A device for reducing stray light

Abstract

The application provides a device for weakening stray light, and belongs to the technical field of optics. The device for weakening stray light comprises a lens barrel, a light elimination part, a lens and a sensor. The light elimination part is designed between the lens and the sensor, which can make up for the deficiency that the stray light between the inner wall of the lens and the sensor cannot be eliminated when the light elimination part is added in front of the lens and inside the lens. The light rays emitted from the lens to the part of the inner wall of the lens barrel between the two diaphragms are transmitted to the outside of the target surface of the sensor or are blocked by the light elimination part through the joint action of other diaphragms on the mounting part, which can effectively deal with the problem of stray light change caused by lens focusing change. No matter where the lens is located, the light elimination part can effectively weaken the stray light. The light elimination part is arranged between the lens and the sensor, which does not increase the length of the imaging system in the axial direction like adding a light elimination structure in front of the lens, and can make the system more compact.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, in particular to a device for weakening stray light. BACKGROUND

[0002] Imaging systems or detection systems are often affected by stray light or interference light, which reduces the imaging quality and detection accuracy. Reducing the reflectivity of the inner wall surface of the optical path structure is a common method for weakening stray light, such as using light-absorbing paint.

[0003] Chinese patents CN201921396233.2 and CN202020470536.0 both use black light-absorbing material layers such as black flocking to weaken stray light, and Chinese patent CN202021304212.6 uses a blackened metal material surface to reduce the reflectivity of the inner wall of the part. The inner wall surface of the structure can also be provided with microstructures or threads to increase the number of reflections of stray light and weaken its intensity. For example, Chinese patent CN200580041871.7 uniformly arranges small recesses and steps on the inner wall of the optical path structure, and Chinese patent CN201910169009.8 makes the surface of the structure into a honeycomb-like microstructure to attenuate the intensity of the stray light after multiple reflections and scattering. Chinese patent CN202021203261.0 provides a method for weakening stray light by using small threads on the inner wall. The above-mentioned patents have the following disadvantages: blackening is only suitable for metal parts, and the degree of stray light reduction inside the blackened metal part is limited when the optical tube structure contains a long optical path. Light-absorbing paint can be used on the surface of various materials and has good effects, but it increases the surface treatment steps of the product and has a high cost. Black flocking on the inner wall has the best light-absorbing effect, but the flocking is easy to fall off after long-term use, and small hairs are easy to adhere to the surface of important optical devices such as lenses, filters, and image sensors, causing black spots or dark spots in the imaging picture and affecting the normal use of the product. Adding microstructures and threads to the inner wall of the structure will greatly increase the cost of manufacturing molds or the body of the part.

[0004] Adding structural components in the optical path, such as setting a light hole that only allows effective light to pass and a baffle that blocks stray light, can also effectively reduce the influence of stray light. The variable aperture between lenses in traditional SLR lenses can weaken part of the stray light, which can be considered as a single-layer diaphragm. Chinese patent CN201110139575.8 adds a diaphragm at the entrance pupil and exit pupil of the lens to reduce stray light. Chinese patent CN201811463473.X and Chinese patent CN201711436174.2 both use the form of adding multiple diaphragms before the entrance pupil of the lens to reduce stray light. Chinese patent CN201810226593.1 sets multiple diaphragms before the entrance pupil, and also sets multiple diaphragms between the lenses of the lens group. The above-mentioned patents have the following shortcomings: In a compact or portable optical device, the space after the exit pupil is generally narrow, and the inner wall of the structural component in this part is also prone to reflection and scattering, which affects the optical system. Adding diaphragms before the entrance pupil, between the lenses, or close to the exit pupil cannot reduce this part of stray light. In addition, when the lens of the imaging optical system has a long working distance and needs to move relative to the image sensor, i.e. focusing, the light rays that produce stray light will change with the movement. If the lens group is zoomable, the light rays that produce stray light will change more during zooming. Therefore, multiple diaphragms set at fixed positions may not be able to meet the needs of reducing stray light at each position. SUMMARY

[0005] The purpose of the present application is to provide a device for reducing stray light.

