Sensor device and method for operating a sensor device

Abstract

A sensor device (10) comprises a vision sensor (1010) that 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. Here, the plurality of pixels (51) comprises at least one first pixel (51R) that is configured to generate electrical signals indicating the intensity of the light received at the first pixel (51R) in a first set of wavelength bands and at least one second pixel (51G) that is arranged adjacent to the first pixel (51R) and configured to generate electrical signals indicating the intensity of the light received at the second pixel (51G) in a second set of wavelength bands that differs from the first set of wavelength bands. The sensor device (10) further comprises an event detection unit (100) that is configured to receive the electrical signals from the first pixel (51R) and the second pixel (51G) and to generate event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel (51R) and the second pixel (51G) above a color difference event threshold.

Description

SENSOR DEVICE AND METHOD FOR OPERATING A SENSOR DEVICEFIELD OF THE INVENTIONThe 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.BACKGROUNDPresently, sensor data obtained in dynamic / event vision sensors, DVS / EVS, are used to obtain temporally highly resolved image streams that might be updated asynchronously. This works well as long as the number of events remains in a regime that allows processing of the event data without a delay that would jeopardize the advantages of the event-based vision sensors. Therefore, improved sensor devices and methods for operating these sensor devices are desirable that mitigate this problem.SUMMARY OF INVENTIONTo this end, a sensor device is provided that comprises a vision sensor 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. Here, the plurality of pixels comprises at least one first pixel that is configured to generate electrical signals indicating the intensity of the light received at the first pixel in a first set of wavelength bands and at least one second pixel that is arranged adjacent to the first pixel and configured to generate electrical signals indicating the intensity of the light received at the second pixel in a second set of wavelength bands that differs from the first set of wavelength bands. The sensor device further comprises an event detection unit that is configured to receive the electrical signals from the first pixel and the second pixel and to generate event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel and the second pixel above a color difference event threshold.Further, a method for operating the above sensor device is provided that comprises generating event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel and the second pixel above a color difference event threshold.In the above, the usual concept of an event-based vision sensor, i.e. to only signal changes of intensities beyond a certain threshold, is further developed by not observing the overall intensity of incoming light, but the differences in the intensities of light of different color, i.e. of different sets of wavelength bands. Only if the difference between intensities of two different colors received at adjacent pixels changes sufficiently with time, an event will be generated. Thus, in comparison to the usual case, where intensity changes of light without color changes generate an event, only changes in the color of light will generate an event. This naturally reduces the number of events while preserving the most relevant information. Accordingly, processing the event data generated by according sensor device will need less processingresources and less time.BRIEF DESCRIPTION OF DRAWINGSFig. 1 is a schematic diagram of a sensor device.Fig. 2 is a schematic block diagram of a sensor section.Fig. 3 is a schematic block diagram of a pixel array section.Fig. 4 is a schematic circuit diagram of a pixel block.Fig. 5 is a schematic block diagram illustrating of an event detecting section.Fig. 6 is a schematic circuit diagram of a current-voltage converting section.Fig. 7 is a schematic circuit diagram of a subtraction section and a quantization section.Fig. 8 is a schematic diagram of a frame data generation method based on event data.Fig. 9 is a schematic block diagram of another quantization section.Fig. 10 is a schematic diagram of another event detecting section.Fig. 11 is a schematic block diagram of another pixel array section.Fig. 12 is a schematic circuit diagram of another pixel block.Fig. 13 is a schematic block diagram of a scan-type sensor device.Fig. 14 is a schematic block diagram of a sensor device.Fig. 15 is a schematic illustration of an event detection unit.Fig. 16 is another schematic illustration of an event detection unit.Fig. 17 is a schematic illustration of the generation of possible difference signals.Figs. 18A and 18B are schematic illustrations of color pixels.Fig. 19 is a schematic process flow of a method for operating a processing device.Fig. 20 is a schematic block diagram of a vehicle control system.Fig. 21 is a diagram of assistance in explaining an example of installation positions of an outside-vehicle information detecting section and an imaging section.Fig. 22A and 22B are schematic illustrations of a mobile device and a head mounted display comprising a sensor device.DETAILED DESCRIPTIONThe present disclosure is directed to mitigating problems related to 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.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.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.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.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.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.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.