Lens continuous zooming mechanism

Abstract

The invention provides a lens continuous zooming mechanism. The lens continuous zooming mechanism comprises a base, a guide group, a zooming driving group, a zoom lens group, a compensation lens group, a first switch group, a second switch group and a switch stop block. The zoom driving group is mounted on a base in the guide group, a first anti-backlash bearing and a second anti-backlash bearing in the zoom sliding block group are clamped in a zoom curve groove in a cam rod, and zoom anti-backlash is realized under the combined action of a first anti-backlash spring in the zoom sliding block group and a kidney-shaped hole in a zoom sliding block; a third anti-backlash bearing and a fourth anti-backlash bearing in the compensation sliding block set are clamped into a compensation curve groove in the cam rod, and compensation anti-backlash is achieved under the combined action of a third anti-backlash spring and a kidney-shaped hole in the compensation sliding block. The zoom mirror group and the compensation mirror group are both mounted on the same pair of slide rails with prepressing, and continuous and reliable zoom of the lens is realized by utilizing the guide of the slide rails and driving a cam lever with a zoom and compensation curve groove through a single motor; and the zoom driving group and the guide group are in flexible connection, so that the assembly difficulty is reduced, and the whole-course zoom time is short.

Description

Technical Field

[0001] The invention relates to a zoom lens, in particular to a lens continuous zoom mechanism. Background Art

[0002] When the focal length of a continuous zoom lens changes continuously within a certain range, the image plane position remains unchanged, and the size of the image of the scene on the image plane is continuously variable, obtaining a visual effect that cannot be achieved by a fixed-focus lens and a multi-speed zoom lens, and can achieve the purpose of searching for targets in a large field of view and tracking or identifying targets in a small field of view. Since the continuous zoom lens has the ability to search for targets in a large field of view and track targets in a small field of view, the field of view changes continuously, and it is not easy to lose the target, which greatly improves the adaptability of the imaging system, and therefore has been widely used in various fields. Image quality and optical axis stability are one of the key technical indicators for measuring continuous zoom lenses. In some tracking and sighting scenarios, the requirements for image quality and optical axis stability of continuous zoom lenses are getting higher and higher. The zoom mechanism is the core of the continuous zoom lens, and its performance directly affects the performance of the continuous zoom lens, and then affects the various functions and performances of the continuous zoom imaging system. The zoom mechanism generally includes a group of variable magnification lens groups, a group of compensation lens groups, and a corresponding drive group. Usually, the two lens groups, driven by the drive group, move linearly along the optical axis according to the conjugate relationship designed according to the optical principle to complete the zoom of the lens and achieve clear imaging. In order to achieve clear and jitter-free images throughout the zoom process and to ensure that the optical axis offset during and after zooming is within the required range, it is necessary to ensure the accuracy of the linear motion of the zoom lens group and the compensation lens group along the optical axis, while ensuring that the zoom mechanism is free of gaps.

[0003] At present, the common zoom mechanisms include the curve sleeve mechanism and the screw guide mechanism. The working principle of the curve sleeve zoom mechanism is: a zoom curve groove and a compensation curve groove are processed on the curve sleeve by high-precision machining. These two curve grooves meet the conjugate relationship of the optical design, and the zoom is achieved by converting the rotational motion of the curve sleeve into the linear motion of the zoom lens group and the compensation lens group along the guide tube. Since this zoom mechanism can ensure the positional relationship between the zoom lens group and the compensation lens group during zooming by simply rotating the curve sleeve, it is relatively simple to control it. However, since the zoom lens group and the compensation lens group are matched with the guide tube of the curve sleeve mechanism, and between the guide pin and the curve groove, the wear caused by sliding friction will cause the matching clearance to become larger and larger as the use time increases, which is not only easy to cause the mechanism to stagnate or even completely jam, but also easy to cause image jitter and optical axis drift during zooming.

[0004] The basic working principle of the screw-slide zoom mechanism is: both the zoom lens group and the compensating lens group are mounted on the slide rails and connected to the nuts on the two screws respectively, two drive groups are used to control the zoom lens group and the compensating lens group respectively, and zooming is achieved by converting the rotational motion of the screw into the linear motion of the zoom lens group and the compensating lens group along the slide rails. For example, the Chinese utility model patent with the announcement number CN213876152U discloses a screw-slide zoom mechanism, which is essentially a structure in which the zoom lens group and the compensating lens group are fixed on the same pair of slide rails using a slide rail guide and a stepper motor (with integrated screw nut and encoder) drive. The two lens groups are connected to the nuts on the two stepper motors respectively, and the conjugate relationship between the zoom lens group and the compensating lens group is ensured by the closed-loop control of the encoder provided by the stepper motor. Since the friction between the kinematic pairs of this zoom mechanism is rolling friction, and the gap in the mechanism is eliminated by using anti-backlash nuts and pre-loaded slide rails, this zoom mechanism has high precision, long life, good stability and high reliability. However, since the nut and the two lens groups in this zoom mechanism are hard-connected, the parallelism requirements between the lead screw and the slide rail are relatively high. If there is a slight error in the parallelism between the slide rail and the lead screw or the straightness of the lead screw itself, image jitter and optical axis drift will occur during the zoom process, so the assembly difficulty is relatively large. In addition, since it uses a double lead screw and a double motor to control the zoom lens group and the compensation lens group respectively so that they reach the conjugate position in real time, the servo control of the lead screw and slide rail zoom mechanism is difficult, complex, and costly compared to the curved sleeve zoom mechanism. Summary of the invention

[0005] The purpose of the present invention is to solve the problems that the existing lens zoom mechanism is prone to image jitter and optical axis drift, as well as the difficulty of servo control, complex structure and high cost, and to provide a lens continuous zoom mechanism. The variable magnification lens group and the compensation lens group used in the continuous zoom mechanism of the present invention are both installed on the same pair of pre-loaded slide rails, guided by the slide rails; the zoom function is achieved by a single motor driving a cam rod with a variable magnification compensation curve groove; the drive group and the guide group are softly connected to reduce the difficulty of assembly. All kinematic pairs are designed to eliminate backlash, so that the mechanism maintains high precision and high stability, while reducing the number of control elements as much as possible to reduce the cost of the mechanism.

