1543results about How to "Miniaturization" patented technology

The invention relates to a shock absorber and a shock absorption system, and belongs to the technical field of precise shock absorption. The shock absorber comprises a base, a top plate, a piston and a supporting piece, a cavity is formed in the side, facing the top plate, of the base, the piston is connected with the base in the cavity in the mode that the piston can move in the depth direction of the cavity, the piston and the cavity are sealed to form a sealed cavity, the piston is connected with the top plate through the supporting piece, and therefore the pneumatic assembly with the vertical vibration reduction function is integrated in the vibration damper. The air cavity and the piston of the pneumatic assembly are both arranged at the bottom of the shock absorber, so that the air cavity and the piston are prevented from occupying the space between the base and the top plate in the shock absorber, and due to the fact that the area of the area, where the air cavity can be arranged, of the shock absorber base is larger, the shock absorber base can be more compact under the condition that the thickness of the base is not increased or slightly increased. The air cavity and the piston are arranged in the shock absorber base, so that the device integration density can be improved, the space can be compact, and miniaturization and multi-functionalization of the shock absorber are facilitated.

The invention relates to the technical field of electronic equipment, and discloses a piezoelectric heat dissipation device and a heat dissipation system.The piezoelectric heat dissipation device comprises a shell, a connecting assembly and a piezoelectric assembly, the piezoelectric assembly is arranged in the shell and connected with the shell through the connecting assembly, and the piezoelectric assembly comprises a first piezoelectric element, a vibrating diaphragm, a supporting frame and a jet plate which are sequentially connected in the first direction; a jet hole is formed in the jet plate, and an energy conversion cavity communicated with the jet hole is defined by the vibrating diaphragm, the supporting frame and the jet plate; the shell comprises a shell body and an air outlet cover plate, the shell body is provided with an opening facing the jet flow plate in the first direction, the air outlet cover plate covers the opening and is provided with an air outlet communicated with the jet flow hole, and the shell body is further provided with an air inlet communicated with the jet flow hole. The piezoelectric heat dissipation device is simple in structure and easy to miniaturize, and the structural arrangement of the heat dissipation system is beneficial to improving the heat dissipation effect of the piezoelectric heat dissipation device.

The invention provides a cam, a wave generator and a harmonic reducer, the cam comprises a cam body, grooves are formed in the circumferential side face of the cam body, and the grooves are continuously or intermittently distributed in the circumferential direction of the cam body; the length of the cam body in the axial direction is H, the width W of any groove in the axial direction of the cam body meets the condition that W / H is larger than or equal to 0.15 and smaller than or equal to 0.3, and after the cam is matched with the flexible bearing, buffer spaces capable of providing elastic deformation and absorbing vibration are formed in the grooves. According to the harmonic reducer, the cam with the groove and the width meeting the design range is designed and constructed in the peripheral side face, the balance weight of the cam is reduced, the contact area between the cam and the flexible bearing is reduced, in the operation process of the harmonic reducer, a buffer space for providing elastic deformation and absorbing vibration can be formed in the groove with a certain span in the axial direction, and the service life of the harmonic reducer is prolonged. Load distribution of the harmonic reducer in the operation process is more uniform, and high-speed, low-noise and small-vibration operation of the harmonic reducer is facilitated.

The present application provides an array-type image detection device, including two columns of imaging arrays arranged at intervals along a first direction, each column of the imaging array includes a plurality of imaging modules arranged at intervals along a second direction, each imaging module includes a magnifying lens and an imaging chip arranged in sequence along its optical axis; each imaging module magnifies the image to be detected located in its detection area and images it in its imaging area and is acquired by the imaging chip located in its imaging area; and except for the detection areas located at the head and tail sides of the second direction, each detection area has overlapping parts with other detection areas at both ends along the second direction. The array-type image detection device provided by the present application can effectively solve the problems of low resolution of existing contact image sensors, difficulty in detecting high-resolution images, and detection blind spots when performing magnified detection, and can obtain a clear magnified image of the image to be detected within the full-frame range.

