CN108388826B - Electronic device - Google Patents
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- CN108388826B CN108388826B CN201710063794.XA CN201710063794A CN108388826B CN 108388826 B CN108388826 B CN 108388826B CN 201710063794 A CN201710063794 A CN 201710063794A CN 108388826 B CN108388826 B CN 108388826B
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V40/00—Recognition of biometric, human-related or animal-related patterns in image or video data
- G06V40/10—Human or animal bodies, e.g. vehicle occupants or pedestrians; Body parts, e.g. hands
- G06V40/12—Fingerprints or palmprints
- G06V40/13—Sensors therefor
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Abstract
An electronic device, comprising: the middle shell comprises a first surface and a second surface which are arranged in an opposite mode, a groove is formed in the first surface of the middle shell and penetrates through the middle shell with partial thickness, a first through hole and a second through hole are formed in the bottom of the groove, and the first through hole and the second through hole penetrate through the rest of the middle shell; the image sensor is positioned in the groove; one end of the flexible circuit board is connected with the image sensor, penetrates through the first through hole, bends towards the direction of the second through hole and extends on the second surface; and the light source is positioned on the flexible circuit board at the bottom of the second through hole. In the technical scheme of the invention, the middle shell is used for replacing the rubber frame, so that the production cost of the electronic equipment is reduced, the process difficulty of assembling the electronic equipment is reduced, the yield is improved, and the production efficiency is improved.
Description
Technical Field
The present invention relates to the field of fingerprint imaging, and in particular, to an electronic device.
Background
The fingerprint identification technology collects the fingerprint image of a human body through the imaging device group and then compares the fingerprint image with the existing fingerprint imaging information in the fingerprint identification system to realize identity identification. Due to the convenience of use and the uniqueness of human fingerprints, fingerprint identification technology has been widely applied to various fields, such as: the security inspection field such as public security bureau, customs, etc., the entrance guard system of buildings, and the consumer goods field such as personal computer and mobile phone, etc.
The imaging module who adopts among the fingerprint identification technique has one kind and gathers human fingerprint image through optical image sensor. When fingerprint sensing is carried out, a finger presses on a sensing plane of the optical image sensor, incident light generated by the light source is transmitted to the surface of the finger on the sensing plane, reflection and refraction occur on the surface of the finger, reflected light formed by reflection of the finger is projected onto the optical image sensor, and a fingerprint image of the finger is acquired by the optical image sensor.
However, the electronic device integrated with the optical image sensor in the prior art often has the problems of high process difficulty and high cost.
Disclosure of Invention
The invention provides electronic equipment to reduce processing difficulty and process cost.
To solve the above problems, the present invention provides an electronic device including:
the middle shell comprises a first surface and a second surface which are arranged in an opposite mode, a groove is formed in the first surface of the middle shell and penetrates through the middle shell with partial thickness, a first through hole and a second through hole are formed in the bottom of the groove, and the first through hole and the second through hole penetrate through the rest of the middle shell; the image sensor is positioned in the groove; one end of the flexible circuit board is connected with the image sensor, penetrates through the first through hole, bends towards the direction of the second through hole and extends on the second surface; and the light source is positioned on the flexible circuit board at the bottom of the second through hole.
Optionally, the image sensor has a photosensitive surface parallel to the first surface of the middle shell, and an area on the photosensitive surface where a photosensitive device is formed is an imaging area; the light source is provided with a light emergent surface; the side wall of the second through hole close to the light source is a first side wall; the distance between the boundary of the imaging area close to the light source and the first side wall is a first distance; the distance between the center of the light emitting surface and the light sensing surface is a second distance; a ratio of the first distance to the second distance is greater than 2.9: 1.
Optionally, the first distance is greater than 2.9 mm.
Optionally, the light source is a light emitting diode.
Optionally, the second through hole is larger than the first through hole in size in a square pointing to the first through hole along the second through hole.
