Detection pixels and pixel systems

Abstract

A pixel system for an imaging device can include one or more pixels including a pulse trigger component configured to detect a pulse at one or more threshold voltages; a timer system forming a part of and / or connected with the one or more pixels, the timer system including one or more flip-flop switches. The pulse trigger component can be configured to initiate the one or more flip-flop switches in response to detecting the pulse at the one or more thresholds. The pixel system can include a time-of-flight (TOF) module operatively connected to the one or more pixels and / or the timer system to determine a TOF based on an output from the timer system when either or both of passive imaging and asynchronous laser pulse detection are performed simultaneously.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to pixels, and more particularly to detection pixels and pixel systems. BACKGROUND

[0002] Certain pixel designs can be made to detect actively illuminated (e.g., laser pulses) rather than just passively illuminated. Conventional designs can only detect that a pulse has occurred, but cannot properly detect the transit time, and thus cannot accurately measure distance.

[0003] Such conventional methods and systems are generally considered satisfactory for their intended purpose. However, there is still a need in the art for improved detection pixels and pixel systems. The present disclosure provides a solution for this need. SUMMARY

[0004] According to at least one aspect of the present disclosure, a pixel system for an imaging device can include one or more pixels including a pulse trigger component configured to detect a pulse at one or more threshold voltages; a timer system forming a part of and / or connected with the one or more pixels, the timer system including one or more trigger switches. The pulse trigger component can be configured to initiate the one or more trigger switches in response to detecting the pulse at the one or more thresholds. The pixel system can include a time-of-flight (TOF) module operatively connected to the one or more pixels and / or the timer system to determine a TOF based on an output from the timer system.

[0005] The timer system can include at least one voltage ramp configured to allow the TOF module to determine a TOF of a signal based on a time-varying voltage value of the at least one voltage ramp. The timer system can include one or more analog-to-digital converters (ADCs), wherein the one or more ADCs are configured to receive voltage values from the at least one voltage ramp when the one or more trigger switches are initiated by the pulse.

[0006] The one or more pixels can include a voltage buffer connected to the at least one voltage ramp, a column buffer connected to each of the one or more ADCs, and a ramp capacitor connected to the column buffer. The one or more trigger switches can be disposed between each column buffer and the voltage buffer connected to the at least one voltage ramp.

[0007] The pulse trigger assembly can include a diode, an amplifier connected to the diode to receive a voltage therefrom, one or more high pass filters connected to the amplifier, a comparator for each of the one or more threshold voltages, and a voltage threshold trigger line connecting a respective comparator to a respective trigger switch of the one or more trigger switches. The pulse trigger assembly can include one or more TOF mode switches configured to selectively allow operation of the one or more trigger switches.

[0008] The one or more trigger switches can include a first trigger switch and a second trigger switch connected to a first comparator and a second comparator, respectively, and configured to be activated at a first threshold voltage of the pulse and a second threshold voltage of the pulse, respectively. The one or more TOF mode switches can include a first TOF switch and a second TOF switch. In the first TOF mode, the first TOF switch can be activated such that the first trigger switch can be activated. In the second TOF mode, the second TOF switch can be activated such that the second trigger switch can be activated.

[0009] The pulse trigger assembly can include an asynchronous laser pulse detection (ALPD) system selectively connected to the first threshold trigger voltage line by an ALPD mode switch. The ALPD system can be connected between the first comparator and the first TOF mode switch. The first TOF mode switch can be located between the first comparator and the first trigger switch. The second TOF mode switch can be connected between the amplifier and the second comparator.

[0010] The pixel can include a passive imaging system connected to the diode. The passive imaging system includes at least one passive imaging mode switch configured to allow passive imaging signals from the diode to be output to at least one of the one or more ADCs in a passive imaging mode. The pixel can be configured such that the passive imaging mode can be activated with the first TOF mode but not with the second TOF mode, and the ALPD mode can be activated with the passive imaging mode.

[0011] The one or more pixels can be configured to enable the first TOF mode and the second TOF mode to be initiated together to provide a multi-threshold readout, thereby allowing the TOF module to reduce or eliminate one or more errors. In certain embodiments, the one or more high pass filters can include a single high pass filter operatively connected to each comparator. The voltage ramp can be connected to a passive imaging line in front of the voltage buffer through a ramp switch.

