Camera module

Abstract

A camera module includes a circuit board, a photosensitive element and a lens assembly. The camera module also includes a light guide, a light source assembly and a cover ring. The photosensitive element is arranged on the circuit board and is electrically connected to the circuit board. The lens assembly is arranged on a side of the photosensitive element away from the circuit board. At least part of the structure of the light guide is arranged outside the lens assembly. The light source assembly includes a light source. The cover ring is arranged on the top of the light guide. A mounting portion is also arranged at the periphery of the light guide. A glue groove is provided on the mounting portion. The glue groove is provided with an adhesive portion to connect the light guide and the cover ring. The camera module provided by the present invention is provided with a light guide and a light source assembly for fill light, which greatly improves the imaging effect of the camera module. In addition, a mounting portion with a glue groove is provided on the light guide. Glue can be poured into the glue groove to form an adhesive portion to bond the cover ring to the light guide. Therefore, the problem of glue creeping to the outer peripheral surface of the light guide due to capillary phenomena and the like during glue coating, which affects the appearance and light guide effect, is reduced, and the imaging effect of the camera module is further improved.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and in particular to a camera module. Background Art

[0002] With the advancement of science and technology, cameras are being used more and more widely. At present, in addition to cameras, mobile phones, computers and other electronic products are equipped with cameras to facilitate people to take pictures anytime and anywhere, bringing convenience and fun to people's lives.

[0003] As cameras become more and more popular, people have more and more requirements for their functions. One of the important points is that they hope the camera's imaging effect will be better and clearer. Summary of the invention

[0004] The purpose of the present invention is to provide a camera module with better imaging effect.

[0005] The present invention provides a camera module, comprising a circuit board, a photosensitive element and a lens assembly. The camera module also comprises a light guide, a light source assembly and a cover ring. The photosensitive element is arranged on the circuit board and is electrically connected to the circuit board. The lens assembly is arranged on a side of the photosensitive element away from the circuit board. At least part of the structure of the light guide is arranged on the outside of the lens assembly. The light source assembly comprises a light source. The cover ring is arranged on the top of the light guide. A mounting portion is also arranged at the periphery of the light guide. A glue groove is opened on the mounting portion. The glue groove is provided with an adhesive portion to connect the light guide and the cover ring.

[0006] In one embodiment, the cover ring includes a connecting portion, the connecting portion is a flat plate, and the connecting portion covers the glue groove of the mounting portion of the light guide component.

[0007] In one embodiment, the outer side of the light guide is provided with an inclined outer side surface, the cover ring also includes a conical matching portion, the connecting portion is provided at the bottom edge of the matching portion, the matching portion matches with the outer side surface of the light guide plate; the mounting portion protrudes outside the outer side surface.

[0008] In one embodiment, the width of the connecting portion is greater than the width of the glue groove.

[0009] In one embodiment, the light guide member includes an upper part and a lower part, a convex ring is provided on the inner side of the upper part, the bottom surface of the convex ring is tightly fitted with the top surface of the lens assembly, the upper part is located above the lens assembly, the lower part is located outside the lens assembly, and the mounting part is provided on the outer periphery of the lower part.

[0010] In one embodiment, the plurality of mounting portions are evenly arranged along the circumference of the light guide member.

[0011] In one embodiment, the glue groove is opened at the top of the mounting portion, and the glue groove is arc-shaped, and all the glue grooves on the plurality of mounting portions are located on the same circumference.

[0012] In one embodiment, the light source assembly further includes a circuit board and a mounting plate, the light source is disposed on the circuit board, the circuit board is disposed on the mounting plate, and the light source assembly is disposed at the bottom of the light guide.

[0013] In one embodiment, a fixing column is further provided at the bottom of the light guide member facing the light source assembly, and fixing holes corresponding to the fixing columns of the light guide member are formed on the circuit board and the mounting board.

[0014] In one embodiment, a groove is formed at the bottom of the light guide member facing the light source assembly, and the light source is accommodated in the groove.