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.Fig. 2 is a block diagram illustrating a configuration example of the sensor section 21 of Fig. 1.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.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.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.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.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 conversionsection 34 can perform CDS (Correlated Double Sampling) together with pixel signal AD conversion.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).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.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.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.Fig. 3 is a block diagram illustrating a configuration example of the pixel array section 31 of Fig. 2.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.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.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 ofdetecting 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.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.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.Fig. 4 is a circuit diagram illustrating a configuration example of the pixel block 41.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.The pixel 51 includes a photoelectric conversion element 61 and transfer transistors 62 and 63.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.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.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.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) thepixels 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.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.The reset transistor 71, the amplification transistor 72, and the selection transistor 73 include, for example, N-type MOSFETs.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.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.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.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.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.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.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.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.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.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.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.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.Fig. 5 is a block diagram illustrating a configuration example of the event detecting section 52 of Fig. 3.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.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.The buffer 82 buffers photovoltages from the current-voltage converting section 81 and supplies the resultant to the subtraction section 83.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.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.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.Fig. 6 is a circuit diagram illustrating a configuration example of the current-voltage converting section 81 of Fig. 5.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.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.The source of the transistor 93 is grounded.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 thetransistor 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.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.Fig. 7 is a circuit diagram illustrating configuration examples of the subtraction section 83 and the quantization section 84 of Fig. 5.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.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.The operational amplifier 102 has an output terminal connected to the non-inverting input terminal (+) of the comparator 111.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.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 103.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).Qinit = Cl x Vinit (1)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.When a photovoltage on the buffer 82 (Fig. 5) side of the capacitor 101 in the case where the switch 104has 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).Qafter = Cl x Vafter (2)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).Q2 = -C2 x Vout (3)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.Qinit = Qafter + Q2 (4)When Expression (1) to Expression (3) are substituted for Expression (4), Expression (5) is obtained.Vout = -(C1 / C2) x (Vafter - Vinit) (5)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.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.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.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.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.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.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.A = CGiogC 1 / C2 (ZiPhoto_n) (6)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 IxJ.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.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.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 eventdata to the frame data.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.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").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.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.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.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.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.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.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 databy 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.