Laser drive modes for aiming systems in bar code imagers

Abstract

Methods and systems for driving an aiming assembly of a bar code imager are provided. An example method includes obtaining an operating mode of a bar code imager having an aiming assembly, and in response, determining a duty cycle of an aiming pulse of the aiming assembly. The duty cycle is determined as a percentage of a frame duration of an imaging sensor, and further, such that the aiming pulse satisfies simultaneous constraints. The constraints include simultaneous peak pulse optical power constraints that are independent of frame duration and heat dissipation constraints that are dependent on frame duration.

Description

Technical Field

[0001] The present disclosure relates to laser drive modes for aiming systems of bar code imagers. Background Art

[0002] Bar code imagers use aiming systems that produce an aiming dot or other aiming pattern in the field of view to provide the user with a visual reference that can always be relied upon to align the imager with the bar code or other scannable mark. Typically, these aiming systems use red LEDs. More recently, as LED designs have improved, aiming systems have used green LEDs. The green aiming dot / pattern provides the user with greater visual contrast and greater visibility (especially at long range applications and outdoors), with more than 9 times greater visibility compared to a red LED source.

[0003] However, operating a green laser presents several challenges that limit its users, especially for high ambient temperature applications typical of small imaging engines and barcode readers. Green lasers operate at high operating voltages, which increases the need for heat dissipation within the barcode imager. The laser life of a green laser is shorter than that of a red light emitting diode because the operating current increases as the laser ages faster, which also results in higher self-heating. Another design challenge is that the reduced green wavelength reflectivity from the brown cardboard requires longer sensor exposure for aiming point visibility in the image. This can result in saturation of the image at lower ambient light levels, disabling ranging and select list functions.

[0004] Therefore, there is a need for improved green wavelength aiming systems and aiming system operation within a bar code imager.

[0005] Other issues affect the implementation of green laser use in bar code imagers. Complementary metal oxide semiconductor (CMOS) laser driver integrated circuits (ICs) have emerged in recent decades. These devices generally lack laser variability due to limited power supply capacity. That is, conventional laser drivers on ICs are insufficient to drive green lasers, thereby requiring additional higher voltage power supplies. Boost circuits are typically included to provide the additional power requirements at a fixed boost voltage, but such circuits are inefficient once the temperature of the laser changes. As a result, conventional laser driver circuits are highly inefficient during the operating life of the laser and waste a large amount of power that is always converted into heat, thereby placing further stress on the laser driver circuit.

[0006] Therefore, there is a need for systems and methods for an electrically efficient green laser diode drive system with a boost servo, for example, in a bar code imager. Summary of the invention

[0007] In an embodiment, the present invention is a bar code imager comprising: an imager configured to capture images on a field of view of the bar code imager, each image captured during a frame duration of the bar code imager; an aiming assembly comprising a green laser source and configured to generate a green laser aiming pattern within the field of view of the bar code imager and comprising emissions having a wavelength within 495nm-570nm; and a controller configured to determine an operating mode of the bar code imager and, in response, control a drive mode of the green laser source to generate the green laser aiming pattern as a single aiming pulse per frame duration and having a duty cycle within each frame duration that simultaneously satisfies a peak pulse optical power constraint that is independent of the frame duration and a heat dissipation constraint that is dependent on the frame duration.

[0008] In a variation of this embodiment, the operating mode of the bar code imager is any of: (i) a triggered horizontal mode, in which the imager captures images in response to an operable trigger, or (ii) a presentation mode, in which the imager captures images over a continuous time period comprising a plurality of continuous frame durations, wherein the heat dissipation constraints of the triggered horizontal mode are different from the heat dissipation constraints of the presentation mode.

[0009] In a variation of this embodiment, the green laser source has a Class 2 laser safety rating, and wherein the imager is configured to capture images at 60 frames per second, and wherein the duration of a single aiming pulse that triggers the horizontal mode is between 2 ms and 8 ms, and wherein the duration of a single aiming pulse that triggers the demonstration mode is between 0.5 ms and 2 ms.

[0010] In a variation of this embodiment, the peak pulse optical power constraint is an achievable emission limit for the aiming pulse.

[0011] In a variation of this embodiment, the achievable emission limit AEL_pulse of the aiming pulse in Watts (W) is expressed as: AEL_pulse=7×10 -4 (tp) -.25 , where tp is the pulse duration.

[0012] In a variation of this embodiment, the heat dissipation constraint is an achievable emission limit P_ave in Watts (W) for the average power of the aiming pulse within a time window formed by a plurality of consecutive frame durations, and is expressed as: P_ave = 7×10 -4 (T1) -.25 , where T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

[0013] In a variation of this embodiment, the duty cycle DC within each frame duration that satisfies both the peak pulse optical power constraint and the heat dissipation constraint is expressed as: Where Tf is the frame duration and T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

[0014] In a variation of this embodiment, the duty cycle DC within each frame duration that satisfies both the peak pulse optical power constraint and the heat dissipation constraint is expressed to be within +20% and -90% of the following values:

[0015] In a variation of this embodiment, the duty cycle of the aiming pulse is a non-overlapping duty cycle such that the sensor exposure window of the imager and the aiming pulse do not overlap during the frame duration.

[0016] In a variation on this embodiment, the duty cycle of the aiming pulse is an overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse at least partially overlap during the frame duration.

[0017] In a variation on this embodiment, the duty cycle of the aiming pulse is an overlapping duty cycle such that the aiming pulse occurs within a sensor exposure window of the imager during the frame duration.

[0018] In a variation of this embodiment, the peak optical power constraint is the peak power at the center spot of the green laser aiming pattern.

[0019] In another embodiment, the present invention is a method for driving an aiming assembly of a bar code imager, the method comprising: obtaining, at a controller, an operating mode of a bar code imager having an imager configured to capture multiple images on a field of view of the bar code imager, each image being captured during a frame duration of the bar code imager; in response to the operating mode, determining, at the controller, a duty cycle of a single aiming pulse per frame duration, the single aiming pulse comprising a green laser aiming pattern generated by a green laser source of the aiming assembly and comprising emissions having a wavelength within a range of 495 nm-570 nm, wherein determining the duty cycle of the green laser aiming pattern comprises identifying a duty cycle that simultaneously satisfies a peak pulse optical power constraint that is independent of the frame duration and a heat dissipation constraint that is dependent on the frame duration.

[0020] In a variation of this embodiment, acquiring the operating mode includes determining whether the bar code imager is in (i) a trigger level mode, in which the imager captures an image in response to an operable trigger, or in (ii) a presentation mode, in which the imager captures images over a continuous time period comprising a plurality of continuous frame durations, wherein the heat dissipation constraints of the trigger level mode are different from the heat dissipation constraints of the presentation mode.

[0021] In a variation of this embodiment, the green laser source has a Class 2 laser safety rating, and wherein the imager is configured to capture multiple images at 60 frames per second, and wherein determining a duty cycle of the green laser aiming pattern includes setting a duration of a single pulse that triggers a horizontal mode between 2 ms and 8 ms, and setting a duration of a single pulse that triggers a demonstration mode between 0.5 ms and 2 ms.

[0022] In a variation of this embodiment, it is characterized in that determining the duty cycle of the green laser aiming pattern includes determining a duty cycle DC that satisfies both the peak pulse optical power constraint and the heat dissipation constraint according to the following expression:

[0023] In a variation of this embodiment, determining the duty cycle of the green laser aiming pattern includes determining a duty cycle DC that satisfies both the peak pulse optical power constraint and the heat dissipation constraint by being within +20% and -90% of the following expression:

[0024] In a variation of this embodiment, the peak pulse optical power constraint is an achievable emission limit for the aiming pulse.

[0025] In a variation of this embodiment, the achievable emission limit AEL_pulse of the aiming pulse in Watts (W) is expressed as: AEL_pulse=7×10 -4 (tp) -.25 . .

[0026] In a variation of this embodiment, the heat dissipation constraint is an achievable emission limit P_ave in Watts (W) for the average power of the aiming pulse within a time window formed by a plurality of consecutive frame durations, and the heat dissipation constraint is expressed as: P_ave = 7×10 -4 (T1) -.25 . .

[0027] In a variation on this embodiment, the duty cycle of the aiming pulse is a non-overlapping duty cycle such that the sensor exposure window of the imager and the aiming pulse do not overlap during the frame duration.

[0028] In a variation on this embodiment, the duty cycle of the aiming pulse is an overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse at least partially overlap during the frame duration.

[0029] In a variation on this embodiment, the duty cycle of the aiming pulse is an overlapping duty cycle such that the aiming pulse occurs within a sensor exposure window of the imager during the frame duration.

[0030] In a variation of this embodiment, the peak optical power constraint is the peak power at the center spot of the green laser aiming pattern.

[0031] In another embodiment, a bar code imager includes: an imager configured to capture images on a field of view of the bar code imager, each image being captured during a frame duration of the bar code imager; an aiming assembly including a green laser source and configured to generate a green laser aiming pattern within the field of view of the bar code imager; and a controller configured to control a driving mode of the green laser source in response to an operating mode of the bar code imager to generate the green laser aiming pattern as a single aiming pulse per frame duration and having a duty cycle within each frame duration that simultaneously satisfies a minimum single pulse optical power condition of the aiming pulse and an average power condition within a sequence of aiming pulses.

[0032] In another embodiment, a bar code imager includes: an imager configured to capture images on a field of view of the bar code imager, each image being captured during a frame duration of the bar code imager; an aiming assembly including a green laser source and configured to generate a green laser aiming pattern within the field of view of the bar code imager; and a controller configured to control a drive mode of the green laser source in response to an operating mode of the bar code imager to generate the green laser aiming pattern as a single aiming pulse per frame duration and having a duty cycle within each frame duration within a predetermined tolerance range of an optimized state representing an intersection of a single pulse optical power rule of the aiming pulse and an average power within a regular sequence of aiming pulses. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, in which the same reference numerals represent the same or functionally similar elements throughout the different views, together with the following detailed description, are incorporated into and form a part of the specification and are used to further illustrate embodiments of the concepts of the claimed invention and to explain the various principles and advantages of those embodiments.

