Obviousness

Obviousness Analysis of US Patent 9232158

This analysis addresses the obviousness of US Patent 9232158, titled "Large dynamic range cameras," under 35 U.S.C. § 103, considering the prior art cited within the patent's background. The priority date for US9232158B2 is August 25, 2004.

Core Inventive Concept of US9232158B2

US9232158B2 describes a digital camera system designed to achieve a large dynamic range. The key features of the claimed invention, as understood from its abstract and detailed description, include:

• A plurality of camera channels, each comprising its own optics component and an image sensor with an array of photo-detectors.
• The sensors of these channels are integrated on a common semiconductor substrate.
• A processing component is configured to separately and simultaneously control the integration time of each channel, with at least one channel having a different integration time than another.
• The processing component combines data from these channels to generate a single image with a large dynamic range.

The patent explicitly identifies the problem it aims to solve: temporal aliasing in prior art systems that achieve wide dynamic range by sequentially capturing multiple images with different exposure times using a single image sensor.

Prior Art References for Analysis

The background section of US9232158B2 discusses several prior art patents that address wide dynamic range imaging:

• U.S. Pat. No. 4,647,975 (Nishizawa): Discloses a method of acquiring two or more images, each with a different exposure time, and then fusing or merging these images to form a single piece of pixel information with a wide dynamic range.
• U.S. Pat. No. 5,168,532 (Takagi et al.): Discloses using a selection rule to combine information from multiple images acquired at different exposure times.
• U.S. Pat. No. 5,671,013 (Takagi): Also discloses using a selection rule to combine information from multiple images with different exposure times.

US9232158B2 explicitly states that methods described in U.S. Pat. Nos. 4,647,975, 5,168,532, and 5,671,013 "exhibit undesirable temporal aliasing if the scene or camera is moving because the two or more images having different exposure times are captured using the same image sensor and thus are not captured concurrently."

Obviousness Argument

A person having ordinary skill in the art (PHOSITA) in digital camera design as of the August 25, 2004, priority date would have found the claimed invention of US9232158B2 obvious by combining the teachings of the aforementioned prior art references with general knowledge in the field.

1. Combination of US 4,647,975 (Nishizawa) and General Knowledge of Image Sensor Design and Semiconductor Integration:

• Nishizawa's Core Teaching: U.S. Pat. No. 4,647,975 clearly teaches the fundamental concept of creating a wide dynamic range image by combining multiple constituent images taken at different exposure times. This established the goal and a general methodology for achieving high dynamic range.
• Identified Problem: The limitation of Nishizawa's approach, acknowledged by US9232158B2, is the temporal aliasing caused by the sequential capture of images using a single image sensor.
• Motivation for Combination: A PHOSITA would be strongly motivated to overcome this known and undesirable temporal aliasing artifact. The most direct and logical solution to achieve concurrent capture of images at different exposure times is to employ separate imaging elements that can operate simultaneously.
• Application of General Knowledge: By 2004, the semiconductor industry had well-established capabilities for integrating multiple functional blocks, including arrays of photo-detectors and associated circuitry, onto a single integrated circuit (IC) or semiconductor substrate. This integration offered benefits such as compactness, reduced cost, lower power consumption, and improved signal integrity due to shorter electrical paths. Given the desire for simultaneous capture, a PHOSITA would readily conceive of implementing multiple image sensor arrays, each with its own independent exposure (integration time) control, on a single chip. This would allow each array to capture an image of the same field of view concurrently but with its own optimal integration time. The patent itself states that "the digital camera systems described herein overcome this dynamic range limitation through the use of multiple camera channels, including multiple optics and image sensors on a single integrated circuit (IC) or semiconductor substrate." This framing suggests that the integration of multiple sensors on a single IC was a known and viable solution pathway for addressing such problems.
• Optics and Processing: It would also be evident to a PHOSITA to associate each sensor array with its own optics (e.g., microlenses, which were also known in the art) to direct light to the respective sensor. Furthermore, the concept of combining the data from these different exposures to form a single high dynamic range image, as taught by Nishizawa, would be directly applicable to the simultaneously captured data from the multiple channels. The patent describes an image processor that "combines the images from the two or more camera channels to provide a full-color large dynamic range image."

Therefore, combining the known technique of multi-exposure HDR imaging (Nishizawa) with the well-understood engineering principle of semiconductor integration to enable simultaneous capture of different exposures on multiple on-chip sensors, in order to overcome the recognized problem of temporal aliasing, would have been obvious to a PHOSITA.

2. Combination of US 5,168,532 (Takagi et al.), US 5,671,013 (Takagi), and General Knowledge:

The arguments for obviousness using U.S. Pat. Nos. 5,168,532 and 5,671,013 would be substantially similar. These patents reinforce the prior art's understanding of combining multiple exposures for dynamic range, and they share the same deficiency of temporal aliasing due to sequential capture on a single sensor. The motivation to remedy this deficiency through simultaneous capture via integrated multiple channels would be equally strong.

In summary, the core advance of US9232158B2 – using multiple, independently controlled image sensor channels on a single substrate to capture simultaneous images at different integration times for high dynamic range – represents a predictable solution to a known problem in the art (temporal aliasing), achieved by combining existing HDR processing techniques with routine semiconductor integration and multi-sensor design practices.