The invention relates to a double-pump light semi-transparent and semi-reflective miniaturized triaxial SERF atom magnetometer device, which is characterized in that single pump light is guided into a probe by a polarization maintaining optical fiber; and then one beam of pump light is divided into two beams of circular polarization pump light with the same light intensity by using a half-wave plate, a polarization splitting prism, a right-angle reflector and a quarter-wave plate, and then the two beams of circular polarization pump light vertically pass through the same alkali metal gas chamber. After the pump light penetrating through the air chamber passes through the semi-transparent and semi-reflective flat beam splitter, one half of the pump light is detected by the photoelectric detector and used for extracting magnetic field information, and the other half of the pump light returns to the original path and passes through the alkali metal air chamber for the second time. According to the invention, high-sensitivity simultaneous measurement of a three-axis magnetic field of the miniaturized three-axis SERF atom magnetometer is realized, the atomic spin polarizability is enhanced, the uniformity of the atomic spin polarizability in the air chamber is improved, and the technical problem of spin polarizability uniformity in miniaturized application of the SERF atom magnetometer is solved; and the application of the array type triaxial SERF atom magnetometer in the fields of magnetocardiography, brain magnetism and the like is facilitated.

The utility model discloses a battery cover plate assembly, a battery shell and a battery. The battery cover plate assembly comprises a cover plate body. The cover plate body is a metal piece, the cover plate body is provided with a thinned area and a non-thinned area, the thickness of the thinned area is smaller than that of the non-thinned area, the non-thinned area comprises a first non-thinned area, and the first non-thinned area surrounds the peripheral side of the thinned area and is suitable for being connected with a shell of the battery shell. According to the battery cover plate assembly disclosed by the embodiment of the utility model, the thinning area is arranged and the thickness of the thinning area is smaller than that of the non-thinning area, so that the overall weight of the cover plate body can be reduced, and the light weight of the battery cover plate assembly is facilitated; therefore, the capacity ratio of unit weight of the battery can be improved, and the loading capacity of the battery under the same weight can be improved; moreover, the first non-thinned area surrounds the peripheral side of the thinned area and is suitable for being connected with the shell of the battery shell, and the thickness of the first non-thinned area is relatively large, so that the connection strength of the cover plate body and the shell can be ensured.

The utility model discloses a chip medicine cake box mechanism of a traditional Chinese medicine external treatment device, each of an upper box body and a lower box body comprises a box body bottom plate provided with a through hole, and the outer edge of each box body bottom plate is provided with a box body flange folded inwards. A bottom plate of the box body is provided with a cylindrical isolation plate; the cylindrical isolation plate is positioned on the outer side of the through hole; and an annular pressing plate is arranged between the cylindrical isolation plate and the outer edge of the through hole. The turnup edges of the upper box body and the lower box body are mutually clamped, the cylindrical upper isolation plate and the cylindrical lower isolation plate are mutually buckled and contacted, and a closed space is formed in the chip medicine cake box mechanism. A storage chip and a radio frequency coil are installed in the closed space. Moxibustion fumigation medicine cakes are installed between the annular upper pressing plate and the annular lower pressing plate. The moxibustion fumigation medicine cake, the storage chip and the radio frequency coil are respectively located in independent spaces, so that damage of thermal radiation of the moxibustion fumigation medicine cake to the storage chip and the radio frequency coil is avoided, and the service life of the storage chip and the service life of the radio frequency coil are prolonged. And the structure is compact, and the connection among the parts is more reliable.

