Patent Application
20230393368
This application herein incorporates International Publication No. WO 2020/021578 in its entirety.
Currently, to have a large reading field, two or more parallel lectors or optical readers or image readers are needed. If these are not available, a moving single lector (or optical reader or image reader) with a complicated handling system must be implemented. Such complicated handling system is expensive and slow.
The inventors have appreciated that a solution is needed that can extend a reading field with one lector or optical reader or that can extend a reading field without a complicated handling system.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The technical solution at the basis of the present invention is that of not only providing a focus device alternative to the ones already known and that ensure quickly reaching the desired focusing position but also providing an extended reading field and having a device that can focus at all areas of the reading field and the extended reading field.
The disclosed system described herein is an electromagnetic autofocus with cushioning for imager devices and applications where it is necessary to quickly move an optical unit along a rectilinear axis and orient it to extend a reading field. The device consists of a translating component made by a hollow cylindrical support in aluminum that houses a lens, two sliding bushings and two circular motion coils electrically connected to two conductive springs. Further, the device includes a guide inside which the translating component slides, two permanent magnets that envelop the guide, a spacer, two limits of motion, a plastic support, a balancing mass, and a printed circuit board with an image sensor. Four fixed electromagnets are mounted outside of the device.
The orientable autofocus allows the imaging device to obtain an extension of a reading field with only a lector (i.e. reader). The orientation is quick and the cost to implement the imaging device is low.
In a first aspect, an imaging device is provided that includes a focusing device. The focusing device includes an optical assembly. The optical assembly is configured to have an optical lens system including one or more lenses made from a hard transparent substance or made from a liquid lens system including an optical liquid material. The optical assembly collects an image located at a distance at a reading field of the imaging device and transfers the image to an acquisition sensor in the focusing device. The focusing device is configured to be orientable about an axis in positions. When the focusing device is in one position, the optical axis of the optical assembly in the focusing device is perpendicular to the reading field. When the focusing device is rotatable about the axis in another position, the optical axis moves and creates an extended reading field from the movement of the optical axis. The extended reading field is the area adjacent to (or on either side of) the reading field. Electromagnets are located exterior to the focusing device. At least two magnets are placed around the optical assembly. When the optical axis of the optical assembly in the focusing device is oriented perpendicular to the reading field, the optical assembly achieves a fixed focus. Electromagnets and at least two magnets create a magnetic levitation, which causes a rotation of the focusing device. When the magnetic levitation causes the rotation of the focusing device at the axis, the rotation of the focusing device yields the extended reading field and the focusing device achieves an orientable focus in the adjacent areas to the reading field.
In another aspect, a method for creating an imaging device with an orientable focus for extension of a reading field is provided that includes configuring a focusing device in the imaging device with an optical assembly that has a lens system or a liquid lens system. Through the optical assembly, an image is captured located at a distance at a reading field of the focusing device. The optical assembly is oriented to extend beyond the reading field, which is perpendicular to an optical axis of the optical assembly. An extension of the reading field of the focusing device comprises rotating the focusing device about an axis. A plurality of electromagnets is located in proximity to the optical assembly. At least two magnets are placed around the optical assembly, where the at least two magnets have opposite polarities. A line of sight of the focusing device is oriented perpendicular to the reading field to achieve a fixed focus. A magnetic levitation is created between the plurality of electromagnets and at least the two magnets. The magnetic levitation causes a rotation of the focusing device at the axis. A rotation of the focusing device yields an extension to the reading field and achieves an orientable focus in the extended areas beyond the reading field.