Optionally, the electronic device further includes: a protective cover plate on the first side of the middle shell; and a first adhesive layer on a side of the image sensor facing the protective cover plate; the image sensor is attached to the protective cover plate through the first adhesive layer.
Optionally, the material of the first adhesive layer is an optically transparent adhesive.
Optionally, the electronic device further includes: a second adhesive layer on the second side of the middle shell; the flexible circuit board is fixedly connected with the second surface of the middle shell through the second bonding layer.
Optionally, the second adhesive layer is made of a double-sided adhesive or a thermosetting adhesive.
Optionally, the second adhesive layer is disposed around the first through hole and the second through hole and located on the second surface between the first through hole and the second through hole.
Compared with the prior art, the technical scheme of the invention has the following advantages:
a groove, a first through hole and a second through hole are formed in the middle shell, and the first through hole and the second through hole are located at the bottom of the groove; and the flexible circuit board with one end connected with the image sensor in the groove penetrates through the first through hole, is bent towards the direction of the second through hole and extends on the second surface. Fixing the shape of the flexible circuit board by using the first through hole and the second through hole through a method of arranging a groove and the first through hole and the second through hole in the middle shell, and playing a supporting role between the flexible circuit board and the image sensor; the image sensor is positioned in the groove, the light source is positioned on the flexible circuit board at the bottom of the second through hole, the size of the second through hole and the thickness of the middle shell can influence the relative position relationship between the light source and the image sensor, so the middle shell can also play a role in adjusting the position between the light source and the image sensor; compared with the technical scheme with the rubber frame, the middle shell replaces the rubber frame, and the use of the rubber frame is omitted, so that the production cost of the electronic equipment is reduced; the technical scheme of the invention can effectively reduce the process difficulty of the electronic equipment assembly, effectively reduce the process cost, be beneficial to improving the yield and be beneficial to improving the production efficiency.
Drawings
FIG. 1 is a schematic diagram of a three-dimensional structure of a fingerprint imaging module;
FIG. 2 is a schematic cross-sectional view of the fingerprint imaging module shown in FIG. 1 along line aa;
FIG. 3 is a schematic three-dimensional structure diagram of an embodiment of an electronic device of the present invention;
FIG. 4 is an enlarged schematic view of the inner structure of the ring 101 in the embodiment of FIG. 3;
FIG. 5 is a schematic cross-sectional view along line AA in the embodiment of FIG. 3;
fig. 6 is an enlarged schematic view of the structure inside the ring 102 in the embodiment shown in fig. 5.
Detailed Description
As can be seen from the background art, the electronic device integrated with the optical image sensor in the prior art has the problems of high process difficulty and high cost. The reason that its processing degree of difficulty is big, the high problem of processing cost is analyzed to present combination fingerprint imaging module:
referring to fig. 1 and 2, a schematic structural diagram of a fingerprint imaging module integrated with an optical image sensor is shown. Fig. 1 is a schematic three-dimensional structure diagram of the fingerprint imaging module 10; fig. 2 is a schematic cross-sectional view of the fingerprint imaging module 10 shown in fig. 1 along line aa.
a protective cover plate 11 for protection; an image sensor 12 having a first face facing the protective cover 11 and a second face opposite to the first face, the image sensor 12 being bonded to the protective cover 11 by an Optically Clear Adhesive (OCA glue) 13 on the first face; an Integrated Circuit (IC) 18 is fixed on the surface of the image sensor 12 by an Anisotropic Conductive Film (ACF) process; one end of the flexible circuit board 14 is connected with the first surface of the image sensor 12 through an anisotropic conductive film process, and the other end of the flexible circuit board is bent to the second surface of the image sensor 12 and fixedly connected with the second surface of the image sensor 12; the light source 15 is connected to the flexible circuit board 14 by Surface Mount Technology (SMT), connected to the image sensor 12 by the flexible circuit board 14, and fixed to a side of the image sensor 12 away from the protective cover 11.
