Apparatus and method for sensing the position, size, shape and location orientation of one or more objects in two dimensions. The position sensor uses arrays of light sensors mounted on a substrate. When an object passes in proximity to the light sensors light energy from a plurality of light sources is either reflected from the object to the light sensors, or is emitted directly to the light sensors. The light energy is then converted to individual signals and transmitted through circuit traces in a printed circuit board to a local controller. The information may then be processed to determine the size, position, shape and location orientation of an object.
|
0. 37. An object sensor to determine the position of an object comprising:
a plurality of discrete light detectors distributed over a surface, each detector having a two dimensional detection surface;
at least one light source arranged relative to the detectors such that the amount of light that reaches each discrete light detector varies according to the position of the object, the output of each discrete light detector in the plurality of discrete light detectors used together to determine the position of the object.
0. 40. A method of detecting at least one of a presence, a position, a size, a shape and an orientation of an object using a plurality of discrete light energy detectors distributed over the surface of a detector portion of a substrate, each discrete light energy detector having a two dimensional detection surface having an area that is a non-negligible percentage of the detector portion, the plurality of light energy detectors arranged in two dimensions such that the detection surfaces of the plurality of light energy detectors substantially fill the detector portion of the substrate, the method comprising:
passing an object in proximity to the plurality of discrete light energy detectors;
emitting light energy from at least one light source;
using the object to controllably determine which of the plurality of light energy detectors receives light;
receiving the light energy at at least some of the plurality of light energy detectors based on at least some of the position, the size, the reflectivity of the object, the transmissivity of the object, and/or the orientation of the object;
transmitting a signal from each of the light energy detectors based on an amount of received light energy received at each light energy detector; and
determining the at least one of the presence, the position, the size, the shape and the orientation of the object based on the signals transmitted from the light energy detectors.
29. A method of detecting at least one of a presence, a position, a size, a shape and an orientation of an object using a plurality of discrete light energy detectors distributed over the surface of a detector portion of the substrate, each discrete light energy detector having a two dimensional detection surface having an area that is a non-negligible percentage of the detector portion, the plurality of light energy detectors arranged in two dimensions such that the detection surfaces the plurality of light energy detectors substantially fill the detector portion of the substrate, the method comprising:
passing an object in proximity to the plurality of discrete light energy detectors;
emitting light energy from a plurality of light sources;
using the object to controllably determine which of the plurality of light energy detectors receive light from the plurality of light sources;
receiving the light energy at at least some of the plurality of light energy detectors based on at least some of the position, the size, the reflectivity of the object, the transmissivity of the object, and/or the orientation of the object;
transmitting a signal from each of the light energy detectors based on an amount of received light energy received at each light energy detector;
determining the at least one of the presence, the position, the size, the shape and the orientation of the object based on the transmitted signals from the light energy detectors.
0. 1. An object sensor usable to sense a position of an object, comprising:
a substrate having a surface;
a plurality of discrete light energy detectors distributed over the surface of a detector portion of the substrate, each discrete light energy detector having a two dimensional detection surface having an area that is a non-negligible percentage of the detector portion, the plurality of light energy detectors arranged in a two-dimensional array such that the detection surfaces of the plurality of light energy detectors substantially fill the detector portion of the substrate; and
at least one light source arranged relative to the detector portion of the substrate to illuminate the plurality of discrete light energy detectors in absence of the object.
0. 2. The object sensor according to
0. 3. The object sensor according to
0. 4. The object sensor according to
0. 5. The object sensor of
0. 6. The object sensor of
0. 7. The object sensor of
0. 8. The object sensor of
0. 9. The object sensor according to
0. 10. The object sensor of
0. 11. The object sensor of
0. 12. The object sensor according to
0. 13. The object sensor according to
0. 14. The object sensor according to
the at least one light source comprises a plurality of light sources;
at least some of each of the plurality of light sources is mounted on the substrate within one of the light energy detectors.
