CN105372782B - A kind of linear drives optical focusing device - Google Patents

Abstract

A linear drive optical focus device belongs to the technical field of optical focus technology and relates to a linear drive optical focus device. The invention adopts an absolute multi-circle encoder as a feedback element, thereby improving the focusing precision, and adopts a linear bearing and a guide rail as a linear guide, thereby improving the guiding precision. The invention includes a connecting cylinder, a stepping motor, an absolute multi-turn encoder, a focusing mechanism, and left and right end covers. , Adjusting the pressure plate and the ball joint rod, one end of the lead screw is coaxially fixedly connected with the output shaft of the stepping motor, and the other end of the lead screw is connected with the absolute multi-turn encoder; In the center of the lens base, the focusing lens base has first, second and third supports; the second support is set on the first guide rail; the third support is set on the second guide rail.

Description

A Linear Drive Optical Focusing Device

technical field

The invention belongs to the technical field of optical focusing technology, and relates to a linear drive optical focusing device.

Background technique

During the actual work of the optical system, changes in the actual image plane position will be caused by changes in external factors such as temperature and observation distance, so it is necessary to focus during work. At present, the commonly used focusing methods are manual focusing and automatic focusing. Manual focusing is to achieve focusing by designing and rotating the focusing ring. The focus is achieved through the motor inside the lens barrel. At present, the ultrasonic motor is commonly used on the camera lens, which directly drives the lens to move axially, and then determines the position of the image plane through phase detection. The actual working automatic focusing system, because there is no independent ultrasonic motor drive device, needs to achieve focusing through the cooperation of ordinary stepping motors and intermediate transmission chains, the focusing accuracy is affected, and the cam or sleeve of the automatic focusing system The structure puts forward high requirements for matching accuracy, and temperature changes will affect the normal operation of the system, while the accuracy of existing feedback components (such as potentiometers, etc.) limits the focus step size, so the existing optical focus mechanism needs to be further improved. Improve the design.

Contents of the invention

In order to overcome the deficiencies of the prior art above, the present invention provides a linear drive optical focusing device, the focusing device uses an absolute multi-turn encoder as a feedback element, the focusing accuracy is improved, and a linear bearing and a cylindrical guide rail are used as Linear guide, guide accuracy can be improved.

In order to achieve the above purpose, the technical solution adopted in the present invention is: a linear drive optical focusing device, including a connecting cylinder, a stepping motor, an absolute multi-turn encoder, a focusing mechanism, left and right end caps, left and right ends The cover is respectively fixed on the left and right ends of the connecting cylinder. The focusing mechanism is composed of a lead screw, a focusing lens group, a focusing lens seat, a first guide rail, a second guide rail, an adjusting pressure plate and a ball joint rod. One end of the lead screw is connected to the The output shaft of the stepping motor is fixedly connected coaxially, and the other end of the lead screw is connected with the absolute multi-turn encoder through a coupling; 1. The second and third supports; the anti-backlash nut is set on the lead screw through the thread, the ball joint rod is fixedly connected with the anti-backlash nut, the adjusting pressure plate is fixed on the side of the first support, and the top of the first support It forms a groove with the adjusting pressure plate, and the ball head of the ball joint rod is set in the groove and above the screw; the second support is set on the first guide rail, and the two ends of the first guide rail are respectively fixed on the left and right end caps on; the third support is set on the second guide rail, and the two ends of the second guide rail are respectively fixed on the left and right end covers.

The center of the described leading screw, the center of the first guide rail and the center of the second guide rail are all arranged on the circle with the center of the focusing mirror seat as the center of the circle, the connecting line between the center of the leading screw and the described center of circle, the first The line connecting the center of the guide rail and the center of the circle, and the line connecting the center of the second guide rail and the center of the circle are 120° to each other.

An inner hole is arranged at the center of the focusing lens base, and the focusing lens group is coaxially arranged in the inner hole of the focusing lens base.

The second support of the focusing mirror base is set on the first guide rail through two linear bearings, a retaining ring for holes is arranged on the outside of the two linear bearings, and a bearing spacer is arranged between the two linear bearings .

An anti-rotation limit block is fixed on the third support of the focusing lens base, and a long hole is arranged on the anti-rotation limit block, and the second guide rail passes through the long hole, and the long hole The length direction is along the radial direction of the focusing lens group, and the width of the long hole is the same as the diameter of the second guide rail.

The absolute multi-turn encoder is fixed on the left end cover, the stepper motor is fixed on the right end cover, the left end of the lead screw passes through the left end cover to connect with the absolute multi-turn encoder, the left end of the lead screw A deep groove ball bearing is arranged between the head and the left end cover; the right end of the lead screw is coaxially fixedly connected with the output shaft of the stepping motor.

The cross-sections of the first and second guide rails are circular.

The lead screw is a precision lead screw.

