A simple, small and cheap parfocal device

Abstract

The utility model relates to a simple, small and cheap parfocal device, comprising a lens barrel, a photosensitive barrel and a guide barrel, wherein the lens barrel is sleeved on one end of the photosensitive barrel, and the lens barrel and the photosensitive barrel are both arranged inside the guide barrel; the guide barrel is provided with a first spiral groove with equal pitch, the lens barrel is provided with a first convex shaft, and the first convex shaft is slidably connected with the first spiral groove; the lens barrel is provided with a second spiral groove with non-equal pitch, the photosensitive barrel is provided with a second convex shaft, and the second convex shaft is slidably connected with the second spiral groove; a third convex shaft is provided at one end of the photosensitive barrel away from the second convex shaft, the guide barrel is provided with a transverse guide groove, and the third convex shaft is slidably connected with the transverse guide groove. The utility model only uses an ordinary fixed focal length lens and a photosensitive linkage part, so that when the magnification is changed, the photosensitive element is always in the image plane to obtain a clear image and achieve parfocality, does not require a complex variable focus optical lens group, has a simple structure, is low in price, and is conducive to popularization and use.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging, in particular to a simple, small and cheap parfocal device. Background Art

[0002] Parfocality means that during the zoom process, when switching from one focal length to another, the imaging position of the object remains unchanged, and the image clarity can be maintained without the user having to refocus. This is very useful in certain application scenarios that require rapid switching of viewing angles, such as when photographing fast-moving objects or quickly switching between objective lenses of different magnifications to observe samples under a microscope.

[0003] The design of the parfocal device usually involves a complex variable-focus optical lens group with a long lens barrel, and there are multiple expensive and complex optical lenses inside the lens barrel. For example, the continuous zoom microscope disclosed by Chinese patent publication number CN206532031U adjusts the connection magnification through the zoom hand wheel, and also needs to focus through the focusing hand wheel to make the object image clear. The objective lens unit is composed of a first zoom lens group, a fixed lens group, a second zoom lens group, etc. The zoom hand wheel adjusts the first zoom lens group and the second zoom lens group to move up and down. It can be seen that the optical lens structure is very complicated.

[0004] However, the existing parfocal devices often have high costs due to their complex optical structures. Therefore, how to simplify the optical design of the parfocal device and reduce the manufacturing cost while maintaining its high performance has become an important issue that needs to be solved in the field of optical equipment manufacturing. Utility Model Content

[0005] In order to overcome the problem that the existing parfocal devices often lead to high costs due to their complex optical structures, the utility model provides a simple, small and low-cost parfocal device.

[0006] The technical solution of the utility model is as follows:

[0007] A simple, small and inexpensive parfocal device comprises a lens barrel, a photosensitive cylinder and a guide cylinder, wherein the lens barrel is sleeved on one end of the photosensitive cylinder, and the lens barrel and the photosensitive cylinder are both arranged inside the guide cylinder; the guide cylinder is provided with a first spiral groove with equal pitch, the lens barrel is provided with a first convex shaft, and the first convex shaft is slidably connected to the first spiral groove; the lens barrel is provided with a second spiral groove with non-equal pitch, the photosensitive cylinder is provided with a second convex shaft, and the second convex shaft is slidably connected to the second spiral groove; a third convex shaft is provided at one end of the photosensitive cylinder away from the second convex shaft, the guide cylinder is provided with a transverse guide groove, and the third convex shaft is slidably connected to the transverse guide groove.

[0008] The utility model according to the above scheme is characterized in that an imaging lens is provided at one end of the lens barrel away from the first convex axis; and a photosensitive element is provided at one end of the photosensitive barrel close to the second convex axis.

[0009] The utility model according to the above scheme is characterized in that the pitch of the second spiral groove gradually increases from one end of the lens to the other end, and the photosensitive tube can rotate relative to the lens tube through the second spiral groove and move horizontally in the guide tube.