[0034] Figure 1 is a perspective view of an example scanning device according to various embodiments of the present invention.

[0035] Figure 2 It is a method for implementing the embodiment described in this article. Figure 1 00140] Block diagram of example logic circuitry for an example scanning device.

[0036] Figure 3 An example driving circuit configuration for driving a green laser diode according to various embodiments of the present invention is shown.

[0037] Figure 4 Another example driving circuit configuration for driving a green laser diode according to various embodiments of the present invention is shown.

[0038] Figure 5 An example method for driving a green laser diode according to various embodiments of the present invention is shown.

[0039] Figure 6 Methods for driving an aiming assembly of a scanning device according to various embodiments of the present invention are shown.

[0040] Figure 7 Frame durations of a scanning device image sensor are shown, showing an aiming pulse having a predetermined duty cycle, according to various embodiments of the present invention.

[0041] Figure 8 An example solution space for suitable duty cycles for aiming pulses within a frame duration for a scanning device according to various embodiments of the invention is shown.

[0042] Figure 9-11 Different synchronizations between an aiming pulse and an image sensor exposure window, both within a frame duration, are shown respectively according to various embodiments of the invention.

[0043] Those skilled in the art will appreciate that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the sizes of some of the elements in the drawings may be exaggerated relative to other elements to help improve understanding of the embodiments of the present invention.

[0044] Device and method construction have been represented in the drawings by conventional symbols where appropriate, showing only those specific details relevant to an understanding of the embodiments of the invention so as not to obscure the disclosure with details that would be apparent to one of ordinary skill in the art having the benefit of the description herein. DETAILED DESCRIPTION

[0045] Generally speaking, users of wireless (e.g., battery-powered) electronic devices expect the devices to apply power efficiently to maximize device uptime / lifetime and reduce corresponding costs due to excess power consumption and device maintenance and / or replacement. Many conventional wireless electronic devices include green laser diodes that are difficult (if not impossible) for IC laser drivers to power without an additional high voltage power supply. However, these conventional power supplies apply a fixed voltage intended to drive the green laser diode, and therefore are not able to efficiently apply different optimal voltages as the laser temperature changes.

[0046] The method / system of the present disclosure provides a solution to this power inefficiency problem associated with conventional power supplies. That is, the method / system of the present disclosure mitigates these inefficient power consumption (e.g., heat dissipation) problems associated with conventional power supplies by introducing a boost servo algorithm configured to determine an optimal boost voltage for driving a green laser diode. The boost voltage can be increased or decreased as needed to compensate for the forward voltage requirement on the green laser diode that varies with temperature. In this way, designers of such green laser diode systems may not need to select a fixed boost voltage to operate at all operating temperatures, thereby increasing the power consumption efficiency of the system. In addition, these power consumption efficiencies are further expressed when the green laser diode is pulsed (e.g., less than 100% duty cycle), where the boost voltage can be even further reduced to compensate for the inactive period of the laser. As a result, the method / system of the present disclosure maximizes device uptime / lifetime and increases overall power consumption efficiency by intelligently and actively adjusting the forward voltage provided to the green laser diode to adjust for temperature changes that occur during laser operation, thereby reducing excess power dissipation in the form of heat.

[0047] Further, scanning devices (such as bar code imagers) that use green laser sources in aiming systems are limited due to high operating voltages (which result in high heat) and due to shortened laser lifetime. Although green laser sources can produce higher contrast than red laser sources, in bar code imaging applications, green laser sources are more susceptible to ambient light saturation. As a result, green laser sources are typically operated at higher optical power output levels, but this exacerbates heat dissipation and laser degradation issues.

[0048] The method / system of the present disclosure provides a solution to the heat dissipation and laser degradation problems of scanning devices using green laser sources (particularly for aiming pattern generation) by determining and controlling aiming pulse parameters to meet multiple simultaneous operation constraints. As referred to herein, "green" laser light may refer to light emitted at a wavelength in a range between approximately 495 nanometers (nm) and 570 nm. More specifically, the laser diodes described herein may be configured to output light in a wavelength range of 510 nm to 525 nm.

[0049] Now referring to the accompanying drawings, Figure 11 is a perspective view of an example scanning device 100, such as a bar code imager, according to various embodiments of the present invention. The example scanning device 100 includes an example housing 102 in which an image sensor 106 is disposed. The image sensor 106 captures image data representing objects in a field of view 108, which is at least partially defined by a forward opening or window 110 (also referred to herein as an "optical window") on a front side 112 of the example scanning device 100. The example scanning device 100 includes an indicia decoder 114 in communication with the image sensor 106 and configured to receive the image data and decode indicia captured in the image data.

[0050] Figure 1 The example housing 102 includes a generally elongated handle or lower grip portion 116, and an upper body portion 118 having a front side 112 with a forward opening or window 110 located on the front side 112. The cross-sectional dimensions and overall dimensions of the grip portion 116 allow the example scanning device 100 to be conveniently held in the hand of an operator during operation. The forward opening or window 110 is configured to be generally facing away from the user when the user places the example scanning device 100 in a handheld position. Portions 116 and 118 may be constructed of a lightweight, resilient, impact-resistant, self-supporting material such as a synthetic plastic material. The housing 102 may be injection molded, but may also be vacuum formed or blow molded to form a thin hollow housing defining an interior space having a volume sufficient to contain the various components of the handheld scanner 100. Although the housing 102 is shown as a portable, point of transaction, gun-shaped, handheld housing, any other configuration may be used, including a hands-free configuration.

[0051] A manually actuatable trigger 120 is mounted in a moving relationship on the handle portion 116 in a forward region 124 of the handle portion 116. Once a target falls within the imaging field of view 108, an operator's finger may be used to actuate (e.g., depress) the trigger 120 to cause the image sensor 106 to capture an image of the target. As a result of actuating the trigger 120, the example scanning device 100 may generate an aiming pattern 109 using an aiming pattern component 122. The aiming pattern 109 may visually indicate the field of view 108 of the example scanning device 100 to an operator using the device 100, and may more specifically indicate areas within the field of view 108 where the device 100 may successfully scan and / or otherwise interpret indicia within the field of view.

[0052] The aiming pattern assembly 122 (comprising, for example, Figure 2The aiming pattern assembly 222 of the example scanning device 100 may include a green diode laser (within the aiming illumination component 222A) that is configured to output green laser light in response to receiving a forward voltage as a result of an operator actuating the trigger 120. As further discussed herein, the aiming pattern assembly 122 may also include a boost servo (not shown) that actively adjusts the boost voltage provided to the green diode laser in order to maximize the power consumption efficiency of the example scanning device 100.

[0053] In any case, once the aiming pattern component 122 has generated the aiming pattern, the operator can then adjust the orientation of the example scanning device 100 until the aiming pattern is centered over the indicia included as part of the target. The example scanning device 100 can then capture image data of the target using the image sensor 106, and thereafter proceed to decode any indicia included within the image by applying the indicia decoder 114 to the image data.

[0054] Figure 2 It means that it is possible to implement Figure 1 1 is a block diagram of example logic circuitry of an example scanning device 100. Figure 2 An example logic circuit is a processing platform 200 that is capable of executing instructions to, for example, implement the operations of the example methods described herein, as can be represented by the flowcharts of the drawings accompanying this specification. Other example logic circuits capable of, for example, implementing the operations of the example methods described herein include field programmable gate arrays (FPGAs) and application specific integrated circuits (ASICs).

[0055] Figure 2 The example processing platform 200 includes a processor 202, such as, for example, one or more microprocessors, controllers, and / or any suitable type of processor. Figure 2 The example processing platform 200 includes a memory (e.g., volatile memory, non-volatile memory) 204 accessible by a processor 202 (e.g., via a memory controller). The example processor 202 interacts with the memory 204 to obtain, for example, machine-readable instructions stored in the memory 204 corresponding to operations represented, for example, by the (multiple) flow charts of the present disclosure. Additionally or alternatively, the machine-readable instructions corresponding to the example operations described herein may be stored on one or more removable media (e.g., compact disks (CDs), digital versatile disks (DVDs), removable flash memory, etc.), which may be coupled to the processing platform 200 to provide access to the machine-readable instructions stored thereon. The processor 202 and the memory 204 are disposed in the housing 102.

[0056] Figure 2The example processing platform 200 includes one or more communication interfaces disposed in the housing 102, such as, for example, one or more network interfaces 206, and / or one or more input / output (I / O) interfaces 208. The communication interface(s) may enable Figure 2 The processing platform 200 can communicate with, for example, another device, system, a host system (e.g., an inventory management system, a POS station, etc.), a data store, a database, and / or any other machine.

[0057] Figure 2 The example processing platform 200 may include (multiple) network interfaces 206 to enable communication with other machines (e.g., inventory management systems, POS stations, etc.) via, for example, one or more networks. (Multiple) example network interfaces 206 include any suitable type of (multiple) communication interfaces (e.g., wired interfaces and / or wireless interfaces) configured to operate according to any suitable (multiple) communication protocols. Example network interfaces 206 include TCP / IP interfaces, Wi-Fi TM transceiver (e.g., in accordance with the IEEE 802.11x family of standards), Ethernet transceiver, cellular network radio, satellite network radio, or any other suitable interface based on any other suitable communication protocol or standard.

[0058] Figure 2 The example processing platform 200 may include (a plurality of) input / output (I / O) interfaces 208 (e.g., interface, near field communication (NFC) interface, universal serial bus (USB) interface, serial interface, infrared interface, etc.), to (1) implement user input (e.g., from Figure 1 The handheld scanner 200 may include: (1) receiving a trigger 120 (e.g., a touch screen, keyboard, mouse, touchpad, joystick, trackball, microphone, button, etc.), (2) communicating output data (e.g., mode change confirmation, visual indicator, instruction, data, image, etc.) to a user (e.g., via output device 210, speaker, printer, tactile device, etc.), and / or (3) interacting with other components of the handheld scanner 200 (e.g., imaging component 212, output device 210, etc.). Example output devices 210 may include sound generating devices, tactile devices, etc.

