Field-selectable dynamic gain control mode for optical sensors

Abstract

Apparatus and related methods relate to a field-selectable gain mode system. In illustrative examples, an APD-based sensor can have two or more predetermined gain modes. For example, a gain mode can be activated in response to a user-generated selection signal. For example, an APD-based sensor can apply a user-selected gain mode by independently controlling a circuit gain, a transmitter gain, and an APD gain. When a user selection signal is selected, for example, a controller can apply corresponding independent gain parameters to the circuit gain, the transmitter gain, and the APD gain, thereby providing a collective high dynamic range sensor system. For example, the independent gain parameters can include a range of control voltages, a range of control currents, and / or a range of gain inputs. Various embodiments can advantageously enable increased precision over an extended operating range of gain values.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 261,311, titled “Field-Selectable Dynamic Gain Control Modes of Optical Sensors,” by Ashley Wise, filed September 17, 2021.

[0003] This application incorporates by reference the entire contents of the foregoing applications.

[0004] The subject matter of this application can have the same inventive power and / or can be related to the subject matter of:

[0005] U.S. Application Serial No. 15 / 625,949, titled “Open-Loop Laser Power-Regulation,” by Ashley Wise, filed June 16, 2017, and issued as U.S. Patent No. 9985414 on May 29, 2018;

[0006] U.S. Application Serial No. PCT / US21 / 71304, titled “Open-Loop Photodiode Gain Regulation,” by Ashley Wise et al., filed August 27, 2021;

[0007] U.S. Application Serial No. 63 / 107,311, titled “Frequency Domain Opposed-Mode Photoelectric Sensor,” by David S. Anderson et al., filed October 29, 2020;

[0008] U.S. Application Serial No. 17 / 036,255, titled “Near Range Radar,” by Ashley Wise et al., filed September 29, 2020;

[0009] U.S. Application Serial No. 62 / 924,025, titled “Near Range Radar,” by Ashley Wise et al., filed October 21, 2019;

[0010] U.S. Application Serial No. 17 / 446,142, titled “Open-Loop Photodiode Gain Regulation,” by Ashley Wise et al., filed August 26, 2021; and

[0011] U.S. Application Serial No. 63 / 071,080, titled “Open-Loop Photodiode Gain Regulation,” filed August 27, 2020 by Ashley Wise et al.

[0012] The present application incorporates by reference the entire contents of the foregoing applications. TECHNICAL FIELD

[0013] Various embodiments relate generally to gain control.

[0014] BACKGROUND

[0015] Photodiodes, including avalanche photodiodes (APDs), are employed in a range of applications. Applications can include, but are not limited to, presence and positioning in optoelectronic sensors, distance measurement in triangulation and time-of-flight sensors, and fiber optic communications.

[0016] In some examples, the accuracy of distance measurements using APDs can be affected by the reflectivity and distance of a target object. In some examples, the sensitivity of distance measurements can also be affected by environmental parameters such as temperature and ambient light. Accordingly, calibration can sometimes be applied to adjust a distance sensor according to a measurement environment.

[0017] SUMMARY

[0018] Apparatuses and related methods relate to a field selectable gain mode system. In illustrative examples, for example, an APD-based sensor can have two or more predetermined gain modes. For example, a gain mode can be activated in response to a user-generated selection signal. For example, an APD-based sensor can apply a user-selected gain mode by independently controlling a circuit gain, a transmitter gain, and an APD gain. When a user selection signal is selected, for example, a controller can apply corresponding independent gain parameters to the circuit gain, the transmitter gain, and the APD gain, thereby providing a collectively high dynamic range sensor system. For example, the independent gain parameters can include a range of control voltages, a range of control currents, and / or a range of gain inputs. Various embodiments can advantageously achieve increased accuracy over an extended operating range of gain values.

[0019] Various embodiments can realize one or more advantages. For example, some embodiments can further generate a measurement offset profile based on the user-selected gain mode to advantageously maintain high measurement accuracy independent of the user-selected gain mode. For example, some embodiments can advantageously improve gain adjustment latency by comparing the updated set of gain parameters to the original set of gain parameters such that only gain parameters with changes are applied. For example, some embodiments can generate at least one of the user-selectable gain modes based on measured environmental parameters to advantageously maintain measurement accuracy according to the measured environmental parameters.

[0020] The details of various embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims. DETAILED DESCRIPTION

[0022] Figure 1 An exemplary selectable dynamic gain mode sensor (SDGMS) employed in an illustrative use case scenario is depicted.

[0023] Figure 2 A block diagram of an exemplary SDGMS system is depicted.

[0024] Figure 3 An electrical block diagram of an exemplary SDGMS system is depicted.

[0025] Figure 4 An exemplary limited dynamic range window that can be extended by an exemplary SDGMS system is depicted.

[0026] Figure 5 An exemplary set of nominal user-selectable gain mode levels is depicted.

[0027] Figure 6 An exemplary amplitude plot of an exemplary high reflectivity (HR) gain mode of an exemplary SDGMS is depicted.

[0028] Figure 7 An exemplary amplitude plot of an exemplary low reflectivity (LR) gain mode of an exemplary SDGMS is depicted.

[0029] Figure 8 An exemplary SDGMS system control method is depicted.

[0030] Figure 9A And Figure 9B An exemplary user interface interaction process for field-adjusting a first channel of an exemplary SDGMS is depicted.