[0010] The utility model according to the above scheme is characterized in that a spring is provided between the end of the lens barrel and the end of the photosensitive barrel, one end of the spring abuts against the outer end surface of the lens barrel, and the other end abuts against the inner end surface of the columnar portion with a larger diameter on the photosensitive barrel.

[0011] The utility model according to the above scheme is characterized in that an adjustment ring is provided on the outside of the first spiral groove of the guide cylinder, and the adjustment ring rotates around the axis of the guide cylinder; the inner side wall of the adjustment ring is provided with a linear guide groove parallel to the axis, and the first cam passes through the first spiral groove from the inside to the outside and is slidably connected with the linear guide groove.

[0012] Furthermore, the guide tube is provided with two centrally symmetrical first spiral grooves, the lens tube is provided with two symmetrical first convex shafts, and the two opposite inner side walls of the adjustment ring are each provided with a linear guide groove, and the two first convex shafts slide in the first spiral groove and the linear guide groove on the corresponding sides.

[0013] Furthermore, the outer peripheral surface of the adjustment ring is provided with stripes for increasing the surface roughness.

[0014] Furthermore, the guide sleeve is provided with a front end housing and a rear end housing, the front end housing is located on a side of the adjustment ring close to the object, and the rear end housing is located on the other side of the adjustment ring.

[0015] The utility model according to the above scheme is characterized in that the lens barrel is provided with two centrally symmetrical second spiral grooves, and the photosensitive barrel is provided with two symmetrical second convex shafts, which slide in the second spiral grooves on the corresponding sides.

[0016] The utility model according to the above scheme is characterized in that the guide cylinder is provided with two symmetrical transverse guide grooves, and the photosensitive cylinder is provided with two symmetrical third convex shafts, and slides in the transverse guide grooves on the corresponding sides.

[0017] The utility model according to the above scheme has the following beneficial effects:

[0018] The utility model utilizes a first convex shaft and a first spiral groove to adjust the axial position of the lens barrel in the guide barrel, thereby changing the distance between the imaging lens and the object, and further changing the magnification of the object, and the first spiral groove is continuous, so that the magnification of the imaging lens can be adjusted to be a continuously variable adjustment; and then utilizes a second convex shaft and a second spiral groove to realize the photosensitive barrel rotating relative to the lens barrel along the second spiral groove and changing its axial position in the guide barrel;

[0019] The utility model uses a combined groove structure of a first spiral groove with equal pitch and a second spiral groove with non-equal pitch to realize that after the photosensitive tube automatically follows the position change of the lens tube, the photosensitive chip always remains at the imaging position of the object to obtain a clear image without manual focusing. It can be seen that the utility model only uses an ordinary fixed-focal-length lens plus a photosensitive linkage part, so that when the magnification is changed, the light-sensitive chip is always in the image plane to obtain a clear image and achieve parfocus, and does not require a complex variable-focus optical lens group. The structure is simple and the price is low, which is conducive to popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the utility model;

[0021] Figure 2 It is a structural exploded diagram of the utility model;

[0022] Figure 3 This is the structural exploded view after removing the outer shell;

[0023] Figure 4 It is a structural schematic diagram of the guide cylinder;

[0024] Figure 5 It is a structural schematic diagram of the lens barrel;

[0025] Figure 6 Schematic diagram of the structure of the adjustment ring.

[0026] In the figure,

[0027] 1. Adjustment components;

[0028] 11. guide cylinder; 111. first spiral groove; 112. transverse guide groove;

[0029] 12. Adjusting ring; 121. Linear guide groove;

[0030] 2. Lens assembly;

[0031] 21, lens barrel; 211, first convex shaft; 212, second spiral groove;

[0032] 22. Imaging lens;

[0033] 3. Photosensitive components;

[0034] 31, photosensitive cylinder; 311, second convex shaft; 312, third convex shaft;

[0035] 32. Photosensitive chip;

[0036] 33. Spring;

[0037] 4. Outer shell;

[0038] 41. Front end housing;

[0039] 42. Rear end housing. DETAILED DESCRIPTION

[0040] In order to better understand the purpose, technical solution and technical effect of the utility model, the utility model is further explained in conjunction with the drawings and embodiments below. It should be noted that similar numbers and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, it is stated that the embodiments described below are only used to explain the utility model and are not used to limit the utility model.