The invention relates to a vehicle power supply system, a control method of the vehicle power supply system and a vehicle. In the vehicle power supply system, a first DCDC conversion module is electrically connected with a power battery system through a first switch unit; the second DCDC conversion module is electrically connected with the power battery system; the first switch unit is a normally closed switch; the first DCDC conversion module is also electrically connected with the second switch unit; the rated power of the first DCDC conversion module is smaller than that of the second DCDC conversion module; the first DCDC conversion module and the second DCDC conversion module are both used for converting high voltage provided by the power battery system into low voltage. The first DCDC conversion module provided by the embodiment of the invention is relatively small in structure and relatively low in cost, and the first DCDC conversion module is arranged in the whole vehicle, so that the weight and the cost of the vehicle can be reduced, and miniaturization of the vehicle is facilitated.

The utility model relates to the technical field of wafer processing, in particular to a wafer carrying mechanism and wafer thinning equipment, the wafer carrying mechanism comprises a base, a clamping assembly and an adsorption assembly, the clamping assembly is arranged on the base, at least two power output ends of the clamping assembly can be close to each other to clamp a wafer, and the adsorption assembly is arranged on the base. Or can be far away from each other to release the wafer; the adsorption end of the adsorption assembly can adsorb a wafer, and in the vertical direction, the adsorption end of the adsorption assembly and the power output end of the clamping assembly are located on the two sides of the base respectively. By means of the arrangement, the wafer carrying mechanism has the clamping function and the adsorption function at the same time, the occupied space is small, the wafer carrying mechanism can be conveniently installed in wafer thinning equipment which is more compact in structural layout, and miniaturization of the wafer thinning equipment can be achieved easily.

The invention provides an electric connector, a circuit board assembly and electronic equipment. The electric connector comprises an insulating shell and a terminal, the terminal is fixedly connected to the insulating shell, a plug-in space is arranged in the insulating shell, an opening is formed in the bottom surface of the insulating shell, the plug-in space is communicated with the outside of the insulating shell through the opening, and the bottom surface of the insulating shell faces the circuit board. At least part of the first electric connection end of the terminal is located in the insertion space and used for being electrically connected with the signal transmission structure, the second electric connection end of the terminal extends out of the bottom face of the insulation shell and used for being electrically connected with a circuit board, and when the electric connector is used for being electrically connected with the signal transmission structure, the signal transmission structure enters the insertion space through the opening; and a first electrical connection end of the connection terminal. Therefore, one side of the bottom surface of the electric connector is electrically connected with the signal transmission structure and the circuit board, and the signal transmission structure is fixed through the cooperation of the circuit board and the peripheral structure, so that a pressing structure is omitted, and the electric connector is effectively reduced.

One ECR ion source generates a He < 2 + > ion beam, the other ECR ion source generates a H2 < + > ion beam, the He < 2 + > or H2 < + > ion beam is selected by a deflection magnet and then transmitted and focused by LEBT to enter an RFQ, the focusing factor of the RFQ is increased and then reduced, DTL is IH-DTL designed by adopting KONUS beam dynamics and comprises two KONUS periods, the working frequencies of the RFQ and the DTL are respectively 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, 425MHz, after He < 2 + > or H2 < + > ion beams are accelerated by RFQ and DTL, the MEBT distributes and transmits the ion beams to a downstream accelerator and an isotope production device. According to the proton helium ion implanter provided by the invention, the particle beam can meet the injection requirement of a subsequent synchrotron, the miniaturization of the proton helium ion implanter is realized, and the production of medical isotopes is considered.

The invention relates to the field of aero-engines, in particular to a fan stationary blade retaining structure of an open rotor engine. The fan stationary blade retaining structure is positioned between the fan blade handle and the stationary blade hub and comprises a magnetic suspension spherical joint; the magnetic suspension spherical joint comprises a spherical joint inner shell, a spherical joint outer shell, a limiting structure and an electromagnetic force adjusting device. The tail end of a blade handle of the fan stationary blade is fixedly connected with a spherical joint inner shell of the magnetic suspension spherical joint, and a spherical joint outer shell is installed in a corresponding installation cavity in the stationary blade hub and then fixed to the intermediate case. The limiting structure is arranged between the spherical joint inner shell and the spherical joint outer shell along the axis of the blade handle, and a local mechanical weak part is arranged on the limiting structure. The limiting structure between the spherical joint inner shell and the spherical joint outer shell can decouple the fan stationary blade and the intermediate case, impact and vibration loads transmitted to the intermediate case are reduced, and it is guaranteed that the intermediate case still has enough structural safety after being subjected to large impact loads.