[0006] The technical solution provided by the present invention is as follows:

[0007] A lens continuous zoom mechanism, comprising a guide group, a zoom drive group, a magnification lens group and a compensation lens group;

[0008] The guide group includes a base, a first pre-loaded slide rail, a second pre-loaded slide rail, a zoom slider group, a zoom lens group bracket, a compensation slider group and a compensation lens group bracket; the first pre-loaded slide rail and the second pre-loaded slide rail are arranged in parallel on the top surface of the base; the zoom slider group and the compensation slider group are arranged on the first pre-loaded slide rail and the second pre-loaded slide rail, and straddle the first pre-loaded slide rail and the second pre-loaded slide rail, and the zoom slider group and the compensation slider group can slide along the first pre-loaded slide rail and the second pre-loaded slide rail; the maximum distance between the zoom slider group and the compensation slider group is determined according to the zoom limit stroke of the lens;

[0009] The zoom lens group bracket and the compensating lens group bracket are respectively fixed vertically on the top surfaces of the zoom slider group and the compensating slider group, and are coaxially arranged; the zoom lens group bracket and the compensating lens group bracket are respectively used to install the zoom lens group and the compensating lens group;

[0010] The zoom slider group includes a zoom slider, a first positioning rod, a first bearing rod, a first anti-backlash spring, a first anti-backlash bearing and a second anti-backlash bearing; the first positioning rod is located in the zoom slider and is vertically arranged with the first bearing rod, and one end of the first bearing rod is fixedly connected with the first positioning rod; the end of the zoom slider has a first boss extending vertically outward, and the other end of the first bearing rod extends out along the inner hole of the first boss; the first anti-backlash spring is sleeved on the first positioning rod, the first anti-backlash bearing is mounted on the first boss, and the second anti-backlash bearing is mounted on the extended section of the first bearing rod; the first anti-backlash spring is used to cause radial misalignment between the first anti-backlash bearing and the second anti-backlash bearing;

[0011] The compensating slider group includes a compensating slider, a second positioning rod, a second bearing rod, a second anti-backlash spring, a third anti-backlash bearing and a fourth anti-backlash bearing; the second positioning rod is located in the compensating slider and is vertically arranged with the second bearing rod, and one end of the second bearing rod is fixedly connected with the second positioning rod; the end of the compensating slider has a second boss extending vertically outward, and the other end of the second bearing rod extends out along the inner hole of the second boss; the third anti-backlash spring is sleeved on the second positioning rod, the third anti-backlash bearing is mounted on the second boss, and the fourth anti-backlash bearing is mounted on the extended section of the second bearing rod; the second anti-backlash spring is used to cause radial misalignment between the third anti-backlash bearing and the fourth anti-backlash bearing;

[0012] The zoom drive group is mounted on the top surface of the base and is arranged parallel to the side of the guide group; the zoom drive assembly includes a zoom motor assembly, a first zoom gear, a second zoom gear, a cam bracket and a cam rod mounted on the cam bracket, and the side wall of the cam rod is provided with a conjugate relationship between a zoom curve groove and a compensation curve groove designed according to optical principles, the groove width of the zoom curve groove is equal to the outer diameter of the first anti-backlash bearing and the second anti-backlash bearing, and the groove width of the compensation curve groove is equal to the outer diameter of the third anti-backlash bearing and the fourth anti-backlash bearing;

[0013] The first zoom gear is coaxially mounted on one end of the cam rod, and the second zoom gear is coaxially mounted on the output end of the zoom motor assembly; the second zoom gear can reliably mesh with the first zoom gear for transmission;

[0014] The first and second anti-backlash bearings of the zoom slider group are inserted into the zoom curve groove of the cam rod, and the third and fourth anti-backlash bearings of the compensation slider group are inserted into the compensation curve groove of the cam rod; the cam rod can rotate under the drive of the zoom motor, so that the radial misalignment between the first and second anti-backlash bearings can be eliminated under the squeezing action of the wall of the zoom curve groove, and the radial misalignment between the third and fourth anti-backlash bearings can be eliminated under the squeezing action of the wall of the compensation curve groove.

[0015] Furthermore, it also includes a zoom limit assembly, which is used to calibrate the zoom starting position and zoom stroke of the lens;

[0016] The zoom limit assembly includes a switch block, a first switch group and a second switch group; the first switch group and the second switch group are respectively fixed at two ends of the top surface of the base and are located between the first pre-loaded slide rail and the second pre-loaded slide rail; the distance between the first switch group and the second switch group is determined according to the zoom limit travel of the lens;

[0017] The switch block is installed at the bottom of the magnification slider and can contact the first switch group or the second switch group. When the switch block touches the first switch group, the measured large field of view value of the lens is greater than the large field of view value required by the lens technical indicators; when the switch block touches the second switch group, the measured small field of view value of the lens is less than the small field of view value required by the lens technical indicators.

[0018] Furthermore, it also includes a zoom lens group adjustment gasket and a compensation lens group adjustment gasket; the zoom lens group is installed in the central mounting hole on the top of the zoom lens group bracket through the zoom lens group adjustment gasket; the compensation lens group is installed in the central mounting hole on the top of the compensation lens group bracket through the compensation lens group adjustment gasket;

[0019] The variable magnification lens group adjustment gasket and the compensating lens group adjustment gasket are used to adjust the distance between the variable magnification lens group and the compensating lens group so that the installation positions of the variable magnification lens group and the compensating lens group meet the optical design requirements.

[0020] Furthermore, the first pre-stressed slide rail comprises a first rail and a first slider installed on the first rail, and the first rail and the first slider have a pre-stress between them. The second pre-stressed slide rail comprises a second rail and a second slider installed on the second rail, and the second rail and the second slider have a pre-stress between them. Both ends of the variable power slider and both ends of the compensation slider are respectively fixed to the top surfaces of the first slider and the second slider, and the bottom surfaces of the variable power slider and the compensation slider are in full contact with the top surfaces of the first slider and the second slider;

[0021] The variable magnification slider and the compensation slider can slide along the first track and the second track driven by the first slider and the second slider.

