Abstract: Disclosed is an ultra-short focus projecting optical system, which includes a display unit, a first lens group having a positive focus power, a second lens group having a positive focus power, a third lens group having a negative focus power, and an aspherical reflector arranged sequentially along a projection direction. The first lens group includes a first lens, a second lens and a diaphragm arranged sequentially along the projection direction. The first lens is a glass aspherical lens, the second lens is a glass spherical lens, and the first lens and the second lens are bent toward the diaphragm from their respective centers to their respective peripheries. The ultra-short focus projecting optical system and a projection device provided by this application can realize a large aperture and high resolution.

Abstract: Disclosed is an ultra-short focus projecting optical system, which includes a display unit, a first lens group having a positive focus power, a second lens group having a positive focus power, a third lens group having a negative focus power, and an aspherical reflector arranged sequentially along a projection direction. The first lens group includes a first lens, a second lens and a diaphragm arranged sequentially along the projection direction. The first lens is a glass aspherical lens, the second lens is a glass spherical lens, and the first lens and the second lens are bent toward the diaphragm from their respective centers to their respective peripheries. The ultra-short focus projecting optical system and a projection device provided by this application can realize a large aperture and high resolution.

Abstract: An optical system and a projection device are provided. The optical system includes a display unit, a first lens group, a second lens group, and a reflector in sequence along a transmission direction of light; both the first lens group and the second lens group have positive focal powers; the optical system satisfies the following relationship: 0.01?|?100|?0.02 and 0.005?|?200|?0.015; ?100 represents a focal power of the first lens group, and ?200 represents a focal power of the second lens group.

Abstract: Provided is a rhomboid structured triboelectric nanogenerator based on a built-in U-shaped support. The device includes a diamond-shaped bracket and two U-shaped supports. The U-shaped supports is connected with the diamond-shaped bracket through four connecting rods, and the supporting plates of U-shaped supports are sequentially adhered with metal conductor layer and a dielectric material layer, which forms the power generation unit. When the diamond-shaped bracket is closed, the dielectric material layers on the two supporting plates come into contact to produce friction charge; and then subjected to the reverse force after compression of the spring, the two dielectric material layers are separated, so as to generate an induction electric field by the friction charge and form a potential difference. Compared with an existing vibration energy harvester, the advantages will be small space occupation, a long service life, simple fabrication, and a high energy conversion rate.

Abstract: The present disclosure provides an electrostatic self-powered displacement grid sensor used for measuring the displacement of a component to be measured. The device structure includes a sliding chute and a sliding sheet, wherein the sliding chute is fixed to a fixed end, and the bottom of the inner side of the sliding chute is provided with a sensing array; the sliding sheet is fixedly connected with the component to be measured, and the lower end of the sliding plate is in contact with the bottom of the inner side of the sliding chute. When the sliding sheet slides over the sensing array; a corresponding electrical signal is produced, and the number of segments and the distance on sensing units on a single sensing array over which the sliding sheet slides can be obtained according to numbers and output current of sensing units in the sensing array indicated by the signal, and therefore the structural displacement is obtained.

Abstract: The present application provides an optical system and a projection device. The optical system includes a display unit, a first lens group, a second lens group and a reflector which are sequentially arranged along a light transmission direction. The first lens group has a positive focal power, the second lens group has a negative focal power, a total of focal powers of the second lens group and the reflector is positive. A distance from a side of the first lens group close to the display unit to another side of the second lens group far away from the display unit is T0, a distance from the side of the second lens group far away from the display unit to the reflector is T, and T0/T is greater than or equal to 0.8 and less than or equal to 1.1. The optical system provided by the present application is small in size and portable.

Abstract: An optical system and a projection device are provided. The optical system includes a display unit, a first lens group, a second lens group, and a reflector in sequence along a transmission direction of light; both the first lens group and the second lens group have positive focal powers; the optical system satisfies the following relationship: 0.01?|?100|?0.02 and 0.005?|?200|?0.015; ?100 represents a focal power of the first lens group, and ?200 represents a focal power of the second lens group.

Abstract: The present disclosure provides an electrostatic self-powered strain grid sensor configured to measure strain of a component to be measured. The sensor includes a slide groove and a slide sheet. The slide groove is fixed to a fixing end and a sensor array is arranged at an inside bottom of the slide groove. The slide sheet is fixedly connected with the component to be measured and a lower end part of the slide sheet is in contact with the inside bottom of the slide groove. An electric signal is output when the slide sheet sweeps over the sensor array. Based on the output current of a sensor unit of the sensor array indicated by the signal, the number of segments swept over by the slide sheet and a distance swept over the sensor units in a single sensor array by the slide sheet is obtained, thereby acquiring a structural strain.

Abstract: The present disclosure provides an electrostatic self-powered displacement grid sensor used for measuring the displacement of a component to be measured. The device structure includes a sliding chute and a sliding sheet, wherein the sliding chute is fixed to a fixed end, and the bottom of the inner side of the sliding chute is provided with a sensing array; the sliding sheet is fixedly connected with the component to be measured, and the lower end of the sliding plate is in contact with the bottom of the inner side of the sliding chute. When the sliding sheet slides over the sensing array; a corresponding electrical signal is produced, and the number of segments and the distance on sensing units on a single sensing array over which the sliding sheet slides can be obtained according to numbers and output current of sensing units in the sensing array indicated by the signal, and therefore the structural displacement is obtained.

Abstract: The present disclosure provides an electrostatic self-powered strain grid sensor configured to measure strain of a component to be measured. The electrostatic self-powered strain grid sensor includes a slide groove and a slide sheet. The slide groove is fixed to a fixing end and a sensor array is arranged at an inside bottom of the slide groove. The slide sheet is fixedly connected with the component to be measured and a lower end part of the slide sheet is in contact with the inside bottom of the slide groove. A corresponding electric signal is output when the slide sheet sweeps over the sensor array. Based on the number and magnitude of the output current of a sensor unit of the sensor array indicated by the signal, the number of segments swept over by the slide sheet and a distance swept over the sensor units in a single sensor array by the slide sheet is obtained, thereby acquiring a structural strain.

Abstract: Provided is a rhomboid structured triboelectric nanogenerator based on a built-in U-shaped support. The device includes a diamond-shaped bracket and two U-shaped supports. The U-shaped supports is connected with the diamond-shaped bracket through four connecting rods, and the supporting plates of U-shaped supports are sequentially adhered with metal conductor layer and a dielectric material layer, which forms the power generation unit. When the diamond-shaped bracket is closed, the dielectric material layers on the two supporting plates come into contact to produce friction charge; and then subjected to the reverse force after compression of the spring, the two dielectric material layers are separated, so as to generate an induction electric field by the friction charge and form a potential difference. Compared with an existing vibration energy harvester, the advantages will be small space occupation, a long service life, simple fabrication, and a high energy conversion rate.