CN111341204B

CN111341204B - Display device

Info

Publication number: CN111341204B
Application number: CN202010101176.1A
Authority: CN
Inventors: 陈信学; 刘品妙; 黄任伟
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2019-07-24
Filing date: 2020-02-19
Publication date: 2022-02-18
Anticipated expiration: 2040-02-19
Also published as: CN111341204A; TWI710938B; TW202105142A

Abstract

The invention discloses a display with a fingerprint sensor. The display comprises a transparent column body, an inner column body, a flexible display and a fingerprint sensor. The transparent cylindrical body is provided with an accommodating space and comprises an axial outer surface and an axial inner surface. The inner column body is arranged in the accommodating space. In the first state, the flexible display is coiled along the inner cylinder and is accommodated in the accommodating space, and in the second state, the flexible display is stretched out of the transparent cylinder from the inner cylinder. The fingerprint sensor is arranged on the axial outer surface and receives the fingerprint sensing light source entering the axial inner surface so as to carry out fingerprint identification.

Description

Display device

Technical Field

The present invention relates to a display, and more particularly, to a flexible display having a fingerprint sensor.

Background

Conventional flexible displays include, for example: the scroll display mainly comprises a flexible panel and a storage device, wherein the flexible panel comprises a display panel which can be curled or bent, the display panel of the type can have the display function of a full screen when being unfolded, and when being closed or standby, the display panel is curled or folded into the storage device through the characteristic of flexibility, so that the occupied space of the display panel is reduced, and the carrying convenience of the whole display is improved. The receiving device may be a housing with different accommodating spaces, such as a square or rectangular housing, or a cylindrical or pen-shaped structure, but all have an opening on one side for pulling out or retracting the flexible panel.

In the prior art, the flexible panel may be rolled back in different ways according to different receiving spaces when being stored, but when the flexible panel is to be opened for use, an unlocking function is mostly set to increase the safety in operation, and the flexible panel can be pulled out for use after the unlocking is successful, or the flexible panel can be used only by unlocking first after being pulled out first. Therefore, in the prior art, a locking structure is added to the housing structure to increase the operation safety, but the design of the locking structure directly increases the volume and weight of the storage device, and still has room for improvement.

In view of the foregoing, the conventional reel display still has a drawback in terms of the setup of the unlocking function and the safety of the actual operation, so that the present invention improves the drawbacks of the prior art by designing a reel display with a fingerprint sensor, thereby ensuring that the safety performance of the device identification meets the requirements and further enhancing the industrial implementation.

Disclosure of Invention

In view of the above problems in the prior art, it is an object of the present invention to provide a scroll display having a fingerprint sensor, which has a multi-finger recognition mode and uses the conventional structure and light source to form a multi-finger recognition area, thereby solving the problems of insufficient safety and excessive hardware installation cost of the conventional scroll display.

In accordance with the above objectives, embodiments of the present invention provide a display. It includes a transparent column, an inner column, a flexible display and a fingerprint sensor. The transparent column has a containing space, and the transparent column comprises an axial outer surface and an axial inner surface. The inner cylinder is arranged in the accommodating space and faces the axial inner surface. One side of the flexible display is connected with the inner cylinder, and the flexible display is coiled along the inner cylinder and is contained in the containing space in the first state, or the flexible display is stretched out of the transparent cylinder from the inner cylinder in the second state. The fingerprint sensor is arranged on the axial outer surface and receives the fingerprint sensing light source entering the axial inner surface so as to provide the fingerprint sensor for fingerprint identification.

Specifically, the flexible display may include a flexible circuit board and a display panel, the display panel is disposed on the flexible circuit board, in a first state, the display panel and the flexible circuit board are overlapped and wound on the inner post, in a second state, the display panel is located between the flexible circuit board and the inner post, and the fingerprint sensing light source is disposed on the flexible circuit board.

Specifically, the fingerprint sensor can sense at least two objects, and the areas occupied by the at least two objects are different.

Specifically, the inner cylinder may be eccentrically disposed, the inner cylinder has a first axis and the transparent cylinder has a second axis, and a distance from the first axis to the fingerprint sensor is smaller than a distance from the second axis to the fingerprint sensor.