In yet another aspect, an imaging device has an autofocus and has a focusing device that pivots so as to extend a reading field located at a distance. A pair of ring magnets is configured to radially magnetize with opposite polarities. A ring spacer is located between the pair of ring magnets. The pair of ring magnets and the ring spacer form a first cylindrical shape. The pair of ring magnets is configured to attach to an exterior of a cylindrical-shaped guide. The pair of ring magnets and the ring spacer are adjacent to the cylindrical-shaped guide. A motion coil is located adjacent to an interior of the cylindrical-shaped guide. The motion coil is in a second cylindrical shape. A sliding bushing is adjacent to the motion coil and located adjacent to the interior of the cylindrical-shaped guide. The motion coil is attached to a cylindrical support that is located to the interior of the motion coil. The cylindrical support is also located to the interior of the sliding bushing and includes a lens. The sliding bushing is attached to one end of conductive springs, and the other end of the conductive springs is attached to the focusing device in proximity to an image sensor. The sliding bushing and the motion coil move in a direction along the interior of the cylindrical-shaped guide when the motion coil receives an electric current that passes through the conductive springs. When the sliding bushing and the motion coil move, the cylindrical support including the lens also moves. The sliding bushing, the motion coil, and the cylindrical support with the lens move together as a unit. An amount of movement of the unit aids in a focus of the reading field when captured at the image sensor. A magnetic field crosses the pair of ring magnets in a direction orthogonal to the movement of the unit. Electromagnets are configured to be located at an exterior of the first cylindrical shape of the pair of ring magnets and are also located in proximity to the pair of ring magnets such that magnetic levitation occurs between the electromagnets and the pair of ring magnets. Each of a first pair of electromagnets is located on one side of the pair of ring magnets and each of a second pair of electromagnets is located on the other side of the pair of ring magnets. When magnetic levitation is balanced or even, the first pair of electromagnets and the second pair of electromagnets are equidistant and are placed in a fixed position. The focusing device achieves a fixed focus on the reading field. When the magnetic levitation changes, the change of magnetic levitation causes the focusing device to move and rotate about an axis to the desired position, which is maintained through the adjustment of the current that passes in the electromagnets. The focusing device is in a rotated position with an orientable focus on an extended reading field adjacent to the reading field.
In a final another aspect, an imaging device has an autofocus and has a focusing device that pivots so as to extend a reading field located at a distance. A pair of ring magnets is configured to radially magnetize with opposite polarities. A ring spacer is located between the pair of ring magnets. The pair of ring magnets and the ring spacer form a first cylindrical shape. The pair of ring magnets is configured to attach to an exterior of a cylindrical-shaped guide. The pair of ring magnets and the ring spacer are adjacent to the cylindrical-shaped guide. The interior of the cylindrical-shaped guide includes a liquid lens system. A magnetic field crosses the pair of ring magnets in a direction orthogonal to the movement of the unit. Electromagnets are configured to be located at an exterior of the first cylindrical shape of the pair of ring magnets and are also located in proximity to the pair of ring magnets such that magnetic levitation occurs between the electromagnets and the pair of ring magnets. Each of a first pair of electromagnets is located on one side of the pair of ring magnets and each of a second pair of electromagnets is located on the other side of the pair of ring magnets. When magnetic levitation is balanced or even, the first pair of electromagnets and the second pair of electromagnets are equidistant and are placed in a fixed position. The focusing device achieves a fixed focus on the reading field. When the magnetic levitation changes, the change of magnetic levitation causes the focusing device to move and rotate about an axis to the desired position, which is maintained through the adjustment of the current that passes in the electromagnets. The focusing device is in a rotated position with an orientable focus on an extended reading field adjacent to the reading field.
The present invention is illustrated by way of example and not limitation in the accompanying figures in which like reference numerals indicate similar elements and in which:
The subject matter of aspects of the present invention is described with specificity herein to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent.
Embodiments of the invention includes an imager device or industrial camera that includes a focus lens system. The focus lens system is capable of being oriented in order to extend the reading field of the imager device. In one embodiment, the imager device includes four fixed electromagnets and two ring permanent magnets. The two ring permanent magnets are radially placed around a barrel lens and magnetized with opposite polarities. As the focus lens system is oriented, the focus orientation around a rotation axis is achieved by the magnetic attraction or magnetic repulsion forces (magnetic levitation) between the four fixed electromagnets and the two ring permanent magnets. In embodiments, autofocus is a preferred embodiment, but a non-autofocus optical assembly can be implemented.
