Slim infrared LED targets optical touch screens
The new Osram SFH4053 requires only 0.45mm of height within the frame. Thus, it suits well for deployment in tablet computers. The IRED however is powerful enough to illuminate relatively large displays of laptop computers.
The components of optical touch screens are placed in a slim bezel around the display panel. Typically, such a bezel has a height of 0.5 to 1mm. Rows and columns of opposite ILEDs and detectors span an invisible infrared light grid across the display panel. Large notebook and all-in-one-computer displays typically are illuminated from two corners with infrared light. Camera sensors next to the IRED can detect a signal only when the user’s finger on the display reflects the light emitted by the IRED. This method gets along with relatively few components, but it requires IREDS with very high radiation power.
Osram Opto Semiconductors’ new SFH4053 comes in a very slim ChipLED package with a size of only 0,5 x 1mm. Thus, the component is among the slimmest ones currently obtainable. It emits light at a wavelength of 850nm which is invisible for the human eye. Due to its high-efficiency thin film chip technology the IRED offers high light yield at low currents and thus it can be used in portable battery-powered devices. In continuous operation mode the device provides a radiation power of up to 35mW at a current of 70mA. In pulse mode, the radiation power can be raised significantly.