Abstract: A circuit board optimized for a denser component population within a standard size of footprint includes a mother board and a plurality of sub-board layers stacked on and connected to the mother board. Each of the sub-board layers has a plurality of daughter boards. The sub-board layers are composed of a first sub-board layer and a second sub-board layer. The daughter boards of the first sub-board layer are arranged on a side of the mother board, and the daughter boards of the second sub-board layer are arranged on the daughter boards of the first sub-board layer.

Abstract: A projector or group of projectors each includes a data acquisition module, a first storage, a first determining module, and a first communicating module. The data acquisition module acquires present working values of working portions of the projector. The first storage stores working parameters comprising fixed normal values when the projector and all its parts is in normal working state. The first determining module can determine whether a reading showing the present working value is consistent with fixed normal parametric value. The first communicating module communicates with a monitoring terminal, and when the present working value is not consistent with the fixed normal value, the present working value of the working parameter is transmitted to a monitoring terminal. A projector monitoring system and method are also disclosed.

Abstract: An electronic device shell can be configured to compactly receive at least one expansion card. The electronic device shell comprises a bottom plate, a front plate connected with a front end of the bottom plate, and a rear plate connected with a rear end of the bottom plate. The front plate is recessed away from the rear plate to form a first lead portion. The expansion card is located on the bottom plate and between the front plate and the rear plate. One end of the expansion card is secured on the rear plate, and the other end of the expansion card is received in the first lead portion.

Abstract: A system for controlling a robot by brain electrical signal, includes a screen, an electronic signal detection device, and a host computer. The screen shows a plurality of icons thereon, and the plurality of icons flashes at different frequencies. The electrical signal detection device detects brain electrical signal when one of the plurality of icons is stared. The host computer stores a plurality of personal reference parameters corresponding to the plurality of icons of the screen. The host computer processes the brain electrical signal to get parameters of use, and compares the parameters of use with the plurality of personal reference parameters to choose and execute the icon which is stared.

Abstract: A power control system allowing multiple voltage levels from a single power adaptor includes a power supply device and an electronic device. The power supply device includes a power supply and a first power controller. The power supply is configured to supply power for a graphics card as an external renderer, and the first power controller is configured to output a voltage signal. The electronic device includes a second power controller electrically coupled to the first power controller and the second power controller is configured for obtaining the voltage signal from the first power controller. The first power controller can output a first voltage or a second voltage to the second power controller to supply power for the electronic device.