CN109858417B

CN109858417B - Optical fingerprint imaging device under screen

Info

Publication number: CN109858417B
Application number: CN201910057083.0A
Authority: CN
Inventors: 程泰毅; 焉逢运; 孙云刚; 谢詹奇
Original assignee: Silead Inc
Current assignee: Silead Inc
Priority date: 2019-01-22
Filing date: 2019-01-22
Publication date: 2021-02-02
Anticipated expiration: 2039-01-22
Also published as: CN109858417A

Abstract

The invention provides an optical fingerprint imaging device under a screen, which comprises: a substrate provided with a light emitting unit; the light sensing element is arranged on one side of the substrate and is used for converting an optical signal into an electric signal to form an image; the first diaphragm unit is arranged on one side, away from the light sensing element, of the substrate and comprises a first 1/4 wave plate and a first linear polarizer, and the first 1/4 wave plate is located between the first linear polarizer and the substrate; the third 1/4 wave plate is arranged on one side of the first membrane unit, which is far away from the substrate, and a third angle is formed between the optical axis of the third 1/4 wave plate and the polarization direction of the first linear polarizer, wherein the numerical value of the third angle is 45 +/-5 degrees; and the cover plate is arranged on the side, facing away from the substrate, of the third 1/4 wave plate and is provided with a light-transmitting area, and the light-transmitting area is used for being pressed or approached by a finger of a user. The optical fingerprint imaging device under the screen can effectively improve the imaging stability and quality.

Description

Optical fingerprint imaging device under screen

Technical Field

The invention relates to the technical field of optical fingerprints under screens, in particular to an optical fingerprint imaging device under a screen.

Background

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

The fingerprint under the screen can be applied to the OLED display screen by adopting a fingerprint sensor imaging method at present. Specifically, light emitted from the OLED light source disposed in the display panel passes through 1/4 wave plate and linear polarizer sequentially disposed on the outer surface of the display panel to reach the finger pressed or contacted on the glass cover plate. The light is diffusely reflected at the ridges of the finger and becomes less bright, while the light is more bright at the valleys due to the occurrence of specular reflection. Therefore, the brightness of the light reflected back and reaching the fingerprint sensor is different, and imaging is realized.

As shown in fig. 1, light emitted from an OLED light source 400c disposed in a display panel 400 of an OLED display panel passes through an 1/4 wave plate 100a and a linear polarizer 100b and then emits linearly polarized light (r) and (r). The linear polarized light (r) points to the valley of the user's finger, and the linear polarized light (r) points to the ridge of the user's finger. Also, the valleys of the user's finger do not contact the cover glass 500, and the ridges of the user's finger contact the cover glass 500.

Therefore, the two sides of the surface of the cover glass 500 corresponding to the valleys of the user's fingers are made of glass and air, respectively. It is also known that the propagation velocity of light in glass materials is lower than the propagation velocity of light in air. That is, the air contained between the valleys of the user's fingers and the cover glass 500 is an optically thinner medium relative to the material from which the cover glass 500 is made.

According to the principle of light reflection, when light is emitted from an optically dense medium to an optically sparse medium, the light is reflected at the boundary between the optically dense medium and the optically sparse medium. Thus, most of the linearly polarized light (r) is specularly reflected at the cover glass 500. The reflected light (c) is still linearly polarized in the same polarization direction as the linearly polarizing plate 100b, so that it can pass through the linearly polarizing plate 100 b. Then, the circularly polarized light (c) is emitted through 1/4 wave plate 100a and emitted downward to the fingerprint sensor 600.

Similarly, the two sides of the surface of the cover glass 500 corresponding to the ridges of the user's fingers are made of glass and the user's fingers, respectively. Due to the density difference between the glass material and the user's finger, the density difference is much smaller than the density difference between the glass material and the air. Therefore, the difference between the propagation speed of light in the glass material and the propagation speed of light in the user's finger is small. That is, the cover glass 500 is made of a material having a similar light density to that of the user's finger.

Thus, most of the linearly polarized light (r) will be diffusely reflected at the position of the user's finger ridge. Thus, the intensity and brightness of the diffusely reflected light (c) is weaker than the specularly reflected light (c). And, the reflected light (c) is still linearly polarized light having the same polarization direction as the linearly polarizing plate 100b, so that it can pass through the linearly polarizing plate 100 b. Then, the circularly polarized light is emitted through 1/4 wave plate 100a, and is emitted to the lower side of the screen to reach the fingerprint sensor 600.

Then the intensity and brightness of the circularly polarized light reflected by the ridges is weaker than the circularly polarized light reflected specularly at the valleys. Thus, the fingerprint sensor 600 performs imaging according to the brightness difference of the light reflected back from the valleys.

As can be seen from the above, the existing technology of imaging by using the fingerprint sensor 600 under the screen requires that the finger of the user must be well attached to the cover glass 500 based on the imaging principle, so that the light can be diffusely reflected at the position of the ridge of the finger, which is different from the specular reflection. In this way, the intensity and brightness of the reflected light reaching the fingerprint sensor 600 can be differentiated to form an image.

However, in some cases, such as low ambient temperature, the user's fingers are relatively stiff; or, the user's fingers are dry, etc., it may be difficult for the user's fingers to remain attached to the cover glass 500. Then, the contact between the ridge of the user's finger and the cover glass 500 is insufficient. Then at this time, specular reflection may also occur at the location of the ridge. Thus, the difference in the intensity and brightness of the reflected light finally reaching the fingerprint sensor 600 is not significant, and the imaging stability and quality are poor.

