This paper proposes a new display device for switching between 3D and 2D images. A concave lens array is
formed on the surface of a first panel, while a convex lens array is formed on the surface of a second panel. An
image-plane of display, the first panel and the second panel are arranged in this order, and the concave lens and the
convex lens face each other. When the two panels are brought into contact with each other, they show 2D images
equivalent to that of one transparent plate. But when the separation interval between the panels is optimum, we see 3D
images similar to that caused by lenticular lenses. This display is applied to a 3D and 2D switchable mobile display.
Our new type of camera module is small and thin, and is able to detect the distances of objects as well as their images. The module comprises a four-lens array, one imaging sensor and optical filters. The imaging sensor is divided into four areas, two of which are covered with green filters and the other two with infiared filters. A prototype was fabricated with a focal length of 2.63 mm and a baseline length of 2.59 mm. The two images with the same optical filters have parallax, so the distances of objects can be calculated by comparing the two images. We use infrared images illuminated with infrared LEDs at night, and green images during the daytime. After calibrating the images, we achieved a distance-detection accuracy of within ±2.5% at 1 m in spite of the camera's small baseline length. Consequently, our new distance detection camera module is small and thin, and generates a depth-image of an object as well as its image. Our camera module is thus applicable to vehicles, security systems and three-dimensional imaging.
We have proposed a new type of camera module with a thin structure and distance-detection capability. This camera
module has a four-lens-array with diffraction gratings (one for blue, one for red, and two for green). The diffraction
gratings on the mold are formed mechanically, and the plastic lens array is fabricated by injection molding. The two
green images are compared to detect parallax, and parallax-corrected blue, red and green images are then composed to
generate a color image. We have developed new design software and molding technologies for the grating lenses. The
depth and period of blazed gratings and the shapes of aspheric lenses are optimized; and blue, red and two green
aspheric lenses with gratings are molded as a single four-lens-array. The diffraction gratings on both surfaces of each
lens act to improve field curvature and realize wide-angle imaging. However, blazed gratings sometimes cause
unnecessary diffraction lights that impede the formation ofhigh-resolution images. We have developed a new method to
measure necessary first-order diffraction lights and unnecessary diffraction lights separately. Use of this method allows
the relationship between molding conditions and necessary/unnecessary diffraction lights to be shown. Unnecessary
diffraction lights can be diminished by employing the optimal molding processes, allowing our grating lenses to be used
for image capture.
Our new type of camera module has a four-lens-array and an imaging sensor. The imaging sensor is divided to four regions, and these four regions are aligned in one-to-one correspondence with the four lenses. Four color filters are placed over the four imaging regions. First region has a blue filter, second has a red, and the other two have green filters, and two regions with green filters are aligned diagonally. Diffraction gratings are formed on aspheric surfaces of the four lenses, and MTF characteristics of these lenses are improved. The four images taken through the different lenses have parallax, but these parallaxes can be calculated by comparison of the two green images. Pixel shifts of blue, red and green images are realized by rotating the four-lens-array slightly with respect to the imaging sensor. After correcting the parallaxes, the green image, the parallax-corrected blue image and the parallax-corrected red image are composed to generate the resultant color image with high resolution. Distances between objects and the four-lens-array are detected by use of the above parallaxes, and measurement error is less than 2.5% for near objects. With above configuration and functions, our camera module has realized smaller height, higher image resolution and distance-detection capability, and will be applied for cellular phones and automobile vehicles.