Abstract: An installation jig used for installing information equipment in a rack, the installation jig has a pair of slidable members extending in a direction heading from a near side to a fore side of the rack, stoppers preventing the slidable members to be pushed over a predetermined position in the fore side and knobs pulling out the slidable members from the near side. The slidable members each have an inclined surface with a planar portion and each have a bottom with a planar portion, the bottom being formed at the side opposite to the inclined surface. A height between the bottom and the inclined surface is decreased from the near side to the fore side, and the inclined surface and the bottom is formed by using a material with a low friction coefficient.

Abstract: A drive controlling circuit for electric shutters provided with a plurality of discriminating circuits for detecting failures and a plurality of warning circuits including buzzers or luminous diodes operated by the discriminating circuits in order that various failures of the shutter in use can be positively and quickly known. This controlling circuit makes impossible to release the shutter when something is wrong with the shutter.