In order to realize the connection between the flexible circuit board 14 and the second surface of the image sensor 12, the fingerprint imaging module 10 further includes a rubber frame 16. The rubber frame 16 is firstly attached to the second surface of the image sensor 12 through a double-sided adhesive tape, and the flexible circuit board 14 is attached to the surface of the rubber frame 16 opposite to the image sensor 12 through the double-sided adhesive tape after being bent, so that the flexible circuit board 14 is fixed, and a supporting function is realized between the image sensor 12 and the flexible circuit board 14.
As shown in fig. 2, the light source 15 is typically a light emitting diode adopting a side-emitting point light source light emitting mode, that is, the incident light generated by the light source 15 is emitted in a cone shape from the light emitting center of the light source 15: the center point has the largest brightness, and the closer to the periphery, the weaker the brightness. When the angle between the light-emitting direction and the center is in the range of 50 ° to 60 °, the brightness of the light is reduced to about half of the brightness of the light-emitting center.
When the fingerprint imaging module 10 shown in fig. 2 works, a finger 19 presses on the protective cover plate 11, and the ridge line of the fingerprint contacts the protective cover plate 11, so that the total reflection condition of light on the surface of the protective cover plate 11 is destroyed, and therefore, the incident light projected to the ridge line position cannot be totally reflected on the surface of the protective cover plate 11; the valley line and the surface of the protective cover 11 have a certain gap, so that the total reflection condition is maintained, and the incident light projected to the valley line position can still be totally reflected. Therefore, the light intensity of the reflected light formed by the reflection of the finger has a certain distribution on the surface of the image sensor 12, and the image sensor 12 can obtain the fingerprint image after processing by sensing the light intensity distribution of the reflected light and converting the light intensity into an electric signal.
Due to the light emitting characteristics of the light source 15, in the image sensor 12, a partial area close to the light source 15 may be too bright and saturated due to too large light intensity of reflected light exceeding the sensing range of the image sensor 12, and the image sensor 12 cannot sense light intensity distribution, so that the fingerprint image acquisition fails, and becomes a first failure area; in the partial region far from the light source 15, the reflected light intensity is too small, which may cause the image sensor 12 to fail to obtain a clear fingerprint image, and thus becomes a second failure region. The region between the first dead zone and the second dead zone is an effective region where a clear fingerprint image can be obtained.
The image sensor 12 senses light intensity through a photo-sensing device disposed on the first face, thereby obtaining a light intensity distribution of reflected light projected to the surface. The active area is required to be located at a position on the first side of the image sensor 12 where the photosensitive device is located in order to enable the image sensor 12 to obtain a clear fingerprint image and thus improve the performance of the fingerprint imaging module 10.
The relative position between the light source 15 and the image sensor 12 affects the incident angle of the incident light projected to the finger and the position of the reflected light projected to the surface of the image sensor 12, thereby affecting the position of the active area on the first side of the image sensor 12. The relative positional relationship between the light source 15 and the image sensor 12 is related to the size of the adhesive frame 16 in the direction perpendicular to the first face. The glue frame 16 is used to adjust the distance between the light source 15 and the image sensor 12, in addition to being used to secure the flexible circuit board 14 and to support the image sensor 12 and the flexible circuit board 14.
But with the improvement of device integration level, the size of fingerprint imaging module is littleer and littleer. Correspondingly, among the fingerprint imaging module, the size of each part also reduces thereupon. Wherein the size of the glue frame 16 is also getting smaller and smaller. The reduction of gluey frame 16 size has increased gluey frame 16 assembly process's degree of difficulty to restricted the cost and the technology degree of difficulty of fingerprint imaging module, restricted the improvement of production efficiency and yield.
In order to solve the technical problem, the invention provides the electronic equipment, and the middle shell is used for replacing the rubber frame, so that the production cost of the electronic equipment is reduced, and the difficulty of an assembly process is reduced.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Referring to fig. 3 to 6, schematic structural diagrams of an embodiment of the electronic device of the invention are shown.
