Patent Application
20070295817
Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
Embodiments of an automatic data collection apparatus and method for variable focus using a deformable mirror are described herein. In the following description, numerous specific details are given to provide a thorough understanding of embodiments. One skilled in the relevant art will recognize, however, that the embodiments can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.”
The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed invention.
As an overview, an automatic data collection device of an embodiment is provided for reading a target machine-readable symbol, such as barcode symbols, stacked code symbols, matrix code symbols, or other types of one-dimensional (1D) or two-dimensional (2D) machine-readable symbols by scanning. The data collection device includes a light source to provide a scanning beam to scan the target machine-readable symbol and a scanning mirror to deflect the scanning beam across the target machine-readable symbol. The scanning mirror of one embodiment is a microelectromechanical structure (MEMS) mirror.
In one embodiment, the automatic data collection device further includes a deformable mirror that operates in conjunction with the scanning mirror to enhance reading capabilities from near to far fields, or to otherwise improve focusing or other optical capabilities of the data collection device. The deformable mirror provides dynamic wavefront correction so as to control the focus and/or beam divergence, while the scanning mirror creates a back and forth exploration of the region of the target machine-readable symbol that is being scanned. The deformable mirror can comprise a deformable silicon membrane in one embodiment.
An embodiment of the automatic data collection device can further include a focus control algorithm that attempts to optimize the focus, in response to degrees of focus that are measured from incoming scan data from the target machine-readable symbol. A decoding algorithm of the automatic data collection device can be provided with the incoming scan data that is usable to measure or otherwise determine the degrees of focus, and can then provide this feedback information to the focus control algorithm to allow the focus control algorithm to generate control signals to change the shape of the deformable mirror. Thus, the longer a user of the automatic data collection device waits, the sharper (or more focused and accurate) the scanning operation and the resultant scanning data can become.
The data collection device 10 includes a head 16, a handle 18, and an actuator such as a trigger 20. While the trigger 20 is shown with a specific shape and in a specific location in the embodiment of
The data collection device 10 can comprise a portable data collection device, a hand-held scanning device, or other suitable electronic device having the various data reading capabilities described herein. It is appreciated that some embodiments are provided that may not necessarily have the same shape or identical features or identical use as the embodiments illustrated in the various figures. However, such embodiments can nevertheless include a deformable mirror as will be explained in detail below.
The scanning beam 14 is symbolically depicted (for purposes of simplicity) in
As shown in the embodiment of
In one embodiment, the data collection device 10 includes a light detector 42 and one or more light sources 44 to generate light for the scanning beam 14 that reads a target machine-readable symbol, such as the barcode symbol 12. An example of the light source 44 of one embodiment is a laser, light emitting diode (LED), or other suitable light source that can be used for scanning the target barcode symbol 12.
The data collection device 10 can employ suitable optics such as one or more lenses 45 (such as a pre-focusing lens), a deformable mirror 48, and a scanning mirror 46 that is used to move the scanning beam 14 across the target barcode symbol 12. In operation, the light source 44 generates a light, and the light is then directed through the lens 45 (which can for example collimate the light) to the deformable mirror 48. The deformable mirror 48 then reflects or returns or otherwise directs the light onto the scanning mirror 46.
The scanning mirror 46 is driven or otherwise actuated by an actuator 55, so as to cause the light incident thereon to be scanned across the target barcode symbol 12 as the scanning beam 14. In one embodiment, the scanning mirror 46 comprises a MEMS mirror, and the actuator 55 can comprise an electrostatic actuator, a piezoelectric actuator, or a magnetic actuator.
The deformable mirror 48 of an embodiment comprises a deformable silicon membrane. The components of an embodiment of the deformable mirror 48 and an embodiment of a process for manufacturing the deformable mirror 48 will be described in more detail later below.
In an embodiment, the deformable mirror 48 is deformed (or otherwise actuated in a manner that the shape of the deformable mirror 48 is changed) by an actuator 56. The actuator 56 can comprise an electrostatic actuator, a piezoelectric actuator, or a magnetic actuator. For example, with an embodiment of the deformable mirror 48 that includes electrodes for applying repulsive/attractive electrostatic forces to a deformable silicon membrane, the actuator 56 can be an electrostatic actuator that applies the appropriate amount and the appropriate polarity of voltage potentials to specific electrodes.