Herein, the expressions “axial,” “axially,” and similar expressions refer to a direction substantially parallel to the optical axis, while “radial,” “radially” and similar expressions refer to a direction substantially perpendicular to the optical axis.
Autofocus is well known in vision systems. U.S. Pat. No. 8,731,389 B2 from COGNEX is an example: “[0008] This invention overcomes disadvantages of the prior art by providing an electro-mechanical auto-focus function for a smaller-diameter lens type.”
Autofocus capability can be implemented by means of liquid lens or by means of electro-mechanical movements of lenses. Embodiments of the present invention disclose lens, balancing mass, rubber, sliding bushing, conductive spring, and motion coil. A similar approach, based on the exploitation of electromagnetic actuator, is described in U.S. Pat. No. 6,594,450 B1 from INTELLECTUAL VENTURES: “[0021] Please refer to FIG. 1 showing a perspective view of an auto-focus mechanism 10 according to the present invention. The auto-focus mechanism 10 includes a first hollow cylinder 12 attached to a frame (ref. 14, FIG. 2a), a first lens 16 also attached to the frame, an insulated metal wire wound around the cylinder 12 forming a coil 18, and a second hollow cylinder 20 holding a second lens 22. The second cylinder 20 fits over the first cylinder 12 and the coil 18 and is movable along the central axis of the first cylinder 12. The first and second lenses 16, 22 are also aligned on the central axis of the first cylinder 12. The first and second cylinders 12, 20 are mechanically connected by an elastic member such as a spring (ref. 24, FIG. 2a). The second cylinder 20 is made of metal, preferably a metal with high magnetic permeability such as iron, or magnetized iron or other permanent magnet material. The coil 18 is a linear coil of insulated conductor capable of being energized by a power source (not shown) to conduct a current. The coil 18 and second cylinder 20 form a solenoid-type device (e.g. electromagnetic valve). The auto-focus mechanism 10 is installed in a camera such as a film-based or digital camera. The first and second lenses 16, 22 work in conjunction to focus light from a subject to be photographed onto a photographic medium such as a photographic film or a charge-coupled device (CCD), the distance between the first and second lenses 16, 22 determining the focal length of the auto-focus mechanism 10.”
Typical industrial application vision system installations are based on a set of fixed installed cameras, each of them being a camera with an autofocus property and each one being devoted to frame its reading field.
European Patent No. EP2624042 B1 from COGNEX, for example, proposes a system and method for expansion of a field of view in a vision system by means of a set of mirrors that transmit light from a scene in respective different partial fields of view. “[0003] A common use for ID readers is to track and sort objects moving along a line (e.g. a conveyor) in manufacturing and logistics operations. The ID reader can be positioned over the line at an appropriate viewing angle to acquire any expected IDs on respective objects as they each move through the field of view. The focal distance of the reader with respect to the object can vary, depending on the placement of the reader with respect to the line and the size of the object. That is, a larger object may cause IDs thereon to be located closer to the reader, while a smaller/flatter object may contain IDs that are further from the reader. In each case, the ID should appear with sufficient resolution to be properly imaged and decoded. Thus, the field of view of a single reader, particularly in with widthwise direction (perpendicular to line motion) is often limited. Where an object and/or the line is relatively wide, the lens and sensor of a single ID reader may not have sufficient field of view in the widthwise direction to cover the entire width of the line while maintaining needed resolution for accurate imaging and decoding of IDs. Failure to image the full width can cause the reader to miss IDs that are outside of the field of view. [0004] There are several techniques that can be employed to overcome the limitation in field of view of a single ID reader, and expand the systems overall field of view in the widthwise direction. For example, one can employ multiple ID readers/cameras focused side by side to fully cover the width of the line. This is often an expensive solution as it requires additional hardware and optics. Alternatively, a line-scan system with inherently wider FOV can be employed.”
Embodiments of the invention propose to solve the problem by exploiting magnetic levitation (magnetic attraction/repulsion forces). Also, embodiments of the invention disclose an automatic orientation of a camera in order to augment the reading field.