Wherein FIG. 3 is a schematic three-dimensional structure of the electronic device; FIG. 4 is an enlarged schematic view of the inner structure of the ring 101 in the embodiment of FIG. 3; FIG. 5 is a schematic cross-sectional view along line AA in the embodiment of FIG. 3; fig. 6 is an enlarged schematic view of the structure inside the ring 102 in the embodiment shown in fig. 5.
The electronic device 100 includes:
the middle shell 110, the middle shell 110 includes a first surface 111 (shown in fig. 4) and a second surface 112 (shown in fig. 5) that are opposite to each other, a groove 113 (shown in fig. 4) is provided in the first surface 111 of the middle shell 110, the groove 113 penetrates through a part of the thickness of the middle shell 110, a first through hole 115 and a second through hole 114 are provided at the bottom of the groove 113, and the first through hole 115 and the second through hole 114 penetrate through the remaining middle shell 100; an image sensor 120 (shown in FIG. 6) located within the recess 113; a flexible circuit board 140, one end of which is connected to the image sensor 120, penetrates through the first through hole 115, bends toward the second through hole 114, and extends on the second surface 112; and the light source 130 is positioned on the flexible circuit board 140 at the bottom of the second through hole 115.
The middle case 110 is used for fixing the shape of the flexible circuit board 140, and plays a supporting role between the flexible circuit board 140 and the image sensor 120; the image sensor 120 is located in the groove 113, the light source 130 is located on the flexible circuit board 140 at the bottom of the second through hole 114, the distance between the light source 130 and the image sensor 120 is related to the depth of the second through hole 114, the size of the second through hole 114 and the thickness of the middle shell 110 influence the distance between the light source 130 and the image sensor 120, so the middle shell 110 and the second through hole 114 can also function to adjust the relative position relationship between the light source 130 and the image sensor 120; compared with the technical scheme with the rubber frame, the middle shell 110 replaces the rubber frame, and the use of the rubber frame is omitted, so that the production cost of the electronic equipment is reduced; the use of a rubber frame is omitted, the assembly process of the rubber frame is omitted, and the assembly process difficulty of the middle shell 110 is smaller than that of the rubber frame because the volume of the middle shell 110 is larger than that of the rubber frame, so that the technical scheme of the invention can effectively reduce the assembly process difficulty of the electronic equipment, can effectively reduce the process cost, is beneficial to improving the yield and is beneficial to improving the production efficiency.
The structure of the electronic device 100 will be described in detail below with reference to the accompanying drawings.
In this embodiment, the electronic device 100 is a portable electronic device such as a mobile phone or a tablet computer, and the electronic device 100 has a fingerprint identification function. In other embodiments of the present invention, the electronic device may also be other non-portable electronic devices.
The middle case 110 is used for fixing hardware of the electronic device 100.
Various hardware of the electronic device 100 is fixed to the middle housing 110 by means of adhesive, screw threads, or the like. In this embodiment, the electronic device 110 is a mobile phone, and hardware such as a display screen of the mobile phone and a circuit board provided with a chip are fixed on the middle shell 110.
Specifically, the middle shell 110 includes a first surface 111 and a second surface 112 (as shown in fig. 5) that are disposed opposite to each other. A groove 113 is formed in the first surface 111 of the middle shell 110, and a first through hole 115 and a second through hole 114 are formed at the bottom of the groove 113.
The recess 113 is used for accommodating the image sensor 120; the first through hole 115 is used for providing a space for the flexible circuit board 140 to penetrate through the middle shell 110; the second through hole 114 is used for accommodating the light source 130 and also for providing a passage for the incident light generated by the light source 130 to pass through the middle shell 110.
