TECHNICAL FIELD

The present technology relates to a solid-state imaging element and an imaging device. More specifically, the present technology relates to a solid-state imaging element that compares a change amount of an incident light amount with a threshold, and an imaging device.

BACKGROUND ART

Conventionally, a synchronous solid-state imaging element for capturing image data (frame) in synchronization with a synchronous signal such as a vertical synchronous signal has been used in an imaging device or the like. The typical synchronous solid-state imaging element can acquire the image data only at each cycle (for example, 1/60 seconds) of the synchronous signal, and is thus difficult to deal with a case where higher-speed processing is required in the fields of transportation, robots, and the like. Therefore, an asynchronous solid-state imaging element that detects the presence or absence of an address event for each pixel has been proposed (for example, see Patent Document 1). Here, the address event means that a light amount of a pixel has varied at a certain pixel address and a variation amount has exceeded a threshold. The address event includes an on-event in which the light amount of a pixel has varied and the variation amount has exceeded a predetermined upper limit, and an off-event in which the variation amount has fallen below a predetermined lower limit. In the asynchronous solid-state imaging element, two-bit data including a detection result of a one-bit on-event and a detection result of a one-bit off-event is generated for each pixel. Such a solid-state imaging element for detecting the presence or absence of an address event for each pixel is called dynamic vision sensor (DVS).

CITATION LIST

Patent Document

Patent Document 1: PCT Japanese Translation Patent Publication No. 2017-535999

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The above-described asynchronous solid-state imaging element (DVS) generates data at a much higher speed than the synchronous solid-state imaging element. However, in image recognition or the like, high-quality image data of three bits or more is sometimes required for each pixel, in addition to detection of the presence or absence of an address event, and the above-described DVS for generating two-bit data for each pixel cannot satisfy the request. To capture higher-quality image data, an analog to digital converter (ADC) that converts an analog signal generated by photoelectric conversion into three or higher-bit data is only required to be added to the DVS. However, this configuration has a problem that the AD conversion time is longer than the case of generating two-bit data for each pixel.

The present technology has been made in view of such a situation, and an object is to shorten the time required for AD conversion when further capturing image data in a solid-state imaging element that detects the presence or absence of an address event.

Solutions to Problems

The present technology has been made to solve the above-described problem and the first aspect is a solid-state imaging element including a detection block in which a first pixel that generates a first analog signal by photoelectric conversion and a second pixel that generates a second analog signal by photoelectric conversion are arrayed, a first analog-digital converter configured to convert the first analog signal into a digital signal on the basis of whether or not a change amount of an incident light amount of the detection block exceeds a predetermined threshold, and a second analog-digital converter configured to convert the second analog signal into a digital signal on the basis of whether or not the change amount exceeds the threshold. This brings about an effect that the first and second analog signals are converted into the digital signals in parallel.

Furthermore, in the first aspect, a first shared block in which a predetermined number of the first pixels is arrayed, the first pixels sharing a floating diffusion layer that accumulates a charge of an amount according to the first analog signal, and a second shared block in which a predetermined number of the second pixels is arrayed, the second pixels sharing a floating diffusion layer that accumulates a charge of an amount according to the second analog signal, may be further included, and at least a part of the first shared block and at least a part of the second shared block may be arranged in the detection block. This brings about an effect that pixel signals in an overlapping area of the detection block and the first and second shared blocks are read in parallel.

Furthermore, in the first aspect, the detection block may include first and second detection blocks, a part of the first shared block and a part of the second shared block may be arranged in the first detection block, and a rest of the first shared block and a rest of the second shared block may be arranged in the second detection block. This brings about an effect that pixel signals in an overlapping area of the detection block and the first and second shared blocks are read in parallel.

Furthermore, in the first aspect, a part of the first shared block and a part of the second shared block may be arranged in the detection block, and a rest of the first shared block and a rest of the second shared block may not be arranged in the detection block. This brings about an effect that an address event is detected in a part of the shared blocks, and an address event is not detected in the rest of the shared blocks.

Furthermore, in the first aspect, a drive circuit configured to change a size of the detection block by a predetermined control signal may be further included. This brings about an effect that the size of the detection block is changed.

Furthermore, in the first aspect, the detection block may include a plurality of first light-receiving units each configured to generate a charge by photoelectric conversion, a plurality of second light-receiving units each configured to generate a charge by photoelectric conversion, a first detection unit configured to detect whether or not a change amount of a photocurrent flowing through a first connection node to which the plurality of first light-receiving units is connected exceeds the threshold, a second detection unit configured to detect whether or not a change amount of a photocurrent flowing through a second connection node to which the plurality of second light-receiving units is connected exceeds the threshold, and a switch configured to open or close a path between the first connection node and the second connection node according to the control signal. This brings about an effect that the size of the detection block is changed by the control of the switch.

Furthermore, in the first aspect, the detection block may include a plurality of light-receiving units each configured to generate a charge by photoelectric conversion, and a detection unit configured to detect whether or not a change amount of a photocurrent according to an amount of the charge exceeds the threshold, the plurality of light-receiving units may be arranged in pixels different from one another, and the plurality of light-receiving units may share the detection unit. This brings about an effect that an address event is detected by the detection unit shared by the plurality of pixels.

Furthermore, the second aspect of the present technology is an imaging device including a detection block in which a first pixel that generates a first analog signal by photoelectric conversion and a second pixel that generates a second analog signal by photoelectric conversion are arrayed, a first analog-digital converter configured to convert the first analog signal into a digital signal on the basis of whether or not a change amount of an incident light amount of the detection block exceeds a predetermined threshold, a second analog-digital converter configured to convert the second analog signal into a digital signal on the basis of whether or not the change amount exceeds the threshold, and a signal processing unit configured to process the digital signals. This brings about an effect that the first and second analog signals are converted into the digital signals in parallel, and the digital signals are processed.

