Optical imaging device and method

Abstract

The present invention relates to an optical imaging device and method for reading an optical code. The imaging device comprises a sensor, a lens, a plurality of lighting devices and a plurality of reflective surfaces. The sensor is configured to sense using a predetermined number of pixel rows, wherein the predetermined pixel rows are arranged in predetermined positions. The lens has an imaging path along an optical axis. The plurality of lighting devices are configured to transmit an illumination pattern along the optical axis, and the plurality of reflective surfaces are configured to fold the optical axis.

Description

[0001] This application is a divisional application with the application date of "August 25, 2017", application number "201710742440.8", and title "Optical imaging device and method".

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] not applicable.

[0004] STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0005] not applicable. Background Art

[0006] The use of identification codes to mark objects is commonly used in both industrial and commercial environments. For example, one-dimensional codes (bar codes) and two-dimensional codes have been placed on objects to allow for rapid identification of objects based on the data contained in the code. Typically, laser-based scanning devices and systems are used to read codes due to their ability to successfully scan codes when objects are moved quickly past the scanner. This can allow laser-based scanning devices to have very high scan rates (lines per second) when compared to other scanning devices.

[0007] Additionally, laser-based systems can be easily debugged because the laser scanner's read area can be clearly marked by a laser line. This can allow a user to quickly determine the correct alignment of the laser scanner with a peripheral device. Further, laser scanning devices can have a large viewing angle (e.g., 60 to 90 degrees). The large viewing angle allows the laser scanner to be mounted very close to the object to be scanned or the scanning area (i.e., a conveyor belt) while still maintaining an adequate read area to be able to read the code.

[0008] However, laser-based devices are subject to a variety of adjustments and are often adjusted to limit the energy that the laser can output. Such adjustments to the laser output power can limit the distance and field of view ("FOV") at which laser-based scanning devices and systems can be used. In addition, many laser-based scanning devices utilize rotating or vibrating mirrors to generate moving spots. These moving parts can subject the laser-based scanning system to additional wear and tear, and thereby reduce both the reliability and life of the device.

[0009] Previously, vision or camera based systems have been used in an attempt to provide an alternative to using laser scanning devices. However, previous vision or camera based systems did not have a scan rate sufficient to be able to scan many codes, especially in applications where codes need to be scanned quickly. For example, in an application where an object moves at a speed of approximately 1m / s, a laser scanner may scan a code at a rate of 1000 lines per second. Therefore, the code will only move 1mm between scans. However, a typical vision or camera based system may have a scan rate of only 30 frames per second, allowing approximately 33mm of movement between frames. This may result in missing codes or partially imaged codes, or it may be possible to not capture the code in any of the frames at all.

[0010] Further, in camera- or vision-based scanning systems, the angle of the field of view is determined by the focal length of the imaging lens and the size of the sensor. Typically, these systems have an angle of about 30 degrees to about 40 degrees. These angles are generally smaller than those of laser-based scanning systems. Therefore, in order for a camera- or vision-based scanning system to cover the same field of view as a laser-based scanning system, the camera- or vision-based scanning system must be placed farther away from the object to be imaged than the laser-based scanning system. Therefore, a solution for increasing the scanning rate of a vision system is needed. Summary of the invention

[0011] An optical imaging device for reading an optical code is disclosed. The imaging device includes an area sensor, a lens, a plurality of lighting devices, and a plurality of reflective surfaces. The sensor is configured to sense using a predetermined number of pixel rows, wherein the predetermined pixel rows are arranged in predetermined positions. The lens has an imaging path along an optical axis. The plurality of lighting devices are configured to transmit an illumination pattern by generating an illumination path along the optical axis, and the plurality of reflective surfaces are configured to fold the optical axis.

[0012] In some embodiments, only predetermined rows of pixels are used to image the object. The sensor may have 960 rows of 1280 pixels, and the predetermined number of rows of pixels to be used may be 40 rows.

[0013] In some embodiments, the multiple lighting devices are light emitting diodes. These lighting devices can be arranged on a plane that also contains the optical axis. The multiple reflective surfaces can be reflectors. Some embodiments include a reflective surface that is configured to fold an illumination axis along the same axis as the optical axis. In some embodiments, the folded optical axis reduces the minimum focus distance to the nearest reading plane. In addition, the folded optical axis can reduce the required installation space between the device and the nearest reading plane. Optionally, the illumination pattern generated by the lighting device is combined with a predetermined number of pixel rows for use by the sensor.

[0014] The optical imaging device may further include an exit window, wherein the illumination path and the imaging path will exit the optical imaging device through the exit window. In addition, the exit window may include a filter for filtering a predetermined band of the light wavelength spectrum in at least one of the imaging path and the illumination path. In some embodiments, the exit window includes a plurality of filters, and the filters in the imaging path and in the illumination path are polarized using cross-polarization directions.

[0015] A method for reading an optical code using an optical device is also disclosed. The method includes: focusing an imaging path along an optical axis using a lens; generating an illumination pattern; folding the imaging path using a plurality of reflective surfaces; and sensing an object in the imaging path using an area sensor. The lens is integrated into the optical device, and the illumination pattern has an illumination path along an axis approximately the same as the axis of the imaging path. The sensor uses only a predetermined number of pixel rows available to the sensor.

