Sensor device and method for operating a sensor device

Abstract

A sensor device (10) comprises a pixel array (1011) having a plurality of pixels (51) each being configured to receive light and to perform photoelectric conversion to generate an electrical signal indicating the intensity of the received light, a plurality of event detecting sections (52) that are configured to receive the electrical signals from each of the plurality of pixels (51) and to generate event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel (51) above an event threshold, and a selection section (100) that is configured to receive the electrical signals generated by a group (511) of adjacent pixels (51), to determine from the electrical signals at which pixel (51) of the group (511) the largest intensity has been received, and to enable generation of event data for the pixel (51) of the group that did receive the largest intensity while disabling generation of event data for the other pixels (51) of the group.

Description

[0001] SENSOR DEVICE AND METHOD FOR OPERATING A SENSOR DEVICE

[0002] FIELD OF THE INVENTION

[0003] The present technology relates to a sensor device, and a method for operating a sensor device, in particular, to a sensor device and a method for operating a sensor device that allows an improved generation of event data.

[0004] BACKGROUND

[0005] Presently, sensor data obtained in dynamic / event vision sensors, DVS / EVS, are used to obtain temporally highly resolved image streams by generating event data whenever the intensity received at a pixel changes by more than a predetermined amount. Although temporally highly resolved, event data might be noisy, i.e. generation of event data might be triggered by noise. Further, intensity changes may affect several pixels, leading to spatial blurring. Thus, the spatial resolution of DVS / EVS may not be equal to the pixel resolution of the DVS / EVS. Therefore, improved sensor devices and methods for operating these sensor devices are desirable that mitigate this problem.

[0006] SUMMARY OF INVENTION

[0007] To this end, a sensor device is provided that comprises a pixel array having a plurality of pixels each being configured to receive light and to perform photoelectric conversion to generate an electrical signal indicating the intensity of the received light, a plurality of event detecting sections that are configured to receive the electrical signals from each of the plurality of pixels and to generate event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel above an event threshold, and a selection section that is configured to receive the electrical signals generated by a group of adjacent pixels, to determine from the electrical signals at which pixel of the group the largest intensity has been received, and to enable generation of event data for the pixel of the group that did receive the largest intensity while disabling generation of event data for the other pixels of the group.

[0008] Further, a method for operating such a sensor device is provided, the method comprising: at each of the plurality of pixels, receiving light to perform photoelectric conversion and generating an electrical signal indicating the intensity of the received light; at the plurality of event detecting sections, receiving the electrical signals from each of the plurality of pixels and generating event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel above an event threshold; and at the selection section, receiving the electrical signals generated by a group of adjacent pixels, determining from the electrical signals at which pixel of the group the largest intensity has been received, and enabling generation of event data for the pixel of the group that did receive the largest intensity while disabling generation of event data for the other pixels of the group.

[0009] In the above, the usual concept of an event-based vision sensor to generate events / event data for each pixel, if the intensity of light that has been received at said pixel increases by more than a predetermined threshold is refined such that amongst a group of pixels only the pixel that receives the largest intensity is allowed to generate event data. The other pixels of the group are silenced, i.e. no event detection is carried out in these pixels although the received intensities might change by more than the predetermined threshold. Accordingly, if in the group of pixels several events at different pixels occur within a predetermined time interval, only the event caused by the largest intensity is detected. This reduces noise around the corresponding pixel. Moreover, blurring caused by light that spreads to different adjacent pixels is reduced, since from these pixels only a single event is generated. Accordingly, the noise and blurring can be reduced, which allows increasing the spatial resolution obtainable by the sensor device.

[0010] BRIEF DESCRIPTION OF DRAWINGS

[0011] Fig. 1 is a schematic diagram of a sensor device.

[0012] Fig. 2 is a schematic block diagram of a sensor section.

[0013] Fig. 3 is a schematic block diagram of a pixel array section.

[0014] Fig. 4 is a schematic circuit diagram of a pixel block.

[0015] Fig. 5 is a schematic block diagram illustrating of an event detecting section.

[0016] Fig. 6 is a schematic circuit diagram of a current-voltage converting section.

[0017] Fig. 7 is a schematic circuit diagram of a subtraction section and a quantization section.

[0018] Fig. 8 is a schematic diagram of a frame data generation method based on event data.

[0019] Fig. 9 is a schematic block diagram of another quantization section.

[0020] Fig. 10 is a schematic diagram of another event detecting section.

[0021] Fig. 11 is a schematic block diagram of another pixel array section.

[0022] Fig. 12 is a schematic circuit diagram of another pixel block.

[0023] Fig. 13 is a schematic block diagram of a scan-type sensor device.

[0024] Fig. 14 is a schematic block diagram of a sensor device.

[0025] Figs. 15A and 15B are schematic illustrations of the effect obtainable with the sensor device.

[0026] Fig. 16 is another schematic illustration of a sensor device. Fig. 17 is a schematic illustration of a winner-take-all circuit.

[0027] Fig. 18 is a schematic illustration of a current mirror.

[0028] Fig. 19 is a schematic illustration of enabling and disabling event generation.

[0029] Fig. 20 is another schematic illustration of enabling and disabling event generation.

[0030] Fig. 21 is a schematic process flow of a method for operating a sensor device.

[0031] Fig. 22 is a schematic block diagram of a vehicle control system.

[0032] Fig. 23 is a diagram of assistance in explaining an example of installation positions of an outside-vehicle information detecting section and an imaging section.

[0033] Figs. 24A and 24B are schematic illustrations of a mobile device and a head mounted display comprising a sensor device.

[0034] DETAILED DESCRIPTION

[0035] The present disclosure is directed to mitigating problems related to the generation and processing of the data of event based / dynamic vision sensors, EVS / DVS. The present disclosure is based on the operation of conventional EVS / DVS. Thus, at first a possible implementation of an EVS / DVS will be described. This is of course purely exemplary. It is to be understood that EVSs / DVSs could also be implemented differently.

[0036] Fig. 1 is a diagram illustrating a configuration example of a sensor device 10, which is in the example of Fig. 1 constituted by a sensor chip.

[0037] The sensor device 10 is a single-chip semiconductor chip and includes a sensor die (substrate) 11, which serves as a plurality of dies (substrates), and a logic die 12 that are stacked. Note that, the sensor device 10 can also include only a single die or three or more stacked dies.

[0038] In the sensor device 10 of Fig. 1, the sensor die 11 includes (a circuit serving as) a sensor section 21, and the logic die 12 includes a logic section 22. Note that, the sensor section 21 can be partly formed on the logic die 12. Further, the logic section 22 can be partly formed on the sensor die 11.

[0039] The sensor section 21 includes pixels configured to perform photoelectric conversion on incident light to generate electrical signals, and generates event data indicating the occurrence of events that are changes in the electrical signal of the pixels. The sensor section 21 supplies the event data to the logic section 22. That is, the sensor section 21 performs imaging of performing, in the pixels, photoelectric conversion on incident light to generate electrical signals, similarly to a synchronous image sensor, for example. The sensor section 21, however, generates event data indicating the occurrence of events that are changes in the electrical signal of the pixels instead of generating image data in a frame format (frame data). The sensor section 21 outputs, to the logic section 22, the event data obtained by the imaging.

[0040] Here, the synchronous image sensor is an image sensor configured to perform imaging in synchronization with a vertical synchronization signal and output frame data that is image data in a frame format. The sensor section 21 can be regarded as asynchronous (an asynchronous image sensor) in contrast to the synchronous image sensor, since the sensor section 21 does not operate in synchronization with a vertical synchronization signal when outputting event data. In particular, the sensor section 21 can output event data with a temporal precision of 10'6s.

[0041] Note that, the sensor section 21 may generate and output, other than event data, frame data, similarly to the synchronous image sensor. In addition, the sensor section 21 can output, together with event data, electrical signals of pixels in which events have occurred, as pixel signals that are pixel values of the pixels in frame data.

[0042] The logic section 22 controls the sensor section 21 as needed. Further, the logic section 22 performs various types of data processing, such as data processing of generating frame data on the basis of event data from the sensor section 21 and image processing on frame data from the sensor section 21 or frame data generated on the basis of the event data from the sensor section 21, and outputs data processing results obtained by performing the various types of data processing on the event data and the frame data. The logic section 22 may implement the functions of a control unit as described below.

[0043] Fig. 2 is a block diagram illustrating a configuration example of the sensor section 21 of Fig. 1.

[0044] The sensor section 21 includes a pixel array section 31, a driving section 32, an arbiter 33, an AD (Analog to Digital) conversion section 34, and an output section 35.

[0045] The pixel array section 31 includes a plurality of pixels 51 (Fig. 3) arrayed in a two-dimensional lattice pattern. The pixel array section 31 detects, in a case where a change larger than a predetermined threshold (including a change equal to or larger than the threshold as needed) has occurred in (a voltage corresponding to) a photocurrent that is an electrical signal generated by photoelectric conversion in the pixel 51, the change in the photocurrent as an event. In a case of detecting an event, the pixel array section 31 outputs, to the arbiter 33, a request for requesting the output of event data indicating the occurrence of the event. Then, in a case of receiving a response indicating event data output permission from the arbiter 33, the pixel array section 31 outputs the event data to the driving section 32 and the output section 35. In addition, the pixel array section 31 may output an electrical signal of the pixel 51 in which the event has been detected to the AD conversion section 34.

[0046] The driving section 32 supplies control signals to the pixel array section 31 to drive the pixel array section 31. For example, the driving section 32 drives the pixel 51 regarding which the pixel array section 31 has output event data, so that the pixel 51 in question supplies (outputs) a pixel signal to the AD conversion section 34.

[0047] The arbiter 33 arbitrates the requests for requesting the output of event data from the pixel array section 31, and returns responses indicating event data output permission or prohibition to the pixel array section 31.

