CN114827450A

CN114827450A - Analog image sensor circuit, image sensor device and method

Info

Publication number: CN114827450A
Application number: CN202111397742.9A
Authority: CN
Inventors: 吴志桓; 姚文翰
Original assignee: Pixart Imaging Inc
Current assignee: Pixart Imaging Inc
Priority date: 2021-01-18
Filing date: 2021-11-19
Publication date: 2022-07-29
Anticipated expiration: 2041-11-19
Also published as: CN114827450B

Abstract

The invention discloses a method for simulating an image sensor circuit, which comprises the following steps: providing an event camera comprising pixel units; sensing a current pixel value of the pixel unit by using an event camera to detect whether the pixel value is changed; when the pixel value changes, the event camera is used to trigger the digital processing circuit in the power saving mode and transmit the information of the pixel value to the digital processing circuit. The invention can save more electric power, avoid the consumption, simultaneously avoid the image loss and reduce the calculation amount. The invention also provides a related analog image sensor circuit, an image sensor device and a method.

Description

Analog image sensor circuit, image sensor device and method

Technical Field

The present application relates to an image monitoring mechanism, and more particularly, to an analog image sensor circuit, an image sensor device and a corresponding method.

Background

Referring to fig. 1, fig. 1 is a schematic diagram of a monitoring system 50 in the prior art. The monitoring system 50 includes a passive sensor 52 electrically connected to an external host 56 and an image sensing device 54. The passive sensor 52 may send a trigger signal to the external host 56 when detecting a temperature change, and the external host 56 is awakened and activates the image sensor 54 by the trigger signal, so that the image sensor 54 may perform exposure adjustment after activation, and then start to acquire a monitoring image or record a monitoring video. Therefore, even if the passive sensor 52 senses a temperature change, the image sensor 54 still needs to wait for the transmission of the trigger signal to be completed, the wake-up waiting time of the external host 56 and the image sensor 54, and the exposure adjustment time of the image sensor 54 to elapse before the monitoring image can be acquired, so the monitoring system 50 cannot immediately record the monitoring video when the passive sensor 52 senses an abnormal condition.

Disclosure of Invention

It is therefore an object of the present invention to disclose an analog image sensor circuit, an image sensor device and a corresponding method to solve the above-mentioned problems.

According to an embodiment of the present application, an analog image sensor circuit is disclosed. The analog image sensor circuit is configured to be externally coupled to a digital processing circuit configured to perform a motion detection. The analog image sensor circuit comprises an event camera which comprises at least one pixel unit. The event camera is used for sensing at least one current pixel value of the at least one pixel unit to detect whether the at least one pixel value changes. When the at least one pixel value changes, the event camera triggers the digital processing circuit in a power-saving mode and transmits information of the at least one pixel value to the digital processing circuit.

According to an embodiment of the present application, an image sensor device is disclosed. The image sensor device comprises the analog image sensor circuit and the digital processing circuit. The digital processing circuit generates a current data frame using the information of the at least one pixel value and the last data frame stored in the digital processing circuit.

According to an embodiment of the present application, a method for simulating an image sensor circuit for external coupling to a digital processing circuit for performing a motion detection is disclosed. The method comprises the following steps: providing an event camera comprising at least one pixel unit; sensing a current at least one pixel value of the at least one pixel unit by using the event camera to detect whether the at least one pixel value is changed; when the at least one pixel value changes, the event camera is used to trigger the digital processing circuit in a power-saving mode and transmit information of the at least one pixel value to the digital processing circuit.

According to an embodiment of the present application, a method of an image sensor device is disclosed. The method comprises the following steps: providing a digital processing circuit externally coupled to the image sensor device to perform a motion detection; and generating a current data frame using the information of the at least one pixel value and the last data frame stored in the digital processing circuit.

Drawings

Fig. 1 is a schematic diagram of a monitoring system in the prior art.

Fig. 2 is a schematic diagram of a motion detection device according to an embodiment of the invention.

Fig. 3 is a flowchart of a motion detection method applicable to a motion detection apparatus according to an embodiment of the present invention.

Fig. 4 is a flowchart of a motion detection method applied to a motion detection device according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of the change in the frame rate exhibited by the image capturing unit according to the foregoing embodiment of the present invention.

Fig. 6 is a functional block diagram of an intelligent motion detection device according to a first embodiment of the invention.

Fig. 7 is a process diagram of the intelligent motion detection device according to the first embodiment of the invention.

Fig. 8 is a functional block diagram of an intelligent motion detection device according to a second embodiment of the present invention.

Fig. 9 is a process diagram of an intelligent motion detection device according to a second embodiment of the invention.

Fig. 10 is a functional block diagram of an intelligent motion detection device according to a third embodiment of the present invention.

Fig. 11 is a process diagram of an intelligent motion detection device according to a third embodiment of the invention.

FIG. 12 is a flowchart of a determining method according to an embodiment of the present invention.

Fig. 13 is a block diagram of a monitoring system according to an embodiment of the present application.

FIG. 14 is a schematic illustration of three different operational scenarios of portions or elements of the monitoring system of FIG. 13.

FIG. 15 is a diagram illustrating two different operations performed by the digital processing circuit of FIG. 13 to update and generate data of a current frame.

Fig. 16 is a flow chart illustrating the operation of the smart motion detector just entering the normal mode according to an embodiment of the present application.

Wherein the reference numerals are as follows:

50 prior art monitoring system

52 prior art passive sensor

54 prior art image sensing device

56 prior art external host

60. 60' movement detection device

62 passive sensor

64 external host

66 image acquisition unit

68 arithmetic processor

70 memory

72 light emitting unit

80. 80 ', 80' intelligent motion detection device

82 memory module

84 processor

86. 86 ', 86' sensing module

88 external storage module

90 comparator

92 passive sensor

I1 prestore images

I2 real-time image

1300 monitoring system

1301 image sensor device

1305 analog image sensor

1306 event camera

1310 digital processing circuit

1311. 1316 Picture buffer

1312 intelligent movement detector

1315 backend system device

1317 external processor

Detailed Description

Referring to fig. 2, fig. 2 is a schematic diagram of a motion detection device 60 according to an embodiment of the invention. The motion detection device 60 can be collocated with the passive sensor 62 and the external host 64 to provide the preferred intelligent motion detection function. The motion detection device 60 is electrically connected between the passive sensor 62 and the external host 64. The passive sensor 62 is used to sense whether a specific condition occurs, such as a living body passing through the monitoring area or a door opening in the monitoring area, so as to trigger the movement detection device 60 to analyze whether an event meeting a standard exists in the specific condition, such as the event sensed by the passive sensor 62 may be identified as an expected object. After the event is confirmed, the motion detection device 60 sends relevant data to the external host 64 to determine whether to activate a security alarm.