[0031] Figure 10An exemplary user interface interaction process for depicting a second channel of an exemplary SDGM is depicted.

[0032] Like reference symbols in the various drawings indicate like elements.

[0033] DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0034] Figure 1 An exemplary selectable dynamic gain mode sensor (SDGMS) employed in an illustrative use case scenario is depicted. In an exemplary scenario 100, a SDGMS 105 can be operated by a user 110 to a desired gain mode. The SDGMS 105 can have a user interface including a display 115. The interface can include a user input element 120 (e.g., a button). The user 110 can operate the user input element 120 as shown in an exemplary interface display 125 to selectively operate the SDGMS 105 to a predetermined dynamic gain mode. As shown, by way of example and not limitation, the dynamic gain modes can include a performance ("PErF"), a low reflectivity (LR) gain mode ("bLAc"), and a high reflectivity (HR) gain mode ("ShnY"). In some embodiments, by way of example and not limitation, the performance mode can be a default mode.

[0035] The user 110 can, for example, operate the SDGMS 105 to a gain mode that is suitable for a target object. The SDGMS 105 can, for example, be configured as a distance sensor. When using the SDGMS 105 to detect a distance to a high-reflectivity target, such as a shiny metal target 135 (e.g., a polished metal toolbox), the user 110 can select the HR gain mode. When using the SDGMS 105 to detect a distance to a normal-reflectivity target, such as a paperboard box 130, the user 110 can select the performance (e.g., "normal" gain). When using the SDGMS 105 to detect a distance to a minimal-reflectivity target, such as a black rubber tire 140, the user 110 can select the LR gain mode. Thus, in various embodiments, the SDGMS 105 can be advantageously fielded to one of a plurality of (predetermined) dynamic gain modes according to the (current) intended application.

[0036] Each (predetermined) dynamic gain mode can correspond to one or more predetermined settings. For example, when the SDGMS 105 is operated to a predetermined gain mode, the control unit of the SDGMS 105 can apply a predetermined gain mode profile to various hardware and / or software parameters. The gain mode profile can for example include a transmitter power parameter. The gain mode profile can for example include a receiver drive control (e.g., drive voltage, drive current) parameter. The gain mode profile can for example include at least one calibration profile. The calibration profile can for example include a temperature calibration. The calibration profile can for example include a voltage calibration. For example, the predetermined gain mode can advantageously optimize the SDGMS 105 for a predetermined operating mode. Within the predetermined gain mode, the SDGMS 105 can advantageously dynamically adjust the gain within a (predetermined) range. The dynamic gain range can for example be determined as a function of the gain mode profile.

[0037] For example, APDs can be used in myriad applications. By way of example and not limitation, APDs can include single-photon avalanche diodes (SPADs). For example, APDs can include silicon photomultipliers (SiPMs). In some embodiments, for example, APDs can include multi-pixel photon counters (MPPCs).

[0038] In various embodiments, for example, APDs can be applied to presence measurements. APDs can for example be applied to distance measurements. In some embodiments, a system including APDs can be configured as a time-of-flight sensor. In some embodiments, APDs can for example be used in fiber-optic communication implementations.

[0039] APDs can for example operate at high reverse bias voltages. By way of example and not limitation, reverse bias voltages can include a range of 20 to 200 volts.

[0040] APDs can for example provide current gain of the photoelectric current in the order of 1 to 100. When operated in Geiger-mode, APD gain can for example be in the order of several thousands to several millions. In some embodiments, for example, the current gain of the APD can be embedded in a photodetector. Such embodiments can for example advantageously provide improved signal-to-noise ratio relative to photodetectors with external gain, such as transimpedance amplifiers (TIAs). In some embodiments, a TIA can be implemented to obtain the output of the APD.

[0041] APD gain can be proportional to the reverse bias voltage. If the reverse bias voltage is too low, the APD can not operate at all. If the reverse bias voltage is too high, the APD can enter Geiger mode (which can be unstable). Accordingly, various embodiments can adjust APD gain up and down to accommodate a wide range of light intensities hitting the APD. Adjusting the gain of the APD can be done, for example, by adjusting the reverse bias voltage. In some embodiments, the settling time for (dynamic) APD gain adjustment can be long. For example, in some embodiments, a large APD gain adjustment time can be up to 250 ms. For example, in some embodiments, switching from 100x gain to 10x gain can require waiting hundreds of milliseconds for the gain change to take effect. However, in some applications, the photosensor can need to operate with a response speed of around 250us to 5ms. Accordingly, during run mode operation, a large APD gain adjustment time can be too slow to occur without interrupting the sensor response time.

[0042] Various embodiments can advantageously operate the APD gain into predetermined gain modes corresponding to a (limited) dynamic range. The output gain of the APD can be adjusted, for example, over a dynamic range. The APD can operate, for example, at a predetermined reverse bias voltage based on the currently selected gain mode. The APD can operate, for example, within a limited reverse bias voltage range corresponding to a (predetermined) maximum response time and based on the currently selected gain mode. Accordingly, various embodiments can advantageously provide a wide gain range while achieving fast response times.

[0043] The dynamic range of light intensities hitting a photodiode (e.g., APD) can be quite large. In some systems, for example, light emitted by a light emitting element (e.g., laser, vertical cavity surface emitting laser (VCSEL), edge emitting laser (EEL), LED) can be reflected by a target, and a portion of that reflected light, including diffuse and specular components, can be received on the APD.

