A focusing structure for a continuous zoom lens of an infrared system

Abstract

The utility model discloses a focusing structure of a continuous zoom lens of an infrared system, belonging to the technical field of infrared system imaging, comprising a focusing drive component and a focusing lens group component, wherein the focusing drive component comprises a focusing motor seat, a focusing worm, a focusing motor, an eccentric wheel, a focusing seat cover plate, a focusing worm wheel, a focusing seat, a limiting wear-resistant block and a limiting screw, the focusing lens group is installed in a focusing lens seat, the focusing lens seat is installed on a linear guide rail, a round wire coil spring is installed inside the focusing lens seat, a linear potentiometer is installed on the focusing lens seat, one side of the linear potentiometer ejector pin is pressed against a fixed block, thereby ensuring that during the sliding process of the focusing lens seat, the position information of the focusing lens group is fed back in real time, and accurate and reliable code disk position information is provided for subsequent software control of the focusing process. The utility model can make the focusing control algorithm of the continuous zoom infrared system simple and reliable, and at the same time, the internal space occupies a considerable limit, and can be widely used in structural design in related fields.

Description

Technical Field

[0001] The utility model relates to the technical field of infrared system continuous zoom lenses, in particular to a focusing structure of an infrared system continuous zoom lens. Background Art

[0002] In recent years, with the continuous development and progress of infrared technology at home and abroad, infrared optical systems have been widely used in military and civilian fields. At the same time, small size and light weight have become the most basic technical requirements of infrared systems.

[0003] Due to the constraints on space, traditional infrared optical machines have developed in the direction of refinement and miniaturization. This inevitably requires the ability to think from multiple angles when doing structural design, and to complete the structural design of the product within the limited space to meet the functional and performance requirements of the whole machine. Therefore, it is necessary to design a focusing structure for the continuous zoom lens of the infrared system. Utility Model Content

[0004] The purpose of the utility model is to provide a focusing structure for a continuous zoom lens of an infrared system, so as to solve the problem that the existing cylindrical cam barrel focusing structure of the infrared system cannot meet the space constraints, and to design a new focusing mechanism to meet the requirements of optics and the structure of the whole machine. Secondly, the assembly of the cylindrical cam barrel focusing structure is relatively complicated, and there are strict requirements on the machining accuracy of parts and the gaps between the sliding barrel, the fixed barrel and the cam barrel. If the gap is too small, it will cause the sliding to be not smooth. If the gap is too large, it will cause the sliding barrel to deviate greatly during the movement, thereby causing the consistency and stability of the optical axis during the focusing process of the entire infrared system. In addition, the cylindrical cam barrel structure relies on the sliding guide pin to slide in the cam groove to drive the sliding barrel to move forward and backward. A gap of 0.01 to 0.015 mm must be designed between the guide pin and the cam groove to ensure smooth sliding. Due to the existence of this sliding gap, the motor will inevitably produce a backlash problem during the focusing process, and a software design algorithm is required to eliminate the problem of backlash affecting the focusing position.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A focusing structure of a continuous zoom lens of an infrared system comprises a focusing drive component and a focusing lens group component, wherein the focusing drive component comprises a focusing motor seat, a focusing worm, a focusing motor, an eccentric wheel, a focusing seat cover plate, a focusing worm wheel, a flanged ball bearing, a focusing seat, a limiting wear block and a limiting screw, and the focusing lens group component comprises a guide pin, a high-precision linear potentiometer, an ultra-precision linear guide rail, a focusing lens group and a focusing lens seat, and the focusing drive component is mounted on a main frame.

[0007] As a further solution of the utility model: the focusing motor seat is installed on the main frame.

[0008] As a further solution of the utility model: the focus motor is installed on the focus motor seat, the output shaft of the focus motor is pressed into the focus worm hole through the top screw, and the focus worm is meshed with the focus worm wheel.

[0009] As a further solution of the utility model: the focusing lens seat is installed on an ultra-precision linear guide rail.

[0010] As a further solution of the utility model: the high-precision linear potentiometer is installed on the focusing lens seat.

[0011] As a further solution of the utility model: the focusing lens seat and the front lens group mounting hole are through-mounted.