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).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.Fig. 9 is a block diagram illustrating another configuration example of the quantization section 84 of Fig. 5.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.In Fig. 9, the quantization section 84 includes comparators 111 and 112 and an output section 113.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.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.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 notto be the case.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.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.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.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.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.Preferably, the quantization section 84 has a configuration as illustrated in Fig. 9.Fig. 10 is a diagram illustrating another configuration example of the event detecting section 52.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.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.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.The quantizer 440 includes a comparator 441. The comparator 441 corresponds to the comparator 111.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).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.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).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. 2.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.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.Thus, the pixel array section 31 of Fig. 11 is similar to the case of Fig. 3 in that the pixel array section 31includes 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.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.Fig. 12 is a circuit diagram illustrating a configuration example of the pixel block 41 of Fig. 11.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.In this case, the pixel 51 can only include the photoelectric conversion element 61 without the transfer transistors 62 and 63.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.Fig. 13 is a block diagram illustrating a configuration example of a scan type imaging device which may be used as an EVS.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.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.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 maydetermine a selection region on the basis of requests from the pixels 530 in the pixel array section 521.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.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.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, -)).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. In the following it will be described how this basic concept of event-based vision sensors can be extended to color variations.To this end, Fig. 14 illustrates in a schematic and simplified manner a sensor device 10 that comprises a vision sensor 1010 and an event detection unit 100. The vision sensor 1010 and the event detection unit 100 may be arranged at different chips / sensor dies. As illustrated in Fig. 14, the vision sensor 1010 may be located on the sensor die 11 and the event detection unit 100 may be located on the logic die 12. The event detection unit 100 may even be part of a different processor or a different computing device. However, the vision sensor 1010 and the event detection unit 100 may also be located on the same chip.The vision sensor 1010 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.As illustrated in Fig. 14, the plurality of pixels 51 comprises at least one first pixel 5 IRthat is configured to generate electrical signals indicating the intensity of the light received at the first pixel 51R in a first set of wavelength bands and at least one second pixel 51G that is arranged adjacent to the first pixel 51R andconfigured to generate electrical signals indicating the intensity of the light received at the second pixel 51G in a second set of wavelength bands that differs from the first set of wavelength bands. Thus, amongst the pixels 51 of the vision sensor pixels 51R, 51G are present that are sensitive only to specific wavelengths bands / spectra, i.e. that only respond to the reception of light having a particular color (mixture). Here the set of wavelengths bands may be a continuous spectrum or may refer to two or more separated spectra. The vision sensor 1010 may only comprise such color sensitive pixels 51R, 51G. Alternatively, the color sensitive pixels 51R, 51G may only form a subset of all the pixels 51, while other pixels are sensitive to all wavelengths.Here, it should be noted that the concept of a pixel 51 is to be understood such as to mean an element or element group that generates electricals signals by photoelectric conversion only in the respective set of wavelength bands. For example, a color sensitive pixel 51R, 51G may comprise a single photodiode that only converts light of the respective set of wavelength bands. However, color pixel sensitive pixels 51R, 51G may also comprise several photodiodes converting light of parts of the set of wavelength bands. Here, each of the multiple photodiodes may be part of a subpixel, i.e. it may be read out separately, or the multiple photodiodes may generate the electrical signal of the pixel together, e.g. by being connected to a single floating diffusion. In fact, it is not of particular importance how the electric signals indicating the intensities of light in the different sets of wavelength bands are generated. What matters is that intensities of different colors are measured by the different color sensitive pixels 51R, 51G.The electrical signals from the first pixel 51R and the second pixel 51G are forwarded to the event detection unit 100 