[0006] The present application provides a device for reducing stray light, comprising a lens barrel, a light extinction member, a lens and a sensor respectively arranged at both ends of the inner side of the lens barrel, the lens barrel comprising a mounting portion, a far object end arranged on the mounting portion, and an adjusting portion connected to the far object end and capable of preventing light not passing through the lens from entering, the lens being movable forward and backward inside the adjusting portion, the inner diameter of the adjusting portion being larger than the inner diameter of the mounting portion at the far object end, the light extinction member comprising a first diaphragm connected to the side of the lens close to the sensor and abutting against the inner wall of the mounting portion, and a second diaphragm to an Nth diaphragm arranged in sequence backward along the direction from the lens to the sensor on the inner wall of the mounting portion; the second diaphragm to the Nth diaphragm are respectively installed at a preset position in the lens barrel according to the position of the previous diaphragm, and the common action of any two adjacent diaphragms transmits the light rays emitted from the lens to the part between the two diaphragms on the inner wall of the lens barrel to the outside of the target surface of the sensor or stops the light rays.

[0007] Furthermore, the adjustment unit includes a first light-blocking plate connected to the far-object end, a near-object end disposed on the inner side, and a second light-blocking plate disposed at the entrance opening. The axes of the first to Nth apertures, the axis of the lens, the axis of the sensor, and the axis of the circuit board all coincide with the axis of the lens barrel. When the lens is positioned close to the far-object end, the line connecting the far-object end and the bottom end of the sensor intersects the line connecting the bottom end of the upper part of the first aperture and the top end of the sensor at a first intersection point. The bottom end of the upper part of the second aperture intersects the first intersection point. N represents 3, 4, 5... The Nth aperture satisfies the following condition: the extension line connecting the top end of the lower part of the first aperture and the bottom end of the upper part of the (N-1)th aperture intersects the inner wall of the mounting part at the (N-2)th reflection point. The line connecting the bottom of the sensor and the (N-2)th reflection intersection point, and the line connecting the bottom of the upper part of the first aperture and the top of the sensor, intersects at the (N-1)th intersection point. The bottom of the upper part of the aperture intersects with the (N-1)th intersection point. When N is the last aperture, the extension line of the line connecting the bottom of the upper part of the Nth aperture and the top of the lower part of the first aperture does not intersect with the inner wall of the mounting part. During the process of the lens moving from the position near the far object end to the near object end, the extension line of the line connecting the far object end and the bottom of the sensor intersects with the adjustment part at the adjustment reflection intersection point. The intersection point of the extension line of the line connecting the top of the lower part of the first aperture and the bottom of the upper part of the first aperture and the adjustment part is between the adjustment reflection intersection point and the far object end.

[0008] Furthermore, it also includes a circuit board disposed on the side of the sensor away from the lens. The light-absorbing component also includes a stop aperture disposed close to the sensor to prevent light from shining onto the circuit board. The axis of the stop aperture coincides with the axis of the lens barrel. The line connecting the upper part and at most the bottom of the stop aperture and the bottom of the upper part of the first aperture to the top of the sensor intersects.

[0009] Furthermore, the thickness 'a' of the first aperture to the Nth aperture and the stop aperture is 0.1 mm < a < 10 mm.

[0010] Furthermore, the upper edges of the first to Nth aperture stops and the lower edges of the first to Nth aperture stops each include a first chamfer set in the direction of the lens.

[0011] Furthermore, the upper edge and the lower edge of the stop aperture both include a second chamfer set towards the sensor direction.

[0012] Furthermore, the inner diameter of the mounting portion decreases or increases sequentially from the end connected to the adjustment portion to the other end closer to the sensor, or remains unchanged.

[0013] Furthermore, the matting component also includes a first matting varnish layer disposed on the inner wall of the lens barrel or a first matting film adhered to the inner wall of the lens barrel.

[0014] Furthermore, the matting component also includes a second matting paint layer disposed on the outer periphery of the first aperture to the Nth aperture and the stop aperture, or a second matting film bonded to the outer periphery of the first aperture to the Nth aperture and the stop aperture.

[0015] The device for reducing stray light according to the present invention has the following beneficial effects:

[0016] A light-absorbing element is designed between the lens and the sensor. This allows the combined effect of any two adjacent apertures to transmit light emitted from the lens to the portion of the lens barrel's inner wall located between those two apertures, either to the outside of the sensor target surface or to block that light. This compensates for the inability to eliminate stray light from the inner wall between the lens and sensor when adding light-absorbing elements in front of or inside the lens. An adjustment section prevents light that has not passed through the lens from entering. Adjusting the lens's position within the adjustment section prevents light passing through the lens from entering the adjustment section and being reflected onto the sensor. The mounting section, through the combined effect of other apertures, transmits light emitted from the lens to the portion of the lens barrel's inner wall located between those two apertures, either to the outside of the sensor target surface or to block that light. This effectively addresses stray light variations caused by changes in lens focus. Regardless of the lens's position, the light-absorbing element effectively reduces stray light. Because the light-absorbing element is positioned between the lens and the sensor, it does not increase the axial length of the imaging system like adding a light-absorbing structure in front of the lens, allowing for a more compact system. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the invention, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without any inventive effort.