The light detector 42 (such as a photodetector, phototransistor, or other type of light detector) can be positioned in a manner to sense light from the scanning beam 14 that is reflected or otherwise returned back from the target barcode symbol 12 and to generate an analog electrical signal (or other type of signal) representative of the received returned light.
An analog-to-digital (A/D) converter 50 transforms the analog electrical signals from the photodetector 42 and/or other signals into digital signals. For example for returned light that is received by the photodetector 42 that contains encoded data, the digital signals obtained from the received signals can be processed to decode or otherwise obtain the underlying encoded data.
In an embodiment, the signal generated by the light detector 32 also can be used to determine a degree of focus or other characteristic associated with the scanning beam 14. For example and as will be explained in further detail below, the signal generated by the light detector 42 can be analyzed to determine whether improved focusing is needed to get an improved read of the target barcode symbol 12, and if necessary, such feedback information can be used cause the deformable mirror 48 to change its shape to thereby change the focus.
The data collection device 10 of
Moreover, in one example embodiment at least one digital signal processor (DSP) 38 may be provided to cooperate with the microprocessor 34 to process signals and data returned from the symbols. Such signal processing may be performed for purposes of reading data from signals received from the target machine-readable symbol. For instance during decoding, the DSP 38 can perform image processing to extract the encoded data from the scanned target barcode symbol 12. The DSP 38 can also be used to process signals that result from scanning other types of 1D or 2D machine-readable symbols and/or from imaging machine-readable symbols (if the data collection device 10 is a multi-mode device having imaging capability).
In an embodiment, the microprocessor 34 can execute software or other machine-readable instructions stored in a machine-readable storage medium in order to perform the decoding or to otherwise control operation of the data collection device 10, including operations associated with determining the degree of focus (or other property/characteristic) of the scanning beam 14 based on the data provided by the A/D converter and operations associated with making adjustments to the shape of the deformable mirror 48 to change the focus or other characteristic of the scanning beam 14. Such a storage medium can be embodied by a random access memory (RAM) 36, a read only memory (ROM) 40, or other storage medium 41. The software stored in the storage medium 41, for example, can include the focus control algorithm that can be used to assess the degree of focus, depth of field, or other scanning-related feature of the data collection device 10, and that can then initiate adjustment of the deformable mirror 48.
As used in this herein, the ROM 40 includes any non-volatile memory, including erasable memories such as EEPROMs. The RAM 36 is provided to temporarily store data, such as a digital data from the A/D converter 50. The RAM 36 can also store other types of data, such as variable values, results of calculations, state data, or other information.
Symbol reading and decoding technology is well known in the art and will not be discussed in further detail. Many alternatives for scanners, symbol decoders, and optical elements that can be used in the data collection device 10a are taught in the book, The Bar Code Book, Third Edition, by Roger C. Palmer, Helmers Publishing, Inc., Peterborough, N.H., U.S.A. (1995) (ISBN 0-911261-09-5). Useful embodiments can also be derived from the various components disclosed in U.S. Pat. No. 6,286,763, issued Sep. 11, 2001, and assigned to the same assignee as the present application.
The data collection device 10 can include a communication port 52 to provide communications to external devices. The communication port 52 can be a hardwire or wireless interface, and can even employ an antenna, radio, USB connection, Ethernet connection, modem, or other type of communication device. The communication port 52 can provide communications over a communications network (not shown) to a host (not shown), allowing transmissions of data and/or commands between the data collection device 10 and the host. The communications network can take the form of a wired network, for example a local area network (LAN) (e.g., Ethernet, Token Ring), a wide area network (WAN), the Internet, the World Wide Web (WWW), wireless LAN (WLAN), wireless personal area network (WPAN), and other network. Alternatively or additionally, the communications network can be a wireless network, for example, employing infrared (IR), satellite, and/or RF communications.
The data collection device 10 includes a keypad, mouse, touch screen, or other user input device 54 to allow user input. It is appreciated that other devices for providing user input can be used. The user input device 54 is usable to allow the user to select modes (e.g., modes for reading matrix code symbols, barcode symbols, or other symbols), turn the data collection device 10 ON/OFF, adjust power levels, and others. The bus 28 couples the user input device 54 to the microprocessor 34 to allow the user to enter data and commands.