[0048] The AD conversion section 34 includes, for example, a single-slope ADC (AD converter) (not illustrated) in each column of pixel blocks 41 (Fig. 3) described later, for example. The AD conversion section 34 performs, with the ADC in each column, AD conversion on pixel signals of the pixels 51 of the pixel blocks 41 in the column, and supplies the resultant to the output section 35. Note that, the AD conversion section 34 can perform CDS (Correlated Double Sampling) together with pixel signal AD conversion.

[0049] The output section 35 performs necessary processing on the pixel signals from the AD conversion section 34 and the event data from the pixel array section 31 and supplies the resultant to the logic section 22 (Fig. 1).

[0050] Here, a change in the photocurrent generated in the pixel 51 can be recognized as a change in the amount of light entering the pixel 51, so that it can also be said that an event is a change in light amount (a change in light amount larger than the threshold) in the pixel 51.

[0051] Event data indicating the occurrence of an event at least includes location information (coordinates or the like) indicating the location of a pixel block in which a change in light amount, which is the event, has occurred. Besides, the event data can also include the polarity (positive or negative) of the change in light amount.

[0052] With regard to the series of event data that is output from the pixel array section 31 at timings at which events have occurred, it can be said that, as long as the event data interval is the same as the event occurrence interval, the event data implicitly includes time point information indicating (relative) time points at which the events have occurred. However, for example, when the event data is stored in a memory and the event data interval is no longer the same as the event occurrence interval, the time point information implicitly included in the event data is lost. Thus, the output section 35 includes, in event data, time point information indicating (relative) time points at which events have occurred, such as timestamps, before the event data interval is changed from the event occurrence interval. The processing of including time point information in event data can be performed in any block other than the output section 35 as long as the processing is performed before time point information implicitly included in event data is lost.

[0053] Fig. 3 is a block diagram illustrating a configuration example of the pixel array section 31 of Fig. 2.

[0054] The pixel array section 31 includes the plurality of pixel blocks 41. The pixel block 41 includes the IxJ pixels 51 that are one or more pixels arrayed in I rows and J columns (I and J are integers), an event detecting section 52, and a pixel signal generating section 53. The one or more pixels 51 in the pixel block 41 share the event detecting section 52 and the pixel signal generating section 53. Further, in each column of the pixel blocks 41, a VSL (Vertical Signal Line) for connecting the pixel blocks 41 to the ADC of the AD conversion section 34 is wired.

[0055] The pixel 51 receives light incident from an object and performs photoelectric conversion to generate a photocurrent serving as an electrical signal. The pixel 51 supplies the photocurrent to the event detecting section 52 under the control of the driving section 32.

[0056] The event detecting section 52 detects, as an event, a change larger than the predetermined threshold in photocurrent from each of the pixels 51, under the control of the driving section 32. In a case of detecting an event, the event detecting section 52 supplies, to the arbiter 33 (Fig. 2), a request for requesting the output of event data indicating the occurrence of the event. Then, when receiving a response indicating event data output permission to the request from the arbiter 33, the event detecting section 52 outputs the event data to the driving section 32 and the output section 35.

[0057] The pixel signal generating section 53 generates, in the case where the event detecting section 52 has detected an event, a voltage corresponding to a photocurrent from the pixel 51 as a pixel signal, and supplies the voltage to the AD conversion section 34 through the VSL, under the control of the driving section 32.

[0058] Here, detecting a change larger than the predetermined threshold in photocurrent as an event can also be recognized as detecting, as an event, absence of change larger than the predetermined threshold in photocurrent. The pixel signal generating section 53 can generate a pixel signal in the case where absence of change larger than the predetermined threshold in photocurrent has been detected as an event as well as in the case where a change larger than the predetermined threshold in photocurrent has been detected as an event.

[0059] Fig. 4 is a circuit diagram illustrating a configuration example of the pixel block 41.

[0060] The pixel block 41 includes, as described with reference to Fig. 3, the pixels 51, the event detecting section 52, and the pixel signal generating section 53.

[0061] The pixel 51 includes a photoelectric conversion element 61 and transfer transistors 62 and 63.

[0062] The photoelectric conversion element 61 includes, for example, a PD (Photodiode). The photoelectric conversion element 61 receives incident light and performs photoelectric conversion to generate charges.

[0063] The transfer transistor 62 includes, for example, an N (Negative)-type MOS (Metal-Oxide- Semiconductor) FET (Field Effect Transistor). The transfer transistor 62 of the n-th pixel 51 of the IxJ pixels 51 in the pixel block 41 is turned on or off in response to a control signal OFGn supplied from the driving section 32 (Fig. 2). When the transfer transistor 62 is turned on, charges generated in the photoelectric conversion element 61 are transferred (supplied) to the event detecting section 52, as a photocurrent.

[0064] The transfer transistor 63 includes, for example, an N-type MOSFET. The transfer transistor 63 of the n- th pixel 51 of the IxJ pixels 51 in the pixel block 41 is turned on or off in response to a control signal TRGn supplied from the driving section 32. When the transfer transistor 63 is turned on, charges generated in the photoelectric conversion element 61 are transferred to an FD 74 of the pixel signal generating section 53.

[0065] The IxJ pixels 51 in the pixel block 41 are connected to the event detecting section 52 of the pixel block 41 through nodes 60. Thus, photocurrents generated in (the photoelectric conversion elements 61 of) the pixels 51 are supplied to the event detecting section 52 through the nodes 60. As a result, the event detecting section 52 receives the sum of photocurrents from all the pixels 51 in the pixel block 41. Thus, the event detecting section 52 detects, as an event, a change in sum of photocurrents supplied from the IxJ pixels 51 in the pixel block 41.

[0066] The pixel signal generating section 53 includes a reset transistor 71, an amplification transistor 72, a selection transistor 73, and the FD (Floating Diffusion) 74.

[0067] The reset transistor 71, the amplification transistor 72, and the selection transistor 73 include, for example, N-type MOSFETs.

[0068] The reset transistor 71 is turned on or off in response to a control signal RST supplied from the driving section 32 (Fig. 2). When the reset transistor 71 is turned on, the FD 74 is connected to a power supply VDD, and charges accumulated in the FD 74 are thus discharged to the power supply VDD. With this, the FD 74 is reset.

[0069] The amplification transistor 72 has a gate connected to the FD 74, a drain connected to the power supply VDD, and a source connected to the VSL through the selection transistor 73. The amplification transistor 72 is a source follower and outputs a voltage (electrical signal) corresponding to the voltage of the FD 74 supplied to the gate to the VSL through the selection transistor 73.

[0070] The selection transistor 73 is turned on or off in response to a control signal SEL supplied from the driving section 32. When the selection transistor 73 is turned on, a voltage corresponding to the voltage of the FD 74 from the amplification transistor 72 is output to the VSL.

[0071] The FD 74 accumulates charges transferred from the photoelectric conversion elements 61 of the pixels 51 through the transfer transistors 63, and converts the charges to voltages.

[0072] With regard to the pixels 51 and the pixel signal generating section 53, which are configured as described above, the driving section 32 turns on the transfer transistors 62 with control signals OFGn, so that the transfer transistors 62 supply, to the event detecting section 52, photocurrents based on charges generated in the photoelectric conversion elements 61 of the pixels 51. With this, the event detecting section 52 receives a current that is the sum of the photocurrents from all the pixels 51 in the pixel block 41, which might also be only a single pixel.

[0073] When the event detecting section 52 detects, as an event, a change in photocurrent (sum of photocurrents) in the pixel block 41, the driving section 32 turns off the transfer transistors 62 of all the pixels 51 in the pixel block 41, to thereby stop the supply of the photocurrents to the event detecting section 52. Then, the driving section 32 sequentially turns on, with the control signals TRGn, the transfer transistors 63 of the pixels 51 in the pixel block 41 in which the event has been detected, so that the transfer transistors 63 transfers charges generated in the photoelectric conversion elements 61 to the FD 74. The FD 74 accumulates the charges transferred from (the photoelectric conversion elements 61 of) the pixels 51. Voltages corresponding to the charges accumulated in the FD 74 are output to the VSL, as pixel signals of the pixels 51, through the amplification transistor 72 and the selection transistor 73.

[0074] As described above, in the sensor section 21 (Fig. 2), only pixel signals of the pixels 51 in the pixel block 41 in which an event has been detected are sequentially output to the VSL. The pixel signals output to the VSL are supplied to the AD conversion section 34 to be subjected to AD conversion.

[0075] Here, in the pixels 51 in the pixel block 41, the transfer transistors 63 can be turned on not sequentially but simultaneously. In this case, the sum of pixel signals of all the pixels 51 in the pixel block 41 can be output.

[0076] In the pixel array section 31 of Fig. 3, the pixel block 41 includes one or more pixels 51, and the one or more pixels 51 share the event detecting section 52 and the pixel signal generating section 53. Thus, in the case where the pixel block 41 includes a plurality of pixels 51, the numbers of the event detecting sections 52 and the pixel signal generating sections 53 can be reduced as compared to a case where the event detecting section 52 and the pixel signal generating section 53 are provided for each of the pixels 51, with the result that the scale of the pixel array section 31 can be reduced.

[0077] Note that, in the case where the pixel block 41 includes a plurality of pixels 51, the event detecting section 52 can be provided for each of the pixels 51. In the case where the plurality of pixels 51 in the pixel block 41 share the event detecting section 52, events are detected in units of the pixel blocks 41. In the case where the event detecting section 52 is provided for each of the pixels 51, however, events can be detected in units of the pixels 51.

[0078] Yet, even in the case where the plurality of pixels 51 in the pixel block 41 share the single event detecting section 52, events can be detected in units of the pixels 51 when the transfer transistors 62 of the plurality of pixels 51 are temporarily turned on in a time-division manner.

[0079] Further, in a case where there is no need to output pixel signals, the pixel block 41 can be formed without the pixel signal generating section 53. In the case where the pixel block 41 is formed without the pixel signal generating section 53, the sensor section 21 can be formed without the AD conversion section 34 and the transfer transistors 63. In this case, the scale of the sensor section 21 can be reduced. The sensor will then output the address of the pixel (block) in which the event occurred, if necessary with a time stamp.