[0059] To capture images of objects and / or barcodes on objects, the example processing platform 200 includes an example imaging assembly 212 disposed in a housing. The imaging assembly 212 includes an image sensor 106 under the control of, for example, a processor 202 to capture image frames representing portions of an environment in which the example scanning device 100 operates that fall within an imaging field of view 108 of the imaging assembly 212. The image sensor 106 includes a plurality of photosensitive elements forming a substantially flat surface. The processor 202 may be communicatively coupled to the imaging assembly 212 via (multiple) input / output (I / O) interfaces 208.

[0060] The example imaging component 212 includes any number and / or type(s) of tag decoders 114 (e.g., tag decoders 114) to detect and / or decode a tag to determine a payload of the tag. In some examples, the tag decoder 114 is implemented by the processor 202. The tag decoder 114 transmits the decoded payload of the tag to a host system (e.g., via the processor 202) via a communication interface (e.g., network interface(s) 206 and / or I / O interface(s) 208).

[0061] The example imaging assembly 212 includes an optical assembly 214 to form an image of an object in the field of view 108 on a surface of the image sensor 106. The optical assembly 214 may include any number and / or type(s) of optical elements and / or components 214A, including, for example, one or more lenses, filters, focus motors, apertures, lens holders, liquid lenses, or any other components and / or optical elements.

[0062] To focus the imaging assembly 212 on the object, the example imaging assembly 212 may include a focus controller 212A, and the optical assembly 214 may include any number and / or type(s) of focusing components 214B (e.g., motors, liquid lenses, etc.). In some examples, the focus controller 212A is implemented by the processor 202. In some examples, the example imaging assembly 212 is a fixed focus scanner.

[0063] To illuminate the target to be imaged, the example imaging assembly 212 may include an illumination generator 212B. The illumination generator 212B may emit light in the field of view 108 to, for example, facilitate autofocus and / or improve the quality of image frames captured by the image sensor 106.

[0064] To generate the illuminated aiming pattern, the example imaging assembly 212 may include an aiming pattern assembly 222 (e.g., an implementation of the aiming pattern assembly 122). In general, the aiming pattern assembly 222 is configured to generate light through the optical window 110 of the example scanning device 100 to provide a clear illuminated aiming pattern in the field of view 108. The aiming pattern assembly 222 may include an aiming illumination component 222A, such as one or more light sources (e.g., lasers, LEDs, one or more apertures, one or more diffractive and / or refractive elements, etc.) and an aiming illumination controller 222B.

[0065] Aiming lighting controller 222B may generally control aiming lighting component 222A, in particular, by providing various amounts of power to component 222A. Aiming lighting controller 222B may include a boost regulator (not shown) configured to provide a boost voltage to, for example, an LED that is part of aiming lighting component 222A. Processor 202 may execute instructions (e.g., stored on memory 204) including a boost servo algorithm that may adjust the boost voltage provided by the boost regulator to provide an optimal voltage level to drive the LED. For example, processor 202 may cause a laser temperature sensor (not shown) included as part of aiming lighting controller 222B to obtain a temperature corresponding to the LED of aiming lighting component 222A, and may cause the boost regulator to provide an optimal voltage to the LED based on temperature changes during operation to compensate for changes in forward voltage requirements.

[0066] Figure 3 An example driving circuit configuration 300 for driving a green laser diode according to various embodiments of the present invention is shown. In general, the example driving circuit configuration 300 can adaptively provide various voltage outputs to drive the green laser diode in response to the changing operating conditions within the configuration 300 so as to maintain a constant optical power drive. As shown in the figure, Figure 3 Two servos are shown, one of which regulates the optical power of the laser diode (e.g., via a photodiode 310 and an optical power loop 312), and the other of which optimizes the electrical power delivered to the laser diode (e.g., via a boost servo 314). The example driver circuit configuration 300 may broadly include a discrete-time feedback loop that regulates the voltage provided to the diode in a manner that optimizes the electrical power efficiency of a green laser diode. Of course, while described herein as a green laser diode, it should be understood that such a configuration 300 may provide voltage to any suitable illumination source (e.g., a red LED) and / or other circuit components.

[0067] The example driver circuit configuration 300 may include a boost regulator 302 configured to provide a boost voltage V to a laser driver circuit 304, an optional laser current sensor 306, and a green laser diode 308. 升压 The boost regulator 302 may receive input power from an input power source (not shown) and may vary the boost voltage V in response to a decision made by the boost servo 314. 升压 The laser driving circuit 304 can use a driving voltage V 驱动 To drive the green laser diode 308, the laser current sensor 306 can optionally use a sensing voltage V 感测 to measure the current flowing to the green laser diode 308, and the green laser diode 308 can use the laser voltage V 激光器 To output green laser light, for example, as an aiming pattern of the example scanning device 100. Therefore, the boost voltage can be defined as:

[0068] V 升压 =V 驱动 +V 感测 +V 激光器 (1)

[0069] Therefore, the boost voltage V 升压 must be large enough to enable the laser driver circuit 304 to drive the green laser diode 308 without substantially exceeding the drive voltage V 驱动 300). In addition, the green laser diode 308 may have a range of forward voltages that can be used to efficiently drive the diode 308 based on the operating characteristics of the diode 308 (e.g., temperature). For example, when the green laser diode 308 is completely cold (e.g., has not yet begun to operate), the diode 308 may require more than 9V to generate green laser light. In contrast, when the green laser diode 308 is fully warmed up (e.g., has been operating for a significant duration), the diode 308 may require less than 5V to generate green laser light. Therefore, the boost regulator 302 and the boost servo 314 can actively adjust the boost voltage V during operation of the example driver circuit configuration 300. 升压 , in order to efficiently drive all components of configuration 300.

[0070] Specifically, the boost regulator 302 may have a programmable output to implement a boost voltage V based on the voltage requirements of the laser driver circuit 304, the green laser diode 308, and the optional laser current sensor 306. 升压 It should be noted that relative to the drive voltage V 驱动 and the laser voltage V 激光器 , sensing voltage V 感测Usually very small, so the sensing voltage V 感测 may not significantly affect the boost voltage V at any particular time 升压 Regardless, the boost regulator 302 may initially provide a maximum boost voltage V sufficient to drive all components of the example driver circuit configuration 300. 最大 , and the boost servo 314 can acquire / measure the laser voltage V 激光器 The boost servo 314 may not measure the boost voltage directly, and may instead measure the boost voltage V 升压 The associated parameters are programmed, and it is assumed that the boost regulator 302 delivers the programmed voltage after receiving a signal from the boost servo 314. For example, the boost servo 314 can acquire / measure the laser voltage V 激光器 And it can be assumed that the boost voltage V 升压 is the maximum boost voltage V 最大 In addition, the boost servo 314 can typically measure the laser voltage V at the anode of the green laser diode 308. 激光器 However, in some aspects, the boost servo 314 can measure the laser voltage V at the cathode of the green laser diode 308. 激光器 .

[0071] Use the laser voltage V 激光器 and the maximum boost voltage V 最大 , the boost servo 314 can determine the maximum boost voltage V 最大 and the laser voltage V 激光器 Whether the voltage difference between them exceeds the driving voltage V 驱动 , and if not, the boost servo 314 can cause the boost regulator 302 to continue to provide the maximum boost voltage V 最大 If the boost servo 314 determines the maximum boost voltage V 最大 and the laser voltage V 激光器 The voltage difference between them does exceed the driving voltage V 驱动 , the boost servo 314 can enable the boost regulator 302 to provide the optimal voltage V based on the excess voltage 最佳 For example, if the boost servo 314 determines the maximum boost voltage V 最大 and the laser voltage V 激光器 The voltage difference between them exceeds the driving voltage V 驱动 1V, the boost servo 314 can determine the optimal voltage V 最佳 Ratio to maximum boost voltage V 最大 1V smaller, and accordingly the boost regulator can output the optimal boost voltage V 最佳 =V 最大In this way, the boost servo 314 enables the boost regulator 302 to output a dynamic and higher voltage than the static boost voltage (eg, the maximum boost voltage V 最大 ) and thus waste a lot of power in conventional systems. A more electrically efficient boost voltage V 升压 , to drive the laser driving circuit 304 and the green laser diode 308.

[0072] Additionally, in some aspects, the green laser diode 308 can be pulsed such that the diode 308 has a duty cycle of less than 100%. In these aspects, although the boost voltage V 升压 The green laser diode 308 is not driven, but other components of the example driver circuit configuration 300 and / or other electrically coupled circuits (not shown) (e.g., additional lighting components, buck drive, etc.) may require power. The boost servo 314 can determine a low voltage VLOW sufficient to power these additional components during time periods when the green laser diode 308 is inactive (e.g., between laser pulses). Thus, the boost servo 314 can cause the boost regulator 302 to output an optimal boost voltage V when the green laser diode 308 is pulsing. 最佳 , and can make the regulator 302 output a low voltage VLOW when the diode 308 is inactive. For example, if the optimal boost voltage V 最佳 If the low voltage VLOW is 8V and the low voltage VLOW is 3V, the boost servo 314 can cause the boost regulator 302 to output 8V when the green laser diode 308 should emit light pulses, and the servo 314 can cause the regulator 302 to output 3V when the diode 308 should not emit light pulses (e.g., inactive, between pulses). In this way, the boost servo 314 and the boost regulator 302 can further increase the boost voltage V provided by the regulator 302 during the diode inactive period. 升压 The quiescent boost voltage (eg, the maximum boost voltage V 最大 ) to further improve the conventional system.

[0073] In some instances, the green laser diode 308 may remain inactive long enough to cool between subsequent drive events (eg, emitting laser pulses). In these instances, the optimal boost voltage V 最佳 may not be sufficient to drive diode 308, and boost servo 314 may need to determine an increased optimal drive voltage based on the current operating state of diode 308. Alternatively, green laser diode 308 may remain active long enough to heat up significantly and thereby reduce the voltage requirement to drive diode 308. In this case, the optimal boost voltage V 最佳The voltage required to drive the diode 308 may be exceeded, and the boost servo 314 may need to determine a reduced optimal drive voltage based on the current operating state of the diode 308. In either case, the boost servo 314 can actively update the optimal boost voltage V required to drive all components of the example driver circuit configuration 300 and / or any electrically coupled components (e.g., additional lighting components, buck drive, etc.) at a refresh rate (e.g., once every x laser cycles, once every x milliseconds, etc.). 最佳 .

