part to shadow the other end of the part on the detector. Due to the fact that it will be so large, any light source will cause its shadow on the detector.

  Two or more light sources are ordered to reduce the elapsed time before image information is collected for calculation. This is particularly advantageous when the three light sources are separately spaced relative to the plane defined by the light source and the CCD or imaging array (see, eg, FIG. 1B). Each of the light sources 12, 14 is incident on the component 18 because the light sources are generally at different angular positions from each other with respect to a line drawn from the nozzle 30 that is perpendicular to the surface of the detector 24. Sometimes it will direct its principal ray at a different angle to this normal. As used herein, the chief ray is the chief ray emanating from the center of illumination generated by the radiation source referenced nominally from the mechanical axis of the detector body, thereby causing the core of emitted radiation (Note that it is typically symmetrical) is bisected by the principal ray. This allows information contained in the shadow, such as edge information, to represent different spatial positions of the part. That is, as shown in FIG. 2, one side end can be aligned with respect to the light source 12 and with the rotation of the part less than 90 degrees, the other side end with respect to the light source 14. Can be aligned.

  The light sources 12, 14 are ordered in any suitable manner. For example, ordering the light sources 12, 14 at the full frame readout rate of the detector 24 (eg, 2 kHz line readout rate) reduces the amount of time that elapses between these light sources. The amount of time is ordered so that the amount of angular rotation of the parts during the interval is relatively small. By ordering the light sources in that way, it is possible to individually obtain shadow images derived from either light source, thereby reducing the movement of parts between any particular shadow image. Thus reducing granularity and enhancing the resolution of a series of images from that particular light source. Each light source makes it possible to collect shadow images from different rotational positions of the part. Based on different light source positions relative to the part, shadow images from two or more angular positions of the part are collected in a relatively short time. Component information can be collected in less time than would be required if a single light source was excited to collect data. This is because full rotation of the part is required to obtain angle information.

  Another important feature of embodiments of the present invention is the ability to generate a measurement envelope or sensing field of varying dimensions. As used herein, a “sensing field” is a sensor that is excited by a light source (when all light sources are excited), as modified by any mechanical shield such as a housing. The cumulative space irradiated. Thus, the sensing field does not necessarily require even a mechanical housing. The detection field is formed by adapting multiple light sources arranged so that a single sensor can detect the orientation of a component of varying size. For example, if the part is 25 mm laterally, one excited light source located 12.5 mm from the nominal center of the part and arranged perpendicular to the detector has its principal ray, It will capture the end of the part that was rotating in the sensing field. This embodiment, in its simplest form, requires only one excited light source per size component. The light sources have a specified conical solid angle of the light emitted from them, so that, as explained above, the distance that is transverse or roughly parallel to the nominal center and to the detector surface is Can be adjusted to give the divergence of this light source to project the shadow of the edge of the light source. However, a light source arranged, for example, with the principal ray of the light source going 8 mm from the nozzle 30 and along the diameter of the part 18 parallel to the detector 24 will be a relative orientation of the solid angle of light as well as Depending on the location of the light source it will be blocked. Based on the solid angle of each light source 12, 14 and the size of the part, each light source illuminates various areas of the part. It is important to select which one or more of the multiple light sources should be excited. This is because different sized parts generate even a part of the shadow, resulting in the use of different light sources. The light source control electronics 38 can also provide selective light source excitation based on expected component sizes. However, the light source control electronics 38 can provide a varying excitation order for parts of the same size to facilitate processing or to provide additional information about the part.

  As parts are swapped from small parts to large parts in the same sensor, they are directed more and more along a line parallel to detector 24 or a lateral line from detector 24 but to detector 24 A light source having a principal ray measured from a vertical line through the nozzle 30 or the center of rotation of the part images the end of the increasingly larger part by selectively sequencing the light sources 12,14. Will. (See arrow A in FIG. 1B). The light sources 12, 14 are ordered to project shadows from opposite sides of the part 18 at the same part measurement time interval (in the case where each light source projects a shadow on one side). Selection of the appropriate light source generally allows the light source to be turned on based on a priori knowledge of the expected part size, so that the end of the part 18 is imaged on the detector 24. Can be formed. This allows parts of varying size to be imaged on the detector 24 without requiring the use of multiple sensors that are fixed measurement envelopes or sensing field types.