[0080] Fig. 5 is a block diagram illustrating a configuration example of the event detecting section 52 of Fig. 3.

[0081] The event detecting section 52 includes a current-voltage converting section 81, a buffer 82, a subtraction section 83, a quantization section 84, and a transfer section 85.

[0082] The current-voltage converting section 81 converts (a sum of) photocurrents from the pixels 51 to voltages corresponding to the logarithms of the photocurrents (hereinafter also referred to as a "photovoltage") and supplies the voltages to the buffer 82.

[0083] The buffer 82 buffers photovoltages from the current-voltage converting section 81 and supplies the resultant to the subtraction section 83.

[0084] The subtraction section 83 calculates, at a timing instructed by a row driving signal that is a control signal from the driving section 32, a difference between the current photovoltage and a photovoltage at a timing slightly shifted from the current time, and supplies a difference signal corresponding to the difference to the quantization section 84.

[0085] The quantization section 84 quantizes difference signals from the subtraction section 83 to digital signals and supplies the quantized values of the difference signals to the transfer section 85 as event data.

[0086] The transfer section 85 transfers (outputs), on the basis of event data from the quantization section 84, the event data to the output section 35. That is, the transfer section 85 supplies a request for requesting the output of the event data to the arbiter 33. Then, when receiving a response indicating event data output permission to the request from the arbiter 33, the transfer section 85 outputs the event data to the output section 35.

[0087] Fig. 6 is a circuit diagram illustrating a configuration example of the current-voltage converting section 81 of Fig. 5.

[0088] The current-voltage converting section 81 includes transistors 91 to 93. As the transistors 91 and 93, for example, N-type MOSFETs can be employed. As the transistor 92, for example, a P-type MOSFET can be employed.

[0089] The transistor 91 has a source connected to the gate of the transistor 93, and a photocurrent is supplied from the pixel 51 to the connecting point between the source of the transistor 91 and the gate of the transistor 93. The transistor 91 has a drain connected to the power supply VDD and a gate connected to the drain of the transistor 93. The transistor 92 has a source connected to the power supply VDD and a drain connected to the connecting point between the gate of the transistor 91 and the drain of the transistor 93. A predetermined bias voltage Vbias is applied to the gate of the transistor 92. With the bias voltage Vbias, the transistor 92 is turned on or off, and the operation of the current-voltage converting section 81 is turned on or off depending on whether the transistor 92 is turned on or off.

[0090] The source of the transistor 93 is grounded.

[0091] In the current-voltage converting section 81, the transistor 91 has the drain connected on the power supply VDD side. The source of the transistor 91 is connected to the pixels 51 (Fig. 4), so that photocurrents based on charges generated in the photoelectric conversion elements 61 of the pixels 51 flow through the transistor 91 (from the drain to the source). The transistor 91 operates in a subthreshold region, and at the gate of the transistor 91, photovoltages corresponding to the logarithms of the photocurrents flowing through the transistor 91 are generated. As described above, in the current-voltage converting section 81, the transistor 91 converts photocurrents from the pixels 51 to photovoltages corresponding to the logarithms of the photocurrents.

[0092] In the current-voltage converting section 81, the transistor 91 has the gate connected to the connecting point between the drain of the transistor 92 and the drain of the transistor 93, and the photovoltages are output from the connecting point in question.

[0093] Fig. 7 is a circuit diagram illustrating configuration examples of the subtraction section 83 and the quantization section 84 of Fig. 5.

[0094] The subtraction section 83 includes a capacitor 101, an operational amplifier 102, a capacitor 103, and a switch 104. The quantization section 84 includes a comparator 111.

[0095] The capacitor 101 has one end connected to the output terminal of the buffer 82 (Fig. 5) and the other end connected to the input terminal (inverting input terminal) of the operational amplifier 102. Thus, photovoltages are input to the input terminal of the operational amplifier 102 through the capacitor 101.

[0096] The operational amplifier 102 has an output terminal connected to the non-inverting input terminal (+) of the comparator 111.

[0097] The capacitor 103 has one end connected to the input terminal of the operational amplifier 102 and the other end connected to the output terminal of the operational amplifier 102.

[0098] The switch 104 is connected to the capacitor 103 to switch the connections between the ends of the capacitor 103. The switch 104 is turned on or off in response to a row driving signal that is a control signal from the driving section 32, to thereby switch the connections between the ends of the capacitor A photovoltage on the buffer 82 (Fig. 5) side of the capacitor 101 when the switch 104 is on is denoted by Vinit, and the capacitance (electrostatic capacitance) of the capacitor 101 is denoted by Cl. The input terminal of the operational amplifier 102 serves as a virtual ground terminal, and a charge Qinit that is accumulated in the capacitor 101 in the case where the switch 104 is on is expressed by Expression (1).

[0099] Qinit = Cl x Vinit (1)

[0100] Further, in the case where the switch 104 is on, the connection between the ends of the capacitor 103 is cut (short-circuited), so that no charge is accumulated in the capacitor 103.

[0101] When a photovoltage on the buffer 82 (Fig. 5) side of the capacitor 101 in the case where the switch 104 has thereafter been turned off is denoted by Vafter, a charge Qafter that is accumulated in the capacitor 101 in the case where the switch 104 is off is expressed by Expression (2).

[0102] Qafter = Cl x Vafter (2)

[0103] When the capacitance of the capacitor 103 is denoted by C2 and the output voltage of the operational amplifier 102 is denoted by Vout, a charge Q2 that is accumulated in the capacitor 103 is expressed by Expression (3).

[0104] Q2 = -C2 x Vout (3)

[0105] Since the total amount of charges in the capacitors 101 and 103 does not change before and after the switch 104 is turned off, Expression (4) is established.

[0106] Qinit = Qafter + Q2 (4)

[0107] When Expression (1) to Expression (3) are substituted for Expression (4), Expression (5) is obtained.

[0108] Vout = -(C1 / C2) x (Vafter - Vinit) (5)

[0109] With Expression (5), the subtraction section 83 subtracts the photovoltage Vinit from the photovoltage Vafter, that is, calculates the difference signal (Vout) corresponding to a difference Vafter - Vinit between the photovoltages Vafter and Vinit. With Expression (5), the subtraction gain of the subtraction section 83 is C1 / C2. Since the maximum gain is normally desired, Cl is preferably set to a large value and C2 is preferably set to a small value. Meanwhile, when C2 is too small, kTC noise increases, resulting in a risk of deteriorated noise characteristics. Thus, the capacitance C2 can only be reduced in a range that achieves acceptable noise. Further, since the pixel blocks 41 each have installed therein the event detecting section 52 including the subtraction section 83, the capacitances Cl and C2 have space constraints. In consideration of these matters, the values of the capacitances Cl and C2 are determined.

[0110] The comparator 111 compares a difference signal from the subtraction section 83 with a predetermined threshold (voltage) Vth (>0) applied to the inverting input terminal (-), thereby quantizing the difference signal. The comparator 111 outputs the quantized value obtained by the quantization to the transfer section 85 as event data.

[0111] For example, in a case where a difference signal is larger than the threshold Vth, the comparator 111 outputs an H (High) level indicating 1, as event data indicating the occurrence of an event. In a case where a difference signal is not larger than the threshold Vth, the comparator 111 outputs an L (Low) level indicating 0, as event data indicating that no event has occurred.

[0112] The transfer section 85 supplies a request to the arbiter 33 in a case where it is confirmed on the basis of event data from the quantization section 84 that a change in light amount that is an event has occurred, that is, in the case where the difference signal (Vout) is larger than the threshold Vth. When receiving a response indicating event data output permission, the transfer section 85 outputs the event data indicating the occurrence of the event (for example, H level) to the output section 35.

[0113] The output section 35 includes, in event data from the transfer section 85, location / address information regarding (the pixel block 41 including) the pixel 51 in which an event indicated by the event data has occurred and time point information indicating a time point at which the event has occurred, and further, as needed, the polarity of a change in light amount that is the event, i.e. whether the intensity did increase or decrease. The output section 35 outputs the event data.

[0114] As the data format of event data including location information regarding the pixel 51 in which an event has occurred, time point information indicating a time point at which the event has occurred, and the polarity of a change in light amount that is the event, for example, the data format called "AER (Address Event Representation)" can be employed.

[0115] Note that, a gain A of the entire event detecting section 52 is expressed by the following expression where the gain of the current-voltage converting section 81 is denoted by CGiogand the gain of the buffer 82 is 1.

[0116] A = CGiogC 1 / C2 (ZiPhoto_n) (6)

[0117] Here, iPhoto_n denotes a photocurrent of the n-th pixel 51 of the IxJ pixels 51 in the pixel block 41. In Expression (6), E denotes the summation of n that takes integers ranging from 1 to HJ.

[0118] Note that, the pixel 51 can receive any light as incident light with an optical fdter through which predetermined light passes, such as a color fdter. For example, in a case where the pixel 51 receives visible light as incident light, event data indicates the occurrence of changes in pixel value in images including visible objects. Further, for example, in a case where the pixel 51 receives, as incident light, infrared light, millimeter waves, or the like for ranging, event data indicates the occurrence of changes in distances to objects. In addition, for example, in a case where the pixel 51 receives infrared light for temperature measurement, as incident light, event data indicates the occurrence of changes in temperature of objects. In the present embodiment, the pixel 51 is assumed to receive visible light as incident light. Fig. 8 is a diagram illustrating an example of a frame data generation method based on event data.

[0119] The logic section 22 sets a frame interval and a frame width on the basis of an externally input command, for example. Here, the frame interval represents the interval of frames of frame data that is generated on the basis of event data. The frame width represents the time width of event data that is used for generating frame data on a single frame. A frame interval and a frame width that are set by the logic section 22 are also referred to as a "set frame interval" and a "set frame width," respectively.

[0120] The logic section 22 generates, on the basis of the set frame interval, the set frame width, and event data from the sensor section 21, frame data that is image data in a frame format, to thereby convert the event data to the frame data.

