Abstract: A power supply device includes a secondary battery and a charger, and can further utilize an external D.C. power supply. A switch is interposed between a negative electrode of the secondary battery and the ground. This switch is turned OFF when the external D.C. power supply is connected to the power supply device, and is turned ON when the external D.C. power supply is removed from the power supply device. The charger controls the charge of the secondary battery from the external D.C. power supply by regulating the potential of the negative electrode of the battery. A contact remains OFF while the external D.C. power supply is connected to the power supply device. In consequence, a current does not directly flow from the external D.C. power supply to the secondary battery. Therefore, a back-flow prevention diode, which otherwise results in power consumption, need not be disposed between the secondary battery and the load.

Abstract: In a paper-punching device for use in an image-forming apparatus, the rear edge of a sheet of paper that is being transported through a transport guide is detected by the photosensor. After a predetermined time has passed since the detection, a punching device is activated. At this time, a punching member is depressed downward, and a punching blade attached to its top penetrates through the sheet of paper, thereby forming a punch hole. Even during the punching operation, transport rollers continue to rotate. Therefore, when the sheet of paper is caught by the punching blade, the transport rollers are allowed to slip a predetermined amount with respect to the paper. For this reason, at least one of the transport rollers is made of a foamed material. With this arrangement, since the punching operation is carried out on the rear side of the sheet of paper, it becomes possible to reduce the occurrence of paper jams even if sheets of paper are transported in succession.

Abstract: A power supply apparatus includes a battery, a voltage converter for converting the output of the battery to a different D.C. voltage by ON/OFF action of a main voltage converter control switch circuit, and a device for estimating a remaining capacity of the battery. The remaining battery capacity estimation device detects a non-load voltage of the battery when the main voltage converter control switch circuit is OFF, and estimates the remaining capacity of the battery.

Abstract: A power source device capable of using both an external DC power source and a battery contained therein, and an electronic device using this power source device. A circuit is provided to measure the battery voltage, to calculate the remaining capacity of the battery and to indicate the remaining capacity. Means is provided which detects the state where no battery is mounted in the power source device, and short-circuits the input side of the battery voltage-measuring circuit. When no battery is mounted, therefore, a voltage leaking from the external DC power source is not erroneously measured as the battery voltage, and the remaining amount of power of the battery is correctly calculated.

Abstract: A battery protection circuit for protecting a battery is proposed. The circuit includes a detecting circuit for detecting a battery condition and producing a detected voltage in relation to the battery condition, a comparator comparing the detected voltage with a given voltage, and a switching circuit controlling a connection between the battery and electrical elements. In the battery protection circuit, when the comparator determines that the battery needs to be protected from the battery condition, the switching circuit turns off to disconnect the battery from the electrical elements.

Abstract: An automatic document feeder having a recirculating conveying path with a first switchback means between the document hopper and a presentation area interfacing with the scanning exposure region of an optical reading apparatus and a second switchback means between the presentation area and the document hopper, each such switchback means being selectively operable to either invert the surfaces or reverse the leading and trailing edges of the document for presentation at the presentation area, so as to facilitate document handling in the event of jamming and to reduce the size of the feeder. Additionally, the feeder can be used in correspondence with a copying machine having a conveying path with a third switchback means located between a photosensitive drum and an intermediate tray for reversing the leading and trailing edges of the copying paper and a fourth switchback means located between the photosensitive drum and a discharge hopper for inverting the surfaces of the copying paper.

Abstract: A lens repositioning device for use in a copying machine which device comprises a generally elongated lens carriage having a lens assembly fixedly mounted thereon; a single traction cable adapted to be driven by a drive unit and including generally intermediate first and second cable portions over the length thereof which extend parallel to each other and are, when the traction cable is driven by the drive unit, moved at the same velocity and in the same direction, and a guide member. The lens carriage is rigidly connected at its opposite ends with the respective first and second portions of the traction cable. The guide member is operable during the movement of the traction cable accompanied by the movement of the lens carriage to guide the lens assembly to follow a curved path of a predetermined configuration.

Abstract: A document scanning device such as a copier has defined within itself a point at which the brightness of an original document is detected and a separate point at which the document is scanned. The level of light exposure given to the document is controlled according to the detected brightness. The distance between the aforementioned two points is set with the delay time of an exposure control circuit taken into account. The delay time is set according to the fastest scanning speed of the device and is increased by means of a delay circuit if the scanning speed is deceased.