In a possible implementation aspect, the passive sensor 62 may be a temperature sensor, such as an infrared sensor, and the motion detection device 60 may be selectively switched between the power saving mode and the wake-up mode. The passive sensor 62 does not sense the temperature change when the monitored area is in a normal state, and the mobile detection device 60 is kept in the power saving mode; when an abnormal specific condition occurs in the monitoring area, such as the passage of a living body, the passive sensor 62 can detect the temperature change and generate a trigger signal for switching the motion detection device 60 from the power saving mode to the wake-up mode.

The movement detection device 60 may include an image acquisition unit 66, an arithmetic processor 68, a memory 70, and a light emitting unit 72. The arithmetic processor 68 may drive the image acquisition unit 66 to remain in the power saving mode or the wake-up mode, and further may also drive the image acquisition unit 66 to selectively acquire a low-quality and high-quality monitor image. In a possible implementation, the light-emitting unit 72 is only activated to provide supplementary lighting when the image-capturing unit 66 captures an image, which can save energy consumption and improve the quality of the image captured by the image-capturing unit 66.

The image capturing unit 66 can operate in the power saving mode at a low frame rate to capture the background image, and in the wake-up mode at a high frame rate to capture the multiple monitoring images. The background image may be a low quality image and may be used as a basis for automatic exposure adjustment by the image capture unit 66. The monitor image may include a low quality first monitor image and a high quality second monitor image, wherein the first monitor image is provided to the arithmetic processor 68 to identify whether the event has occurred; the second monitored image is provided to the external host 64 to determine whether to activate a security alarm. The monitor image acquired by the image acquisition unit 66 may be stored in the memory 70 and the high quality monitor image may be further transmitted to the external host 64.

In this embodiment, the monitoring system first detects whether an object passes through the monitoring area by using the passive sensor 62, and then analyzes whether the passing object meets a default condition (e.g., an event meeting a standard) by using the movement detection device 60. If there is a passing object in the field of view of the passive sensor 62 and the passing object is recognized to be in accordance with a specific situation, the passive sensor 62 switches the movement detection device 60 to the wake-up mode, and the movement detection device 60 determines whether the passing object is an expected object (e.g., a pedestrian); if the passing object is determined to be a pedestrian, the movement detection device 60 activates the external host 64, and the external host 64 starts to recognize the object in the monitored image and performs one or more of the following operations: selecting whether to switch the mobile detection device 60 to the video recording mode, requesting the mobile detection device 60 to transmit the monitoring video outwards, instructing the mobile detection device 60 to issue an alarm, turning off the mobile detection device 60, or waking up another mobile detection device 60' electrically connected to the external host 64.

Referring to fig. 3, fig. 3 is a flowchart of a motion detection method applicable to the motion detection device 60 according to an embodiment of the present invention. First, steps S200 and S202 are executed to start the monitoring system, and the passive sensor 62 is used to detect the object within the field of view. If the passive sensor 62 does not detect a temperature change, step S204 is executed to maintain the image capturing unit 66 in the power saving mode; if the passive sensor 62 detects a temperature change, step S206 is executed to enable the passive sensor 62 to transmit a trigger signal to switch the image capturing unit 66 from the power saving mode to the wake-up mode. Next, steps S208 and S210 are executed, the light-emitting unit 72 is activated according to the ambient brightness, and the image obtaining unit 66 obtains the (low quality) first monitoring image, and the processor 68 simply analyzes the first monitoring image to determine whether to activate the external host 64.

In one embodiment, the image obtaining unit 66 obtains the low-quality monitoring image by using a part of pixels, for example, dividing a pixel array into a plurality of 2 × 2 pixel blocks, and obtaining the image by using one pixel in each pixel block. In other possible embodiments, the image obtaining unit 66 obtains the image by using all pixels, divides all pixels into a plurality of pixel blocks (e.g. a 2 × 2 pixel block), and combines the values of all pixels in each pixel block to obtain the block value, so as to generate the low-quality monitoring image according to the plurality of block values.

In step S210, the calculation processor 68 preferably analyzes a specific region of interest in the first monitored image to determine whether to activate the external host 64, wherein the size of the specific region of interest is smaller than that of the first monitored image, so that the calculation processor 68 can obtain the image analysis result quickly due to less data processing amount of the region of interest. Setting the first monitor image as a low-quality monitor image helps to speed up the image analysis of a specific region of interest. The position and size of the region of interest are preferably preset by the user; for example, when the first monitoring image has a gate and a window, and the region of interest only covers the pattern of the gate, the image analysis result can be prevented from being influenced by the swinging of the leaf shadow outside the window, or the region of interest can cover the edge of the window, so as to detect whether a thief climbs the window and simultaneously prevent the image analysis result from being influenced by the shadow of the person at the door. The position and size of the region of interest may further vary as a result of the image analysis. However, the calculation processor 68 may also analyze the whole region in the first monitored image to perform the step S210, and the variation depends on the design requirement. The foregoing image analysis technique may be accomplished by identifying a pattern contour within the monitored image, comparing feature points of the monitored image, and selectively analyzing intensity variations of the monitored image.

When the object does not meet the default condition, for example, the passing object in the monitored image is an animal but not a human, step S212 is executed if the external host 64 is not activated, and the image capturing unit 66 can be actively (automatically) or passively (according to the external command generated by the analysis result of the monitored image) turned off to return to the power saving mode. If the object meets the default condition, that is, the passage in the monitored image is an unauthorized human, step S214 is executed to start the external host 64, and the image obtaining unit 66 starts to obtain a second monitored image with high quality; the second monitor image may be in still image format or continuous video format and stored in the memory 70. Then, step S216 is executed to enable the external host 64 to receive the second monitoring image, and the external host 64 precisely identifies the object in the second monitoring image by using the image recognition algorithm.

When the second monitoring image does not meet the predetermined threshold, i.e. the object is not an unauthorized human, step S218 is executed to actively or passively turn off the motion detection device 60 to save energy. If the second monitoring image meets the predetermined threshold and the object is defined as an unauthorized human, step S220 is executed to enable the external host 64 to switch the mobile detection device 60 to the recording mode, the mobile detection device 60 can upload the monitoring video for backup, and other mobile detection devices 60' can be woken up at the same time to provide comprehensive monitoring. Therefore, the passive sensor 62 does not directly start the external host 64 when detecting the object, the motion detection device 60 wakes up by the trigger of the passive sensor 62 to obtain the first monitored image, and then the external host 64 determines whether to start according to the low-quality image analysis result of the first monitored image obtained by the motion detection device 60.

