Abstract: An electroluminescent display comprising a mask (13) defining the information to be displayed mounted in front of an electroluminescent (EL) material backlight (16). The mask (13) comprises a layer of liquid crystal vesticles (14) encapsulated in a curable polymer matrix (15), where the polymer chains of the polymer matrix (15) have been cross-linked by exposure to radiation. Preferably the polymer matrix is a UV curable polyurethane. The invention also concerns a method of making such a display.

Abstract: An electroluminescent layer for a light. The light includes a phosphor with a fluorescent pigment or dye.

Abstract: A drive circuit of a display device comprising a capacitive display (H1) and a further display H2. The drive circuit is arranged to provide to the capacitive display, such as an electroluminescent display, an AC drive signal at a first, high voltage from a low voltage power source such that, in use, the drive circuit is repeatedly charged and discharged. The drive circuit is further arranged such that, when the capacitive display discharges, a discharge current from the display is supplied at a second, lower voltage to the further display. In the way energy from the capacitive display is used to drive a further display rather than being discarded.

Abstract: An electroluminescent circuit for driving an electroluminescent display having a plurality of segment electrodes and a common electrode. The circuit comprises a DC power supply, an output terminal for each of the segments and common electrodes and at least one supply half H-bridge for connecting at least one of each of the segment electrodes and the common electrode selectively to one of the DC supply and a reference voltage. Each supply half H-bridge comprises a top switch and a bottom switch in series having a junction between them. The top switch is connected to the DC supply and the bottom switch is connected to a reference voltage. A discharge circuit is provided for selectively discharging the electroluminescent display, the discharge circuit comprising a discharge half H-bridge in which a top switch is connected to the DC supply and to a discharge path.

Abstract: A drive circuit for driving electroluminescent (EL) segments and polymer dispersed liquid crystal (PDLC) segment of a display. The circuit may include a flyback converter for generating an A.C. output voltage, a first switching circuit for selectively connecting the output voltage to the EL segments, and a second switching circuit for selectively connecting the output voltage to the PDLC segments. In order to drive the EL segments and PDLC segments at the required frequencies, the polarity of the output voltage applied to the PDLC segments is swapped at a frequency lower than the frequency at which the polarity of the output voltage is swapped for the EL segments. In this way, only a single high voltage power supply is required to drive both the EL and PDLC segments.

Abstract: An electroluminescent display of the type having a switchable electroluminescent (EL) material backlight (16) mounted behind a mask (13) defining the information to be displayed, in which display the mask is constructed as a layer of physically-stabilised Liquid Crystal (LC) material (14) switchable to define the information to be displayed; and the LC mask and the EL backlight are constructed as a single entity. The LC mask may be directly formed on the EL backlight, or there may be an insulating interlayer (10) between LC mask and EL backlight. The LC mask and EL backlight may be held between a common pair of electrodes (11, 20).

Abstract: An electroluminescent display comprising a substrate (1), a substantially transparent electrode (2) adjacent to the substrate, a layer of electroluminescent material (3) adjacent to the substantially transparent electrode, a layer of dielectric material (4) adjacent to the layer of electroluminescent material and a further electrode (5) adjacent to the dielectric layer, in which there is further provided an intermediate layer (6) between the substantially transparent electrode and the layer of electroluminescent material. The intermediate layer typically acts as a diffuser and may comprise Barium Titanate.

Abstract: Certain materials are electroluminescent, and this electroluminescent effect has been used in the construction of backlights for displays. Such a backlight commonly consists of a transparent front layer (11) known as the substrate carrying its rear face a transparent electrically-conductive film (12) forming the backlight's front electrode and covered by a layer of electro-luminescent/phosphor material (13) over the rear face of which is a high-dielectric layer (16) bearing on its rear face a conductive film (17) forming the back electrode. The whole is positioned behind a mask (18) that defines whatever characters the display is to show. This use of a mask has some disadvantages, some of which can be overcome by utilising an array of suitably shaped individual electrodes (21) instead of a continuous one, and by shaping the electroluminescent material itself in discrete areas (43) each tightly matching in shape and size the relevant individual shaped back electrode (21).

Abstract: A light-emitting display having display areas (14), which may be lit or unlit, comprising a sensor (13) for ambient light, in which the display is arranged to use an output of the sensor (13) to modify the brightness of the display areas (14) when lit in dependence upon the ambient tight conditions, the sensor being hidden behind an unlightable section of the display. The display is particularly advantageously an electroluminescent display.

Abstract: A membrane switch comprising a flexible membrane (32, 38, 138) forming a movable part of the switch, the flexible membrane comprising an electroluminescent display (38, 138). More specifically, a switch of the non-latching type, typically for use with a flexible electroluminescent display, which switch comprises: an underlying circuit layer (31, 131) carrying a circuit (34, 35, 134, 135) which the switch is to operate, the circuit being broken by a gap (36, 136) which the switch is to close; a resiliently-deformable contact layer (32, 38, 138), mounted to face the circuit layer's circuit face, the contact layer's circuit-facing surface carrying a conductive bridge portion (37, 137) aligned with the gap, which bridge portion can be resiliently pushed into operative contact with the circuit layer to close the gap therein so long as an applied pushing force (F) is present; and spacing means (33, 133) that keeps the two layers apart in the absence of any applied force pushing them together.