[0016] Optionally, the method may further include: folding the illumination pattern using the plurality of reflective surfaces. The method may further include: reducing reflections from the optical code using a filter, the filter may be a UV filter. The optical device may further include a filter in at least one of the imaging path and the illumination path for filtering out a determined band of the light wavelength spectrum. The illumination pattern may be generated using a plurality of illumination devices, and the plurality of illumination devices may be integrated into the optical device.

[0017] A folding attachment device for an existing optical imaging device is also disclosed. The folding attachment device includes a folded optical path portion and a linear illumination pattern generator. The folded optical path portion is configured to fold the optical path of the optical imaging device, and the linear illumination pattern generator is associated with a windowed portion of a sensor of the optical imaging device. Optionally, the linear illumination pattern generator may include at least one of a beam splitter and a dichroic mirror. The device may further include an inclined exit window, the inclined exit window being used to reduce reflections into the auxiliary device and may be inclined at approximately 15 to 30 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A general optical reader field of view determination is demonstrated.

[0019] Figure 2 Optical reader field of view determination with alternative lens focal lengths is demonstrated.

[0020] Figure 3A is a system view of a general optical reader.

[0021] Figure 3B is a system view of a general optical reader with a single foldout.

[0022] Figure 4 is a graphical representation of a windowed sensor.

[0023] Figure 5 is a graphical representation of a windowed sensor sensing a one-dimensional barcode moving in a defined direction.

[0024] Fig. 6A is a system view of an embodiment of a lighting device pattern layout of the illumination path on the same plane as the optical axis.

[0025] Figure 6B is an alternative system view of an embodiment of a lighting device pattern layout for illumination on the same plane as the optical axis.

[0026] Figure 7 is a system view of an alternative folded optical reader with a longer internal path.

[0027] Figure 8 is a system diagram of an exemplary imaging system with a multi-folded optical path.

[0028] Fig. 9 is a system diagram of an embodiment of a multi-reflective surface imaging system illustrating the folding of the optical path in the imaging system.

[0029] Fig.10 yes Figure 8 Isometric view of a multi-reflective surface imaging system.

[0030] Fig.11 yes Figure 8 Side view of a multi-reflective surface imaging system.

[0031] Fig.12 is a cross-sectional view of an alternative multi-reflective surface imaging system.

[0032] Fig.13 is an alternative embodiment of a multi-reflective surface imaging system where the illumination is not folded along with the imaging path.

[0033] Fig.14 is an alternative embodiment of a multi-reflective surface imaging system with a beam splitter for combining illumination paths and optical paths.

[0034] Fig.15 Possible illumination patterns using an optical imaging device as presented above are demonstrated.

[0035] FIG. 16A to FIG. 16C Several embodiments of illumination optics are presented.

[0036] Fig.17 is an alternative embodiment of a multi-reflective surface imaging system with a tilted exit window.

[0037] Fig.18 is a flow chart illustrating a process for sensing an object using an optical imaging system. DETAILED DESCRIPTION

[0038] Before explaining any embodiment of the present invention in detail, it should be understood that the present invention is not limited in its application to the construction details and component arrangements set forth in the following description or shown in the following drawings. The present invention can have other embodiments and can be practiced or executed in different ways. Moreover, it should be understood that the words and terms used herein are for illustrative purposes and should not be considered as restrictive. The use of "including", "comprising" or "having" and its variations herein is meant to cover the items listed thereafter and their equivalents and additional items. Unless otherwise specified or limited, the terms "mount", "connect", "support" and "couple" and their variations are used in a broad sense and cover direct and indirect mounting, connection, support and coupling. Further, "connect" and "couple" are not limited to physical or mechanical connections or couplings.

[0039] Additionally, use of the term "code" may be understood to refer to various readable codes, such as one-dimensional "barcodes," two-dimensional codes (eg, QD codes, etc.), and various other code types. Use of the term code is not limited to the type of code to which it is applied.

[0040] The following discussion is presented to enable those skilled in the art to make and use embodiments of the present invention. Various modifications to the embodiments shown will be very obvious to those skilled in the art, and the general principles herein can be applied to other embodiments and applications without departing from embodiments of the present invention. Therefore, embodiments of the present invention are not intended to be limited to the embodiments shown, but should conform to the widest range consistent with the principles and features disclosed herein. The following specific implementation paradigms are read with reference to the accompanying drawings, wherein the same elements in different figures have the same reference numbers. The drawings, which are not necessarily drawn to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the present invention. Those skilled in the art will recognize that the examples provided herein have many useful alternatives and fall within the scope of embodiments of the present invention.

[0041] Using imaging devices and systems to read codes or even perform basic imaging tasks requires that the imaging device or reader have a minimum distance from the object to be imaged in order to ensure that proper field of view and focus can be achieved. In some applications, the effective distance between the reader and the object to be imaged may sometimes be very limited. In some examples, the focal length of the lens used in the optical reader can be modified in order to reduce the minimum closest focus plane distance. However, reducing the minimum closest focus plane distance by reducing the focal length can increase the field of view angle, thereby increasing the size of the farthest imaging plane. This increase in the size of the farthest imaging plane can reduce the resolution of the farthest imaging plane, thereby making it more difficult to analyze smaller objects. The following can be used in the following Figure 1 and Figure 2 See the discussion of Adjusting the Focus to Reduce the Minimum Focus Distance for an example of adjusting the focus to reduce the minimum focus distance.