The motion detection device 60 starts to acquire the second monitoring image after the external host 64 is started. The external host 64 must wait for a period of time to wake up other mobile detection devices, and the second monitoring image can record any suspicious object occurring in the monitoring area before the other mobile detection devices are woken up, i.e. the monitoring system will not miss the suspicious object after the passive sensor 62 detects the abnormality and before the other mobile detection devices are woken up. The mobile detection device 60 determines the existence of the object by using the low-quality first monitoring image, and the related analysis and determination of the existence is only simple operation and may be influenced by noise interference; the external host 64 further analyzes the precise movement detection of the object using the high quality second monitor image, for example, by using facial recognition techniques.

The present invention further provides real-time exposure adjustment functions to enable the motion detection device 60 to have a preferred operating performance. Please refer to fig. 4 and 5. Fig. 4 is a flowchart of a movement detection method applied to the movement detection device 60 according to another embodiment of the present invention, and fig. 5 is a schematic diagram of a change in the frame rate shown by the image capturing unit 66 according to the previous embodiment of the present invention. In this embodiment, the steps having the same numbers as those in the previous embodiment have the same contents, and thus are not described in detail. If the passive sensor 62 does not wake up the motion detection device 60, step S205 can be executed after step S202, and the image capturing unit 66 is periodically switched to the wake-up mode to operate at a low frame rate, so that the image capturing unit 66 in the wake-up mode can perform exposure adjustment and simultaneously capture a low-quality background image. If the motion detection device 60 is awake, step S207 can be executed after step S206, and the image capturing unit 66 is switched to the awake mode to operate at the high image rate; at this point, the image capture unit 66 may still obtain a low quality monitor image that is used to determine whether to activate the external host 64 as compared to the background image.

For example, as shown in fig. 5, the image capturing unit 66 may obtain a background image every second and perform the exposure adjustment function when the passive sensor 62 has not triggered the motion detection device 60, that is, obtain the background images at time points T1, T2, T3 and T4, respectively, and the exposure parameters of the image capturing unit 66 can be adjusted accordingly in real time. When the passive sensor 62 triggers the motion detection device 60 at the time point T5 and enters the wake-up mode, the motion detection device 60 can obtain the first monitor image at a frame rate of 30 frames per second, and since the exposure parameters of the latest background image (obtained at the time point T4) are equivalent to the exposure parameters of the first monitor image obtained at the time point T5, the image obtaining unit 66 in the wake-up mode does not need to perform exposure adjustment any more, and can still obtain the preferred monitor image with the proper exposure parameters in real time.

In summary, the movement detection device of the present invention is electrically connected between the passive sensor and the external host, and the movement detection device can start the external host after the passive sensor switches the movement detection device from the power saving mode to the wake-up mode. When the mobile detection device is in the power saving mode, the mobile detection device can be awakened at intervals when operating in the mode with low frame rate, or exposure parameters are adjusted in the power saving mode to obtain a background image; when the mobile detection device is in the wake-up mode, the mobile detection device operates at a high frame rate to obtain a low quality monitoring image. The mobile detection device firstly executes simple image analysis by utilizing the interesting region of the low-quality monitoring image and judges whether an external host is started or not; after the external host is started, the mobile detection device obtains and stores the high-quality monitoring image, so that the external host can perform accurate image analysis according to the high-quality monitoring image, and related application programs can be started conveniently. The mobile detection device can effectively shorten the starting time of the monitoring system without consuming time to wait for the awakening time of an external host and the exposure adjustment time of the mobile detection device.

Referring to fig. 6 and 7, fig. 6 is a functional block diagram of an intelligent motion detection device 80 according to a first embodiment of the present invention, and fig. 7 is a process diagram of the intelligent motion detection device 80 according to the first embodiment of the present invention. The intelligent motion detection device 80 may include a memory module 82, a processor 84, and a sensing module 86. The memory module 82, the processor 84, and the sensing module 86 may be three separate components or may be one or two integrated components. The sensing module 86 may be directly coupled to the memory module 82 and further electrically connected to the processor 84. The sensing module 86 may include a plurality of light detecting pixels arranged in a two-dimensional manner for obtaining an image. The processor 84 may be switched between a sleep mode and a wake mode for image processing of the images acquired by the sensing module 86 to identify specific events within the acquired images, such as unexpected objects appearing in the acquired images.

The sensing module 86 can pre-store (i.e., read from or write to) the memory module 82 or directly transmit the acquired image to the processor 84 according to the operation mode of the processor 84 or the warning signal generated by the motion detection result. The image capacity of the memory module 82 has a default value, and if the memory module 82 is full but a new image is still to be stored in advance, all or part of the previous image is removed to move out of the space for storing the new image. In addition, the image processed by the processor 84 and the pre-stored image stored in the memory module 82 can be transmitted to the external storage module 88, and the external storage module 88 is electrically connected to the intelligent motion detection device 80.

As shown in the first embodiment of fig. 7, the processor 84 operates in the sleep mode when the intelligent motion detection device 80 is not activated. The sensing module 86 may include a comparator 90 for generating a warning signal when movement of an object is monitored. When the processor 84 is operating in the sleep mode, the sensing module 86 may continuously or intermittently acquire a plurality of images, for example, five images per second, which are stored in the memory module 82 in advance. At the same time, comparator 90 reads one or more pre-stored images I1 from plurality of pre-stored images I1 and compares them to the reference image. If the intensity variation between the pre-stored image I1 and the reference image is below the default value, the processor 84 remains in the sleep mode and the comparator 90 reads the next pre-stored image I1 and compares it to the reference image. If the intensity variation between the pre-stored image I1 and the reference image exceeds a predetermined value, the comparator 90 may generate a warning signal to wake up the processor 84 and pre-store the image obtained by the sensing module 86 in the memory module 82. Thus, the warning signal is used to switch the processor 84 from the sleep mode to the wake mode.

The comparator 90 of the present invention can compare the pre-stored image I1 with the reference image in a variety of ways, for example, the comparator 90 can compare the pre-stored image I1 with the entire image range of the reference image or only compare a partial image range. The comparator 90 can compare the intensity sums of all the pixels or the intensity sums of some of the pixels; alternatively, the comparator 90 may compare each pixel in the entire image range, or only compare the intensity of a portion of the image range.

