Focusing group anti-backlash mechanism based on continuous zooming infrared optical system

Abstract

The invention discloses a high and low temperature focusing cam cylinder clearance eliminating mechanism based on an infrared optical system, and relates to the infrared optical system. The focusing device comprises a focusing support, a guide rail, a sliding block, a focusing lens assembly, an anti-backlash assembly and a focusing motor assembly. The focusing support is of a frame structure with an opening in the top, the two sets of sliding blocks are installed on the tops of the two sides of the focusing support respectively, and the anti-backlash assembly is installed at the bottom of the focusing support. The bottom of the focusing lens assembly is installed on the anti-backlash assembly, the two guide rail sets are installed at the two ends of the focusing lens assembly respectively, and the guide rails slide in the sliding blocks. The focusing motor assembly is connected with the anti-backlash assembly; according to the invention, the motion mode of sliding of the double-guide-rail sliding block is adopted, so that eccentricity and inclination of the lens frame caused by uneven stress of the focusing lens assembly in the torque transmission process of the focusing motor can be effectively avoided; the structure of the two nuts and the spring is arranged on the lead screw, so that gaps between the nuts and the transmission lead screw can be effectively eliminated, constant force can be ensured in the whole focusing stroke, and the control precision of the focusing motor is effectively improved.

Description

Technical Field

[0001] This invention relates to infrared optical systems, and more particularly to a dual-rail mounting configuration that makes the focusing lens assembly more stable and reliable during axial movement. The gap elimination mechanism for the focusing lens assembly based on a continuous zoom infrared optical system eliminates the gap during focusing by using a gap elimination component with constant elasticity. Background Technology

[0002] In the military and civilian markets, traditional single-field-of-view, dual-field-of-view, and triple-field-of-view infrared thermal imagers are no longer sufficient to meet growing market demand, leading to the increasingly widespread application of continuous zoom thermal imagers. Continuous zoom thermal imagers require lenses with axially movable zoom and focusing lens groups to achieve continuous zoom functionality. The zoom lens group is used to change the focal length, while the focusing lens group is used to compensate for focal length changes in different scenes and temperatures, ensuring the thermal imager outputs clear images under various conditions. In practical applications, it has been found that the relative position of the focusing lens frame significantly impacts the imaging effect. Traditional thermal imagers typically install a backlash-eliminating spring between the end face of a lead screw and a shaped nut. Rotation of the lead screw compresses the spring to eliminate the gap between the lead screw and the nut. The spring force is affected by the elastic coefficient and the spring deformation. The varying compression length of the spring by the focusing lens group at different positions results in inconsistent spring force on the focusing lens assembly. This significantly increases the control difficulty of the focusing motor and fails to completely eliminate hysteresis in the focusing lens assembly.

[0003] Traditional continuous zoom thermal imagers typically use a single-rail slider as the axial sliding mechanism for the focusing component. This structure is a single cantilever structure, which can lead to uneven force distribution during transmission. The lens frame may tilt and deform, resulting in image blurring, trailing, and other phenomena. Summary of the Invention

[0004] The present invention addresses the problem that the focusing assembly of existing continuous zoom thermal imagers suffers from uneven stress, which can lead to tilting and deformation of the lens frame, resulting in image blurring and trailing. It provides a dual-rail mounting method that makes the focusing lens assembly more stable and reliable during axial movement. The invention utilizes a gap-eliminating component with constant elasticity to eliminate gaps in the focusing lens assembly during focusing, based on a continuous zoom infrared optical system focusing group gap-eliminating mechanism.