0. 15. The object sensor according to
0. 16. The object sensor of
0. 17. The object sensor according to
0. 18. The object sensor according to
0. 19. The object sensor according to
0. 20. The object sensor according to
0. 21. The object sensor according to
0. 22. The object sensor according to
0. 23. The object sensor according to
0. 24. The object sensor according to
0. 25. The object sensor of
0. 26. The object sensor according to
0. 27. The object sensor according to
0. 28. The object sensor of
30. The method of
emitting light energy from a position opposing the light energy detectors toward the light energy detectors.
31. The method of
32. The method of
33. The method of
34. The method of
emitting light energy from a position to reflectively scatter from the surface of the object to the light energy detectors.
35. The method of
emitting light energy from center portions of at least some of the light energy detectors to reflectively scatter from the surface of an object to the light energy detectors.
36. The method of
0. 38. The object sensor of
a collimating film positioned adjacent to the plurality of light detectors, the collimating film to screen out light that is not scattered in a near vertical direction from the object.
0. 39. The object sensor of
0. 41. The method of
0. 42. The method of
collimating the emitted light before the emitted light reaches the light energy detectors.
0. 43. The method of
collimating the light before the light reaches the light energy detectors.
|
1. Field of Invention
This invention relates to a two-dimensional object position sensor usable to detect the position, orientation, size and/or location of an object.
2. Description of Related Art
The use of object position sensors is well known in the art. Typically, these sensors may include a light emitting diode placed in a fixed location that emits light energy in the direction of a photocell. When an object moves into the path of the light energy, the photocell ceases to send an electronic signal, thus indicating the presence of the object. Alternatively, the light emitting diode may be positioned to reflect light off of the object towards the photocell. In this arrangement, the presence of the would cause the photocell to generate an electronic signal.
In addition to these types of sensing devices, other sensing devices have been adapted for use in particular applications, such as photocopiers and printers. Typically, a sheet of paper is tracked as the sheet travels through the photocopier or printer using one-dimensional sensors or “fax bars” that detect the presence of the edge of a sheet of paper at a particular location within the photocopier or printer. These fax bars may use linear sensors arrays, which are only capable of sensing the object in one direction.
Small area imaging system such as CCD arrays and X-ray imaging systems have detector sizes on the order of 10 microns and 100 microns respectively. Due to the small pixel size and the technology that underlies the small area imaging arrays using such imaging arrays to sense the position of an object over a large area is impractical, especially when the object is in the near field of these small area imaging arrays.
Sensors usable to determine the size, position and/or location of objects are necessary in numerous operations and processes to allow for precise tracking and control of an object during the course of the process or operation. Typically, object position sensors may be placed in different locations along the path of an object undergoing a process. For instance, in an assembly line, object position sensors may be placed at various locations on the assembly line to indicate the presence of an object, such as a machine part in a manufacturing process. Object position sensors may also be used in package sorting operations involving a conveyor belt. In this type of operation, object position sensors may be placed at various locations along the conveyer belt to indicate the presence of an object, such as a box or package. In both the assembly line process and conveyor belt application, the object position sensors are used to track the progress of a box, package, or machine part through the process. This information may also be used to trigger other events within the operation or process itself.
Object position sensors are particularly applicable to photocopiers and printers to track and control the progress of a sheet of paper or other image recording medium as it progresses through the device. In conventional photocopiers and printers, a sheet of paper is tracked by a series of position sensors located at various points on a paper path within the device. In order for these position sensors to work effectively, the sheet of paper is constrained to have an edge placed along a side of the paper path, such that the object position sensor will positively register the presence of a sheet of paper. In addition, the sheet of paper may only positively be located within the paper path when it passes by one of these position sensors and is unaccounted at all other positions within the paper path. Because of this, it may often be difficult, for example, to pinpoint the exact location of a paper sheet that has become jammed in the paper path.