The bus 28 also couples the trigger 20 to the microprocessor 34. In response to activation of the trigger 20, the microprocessor 34 can cause the light source 44 to generate light that can be used as the scanning beam 14. In one embodiment, an initial press of the trigger 20 can be used to generate the scanning beam 14 to scan the target barcode symbol 12 and to initiate analysis of the returned light to determine degree of focus, depth of field, or other optical feedback information for adjusting the deformable mirror 48. Then, a subsequent or additional pressing of the trigger 20 can be used to initiate the final scanning, after the degree of focus or other characteristic associated with the scanning beam 14 has been optimized.
The data collection device can 10 include human-perceptible visual (e.g., a display output) and audio indicators 56 and 58 respectively. The bus 28 couples the visual and audio indicators 56 and 58 to the microprocessor 34 for control thereby. The visual indicators 56 take a variety of forms, for example: light emitting diodes (LEDs) or a graphic display such as a liquid crystal display (LCD) having pixels. These or other visual indicators can also provide other data associated with the operation of the data collection device 10, such as visual indicators to indicate whether the data collection device 10 is ON/OFF, reading, interrogating, low on battery power, successful or unsuccessful reads/interrogations, and so forth.
The audio indicator 58 can take the form of one or more dynamic electrostatic or piezo-electric speakers, for example, operable to produce a variety of sounds (e.g., clicks and beeps), and/or frequencies (e.g., tones), and to operate at different volumes. Such sounds can convey various types of information, such as whether a symbol was successfully or unsuccessfully read, low battery power, or other information.
Referring first to
The lens 45 directs the collimated light 62 onto a reflective surface of the deformable mirror 48. The deformable mirror 48 is shaped and positioned such that the collimated light 62 incident thereon is directed to the scanning mirror 46. The light received by the scanning mirror 46 from the deformable mirror 48 is represented in
As an example, if the reflective surface of the deformable mirror 48 has a generally flat shape, then the focal distance is theoretically at infinity. If the reflective surface of the deformable mirror 48 is changed to a generally elliptical shape, then the focal distance can be suitably controlled or otherwise set to a distance for optimum scanning, such as a 200 mm focus distance between the target barcode symbol 12 and the data collection device 10 in some situations. Therefore, to provide longer focal distances (thus also increasing the depth of field), the reflective surface of the deformable mirror 48 can be deformed to a flatter shape, as compared to a shape with a more pronounced curvature (for shorter focal distances and a decrease of the depth of field).
Controlling more accurately the wavefront of the light 64 enables increased control of beam divergence. Providing a profile of the light 64 (and hence the scanning beam 14) in this manner can produce a quasi-free diffraction effect in one embodiment, where a center peak of the scanning beam 14 can be invariant over an extended range. Furthermore, it is possible to extend the identification depth of field measured at a low modulation transfer function (MTF).
In an embodiment, the shape of the deformable mirror 48 can be controlled in a manner that addresses comas or other types of optical aberrations. For example, due to an angle of incidence of the collimated light 62 on the reflective surface of the deformable mirror 48, a coma (off-axis light rays that do not converge at a focal plane) may result. However, an embodiment can correct or otherwise compensate for this coma by providing the reflective surface of the deformable mirror 48 with an asymmetric curvature. For instance, one or more electrodes (or other conductors or actuators) underneath the reflective surface of the deformable mirror 48 can be slightly shifted off-center to provide the appropriate asymmetric curvature, such as where a curvature on one side relative to the center is different than a curvature on a second side relative to the center.
In an embodiment, the shape of the deformable mirror 48 can be controlled or otherwise tailored using an arrangement of electrodes that produce an electric field that applies forces to the deformable mirror 48. Voltage potentials can be applied to the electrodes to dynamically change the shape of the deformable mirror 48, such as in response to feedback information that indicates a need to change focus.
