JAJSF42B April 2018 – June 2019 DLPC3478
For supporting 3D glasses, the DLPC3478 device-based chip set outputs sync information to synchronize the Left eye/Right eye shuttering in the glasses with the displayed DMD image frames.
Two different types of glasses are often used to achieve synchronization. One relies on an infrared (IR) transmitter on the system PCB to send an IR sync signal to an IR receiver in the glasses. In this case device output signal GPIO_04 can be used to cause the IR transmitter to send an IR sync signal to the glasses. The timing for signal GPIO_04 is shown in Figure 9.
The second type of glasses relies on sync information that is encoded into the light being outputted from the projection lens. This is referred to as the DLP Link approach for 3D, and many 3D glasses from different suppliers have been built using this method. This demonstrates that the DLP Link method can work reliable. The advantage of the DLP Link approach is that it takes advantage of existing projector hardware to transmit the sync information to the glasses. This can save cost, size and power in the projector.
For generating the DLP Link sync information, one light pulse per DMD frame is outputted from the projection lens while the glasses have both shutters closed. To achieve this, the device signals the DLPA200x device or DLPA300x device when to enable the illumination source (typically LEDs or lasers) so that an encoded light pulse is output once per DMD frame. Because the shutters in the glasses are both off when the DLP Link pulse is sent, the projector illumination source is also disabled except when the device sends light to create the DLP Link pulse. Figure 28 and Figure 29 show the timing for the light pulses for DLP Link 3D operation.
|HDMI Source Reference||3D DMD SEQUENCE RATE (Hz)||A||B||C||D||E|