Optical Sensor Read-Out Circuit Placement for Reflection Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical sensor apparatuses experience image quality degradation due to light reflections from external connection terminals and read-out circuits, leading to uneven light and dark distributions at the periphery of the image screen, which affects the commercial value of the devices.
Innovation Solution
The optical sensor apparatus design includes a package with a window where the read-out circuit is positioned under the sensor chip and hidden from view, eliminating reflections by ensuring no portion of the read-out circuit extends beyond the sensor chip, and using underfill resin and conductive materials to facilitate electrical connections without exposing external terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If external connection terminals are arranged off the sensor chip to enable wire bonding connections, then electrical connectivity is achieved, but light reflection from these terminals causes uneven light and dark distributions at the periphery of the image screen
Solution Approach 1:
The patent extracts the harmful function of external connection terminals by moving them to the back surface of the package, away from the light path. The terminals are still electrically connected through the sensor chip and read-out circuit, but they no longer reflect light into the image area, thus eliminating the harmful effect while preserving electrical connectivity.
Solution Approach 2:
The patent relocates the external connection terminals from the front surface (where they caused light reflection problems) to the back surface of the package. This dimensional relocation moves the terminals out of the optical path while maintaining their electrical connection function through the sensor chip and read-out circuit.
2Ease of manufacture
If read-out circuit area is extended off the sensor chip to accommodate external connection terminals, then wire bonding is enabled, but image quality deteriorates due to peripheral light and dark undulations
Solution Approach 1:
The patent extracts the problematic extension of the read-out circuit from the front surface by relocating external connection terminals to the back surface. This allows the read-out circuit to be confined to the area under the sensor chip, eliminating the source of light reflection while preserving wire bonding capability through the relocated terminals.
Solution Approach 2:
The patent resolves the conflict by using the back surface dimension of the package for external connection terminals. This allows the read-out circuit to remain compact under the sensor chip (maintaining image quality) while still providing wire bonding capability through terminals accessed from the rear side.
3Use of energy by moving object
If anti-reflection coating is applied to the sensor chip surface, then light absorption is improved, but reflected light from other components still causes peripheral image degradation
Solution Approach 1:
The patent complements the anti-reflection coating on the sensor chip surface by additionally addressing reflections from other components. By relocating external connection terminals to the back surface, the patent extracts these additional reflection sources from the optical path, working synergistically with the surface anti-reflection coating to minimize all light reflections.
Solution Approach 2:
The patent applies anti-reflection coating to the sensor chip surface and simultaneously relocates external connection terminals to the back surface, creating a multi-faceted solution that addresses reflections from multiple sources. This universal approach minimizes light reflection effects throughout the entire optical path.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves a uniform light intensity distribution across the image surface, enhancing image quality by preventing light reflections and ensuring high-resolution images.
Implementation Method 1
the infrared optical sensor apparatus has been cooled to, for example, liquid-nitrogen temperature during operation. With improvements in semiconductor technology, the infrared optical sensor apparatus has sufficiently high image quality, even if the infrared optical sensor apparatus is cooled by using thermoelectric device such as a Peltier device.
Implementation Method 2
Patent Document 1 (Japanese Unexamined Patent Application Publication No. 6-302845) proposes an anti-reflection coating that absorbs reflected light to suppress noise light produced in the light receiving regions (pixels) of a solid-state image sensing device for visible light.
Implementation Method 3
a light receiving apparatus is proposed, in which the through-holes are filled with resin that transmits visible light and blocks infrared light.
Data Source
AI summary
An optical sensor apparatus includes a package having a window; a sensor chip having an array of light receiving devices and a pixel electrode connected to each light receiving device, the sensor chip having an incidence surface that faces the window of the package; and a read-out circuit disposed under the sensor chip, the read-out circuit having a read-out electrode electrically connected to each pixel electrode of the sensor chip. The sensor chip and the read-out circuit are housed in the package. In plan view from the sensor chip, the read-out circuit is overlapped by the sensor chip, and the read-out circuit has no portion extending off the sensor chip.