[0012] According to at least one aspect of the present disclosure, a pixel can include any suitable embodiment of a pixel disclosed herein (e.g., as described above). For example, a pixel can include a pulse trigger component configured to detect a pulse at one or more threshold voltages, and a timer system connected to the pulse trigger component, the timer system including one or more trigger switches. The pulse trigger component can be configured to initiate the one or more trigger switches in response to detecting the pulse at the one or more thresholds. The timer system can include a voltage buffer configured to be connected to at least one voltage ramp, one or more column buffers configured to be connected one or more respective analog-to-digital converters (ADCs), wherein the one or more trigger switches are disposed between each column buffer and the voltage buffer, and one or more ramp capacitors connected to each column buffer for receiving a voltage from the voltage ramp. The pulse trigger component can include a diode, an amplifier connected to the diode to receive a voltage therefrom, one or more high pass filters connected to the amplifier, a comparator for each of the one or more threshold voltages, a voltage threshold trigger line connecting a respective comparator to a respective trigger switch of the one or more trigger switches, and one or more TOF mode switches configured to selectively allow operation of the one or more trigger switches. The one or more trigger switches can include a first trigger switch and a second trigger switch connected to a first comparator and a second comparator, respectively, and configured to initiate at a first threshold voltage of the pulse and a second threshold voltage of the pulse, respectively.

[0013] According to at least one aspect of the disclosure, a method can include determining a time of flight (TOF) of an output signal by first determining a single time value at which a pixel receives a pulse at two or more threshold voltages to determine a single time value at which the pulse is received. The method can then include comparing an initial voltage to a ramp voltage at the single time value at which the pulse is received using a voltage ramp to determine a voltage difference, and then correlating the voltage difference to the TOF based on correlation data. The method can also include selecting between a TOF multi-threshold mode and a different operating mode. The method can include any other suitable method or methods and / or one or more portions thereof.

[0014] These and other features of embodiments of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0015] For a more complete understanding of how to make and use the device and method of the present disclosure, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:

[0016] Figure 1 is a schematic diagram of an embodiment of an imaging system according to the present disclosure;

[0017] Figure 2 is a schematic diagram of an embodiment of a system according to the present disclosure;

[0018] Figure 3A is a schematic diagram of an embodiment of Figure 2 is shown as having both a passive imaging mode and an asynchronous laser pulse detection (ALPD) mode enabled;

[0019] Figure 3B is a schematic diagram of an embodiment of Figure 2 is shown as having both a first time of flight (TOF) mode and a passive imaging mode enabled;

[0020] Figure 3C is a schematic diagram of an embodiment of Figure 2 is shown as having both a first TOF mode and a second TOF mode enabled, with passive imaging mode and ALPD mode disabled;

[0021] Figure 4 is a schematic diagram of an embodiment of a system according to the present disclosure;

[0022] Figure 5A is a schematic diagram of an embodiment of Figure 4 is shown as having both a passive imaging mode and an ALPD mode enabled, with TOF mode disabled;

[0023] Figure 5B is Figure 4 a schematic diagram of an embodiment of

[0024] Figure 5C is Figure 4 a schematic diagram of an embodiment of

[0025] Figure 6 is a schematic diagram showing single-threshold TOF measurements; and

[0026] Figure 7 is a series of diagrams showing the difference between single-threshold TOF measurements and multi-threshold (e.g., two) TOF measurements. DETAILED DESCRIPTION

[0027] Reference will now be made to the drawings wherein like numerals refer to like features throughout this disclosure. For purposes of explanation and illustration, and Figure 1 schematic diagrams of embodiments of systems according to the present disclosure are shown in Figures 2 to 7 and are generally labeled with reference numeral 100. Other embodiments and / or aspects of the present disclosure are shown in

[0028] Referring to Figure 1 , embodiments of system 100 can include one or more laser sources 101 (e.g., providing a Gaussian-shaped pulse) connected to one or more optics 103 to output a laser pulse 104 (e.g., through air) to a target 103 having a reflectivity and at a distance from laser source 101. System 100 can include an imaging device 105 connected to one or more optics 107 for receiving a reflected laser pulse 106. In certain embodiments, system 100 can be configured to operate with a target at any suitable distance and having any suitable resolution.