[0018] Figure 1 This is a schematic diagram of the structure of a device for reducing stray light according to an embodiment of the present invention, in which the inner diameter of the mounting part remains unchanged and no focusing is performed;

[0019] Figure 2 This is a schematic diagram of the structure of a device for reducing stray light according to an embodiment of the present invention, in which the inner diameter of the mounting part remains unchanged and the focus is adjusted.

[0020] Figure 3 This is a schematic diagram of the structure of a device for reducing stray light according to an embodiment of the present invention, in which the inner diameter of the mounting part gradually decreases and no focusing is performed.

[0021] In the diagram: 10-Lens, 20-First aperture stop, 21-Second aperture stop, 22-Third aperture stop, 23-Stop aperture stop, 30-Lens barrel, 31-Sensor, 32-Circuit board, 41-Adjustment unit, 42-First light-blocking plate, 43-Second light-blocking plate, 44-Mounting unit. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0023] Please see Figures 1-3 An embodiment of the present invention provides a device for reducing stray light, comprising a lens barrel 30, an anti-light extinguishing element, a lens 10 and a sensor 31 respectively disposed at both ends of the inner side of the lens barrel 30. The lens barrel 30 includes a mounting portion 44, a remote object end disposed on the mounting portion 44, and an adjustment portion 41 connected to the remote object end and preventing light that has not passed through the lens 10 from entering therein. The lens 10 can move along a corresponding direction as the adjustment portion 41 extends and retracts. The inner diameter of the adjustment portion 41 is larger than the inner diameter of the mounting portion 44 at the remote object end. The anti-light extinguishing element includes a component that is fitted and connected to the lens 10 near the lens 10. A first aperture 20 is located near one side of the sensor 31 and abuts against the inner wall of the mounting part 44. A second aperture 21 to the Nth aperture are sequentially arranged on the inner wall of the mounting part 44 along the direction from the lens 10 to the sensor 31. The second aperture 21 to the Nth aperture are respectively installed at preset positions inside the lens barrel 30 according to the position of the previous aperture. The combined effect of any two adjacent apertures will transmit the light emitted from the lens 10 to the part of the inner wall of the lens barrel 30 located between the two apertures to the outside of the target surface of the sensor 31 or block the light.

[0024] Specifically, the end of sensor 31 is located outside the target surface of sensor 31. By using the end of sensor 31 as a reference point, it is convenient to set each aperture stop inside the lens barrel 30. When the lens 10 is not focused, the positions of the second aperture stop 21 to the Nth aperture stop are determined sequentially according to the position of the previous aperture stop and the principle of light reflection. Each aperture stop is installed in the corresponding preset position inside the lens barrel 30. The lens 10 emits light to the part of the inner wall of the lens barrel 30 located between two adjacent aperture stops. The inner wall of the lens barrel 30 reflects the light. These two aperture stops can either transmit the emitted light to the end of sensor 31 or block the reflected light, which can compensate for the addition of extinction in front of and inside the lens 10. The light-absorbing component cannot eliminate the stray light from the inner wall between the lens 10 and the sensor 31. After focusing the lens 10, no light that has not passed through the lens 10 enters the inner side of the adjustment section 41. The lens 10 is extended by a certain length so that when the light emitted after passing through the lens 10 enters the inner side of the adjustment section 41, the adjustment section 41 blocks the light, so that it cannot be reflected to the sensor 31. This can effectively deal with the stray light change problem caused by the focus change of the lens 10. No matter what position the lens 10 is in, the light-absorbing component can effectively reduce stray light.