[0012] As a further solution of the utility model: the focus drive component realizes the conversion of the rotation of the motor into linear motion, thereby driving the focus lens group component to move forward and backward, and the worm gear inside the focus drive component drives the eccentric wheel structure to realize the conversion of the rotation output of the focus motor into linear motion of the eccentric wheel after a large deceleration of the worm gear, thereby meeting the focal plane adjustment resolution requirements during focusing. Within the extreme space range, with the compensation lens group in front and the turning component in the back, the focusing structure has only a 15mm lateral space range to achieve the focusing function.

[0013] As a further solution of the utility model: a limiting structure is designed on the focusing drive component to ensure that the eccentric wheel can achieve reciprocating motion, which is convenient for motor control.

[0014] As a further solution of the utility model: the round wire helical spring installed on the focusing lens assembly is designed with a certain compression ratio to ensure that the eccentric wheel can be pressed back by the elastic force of the spring during the return stroke. A guide pin is designed in the middle of the round wire helical spring to ensure that the spring works smoothly under a large compression ratio.

[0015] As a further solution of the utility model: the focusing lens assembly is installed on an ultra-precision linear guide rail. The gap between the guide rail and the slider must be sufficient to not affect the optical axis consistency and stability of the entire infrared system during the focusing process.

[0016] As a further solution of the utility model: the focusing lens seat is installed on the slider and is positioned by through-hole means to ensure coaxiality with the front lens group, thereby achieving consistency and stability of the optical axis of the whole machine during subsequent optical debugging.

[0017] As a further solution of the utility model: the focusing lens group component is installed with a precision linear potentiometer, and the precise point of the mechanism movement is fed back to the control system through the linear potentiometer, which can ensure real-time control of the focusing lens group component during the reciprocating motion.

[0018] Compared with the prior art, the beneficial effects of the utility model are:

[0019] The utility model adopts a structural form in which a worm gear drives an eccentric wheel, thereby realizing the focusing function of the focusing lens group, greatly reducing the lateral space occupied by the focusing structure. Compared with the traditional focusing structure, since the focusing lens group is not driven forward and backward by a cylindrical cam, the empty return phenomenon of the motor is eliminated, and the elimination of the motor empty return through software control is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a focusing structure diagram of a continuous zoom lens of an infrared system.

[0021] Figure 2 The present invention is a structural diagram of a focus driving component in a focus structure of a continuous zoom lens of an infrared system.

[0022] Figure 3 The present invention is a structural diagram of the focusing lens group components in the focusing structure of a continuous zoom lens of an infrared system.

[0023] Figure 4 This is the commonly used focusing structure diagram of the continuous zoom lens of the common infrared system.

[0024] In the figure: 1. compensation mirror seat component; 2. guide pin pressure plate; 3. guide pin fixing block; 4. round wire coil spring; 5. focusing lens group component; 6. limit wear-resistant block; 7. focusing drive component; 8. turning component; the focusing drive component includes: 9. focusing motor seat; 10. focusing worm; 11. focusing motor; 12. eccentric wheel; 13. focusing seat cover; 14. focusing worm wheel; 15. flanged ball bearing; 16. focusing seat; 17. limit screw; 18. guide pin; 19. high-precision linear potentiometer; 20. ultra-precision linear guide; 21. focusing lens group; 22. focusing lens seat; 23. focusing motor; 24. focusing lens seat; 25. rotary potentiometer; 26. cylindrical cam; 27. focusing guide pin; 28. focusing lens group; 29. ​​cam pressure ring; 30. pinion; 31. cam retaining ring. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0026] See also Figures 1 to 3In the embodiment of the utility model, a focusing structure of a continuous zoom lens of an infrared system includes a focusing drive component 7 and a focusing lens group component 5, wherein the focusing drive component 7 includes a focusing motor seat 9, a focusing worm 10, a focusing motor 11, an eccentric wheel 12, a focusing seat cover 13, a focusing worm wheel 14, a flanged ball bearing 15, a focusing seat 16, a limit wear block 6 and a limit screw 17, and the focusing lens group component 5 includes a guide pin 18, a high-precision linear potentiometer 19, an ultra-precision linear guide rail 20, a focusing lens group 21 and a focusing lens seat 22;

