Electrostatic 3-d printer controlling layer thickness using feedback loop to transfer device

Abstract

3-D printers include an intermediate transfer surface that transfers a layer of material to a platen each time the platen contacts the intermediate transfer surface to successively form a freestanding stack of layers of the material on the platen. A sensor detects the thickness of the layer on the platen after a fusing station fuses the layer. A feedback loop is electrically connected to the sensor and a development station (that includes a photoreceptor, a charging station providing a static charge to the photoreceptor, a laser device exposing the photoreceptor, and a development device supplying the material to the photoreceptor). The development station adjusts the transfer bias of the development device, based on a layer thickness measurement from the sensor through the feedback loop, to control the thickness of subsequent ones of the layers transferred from the intermediate transfer surface to the freestanding stack on the platen.