[0025] The adjustment unit 41 includes a first light-blocking plate 42 connected to the far object end, a near object end disposed on the inner side, and a second light-blocking plate 43 disposed at the entrance opening. The axes of the first aperture 20 to the Nth aperture, the axis of the lens 10, the axis of the sensor 31, and the axis of the circuit board 32 all coincide with the axis of the lens barrel 30. When the lens 10 is positioned close to the far object end, the line connecting the far object end and the bottom end of the sensor 31 intersects the line connecting the bottom end of the upper part of the first aperture 20 and the top end of the sensor 31 at the first intersection point. The bottom end of the upper part of the second aperture 21 intersects the first intersection point. N represents 3, 4, 5, ... The Nth aperture satisfies the following: the extension line of the line connecting the top end of the lower part of the first aperture (20) and the bottom end of the upper part of the (N-1)th aperture intersects the inner wall of the mounting part (44) at the (N-2)th reflection intersection point. The sensor (31) The line connecting the bottom of the first aperture (20) and the N-2th reflection intersection point, and the line connecting the bottom of the upper part of the first aperture (20) and the top of the sensor (31) intersect at the N-1th intersection point. The bottom of the upper part of the aperture intersects with the N-1th intersection point. When N is the last aperture, the extension line of the line connecting the bottom of the upper part of the Nth aperture and the top of the lower part of the first aperture (20) does not intersect with the inner wall of the mounting part (44). During the process of the lens (10) moving from the position near the far end to the near end, the extension line of the line connecting the far end and the bottom of the sensor (31) intersects with the adjustment part (41) at the adjustment reflection intersection point. The intersection point of the extension line of the line connecting the top of the lower part of the first aperture (20) and the bottom of the upper part of the first aperture (20) and the adjustment part (41) is between the adjustment reflection intersection point and the far end.

[0026] Specifically, the lens barrel 30, lens 10, sensor 31, circuit board 32, and each aperture are all axially symmetrical objects. The lens 10, sensor 31, circuit board 32, and each aperture are all located inside the lens barrel 30. The axes of the lens 10, sensor 31, circuit board 32, and each aperture coincide with the axis of the lens barrel 30. The axis of the light-transmitting hole of each aperture coincides with the axis of the lens 10. The axis of the lens 10 can be used as the optical axis. Imaging beam distribution spaces are provided on both sides of the optical axis. The non-light-transmitting hole parts of the inner wall of the lens barrel 30 and each aperture should be outside the imaging beam distribution space. The line connecting the bottom of the upper part of the first aperture 20 and the top of the sensor 31 can be the upper limit line of the imaging beam distribution space. The line connecting the top of the lower part of the first aperture 20 and the bottom of the sensor 31 can be the lower limit line of the imaging beam distribution space. The first aperture stop 20 is disposed close to one side of the lens 10. Since it is connected to the lens 10, it can move with the lens 10. The first aperture stop 20 abuts against the inner wall of the mounting portion 44. When the lens 10 is not focused, the first aperture stop 20 abuts against the far object end of the mounting portion 44, thus preventing light from the adjustment portion 41 from shining onto the portion of the mounting portion 44 located between the far object end and the second aperture stop 21. The first aperture stop 20 to the Nth aperture stop are all disposed along the vertical line of the axis of the lens barrel 30. When the axis of the lens barrel 30 is horizontal, the first aperture stop 20 to the Nth aperture stop are all vertically disposed.

[0027] Specifically, when lens 10 is positioned close to the far-object end, i.e., at infinity imaging position, the line connecting the far-object end and the bottom of sensor 31, and the line connecting the bottom of the upper part of first aperture 20 and the top of sensor 31, intersect at a first intersection point. Based on this first intersection point, the position of the bottom of the upper part of second aperture 21 can be determined, thus determining the size of the light-transmitting aperture of second aperture 21. By fixing second aperture 21 to the inner wall of mounting part 44, the size of second aperture 21 and its position within lens barrel 30 can be determined. The side of first aperture 20 furthest from lens 10 abuts against the far-object end, and the line connecting the far-object end and the bottom of sensor 31 is the position... The only reflected light ray to the sensor 31 is located in the section of the mounting part 44 between the first aperture 20 and the second aperture 21. At this time, the light passing through the lens 10 cannot reach the section of the mounting part 44 between the first aperture 20 and the second aperture 21, so there is no incident light and therefore no reflected light ray. The second aperture 21 to the Nth aperture are all located on the inner wall of the mounting part 44 and abut against the mounting part 44, so light can only pass through the light-transmitting holes of the second aperture 21 to the Nth aperture respectively. From the third aperture 22... Taking the Nth aperture as the direction of successive backward movement, the second aperture 21 is the aperture preceding the third aperture 22, and the (N-1)th aperture is the aperture preceding the Nth aperture. On the mounting part 44 located between any two adjacent apertures, the extension of the line connecting the top of the lower part of the first aperture 20 and the bottom of the upper part of the (N-1)th aperture intersects the inner wall of the mounting part 44 at the (N-2)th reflection intersection point. The line connecting the top of the lower part of the first aperture 20 and the (N-2)th reflection intersection point is the incident light, and the line connecting the bottom of the sensor 31 and the first reflection intersection point is the reflected light. The line connecting the bottom of sensor 31 and the first reflection point, and the line connecting the bottom of the upper part of the first aperture 20 and the top of sensor 31, intersect at the (N-1)th intersection point. Based on the (N-1)th intersection point, the position of the bottom of the upper part of the Nth aperture can be determined, thus determining the size of the light-transmitting aperture of the Nth aperture. By fixing the Nth aperture to the inner wall of the mounting part 44, the size of the Nth aperture and its position within the lens barrel 30 can be determined. The size and position of each aperture within the lens barrel 30 are determined sequentially from the third aperture 22 to the Nth aperture. On the mounting part 44, in any two adjacent apertures from the second aperture 21 to the Nth aperture, there is only one incident ray emitted from the bottom top of the first aperture 20 to the reflection point on the mounting part 44, and one reflected ray from the reflection point to the bottom of sensor 31. Since the reflected ray can only be reflected to the bottom of sensor 31, it will not interfere with sensor 31.The extension of the line connecting the bottom of the upper part of the Nth aperture and the top of the lower part of the first aperture 20 is the incident light passing through the Nth aperture. Since this extension line does not intersect with the inner wall of the mounting part 44, it means that the incident light cannot illuminate the inner wall of the mounting part 44. Therefore, the inner wall of the lens barrel 30 cannot reflect the light onto the sensor 31, and the lens barrel 30 will not reflect interference light to the sensor 31.