that is configured to generate event data therefrom that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel 51R and the second pixel 51G above a color difference event threshold. Thus, the event detection unit 100 operates according to the principles of an event-based vision sensor as described above with respect to Figs. 5 to 13. However, instead of operating on the intensity measured by a pixel 51, it operates on the difference of intensities of two different color sensitive pixels 51R, 51G. This means that an event is only generated, if there is a change in color that is sufficiently large. For example, if the first pixel 51R is sensitive to red light and the second pixel 51G is sensitive to green light, an event is generated, if the light received at both pixels at the same point in time changes its color to become redder or greener by a sufficient amount. Thus, the number of events that will be generated will be restricted to only such events that represent a color change. This will reduce the number of events and hence also the processing power and time required for processing the events.Here, it should be noted that the first pixel 51R and the second pixel 51G are arranged adjacent to each other as illustrated in Fig. 14. This ensures that the light received at these pixels can be considered to be the “same” light, if the spatial variations of the observed scene are larger than the resolution of the pixel array 1011. This is in particular ensured if a microlens array 1020 is used that equally focus light on the first and second pixel 51R, 51G. As illustrated in Fig. 14 this microlens array 1020 may comprise to this end a microlens 1021 that covers the first pixels 51R and the second pixel 51G.The adjacent or co-planar arrangement of the first and second pixels 51R, 51G also ensures that thesignals from these pixels do not suffer the problems of stacked color-sensitive pixels that are used e.g. in “Event-Based Pixel Sensitive to Changes of Color and Brightness” by Berner and Delbruck (IEEE Transactions on circuits and systems - I: Regular papers, vol. 58, No. 7, July 2011). There, two pixels that are sensitive to different colors are created by buried double junction. However, due to the stacked arrangement of such photodiodes the obtained electrical signals are biased such that a clear separation of color signals could not be obtained. These problems are mitigated by the adjacent, i.e. co-planar and nonstacked, arrangement of the first and second pixels 51R, 51G that allows for a separated readout of color sensitive intensity signals, and hence for an unbiased difference signal.The difference of the electrical signals generated in the first pixel 51R and the second pixel 51G is generated in a subtraction module 110 that receives the electrical signals of the first pixel 51R and the second pixel 51G as input. Here, the electrical signals may be photocurrents or photovoltages and the subtraction module 110 is configured to respectively generate the difference of these photocurrents or photovoltages in order to determine the differences of the received intensities of light. The configuration of the subtraction module 110 is arbitrary as long as it can generate the difference of the received electrical signals. The subtraction module 110 may also operate in the digital domain, i.e. the difference is computed digitally. The difference between the electrical signals is then fed into an event detection circuit of the event detection unit 100 as e.g. the one described above with reference to Figs. 5 to 13. Here, it should be noted that the subtraction module 110 may be part of the event detection unit 100, may be located on the same chip as the event detection unit 100, but outside of the event detection unit 100 or may be located elsewhere, e.g. on the chip of the vision sensor 1010.Fig. 15 shows a possible implementation of the subtraction of the electrical signals generated by the first pixel 51R and the second pixel 51G. According to the example of Fig. 15 the photocurrents generated by photoelectric conversion within the first pixel 51R and the second pixel 51G are subtracted from each other by an appropriate and in principle known subtraction module 110. The resulting photocurrent is then fed into the event detection section 52 described above with respect with Figs. 5 to 13. Thus, in this example the event detection circuitry is adjusted by inserting a subtraction of different color signal photocurrents before the input to a (standard) event detection section 52. This has the advantage that the subtraction can be performed also outside the event detection section 52, which makes the circuit design more flexible.Alternatively, as illustrated in Fig. 16 the photocurrents generated in each of the first pixel 51R and the second pixel 51G are each provided to a respective current-voltage converting section 81 as e.g. described above with respect to Fig. 6. The resulting photovoltages are then input into an appropriate, in principle known subtraction module 110. The voltage difference is input to a subtraction section 83 and a quantization section 84 e.g. as the ones described above with respect to Figs. 7, 9 and 10. There the temporal variation of the voltage difference is determined and compared with a (color difference) event threshold to determine whether the change in the voltage difference is sufficiently large to trigger an event. As usual in event-based vision sensors, ON and OFF events may be generated as explained with respect to Fig. 9 above, i.e. by using a negative color difference event threshold to detect OFF events and a positive color difference event threshold to detect ON events. Such ON and OFF events indicate in thissetting that one of the two colors that are compared based on the respective electrical