Initialization and Reset Methods

The stable characteristics of a DIAC make resetting ON pixels and display initialization quite easy and dependable. Below is the waveform we are currently developing. This waveform takes advantage of the DIAC's high speed switching characteristic. The ramp is used to drive a momentary discharge that triggers and ends rapidly. The holding current characteristic requires a certain current to maintain conductivity. The capacitivly coupled ramp is slow and does not provide sufficient current to maintain a discharge.

Reset and Initialization Waveform

Resetting ON Cells

The supply voltage Vs is used to supply the driving pulses. The last illumination discharge occurs with falling transition prior to T0. Consequently, the illumination cell is ready to be triggered at time t0. The figure shows voltage V0 being applied at time t0. Voltage Vo is not high enough to trigger the illumination cells, but it is set to be close to a minimum trigger voltage V1. The voltage range V1-V1 is the range where cells will trigger. As each ON cell triggers between times t1 and t2, the slowly rising ramp does not provide enough current to keep the DIAC in the conduction region. The result is a resetting of the cell to the OFF state. For convenience, a reset pulse can ramp up to voltage Vs.

Initialization

AC-coupled circuits require initialization. A DIAC based memory cell is no exception. Our waveform continues to ramp up to a voltage Vset at time t3. Visibly, it does not appear to do anything. It does NOT trigger a discharge on each application. Rather, Vset applies enough voltage to trigger the cells on power up, and will correct unstable cell voltages if they occur. Essentially, it creates a reference level for the AC-coupled cells. By using this approach, there is no background glow produced.