[0044] In some embodiments, the SDGMS 105 can be configured with gain modes corresponding to a “normal” target having a reflectivity between 3% and 90% diffuse reflection, and negligible specular reflection, by way of example and not limitation. However, many applications can require sensing a wider range of targets, such as, for example, targets including clear and high angle (0.1%) and partially specular (1000%). This exemplary range of reflectivities can represent a dynamic range of 1:10000. Fully specular targets, such as mirrors and retro-reflectors, can require a dynamic range of 1:100000 or more, for example.

[0045] Light intensity decreases 1 / D 2(where D = distance). Thus, a low reflectivity target requiring a 1: 10000 dynamic range at a distance D can require a 1: 250000 dynamic range at a second distance = 5*D.

[0046] For example, a dynamic range of an electronic circuit can be required to match a required dynamic range of an intended target. The dynamic range of an electronic circuit can be measured, for example, relative to a noise floor and / or baseline. The baseline / noise floor can be, for example, a minimum operating level (e.g., voltage, current, ADC value) at which a signal can be sufficiently distinguished from noise.

[0047] For example, a dynamic range of an electronic circuit can be limited at an upper limit by saturation. When a voltage, current, and / or ADC input is above a threshold, the circuit can saturate and be unable to further measure the input. For a given electronic circuit configuration, the dynamic range can include, for example, a saturation divided by a noise floor.

[0048] For a given electronic circuit configuration, the ratio of saturation to noise floor can be between 1:50 and 1:200, by way of example and not limitation. For example, to meet a minimum dynamic range of 1: 10000, the circuit dynamic range can need to be scaled by a change in gain. For example, increasing the gain by a factor of 10 can provide a dynamic range of 1:500 to 1:2000 by a change in gain. In various embodiments, this principle can be advantageously applied, for example, to provide a circuit with a desired dynamic range (e.g., greater than the example, less than the example).

[0049] Figure 2 A block diagram of an example SDGMS system is depicted. In the depicted example SDGMS system 200, a transmitter 205 is controlled by a transmitter power module 210. In the depicted illustrative example, the transmitter power module can adjust transmitter power, by way of example and not limitation, by changing current to a laser. The transmitter power module can provide, for example, a transmitter power dynamic range of between 1:5 to 1:20. In various examples, the transmitter 205 can transmit a signal (e.g., an electromagnetic signal) to a target object 215. The transmitter 205 can include, for example, an optoelectronic transmitter. The transmitter 205 can include, for example, a laser, and the transmitted signal can include a light beam. The transmitter 205 can include, for example, an LED. The transmitter 205 can transmit, for example, a pulsed signal. The pulsed signal can be clocked, for example. A monitor photodiode can measure a characteristic of the transmitted signal, for example.

[0050] The receiver may, for example, receive a reflection of the transmitted signal reflecting off of a target object 215. The receiver may, for example, include a photodetector. As shown, the photodetector can include an avalanche photodiode (APD 220). The APD 220 is driven by an APD voltage 225 (e.g., a reverse bias voltage). As shown, the APD voltage 225 may, for example, represent a dynamic gain range from 1 : 1 to 1 :20.

[0051] In the depicted example, an electronic circuit gain is applied to the output (e.g., voltage, current) of the APD 220. As shown, the electronic circuit gain can be provided by a transimpedance amplifier (TIA 230). The TIA 230 may, for example, be implemented to adjust the gain of the output of the APD 220.

[0052] In the depicted example, the electronic circuit gain can be provided by a gain stage (e.g., operational amplifier gain stage) circuit (gain stage 235). The stage 235 may, for example, be implemented to adjust the gain of the output of the APD 220. In some embodiments, the stage 235 can operate directly on the output of the APD 220. In some embodiments, the stage 235 may, for example, operate on the output of the TIA 230. The electronic circuit gain (e.g., TIA 230 and / or stage 235) may, for example, provide a dynamic range between 1 :5 to 1 :20 in adjustable gain.

[0053] As shown, an analog-to-digital converter (ADC 240) circuit can operate on the output of the stage 235. The ADC 240 may, for example, operate on the output of the TIA 230. The ADC 240 may, for example, provide a dynamic (gain) range between 1 :50 to 1 :200 relative to the noise floor of the signal.

[0054] Overall, in the upper limit, the depicted example SDGMS system 200 can have a dynamic range of 1 :80,000 in the depicted gain mode. In some embodiments, the gain mode may, for example, be adjustable. Some embodiments may, for example, further increase this dynamic range. Various embodiments may, for example, advantageously enable a single sensor system to view both dark targets (e.g., 0.1% reflectivity) at long distances, as well as highly reflective targets (e.g., 1000% reflectivity) at close range. Various such embodiments may, for example, account for an additional 1 / D2 factor (where D = distance to target) of target intensity versus distance.

[0055] Various embodiments can, for example, provide transmitter gain control and circuit gain control to advantageously achieve a wide dynamic range while maintaining fast response speed. Some embodiments can, for example, increase the dynamic range (e.g., greater than 1 :80000) by another order of magnitude. For example, a combination of circuit gain control and transmitter gain control (e.g., through selectable gain modes) can advantageously provide, in some embodiments, more gain between, for example and without limitation, 5x and lOOx. Such embodiments can, for example, allow for a user-selectable APD gain mode that optimizes the electronic circuitry and software for two or more gain modes. Accordingly, various embodiments can advantageously provide predetermined gain modes to increase the effective gain range of a single sensor across multiple gain modes that would otherwise be too slow to be strictly enforced during a run mode, while maintaining fast response speed.