[0022] Further, the zoom lens group bracket is vertically fixed to the middle part of the top surface of the zoom slider, the top surface of the zoom slider and close to one end of the zoom drive group has a first protrusion extending vertically upward, the first protrusion is provided with a first step blind hole along the axis direction of the central mounting hole at the top of the zoom lens group bracket, the first positioning rod and the first anti-backlash spring are installed in the first step blind hole, and the two ends of the first anti-backlash spring are limited between the step surface of the first step blind hole and the step surface of the first positioning rod;

[0023] The first boss extends outward perpendicularly to the side wall of the first protrusion, and the inner hole of the first boss is a first waist hole; the first bearing rod is located in the first waist hole, and the first bearing rod is threadedly connected to the first positioning rod;

[0024] The compensation lens group bracket is vertically fixed to the middle of the top surface of the compensation slider, and the top surface of the compensation slider and close to one end of the zoom drive group has a second protrusion extending vertically upward, and the second protrusion is provided with a second step blind hole along the axis direction of the central mounting hole at the top of the compensation lens group bracket, and the second positioning rod and the second backlash elimination spring are installed in the second step blind hole, and the two ends of the second backlash elimination spring are limited between the step surface of the second step blind hole and the step surface of the second positioning rod;

[0025] The second boss extends outward perpendicularly to the side wall of the second protrusion, and the inner hole of the second boss is a second waist hole; the second bearing rod is located in the second waist hole, and the second bearing rod is threadedly connected to the second positioning rod.

[0026] Further, the first boss and the second boss are stepped shaft-shaped, the first anti-backlash bearing is coaxially mounted on the first boss and away from the shaft body of the first protrusion side wall by bonding, and the third anti-backlash bearing is coaxially mounted on the second boss and away from the shaft body of the second protrusion side wall by bonding;

[0027] The second anti-backlash bearing and the fourth anti-backlash bearing are respectively mounted on the first bearing rod and the second bearing rod by bonding.

[0028] Furthermore, both ends of the cam bracket have support arms arranged vertically upward, and one end of the cam rod is installed on the support arm at one end of the cam bracket through a deep groove ball bearing; the cam rod is sleeved in the inner ring of the deep groove ball bearing and is freely matched with the inner ring of the deep groove ball bearing;

[0029] The other end of the cam rod is mounted on the support arm at the other end of the cam bracket through a matching angular contact ball bearing; the cam rod is sleeved in the inner ring of the matching angular contact ball bearing and is fixedly connected to the inner ring of the matching angular contact ball bearing and is axially pressed by a third bearing pressure ring.

[0030] Furthermore, a first step through hole is formed on the support arm at one end of the cam bracket, and the deep groove ball bearing is installed in the small hole of the first step through hole; and further comprises a first bearing pressure ring, which is coaxially installed in the large hole of the first step through hole, and the end face of the first bearing pressure ring contacts the end face of the outer ring of the deep groove ball bearing to prevent the deep groove ball bearing from axially moving;

[0031] A through hole is formed on the support arm at the other end of the cam bracket, a bearing sleeve is installed in the through hole, a second step through hole is formed in the bearing sleeve along the axis, and the paired angular contact ball bearing is installed in a small hole of the second step through hole;

[0032] It also includes a second bearing pressure ring, which is located in the large hole of the second step through hole, and the end face of the second bearing pressure ring contacts the end face of the outer ring of the paired angular contact ball bearing to prevent the paired angular contact ball bearing from moving axially.

[0033] Furthermore, the zoom motor assembly includes a zoom motor seat and a zoom motor, wherein the zoom motor seat is fixed on the support arm at the other end of the cam bracket and is close to the edge of the support arm; the zoom motor is installed on the zoom motor seat;

[0034] It also includes a gear pressure plate, through which the second zoom gear is axially fixedly connected to the output shaft of the zoom motor.

[0035] The zoom motor is equipped with a high-precision encoder for real-time feedback of the focal length.

[0036] Furthermore, the transmission ratio of the first zoom gear and the second zoom gear is determined according to the zoom time required by the lens technical indicators; the larger the transmission ratio, the slower the zoom time, and the smaller the transmission ratio, the faster the zoom time.

[0037] The advantages of the present invention are:

[0038] 1. The continuous zoom mechanism of the lens of the present invention comprises a guide group, a zoom driving group, a magnification lens group and a compensation lens group; the guide group comprises a pair of pre-loaded slide rails, the magnification lens group and the compensation lens group are respectively installed on the pre-loaded slide rails through a magnification slider group and a compensation slider group, and the sides of the magnification slider group and the compensation slider group are both equipped with anti-backlash bearing groups, which are respectively inserted into the magnification curve groove and the compensation curve groove provided on the cam rod of the zoom driving group, and the radial misalignment between the anti-backlash bearings in the anti-backlash bearing groups on the magnification slider group and the compensation slider group can be eliminated under the squeezing action of the magnification curve groove wall and the compensation curve groove wall, so as to realize stable zoom of the lens, and the zoom accuracy is high and the reliability is strong.

[0039] 2. In the present invention, a pair of anti-backlash bearings are used on the zoom slider group and the compensation slider group, which are respectively inserted into the zoom curve groove and the compensation curve groove of the cam rod. The width of the anti-backlash bearing is equal to the width of the corresponding curve groove. When the anti-backlash bearing rolls in the curve groove, even if it is worn, the anti-backlash bearing can still be clamped in the corresponding curve groove under the pressure of the anti-backlash spring installed on the zoom slider group and the compensation slider group, and no gap will appear. This avoids the problem that the guide pin and the curve groove in the curve sleeve mechanism in the prior art are matched with the shaft hole. As the use time increases, the friction causes the matching gap to become larger and larger, thereby resulting in a decrease in zoom accuracy and jitter of the image optical axis.

