Abstract: An acoustic reflector includes a reflection portion on which an elliptical reflection surface is formed, in which sound output from a speaker device that has an output position of the sound at or near one focal point on the elliptical reflection surface is reflected by the elliptical reflection surface, and the reflection portion has a size that reflects sound in a range of equal to or less than a nominal directional angle of the speaker device. As a result, because an outer shape of the reflection portion is formed to have a size in the range corresponding to the nominal directional angle of the speaker device, it is possible to reduce the size of the acoustic reflector.

Abstract: An acoustic reflector includes a reflection portion on which an elliptical reflection surface is formed, in which sound output from a speaker device that has an output position of the sound at or near one focal point on the elliptical reflection surface is reflected by the elliptical reflection surface, and the reflection portion has a size that reflects sound in a range of equal to or less than a nominal directional angle of the speaker device. As a result, because an outer shape of the reflection portion is formed to have a size in the range corresponding to the nominal directional angle of the speaker device, it is possible to reduce the size of the acoustic reflector.

Abstract: An electronic instrument having a resettable security code as a way of preventing the burglary of the electronic instrument mounted to a movable device such as a car. When the electronic instrument is mounted to the movable device or a battery is exchanged, the entry of the security code is required by the user. If the user does not know or remember the security code, a random number is automatically generated inside of the electronic instrument and converted into an initializing code according to the predetermined rules. The user reports the generated random number to a service company or the manufacturer. The service company or the manufacturer checks if the user is registered. When the user is certified, the service company or the manufacturer gives the initializing code corresponding to the random number to the user. Then, the user enters the given initializing code for resetting the security code.