When the processor 84 is in the wake-up mode, the real-time image I2 obtained by the sensing module 86 can be directly transmitted to the processor 84 for digital image processing, and is not stored in the memory module 82. The processor 84 in the wake mode may alternatively process the real-time image I2 and receive the pre-stored image I1 from the memory module 82, or receive the pre-stored image I1 after the processing of the real-time image I2 is completed. The image processing of the real-time image I2 can be prioritized over the image processing of the pre-stored image I1, so the intelligent motion detection device 80 can focus on processing real-time situations within the monitoring range. The image processing of the pre-stored image I1 may be started when the image processing of the real-time image I2 is completed or paused. If the processor 84 is capable of handling huge amount of data, the real-time image I2 and the pre-stored image I1 can be alternatively processed, i.e. the intelligent motion detection device 80 can provide the detection results of the current time period and the previous time period.

In some embodiments, the pre-stored image obtained by the sensing module 86 when the processor 84 operates in the sleep mode may be pre-stored in the memory module 82, and the image obtained by the sensing module 86 when the processor 84 operates in the wake mode may be transmitted to the processor 84. In other embodiments, the processor 84 and the sensing module 86 may be turned off in the non-operating mode; when the intelligent motion detection device 80 receives the trigger signal, the sensing module 86 can acquire the image and directly transmit the image to the memory module 82, and then the processor 84 can send a request to the sensing module 86 to receive the acquired image. The trigger signal may be an alert notification generated by an external unit or an alert notification generated by a built-in unit of the intelligent motion detection apparatus 80.

In addition, either or both of the image quality and the frame rate of the sensing module 86 may be changed as the processor 84 operates in the sleep mode or the wake-up mode. For example, when the processor 84 is operating in the sleep mode, the sensing module 86 may obtain an image with low quality or low frame rate for comparison with the reference image, which may help to save transmission bandwidth and storage capacity. If the intensity between the low quality or low frame rate image and the reference image exceeds a predetermined value, an alarm signal is generated, so that the sensing module 86 can start to acquire a high quality or high frame rate image for pre-storage in the memory module 82, and switch the processor 84 to the wake-up mode at the same time. Then, the pre-stored high quality image or the pre-stored high frame rate image in the memory module 82 can be transmitted to the processor 84 when the processor 84 operates in the wake-up mode, so that the intelligent motion detection device 80 does not lose important image information before the processor 84 switches to the wake-up mode.

Referring to fig. 8 to 11, fig. 8 is a functional block diagram of an intelligent motion detection device 80 'according to a second embodiment of the present invention, fig. 9 is a process diagram of the intelligent motion detection device 80' according to the second embodiment of the present invention, fig. 10 is a functional block diagram of an intelligent motion detection device 80 ″ according to a third embodiment of the present invention, and fig. 11 is a process diagram of the intelligent motion detection device 80 ″ according to the third embodiment of the present invention. In the second embodiment and the third embodiment, the elements having the same numbers as those of the first embodiment have the same structures and functions, and the description thereof will not be repeated.

In one possible embodiment, the intelligent motion detection device 80 'may include a memory module 82, a processor 84, a sensing module 86', and a passive sensor 92. The passive sensor 92 may electrically connect the processor 84 and the sensing module 86'. When the passive sensor 92 does not detect any abnormal phenomenon, the sensing module 86' is turned off and the processor 84 is maintained in the sleep mode. When the passive sensor 92 detects the movement of the object, the passive sensor 92 generates an alarm signal, and the alarm signal can be used to activate the sensing module 86' and switch the processor 84 from the sleep mode to the wake mode. While the processor 84 is still operating in the sleep mode, the sensing module 86' can retrieve the pre-stored image I1 and transmit the pre-stored image I1 to the memory module 82. If the processor 84 is operating in the wake-up mode, the sensing module 86' can acquire the real-time image I2 and transmit the real-time image I2 to the processor 84, and the pre-stored image I1 in the memory module 82 can also be transmitted to the processor 84 accordingly.

The intelligent motion detection device 80 'may have a non-operational mode in which the processor 84 and the sensing module 86' may be turned off. When the passive sensor 92 detects the movement of the object and generates a warning signal, the warning signal triggers the sensing module 86 'to start the sensing module 86' to acquire the pre-stored image and transmit the pre-stored image to the memory module 82. The processor 84 may then be switched to the wake mode and send a request to the sensor module 86' for subsequent operations to receive the pre-stored image.

In other embodiments, the intelligent motion detection device 80 "may include a memory module 82, a processor 84, a sensing module 86" having a comparator 90, and a passive sensor 92. The passive sensor 92 may trigger the sensing module 86 "when an anomaly is detected. The triggering sensing module 86 "may retrieve the pre-stored image I1 and transmit it to the memory module 82, and the comparator 90 may compare the pre-stored image I1 with the reference image to determine whether to switch the mode of the processor 84. The comparator 90 is used to identify anomalies. If the intensity variation between the pre-stored image I1 and the reference image is below the default value, the anomaly may be caused by noise, and the processor 84 will not be awakened; if the intensity between the pre-stored image I1 and the reference image varies beyond a predetermined value, an anomaly may indicate that someone or something has invaded the monitoring range of the intelligent motion detection device, so that the processor 84 can be switched to the wake-up mode for recording. When the processor 84 is operating in the wake-up mode, the real-time image I2 captured by the sensing module 86 ″ and the pre-stored image I1 in the memory module 82 may be transmitted to the processor 84 and then further transmitted to the external storage module 88 for digital image processing.

Referring to fig. 12, fig. 12 is a flowchart of a determining method according to an embodiment of the invention. The determination method described in fig. 12 can be applied to the intelligent motion detection device shown in fig. 6 to 11. First, step S800 and step S802 are executed to start the determination method to monitor the movement of the object, and the monitoring function can be executed by the

sensing modules

86, 86' and 86 ″ or the passive sensor 92. If no exception is detected, step S804 is performed to maintain the processor 84 in the sleep mode. If the movement of the object is detected, step S806 and step S808 are executed to generate a warning signal to enable the processor 84, and the image is obtained through the

sensing modules

86, 86', and 86 ″. When the processor 84 is not operating in the wake mode, step S810 is executed to enable the

sensing modules

86, 86', and 86 ″ to generate the pre-stored image I1 in the memory module 82. When the processor 84 operates in the wake mode, step S812 and step S814 are executed, the real-time image I2 is generated by the

sensing modules

86, 86', and 86 ″ and both the pre-stored image I1 and the real-time image I2 can be transmitted to the processor 84.