[0029] According to at least one aspect of the present disclosure, referring to Figure 2 and Figure 4 , a pixel system 200, 400 for an imaging device (e.g., imaging device 105) can include one or more pixels 201, 401 including a photodiode 202, 402 configured to generate a photocurrent at one or more threshold voltages (e.g., V th1 and / or V th2) pulse trigger assembly 203, 403 under detection of a pulse. The pixel system 200, 400 can include a timer system 205, 405 that forms part of and / or is connected with the one or more pixels 201, 401. The timer system 205, 405 can include one or more trigger switches 207a, 207b, 407a, 407b. The pulse trigger assembly 203, 403 can be configured to initiate the one or more trigger switches 207a, 207b, 407a, 407b in response to detection of a pulse at one or more thresholds.

[0030] The pixel system 100 can include a time of flight (TOF) module 209, 409 operatively connected to the one or more pixels 203, 403 and / or the timer system 205, 405 to determine a TOF based on output from the timer system 205, 405. The TOF module 209, 409 can include any suitable computer hardware and / or software configured to perform any suitable function (e.g., as disclosed herein).

[0031] The timer system 205, 405 can include at least one voltage ramp 211, 411 configured to allow the TOF module 209 to determine a TOF of a signal based on a voltage value of the at least one voltage ramp 211 that varies over time. The timer system 205, 405 can include one or more analog-to-digital converters (ADCs) 213a, 213b, 413a, 413b. The one or more ADCs 213a, 213b, 413a, 413b can be configured to receive voltage values from the at least one voltage ramp 211 when the one or more trigger switches 207a, 207b, 407a, 407b are initiated by a pulse.

[0032] For example, in certain embodiments, one or more pixels 203, 403 can include a voltage buffer 215, 415 connected to at least one voltage ramp 211, 411, a column buffer 217a, 217b, 417a, 417b connected to each of one or more ADCs 213a, 213b, 413a, 413b, and a ramp capacitor 219a, 219b, 419a, 419b connected to the column buffer 217a, 217b, 417a, 417b. In this regard, the one or more ADCs 213a, 213b, 413a, 413b can read the voltage on each ramp capacitor 219a, 219b, 419a, 419b and provide the ramp voltage to the TOF module 209, 409. This allows the TOF module 209, 409 to determine the TOF from the voltage difference between the starting voltage of the one or more voltage ramps 211, 411 and the ramp capacitor 219a, 219b, 419a, 419b voltage, which is indicative of the amount of time that has elapsed. In certain embodiments, a dedicated clock mechanism is not needed. In certain embodiments, the system 200, 400 can include multiple pixels 203, 403 and can, for example, utilize a single voltage ramp 211 and / or ADC (or set of ADCs) common to all pixels 203, 403.

[0033] For example, one or more trigger switches 207a, 207b, 407a, 407b can be disposed between each column buffer 217a, 217b, 417a, 417b and the voltage buffer 215, 415 connected to at least one voltage ramp 211, 411. Any other suitable location is contemplated herein.

[0034] The pulse trigger assembly 203, 403 can include a diode 219, 419 and an amplifier 221, 421 connected to the diode 219, 419 to receive a voltage therefrom. As understood by one of ordinary skill in the art, the diode 219, 419 can be biased, having a cathode voltage. The pulse trigger assembly 203, 403 can include one or more high pass filters 223a, 223b, 423 connected to the amplifier 221, 421, a comparator 225a, 225b, 425a, 425b for each of one or more threshold voltages, and a voltage threshold trigger line 227a, 227b, 427a, 427b connecting the respective comparator 225a, 225b, 425a, 425b to a respective trigger switch 207a, 207b, 407a, 407b of the one or more trigger switches 207a, 207b, 407a, 407b. As understood by one of ordinary skill in the art, the voltage threshold trigger line 227a, 227b, 427a, 427b can be connected to the respective trigger switch 207a, 207b, 407a, 407b to provide a voltage to the trigger switch 207a, 207b, 407a, 407b to trigger the trigger switch 207a, 207b, 407a, 407b to open or close. Figure 2As shown, high-pass filters 223a and 223b may be components shared with comparators 225a and 225b. In some embodiments, for example, as Figure 4 As shown, the high-pass filter 423 can be separated from the comparators 425a, 425b. Any suitable depiction of the components is contemplated herein. One or more trigger switches 207a, 207b can be any suitable type of switch configured to be controlled, for example, by a control voltage applied to their gates.