Specifically, the fingerprint sensing light source can be disposed on the inner cylinder facing the fingerprint sensor.

In accordance with the above objects, another embodiment of the present invention provides a display. It includes a transparent column, an inner column, a flexible display and a fingerprint sensor. The transparent column has a containing space, and the transparent column comprises an axial outer surface and an axial inner surface. The inner cylinder is arranged in the accommodating space and faces the axial inner surface. One side of the flexible display is connected with the inner cylinder, and the flexible display is coiled along the inner cylinder and is contained in the containing space in the first state, or the flexible display is stretched out of the transparent cylinder from the inner cylinder in the second state. The fingerprint sensor is arranged on the axial inner surface and receives the fingerprint sensing light source from the accommodating space so as to provide the fingerprint sensor for fingerprint identification.

In view of the above, the display disclosed in the embodiment of the invention can achieve multi-finger fingerprint identification through the multi-finger fingerprint identification area, thereby improving the identification security. Meanwhile, the surface of the transparent columnar body is used for arranging the fingerprint sensor, and the inner columnar body or the flexible display is used for providing a fingerprint sensing light source, so that the additional arrangement of a fingerprint sensing device on the display is reduced, and the hardware arrangement cost is reduced.

Drawings

In order to make the technical features, contents and advantages of the present invention, and the effects achieved thereby, more obvious, the present invention will be described in detail with reference to the accompanying drawings, and in the following embodiments:

fig. 1A and 1B are schematic views of a display according to an embodiment of the invention.

Fig. 2 is a schematic diagram of the eccentric arrangement of the inner cylinder according to the embodiment of the invention.

Fig. 3 is a schematic diagram of a fingerprint sensing area according to an embodiment of the invention.

Fig. 4 is a schematic diagram of a display according to another embodiment of the invention.

Fig. 5A and 5B are schematic views of a fingerprint sensor disposed on an axial inner surface according to an embodiment of the invention.

Fig. 6A and 6B are schematic views of a fingerprint sensor disposed on an axial outer surface according to an embodiment of the invention.

The reference numerals are explained below:

10. 11, 12, 13: display device

20. 60: transparent columnar body

21: containing space

22: opening of the container

23: first axle center

201. 601, a step of: axial outer surface

202. 602: axial inner surface

30. 32, 70: inner column

31: second axle center

40: flexible display

401: display panel

402: flexible circuit board

50: fingerprint sensor

51: fingerprint identification area

61: protective layer

90: hand part

91: first knuckle

92: second finger joint

93: finger(s)

H: height

ITO: transparent conductive film

M: metal layer

M1: first state

M2: second state

R1, R2: distance between two adjacent plates

SRO: photosensitive layer

T: transistor with a metal gate electrode

W: width of

Detailed Description

In order to facilitate understanding of technical features, contents, advantages and effects achieved by the present invention, the present invention is described in detail below with reference to the accompanying drawings in the form of embodiments, and the drawings used in the present invention are only for illustrative purposes and assistance of description, and are not necessarily true to scale and precise arrangement after the present invention is implemented, and therefore, the present invention should not be interpreted and limited in the scope of the actual implementation by the scale and arrangement relationship of the attached drawings.

In the drawings, the thickness or width of layers, films, panels, regions, light guides, etc. is exaggerated for clarity. Like reference numerals refer to like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected," may refer to physical and/or electrical connections. Further, "electrically connected" or "coupled" may mean that there are additional elements between the elements. Further, it will be understood that, although the terms "first", "second", "third" and/or the like may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should be used to distinguish one element, component, region, layer and/or section from another element, component, region, layer and/or section. Therefore, they are used for descriptive purposes only and not to be construed as indicating or implying relative importance or order relationships thereof.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Please refer to fig. 1A and fig. 1B, which are schematic diagrams of a display according to an embodiment of the invention. FIG. 1A is a schematic view of the display 10 in the first state M1, and FIG. 1B is a schematic view of the display 10 in the second state M2. As shown in the drawings, the display 10 includes a transparent cylinder 20, an inner cylinder 30, a flexible display 40 and a fingerprint sensor 50, wherein the transparent cylinder 20 is made of a transparent material, such as transparent glass. In the present embodiment, the transparent cylindrical body 20 is a cylinder, but the invention is not limited thereto, and in other embodiments, the transparent cylindrical body 20 may also be a polygonal cylinder. The transparent cylindrical body 20 is hollow and has an accommodating space 21, the side surface of the transparent cylindrical body 20 includes an axial outer surface 201 and an axial inner surface 202, the axial inner surface 202 defines the accommodating space 21 inside the transparent cylindrical body 20, and the axial outer surface 201 is provided with the fingerprint sensor 50 to form a fingerprint identification area. The inner cylinder 30 is disposed in the accommodating space 21 inside the transparent cylindrical body 20 and faces the axial inner surface 202, and the inner cylinder 330 can be a rotating reel for converting different states of the flexible display 40 for being rolled, stored or pulled out and unfolded