It should be noted that the above background description is only for the sake of clarity and complete description of the technical solutions of the present invention and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the invention.

Disclosure of Invention

Based on the foregoing defects in the prior art, embodiments of the present invention provide an optical fingerprint imaging apparatus under a screen, which can effectively improve imaging quality.

In order to achieve the above object, the present invention provides the following technical solutions.

An underscreen optical fingerprint imaging apparatus comprising:

a substrate provided with a light emitting unit;

the light sensing element is arranged on one side of the substrate and used for converting an optical signal into an electric signal;

the first film unit is arranged on one side, away from the light sensing element, of the substrate and comprises a first 1/4 wave plate and a first linear polarizer; the first 1/4 wave plate is located between the first linear polarizer and the substrate;

a third 1/4 wave plate disposed on a side of the first film unit facing away from the substrate, wherein a third angle is formed between an optical axis of the third 1/4 wave plate and a polarization direction of the first linear polarizer, and a value of the third angle is 45 ° ± 5 °;

the cover plate is arranged on one side, away from the substrate, of the third 1/4 wave plate, and is provided with a light transmission area which is used for being pressed or closed by a finger of a user.

Preferably, the light emitting unit emits light pointing to the light transmission region and emits first linearly polarized light after passing through the first 1/4 wave plate and the first linearly polarized light plate; the first linearly polarized light passes through the third 1/4 wave plate and then emits first circularly polarized light;

part of the first circularly polarized light reflects back second circularly polarized light after being subjected to mirror reflection in the light-transmitting area, and the rotating direction of the second circularly polarized light is opposite to that of the first circularly polarized light; and the second circularly polarized light passes through the third 1/4 wave plate and then emits second linearly polarized light vertical to the polarization direction of the first linearly polarized light, so that the second linearly polarized light cannot penetrate through the first linearly polarized light.

Preferably, the finger of the user has a surface layer of the fingerprint and a deep layer of the fingerprint, and both the surface layer of the fingerprint and the deep layer of the fingerprint have ridges and valleys;

when a finger of a user presses or approaches the light transmission area, part of the first circularly polarized light penetrates through the light transmission area to reach the deep layer of the fingerprint, and reflects target signal light after diffuse reflection occurs at the ridge and the valley of the deep layer of the fingerprint respectively; at least part of the target signal light reaches the light sensing element after passing through the third 1/4 wave plate and the first membrane unit in sequence.

Preferably, the target signal light includes first natural light and second natural light; the first natural light is formed by retroreflecting the first circularly polarized light after the first circularly polarized light is subjected to diffuse reflection at valleys of the surface layer and the deep layer of the fingerprint, and the second natural light is formed by retroreflecting the first circularly polarized light after the first circularly polarized light is subjected to diffuse reflection at ridges of the surface layer and the deep layer of the fingerprint; the brightness of the first natural light is greater than the brightness of the second natural light.

Preferably, a second film unit is arranged between the substrate and the light sensing element, the second film unit comprises a second 1/4 wave plate and a second linear polarizer, and the second 1/4 wave plate is positioned between the second linear polarizer and the substrate;

the optical axis of the first 1/4 wave plate forms a first angle with the polarization direction of the first linear polarizer, and the optical axis of the second 1/4 wave plate forms a second angle with the polarization direction of the second linear polarizer;

along the viewing angle direction of the second diaphragm unit pointing to the first diaphragm unit, one of the first angle and the second angle is +45 ° ± 5 °, and the other is-45 ° ± 5 °.

Preferably, the first angle is +45 ° ± 5 °, the second angle is-45 ° ± 5 °; alternatively, the first angle is-45 ° ± 5 °, and the second angle is +45 ° ± 5 °.

Preferably, the first and second diaphragm units at least partially overlap.

Preferably, a projection of the second membrane unit towards the first membrane unit at least partially covers the first membrane unit.

Preferably, the light sensing element is disposed in the fingerprint module, and the second film unit forms a part of the fingerprint module structure.

Preferably, the fingerprint module is provided with a support for supporting the light sensing element, and the second membrane unit is arranged on the support.

Preferably, the bracket defines an accommodating space, and the accommodating space is provided with a lens barrel; the light can reach the light sensing element through the lens cone; the second membrane unit is at least partially accommodated in the accommodating space; alternatively, the second diaphragm unit is at least partially disposed in the lens barrel.

Preferably, the second diaphragm unit is supported at an end of the support; alternatively, the second linear polarizer is accommodated in an accommodating space defined by the bracket, and the second 1/4 wave plate is supported at an end of the bracket.

Preferably, a plurality of optical lenses are further disposed between the light-sensing element and the substrate.

Preferably, the second membrane unit is located above all the optical lenses; or, the second membrane unit is positioned below all the optical lenses; or, the second membrane unit is positioned between any two adjacent optical lenses; or; one or more optical lenses are spaced between the second 1/4 wave plate and the second linear polarizer.

Preferably, a plurality of the optical lenses are arranged in the accommodating space; alternatively, a plurality of the optical lenses are provided in the lens barrel.

Preferably, an optical filter is further disposed between the substrate and the light-sensing element, and the optical filter is configured to at least partially filter noise light in the target signal light.