[0121] That is, the logic section 22 generates, in each set frame interval, frame data on the basis of event data in the set frame width from the beginning of the set frame interval.

[0122] Here, it is assumed that event data includes time point information ti indicating a time point at which an event has occurred (hereinafter also referred to as an "event time point") and coordinates (x, y) serving as location information regarding (the pixel block 41 including) the pixel 51 in which the event has occurred (hereinafter also referred to as an "event location").

[0123] In Fig. 8, in a three-dimensional space (time and space) with the x axis, the y axis, and the time axis t, points representing event data are plotted on the basis of the event time point t and the event location (coordinates) (x, y) included in the event data.

[0124] That is, when a location (x, y, t) on the three-dimensional space indicated by the event time point t and the event location (x, y) included in event data is regarded as the space-time location of an event, in Fig. 8, the points representing the event data are plotted on the space-time locations (x, y, t) of the events.

[0125] The logic section 22 starts to generate frame data on the basis of event data by using, as a generation start time point at which frame data generation starts, a predetermined time point, for example, a time point at which frame data generation is externally instructed or a time point at which the sensor device 10 is powered on.

[0126] Here, cuboids each having the set frame width in the direction of the time axis t in the set frame intervals, which appear from the generation start time point, are referred to as a "frame volume." The size of the frame volume in the x-axis direction or the y-axis direction is equal to the number of the pixel blocks 41 or the pixels 51 in the x-axis direction or the y-axis direction, for example.

[0127] The logic section 22 generates, in each set frame interval, frame data on a single frame on the basis of event data in the frame volume having the set frame width from the beginning of the set frame interval. Frame data can be generated by, for example, setting white to a pixel (pixel value) in a frame at the event location (x, y) included in event data and setting a predetermined color such as gray to pixels at other locations in the frame.

[0128] Besides, in a case where event data includes the polarity of a change in light amount that is an event, frame data can be generated in consideration of the polarity included in the event data. For example, white can be set to pixels in the case a positive polarity, while black can be set to pixels in the case of a negative polarity.

[0129] In addition, in the case where pixel signals of the pixels 51 are also output when event data is output as described with reference to Fig. 3 and Fig. 4, frame data can be generated on the basis of the event data by using the pixel signals of the pixels 51. That is, frame data can be generated by setting, in a frame, a pixel at the event location (x, y) (in a block corresponding to the pixel block 41) included in event data to a pixel signal of the pixel 51 at the location (x, y) and setting a predetermined color such as gray to pixels at other locations.

[0130] Note that, in the frame volume, there are a plurality of pieces of event data that are different in the event time point t but the same in the event location (x, y) in some cases. In this case, for example, event data at the latest or oldest event time point t can be prioritized. Further, in the case where event data includes polarities, the polarities of a plurality of pieces of event data that are different in the event time point t but the same in the event location (x, y) can be added together, and a pixel value based on the added value obtained by the addition can be set to a pixel at the event location (x, y).

[0131] Here, in a case where the frame width and the frame interval are the same, the frame volumes are adjacent to each other without any gap. Further, in a case where the frame interval is larger than the frame width, the frame volumes are arranged with gaps. In a case where the frame width is larger than the frame interval, the frame volumes are arranged to be partly overlapped with each other.

[0132] Fig. 9 is a block diagram illustrating another configuration example of the quantization section 84 of Fig. 5.

[0133] Note that, in Fig. 9, parts corresponding to those in the case of Fig. 7 are denoted by the same reference signs, and the description thereof is omitted as appropriate below.

[0134] In Fig. 9, the quantization section 84 includes comparators 111 and 112 and an output section 113.

[0135] Thus, the quantization section 84 of Fig. 9 is similar to the case of Fig. 7 in including the comparator 111. However, the quantization section 84 of Fig. 9 is different from the case of Fig. 7 in newly including the comparator 112 and the output section 113.

[0136] The event detecting section 52 (Fig. 5) including the quantization section 84 of Fig. 9 detects, in addition to events, the polarities of changes in light amount that are events. In the quantization section 84 of Fig. 9, the comparator 111 outputs, in the case where a difference signal is larger than the threshold Vth, the H level indicating 1, as event data indicating the occurrence of an event having the positive polarity. The comparator 111 outputs, in the case where a difference signal is not larger than the threshold Vth, the L level indicating 0, as event data indicating that no event having the positive polarity has occurred.

[0137] Further, in the quantization section 84 of Fig. 9, a threshold Vth' (<Vth) is supplied to the non-inverting input terminal (+) of the comparator 112, and difference signals are supplied to the inverting input terminal (-) of the comparator 112 from the subtraction section 83. Here, for the sake of simple description, it is assumed that the threshold Vth' is equal to -Vth, for example, which needs however not to be the case.

[0138] The comparator 112 compares a difference signal from the subtraction section 83 with the threshold Vth' applied to the inverting input terminal (-), thereby quantizing the difference signal. The comparator 112 outputs, as event data, the quantized value obtained by the quantization.

[0139] For example, in a case where a difference signal is smaller than the threshold Vth' (the absolute value of the difference signal having a negative value is larger than the threshold Vth), the comparator 112 outputs the H level indicating 1, as event data indicating the occurrence of an event having the negative polarity. Further, in a case where a difference signal is not smaller than the threshold Vth' (the absolute value of the difference signal having a negative value is not larger than the threshold Vth), the comparator 112 outputs the L level indicating 0, as event data indicating that no event having the negative polarity has occurred.

[0140] The output section 113 outputs, on the basis of event data output from the comparators 111 and 112, event data indicating the occurrence of an event having the positive polarity, event data indicating the occurrence of an event having the negative polarity, or event data indicating that no event has occurred to the transfer section 85.

[0141] For example, the output section 113 outputs, in a case where event data from the comparator 111 is the H level indicating 1, +V volts indicating +1, as event data indicating the occurrence of an event having the positive polarity, to the transfer section 85. Further, the output section 113 outputs, in a case where event data from the comparator 112 is the H level indicating 1, -V volts indicating -1, as event data indicating the occurrence of an event having the negative polarity, to the transfer section 85. In addition, the output section 113 outputs, in a case where each event data from the comparators 111 and 112 is the L level indicating 0, 0 volts (GND level) indicating 0, as event data indicating that no event has occurred, to the transfer section 85.

[0142] The transfer section 85 supplies a request to the arbiter 33 in the case where it is confirmed on the basis of event data from the output section 113 of the quantization section 84 that a change in light amount that is an event having the positive polarity or the negative polarity has occurred. After receiving a response indicating event data output permission, the transfer section 85 outputs event data indicating the occurrence of the event having the positive polarity or the negative polarity (+V volts indicating 1 or -V volts indicating -1) to the output section 35.

[0143] Preferably, the quantization section 84 has a configuration as illustrated in Fig. 9.

[0144] Fig. 10 is a diagram illustrating another configuration example of the event detecting section 52.

[0145] In Fig. 10, the event detecting section 52 includes a subtractor 430, a quantizer 440, a memory 451, and a controller 452. The subtractor 430 and the quantizer 440 correspond to the subtraction section 83 and the quantization section 84, respectively.

[0146] Note that, in Fig. 10, the event detecting section 52 further includes blocks corresponding to the currentvoltage converting section 81 and the buffer 82, but the illustrations of the blocks are omitted in Fig. 10.

[0147] The subtractor 430 includes a capacitor 431, an operational amplifier 432, a capacitor 433, and a switch 434. The capacitor 431, the operational amplifier 432, the capacitor 433, and the switch 434 correspond to the capacitor 101, the operational amplifier 102, the capacitor 103, and the switch 104, respectively.

[0148] The quantizer 440 includes a comparator 441. The comparator 441 corresponds to the comparator 111.

[0149] The comparator 441 compares a voltage signal (difference signal) from the subtractor 430 with the predetermined threshold voltage Vth applied to the inverting input terminal (-). The comparator 441 outputs a signal indicating the comparison result, as a detection signal (quantized value).

[0150] The voltage signal from the subtractor 430 may be input to the input terminal (-) of the comparator 441, and the predetermined threshold voltage Vth may be input to the input terminal (+) of the comparator 441.

[0151] The controller 452 supplies the predetermined threshold voltage Vth applied to the inverting input terminal (-) of the comparator 441. The threshold voltage Vth which is supplied may be changed in a time-division manner. For example, the controller 452 supplies a threshold voltage Vthl corresponding to ON events (for example, positive changes in photocurrent) and a threshold voltage Vth2 corresponding to OFF events (for example, negative changes in photocurrent) at different timings to allow the single comparator to detect a plurality of types of address events (events).

[0152] The memory 451 accumulates output from the comparator 441 on the basis of Sample signals supplied from the controller 452. The memory 451 may be a sampling circuit, such as a switch, plastic, or capacitor, or a digital memory circuit, such as a latch or flip-flop. For example, the memory 451 may hold, in a period in which the threshold voltage Vth2 corresponding to OFF events is supplied to the inverting input terminal (-) of the comparator 441, the result of comparison by the comparator 441 using the threshold voltage Vthl corresponding to ON events. Note that, the memory 451 may be omitted, may be provided inside the pixel (pixel block 41), or may be provided outside the pixel. Fig. 11 is a block diagram illustrating another configuration example of the pixel array section 31 of Fig.

[0153] 2.

[0154] Note that, in Fig. 11, parts corresponding to those in the case of Fig. 3 are denoted by the same reference signs, and the description thereof is omitted as appropriate below.

[0155] In Fig. 11, the pixel array section 31 includes the plurality of pixel blocks 41. The pixel block 41 includes the lx J pixels 51 that are one or more pixels and the event detecting section 52.

[0156] Thus, the pixel array section 31 of Fig. 11 is similar to the case of Fig. 3 in that the pixel array section 31 includes the plurality of pixel blocks 41 and that the pixel block 41 includes one or more pixels 51 and the event detecting section 52. However, the pixel array section 31 of Fig. 11 is different from the case of Fig. 3 in that the pixel block 41 does not include the pixel signal generating section 53.