The groove 113 is positioned in the first surface 111 of the middle shell 110 and penetrates through part of the thickness of the middle shell 110; the first through hole 115 and the second through hole 114 are located at the bottom of the groove 113, and penetrate through the middle shell 110 with the remaining thickness. The groove 113, the first through hole 115 and the second through hole 114 constitute a stepped groove in a through hole shape, that is, a stepped structure is formed between the side wall of the groove 113 and the side wall of the second through hole 114 and between the side wall of the groove 113 and the side wall of the first through hole 115.
The image sensor 120 located in the groove 113 is used for collecting reflected light carrying fingerprint information and converting an optical signal of the reflected light into an electrical signal to obtain a fingerprint image. By disposing the image sensor 120 in the groove 113, the image sensor 120 can be prevented from being squeezed.
The image sensor 120 is an optical image sensor. The image sensor 120 has a photosensitive surface on which photosensitive devices are formed, and an area on the photosensitive surface on which the photosensitive devices are formed is an image forming area. When the reflected light carrying the fingerprint information is projected into the imaging area, the reflected light is collected by the photosensitive device, so that a fingerprint image is obtained.
Note that, the electronic apparatus 100 further includes: a protective cover plate 201 on the first surface 111 of the middle case 110; and a first adhesive layer 150 (shown in fig. 6) on a side of the image sensor 120 facing the protective cover 201; the image sensor 120 is attached to the protective cover 201 by the first adhesive layer 150.
In this embodiment, the electronic device 100 has a display screen, the display screen is located on the first surface 110 of the middle shell 110, and a glass cover plate of the display screen extends to a position where the groove 113 is located, so that the protective cover plate 201 is the glass cover plate of the display screen. In other embodiments of the present invention, the protective cover plate may be made of other materials. Specifically, the glass cover of the display is the front cover of the mobile phone, so the image sensor 120 is attached to the front cover of the mobile phone through the first adhesive layer 150.
The first adhesive layer 150 is used to realize the fixed connection between the image sensor 120 and the protective cover 201, thereby realizing the fixation of the image sensor 120.
In this embodiment, the photosensitive surface of the image sensor 120 faces the protective cover 201, so the first adhesive layer 150 is located on the photosensitive surface, and therefore both incident light and reflected light for obtaining a fingerprint image need to transmit the first adhesive layer 150, so the material of the first adhesive layer 150 is Optically clear adhesive (OCA glue).
The optical transparent adhesive has the advantages of high clarity, high light transmittance, high adhesion, high weather resistance, water resistance, high temperature resistance, ultraviolet resistance and the like; in addition, the thickness of the optically transparent adhesive is controllable, and uniform spacing can be provided; and no yellowing, peeling and deterioration will occur after long-term use. Therefore, the first adhesive layer 150 made of an optically transparent adhesive material can reduce the influence of the existence of the first adhesive layer 150 on the light collection function of the image sensor 120, thereby facilitating the improvement of the connection strength between the image sensor 120 and the protective cover plate 201 and the stability of the electronic device.
It should be noted that although the image sensor 120 is fixedly connected to the protective cover 201 through the first adhesive layer 150, the image sensor 120 is also located in the groove 113, and the groove 113 is used to accommodate the image sensor 120, so that the position where the image sensor 120 is attached to the protective cover 201 corresponds to the position of the groove 113.
It should be noted that the image sensor 120 is attached to the protective cover 201 by the first adhesive layer 150, so that the image sensor 120 is fixed. In addition, in order to avoid the image sensor 120 from being squeezed, and in addition, in consideration of the influence of the processing precision, in this embodiment, the image sensor 120 is suspended in the groove 113, that is, the distance between the surface of the protective cover 201 facing the middle shell 110 and the bottom of the groove 113 is greater than the thickness of the image sensor 120. By the method, the process difficulty of assembling and fixing the image sensor 120 can be effectively reduced, and the assembly efficiency and the yield can be improved. In other embodiments of the present invention, the image sensor may also be fixed to the bottom of the groove.