[0005] The present invention relates to a backlash elimination mechanism for a focusing group in a continuous zoom infrared optical system, characterized in that the backlash elimination mechanism includes a focusing bracket, guide rails, sliders, a focusing lens assembly, a backlash elimination assembly, and a focusing motor assembly; the focusing bracket is a frame structure with an open top, two sets of sliders are respectively installed on the top of both sides of the focusing bracket, and the backlash elimination assembly is installed at the bottom of the focusing bracket; the bottom of the focusing lens assembly is installed on the backlash elimination assembly, and two sets of guide rails are respectively installed at both ends of the focusing lens assembly, the guide rails sliding within the sliders; the focusing motor assembly is connected to the backlash elimination assembly; wherein: The inner wall of the slider is provided with a slide groove, and the guide rail is embedded in the slide groove and slides along the slide groove; The focusing lens assembly includes a focusing lens mount, a focusing lens frame, and a focusing lens element. The focusing lens mount is T-shaped and is vertically mounted on the backlash elimination assembly. The focusing lens frame is fixed to the middle of the focusing lens mount with screws, and the focusing lens element is mounted on top with a pressure ring. Two sets of guide rails are respectively mounted on both ends of the focusing lens mount with screws. The backlash elimination assembly includes a lead screw, backlash elimination nut I, backlash elimination nut II, and backlash elimination spring. Backlash elimination nut I is installed at the rear end of the lead screw, backlash elimination nut II is installed at the front end of the lead screw, and backlash elimination spring is fitted in the middle section of the lead screw and located between backlash elimination nut I and backlash elimination nut II. Both backlash elimination nut I and backlash elimination nut II are barrel-shaped. The large end of backlash elimination nut I is flange-shaped and connects to the bottom of the focusing lens mount, while the small end has two protruding rectangular serrations. The large end of backlash elimination nut II is used to fix the backlash elimination spring, and the small end has two rectangular notches. The serrations of backlash elimination nut I and the notches of backlash elimination nut II cooperate with each other to compress the backlash elimination spring. The backlash elimination spring generates a constant spring force between backlash elimination nut I and backlash elimination nut II to eliminate the backlash between the nut and the lead screw. The focusing motor assembly includes a motor bracket, a focusing motor, a coupling, bearings, and a bearing cover. The rear of the motor bracket is cylindrical, with two side wings connected to the focusing bracket. The focusing motor is mounted on the motor bracket, and the bearings are mounted on the power output shaft of the focusing motor. The power output shaft of the focusing motor is connected to a lead screw via a coupling, driving the lead screw to rotate. The bearing cover is mounted on the front end of the motor bracket, and the power output shaft of the focusing motor passes through the bearing cover and is then installed in the bearing.

[0006] The backlash elimination mechanism of the focusing group in the continuous zoom infrared optical system of this invention adopts a dual-rail slider sliding motion mode, which can effectively avoid uneven force on the focusing lens assembly during the torque transmission of the focusing motor, which would cause the lens frame to be eccentric or tilted, resulting in trailing and blurring of the thermal image output. The structure of two nuts and springs on the lead screw does not change the relative position of the two nuts on the lead screw, and the elastic force of the backlash elimination spring does not change. This can effectively eliminate the gap between the nuts and the transmission lead screw, and also ensure that the force is constant throughout the entire focusing stroke, thus improving the control accuracy of the focusing motor. Attached Figure Description

[0007] Figure 1This is a schematic diagram of the structure of the present invention.

[0008] Figure 2 This is a schematic diagram of the focusing lens assembly structure of the present invention.

[0009] Figure 3 This is a schematic diagram of the gap-eliminating component structure of the present invention.

[0010] Figure 4 This is a schematic diagram of the connection structure of the gap-eliminating component of the present invention.

[0011] Figure 5 This is a schematic diagram of the pin gap lead screw structure of the present invention.

[0012] Figure 6 This is a schematic diagram of the gap-eliminating nut I of the present invention.

[0013] Figure 7 This is a schematic diagram of the gap-eliminating nut II structure of the present invention.

[0014] The components include: 1. Focusing bracket; 2. Guide rail; 3. Slider; 4. Focusing lens mount; 5. Focusing lens frame; 6. Focusing lens; 7. Lead screw; 8. Backlash-eliminating nut I; 9. Backlash-eliminating nut II; 10. Backlash-eliminating spring; 11. Sawtooth; 12. Notch; 13. Motor bracket; 14. Focusing motor; 15. Coupling; 16. Bearing; and 17. Bearing cover. Detailed Implementation

