رؤية الالوان - التلفزيون الملون - الضوء .. الفيزياء

Color vision - Color TV - Light .. Physics

Color vision

The light-sensitive cells of the eye are divided into two types: rods and cones. Rods are characterized by their ability to sense low-intensity visible waves and their inability to distinguish between colors, which makes our vision in the dark limited to black and white. As for cone cells, they are characterized by their sensitivity to daylight, no matter how intense it is, and this sensitivity varies according to the wavelength, and that they are able to distinguish all colors. Color vision can be explained by dividing cone cells into three groups, each of which has a special sense of one of these three colors: red, green, and blue. The light falling on the eye prepares one or more of these groups to the extent that they are affected by its color. As for color blindness, it is a hereditary disease resulting from a malfunction in the functions of one or more of these groups.

Color TV

In color TV, light is divided into three primary colors: red, green, and blue. Special types of mirrors and filters are used for this purpose (a filter is a thin colored membrane through which only light of similar color passes). Each color is then sent to an independent tube in the camera, where each photographed scene is converted into its primary colors: red, green, and blue. Each color forms an independent television signal.

Then, these signals are sent to three electron guns, each of which gives off a beam of electrons that collect on a plate containing a large number of holes called a shadow mask, followed by a curtain with a large number of phosphorous dots collected in three groups. When the electrons stimulate these dots, each of them sends out colored light in one of the three mentioned colors, the intensity of which varies depending on the beam of electrons that causes it. When the electron boots scan the entire mask, they scatter through each hole, and the beam carrying the red signal collides with the phosphor dots emitting the red color, in a process of precise focusing that is repeated for the rest of the colors. As the current of each beam changes, its color changes, which regenerates all the primary colors of the television scene. The television camera separates the light into its three components (up). The transmitted signals control three electron beams that pass through the shadow mask and then collide with the phosphor dots designated for them.