[0157] As described above, in the pixel array section 31 of Fig. 11, the pixel block 41 does not include the pixel signal generating section 53, so that the sensor section 21 (Fig. 2) can be formed without the AD conversion section 34.

[0158] Fig. 12 is a circuit diagram illustrating a configuration example of the pixel block 41 of Fig. 11.

[0159] As described with reference to Fig. 11, the pixel block 41 includes the pixels 51 and the event detecting section 52, but does not include the pixel signal generating section 53.

[0160] In this case, the pixel 51 can only include the photoelectric conversion element 61 without the transfer transistors 62 and 63.

[0161] Note that, in the case where the pixel 51 has the configuration illustrated in Fig. 12, the event detecting section 52 can output a voltage corresponding to a photocurrent from the pixel 51, as a pixel signal.

[0162] Fig. 13 is a block diagram illustrating a configuration example of a scan type imaging device which may be used as an EVS.

[0163] As illustrated in Fig. 13, an imaging device 510 includes a pixel array section 521, a driving section 522, a signal processing section 525, a read-out region selecting section 527, and an optional signal generating section 528.

[0164] The pixel array section 521 includes a plurality of pixels 530. The plurality of pixels 530 each output an output signal in response to a selection signal from the read-out region selecting section 527. The plurality of pixels 530 can each include an in-pixel quantizer as illustrated in Fig. 10, for example. The plurality of pixels 530 outputs output signals corresponding to the amounts of change in light intensity. The plurality of pixels 530 may be two-dimensionally disposed in a matrix as illustrated in Fig. 13. The driving section 522 drives the plurality of pixels 530, so that the pixels 530 output pixel signals generated in the pixels 530 to the signal processing section 525 through an output line 514. Note that, the driving section 522 and the signal processing section 525 are circuit sections for acquiring grayscale information.

[0165] The read-out region selecting section 527 selects some of the plurality of pixels 530 included in the pixel array section 521. For example, the read-out region selecting section 527 selects one or a plurality of rows included in the two-dimensional matrix structure corresponding to the pixel array section 521. The readout region selecting section 527 sequentially selects one or a plurality of rows on the basis of a cycle set in advance, e.g. based on a rolling shutter. Further, the read-out region selecting section 527 may determine a selection region on the basis of requests from the pixels 530 in the pixel array section 521.

[0166] The optional signal generating section 528 may generate, on the basis of output signals of the pixels 530 selected by the read-out region selecting section 527, event signals corresponding to active pixels in which events have been detected of the selected pixels 530. The events mean an event that the intensity of light changes. The active pixels mean the pixel 530 in which the amount of change in light intensity corresponding to an output signal exceeds or falls below a threshold set in advance. For example, the signal generating section 528 compares output signals from the pixels 530 with a reference signal, and detects, as an active pixel, a pixel that outputs an output signal larger or smaller than the reference signal. The signal generating section 528 generates an event signal (event data) corresponding to the active pixel.

[0167] The signal generating section 528 can include, for example, a column selecting circuit configured to arbitrate signals input to the signal generating section 528. Further, the signal generating section 528 can output not only information regarding active pixels in which events have been detected, but also information regarding non-active pixels in which no event has been detected.

[0168] The signal generating section 528 outputs, through an output line 515, address information and timestamp information (for example, (X, Y, T)) regarding the active pixels in which the events have been detected. However, the data that is output from the signal generating section 528 may not only be the address information and the timestamp information, but also information in a frame format (for example, (0, 0, 1, o, -)).

[0169] In the following description reference will mainly be made to sensor devices of the EVS type as described above in order to ease the description and to cover an important application example. However, the principles explained below apply just as well to any event-based vision sensor that is capable to generate events based on the occurrence of temporal intensity changes.

[0170] In the following description the above sensor is modified such as to allow suppression of erroneously or superfluously generated event data. This allows to increase the spatial resolution of according sensors.

[0171] To this end, Fig. 14 illustrates in a schematic and simplified manner a sensor device 10. The sensor device 10 comprises a pixel array 1011 as e.g. described above that has a plurality of pixels 51 that are each configured to receive light and to perform photoelectric conversion to generate an electrical signal indicating the intensity of the received light. Although the following description refers to pixels 51, each reference to a pixel 51 can be replaced by a reference to a pixel block 41 as described above. This means, the intensity observed by the pixel 51 as described below may also be obtained by summing the intensities of subpixels or by accessing intensities received at different sub-pixels at different times. Thus, the below reference to pixels 51 serves only the purpose to ease the description. It is, however, not limiting.

[0172] The sensor device 10 comprises further a plurality of event detecting sections 52, an example of which has been described above. The event detecting sections 52 are configured to receive the electrical signals from each of the plurality of pixels 51 and to generate event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel 51 above an event threshold.

[0173] As illustrated in Fig. 14 (and as described above with respect to Fig. 3 for pixel blocks 41 with only a single pixel 51), each pixel 51 may be provided with its own event detecting section 52. However, there might also be one event detecting section 52 for a plurality of pixels 51 that receives the electrical signals from the different pixels 51 in a time-multiplexed manner. The number of pixels 51 per event detecting section 52 may also vary across different regions of the pixel array 1011. Further, it might also be dynamically decided which pixel signal is provided to which event detecting section 52.

[0174] As illustrated in Fig. 14, the event detecting sections 52 may be arranged within the pixels 51. However, the event detecting sections 52 (or parts thereof) may also be arranged outside the pixels 51, but within the pixel array 1011. Also, the event detecting sections 52 (or parts thereof) may be separated from the pixel array 1011. The pixel array 1011 and the event detecting sections 52 (or parts thereof) may even be arranged at different chips / sensor dies. The pixel array 1011 may be located on the sensor die 11 and the event detecting sections 52 may be located on the logic die 12. The event detecting sections 52 may even be part of a different processor or a different computing device. However, it is preferred that the pixel array 1011 and the event detecting sections 52 are located on the same chip and it is most preferred that the event detecting sections 52 are constituted as described above.

[0175] The sensor device 10 comprises further at least one selection section 100 that is configured to receive the electrical signals generated by a group 511 of adjacent pixels 51. From these electrical signals the selection section 100 determines at which pixel 51 of the group 511 the largest intensity has been received. Based on this determination the selection section 100 enables generation of event data for the one pixel 51 of the group that did receive the largest intensity. For all other pixels 51 of the group 511 generation of event data is disabled.

[0176] Here, the functions of the selection section 100 may be carried out by a control unit of the sensor device 10. This control unit may control various functions of the sensor device 10 and may be constituted by any processing device, such as a processor, a microcomputer, a CPU, a GPU, a FPGA, an ASIC or the like. The control unit may be implemented in hardware, in software or as a mixture of hardware and software. The control unit may be located on the same chip as the pixel array 1011. However, it may also be located on a different chip, in particular the control unit may be part of the logic die 12. Preferably, the selection section 100 is not part of or constituted by such a control unit but consists of comparably simple circuitry that allows automatic enabling and disabling of event data generation without the necessity of control or computing steps.

[0177] As illustrated in Fig. 14, the selection section 100 receives the electrical signals of several pixels 51 that are arranged adjacent to each other. For example, the adjacent pixels 51 form a group 511 of N x N pixels 51, with N a natural number larger than 1, preferably with N = 2, or 3. This means that square shaped regions of the pixel array 1011 will produce only a single event. The size of the square shaped regions is preferably limited, since for two large groups the gain in spatial resolution obtained by suppressing noise or blurring is overcompensated by the reduction of event data due to the grouping.

[0178] The group 511 of pixels 51 is not necessarily square shaped, but may also be rectangle shaped, e.g. formed by 2 x 1, 3 x 1, 4 x 1, 3 x 2 or 4 x 2 pixels 51 arranged horizontally or vertically, or may even be arbitrary. Further, the groups 511 may also overlap, i.e. each pixel 51 may be part of more than one group 511. The pixel array 1011 may be entirely covered by groups 511 or only parts of the pixel array 1011 may be covered with groups 511.

[0179] Further, the sensor device 10 may change size and / or location of groups 511 within the plurality of pixels 51. Accordingly, pixel groups 511 can be dynamically set up for regions showing a high amount of noise or blurring in previous time periods. Also, the size of the groups 511 can be changed depending on the previously detected distribution of events or depending on the efficiency of the processing that is based on event data generated by the sensor device 10.

[0180] For each pixel group 511 only the pixel 51 is allowed to generate event data 51 that received the strongest intensity of light, i.e. that is illuminated the most. For all other pixels 51 of this group 511 event generation is disabled, for example by totally disabling the respective pixels 51, e.g. by grounding photoelectric conversion elements within the pixels 51 or by interrupting signal propagation within the event detecting sections 52.

[0181] In this manner, noise or blurring can be reduced by suppressing event data generation in pixels 51 that are adjacent to a pixel 51 that received at the same time a higher intensity of light. In particular, since events generated by noise are in most cases triggered by signals corresponding to intensities that are lower than the intensities received during triggering of true events, noise around true events is suppressed, enhancing the “contrast” of such true events against the (up to noise) event-less background.

[0182] Further, a moving object in a captured scene may generate events in adjacent pixels 51, since light from the same region on the object is received at neighboring pixels 51. However, for recognizing features of the object, it is most often sufficient, if not preferable, that the features of the object are projected onto a single pixel 51. Using only the pixel 51 that received the largest intensity can therefore also in this situation help to improve the processing of the event data, either by reducing redundant information or even by allowing deduction of features of a captured object more easily.

[0183] This is exemplified in Figs. 15A and 15B. Figs. 15A and 15B show both ON-events generated by the movement of a bright line. OFF-events are not illustrated in the example in order to ease the description. The principle described for ON-events works the same for OFF-events.