Next, after the step S816 is executed, the processor 84 may analyze the real-time image I2 obtained by the

sensing module

86, 86 ', or 86 ″ after the capturing function of the

sensing module

86, 86', or 86 ″ is initiated. The

sensing modules

86, 86', and 86 "are not triggered, perhaps by the sudden disappearance of an object or other special condition, and step S818 may be performed to analyze the prestored image I1 in the memory module 82 via the processor 84. It should be noted that the processor 84 not only performs the image processing on the real-time image I2 before the pre-stored image I1, but also alternatively performs the image processing on the pre-stored image I1 and the real-time image I2 alternately according to the actual needs of the user and the effective operation performance.

In summary, the warning signal can be generated by the sensing module or a passive sensor (e.g., a thermal sensor, an accelerometer, or a gyroscope). The warning signal is used for triggering the pre-storage function of the sensing module and the mode switching function of the processor. When the warning signal is received, the sensing module can accordingly acquire the pre-stored image at the first time, and the pre-stored image is transmitted to the memory module. After a period of time has elapsed, after the processor has switched from the sleep mode to the awake mode, the processor receiving the warning signal may send a request associated with the real-time image and the pre-stored image to the sensing module at a second time. The second time is later than the first time, the image processing is carried out on the image prestored in the memory module after the first time, and the real-time image is directly transmitted to the processor for image processing and is not stored in the memory module. Compared with the prior art, the intelligent motion detection device and the related judgment method thereof can obtain the detection image without waiting for the wake-up processor, and can effectively shorten the starting time of the intelligent motion detection device.

Referring to fig. 13 and 14 in combination, fig. 13 is a block diagram of a monitoring system 1300 according to an embodiment of the present disclosure, and fig. 14 is a diagram of three different operation schemes of parts or elements of the monitoring system 1300 in fig. 13. As shown in fig. 13, the monitoring system 1300 includes three parts, namely, an Integrated Circuit (IC) part or component, a digital IC part or component, and a backend system device. In other embodiments, the analog integrated circuit portion or element and the digital integrated circuit portion or element may be integrated together to implement an image sensor device 1301, wherein the image sensor device 1301 may also be a single integrated circuit. That is, the image sensor device 1301 can be divided into an analog part (i.e., the analog integrated circuit part or element) and a digital part (i.e., the digital integrated circuit part or element).

The analog integrated circuit portion or element is a collection of analog circuits or elements, such as may be (or include) an analog image sensor circuit, such as an analog image sensor 1305 including an event camera 1306, where the event camera 1306 may also be referred to as an event sensor and includes at least one pixel element (e.g., at least one active pixel element), i.e., one or more pixel elements (e.g., pixels or sub-pixels). It should be noted that, in practice, an event camera unit/circuit may include a pixel unit and is used to report a change in brightness when the brightness changes and not to report when the brightness does not change. That is, the event camera 1306 is used to detect whether one or more brightness changes have occurred in one or more pixel cells.

The digital integrated circuit portion or component is a collection of digital circuits or components, which may be (or include) a digital processing circuit that includes a first image register 1311 and a motion detector, such as a Smart Motion Detector (SMD) 1312. When the event camera 1306 sends information about pixel images or changes in their values, the smart motion detector 1312 can use the pixel level information to generate frame data (i.e., a frame level image) and can detect whether motion has occurred. If it determines that a motion has occurred, the smart motion detector 1312 can generate an alarm signal to the back-end system 1315. Conversely, if no motion occurs, the smart motion detector 1312 does not generate the warning signal. The smart motion detector 1312 can accurately detect whether there is an actual motion and can filter out some unwanted image disturbances, such as moving images of swaying leaves or swaying grass; this is not a limitation of the present application.

Upon receiving a warning signal sent from the digital processing circuit 1310, the back-end system 1315 is configured to receive the video stream (i.e., frames) from the digital processing circuit 1310 and, for example, to initiate a video recording operation. The back-end system 1315 includes a second image register 1316 and an external processor 1317 externally coupled to the image sensor device (i.e., the analog integrated circuit portion or component and the digital integrated circuit portion or component).

The activation speed or time of the event camera 1306 (or the analog image sensor circuit 1305) is substantially faster than the activation speed or time of the smart motion detector 1312 (or the digital processing circuit 1310), and also substantially faster than the activation speed or time of the external processor 1317 (or the backend system device 1315). In one embodiment, if there are no pixel changes, only the event camera 1306 (or only the analog image sensor circuit 1305) is powered, while other circuits (i.e., the digital processing circuit 1310 and the backend system 1315) are powered down or left in a power saving mode, such as at a low operating frequency to save more power. Once the event camera 1306 (or the analog image sensor circuit 1305) detects a pixel value change, the smart motion detector 1312 wakes up by a trigger signal sent from the analog image sensor circuit 1305 to perform the motion detection. Only when the motion detection result indicates that an actual motion occurs, the external processor 1317 in the back-end system 1315 is woken up by a trigger signal sent from the digital processing circuit 1310 to perform additional video processing and/or video recording operations. In other embodiments, if the event camera 1306 includes multiple pixels, then "no pixel change" may refer to a condition where the number of pixels that actually have a pixel value change is below a first particular threshold, and "pixel value change" may refer to a condition where the number of pixels that actually have a pixel value change exceeds a second particular threshold.

If the pixel values change before the motion detector 1312 is fully awakened, one or more pixel values sensed by the image sensor circuit 1305 are stored in the first image register 1311 and are transmitted or forwarded to the motion detector 1312 once the motion detector 1312 is fully awakened to receive the sensed one or more pixel values. That is, when the event camera 1306 is about to send one or more pixel values to the digital processing circuit 1310, the one or more pixel values are stored in the first image register 1311 before the smart motion detector 1312 wakes up, and the first image register 1311 is used to store the plurality of pixel values from the event camera 1306 before the smart motion detector 1312 wakes up. Similarly, one or more frames or one or more video streams processed by the digital processing circuit 1310 are stored in the second video register 1316 when it is determined that frame data formed by the sensed one or more pixel values relates to an actual motion event before the external processor 1317 is fully woken up, and then the one or more frames or the one or more video streams are transmitted or forwarded to the external processor 1317 once the external processor 1317 is fully woken up to receive the one or more frames or the one or more video streams. Furthermore, when the digital processing circuit 1310 is to send one or more frames to the back-end system device 1315, the one or more frames are stored in the second graphic buffer 1316 before the external processor 1317 is woken up, and the second graphic buffer 1316 is used to store the one or more frames from the digital processing circuit 1310 before the external processor 1317 is woken up. By using the above mechanism and the first and second image buffers, more power can be saved and the image loss can be avoided.