The flexible circuit board 140, one end of which is connected to the image sensor 120, is used to connect the image sensor 120 to an external circuit, so as to supply power to the image sensor 120 and to read and process an electrical signal generated by the image sensor 120, so as to obtain a fingerprint image.
Other hardware such as a circuit board and a chip of the electronic device 100 are fixed on the second surface 112 of the middle shell 110, the flexible circuit board 140 is in a strip shape, and one end of the flexible circuit board is connected to the image sensor 120 through an anisotropic conductive film process; the flexible circuit 140 penetrates through the first through hole 115 and is bent from the first surface 111 to the second surface 112 of the middle shell 110; the other end of the flexible circuit board 140 is located on the second surface of the middle shell 110, and is connected to the circuit board of the electronic device 100, so as to connect the image sensor 120 to an external circuit. In this embodiment, the flexible Circuit Board 140 and a Printed Circuit Board (PCB) of the mobile phone are electrically connected through a connector (connector) or by soldering.
After being bent to the second surface 112 of the middle shell 110, the flexible circuit board 140 is bent toward the second through hole 114 and extends on the second surface 112. In this embodiment, the flexible circuit board 140 extends on the second surface 112 to a side of the second through hole 114 away from the first through hole 115. The flexible circuit board 140 is also located at the bottom of the second light flux 114.
The electronic device 100 further comprises: a second adhesive layer 160 on the second side 112 of the middle shell 110; the flexible circuit board 140 is attached to the second surface 112 through the second adhesive layer 160.
Specifically, the material of the second adhesive layer 160 is a double-sided adhesive or a thermosetting adhesive. The double-sided adhesive tape or the thermosetting adhesive tape has low cost and good adhesive performance, so that the cost of the electronic device and the process difficulty can be reduced by setting the material of the second adhesive layer 160 as the double-sided adhesive tape or the thermosetting adhesive tape.
In order to improve the connection strength between the flexible circuit board 140 and the second surface 112 of the middle shell 110, the second adhesive layer 160 is disposed around the second through hole 114 and the first through hole 115 and is located on the second surface 112 between the second through hole 114 and the first through hole 115 to increase the area of the second adhesive layer 160 and increase the adhering area between the flexible circuit board 140 and the middle shell 110, so as to enhance the connection strength between the flexible circuit board 140 and the middle shell 110.
The bottom of the second through hole 114 is also provided with the light source 130 for generating incident light. Specifically, the light source 130 is fixed on the flexible circuit board 140 at the bottom of the second light guide 114 by a surface mounting technique. The second through hole 114 is used to accommodate the light source 130 and also to provide a passage for the incident light generated by the light source 130 to pass through the middle case 110.
It should be noted that, since the second through hole 114 is used for transmitting incident light; the first through hole 115 is used to provide a space for the flexible circuit board 140 to penetrate through the middle case 110, and the thickness of the flexible circuit board 140 is limited. Therefore, in the embodiment, the area of the second through hole 114 is larger than that of the first through hole 115 in a plane parallel to the first surface 111, so as to increase the incident light transmission channel, enhance the light intensity of the incident light to improve the quality of the fingerprint image obtained by the image sensor 120, reduce the volume of the electronic device 100, and improve the integration level.
In addition, in this embodiment, the assembling sequence of the electronic device 100 is as follows: first, one end of the flexible circuit board 140 is connected to the image line photosensor 120 and the light source 130 is fixed to the flexible circuit board 140; then, the image sensor 120 is attached to the protective cover 201 through the first adhesive layer 150; then, the flexible circuit board 140 not connected to the image sensor 120 is passed through the first through hole 115, and the protective cover plate 201 is attached to the first surface of the middle shell 110 by means of double-sided adhesive tape or thermosetting adhesive tape; then, the flexible circuit board 140 bent to the second surface 112 of the middle shell 110 is bent toward the second through hole 114 and fixed to the second surface 112 of the middle shell 110 by the second adhesive layer 160. The first through hole 115 is directed toward the second through hole 114, and the size of the first through hole 115 is greater than the thickness of the light source 130. That is, the first through hole 115 is required to enable the flexible circuit board 140 to pass through, and in the passing process, the light source 130 connected to the flexible circuit board 140 is not affected, so that the phenomenon that the light source 130 is damaged in the assembly process is reduced, and the yield is improved.