  While the above description has focused on embodiments where a single nozzle is disposed within the sensing field, other embodiments can provide any suitable number of nozzles in the sensing field. FIG. 3 is a diagram of a system 20 for detecting component orientation in accordance with another embodiment of the present invention. System 20 includes many of the same or similar components as system 10 shown in FIG. 2, and similar components are numbered similarly. FIG. 3 shows that two or more nozzles 30 can be disposed in the sensing field 31 so that the orientation and position of multiple parts can be imaged substantially simultaneously to reduce processing time. Show.

  The sensing field 31 is the range between the radiation (light) source and the detector, where the components placed on the nozzle direct the light onto those components. In this embodiment, the shadow from the end of the part is projected onto the detector 24. Depending on the position of the nozzle 30 and the light sources 12, 14, the part 18, in particular a predetermined size, is measured, for example by ordering the various light sources 12, 14, so that the shadow of the part 18 is affected by other nozzles It can be distinguished from the shadow of the top part. The temporal ordering of the light sources 12, 14 in which the light source control electronics 38 excites the light source 12 first and then the light source 14 is shown in FIG. This has the advantage of allowing two or more parts 18 to be measured at substantially the same time in the sensing range. Furthermore, depending on the spacing between the nozzles 30, the nozzle 30 can hold components that vary in size, and still achieve component measurement while rotating such components over the nozzle 30. Make it possible.

  FIG. 3 shows an example of a double edge measurement when considered with respect to the light sources 12, 14 because the shadow of the two ends of the part 18 falls on the detector 24.

  FIG. 4 is a diagram of a part measurement system 50 according to another embodiment of the present invention. FIG. 4 shows a sensing field 31 in which the detector 24 comprises two spaced apart detector portions 24A, 24B, each of which detects light incident from the light sources 12,14. receive. The detector portions 24A, 24B can be disposed adjacent to each other and at various angles since each light source-detector pair operates independently. The principal axis of the detector 24A is not necessarily in the same plane as the principal axis of the detector 24B. Further, detectors 24A and 24B can be configured to image shadows from different parts of the part. By using a separate detector section, it is possible to use a smaller detector section, and if necessary, the detector sections 24A, 24B can be packaged separately. In this way, a very long detector 24 is not required to establish the same large part detection envelope or field 31. However, the ordering of the light sources 12, 14 is essentially the same as in the previous embodiment.

  FIG. 4 is an example of a double end measurement when considered with respect to the light sources 12 and 14 because the shadows at the two ends of the part 18 fall on each of the detectors 24A and 24B.

  FIG. 5 is a diagram of a part measurement system 60 according to another embodiment of the present invention. The part measurement system 60 has many similarities to the part measurement system 50 shown in FIG. 4, and similar parts are numbered similarly. The main difference between the part measurement systems 60 and 50 is the relative orientation of the detector portions 24A and 24B. Specifically, referring to FIG. 4, the surfaces of detector portions 24A and 24B lie in approximately the same plane and appear coplanar when viewed in two dimensions. However, the part measurement system 60 shown in FIG. 5 shows detector portions 24A and 24B arranged such that the major axes of detector portions 24A and 24B are not in the same plane. Accordingly, the detector portions 24A and 24B of the part measurement system 60 do not appear coplanar with respect to each other. Instead, detector portions 24A and 24B are disposed perpendicular to the centerline of illumination from the respective light source for each detector portion. For example, detector portion 24A appears to be oriented with respect to light source 14 such that ends 62 and 64 are equidistant from light source 14. The detector portion 24A is also disposed in the plane of the shadow 20, and the ordering of the light sources operates as shown in the relative timing diagram of FIG. Although the detector portions 24A and 24B are shown as being disposed at a relatively slight angle with respect to each other, any suitable angle, such as 90 degrees, can be used.

