Abstract: A lead-free and copper-free tin alloy has 3.0-5.0 wt % (weight percentage) silver, 0.01-3.5 wt % bismuth, 0.01-3.5 wt % antimony, 0.005-0.1 wt % nickel, 0.005-0.02 wt % germanium and tin of a residual weight percentage. The lead-free and copper-free tin alloy can be used to manufacture solder ball for a ball grid array package, and the solder bump formed by the solder ball can withstand the thermal stress caused by the temperature change of the electronic component itself or the environment, and has the ability to withstand high mechanical shocks at the same time.

Abstract: Provided is an electronic device and an electric energy conversion method. The electronic device includes at least one moving component, a transducer system, a charging and discharging system, and a power supply system. The transducer system has at least one piezoelectric membrane and a storage unit. The at least one piezoelectric membrane is disposed on the at least one moving component, and the storage unit is electrically coupled to the at least one piezoelectric membrane. The charging and discharging system is electrically coupled to the at least one moving component and the transducer system. The power supply system is electrically coupled to the at least one moving component, the transducer system, and the charging and discharging system to provide main energy. The at least one moving component starts to operate, the at least one moving component leads the at least one piezoelectric membrane to deform elastically to generate assisting charges.

Abstract: The disclosure provides a method and a projection device for focal length calibration. The projection device includes a distance sensor, a projection lens, and a controller. The method includes: defining, by the distance sensor, a detection area on a projection surface; dividing, by the controller, the detection area into a plurality of reference areas; detecting, by the distance sensor, a reference distance between the projection device and each reference area; finding, by the controller, at least one first area and at least one second area in the reference areas; and performing, by the controller, a focusing operation of the projection lens only based on the reference distance of each second area.

Abstract: The disclosure provides a method and a projection device for focal length calibration. The projection device includes a distance sensor, a projection lens, and a controller. The method includes: defining, by the distance sensor, a detection area on a projection surface; dividing, by the controller, the detection area into a plurality of reference areas; detecting, by the distance sensor, a reference distance between the projection device and each reference area; finding, by the controller, at least one first area and at least one second area in the reference areas; and performing, by the controller, a focusing operation of the projection lens only based on the reference distance of each second area.

Abstract: A projection apparatus is provided, which includes a projector body, a first ultrasonic sensor and a second ultrasonic sensor. The projection apparatus is configured to project an image onto a screen. The first ultrasonic sensor and the second ultrasonic sensor are disposed on the projector body. The first ultrasonic sensor and the second ultrasonic sensor are respectively configured to measure a distance between the projector body and the screen. The projector body corrects the image in a horizontal direction through the first ultrasonic sensor and the second ultrasonic according to the measured distances. The first ultrasonic sensor and the second ultrasonic sensor are disposed on a first reference line corresponding to the first direction. The projection apparatus of the invention may provide good image quality.

Abstract: A projection apparatus is provided, which includes a projector body, a first ultrasonic sensor and a second ultrasonic sensor. The projection apparatus is configured to project an image onto a screen. The first ultrasonic sensor and the second ultrasonic sensor are disposed on the projector body. The first ultrasonic sensor and the second ultrasonic sensor are respectively configured to measure a distance between the projector body and the screen. The projector body corrects the image in a horizontal direction through the first ultrasonic sensor and the second ultrasonic according to the measured distances. The first ultrasonic sensor and the second ultrasonic sensor are disposed on a first reference line corresponding to the first direction. The projection apparatus of the invention may provide good image quality.

Abstract: A Bluetooth device used for data transmission between first and second peripheral devices is provided. The Bluetooth device includes a processing circuit and a Bluetooth chip configured to be capable of being operated in a transmitting mode and a receiving mode for data transmitting and data receiving, respectively. In the transmitting mode, a first communication link is established between the Bluetooth chip and the first peripheral device through a first communication protocol. The processing circuit establishes a second communication protocol. In the receiving mode, a second communication link is established between the Bluetooth chip and the second peripheral device through a third communication protocol. The second peripheral device transmits a data to the Bluetooth chip through the second communication link and the Bluetooth chip transmits, based on the second communication protocol, the received data to the first peripheral device through the first communication link simultaneously.

Abstract: A Bluetooth device used for data transmission between first and second peripheral devices is provided. The Bluetooth device includes a processing circuit and a Bluetooth chip configured to be capable of being operated in a transmitting mode and a receiving mode for data transmitting and data receiving, respectively. In the transmitting mode, a first communication link is established between the Bluetooth chip and the first peripheral device through a first communication protocol. The processing circuit establishes a second communication protocol. In the receiving mode, a second communication link is established between the Bluetooth chip and the second peripheral device through a third communication protocol. The second peripheral device transmits a data to the Bluetooth chip through the second communication link and the Bluetooth chip transmits, based on the second communication protocol, the received data to the first peripheral device through the first communication link simultaneously.