A circuit for providing an output voltage for a DRAM word line which can be used to drive memory word lines which can be as high as 2Vdd. The projection objective includes a system aperture stop and refractive andor reflective optical elements that are arranged relative to an optical system axis. Based on these residues and parameters stored in a coding parameter storage section, component codes constructed by continuous sequences of 1 and 0 using a predetermined number of bits as a unit are respectively generated by component code generating sections. The downhole unit is operable to house the logging tool. The first region of the base portion is capable of being folded back towards a second region of the base portion that includes the first edge, and the engaging portion of the second reinforcing member is capable of being engaged with the first reinforcing member.