[0028] Specifically, the far end of the lens barrel 30 is farther from the object than the near end. When focusing the lens 10, the length of the adjustment section 41 of the lens barrel 30 can be varied. When the adjustment section 41 is at its shortest, the lens 10 is positioned close to the far end. When the adjustment section 41 is extended, the lens 10 moves from the position close to the far end to the position close to the near end. During this movement, the lens 10 moves away from the second aperture stop 21. Since the first aperture stop 20 is connected to the lens 10, it moves with the movement of the lens 10. The second light-blocking plate 43 can block light that has not passed through the lens 10, preventing external light from shining onto the inner wall of the adjustment section 41 before being reflected back onto the sensor 31 and interfering with it. Therefore, only light that has passed through the lens 10 remains on the inner wall of the adjustment section 41. The inner diameter of the adjusting part 41 remains unchanged, and the inner diameter of the adjusting part 41 is larger than the maximum inner diameter of the mounting part 44. Since one end of the first light-blocking plate 42 is connected to the far end of the mounting part 44, the first light-blocking plate 42 protrudes from the outside of the mounting part 44. When the lens 10 is focused to the near end, the adjusting part 41 extends to its maximum length. The extension line of the line connecting the far end and the bottom end of the sensor 31 intersects the adjusting part 41 at the adjustment reflection intersection point. Adjusting the focusing length of the lens 10 allows external light to pass through the lens 10 and the first aperture 20 before entering the adjusting part 41. The intersection point is between the adjustment reflection intersection point and the far end. Therefore, after the light shines on the adjusting part 41, it will be reflected to the first light-blocking plate 42. When the first light-blocking plate 42 blocks the light, it cannot be reflected onto the sensor 31. During the focusing process of the lens 10, that is, during the movement of the lens 10 from the far object end to the near object end, the intersection of the extension line of the line connecting the top of the lower part of the first aperture 20 and the bottom of the upper part of the first aperture 20 and the adjustment section 41 is between the adjustment reflection intersection point and the far object end. This ensures that the focal point of the external light passing through the lens 10 and the first aperture 20 and entering the adjustment section 41 is between the adjustment reflection intersection point and the far object end. When the light shines on the adjustment section 41, it will be reflected onto the first light-blocking plate 42. The first light-blocking plate 42 blocks the light, so it cannot be reflected onto the sensor 31. After the lens 10 is focused, the first aperture 20 moves forward, so the angle between the line connecting the top of the lower part of the first aperture 20 and the bottom of the upper part of any subsequent aperture and the horizontal axis becomes smaller. The intersection point of this line with the inner wall of the lens barrel 30 is located behind the intersection point when the lens is not focused. At this time, the incident light and the reflected light have no intersection point on the lens barrel 30. The inner wall of the lens 10 will reflect the incident light to the adjacent aperture behind this aperture, and it cannot be reflected to the sensor 31. If this aperture is the last aperture among the third to Nth apertures, the extension line of the line connecting the top of the lower part of the first aperture 20 and the bottom of the upper part of this aperture is farther away from the inner wall of the lens barrel 30, and it will be even less likely to be transmitted to the inner wall of the lens barrel 30.

