Abstract: A battery pack and a method of diagnosing a failure of an overcurrent detection circuit are provided to diagnosing the overcurrent detection circuit so as to maintain the overcurrent detection circuit in a safe state. A detection signal output from a current detection element connected to an output side of a battery unit is compared with a threshold value. An overcurrent is detected when the detection signal indicates an overcurrent value exceeding the threshold value. In the method, a failure of the overcurrent detection circuit is detected by inputting an overcurrent diagnostic signal to the overcurrent detection circuit.

Abstract: To provide a digital camera for taking an image inside the oral cavity without causing a sanitary problem and enabling a dentist to easily monitor an object in the oral cavity of a patient on a screen and the patient to easily view the object on the screen when the camera is used. A digital camera for taking an image inside the oral cavity comprises a camera body (2) including a lens barrel (2a) to be inserted into the oral cavity, an intermediate part continuous to the lens barrel (2a), and a grip (2b) continuous to the intermediate part; and a dental instrument (3) detachably fitted onto the lens barrel (2a). On the intermediate part of the camera body (2) is mounted a liquid crystal display (2c).