[0184] Fig. 15A shows a situation where light from one region of the brigth line is received at several adjacent pixels 51. This means that several pixels 51 surrounding the exact image L of the bright line on the pixel array 1011 detect a change of the received intensity that is above the event threshold. These pixels 51 are depicted black in Fig 15A. It is apparent in Fig. 15A that the image L of the bright line is captured in a blurred manner.

[0185] Fig. 15B shows the same situation where the above described switch off of event generation is carried out. In Fig. 15B it is assumed that 2x2 pixels 51 form the groups 511. These groups 511 do not overlap, i.e. they are arranged as illustrated in Fig. 1: each pixel 51 belongs only to a single group 511. As explained above, this is not limiting, but eases the description. Groups 511 are indicated by thick black lines in Fig. 15B.

[0186] As is apparent from Fig. 15B, the number of events representing the line is reduced. Nevertheless, it is possible to deduce the presence of the image L of the line without difficulty. Moreover, since segments of the image L of the line are represented by single pixels 51, it is possible to determine the location of the line with greater precision as it would be possible from Fig. 15A. Accordingly, in the situation of Fig. 15B the sensor device 10 can resolve the position of the line with larger accuracy, i.e. it has a higher spatial resolution than in the situation of Fig. 15A.

[0187] Thus, by enabling and disabling event generation based on the received intensity, the spatial resolution of the sensor device 10 can be enhanced.

[0188] Here, it is preferable that the electrical signals generated by the pixels 51 are photocurrent generated by photoelectric conversion elements 61 within the pixel 51, as e.g. described above with respect to Fig. 4. The selection section 100 is then configured to determine the largest photocurrent in order to determine the largest intensity and to generate control signals that enable and disable event data generation for the pixels 51 of the group 511. Since the photocurrent of the pixels 51 is a direct measure of the received intensity this is a particularly easy implementation of the determination of the largest intensity of the received light. However, in principle, it would also be possible to determine the largest intensity from electrical signals derived from the photocurrent such as e.g. a voltage obtained from converting the photocurrent, e.g. in a current-voltage conversion section 81 as described above with respect to Fig. 6.

[0189] In order to obtain the photocurrent generated at the pixels 51 without disturbing the signal flow within the event detecting section 52, the selection section 100 may comprise current mirrors 110. These current mirrors 110 receive as input the photocurrent and provide as output on the one hand the original photocurrent and a replication of the photocurrent. This is exemplary illustrated in Fig. 16, where the current mirrors 110 replicate the photocurrent provided from the photoelectric conversion elements 61 to the event detecting sections 52. Using current mirrors 110 provides the advantage that the photocurrent fed into the event detecting sections 52 is not affected by the determination of the largest photocurrent, since this is done on the replicated photocurrents. Thus, in principle it is possible to perform event data generation as if no such determination is made. Here, the type of current mirror 110 that is used is in principle arbitrary as long as it allows a precise and reliable replication of the photocurrents. An example for a circuit diagram of a current mirror 110 is shown in Fig. 18. However, any other current mirror circuitry might be used.

[0190] Further, the selection section 100 may comprise a winner-take-all circuit 120 that comprises input lines 122 that are configured to receive said replications of photocurrents and output lines 124 that are connected to the respective event detecting sections 52 from which the replications of photocurrents are obtained. Thus, as exemplary illustrated in Fig. 16 the event detecting sections 52 receive signals along two different paths. First, they are provided with the photocurrents from the photoelectric conversion elements 61 in the usual manner. Second, they are provided with control signals that enable or disable generation of event data. These control signals may be generated by a winner-take-all circuit 120, which compares all incoming replications of photocurrents and determines thereby the photocurrent indicating the largest intensity of received light.

[0191] In particular, the largest replication of photocurrents triggers an output of an enable signal through the respective output line 124 of the winner-take-all circuit 120 to the event detecting section 52 to which the photocurrent corresponding to the largest replication of photocurrents is provided (thick arrow in Fig. 16), while disable signals are output through the remaining output lines (thin arrows in Fig. 16).

[0192] Winner-take-all circuits 120 are in principle known to a skilled person and an arbitrary winner-take-all circuit 120 may be used. One example for a winner-take-all circuit 120 is shown in Fig. 17.

[0193] The illustrated winner-take-all circuit 120 has four input lines 122 and four output lines 124, according to the four pixels 51 arranged in the one group 511 of the example of Fig. 16. However, depending on the number of pixels 51 per group 511, the number of input lines 122 and output lines 124 may also be different, i.e. it corresponds to the number of pixels 51 per group 511. At each input line 122 one of the replications of photocurrents is applied. Each input line 122 is connected via an inner transistors 95 and an outer transistor 96 to the output line 124 in the illustrated manner. Further, each output line 124 is connected via the outer transistor 96 to a current source 97.

[0194] The effect of this circuitry is that the largest input current leads to the largest reduction of resistance at the corresponding outer transistor 96, thus pulling the largest portion of the current generated at the current source 97 to the respective output line 124. This in turn reduces the resistance at the corresponding inner transistor 95, leading to a larger current flow through this inner transistor 95. This reduces resistance at the outer transistor 96 further. This process continues until the entire current generated at the current source 97 flows through the output line 124 connected via inner transistor 95 and outer transistor 96 to the input line 122 that provides the largest input current. In this sense the “winner takes all”, i.e. only the output line 124 connected to the input line 122 at which the largest current is received provides an output current, while through all other output lines 124 no current is output.

[0195] Thus, the winner-take-all circuit 120 is ideally configured to provide the basis for an enable signal to just that event detecting section 52 to which the largest photocurrent is provided. For example, the current output from the winner-take-all circuit 120 can be converted to a control voltage that is used to trigger switches of the event detecting section 52 or switches added to the event detecting section 52 such as to interrupt or disturb signal processing in the event detecting section 52, if the voltage is not sufficiently high. This allows selecting in a reliable and comparably easy manner which of the detected intensities can be used for event data generation.

[0196] The current mirrors 110 may replicate the photocurrent at any stage of the processing of the electrical signal provided from the pixels 51. Preferably, if the event detecting sections 52 comprise current-voltage converting sections 81 that converts the photocurrent into a voltage based on which voltage event data generation is carried out, the current mirrors 110 are configured to receive as inputs the photocurrents input from the pixels 51 of the group 511 into the respective current-voltage converting sections 81. That is, the photocurrent is mirrored just before current-voltage conversion, i.e. photocurrents are compared based on which photocurrents the event detecting sections 52 operate.

[0197] An example of such a connection of a current mirror 110 to a current-voltage converting section 81 is illustrated in Fig. 18. Here, the current-voltage converting section 81 is configured as explained above with respect to Fig. 6. Thus, a detailed description is not necessary. It is further understood that any other current-voltage converting section 81 may be used.

[0198] In the example of Fig. 18, the current mirror 110 is connected via an additional transistor 94 to the current-voltage converting section 81. The current mirror 110 and the additional transistor 94 replace the connection of Fig. 6 between the transistor 91 and the power supply VDD. The photocurrent flowing through the transistors 91 and 94 is replicated by the current mirror 110. The replicated photocurrent is input into the winner-take-all circuit 120 as explained above. Further, as explained above with respect to Fig. 6, the photocurrent is converted at transistor 91 into a voltage that is provided for event data generation to the remaining components of the event detecting section 52.

[0199] Here, each event detecting section 52 may comprise a subtraction section 83 that receives the voltage from the respective current-voltage converting section 81 and in which the change of intensities of light is determined by detecting a change of the received voltage. In particular, the event detecting sections 52 carry out event detection by monitoring the photovoltage obtained from the current-voltage conversion of the photocurrent. Here, the event detection may be carried out in a subtraction section 83 as described above with respect to Figs. 7 or 10. But event detection may also be carried out in a differently constituted subtraction section 83.

[0200] The control signal from the selection section 100 enables and disables then event data generation by enabling and disabling the detection of the change of the received voltages in the subtraction sections 83. For example, as illustrated in a simplified manner in Fig. 19, the signal path between (or in) the currentvoltage converting section 81 and the subtraction section 83 may be interrupted by the selection section 100 for all those event detecting sections 52 of a group 511 that do not receive the largest photocurrent of the group 511. For example, a transistor is provided between the current-voltage converting section 81 and the subtraction section 83 that sets the voltage to ground potential or a predetermined voltage such as e.g. VDD, if the signal provided from the winner-take-all circuit 120 is low.

[0201] A particular example for this is shown in Fig. 20, which example is based on the subtraction section 83 discussed above with respect to Fig. 7.

[0202] As explained above, the subtraction section 83 comprises a first capacitor 101, a second capacitor 103, an operational amplifier 102, and a (first) switch 104. The subtraction section 83 may further comprise a second switch 105. The first capacitor 101 has a first end that receives the voltage from the respective current-voltage converting section 81 and a second end connected to an input terminal of the operational amplifier 102. The second capacitor 103 has a first end connected to the input terminal of the operational amplifier 102 and to the second end of the first capacitor 101 and a second end connected to an output terminal of the operational amplifier 102. Both of the first switch 104 and the second switch 105 are configured to electrically connect the first end and the second end of the second capacitor 103 when switched on. As explained above, the operational amplifier 102 is configured to indicate at its output terminal the change of the voltage received at the first end of the first capacitor 101. Then, the control signal received from the selection section enables event data generation by switching the first switch 104 and the second switch 105 off and disables event data generation by switching one of the switches 104, 105 on.

[0203] Here, the second switch 105 may be provided only, if switching via the (first) switch 104 is not desired, which first switch 104 also receives control signals from the driving section 32. For example, the second switch 105 may be used to ensure shorting of the second capacitor 103 irrespective of the driving signals obtained for the first switch 104.

[0204] Thus, the control signal from the selection section 100 can be used to disable event data generation by shorting the second capacitor 103, i.e. the capacitor of the subtraction section that is connected to input and output of the operational amplifier 102. In this manner determination of voltage changes is disabled. For normal operation, the control signal from the selection section 100 provides no modification to the normal operation of the subtraction section 83, either by providing no additional control signal to the first switch 104 or by opening the second switch 105.