[0042] Figure 1 A general optical reader 100 is shown having a field of view ("FOV") 102. The reader 100 can be configured to read data between a first plane 104 and a second plane 106. The first plane 104 and the second plane 106 can be separated by a first distance 108. In one example, the distance can be 304 mm. However, the first distance 108 can be greater than 304 mm or less than 304 mm. Additionally, the first plane 104 and the second plane 106 can have defined widths. In one example, the first plane 104 can have a width of 100 mm and the second plane 106 can have a width of 254 mm. Thus, once the size of the sensor and the focal length of the lens within the reader are determined, the FOV 102 of the reader 100 can be defined. Figure 1 In the example of FIG. 1 , assuming a one-third inch sensor and a 9.6 mm focal length lens, the FOV 102 may be ±14 degrees, where the first plane 104 and the second plane 106 are arranged as discussed above. This results in a distance 109 between the first plane 104 and the reader 100 of approximately 203 mm. A distance 109 of 203 mm may not be suitable for some applications, especially where space is limited. The FOV 102 may generally be calculated by the equation where α is equal to the FOV angle 102; f' is equal to the focal length of the lens; and s is equal to the imaging sensor size. Alternatively, it can be determined by the equation The FOV is determined where y is equal to half the length of the second plane 106 (shown as distance 110); and d is equal to the distance from the reader 100 to the farthest plane 106 (shown as distance 112).

[0043] In order to reduce the minimum focus distance to the first plane 104, the focal length of the lens of the reader 100 may be reduced. Figure 2, an example imaging system 200 can be seen with a reader 202 having a lens with a focal length of 4.2 mm. The system 200 can further have a first plane 204 and a second plane 206 separated by a distance 208. For comparison purposes, in this example, the first plane 204 and the second plane 206 are separated by approximately 304 mm. Assuming the same one-third inch sensor is used, by increasing the focal length of the lens from Figure 1 The 9.6 mm focal length used in the system in FIG. 2 is reduced to 4.2 mm, and the minimum distance 210 from the first plane 204 can be reduced to 88 mm. Further, this changes the angle of the FOV 212 of the imaging path to approximately 30 degrees. In addition, assuming that the first plane 204 has a width of 100 mm, the width of the second plane 206 increases to 455 mm.

[0044] While the above examples provide possible solutions for reducing the minimum distance to an object to be imaged by an imaging system by reducing the focal length of the lens, in some examples, it may be possible to reduce the minimum distance to an object to be imaged to be sufficient for a given application. One solution for further reducing the space required between the imaging device and the object to be imaged is to fold the optical path. In one example, a reflector can be used to fold the optical path. However, other reflective surfaces can be used to fold the optical path, such as a prism that produces internal reflections.

[0045] Now go to Figure 3A and Figure 3B , an optical imaging system 300 can be seen. The optical imaging system 300 can have an imaging device 302. The imaging device 302 can include a sensor 303, one or more lighting devices 304, and an imaging lens 306. The optical imaging system can further include a reflective surface 308, such as Figure 3B As shown in , the reflective surface can be contained in the housing 310. In one embodiment, the sensor 303 can be a CMOS type sensor. Alternatively, the sensor 303 can be a CCD type sensor or other type of suitable sensor. In one embodiment, the sensor 303 can be an AR0134 sensor from Aptina. Imaging sensors can generally limit the object scanning speed due to the limited frame rate available in many digital imaging sensors. In order to increase the frame rate of a digital imaging sensor, the effective sensing area of ​​the sensor 303 can be reduced. For example, as Figure 4, a graphical representation of a sensing area 400 of a sensor can be seen. Sensing area 400 can include a plurality of pixels. The number of pixels in a given sensing area 400 determines the resolution of a given sensor. In some embodiments, the sensor can have millions of pixels (megapixels). For example, common sensor sizes can be 4 megapixels, 8 megapixels, 12 megapixels, etc. The higher the number of pixels in sensing area 400, the greater the resolution of the sensor. Although a larger pixel count increases the resolution of the sensor, the increase in resolution may have an adverse effect on the scanning speed due to the required processing power associated with the increased number of pixels.

[0046] In order to increase the scanning speed of the sensor without reducing the desired resolution, the sensing area 400 may be reduced so that only a portion of the sensing face 400 remains active. Figure 4 A first inactive region 402 and a second inactive region 404 are shown surrounding an active pixel region 406. In one embodiment, the active pixel region 406 can be sized to the expected FOV required to view a particular code. For example, in the case where a one-dimensional barcode is expected to be scanned in a particular orientation (i.e., vertically or horizontally), the active pixel region 406 can be oriented in a similar manner (vertically or horizontally). Further, since only a portion of the width of a given code is required for a one-dimensional code, the active region 406 can be reduced to a few pixel rows. For example, the active sensing region 406 can be reduced to between 10 and 50 rows. However, more or fewer pixel rows can also be used as needed for a given application. In one example, for a sensor having a resolution of 960 rows of 1280 pixels and a frame rate of 54 frames per second, by using 40 rows of 1280 pixels, the active sensing region 406 can be reduced by a factor of 24, and the frame rate can be increased by a corresponding factor of 24. When using an optical imaging system, this frame rate increase can allow for increased scanning speed and throughput. Additionally, the active sensing area 406 can be reduced to a number of rows between 10 and 100. Although the active sensing area 406 can be reduced to less than 10 rows, maintaining at least 10 rows may reduce the effects of bad pixels in the sensor. Further, maintaining at least 10 rows in the active sensing area 406 may improve the accuracy of the imaging device by providing increased information (compared to a row sensor).