[0040] 3. In the guide group of the present invention, two pre-loaded slide rails are used in pairs, and the base is finely processed according to the processing and installation benchmark to ensure the parallelism of the installation of the two slide rails on the base.

[0041] 4. The guide group and zoom drive group in the present invention adopt a modular design, and when integrated, a soft connection between the guide group and the zoom drive group is achieved by plugging and matching the anti-backlash bearing with the corresponding curved groove on the cam rod. Even if there is a certain deviation in the parallelism between the zoom drive group and the guide group, it will not have a fatal impact on the optical axis, thereby reducing the difficulty of installation and adjustment.

[0042] 5. The larger the meshing transmission ratio of the first zoom gear and the second zoom gear in the zoom drive group of the present invention, the slower the zoom time, and the smaller the transmission ratio, the faster the zoom time. Therefore, the meshing transmission ratio of the first zoom gear and the second zoom gear can be optimized according to the required zoom time. The design is highly operational and can meet different focusing requirements.

[0043] 6. In the present invention, only one set of zoom motor is used to drive the cam rod to complete the zoom. Compared with the existing screw slide rail mechanism, the driving components are reduced, thereby reducing the cost of the zoom mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a three-dimensional structural schematic diagram of a lens continuous zoom mechanism of the present invention;

[0045] Figure 2 It is a top view of a lens continuous zoom mechanism of the present invention;

[0046] Figure 3 It is a three-dimensional schematic diagram of the structure of the guide group of the present invention;

[0047] Figure 4 is a side view of the guide group of the present invention;

[0048] Figure 5 It is a schematic diagram of the three-dimensional structure of the zoom slider group of the present invention;

[0049] Figure 6 is a cross-sectional view of the zoom slider assembly of the present invention;

[0050] Figure 7 It is a structural stereoscopic schematic diagram of the compensation slider group of the present invention;

[0051] Figure 8 is a cross-sectional view of the compensation slider assembly of the present invention;

[0052] Fig. 9 This is a front view of the zoom drive group of the present invention;

[0053] Fig.10 It is a structural front view of the cam of the present invention.

[0054] Description of the accompanying drawings: 1-guide group, 2-zoom drive group, 3-zoom lens group, 4-zoom lens group adjustment gasket, 5-compensation lens group, 6-compensation lens group adjustment gasket, 71-first switch group, 72-second switch group, 8-switch block, 9-base, 10-first pre-loaded slide rail, 101-first slider, 102-first track, 11-second pre-loaded slide rail, 111-second slider, 112-second track, 12-zoom slider group, 13-zoom lens group bracket, 14-compensation slider group, 15-compensation lens group bracket, 16-zoom slider, 161-first waist hole, 171-first positioning rod, 172-second positioning rod, 181-first bearing rod, 182-second bearing rod, 191-first anti-backlash spring, 192-second anti-backlash spring, 201-first anti-backlash bearing, 211-second anti-backlash bearing, 202-third anti-backlash bearing, 212-fourth anti-backlash bearing, 22-compensation slider, 221-second waist hole, 23-cam bracket, 24-cam rod, 241-zoom curve groove, 242-compensation curve groove, 25-deep groove ball bearing, 26-first bearing pressure ring, 27-bearing sleeve, 28-paired angular contact ball bearing, 29-second bearing pressure ring, 30-third bearing pressure ring, 31-first zoom gear, 32-second zoom gear, 33-gear pressure plate, 34-zoom motor seat, 35-zoom motor. DETAILED DESCRIPTION

[0055] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0056] Reference Figure 1 and Figure 2 A lens continuous zoom mechanism provided by a preferred embodiment of the present invention comprises a guide group 1, a zoom drive group 2, a zoom lens group 3, a zoom lens group adjustment gasket 4, a compensation lens group 5, a compensation lens group adjustment gasket 6, a first switch group 71, a second switch group 72 and a switch block 8. The zoom drive group 2 is mounted on a base 9 in the guide group 1, and the first anti-backlash bearing 201 and the second anti-backlash bearing 211 in the zoom slider group 12 are inserted into the zoom curve groove 241 on the cam rod 24, and the clearance is eliminated under the joint action of the first anti-backlash spring 191 and the first waist hole 161 on the zoom slider 16. The first anti-backlash bearing 202 and the second anti-backlash bearing 212 in the compensation slider group 14 are inserted into the compensation curve groove 242 on the cam rod 24, and the clearance is eliminated under the joint action of the second anti-backlash spring 192 and the second waist hole 221 on the compensation slider 22. The zoom lens group 3 is installed on the zoom lens group bracket 13 in the guide group 1 and cooperates with the axial hole of the zoom lens group bracket 13; the compensation lens group 5 is installed on the compensation lens group bracket 15 in the guide group 1 and cooperates with the axial hole of the compensation lens group bracket 15.

[0057] When the cam rod 24 in the zoom drive group 2 is rotated to the extreme position, the zoom lens group 3 and the compensating lens group 5 should be maintained at the theoretical position of the optical design, and the thickness of the zoom lens group adjustment gasket 4 and the compensating lens group adjustment gasket 6 are determined according to the difference between the theoretical value and the measured value. By adjusting the thickness of the zoom lens group adjustment gasket 4 and the compensating lens group adjustment gasket 6, the installation positions of the zoom lens group and the compensating lens group can be adjusted to meet the optical design requirements.