[0035] like Figure 2 As shown, pulse trigger assemblies 203, 403 may include one or more TOF mode switches 229a, 229b, which are configured to selectively allow operation of one or more trigger switches 207a, 207b. Figure 4 As shown, a single TOF mode switch 429 can be used to selectively allow ramp voltages to one or more trigger switches 407a, b.

[0036] like Figure 2 and Figure 4 As shown, one or more trigger switches 207a, 207b, 407a, 407b may include first trigger switches 207a, 407a and second trigger switches 207b, 407b, the first trigger switches 207a, 407a and the second trigger switches 207b, 407b are respectively connected to first comparators 225a, 425a and second comparators 225b, 425b, and are respectively configured to respond to a first threshold voltage of the pulse (e.g., V). th1 ) and the second threshold voltage of the pulse (e.g., V th2 Start-up is initiated under certain conditions. For example, when the voltage received from diodes 219 and 419 is equal to or higher than a first threshold (e.g., V). th1 When the first comparators 225a and 425a are in operation, they can output signals to lines 227a and 427a to close the first trigger switches 207a and 407a. The second trigger switches 207b and 407b and / or any other suitable number of trigger switches can operate in a similar manner.

[0037] like Figure 2 As shown, one or more TOF mode switches 229a, 229b may include a first TOF switch 229a and a second TOF switch 229b. In the first TOF mode (e.g., as shown in the diagram), Figure 3B As shown), the first TOF switch 229a can be activated, thereby activating the first trigger switch 207a. In the second TOF mode (e.g., as shown), Figure 3C As shown, the second TOF switch 229b can be activated, which in turn activates the second trigger switch 207b.

[0038] The pulse trigger assembly 203, 403 and / or pixel 201, 401 can include an asynchronous laser pulse detection (ALPD) system 231, 431 that is selectively connected to the first threshold trigger voltage line 227a, 427a, for example, through an ALPD mode switch 233 (as shown, for example, in Figure 2 ) or without a switch (as shown, for example, in Figure 4 ). For example, the ALPD system 231 can be connected between the first comparator 225a, 425a and the first TOF mode switch 229a (as shown, for example, in Figure 2 ). As shown, for example, in Figure 4 , it is contemplated that the ALPD system 231 can be connected in parallel with the threshold trigger voltage line 427a without a switch (as shown, for example, in Figure 2 ) located therebetween. Any other suitable location is contemplated herein.

[0039] As shown, for example, in Figure 2 , the first TOF mode switch 229a can be located between the first comparator 225a and the first trigger switch 207a. In certain embodiments, a second TOF mode switch can be connected between the amplifier 221 and the second comparator 225b. Any other suitable location is contemplated herein. In certain embodiments, the ALPD system 231, 431 can include components suitable for outputting a signal to a control module (e.g., TOF module 209) to indicate that a pulse was received but cannot provide data indicating a TOF. For example, the ALPD system 231 can include a pulse switch 231a that is activated by a voltage from the first comparator 225a to allow the voltage V dd to act on a capacitor 231b. A column buffer 231c can be connected to a suitable ADC (not shown) that can be connected to the control module for reading when the voltage in the capacitor 231b is at V dd . The control module can then determine that a pulse has occurred, for example, without determining a TOF.

[0040] In certain embodiments, the pixel 201, 401 can include a passive imaging system 233, 433 connected to the diode 219, 419. The passive imaging system 433 can include at least one passive imaging mode switch 235, 435 configured to allow passive imaging signals from the diode 219, 419 to be output to at least one of the one or more ADCs (e.g., the second ADC 213b, 413b) in a passive imaging mode (as shown, for example, in Figure 3A , Figure 5A and Figure 5B ). The pixel 201 can be configured such that the passive imaging mode can be activated with the first TOF mode (as shown, for example, in Figure 3B ), but not with the second TOF mode (as shown, for example, inFigure 3C and Figure 5C As shown). Figure 3A and Figure 5A As shown, ALPD mode can be activated together with passive imaging mode, or passive imaging mode can be activated independently (e.g., Figure 5B ).

[0041] like Figure 3C and Figure 5C As shown, one or more pixels 201 can be configured such that the first TOF mode and the second TOF mode can be activated together to provide multiple threshold readings, thereby allowing the TOF module to reduce or eliminate one or more errors. This paper envisions any other suitable combination of modes.