[0205] In the example of Fig. 16, i.e. for the presence of a winner-take-all circuit 120, the output current of the winner-take-all circuit 120 may be converted into a voltage signal such that high current leads to a low or zero / ground potential voltage, while low current leads to a high potential voltage. These voltages could be superseded the driving signals provided from the driving section 32 to the (first) switch 104. This will effectively close the (first) switch 104 of all event detecting sections 52 that did not receive the highest photocurrent of the respective group 511 of pixels 51, while the event detecting section 52 that did receive the highest photocurrent can operate normally based on the driving signals from the driving section. Also, it might be possible to provide the converted voltages to the second switch 105 to short the second capacitor 103.

[0206] The second switch 105 might here also be a transistor with an inverting gate. Then, current outputs of the winner-take-all circuit 120 can be converted directly proportional to voltages, i.e. high currents lead to high voltages, which lead to an open second switch 105 due to the inverting gate.

[0207] Of course, there are many other ways to implement the above-described disablement of event detection for pixels 51 that do not receive as much intensity as one of the neighboring pixels 51. The abovedescribed method for operating a sensor device 10 can be summarized as illustrated in Fig. 21.

[0208] Here, at S101 at each of the plurality of pixels 51, light is received to perform photoelectric conversion and an electrical signal indicating the intensity of the received light is generated. At SI 02, at the plurality of event detecting sections 52, the electrical signals from each of the plurality of pixels 51 are received and event data are generated that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel 51 above an event threshold. At S103, at the selection section 100, the electrical signals generated by a group 511 of adjacent pixels 51 are received and it is determined from the electrical signals at which pixel 51 of the group the largest intensity has been received. At SI 04 generation of event data is enabled for the pixel 51 of the group 511 that did receive the largest intensity, while generation of event data is disabled for the other pixels 51 of the group 511.

[0209] This allows reduction of events caused by noise and blurring, which in turns allows a better spatial resolution.

[0210] The technology according to the above (i.e. the present technology) is applicable to various products. For example, the technology according to the present disclosure may be realized as a device that is installed on any kind of moving bodies, for example, vehicles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobilities, airplanes, drones, ships, and robots.

[0211] Fig. 22 is a block diagram depicting an example of schematic configuration of a vehicle control system as an example of a mobile body control system to which the technology according to an embodiment of the present disclosure can be applied.

[0212] The vehicle control system 12000 includes a plurality of electronic control units connected to each other via a communication network 12001. In the example depicted in Fig. 22, the vehicle control system 12000 includes a driving system control unit 12010, a body system control unit 12020, an outside -vehicle information detecting unit 12030, an in-vehicle information detecting unit 12040, and an integrated control unit 12050. In addition, a microcomputer 12051, a sound / image output section 12052, and a vehicle-mounted network interface (I / F) 12053 are illustrated as a functional configuration of the integrated control unit 12050. The driving system control unit 12010 controls the operation of devices related to the driving system of the vehicle in accordance with various kinds of programs. For example, the driving system control unit 12010 functions as a control device for a driving force generating device for generating the driving force of the vehicle, such as an internal combustion engine, a driving motor, or the like, a driving force transmitting mechanism for transmitting the driving force to wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating the braking force of the vehicle, and the like.

[0213] The body system control unit 12020 controls the operation of various kinds of devices provided to a vehicle body in accordance with various kinds of programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various kinds of lamps such as a headlamp, a backup lamp, a brake lamp, a turn signal, a fog lamp, or the like. In this case, radio waves transmitted from a mobile device as an alternative to a key or signals of various kinds of switches can be input to the body system control unit 12020. The body system control unit 12020 receives these input radio waves or signals, and controls a door lock device, the power window device, the lamps, or the like of the vehicle.

[0214] The outside-vehicle information detecting unit 12030 detects information about the outside of the vehicle including the vehicle control system 12000. For example, the outside-vehicle information detecting unit 12030 is connected with an imaging section 12031. The outside-vehicle information detecting unit 12030 makes the imaging section 12031 image an image of the outside of the vehicle, and receives the imaged image. On the basis of the received image, the outside-vehicle information detecting unit 12030 may perform processing of detecting an object such as a human, a vehicle, an obstacle, a sign, a character on a road surface, or the like, or processing of detecting a distance thereto.

[0215] The imaging section 12031 is an optical sensor that receives light, and which outputs an electric signal corresponding to a received light amount of the light. The imaging section 12031 can output the electric signal as an image, or can output the electric signal as information about a measured distance. In addition, the light received by the imaging section 12031 may be visible light, or may be invisible light such as infrared rays or the like.

[0216] The in-vehicle information detecting unit 12040 detects information about the inside of the vehicle. The in-vehicle information detecting unit 12040 is, for example, connected with a driver state detecting section 12041 that detects the state of a driver. The driver state detecting section 12041, for example, includes a camera that images the driver. On the basis of detection information input from the driver state detecting section 12041, the in-vehicle information detecting unit 12040 may calculate a degree of fatigue of the driver or a degree of concentration of the driver, or may determine whether the driver is dozing.

[0217] The microcomputer 12051 can calculate a control target value for the driving force generating device, the steering mechanism, or the braking device on the basis of the information about the inside or outside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030 or the in-vehicle information detecting unit 12040, and output a control command to the driving system control unit 12010. For example, the microcomputer 12051 can perform cooperative control intended to implement functions of an advanced driver assistance system (ADAS) which functions include collision avoidance or shock mitigation for the vehicle, following driving based on a following distance, vehicle speed maintaining driving, a warning of collision of the vehicle, a warning of deviation of the vehicle from a lane, or the like.

[0218] In addition, the microcomputer 12051 can perform cooperative control intended for automatic driving, which makes the vehicle to travel autonomously without depending on the operation of the driver, or the like, by controlling the driving force generating device, the steering mechanism, the braking device, or the like on the basis of the information about the outside or inside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030 or the in-vehicle information detecting unit 12040.

[0219] In addition, the microcomputer 12051 can output a control command to the body system control unit 12020 on the basis of the information about the outside of the vehicle which information is obtained by the outside-vehicle information detecting unit 12030. For example, the microcomputer 12051 can perform cooperative control intended to prevent a glare by controlling the headlamp so as to change from a high beam to a low beam, for example, in accordance with the position of a preceding vehicle or an oncoming vehicle detected by the outside-vehicle information detecting unit 12030.

[0220] The sound / image output section 12052 transmits an output signal of at least one of a sound and an image to an output device capable of visually or auditorily notifying information to an occupant of the vehicle or the outside of the vehicle. In the example of Fig. 22, an audio speaker 12061, a display section 12062, and an instrument panel 12063 are illustrated as the output device. The display section 12062 may, for example, include at least one of an on-board display and a head-up display.

[0221] Fig. 23 is a diagram depicting an example of the installation position of the imaging section 12031.

[0222] In Fig. 23, the imaging section 12031 includes imaging sections 12101, 12102, 12103, 12104, and 12105.

[0223] The imaging sections 12101, 12102, 12103, 12104, and 12105 are, for example, disposed at positions on a front nose, sideview mirrors, a rear bumper, and a back door of the vehicle 12100 as well as a position on an upper portion of a windshield within the interior of the vehicle. The imaging section 12101 provided to the front nose and the imaging section 12105 provided to the upper portion of the windshield within the interior of the vehicle obtain mainly an image of the front of the vehicle 12100. The imaging sections 12102 and 12103 provided to the sideview mirrors obtain mainly an image of the sides of the vehicle 12100. The imaging section 12104 provided to the rear bumper or the back door obtains mainly an image of the rear of the vehicle 12100. The imaging section 12105 provided to the upper portion of the windshield within the interior of the vehicle is used mainly to detect a preceding vehicle, a pedestrian, an obstacle, a signal, a traffic sign, a lane, or the like.

[0224] Incidentally, Fig. 23 depicts an example of photographing ranges of the imaging sections 12101 to 12104. An imaging range 12111 represents the imaging range of the imaging section 12101 provided to the front nose. Imaging ranges 12112 and 12113 respectively represent the imaging ranges of the imaging sections 12102 and 12103 provided to the sideview mirrors. An imaging range 12114 represents the imaging range of the imaging section 12104 provided to the rear bumper or the back door. A bird’s-eye image of the vehicle 12100 as viewed from above is obtained by superimposing image data imaged by the imaging sections 12101 to 12104, for example.

[0225] At least one of the imaging sections 12101 to 12104 may have a function of obtaining distance information. For example, at least one of the imaging sections 12101 to 12104 may be a stereo camera constituted of a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

[0226] For example, the microcomputer 12051 can determine a distance to each three-dimensional object within the imaging ranges 12111 to 12114 and a temporal change in the distance (relative speed with respect to the vehicle 12100) on the basis of the distance information obtained from the imaging sections 12101 to 12104, and thereby extract, as a preceding vehicle, a nearest three-dimensional object in particular that is present on a traveling path of the vehicle 12100 and which travels in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, equal to or more than 0 km / hour). Further, the microcomputer 12051 can set a following distance to be maintained in front of a preceding vehicle in advance, and perform automatic brake control (including following stop control), automatic acceleration control (including following start control), or the like. It is thus possible to perform cooperative control intended for automatic driving that makes the vehicle travel autonomously without depending on the operation of the driver or the like.

[0227] For example, the microcomputer 12051 can classify three-dimensional object data on three-dimensional objects into three-dimensional object data of a two-wheeled vehicle, a standard-sized vehicle, a largesized vehicle, a pedestrian, a utility pole, and other three-dimensional objects on the basis of the distance information obtained from the imaging sections 12101 to 12104, extract the classified three-dimensional object data, and use the extracted three-dimensional object data for automatic avoidance of an obstacle. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that the driver of the vehicle 12100 can recognize visually and obstacles that are difficult for the driver of the vehicle 12100 to recognize visually. Then, the microcomputer 12051 determines a collision risk indicating a risk of collision with each obstacle. In a situation in which the collision risk is equal to or higher than a set value and there is thus a possibility of collision, the microcomputer 12051 outputs a warning to the driver via the audio speaker 12061 or the display section 12062, and performs forced deceleration or avoidance steering via the driving system control unit 12010. The microcomputer 12051 can thereby assist in driving to avoid collision.