One side of the flexible display 40 is connected to the inner column 30, as shown in fig. 1A, when the display 10 is in the first state M1, the flexible display 40 is curled to be accommodated in the accommodating space 21, and the display 10 can be in a standby state at this time, when a user needs to operate the display 10 to display a screen, an unlocking procedure needs to be performed first to pull out the flexible display 40 from the opening 22, so that the second state M2 shown in fig. 1B is formed. In the unlocking procedure of this embodiment, the user holds the display 10, places the fingers of the four hands except the thumb in the fingerprint identification area of the fingerprint sensor 50, identifies the fingerprint of the user by the fingerprint sensor 50, and determines whether the user is a qualified user by comparison, if the user is identified as a correct user, the flexible display 40 displays a startup picture or a picture during previous closing, and if the user is identified as an unregistered user, the flexible display 40 maintains a standby state, or the transparent columnar body 20 may be provided with a locking structure, and if the unlocking is not successful, the flexible display 40 cannot be pulled out.

In the present embodiment, the fingerprint sensing light source may be disposed on the flexible display 40, as shown in the figure, the flexible display 40 includes a display panel 401 and a flexible circuit board 402, the display panel 401 is disposed on the flexible circuit board 402, and a display surface of the display panel 401 faces the inner cylinder 30, when the display panel 401 is in the first state M1, the display panel 401 is curled and received along the inner cylinder 30, so that the flexible circuit board 402 faces the axial inner surface 202 of the transparent cylindrical body 20. The flexible circuit board 402 includes a pixel circuit for displaying images and a backlight source, which may be a self-luminous element, and may be used as a fingerprint sensing light source in addition to a light source originally required for providing images displayed by the display panel 401. Since the flexible display 40 is disposed relative to the inner cylinder 30 in such a manner that the flexible circuit board 402 is disposed at the outer side, i.e., facing the axial inner surface 202 of the transparent cylindrical body 20, the distance between the backlight and the fingerprint sensor 50 on the axial outer surface 201 of the transparent cylindrical body 20 can be shortened, and the sensitivity of fingerprint sensing can be improved. In addition, since the fingerprint sensor 50 is disposed on the axial outer surface 201 of the first cylindrical body 20 and the disposed position thereof can overlap the thin film transistor of the display panel 401, compared to the prior art in which the fingerprint sensor is disposed on the display panel, the aperture ratio of the fingerprint sensor and the opaque elements such as the thin film transistor of the display panel are low in the manner of being disposed in parallel. Therefore, the present embodiment also has an advantage of increasing the aperture ratio of the display panel 401.

In addition, when the flexible display 40 is pulled out to be in the second state M2, if the display 10 enters the standby state and needs to be unlocked again, the flexible display 40 is completely pulled out of the transparent pillar 20, and the backlight of the flexible circuit board 402 cannot be provided as the sensing light source. The display 10 may be designed to have a pull-back structure, and a button or spring structure is used to roll the flexible display 40 back to a predetermined length, so that the backlight is directed to the fingerprint sensor 50 again, and a fingerprint sensing light source is provided to perform fingerprint identification, thereby achieving the purpose of unlocking.