[0015] In one embodiment, the lens assembly includes a first lens assembly, a second lens assembly, a driving device and a base, the base is arranged on the circuit board, the base forms a cavity, the first lens assembly is arranged on the base, the second lens assembly is arranged on the driving device, the driving device is arranged on a side of the base away from the circuit board, the second lens assembly is located on a side of the first lens assembly away from the photosensitive element, the first lens assembly is a fixed focus lens, and the second lens assembly is a zoom lens.

[0016] The second lens assembly protrudes above the driving device toward a side away from the photosensitive element, and the light guide includes a portion surrounding the outer periphery of the portion of the second lens assembly protruding above the driving device.

[0017] The height from the end surface of the light guide away from the circuit board to the circuit board is greater than the height from the end surface of the second lens assembly away from the circuit board to the circuit board.

[0018] The lens assembly further includes a cover plate, which is attached to the end edge of the light guide away from the circuit board. A glue-containing groove is formed on the end surface of the light guide and the cover plate. The cover ring is arranged around the outer periphery of the cover plate.

[0019] The light guide member is also provided with a flared light emitting surface on the inner side of the end edge away from the circuit board.

[0020] The camera module provided by the present invention provides fill light for the camera module due to the provision of a light guide and a light source assembly, thereby greatly improving the imaging effect of the camera module, and a mounting portion with a glue groove is provided on the light guide, and glue can be poured into the glue groove to form a glue portion, so that the cover ring is bonded to the light guide, thereby reducing the problem of glue creeping to the outer peripheral surface of the light guide due to capillary phenomena during glue coating and affecting the appearance and light guiding effect, thereby further improving the imaging effect of the camera module. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a three-dimensional assembly diagram of a camera module according to an embodiment of the present invention.

[0022] Figure 2 for Figure 1 Another angle stereoscopic assembly diagram of the camera module shown.

[0023] Figure 3 for Figure 1 An exploded perspective view of the camera module shown.

[0024] Figure 4 for Figure 1 Another angle of the camera module is shown.

[0025] Figure 5 for Figure 1 A cross-sectional view of the camera module shown. DETAILED DESCRIPTION

[0026] In order to further explain the technical methods and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments.

[0027] like Figures 1 to 5 As shown, the camera module of one embodiment of the present invention includes a circuit board 11, a photosensitive element 13, a filter 17, a lens assembly, a light guide 25, a light source assembly 27, a cover ring 29 and a cover plate 31. The lens assembly includes a base 15, a first lens assembly 19, a second lens assembly 21 and a driving device 23.

[0028] In this embodiment, the circuit board 11 may be a flexible circuit board. The circuit board 11 includes a main body portion located corresponding to the photosensitive element 13 and a first extension portion extending from the main body portion.

[0029] In this embodiment, the photosensitive element 13 and the base 15 are both arranged on the circuit board 11, and the base 15 forms a cavity 152, and the photosensitive element 13 is accommodated in the cavity 152. Specifically, the photosensitive element 13 can be a photosensitive chip, such as a CCD (Charge Coupled Device) photosensitive chip or a CMOS (Complementary Metal Oxide Semiconductor) photosensitive chip. The photosensitive element 13 is electrically connected to the circuit board 11 to transmit an electrical signal to the circuit board 11. A fixing platform 154 protruding inward is formed on the inner wall of the base 15.

[0030] In this embodiment, the filter 17 is disposed on the fixing platform 154, and the filter 17 is located between the photosensitive element 13 and the first lens assembly 19 and the second lens assembly 21. In this embodiment, the filter 17 is disposed below the fixing platform 154. It can be understood that the filter 17 can also be located above the fixing platform 154. The filter 1 can be fixed on the fixing platform 154 by glue.

[0031] In this embodiment, the first lens assembly 19 is disposed on the base 15. Specifically, the first lens assembly 19 includes a first lens group and a first lens barrel, the first lens group is assembled in the first lens barrel, the outer side of the first lens barrel is provided with an external thread, the inner wall of the base 15 is provided with an internal thread, and the first lens assembly 19 is fixed in the base 15. The first lens assembly 19 is a fixed-focus lens.

[0032] In this embodiment, the second lens assembly 21 is disposed in the driving device 23, and the driving device 23 is disposed on the base 15, so that the second lens assembly 21 is located on the side of the first lens assembly 19 away from the photosensitive element 13. Specifically, the driving device 23 is disposed on the side of the base 15 away from the circuit board 11. The second lens assembly 21 is a zoom lens. The second lens assembly 21 includes a second lens group and a second lens barrel, and the second lens group is assembled in the second lens barrel.