[0042] Figure 2 and Figure 4 The implementation scheme can be configured to function similarly. (And...) Figure 2 Compared to the implementation plan, Figure 4 Implementations may include different component arrangements, for example, to reduce the number of components. For example, in some implementations, one or more high-pass filters may include a single high-pass filter 423 operatively connected to each comparator 425a, 425b. A voltage ramp 411 may be connected in front of a voltage buffer 415 via a ramp switch (e.g., a TOF mode switch 429) to the passive imaging line 437. In some implementations, for example, as... Figure 4 As shown, the voltage ramp can be buffered into the pixel to reduce recoil noise, the buffer can be reused from a state that would otherwise be a passive imaging readout path, and the integration capacitor can be disconnected by turning on the passive mode switch. In some implementations, the voltage ramp can be disconnected and the integration capacitor connected to the buffer, rst2 can be enabled according to the ALPD readout, and rst1 can be kept disabled until a passive imaging readout occurs, and the ADC for TOF2_out can be disabled.

[0043] According to at least one aspect of the present disclosure, a pixel can include any suitable implementation of a pixel (e.g., pixel 201, 401) disclosed herein (e.g., as described above). For example, a pixel can include a pulse trigger component configured to detect a pulse at one or more threshold voltages, and a timer system connected to the pulse trigger component, the timer system including one or more trigger switches. The pulse trigger component can be configured to initiate the one or more trigger switches in response to detecting the pulse at the one or more thresholds. The timer system can include a voltage buffer configured to be connected to at least one voltage ramp, one or more column buffers configured to be connected to one or more respective analog-to-digital converters (ADCs), wherein the one or more trigger switches are disposed between each column buffer and the voltage buffer, and one or more ramp capacitors connected to each column buffer for receiving a voltage from the voltage ramp. The pulse trigger component can include a diode, an amplifier connected to the diode to receive a voltage therefrom, one or more high pass filters connected to the amplifier, a comparator for each of the one or more threshold voltages, a voltage threshold trigger line connecting a respective comparator to a respective trigger switch of the one or more trigger switches, and one or more TOF mode switches configured to selectively allow operation of the one or more trigger switches. The one or more trigger switches can include a first trigger switch and a second trigger switch connected to a first comparator and a second comparator, respectively, and configured to initiate at a first threshold voltage of the pulse and a second threshold voltage of the pulse, respectively.

[0044] According to at least one aspect of the present disclosure, a method can include determining a time-of-flight (TOF) of an output signal by first determining a single time value at which a pulse is received at a pixel at two or more threshold voltages to determine the pulse is received. The method can then include comparing an initial voltage to a ramp voltage at the single time value at which the pulse is received using a voltage ramp to determine a voltage difference, and then correlating the voltage difference to the TOF based on correlation data. The method can further include selecting between a TOF multi-threshold mode and a different operating mode.

[0045] In certain embodiments, the method can include receiving data points for each of a plurality of threshold values, and extrapolating a single time of flight value from the plurality of data points. For example, TOF module 209, 409 can perform this function (e.g., by linearly extrapolating / estimating time of flight from threshold crossing counts). The method can include associating a plurality of threshold crossings with a respective pulse signal. The method can include using the single time of flight to calculate TOF. The method can include resolving ambiguities, for example, by determining that a single time of flight match between two signals having the same time of flight within at least one error range determines that both signals have arrived, or that a simultaneous threshold crossing involves two or more non-synchronous signals. The method can include any other suitable method(s) and / or one or more portions thereof. Suitable methods disclosed herein can be stored on a computer readable medium and / or otherwise executable by a suitable computer.

[0046] According to the present disclosure, a laser pulse can be shined on a diode (e.g., a photosensitive element) and produce a voltage pulse. An amplifier can amplify this input signal according to a reference voltage (e.g., V ref ). The output from the amplifier can be sent to a first high pass filter and / or comparator to compare to a first threshold (e.g., V th1 , a predetermined set voltage). When the amplifier output is equal to or higher than the threshold, the comparator can output a signal to activate (e.g., close a flip-flop switch).

[0047] A voltage ramp can be used to time the transit of a signal. For example, when a laser signal is first emitted, the voltage ramp can be ramped at a fixed rate, for example, 200 mV per second. The TOF module can mark the starting voltage and / or time, which is then used to calculate TOF. When a pulse is received and a flip-flop switch is activated, the ramp voltage can be read and correlated to a time, resulting in a TOF.

