mortgage seeks to enforce its right against the Oakland, Antioch & Eastern Railway, the lessee, it must sue to foreclose the mortgage, and should there be a deficiency it may pursue the lessee therefor. This rule is based on the ground that a creditor is entitled to enforce all collateral obligations for the payment of his debt which *53 a person standing in the situation of a surety for others holds for his indemnity. The application of this principle is made possible by the aid of the doctrine of equitable subrogation, under which the lessee, by the assumption of the debt has become, as to the lessor, the principal debtor, the lessor occupying thereafter the position of surety." A petition to have this case heard in the Supremethe same directions as the image scanning unit. It should be noted that the processing unit is an integral assembly of a drum unit having a photoconductive drum and a developing unit having a developing sleeve.
In this prior art, the image forming apparatus and the image scanning unit are coupled in series by at least two two-parts link members, and the link members are provided with means for holding the opening cover, whereby the opening cover is opened and closed by the holding means of the link members that move as the image scanning unit is opened and closed.
However, since such an opening and closing technique requires at least two two-parts link members and requires the link members to be provided with the holding means for the opening