In an embodiment, the manner in which to apply the voltage potentials (e.g., specific voltage amplitudes, selection of specific electrodes to receive the voltage potentials, sequence and timing of application of the voltage potentials, etc.) can be based on pre-loaded maps or other settings contained in the storage medium 41 (or other storage medium) that are used by the microprocessor 34. For example, with regards to sequence and timing, voltage potentials can be applied to certain electrodes before other electrodes. The geometry or other manner of arrangement of the electrodes can include, but not be limited to, concentric, sectored, striped, annular, checkerboard, matrix, or other suitable electrode arrangement.
The user activates the data collection device 10 for scanning the target barcode symbol 12 at a block 72. In one embodiment, pressing the trigger 20 can cause this activation. In yet another embodiment, the user can partly (not fully) press the trigger 20 at the block 72, thereby initiating a process in which scanning and decoding is performed to determine degree of focus, for example, for changing the shape of the deformable mirror 48 for adjustment purposes, but without yet performing final data acquisition.
The light source 44 generates the scanning beam 14 at a block 74. For example and as shown in
The light detector 42 receives the returned light from the target barcode symbol 12 at a block 76, and the returned light is converted to digital data by the A/D converter 50. The decoding algorithm decodes the digital data to obtain the data encoded in the target barcode symbol 12.
Whether or not to change the shape of the deformable mirror 48 (and by how much) can be based on one or more of the returned light (in analog form) received by the light detector 42, the digital data provided by the A/D converter 50, or the data decoded from the digital data. Such determination or other evaluation can be performed at a block 78.
For example, the strength of the analog signal provided by the light detector 42 can be indicative of the focal distance between the target barcode symbol 12 and the data collection device 10. If the strength of the analog signal is too weak or otherwise falls below some minimum threshold level, then such a condition may indicate that the data collection device 10 is positioned too far from the target barcode symbol 12. Therefore, the curvature of the deformable mirror 48 may be decreased (to increase the flatness of the shape), thereby lengthening the focal distance.
Conversely, if the strength of the analog signal is too strong or otherwise exceeds some maximum threshold level, then such a condition may indicate that the data collection device 10 is positioned too close to the target barcode symbol 12. Therefore, the curvature of the deformable mirror 48 may be increased (to decrease the flatness of the shape), thereby shortening the focal distance.
In one embodiment, the digital data provided by the A/D converter 50 is evaluated at the block 78 using the focus control algorithm stored in the storage medium 41 and executable by the microprocessor 34. For instance, the digital data can be evaluated for values that fall within or outside of certain expected values.
In yet another embodiment, the decoded data can be evaluated. For example, the decoding algorithm can decode the digital data, and then the focus control algorithm evaluates the results of the decoding. If the decoded data indicates missing or incorrect characters (characters from a UPC code, for instance), then such a result may indicate that the target barcode symbol 12 is positioned too far away, thereby resulting in missing/incorrect data.
As yet another example to evaluate the digital data and/or the decoded data, the digital data and/or the data decoded therefrom as a result of two or more scanning operations can be compared with one another. If two or more consecutive scans of the same barcode symbol 12 result in identical decoded data or other identical values, then such a condition may indicate that the proper focal length is present. Conversely, if there are inconsistent results in decoding data from the same target barcode symbol 12, then such a condition may indicate that the focal distance is not correct, thereby resulting in erroneous readings.
Other techniques for evaluating the analog signal, the digital data, the results of the decoding, etc. can be used by the focus control algorithm to determine the degree of focus, depth of field, or other property associated with the scanning beam 14 at the block 78.
At a block 80, the microprocessor 34 cooperates with the focus control algorithm to determine whether and to what degree to change the shape of the deformable mirror, based on the evaluation performed at the block 78 that generates feedback information. If the evaluation at the block 78 indicates that the shape of the deformable mirror 48 needs to be changed (such as to change the focal distance), then the shape of the deformable mirror is changed at a block 82.
As explained above for one embodiment, the shape of the deformable mirror 48 can be changed or otherwise controlled by application of voltage potentials to electrodes of the deformable mirror 48. The changes may be provided incrementally, until an optimum shape of the deformable mirror 48 is obtained. Therefore, the process described above in blocks 76-82 can be repeated as necessary (e.g., decoding, evaluating results, changing the shape in response, etc.).
