This paper presents a projection on the basis of the true 3D imaging display system and analyzes construction for the voxel. We proposed a new method based on the theory of high-speed projector - Three DMD/OLED coaxial optical path display. We did some experiments about the clock distribution for the coaxial optical path. The innovation improves frame rate and operating stability for the display device, reduces the high frame rate on one single device. We also found a new approach - local state-space model - Fornasini-Marchesini for constructing the volume pixels. The mechanism is simple to build and low price; the optical field can be displayed in the whole above x-y plane except the zenith point.