[0047] Now go to Figure 5 , Figure 4The sensing face 400 of FIG. 4 is shown imaging a one-dimensional bar code 500 as it passes through the sensing face 400 in the direction shown. The orientation of the imaged code is such that the active sensing area 406 is able to image all of the data in the bar code 500, even if only a portion of the sensing face 400 is active. In one embodiment, the active sensing area 406 may be oriented horizontally (so as to coincide with the maximum dimension of the sensor) to allow for a larger FOV and better resolution, and may also be aligned with the direction of movement of the code.

[0048] Now return to Figure 3A and Figure 3B , the optical reader 300 may include one or more illumination devices 304. In one embodiment, the illumination device 304 may be a light emitting diode ("LED"). In some examples, the illumination device 304 may be a single-color LED. Alternatively, a multi-color LED may be used to allow different wavelengths to be presented to the object depending on the type of code to be imaged. In some embodiments, the illumination device 304 may output light at a constant output. Alternatively, the optical reader 300 may vary the output of the illumination device 304. For example, in some applications, the code to be read may be on a highly reflective object, where high intensity light may blur or "wash-out" the code. Therefore, the output of the illumination device 304 may be reduced to ensure proper illumination of the object. Additionally, the illumination device may include a reference to a light source. FIG. 16A to FIG. 16C The illumination optics are discussed in more detail.

[0049] In addition, as in Figure 3A and Figure 3B As shown in FIG. 3 , a filter positioned in the exit window 314 of the imaging device 300 can be used to filter out ambient light. In addition, the filter can be designed to filter out a certain band of the light wavelength spectrum, and can filter the imaging path, the illumination path, or both. In one example, the illumination device 304 can output light in the ultraviolet spectrum. Further, in some examples, the code on the object can be printed using fluorescent ink, where the emission wavelength is different from the excitation wavelength, and the use of a filter on the imaging path can only allow the fluorescence emission wavelength provided by the fluorescent ink to pass, thereby only allowing the object of interest (code) to be imaged.

[0050] In addition, cross-polarized light can be used to avoid reflections on the object to be imaged. This feature is advantageous when the code to be imaged is on a shiny surface or a reflective surface (e.g., a polished metal object). In order to polarize the light, a polarizer can be placed in front of the lighting device 304, and a polarizer with a polarization direction perpendicular to the illumination polarizer can be placed in the imaging path. In one embodiment, the polarizer can be integrated into the exit window 314. Alternatively, the polarizer can be incorporated into the lighting device 304 and incorporated into the imaging lens. Further, the polarizer can be placed directly in front of the lighting device 304 and directly in front of the imaging lens. In some embodiments, the polarization direction of the imaging path can be parallel to the illumination polarizer; alternatively, the polarization direction can be perpendicular to the illumination polarizer. Typically, the orientation of the polarizer is selected based on the application.

[0051] The one or more illumination devices 304 can be further oriented so that light is transmitted along an axis that is approximately the same as the optical imaging axis 312. In some embodiments, the illumination device 304 is arranged on a plane that contains the optical imaging axis 312. In one embodiment, the illumination device 304 can transmit light along an axis that is similar to but separate from the optical imaging axis 312. However, because both the optical imaging axis 312 and the illumination axis are approximately the same due to the use of the reflective surface 308, the two axes can be close enough so that the illumination device 304 provides illumination in the field of view of the optical reader 300.

[0052] In one embodiment, one or more illumination devices 304 may be used. Further, to help match the illumination pattern geometry to the imaging path or to coincide with a sensing region (e.g., active sensing region 406 discussed above). Fig. 6A An example of positioning lighting fixtures can be seen in . Fig. 6A A plurality of illumination devices 600 and imaging lenses 602 positioned within illumination optics 604 are shown. Fig. 6A As shown in FIG. 6 , the illumination devices 600 may be arranged linearly. Further, the illumination devices 600 may be evenly distributed on either side of the imaging lens 602. Alternatively, the illumination devices 600 may be distributed non-uniformly, or, if applicable, in a non-linear pattern. Fig. 6A The lighting device 600 arranged as in Figure 4 and Figure 5 The active sensing area 406 has a similar lighting pattern.