Japanese Patent No. JP09043663 A discloses a vision system that is exploited for image stabilization purposes: “[0001] The present invention, a video camera using the magnetic levitation of the camera shake correction device and a method thereof according to the present invention, more specifically, to an outer side of the fixed iron core of the lens barrel and a camera respectively corresponding to the inner side of the electromagnets in such a manner that, when the camera shake correction mode of a predetermined amount of current to the electromagnet assembly and the camera lens and the lens barrel from the floating (rise), the image shake caused by camera shake can be automatically corrected using the magnetic levitation of a video camera-shake correction apparatus and a related method.”
U.S. Pat. No. 9,684,184 B2 discloses an actuator device for stabilizing the optical image of a lens assembly with respect to an image sensor in a camera. The lens assembly is movable with respect to a support structure which supports the device. It is provided a first electrical winding for the autofocus and a second electrical winding for stabilizing the optical image, as well as a plurality of magnets. The two windings are fixed to the support structure, while the magnets are fixed to the lens assembly. Through the adjustment of the current that passes in the two windings, the lens assembly is focused and the optical image is stabilized. “[ABS]: the actuator module further includes a plurality of trapezoidal magnets affixed to the lens assembly structure for magnetic interaction with one or more of the one or more optical image stabilization coils and the one or more autofocus coils.”
U.S. Pat. No. 9,001,224 B2 discloses a device for guiding a lens-holder that corrects the optical image in case of vibrations of the camera. The lens-holder is mobile with respect to a support structure of the device. Thus, provided is a first electrical winding for the autofocus fixed to the lens-holder, a second electrical winding for the correction of vibrations fixed to the support structure, and a permanent magnet also fixed to the support structure. Through the adjustment of the current that passes in the two windings, the lens-holder is focused and the optical image is corrected.
None of the documents found, alone, discloses all the features of the invention. A combination of the references does not lead to the implementation proposed by embodiments of the invention.
PCT Publication No. WO2020/021578 A1 discloses a device for focusing a light beam. It also discloses that the cushioning of the translating group is obtained by coupling the elastic springs and the force generated by the electric current induced in a hollow cylindrical support. The WO2020/021578 publication is incorporated herein in its entirety.
A cross-section view of an imaging device 100 is shown in
Focusing device 105 has abutment rings 115A and 115B that are used to limit the motion of sliding bushings 120. Sliding bushings 120 move in a linear direction along a guide 125. Sliding bushings 120 can be made from a variety of materials including polyoxymethylene (POM), polytetrafluorethylene (PTFE), polyamide, and polyethylene (PE).
Guide 125 has a cylindrical shape and is usually made of stainless steel, but can also be made of other materials. Guide 125 has an axial cavity in which an assembly formed by the optical assembly, sliding bushings 120, motion coils 130, and a support 135 are slidingly housed. Guide 125 substantially acts as a sliding bearing.
Focusing device 105 also includes motion coils 130, which are usually made of copper wire. Support 135 is adjacent to motion coils 130 and can be hollow and cylindrical in shape. Support 135 is used to provide structural support for lens 140, sliding bushings 120, and motion coils 130. Support 135 is usually made of aluminum, but can be made of another light-weight material.
As one can see in
Surrounding the cylindrical shape of the optical assembly, sliding bushings 120, guide 125, motion coils 130, and support 135 are magnets 145A and 145B, which are separated by a spacer 150. As one of ordinary skill in the art understands, the arrangements of components in
Electromagnets 110A, 110B, 110C, and 110D are located in pairs on opposite sides of focusing device 105 near, but not touching magnets 145A and 145B. Electromagnets 110A, 110B, 110C, and 110D can be made of copper wire and iron, but can also be made of other conductive and ferromagnetic materials.