[0074] Further, in some aspects, the boost servo 314 may also restore to the maximum boost voltage V after a rest period between laser pulses. 最大 For example, a user may pull the trigger 120 of the example scanning device 100, during which the boost servo 314 determines the optimal boost voltage V 最佳 After the user releases the trigger 120, the user may subsequently pull the trigger after a duration exceeding the rest period, so that the boost servo 314 determines the optimal boost voltage V corresponding to the operating state of the green laser diode 308 during the current trigger pull period. 最佳 Before, the boost regulator 302 is automatically made to output the maximum boost voltage V 最大 .

[0075] The example driving circuit configuration 300 also includes a photodiode 310 and an optical power loop 312 configured to maintain a constant optical power output of the green laser diode 308. The photodiode 310 may be included as part of the green laser diode 308 and may generate a voltage V 激光器 The optical power loop 312 receives the photocurrent and converts the photocurrent into a voltage signal that can adjust the output of the laser driver circuit 304 based on the operating state of the green laser diode 308 indicated by the photocurrent. The optical power loop 312 can adjust the voltage signal, for example, using an error amplifier (not shown) and a calibrated reference voltage, to maintain a constant optical power of the green laser diode 308. The output of the error amplifier can be periodically monitored by the boost servo 314 to ensure that there is enough headroom to maintain the optical output power, whereby the boost servo 314 can make changes to increase the boost voltage to add the required headroom. In addition, the output of the optical power loop 312 (e.g., gate voltage) can be received by the boost servo 314 and can be used by the boost servo 314 to determine adjustments to the voltage provided by the boost regulator 302, as described herein.

[0076] Additionally, the example driver circuit configuration 300 includes a ground 316 and an optional laser temperature sensor 318. The ground 316 may be an electrical ground for the example driver circuit configuration 300 such that a voltage (eg, V 升压 、V 驱动 、V 感测 and V 激光器 ). The path of current flowing to the green laser diode 308 can thus be described as flowing from the boost regulator 302 to the laser driver circuit 304, optionally through the laser current sensor 306, through the green laser diode 308, and ultimately to the ground 316. An optional laser temperature sensor 318 can be included as part of the green laser diode 308 and / or otherwise connected to the diode 308 to measure the operating temperature of the diode 308 before, during, and after an active (e.g., providing aiming illumination) period of time. In some aspects, the optional temperature sensor 318 can be communicatively coupled to the boost servo 314 such that the boost servo 314 can receive the laser operating temperature from the sensor 318 to determine an appropriate response to the boost voltage V provided by the boost regulator 302. 升压 changes.

[0077] The example driver circuit configuration 300 also includes other circuits 320, which may generally include other electronic components (multiple) electrically coupled to the boost regulator 302. For example, the other circuits 320 may include an illumination LED, a driver circuit, and / or any other suitable electronic components or combinations thereof. Figure 3 As shown, the other circuit 320 may also be electrically coupled to the ground 316 such that both the green laser diode 308 and the other circuit 320 receive the input drive voltage from the boost regulator 302 and discharge to the ground 316 .

[0078] Figure 4 Another example driver circuit configuration 400 for driving a green laser diode 406 according to various embodiments of the present invention is shown. Figure 3 The example drive circuit configuration 300 shown, configuration 400 includes a boost regulator 402, a green laser diode 406, a laser drive circuit 408, a boost servo 412, an optional laser current sensor 414, a ground 416, and an optional laser temperature sensor 418. In addition, the example drive circuit configuration 400 can be as previously described with reference to Figure 3 400 performs a similar voltage regulation function as described in the example drive circuit configuration 300 in FIG. 400 , however, differs from FIG. 400 in two notable aspects. Figure 3The illustrated configuration 300 differs in that 1) the green laser diode 406 represents a floating case laser without a photodiode (eg, photodiode 310), and 2) the laser driver circuit 408 is driven by a current regulation loop 410 in a constant current mode rather than a constant optical power mode.

[0079] Regardless, the example driver circuit configuration 400 can adaptively provide various voltage outputs to drive the green laser diode 406 in response to changing operating conditions within the configuration 400 so as to maintain a constant current. The example driver circuit configuration 400 can broadly include a discrete time feedback loop that adjusts the voltage provided to the diode in a manner that optimizes the electrical power efficiency of the green laser diode. Of course, while described herein as a green laser diode, it should be understood that such a configuration 400 can provide voltage to any suitable illumination source (e.g., a red LED) and / or other circuit components.

[0080] The boost regulator 402 is configured to provide a boost voltage V to the laser driver circuit 408, the current sensor 404 (also referred to herein as a “current sensing circuit”), and the green laser diode 406. 升压 The boost regulator 402 may receive input power from an input power source (not shown) and may vary the boost voltage V in response to a determination made by the boost servo 412. 升压 The laser driving circuit 408 can use a driving voltage V 驱动 To drive the green laser diode 406, the current sensor 404 can use the sensing voltage V 感测 to measure the current flowing to the green laser diode 406, and the green laser diode 406 can use the laser voltage V 激光器 to output green laser light, for example, as an aiming pattern of the example scanning device 100. Therefore, the boost voltage may be defined as provided in equation (1).

[0081] Therefore, the boost voltage V 升压 must be large enough to enable the laser driver circuit 408 to drive the green laser diode 406 without significantly exceeding the drive voltage V 驱动400 ). In addition, the green laser diode 406 may have a range of forward voltages that can be used to efficiently drive the diode 406 based on the operating characteristics of the diode 406 (e.g., temperature). For example, when the green laser diode 406 is completely cold (e.g., has not yet begun to operate), the diode 406 may require more than 9V to generate green laser light. In contrast, when the green laser diode 406 is fully warmed up (e.g., has been operating for a significant duration), the diode 406 may require less than 5V to generate green laser light. Therefore, the boost regulator 402 and the boost servo 412 can actively adjust the boost voltage V during operation of the example driver circuit configuration 400. 升压 , in order to efficiently drive all components of configuration 400.

[0082] Specifically, the boost regulator 402 may have a programmable output to implement a boost voltage V based on the voltage requirements of the laser driver circuit 408, the green laser diode 406, and the current sensor 404. 升压 It should be noted that relative to the drive voltage V 驱动 and the laser voltage V 激光器 , sensing voltage V 感测 Usually very small, so the sensing voltage V 感测 may not significantly affect the boost voltage V at any particular time 升压 Regardless, the boost regulator 402 may initially provide a maximum boost voltage V sufficient to drive all components of the example driver circuit configuration 400. 最大 , and the boost servo 412 can acquire / measure the laser voltage V 激光器 and the maximum boost voltage V 最大 For comparison. The boost servo 412 can typically measure the laser voltage V at the cathode of the green laser diode 406. 激光器 However, in some aspects, the boost servo 412 can measure the laser voltage V at the anode of the green laser diode 406. 激光器 .

[0083] Use the laser voltage V 激光器 and the maximum boost voltage V 最大 , the boost servo 412 can determine the maximum boost voltage V 最大 and the laser voltage V 激光器 Whether the voltage difference between them exceeds the driving voltage V 驱动 , and if not, the boost servo 412 can cause the boost regulator 402 to continue to provide the maximum boost voltage V 最大 If the boost servo 412 determines the maximum boost voltage V 最大 and the laser voltage V 激光器The voltage difference between them does exceed the driving voltage V 驱动 , the boost servo 412 can enable the boost regulator 402 to provide the optimal voltage V based on the excess voltage 最佳 For example, if the boost servo 412 determines the maximum boost voltage V 最大 and the laser voltage V 激光器 The voltage difference between them exceeds the driving voltage V 驱动 1.5V, the boost servo 412 can determine the optimal voltage V 最佳 Ratio to maximum boost voltage V 最大 1.5V less, and the boost regulator can accordingly output the optimal boost voltage V 最佳 =V 最大 In this way, the boost servo 412 enables the boost regulator 402 to output a dynamic and higher voltage than the static boost voltage (eg, the maximum boost voltage V 最大 ) and thus waste a lot of power in conventional systems. A more electrically efficient boost voltage V 升压 , to drive the laser driving circuit 408 and the green laser diode 406.

[0084] Additionally, in some aspects, the green laser diode 406 can be pulsed such that the diode 406 has a duty cycle of less than 100%. In these aspects, although the boost voltage V 升压 The green laser diode 406 is not driven, but other components of the example driver circuit configuration 400 and / or other electrically coupled circuits (not shown) (e.g., additional lighting components, a buck drive, etc.) may require power. The boost servo 412 may determine that it is sufficient to power these additional components during the time period when the green laser diode 406 is inactive (e.g., between laser pulses). Thus, the boost servo 412 may cause the boost regulator 402 to output the optimal boost voltage V when the green laser diode 406 is pulsing. 最佳 , and can make the regulator 402 output a low voltage VLOW when the diode 406 is inactive. For example, if the optimal boost voltage V 最佳 If the low voltage VLOW is 7V and the low voltage VLOW is 4V, the boost servo 412 can cause the boost regulator 402 to output 7V when the green laser diode 406 should emit light pulses, and the servo 412 can cause the regulator 402 to output 4V when the diode 406 should not emit light pulses (e.g., inactive, between pulses). In this way, the boost servo 412 and the boost regulator 402 can further increase the boost voltage V provided by the regulator 402 during the diode inactive period. 升压 The quiescent boost voltage (eg, the maximum boost voltage V 最大 ) to further improve the conventional system.

[0085] In some instances, the green laser diode 406 may remain inactive long enough to cool between subsequent drive events (eg, emitting laser pulses). In these instances, the optimal boost voltage V 最佳 may not be sufficient to drive diode 406, and boost servo 412 may need to determine an increased optimal drive voltage based on the current operating state of diode 406. Alternatively, green laser diode 406 may remain active long enough to heat up significantly and thereby reduce the voltage requirement to drive diode 406. In this case, the optimal boost voltage V 最佳 The voltage required to drive the diode 406 may be exceeded, and the boost servo 412 may need to determine a reduced optimal drive voltage based on the current operating state of the diode 406. In either case, the boost servo 412 can actively update the optimal boost voltage V required to drive all components of the example driver circuit configuration 400 and / or any electrically coupled components (e.g., additional lighting components, buck drive, etc.) at a refresh rate (e.g., once every x laser cycles, once every x milliseconds, etc.). 最佳 .