[0029] It also includes a circuit board 32 disposed on the side of the sensor 31 away from the lens 10. The light-absorbing component may also include a stop aperture 23 disposed close to the sensor 31 to prevent light from shining onto the circuit board 32. The axis of the stop aperture 23 coincides with the axis of the lens barrel 30. The upper part of the stop aperture 23 and at most the bottom end intersect the line connecting the bottom end of the upper part of the first aperture 20 and the top end of the sensor 31.

[0030] Specifically, when N is the last aperture, the light passing through the top of the lower part of the first aperture 20 cannot illuminate the inner wall of the lens barrel 30 after passing through the Nth aperture, but will illuminate the circuit board 32. The circuit board 32 can reflect the light to the sensor 31. Therefore, the stop aperture 23 prevents this part of the light from being reflected to the sensor 31.

[0031] The thickness 'a' of the first aperture 20 to the Nth aperture and the stop aperture 23 can all be 0.1mm < a < 10mm.

[0032] The upper edges of the first aperture stop 20 to the Nth aperture stop, and the lower edges of the first aperture stop 20 to the Nth aperture stop, can each include a first chamfer set in the direction of the lens 10.

[0033] The upper edge and the lower edge of the stop aperture 23 may each include a second chamfer set in the direction of the sensor 31.

[0034] The inner diameter of the mounting part 44 can decrease or increase sequentially from the end connected to the adjustment part 41 to the other end near the sensor 31, or remain unchanged.

[0035] The matting component may also include a first matting varnish layer disposed on the inner wall of the lens barrel 30 or a first matting film adhered to the inner wall of the lens barrel 30.

[0036] The matte finish may also include a second matte paint layer disposed on the outer periphery of the first aperture 20 to the Nth aperture and the stop aperture 23, or a second matte film bonded to the outer periphery of the first aperture 20 to the Nth aperture and the stop aperture 23.

[0037] The inner diameter of the adjusting part 41 can remain constant from one end of the incident opening to the end connected to the mounting part 44.

[0038] The light-reducing component may also include a limiting aperture disposed on the side of the lens 10 away from the first aperture 20, for limiting the light entering the lens 10, the axis of the limiting aperture being coincident with the axis of the lens barrel 30.

[0039] Specifically, the first aperture 20 is positioned immediately adjacent to the rear surface of the lens 10 and moves with the lens 10 during focusing. The inner diameter of the mounting portion 44 of the lens barrel 30 can vary axially, either gradually decreasing or remaining constant. Taking the infinity imaging position of the first aperture 20 as a dividing point, the inner diameter of the lens barrel 30 corresponding to the position where the first aperture 20 is near the imaging end is larger than the inner diameter of the lens barrel 30 at the dividing point. Multiple apertures have axially varying aperture diameters. When the inner diameter of the mounting portion 44 remains constant, the aperture diameters of each aperture from the second aperture 21 to the Nth aperture can gradually decrease; conversely, when the inner diameter of the mounting portion 44 gradually decreases, the aperture diameters of each aperture from the second aperture 21 to the Nth aperture can remain constant. The principle behind the axial placement of the second aperture 21 to the Nth aperture is to prevent light incident on the inner wall of the lens barrel 30 from directly incident on the surface of the sensor 31 due to specular reflection. The greater the difference between the aperture value and the inner diameter of the lens barrel 30, the fewer the number of matting stops needed, and the better the matting effect. Chamfering can be applied to the edge of the aperture to effectively prevent stray light from being reflected to the image plane. Spraying matting paint or applying matting film to the aperture and the inner wall of the lens barrel 30 can further reduce stray light. Adding multiple aperture stops in front of the lens 10, in combination, can achieve even better matting effects.