  FIG. 5 is an example of a double end measurement when considered for each light source, as the shadows at the two ends of the part 18 fall on each of the detectors 24A, 24B.

  FIG. 6 is a diagram of a component measurement and detection system 70 in accordance with another embodiment of the present invention. The part measurement and detection system 70 is similar to the embodiment shown in FIG. 2, and similar components are numbered similarly. The main difference between the system 70 of FIG. 6 and the system 10 of FIG. As can be seen, the light sources 12, 14 are initially directed to move their illumination away from the detector portion 24, and the illumination is reflected by mirror surfaces 72, 74 (typically substantially And is directed towards the nozzle 30 and the detector 34. This embodiment provides flexibility regarding the placement of the light sources 12,14. As shown in FIG. 6, detector 24 could also incorporate any of the respective detector layouts shown in FIG. 4 or FIG. However, in an embodiment using a split detector portion and specular reflector, one light source could utilize a specular reflector, while another light source has its principal ray as a component. It could be arranged so that it is incident directly on top and therefore does not require a specular reflector. Further, although FIG. 6 shows the use of a specular reflector between the light sources 12, 14 and the component, such a specular reflector can be disposed between the component and the detector 34. Will.

  FIG. 7 is a diagram of a component measurement and detection system 80 according to an embodiment of the present invention. The part measurement and detection system 80 is illustrated to show how to detect the offset and rotation orientation of a part relative to an oversized part (eg, a single end measurement) using embodiments of the present invention. This description is given to detail the calculation of rotation and position (x, y) offset for a single end measurement and can be extended to a double end measurement. U.S. Pat. 5,559,727 also provides for calculating rotation and position offsets for two-sided measurements for different light source / detector arrangements. FIG. 7 shows an example of a one-sided measurement for either one of the light sources 12, 14 as only one shadow at one end falls on each of the detector portions 24A, 24B. Such a component is generally too large to fit the shadows on opposite sides simultaneously onto any single detector portion.

  FIG. 7 shows a component 100 that projects shadows onto detector portions 24A and 24B. However, each detector part only captures a single shadow. This is because the shadow of the opposite side of the part 100 is so large that it does not fall on the detector portions 24A and 24B. In this embodiment, detector outputs 28A and 28B provide a shadow minimum indicating when each piece (side) of part 100 is aligned with a given ray emanating from one of light sources 12,14. In order to detect, the component 100 is monitored while being rotated. For example, in the case shown in FIG. 7, a slight counterclockwise rotation will cause the end 102 of the part 100 to be aligned with the light beam emanating from the light source 14. Such alignment will produce a local minimum on the detector portion 24A. In FIG. 7, it will be appreciated that although the detector appears to be positioned perpendicular to the light source, non-orthogonal positions may also be employed.

The single light source of FIG. 7 shown in FIG. 8 to determine the x-axis and y-axis offsets in FIG. 7, the width of the part, the total length of the side of the part, and the rotational offset of the part Consider a similar example of a detector pair. The length of the minimum width is measured by determining the distance D ₁ of the between Kagetan portion and the detector point O _1. The distance D ₁ is associated with the dimension L ₁ of the parts as follows. When the distance _{D 1} is a minimum,

And there

as well as

It is.
Equations for L _C and α ₁ _side_a can be similarly derived when side_c (side C) is rotated to a similar position such as side_a (side A) in FIG. Encoder and encoder electronics captures the encoder rotation E _1. Incidentally, _{D 1} is the smallest. If the step size between successive encoder rotations is T, when side_a (side A) is aligned with the reference axis of the pick and place machine and is perpendicular to the main axis of the detector 24b The part rotation encoder value is

It is.
Where α ₁ _side_a is the angle formed between the line to O ₁ on the detector 24 b and the line to S ₁ on the point light source 12 and θ ₁ is on the detector 24 b in the light source 12. The angle formed between the line to O ₁ and the reference axis of the pick and place machine. The part width _Wac can be calculated as:

  The offset of the nozzle shaft 30 (rotation axis) along the line W from the center of the part is given by the following equation.