signals of the first pixel 51R and the second pixel 51G has gained importance with respect to the other one.If a current-voltage converting section 81 as the one of Fig. 6 is used, a photovoltage that is the logarithm of the photocurrent is generated. Thus, event detection is based on the difference of the logarithms of the photocurrent. This increases the dynamic range of the sensor device 10. Of course, it will also be possible to base the event detection on the difference of the logarithm of photovoltages or to have a linear conversion from photocurrent to photovoltage.As indicated by amplifiers 120 in Fig. 15 the electrical signals might be amplified before subtraction. In particular, the gains of the two amplifiers 120 may be adjusted such that for an illumination of the vision sensor 1010 with constant white light, no event data are generated. This means that for illumination with white light the electrical signals are calibrated such that they do not indicate a difference in the intensities received by the first pixel 51R and the second pixel 51G. Thus, an event will only be generated if a deviation from white light occurs that leads to an increase of the intensity of light within one of the first and second sets of wavelengths bands. In this manner it is ensured that the sensor device 10 reacts on true color changes without being biased to a particular color. Although the amplifiers 120 are only illustrated in Fig. 15 it is understood that photocurrents and photovoltages might be amplified.In Figs. 15 and 16 the electrical signal is directly forwarded to the subtraction module 110. However, the photocurrent from the first pixel 51R and the second pixel 51G can also be mirrored with an according circuitry. This allows to carry out standard event detection as explained above with respect to Figs. 5 to 13 with one of the photocurrent and its mirror, while the other one of the two is used for the generation of color events as described above.Further, all the elements outside the first pixel 51R and the second pixel 51G may be part of the event detection unit 100. They may, however, also be arranged outside the event detection unit 100 either on the same die or on a separate die. How the elements are grouped is irrelevant as long as they can provide the above-described functions.Although the sets of wavelength bands to which the first pixel 51R and the second pixel 51G respond are in principle arbitrary, it is preferable that the first pixel 51R generates an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light, and that the second pixel 51G is configured to generate an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light that is different from the one indicated by the first pixel 51R. Here red light is for example understood as light with a hue angle of 353°, green light is understood as light with a hue angle of 128°, blue light is understood as light with a hue angle of 228°, and yellow light is understood as light with a hue angle of 58°. Additionally or alternatively, red light is understood to be light in a wavelength range of 625 nm to 750 nm, green light is understood to be light in a wavelength range of 500 nm to 565 nm, blue light is understood to be light in a wavelength range of 450 nm to 485 nm, and yellow light is understood to be light in a wavelength range of 565 nm to 590 nm.Thus, the first pixel 51R and the second pixel 51G indicate the intensities of one of the four opponent colors as used in opponent process color theory (see e.g. Michael Foster (1891). A Text-book of physiology. Lea Bros. & Co.). Preferably, the first pixel 51R and the second pixel 51G indicate intensities of opponent color, i.e. red and green or blue and yellow. This allows to operate the sensor device 10 similar to the human eye and to extract scene information in an inherently compressed manner.In the above description reference was made to two different pixels 51R, 51G that generate intensity signals for two different colors / sets of wavelength bands. However, also more than two such pixels may be present. In particular, the plurality of pixels 51 may comprise at least one third pixel 5 IB that is arranged adjacent to either the first pixel 51R or the second pixel 51G and configured to generate an electrical signal indicating the intensity of the light received at the third pixel 5 IB in a third set of wavelength bands that is different from the first and second set of wavelength bands. The event detection unit 100 is then configured to generate event data based on the difference of intensities of light received at the same point in time at any two pixels out of the first pixel 51R, the second pixel 51G, and the third pixel 5 IB. That is events may be generated due to color changes in any of the three color channels observable by the first pixel, 51R, the second pixel 51G, and the third pixel 5 IB.Moreover, as illustrated in Fig. 17, the plurality of pixels 51 may comprise at least one fourth pixel 51Y that is arranged such that the first pixel 51R, the second pixel 51G, the third pixel 5 IB, and the fourth pixel 51Y are arranged in two columns and two rows, the fourth pixel 51Y being configured to generate an electrical signal indicating the intensity of the light received at the fourth pixel 51Y in a fourth set of wavelength bands that is different from the first, second, and third set of wavelength bands. As illustrated by the arrows in Fig. 17 the event detection unit 100 is then configured to generate event data based on the difference of intensities of light received at the same point in time at any two pixels out of the first pixel 51R, the second pixel 51G, the third pixel 5 IB, and the fourth pixel 51Y.This allows to generate events based on various color combinations. Which colors to compare can here also be