[0086] Further, in some aspects, the boost servo 412 may also restore to the maximum boost voltage V after a rest period between laser pulses. 最大 For example, a user may pull the trigger 120 of the example scanning device 100, during which the boost servo 412 determines the optimal boost voltage V 最佳 After the user releases the trigger 120, the user may subsequently pull the trigger after a duration exceeding the rest period, so that the boost servo 412 determines the optimal boost voltage V corresponding to the operating state of the green laser diode 406 during the current trigger pull period. 最佳 Before, the boost regulator 402 is automatically made to output the maximum boost voltage V 最大 .

[0087] The example drive circuit configuration 400 also includes a current regulation loop 410 configured to maintain a constant current flowing from the boost regulator 402 to the ground 416. The current sensing circuit 404 generates a current that is proportional to the laser voltage V 激光器 The current regulation loop 410 receives and uses a corresponding voltage feedback signal to maintain a constant current. The current regulation loop 410 may regulate the voltage feedback signal, for example using an error amplifier (not shown) and a calibrated reference voltage, to maintain a constant current flowing from the boost regulator 402 to the ground 416. In addition, the current regulation loop 410 output may be received by the boost servo 412 and may be used by the boost servo 412 to determine adjustments to the voltage provided by the boost regulator 402, as described herein.

[0088] In general, when the green laser diode 406 is driven at a constant current, the optical power of the diode 406 may decrease over time as the temperature of the diode 406 increases during operation. In other words, as the voltage requirement to drive the green laser diode 406 decreases with increasing temperature, the optical power output of the diode 406 similarly decreases when the current flowing through the diode 406 remains constant. As a result, the optical power of the green laser diode 406 may be highest during initial operation when the diode 406 is cold.

[0089] Thus, in a configuration similar to the example driver circuit configuration 400 where constant optical power may not be a primary concern, the constant current loop 410 may attempt to maintain a maximum cold regulation current so that the optical power will only decrease as temperature increases during operation. Alternatively, the optional laser temperature sensor 318 may be used with a temperature reference table (not shown) to correct for optical power loss by increasing the current through the green laser diode 406.

[0090] As previously described, the example driver circuit configuration 400 also includes a ground 416 and an optional laser temperature sensor 418. The ground 416 can be an electrical ground for the example driver circuit configuration 400, such that a voltage (e.g., V 升压 、V 驱动 、V 感测 and V 激光器 ). The path of current flowing to the green laser diode 406 can thus be described as flowing from the boost regulator 402 to the current sensor 404, through the green laser diode 406, through the laser driver circuit 408, optionally through the laser current sensor 414, and finally to the ground 416. An optional laser temperature sensor 418 can be included as part of the green laser diode 406 and / or otherwise connected to the diode 406 to measure the operating temperature of the diode 406 before, during, and after an active (e.g., providing aiming illumination) period of time. In some aspects, the optional temperature sensor 418 can be communicatively coupled to the boost servo 412 such that the boost servo 412 can receive the laser operating temperature from the sensor 418 to determine an appropriate response to the boost voltage V provided by the boost regulator 402. 升压 changes.

[0091] The example driver circuit configuration 400 also includes other circuits 420, which may generally include other electronic components (multiple) electrically coupled to the boost regulator 402. For example, the other circuits 420 may include an illumination LED, a driver circuit, and / or any other suitable electronic components or combinations thereof. Figure 4As shown, the other circuit 420 may also be electrically coupled to the ground 416 such that both the green laser diode 406 and the other circuit 420 receive the input drive voltage from the boost regulator 402 and discharge to the ground 416 .

[0092] Figure 5 An example method 500 for driving a green laser diode according to various embodiments of the present invention is shown. It should be understood that in some embodiments, any of the blocks of method 500 may be performed by any of the example scanning device 100, aiming pattern assembly 222, aiming illumination controller 222B, processor(s) 202, and / or any other suitable device.

[0093] The method 500 includes outputting a maximum boost voltage by a boost regulator to drive a green laser diode (block 502). Generally speaking, and as previously described, the maximum boost voltage may be sufficient to drive the green laser diode and some other additional electrical components (e.g., laser driver circuits 304, 408, laser current sensor 306, current sensing circuit 404). The method 500 may also include measuring, by a boost servo, a laser voltage of the green laser diode and the maximum boost voltage (block 504). The boost servo may typically measure the laser voltage at the anode of the green laser diode, but in some aspects, the boost servo may measure the laser voltage at the cathode of the green laser diode.

[0094] The method 500 also includes calculating, by the boost servo, a voltage difference between the laser voltage and the maximum boost voltage (block 506). In some aspects, the boost servo can additionally measure a laser current sense voltage corresponding to a current level flowing through the green laser diode. In these aspects, the boost servo can calculate the voltage difference by subtracting both the laser voltage and the laser current sense voltage from the maximum boost voltage.

[0095] The method 500 also includes comparing, by the boost servo, the voltage difference with a drive voltage corresponding to the laser drive circuit to determine whether the voltage difference exceeds the drive voltage (block 508). As a first example, the boost servo may determine that the voltage difference between the laser voltage (and optionally the laser current sensing voltage) and the maximum boost voltage is 3V, and the drive voltage may be 2V. In this first example, the boost servo may compare the voltage difference with the drive voltage to determine that the voltage difference exceeds the drive voltage 1V. As a first example, the boost servo may determine that the voltage difference between the laser voltage (and optionally the laser current sensing voltage) and the maximum boost voltage is 2V, and the drive voltage may be 2V. In this second example, the boost servo may compare the voltage difference with the drive voltage to determine that the voltage difference is equal to the drive voltage. In either case, the boost servo may determine a change (e.g., a decrease) to the maximum boost voltage (e.g., 1V and 0V, respectively), by which the boost servo may achieve more electrically efficient operation of the drive circuit.

[0096] In some aspects, the servo motor can determine whether the drive voltage corresponding to the laser drive circuit meets the drive voltage threshold before, during, or after comparing the voltage difference to the drive voltage. For example, the boost servo can monitor an optical power control loop (e.g., optical power loop 312) that is configured to adjust the drive voltage at a monitoring frequency to determine whether the drive voltage meets the drive voltage threshold. The monitoring frequency can be any suitable frequency (e.g., once every x laser cycles, once every x milliseconds, etc.) and can enable the boost servo to determine whether the drive voltage needs to be adjusted, thereby affecting the overall voltage requirement from the boost regulator. The drive voltage threshold can be any suitable voltage value, a percentage deviation from a desired value, and / or any other suitable numerical value corresponding to the drive voltage, or a combination thereof. In this way, the boost servo can verify that the drive voltage used to compare the voltage difference will provide a precise voltage excess that the boost voltage can use to adjust the boost voltage provided by the boost regulator.

[0097] Therefore, in response to determining that the voltage difference exceeds the driving voltage by the excess voltage, the method 500 further includes causing the boost regulator to output an optimal voltage based on the excess voltage by the boost servo (block 510). Returning to the above example, the boost servo may determine that the maximum boost voltage should be reduced by 1V in the first example so that the optimal voltage is 1V less than the maximum boost voltage. In the above second example, the boost servo may determine that the voltage difference does not exceed the driving voltage (they are equal) so that the optimal voltage is the maximum boost voltage.

[0098] In some aspects, the laser voltage is a first laser voltage, the optimal voltage is a first optimal voltage, the voltage difference is a first voltage difference, and the excess voltage is a first excess voltage. In these aspects, the boost servo can then measure a second laser voltage of the green laser diode and the first optimal boost voltage. Thereafter, the boost servo can calculate a second voltage difference between the second laser voltage and the first optimal boost voltage, and can compare the second voltage difference to the drive voltage to determine whether the second voltage difference exceeds the drive voltage. In response to determining that the second voltage difference exceeds the drive voltage by a second excess voltage, the boost servo can cause the boost regulator to output a second optimal voltage based on the second excess voltage.

[0099] As an example, the driving voltage may be 1.5V, the first laser voltage may be 6V, and the first optimal voltage may be 8V. The boost servo may measure the second laser voltage of the green laser diode after the first operating time period, and as a result of the increased temperature during operation, the second laser voltage may be 5.5V. The boost servo may calculate the second voltage difference by subtracting the second laser voltage (5.5V) from the first optimal voltage (8V) to determine a second voltage difference of 2.5V. The boost servo may compare the second voltage difference (2.5V) to the driving voltage (1.5V) to determine that the second voltage difference exceeds the driving voltage 1V. As a result, the boost servo may output a second optimal voltage of 7V by subtracting 1V from the first optimal voltage (8V).

[0100] In some aspects, the boost servo can use a temperature sensor to obtain the laser temperature. In these aspects, the boost servo can also obtain the lookup optimal voltage from a temperature reference table based on the laser temperature. The boost servo can also compare the optimal voltage with the lookup optimal voltage to determine the change to the optimal voltage. For example, the optimal voltage output by the boost regulator can be 9V, and the laser voltage can be 7V. In this example, the temperature sensor can measure the temperature of the laser and / or the operating environment, which can be sent to the boost servo, and the boost servo can obtain a lookup optimal voltage of 6V from the temperature reference table based on the temperature obtained from the temperature sensor to drive the green laser diode. Therefore, the boost servo can compare the optimal voltage (9V) and / or the laser voltage (7V) with the lookup optimal voltage (6V) to determine that the optimal voltage can be reduced by 1V without sacrificing laser drive.

[0101] Additionally or alternatively, in some aspects, the boost servo can be calibrated to identify the room temperature laser forward voltage and can be configured to estimate the optimal boost voltage as a function of temperature. As a specific time, the boost servo can obtain the laser temperature from the temperature sensor and can then calculate the estimated optimal boost voltage based on the room temperature laser forward voltage. The boost servo can then cause the boost regulator to output the estimated optimal boost voltage.