[0058] Reference Figure 3 and Figure 4 The guide group 1 includes a base 9, a first pre-stressed slide rail 10, a second pre-stressed slide rail 11, a zoom slider group 12, a zoom lens group bracket 13, a compensation slider group 14, and a compensation lens group bracket 15. The base 9 is designed and finely processed based on the side and bottom surfaces of the first pre-stressed slide rail and the second pre-stressed slide rail as reference surfaces to ensure that the first pre-stressed slide rail 10 and the second pre-stressed slide rail 11 are parallel to the top surface of the base after being installed on the base with screws. The first pre-stressed slide rail 10 is composed of a first slider 101 and a first track 102, and the second pre-stressed slide rail 11 is composed of a second slider 111 and a second track 112. The two slide rails are selected in pairs, and both are selected with a model with a pre-stress between the slider and the track to eliminate the gap between the slider and the track. The zoom slider group 12 and the compensation slider group 14 are arranged at both ends of the first pre-loaded slide rail 10 and the second pre-loaded slide rail 11, and straddle the first pre-loaded slide rail and the second pre-loaded slide rail. The zoom slider group 12 and the compensation slider group 14 can slide along the first pre-loaded slide rail and the second pre-loaded slide rail.

[0059] The zoom lens group bracket 13 and the compensating lens group bracket 15 are vertically mounted on the middle of the top surfaces of the zoom slider group 12 and the compensating slider group 14 respectively with screws. At the same time, a screw hole for mounting the zoom lens group 3 is reserved in the center of the zoom lens group bracket 13, and a screw hole for mounting the compensating lens group 5 is reserved in the center of the compensating lens group bracket 15.

[0060] Reference Figure 5 and Figure 6 The zoom slider group 12 includes a zoom slider 16, a first positioning rod 171, a first bearing rod 181, a first anti-backlash spring 191, a first anti-backlash bearing 201, and a second anti-backlash bearing 211. The two ends of the zoom slider are respectively fixed to the first slider 101 with a preloaded slide rail and the second slider 111 with a preloaded slide rail by screws, and the bottom surface of the zoom slider is in reliable contact with the bottom surfaces of the first slider 101 and the second slider 111.

[0061] A first protrusion extending vertically upward is provided on the top surface of the zoom slider 16 and close to one end of the zoom drive group. A first step blind hole is opened on the first protrusion along the axial direction of the center mounting hole (screw hole) at the top of the zoom lens group bracket 13. The first positioning rod and the first anti-backlash spring 191 are installed in the first step blind hole. Both ends of the first anti-backlash spring 191 are limited between the step surface of the first step blind hole and the step surface of the first positioning rod 171.

[0062] The side wall of the first protrusion of the variable power slider 16 is vertically provided with a first boss extending outward, and the first boss is in the shape of a stepped shaft. A first waist hole 161 for matching with the first bearing rod 181 is opened along the axis of the first boss, and the axis of the first waist hole is perpendicular to the axis of the first step blind hole on the first protrusion. A threaded hole is provided on the first positioning rod 171, and the threaded hole is used to be radially fixedly connected with one end of the first bearing rod 181. The outer diameters of the first anti-backlash bearing 201 and the second anti-backlash bearing 211 are equal to the groove width of the variable power curved groove 241 on the cam rod 24. The first anti-backlash bearing 201 is coaxially mounted on the first boss and away from the shaft body of the side wall of the first protrusion by bonding, and the second anti-backlash bearing 211 is mounted on the other end of the first bearing rod 181. After the first positioning rod 171 is covered with the first anti-backlash spring 191, it is inserted into the first step blind hole of the first convex block on the zoom slider 16. The first bearing rod 181 equipped with the second anti-backlash bearing 211 passes through the first waist hole 161 and is threadedly connected to the screw hole on the rod body of the first positioning rod 171. The first anti-backlash bearing 201 and the second anti-backlash bearing 211 produce a certain radial misalignment under the joint action of the first waist hole 161 and the first anti-backlash spring 191. Since the outer diameters of the first anti-backlash bearing 201 and the second anti-backlash bearing 211 are equal to the width of the zoom curve groove 241 of the cam rod 24, when the first anti-backlash bearing and the second anti-backlash bearing are inserted into the zoom curve groove 241, the misalignment will be eliminated under the squeezing action of the groove wall of the zoom curve groove. At this time, under the pressure of the first anti-backlash spring 191, the two bearings are always squeezed in the curve groove to achieve anti-backlash.

[0063] Reference Figure 7 and Figure 8 The compensation slider group 14 includes a compensation slider 22, a second positioning rod 172, a second bearing rod 182, a second backlash-eliminating spring 192, a third backlash-eliminating bearing 202 and a fourth backlash-eliminating bearing 212. The two ends of the compensation slider are respectively fixed to the first slider 101 with a preloaded slide rail and the second slider 111 with a preloaded slide rail by screws, and the bottom surface of the compensation slider is in reliable contact with the bottom surfaces of the first slider 101 and the second slider 111. The initial position of the compensation slider is at the second zoom limit position of the lens, that is, the maximum distance between the zoom slider and the compensation slider is the zoom limit stroke of the lens.

[0064] The top surface of the compensation slider 22 and close to one end of the zoom drive group has a second protrusion extending vertically upward, and a second step blind hole is opened on the second protrusion along the axis direction of the center mounting hole (screw hole) at the top of the compensation lens group bracket 15. The second positioning rod 172 and the second anti-backlash spring 192 are installed in the second step blind hole, and the two ends of the second anti-backlash spring 192 are limited between the step surface of the second step blind hole and the step surface of the second positioning rod 172. The side wall of the second protrusion of the compensation slider is vertically provided with a second boss extending outward, and the second boss is in the shape of a step shaft, and a second waist hole 221 for matching with the second bearing rod 182 is opened along the axis of the second boss. The second positioning rod 172 is provided with a threaded hole, and the threaded hole is used to connect one end of the second bearing rod 182 for radial fixed connection. The outer diameters of the third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 are equal to the groove width of the compensation curve groove 242 on the cam 24. The third anti-backlash bearing 202 is coaxially mounted on the second boss and away from the shaft body of the second protrusion side wall by bonding, and the fourth anti-backlash bearing 212 is coaxially mounted on the other end of the second bearing rod 182 by bonding. After the second anti-backlash spring 192 is sleeved on the second positioning rod 172, it is inserted into the second step blind hole on the second protrusion; the second bearing rod 182 with the fourth anti-backlash bearing 212 passes through the second waist hole 221 and is threadedly connected to the screw hole of the second positioning rod 172. The third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 produce a certain radial misalignment under the joint action of the second waist hole 221 and the second anti-backlash spring 192. Since the outer diameters of the third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 are equal to the width of the compensation curve groove 242 of the cam rod 24, when the third anti-backlash bearing and the fourth anti-backlash bearing are inserted into the compensation curve groove 242, the misalignment will be eliminated under the extrusion of the compensation curve groove wall. At this time, under the pressure of the second anti-backlash spring 192, the two bearings are always squeezed in the compensation curve groove, so that clearance can be eliminated.