The utility model provides an optical machine illumination system and laser projection equipment, and relates to the technical field of laser display. According to the optical machine illumination system, the first face of the first prism is arranged to be the curved face, the first face is used for collecting the illumination light beam and adjusting the incident angle of the illumination light beam entering the second face to replace a lens, materials and space of the lens are saved, and the system size and the number of optical elements can be effectively reduced; and miniaturization of the equipment is facilitated. Meanwhile, by adding the second prism, the propagation path of the light beam is prolonged, so that the projection light beam and the non-projection light beam can be separated, and the contrast ratio is improved.

The invention relates to a miniaturized closed-loop FID scalar atom magnetometer and an implementation method thereof, and belongs to the field of atom magnetic measurement. According to the method, the closed-loop working mode of the FID magnetometer is realized by utilizing a self-made electronics system, the modulation frequency of pumping light is corrected in real time, so that the magnetometer still keeps high sensitivity under a large magnetic field change rate, and the performance restriction between the dynamic range and the sensitivity of an open-loop FID magnetometer is broken through. The interaction between the self-made frequency meter and the time sequence control system is the core component of the closed loop of the magnetometer system. The device can measure a magnetic field with a large change rate at a high speed, is high in sensitivity and accuracy, and plays an important role in field magnetic measurement application.

The invention relates to the technical field of semiconductor photoelectronics and liquid crystal materials, in particular to a vortex light laser and a preparation method thereof. The supporting structure is arranged on the laser light source; the liquid crystal structure is arranged on the supporting structure, and the liquid crystal structure is configured to convert linearly polarized light from the laser light source into circularly polarized light and further convert the circularly polarized light into vortex light. In addition, the cholesteric liquid crystal in the liquid crystal structure can change the rotation direction of the circularly polarized light under the irradiation of the ultraviolet light source, so that the topological charge number of the vortex light can be regulated and controlled. Compared with a traditional vortex light laser, the vortex light laser has the advantages of being high in conversion efficiency, low in preparation cost, high in preparation speed, capable of tuning vortex light of orbital angular momentum, capable of conducting autonomous regulation and control on emergent light under the condition that an external electric field is not introduced, and capable of improving the utilization rate of the vortex light. The preparation process is compatible with the traditional semiconductor process, the size is small, and the integration level is high.

The invention relates to a semiconductor device and a preparation method thereof. The semiconductor device comprises a semiconductor material layer; the first groove is located in the semiconductor material layer, the side wall and the bottom wall of the first groove are connected through an arc angle, and the included angle between the plane where the side wall is located and the plane where the bottom wall is located is an obtuse angle; the drain region is located in the semiconductor material layer on the periphery of the first groove, and the depth of the drain region is smaller than that of the first groove; the well region is located in the semiconductor material layer below the bottom wall; the field oxide layer extends on the part, between the well region and the drain region, of the bottom wall and the side wall; the gate dielectric layer is connected with the field oxide layer and covers part of the well region; the field plate is located on the field oxide layer; the grid electrode is located on the grid electrode dielectric layer; the source region is positioned on the surface layer of the well region; a current conduction path of the semiconductor device comprises a first current conduction path which is located in the semiconductor material layer and extends close to the bottom wall and a second current conduction path which extends close to the side wall. Therefore, the on-resistance of the device is reduced, and the voltage-resistant performance of the device is ensured at the same time.