In such conventional photocopiers and printers, these position sensors are often only capable of sensing a sheet of paper in one dimension. A fax bar is one such device used in fax machines, copiers and printers which is capable of sensing the presence of a sheet of paper in only one dimension. While this type of sensing capability may be effective for tracking and controlling the motion of a sheet of paper in such conventional copiers and printers, the tracking and control capabilities of photocopiers and printers could benefit from providing an ability to handle a wide variety of sheet sizes and media types, multiple sheets moving together, to use center registration, and to position the sheets in arbitrary trajectories, that is, for example, by eliminating the constraint that the sheets have an edge positioned against the side of the paper path. Conventionally, if a paper path of a photocopier or printer were to be provided with such capabilities, a large number of discrete sensors would be required. While this may provide improved tracking of a sheet of paper throughout the paper path, it is an option that is currently uneconomical and impractical.
This invention provides systems and methods for sensing the size and position of an object with a two dimensional array of sensors that spans at least a portion of the path of the object.
This invention separately provides systems and methods that track an object continuously over a relatively long distance, such that the position of the object may be determined at any time while the object is in the vicinity of the array.
In various exemplary embodiments, the two-dimensional array of sensors may be fabricated inexpensively and may track an object with relatively high precision as it travels across a large area.
In various exemplary embodiments of the systems and methods according to this invention, an object position sensor uses a close-packed array of analog sensor elements, or pixels, along with appropriate illumination to determine object edge positions, and to infer object size, orientation, shape and position. In some exemplary embodiments, this is accomplished by distributing a series of light sources over the surface of a substrate such that light energy will be directed towards a series of discrete light energy detectors, or will reflect off of an object toward these discrete light energy detectors. In various exemplary embodiments, a collimating film is positioned over the light energy detectors to reduce the amount of low-angled light energy that reaches the surface of the light energy detectors. In some exemplary embodiments, a transmissive plate is positioned over the collimating film or over the analog sensor elements to allow an object to pass over the light energy detectors.
In various exemplary embodiments, the electrical signals from the sensors may then be locally digitized and hierarchically processed. In a reflective-type system, when an object, such as a sheet of paper, passes in the vicinity of the light energy detectors, light energy emitted from a light source is reflected off the surface of the object, passes through the collimating film, and is received by some of the light energy detectors. Alternatively, in a transmissive-type system, the light sources may be positioned opposite the light energy detectors. In this configuration, an object would block the light energy from reaching the light energy detectors.
In various exemplary embodiments, the sensor systems of this invention may be fabricated inexpensively using methods similar to those used to make large area solar cells or large area photoreceptor media, such as organic photoreceptor belts. These processes use roll-to-roll fabrication, which creates amorphous-Si:H photodiodes on a foil substrate, such as polyimide, or organic photoconductor or polyester. An organic photoreceptor sensor may be deposited on a substrate by a large-scale evaporation process, in the case of small molecule organics, or by a printing or coating process for polymer-based organics. In these exemplary embodiments, lateral patterning of the photosensitive material is not necessary. That is, the photo-responsive material is continuous and uniform. In this case, electron-hole pairs created by light absorbed in areas not containing collection electrodes simply recombine and do not drift to the collection electrodes. The lateral conductivity of the photosensitive material of these embodiments is low enough to essentially isolate the sensor elements.
The sensor elements of the sensor system can be arranged in arrays and have a relatively large size and/or pitch. For example, the center-to-center spacing or pitch can be sufficient to allow for sensors having a diameter of one cm in the case of a circular sensor element. Through the use of arrays, the position sensing resolution of the sensor systems and methods of this invention are considerably finer than the size and pitch of the sensor elements themselves. In this way, large areas may be covered by arrays of analog sensor elements to determine the position and size of an object in proximity to the array.
