Abstract: Controller 40 receives accelerator opening and brake depressing amounts, and the output of an ammeter 30 and voltmeter 32 as inputs. In response to the state of these input signals, the controller 40 determines the timing to detect the state of charge (SOC) of the battery 10 and detects the SOC of the battery 10. That is, it is first judged that the SOC is not more than a predetermined value if the voltage of the battery 10 is not more than a predetermined value when the accelerator opening is not more than a predetermined value. It is next judged that the SOC is not more than a predetermined value if the voltage of the battery 10 is not more than a predetermined value when the brake is depressed beyond a certain degree. In these cases, the engine 24 is driven to cause a generator 22 to perform generation of electricity to charge the battery 10.

Abstract: A file data retrieving system includes a filing device for storing file data and retrieval-use-image data used for retrieving file data. The file data is stored in a predetermined data form. The retrieval-use-image data has an image density smaller than that of the file data. The system also has an image data reproducing circuit for reproducing image data to be displayed from each of the file data and the retrieval-use-image data. Further the system has a display unit for displaying the image data supplied from the image data reproducing circuit. The display unit displays the image data reproduced from the retrieval-use-image data at the time of retrieval of the file data.