The invention discloses a spring-free magnetic springback type switch key, which comprises a shell, a shaft rod inserted into the shell, a magnetic column arranged in the shaft rod, an electromagnetic coil positioned in the shell and arranged outside the shaft rod in a surrounding manner, and a trigger assembly mounted in the shell and matched with the shaft rod, the shaft rod is provided with a hollow column body extending downwards, and the magnetic column is located in the hollow column body; an annular wall is arranged on the inner bottom face of the shell in an upward protruding mode, a guide groove matched with the hollow column in the shaft rod is formed, and the guide groove is used for conducting linear guiding on relative matching of the hollow column. And the electromagnetic coil is sleeved outside the ring wall. According to the switch key, the electromagnet is matched with the magnet, rebounding of the key is achieved through magnetic force, and the intensity of feedback force is flexibly changed by adjusting the magnetic force of the electromagnet.

The utility model provides a lens focusing assembly, a camera module and electronic equipment. The lens focusing assembly comprises a first lens mounting seat, a shell and a displacement detection device. The displacement detection device adopts a magnetic sensor and three magnetic pieces (detection magnetic assemblies) to carry out position detection. Wherein the polarities of the magnetic poles on the two sides of each of the first magnetic piece and the third magnetic piece in the second direction are opposite, and the polarities of the magnetic poles on the two sides of the second magnetic piece in the first direction are opposite. And the polarity of the second magnetic piece close to the first magnetic piece and the third magnetic piece is the same as the magnetic pole polarity of the sides, facing the shell, of the first magnetic piece and the third magnetic piece. When the magnetic sensor fixedly arranged on the shell translates relative to the detection magnetic assembly fixedly arranged on the first lens mounting seat, the position of the corresponding magnetic field intensity peak value is farther away from the second magnetic piece, so that the effective detection stroke of the displacement detection device is effectively increased, and the cost is reduced.

The relay comprises a ceramic cover, an auxiliary static contact fixedly arranged on the ceramic cover, a coil assembly arranged below the ceramic cover and a PCB used for controlling the coil assembly to work, and the coil assembly is provided with a winding terminal; the relay further comprises an auxiliary leading-out terminal correspondingly connected with the auxiliary static contact, a coil leading-out terminal electrically connected with the winding terminal through the PCB and an insulating part used for fixedly holding the auxiliary leading-out terminal and the coil leading-out terminal, and the insulating part is integrally formed through injection molding. According to the relay, the insulating part used for fixedly holding the auxiliary leading-out terminal and the coil leading-out terminal is integrally formed through injection molding, so that forming and assembling are facilitated, the manufacturing procedures are reduced, the manufacturing efficiency is improved, the manufacturing cost is reduced, the structural strength is enhanced, and the relay is more compact in structure and smaller in size.

The invention provides an optical lens and electronic equipment with the same. According to the optical lens, a first lens has negative focal power, the first side face of the first lens is a convex face, and the second side face of the first lens is a concave face; the first side surface of the second lens is a concave surface, and the second side surface of the second lens is a convex surface; the third lens has positive focal power, the first side surface of the third lens is a convex surface, and the second side surface of the third lens is a convex surface; the fourth lens has positive focal power, and the second side surface of the fourth lens is a convex surface; the fifth lens has focal power; the first side surface of the sixth lens and the second side surface of the sixth lens have the same surface type; the seventh lens has focal power, and the second side face of the seventh lens is a convex face. The optical lens solves at least one of the problems that an optical lens in the prior art cannot give consideration to miniaturization and high resolution, is poor in pixel, is poor in imaging quality in a dark environment, and cannot be matched with a higher-pixel chip due to poor central angle resolution while meeting a large field angle.