[0056] In various embodiments, the selectable gain modes can be associated with (predetermined) calibration profiles. For example, various embodiments can advantageously maintain measurement accuracy for all selectable gain modes. Various embodiments can advantageously maintain consistent gain levels across a wide temperature range. For example, some embodiments can advantageously maintain consistent gain levels between -10°C and +50°C.

[0057] Figure 3 An electrical block diagram of an exemplary SDGMS system is depicted. The SDGMS 300 includes a processor 305 (e.g., a “microcontroller” as shown). The processor 305 is operably coupled to a random access memory module (RAM 320). The processor 305 is operably coupled to a program memory module 310 (e.g., a non-volatile memory).

[0058] In the depicted example, the program memory module 310 includes a temperature and accuracy compensation memory module (TACMM 315). The TACMM 315 can, for example, include (predetermined) temperature calibration profiles. The TACMM 315 can, for example, include (predetermined) accuracy calibration profiles. The calibration profiles can, for example, be specific to a sensor. The calibration profiles can, for example, be specific to a sensor family. The calibration profiles can, for example, include parameters. The calibration profiles can, for example, be embodied in the form of one or more lookup tables (LUTs). The calibration profiles can, for example, include one or more predetermined calibration relationships (e.g., equations).

[0059] The processor 305 is operatively coupled to the user interface 325. The processor 305 can receive signals from and / or send signals to a user, e.g., via the user interface 325. For example, a user can operate the user interface 325 to provide a signal to the processor 305 to select a (predetermined) gain mode. The processor 305 receives a gain selection signal 330. The gain selection signal 330 can be received via the user interface 325, e.g., in response to a user’s operation. In the depicted example, the processor 305 also receives a temperature input signal 335. The processor 305 can retrieve a calibration profile from the TACMM 315, e.g., in response to the gain selection signal 330 and / or the temperature input signal 335. The processor 305 can retrieve a gain mode profile from the program memory module 310, e.g., in response to the gain selection signal 330.

[0060] The processor 305 is also operatively coupled to a circuit controller 340. The circuit controller 340 outputs control signals to a gain stage (e.g., the gain stage 235). The gain stage can operate, e.g., on an output of an APD.

[0061] The processor 305 is also operatively coupled to a digital-to-analog converter module 345 (“DAC”). The converter module 345 provides a signal to a high voltage driver 350. The converter module 345 can provide a signal to the high voltage driver 350, e.g., in response to a signal generated by the processor 305 in accordance with a gain selection mode. The high voltage driver 350 generates an APD voltage (e.g., a drive voltage, a reverse bias voltage) in response to a signal received from the converter module 345.

[0062] The processor 305 is operatively coupled to a converter module 355 (“DAC”). The converter module 355 is operatively coupled to a transmitter current driver 360. The converter module 355 can generate a signal for the transmitter current driver 360, e.g., in response to a currently selected gain mode profile. The transmitter current driver 360 generates a transmitter current (e.g., for driving the transmitter 205). The transmitter current driver 360 can generate a transmitter current, e.g., in response to a signal from the converter module 355.

[0063] Accordingly, various embodiments can advantageously implement gain control through a combination of transmitter gain control (e.g., via the converter module 355 and / or the transmitter current driver 360), APD (receiver) gain control (e.g., via the converter module 345 and / or the high voltage driver 350), and / or electronic circuit control (e.g., the circuit controller 340). The SDGMS 300 can dynamically operate, e.g., within a wider gain range operable by the sensor, within a limited dynamic gain range, in response to a currently selected gain mode. Accordingly, various embodiments can advantageously implement fast response times within an extended operating range of gain values.

[0064] Figure 4 An example limited dynamic range window that can be extended by an example SDGMS system is depicted. Plot 400 depicts amplitude versus true distance (mm) in a single gain mode. For example, amplitude can be approximately (1 / distance 2 ). Plot 400 can represent, for example, a "normal" gain mode. Plot 400 can represent, for example, a sensor without selectable gain ranges.

[0065] In the depicted example, a signal received from a very high reflectivity target (e.g., > 1000%) at a minimum gain level in the near range (e.g., < 1500 mm) can exceed the saturation threshold of the sensor, as shown by the "x" data points in plot 400. In region 405, light received from a very high reflectivity target can be above saturation at a minimum gain in the near range. A signal received from a very low reflectivity target (e.g., < 0.1%) at a maximum gain level in the far range (e.g., > 2000 mm) can be below the noise floor of the sensor, as shown by the "o" data points in plot 400. In region 410, light received from a very low reflectivity target can be below the noise floor at a maximum gain level in the far range.

[0066] For example, in a given gain mode, a high reflectivity target can be above saturation in the near range even at a minimum gain level. In a given gain mode, a very low reflectivity target can be below the noise floor in the far range even at a maximum gain level.

[0067] Various embodiments can advantageously provide a user selectable gain mode that adjusts APD gain to an (predetermined) operating value. Various embodiments can advantageously provide a user selectable gain mode that adjusts APD gain to an (predetermined) operating range. For example, some embodiments can advantageously provide an additional adjustment of 1 : 1 to 1 : 20. Such embodiments can advantageously increase the dynamic range of the system (e.g., at least with reference to Figure 2 and Figure 3 disclosed ranges) to around 1 : 1000000.

