What Is a Lenticular Lens?
A lenticular lens is a convex lens whose cross-section is shaped like a fish cake and is generally a sheet of multiple elongated convex lenses in a row. By displaying parallax images or videos on a screen with a lenticular lens attached to the screen, it is possible to achieve stereoscopic vision with the naked eye.
Uses of Lenticular Lenses
The primary applications of lenticular lenses are “3D stereopsis with the naked eye” and “creating 2D images whose patterns change depending on the viewing angle.” This principle is also applied to souvenir cards and keychains, which have lenticular lenses attached to their surfaces. In recent times, there have been advancements in naked-eye stereoscopic displays that do not require 3D glasses.
Principles of Lenticular Lenses
Lenticular lenses are often made of materials such as PET or acrylic and are used as sheets consisting of a series of long, thin convex lenses with a cross-section shaped like a fish cake. By attaching this sheet or printing directly on the back of the sheet, effects like “stereoscopic vision” and “objects seen from different viewing angles” can be achieved. This effect is produced when light is refracted by lenticular lenses. Precise alignment of each convex lens of the lenticular lens with the target image or video is crucial to achieve this effect. Misalignment can result in an ineffective display. Lenticular sheets use a numerical value called “lpi” to indicate the fineness of the sheet’s surface, so it is important to produce images and videos that match this pitch. For example, 30 lpi means there are 30 lenses per inch and 100 lpi means there are 100 lenses per inch.
The viewing angle also changes depending on the refractive index of the lenticular lenses, which is determined by the ratio of the thickness to the number of lines. For the same number of lines, thicker lenses provide a deeper 3D effect, while thinner lenses are better suited for 2D displays.
An Example of Application of Lenticular Lenses
For example, when used as a Center Information Display (CID) for in-vehicle use, a single display can simultaneously generate car navigation images on the driver’s side and entertainment images such as movies on the passenger side. In the context of a 3D stereoscopic display for the naked eye, two types of images with parallax adjusted for the left eye and the right eye are generated. The conditions of the lenticular lenses are adjusted so that the light from the pixels displaying the respective image data is separated in the direction of the user’s left eye and right eye.