For instance, in a photocopier, these two-dimensional arrays of sensor elements may extend over the entire paper path, such that a sheet of paper can be continuously and accurately tracked throughout the entire process, including around the curves and bends of the paper path. Further, because the size and shape of the object may be determined through the use of the array of sensor elements, processes may be adapted to handle a wide variety of object sizes. For instance, the sensor systems and methods of this invention could be used in a photocopier to determine a variety of sheet sizes and media types, to determine if multiple sheets are moving together, to use center registration and to determine the position of a sheet of paper such that the photocopier may make adjustments or reposition the sheet of paper based on the information received from the position sensors.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of the preferred embodiments.
Various exemplary embodiments of the invention will be described with reference to the accompanied drawings, in which like elements are labeled with like numbers and in which:
Those portions of the light energy 146 that are not obscured by the object 10 will pass uninterrupted through the transmissive plate 136 to a collimating film 132. The collimating film 132 channels light energy 146 through a collimated light path 134 onto a light energy detector 128. Light rays traveling within an acceptance cone of the high aspect ratio holes in the collimating film are able to reach a sensor 128, whereas light rays traveling at lower angles are absorbed by the collimating film. The light sensors 128 may be solar cells, photoreceptors, or any other known or later-developed device, apparatus, structure or system that will extend over a sufficiently large area, such as 1 cm diameter circle, and that is capable of transforming light energy into electrical signals. The collimating film 132 may be a paper material, a plastic material or any other appropriate material having the desired light absorbing qualities. The collimating film 132 screens out ambient light and low-angled portions of the light energy 146 that did not emanate directly from the light sources 142. It should also be appreciated that the light sources 142 may be implemented by using ambient light channeled toward the transmissive plate 144 through a second collimating film or other such light channeling device to achieve the desired effect.
The light energy detectors, or light sensors, 128 may be one or more of any number of different types of light sensing devices. In the exemplary embodiment illustrated in
In the large area object position sensor 100 shown in
The collimating film 232 then channels those rays of light 246 traveling nearly parallel to the high aspect holes in the collimating film through a number of collimated light paths 234 onto a number of light sensors 228. Light rays incident at lower angles are absorbed by the collimating film and do not arrive at a light sensor 228. As in the large area object position sensor 100, the transmissive plate 236 may be formed of a rigid or flexible material, such as glass or plastic. The collimating film 232 may be of paper or plastic having a light absorptive surface. Similarly to the collimating film 132 of the large area object position sensor 100, the collimating film 232 functions to screen out ambient or lower-angle light energy that is not scattered in a nearly vertical direction from the object 10 passing over the light source 242.
It should be appreciated that, in various exemplary embodiments, the collimating film can be omitted. However, if the collimating film is omitted, the light reflected from or passing by the object from the light source must be sufficiently oriented relative to the large area positions sensor so that the position of the object can be accurately determined. As outlined above, if light reflected from the object impinges on multiple sensors, or if light from the light source reaches sensors that should be eclipsed by the object, the accuracy of the signals from the sensors is reduced.
If the collimating film is omitted, one or more light sources having optics that collimate the light before it is blocked or passed by a transmissive system can be used. In fact, if the one or more light source is located sufficiently distant from the object, the collimating optics may be omitted as well. Alternatively, in a reflective system, collimating optics or other collimating elements can be used in place of the collimating film. Moreover, if the reflective properties of the object to be sensed are sufficiently known in advance, the uncollimated light reflected from that object can be used to illuminate multiple light sensors, with the information about the reflective properties used during processes to accurately determine the position of the object relative to these sensors.