[0228] At least one of the imaging sections 12101 to 12104 may be an infrared camera that detects infrared rays. The microcomputer 12051 can, for example, recognize a pedestrian by determining whether or not there is a pedestrian in imaged images of the imaging sections 12101 to 12104. Such recognition of a pedestrian is, for example, performed by a procedure of extracting characteristic points in the imaged images of the imaging sections 12101 to 12104 as infrared cameras and a procedure of determining whether or not it is the pedestrian by performing pattern matching processing on a series of characteristic points representing the contour of the object. When the microcomputer 12051 determines that there is a pedestrian in the imaged images of the imaging sections 12101 to 12104, and thus recognizes the pedestrian, the sound / image output section 12052 controls the display section 12062 so that a square contour line for emphasis is displayed so as to be superimposed on the recognized pedestrian. The sound / image output section 12052 may also control the display section 12062 so that an icon or the like representing the pedestrian is displayed at a desired position.

[0229] An example of the vehicle control system to which the technology according to the present disclosure is applicable has been described above. The technology according to the present disclosure is applicable to the imaging section 12031 among the above-mentioned configurations. Specifically, the sensor device 10 is applicable to the imaging section 12031. The imaging section 12031 to which the technology according to the present disclosure has been applied flexibly acquires event data and performs data processing on the event data, thereby being capable of providing appropriate driving assistance.

[0230] Further possible implementations of the sensor device 10 are mobile devices 3000 such as cell phones, tablets, smart watches and the like as shown in Fig. 24A or head-mounted displays 4000 as shown in Fig. 24B. Further, the sensor device 10 is useable in augmented and / or virtual reality applications / cameras or in surveillance systems like 360° cameras.

[0231] Note that, the embodiments of the present technology are not limited to the above-mentioned embodiment, and various modifications can be made without departing from the gist of the present technology.

[0232] Further, the effects described herein are only exemplary and not limited, and other effects may be provided.

[0233] Note that, the present technology can also take the following configurations.

[0234] [1] A sensor device (10) comprising: a pixel array (1011) having a plurality of pixels (51) each being configured to receive light and to perform photoelectric conversion to generate an electrical signal indicating the intensity of the received light; a plurality of event detecting sections (52) that are configured to receive the electrical signals from each of the plurality of pixels (51) and to generate event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel (51) above an event threshold; and a selection section (100) that is configured to receive the electrical signals generated by a group (511) of adjacent pixels (51), to determine from the electrical signals at which pixel (51) of the group (511) the largest intensity has been received, and to enable generation of event data for the pixel (51) of the group that did receive the largest intensity while disabling generation of event data for the other pixels (51) of the group. [2] The sensor device (10) according to [1], wherein the electrical signal is a photocurrent generated by a photoelectric conversion element within the pixel (51); and the selection section (100) is configured to determine the largest photocurrent in order to determine the largest intensity and to generate control signals that enable and disable event data generation for the pixels (51) of the group (511).

[0235] [3] The sensor device (10) according to [2], wherein the selection section (100) comprises current mirrors (110) that are configured to receive as inputs the photocurrents input from the pixels (51) of the group (511) into the respective event detecting sections (52) and to provide as outputs replications of these photocurrents, and a winner-take-all circuit (120) that comprises input lines (122) that are configured to receive said replications of photocurrents and output lines (124) that are connected to the respective event detecting sections (52) from which the replications of photocurrents are obtained; and the largest replication of photocurrents triggers an output of an enable signal through the respective output line (124) of the winner-take-all circuit (120) to the event detecting section (52) to which the photocurrent corresponding to the largest replication of photocurrents is provided, while outputting disable signals through the remaining output lines

[0236] [4] The sensor device (10) according to [3], wherein each event detecting section (52) comprises a current-voltage converting section (81) that converts the photocurrent into a voltage based on which voltage event data generation is carried out; the current mirrors (110) are configured to receive as inputs the photocurrents input from the pixels (51) of the group (511) into the respective current-voltage converting sections (81).

[0237] [5] The sensor device (10) according to [4], wherein each event detecting section (52) comprises a subtraction section (83) that receives the voltage from the respective current-voltage converting section (81) and in which the change of intensities of light is determined by detecting a change of the received voltage; and the control signal enables and disables event data generation by enabling and disabling the detection of the change of the received voltages in the subtraction sections (83).

[0238] [6] The sensor device (10) according to [5], wherein the subtraction section (83) comprises a first capacitor (101), a second capacitor (103), an operational amplifier (102), and a switch (104, 105); the first capacitor (101) has a first end that receives the voltage from the respective currentvoltage converting section (81) and a second end connected to an input terminal of the operational amplifier (102); the second capacitor (103) has a first end connected to the input terminal of the operational amplifier (102) and to the second end of the first capacitor (101) and a second end connected to an output terminal of the operational amplifier (102); the switch (104, 105) is configured to electrically connect the first end and the second end of the second capacitor (103) when switched on; the operational amplifier (102) is configured to indicate at its output terminal the change of the voltage received at the first end of the first capacitor (101); and the control signal enables event data generation by switching the switch (104, 105) off and disables event data generation by switching the switch on.

[0239] [7] The sensor device (10) according to any one of [1] to [6], wherein the group (511) of adjacent pixels (51) is a group of N x N pixels (51), with N a natural number larger than 1, preferably with N = 2, or 3.

[0240] [8] The sensor device (10) according to any one of [1] to [7], wherein the sensor device (10) is configured to change a size and / or a location of the group (511) of adjacent pixels (51) within the plurality of pixels (51).

[0241] [9] A method for operating the sensor device (10) according to any one of [1] to [8], the method comprising: at each of the plurality of pixels (51), receiving light to perform photoelectric conversion and generating an electrical signal indicating the intensity of the received light; at the plurality of event detecting sections (52), receiving the electrical signals from each of the plurality of pixels (51) and generating event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel (51) above an event threshold; and at the selection section (100), receiving the electrical signals generated by a group (511) of adjacent pixels (51), determining from the electrical signals at which pixel (51) of the group the largest intensity has been received, and enabling generation of event data for the pixel (51) of the group (511) that did receive the largest intensity while disabling generation of event data for the other pixels (51) of the group (511).

Claims

CLAIMS1. A sensor device comprising: a pixel array having a plurality of pixels each being configured to receive light and to perform photoelectric conversion to generate an electrical signal indicating the intensity of the received light; a plurality of event detecting sections that are configured to receive the electrical signals from each of the plurality of pixels and to generate event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel above an event threshold; and a selection section that is configured to receive the electrical signals generated by a group of adjacent pixels, to determine from the electrical signals at which pixel of the group the largest intensity has been received, and to enable generation of event data for the pixel of the group that did receive the largest intensity while disabling generation of event data for the other pixels of the group.

2. The sensor device according to claim 1, wherein the electrical signal is a photocurrent generated by a photoelectric conversion element within the pixel; and the selection section is configured to determine the largest photocurrent in order to determine the largest intensity and to generate control signals that enable and disable event data generation for the pixels of the group.

3. The sensor device according to claim 2, wherein the selection section comprises current mirrors that are configured to receive as inputs the photocurrents input from the pixels of the group into the respective event detecting sections and to provide as outputs replications of these photocurrents, and a winner-take-all circuit that comprises input lines that are configured to receive said replications of photocurrents and output lines that are connected to the respective event detecting sections from which the replications of photocurrents are obtained; and the largest replication of photocurrents triggers an output of an enable signal through the respective output line of the winner-take-all circuit to the event detecting section to which the photocurrent corresponding to the largest replication of photocurrents is provided, while outputting disable signals through the remaining output lines4. The sensor device according to claim 3, wherein each event detecting section comprises a current-voltage converting section that converts the photocurrent into a voltage based on which voltage event data generation is carried out; the current mirrors are configured to receive as inputs the photocurrents input from the pixels of the group into the respective current-voltage converting sections.

5. The sensor device according to claim 4, wherein each event detecting section comprises a subtraction section that receives the voltage from the respective current-voltage converting section and in which the change of intensities of light is determined by detecting a change of the received voltage; andthe control signal enables and disables event data generation by enabling and disabling the detection of the change of the received voltages in the subtraction sections.

6. The sensor device according to claim 5, wherein the subtraction section comprises a first capacitor, a second capacitor, an operational amplifier, and a switch; the first capacitor has a first end that receives the voltage from the respective current-voltage converting section and a second end connected to an input terminal of the operational amplifier; the second capacitor has a first end connected to the input terminal of the operational amplifier and to the second end of the first capacitor and a second end connected to an output terminal of the operational amplifier; the switch is configured to electrically connect the first end and the second end of the second capacitor when switched on; the operational amplifier is configured to indicate at its output terminal the change of the voltage received at the first end of the first capacitor; and the control signal enables event data generation by switching the switch off and disables event data generation by switching the switch on.

7. The sensor device according to claim 1, wherein the group of adjacent pixels is a group of N x N pixels, with N a natural number larger than 1, preferably with N = 2, or 3.

8. The sensor device according to claim 1, wherein the sensor device is configured to change a size and / or a location of the group of adjacent pixels within the plurality of pixels.

9. A method for operating the sensor device of claim 1, the method comprising: at each of the plurality of pixels, receiving light to perform photoelectric conversion and generating an electrical signal indicating the intensity of the received light; at the plurality of event detecting sections, receiving the electrical signals from each of the plurality of pixels and generating event data that indicate as an event the occurrence of a change of the intensities of light received at the respective pixel above an event threshold; and at the selection section, receiving the electrical signals generated by a group of adjacent pixels, determining from the electrical signals at which pixel of the group the largest intensity has been received, and enabling generation of event data for the pixel of the group that did receive the largest intensity while disabling generation of event data for the other pixels of the group.

Images