[0041] It should be noted that the terms "first", "second" and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Several" means two or more, unless otherwise clearly and specifically defined.

[0042] Embodiment 1

[0043] like Figure 1 As shown, a simple, small and cheap parfocal device includes an adjustment component 1, a lens component 2 and a photosensitive component 3. The adjustment component 1 is connected to the lens component 2 and is used to control the rotation of the lens component 2. The lens component 2 has an imaging lens. When the lens component 2 rotates, the distance from the imaging lens to the object can be changed, that is, the object distance can be changed.

[0044] In this embodiment, the adjustment assembly 1 includes a guide cylinder 11, and the lens assembly 2 includes a lens barrel 21, and an imaging lens is fixedly mounted at one end of the lens barrel 21. The guide cylinder 11 is sleeved on the outside of the lens barrel 21, and the guide cylinder 11 is provided with a first spiral groove 111 with equal pitch, and the lens barrel 21 is provided with a first convex shaft 211, and the first convex shaft 211 passes through the first spiral groove 111 from the inside of the guide cylinder 11 and slides in the first spiral groove 111. The first convex shaft 211 can be moved from the outside of the guide cylinder 11 to slide in the first spiral groove 111, thereby controlling the lens assembly 2 to rotate in the guide cylinder 11. Under the action of the trajectory of the first spiral groove 111, the lens assembly 2 rotates while moving laterally along the axial direction of the guide cylinder 11, thereby changing the distance between the imaging lens and the end of the guide cylinder 11, and also changing the distance between the imaging lens and the object. In actual operation, when the first convex shaft 211 is moved to control the rotation of the lens barrel 21 and the imaging lens is "retracted" into the guide barrel 11 and away from the barrel end, the object distance increases; conversely, when the first convex shaft 211 is moved to control the rotation of the lens barrel 21 and the imaging lens is close to the end of the guide barrel 11, the object distance decreases.

[0045] The pitch of the first spiral groove 111 is equal, so when the lens barrel 21 rotates a unit angle in the guide barrel 11 through the first convex shaft 211, the lens barrel 21 moves the same unit distance laterally in the guide barrel 11. Since the first spiral groove 111 is continuous, the magnification of the imaging lens can be adjusted continuously.

[0046] The photosensitive component 3 is linked to the lens component 2 and moves relative to the lens component 2 as the lens component 2 rotates. The photosensitive component 3 has a photosensitive chip 32. When the photosensitive component 3 and the lens component 2 move relative to each other, the distance between the photosensitive chip 32 and the imaging lens is changed, and the photosensitive chip 32 is always located at the image plane of the object after passing through the imaging lens, so that the photosensitive chip 32 can clearly capture the image of the object. Using the imaging relationship between the object distance, the focal length of the imaging lens, and the image distance, and based on the known object distance and the known focal length of the imaging lens, the position of the photosensitive chip 32 after movement can be determined.

[0047] In this embodiment, the photosensitive assembly 3 includes a photosensitive cylinder 31, one end of which is inserted into the lens barrel 21, and the lens barrel 21 and the photosensitive cylinder 31 are both arranged inside the guide barrel 11, and can rotate in the guide barrel 11. The lens barrel 21 is provided with a second spiral groove 212, and the photosensitive cylinder 31 is provided with a second convex shaft 311, and the second convex shaft 311 slides in the second spiral groove 212; the end of the photosensitive cylinder 31 away from the second convex shaft 311 is provided with a third convex shaft 312, and the guide barrel 11 is provided with a transverse guide groove 112, and the third convex shaft 312 is slidably connected to the transverse guide groove 112.