Preferably, the filter is located above the second membrane unit; alternatively, the optical filter is positioned between the second 1/4 wave plate and the second linear polarizer; or the optical filter is positioned between the second membrane unit and the light sensing element.

Preferably, the optical filter is arranged in the accommodating space; alternatively, the optical filter is disposed in the lens barrel.

By means of the technical scheme, the invention has the beneficial effects that:

according to the off-screen optical fingerprint imaging device, the third 1/4 wave plate is arranged on the side, away from the substrate, of the first membrane unit, so that light with mirror reflection can be eliminated, and imaging is achieved by utilizing light with diffuse reflection of deep layers of fingers. Therefore, the imaging of the light sensing element is not affected by the fact that the fingers are dry and wet and whether the fingers are in good contact with the cover plate or not, and the imaging quality and stability are good.

That is, the off-screen optical fingerprint imaging apparatus according to the embodiment of the present invention does not perform imaging using specular reflection light, but performs imaging using diffuse reflection light. Therefore, even if the fingers of the user do not contact with the cover plate or the fingers of the user do not contact with the cover plate well, namely the fingerprint ridges do not contact with the surface of the cover plate sufficiently at the moment, so that a large amount of specular reflection light exists, the normal receiving and imaging of the diffuse reflection light by the light sensing elements cannot be influenced.

Therefore, the optical fingerprint imaging device under the screen can acquire, image and identify fingerprint information even if the fingers of a user do not contact with the cover plate. Thus, the imaging quality and stability are not affected by whether the user's finger is in contact with the cover plate.

Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not so limited in scope. The embodiments of the invention include many variations, modifications and equivalents within the spirit and scope of the appended claims.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, the proportional sizes, and the like of the respective members in the drawings are merely schematic for facilitating the understanding of the present invention, and do not specifically limit the shapes, the proportional sizes, and the like of the respective members of the present invention. Those skilled in the art, having the benefit of the teachings of this invention, may choose from the various possible shapes and proportional sizes to implement the invention as a matter of case. In the drawings:

FIG. 1 is a schematic structural diagram of a lower optical fingerprint imaging device and an optical path diagram thereof in the prior art;

FIG. 2 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a mirror reflection light path diagram thereof according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of an optical fingerprint imaging device under a screen and an optical path diagram of deep diffuse reflection according to a first embodiment of the present invention;

FIG. 4 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram according to a second preferred embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram thereof according to a third preferred embodiment of the present invention;

FIG. 6 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram thereof according to a fourth preferred embodiment of the present invention;

FIG. 7 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram according to a fifth preferred embodiment of the present invention;

FIG. 8 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram according to a sixth preferred embodiment of the present invention;

FIG. 9 is a schematic structural diagram of an optical fingerprint imaging device under a screen and a deep diffuse reflection optical path diagram according to a seventh preferred embodiment of the present invention;

FIG. 10A is a schematic diagram of the first 1/4 wave plate having an optic axis +45 ° ± 5 ° from the polarization direction of the first linear polarizer;

FIG. 10B is a schematic diagram of the second 1/4 wave plate having an optic axis at-45 ° ± 5 ° to the polarization direction of the second linear polarizer;

FIG. 11A is a schematic diagram of the first 1/4 wave plate having an optic axis at-45 ° ± 5 ° to the polarization direction of the first linear polarizer;

fig. 11B is a schematic diagram of the second 1/4 wave plate having an optical axis +45 ° ± 5 ° with the polarization direction of the second linear polarizer.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a single embodiment.

Unless defined otherwise, all 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. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In this specification, a direction pointing to or facing a user in a normal use state of the off-screen optical fingerprint imaging apparatus according to the embodiment of the present invention is defined as "up", and a direction opposite thereto, or a direction away from the user is defined as "down".

Specifically, when the off-screen optical fingerprint imaging apparatus according to the embodiment of the present invention is configured in an electronic device, a direction in which a display screen of the electronic device is directed toward or faces a user is defined as "up", and a direction in which the display screen of the electronic device is directed away from the user is defined as "down".

More specifically, the upward direction illustrated in fig. 2 to 9 is defined as "up", and the downward direction illustrated in fig. 2 to 9 is defined as "down".

The optical fingerprint imaging device under the screen provided by the embodiment of the invention can be applied to scenes including but not limited to unlocking of fingerprints under the screen, user identity verification, authority acquisition and the like.

Specifically, when the off-screen optical fingerprint imaging apparatus of the embodiment of the present invention is configured in an electronic device, the electronic device may acquire fingerprint feature information of a user based on the off-screen optical fingerprint imaging apparatus, so as to match the fingerprint feature information with stored fingerprint information, so as to implement identity authentication on a current user, and thus determine whether the current user has a corresponding right to perform a related operation on the electronic device.

It should be noted that the fingerprint information obtained as described above is only one common example of the user's biometric features. Those skilled in the art can extend the technical solution of the embodiments of the present invention to any suitable biometric authentication scenario within the scope that can be envisioned. For example, the scenario of verifying by acquiring biometric information, that is, the iris of the user, is not limited in the embodiment of the present invention.

The following is set forth in a scenario in which user fingerprint information is obtained as a main description. It will nevertheless be understood that no limitation of the scope of the embodiments of the invention is thereby intended, as illustrated in the accompanying drawings.