[0033] In this embodiment, the driving device 23 may be a voice coil motor. Of course, the driving device 23 may also be a driving device made of memory alloy, as long as it can drive the second lens assembly 21 to move up and down for zooming. Specifically, the voice coil motor includes a housing, a magnet, a carrier and a coil. The magnet is arranged on the housing, the coil is arranged on the carrier, and the second lens assembly 21 is fixed on the carrier. By energizing the coil, under the action of the magnet, a magnetic force can be generated to push the carrier to move linearly relative to the housing, thereby realizing the focusing of the second lens assembly 21. Specifically, the housing is fixed on the base 15.

[0034] In this embodiment, the light guide 25 is arranged outside the second lens assembly 21, and the light guide 25 is annular, surrounding the outside of the entire second lens assembly 21. The light guide 25 guides the light toward the optical axis of the second lens assembly 21, which can fill in the light for the camera module and improve the imaging effect of the camera module; and because the light guide 25 surrounds the second lens assembly 21 in an annular shape, the uniformity of the fill in light can be better, further improving the imaging effect of the camera module. Specifically, the light guide 25 is fixed to the outside of the driving device 23 and partially exposed at the top of the driving device 23. The second lens assembly 21 protrudes to the top of the driving device 23 on the side away from the photosensitive element 13. The height from the end face of the light guide 25 away from the circuit board 11 to the circuit board 11 is greater than the height from the end face of the second lens assembly 21 away from the circuit board 11 to the circuit board 11. In this way, the height of the entire camera module can be well controlled, and the light guide 25 can well guide the light into the second lens assembly 21.

[0035] The light guide 25 includes an upper portion 250 and a lower portion 251. The upper portion 250 is located on the top of the lower portion 251, and at least a portion of the structure of the upper portion 250 is stacked with the lens assembly along the optical axis direction of the lens assembly, and at least a portion of the structure of the upper portion stacked with the lens assembly is annular in cross section. A convex ring 252 is provided on the inner side of the upper portion 250, and the bottom surface of the convex ring 252 is tightly fitted with the top surface of the driving device 23. The upper portion 250 is located above the driving device 23, and the lower portion 251 is located outside the driving device 23, so that the light guide 25 includes a portion surrounding the outer periphery of the portion of the second lens assembly 21 protruding above the driving device 23. In this embodiment, the cross-sections of the outer periphery and the inner side of the upper portion 250 are both circular, the cross-section of the outer periphery of the lower portion 251 is circular, and the cross-section of the inner side is rectangular, and the rectangular inner side of the lower portion 251 matches the rectangular outer periphery of the driving device 23.

[0036] An inclined side surface 253 is provided on the inner side of the top of the upper portion 251 of the light guide 25, and the side surface 253 faces the light incident side of the second lens assembly 21, that is, a trumpet-shaped inclined light emitting surface is formed on the inner side of the edge of the light guide 25 away from the circuit board 11. The inclined side surface 253 can better guide the light toward the optical axis of the second lens assembly 21. Specifically in this embodiment, the side surface 253 is a conical surface.

[0037] A mounting portion 254 is also provided at the periphery of the light guide 25, and a glue groove 255 is provided on the mounting portion 254. By providing the glue groove 255, glue can be poured into the glue groove 255 to form a glue portion, so that the cover ring 29 is bonded to the light guide 25, thereby reducing the problem of glue creeping to the outer peripheral surface of the light guide 25 due to capillary phenomena during gluing, thereby affecting the appearance and light guiding effect. Specifically, the mounting portion 254 is provided at the periphery of the lower portion 251. Specifically in the present embodiment, a plurality of mounting portions 254 are uniformly arranged along the circumference of the light guide 25. More specifically, the glue groove 255 is provided at the top of the mounting portion 254, and the glue groove 255 is arc-shaped, and all the glue grooves 255 on the plurality of mounting portions 254 are located on the same circumference.