[0048] The second convex shaft 311 cooperates with the second spiral groove 212 to realize the rotation of the photosensitive cylinder 31 relative to the lens barrel 21, and the third convex shaft 312 cooperates with the transverse guide groove 112 to realize that the photosensitive cylinder 31 can only move transversely relative to the guide cylinder 11, thereby realizing that during the rotation of the photosensitive cylinder 31 and the lens barrel 21, the photosensitive cylinder 31 rotates relative to the lens barrel 21 along the trajectory of the second spiral groove 212, when the lens barrel 21 rotates forward, the photosensitive cylinder 31 rotates reversely, and when the lens barrel 21 rotates reversely, the photosensitive cylinder 31 rotates forward; and the two move relative to each other during rotation, so that the lens barrel 21 and the photosensitive cylinder 31 approach each other or move away from each other.

[0049] The second spiral groove 212 has a non-uniform pitch. Specifically, the pitch of the second spiral groove 212 at one end close to the photosensitive cylinder 31 is larger, and the pitch of the second spiral groove 212 at one end away from the photosensitive cylinder 31 is smaller. The photosensitive cylinder 31 rotates and moves relative to the lens barrel 21 with the help of the second spiral groove 212. When the second convex shaft 311 slides at a wider pitch, the photosensitive cylinder 31 moves a larger distance when rotating; when the second convex shaft 311 slides at a narrower pitch, the photosensitive cylinder 31 moves a smaller distance when rotating. Therefore, when the imaging lens 22 of the lens barrel 21 and the photosensitive element of the photosensitive cylinder 31 are far apart, the photosensitive cylinder 31 moves a larger distance when rotating; when the imaging lens 22 of the lens barrel 21 and the photosensitive element of the photosensitive cylinder 31 are close, the photosensitive cylinder 31 moves a smaller distance when rotating.

[0050] like Figure 4 and Figure 5 As shown, in a preferred embodiment, the guide tube 11 is provided with two centrally symmetrical first spiral grooves 111, the lens barrel 21 is provided with two symmetrical first convex shafts 211, the lens barrel 21 is provided with two centrally symmetrical second spiral grooves 212, and the photosensitive tube 31 is provided with two symmetrical second convex shafts 311. In this way, the lens barrel 21 slides in the first spiral grooves 111 on the corresponding side by using the first convex shafts 211 on both sides to ensure the stability of the lens barrel 21 during rotation; similarly, the photosensitive tube 31 slides in the second spiral grooves 212 on the corresponding side by using the second convex shafts 311 on both sides to ensure the stability of the photosensitive tube 31 when rotating at the end of the lens barrel 21.

[0051] In a preferred embodiment, the guide cylinder 11 is provided with two symmetrical transverse guide grooves 112, and the photosensitive cylinder 31 is provided with two symmetrical third protrusions 312. The third protrusions 312 on both sides of the photosensitive cylinder 31 slide in the transverse guide grooves 112 on the corresponding sides, so that the photosensitive cylinder 31 moves smoothly in the guide cylinder 11.

[0052] The photosensitive cylinder 31 is composed of two cylinders with different diameters, including a cylinder with a smaller diameter and a cylinder with a larger diameter. One end of the cylinder with a smaller diameter is connected to the lens barrel 21, and the second protruding shaft 311 is arranged on the cylinder with a smaller diameter; the cylinder with a larger diameter is connected to the guide cylinder 11, and the third protruding shaft 312 is arranged on the cylinder with a larger diameter. In this way, the photosensitive cylinder 31 is compatible with the lens barrel 21 and the guide cylinder 11 at the same time. One end is connected to the lens barrel 21 by the cylinder with a small diameter, so that the second protruding shaft 311 is stably inserted into the second spiral groove 212; the other end is connected to the guide cylinder 11 by the cylinder with a large diameter, so that the third protruding shaft 312 is stably inserted into the transverse guide groove 112. Therefore, the photosensitive tube 31 can be stably connected to the lens barrel 21 and the guide tube 11 at the same time, ensuring close cooperation between the various components. When the lens barrel 21 moves, the photosensitive tube 31 moves accordingly, and the two move stably in the guide tube 11 according to the predetermined trajectories of the first spiral groove 111 and the second spiral groove 212.