[0102] In some aspects, the boost servo can adjust the input current of the boost regulator so that the boost regulator outputs optimal power based on the excess voltage. The boost servo can adjust the input current in response to determining that the voltage difference exceeds the drive voltage by the excess voltage. In this way, the input power of the boost regulator can be optimized by adjusting the input current instead of the input voltage by the boost servo and / or adjusting the input current and the input voltage to match the power required by the load of the laser driving component. This will improve efficiency and reduce the peak current required by the component by indirectly reducing the boost voltage as a result of reducing the input current of the boost regulator.

[0103] The method 500 also includes calculating, by the boost servo, a low voltage configured to drive at least one additional component electrically coupled to the boost regulator when the green laser diode is inactive. In some aspects, the at least one additional component is an illumination light emitting diode (LED). However, and as previously described, the at least one additional component can be any suitable component electrically coupled to the boost regulator. For example, the low voltage output by the boost regulator can be used to drive an additional buck driver on other circuits unrelated to driving the green laser diode when the diode is not actively emitting laser pulses.

[0104] In response to the green laser diode being inactive, the method 500 also includes causing the boost servo to cause the boost regulator to output a low voltage to power the at least one additional component (block 514). In some aspects, the boost servo may determine that the green laser diode has been inactive for more than a rest interval and may cause the boost regulator to output a maximum boost voltage to drive the green laser diode. Alternatively, the boost servo may determine that the green laser diode has been inactive for less than a rest interval and may cause the boost regulator to output an optimal voltage to drive the green laser diode because the diode has not had enough time to sufficiently cool to require the maximum boost voltage to drive. The rest interval may be any suitable time period.

[0105] Additionally, in some aspects, the boost servo may determine that the laser diode has been active for greater than an activity duration threshold. In response to determining that the laser diode has been active for greater than an activity duration threshold, the boost servo may measure a laser voltage at an anode of the laser diode, and may calculate a voltage difference between the laser voltage at the anode of the laser diode and an optimal voltage. Thus, the voltage difference measured by the boost servo may be measured between a gate voltage provided by an optical power control loop and the laser voltage and / or between the laser diode anode and the optimal voltage. Of course, it should be understood that either measurement may be appropriate, and various factors (e.g., the self-heating effect of the laser diode) may make either measurement more reliable at any particular time.

[0106] As mentioned above, scanning devices (such as bar code imagers) that use green laser sources in the aiming assembly are also limited due to high operating voltages (which result in high heat) and due to shortened laser life. Although green laser sources can produce higher contrast than red laser sources, in bar code imaging applications, green laser sources are more susceptible to saturation in ambient light. As a result, green laser sources are typically operated at higher optical power output levels, but this exacerbates heat dissipation and laser degradation issues.

[0107] In response, in various examples, a scanning device (e.g., a bar code imager) herein may include technology for controlling a laser drive of an aiming component, particularly an aiming component (such as an aiming pattern component 222) using a green laser source. In some examples, the bar code imager includes an imaging component 212 such as the scanning device 100, the imaging component 212 being configured to capture images on the field of view of the bar code imager, wherein each image is captured during a frame duration of the bar code imager. In some examples, a controller (such as an aiming illumination controller 222B) controls the aiming component by controlling a drive mode of the aiming component. Specifically, the controller 222B may be configured to determine an optimal duty cycle value for an aiming pattern generated by the aiming component 222. For example, when the duty cycle is greater than the optimal value, heat dissipation increases at the same aiming pattern visual brightness; the aiming pattern visual brightness is limited by a frame average radiant power constraint. When the duty cycle is less than the optimal value, the aiming pattern visual brightness decreases; the latter is limited by a peak pulse light power constraint. As discussed further, the optimal duty cycle can be a single value, multiple different values, or a value that falls within a range of values ​​forming a solution space.

[0108] In various examples herein, control of the aiming pattern is described as being performed by controller 222B. This control is similar to that described above in Figure 3-5 In some examples, the controller 222B is implemented to include one or both of the following: a) a circuit for maintaining a constant laser operating current, wherein thermal correction is performed using a stored lookup table, which may be useful for aiming assemblies without a built-in monitoring detector; and b) a circuit for maintaining a constant laser monitoring current, which may be useful for aiming assemblies with a built-in monitoring detector.

[0109] In some examples, controller 222B may be configured to control aiming assembly 222 so that the green laser aiming pattern is generated as a single pulse per frame duration. In some examples, controller 222B controls the aiming assembly to generate pulses of multiple green laser aiming patterns per frame duration. Frame duration represents the time taken by the bar code imager to complete the entire image capture interval. For example, frame duration Tf can be the inverse of the frame per second (FPS) rate F at which the bar code imager is operated. For example, a 60FPS bar code imager has a frame duration of 16.67ms.

[0110] In addition, in some examples, controller 222B determines a duty cycle for the green aiming pattern pulses of each frame duration. For example, in some examples, the duty cycle is determined to simultaneously satisfy a peak pulse optical power constraint that is independent of the frame duration and a heat dissipation constraint that is dependent on the frame duration. In some examples, the duty cycle is determined to simultaneously satisfy a minimum single pulse optical power condition for the aiming pulse and an average power condition for a series of aiming pulses. In some examples, the duty cycle is determined to be within a predetermined tolerance range of an optimized state representing the intersection of a single pulse optical power rule for the aiming pulse and an average power rule for a series of aiming pulses.

[0111] Figure 6 An example method 600 for driving an aiming component of a bar code imager, such as the scanning device 100, to satisfy simultaneous operation constraints is shown. Optionally, the method 600 may include an initial process (block 602) in which a controller, such as the controller 222B, obtains an operating mode of the bar code imager, and obtains static characteristics of an aiming component, such as the aiming pattern component 222, at a subsequent process (block 604). For example, at block 602, the controller may determine that the bar code imager is in a trigger level mode, in which the bar code imager captures images in response to a manually actuatable trigger 120, such as when the bar code imager is in a handheld mode. Alternatively, the controller may determine that the bar code imager is in a demonstration mode, in which the bar code imager captures images for a continuous period of time including a plurality of continuous frame durations, such as when the bar code imager is mounted in a fixed position in the demonstration mode. In either example, the determination of the operating mode can be in response to a user-initiated event, such as pulling a trigger 120 on the bar code imager, or such as a sensed state from a sensor in a handle (e.g., an elongated handle or lower grip portion 116) or base of the bar code imager, which senses when the bar code imager is mounted on a fixed base (not shown) for demonstration mode or when it is released from a fixed base for triggering a horizontal mode.

[0112] In some examples, the operating mode is determined and the simultaneous constraints are used to determine a duty cycle that may vary with the operating mode. For example, the frame duration of a bar code imager in a triggered level mode may be different than the frame duration when in a presentation mode.

[0113] At optional block 604, controller 222B may determine static characteristics of the laser aiming assembly, such as characteristics that define the operation of the laser source. As an example, the static characteristic is a laser safety class (e.g., Class 2, Class 3R, Class 3B, or Class 4), as determined by the Center for Devices and Radiological Health (CDRH) as part of the Food and Drug Administration and the Z136.1 Laser Safety Standard of the American National Standards Institute. Although any number of static laser characteristics may be used, in some examples, the class ratings are used because they provide a human-accessible laser power for visible light conditions that the aiming assembly is to meet over the entire field of view and at near-field and far-field distances from the bar code imager. As described above, in various examples, aiming pattern assembly 222 includes an illumination component 222A, and illumination component 222A includes a green laser source (e.g., a green laser diode). In some examples, the green laser source may be a Class 2 laser rated to have an output power of less than 1 mW. In some examples, controller 222B acquires static characteristics stored in memory 204 or stored in aiming illumination component 222A.

[0114] To determine the duty cycle of the pulses generated by the aiming assembly, the controller 222B (block 606) obtains imaging parameters of the bar code imager, which may include the number of frames per second or frame duration at which the bar code imager operates. For example, such data may be stored in the memory 204. In some examples, these imaging parameters vary with the operating mode (determined by block 602). For example, the frame duration may be different when the bar code imager is in a triggered level mode compared to a demonstration mode.

[0115] At block 608, the controller 222B identifies constraints to be satisfied during operation of the bar code imager. In the example shown, two types of constraints are identified: constraints related to frame duration, and another constraint that is a constraint independent of frame duration. More specifically, in the example, the first constraint is a peak pulse optical power constraint related to frame duration that establishes a peak pulse optical power for one or more green aiming pulses per frame duration. This constraint limits the optical power that can be delivered during the frame duration. The second constraint is a constraint independent of frame duration that provides a heat dissipation constraint for the bar code imager such that the maximum amount of heat dissipation required is no greater than a predetermined protocol.

[0116] In the case where the constraints related to frame duration and independent of frame duration are identified, at block 610, the controller 222B applies a solution rule to determine a duty cycle that simultaneously solves the peak pulse optical power constraint related to frame duration and the heat dissipation constraint independent of frame duration. At block 612, the aiming assembly is controlled to operate according to the duty cycle.

[0117] In various implementations, method 600 may begin at block 606, for example, where the simultaneous constraints are not dependent on the mode of operation or where the simultaneous constraints are automatically accessed by the controller and are not determined based on the mode of operation. Further, for example, where the simultaneous constraints stored within the bar code imager already incorporate any relevant static characteristics, static characteristics of the laser aiming assembly may not be obtained. Other variations to these descriptions include using more than two simultaneous constraints.

[0118] In an example implementation of block 610, controller 222B optionally determines an operating mode of the bar code imager, and based on the operating mode, determines a duty cycle for a single aiming pulse per frame duration such that the duty cycle within each frame duration satisfies both a peak pulse optical power constraint that is independent of the frame duration and a heat dissipation constraint that is dependent on the frame duration. In some examples, the process of block 610 does not determine or use the operating mode of the bar code imager. In one example, the peak pulse optical power constraint is an achievable emission limit for the aiming pulse, where the constraint is applied to the pulse but does not depend on the frame duration. For example, for a Class 2 green laser source, the achievable emission limit AEL_Pulse (expressed in Watts (W)) for the aiming pulse is expressed as:

[0119] AEL_Pulse = 7 × 10 -4 (tp) -.25 (2)

[0120] where tp is the pulse duration. Figure 7 A frame duration 700 is shown having a time length D during which the bar code imager will capture an image of the field of view, and Figure 7 A pulse 702 is shown having a pulse duration tp as long as the aiming pulse contained within the frame duration.