[0065] Reference Fig. 9 and Fig.10 The zoom drive group 2 includes a cam bracket 23, a cam rod 24, a deep groove ball bearing 25, a first bearing pressure ring 26, a bearing sleeve 27, a paired angular contact ball bearing 28, a second bearing pressure ring 29, a third bearing pressure ring 30, a first zoom gear 31, a second zoom gear 32, a gear pressure plate 33, a zoom motor seat 34 and a zoom motor 35; a zoom curve groove 241 and a compensation curve groove 242 are processed on the side wall of the cam rod 24, and the zoom curve groove 241 and the compensation curve groove 242 are finely processed according to the conjugate relationship designed according to the optical principle. The outer diameters of the first anti-backlash bearing 201 and the second anti-backlash bearing 211 are both equal to the groove width of the zoom curve groove 241 on the cam rod 24, and the outer diameters of the third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 are both equal to the groove width of the compensation curve groove 242 on the cam rod 24.

[0066] The two ends of the cam bracket 23 have support arms arranged vertically upward. One end of the cam rod 24 is mounted on the support arm at one end of the cam bracket through a deep groove ball bearing 25, and this end of the cam rod is sleeved in the inner ring of the deep groove ball bearing and is freely connected to the inner ring of the deep groove ball bearing. The other end of the cam rod is mounted on the support arm at the other end of the cam bracket through a matching angular contact ball bearing, and this end of the cam rod is sleeved in the inner ring of the matching angular contact ball bearing, and this end of the cam rod is connected to the matching angular contact ball bearing 28 in a completely fixed manner. The cam rod adopts an assembly method in which one end is fixed and the other end is free, which can effectively prevent the mechanism from being stuck or stuck due to deformation of parts at high and low temperatures. Specifically, a first step through hole is opened on the support arm at one end of the cam bracket, and the deep groove ball bearing 25 is installed in the small hole of the first step through hole; the first bearing pressure ring 26 is coaxially installed in the large hole of the first step through hole, and the end face of the first bearing pressure ring 26 contacts the end face of the outer ring of the deep groove ball bearing 25 to prevent the deep groove ball bearing from moving axially. A through hole is formed on the support arm at the other end of the cam bracket 23, in which a bearing sleeve 27 is installed. The bearing sleeve 27 has a second step through hole formed along the axis. The paired angular contact ball bearing 28 is installed in the small hole of the second step through hole. The second bearing pressing ring 29 is located in the large hole of the second step through hole, and the end face of the second bearing pressing ring 29 contacts the end face of the outer ring of the paired angular contact ball bearing 28 to prevent the paired angular contact ball bearing from moving axially. The third bearing pressing ring 30 is located at the end of the cam rod 24 to axially press the cam rod 24 into the inner ring of the paired angular contact ball bearing 28 to prevent the cam rod 24 from moving axially.

[0067] The zoom motor seat 34 is fixed on the support arm at the other end of the cam bracket, and is close to the edge of the support arm. The zoom motor 35 is installed on the zoom motor seat. The second zoom gear 32 is fixedly installed on the output shaft of the zoom motor 35 along the axial direction through the gear pressure plate 33 and screws. The first zoom gear 31 is axially fixed on the cam rod 24 with screws, and the first zoom gear 31 and the second zoom gear 32 can mesh and transmit, and there is no empty return, so as to ensure the smooth operation of the zoom mechanism. When the zoom motor 35 works, the cam rod 24 is driven to rotate through the meshing transmission of the first zoom gear 31 and the second zoom gear 32, and the rotation is converted into the sliding of the magnification lens group 3 and the compensation lens group 5 on the slide rails 10 and 11 along the optical axis direction, so as to realize continuous zooming of the lens.

[0068] The zoom motor 35 is equipped with a high-precision encoder for real-time feedback of the position of the zoom motor to achieve closed-loop control of the zoom. It is easy for ordinary technicians in this field to understand that the zoom motor can be equipped with other types of position feedback devices.

[0069] Specifically, the first switch group 71, the second switch group 72 and the switch block 8 constitute a zoom limit assembly, which is used to calibrate the zoom starting position and zoom stroke of the lens. The first switch group and the second switch group are respectively fixed at both ends of the top surface of the base 9, and are located between the first track 102 and the second track 112. The positions of the first switch group 71 and the second switch group 72 are zoom limit positions, which are determined according to the zoom limit stroke of the lens. The switch block 8 is installed at the bottom of the zoom slider 16. When the zoom lens group 3 and the compensation lens group slide to the zoom limit position, the two sides of the switch block 8 can touch the first switch group 71 or the second switch group 72, thereby realizing the calibration of the zoom starting position and stroke. Specifically, when the switch block 8 touches the first switch group 71, the measured large field of view value of the lens should be greater than the large field of view value required by the lens technical indicators; when the switch block 8 touches the second switch group 72, the measured small field of view value of the lens should be less than the small field of view value required by the lens technical indicators. This can ensure that the large and small field of view values ​​throughout the zoom range cover the field of view values ​​required by the lens technical indicators. The above two touch positions can both be used as the zero position of the zoom stroke. When one of them is selected as the zero position, the other position is used as electrical protection. When the zoom reaches the zero position, the encoder of the zoom motor 35 is set to zero, and the field of view value required by the lens technical indicators is calibrated by the code value of the encoder.