[0053] like Figure 6 As shown, in this embodiment, the adjustment assembly 1 also includes an adjustment ring 12, which is sleeved on the outside of the first spiral groove 111 of the guide cylinder 11 and rotates around the axis of the guide cylinder 11; the inner wall of the adjustment ring 12 is provided with a linear guide groove 121 parallel to the axis, and the first protruding shaft 211 passes through the first spiral groove 111 from the inside to the outside and is slidably connected with the linear guide groove 121. The linear guide groove 121 of the adjustment ring 12 is used to move the first protruding shaft 211, and the first protruding shaft 211 can be self-adapted to the lateral displacement of the first protruding shaft 211, so as to avoid interfering with the lateral movement of the lens barrel 21 in the guide cylinder 11. The specific operation is: rotate the adjustment ring 12, and use the linear guide groove 121 on the inner wall of the adjustment ring 12 to push the first protruding shaft 211 to slide in the first spiral groove 111, and the first protruding shaft 211 moves along the linear guide groove 121 while sliding in the first spiral groove 111. This structure cleverly transforms the complex route of moving the first convex shaft 211 around the guide cylinder 11 and along the first spiral groove 111 into rotating the adjustment ring 12, the operation method is simple, and the operation structure is stable.

[0054] In this embodiment, the guide cylinder 11 is also sleeved with a front end housing 41 and a rear end housing, the front end housing 41 is located on the side of the adjusting ring 12 close to the object, and the rear end housing is located on the other side of the adjusting ring 12. The rear side of the front end housing 41 is connected to the front side of the adjusting ring 12, and the front side of the rear end housing is connected to the rear side of the adjusting ring 12, so as to limit the position of the adjusting ring 12 in the axial direction of the guide cylinder 11. It can be seen that the gap between the front end housing 41 and the rear end housing defines the installation area of ​​the adjusting ring 12, and the adjusting ring 12 can only rotate within the installation area. In addition, since the front end housing 41, the adjusting ring 12 and the rear end housing are successively connected on the guide cylinder 11, the guide cylinder 11 can be covered as a whole to form a protective cover, which is conducive to increasing the service life of the entire device.

[0055] Embodiment 2

[0056] A simple, small and cheap parfocal device comprises an adjustment assembly 1, a lens assembly 2 and a photosensitive assembly 3, and the rest of the structure is the same as that of the first embodiment, except that: on the basis of the above structure, a spring 33 is provided between the end of the lens barrel 21 and the end of the photosensitive barrel 31, one end of the spring 33 abuts against the outer end surface of the lens barrel 21, and the other end abuts against the inner end surface of the cylindrical part with a larger diameter on the photosensitive barrel 31. The spring 33 applies elastic force to the lens barrel 21 and the photosensitive barrel 31 on both sides respectively, and under the action of the elastic force, the second convex shaft 311 of the photosensitive barrel 31 abuts against the side of the second spiral groove 212 close to the photosensitive barrel 31. In this way, even if the second convex shaft 311 and the second spiral groove 212 are not well matched due to processing, the second convex shaft 311 will not shake in the second spiral groove 212 due to the large matching clearance, and shaking between the lens barrel 21 and the photosensitive barrel 31 can be avoided; when the second convex shaft 311 moves to any point on the second spiral groove 212, the relative distance between the lens barrel 21 and the photosensitive barrel 31 is a unique value. Therefore, the image distance from the photosensitive chip 32 to the imaging lens has a unique value, which improves the adjustment precision and accuracy.

[0057] In order to better understand the implementation principle of the first spiral groove and the second spiral groove of the present scheme, the following is a method for implementing the above-mentioned simple, small and inexpensive parfocal device, in which the object distance u, the focal length f of the imaging lens and the image distance v satisfy the imaging formula: 1 / f=1 / u+1 / v, and the object distance is less than twice the focal length of the imaging lens and greater than 1 times the focal length of the imaging lens, that is, f<u<2f. The distance from the imaging lens to the object satisfies this condition, ensuring that the object forms an enlarged real image after passing through the imaging lens so as to be captured by the photosensitive element.