The calculation process described mathematically by Equations 1 through 6 is optional that it can be repeated for the remaining opposing sides of the part 100, from which orthogonal widths and offsets can be calculated. This process can be applied repeatedly to the part 100, where the values L _a , L _b , L _c , L _d (the length of the side of the part 100) are ordered to excite the light sources 12, 14. Can be derived from any sequence of minimum projections available on the detectors 24b, 24a by the light sources 12, 14 as determined by the rotation of the component 100 relative to the light sources 12, 14.

  FIG. 9 is a diagram of a component orientation and placement detection system 210 in accordance with an aspect of the present invention. FIG. 9 is somewhat similar to FIG. 1 and similar components are similarly numbered. Component orientation and placement detection system 210 includes light sources 212, 214 configured to direct illumination 216 onto component 218 from at least two different angles. The light sources 212, 214 can be any suitable light source as long as they provide illumination with sufficient intensity when considered for each light source. Thus, the light sources 212, 214 can be non-coherent or coherent illumination sources. The light sources 212, 214 are preferably laser diodes, but in some embodiments, the light sources 212, 214 are light emitting diodes. The light sources 212, 214 provide illumination in substantially the same plane as defined by either one of the light sources and two points on the detector (first and last pixels on the detector). Can be arranged as follows.

  Divergent illumination from the light source 212 passes through the optical element 217, which reduces the degree of divergence of the illumination and preferably functions to make the passing light substantially parallel. As shown, illumination from the light source 212 through the optical element 217 forms a first beam 219 having a reduced divergence, while illumination from the light source 214 through the optical element 217 has a reduced divergence. A second beam 221 is formed. The optical element 217 is preferably a lens that is spherical or cylindrical. However, a cylindrical lens is more preferred. Illumination emanating from the optical element 217 provides less compactness than the ray bundle that would otherwise be present, thereby requiring less part rotation. This will speed up the calculation of part alignment. Moreover, those skilled in the art will appreciate that the optical element 217 is disposed in an opposite direction from the optically ideal orientation. Thus, the optical element 217 has a flat surface proximate to the zone 223 of the part. The optical element 217 having a flat surface proximate to the component zone provides the component orientation and placement detection system 210 with a convenient seal against contaminants.

  In accordance with one aspect of the invention, the filter 225 is disposed proximate to the detector 224 to reduce ambient light falling on the detector 224. The filter 225 can filter based on the angle and / or wavelength of the incident light.

  One skilled in the art would have a complete part measurement of about 225 degrees (180 degrees to image both ends + up to 45 to image the first edge) for a four-sided part. In degrees) rotation. This is significantly faster than requiring a full revolution of the part.

  In some cases, the pick and place machine may not have any a priori knowledge of part size. In such a case, the pick and place machine can perform a “light source scan” in which a plurality of light sources are sequentially excited and any one of the light sources is at least one. It is determined whether or not one shadow portion is disposed on the part to project onto at least one detector. If such a combination is found, the measurement and alignment of the part can be performed with the selected detector / light source combination.

  The operation of an embodiment of the present invention generally includes the following steps. The first step is to calibrate the light source, nozzle and detector positions relative to each other. There are a number of techniques that can be used for this operation. For example, the calculation of the position of the various sensor elements can be done by placing a sensor having a test component fixed in place on a coordinate measuring machine and then using the coordinate measuring machine to determine all relative positions of the test component. It can be performed by identifying and thus knowing the position of light rays incident on the detector from one or more light sources with respect to the position of the nozzle and the position of the detector.