As shown in fig. 14, the analog image sensor circuit 1305 is always awake (i.e., in an awake state or in a normal mode other than a power-saving mode), for example, when powered on, to continuously or periodically detect whether one or more pixel values of one or more pixel units have changed. In a first operation scenario (but not limited to), if no pixel change is determined, the analog image sensor circuit 1305 does not send a trigger signal to wake up the digital processing circuit 1310 and the backend system 1315. Thus, the digital processing circuit 1310 and the backend system 1315 remain asleep or in the power saving mode, and the analog image sensor circuit 1305 does not transmit pixel data to the digital processing circuit 1310 and the backend system 1315.

In a second operation scheme (but not limited to), if at least one pixel value is determined to change, the analog image sensor circuit 1305 is configured to send a trigger signal to wake up the digital processing circuit 1310 and also send the sensed pixel data to the digital processing circuit 1310. In the case where the activation speed/time of the first image register 1311 is significantly faster than the activation speed/time of the smart motion detector 1312, the sensed pixel data may be temporarily stored in the first image register 1311 by using a freeze operation before the smart motion detector 1312 fully wakes up. After the digital processing circuit 1310 completely leaves the power saving mode and enters the normal mode, the pixel data sensed by the analog image sensor circuit 1305 can be directly transmitted to the motion detector 1312 without using the first image register 1311. In this case, if it is determined that no actual movement has occurred, the digital processing circuit 1310 does not send a warning signal to wake up the back-end system device 1315, and does not transmit the generated frames or image streams to the back-end system device 1315.

It should be noted that once the motion detector 1312 fully enters the normal mode, the motion detector 1312 is capable of receiving and processing the incoming pixel data and the stored pixel data of the first image register 1311 simultaneously. For example, without limitation, the motion detector 1312 can rapidly process the accumulated pixel values stored in the first image buffer 1311 using an ultra-high frame rate or higher frame rate image processing frequency and then synchronize the processed pixel values with the analog values of the incoming pixel data. For example, each time the analog image sensor circuit 1305 is called to sense multiple pixel cells, the motion detector 1312 processes the accumulated pixel values stored in the first image buffer 1311 and processes the analog values of the incoming pixel data in parallel until the first image buffer 1311 becomes empty.

In a third operation scenario (but not limited thereto), the first image buffer 1311 is capable of collecting and storing pixel information (pixel values or pixel differences) of a plurality of pixel units transmitted from the analog image sensor circuit 1305, and is capable of processing, forming and generating data of one or more complete frames. The smart motion detector 1312 is capable of determining whether actual motion has occurred based on the generated frame data. If it is determined that an actual movement has occurred, the digital processing circuit 1310 sends a warning signal to wake up the back-end system device 1315 and also sends the sensed frames or image streams to the back-end system device 1315. In this case, the sensed frames or streams can be temporarily stored in the second picture buffer 1316 using the freeze operation before the back-end system device 1315 is fully awake. When the backend system 1315 completely leaves the power saving mode and enters the normal mode, the sensed frames or image streams can be directly transmitted to the external processor 1317 without being buffered in the second image buffer 1316.

Please refer to fig. 13 again. Specifically, for determining whether a pixel value (or each pixel value) has changed, the event camera 1306 is used to sense or capture the current pixel value of a corresponding pixel cell to detect whether the pixel value has changed. The event camera 1306, for example, senses or captures the current pixel value of the pixel unit (as shown in S13051), and then calculates a pixel difference Diff between the sensed current pixel value and a reference pixel value of the pixel unit (as shown in S13052), where the reference pixel value of the pixel unit may be a previous pixel value sensed by the event camera at an earlier point in time for the pixel unit, or may be an average of a plurality of pixel values sensed by the event camera at the earlier point in time for the pixel unit. Thus, likewise, for a plurality (or all) of the pixel cells, the event camera 1306 is able to capture a plurality of current pixel values and then calculate or generate a plurality of pixel differences corresponding to the plurality of pixel cells, respectively.

Then, for the pixel value, the event camera 1306 determines whether the pixel value has changed by comparing the pixel difference with a pixel threshold TH (as shown in S13053). If the pixel difference Diff is higher than the pixel threshold TH, the event camera 1306 may determine that the pixel value has changed. On the other hand, if the pixel difference Diff is not higher than the pixel threshold TH, the event camera 1306 determines that the pixel value has not changed. It should be noted that, in the present embodiment, the pixel value is changed by a large variation, and the pixel value is not changed by a small variation or no change.

When the pixel difference Diff is equal to or higher than the pixel threshold TH, the event camera 1306 is configured to generate and send a trigger signal to wake up the digital processing circuit 1310, send information/data regarding a currently counted value of a counter N and the currently captured pixel value to the digital processing circuit 1310, update the reference pixel value by using the currently captured pixel value, and reset the counter N to zero. The counter value N is initially set to zero. If the motion detector 1312 is not in the normal mode, the current value of the counter value N and the current captured pixel value related information/data are temporarily stored in the first graphic register 1311. It should be noted that the pixel difference Diff of the pixel unit is calculated and updated again after each exposure operation performed on the pixel unit is finished to obtain the currently sensed pixel value. When the pixel difference Diff is not higher than the pixel threshold TH, the event camera 1306 increments or increments the counter value by one, and the event camera 1306 does not send the trigger signal, the current counted value of the counter value N, and information/data related to the currently captured pixel value.

The value of the counter value N is used to indicate the number of frames in which the pixel value of a pixel unit has not changed at any time point of a plurality of consecutive frames, or equivalently, the counter value N used by the event camera 1306 is used to determine a time interval between two times the pixel value of the pixel unit has changed. It should be noted that the values of the counter values N corresponding to different pixel units may be the same, different or partially different. In one embodiment, a resulting counter value may be selected from the values of the counter values N corresponding to the different pixel units, wherein the resulting counter value is, for example, a minimum value of all the counter values N, and the selected resulting counter value may be used to indicate a number of frames in which all the pixel values of all the pixel units have not changed at the time points of the consecutive frames.

Also, for example, but not by way of limitation, the frame rate may be equal to 30Hz, i.e., 30 frames per second, and if it is determined that the pixel value of the pixel unit has not changed within one second, the counter value N may be sequentially incremented by 1 up to 30 in that second from zero, at which point if it is determined that the pixel value has changed at the next frame time point, the counter value N will not be counted next to, for example, 31, but the event camera 1306 generates a trigger signal to wake up the digital processing circuit 1310 and transmits the currently counted counter value (i.e., 30) to the digital processing circuit 1310 before the counter value N is reset to zero. Furthermore, at the same time, the event camera 1306 also outputs information/data of the sensed/captured pixel values to the digital processing circuit 1310.