[0053] The illumination optics 604 can be produced in many ways. In some embodiments, the lighting device 600 is placed in an injection molded part (e.g., the illumination optics 604) and can take any desired shape, such as, FIG. 16A to FIG. 16CThe shapes of non-limiting examples for illumination optics are shown in FIG. In some embodiments, an aperture for an imaging path may be included. In some embodiments, the illumination optics are formed from a single injection molded component (e.g., Fig. 6A In other embodiments, the illumination optical devices can be combined together so that Figure 6B As shown in , multiple illumination optics (but not all illumination optics) are positioned in a group of injection molded parts. In still other embodiments, the illumination optics are positioned individually. It is further contemplated that other polymer molding processes may be used, such as thermoforming, compression molding, blow molding, or other processes known in the art.

[0054] In some embodiments, it is desirable to have an illumination device 304 that provides illumination along the same axis as the optical imaging axis. For example, when the imaging device is very close to the object to be imaged, it may be advantageous to provide illumination that is in line with the optical imaging axis. For example, it may be advantageous to provide illumination along the same axis as the optical imaging axis when imaging objects at long distances, because the illumination may be partially or completely outside the FOV after a certain distance if there is an angle between the imaging path and the illumination path. By having the illumination path in line with the optical imaging axis, the illumination will generally illuminate the FOV. This may further allow for increased efficiency when imaging objects at longer distances.

[0055] In addition, by providing illumination that is in line with the optical imaging axis, debugging and setting up the optical imaging system 300 can be assisted by allowing the user to use the illumination as a guide to know exactly where the imaging path is. Therefore, by providing illumination that is in line with the optical axis, the advantages of a laser-based scanning system can be incorporated into the optical imaging system. In some embodiments, a beam splitter (e.g., a 50% transmission, 50% reflection beam splitter) can be used to converge the illumination axis with the optical imaging axis. However, other optical manipulation devices can also be used. For example, when different wavelengths are used for the illumination path and the imaging path (e.g., when fluorescence imaging is used), a dichroic filter can be used instead of a beam splitter.

[0056] like Figure 3BAs shown in , the reflective surface 308 of the optical reader 300 can be used to "fold" the imaging path. In one embodiment, the reflective surface can be a mirror. Alternatively, other reflective materials, such as prisms, can be used. The reflective surface 308 can allow the optical reader 300 to be placed near the nearest desired reading plane. For example, the imaging lens 306 of the optical reader 300 can have a focal length of 4.2 mm, so that maintaining the desired FOV described above will result in a minimum focus distance of 88 mm. This will generally require the nearest reading plane to be at least 88 mm away from the imaging lens 306. In some applications, the distance to the first focal plane needs to be smaller, for example, 30 mm. However, by positioning the reflective surface 308 at a 45-degree angle, the optical imaging axis 312 can be folded at a 90-degree angle. This can allow the optical reader 300 to be positioned closer to the nearest reading plane. In this example, assuming that the reflective surface 308 is positioned approximately 30 mm from the focusing lens 306 and 30 mm from the exit window 314 of the housing 310, 60 mm of the 88 mm minimum focus distance can be positioned within the optical imaging system 300, thereby requiring only 28 mm of distance between the exit window 314 of the optical imaging system 300 and the nearest reading plane.

[0057] Now go to Figure 7 , an alternative embodiment of the optical imaging system 300 of FIG. 3 can be seen. Figure 7 An optical imaging system 700 is shown, which may include an imaging device 702. The imaging device 702 may include a sensor 702, one or more illumination devices 704, and an imaging lens 706. In similar embodiments, the one or more illumination devices 704 may be positioned in the same horizontal plane as the imaging lens 706. In embodiments such as this, multiple illumination devices 704 may be positioned on either side of the imaging lens 706, e.g., Fig. 6A , Figure 6B 6 and imaging lens 602 shown in the orientation or those other orientations discussed above. The optical imaging system can further include a reflective surface 708, which can be contained in the housing 710. However, in this embodiment, the reflective surface 708 can be positioned approximately 65 mm from the focusing lens 706 and 25 mm from the exit window 712 of the housing 710. This can allow a zero distance between the exit window 712 of the optical reader 700 and the nearest reading plane, wherein the imaging lens 706 has a focal length of 4.2 mm. Therefore, Figure 7 Possible modifications to the imaging path within optical imaging system 700 are shown to allow the minimum focus distance to be fully contained within optical imaging system 700. This can allow for additional flexibility when integrating optical imaging system 700 into an application.

[0058] Now go to Figure 8 , further embodiments of the optical imaging system can be seen. Figure 8 An optical imaging system 800 is shown. The optical imaging system 800 may include an imaging device 802. The imaging device 802 may include a sensor 803, one or more lighting devices 804, and an imaging lens 806. The optical imaging system 800 may further include a first reflective surface 808, a second reflective surface 810, and a third reflective surface 812. The reflective surfaces 808, 810, 812 may be contained within a housing 814. In this embodiment, the imaging path and the illumination path may be folded through the reflective surfaces 808, 810, 812 to allow for alternative housing 814 designs. Similar to the above, the reflective surfaces 808, 810, 812 may be positioned to allow the entire minimum focus plane distance to be contained within the housing 814, so that no additional distance is required between the exit window 816 and the nearest reading plane. However, the reflective surfaces 808, 810, 812 may also be positioned to minimize the size of the housing 814 while also limiting the additional distance required between the exit window 816 and the nearest reading plane, if applicable. Although optical imaging system 800 is shown as having three reflective surfaces, more or less than three reflective surfaces may be used, as applicable.