Please refer to fig. 2, which is a schematic diagram illustrating an eccentric arrangement of an inner cylinder according to an embodiment of the present invention. As shown in the figure, the display 10 includes a transparent column 20 and an inner column 30, the inner column 30 is disposed in the accommodating space 21, one side of the flexible display 40 is connected to the inner column 30, and includes a display panel 401 and a flexible circuit board 402, and the same parts as those of the above embodiments will not be described again. In the present embodiment, the inner cylinder 30 is not disposed at the center of the accommodating space 21, the transparent cylindrical body 20 has a first axis 23, the inner cylinder 30 has a second axis 31, the first axis 23 and the second axis 31 are not overlapped, and the inner cylinder 30 is disposed in an eccentric manner. With the axial outer surface 201 of the transparent column 20 as the location for disposing the fingerprint sensor 50, the distance R1 from the first axis 23 to the fingerprint sensor 50 on the axial outer surface 201 is greater than the distance R2 from the second axis 31 to the fingerprint sensor 50 on the axial outer surface 201. In other words, the second axis 31 is closer to the fingerprint sensor 50, and when the flexible circuit board 402 of the flexible display 40 is used as the fingerprint sensing light source, the second axis can be closer to the fingerprint sensor 50, thereby increasing the recognition sensitivity. On the other hand, the space vacated by the accommodating space 21 can also be used as a setting position of other elements such as a battery and a circuit board of the display 10, so as to improve the utilization rate of the internal space of the device.

Please refer to fig. 3, which is a schematic diagram of a fingerprint sensing area according to an embodiment of the present invention. As shown in the figures, the reel display 10 includes a transparent pillar 20, an inner pillar 30, and a flexible display 40, and the flexible display 40 includes a display panel 401 and a flexible circuit board 402, and the same portions as those in the above embodiments will not be described again. In the present embodiment, the fingerprint sensor forms a fingerprint identification area 51 on the axial outer surface of the transparent cylindrical body 20, and performs fingerprint identification on the hand 90 of the user to perform an unlocking procedure by using the flexible circuit board 402 of the flexible display 40 as a fingerprint sensing light source. The fingerprint sensing area 51 can sense at least two objects, i.e. fingerprints of at least two different knuckles of a finger (e.g. the first knuckle 91 and the second knuckle 92 of the finger), and the sensed areas of the at least two objects are different because the lengths and widths of the knuckles are different. The width W and height H of the entire fingerprint recognition area 51 may be 45x45mm (e.g., the area of the first knuckle 91 and the second knuckle 92 of the two fingers). In a preferred embodiment, the width W and height H may be 45x90mm (e.g., the area of the first knuckle 91 and the second knuckle 92 of a four-handed finger). In the present embodiment, when the user holds the display 10 with the hand 90, four fingers from the index finger to the little finger can hold the fingerprint recognition area 51 while recognizing the four fingers. Compared with fingerprint identification of a single finger, the fingerprint identification of multiple fingers can obviously increase the identification characteristic points, improve the identification safety, and is suitable for financial transactions, shopping and other applications with higher safety requirements.

Please refer to fig. 4, which is a schematic diagram of a display according to another embodiment of the invention. As shown in the figures, the reel display 11 includes a transparent cylindrical body 20, an inner cylinder 32, a flexible display 40 and a fingerprint sensor 50, the transparent cylindrical body 20 is formed by a transparent material, in this embodiment, the transparent cylindrical body 20 is a cylinder, the inside of the transparent cylindrical body is a hollow structure, an accommodating space 20 for accommodating the inner cylinder 32 is formed, a side surface of the transparent cylindrical body 20 includes an axial outer surface 201 and an axial inner surface 202, the axial inner surface 202 defines the accommodating space 21 inside the transparent cylindrical body 20, and the fingerprint sensor 50 is disposed on the axial outer surface 201. The flexible display 40 can be wrapped around the inner column 32 and received in the receiving space 21. Unlike the previous embodiments, the fingerprint sensing light source of the present embodiment is disposed on the inner cylinder 32, and the fingerprint sensing light source faces the fingerprint sensor 50 from the accommodating space 21 to serve as a sensing light source for fingerprint identification. The reason why the light source is disposed on the inner cylinder 32 itself is that in the second state M2, the flexible display 40 is pulled out, and the backlight originally used as the fingerprint sensing light source is pulled out of the transparent cylinder 20 and cannot be used as the fingerprint sensing light source any more, so the inner cylinder 32 itself is disposed as the light source, and when the flexible display 40 is pulled out, the scroll display 11 can also have the fingerprint identification function. For example, when the display screen is not operated for a period of time and enters the standby state, the unlocking procedure can be performed again through fingerprint recognition by the configuration of the embodiment, and the original display state is returned again.