[0070] When the zoom motor 35 drives the cam rod 24 to rotate, after the first anti-backlash bearing 201 and the second anti-backlash bearing 211 in the preferred embodiment of the present invention are inserted into the zoom curve groove 241 of the cam rod 24, since the diameters of the first anti-backlash bearing and the second anti-backlash bearing are the same as the groove width of the zoom curve groove, the radial misalignment of the two bearings caused by installation is eliminated under the squeezing pressure of the groove walls on both sides of the zoom curve groove, thereby achieving zoom elimination; after the third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 are inserted into the compensation curve groove 242 of the cam rod 24, since the diameters of the third anti-backlash bearing 202 and the fourth anti-backlash bearing 212 are the same as the groove width of the compensation curve groove, the radial misalignment of the two bearings caused by installation is eliminated under the pressure of the squeezing pressure of the groove walls on both sides of the compensation curve groove, thereby achieving compensation elimination.

[0071] The preferred embodiment of the present invention adopts a double slide rail guide, and a single cam rod simultaneously drives the magnification lens group and the compensation lens group to slide on the slide rail along the optical axis according to a conjugate optical relationship to achieve zooming; by selecting a slide rail with pre-pressure and adopting a double bearing anti-backlash method, the entire zoom mechanism is anti-backlash; the zoom mechanism has the advantages of the curved sleeve mechanism and the screw slide rail mechanism, and avoids the disadvantages of both, thereby achieving the goals of simple and easy adjustment of the zoom mechanism structure, low control difficulty, high precision, long life and good stability.

[0072] The above description is only a preferred embodiment of the present invention, which is only used to illustrate the technical solution of the present invention rather than to limit it. It should be pointed out that ordinary professional and technical personnel in the field can modify the specific technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A lens continuous zoom mechanism, characterized in that: It includes a guide group, a zoom drive group, a zoom lens group and a compensating lens group; The guide group includes a base, a first pre-loaded slide rail, a second pre-loaded slide rail, a zoom slider group, a zoom lens group bracket, a compensation slider group and a compensation lens group bracket; the first pre-loaded slide rail and the second pre-loaded slide rail are arranged in parallel on the top surface of the base; the zoom slider group and the compensation slider group are arranged on the first pre-loaded slide rail and the second pre-loaded slide rail, and straddle the first pre-loaded slide rail and the second pre-loaded slide rail, and the zoom slider group and the compensation slider group can slide along the first pre-loaded slide rail and the second pre-loaded slide rail; the maximum distance between the zoom slider group and the compensation slider group is determined according to the zoom limit stroke of the lens; The zoom lens group bracket and the compensating lens group bracket are respectively fixed vertically on the top surfaces of the zoom slider group and the compensating slider group, and are coaxially arranged; the zoom lens group bracket and the compensating lens group bracket are respectively used to install the zoom lens group and the compensating lens group; The zoom slider group includes a zoom slider, a first positioning rod, a first bearing rod, a first anti-backlash spring, a first anti-backlash bearing and a second anti-backlash bearing; the first positioning rod is located in the zoom slider and is vertically arranged with the first bearing rod, and one end of the first bearing rod is fixedly connected with the first positioning rod; the end of the zoom slider has a first boss extending vertically outward, and the other end of the first bearing rod extends out along the inner hole of the first boss; the first anti-backlash spring is sleeved on the first positioning rod, the first anti-backlash bearing is mounted on the first boss, and the second anti-backlash bearing is mounted on the extended section of the first bearing rod; the first anti-backlash spring is used to cause radial misalignment between the first anti-backlash bearing and the second anti-backlash bearing; The compensating slider group includes a compensating slider, a second positioning rod, a second bearing rod, a second anti-backlash spring, a third anti-backlash bearing and a fourth anti-backlash bearing; the second positioning rod is located in the compensating slider and is vertically arranged with the second bearing rod, and one end of the second bearing rod is fixedly connected with the second positioning rod; the end of the compensating slider has a second boss extending vertically outward, and the other end of the second bearing rod extends out along the inner hole of the second boss; the third anti-backlash spring is sleeved on the second positioning rod, the third anti-backlash bearing is mounted on the second boss, and the fourth anti-backlash bearing is mounted on the extended section of the second bearing rod; the second anti-backlash spring is used to cause radial misalignment between the third anti-backlash bearing and the fourth anti-backlash bearing; The zoom drive group is mounted on the top surface of the base and is arranged parallel to the side of the guide group; the zoom drive assembly includes a zoom motor assembly, a first zoom gear, a second zoom gear, a cam bracket and a cam rod mounted on the cam bracket, and the side wall of the cam rod is provided with a conjugate relationship between a zoom curve groove and a compensation curve groove designed according to optical principles, the groove width of the zoom curve groove is equal to the outer diameter of the first anti-backlash bearing and the second anti-backlash bearing, and the groove width of the compensation curve groove is equal to the outer diameter of the third anti-backlash bearing and the fourth anti-backlash bearing; The first zoom gear is coaxially mounted on one end of the cam rod, and the second zoom gear is coaxially mounted on the output end of the zoom motor assembly; the second zoom gear can reliably mesh with the first zoom gear for transmission; The first and second anti-backlash bearings of the zoom slider group are inserted into the zoom curve groove of the cam rod, and the third and fourth anti-backlash bearings of the compensation slider group are inserted into the compensation curve groove of the cam rod; the cam rod can rotate under the drive of the zoom motor, so that the radial misalignment between the first and second anti-backlash bearings can be eliminated under the squeezing action of the wall of the zoom curve groove, and the radial misalignment between the third and fourth anti-backlash bearings can be eliminated under the squeezing action of the wall of the compensation curve groove.

2. The lens continuous zoom mechanism according to claim 1, characterized in that: It also includes a zoom limit assembly, which is used to calibrate the zoom starting position and zoom stroke of the lens; The zoom limit assembly includes a switch block, a first switch group and a second switch group; the first switch group and the second switch group are respectively fixed at two ends of the top surface of the base and are located between the first pre-loaded slide rail and the second pre-loaded slide rail; the distance between the first switch group and the second switch group is determined according to the zoom limit travel of the lens; The switch block is installed at the bottom of the magnification slider and can contact the first switch group or the second switch group. When the switch block touches the first switch group, the measured large field of view value of the lens is greater than the large field of view value required by the lens technical indicators; when the switch block touches the second switch group, the measured small field of view value of the lens is less than the small field of view value required by the lens technical indicators.