[0048] Certain embodiments can also include a passive imaging system. In certain embodiments, a passive capacitor can obtain a voltage from a current mirror connected to a diode. An ADC can read the passive capacitor voltage. In certain embodiments, the passive imaging system can share one or more components (e.g., capacitor, buffer, and / or ADC) with the timing system, such that in passive mode, these components are used to read passive signals, and in TOF mode, these components are used to read ramp voltages when a pulse is detected.

[0049] A voltage ramp can be beneficial as some imaging devices can already be included on board. Ramping the voltage and holding at the voltage at the digitized trigger point is one implementation of just recording time. Additionally or alternatively, implementations can include one or more digital counters to count elapsed time and send out a digital signal directly. For example, it is contemplated that a counter or clock can be used, for example, but would be more power consuming and take up more space than using a voltage ramp.

[0050] Implementations provide systems that perform improved transit time measurements. Implementations allow for multi-threshold (e.g., at least dual-threshold) monitoring of a pulse signal. Implementations can include a replicated second path for a second threshold (e.g., V th1 ) that is different than the first threshold (e.g., V th2 ). Implementations can allow for independent and simultaneous measurements of a sample on multiple capacitors, allowing for two data points to be obtained. As shown in Figure 6 , a single threshold measurement can be made, but there will be an error that can or can not be acceptable or desirable.

[0051] As shown in Figure 7 , a comparison between a single threshold measurement and a dual threshold measurement shows the benefits of using a dual threshold measurement. As can be seen, with a dual threshold measurement (bottom of Figure 7 ), having two data points allows a TOF module (e.g., 209, 409) to extrapolate the data points to a line to allow for more accurate determination of signal type and transit time. For example, where a single threshold measurement incorrectly treats a contemporaneous signal of different amplitudes (e.g., the same signal reflected from two different materials at the same distance, Figure 7 , top left) as two different signals, a dual threshold system allows the intersection to form a line that intersects the time axis, indicating that the signal arrived at the same time regardless of amplitude (which indicates a single signal reflected from multiple surfaces, e.g., Figure 7 , bottom left). Where a single threshold measurement incorrectly treats multiple signals arriving at different times as a single signal (e.g., Figure 7 , top right), a dual threshold measurement correctly separates the two individual signals to two different times of arrival. Using the times generated using the multi-threshold approach, a TOF module can extrapolate a more accurate time of arrival and use that value to calculate a TOF (e.g., for use in ranging a target).

[0052] For example, embodiments can detect a pulse twice within a single pulse and reduce time / depth ambiguity caused by signal amplitude. For example, certain embodiments add a new mode for TOF detection that utilizes few additional transistors. The new mode allows for two samples of a single laser pulse signal waveform and allows for simultaneous readout and appropriate processing of the simultaneous readouts. Embodiments can eliminate or mitigate motion artifacts and reduce depth ambiguity due to other reasons that cause signal amplitude differences, such as target reflectivity differences, backscatter, etc. Embodiments can still support TOF signal calibration through the TOF imaging path. Embodiments of the gain / buffer component can have adjustable gain and bandwidth through bias current adjustment, the corner frequency of the high pass filter can be voltage adjustable, the current mirror current gain / attenuation can be adjustable. In certain embodiments, during TOF mode, the input PMOS TX can be connected to V dd or a separate voltage to keep the DI behavior.

[0053] For example, certain pixel / readout block diagrams are shown herein. Any components not described herein and not shown in the drawings can be readily understood to have functionality as understood by one of ordinary skill in the art at least in light of the present disclosure. Embodiments can utilize active pulse detection as well as passive imaging to achieve improved fidelity and direct time of flight (TOF) imaging. Embodiments allow for front edge pulse detection, whereby range / reflectivity ambiguity challenges can be mitigated.