[0068] Figure 5 An example set of nominal user selectable gain mode levels is depicted. Plot 500 represents an example of three user selectable gain levels. For example, 2x gain (e.g., of an APD) can correspond to an HR mode. As shown, 10x gain can correspond to a "normal" (e.g., "performance") mode, for example. As shown, 50x gain can correspond to an LR mode, for example.

[0069] For example, various embodiments can be provided with predetermined gain mode levels that are geometrically related to one another. For example, each gain mode can be a (predetermined) multiple of the previous gain mode (e.g., 5 times as shown). In some embodiments, for example, the normal gain mode can be selected in the transition between the substantially linear section of the relative linear gain versus APD voltage relationship.

[0070] Figure 6 An exemplary amplitude plot of an exemplary high reflectivity (HR) gain mode of an exemplary SDGMS is depicted. Plot 600 may, for example, represent the amplitude versus true range in the HR gain mode. The gain mode may, for example, correspond to 2x APD gain (e.g., as disclosed at least with reference to Figure 5 In the depicted example, for lower APD gain, a high reflectivity target at minimum gain is below the saturation level.

[0071] Figure 7 An exemplary amplitude plot of an exemplary low reflectivity (LR) gain mode of an exemplary SDGMS is depicted. Plot 700 may, for example, represent the amplitude versus true range in the LR gain mode. The gain mode may, for example, correspond to 50x APD gain (e.g., as disclosed at least with reference to Figure 5 In the depicted example, for higher APD gain, a very low reflectivity target at maximum gain is above the noise floor.

[0072] Figure 8 An exemplary SDGMS system control method is depicted. Method 800 may, for example, be performed by a processor 305 executing instructions stored in a program memory module 310. Method 800 starts 805 and obtains 810 a user selectable gain mode (e.g., corresponding to a current value based on input from a user interface). The automatic gain settings corresponding to the gain mode are retrieved 815. The current temperature is retrieved 820 (e.g., from a temperature sensor). In step 825, an offset is generated (e.g., retrieved, calculated) and applied to the APD DAC to achieve the desired gain at the current temperature. The offset is applied 830 to the transmitter DAC to achieve the desired transmitter power at the current temperature. The circuit control gain level is set 835.

[0073] A measurement (e.g., corresponding to a signal received by the APD) is performed 840.

[0074] An offset is applied 845 to the measurement based on the current APD setting. An offset is applied 850 to the measurement based on the transmitter setting. An offset is applied 855 to the measurement based on the circuit control. An offset is applied 860 to the measurement based on the current temperature (e.g., calibrated in response to the current gain mode). A final measurement value is generated 865. The final measurement can advantageously have high precision, for example, over a wide dynamic range.

[0075] In various embodiments, the offset to improve precision due to gain setting and temperature can be computed, for example, on an independent basis. In various embodiments, the offset to improve precision due to gain setting and temperature can be computed, for example, on a series basis. For example, the offset can be implemented as a direct value. For example, the offset can be implemented as a LUT. For example, the offset can be implemented as an equation.

[0076] Figure 9A and Figure 9B An exemplary user interface interaction process is depicted for field adjusting a first channel of an exemplary SDGMS. Figure 10 An exemplary user interface interaction process is depicted for field adjusting a second channel of an exemplary SDGM.

[0077] Although various embodiments have been described with reference to the accompanying drawings, other embodiments are possible.

[0078] Although an exemplary system has been described with reference to the accompanying drawings, other implementations can be deployed in other industrial, scientific, medical, commercial, and / or residential applications.

[0079] In some embodiments, the transmitter power can be adjustable. Such embodiments can advantageously reduce light directly into the APD, for example. Such embodiments can have a less predictable current versus wattage curve for the transmitter at low values, for example. In addition, if a monitor photodiode is used, its signal level can also be reduced. For example, there can be a fundamental limit on the high side of the transmitter power. For example, the transmitter element itself can have a physical limit on peak power. For example, at higher temperatures at which the sensor can operate, the limit can be lower. For example, operating the transmit power higher can also be limited by laser class limits and / or FDA light limits.

[0080] In some embodiments, the circuit gain can be adjustable. For example, a TIA gain can provide a good signal-to-noise ratio. However, it can be difficult to make the TIA gain adjustable, for example. The range of gain that can be achieved by TIA gain adjustment can be limited, for example. In various embodiments, an operational amplifier-based gain stage can be implemented to adjust the circuit gain. In some embodiments, the circuit bandwidth and / or RMS noise level can change when adjusting the gain. High gain and high signal bandwidth can be difficult to achieve simultaneously, for example (e.g., with an operational amplifier-based gain stage, with circuit gain adjustment).

[0081] In some embodiments, the integration time can be adjustable, for example. For example, some embodiments can integrate a circuit and / or a light receiving element, such as a CMOS pixel. In such embodiments, the exposure time can be adjusted to change the gain, for example. A longer exposure time can correspond to increased collection of ambient light, which can add noise to the signal measurement.

[0082] In some embodiments, the optics can be adjusted, for example. For example, the effective clear aperture of the optical system can be adjusted to control the amount of light received. Such embodiments can increase mechanical complexity, for example. Some embodiments can increase the response time, for example.