The off-screen optical fingerprint imaging device of the embodiment of the invention can be applied to electronic devices including but not limited to mobile smart phones, tablet electronic devices, computers, GPS navigators, personal digital assistants, intelligent wearable devices and the like.

As shown in fig. 2 to 9, the underscreen optical fingerprint imaging apparatus according to the embodiment of the present invention may include a substrate 4 configured with a light emitting unit 4 c. The substrate 4 may include a first panel substrate 4a and a second panel substrate 4 b. The first panel substrate 4a is located above the second panel substrate 4b, and the two are stacked.

The first panel substrate 4a and the second panel substrate 4b may be made of a light-transmitting material such as glass, PI resin, or the like. Thus, the light emitted from the light emitting unit 4c can propagate in the first panel base 4a and the second panel base 4 b.

The light emitting unit 4c may be any suitable light emitting element including an OLED or an LED, and may be disposed between the first panel substrate 4a and the second panel substrate 4 b. That is, the light emitting unit 4c is disposed on the second panel substrate 4b, and the second panel substrate 4b may serve as a support to carry the light emitting unit 4 c.

Thus, the substrate 4 may be a self-luminous display. Therefore, the light emitting unit 4c of the substrate 4 can be used not only for display but also as an excitation light source. The excitation light source is used for emitting excitation light to the finger of the user, and the excitation light is reflected by the finger of the user to form target signal light carrying fingerprint information.

Further, the underscreen optical fingerprint imaging apparatus may be further provided with a light-sensing element 6 located at one side of the substrate 4 (below the substrate 4 as illustrated in fig. 2 to 9). The light sensor 6 is at least used for receiving the target signal light reflected from the user's finger above the substrate 4. And, the target signal light may be converted into an electrical signal to generate a fingerprint image.

The light sensing element 6 can further send the fingerprint image to an image processor connected with the signal, the image processor performs image processing to obtain a fingerprint signal, and fingerprint identification is performed on the fingerprint signal through an algorithm.

The light sensing element 6 may be a fingerprint chip only. I.e. the fingerprint chip is constructed separately to form the light-sensing element 6.

Alternatively, the light-sensing element 6 may be a fingerprint sensor equipped with a fingerprint chip. I.e. a fingerprint sensor configuration provided with a fingerprint chip, forms the light sensing element 6.

Alternatively, the light sensing element 6 may also be a fingerprint sensor array (as in the known embodiment provided in CN 203909812U). The fingerprint sensor array may include a plurality of fingerprint sensors, each configured with a fingerprint chip.

In other words, the light-sensing element 6 may be of any suitable configuration configured with a fingerprint chip.

The other side of the substrate 4 facing away from the light-sensing element 6 (above the substrate 4 as illustrated in fig. 2 to 9) is provided with a first film unit 1. The first diaphragm unit 1 may include a first 1/4 wave plate 1a and a first linear polarizer 1 b. Also, the first 1/4 wave plate 1a is located between the first linear polarizer 1b and the substrate 4, i.e., the first 1/4 wave plate 1a is located below the first linear polarizer 1 b.

The first 1/4 wave plate 1a and the first linear polarizer 1b may be made of organic materials or inorganic materials, as long as they can realize the phase retardation function and the polarization function, respectively.

The first 1/4 wave plate 1a and the first linear polarizer 1b may be stacked or spaced apart.

Further, the side of the first membrane unit 1 facing away from the substrate 4 (above the first membrane unit 1 as illustrated in fig. 2 to 9) is provided with a third 1/4 wave plate 3. The third 1/4 wave plate 3 may be stacked on the substrate 4 or separated from the substrate 4.

A third angle is formed between the optical axis of the third 1/4 wave plate 3 and the polarization direction of the first linear polarizer 1 b. And, the numerical value (i.e., absolute value) of the third angle is in the vicinity of 45 °. Specifically, the value of the third angle may be within a fault tolerance range.

Specifically, the value of the third angle is 45 ° ± 5 °, then the value of the third angle is 45 °, and is within the tolerance range of 0-10 °. For example, the third angle has a value of 42 °, 45 °, 48 °, or 50 °, etc., which can satisfy the actual requirement.

The side of the third 1/4 wave plate 3 facing away from the third 1/4 wave plate 3 (above the third 1/4 wave plate 3 as illustrated in FIGS. 2-9) is provided with a cover plate 5. The cover 5 has a light-transmitting region on which an operation region for a user's finger to press or approach is formed.

In the present embodiment, the light-transmitting region may occupy the entire upper surface of the cover plate 5. The cover 5 may be made of a light-transmitting material as a whole, and no light-opaque region is present on the upper surface.

Alternatively, the light-transmitting region may occupy only a part of the upper surface of the cover 5. For example, the cover plate 5 may include a central display region made of a light-transmitting material and a bezel region made of a light-opaque material. Wherein, the central display area can constitute the transparent area.

And, a part or the whole of the light transmission region constitutes the operation region.

The cover 5 having the light-transmitting region may be specifically a glass cover or a sapphire cover. And the upper surface of the cap plate 5 may be provided with a protective layer. It will be appreciated that the depression of the user's finger, in fact, may be the depression of the user's finger against the cover 5; alternatively, the cover plate 5 may be pressed against a protective layer provided on the upper surface thereof.

The operation of the underscreen optical fingerprint imaging apparatus using the above-described embodiment of the present invention will be described.