[0054] As will be appreciated by those of skill in the art, aspects of the present disclosure can be embodied as a system, method, or computer program product. Accordingly, aspects of the present disclosure can take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that can all generally be referred to herein as a "circuit," "module" or "system." A "circuit," "module" or "system" can include one or more portions of one or more separate physical hardware and / or software components that can together perform the disclosed functions of the "circuit," "module" or "system," or the "circuit," "module" or "system" can be a single self-contained unit (e.g., of hardware and / or software). Further, aspects of the present disclosure can take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

[0055] Any combination of one or more computer readable medium can be utilized. The computer readable medium can be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium can be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0056] A computer readable signal medium can include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium can be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0057] Program code embodied on a computer readable medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0058] Computer program code for carrying out operations of aspects of the present disclosure can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++, or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0059] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0060] These computer program instructions can also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0061] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0062] Those of ordinary skill in the art understand that any numerical values disclosed herein can be exact values or can be values within a range. In addition, any approximating language (e.g., “about,” “approximately,” “around,” etc.) used in the present disclosure can mean a specified value within a range. For example, in certain embodiments, a range can be within (e.g., known tolerance limits or error ranges) 20%, or 10%, or 5%, or 2%, or any other suitable percentage or number as understood by one of skill in the art.

[0063] The articles “a,” “an,” and “the” as used in the present document and in the appended claims are each intended to mean one or more than one (i.e., at least one) of the referenced item. By way of example, “an element” means one element or more than one element.

[0064] As used herein in the specification and claims, the phrase “and / or” should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present (whether associated with “and / or” or separated by a comma in the code) together but can, in some instances, be present apart from one another. As used herein in the specification and claims, both the singular and the plural include the concepts of “at least one of” or “one or more.” As used herein in the specification and claims, the phrase “at least one of’ followed by a list using “and / or” should be interpreted to mean “at least one of the elements but not including others of the elements following “and / or” in this fashion. As used herein in the specification and claims, both the singular and the plural include the concepts of “one or more” of the elements so conjoined, i.e., that a list of elements can include one element or any combination of two or more of the elements. As used herein in the specification and claims, the phrase “at least one of’ followed by a list using “and / or” should be interpreted to mean “at least one of the elements but not including others of the elements following “and / or” in this fashion.

[0065] As used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms such as “only one of’ or “exactly one of’ or when used in the claims, “consisting of’ will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as set forth by the Federal Circuit in

[0066] As will be understood by those of ordinary skill in the art in light of the disclosure, any suitable combination(s) and / or any suitable portion(s) thereof of any of the disclosed embodiments are contemplated herein.

[0067] Embodiments of the disclosure, as described above and as shown in the drawings, provide improvements in the fields to which they belong. While this disclosure includes mention of certain embodiments, those of ordinary skill in the art will readily understand that changes and / or modifications can be made to this disclosure without departing from its spirit and scope.

Claims

1. A pixel system for an imaging device, comprising: one or more pixels, at least one of the one or more pixels including a pulse trigger component configured to detect a pulse at two or more threshold voltages; a timer system forming a part of and / or connected with the one or more pixels, the timer system including one or more trigger switches, wherein the pulse trigger component is configured to initiate the one or more trigger switches in response to detecting the pulse at the two or more threshold voltages; and a time of flight (TOF) module operatively connected to the one or more pixels and / or the timer system and configured to determine a TOF based on an output from the timer system.

2. The pixel system of claim 1, wherein the timer system includes at least one voltage ramp configured to allow the TOF module to determine a TOF of a signal based on a voltage value of the at least one voltage ramp as a function of time.

3. The pixel system of claim 2, wherein the timer system includes one or more analog-to-digital converters (ADCs), wherein the one or more ADCs are configured to receive the voltage value from the at least one voltage ramp when the one or more trigger switches are initiated by the pulse.

4. The pixel system of claim 3, wherein the one or more pixels include a voltage buffer connected to the at least one voltage ramp, a column buffer connected to each of the one or more ADCs, and a ramp capacitor connected to the column buffer, wherein the one or more trigger switches are disposed between each column buffer and the voltage buffer connected to the at least one voltage ramp. a diode; 5. The pixel system of claim 4, wherein the pulse trigger component comprises: an amplifier connected to the diode and configured to receive a voltage therefrom; one or more high pass filters connected to the amplifier; a comparator for each of the two or more threshold voltages; and a voltage threshold trigger line connecting a respective comparator to a respective trigger switch of the one or more trigger switches.

6. The pixel system of claim 5, wherein the pulse trigger component includes one or more TOF mode switches configured to selectively allow the one or more trigger switches to be operated.

