Abstract: A screen, a projection system and a focusing method are provided. The screen is used for presenting a projected image and it includes a screen body, a photosensitive detector and a processor. The photosensitive detector is on a projection surface of the screen body for collecting a gray level of the image presented on the screen body. The processor is for obtaining description information of the image according to the gray level of the image collected by the photosensitive detector, the description information of the image indicating definition of the projected image.

Abstract: The disclosure provides a focusing method of optical machine of projector, a focusing device and an optical machine. The focusing method comprises steps of: detecting deformation amount of lens of an optical machine; and controlling and adjusting a focal length of the lens of the optical machine according to the deformation amount of the lens of the optical machine. In the he focusing method, by detecting the deformation amount of the lens of the optical machine in real time and controlling to adjust the focal length of the lens of the optical machine in real time according to the deformation amount of the lens of the optical machine, the adjustment precision of the focal length of the lens of the optical machine can be greatly improved.

Abstract: The present disclosure discloses a vacuum adsorption unit and a vacuum adsorption carrier, wherein the vacuum adsorption unit comprises: a housing defining an air path through-hole therein, the air path through-hole provided with an upper abutting surface and a lower abutting surface; a piston movable provided in the air path through-hole and is located between the upper abutting surface and the lower abutting surface; an outer peripheral wall of the piston is slidably matched with an inner peripheral wall of the air path through-hole; an elastic member having both ends that respectively abut against the housing and the piston, to constantly drive the piston to abut on the upper abutting surface; and a pressure relief passage communicated with the air path through-hole, and is configured to be closed only when the piston moves to abut against the lower abutting surface.

Abstract: The present invention discloses a vehicle steering wheel, relating to the field of auto part technologies, and solving the problems of being prone to occurrent of traffic accidents and reducing traffic safety when the driver is driving in a fatigue state. In embodiments of the present disclosure, the vehicle steering wheel comprises a wheel rim, at least one oximeter is provided within handheld areas of the wheel rim and connected to a control device connected to an alarm device; and the control device is configured to judge whether or not a driver is in a fatigue driving state according to an oxyhemoglobin saturation value in the body of the driver detected by the oximeter, and to control the alarm device to operate if judging the driver is in the fatigue driving state. The present invention is mainly applied in vehicles.

Abstract: Embodiments of the present invention relate to a court marking switching system, including: singles and doubles markings, wherein the singles and doubles markings present white color when they are not lit up, and present a same color with surrounding floor when they are lit up; a switching element which lights up the singles markings and turns off the doubles markings when receiving a doubles command and lights up the doubles markings and turns off the singles markings when receiving a singles command. During the doubles match, only the singles markings are lit up, the lit singles markings present a same color with that of the surrounding floor and are not easy to be observed, while the doubles markings which are not lit up present a white color, such that only the white doubles markings may be observed by a user.

Abstract: An electronic certificate and a display method therefor are disclosed. The electronic certificate includes an electronic certificate body, a display screen and an IC. The display screen is disposed on the front side of the electronic certificate body and is used for displaying project information of the electronic certificate. When the display screen is in a locked state, the display screen does not display any project information. The IC is connected to the display screen and is used for controlling a display function of the display screen.

Abstract: Embodiments of the present invention relate to a court marking switching system, including: singles and doubles markings, wherein the singles and doubles markings present white color when they are not lit up, and present a same color with surrounding floor when they are lit up; a switching element which lights up the singles markings and turns off the doubles markings when receiving a doubles command and lights up the doubles markings and turns off the singles markings when receiving a singles command. During the doubles match, only the singles markings are lit up, the lit singles markings present a same color with that of the surrounding floor and are not easy to be observed, while the doubles markings which are not lit up present a white color, such that only the white doubles markings may be observed by a user.

Abstract: The present invention discloses a vehicle steering wheel, relating to the field of auto part technologies, and solving the problems of being prone to occurrent of traffic accidents and reducing traffic safety when the driver is driving in a fatigue state. In embodiments of the present disclosure, the vehicle steering wheel comprises a wheel rim, at least one oximeter is provided within handheld areas of the wheel rim and connected to a control device connected to an alarm device; and the control device is configured to judge whether or not a driver is in a fatigue driving state according to an oxyhemoglobin saturation value in the body of the driver detected by the oximeter, and to control the alarm device to operate if judging the driver is in the fatigue driving state. The present invention is mainly applied in vehicles.