[0027] The focusing drive component 7 is installed on the main frame, and the eccentric wheel 12 drives the focusing lens group component to move forward and backward along the ultra-precision linear guide 20. A limit wear block 6 is added between the eccentric wheel 12 and the focusing lens seat 22 to increase the wear resistance and facilitate the correction of the focusing position. The return process of the focusing lens group component is reverse movement under the elastic force of the round wire coil spring 4, which can ensure that the eccentric wheel 12 and the limit wear block 6 are always in contact. The focusing lens seat 22 is installed with a high-precision linear potentiometer 19, which can feedback the focusing position information in real time and report it to the system. A guide pin 18 is passed through the inside of the round wire coil spring 4, and the guide pin 18 and the round wire coil spring 4 are fixed on the guide pin fixing block 3. The guide pin pressure plate 2 is used to press the guide pin 18 at the back. The guide pin fixing block 3 is installed on the main frame of the infrared system. In order to ensure the installation position accuracy, the installation hole processing on the main frame needs to set a higher position accuracy requirement.

[0028] The focusing drive component 7 is the driving device of the entire structure and is installed on the main frame of the infrared system. The transmission mechanism is a worm gear driving an eccentric wheel to convert rotational motion into linear motion, thereby driving the focusing lens group 21 installed on the focusing lens seat 22 to achieve focusing control.

[0029] The transmission mechanism is a worm gear mechanism, which has a compact space, a relatively large reduction ratio, and is relatively practical. It is suitable for use in situations where the design space is limited and the structure is densely arranged.

[0030] Since the refractive index of infrared optical materials varies greatly with temperature, changes in ambient temperature will cause the image plane position of the infrared optical system to shift, that is, defocusing. Since the front lens group of the infrared system we designed uses a thin lens with a small relative thickness h / D, its expansion coefficient is relatively large, and the temperature difference has a relatively large impact on the imaging quality. The maximum displacement of the focusing mechanism, that is, the defocus amount allowed by the optical system, is given by the optical design. The focusing lens group 21 gives a defocus amount of ±1mm according to the optical design. Considering factors such as the processing error of the focusing mechanism itself, a certain range of redundancy needs to be reserved during the design. Therefore, when designing the structure, the range of the eccentric wheel is set to ±1.5mm, which can achieve optical compensation at an operating temperature of -40℃ to +60℃, meeting the imaging quality requirements under different ambient temperature conditions.

[0031] The main indicators of focusing are the maximum defocus of the system and the focal plane adjustment resolution. When designing an optical system, a certain amount of defocus is allowed. Within the defocus range, the optical transfer function MTF of the entire optical system will decrease slightly, but it will not affect the imaging quality of the entire system. In general, the maximum defocus is no more than half the focal depth of the optical system;

[0032] The focusing lens seat 22 is installed by a through-shaft method, which can meet the coaxiality requirements of the matching holes of the focusing lens seat 22 and the focusing lens group 21 and the matching holes of the front lens group installed on the main frame, thereby ensuring that the optical axis deviation of the focusing lens group 21 and the front lens group during the sliding process meets the technical requirements;

[0033] Due to space limitations, the front is the position of the compensation mirror holder 1 with a large field of view, and the rear is the position of the reflector in the turning component 8. The limited lateral space of the focusing structure is only 15 mm. The conventional cylindrical cam focusing structure cannot be used in such a small lateral space, so we can only change our thinking and use other structures.

[0034] The focusing motor seat 9 is mounted on the main frame, and the focusing motor 11 is mounted on the focusing motor seat 9. The output shaft of the focusing motor 11 is pressed into the hole of the focusing worm 10 through the top screw. The focusing worm 10 is meshed with the focusing worm wheel 14, and the rotation output of the motor shaft is decelerated and transmitted to the eccentric wheel 12. The eccentric rotation of the eccentric wheel 12 drives the focusing lens group component 5 to push the process. During the pushing process, the focusing lens group component 5 retreats and compresses the round wire coil spring 4. The round wire coil spring 4 and the guide pin are fixed to the guide pin fixing block 3 and the guide pin pressure plate 2. During the return process, the compressed round wire coil spring 4 releases the elastic force FX, driving the focusing lens group component 5 to move backward, so that the reciprocating motion of the focusing lens group component 5 is realized.