7. The pixel system of claim 6, wherein the one or more trigger switches include a first trigger switch and a second trigger switch, the first trigger switch and the second trigger switch being connected to a first comparator and a second comparator, respectively, and configured to be initiated at a first threshold voltage of the pulse and a second threshold voltage of the pulse, respectively.

8. The pixel system of claim 7, wherein the one or more TOF mode switches include a first TOF switch and a second TOF switch, wherein in a first TOF mode, the first TOF switch is activated such that the first trigger switch can be activated, and wherein in a second TOF mode, the second TOF switch is activated such that the second trigger switch can be activated.

9. The pixel system of claim 8, wherein the pulse trigger component includes an asynchronous laser pulse detection (ALPD) system, the ALPD system being selectively connected to the voltage threshold trigger line via an ALPD mode switch.

10. The pixel system of claim 9, wherein the ALPD system is connected between the first comparator and the first TOF switch, wherein the first TOF switch is located between the first comparator and the first trigger switch.

11. The pixel system of claim 10, wherein the second TOF switch is connected between the amplifier and the second comparator.

12. The pixel system of claim 10, wherein the one or more pixels include a passive imaging system connected to the diode, wherein the passive imaging system includes at least one passive imaging mode switch, the at least one passive imaging mode switch being configured to allow a passive imaging signal from the diode to be output to at least one of the one or more ADCs in a passive imaging mode.

13. The pixel system of claim 12, wherein one or more pixels are configured such that the passive imaging mode can be activated with the first TOF mode but not with the second TOF mode, and wherein the ALPD mode can be activated with the passive imaging mode.

14. The pixel system of claim 8, wherein one or more pixels are configured such that the first TOF mode and the second TOF mode can be activated together to provide multiple threshold readings, thereby allowing the TOF module to reduce or eliminate one or more errors.

15. The pixel system of claim 13, wherein the one or more high-pass filters comprise a single high-pass filter operatively connected to each comparator.

16. The pixel system of claim 15, wherein the at least one voltage ramp is connected to the passive imaging line in front of the voltage buffer via a ramp switch.

17. A pixel comprising: A pulse trigger assembly configured to detect a pulse at two or more threshold voltages; as well as A timer system connected to the pulse trigger assembly, the timer system including one or more trigger switches, wherein the pulse trigger assembly is configured to activate the one or more trigger switches in response to detecting the pulse at the two or more threshold voltages, wherein the timer system includes: A voltage buffer, the voltage buffer being configured to be connected to at least one voltage ramp; One or more column buffers configured to be connected to one or more corresponding analog-to-digital converters (ADCs), wherein one or more trigger switches are disposed between each column buffer and the voltage buffer; and One or more ramp capacitors are connected to each column buffer and configured to receive voltage from the at least one voltage ramp; The pulse trigger assembly includes: diode; An amplifier, which is connected to the diode and configured to receive a voltage therefrom; One or more high-pass filters, the one or more high-pass filters being connected to the amplifier; A comparator for each of the two or more threshold voltages; A voltage threshold trigger line, wherein the voltage threshold trigger line connects a corresponding comparator to a corresponding trigger switch among the one or more trigger switches; and One or more transit time-of-flight (TOF) mode switches are configured to selectively allow operation of one or more trigger switches, wherein the one or more trigger switches include a first trigger switch and a second trigger switch, the first trigger switch and the second trigger switch are respectively connected to a first comparator and a second comparator, and are respectively configured to activate at a first threshold voltage of the pulse and a second threshold voltage of the pulse.

18. The pixel of claim 17, wherein the one or more TOF mode switches comprise a first TOF switch and a second TOF switch, wherein, In the first TOF mode, the first TOF switch is activated, enabling the first trigger switch to be activated. In the second TOF mode, the second TOF switch is activated, enabling the second trigger switch to be activated.

19. A method for determining the transit time (TOF) of a signal output to a pixel system for an imaging apparatus, the method comprising: First, by detecting pulses at two or more threshold voltages using the pulse trigger components of the pixel in the pixel system, a single time value of the signal pulse received at the pixel system is determined. Then, a voltage ramp with a voltage value that varies over time is used to determine the voltage difference by comparing the initial voltage of the voltage ramp when the signal is first transmitted with the ramp voltage of the voltage ramp when the pulse is received at a single time value. as well as Then, the voltage difference is associated with the TOF based on the associated data.

20. The method of claim 19, further comprising: Choose between TOF multi-threshold mode and different operating modes.

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