Semiconductor image sensing device

Abstract

A signal charge corresponding to an incident light quantity is accumulated in a first node (N1) of each pixel circuit (10). An accumulated charge exhaust circuit (20) includes each of first nodes (N1) of the plurality of pixel circuits (10) belonging to the same pixel group, and a second node (N2) connected through discharge gates (DG) functioning as variable resistance elements. Second node (N2) functions as a floating drain during an ON period of a control switch (24), while accumulating the signal charge overflowing from each pixel circuit (10), in a capacitor (22) during an OFF period of control switch (24) provided at an intermediate timing in one frame period. When the incident light to the pixel group is intense, a resistance value of each discharge gate (DG) is lowered in response to an increase of the signal charge accumulated in capacitor (22), so that the signal charge accumulated in each pixel circuit can be exhausted once at the above intermediate timing.

Description

technical field [0001] The present invention relates to a semiconductor imaging device; more specifically, the present invention relates to a semiconductor imaging device capable of imaging in a large dynamic range even if there is a region with a large brightness difference in the field of view and capable of detecting sufficient contrast in the entire region. Background technique [0002] Starting with video cameras and digital cameras, even mobile phones now have built-in solid-state imaging elements such as CCD (Charge-coupled device) and CMOS (Complementary metal-oxide semiconductor: Complementary Metal-Oxide Semiconductor) imaging elements, so-called semiconductor imaging devices. Sensors (hereinafter also referred to as "semiconductor imaging elements") are widely used as inexpensive and low-power imaging elements. [0003] However, the sensing capability of semiconductor imaging elements is much inferior to thermal visual sensing. Thermal vision can fully detect the...

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Problems solved by technology

[0005] However, in the composition disclosed in the above-mentioned Patent Document 1, it is necessary to arrange in each pixel circuit a first light-sensing detection element for detecting its own light-receiving amount and a first light-sensing detection element connected to other pixel circuits through a resistance element to detect the average light-receiving amount of nearby pixels. 2 photosensitive detection elements

Therefore, it may be difficult to reduce the pixel size, which is indispensable to meet the demand for high-resolution in recent years

[0006] Moreover, since the first and second photosensitive detection elements are connected in series in each pixel circuit, noise flowing into nodes electrically connected to surrounding pixel circuits may be superimposed on the photocurrent of the first photosensitive detection element, which may cause Noise is easily detected, and detection accuracy may decrease

[0007] In addition, in the composition disclosed in the above-mentioned Patent Document 2, although there is one photosensitive detection element arranged in each pixel circuit, it is necessary to process various signal currents in one pixel circuit, so the composition of the peripheral circuits used for this processing is complicated.

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