In the embodiment, since the fingerprint sensing light source is disposed on the inner cylinder 32, when the flexible display 40 is originally stored in the accommodating space 21, the flexible display 40 surrounds the inner cylinder 32, so that the sensing sensitivity is reduced. Therefore, in addition to the above-mentioned case of unlocking after pulling out the flexible display 40, it can also be used with the above-mentioned embodiment, for example, in the first state M1, the backlight of the flexible circuit board of the flexible display 40 is used as the fingerprint sensing light source, and in the second state M2, the light emitting source of the inner column 32 is used as the fingerprint sensing light source.

In another embodiment, the External Quantum Efficiency (External Quantum Efficiency) of the light received by the fingerprint sensor 50 is better, that is, the ratio of the maximum number of electrons of the output photocurrent to the number of incident photons is larger, and therefore, the fingerprint sensing light source of the inner cylinder 32 can be set as a wavelength-adjustable light source, for example, under different usage situations of the first state M1 and the second state M2, the fingerprint sensing light source can be adjusted to a specific light source wavelength, or dual light sources with different wavelengths are used, so that the fingerprint sensor 50 can receive the sensing light source with a specific wavelength, thereby increasing the sensitivity of sensing, further improving the accuracy of fingerprint identification and improving the security level.

Please refer to fig. 5A and 5B, which are schematic views illustrating a fingerprint sensor disposed on an axial inner surface according to an embodiment of the present invention. As shown in fig. 5A, the display 12 includes a transparent cylindrical body 60 and an inner cylinder 70, the inner cylinder 70 is disposed in the accommodating space inside the transparent cylindrical body 60, and as described in the previous embodiment, the inner cylinder 70 itself is disposed with a light source, and the light source is used as a fingerprint sensing light source. In this embodiment, the transparent cylindrical body 60 may be made of transparent glass, and includes an axial outer surface 601 and an axial inner surface 602 opposite to the axial outer surface 601, and the fingerprint sensor is disposed on the axial inner surface 602, and may be directly fabricated on the axial inner surface 602, or fabricated first and then attached to the axial inner surface 602. Fig. 5B is a schematic diagram of a fingerprint sensor structure, in which a buffer layer and a transistor T, a transparent conductive film ITO, a photosensitive layer SRO, and a metal layer M are sequentially disposed on an axial inner surface 602. When the finger 93 of the user is placed in the fingerprint identification area, the fingerprint sensing light source provided by the inner cylinder 70 is transmitted to the finger 93 through the light-transmitting portion, and because the fingerprint has concave and convex lines, the reflection of light at the slope peaks and valleys is different, and the reflected light transmits different electrical signals through the transparent conductive film ITO, the photosensitive layer SRO and the metal layer M to present the fingerprint characteristics. In the embodiment, the photosensitive layer SRO is a Silicon-rich oxide (Silicon-rich oxide) layer, but the invention is not limited thereto, and in other embodiments, amorphous Silicon (a-Si), PIN photodiode, etc. may be used as the photosensitive layer. Similarly, the transparent conductive layer ITO may be Indium Zinc Oxide (IZO), Aluminum Zinc Oxide (AZO), Aluminum Indium Oxide (AIO), indium oxide (InO), or other transparent conductive materials besides Indium Tin Oxide (ITO).