The utility model discloses a double-frequency filter based on an SIW and an HMSIW. The double-frequency filter comprises a dielectric substrate, an upper metal layer, a lower metal layer, a metal through hole array penetrating through the upper metal layer and the lower metal layer, a 50-ohm feed port and a conical conversion feed structure. An SIW structure is arranged on the upper surface of the substrate, H-shaped complementary split-ring resonators which are symmetrically arranged are arranged on a metal layer on the upper surface of the substrate, so that the dual-frequency filter with metamaterial characteristics is realized, and an HMSIW-based miniaturized dual-frequency filter is realized by cutting an SIW equivalent magnetic wall. Compared with the existing metal waveguide, LTCC (Low Temperature Co-Fired Ceramic) process and the like, the processing difficulty is reduced, and the requirements of easy processing, miniaturization and high performance of modern wireless communication are met.

The utility model provides a scanning module and a scanning laser radar, and relates to the technical field of laser radars. The scanning module comprises a refracting optical element, the refracting optical element has a preset incident direction and a preset refracting direction, the refracting optical element comprises a plane mirror, the plane mirror has an emergent surface, the emergent surface is provided with a metasurface, and a refracting layer is formed on the metasurface; or, a microprism array is distributed on the emergent surface, and the microprism array is limited to form a refraction layer; wherein the refraction layer is used for refracting a light beam incident along a preset incident direction, so that the light beam is emitted along a preset refraction direction. According to the invention, by improving the scanning module of the laser radar, the stability of the scanning module can be improved, and a large pitching field angle can be scanned.

The invention relates to a Ka-band dual-frequency dual-polarization common-caliber millimeter wave antenna system which comprises an antenna unit. The antenna unit comprises a metal floor, a first dielectric layer, a second dielectric layer, a third dielectric layer, a first radiation unit, a first feed patch, a fourth dielectric layer, a fifth dielectric layer, a second radiation unit and a second feed patch which are sequentially stacked from bottom to top, and the first radiation unit and the first feed patch are located on the same layer. The second radiation unit and the second feed patch are located on the same layer; the first feed patch and the second feed patch are different in shape and size. According to the Ka-band dual-frequency dual-polarization common-caliber millimeter wave antenna system, the antennas working in different frequency bands are highly concentrated in a physical space, the problem of serious mutual coupling between the antennas in a compact space is solved, antenna miniaturization is achieved, meanwhile, signal loss is reduced, and therefore the applicability of the antennas is improved.

The invention relates to the field of communication, and discloses an antenna unit, an AIP module and a phased-array antenna, the antenna unit comprises metal layers and low-temperature co-fired ceramic layers which are sequentially and alternately stacked from bottom to top, and the antenna unit is prepared according to the following process: ceramic powder is processed into a green tape through a tape casting technology; sequentially laminating the green ceramic tape and the metal layer to form a laminated structure; the uppermost layer of the stacked structure is a metal layer, and the metal layer comprises an antenna radiation layer, a coupling feed layer and a reference ground layer; applying pressure to the laminated structure and heating the laminated structure to form a green ceramic chip structure; heating the green ceramic chip structure to remove colloid in the green ceramic tape; and co-firing the green ceramic chip structure, and changing the green ceramic tape into a low-temperature co-fired ceramic layer to obtain the antenna unit. The low-temperature co-fired ceramic technology can provide a dielectric material with lower loss and a reliable multi-layer process, and is easier to integrate and miniaturize. Compared with a PCB, the manufacturing process of the antenna unit is simpler, the processing cost can be reduced, and the yield of the antenna unit is improved.

The embodiment of the invention provides an automobile air conditioner heat exchange assembly, an automobile air conditioning box and an automobile air conditioning system, and relates to the field of vehicle-mounted air conditioners, and the automobile air conditioner heat exchange assembly comprises a heat exchange core body, a refrigeration connector and a heating connector. And the heat exchange core body is provided with a heat exchange channel for a refrigerant to flow. The refrigerating connector and the heating connector are both connected with the heat exchange core body and communicate with the heat exchange channel, and one of the refrigerating connector and the heating connector is selectively used in cooperation with the heat exchange core body. The heat exchange core body of the automobile air conditioner heat exchange assembly integrates the functions of the evaporator and the condenser, and is simple in structure, small in size, beneficial to miniaturization and light weight design, few in parts needed for installation and low in assembly cost.