decided dynamically, e.g. by (digitally) switching on and off circuit paths to the respective event detection units 100. Further, it is also possible to combine signals of the different pixels 51R, 51G, 5 IB, 51Y in order to generate additional color channels. For example, combining a red channel with a yellow channel would generate an orange channel. Of course, it is also possible to provide circuitry that switches off one input to the subtraction module 110. Then, the sensor device 10 operates as a usual colored eventbased vision sensor, i.e. events are generated based on intensity changes of a single color and not based on changes of the differences between intensities of different colors.Further, the adjacent arrangement of the four different color sensitive pixels 51R, 51G, 5 IB, 51Y allows the assumption that the same part of an observed scene, i.e. the same light, is projected onto all four color sensitive pixels 51R, 51G, 5 IB, 51Y. In particular, an arrangement is possible, where all four color sensitive pixels 51R, 51G, 5 IB, 51Y are located under one on-chip lens / microlens. Thus, each super-pixel consisting of the four color sensitive pixels 51R, 51G, 5 IB, 51Y is capable to detect various color changes in a scene. This is particularly useful if the pixel array 1011 consists only of such super-pixels or if such super-pixels are regularly distributed within the pixel array 1011.An important example is also here the case where the four pixels 51R, 51G, 5 IB, 51Y are sensitive to the four opponent colors of the opponent process color theory, i.e. where the first set of wavelength bands are the wavelengths of red light, the second set of wavelength bands are the wavelengths of green light, the third set of wavelength bands are the wavelengths of blue light, and the fourth set of wavelength bands are the wavelengths of yellow light. In this case, events may only be generated for the opposing color pairs red-green and blue-yellow as done in the human retina. However, as stated above, also color changes between other colors may result in the generation of events.The color sensitivity of the first to fourth pixels 51R, 51G, 5 IB, 51Y may be obtained in various, in principle arbitrary manners. As illustrated in Fig. 18A the color sensitive pixels 51R, 51G, 5 IB, 51Y (here represented by the first pixel 51R and the second pixel 51G) may comprise respective color filters R, G that allow only light within the respective set of wavelength bands to enter respective photoelectric conversion stages of the first pixel 51R and the second pixel 51G. That is photodiodes formed within the pixels 51 are in principle sensitive to light in a broad spectrum, like e.g. all visible light. However, the color filters R,G let only the light of interest pass to the photodiodes PD, e.g. red light for the first pixel 51R and green light for the second pixel 51G. This allows easy manufacturing of the sensor device 10.Alternatively, or additionally as illustrated in Fig. 18B the color sensitive pixels (again represented by the first pixel 51R and the second pixel 51G) each comprise one or more photodiodes that are only sensitive to light within the respective set of wavelength bands and that perform the photoelectric conversion. That means that different photodiodes are formed within the pixels, e.g. a photodiode PDR sensitive only to red light and a photodiode PDG sensitive only to green light. This also allows forming different color sensitive photodiodes in one pixel 51. Then, the color sensitivity of the pixel 51 can be dynamically adjusted by selectively reading out signals from different color sensitive photodiodes within a single pixel 51. This allows a flexible operation of the sensor device 10.The above explained functioning of the sensor device 10 described above can be summarized by a method for operating the sensor device 10 that is indicated schematically be the process flow of Fig. 19.Here, as a prerequisite step, at S 101 photoelectric conversion is performed to generate an electrical signal indicating the intensity of the received light. Then, at S 102 with a first pixel 51R electrical signals are generated that indicate the intensity of the light received at the first pixel 51R in a first set of wavelength bands, and at SI 03 with a second pixel 51G that is arranged adjacent to the first pixel 51R electrical signals are generated indicating the intensity of the light received at the second pixel 51G in a second set of wavelength bands that differs from the first set of wavelength bands.The essential step of the method is then to generate event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel 51R and the second pixel 51G above a color difference event threshold.This allows obtaining information about an observed scene with a reduced number of event due to theinherent compression achieved by observing changes in the difference between the intensities of different colors. Accordingly processing power and processing time for processing the resulting event data will be reduced in comparison with standard event-based vision sensors.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.Fig. 20 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.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. 20, 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.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.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 imagedimage. 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.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.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.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.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.