[0058] When in use, the position of the stage remains unchanged, that is, the position of the object remains unchanged. When the object distance is increased, a smaller magnification is obtained, and the photosensitive chip is moved closer to the imaging lens to obtain a clear image; when the object distance is decreased, a larger magnification is obtained, and the photosensitive chip is moved away from the imaging lens to obtain a clear image.

[0059] Based on the imaging formula, the position of the photosensitive chip after each change can be determined. When the position of the photosensitive chip changes, the image distance between the photosensitive chip and the imaging lens is equal to the product of the object distance and the focal length divided by the difference between the object distance and the focal length. The derivation of this relationship is as follows:

[0060]

[0061]

[0062]

[0063] Therefore, after the specifications of the imaging lens are selected and its focal length is known, the structure of the first spiral groove can be designed first, and the second spiral groove can be designed based on the structure of the first spiral groove.

[0064] When designing the first spiral groove, it should be satisfied that: when the first convex axis of the lens barrel slides from the starting point to the end point of the first spiral groove, the lens barrel should be able to complete a lateral shift of at least 2 times the focal length. If the pitch is small, the first spiral groove is processed more times on the guide tube, and the lens barrel rotates more times, but it is beneficial to improve the fineness of the object distance adjustment. On the contrary, if the pitch is large, the first spiral groove is processed less times, and the lens barrel rotates less times to complete the lateral shift distance requirement of the lens barrel, and the adjustment accuracy is poor, but the magnification can be changed quickly and the adjustment is fast.

[0065] In a specific embodiment, the total angle of rotation of the lens barrel for a transverse displacement of 2 times the focal length is 300 degrees. It can be determined that the lens barrel has only rotated 5 / 6 of a circle along the first spiral groove and can satisfy the displacement 2f. The processing pitch of the first spiral groove is equal to the total transverse displacement divided by the number of circles, that is, 2f÷5 / 6=2.4f. After determining the structure of the first spiral groove, the second spiral groove can be obtained with the help of the optical bench. It should be noted that the specific steps for obtaining the processing trajectory of the second spiral groove when the object plane is at the zero point position of the horizontal axis of the optical bench are as follows:

[0066] The first spiral groove is divided into several equal parts. Each time the first convex shaft moves a unit segment in the first spiral groove, the lens barrel rotates a unit angle, and the imaging lens moves a fixed distance laterally on the axis of the guide tube; the lateral position X1 from the imaging lens to the object / object plane is recorded each time, that is, X1 represents the distance from the front end surface of the imaging lens to the object plane. The lens on the optical stand is moved accordingly according to the recorded lateral position. Each time the lens on the stand is moved, the position of the image screen needs to be adjusted so that a clear image appears on the image screen; and the lateral position X2 from the image screen to the imaging lens after adjustment is recorded, that is, X2 represents the distance from the front end surface of the imaging lens to the photosensitive surface.

[0067] The coordinate position of the second convex shaft 311 on the axis of the lens barrel 2 is determined according to the recorded multiple X2 values, and one coordinate position corresponds to a track point on the second spiral groove 212, and the angle difference between two adjacent track points is a unit angle of the lens barrel 21 rotation, so that the processing track of the second spiral groove 212 can be obtained. For example, the lens barrel 21 rotates a unit angle of 17°, starting from the end of the second spiral groove 212 near the photosensitive barrel, every 17° rotation, a track point is marked according to the recorded X2 value, and the second spiral groove can be processed according to the measured track point to obtain.