The light source 130 has a light emitting surface, and the incident light is emitted from a light emitting center of the light emitting surface; the incident light passes through the second through hole 114, and transmits through the image sensor 120 and the protective cover 201, and is projected to a finger, and reflected light carrying fingerprint information is formed by reflection on the surface of the finger.
In this embodiment, the light source 130 is a light emitting diode. Specifically, the light source 130 is a light emitting diode adopting a side light emitting point light source light emitting mode, that is, the light emitting surface of the light source 130 is perpendicular to the light sensing surface of the image sensor 120, and the incident light generated by the light source 130 is emitted from the light emitting surface of the light source 130 in a cone shape: the center point has the largest brightness, and the brightness is smaller toward the periphery. Specifically, the light emitting surface of the light source 130 faces the imaging area of the image sensor 120.
Due to the light emitting characteristics of the light source 130, the relative position relationship between the image sensor 120 and the light source 130 may affect the quality of the fingerprint image obtained by the image sensor 120.
If the distance between the light emitting surface of the light source 130 and the imaging area of the image sensor 120 is too small, the intensity of the incident light projected to the finger is too large, so that the intensity of the formed reflected light is too large and exceeds the maximum value of the sensing range of the photosensitive device of the image sensor 120, and therefore, the phenomenon of over-brightness and saturation occurs, and the image sensor 120 cannot sense the intensity distribution, so that the fingerprint image acquisition fails; if the distance between the light emitting surface of the light source 130 and the imaging area of the image sensor 120 is too large, the intensity of the incident light projected to the finger is too small, so that the intensity of the formed reflected light is too small and is lower than the minimum value of the sensing range of the photosensitive device of the image sensor 120, and the problem that a clear fingerprint image cannot be obtained easily occurs.
The distance between the light source 130 and the imaging area of the image sensor 120 needs to be set within a proper range so that the intensity of the formed reflected light is within a reasonable range, and the image sensor 120 obtains a fingerprint image according to the intensity distribution of the reflected light.
In this embodiment, according to the light-emitting divergence angle of the light source 130 and the properties of the light-sensing device of the image sensor, when the ratio of the distance between the boundary of the imaging region close to the side of the light source 130 and the light-emitting surface of the light source 130 to the distance between the center of the light-emitting surface of the light source 130 and the light-sensing surface is in the range of 2.8:1 to 3:1, the image line photosensor 120 can obtain a clearer fingerprint image.
The sidewall of the second through hole 114 close to the light source 130 is a first sidewall; the distance between the boundary of the imaging region close to the light source 130 and the first side wall is a first distance; the distance between the center of the light emitting surface and the light sensing surface is a second distance, and the ratio of the first distance to the second distance is greater than 2.9: 1. When the ratio of the first distance to the second distance is within the above range, the intensity of the reflected light projected to the image sensor 120 can be made appropriate, thereby facilitating a clearer fingerprint image.
Specifically, the distance between the center of the light emitting surface of the light source 130 and the light sensing surface of the image sensor 120 is about 1mm, so the distance between the boundary of the imaging area close to the light source 130 and the first sidewall is greater than 2.9mm, that is, the first distance is greater than 2.9 mm.
