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Exposure method and pixel structure for pulse width modulation pixel

A technology of pulse width modulation and exposure method, which is applied in the field of image sensors, can solve the problems of poor dynamic range performance of pulse width modulation pixels and achieve ultra-low power consumption

Active Publication Date: 2017-02-01
SHANGHAI ADVANCED RES INST CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] In view of the prior art described above, the purpose of the present invention is to provide a pulse width modulation pixel exposure method and a pixel structure for solving the problem of poor dynamic range performance of pulse width modulation pixels in the prior art

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  • Exposure method and pixel structure for pulse width modulation pixel
  • Exposure method and pixel structure for pulse width modulation pixel
  • Exposure method and pixel structure for pulse width modulation pixel

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Embodiment 1

[0037] This embodiment provides a pulse width modulation pixel exposure method, the pulse width modulation pixel includes a photodiode, and the method includes the following steps:

[0038] When performing an exposure operation of a pulse width modulated pixel, the photodiode is first reset to a reset voltage. Under illumination, the node voltage of the photodiode decreases linearly with a slope related to the intensity of light. At this time, the node voltage of the photodiode is compared with two reference voltages with different levels to obtain two sets of pixel signals. Due to the digital characteristics of the output signal, the two groups of pixel signals can be synthesized and output on the same column line.

[0039] As a preferred solution of the present invention, two comparators can be used to compare the node voltage of the photodiode with two reference voltages of different heights, and obtain two sets of pixel signals in the same exposure period.

[0040] As a p...

Embodiment 2

[0042] see figure 1 , this embodiment provides a pulse width modulation pixel structure that can implement the above exposure method. The structure includes: a photodiode PD, a reset transistor M1, a first comparator B1, a second comparator B2, a control switch K1, a combined circuit and a counter.

[0043] Wherein, one end of the reset transistor M1 is connected to the power supply VDD, the other end is connected to the reverse input end of the photodiode PD, and the gate is connected to the reset signal Rst; the positive input end of the photodiode PD is grounded; the first The input terminal of a comparator B1 is respectively connected to the node voltage of the photodiode PD and the first reference voltage RefH, and the output terminal of the first comparator B1 is connected to the combination circuit through the control switch K1; the The input terminal of the second comparator B2 is respectively connected to the node voltage of the photodiode PD and the second reference...

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Abstract

The invention provides an exposure method and pixel structure for a pulse width modulation pixel. According to the exposure method, node voltages of a photodiode is compared with two different reference voltages by two comparators after exposure, thereby obtaining two groups of pixel signals; and then the two groups of pixel signals are synthesized and then the processed signal is outputted. Besides, the pixel structure is composed of a reset transistor, a photodiode, a first comparator, a second comparator, a control switch, a combination circuit, and a counter. According to the invention, the advantages of ultra-low power consumption of the PWM pixel is kept; and because of the characteristic of pixel-level digital-to-analog conversion in the PWM pixel, adaptation to a secondary exposure mode of the PWM pixel is realized.

Description

technical field [0001] The invention relates to the technical field of image sensors, in particular to a pulse width modulation pixel exposure method and a pixel structure. Background technique [0002] The Internet of Things technology is widely used in the integration of networks through communication perception technologies such as intelligent perception, identification technology and pervasive computing. Therefore, it is called the third wave of the development of the world's information industry after computers and the Internet. In the Internet of Things, it is necessary to collect physical information in nature such as temperature, humidity, pressure, and even images through a large number of sensors. Among them, the image sensor has a wide range of applications and has greater research significance because of the intuitive signals it collects and the large amount of information that can be mined. However, today's Internet of Things requires sensors to be more intelli...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N5/355
CPCH04N25/58H04N25/589
Inventor 汪辉霍书瑶章琦汪宁田犁
Owner SHANGHAI ADVANCED RES INST CHINESE ACADEMY OF SCI