[0059] In some examples, the multi-reflective surface optical reader 800 can be used in applications where the focal length of the imaging lens 806 requires a larger minimum focal length. For example, Fig. 9A detailed view of a multi-reflective surface optical imaging system 900 is shown. The optical imaging system 900 may include an imaging device 902, which includes a sensor 903, one or more lighting devices 904, and an imaging lens 906. The imaging system 900 may further include an optical folding device 907, which may include a first reflective surface 908, a second reflective surface 910, and a third reflective surface 912. In one embodiment, the imaging device may be a DM150 or DM260 from Cognex. Further, a communication connection 914 coupled to the imaging device 902 can be seen. In one embodiment, the communication connection 914 may provide communication between the imaging device 902 and a processing device (not shown) such as a PC or a dedicated image processing system. In one embodiment, the communication connection 914 may communicate via a serial connection such as RS-262, RS-485, a universal serial bus ("USB"), or via other protocols such as Firewire, Ethernet, ModBus, DeviceNet, or other suitable communication protocols. In further embodiments, the communication link 914 may be a wireless communication link. For example, the communication link 914 may provide communication with other devices (e.g., the processing devices discussed above) using a wireless protocol (e.g., Wi-Fi, Zigbee, Bluetooth, RF, cellular (3G, 4G, LTE, CDMA), or other known or future developed wired or wireless communication protocols). Additionally, the communication connection 914 may be used to provide power to the imaging device 902. Alternatively, the imaging device 902 may have an alternative power source, such as a battery or a separate external power connection.

[0060] In this example, the imaging lens 906 may have a focal length of 6.2 mm. Thus, assuming the first imaging plane is approximately four inches wide, the minimum object distance will be 131 mm. However, using the equations described above, the minimum focal length may be determined for any given nearer and / or farther plane widths. Further, in the case where the imaging lens 906 lens has a focal length of 6.2 mm, the optical reader 900 may be designed to allow a minimum focus distance of 68 mm to be folded between the reflective surfaces 908, 910, 912. To do so, the distance (d1) between the focusing lens 906 and the first reflective surface 908 may be 15 mm; the distance (d2) between the first reflective surface 908 and the second reflective surface 910 may be 25 mm; and the distance (d3) between the second reflective surface 910 and the third reflective surface 912 may be 28 mm. Thus, a remaining distance of 63 mm is required between the third reflective surface 910 and the object plane 916 in order to achieve the minimum focus distance.

[0061] Because the imaging plane and the illumination plane are "folded" between the reflective surfaces 908, 910, 912, the FOV of the imaging plane increases, requiring the size of the reflective surfaces 908, 910, 912 to increase after each "fold". Using the values ​​discussed above, reflective surface 908 will need to be approximately 40 mm in size around the major axis. Reflective surface 910 will need to be approximately 60 mm in size around the major axis, and reflective surface 912 will need to be approximately 85 mm in size around the major axis. This can be done using the equation The size of the individual reflective surfaces is determined by α, where α is the FOV angle; L is the mirror length; and d is the distance between the mirror and the reader (or alternatively, the distance between the mirrors in a multi-mirror system). Thus, by varying the distances and sizes of the multiple reflective surfaces, the imaging path can be “folded” to allow for a more compact arrangement by reducing the required physical distance between the imaging device and the first imaging plane.

[0062] In addition, although the above optical imaging system 900 is described as a complete system, in some embodiments, it may be desirable to modify an existing imaging device (e.g., imaging device 902) by incorporating an optical folding device (e.g., optical folding device 907) onto the existing imaging device to allow the existing device to be modified accordingly.

[0063] Now go to Fig.10 , an isometric view of the optical imaging system 900 described above can be seen. Here, the FOV of the optical imaging path 1000 can be seen. Fig.10 , the FOV can have a substantially rectangular shape so as to coincide with the imaging surface 1002. The shape can be selected so as to process an optical code 1004 that may pass through the imaging surface 1002 in the direction shown. The rectangular shape can result from a windowed sensor as discussed above. Fig.10 Further shown is a housing 918 surrounding the imaging device 902 and the reflective surfaces 908 , 910 , 912 . Fig.11 A side view of the optical imaging system is shown at 900. Fig.11 As seen in FIG. 1 , the FOV of the optical imaging path 1100 can be seen as the imaging path exits the housing 918. In the example discussed above, the output angle can be approximately 21 degrees.

[0064] Now go to Fig.12, an alternative embodiment of a multi-reflection imaging system 1200 can be seen. Imaging system 1200 may include imaging device 1202. Imaging device 1202 may be an imaging device as discussed above. Imaging device 1202 may be attached to folding device 1204 via adapter plate 1206. Folding device 1204 may include a first reflective surface 1208, a second reflective surface 1210, a third reflective surface 1212, and an exit window 1214. The folding device may further include an illumination device 1216. Illuminating device 1216 may be a plurality of LEDs. Further, folding device 1204 may include an optical lens 1218. Optical lens 1218 may be positioned at the output end of illumination device 1216. In one embodiment, optical lens 1218 may create a line pattern using the output from the illumination device. As discussed above, this may assist in debugging and setting up imaging system 1200 by allowing a user to visualize where the optical imaging path is located, and improve illumination system efficiency. For example, the optical lens 1218 may be used to shape the illumination to match a mating active portion of a sensor 1222 in the imaging device 1202 to match the illumination pattern to the imaging path FOV.