As a second step, one or more shadows from the projection of each part onto the detector by light incident from one or more light sources has a characteristic intensity profile that is processed to extract the edges. . End positions can be interpolated to sub-pixel positions. Such interpolation can be performed using any of a number of techniques including centroid calculation or curve fitting. This then associates a particular end position with the encoder position and the known source beam position. The defined end of the shadow then gives one (r, θ) pair. Where θ is the position of the encoder on the nozzle shaft or attached to the nozzle shaft indicating its relative angular position, and (r, θ) is from the light source to the end on the detector Position, the distance to the end position that defines the position of the part in its particular point in angular space and time. (R, θ) pairs are collected during rotation of the part on the nozzle. (R, θ, B ₁ ) is derived using the plurality of (r, θ) pairs and using a known geometric technique as shown in FIG. Here, θ is used together with α to calculate the angular orientation of the part. The component information includes the component width, the component length, the rotation center nozzle offset x, the rotation center nozzle offset y, and the angle of the frame in which the component reference is defined with respect to the nozzle angular position. Includes location. With this information, the position of the part can be translated via software into a specific pick and place machine frame of mechanical reference, and the part It can be properly positioned to be placed on the target position.

  Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, multiple portions of detector 24 could be placed in the same plane or none in the same plane. Further, such detector portions may not be physically contiguous, but may be segments of the detector, so that the position of multiple nozzles relative to the light source and detector can be Based on the selection of the light source that is turned on for the part, it is possible to image the part on such a detector part.

FIG. 1A is a plan view of the pick and place machine of the present invention. FIG. 1B is a perspective view of the sensor of the present invention. FIG. 2 is a diagram of a system for detecting component orientation and position in accordance with one embodiment of the present invention. FIG. 3 is a diagram of a system for detecting component orientation and position in accordance with another embodiment of the present invention. FIG. 4 is a diagram of a system for detecting component orientation and position in accordance with another embodiment of the present invention. FIG. 5 is a diagram of a system for detecting component orientation and position in accordance with another embodiment of the present invention. FIG. 6 is a diagram of a system for detecting component orientation and position in accordance with another embodiment of the present invention. FIG. 7 is a diagram of a system for detecting component orientation and position in accordance with one embodiment of the present invention. FIG. 8 is a diagram of a single detector / light source pair. FIG. 9 is a diagram of a system for detecting the orientation and position of a part, in accordance with one embodiment of the present invention.

Claims (12)

A sensor system for calculating placement information about a part in an electronic part handling machine adapted to hold the part releasably and rotate the part, comprising:
A sensor,
A plurality of divergent light sources in the sensor arranged to illuminate a component zone in the sensor;
When the component is at least partially disposed in the component zone, the component blocks at least some illumination from at least one divergent light source of the plurality of divergent light sources, and shadows at least a portion of the component. A detector positioned relative to the light source to form a detector on the detector, wherein the detector is adapted to provide a plurality of detector outputs as the part rotates;
Optical means interposed between the component zone and the plurality of divergent light sources to reduce the divergence of light passing therebetween;
A sensor system comprising: an electronic computing device that receives the detector output and calculates the placement information.   2. A sensor system according to claim 1, wherein said optical means is a spherical lens.   The sensor system of claim 2, wherein the spherical lens has a substantially flat surface disposed proximate to the component zone.   4. The sensor system of claim 3, wherein the flat surface provides a seal against contaminants.   2. A sensor system according to claim 1, wherein said optical means is a cylindrical lens.   The sensor system of claim 5, wherein the cylindrical lens has a substantially flat back surface.   The sensor system of claim 6, wherein the substantially flat back surface is disposed proximate to the component zone to provide a seal against contaminants.   The sensor system of claim 1 wherein the optical means substantially collimates light passing through the optical means.   The sensor system of claim 1, further comprising an ambient light filter disposed proximate to the detector to reduce ambient light falling on the detector. The sensor system of claim 9, wherein the filter is an angular filter.   The sensor system of claim 9, wherein the filter is configured to pass the wavelength of the illumination but attenuate ambient light.   The sensor system according to claim 11, wherein the filter is also an angular filter.

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