Please refer to fig. 6A and fig. 6B, which are schematic views of the fingerprint sensor disposed on the axial outer surface according to the embodiment of the present invention. As shown in fig. 6A, the display 13 includes a transparent cylindrical body 60 and an inner cylinder 70, the inner cylinder 70 is disposed in the accommodating space inside the transparent cylindrical body 60, and the inner cylinder 70 is provided with a light source as a fingerprint sensing light source, as in the previous embodiment. In this embodiment, the transparent cylindrical body 60 may be made of transparent glass, and includes an axial outer surface 601 and an axial inner surface 61 opposite to the axial outer surface 601, and the fingerprint sensor is disposed on the axial outer surface 601, and may be directly fabricated on the axial outer surface 601, or fabricated first and then attached to the axial outer surface 601. Fig. 6B is a schematic diagram of a fingerprint sensor structure, in which a buffer layer, a transistor T, a metal layer M, a photosensitive layer SRO, a transparent conductive film ITO, and a protective layer 61 are sequentially disposed on an axial outer surface 601. Because the fingerprint sensor formula sets up on axle good fortune surface 601, set up protective layer 61 can avoid finger 93 direct contact to fingerprint sensor structure, and then provide higher incorruptibility. When the finger 93 of the user is placed in the fingerprint identification area, the fingerprint sensing light source provided by the inner cylinder 70 is transmitted to the finger 93 through the light transmitting portion, and the reflected light shows the difference between the peaks and valleys of the fingerprint, and different electrical signals are transmitted from the transparent conductive film ITO, the photosensitive layer SRO and the metal layer M to show the fingerprint characteristics. Similar to the previous embodiments, the photosensitive layer SRO is a Silicon-rich oxide (Silicon-rich oxide) layer, but the present invention is not limited thereto, and in other embodiments, amorphous Silicon (a-Si), PIN photodiode, etc. may be used as the photosensitive layer. Similarly, the transparent conductive layer ITO may be Indium Zinc Oxide (IZO), Aluminum Zinc Oxide (AZO), Aluminum Indium Oxide (AIO), indium oxide (InO), or other transparent conductive materials besides Indium Tin Oxide (ITO).

The foregoing is by way of example only, and not limiting. It is intended that all equivalent modifications or variations without departing from the spirit and scope of the present invention shall be included in the appended claims.

Claims

1. A display, comprising:

a transparent cylindrical body having a receiving space and including an axial outer surface and an axial inner surface;

an inner cylinder disposed in the accommodating space and facing the axial inner surface;

one side of the flexible display is connected with the inner cylinder, and the flexible display is coiled along the inner cylinder and is contained in the containing space under a first state, or under a second state, the flexible display is stretched out of the transparent cylinder from the inner cylinder; and

the fingerprint sensor is arranged on the axial outer surface and receives a fingerprint sensing light source entering the axial inner surface so as to provide the fingerprint sensor for fingerprint identification;

the flexible display comprises a flexible circuit board and a display panel, wherein the display panel is arranged on the flexible circuit board, the display panel and the flexible circuit board are overlapped and wound on the inner column body in the first state, the display panel is positioned between the flexible circuit board and the inner column body in the second state, and the fingerprint sensing light source is arranged on the flexible circuit board;

the inner column body comprises a retracting device, and when the flexible display is in a completely pulled-out state in the second state, the retracting device limits the flexible display to be rolled back to reserve a preset area on the inner column body.

2. The display of claim 1, wherein the fingerprint sensor senses at least two objects, and the at least two objects occupy different areas.

3. The display of claim 1, wherein the inner cylinder is eccentric, the inner cylinder has a first axis, the transparent cylinder has a second axis, and a distance from the first axis to the fingerprint sensor is smaller than a distance from the second axis to the fingerprint sensor.

4. The display of claim 1, wherein a protective layer is disposed over the fingerprint sensor.

5. The display of claim 1, wherein the fingerprint sensing light source is disposed on the inner cylinder facing the fingerprint sensor.

6. A display, comprising:

the fingerprint sensor is arranged on the axial inner surface and receives a fingerprint sensing light source from the accommodating space so as to provide the fingerprint sensor for fingerprint identification;

7. The display of claim 6, wherein the fingerprint sensor senses at least two objects, and the at least two objects occupy different areas.

8. The display of claim 6, wherein the inner cylinder is eccentric, the inner cylinder has a first axis, the transparent cylinder has a second axis, and a distance from the first axis to the fingerprint sensor is smaller than a distance from the second axis to the fingerprint sensor.

9. The display of claim 6, wherein the fingerprint sensing light source is disposed on the inner cylinder facing the fingerprint sensor.