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.The sound / image output section 12052 transmits an output signal of at least one of a sound and an imageto 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. 20, 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.Fig. 21 is a diagram depicting an example of the installation position of the imaging section 12031.In Fig. 21, the imaging section 12031 includes imaging sections 12101, 12102, 12103, 12104, and 12105.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.Incidentally, Fig. 21 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.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.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 controlintended for automatic driving that makes the vehicle travel autonomously without depending on the operation of the driver or the like.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.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.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.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. 22A or head-mounted displays 4000 as shown in Fig. 22B. Further, the sensor device 10 is useable in augmented and / or virtual reality applications / cameras or in surveillance systems like 360° cameras.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.Further, the effects described herein are only exemplary and not limited, and other effects may be provided.Note that, the present technology can also take the following configurations.[1] A sensor device (10) comprising: a vision sensor (1010) that 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; wherein the plurality of pixels (51) comprises at least one first pixel (51R) that is configured to generate electrical signals indicating the intensity of the light received at the first pixel (51R) in a first set of wavelength bands and at least one second pixel (51G) that is arranged adjacent to the first pixel (51R) and configured to generate electrical signals indicating the intensity of the light received at the second pixel (51G) in a second set of wavelength bands that differs from the first set of wavelength bands; and the sensor device (10) comprises an event detection unit (100) that is configured to receive the electrical signals from the first pixel (51R) and the second pixel (51G) and to generate event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel (51R) and the second pixel (51G) above a color difference event threshold.[2] The sensor device (10) according to [1], wherein the first pixel (51R) is configured to generate an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light; and the second pixel (51G) is configured to generate an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light that is different from the one indicated by the first pixel (51R).[3] The sensor device (10) according to [1] or [2], further comprising a microlens array (1020) comprising a microlens (1021) that covers the first pixel (51R) and the second pixel (51G).[4] The sensor device (10) according to any one of [1] to [3], wherein the plurality of pixels (51) comprises at least one third pixel (5 IB) that is arranged adjacent to either the first pixel (51R) or the second pixel (51G) and configured to generate an electrical signal indicating the intensity of the light received at the third pixel (5 IB) in a third set of wavelength bands that is different from the first and second set of wavelength bands; and the event detection unit (100) is configured to generate event data based on the difference of intensities of light received at the same point in time at any two pixels out of the first pixel (51R), the second pixel (51G), and the third pixel (5 IB).[5] The sensor device (10) according to [4], wherein the plurality of pixels (51) comprises at least one fourth pixel (51Y) that is arranged such that the first pixel (51R), the second pixel (51G), the third pixel (5 IB), and the fourth pixel (51Y) are arranged in two columns and two rows, the fourth pixel (51Y) being configured to generate an electrical signal indicating the intensity of the light received at the fourth pixel (51Y) in a fourth set of wavelength bands that is different from the first, second, and third set of wavelength bands; and the event detection unit (100) is configured to generate event data based on the difference of intensities of light received at the same point in time at any two pixels out of the first pixel (51R), the second pixel (51G), the third pixel (5 IB), and the fourth pixel (51Y).[6] The sensor device (10) according to [5], wherein the first set of wavelength bands are the wavelengths of red light; the second set of wavelength bands are the wavelengths of green light; the third set of wavelength bands are the wavelengths of blue light; the fourth set of wavelength bands are the wavelengths of yellow light.[7] The sensor device (10) according to any one of [1] to [6], wherein each pixel (51) is configured to generate as electrical signal a photocurrent; and the event detection unit (100) is configured to determine the differences of photocurrents in order to determine the differences of the received intensities of light.[8] The sensor device (10) according to any one of [1] to [7], wherein each pixels (51) is configured to generate as electrical signal a photovoltage; and the event detection unit (100) is configured to determine the differences of photovoltages in order to determine the differences of the received intensities of light.[9] The sensor device (10) according to any one of [1] to [8], wherein each pixel (51) is configured to generate as electrical signal a photocurrent or a photo voltage; and the event detection unit (100) is configured to determine the difference of the received intensities of light based on a difference of logarithms of the photocurrents or based on a difference of logarithms of the photovoltages.