3. The lens continuous zoom mechanism according to claim 1 or 2, characterized in that: It also includes a zoom lens group adjustment shim and a compensating lens group adjustment shim; The zoom lens group is installed in the central mounting hole on the top of the zoom lens group bracket through the zoom lens group adjustment gasket; the compensation lens group is installed in the central mounting hole on the top of the compensation lens group bracket through the compensation lens group adjustment gasket; The variable magnification lens group adjustment gasket and the compensating lens group adjustment gasket are used to adjust the distance between the variable magnification lens group and the compensating lens group so that the installation positions of the variable magnification lens group and the compensating lens group meet the optical design requirements.

4. The lens continuous zoom mechanism according to claim 3, characterized in that: The first pre-stressed slide rail comprises a first rail and a first slider installed on the first rail, and the first rail and the first slider have a pre-stress between them; The second pre-stressed slide rail comprises a second rail and a second slider installed on the second rail, and the second rail and the second slider have a pre-stress between them; Both ends of the zoom slider and the compensating slider are respectively fixed to the top surfaces of the first slider and the second slider, and the bottom surface of the zoom slider and the bottom surface of the compensating slider are completely in contact with the top surfaces of the first slider and the second slider; The variable magnification slider and the compensation slider can slide along the first track and the second track driven by the first slider and the second slider.

5. The lens continuous zoom mechanism according to claim 4, characterized in that: The zoom lens group bracket is vertically fixed to the middle of the top surface of the zoom slider, and the top surface of the zoom slider and close to one end of the zoom drive group has a first protrusion extending vertically upward, and the first protrusion is provided with a first step blind hole along the axis direction of the central mounting hole at the top of the zoom lens group bracket, the first positioning rod and the first anti-backlash spring are installed in the first step blind hole, and the two ends of the first anti-backlash spring are limited between the step surface of the first step blind hole and the step surface of the first positioning rod; The first boss extends outward perpendicularly to the side wall of the first protrusion, and the inner hole of the first boss is a first waist hole; the first bearing rod is located in the first waist hole, and the first bearing rod is threadedly connected to the first positioning rod; The compensation lens group bracket is vertically fixed to the middle of the top surface of the compensation slider, and the top surface of the compensation slider and close to one end of the zoom drive group has a second protrusion extending vertically upward, and the second protrusion is provided with a second step blind hole along the axis direction of the central mounting hole at the top of the compensation lens group bracket, and the second positioning rod and the second backlash elimination spring are installed in the second step blind hole, and the two ends of the second backlash elimination spring are limited between the step surface of the second step blind hole and the step surface of the second positioning rod; The second boss extends outward perpendicularly to the side wall of the second protrusion, and the inner hole of the second boss is a second waist hole; the second bearing rod is located in the second waist hole, and the second bearing rod is threadedly connected to the second positioning rod.

6. The lens continuous zoom mechanism according to claim 5, characterized in that: The first boss and the second boss are stepped shaft-shaped, the first anti-backlash bearing is coaxially mounted on the first boss and away from the shaft body of the first protrusion side wall by bonding, and the third anti-backlash bearing is coaxially mounted on the second boss and away from the shaft body of the second protrusion side wall by bonding; The second anti-backlash bearing and the fourth anti-backlash bearing are respectively mounted on the first bearing rod and the second bearing rod by bonding.

7. The lens continuous zoom mechanism according to claim 1 or 6, characterized in that: The two ends of the cam bracket are provided with support arms arranged vertically upward, and one end of the cam rod is installed on the support arm at one end of the cam bracket through a deep groove ball bearing; the cam rod is sleeved in the inner ring of the deep groove ball bearing and is freely matched with the inner ring of the deep groove ball bearing; The other end of the cam rod is mounted on the support arm at the other end of the cam bracket through a matching angular contact ball bearing; the cam rod is sleeved in the inner ring of the matching angular contact ball bearing and is fixedly connected to the inner ring of the matching angular contact ball bearing and is axially pressed by a third bearing pressure ring.

8. The lens continuous zoom mechanism according to claim 7, characterized in that: A first step through hole is formed on the support arm at one end of the cam bracket, and the deep groove ball bearing is installed in the small hole of the first step through hole; and further comprises a first bearing pressing ring, which is coaxially installed in the large hole of the first step through hole, and the end face of the first bearing pressing ring contacts the end face of the outer ring of the deep groove ball bearing to prevent the deep groove ball bearing from axially moving; A through hole is formed on the support arm at the other end of the cam bracket, a bearing sleeve is installed in the through hole, a second step through hole is formed in the bearing sleeve along the axis, and the paired angular contact ball bearing is installed in a small hole of the second step through hole; It also includes a second bearing pressure ring, which is located in the large hole of the second step through hole, and the end face of the second bearing pressure ring contacts the end face of the outer ring of the paired angular contact ball bearing to prevent the paired angular contact ball bearing from moving axially.

9. The lens continuous zoom mechanism according to claim 8, characterized in that: The zoom motor assembly comprises a zoom motor seat and a zoom motor, wherein the zoom motor seat is fixed on the support arm at the other end of the cam bracket and is close to the edge of the support arm; the zoom motor is mounted on the zoom motor seat; It also includes a gear pressing plate, through which the second zoom gear is axially fixedly connected to the output shaft of the zoom motor; The zoom motor is equipped with a high-precision encoder for real-time feedback of the focal length.

10. The lens continuous zoom mechanism according to claim 1, characterized in that: The transmission ratio of the first zoom gear and the second zoom gear is determined according to the zoom time required by the lens technical indicators; the larger the transmission ratio, the slower the zoom time, and the smaller the transmission ratio, the faster the zoom time.

Images