Abstract: A moveable member which is moveable between first and second positions relative to an optical axis of an imaging camera is used to calibrate the camera. The moveable member has a first reference member positioned at the optical axis when the moveable member is in the first position, and has a second reference member positioned at the optical axis when the moveable member is in the second position. A preferred embodiment has a first calibration device for a front camera and a second calibration for a rear camera when both the front and the rear of the document are to be imaged. A single actuator is used to simultaneously move both moveable members of the first and second calibration devices between the positions mentioned.

Abstract: A method of the operation of an ionization smoke alarm which has a measuring chamber open to the ambient air and ionizable by a radioactive source. A measuring chamber includes a first electrode to which a supply d.c. voltage is applied and a measuring electrode the potential of which changes in response to the smoke density if smoke enters the measuring chamber. This potential is measured for producing a smoke alarm signal if it reaches a predetermined value. The potential of the measuring electrode is measured for at least one further electric field strength that is compared with at least a second potential which occurs at the second field strength according to the law of the agglomeration of small ions if smoke aerosols are present in the measuring chamber.

Abstract: A data processing device for reading a code signal output from the image output screen of a video receiver. The device is provided with a read controller to synchronize the code signal reading operation with the code signal display timing of the video receiver.