Beneficial effects of the present invention:

In the linear drive optical focusing device of the present invention, since the absolute multi-turn shaft encoder is used as the feedback element, the focusing accuracy is improved, and the linear bearing and the guide rail are used as the linear guide to ensure high guide accuracy and avoid stagnation caused by high and low temperatures The damping is relieved due to the internal rolling friction of the linear bearing, and the connection between the anti-backlash nut and the focusing lens seat is connected by a ball joint rod to ensure the freedom of movement and prevent additional movement resistance torque, thereby improving the load capacity of the motor.

Description of drawings

Fig. 1 is the structural representation of linear drive optical focusing device of the present invention;

Fig. 2 is a rear view sectional view of Fig. 1;

Fig. 3 is a side sectional view of Fig. 1;

In the figure, 1—absolute multi-turn encoder, 2—coupling, 3—deep groove ball bearing, 4—left end cover, 5—connecting cylinder, 6—adjusting pressure plate, 7—ball joint rod, 8—adjustment Focus lens seat, 81—the first support, 82—the second support, 83—the third support, 84—groove, 9—focusing lens group, 10—anti-backlash nut, 11—right end cover, 12— Stepper motor, 13—press nail, 14—first guide rail, 15—linear bearing, 16—bearing spacer, 17—retaining ring for hole, 18—second guide rail; 19—anti-rotation limit block, 20—wire Bar, 21-strip hole.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 to 3, a linear drive optical focusing device includes a connecting cylinder 5, a stepping motor 12, an absolute multi-turn encoder 1, a focusing mechanism, and left and right end covers, and the left and right end covers are respectively fixed on the left and right ends of the connecting cylinder 5,

Focusing mechanism is made up of leading screw 20, focusing mirror group 9, focusing mirror seat 8, first guide rail 14, second guide rail 18, adjustment pressure plate 6 and ball joint rod 7, and one end of leading screw 20 is connected with stepper motor The output shaft of 12 is fixedly connected coaxially, and the other end of the lead screw 20 is connected with the absolute multi-turn encoder 1 through the shaft coupling 2; The seat 8 has first, second and third supports; the anti-backlash nut 10 is set on the lead screw 20 through threads, the ball joint rod 7 is fixedly connected with the anti-backlash nut 10, and the adjusting pressure plate 6 is fixed on the first support 81 side, the top of the first support 81 and the adjustment plate 6 form a groove 84, the ball head of the ball joint rod 7 is arranged in the groove 84, and is located above the lead screw 20; the second support 82 is set on the second On a guide rail 14, the two ends of the first guide rail 14 are respectively fixed on the left and right end caps; the third support 83 is sleeved on the second guide rail 18, and the two ends of the second guide rail 18 are respectively fixed on the left and right end caps.

The center of the described leading screw 20, the center of the first guide rail 14 and the center of the second guide rail 18 are all arranged on the circle with the center of the focusing lens holder 8 as the center of the circle, the center of the leading screw 20 and the described center of circle The connection line, the connection line between the center of the first guide rail 14 and the center of the circle, and the connection line between the center of the second guide rail 18 and the center of the circle are 120° mutually.

An inner hole is arranged at the center of the focusing lens base 8, and the focusing lens group 9 is coaxially arranged in the inner hole of the focusing lens base 8, and the shaft hole is passed between the focusing lens group 8 and the focusing lens base 9 The radial position is ensured by cooperation, and the axial position is ensured by pressing the threaded pressure ring.

The second support 82 of the focusing mirror base 8 is set on the first guide rail 14 through two linear bearings 15, and a retaining ring 17 for a hole is arranged on the outside of the two linear bearings 15, and the two linear bearings 15 A bearing spacer 16 is arranged between them.

An anti-rotation stop block 19 is fixed on the third support 83 of the focusing lens base 8, and a long hole 21 is arranged on the anti-rotation stop block 19, and the second guide rail 18 passes through the long bar Holes 21, the length direction of the long hole 21 is along the radial direction of the focusing lens group 9, to eliminate the over-positioning of the focusing lens group 9, the width of the long hole 21 is the same as the diameter of the second guide rail 18, ensuring that the third The support 83 does not swing in the circumferential direction, thereby realizing the anti-rotation function of the anti-rotation limiting block 19 .

The absolute multi-turn encoder 1 is fixed on the left end cover 4, the stepper motor 12 is fixed on the right end cover 11, and the left end of the screw 20 passes through the left end cover 4 and the absolute multi-turn encoder 1 connection, a deep groove ball bearing 3 is arranged between the left part of the leading screw 20 and the left end cover 4; the right end of the leading screw 20 is coaxially fixedly connected with the output shaft of the stepping motor 12.

The cross-sections of the first and second guide rails are circular.

The lead screw 20 is a precision lead screw.

The step length of the stepping motor 12 is 0.0015 mm, the step angle is 1.8°, and the pulse frequency is 1000 pps; the resolution of the absolute multi-turn encoder 1 is 2 to ¹⁵ bits.