The light sensors 228 generate electrical signals that travel through upper circuit paths 226 to upper solder bumps 222. The upper circuit paths 226 are mounted on a substrate 224. The electrical signals travel through lower solder bumps 214 mounted on printed circuit board 210 and lower circuit paths 212 formed on the printed circuit board 210. The light sensors 228 may be solar cells, photoreceptors, or any other known or later-developed device, apparatus, structure or system that will extend over a sufficiently large area, such as a 1 cm diameter circle, and that is capable of transforming light energy into electrical signals. In various other exemplary embodiments, the light sensor 228 may be mounted on the printed circuit board 210, thus eliminating the need for the substrate 224 and the solder bumps 222 and 214. As in the large area object position sensor 100, the electrical signals generated by the light sensors 228 may be processed to derive shape, position and/or orientation of the object. In contrast to the large area object position sensor 100, the large area object position sensor as shown in
As shown in
Additionally, the dark conductivity of the photoreceptor 350 in non-illuminated areas 353 is sufficiently low that the light sensor portions 352 of the photoreceptor 350 are essentially electrically isolated from each other by these non-illuminated portions 353. The non-illuminated portions 353 are created by blocking portions 335 of the collimating film 332.
Because the third exemplary embodiment of the large area object position sensor 300 uses the light sensor portions 352 of the unpatterned photoreceptor 350 to create the electrical signals on the circuit path 326, light shields 343 are placed adjacent to the light sources 342. The light shields 343 prevent light emitted from the light sources 342 from directly shining onto the light sensor portions 352 and thus generating false electrical signals which would have to be subtracted from the total to ascertain that due to the object alone. The light shields 343 can be formed by opaque mylar disks surrounding the light sources 342. Alternatively, the sidewalls of the light sources 342 can be made non-emissive by coating with an opaque potting material or paint. In still other alternatives, the Light Sources 342 may be elevated so that the light emitting areas are well above the level of the photoreceptor sheet 352 and hidden by the collimating film 332. In general any appropriate technique can be used to ensure the light sources 342 do not emit directly onto the light sensor portions 352.
It should be appreciated that, in various exemplary embodiments, the arrays of the large-area light sensors according to this invention can be laid out in specific ways, depending on the application, to reduce the total area of coverage. This can allow other elements, such as motors or air jets, to be integrated into the array. Alternatively, this can be done simply to reduce the cost by reducing the number of light sensors and therefore the cost of any needed ancillary electronics. As long as the open regions between the individual large area light sensors are smaller than the smallest object to be sensed, such sparse arrays can still be used to span large areas and to provide 3-degree-of freedom feedback that is continuous in space and time.
The area of the individual large-area light sensors may be varied to trade off resolution and number of signals. Thus, in the areas of a paper path of a photocopier, printer, or in any other device incorporating the large area sensor systems according to this invention, where low resolution may be acceptable but continuous feedback is still desired, larger light sensors, still close-packed, may be used. For instance, some light sensors may be as small as about 1 mm in diameter. While sensors smaller than 1 mm in diameter may be used in particular applications, there is no upper boundary on the size of the sensor. In regions in any other device incorporating the large area sensor systems according to this invention, where high resolution is needed, small light sensors may be used.
In various exemplary embodiments, the arrays of individual large area light sensors and any needed ancillary electronics according to this invention may be formed into arbitrarily-shaped layouts. For example, “tic-tac-toe-shaped” arrays can be laid out which can give similarly high resolution, continuous feedback using fewer of the large-area light sensors and related electronics, thus reducing costs. In this case, the smallest sensible object will be no smaller than the spacing between rows and/or columns of pixels. In another exemplary embodiment, parallel columns of light sensors can be placed along the process direction of an object. The position and/or the skew of multiple objects could be sensed continuously. By adding cross rows, more complete shape information can be derived.
It should also be appreciated that, in various exemplary embodiments, the large-area light sensor systems according to this invention can use a flexible substrate. In this case, the object can be located with 3 degrees of freedom, such as x, y and θ, relative to the flexible substrate. However, to the extent that the substrate is curved through space, the sensed object could also be detected through 3 dimensions. A flexible substrate would be particularly desirable for sensing flexible objects, such as paper sheets in a paper path. Because the flexible substrate may be curved, objects can be sensed as the objects move along curved paths. Therefore, the flexible substrate may be used in cases where the path of the object or the geometry changes over time. It should further be appreciated that the light weight and large area of the substrate also enables the detector to be used on walls or tables to track human-scale objects over human-scale distances. In this way people, baggage, or relatively large objects may be tracked with the large-area light sensor system according to this invention.