[0038] The outer side of the light guide 25 is provided with an inclined outer side surface 256 , and the inner side surface of the cover ring 29 is in contact with the outer side surface 256 of the light guide 25 . Specifically, the mounting portion 254 protrudes out of the outer side surface 256 .

[0039] A groove 258 is provided at the bottom of the light guide 25 facing the light source assembly 27. Specifically, the groove 258 is provided in the lower portion 251 of the light guide 25. There are multiple grooves 258 on the light guide 25, each groove 258 includes multiple accommodating parts, and the accommodating parts of each groove 258 are interconnected. In the direction perpendicular to the optical axis direction of the lens assembly (i.e., the thickness direction of the light guide 25), each accommodating part is basically located in the middle position of the light guide 25, that is, for each accommodating part, the distance to the inner side of the light guide 25 and the distance to the outer side of the light guide 25 are basically equal. More specifically, each groove 258 includes three accommodating parts, and the middle accommodating part is staggered front and back with the other two accommodating parts.

[0040] A fixing post 259 is further disposed at the bottom of the light guide member 25 facing the light source assembly 27 . The four fixing posts 259 are disposed at corresponding positions of the mounting portion 254 , respectively.

[0041] In this embodiment, the light source assembly 27 is arranged at the bottom of the light guide 25. In this way, the light of the light source assembly 27 can better enter the light guide 25, achieve a better fill light effect, and thus improve the imaging effect of the camera module. Specifically, the light source assembly 27 includes a plurality of light sources 272, and the plurality of light sources 272 are circumferentially arranged at the bottom of the light guide 25. More specifically, in the thickness direction of the light guide 25 (it can also be said to be the radial direction of the light guide 25), each light source 272 is basically located in the middle position of the light guide 25, that is, for each light source 272, its distance to the inner side of the light guide 25 and its distance to the outer side of the light guide 25 are basically equal, which can improve the light guiding uniformity of the light guide 25.

[0042] The light source assembly 27 also includes a circuit board 274, and a plurality of light sources 272 are fixed on the circuit board 274. The circuit board 274 includes a rectangular main body with an opening in the middle, and the light source 272 is arranged on the main body. In order to make each light source 272 basically located in the middle position of the light guide 25, the plurality of light sources 272 on each side of the main body are staggered in the thickness direction of the light guide 25. The light source 272 can be turned on and off by supplying power through the circuit board 274. Specifically, three light sources 272 are arranged on each side of the main body, and the middle light source 272 is closer to the outer edge of the main body relative to the light sources 272 on both sides, and the light sources 272 on both sides are symmetrically arranged on both sides of the middle light source 272. When the main body is annular, all the light sources 272 are arranged on the same arc line concentric with the main body. When the main body is a polygon of other shapes, the plurality of light sources 272 on each side of the main body are also staggered in the front and back.

[0043] The light source 272 is accommodated in the groove 258 at the bottom of the light guide 25, so that the incident area of ​​the light can be increased and the light guiding effect can be enhanced. Specifically, a light source 272 is arranged in each accommodation portion. At the same time, since the light source 272 is accommodated in the groove 258 of the light guide 25, the circuit board 274 can be closely attached to the bottom of the light guide 25, which is conducive to the bonding of the light guide 25 and the circuit board 274.

[0044] The light source assembly 27 further includes a mounting plate 276, on which the main body of the circuit board 274 is disposed. The circuit board 274 further includes a second extension extending from the main body. The mounting plate 276 can be integrally formed with the circuit board 274, or can be formed separately. Specifically, the mounting plate 276 is a rectangular plate, and an opening 277 is provided in the middle of the mounting plate 276, and the mounting plate 276 is sleeved on the periphery of the first lens assembly 19 and the second lens assembly 21.

[0045] A receiving groove 279 is provided on the side of the mounting plate 276 away from the light guide 25, i.e., the bottom of the mounting plate 276. A portion of the receiving groove 279 corresponds to and is close to the outer periphery of the base 15, and another portion corresponds to and is close to the outer periphery of the driving device 23. The adhesive is contained in the receiving groove 279. During installation, the mounting plate 276 is fixed to the base 15 and the driving device 23 after the adhesive is poured and cured in the receiving groove 279. Specifically in this embodiment, the receiving groove 279 extends along the inner edge of the mounting plate 276, i.e., extends along the outer edge of the lens assembly. It can be understood that a plurality of receiving grooves 279 may be intermittently provided at the inner edge of the mounting plate 276, i.e., intermittently provided along the outer edge of the lens assembly.