The specific working process of this embodiment will be described below in conjunction with the accompanying drawings.

As shown in Figures 1 to 3, turn on the stepping motor 12, the stepping motor 12 starts to rotate, and simultaneously drives the lead screw 20 to rotate in the same direction, thereby driving the anti-backlash nut 11 to move linearly along the lead screw 20, because the anti-backlash nut 11 Fixedly connected with the ball joint rod 7, the ball joint rod 7 also moves linearly along the lead screw 20, and at the same time drives the focusing lens base 8 to perform linear motion along the lead screw 20; during this process, the linear bearing 15 and the first The guide rail 14 acts as a linear guide, and the anti-rotation limit block 19 prevents the focusing lens holder 8 from swinging in the circumferential direction;

Since the left end of the screw 20 is connected to the input shaft of the absolute multi-turn encoder 1 through the coupling 2, and the left part of the screw 20 is radially supported by the deep groove ball bearing 3, the absolute multi-turn encoder 1 records The rotation angle of the lead screw 20 is linearly corresponding to the axial position of the focusing lens group 9, and after the power is cut off, the absolute multi-turn encoder 1 can also retain the record of the current position, and the resolution of the absolute multi-turn encoder 1 The ratio can be adjusted according to the requirement of focusing precision.

The final position of the theoretical image plane is determined by detecting the imaging quality of the image plane, and the position information corresponding to the absolute multi-turn encoder 1 is the theoretical focus position. When the target distance changes or the ambient temperature changes and the focal length of the focusing lens group 9 changes, the stepper motor 12 increases or decreases the input pulse on the original basis to change the step angle, so that the focusing lens group 9 takes place before and after. Move to achieve focus, get a new theoretical image plane position, and the absolute multi-turn encoder 1 simultaneously records this position as the new focus theoretical position, so as to realize optical focus under different conditions.

Claims (8)

1. a kind of linear drives optical focusing device, it is characterised in that including connecting cylinder, stepper motor, absolute type multi-turn coding Device, focus adjusting mechanism and left and right end cap, left and right end cap are separately fixed at the left and right end of connecting cylinder, and focus adjusting mechanism is by leading screw, focusing Microscope group, focusing microscope base, the first guide rail, the second guide rail, adjustment pressing plate and ball head connecting rod composition, one end of leading screw and stepper motor Output shaft is fixedly and coaxially connected, and the other end of leading screw is connected by shaft coupling with absolute type encoder；Focusing microscope group is coaxial The center of focusing microscope base is arranged on, focusing lens seat tool has first, second, third bearing；The gap that disappears nut is by thread set in silk On thick stick, ball head connecting rod is fixedly connected with the gap nut that disappears, and adjustment pressing plate is fixed on the sidepiece of the first bearing, the top of the first bearing with Adjust pressing plate and form groove, the bulb of ball head connecting rod is arranged in groove, positioned at the top of leading screw；Second bearing is sleeved on first On guide rail, the both ends of the first guide rail are separately fixed on left and right end cap；Three abutments are sleeved on the second guide rail, the second guide rail Both ends be separately fixed on left and right end cap.

2. linear drives optical focusing device according to claim 1, it is characterised in that the center of described leading screw, first The center of guide rail and the center of the second guide rail are arranged at using the center for microscope base of focusing as on the circle in the center of circle, the center of leading screw and institute Center and the line in the described center of circle, the center of the second guide rail and the described center of circle of the line in the center of circle stated, the first guide rail Line is in 120 °.

3. linear drives optical focusing device according to claim 1, it is characterised in that in described focusing microscope base The heart is provided with endoporus, and focusing microscope group is coaxially disposed in the endoporus of focusing microscope base.

4. linear drives optical focusing device according to claim 1, it is characterised in that the second of described focusing microscope base Bearing is sleeved on the first guide rail by two linear bearings, hole back-up ring is provided with the outside of two linear bearings, two Bearing spacer is provided between individual linear bearing.

5. linear drives optical focusing device according to claim 1, it is characterised in that the of described focusing microscope base Anti-rotation limited block is fixed with three abutments, strip hole is provided with anti-rotation limited block, second guide rail passes through strip hole, long Radial direction of the length direction in bar hole along focusing microscope group, the width of strip hole are identical with the diameter of the second guide rail.

6. linear drives optical focusing device according to claim 1, it is characterised in that described absolute type multi-turn coding Device is fixedly installed on left end cap, and described stepper motor is fixedly installed on right end cap, the left end of leading screw through left end cap with Absolute type encoder is connected, and deep groove ball bearing is provided between the left part and left end cap of leading screw；The right-hand member of leading screw and stepping The output shaft of motor is fixedly and coaxially connected.

7. linear drives optical focusing device according to claim 1, it is characterised in that first, second described guide rail Cross section is circle.

8. linear drives optical focusing device according to claim 1, it is characterised in that described leading screw uses accurate silk Thick stick.