The large object position sensor 600 illustrated in
The curve 1002 is a representation of the light intensity of a light emitter having a bare surface, or no diffusing characteristic at all. As illustrated by the curve 1002, light intensity values vary significantly in accordance with the angular aspect from which the light source is viewed. The curve 1004 is a graphical representation of a light emitter of this invention having the sides of the emitter painted in order to prevent light energy from being emitted in a lateral direction. As evident from the graph, a light emitter with painted side surfaces illustrates characteristics that are closer to a lambertian surface than the characteristics exhibited by the light emitter having the curve 1002. The curve 1006 is a graphical representation of the light emitter of this invention having a frosted surface. A light emitter having a frosted surface or a milky scattering encapsulation for the diffusion of light has the desired effect of a lambertian emitter. This is evident by the nearly circular shape of the curve 1106.
For example, as an object passes the light energy sensor 2 of the array 1200, it may simultaneously pass over the light energy sensor 4. Shortly thereafter, the sheet will pass over the light energy sensors 1 and/or 3, and then shortly after that, the object will pass over the light energy sensors 6 and/or 8. As such, the response from these light energy sensors may be fairly uniform but spaced in time. As the object moves past these light energy sensors, such that the object no longer reflects light back to these light energy detectors the response will correspondingly drop off to zero.
In this way, individual responses from each individual light energy sensor 1202 act in concert with one another to provide output data capable of being processed to determine an object's position to a resolution that is higher or finer than the pitch and/or the size of the light energy sensors 1202. From the data shown, the lateral position error from a single light energy sensor 1202 having a diameter of 1 cm, as limited by the noise, is estimated to be about 35 microns RMS. Thus, for a sheet of paper 8½″×11″, there would be approximately 100 sensors 1202 partially covered at the edges of the sheet. These 100 sensors 1202 would have noise signals which are relatively uncorrelated. Therefore, the error in determining the position and/or rotation of the rectangular object sheet 11 is expected to be less than 5 microns.
While this invention has been described in conjunction with specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention, as set forth above, are intended to be illustrative, not limited. Various changes may be made without departing from the spirit and scope of the invention.
Biegelsen, David K., Jackson, Warren B., Swartz, Lars Erik, Preas, Bryan
Patent | Priority | Assignee | Title |
9161813, | Jul 20 2012 | Stryker Corporation | RF energy console including method for vessel sealing |
Patent | Priority | Assignee | Title |
3549895, | |||
4323925, | Jul 07 1980 | Area Detector Systems Corporation | Method and apparatus for arraying image sensor modules |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jun 21 2004 | Xerox Corporation | (assignment on the face of the patent) | / |
Date | Maintenance Fee Events |
Mar 15 2010 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Apr 15 2014 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
Date | Maintenance Schedule |
May 27 2011 | 4 years fee payment window open |
Nov 27 2011 | 6 months grace period start (w surcharge) |
May 27 2012 | patent expiry (for year 4) |
May 27 2014 | 2 years to revive unintentionally abandoned end. (for year 4) |
May 27 2015 | 8 years fee payment window open |
Nov 27 2015 | 6 months grace period start (w surcharge) |
May 27 2016 | patent expiry (for year 8) |
May 27 2018 | 2 years to revive unintentionally abandoned end. (for year 8) |
May 27 2019 | 12 years fee payment window open |
Nov 27 2019 | 6 months grace period start (w surcharge) |
May 27 2020 | patent expiry (for year 12) |
May 27 2022 | 2 years to revive unintentionally abandoned end. (for year 12) |