Abstract: Provided are a projection system, a projection apparatus, and a calibration method for a displayed image thereof.

Abstract: Provided are a projection system, a projection apparatus, and a calibration method for a displayed image thereof.

Abstract: The disclosure provides a projection system and a projection method using the projection system. The projection system can project a projection beam toward the projection target. The projection system includes an image capturing device and a projection device. The image capturing device can capture an appearance image containing the path target as image information. The projection device is electrically connected to the image capturing device. The projection device can provide a projection beam, and the projection beam includes a first beam and a second beam. The path target is located on the transmitting path of the first beam, and the second beam is projected to the projection target. The projection device can adjust the luminous intensity of the first beam according to the image information, so as to reduce the luminous intensity of the first beam.

Abstract: A signal filtering device is provided. A photoelectric conversion unit is used to convert a light signal into an electric signal, and an input signal adjusting unit is used to decrease a DC component of the electric signal flowing through a DC filtering unit and adjust an AC component of the electric signal.

Abstract: An optical touch device defining a sensing area includes two scanning modules and a light detecting element. The scanning modules respectively disposed on terminals of a first side of the sensing area include light-emitting elements and reflective elements. The light-emitting element is used for emitting a detective light along a first pathway and the reflective element has a reflective surface for reflecting the detective light such that the detective light is emitted along a second pathway. There is an angle forming between the first side and the second pathway and the reflective surface changes a direction of the second pathway such that the detective light scans in the sensing area. The detective light has a first intensity and a second intensity, in which the first intensity is less than the second intensity. The light detecting element is used for receiving a detective light reflected by an object.

Abstract: A laser scanning device and a control method thereof are provided. The method includes: providing a control signal to an oscillating reflective mirror of the device; setting a frequency of the control signal gradually decreased from a maximal-setting-value of a resonant frequency of the mirror; judging whether a light detector receives a laser light reflected by the mirror according to an edge signal of the detector; judging whether a pulse width of the edge signal is equal to a predetermined pulse width when the detector receives the laser light: (1) increasing the frequency of the control signal when the pulse width of the edge signal is greater than the predetermined pulse width, (2) decreasing the frequency of the control signal when the pulse width of the edge signal is less than the predetermined pulse width. The time and labor for measuring the scanning frequency of the mirror may be saved.