It should be noted that, in this embodiment, the image sensor 120 is fixedly connected to the protective cover 201 through the first adhesive layer 150, so the groove 113 is only used to provide a space for accommodating the image sensor 120. In other embodiments of the present invention, when the image sensor is fixed at the bottom of the groove, the groove is not only used to provide a space for accommodating the image sensor, but also used to support and fix the image sensor. In this case, in a plane parallel to the first face, the size of the first through hole is smaller than that of the image sensor, and therefore the first side wall is located between a boundary of the imaging region near the light source and a boundary of the image sensor to improve the support stability of the groove bottom to the image sensor.
In summary, in the technical scheme of the invention, the middle shell is provided with the groove, and the first through hole and the second through hole are positioned at the bottom of the groove; and the flexible circuit board with one end connected with the image sensor in the groove penetrates through the first through hole and bends towards the direction of the second through hole, and the flexible circuit board extends to a second surface of one side of the second through hole, which is far away from the first through hole. Fixing the shape of the flexible circuit board by using the first through hole and the second through hole through a method of arranging a groove and the first through hole and the second through hole in the middle shell, and playing a supporting role between the flexible circuit board and the image sensor; the image sensor is positioned in the groove, the light source is positioned on the flexible circuit board at the bottom of the second through hole, the size of the second through hole and the thickness of the middle shell can influence the relative position relationship between the light source and the image sensor, so the middle shell can also play a role in adjusting the position between the light source and the image sensor; compared with the technical scheme with the rubber frame, the middle shell replaces the rubber frame, and the use of the rubber frame is omitted, so that the production cost of the electronic equipment is reduced; the technical scheme of the invention can effectively reduce the process difficulty of the electronic equipment assembly, effectively reduce the process cost, be beneficial to improving the yield and be beneficial to improving the production efficiency.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. An electronic device, comprising:
the middle shell comprises a first surface and a second surface which are arranged in an opposite mode, a groove is formed in the first surface of the middle shell and penetrates through the middle shell with partial thickness, a first through hole and a second through hole are formed in the bottom of the groove, and the first through hole and the second through hole penetrate through the rest of the middle shell;
the image sensor is positioned in the groove;
one end of the flexible circuit board is connected with the image sensor, penetrates through the first through hole, bends towards the direction of the second through hole and extends on the second surface;
and the light source is positioned on the flexible circuit board at the bottom of the second through hole, and incident light generated by the light source is transmitted through the second through hole to the middle shell so as to acquire a fingerprint image.
2. The electronic device of claim 1, wherein the image sensor has a photosensitive surface parallel to the first surface of the middle housing, and an area on the photosensitive surface where the photosensitive device is formed is an imaging area;
the light source is provided with a light emitting surface, and the light emitting surface of the light source is vertical to the light sensing surface of the image sensor;
the side wall of the second through hole close to the light source is a first side wall;
the distance between the boundary of the imaging area close to the light source and the first side wall is a first distance;
the distance between the center of the light emitting surface and the light sensing surface is a second distance;
a ratio of the first distance to the second distance is greater than 2.9: 1.
3. The electronic device of claim 2, wherein the first distance is greater than 2.9 mm.
4. The electronic device of claim 1, wherein the light source is a light emitting diode.
5. The electronic device of claim 1, wherein a size of the second via is larger than a size of the first via in a direction in which the second via points toward the first via.
6. The electronic device of claim 1, wherein the electronic device further comprises: a protective cover plate on the first side of the middle shell; and a first adhesive layer on a side of the image sensor facing the protective cover plate;
the image sensor is attached to the protective cover plate through the first adhesive layer.
7. The electronic device of claim 6, wherein a material of the first adhesive layer is an optically clear adhesive.
8. The electronic device of claim 1, wherein the electronic device further comprises: a second adhesive layer on the second side of the middle shell;
the flexible circuit board is fixedly connected with the second surface of the middle shell through the second bonding layer.
9. The electronic device according to claim 8, wherein a material of the second adhesive layer is a double-sided tape or a thermosetting tape.
10. The electronic device of claim 8, wherein the second adhesive layer is disposed around the first via and the second via and on the second side between the first via and the second via.
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