At the closed or south end of focusing device 105, a printed circuit 153 is located and holds an image sensor 155, which captures an image that passes through the optical assembly. Also, within focusing device 105, conductive springs 160 attach at one end to printed circuit 153 and attach at the other end to sliding bushing 120. When sliding bushings 120 move in the linear direction along guide 125, conductive springs 160 expand and contract. The movement of sliding bushings 120 also includes the movement of motion coils 130, support 135, lens 140 and the optical assembly moving as one unit. Conductive springs 160 can be made of copper-beryllium wire, but other materials could be used to function as a conductive spring.
Conductive springs 160 are housed inside to the interior of guide 125 and are operatively interposed between the optical assembly and printed circuit 153.
Focusing device 105 also includes an autofocus support 165 and a balancing mass 170. Autofocus support 165 may be made of plastic resin or other material. Balancing mass 170 is used to act as a counterbalance when focusing device 105 pivots or rotates about an axis.
For the sake of ease, sliding bushings 120, motion coils 130, support 135, and the optical assembly with lens 140 may be referred to collectively as a moving mechanism unit 180. Similar to earlier discussions about sliding bushings 120, moving mechanism unit 180 moves in a linear direction in either direction along guide 125. Moving mechanism unit 180 and conductive springs 160 are movable with respect to the remainder of focusing device 105. The ring permanent magnets 145A and 145B are radially magnetized with opposite polarities. The magnetic field crosses the motion coils 130 in a direction orthogonal to the linear direction along guide 125 and closes in the air. The motion coils 130 are powered with opposite electric currents by means of the conductive springs 160. Therefore a Lorentz force is generated in a linear direction along guide 125 causing moving mechanism unit 180 to move back and forth and conductive springs 160 expand and contract. The amount of movement of moving mechanism unit 180 can be determined by the amount of electric current applied to coils 130 by means of the conductive springs 160. However, moving mechanism unit 180 is limited in its movement by abutment rings 115A and 115B. Abutment rings 115A and 115B acts as a buffer or stop to prevent the moving mechanism unit from extending beyond a minimum position or a maximum position.
Turning now to
In
Additionally,
In
Turning now to
From an operational perspective of
In some embodiments, with autofocus support 165, guide 125 is inserted with interference into autofocus support 165. Printed circuit 153 is fixed with screws 410 and balancing mass 170 is fixed with screws 415A and 415B. In other embodiments, guide 125, sliding bushings 120, and magnets 145A and 145B do not exist. This is the case when liquid lens system 640 is used in a focusing device. However, printed circuit 153 is still fixed with screws 410 and balancing mass 170 is fixed with screws 415A and 415B in embodiments that operate with liquid lens system 640.
The purpose of balancing mass 170 is to balance focusing device 105 (or focusing device 605) to a rotation and therefore reduce the electric consumption of electromagnets 110A, 110B, 110C, and 110D to maintain an autofocus orientation. The autofocus orientation is around the rotation axis by means of magnetic attraction/repulsion forces (magnetic levitation) between electromagnets 110A, 110B, 110C, and 110D and magnets 145A and 145B, in embodiments that employ translating lens 140A. In embodiments that employ liquid lens system 640, the magnetic levitation occurs between electromagnets 110A, 110B, 110C, and 110D and magnets 645A and 645B. Like magnets 145A and 145B, magnets 645A and 645B can be made of sintered neodymium iron boron, samarium cobalt (SmCo), alnico, or ceramic (i.e. ferrite).
Alternatively, the autofocus orientation can be obtained by means of a stepper motor and gears but this solution has two disadvantages: It is more expensive and slow. To reduce friction in the autofocus orientation, ball bearings 405 can be used. To minimize stresses and strains of cables for power supply and electrical signals, the cables are passed through holes 400A and 400B of autofocus support 165 on the rotation axis.
Turning now to
When the electric current changes, the magnetic attraction and repulsion changes as shown with imaging device 800C. In
Turning now to
In
In conclusion, many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of embodiments of the present invention. Embodiments of the present invention have been described with the intent to be illustrative rather than restrictive. Certain features and sub-combinations are of utility and may be employed without reference to other features and sub-combinations and are contemplated to be within the scope of the claims.