[0040] Specifically, such as Figure 1 , Figure 1The lower parts of the lens barrel 30, the second aperture 21, the third aperture 22, and the stop aperture 23 are omitted from the drawing. The far object end of the lens barrel 30 can be point A. At this time, the lens 10 is at the position of infinity imaging. The position of the lens 10 and the first aperture 20 behind it is relatively fixed. The position of the first aperture 20 coincides with the exit pupil position of the lens 10. The aperture diameter is not less than the exit pupil diameter. The aperture diameter of the aperture in the figure is the same as the exit pupil diameter. The dashed line passing through the center of the lens 10 is the optical axis. The dotted lines on both sides of the optical axis are the imaging beam distribution space. The inner wall of the lens barrel 30 and the aperture should be outside the dotted lines. The inner diameter of the lens barrel 30 along the axial direction from point A to the image plane remains unchanged. The inner diameter of the part extending from point A to the object side is larger. The method for setting other apertures is as follows: Draw a straight line from point A on the lens barrel 30 to the edge of the field of view of the opposite sensor 31. Draw a line segment perpendicular to the inner wall of the lens barrel 30 at the intersection of the straight line and the dotted line. This line segment is the second aperture 21. Draw a straight line from the vertex on the other side of the first aperture 20 opposite to point A, passing through the vertex of the second aperture 21 and intersecting the lens barrel 30 at point D. Draw another straight line from point D to the edge of the field of view of the aforementioned sensor 31. Draw a line segment perpendicular to the inner wall of the lens barrel 30 at the intersection of this straight line and the dotted line. This line segment is the third aperture 22. Following the method of the second step, draw a straight line again from the vertex on the other side of the first aperture 20 opposite to point A, passing through the vertex of the third aperture 22. At this time, it is found that the straight line no longer intersects the inner wall of the lens barrel 30, so no new aperture is set in this step. In order to prevent light from shining onto the circuit board 32 of the sensor 31 and then reflecting back onto the sensor 31, set an aperture close to the sensor 31. The top of the aperture should not cross the dotted line. The principle behind the aforementioned aperture setting is to prevent light entering the lens 10 from being reflected off the inner wall of the lens barrel 30 and then incident on the surface of the sensor 31. For example, no light will illuminate the inner wall of the lens barrel 30 between B and D. Although light can directly illuminate the inner wall of the lens barrel 30 between DC, this light is blocked by the third aperture 22 located at point C after being emitted from the inner wall of the lens barrel 30. A separate aperture is set for the fourth part because the circuit board 32 of the sensor 31 usually has a high reflectivity, and the light reflected from it will have a significant impact on the imaging after being reflected by the inner wall of the lens barrel 30. In addition, the aperture itself has thickness along the axial direction, and light can also be reflected from the inner wall of the aperture to the sensor 31. Therefore, its edge needs to be chamfered to minimize the surface directly illuminated by light. The chamfering direction is generally based on the premise that the light does not incident on the sensor 31 after being reflected by the chamfered surface. Generally speaking, the chamfered surface closer to the exit pupil faces the exit pupil, and the chamfered surface closer to the sensor 31 faces the sensor 31.

[0041] Specifically, such as Figure 2 , Figure 2The lower parts of the lens barrel 30, the second aperture 21, the third aperture 22, and the stop aperture 23 are omitted from the drawing. The lens 10 and the first aperture 20 are moved to the near-end imaging position. Although no aperture is set between point A and the first aperture 20, because the inner diameter of this section of the lens barrel 30 is increased, no light is reflected from the inner wall of the lens barrel 30 and enters the sensor 31. Other positions of the lens barrel 30 will also not reflect light to the sensor 31, such as in the BC region. The area where light can directly illuminate is D'C, while the area where the lens barrel 30 can directly reflect light to the sensor 31 is BD. These two regions do not intersect, therefore no light can enter the sensor 31 after being reflected once by the inner wall of the lens barrel 30. It is important to note that the diameter of the inner wall of the lens barrel 30 between point A and the first aperture stop 20 is related to the focusing range of the lens 10. From infinity imaging to near-end imaging, the greater the moving distance of the lens 10, the larger the inner diameter of the lens barrel 30 will be. The specific size needs to be determined by auxiliary lines. The principle for determining the size is to ensure that no light can be reflected once by the inner wall of the lens barrel 30 and then enter the sensor 31.

[0042] Therefore, the stray light reduction structure in this application can prevent stray light from directly entering the sensor 31 after one reflection within the focusing range of the lens 10.

[0043] Specifically, as shown in Figure 3, Figure 3 The lower parts of the lens barrel 30, the second aperture 21, the third aperture 22, and the stop aperture 23 are omitted from the drawing; at this point, the lens 10 is positioned at infinity for imaging. The inner diameter of the mounting portion 44 of the lens barrel 30 gradually decreases axially from the object end to the image plane. The aperture setting method is similar to... Figure 1 and Figure 2 The same as in the previous figure. However, it can be observed that, for the same axial distance, the number of apertures on the inner wall of the lens tube 30 in this figure is one more.

[0044] The above-described contents can be implemented individually or in various combinations, and these variations are all within the protection scope of this invention.