[0046] The circuit board 274 and the mounting plate 276 are provided with fixing holes 280 corresponding to the fixing columns 259 of the light guide 25 , so as to facilitate the alignment of the light guide 25 and the light source assembly 27 and also play a role in fixing the light guide 25 and the light source assembly 27 .

[0047] In this embodiment, the cover ring 29 is arranged on the top of the light guide 25, and no glue is applied between the outer side surface 256 of the light guide 25 and the surface where the cover ring 29 is in contact. Specifically, the cover ring 29 can be an independent component, or a part of a component directly integrated on the housing of an electronic product such as a mobile phone, or directly a part of the housing. The top of the cover ring 29 protrudes from the top of the light guide 25, thereby forming a depression on the top of the light guide 25. Specifically, the cover ring 29 can be a metal ring.

[0048] The cover ring 29 includes a connecting portion 292 and a matching portion 294. The connecting portion 292 is disposed at the bottom edge of the matching portion 294. The connecting portion 292 is a flat plate, and the matching portion 294 is a cone. The connecting portion 292 covers the adhesive groove 255 of the mounting portion 254 of the light guide 25 and is bonded to the light guide plate 25. The matching portion 294 matches the outer side surface 256 of the light guide plate 25. Specifically, the width of the connecting portion 292 is greater than the width of the adhesive groove 255, so that the adhesive groove 255 is completely covered.

[0049] In this embodiment, the cover plate 31 is disposed on the top of the light guide 25 (i.e., the edge of the light guide 25 away from the circuit board 11), and is located on the side of the second lens assembly 21 away from the photosensitive element 13, so as to protect the first lens assembly 19 and the second lens assembly 21, and prevent the lens assembly from being contaminated or damaged. Specifically, the cover plate 31 is tightly fitted on the top surface of the light guide 25, and is accommodated in the recess formed by the cover ring 29. A glue-containing groove is also formed on the end surface of the light guide 25 where the cover plate 31 is fitted, so that the cover plate 31 is fixed on the light guide 25.

[0050] In this embodiment, the camera module further includes a first protective film 33, which is disposed on the top of the cover plate 31 to protect the cover plate 31. The camera module further includes a second protective film 35 and a third protective film (not shown), the second protective film 35 being disposed on the top of the first lens assembly 19 to protect the first lens assembly 19, and the third protective film being disposed on the top of the second lens assembly 21 to protect the second lens assembly 21.

[0051] In this embodiment, the camera module also includes a mainboard 39, the circuit board 11 is electrically connected to the mainboard 39 through a first connector, and the circuit board 274 is electrically connected to the mainboard 39 through a second connector. Specifically, the first connector includes a first male seat 392 provided on the first extension of the circuit board 11 and a first female seat 393 provided on the mainboard 39, and the first male seat 392 is plugged into the first female seat 393. The second connector includes a second male seat 395 provided on the second extension of the circuit board 274 and a second female seat 396 provided on the mainboard 39, and the second male seat 395 is plugged into the second female seat 396. The first extension and the second extension are respectively fixed with a first steel sheet 398 and a second steel sheet 399. Since the height of the circuit board 274 is relatively high, the second extension needs to be bent to extend to the mainboard 39, and the circuit board 11 is substantially flush with the mainboard 39. The mainboard 39 is also provided with electronic devices such as capacitors. The mainboard 39 can be a printed circuit board.