[0083] Some sensor embodiments can be provided with separate fixed hardware and / or optical configurations, for example. Different configurations can be provided as separate sensors (e.g., different models), for example. Different configurations can be optimized separately for different operating modes, for example. For example, a first configuration can be optimized for a range of dark targets (less light received). For example, a second configuration can be optimized for a range of bright targets (more light received). These embodiments can therefore require customers to purchase different configurations for different applications, for example. Such embodiments can require replacing sensors and / or installing multiple different configurations in order to monitor targets with a desired range of reflectivity (wide), for example. Various embodiments can advantageously provide gain adjustment for APDs while maintaining a single sensor model and hardware configuration.

[0084] In various embodiments, changes in the circuit gain mode, such as adjusting the APD voltage, can also change characteristics that affect system accuracy (e.g., if the sensor uses light measurements for distance, the change can alter the accuracy of the distance measurement). Naive systems can adjust the gain parameter without adjusting compensation for measurement accuracy, for example.

[0085] Control parameters (e.g., voltage values, current values) for circuit gain mode changes can vary with temperature. For example, naive systems can not account for this. For example, such systems can have inconsistent gains over a wide temperature range.

[0086] For example, APDs can be used in time-of-flight (TOF) principle distance measurement systems. In TOF systems, signal amplitudes measured by photodiodes can directly relate to the accuracy of distance measurements. For example, variations in gain levels can change the timing of signals. The shape of signals (e.g., how fast the leading edge of a pulse rises, how strong the leading edge of a pulse is) can affect the time of measurement of a signal. For example, variations on the order of 67 picoseconds can represent a distance error of 1 cm. For example, variations on the order of 6.7 ns can represent a distance error of 1 meter. Various embodiments can provide control over electrical gain paths and signal amplitudes. Such embodiments can, for example, advantageously provide control that is critical to achieving a desired and / or required distance measurement accuracy (e.g., 1 cm level accuracy). Various embodiments can, for example, advantageously allow gain adjustments while maintaining measurement accuracy.

[0087] Various embodiments can apply one or more measurement principles. For example, various measurement principles can be affected by gain adjustments and / or dynamic ranges. Some embodiments can be configured to measure distances, for example, by triangulation principles. Some embodiments can be configured to measure light intensity (e.g., in relation to distance).

[0088] Various embodiments can be configured to communicate via one or more communication protocols. For example, in some embodiments, an SDGMS can be configured to transmit output signals to a controller. An SDGMS can, for example, be configured to generate output signals in at least one communication protocol including, by way of example and without limitation, IO-Link, Modbus, ProfiNet, Ethernet, serial communication, or some combination thereof. In some embodiments, an SDGMS can be configured to receive input signals from a controller. An SDGMS can, for example, be configured to receive input signals in at least one communication protocol including, by way of example and without limitation, IO-Link, Modbus, ProfiNet, Ethernet, serial communication, or some combination thereof. For example, user inputs can be received from a remote device via at least one communication protocol. User inputs can, for example, include signals indicative of a selection of a gain mode. In some embodiments, gain modes can be automatically selected by a device (e.g., a controller) based on predetermined criteria. For example, gain modes can be selected based on a type of object being detected. For example, gain modes can be selected based on a schedule (e.g., shiny objects run Monday through Tuesday, cardboard boxes run Wednesday through Friday). Thus, some embodiments can advantageously selectively control gain for multiple sensors across a network.

[0089] In various embodiments, some bypass circuit implementations can be controlled in response to signals from analog or digital components, which can be discrete, integrated, or a combination of each. Some embodiments can include programmed devices, programmable devices, or some combination thereof (e.g., PLA, PLD, ASIC, microcontroller, microprocessor), and can include one or more data stores (e.g., cells, registers, blocks, pages) that provide single or multiple levels of digital data storage capability, and can be volatile, non-volatile, or some combination thereof. Some control functions can be implemented in hardware, software, firmware, or any combination thereof.

[0090] A computer program product can contain a set of instructions that, when executed by a processor device, cause the processor to perform prescribed functions. These functions can be performed in conjunction with a controlled device in operable communication with the processor. A computer program product, which can include software, can be stored in a data store tangibly embodied on a storage medium, such as an electronic, magnetic, or rotational storage device, and can be fixed or removable (e.g., hard disk, floppy disk, thumb drive, CD, DVD).

[0091] Although examples of systems that can be portable have been described with reference to the above figures, other implementations can be deployed in other processing applications, such as desktop and networked environments.

[0092] For example, temporary auxiliary energy input can be received from a rechargeable or disposable battery, which can enable use in portable or remote applications. Some embodiments can operate using other DC voltage sources, such as using a 9V (nominal) battery. Alternating current (AC) input can be received, for example, from a 50 / 60 Hz power port or from a portable generator, via a rectifier and appropriate scaling. Supply of AC (e.g., sinusoidal, square, triangular) input can include a line frequency transformer to provide voltage boosting, voltage stepping down, and / or isolation.

[0093] Although specific features of the architecture have been described, performance can be improved in connection with other features. For example, caching (e.g., LI, L2,...) techniques can be used. Random access memory can be included, for example, to provide scratch pad memory and / or to load executable code or parameter information stored for use during run-time operations. Other hardware and software can be provided to perform operations, for example, networks or other communications using one or more protocols, wireless (e.g., infrared) communications, stored operational energy and power sources (e.g., batteries), switching and / or linear power circuitry, software maintenance (e.g., self-test, upgrades), etc. One or more communication interfaces can be provided to support data storage and related operations.