[0065] Now go to Fig.13 , a further embodiment of the optical reader may be considered as an optical reader system 1300. The optical reader system 1300 may include an imaging device 1302 having an imaging lens 1304, a first reflective surface 1306, a second reflective surface 1308, and a third reflective surface 1310. The optical reader system 1300 may further include one or more illumination devices 1312. Fig.13 In an embodiment of the present invention, the illumination device 1312 can be positioned at the exit of the optical reader system 1300 and close to the exit window 1314. This can allow the illumination axis 1316 to have a generally same axis as the imaging axis 1318. Further, the illumination device 1312 can be configured to project light such that the imaged object 1320 is illuminated within the imaging FOV 1322.

[0066] Now go to Fig.14, a further embodiment of the optical reader system may be considered as an optical reader system 1400. The optical reader system 1400 may include an optical imaging device 1402 having an imaging lens 1404, a first reflective surface 1406, a second reflective surface 1408, and a third reflective surface 1410. In one example, the optical imaging device 1402 may be an optical imaging device as described above. The optical reader system 1400 may also include one or more illumination devices 1412. In one embodiment, the illumination device 1412 may be positioned below the first reflective surface 1406. The reflective surface 1406 may be configured to allow illumination to pass through the first reflective surface 1406 and align the illumination axis 1414 with the imaging axis 1416. In one embodiment, the first reflective surface 1406 may be a beam splitter. Alternatively, the first reflective surface 1406 may be a dichroic filter. By aligning the illumination axis 1414 with the imaging axis 1416, the imaging object 1418 may be illuminated on-axis through the imaging FOV 1420.

[0067] Fig.15 An illumination distribution pattern 1508 is shown where the illumination path is transmitted along the same or similar axis as the optical imaging path. Here, the imaging FOV 1502 is shown as projected from the optical imaging system 1504. Similarly, the illumination distribution pattern 1508 within the imaging FOV 1502 is shown as projected onto the imaging object 1506. Fig.15 As seen in FIG. 1 , the most intense illumination is shown in the darker portion of the illumination distribution pattern 1508, which is elongated in shape to coincide with the imaging FOV 1502. Such an illumination distribution shown in the illumination distribution pattern 1508 can provide complete illumination of the imaging object 1506 to allow for more efficient and accurate imaging. Figure 4 and Figure 5 As described above, the sensor in the optical imaging system 1504 is windowed into a predetermined number of pixel rows, and the illumination field 1500 can be combined with the number of pixel rows so that the illumination field 1500 does not extend outside the imaging FOV 1502. Fig.15 , imaging FOV 1502 is constrained, but it is important to note that illumination field 1500 may extend beyond the imaging FOV in multiple directions.

[0068] Now go to FIG. 16A to FIG. 16C , multiple illumination optical devices 1600, 1602 and 1604 can be seen. Fig.16A An exemplary image of a freeform illumination lens 1600 is shown. A freeform illumination lens may be specifically formed to shape and / or pattern illumination from a lighting device. Fig. 16BAn exemplary image of a cylindrical lens 1602 for use with a lighting device is shown. Finally, Fig. 16C A reflective optic 1604 is shown for use with a lighting device, in this example, a total internal reflection (TIR) ​​lens. Each of the illumination optics 1600, 1602, 1604 described above can be used to help shape and / or pattern illumination from a lighting device such as the lighting device described above.

[0069] Now go to Fig.17 , a further embodiment of the optical reader system may be considered as an optical reader system 1700. The optical reader system 1700 may include an optical imaging device 1702 having an imaging lens 1704, a first reflective surface 1706, a second reflective surface 1708, and a third reflective surface 1710. The optical imaging device 1702 may also include one or more lighting devices 1712. The lighting device 1712 may be configured to align the illumination axis with the imaging axis. The optical reader system 1700 may further include an exit window 1714. In one embodiment, the exit window 1714 may be tilted at an angle so as to reduce reflections along the imaging axis. In one embodiment, the exit window 1714 may be angled. In some embodiments, the exit window 1714 is angled at approximately 15 degrees. However, if applicable, the exit window may be angled at greater than 15 degrees or less than 15 degrees. For example, the exit window may be angled at approximately 30 degrees. Further, although the exit window 1714 is Fig.17 is shown as angled from left to right, but the direction of the angle can be modified to provide the optimal amount of reflection reduction in a given application.

[0070] Now go to Fig.18 , a process 1800 for sensing an optical code using an optical imaging system as discussed above can be seen. At process block 1804, an illumination pattern can be generated. In one embodiment, a plurality of lighting devices as discussed above can be used to generate the illumination pattern. Further, in some embodiments, at process block 1805, the illumination pattern can be shaped or filtered as described above. For example, a beam splitter, a dichroic filter and / or by positioning the illumination device in a pattern corresponding to the desired illumination pattern can be used to shape the illumination pattern and placed within the illumination path. In one embodiment, the illumination device can be an LED. At process block 1802, the imaging path can be focused using a lens of the optical imaging system. In one embodiment, the imaging path can be focused based on the focal length of the lens.