The light emitted from the light emitting unit 4c of the substrate 4 toward the light transmitting area of the cover 5 can be roughly divided into two parts, wherein one part of the light is specularly reflected, and the other part of the light is diffusely reflected on the surface layer and the deep layer of the finger. The method comprises the following specific steps:

as shown in fig. 2, in the case where the specular reflection occurs, the light emitting unit 4c emits light directed to the light transmitting area, and emits first linearly polarized light portion after passing through the first 1/4 wave plate 1a and the first linearly polarizing plate 1b

First linearly polarized light of

After passing through a third 1/4 wave plate 3, the first circularly polarized light is emitted

When the user's finger is pressed on the light-transmitting area of the cover plate 5, the first circularly polarized light (R) points to the valley of the user's finger, and the first circularly polarized light (R) is reflected by the valley of the user's finger

A ridge pointing towards the user's finger.

Substantially, the first circularly polarized light r and

not only does specular reflection occur on the light-transmitting area, but diffuse reflection also occurs on the surface layer and deep layer of the user's finger. That is to say, there is a portion of the first circularly polarized light (c) and

specular reflection occurs in the transparent area, and a part of the first circularly polarized light r and b

It penetrates the light-transmitting area of the cover 5 to reach the user's finger and is diffusely reflected at the user's finger.

Since the first circularly polarized light r and r are incident regardless of whether the user's finger is pressed on the light transmission area of the cover plate 5 or whether the user's finger is in contact with the light transmission area of the cover plate 5

The mirror reflection occurs when the light irradiates the light-transmitting area of the cover plate 5. Therefore, in the case where specular reflection occurs, the first circularly polarized light r and b are not discussed for the moment

A case where diffuse reflection occurs.

Thereby, part of the first circularly polarized light r and

after specular reflection in the light-transmitting region, a second circularly polarized light ninc is retroreflected

Due to second circularly polarized light ninthly

Is the first circularly polarized light r and

formed after one reflection, so that the second circularly polarized light ninthly

And the first circularly polarized light (c) and

opposite in direction of rotation.

Subsequently, a second circularly polarized light ninthly and

continues to propagate downwards, and after passing through third 1/4 wave plate 3, emits second linearly polarized light in R and R perpendicular to the polarization direction of first linear polarizer 1b

So that the second linearly polarized light r and

is not transparent to the first linear polarizer 1 b.

It can be seen that by providing the third 1/4 wave plate 3 on the side of the first film unit 1 facing away from the substrate 4, the specularly reflected light can be eliminated.

Further, the user's finger has a fingerprint surface layer and a fingerprint deep layer, and both the fingerprint surface layer and the fingerprint deep layer have ridges and valleys.

As shown in fig. 3, in the case where the surface layer and the deep layer of the finger are diffusely reflected, the first linearly polarized light and the first circularly polarized light are shown by different reference numerals in order to distinguish them from the case where the specular reflection occurs.

The light emitting unit 4c emits light directed to the light transmitting region, and emits first linearly polarized light after passing through the first 1/4 wave plate 1a and the first linearly polarizing plate 1b

And

first linearly polarized light

And

after passing through a third 1/4 wave plate 3Emitting first circularly polarized light

And

when a user's finger is pressed on the light-transmitting area of the cover plate 5, the first circularly polarized light

Valley, first circularly polarized light directed to user's finger

A ridge pointing towards the user's finger.

Likewise, the first circularly polarized light

And

not only specular reflection occurs in the light-transmitting region, but also diffuse reflection occurs in the surface layer and deep layer of the finger. In the case of diffuse reflection on the surface layer and deep layer of the finger, the first circularly polarized light will not be discussed for the moment

And

a situation of specular reflection occurs.

Thereby, part of the first circularly polarized light

And

penetrate through the light-transmitting area to reach the deep layer of the fingerprint, and reflect back the target signal light after diffuse reflection at the ridge and valley of the deep layer of the fingerprint respectively

And

due to the target signal light

And

is the first circularly polarized light

And

formed by diffuse reflection on the surface and deep layers of the finger, so that the target signal light

And

is disorganized and is equivalent to natural light. Thus, at least part of the target signal light

And

the light can reach the light sensing element 6 after passing through the third 1/4 wave plate 3 and the first film unit 1 in sequence, so that the imaging is realized.

That is, the target signal light mainly includes the first natural light and the second natural light. Wherein the first natural light is first circularly polarized light

The second natural light is first circularly polarized light and is reflected back after diffused reflection at the valleys of the surface layer and deep layer of the fingerprint

The reflecting back is formed after the diffuse reflection occurs at the ridges of the surface layer and the deep layer of the fingerprint.

Practice proves that the brightness of the first natural light is greater than that of the second natural light. Although the detailed mechanism of the difference in brightness between the first natural light and the second natural light is not clear at present, in the present invention, it is considered that the reason why the third 1/4 wave plate is added to eliminate the specular reflection light and make the first natural light and the second natural light different may be as follows:

since the valleys of the user's finger (including the valleys of the surface fingerprint and the valleys of the deep fingerprint) do not contact the light-transmitting area. Thus, a cavity is formed between the valley of the user's finger and the upper surface of the light transmissive region. Thus, the first circularly polarized light

Multiple diffuse reflections can occur in the valleys and cavities of the user's finger and eventually a greater amount of light is retroreflected to form the first natural light.

