Abstract Hop spacer field emission display (HOPFED) has several advantages like the well use of secondary electron and the outstanding focus effect. To decrease the manufacture cost of HOPFED, the driving voltage has to be small enough. In this paper, an improved structure has been proposed to decrease the driving voltage. © 2008 Elsevier B.V. All rights reserved. PACS: 79.20.Hx; 85.45.Fd; 07.77.Ka Keywords: Secondary electron; Driving voltage; Field emission electron source 1. Introduction Compared to CRTs, Field Emission Displays (FED) potentially have a low cost and smaller depth. However, there are still some technical issues that prevent the mass production of FED. In order to become a successful product, the FED has to reach good picture quality and low cost. HOPFED is a new structure based on the secondary electrons emission [1]. With modulation of the energy of the primary electrons, the number of the electrons passing through the hop aperture can be controlled. In a matrix display device, a large fraction of the set cost is covered by the driving electronics. Therefore, a low driving voltage has to be applied to decrease the cost [2]. In this paper, the driving characteristic of a HOPFED is simulated with a software based on Monte-Carlo method. Then, an improved structure has been proposed, and its emission character is also simulated. From the comparison of the simulation results, it can be seen that the structure proposed in this paper can reduce the driving voltage significantly.