[0068] Lens position X1 Image screen position X2 Lens position X1 Image screen position X2 Lens position X1 Image screen position X2 30 35.85 37 31.55 44 29.30 31 34.85 38 31.20 45 29.00 32 34.15 39 30.85 46 28.75 33 33.50 40 30.50 47 28.55 34 32.90 41 30.15 48 28.35 35 32.40 42 29.85 49 28.15 36 31.95 43 29.60 50 28.10

[0069] In summary, the design steps of the first spiral groove and the second spiral groove are:

[0070] Step 1: First determine the total rotation angle of the lens barrel and the focal length of the lens;

[0071] Step 2, calculating the pitch of the first spiral groove according to the total lateral displacement distance of the lens barrel;

[0072] Step 3, dividing the first spiral groove into equal segments, and obtaining a unit angle of rotation of the lens barrel within the unit segment;

[0073] Step 4: Use the optical bench to measure the position data of multiple groups of lenses and image screens on the bench;

[0074] Step 5: Determine the machining trajectory of the second spiral groove based on the unit angle of rotation of the lens barrel and the measured multiple image screen positions.

[0075] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A simple, small and cheap parfocal device, characterized in that: It comprises a lens barrel, a photosensitive barrel and a guide barrel, wherein the lens barrel is sleeved on one end of the photosensitive barrel, and the lens barrel and the photosensitive barrel are both arranged inside the guide barrel; The guide tube is provided with a first spiral groove with equal pitch, the lens tube is provided with a first convex shaft, and the first convex shaft is slidably connected to the first spiral groove; the lens tube is provided with a second spiral groove with non-equal pitch, the photosensitive tube is provided with a second convex shaft, and the second convex shaft is slidably connected to the second spiral groove; the photosensitive tube is provided with a third convex shaft at one end away from the second convex shaft, the guide tube is provided with a transverse guide groove, and the third convex shaft is slidably connected to the transverse guide groove.

2. The simple, small and cheap parfocal device according to claim 1, characterized in that: An imaging lens is provided at one end of the lens barrel away from the first convex shaft; and a photosensitive element is provided at one end of the photosensitive barrel close to the second convex shaft.

3. The simple, small and cheap parfocal device according to claim 1, characterized in that: The pitch of the second spiral groove gradually increases from one end of the lens to the other end, and the photosensitive tube can rotate relative to the lens tube through the second spiral groove and move horizontally in the guide tube.

4. The simple, small and cheap parfocal device according to claim 1, characterized in that: A spring is provided between the end of the lens barrel and the end of the photosensitive barrel, one end of the spring abuts against the outer end surface of the lens barrel, and the other end abuts against the inner end surface of the columnar portion with a larger diameter on the photosensitive barrel.

5. The simple, small and cheap parfocal device according to claim 1, characterized in that: An adjusting ring is sleeved on the outside of the first spiral groove of the guide cylinder, and the adjusting ring rotates around the axis of the guide cylinder; The inner side wall of the adjusting ring is provided with a linear guide groove parallel to the axis, and the first convex shaft passes through the first spiral groove from the inside to the outside and is slidably connected with the linear guide groove.

6. The simple, small and cheap parfocal device according to claim 5, characterized in that: The guide tube is provided with two centrally symmetrical first spiral grooves, the lens tube is provided with two symmetrical first convex shafts, and the two opposite inner side walls of the adjustment ring are each provided with a linear guide groove, and the two first convex shafts slide in the first spiral groove and the linear guide groove on the corresponding sides.

7. The simple, small and cheap parfocal device according to claim 5, characterized in that: The outer peripheral surface of the adjustment ring is provided with stripes for increasing the surface roughness.

8. The simple, small and cheap parfocal device according to claim 5, characterized in that: The guide sleeve is provided with a front end housing and a rear end housing, wherein the front end housing is located at a side of the adjusting ring close to the object, and the rear end housing is located at the other side of the adjusting ring.

9. The simple, small and cheap parfocal device according to claim 1, characterized in that: The lens barrel is provided with two centrally symmetrical second spiral grooves, and the photosensitive barrel is provided with two symmetrical second convex shafts, which slide in the second spiral grooves on the corresponding sides.

10. The simple, small and cheap parfocal device according to claim 1, characterized in that: The guide cylinder is provided with two symmetrical transverse guide grooves, and the photosensitive cylinder is provided with two symmetrical third convex shafts, which slide in the transverse guide grooves on the corresponding sides.

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