The utility model provides a light and small laser wind-finding radar device for an aerostat platform, and the device comprises a laser light source which is used for generating a pulse light beam with preset energy and preset frequency; the transmitting-receiving optical system comprises a step-shaped wedge mirror or a holographic optical element, is arranged on an emergent path of the pulse light beam and is used for transmitting the pulse light beam according to a forward conical scanning mode and receiving an echo signal of the pulse light beam; and the laser detector is arranged on an incident path after the echo signal passes through the transceiving optical system, and is used for detecting the echo signal to obtain the frequency shift of the echo signal.

The invention belongs to the technical field of sensors, and particularly relates to a passive NFC aircraft tire temperature and pressure composite sensor system which comprises a filler neck, a rear cover, a pressure core, a conversion circuit board, a conditioning circuit board assembly and a tag antenna assembly. The filler neck is a two-stage step column; the small-diameter end of the filler neck is provided with an air inlet, and the large-diameter end is provided with a cavity; the pressure core body is arranged in the air inlet hole; the pressure core body is connected with the conversion circuit board; the conversion circuit board is connected with the conditioning circuit board assembly; the conditioning circuit board assembly is fixed on the step surface of the cavity at the large-diameter end of the filler neck through a supporting screw; the tag antenna assembly is installed on the supporting screws through the fixing screws. The rear cover is screwed at the large-diameter end of the filler neck; the small-diameter end of the filler neck is connected with a tire through external threads.

The invention provides a control system, method and device for a modular unmanned agricultural machine, and is applied to the technical field of agricultural robots. The system comprises a host module and a plurality of extension modules, the plurality of extension modules comprise an inspection extension and a plurality of operation extensions; the host module is connected with at least one of the plurality of extension modules; each extension module comprises a functional domain controller and an operation sub-module; and one operation extension corresponds to at least one field operation.

The invention provides a projection system and optical display equipment. The projection system comprises a projection lens, a color combination prism and an image source, the projection lens comprises a first lens, a second lens, a third lens and a fourth lens, and the curvature of the lenses and the focal length of the projection lens meet the following conditions:-0.1 < (K1 + K2) / f < 0.1, 0.2 < (K3 + K4) / f < 0.35,-0.1 < (K5 + K6) / f < 0 and-0.3 < (K7 + K8) / f <-0.1; k1 and K2 are respectively the curvature of the surface, far away from the image source, of the first lens and the curvature of the surface, close to the image source, of the first lens; k3 and K4 are respectively the curvature of the surface, far away from the image source, of the second lens and the curvature of the surface, close to the image source, of the second lens; k5 and K6 are respectively the curvature of the surface, far away from the image source, of the third lens and the curvature of the surface, close to the image source, of the third lens; k7 and K8 are the curvature of the surface, far away from the image source, of the fourth lens and the curvature of the surface, close to the image source, of the fourth lens respectively; f is the focal length of the projection lens.

The invention discloses a high-voltage direct-current relay which comprises a pair of static contact leading-out ends, a push rod assembly, a plurality of movable spring assemblies, a magnetic conductive assembly and an elastic assembly. Each movable spring assembly comprises a movable contact spring, the movable contact springs are arranged side by side, and the two ends of each movable contact spring in the first direction are used for making contact with or being separated from the corresponding pair of static contact leading-out ends respectively; wherein the first direction is the arrangement direction of the pair of static contact leading-out ends; the magnetic conductive assembly is arranged on one side, facing the static contact leading-out end, of the plurality of movable reeds and is used for resisting electric repulsive force between the contacts; the elastic assembly is connected to the plurality of movable spring assemblies and the push rod assembly, and the elastic assembly is used for providing contact pressure.