Electroluminescent display device

• Main Authors: TAKAHARA, KAZUHIRO, MIURA, SHOSHIN, GONDO, HIROYUKI, KURAHASHI, KEIZO, OKI, KENICHI
• Format: Patent
• Language: English; French; German
• Published: 05.01.1983
• Subjects: ADVERTISING; ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICESUSING STATIC MEANS TO PRESENT VARIABLE INFORMATION; CRYPTOGRAPHY; DISPLAY; DISPLAYING; EDUCATION; LABELS OR NAME-PLATES; PHYSICS; SEALS; SIGNS

One electrode of an electroluminescent display element (EL) is connected to receive an AC voltage (+/-VA). The other electrode of the display element (EL) is connected to the drain terminal (D) of a switching transistor (Q2) the source terminal (S) of which is connected to a reference (earth) voltage. … When the switching transistor (a,) is ON, the drain terminal (D) is clamped to the reference voltage. The full AC voltage is applied across the display element (EL) which provides a luminous display. … When the switching transistor (Q2) is OFF, a diode element D2, effective between the drain terminal (D) and the source terminal (S), clamps the drain terminal (D) to the breakdown voltage of the diode element. … That breakdown voltage is less than the breakdown voltage of the switching transistor (Q2), so that the transistor is protected from non-recoverable breakdown, but is sufficiently great that the voltage (VEL) applied across the display element (EL) is not high enough to cause the display element (EL) to provide a luminous display.