[0010] The sensor device (10) according to any one of [1] to [9], wherein the event detection unit (100) is configured to amplify the electrical signals such that for an illumination of the vision sensor (1010) with constant white light, no event data are generated.

[0011] The sensor device (10) according to any one of [1] to

[0010] , wherein the first pixel (51R) and the second pixel (51G) comprise respective color filters that allow only light within the respective set of wavelength bands to enter respective photoelectric conversion stages of the first pixel (51R) and the second pixel (51G).

[0012] The sensor device (10) according to any one of [1] to

[0011] , wherein the first pixel (51R) and the second pixel (51G) each comprise one or more photodiodes that are only sensitive to light within the respective set of wavelength bands and that perform the photoelectric conversion.

[0013] A method for operating a sensor device (10) according to any one of [1] to

[0012] , the method comprising: generating event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel (51R) and the second pixel (51G) above a color difference event threshold.

Claims

CLAIMS1. A sensor device comprising: a vision sensor 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; wherein the plurality of pixels comprises at least one first pixel that is configured to generate electrical signals indicating the intensity of the light received at the first pixel in a first set of wavelength bands and at least one second pixel that is arranged adjacent to the first pixel and configured to generate electrical signals indicating the intensity of the light received at the second pixel in a second set of wavelength bands that differs from the first set of wavelength bands; and the sensor device comprises an event detection unit that is configured to receive the electrical signals from the first pixel and the second pixel and to generate event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel and the second pixel above a color difference event threshold.

2. The sensor device according to claim 1, wherein the first pixel is configured to generate an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light; and the second pixel is configured to generate an electrical signal indicating the intensity of one of red light, green light, blue light, and yellow light that is different from the one indicated by the first pixel.

3. The sensor device according to claim 1, further comprising a microlens array comprising a microlens that covers the first pixel and second pixel.

4. The sensor device according to claim 1, wherein the plurality of pixels comprises at least one third pixel that is arranged adjacent to either the first pixel or the second pixel and configured to generate an electrical signal indicating the intensity of the light received at the third pixel in a third set of wavelength bands that is different from the first and second set of wavelength bands; and the event detection unit is configured to generate event data based on the difference of intensities of light received at the same point in time at any two pixels out of the first pixel, the second pixel, and the third pixel.

5. The sensor device according to claim 4, wherein the plurality of pixels comprises at least one fourth pixel that is arranged such that the first pixel, the second pixel, the third pixel, and the fourth pixel are arranged in two columns and two rows, the fourth pixel being configured to generate an electrical signal indicating the intensity of the light received at the fourth pixel in a fourth set of wavelength bands that is different from the first, second, and third set of wavelength bands; and the event detection unit is configured to generate event data based on the difference ofintensities of light received at the same point in time at any two pixels out of the first pixel, the second pixel, the third pixel, and the fourth pixel.

6. The sensor device according to claim 5, wherein the first set of wavelength bands are the wavelengths of red light; the second set of wavelength bands are the wavelengths of green light; the third set of wavelength bands are the wavelengths of blue light; the fourth set of wavelength bands are the wavelengths of yellow light.

7. The sensor device according to claim 1, wherein each pixel is configured to generate as electrical signal a photocurrent; and the event detection unit is configured to determine the differences of photocurrents in order to determine the differences of the received intensities of light.

8. The sensor device according to claim 1, wherein each pixels is configured to generate as electrical signal a photovoltage; and the event detection unit is configured to determine the differences of photovoltages in order to determine the differences of the received intensities of light.

9. The sensor device according to claim 1, wherein each pixel is configured to generate as electrical signal a photocurrent or a photovoltage; and the event detection unit is configured to determine the difference of the received intensities of light based on a difference of logarithms of the photocurrents or based on a difference of logarithms of the photovoltages.

10. The sensor device according to claim 1, wherein the event detection unit is configured to amplify the electrical signals such that for an illumination of the vision sensor with constant white light, no event data are generated.

11. The sensor device according to claim 1, wherein the first pixel and the second pixel comprise respective color filters that allow only light within the respective set of wavelength bands to enter respective photoelectric conversion stages of the first pixel and the second pixel.

12. The sensor device according to claim 1, wherein the first pixel and the second pixel each comprise one or more photodiodes that are only sensitive to light within the respective set of wavelength bands and that perform the photoelectric conversion.

13. A method for operating a sensor device according to claim 1, the method comprising: generating event data that indicate as an event the occurrence of a change of the difference of the intensities of light received at the same point in time by the first pixel and the second pixel above acolor difference event threshold.

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