[0045] It should be noted that in the description of this application, the terms "upper end," "lower end," and "bottom end," indicating orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise limited, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for reducing stray light, characterized in that: The system includes a lens barrel (30), a light-reducing element, a lens (10) and a sensor (31) respectively disposed at both ends of the inner side of the lens barrel (30). The lens barrel (30) includes a mounting part (44), a far-object end disposed on the mounting part (44), and an adjustment part (41) connected to the far-object end and preventing light that has not passed through the lens (10) from entering therein. The lens (10) can move back and forth inside the adjustment part (41). The inner diameter of the adjustment part (41) is larger than the inner diameter of the mounting part (44) at the far-object end. The light-reducing element includes a first aperture (20) that fits and is connected to the side of the lens (10) near the sensor (31) and abuts against the inner wall of the mounting part (44). The light-reducing element extends along the inner wall of the mounting part (44) from the lens. A second aperture (21) to an Nth aperture are sequentially arranged rearward from the head (10) to the sensor (31); the second aperture (21) to the Nth aperture are respectively installed at preset positions inside the lens barrel (30) according to the position of the previous aperture. The combined effect of any two adjacent apertures will transmit the light emitted from the lens (10) to the part of the inner wall of the lens barrel (30) located between the two apertures to the outside of the target surface of the sensor (31) or block the light; the adjustment part (41) includes a first light-blocking plate (42) connected to the far object end, a near object end set on the inner side, and a second light-blocking plate (43) set at the entrance opening. The axis of the first aperture (20) to the Nth aperture, the axis of the lens (10), The axis of the sensor (31) and the axis of the circuit board (32) are both coincident with the axis of the lens barrel (30); when the lens (10) is set near the far end, the line connecting the far end and the bottom end of the sensor (31) and the line connecting the bottom end of the upper part of the first aperture (20) and the top end of the sensor (31) intersect at the first intersection point, and the bottom end of the upper part of the second aperture (21) intersects with the first intersection point. N represents 3, 4, 5... The Nth aperture satisfies: the extension line of the line connecting the top end of the lower part of the first aperture (20) and the bottom end of the upper part of the (N-1)th aperture intersects with the inner wall of the mounting part (44) at the (N-2)th reflection intersection point, and the line connecting the bottom end of the sensor (31) and the (N-2)th reflection intersection point intersects with the upper end of the first aperture (20) at the first intersection point. The line connecting the bottom of the aperture (31) and the top of the sensor (31) intersects at the (N-1)th intersection point. The bottom of the upper part of the aperture intersects with the (N-1)th intersection point. When N is the last aperture, the extension line of the line connecting the bottom of the upper part of the Nth aperture and the top of the lower part of the first aperture (20) does not intersect with the inner wall of the mounting part (44). During the process of the lens (10) moving from the position near the far end to the near end, the extension line of the line connecting the far end and the bottom of the sensor (31) intersects with the adjustment part (41) at the adjustment reflection intersection point. The intersection point of the extension line of the line connecting the top of the lower part of the first aperture (20) and the bottom of the upper part of the first aperture (20) with the adjustment part (41) is between the adjustment reflection intersection point and the far end.

2. The device for reducing stray light as described in claim 1, characterized in that: It also includes a circuit board (32) disposed on the side of the sensor (31) away from the lens (10). The light-absorbing component also includes a stop stop (23) disposed near the sensor (31) to prevent light from shining onto the circuit board (32). The axis of the stop stop (23) coincides with the axis of the lens barrel (30). The upper part of the stop stop (23) and at most the bottom end intersect the line connecting the bottom end of the upper part of the first stop (20) and the top end of the sensor (31).

3. The device for reducing stray light as described in claim 2, characterized in that: The thickness a of the first aperture (20) to the Nth aperture and the stop aperture (23) is 0.1mm < a < 10mm.

4. The device for reducing stray light as described in claim 1, characterized in that: The upper edges of the first aperture stop (20) to the Nth aperture stop, and the lower edges of the first aperture stop (20) to the Nth aperture stop, all include a first chamfer set in the direction of the lens (10).

5. The device for reducing stray light as described in claim 2, characterized in that: The upper edge and the lower edge of the stop aperture (23) both include a second chamfer set in the direction of the sensor (31).

6. The device for reducing stray light as described in claim 1, characterized in that: The inner diameter of the mounting part (44) decreases or increases sequentially from the end connected to the adjustment part (41) to the other end near the sensor (31), or remains unchanged.

7. The device for reducing stray light as described in claim 1, characterized in that: The matting component also includes a first matting varnish layer disposed on the inner wall of the lens barrel (30) or a first matting film adhered to the inner wall of the lens barrel (30).

8. The device for reducing stray light as described in claim 2, characterized in that: The matting component further includes a second matting paint layer disposed on the outer periphery of the first aperture (20) to the Nth aperture and the stop aperture (23), or a second matting film bonded to the outer periphery of the first aperture (20) to the Nth aperture and the stop aperture (23).

Images