[0121] Although the peak pulse optical power constraint does not depend on the frame duration Tf, in the example, the heat dissipation constraint depends on the frame duration and is the achievable emission limit of the average power of the aiming pulse during the time window formed by multiple consecutive frame durations. This constraint is expressed as P_ave (expressed in Watts (W)):

[0122] P_ave=7×10 -4 (T1) -.25 (3)

[0123] Where T1 is the time window duration and varies with the rated power of the green laser source according to the laser safety class. Therefore, the heat dissipation constraint can depend on the frame duration and, in some examples, the static characteristics of the aiming assembly (such as the laser safety class). For an aiming assembly using a Class 1 laser source, the time window T1 is taken to be 10 s and P_ave is 0.394 mW. For a Class 2 laser source, T1 is 0.25 s and P_ave is 0.99 mW.

[0124] To determine the duty cycle, in an example, the controller 222B determines a duty cycle that satisfies the constraints in both Equation 2 and Equation 3. Such a solution may be predetermined and stored in the aiming assembly or memory 204, for example, as a discrete DC value for each operating mode or as a lookup table of DC values ​​determined for different aiming assembly laser safety levels, different operating frame rates, or other static characteristics and imaging parameters. In some examples, the solution may be stored as a solution space of solution values. In some examples, at box 610, the controller 222B may apply an iterative algorithm, a simultaneous linear equation analytical expression, or other technique to find a solution or solution space for multiple constraint expressions. In an example, at box 610, the controller 222B may transform the frame-independent equation (2) into a function of the frame duration and the duty cycle DC. Equation (2) becomes:

[0125] P_ave(Tf, DC)=7×10 -4 (Tf×DC) -.25 ×DC (4)

[0126] Where Tf is the frame duration and P_ave(Tf, DC) is the frame average laser optical power from a single pulse. At block 610, DC can be determined by finding the simultaneous solution of the frame average laser optical power of Equation 4 and the achievable emission limit for the average power of the aiming pulse during the time window formed by multiple consecutive frame durations from Equation 3, resulting in:

[0127] 7×10 -4 (Tf×DC) -.25 ×DC=7×10 -4 (T1) -.25 (5)

[0128]

[0129]

[0130] In the example, for a Class 1 laser operating at a frame rate F of 60 fps (i.e., T1 = 10 s), DC = 0.119 is obtained, and for a Class 2 laser operating at 60 fps (i.e., T1 = 0.25 s), DC = 0.405 is obtained, where F = 1 / Tf. That is, in some examples, Equations 5, 6, and 7 each represent an equivalent expression for a simultaneous constraint solution for the DC of a single aiming pulse within a frame duration. Of course, the time window T1 and the frame duration Tf may vary, as may the laser safety class or other power rating of the aiming source. Still further, in various embodiments, the simultaneous solution of the constraints may be satisfied by any DC value that falls within the solution space of values.

[0131] Figure 8An example solution space 800 of suitable duty cycles that may be determined at block 610 is shown. Heat dissipation constraints are plotted at 802 and 804 for class 1 and class 2 laser sources, respectively. The peak pulse optical power constraint is plotted at 806. The first intersection 808 represents a duty cycle DC that satisfies the simultaneous conditions for a class 1 laser, yielding DC=0.11. The second intersection 810 represents a DC value that satisfies the conditions for a class 2 laser (such as a green laser source in various examples herein), yielding DC=0.41. Based on the solution protocol of block 610, the controller 222B may identify the DC value as a particular intersection of the constraints. In other examples, the DC value may be selected within a sufficient range of values, for example, when other data such as the operating mode of the bar code imager, the static characteristics of the aiming assembly, and the operating temperature are considered. A DC that is in the space above the peak pulse optical power constraint 806 may result in the laser output being too bright for user operation and not meeting the desired eye safety standards. The DC in the space below constraint 806 will meet the eye safety standard, but for various applications, the DC can result in a sufficiently bright aiming pattern in the field of view. For example, to prevent ambient light from washing out the green laser aiming pattern, the controller 222B can apply a solution protocol that seeks to produce the highest possible optical power aiming pattern while satisfying the simultaneous conditions. The peak optical power constraint is determined for the peak power region of the aiming pattern, which will typically be the central spot of the aiming pattern. In various embodiments, the solution protocol applied at box 610 can mean selecting a DC within a range of values ​​in the solution space. For example, the solution space 800 can be satisfied by a DC value within +5%, +10%, +15%, or +20% above one or more of the simultaneous constraints. For example, the solution space 800 can include a DC value within +5%, +10%, +15%, or +20% above any one or more of constraints 802, 804, and 806. Solution space 800 may be satisfied by DC values ​​within -5%, -10%, -20%, -30%, -40%, -50%, -60%, -70%, -80%, -90% under one or more of the simultaneous constraints. For example, solution space 800 may include DC values ​​within -5%, -10%, -20%, -30%, -40%, -50%, -60%, -70%, -80%, -90% under any one or more of constraints 802, 804, and 806. Figure 8 A range of suitable DC values ​​is shown extending from an upper boundary 812 to a lower boundary 814, which together define the boundaries of solution space 800 in the illustrated example. In the example, suitable DC values ​​extend from +20% above constraint 806 to -90% below constraint 806.

[0132] In the example of a green laser source with a Class 2 laser safety rating, where the bar code imager is configured to capture images at 60 frames per second in a triggered level operating mode, resulting in a frame duration of 16.67 ms, the pulse duration tp of a single aiming pulse is determined to be between 2 ms (DC=0.12) and 8 ms (DC=0.48). For the demonstration operating mode, tp is between 0.5 ms (DC=0.03) and 2 ms (DC=0.12).

[0133] Using the duty cycle determined at block 610, controller 22B (block 612) controls the aiming assembly to generate an aiming pulse according to the duty cycle, and may optionally synchronize the position of the aiming pulse with a sensor exposure window within the frame duration. The sensor exposure window corresponds to a window in which image sensor 106 is exposed to capture an image of the field of view of the bar code imager. In some examples, the sensor exposure window is determined by a controller shutter of image sensor 106.

[0134] Figure 9-11 904. Various resulting synchronizations between the aiming pulse and the sensor window within the frame duration are shown. The controller may set the duty cycle of the aiming pulse to have a non-overlapping duty cycle such that sensor exposure window 900 and aiming pulse 902 do not overlap during frame duration 904 ( Fig. 9 In another example, the duty cycle of the aiming pulse is an overlapping duty cycle such that sensor exposure window 900 and aiming pulse 902 at least partially overlap during frame duration 904 ( Fig.10 In another example, the duty cycle of the aiming pulse is an overlapping duty cycle, where the aiming pulse 902 occurs within the sensor exposure window 900 of the imager during the frame duration 904 ( Fig.11 ). For example, in some implementations, the pulse width of the aiming pulse is determined to not only satisfy the simultaneous constraints, but also be equal to or less than the width of the sensor exposure window in width to ensure full overlap. In some examples, the duty cycle of the aiming pulse and / or the synchronization of the aiming pulse is further determined based on the ambient light intensity level (e.g., as measured during the sensor exposure window) to adjust the optical power of the aiming pulse to ensure sufficient brightness relative to the ambient light intensity level.

[0135] The present technology includes other variations. In some examples, the duty cycle of the aiming pulse is determined to satisfy more than two simultaneous constraints. The constraints may include a lifetime degradation condition, an aiming laser source current condition, an aiming laser source voltage condition, a continuous wave optical power condition, a pulse optical power condition, an optimal eye safety value, an average optical power within an aiming pulse sequence, an ambient light intensity level, and an expected total cumulative aiming laser source life. Example additional constraints include a minimum single pulse optical power condition of the aiming pulse that can be satisfied simultaneously and an average power condition within the aiming pulse sequence. Other additional constraints include a predetermined tolerance range of acceptable values ​​imposed on the solution space, which corresponds to satisfying two or more constraints simultaneously, and then using further constraints or separate conditions to determine the duty cycle and / or synchronization of the aiming pulse. In some examples, the constraints are related to the operating mode. For example, certain constraints to be satisfied simultaneously are used during the trigger level mode, and other constraints are used during the demonstration mode.

[0136] The above description relates to the block diagram of the accompanying drawings. The alternative implementation of the example represented by the block diagram includes one or more additional or alternative elements, processes and / or devices. Additionally or alternatively, one or more of the example boxes in the figure can be arranged, divided, rearranged or omitted. The components represented by the boxes in the figure are implemented by any arrangement of hardware, software, firmware and / or hardware, software and / or firmware. In some examples, at least one of the components represented by the box is implemented by a logic circuit. As used herein, the term "logic circuit" is explicitly defined as a physical device including at least one hardware component, which is configured (for example, via an operation according to a predetermined configuration and / or via the execution of a stored machine-readable instruction) to control one or more machines and / or perform the operation of one or more machines. Examples of logic circuits include one or more processors, one or more coprocessors, one or more microprocessors, one or more controllers, one or more digital signal processors (DSPs), one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more microcontroller units (MCUs), one or more hardware accelerators, one or more dedicated computer chips, and one or more system-on-chip (SoC) devices. Some example logic circuits, such as ASICs or FPGAs, are specially configured hardware for performing operations (e.g., one or more of the operations represented by the flowcharts described herein). Some example logic circuits are hardware that executes machine-readable instructions to perform operations (e.g., one or more operations represented by the flowcharts of the present disclosure, if any). Some example logic circuits include a combination of specially configured hardware and hardware that executes machine-readable instructions. The above description relates to various operations described herein and flowcharts that may be attached to this document to illustrate the flow of those operations. Any such flowchart represents an example method disclosed herein. In some examples, the method represented by the flowchart implements the device represented by the block diagram. Alternative implementations of the example methods disclosed herein may include additional or alternative operations. In addition, the operations of the alternative implementations of the methods disclosed herein may be combined, divided, rearranged, or omitted. In some examples, the operations described herein represented by the flowcharts are implemented by machine-readable instructions (e.g., software and / or firmware) stored on a medium (e.g., a tangible machine-readable medium) for execution by one or more logic circuits (e.g., (multiple) processors). In some examples, the operations described herein are implemented by one or more configurations of one or more specially designed logic circuits (e.g., ASIC(s)). In some examples, the operations described herein are implemented by a combination of specially designed logic circuit(s) and machine-readable instructions stored on a medium (e.g., a tangible machine-readable medium) for execution by the logic circuit(s).

