Transparent heaters are optically transparent substrates with electrically conductive coatings or grids. When current flows across the coating or grid, it generates heat. Dontech Therma Klear™ brand transparent heaters provide the warmth necessary to extend the operating temperature of LCDs (liquid crystal displays) in cold environments (e.g., from 0° to below -40°C) and for the anti-fogging, anti-icing, and de-icing of optics and optical displays. Dontech manufactures heaters using different types of glass, plastic, and crystalline substrates. Therma Klear Flex™ transparent heaters allow this same technology to be applied to flexible substrates (e.g., PET) for easy application to displays and touchscreens.
The transparent conductive coating in an optical heater is primarily composed of indium tin oxide (ITO), especially for visible and Near IR applications. In these cases, the ITO can be dielectrically enhanced with index matched thin film coatings to improve reflection and transmission properties in the desired optical performance band. By index matching, reflection losses are converted to transmitted light. Dontech can index match conductive coatings to air (n=1), to the optical substrates (typical: n= 1.41 through n = 2.44), or to an optical adhesive (typical: n=1.41 through n = 2.36). Standard conductivities for ITO coatings range from <1 ohm/sq to >500 ohms/sq. Common applications include avionic displays, military targeting systems, vehicle displays, mobile computers, kiosks, and handheld devices. Dontech designs and produces transparent conductive coatings to meet the following environmental and quality standards in addition to both internal and custom environmental and optical requirements:
For longer wavelength optical heater applications, conductive optical grids need to be utilized, as the ITO coating will no longer be transparent. In all cases, the conductive coating will make contact with two isolated highly conductive busbars. When voltage is applied, the conductive coating generates heat across the surface of the substrate. Transparent heaters can be supplied with wires, connectors, and temperature feedback sensors.
Dontech has extensive engineering and technical support resources that can assist you with your transparent heater design needs. Our technical staff have diverse backgrounds relevant to high-performance display and precision optics markets. For many of our top customers, we function as an extension of their engineering departments, supporting projects from concept to final system delivery. We will integrate our optical filters and other enhancing components into touchscreens, displays, and systems to the level that is needed by our customers.