Developer liquid supplying method and device for liquid development electrophotography

Claim 1

A developer liquid supplying device in liquid development electrophotography comprising a developer liquid tank, a tank for supplying developer liquid to house a developer liquid for supply prepared in advance of a supply concentration Dp to maintain a predetermined fixed quantity V to have a predetermined fixed concentration D of a developer liquid in a developer liquid tank and at a required predetermined level corresponding to said predetermined fixed quantity V, a developer liquid supplying path connecting said tank for supplying developer liquid to said developer liquid tank, a valve means for opening and closing said developer liquid supplying path by detecting the quantity of developer liquid in said developer liquid tank by which said valve means is opened only when the quantity of developer liquid decreases below said predetermined level, maintaining the concentration D of developer liquid in said developer liquid tank by replenishing a quantity Vn of the developer liquid from a supply concentration Dp in proportion to the decrease of a quantity Vn of the developer liquid, Vn being the quantity consumed by n copies out of the quantity V of the developer liquid of said predetermined fixed concentration D to constantly maintain said quantity V at said predetermined level, and restoring a concentration Dn of the developer liquid in the tank decreased through development to at least an initial concentration D by replenishing a developer liquid of said supply concentration Dp, the following formula being used as a criterion for calculating said concentration Dp: where Dn is the density of the developer liquid after having developed n copies of photosensitive paper, and Dp>D>Dn, an intermediate developer liquid tank disposed below said tank for supplying said developer liquid and above said developer liquid tank and disposed in said supplying path connecting said tank for supplying the developEr liquid and said developer liquid tank and receiving developer liquid from said tank for supplying developer liquid, a constant fluid surface-type automatic valve disposed between said tank for supplying developer liquid and said developer liquid supply tank for communicating said tanks with each other and including a spring biased valve rod disposed against the bottom of said intermediate developer liquid tank and causing said automatic valve to open communication between said tanks, said bottom of said intermediate developer liquid tank is concavely shaped extending down toward the developer liquid in said developer liquid tank, said tank for supplying developer liquid has an opening in which said automatic valve is cooperatively disposed and which extends downwardly into said intermediate developer liquid tank, and said valve means constitutes a float operated needle valve disposed in said developer liquid tank, a plate, connected to said developer liquid tank adjacent the top thereof, at least one guide plate supported by said plate and curving into said developer liquid and having longitudinal slots therein, said intermediate developer liquid tank being supported over one of said guide plates, said tank for supplying developer liquid extending at its bottom into said intermediate developer liquid tank, said valve means further comprising a pipe having a longitudinal opening cooperating with said float operated needle valve and secured to said plate, and a horizontally disposed pipe communicating said intermediate developer liquid tank with said longitudinal opening in said pipe.