[0035] The focusing lens seat 22 is installed on the ultra-precision linear guide 20, which can ensure that the focusing lens group 21 can perform single lateral reciprocating movement along the optical axis direction. At the same time, the high-precision linear potentiometer 19 installed on the focusing lens seat 22 can feed back the displacement data of the focusing lens group 21 to the infrared system in real time to achieve precise detection and regulation. During installation, in order to ensure smooth sliding of the focusing lens seat 22 while maintaining the consistency and stability of the optical axis, the focusing lens seat 22 and the front lens group mounting hole are installed in a through-hole manner, thereby ensuring the coaxiality of the mounting hole position, which is also a necessary step to ensure the optical performance of the entire infrared system.

[0036] See also Figure 4 The commonly used focusing structure includes a focusing motor 23, a focusing lens seat 24, a rotary potentiometer 25, a cylindrical cam 26, a focusing guide pin 27, a focusing lens group 28, a cam pressure ring 29, a pinion 30 and a cam retaining ring 31. The commonly used focusing structure is a focusing motor 23 installed on the focusing lens seat 24. The pinion 30 is engaged with the teeth on the cylindrical cam 26 to decelerate the rotation of the output shaft of the focusing motor 23 and transmit it to the cylindrical cam 26 to realize the rotation of the cylindrical cam 26. The cam groove on the cylindrical cam 26 drives the focusing guide pin 27 to slide. The focusing guide pin 27 is installed on the focusing lens group 28, so that it moves back and forth with the focusing guide pin 27. A rotary potentiometer 25 is also installed on the focus lens seat 24. A pinion 30 with the same number of teeth as the focus motor 23 is installed on the output shaft of the rotary potentiometer 25. The pinion 30 also meshes with the teeth on the cylindrical cam 26 to achieve synchronous rotation with the focus motor size. In this way, the motor rotation angle and the potentiometer rotation are synchronized. The real-time data of the cam rotation angle is transmitted to the infrared control system through the rotary potentiometer 25. Cam retaining rings 31 are installed before and after the cylindrical cam 26. The cam retaining ring 31 uses a material with good wear resistance (such as copper or polytetrafluoroethylene) to ensure that the cylindrical cam 26 will not rub product dust when rotating, thereby affecting the structural work. The cam pressing ring 29 is installed on the focus lens seat 24 through a threaded connection, pressed on the cam retaining ring 31, and pressed the cam retaining ring 31 and the cylindrical cam 26. The cam pressing ring 29 cannot be pressed too tight or too loose, and a certain gap must be adjusted to ensure that the cylindrical cam 26 rotates smoothly without blocking.

[0037] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A focusing structure of a continuous zoom lens of an infrared system, comprising a focusing drive component (7) and a focusing lens assembly component (5), characterized in that: The focus drive component (7) comprises a focus motor seat (9), a focus worm (10), a focus motor (11), an eccentric wheel (12), a focus seat cover plate (13), a focus worm wheel (14), a flanged ball bearing (15), a focus seat (16), a limit wear block (6) and a limit screw (17); the focus lens group component (5) comprises a guide pin (18), a high-precision linear potentiometer (19), an ultra-precision linear guide rail (20), a focus lens group (21) and a focus lens seat (22); and the focus drive component (7) is mounted on a main frame.

2. The focusing structure of the infrared system continuous zoom lens according to claim 1, characterized in that: The focusing motor seat (9) is mounted on the main frame.

3. The focusing structure of the infrared system continuous zoom lens according to claim 1, characterized in that: The focus motor (11) is mounted on a focus motor seat (9), and the output shaft of the focus motor (11) is pressed into a hole of a focus worm (10) through a top screw, and the focus worm (10) is meshed with a focus worm wheel (14).

4. The focusing structure of the infrared system continuous zoom lens according to claim 1, characterized in that: The focusing lens seat (22) is installed on an ultra-precision linear guide rail (20).

5. The focusing structure of the infrared system continuous zoom lens according to claim 1, characterized in that: The high-precision linear potentiometer (19) is mounted on the focusing lens seat (22).

6. The focusing structure of the infrared system continuous zoom lens according to claim 1, characterized in that: The focusing lens seat (22) and the front lens assembly mounting hole are through-mounted.

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