An electrical resonance network comprising a first capacitor and a first inductor whose resonance frequency can be tuned by means of a second capacitor and/or a second inductor. The resulting effective capacitor- or inductor value of a network period is controlled by a variable coupling respectively decoupling interval by means of at least one coupling switch. The coupling respectively decoupling interval is synchronized by a sign change of a current and/or voltage in the network.

An electrical resonance network comprising a first capacitor and a first inductor whose resonance frequency can be tuned by means of a second capacitor and/or a second inductor. The resulting effective capacitor- or inductor value of a network period is controlled by a variable coupling respectively decoupling interval by means of at least one coupling switch. The coupling respectively decoupling interval is synchronized by a sign change of a current and/or voltage in the network.

An object of the present invention is to provide an imaging apparatus that can comfortably be focused while an influence on a wide angle image is minimized. The imaging apparatus includes: a display unit for displaying an image being photographed; an enlarged image display function for displaying an image obtained by enlarging a part of an area being photographed in the display unit; an edge component detection function for detecting an edge component amount of an enlarged image area; and a focal point position detection function for detecting movement of a focal point operated by a photographer. Duration time of the enlarged image display displayed by the enlarged image display function is changed in conjunction with the edge component detected by the edge component detection function and the movement of the focal point detected by the focal point position detection function.

A secure telephone call management system is provided for authenticating users of a telephone system in an institutional facility. Authentication of the users of the telephone call management system is accomplished by using a personal identification number, biometric means, and/or radio frequency means. The secure telephone call management system includes accounting software capable of limiting access to the system based on funds in a user's account, and includes management software capable of implementing widespread or local changes to the system. The system monitors a conversation in the telephone call to detect a presence of a first characteristic in audio of the conversation, and terminates the telephone call if the first characteristic does not match a second characteristic of biometric information of a user or a called party.