[0137] As used herein, each of the terms "tangible machine-readable medium," "non-transitory machine-readable medium," and "machine-readable storage device" are expressly defined as a storage medium (e.g., a disk such as a hard drive, a digital versatile disk, an optical disk, a flash memory, a read-only memory, a random access memory, etc.) on which machine-readable instructions (e.g., program code in the form of software and / or firmware) are stored for any suitable period of time (e.g., permanently, for an extended period of time (e.g., while a program associated with the machine-readable instructions is being executed), and / or for a short period of time (e.g., while the machine-readable instructions are cached and / or in the process of being buffered). Further, as used herein, each of the terms "tangible machine-readable medium," "non-transitory machine-readable medium," and "machine-readable storage device" are expressly defined to exclude propagating signals. That is, as used in any claim of this patent, any of the terms "tangible machine-readable medium," "non-transitory machine-readable medium," and "machine-readable storage device" are not to be construed as being implemented by a propagating signal.

[0138] In the above description, specific embodiments have been described. However, it is understood by those skilled in the art that various modifications and changes may be made without departing from the scope of the invention as set forth in the following claims. Therefore, the description and the accompanying drawings are to be considered in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present teachings. Additionally, the described embodiments / examples / implementations should not be interpreted as mutually exclusive, but rather should be understood as potentially combinable, if such combinations are permitted in any way. In other words, any feature disclosed in any of the aforementioned embodiments / examples / implementations may be included in any of the other aforementioned embodiments / examples / implementations.

[0139] These benefits, advantages, solutions to problems, and any (multiple) elements that may make any benefit, advantage, or solution occur or become more prominent are not to be construed as critical, required, or essential features or elements of any or all claims. The claimed invention is defined solely by the appended claims, including any amendments made during the pendency of this application and all equivalents of those claims as issued.

[0140] In addition, in this document, relational terms such as first and second, top and bottom, etc. can be used alone to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "include", "comprises", "has", "has", "includes", "contains", "covers", "covers" or any other variation thereof are intended to cover non-exclusive inclusions, so that a process, method, article or device that includes, has, contains, covers a list of elements includes not only those elements but also other elements that are not explicitly listed or inherent to such processes, methods, articles or devices. Elements that begin with "include one", "have one", "include one", "cover one", in the absence of more constraints, do not exclude the presence of other identical elements in the process, method, article or device that includes, has, contains, covers the element. The terms "one" and "an" are defined as one or more, unless otherwise expressly stated herein. The terms "substantially," "approximately," "approximately," "about" or any other version of these terms are defined as close as understood by one of ordinary skill in the art, and in one non-limiting embodiment, within 10%, within 5%, within 1% in another embodiment, and within 0.5% in another embodiment. The term "coupled," as used herein, is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is "configured" in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

[0141] The abstract of the present disclosure is provided to allow the reader to quickly determine the nature of the present technical disclosure. This abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the above-mentioned detailed description, it can be seen that various features are grouped together in various embodiments for the purpose of integrating the present disclosure. This method of disclosure should not be interpreted as reflecting the intention that the claimed embodiments require more features than those explicitly stated in the claims. On the contrary, as reflected in the following claims, the subject matter of the invention may lie in less than all the features of a single disclosed embodiment. Therefore, the following claims are thus incorporated into the detailed description, wherein each claim represents itself as a subject matter claimed separately.

Claims

1. A barcode imager, comprising: an imager configured to capture images over a field of view of the bar code imager, each image being captured during a frame duration of the bar code imager; an aiming assembly comprising a green laser source and configured to generate a green laser aiming pattern within the field of view of the bar code imager and including emissions having a wavelength within the range of 495 nm-570 nm; as well as a controller configured to control the green laser source to generate the green laser aiming pattern with a single aiming pulse per frame duration and with a duty cycle within each frame duration that satisfies both a peak pulse optical power constraint that is independent of frame duration and a heat dissipation constraint that is dependent on frame duration, Wherein the duty cycle of the aiming pulse is a non-overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse do not overlap during the frame duration.

2. The barcode imager according to claim 1, wherein: The controller is further configured to determine an operating mode of the bar code imager and, in response, control a drive mode of the green laser source, wherein the operating mode of the bar code imager is any one of: (i) a trigger level mode, in which the imager captures the image in response to an operable trigger, or (ii) a presentation mode, in which the imager captures images over a continuous time period comprising a plurality of continuous frame durations, wherein the heat dissipation constraints of the trigger level mode are different from the heat dissipation constraints of the presentation mode.

3. The bar code imager according to claim 2, wherein: The green laser source has a Class 2 laser safety rating, and wherein the imager is configured to capture the image at 60 frames per second, and wherein the duration of the single aiming pulse that triggers the horizontal mode is between 2 ms and 8 ms, and the duration of the single aiming pulse that triggers the demonstration mode is between 0.5 ms and 2 ms.

4. The bar code imager according to claim 1, wherein: The peak pulse optical power constraint is the achievable emission limit of the aiming pulse.

5. The bar code imager according to claim 4, wherein: The achievable emission limit AEL_Pulse in Watts (W) of the aiming pulse is expressed as: AEL_Pulse = 7×10 -4 *(tp) -.25 where tp is the pulse duration.

6. The bar code imager according to claim 1, wherein: The heat dissipation constraint is an achievable emission limit P_ave in Watts (W) for the average power of the aiming pulse within a time window formed by a number of consecutive frame durations and is expressed as: P_ave=7×10 -4 (T1) -.25 Where T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

7. The bar code imager according to claim 1, wherein: The duty cycle DC in each frame duration that satisfies both the peak pulse optical power constraint and the heat dissipation constraint is expressed as: Where Tf is the frame duration and T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

8. The bar code imager according to claim 1, wherein: The duty cycle DC within each frame duration that satisfies both the peak pulse optical power constraint and the heat dissipation constraint is expressed as being within +20% and -90% of the following values: Where Tf is the frame duration and T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

9. The bar code imager according to claim 1, wherein: The duty cycle of the aiming pulse is an overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse at least partially overlap during the frame duration.

10. The bar code imager according to claim 1, wherein: The duty cycle of the aiming pulses is an overlapping duty cycle such that the aiming pulses occur within a sensor exposure window of the imager during the frame duration.

11. The bar code imager according to claim 1, wherein: The peak pulse optical power constraint is the peak power at the central spot of the green laser aiming pattern.

12. A method for driving an aiming assembly of a bar code imager, the method comprising: acquiring, at a controller, an operating mode of the bar code imager having an imager configured to capture a plurality of images over a field of view of the bar code imager, each image being captured during a frame duration of the bar code imager; determining, at the controller, a duty cycle of a single aiming pulse per frame duration, responsive to the operating mode, the single aiming pulse comprising a green laser aiming pattern generated by a green laser source of the aiming assembly and comprising emissions having a wavelength within the range of 495 nm-570 nm, wherein determining the duty cycle of the green laser aiming pattern comprises identifying the duty cycle that satisfies both a peak pulse optical power constraint that is independent of frame duration and a heat dissipation constraint that is dependent on frame duration, Wherein the duty cycle of the aiming pulse is a non-overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse do not overlap during the frame duration.

13. The method according to claim 12, characterized in that Obtaining the operating mode includes determining whether the bar code imager is in (i) a trigger level mode, in which the imager captures the image in response to an operable trigger, or in (ii) a presentation mode, in which the imager captures images over a continuous time period comprising a plurality of continuous frame durations, wherein the heat dissipation constraints of the trigger level mode are different from the heat dissipation constraints of the presentation mode.

14. The method according to claim 13, characterized in that The green laser source has a Class 2 laser safety rating, and wherein the imager is configured to capture the plurality of images at 60 frames per second, and Wherein the duty cycle of the green laser aiming pattern includes setting the duration of the single aiming pulse of the trigger horizontal mode between 2 ms and 8 ms, and setting the duration of the single aiming pulse of the demonstration mode between 0.5 ms and 2 ms.

15. The method according to claim 12, characterized in that The peak pulse optical power constraint is the achievable emission limit of the aiming pulse.

16. The method according to claim 15, characterized in that The achievable emission limit AEL_Pulse in Watts (W) of the aiming pulse is expressed as: AEL_Pulse = 7×10 -4 *(tp) -.25 where tp is the pulse duration.

17. The method according to claim 12, characterized in that The heat dissipation constraint is an achievable emission limit P_ave in Watts (W) for the average power of the aiming pulse within a time window formed by a number of consecutive frame durations and is expressed as: P_ave=7×10 -4 (T1) -.25 Where T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

18. The method according to claim 12, characterized in that Determining the duty cycle of the green laser aiming pattern includes determining the duty cycle DC that satisfies both the peak pulse optical power constraint and the heat dissipation constraint according to the following expression: Where Tf is the frame duration and T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

19. The method of claim 12, wherein: Determining the duty cycle of the green laser aiming pattern includes determining the duty cycle DC that satisfies both the peak pulse optical power constraint and the heat dissipation constraint by being within +20% and -90% of the following expression: Where Tf is the frame duration and T1 is the time window duration and varies with the power rating of the green laser source according to the laser safety level.

20. The method of claim 12, wherein: The duty cycle of the aiming pulse is an overlapping duty cycle such that a sensor exposure window of the imager and the aiming pulse at least partially overlap during the frame duration.

21. The method of claim 12, wherein: The duty cycle of the aiming pulses is an overlapping duty cycle such that the aiming pulses occur within a sensor exposure window of the imager during the frame duration.

22. The method of claim 12, wherein: The peak pulse optical power constraint is the peak power at the central spot of the green laser aiming pattern.

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