[0015] Example 1: A backlash elimination mechanism for a focusing group in a continuous zoom infrared optical system includes a focusing bracket, guide rails, sliders, a focusing lens assembly, a backlash elimination assembly, and a focusing motor assembly. The focusing bracket is a frame structure with an open top. Two sets of sliders are respectively installed on the top of both sides of the focusing bracket, and the backlash elimination assembly is installed at the bottom of the focusing bracket. The bottom of the focusing lens assembly is mounted on the backlash elimination assembly. Two sets of guide rails are respectively installed at both ends of the focusing lens assembly, and the guide rails slide within the sliders. The focusing motor assembly is connected to the backlash elimination assembly. Wherein: The inner wall of the slider is provided with a slide groove, and the guide rail is embedded in the slide groove and slides along the slide groove; The focusing lens assembly includes a focusing lens mount, a focusing lens frame, and a focusing lens element. The focusing lens mount is T-shaped and is vertically mounted on the backlash elimination assembly. The focusing lens frame is fixed to the middle of the focusing lens mount with screws, and the focusing lens element is mounted on top with a pressure ring. Two sets of guide rails are respectively mounted on both ends of the focusing lens mount with screws. The backlash elimination assembly includes a lead screw, backlash elimination nut I, backlash elimination nut II, and backlash elimination spring. Backlash elimination nut I is installed at the rear end of the lead screw, backlash elimination nut II is installed at the front end of the lead screw, and backlash elimination spring is fitted in the middle section of the lead screw and located between backlash elimination nut I and backlash elimination nut II. Both backlash elimination nut I and backlash elimination nut II are barrel-shaped. The large end of backlash elimination nut I is flange-shaped and connects to the bottom of the focusing lens mount, while the small end has two protruding rectangular serrations. The large end of backlash elimination nut II is used to fix the backlash elimination spring, and the small end has two rectangular notches. The serrations of backlash elimination nut I and the notches of backlash elimination nut II cooperate with each other to compress the backlash elimination spring. The backlash elimination spring generates a constant spring force between backlash elimination nut I and backlash elimination nut II to eliminate the backlash between the nut and the lead screw. The focusing motor assembly includes a motor bracket, a focusing motor, a coupling, bearings, and a bearing cover. The rear of the motor bracket is cylindrical, with two side wings connected to the focusing bracket. The focusing motor is mounted on the motor bracket, and the bearings are mounted on the power output shaft of the focusing motor. The power output shaft of the focusing motor is connected to a lead screw via a coupling, driving the lead screw to rotate. The bearing cover is mounted on the front end of the motor bracket, and the power output shaft of the focusing motor passes through the bearing cover and is then installed in the bearing.

[0016] When this device is in use, the focusing motor drives the lead screw to rotate through the coupling. During the rotation of the lead screw, the backlash-eliminating nut I installed on it moves back and forth, which drives the focusing lens mount to move to perform the focusing operation. During the focusing process, the backlash-eliminating nut I and the backlash-eliminating nut II maintain relative displacement. Under the constant spring force of the backlash-eliminating spring, the gap between the nut and the lead screw is eliminated.

[0017] The focusing motor is a traditional motor. In order to highlight the structure of the backlash elimination component more clearly, only a part of the focusing motor is added, and the complete structure is not shown.

Claims

1. A gap elimination mechanism for focusing group of continuous zoom infrared optical system, characterized in that the gap elimination mechanism comprises a focusing support, a guide rail, a slider, a focusing lens assembly, a gap elimination assembly and a focusing motor assembly; the focusing support is a frame structure with an open top, two sets of sliders are respectively installed on the top of both sides of the focusing support, and the gap elimination assembly is installed on the bottom of the focusing support; the focusing lens assembly is installed on the gap elimination assembly at the bottom, two sets of guide rails are respectively installed on both ends of the focusing lens assembly, and the guide rails slide in the sliders; the focusing motor assembly is connected with the gap elimination assembly; wherein: a sliding groove is arranged on the inner wall of the slider, and the guide rail is embedded in the sliding groove and slides along the sliding groove; the focusing lens assembly comprises a focusing lens seat, a focusing lens frame and focusing lens, the focusing lens seat is in T shape and is installed vertically on the gap elimination assembly, the focusing lens frame is fixed in the middle of the focusing lens seat through screws, and the focusing lens is installed on the focusing lens frame through a compression ring; the two sets of guide rails are respectively installed on both ends of the focusing lens seat through screws; the gap elimination assembly comprises a lead screw, a gap elimination nut I, a gap elimination nut II and a gap elimination spring, the gap elimination nut I is installed at the rear end of the lead screw, the gap elimination nut II is installed at the front end of the lead screw, and the gap elimination spring is sleeved on the middle segment of the lead screw and located between the gap elimination nut I and the gap elimination nut II; the gap elimination nut I and the gap elimination nut II are both barrel-shaped, the large end of the gap elimination nut I is in the form of a flange and connected with the bottom of the focusing lens seat, and the small end has two protruding rectangular sawteeth; the large end of the gap elimination nut II is used for fixing the gap elimination spring, and the small end has two rectangular notches; the sawteeth of the gap elimination nut I and the notches of the gap elimination nut II cooperate with each other to compress the gap elimination spring, and the gap elimination spring generates a constant spring force between the gap elimination nut I and the gap elimination nut II to eliminate the gap between the nut and the lead screw; the focusing motor assembly comprises a motor support, a focusing motor, a coupling, a bearing and a bearing cover, the tail of the motor support is cylindrical, the two side wings are connected with the focusing support, the focusing motor is installed on the motor support, the bearing is installed on the power output shaft of the focusing motor, the power output shaft of the focusing motor is connected with the lead screw through the coupling to drive the rotation of the lead screw, and the bearing cover is installed at the front end of the motor support, and the power output shaft of the focusing motor passes through the bearing cover and is installed in the bearing. ​ ​ ​ ​

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