If the microprocessor 34 determines that no further change in the shape of the deformable mirror 48 is needed at the block 80, such as if the focal length is optimum, then a confirmation can be provided to the user at a block 84. For example, a flashing light, a green light, a beep, or other indicator can be provided to the user to indicate that the focus is optimum. The user can then fully press the trigger 20 or take some other action to perform the final scan and/or final decode at a block 86. Alternatively or additionally, the final scan and/or final decode need not necessarily be performed at the block 86—the scanning and decoding result before confirmation of optimum focus can be used as the “final” result, without having to perform additional scanning or decoding.
In one embodiment, the audio or visual confirmation to the user at the block 84 need not be provided. The final result of the decoding, after having reached optimum focus, can be identified and processed appropriately in a manner transparent to the user and without requiring any further action from the user.
Referring first to
Then, silica 90 is deposited via plasma enhanced chemical vapor deposition (PECVD) on the backside of the wafer 80 to act as a mask for backside etching. Afterwards, a first photolithography level (such as by using a photoresist 92) is realized on the front side of the wafer 80, followed by a dry etching of the surface layers 88, 82, and 84 up to the bulk silicon 86, thereby providing an aperture 94 for future electrical connections.
The photoresist 92 is stripped. A second photolithography (such as by using a photoresist 96) is performed on the backside of the wafer 80 to complete the aperture 94 for the electrical connections an aperture 98 for the reflective portion of the deformable mirror 48.
The silica 90 and bulk silicon 86 are dry etched to the buried silica 84. Next, the silica layers 88 on both sides of the wafer 80 are chemically etched to expose the silicon film 82, followed by metallic deposition to obtain a reflective surface 100, thereby resulting in a final mirror substrate portion 101. Any type of suitable metal material can be used for the metallic deposition for the reflective surface 100, including silver, gold, or other metallic material that can provide adequate reflectivity.
Referring next to
A first photolithography and chemical etching is performed at 108 to form specific individual electrodes 110. In an embodiment, at least some of the electrodes 110 are shifted away from a center 112 of the deformable mirror 48, such that the electrodes 110, when applied with voltage potentials, will deform the reflective surface 100 asymmetrically about the center 112. For example, a first part of the reflective surface 100 (on one side of the center 112) may have a more pronounced curvature relative to a second part of the reflective surface 100 (on another side of the center 112). As explained above, this is feature can be provided to correct for coma and/or other aberrations due to the angle of incidence of the light impinging on the reflective surface 100.
In one embodiment, this offset shifting of the electrodes 110 can be obtained by placing a greater number of electrodes on one side of the center 112, as compared to a second side of the center 112, for example. Alternatively or additionally, the electrodes 110 within either or both sides of the center 112 may be irregularly spaced.
PECVD deposition is then performed at 114 to encapsulate the electrodes 110 in silica. At 116, a second photolithography and etching is performed to form thrusts 118 that will support the mirror substrate portion 101 shown in
A seal 124 may be applied over to one or more surfaces of the deformable mirror 48 (e.g., over the silicon film 82, the reflective surface 100, the electrode substrate portion 122, the mirror substrate portion 101, etc.). With the deformable mirror 48 thus assembled, the deformable mirror 48 can then be installed into the data collection device 10, along with other components described above.
Therefore, from the description provided above, it is evident that one embodiment of the deformable mirror 48 provides finer control and tuning of the scanning beam 14. Furthermore, use of the feedback information for determining whether to adjust the shape of the deformable mirror 48 removes the need for a separate dedicated distance sensor to determine whether or not to make adjustments.
All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety.
The above description of illustrated embodiments, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments and examples are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention and can be made without deviating from the spirit and scope of the invention.
For example, the data collection device 10 has been described above in the context of a scanner-type device having the deformable mirror 48. It is appreciated that an embodiment can be provided where the data collection device 10 includes imaging capabilities, such as for imaging matrix code symbols or for imaging other types of 1D and/or 2D machine-readable symbol using imaging light. In such embodiments, the deformable mirror 48 can be used to change a shape of an imaging field, a divergence of an imaging beam, a focus of the imaging beam, or other property associated with the imaging light.
These and other modifications can be made to the embodiments in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. The scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
| Number | Date | Country | |
|---|---|---|---|
| 60805556 | Jun 2006 | US |