[0071] At process block 1806, the imaging path can be folded. In some embodiments, the imaging path can be folded using multiple reflective surfaces. For example, as described above, the imaging path can be folded using mirrors. Folding the imaging path can allow some or all of the minimum focus distance to be contained within the optical imaging system. Reducing the focus distance by folding the imaging path is discussed in more detail above. At process block 1808, the imaging path can be filtered. In some optional embodiments, the optical path is filtered at the exit window of the optical imaging system. For example, the exit window can have a UV filter, a polarizing filter, a dichroic filter, or other filter, as applicable. The exit window can also be tilted to provide filtering for reducing reflections returning along the imaging path. The exit window can be tilted between 0 and 30 degrees, such as, for example, 15 degrees. In some embodiments, the sensor can be windowed 1812 so that only a predetermined portion of the sensor is used to sense the object. As described above with reference to Figure 4 and Figure 5 As discussed, windowing can increase the sensing speed and refresh rate of the sensor by reducing the active pixel area. Finally, at process block 1810, an object in the imaging path can be sensed via the sensor of the optical imaging system. In addition, in some embodiments, after completing process block 1810, the image is registered and processed.

[0072] Although the above embodiments describe having one or three reflective surfaces arranged as in the figures, these embodiments are not meant to be limiting. It should be understood that using the above methods and systems, imaging systems can be designed to be accommodated in a variety of applications and systems.

Claims

1. An optical imaging device for reading an optical code, the device comprising: an area sensor including a first plurality of pixel rows, the area sensor being configured for sensing using only a second plurality of pixel rows, the second plurality of pixel rows being arranged in predetermined positions of the area sensor and including a smaller number of pixel rows than the first plurality of pixel rows; a lens having an imaging path along an optical axis; as well as A lighting device is configured to deliver a lighting pattern by generating a lighting path that is aligned with the optical axis.

2. The device according to claim 1, wherein: The lighting device is arranged on a plane including the optical axis.

3. The device of claim 1, wherein: The illumination pattern is matched to predetermined rows of pixels of the sensor.

4. The device of claim 1, wherein: The device also includes a reflective surface configured to fold the optical axis.

5. The device of claim 1, wherein: The second plurality of pixel rows are read out at a second frame rate that is greater than a first frame rate at which the first plurality of pixel rows are configured to be read out, wherein the second frame rate is greater than the first frame rate in proportion to a ratio of the number of pixel rows in the first plurality of pixel rows to the number of pixel rows in the second plurality of pixel rows.

6. The device of claim 1, further comprising an exit window, wherein: The illumination path and the imaging path exit the optical imaging device through the exit window.

7. The device of claim 6, wherein: The exit window includes a filter in at least one of the imaging path and the illumination path for filtering a predetermined band of the light wavelength spectrum.

8. The device of claim 7, wherein: The exit window includes a plurality of filters, and the filters in the imaging path and in the illumination path are polarized using crossed polarization directions.

9. The device of claim 1, wherein: The first plurality of pixel rows each include at least 960 rows of at least 1280 pixels, and the second plurality of pixel rows include no more than 40 rows of pixels out of the at least 960 rows.

10. The device of claim 4, wherein: Folding the optical axis reduces the required installation space between the device and the nearest reading plane.

11. A method for reading an optical code using an optical device, the method comprising: generating an illumination pattern having an illumination path aligned with an axis aligned with an axis of the imaging path; focusing the imaging path along an optical axis using a lens, the lens being integrated into the optical device; as well as An object in the imaging path is sensed using an area sensor comprising a first plurality of pixel rows, wherein the area sensor is configured for sensing using only a second plurality of pixel rows, the second plurality of pixel rows comprising a less number of pixel rows than the first plurality of pixel rows.

12. The method of claim 11, wherein: The first plurality of pixel rows are aligned in parallel with a direction of movement of the object being sensed.

13. The method of claim 11, further comprising: Multiple reflective surfaces are used to fold the lighting pattern.

14. The method of claim 11, wherein: The optical device includes a filter in at least one of the imaging path and the illumination path.

15. The method of claim 11, wherein: The lighting pattern is generated using a plurality of lighting devices.

16. The method of claim 15, wherein: The plurality of lighting devices are integrated into the optical device.

17. A folding attachment device for an existing optical imaging device, the existing optical imaging device including an area sensor, the folding attachment device comprising: a folded optical path portion configured to fold an optical path of an area sensor of the optical imaging device, the area sensor having a first plurality of pixel rows and configured to sense using only a second plurality of pixel rows, wherein the second plurality of pixel rows are arranged in a windowed portion of the area sensor and include a smaller number of pixel rows than the first plurality of pixel rows; as well as A linear illumination pattern generator is associated with a windowed portion of the area sensor of the optical imaging device.

18. The apparatus of claim 17, wherein: The linear illumination pattern generator includes at least one of a beam splitter and a dichroic mirror.

19. The device of claim 17, further comprising a tilted exit window for reducing reflections into the device.

20. The apparatus of claim 19, wherein: The inclined exit window is inclined at 14.5 to 30.5 degrees.

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