And accordingly, the ridge of the user's finger (the ridge of the surface fingerprint) comes into contact with the light-transmitting area. Thus, part of the first circularly polarized light

The retroreflective can be directly reflected after diffuse reflection on the ridges of the surface fingerprint. Thereby, the first circularly polarized light

Diffuse reflection occurs on the ridges of the surface fingerprint, similar to specular reflection. Then, as can be seen from the above description, the third 1/4 wave plate can block the transmission of the specular reflection light. Resulting in a smaller amount of second natural light and lower brightness.

Further, part of the first circularly polarized light

And can also retroreflect after diffuse reflection occurs at ridges of deep fingerprints. And due to ridges versus valleysBulges downwards, so the first circularly polarized light

The number of diffuse reflections at the ridges of the user's finger may be relatively small,

so that eventually a greater amount of light is retroreflected to form the second natural light.

That is, the light finally reaching the light-sensing element 6 is mainly the first natural light reflected by the valley of the user's finger and the second natural light reflected by the ridge of the user's finger. And because the first natural light and the second natural light have different brightness, the light sensing element 6 performs imaging by using the signal light with different intensity and brightness.

Thus, imaging by using light diffusely reflected by the surface layer and the deep layer of the finger is realized. Thus, the image formation of the light-sensing element 6 is no longer affected by the dryness and wetness of the finger and the good contact with the cover 5, and the quality and stability of the image formation are better.

That is, the related art implements image formation using specular reflection light occurring at fingerprint valleys and diffuse reflection light occurring at fingerprint ridges. Therefore, once the user's finger makes poor contact with the cover glass, the light is also specularly reflected at the fingerprint ridge. As such, there is no difference, or a small difference, in the intensity and brightness of the light received by the fingerprint sensor. Thereby causing the fingerprint sensor to fail to image or to have poor imaging quality and stability.

The optical fingerprint imaging device under the screen can eliminate specular reflection light. That is, the off-screen optical fingerprint imaging apparatus according to the embodiment of the present invention does not perform imaging using specular reflection light, but performs imaging using diffuse reflection light. Thus, even if the fingers of the user do not contact the cover plate 5, or the fingers of the user do not contact the cover plate 5 well, that is, the fingerprint ridges do not contact the surface of the cover plate 5 sufficiently, so that a large amount of specular reflection light exists, the normal receiving and imaging of the diffuse reflection light by the light sensing element 6 will not be affected.

Therefore, the optical fingerprint imaging device under the screen can acquire, image and identify fingerprint information even if the finger of a user does not contact the cover plate 5. Thereby, the imaging quality and stability are not affected by whether the user's finger is in contact with the cover 5.

Further, since the light emitting unit 4c of the substrate 4 emits light not only toward the light transmitting region of the cover 5, it also directly emits light toward the light sensing element 6. The light directly emitted to the light-sensing element 6 is noise light because it does not carry the fingerprint information of the user. This light may degrade the image quality of the photosensitive element 6.

Therefore, it is necessary to attenuate the noise light directly emitted from the light emitting unit 4c to the light sensing element 6 as much as possible without attenuating or with little attenuation the target signal light reflected by the user's finger, in order to further improve the image quality.

In order to achieve the above object, the second film unit 2 may be provided between the substrate 4 and the light-sensing element 6. The second diaphragm unit 2 may include a second 1/4 wave plate 2a and a second linear polarizer 2 b. And, the second 1/4 wave plate 2a is located between the second linear polarizer 2b and the substrate 4.

The second film unit 2 including the second 1/4 wave plate 2a and the second linear polarizer 2b naturally attenuates the brightness of noise light emitted directly downward from the light emitting unit 4 c.

However, in order not to attenuate the luminance of the target signal light reflected back by the finger while attenuating the luminance of the noise light directly emitted to the light sensing element 6 by the light emitting unit 4 c. The angle between the optical axis of the wave plate comprising 1/4 and the polarization direction of the linear polarizer, respectively, of the first diaphragm element 1 and the second diaphragm element 2 should have special requirements.

Specifically, the optical axis of the first 1/4 wave plate 1a forms a first angle α with the polarization direction of the first linear polarizer 1b, and the optical axis of the second 1/4 wave plate 2a forms a second angle β with the polarization direction of the second linear polarizer 2 b.

And, the first angle α and the second angle β are both in the vicinity of 45 ° in numerical value (i.e., absolute value). Specifically, the difference between the first angle α and the second angle β may be within a tolerance range.

Specifically, the first angle α has a value of 45 ° ± 5 °, and the second angle β also has a value of 45 ° ± 5 °. The difference between the values of the first angle alpha and the second angle beta is within the tolerance range of 0-10 deg.. For example, the first angle α has a value of 45 ° and the second angle β has a value of 43 °. Alternatively, the first angle α may have a value of 42 ° and the second angle β may have a value of 50 °, which still satisfies the practical requirements.

Further, in a viewing angle direction (from bottom to top) in which the second diaphragm unit 2 is directed to the first diaphragm unit 1, the direction of the first angle α is opposite to the direction of the second angle β. Specifically, in the above-described view angle direction from bottom to top, one of the first angle α and the second angle β may be +45 ° ± 5 °, and the other may be-45 ° ± 5 °.

