Question

estion 4 (a) Expand the acronym CCD marks) (b) State how charge is 'read out' of a CCD detector and how this could result in a higher-quality digital image, as opposed to using a CMOS detector, when employed in a digital camera. (c) Determine the scale (to the nearest order of magnitude) at which engineering has to be carried out in order to generate a 7 megapixel image from a sensor measuring 2 cm x 2 cm. (d) Put the following list of components into the order they must be stacked for the correct operation of a liquid crystal display (LCD), starting at the front: polarizer 1, polarizer 2, reflector, patterned front electrode plate, back electrode plate, liquid crystal. od (e) State two benefits of using LCD technology in a small portable device such as a digital camera.

Answer 1

a) CCD stands for Charged coupled Device.

b) For the CCD, electrodes in each pixel are arranged so that the charge is transferred downwards along the columns. Hence, during the CCD clocking operation, rows are transferred downwards to the final row (the readout register) which is used to transfer the charge in each pixel out of the CCD so it can be measured.

In the read out register, the electrodes are arranged so that the charge is transferred in the horizontal direction, along the readout register.

At the end of the readout register is an amplifier which measures the value of each charge cloud and converts it into a voltagage, being around 5-10µV per electron.

d) Polarizer 1 - Patterned Front Electrode Plate - Liquid Crystal - Polarizer 2 - Back Electrode Plate - Reflector

e) It enables us to see the content of the camera live on the LCS display before clicking an image.