[0052] The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above in preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A camera module, comprising a circuit board (11), a photosensitive element (13) and a lens assembly, characterized in that: The camera module further comprises a light guide (25), a light source assembly (27) and a cover ring (29); the light sensing element (13) is arranged on the circuit board (11) and is electrically connected to the circuit board (11); the lens assembly is arranged on a side of the light sensing element (13) away from the circuit board (11); at least a part of the structure of the light guide (25) is arranged outside the lens assembly; the light source assembly (27) comprises a light source (272); the cover ring (29) is arranged on the top of the light guide (25); a mounting portion (254) is further arranged at the periphery of the light guide (25); a glue groove (255) is provided on the mounting portion (254); the glue groove (255) is provided with an adhesive portion for connecting the light guide (25) and the cover ring (29); the plurality of mounting portions (254) are arranged along the light guide (25) ) are uniformly arranged in the circumferential direction, the glue groove (255) is opened at the top of the mounting part (254), and all the glue grooves (255) on the multiple mounting parts (254) are located on the same circumference, the light source assembly (27) is arranged at the bottom of the light guide (25), and a groove (258) is opened at the bottom of the light guide (25) facing the light source assembly (27), and the light source (272) is accommodated in the groove (258), there are multiple grooves (258) on the light guide (25), each of the grooves (258) includes multiple accommodating parts, and the accommodating parts of each groove (258) are interconnected, and each of the accommodating parts is located in the middle of the light guide (25) in a direction perpendicular to the optical axis direction of the lens assembly, and each of the accommodating parts is provided with a light source (272).

2. The camera module according to claim 1, wherein: The cover ring (29) comprises a connecting portion (292), the connecting portion (292) being a flat plate, and the connecting portion (292) covers above the glue groove (255) of the mounting portion (254) of the light guide (25).

3. The camera module according to claim 2, wherein: The outer side of the light guide (25) is provided with an inclined outer side surface (256); the cover ring (29) further comprises a conical matching portion (294); the connecting portion (292) is provided at the bottom edge of the matching portion (294); the matching portion (294) matches with the outer side surface (256) of the light guide (25); and the mounting portion (254) protrudes outside the outer side surface (256).

4. The camera module according to claim 2, wherein: The width of the connecting portion (292) is greater than the width of the glue groove (255).

5. The camera module according to claim 1, wherein: The light guide (25) comprises an upper portion (250) and a lower portion (251); a convex ring (252) is provided on the inner side of the upper portion (250); the bottom surface of the convex ring (252) is tightly fitted with the top surface of the lens assembly; the upper portion (250) is located above the lens assembly; the lower portion (251) is located outside the lens assembly; and the mounting portion (254) is provided on the outer periphery of the lower portion (251).

6. The camera module according to claim 1, wherein: The glue groove (255) is in an arc shape.

7. The camera module according to claim 1, wherein: The light source assembly (27) further comprises a circuit board (274) and a mounting plate (276); the light source (272) is arranged on the circuit board (274), and the circuit board (274) is arranged on the mounting plate (276).

8. The camera module according to claim 7, wherein: A fixing column (259) is also provided at the bottom of the light guide (25) facing the light source assembly (27), and fixing holes (280) corresponding to the fixing columns (259) of the light guide (25) are provided on the circuit board (274) and the mounting plate (276).

9. The camera module according to claim 1, wherein: The lens assembly comprises a first lens assembly (19), a second lens assembly (21), a driving device (23) and a base (15); the base (15) is arranged on the circuit board (11); the base (15) forms a cavity (152); the first lens assembly (19) is arranged on the base (15); the second lens assembly (21) is arranged on the driving device (23); the driving device (23) is arranged on a side of the base (15) away from the circuit board (11); the second lens assembly (21) is located on a side of the first lens assembly (19) away from the photosensitive element (13); the first lens assembly (19) is a fixed-focus lens; the second lens assembly (21) is a zoom lens; The second lens assembly (21) protrudes to the top of the driving device (23) on a side away from the photosensitive element (13), and the light guide (25) comprises a portion surrounding the outer periphery of the portion of the second lens assembly (21) protruding to the top of the driving device (23). The height from the end surface of the light guide (25) on the side away from the circuit board (11) to the circuit board (11) is greater than the height from the end surface of the second lens assembly (21) on the side away from the circuit board (11) to the circuit board (11), The lens assembly further comprises a cover plate (31), the cover plate (31) being attached to the end edge of the light guide (25) away from the circuit board (11), a glue containing groove being formed on the end surface where the light guide (25) and the cover plate (31) are attached, and the cover ring (29) is arranged around the outer periphery of the cover plate (31). The light guide (25) is also provided with a trumpet-shaped inclined light-emitting surface on the inner side of the end edge away from the circuit board (11).

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