For example, as shown in fig. 10A and 10B, the first angle α is +45 ° ± 5 °, and the second angle β is-45 ° ± 5 °. Alternatively, as shown in fig. 11A and 11B, the first angle α is-45 ° ± 5 °, and the second angle β is +45 ° ± 5 °.

Of course, the viewing direction is not limited to the bottom-up direction toward the first membrane unit 1 along the second membrane unit 2, but may be the opposite direction. I.e. in a direction from top to bottom pointing along the first membrane unit 1 towards the second membrane unit 2.

The direction of the first angle alpha and the direction of the second angle beta in the direction from top to bottom pointing towards the second membrane unit 2 along the first membrane unit 1 are opposite to the above.

Since the principle that the second film unit 2 including the second 1/4 wave plate 2a and the second linear polarizer 2b has the function of attenuating the luminance of the noise light emitted directly downward from the light emitting unit 4c has been explained above, it is not described in detail herein. The principle of not attenuating or slightly attenuating the brightness of the target signal light reflected back by the finger by the design of the scheme that the first angle α and the second angle β are opposite in direction and equal or similar in value will be described below. The method comprises the following specific steps:

the light emitted from the light emitting unit 4c of the substrate 4 and directed to the first film unit 1 is reflected by the finger pressed on the cover 5, and returns through the first film unit 1 again, and becomes a target signal light of circular polarization or elliptical polarization.

The target signal light propagates in the substrate 4, and after reaching the second 1/4 wave plate 2a of the second film unit 2, the target signal light becomes a linearly polarized light with the same polarization direction as that of the second linearly polarized light plate 2b, and can be incident to the light sensing element 6 through the second linearly polarized light plate 2b without loss or with lower loss to be imaged.

Thus, by providing the second film unit 2 including the second 1/4 wave plate 2a and the second linear polarizer 2b between the substrate 4 and the light sensing element 6, the noise light directly emitted from the substrate 4 to the light sensing element 6 passes through the second 1/4 wave plate 2a and the second linear polarizer 2b, and the brightness is attenuated. Thus, the luminance of noise light can be reduced, and the imaging quality can be improved.

In addition, by configuring the first diaphragm unit 1 including the first 1/4 wave plate 1a and the first linear polarizer 1b and designing the direction and the difference between the first angle α formed between the first 1/4 wave plate 1a and the first linear polarizer 1b and the second angle β formed between the second 1/4 wave plate 2a and the second linear polarizer 2b to be appropriate, the target signal light is not attenuated or less attenuated while the noise light is attenuated. Therefore, the signal-to-noise ratio of the light received by the light sensing element 6 is improved, and the imaging quality is greatly improved.

The second 1/4 wave plate 2a and the second linear polarizer 2b may be made of organic materials or inorganic materials as long as they can realize the phase retardation function and the polarization function, respectively.

The second 1/4 wave plate 2a and the second linear polarizer 2b may be stacked on each other or disposed at a distance.

Further, the second film unit 2 formed by the configuration of the second 1/4 wave plate 2a and the second linear polarizer 2b may be disposed on the light sensing element 6, that is, the lower surface of the second film unit 2 is attached to the upper surface of the light sensing element 6. Also, the second film unit 2 may be formed on the upper surface of the light sensing element 6 through a semiconductor packaging process or an IC chip manufacturing process. In this way, the second film unit 2 and the light sensing element 6 can be integrated, so that the second film unit 2 and the light sensing element 6 can form a single integral component.

Of course, the second film unit 2 may be disposed at an interval from the light sensing element 6, that is, the lower surface of the second linearly polarizing plate 2b is isolated from the upper surface of the light sensing element 6.

In addition, at least a second 1/4 wave plate 2a may be implanted in the substrate 4. Specifically, only the second 1/4 wave plate 2a may be implanted in the substrate 4, while the second linear polarizer 2b and the light-sensing element 6 are located outside the substrate 4. Alternatively, the second 1/4 wave plate 2a and the second linear polarizer 2b are both implanted in the substrate 4, and the light sensing element 6 is located outside the substrate 4. Alternatively, the second 1/4 wave plate 2a, the second linear polarizer 2b and the light sensing element 6 are all implanted in the substrate 4.

By implanting at least the second 1/4 wave plate 2a into the substrate 4, the structure can be integrated. Therefore, the under-screen optical fingerprint imaging device is simpler and more convenient to assemble.

Further, as shown in fig. 2 and 3, the second membrane unit 2 may also be disposed in a bonded manner on the lower surface of the substrate 4, the second membrane unit 2 being superposed on the substrate 4. That is, the upper surface of the second 1/4 wave plate 2a included in the second diaphragm unit 2 is bonded to the lower surface of the substrate 4.

As shown in fig. 4 to 9, the light sensor 6 can be disposed in the fingerprint module 9, and the second film unit 2 can be disposed in the fingerprint module 9 to form a part of the structure of the fingerprint module 9.

Specifically, as shown in fig. 4 to 9, the fingerprint module 9 may be configured with a support 11 supporting the light sensing element 6, and the second film unit 2 is disposed on the support 11. The bracket 11 defines a receiving space 11a, and the receiving space 11a is open at least at the upper end, and the circumferential direction thereof may be closed, or may be non-closed or open.

For example, the holder 11 may be a cylindrical body with an open upper end, and the wall of the cylindrical body is not provided with any through structure, such as a through hole, an opening, etc., for communicating the internal space and the external space. Thereby, the defined accommodating space 11a is circumferentially closed.

