Abstract: The mobile communication terminal includes an emergency call unit that includes a pressure detector detecting a pressure caused by an operation of a user and generates an emergency detection signal when the pressure detector detects a pressure of a predetermined reference value or more; a control unit that generates an emergency call signal when the emergency detection signal is received from the emergency call unit; and a communication unit that receives the emergency call signal from the control unit and transmits the emergency call signal to at least one of a guardian terminal and a management server, wherein the pressure detector includes position pins and an elastic unit located between the position pins and detects a pressure applied to the elastic unit when a pressure of a predetermined reference value or more is applied and the position pins are broken.

Abstract: Disclosed is an optical system for a head-mounted display, in which image rays provided from a display device are diverged to form and provide an enlarged image. First, second, and third lenses or first, second, third, and fourth lenses are sequentially disposed from an object along an optical axis and provide the enlarged image on an image plane, and angles of principal rays are gradually increased from the optical axis toward an edge of the image plane. Thus, as the angles of principal rays increase, the angle of view is improved to provide a large image so that it is possible to appreciate a vivid image due to an increase in the sense of presence and the degree of involvement. The size of the entire optical system can be reduced, thus a head-mounted display can be made compact and lightweight.

Abstract: The mobile communication terminal includes an emergency call unit that includes a pressure detector detecting a pressure caused by an operation of a user and generates an emergency detection signal when the pressure detector detects a pressure of a predetermined reference value or more; a control unit that generates an emergency call signal when the emergency detection signal is received from the emergency call unit; and a communication unit that receives the emergency call signal from the control unit and transmits the emergency call signal to at least one of a guardian terminal and a management server, wherein the pressure detector includes position pins and an elastic unit located between the position pins and detects a pressure applied to the elastic unit when a pressure of a predetermined reference value or more is applied and the position pins are broken.

Abstract: An optical system for a head-mounted display in which image rays provided from a display device are divergent to form and provide an enlarged image is configured so that first and second lenses are sequentially disposed from an object along an optical axis and provide the enlarged image on an image plane, and angles of principal rays are gradually increased from the optical axis toward the edge of the image plane. Thus, as the angles of principal rays are increased, an angle of view is improved to provide a large screen so that it is possible to appreciate a vivid image due to an increase in the sense of presence and the degree of involvement. The entire size of the optical system can be reduced. The head-mounted display can be made compact and lightweight.

Abstract: An optical system for a head-mounted display in which image rays provided from a display device are divergent to form and provide an enlarged image is configured so that first and second lenses are sequentially disposed from an object along an optical axis and provide the enlarged image on an image plane, and angles of principal rays are gradually increased from the optical axis toward the edge of the image plane. Thus, as the angles of principal rays are increased, an angle of view is improved to provide a large screen so that it is possible to appreciate a vivid image due to an increase in the sense of presence and the degree of involvement. The entire size of the optical system can be reduced. The head-mounted display can be made compact and lightweight.

Abstract: Disclosed is an optical system for a head-mounted display, in which image rays provided from a display device are diverged to form and provide an enlarged image. First, second, and third lenses or first, second, third, and fourth lenses are sequentially disposed from an object along an optical axis and provide the enlarged image on an image plane, and angles of principal rays are gradually increased from the optical axis toward an edge of the image plane. Thus, as the angles of principal rays increase, the angle of view is improved to provide a large image so that it is possible to appreciate a vivid image due to an increase in the sense of presence and the degree of involvement. The size of the entire optical system can be reduced, thus a head-mounted display can be made compact and lightweight.