Abstract: A controller for use with a multi-segment electroluminescent display 1. Control signals C1–CN control a plurality of half H-bridges H and Hc, the terminals of the half H-bridges being connected respectively to ground and to a high voltage DC supply 9. One of said half H-bridges provides a common output Vcommon and the remaining H-bridges provide drive voltages V1–VN for the segments of the display. The H bridges are driven by an oscillator 14 so that an AC voltage is selectively applied to the segments of the display. A power supply 24 provides a predetermined amount of power per unit area of the display. This is controlled by an area summation engine 22 having a segment data input, a segment counter and a memory containing area data corresponding to the segment(s) of the display. Based on the input from the segment data input, the area(s) of the segment(s) that are to be lit are obtained from the memory and summed to provide the total area to be lit.

Abstract: An electronic circuit for providing a high voltage alternating current supply from a DC supply to an electroluminescent lamp. The circuit includes an inductive element and an output switching element arranged in series. The output switching element is operable to alternate, in use, between a first state and a second state, whereby in the first state a current path is provided through the inductive element and the output switching element, which current path is interrupted in the second state, such that when the output switching element changes from the first state to the second state, the inductive element generates a voltage at an output of the circuit for charging the electroluminescent lamp. The circuit includes an output diode arranged to prevent current flowing back from the output while the output switching element is in the first state.

Abstract: Certain materials are electroluminescent, and this electroluminescent effect has been used in the construction of backlights for displays. Such a backlight commonly consists of a transparent front layer (11) known as the substrate carrying over its rear face a transparent electrically-conductive film (12) forming the backlight's front electrode and covered by a layer of electroluminescent/phosphor material (13) over the rear face of which is a high-dielectric dielectric layer (16) bearing on its rear face a conductive film (17) forming the back electrode. The whole is positioned behind a mask (18) that defines whatever characters the display is to show. This use of a mask has some disadvantages, some of which can be overcome by utilizing an array of suitably shaped individual electrodes (21) instead of a continuous one; however, this itself has drawbacks, since the lead (22) to each electrode acts as an electrode in its own right, activating the phosphor to show faint but distracting additional illumination.

Abstract: A controller 2 is provided for use with a multi-segment electroluminescent display 1. Control signals C1–C5 control a plurality of half H-bridges H1–H5, the terminals of the half H-bridges being connected respectively to ground 10 and to a high voltage DC supply 9 so that the half H-bridges each provide an AC voltage. One of said half H-bridges provides a common output Vcommon and the remaining H-bridges provide drive voltages V1–V4 for the segments of the display. During each cycle, the controller 2 causes the drive outputs V1–V4 to either be in phase or in anti-phase with the common output Vcommon. This selectively turns the segments on and off at a rate much higher than the human eye can perceive. The brightness of the segments is controlled by varying the proportion of the time that each segment is illuminated.

Abstract: A high voltage AC power supply circuit for a capacitive load CL, such as an electroluminescent lamp, includes a low voltage DC supply, an inductor L and a FET S in series. The FET S can be pulsed so that the inductor L generates a voltage to charge the capacitive load CL via an H-bridge H, which is in parallel with the FET S. A diode D prevents current discharging from the capacitive load CL while the FET S is closed. The total capacitance downstream of the diode D and in parallel with the capacitive load CL is less than the capacitive load CL, so that when the polarity of the H-bridge is reversed, the voltage across the H-bridge collapses to earth and the capacitive load CL is discharged via the low voltage DC supply. The circuits which a employ a large smoothing capacitor in parallel with the H-bridge.

Abstract: Certain materials are electroluminescent, and this electroluminescent effect has been used in the construction of backlights for displays. Such a backlight commonly consists of a transparent front layer (11) known as the substrate carrying over its rear face a transparent electrically-conductive film (12) forming the back-light's front electrode and covered by a layer of electroluminescent/phosphor material (13) over the rear face of which is a high-dielectric dielectric layer (16) bearing on its rear face a conductive film (17) forming the back electrode. The whole is positioned behind a mask (18) that defines whatever characters the display is to show. This use of a mask has some disadvantages, some of which can be overcome by utilizing an array of suitably shaped individual electrodes (21) instead of a continuous one; however, this itself has drawbacks, since the lead (22) to each electrode acts as an electrode in its own right, activating the phosphor to show faint but distracting additional illumination.

Abstract: Certain materials are electroluminescent, and this electroluminescent effect has been used in the construction of backlights for displays. Such a backlight commonly consists of a transparent front layer (11) known as the substrate carrying over its rear face a transparent electrically-conductive film (12) forming the backlight's front electrode and covered by a layer of electroluminescent/phosphor material (13) over the rear face of which is a high-dielectric layer (16) bearing on its rear face a conductive film (17) forming the back electrode. The whole is positioned behind a mask (18) that defines whatever characters the display is to show. This use of a mask has some disadvantages, some of which can be overcome by utilizing an array of suitably shaped individual electrodes (21) instead of a continuous one; however, this itself has drawbacks, since the lead (22) to each electrode acts as an electrode in its own right, activating the phosphor to show faint but distracting additional illumination.

Abstract: An electroluminescent lamp or display comprises a first electrode on a substrate interdigitated with a second electrode on the same substrate. A layer of electroluminescent material is provided over the electrodes. The arrangement has the advantage that light from the electroluminescent material does not need to pass through either of the electrodes. The substrate may be a printed circuit board. In an alternative embodiment the second electrode is provided over the layer of electroluminescent material and gaps are provided in the electrode for the emission for light. The electroluminescent lamps may be used to form a seven-segment display.