The information/data of the changed sensed/captured pixel values may be communicated from the analog image sensor circuit 1305 to the digital processing circuit 1310 using at least two different methods. In one embodiment, the event camera 1306 can send an actual value of the currently captured pixel value to the digital processing circuit 1310, and the digital processing circuit 1310 can directly use the actual value to replace a corresponding value of a pixel element in a previous frame to generate a current frame. Furthermore, in other embodiments, the event camera 1306 sends a difference between an actual value of the actual captured pixel value and an actual value of a previously captured pixel value to the digital processing circuit 1310, and the digital processing circuit 1310 can add the difference to a corresponding value of a pixel element in a previous frame to generate a current frame.

Referring to fig. 15, fig. 15 is a diagram illustrating two different operations of the digital processing circuit 1310 (or the intelligent motion detector 1312) to update and generate data of a current frame. For a pixel cell, such as an active pixel cell, even if the power to some portion of the circuitry within the motion detector 1312 is turned off, the data of the last previous frame can be stored in other portions of the circuitry within the motion detector 1312 as a static frame FS. The static frame FS is generated by the digital processing circuit 1310 when the event camera 1306 detects an earlier point in time when one or more pixel values change, i.e., the static frame FS is associated with one or more previous pixel values. As shown in a first scheme of fig. 15, when it is determined that the pixel value of the active pixel unit changes at a current frame time, the event camera 1306 in the first scheme transmits the actual pixel value of the active pixel unit to the image register 1311 of the digital processing circuit 1310, so that the image data related to the change of the pixel value can be stored in the image register 1311. Then, after the smart motion detector 1312 completely enters the normal mode, the smart motion detector 1312 may generate the current frame FC based on the data of the static frame FS and the actual values of the pixel values. In practice, the motion detector 1312 is arranged to replace the previous value of the active pixel cell in the static frame FS with the actual value to generate a current frame FC.

Furthermore, as shown in a second scheme of FIG. 15, for the active pixel unit, when it is determined that the pixel value of the active pixel unit changes at the current frame time, the event camera 1306 in the second scheme transmits a difference between a previously captured pixel value and a currently captured pixel value corresponding to the active pixel unit to the image register 1311 of the digital processing circuit 1310. Then, after the motion detector 1312 completely enters the normal mode, the motion detector 1312 generates a current frame FC based on the data of the static frame FS and the pixel difference values. In practice, the motion detector 1312 adds the pixel difference to the previously captured pixel values of the same active pixel cell in the static frame FS to generate the current frame FC.

In one embodiment, when the current frame FC is generated, the smart motion detector 1312 (or digital processing circuit 1310) is used to determine whether a motion occurs by generating one or more background frames based on the generated current frame FC and the counter value N and then comparing the current frame FS and the background frames. In practice, information/data of a previous background frame may be stored in a memory circuit of the smart motion detector 1312 so that the information stored in the memory circuit does not disappear even if the power of the smart motion detector 1312 is turned off. If the motion detector 1312 has remained in the normal mode, the motion detector 1312 may perform a recursive moving average calculation operation based on a previous background frame and the current frame FC to generate a current background frame. By way of example, but not limitation, the data of the present background frame may be determined by the following equation:

wherein FB _i Refers to the data, FB, of a current background frame generated at a current frame time point i _i-1 Refers to data of a previous background frame generated at a previous frame time point i-1, and FC refers to data of a current frame (or referred to as a current data frame). Similarly, based onThe data of the next background frame generated by the recursive moving average calculation operation can be determined by the following equation:

where FC' refers to the next data frame. In general, in a monitoring system, after a specific training time period, the data of a curve corresponding to a plurality of background frames at a plurality of different frame time points will be converged to the data of a stable background frame.

However, if the smart motion detector 1312 has just left the power saving mode and there is no previous background frame FB at this time _i-1 The smart motion detector 1312 does not perform the recursive moving average calculation described above, and the smart motion detector 1312 then uses the counter value N to generate a weight value and then uses the weight value, the current data frame FC and the last background frame FB stored in the memory circuit of the smart motion detector 1312 when the power to the smart motion detector 1312 is to be turned off _i-N . At this time, the current background frame FB _i Can be determined by the following equation:

FB _i ＝∝×FB _i-N +(1-∝)×FC

where ∈ is the weight value generated based on the counter value N. In a basic example (but not limited to), the weight value ∈ may be equal to

Or

For example, if the value N is equal to 30, then ℃ -

And the current background frame FB _i Can be prepared fromIs determined by the equation of (a):

and

in addition, the current background frame FB _i It can also be determined by the following equation:

however, the above embodiments are not intended to limit the present application. In other words, the value of the weight value ∈ may be dynamically determined based on the number of frames when the image/pixel value of one pixel unit does not change for several consecutive frames. Since performing recursive moving average calculation at this time necessarily requires recursively calculating to generate a plurality of background frames FB _i-1 、…、FB _i-(N-1) Can generate the current background frame FB _i So that the counter value N is used to directly generate the current background frame FB _i The calculation operation without performing the recursive moving average calculation can simplify the calculation.

For determining whether a motion occurs in the current frame FC, the intelligent motion detector 1312 calculates the current background frame FB _i And a frame difference between the current data frame FC, and then comparing the frame difference with a motion threshold THM to determine whether motion occurs. When the frame difference is higher than the motion threshold THM, the smart motion detector 1312 can determine that motion has occurred and then generate an alarm signal to the back-end system device 1315.

The moving threshold THM may be a fixed threshold value, for example, or may be a value that is dynamically adjusted. In one embodiment, the smart motion detector 1312 can use a curve fitting (curve fitting) operation according to a previous value of the motion threshold THM, the current background frame FB _i The current data frame FC and the counter value N are used to dynamically adjust the moving threshold THM.

Next, for the background frame FB for generating the next one _i+1 When the next data frame FC' is generated by using the information/data of the pixel values sent from the event camera 1306, the smart motion detector 1312 can, for example, generate a current background frame FB based on the generated current background frame FC _i And the next data frame FC' to perform a recursive moving average calculation.