[0094] Some systems can be implemented as computer systems that can be used for various implementations. For example, various implementations can include digital circuitry, analog circuitry, computer hardware, firmware, software, or combinations thereof. An apparatus can be implemented in a computer program product tangibly embodied in an information carrier, e.g., in a machine-readable storage device, for execution by a programmable processor; methods can be performed by a programmable processor executing a program of instructions to perform functions of various embodiments by operating on input data and generating output. Various embodiments can advantageously be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and / or at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, in a computer to perform a specified activity or bring about a specified result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0095] As an example, suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or input to, or both, one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD- ROM disks. The mass storage devices, the processor and the memory can be supplemented by, or incorporated in, ASICs (application- specific integrated circuits).

[0096] In some implementations, each system can be programmed with the same or similar information and / or initialized with substantially the same information stored in volatile and / or non-volatile memory. For example, one data interface can be configured to perform auto-configuration, auto-download, and / or auto-update functions when coupled to an appropriate host device, such as a desktop computer or a server.

[0097] In some implementations, one or more user interface features can be configured to perform specific functions. Various embodiments can be implemented in computer systems including graphical user interfaces and / or Internet browsers. To provide for interaction with a user, some implementations can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer.

[0098] In various implementations, the system can communicate using suitable communication methods, equipment, and techniques. For example, the system can communicate with compatible devices (e.g., devices capable of transmitting data to and / or from the system) using point-to-point communication, in which a message is transmitted directly from a source to a receiver over a dedicated physical link (e.g., a fiber optic link, point-to-point wiring, a daisy chain). The components of the system can exchange information through analog or digital data communications of any form or medium, including packet-based messages over a communications network. Examples of communications networks include, for example, LANs (local area networks), WANs (wide area networks), MANs (metropolitan area networks), wireless and / or optical networks, computers and networks that form the Internet, or some combination thereof. Other implementations can transmit messages by broadcasting to all or substantially all devices coupled together by a communications network, such as by using an omnidirectional radio frequency (RF) signal. Still other implementations can transmit messages that feature high directivity, such as RF signals transmitted using directional (i.e., narrow-beam) antennas or infrared signals that can optionally be used with focusing optics. Still other implementations are possible using suitable interfaces and protocols, such as, by way of example and not intended to be limiting, Modbus, IO-Link, serial communication, USB 2.0, Fire wire, ATA / IDE, RS-232, RS-422, RS-485, 802.11a / b / g, Wi-Fi, Ethernet, IrDA, FDDI (Fiber Distributed Data Interface), Token Ring, multiplexing techniques based on frequency-division, time-division, or code-division, or some combination thereof. Some implementations can optionally incorporate features such as error detection and correction (ECC) for data integrity, or security measures such as encryption (e.g., WEP) and password protection.

[0099] In various embodiments, a computer system can include an Internet of Things (IoT) device. An IoT device can include objects that have embedded electronics, software, sensors, actuators, and network connectivity that enable these objects to collect and exchange data. IoT devices can send data to another device through an interface, enabling use with wired or wireless devices. IoT devices can collect useful data and then transmit the data autonomously between other devices.

[0100] Various examples of modules can be implemented using circuitry including a variety of electronic hardware. By way of example, and not limitation, the hardware can include transistors, resistors, capacitors, switches, integrated circuits, other modules, or some combination thereof. In various examples, the modules can include analog logic, digital logic, discrete components, traces, and / or memory circuitry fabricated on a silicon substrate, including various integrated circuits (e.g., FPGAs, ASICs), or some combination thereof. In some embodiments, the modules can involve execution of preprogrammed instructions, software executed by a processor, or some combination thereof. For example, various modules can involve both hardware and software.

[0101] In an illustrative aspect, a method can increase dynamic range in an optical measurement sensor. The method can include providing a user selection of APD gain modes, where the user can select between two or more gain modes. The gain modes can be consistent across an operating temperature range. Measurements can be offset based on the gain modes (e.g., to maintain accuracy).

[0102] The method can also include automatic gain control via additional circuit control of the transmitter current. The method can include automatic gain control via at least one TIA. The method can include automatic gain control via at least one operational amplifier gain switch. The method can include automatic gain control via a combination of at least one TIA and at least one operational amplifier gain switch. In some embodiments, the method can omit at least one TIA and / or at least one operational amplifier gain switch.

[0103] For example, the automatic gain can be consistent across an operating temperature range. Measurements can be offset based on the circuit gain settings (e.g., to maintain accuracy).

[0104] The user gain selection can be performed, for example, by a user interacting with an LED display. The user gain selection can be performed, for example, by a user interacting with an LCD display. The user gain selection can be performed, for example, by a user interacting with a button user interface on the sensor. The user gain selection can be communicated, for example, via an IO-Link. The user gain selection can be communicated, for example, via serial communication.

[0105] In illustrative aspects, a field-selectable gain mode sensor (e.g., 300) can include a user interface (e.g., 325) configured to receive a user selection from a plurality of predetermined user-selectable gain modes. The field-selectable gain mode sensor can include a controller circuit (e.g., 305) operably coupled to the user interface to receive the user selection of a predetermined user-selectable gain mode and determine a corresponding set of independent gain parameters. The field-selectable gain mode sensor can include a plurality of gain stages operably coupled to the controller circuit including a circuit gain control circuit (e.g., 340), a transmitter gain control circuit (e.g., 360), and an APD gain control circuit (e.g., 350).

