TECHNICAL FIELD

The present disclosure relates to an imaging device with both dynamic vison sensor and imaging capabilities.

BACKGROUND

In the related art, a synchronization-type solid-state imaging device that captures image data in synchronization with a synchronization signal such as a vertical synchronization signal has been used in an imaging device and the like. In the typical synchronization-type solid-state imaging device, it is difficult to acquire image data for every period of the synchronization signal (for example, for every 1/60 seconds), and thus it is difficult to cope with cases in which relatively high-speed processing is demanded, such as in fields demanding high speed (e.g. real time) processing, such as autonomous vehicles, robotics, and the like. In this regard, there is suggested a non-synchronization-type solid-state imaging device in which a detection circuit is provided for every pixel to detect a situation in which a light-reception amount exceeds a threshold value as an address event in real time. The non-synchronization-type solid-state imaging device that detects the address event for every pixel is also referred to as a dynamic vision sensor (DVS).

SUMMARY

Technical Problem

A sensor with a combination of DVS and regular frame based imaging can be achieved using various methods. These include devices that feature time-based readout using additional photodiodes, known as asynchronous time-based image sensors (ATIS) systems. However, because ATIS systems require two photodiodes per pixel in order to provide image sensor and DVS signals, they suffer from degraded resolution and image quality as compared to arrangements that do not require additional photodiodes. Other devices feature pixels that provide image sensor signals and dynamic vision sensor (DVS) event signals using a common photodiode, known as dynamic and active pixel vision sensor (DAVIS) systems. However, DAVIS systems can suffer from decreased sensitivity due to the need to suppress interference between the image and event detection functions, as those functions are not well isolated. In addition, difficulty in readout of DVS and active image sensor signals can degrade the dynamic range of DAVIS sensors.

Therefore, the present disclosure provides a solid-state imaging device and an imaging device which are capable of providing both imaging and event detection functions with improved event detection capabilities and light-reception efficiency as compared to other configurations.

Solution to Problem

In accordance with embodiments and aspects of the present disclosure, there is provided an imaging device comprising a plurality of photoelectric conversion regions or pixels, also referred to herein as unit pixels, arranged in a pixel array. At least some of the pixels are configured as event detection pixels, while other of the pixels are configured as image sensing or capture pixels. In general, the event detection pixels are interspersed amongst the image capture pixels within the pixel array. In operation, the detection of an event by one or more event detection pixels in trigger operation of the image sensing pixels.

Each pixel includes a single photoelectric conversion region and an associated readout circuit. More particularly, each image sensing pixel includes a photoelectric conversion region and a first readout circuit, also referred to herein as an imaging generation unit or circuit. Each event detection pixel includes a photoelectric conversion region and a second readout circuit, also referred to herein as an event detection circuit.

In accordance with at least some embodiments and aspects of the present disclosure, each event detection pixel occupies a larger area of the pixel array than any one image sensing pixel. As an example, but without limitation, each event detection pixel may occupy an area that is four times the area of each image sensing pixel. In accordance with other embodiments and aspects of the present disclosure, each event detection pixel may occupy an area that is equal to the area of each image sensing pixel. In accordance with still further embodiments of the present disclosure, different ratios of image sensing pixels to event detection pixels can be included within the pixel array. As examples, but without limitation, the ratio can be 3:1, 4:1, 12:1, 15:1, 32:1, or 35:1. In accordance with at least some embodiments and aspects of the present disclosure, a ratio of any area of the photoelectric conversion region of each event detection pixel occupies a larger area within the plane of the pixel array.

In accordance with still further embodiments and aspects of the present disclosure, isolation structures are provided to isolate at least some of the unit pixels from other unit pixels. For example, full thickness dielectric trench (RFTI) isolation structures can be formed around each of the event detection pixels. As a further example, rear deep trench isolation (RDTI) isolation structures can be formed around least portions of the image sensing pixels, to provide isolation between adjacent image sensing pixels. In accordance with still other embodiments and aspects of the present disclosure, at least to some readout circuit elements can be shared by multiple photoelectric conversion regions. For example, a group of image sensing pixels may share readout circuit elements. As an example, but without limitation, the group of image sensing pixels may be in the form of a Bayer array. In accordance with still other embodiments of the present disclosure, some or all of the event detection pixels may additionally function as image sensing pixels. Moreover, in such embodiments, image sensor readout circuit elements and event detection circuit elements within a group of event detection pixels can be shared. As an example, but without limitation, such a group of event detection pixels may be in the form of a Bayer array.

The present disclosure can provide imaging devices with dynamic vision sensing and imaging capabilities that are capable of improved light-reception efficiencies.