Fig. 16 is provided to make the reader more clearly understand the above-described operation of the present application. Fig. 16 is a flow chart illustrating the operation of the smart motion detector 1312 just entering the normal mode according to an embodiment of the present application. The description of the steps is described below:

step 1605: starting;

step 1610: generating a current data frame FC based on the previous data/static current frame FS and the information or data (e.g. actual pixel values or pixel differences) of the image/pixel values of the changed pixels;

step 1615: generating a weight value ∈ according to the counter value N received from the event camera 1306 and buffered in the first image buffer 1311;

step 1620: generating a current background frame according to the weight value ∞ and the last background frame and the current data frame FC stored in the intelligent motion detector 1312;

step 1625: calculating a frame difference between the current data frame FC and the current background frame;

step 1630: dynamically updating the value of the moving threshold THM according to the previous or original motivation value of the moving threshold THM, the last background image frame and the current data image frame FC;

step 1635: judging whether the image frame difference is equal to or higher than the moving threshold value THM; if the frame difference is equal to or higher than the motion threshold THM, the flow proceeds to step 1645, otherwise, the flow proceeds to step 1640;

step 1640: not generating the warning signal; and

step 1645: the warning signal is generated.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An analog image sensor circuit for coupling to a digital processing circuit for performing motion detection, the analog image sensor circuit comprising:

an event camera including pixel units;

wherein the event camera is used for sensing the pixel value of the pixel unit to detect whether the pixel value is changed; when the pixel value changes, the event camera is used to trigger the digital processing circuit and transmit information of the pixel value to the digital processing circuit.

2. The analog image sensor circuit of claim 1, wherein the event camera additionally transmits a counter value to the digital processing circuit when the pixel value changes; the counter value corresponds to a time interval between an event that the digital processing circuit enters the power saving mode and an event that the pixel value changes; and, when the pixel value is not changed at a specific frame time point, the counter value is incremented by one and is not transmitted.

3. The analog image sensor circuit of claim 2, wherein the information of the pixel values and the counter values are stored in a first image register of the digital processing circuit before the digital processing circuit completely leaves the power saving mode and enters a normal mode, such that the digital processing circuit performs the motion detection according to the information of the pixel values and the counter values stored in the first image register after completely entering the normal mode.

4. The analog image sensor circuit of claim 2, wherein the event camera is to:

when the pixel difference between the reference pixel value of the pixel unit and the current pixel value of the pixel unit is higher than a pixel threshold value, judging that the pixel value is changed;

generating the information for the pixel values;

outputting the information of the counter value and the pixel value to the digital processing circuit;

updating the reference pixel value to the current pixel value; and

resetting the counter value to zero.

5. The analog image sensor circuit of claim 2, wherein the event camera is to:

when the pixel value is lower than the pixel threshold value, judging that the pixel value is not changed;

not outputting the information of the counter value and the pixel value to the digital processing circuit; and

the counter value is cumulatively incremented by one.

6. The analog image sensor circuit of claim 1, wherein when the event camera determines that the pixel value changes, the event camera transmits a trigger signal to wake up the digital processing circuit in the power saving mode.

7. The analog image sensor circuit of claim 1, wherein the information of the pixel value is an actual image capture value of the pixel value.

8. The analog image sensor circuit of claim 1, wherein the information of the pixel value is a difference between a present pixel value of the pixel cell and a previous pixel value of the pixel cell.

9. An image sensor device, comprising:

an analog image sensor circuit as claimed in claim 1; and

a digital processing circuit, externally coupled to the analog image sensor circuit, for performing motion detection;

wherein the digital processing circuit uses the information of the pixel values of claim 1 and stores the information

The last data frame in the digital processing circuit is used for generating a current data frame.

10. The image sensor device of claim 9, wherein the digital processing circuit generates a current background frame based on the counter value, the current data frame, and a last background frame stored in the digital processing circuit without performing recursive calculations; the counter value corresponds to a time interval between an event of the digital processing circuit entering a power saving mode and an event of a change in the pixel value.

11. The image sensor apparatus of claim 10, wherein the digital processing circuit uses the counter value to generate a weight value, and then uses the weight value, the one current data frame and the last background frame to directly compute the one current background frame.

12. The image sensor apparatus of claim 11, wherein the digital processing circuit is to:

calculating a frame difference between the current data frame and the current background frame;

comparing the frame difference with a motion threshold to determine whether motion occurs in the current data frame; and

when the movement occurs, a warning signal is generated and output to a background monitoring system externally coupled to the image sensor device.

13. A method of an image sensor device, comprising:

providing a digital processing circuit externally coupled to the analog image sensor circuit of claim 1 and configured to perform motion detection; and

a current data frame is generated using the information on the pixel values of claim 1 and a last data frame stored in the digital processing circuit.

14. The method of claim 13, further comprising:

generating a current background frame based on the counter value, the current data frame and the last background frame stored in the digital processing circuit without performing recursive computation;

wherein the counter value corresponds to an event that the digital processing circuit enters a power saving mode and the pixel value occurs

The time interval between changed events.

15. The method of claim 14, wherein the method further comprises:

generating a weight value using the counter value; and

directly computing the current background frame using the weight value, the current data frame, and the last background frame.

16. The method of claim 15, further comprising:

17. A method of simulating an image sensor circuit for external coupling to a digital processing circuit for performing motion detection, the method comprising:

providing an event camera comprising pixel units;

sensing a current pixel value of the pixel unit using the event camera to detect whether the pixel value changes;

when the pixel value changes, the event camera is used to trigger the digital processing circuit in a power saving mode, and information of the pixel value is transmitted to the digital processing circuit.

18. The method of claim 17, further comprising:

transmitting a counter value to the digital processing circuit using the event camera when the pixel value changes; and

incrementing the counter value by one and not transmitting the counter value to the digital processing circuit when the pixel value does not change at a particular frame time point;

wherein the counter value corresponds to the event of the digital processing circuit entering the power saving mode and the pixel value

The time interval between events at which the change occurs.

19. The method of claim 18, wherein the information about the pixel values and the counter values are stored in a first graphics register of the digital processing circuit before the digital processing circuit completely leaves the power saving mode and enters a normal mode, and the digital processing circuit is enabled to perform the motion detection according to the information about the pixel values and the counter values stored in the first graphics register after completely entering the normal mode.

20. The method of claim 18, further comprising:

generating the information for the pixel values;

updating the reference pixel value to the current pixel value; and

resetting the counter value to zero.

21. The method of claim 18, further comprising:

when the pixel difference is lower than the pixel threshold value, judging that the pixel value is not changed;

the counter value is cumulatively incremented by one.

22. The method of claim 17, further comprising:

transmitting a trigger signal from the event camera to wake up the digital processing circuit in the power saving mode when the pixel value changes.

23. The method of claim 17, wherein the information for the pixel value is an actual image capture value for the pixel value.

24. The method of claim 17, wherein the information for the pixel value is a difference between a present pixel value of the pixel cell and a previous pixel value of the pixel cell.