[0106] For example, when a user-selectable gain mode is selected (810), the controller circuit can apply (e.g., 825, 830, 835) independent gain parameters corresponding to the selected user-selectable gain mode to the plurality of gain stages. For example, the controller circuit can apply (e.g., 845, 850, 855) a measurement offset profile based on the user-selectable gain mode profile. For example, the measurement offset profile can include offsets configured to be applied to distance measurements as a function of transmitter gain offsets, APD gain offsets, circuit gain offsets, and environmental parameters including ambient temperature and ambient light. For example, a target accuracy of distance measurements is maintained independent of the selected gain mode and a dynamic gain range is provided.

[0107] For example, the plurality of predetermined user-selectable gain modes can be generated based on at least one calibration profile. The calibration profile can include a temperature calibration profile, an accuracy calibration profile, and a lookup table storing predetermined parameters. For example, for each of the user-selectable gain mode profiles, a set of independent gain parameters corresponding to each of the circuit gain control circuit, the transmitter gain control circuit, and the APD gain control circuit can be generated.

[0108] The field-selectable gain mode sensor, upon receiving a user selection to switch from a first user-selectable gain mode to a second user-selectable gain mode such that a set of updated independent gain parameters are applied to the plurality of gain stages, for example, for each of the updated independent gain parameters in the second user-selectable gain mode, the controller circuit can apply the updated independent gain parameter only when the updated gain parameter is different from the corresponding original independent gain parameter.

[0109] For example, the independent gain parameters can include a range of control voltages. For example, the independent gain parameters can include a range of control currents. For example, the independent gain parameters include a range of gain selection inputs.

[0110] For example, at least one of a plurality of predetermined user-selectable gain modes can be generated based on the measured environmental parameter. For example, the controller circuit can be configured to dynamically adjust the individual gain parameters within a predetermined range when the field-selectable gain mode sensor is operating in the user-selectable gain mode. For example, the circuit gain control circuit can comprise a transimpedance amplifier.

[0111] Many implementations are described. However, it is to be understood that various modifications can be made. For example, advantageous results can be achieved if steps of the disclosed techniques were performed in a different order and / or if components of the disclosed systems were combined in a different manner, or if the components were supplemented with other components. Therefore, other implementations are also contemplated within the scope of the following claims.

Claims

1. A field-selectable gain mode sensor (300), comprising: User interface (325) is configured to receive user selections from a plurality of predefined user-selectable gain modes; A controller circuit (305) coupled to the user interface receives the user selection of the predetermined user-selectable gain mode and determines a corresponding set of independent gain parameters; as well as Multiple gain stages operatively coupled to the controller circuitry include a circuit gain control circuit (340), a transmitter gain control circuit (360), and an APD gain control circuit (350), wherein... When the user-selectable gain mode (810) is selected, the controller circuit applies the independent gain parameters corresponding to the selected user-selectable gain mode to the plurality of gain levels (825, 830, 835), and Based on user-selectable gain mode profiles, measurement offset profiles (845, 850, 855) are applied to provide a dynamic gain range corresponding to the target object; The measurement offset profile includes offsets applied to distance measurements based on transmitter gain offset, APD gain offset, circuit gain offset, and environmental parameters including ambient temperature and ambient light, thereby maintaining the target accuracy of the distance measurement independent of the selected gain mode.

2. The field-selectable gain mode sensor according to claim 1, wherein, The plurality of predetermined user-selectable gain modes are generated based on at least one calibration profile, wherein the calibration profile includes: Temperature calibration configuration file; Accuracy calibration configuration file; and A lookup table stores predetermined parameters such that, for each of the user-selectable gain mode configuration files, a set of independent gain parameters corresponding to each of the circuit gain control circuit, the transmitter gain control circuit, and the APD gain control circuit is generated.

3. The field-selectable gain mode sensor according to claim 1, wherein: When receiving the user selection to switch from a first user-selectable gain mode to a second user-selectable gain mode so that a set of updated independent gain parameters are to be applied to the plurality of gain levels, For each of the updated independent gain parameters in the second user-selectable gain mode, the controller circuit applies the updated independent gain parameter only if the updated gain parameter is different from the corresponding original independent gain parameter.

4. The field-selectable gain mode sensor according to claim 1, wherein, The independent gain parameter includes the range of the control voltage.

5. The field-selectable gain mode sensor according to claim 1, wherein, The independent gain parameter includes the range of the control current.

6. The field-selectable gain mode sensor according to claim 1, wherein, The independent gain parameter includes the range of the gain selection input.

7. The field-selectable gain mode sensor according to claim 1, wherein, At least one of the plurality of predetermined user-selectable gain modes is generated based on measured environmental parameters.

8. The field-selectable gain mode sensor according to claim 1, wherein, When the field-selectable gain mode sensor operates in a user-selectable gain mode, the controller circuit is configured to dynamically adjust the independent gain parameters within a predetermined range.

9. The field-selectable gain mode sensor according to claim 1, wherein, The circuit gain control circuit includes a transimpedance amplifier.

10. The field-selectable gain mode sensor according to claim 1, wherein, The multiple gain stages include operational amplifier-based gain stages.

11. The field-selectable gain mode sensor according to any one of claims 1-10, wherein, Each of the multiple pre-defined user-selectable gain modes corresponds to the dynamic range of the target object.

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