Alternatively, the holder 11 may be a cylindrical body having a wall provided with a through structure, such as a through hole or an opening, for communicating the internal space and the external space. Alternatively, the holder 11 has a casing structure that is not closed in the circumferential direction, and may have an arc-shaped or C-shaped cross section in a plan view, for example. Still alternatively, the support 11 may be a plurality of columns which are arranged at intervals in the circumferential direction, thereby forming a structure similar to a fence. Thus, the defined accommodating space 11a is not closed or opened.

The light sensing element 6 is accommodated in the accommodating space 11a and fixed on the inner wall of the accommodating space 11 a. In order to reserve a sufficient installation space for other components, the light sensing element 6 is preferably installed at the bottom of the accommodating space 11 a.

The second diaphragm unit 2 may be disposed on the support 11. The second membrane unit 2 thus forms part of the structure of the fingerprint module 9 itself. The second diaphragm unit 2 becomes a part of the structure of the fingerprint module 9 itself, and may be formed integrally with the support 11 before the fingerprint module 9 is assembled with the second diaphragm unit 2. I.e. the second membrane unit 2 is built into the fingerprint module 9. Alternatively, the second diaphragm unit 2 is built into the holder 11.

Thus, by providing the second diaphragm unit 2 including the second linear polarizer 2b and the second 1/4 wave plate 2a on the support 11, structural integration can be achieved, thereby facilitating assembly of the fingerprint module 9.

Further, a lens barrel 10 may be disposed in the accommodating space 11a, and the target signal light may reach the light-sensing element 6 through the lens barrel 10. Specifically, the lens barrel 10 may be provided with any one or more of the structures of the second diaphragm unit 2, the filter 7 mentioned below, the optical lens 8, and the like. The target signal light can reach the light-sensing element 6 through the structure provided in the lens barrel 10.

The second diaphragm unit 2 may be disposed on the bracket 11 in such a manner that the second diaphragm unit 2 is directly disposed on the bracket 11; alternatively, the second diaphragm unit 2 is at least partially disposed in the lens barrel 10, indirectly disposed on the mount 11 through the lens barrel 10.

The second diaphragm unit 2 may be at least partially disposed in the lens barrel 10, and the second diaphragm unit 2 is entirely disposed in the lens barrel 10 (as in the embodiment illustrated in fig. 7 to 8).

Alternatively, only the second linear polarizer 2b included in the second diaphragm unit 2 is disposed in the lens barrel 10, and the second 1/4 wave plate 2a is located outside the lens barrel 10 (not shown). The second 1/4 wave plate 2a is located outside the lens barrel 10, and the second 1/4 wave plate 2a is supported on the top end of the support 11; alternatively, the second 1/4 wave plate 2a is disposed in the accommodating space 11a of the bracket 11.

Alternatively, only the second 1/4 wave plate 2a included in the second film unit 2 is disposed in the lens barrel 10, and the second linear polarizer 2b is located outside the lens barrel 10 (not shown). The second linear polarizer 2b may be located outside the lens barrel 10, and the second linear polarizer 2b is disposed in the accommodating space 11a of the bracket 11.

The second membrane unit 2 is arranged directly on the carrier 11, so that the second membrane unit 2 is at least partially embedded in the carrier 11. Specifically, the second diaphragm unit 2 may be entirely accommodated in the accommodating space 11a (as in the embodiment illustrated in fig. 4 to 6).

Alternatively, only the second linear polarizer 2b included in the second diaphragm unit 2 is accommodated in the accommodating space 11a, and the second 1/4 wave plate 2a is located outside the accommodating space 11a (not shown). The second 1/4 wave plate 2a may be located outside the accommodating space 11a, and the second 1/4 wave plate 2a is supported on the top of the bracket 11.

Alternatively, the second membrane unit 2 may be entirely located outside the accommodating space 11a (as in the embodiment illustrated in fig. 9). At this time, the second diaphragm unit 2 is supported on the top end of the frame 11.

Further, an optical filter 7 may be disposed between the light sensing element 6 and the substrate 4, and the optical filter 7 is configured to at least partially filter noise light mixed in the target signal light, so as to improve the sensing of the light sensing element 6 on the received light and improve the imaging quality.

Specifically, the light-emitting unit 4c disposed on the substrate 4 serves as an excitation light source, and the excitation light emitted by the excitation light source is generally visible light, and the target signal light is also visible light. Then, the noise light may be invisible light in the ambient light, such as infrared light, near-infrared light, or the like. Therefore, the filter 7 may be specifically an infrared filter.

The filter 7 may allow the target signal light to pass therethrough, while filtering noise light (including invisible light such as infrared light, near-infrared light, and the like) in ambient light (e.g., sunlight). Therefore, when the electronic device equipped with the underscreen optical fingerprint imaging apparatus of the embodiment of the invention is used outdoors, the optical filter 7 can effectively filter noise light in external environment light, thereby improving the signal-to-noise ratio of light reaching the light sensing element 6.

The filter 7 may be disposed on a light-transmissive carrier, or the filter 7 may be supported by a light-transmissive carrier. For example, the light-transmitting support may be a glass sheet, and the optical filter 7 may be disposed on the upper surface or the lower surface of the glass sheet in a bonded manner so that the surface of the optical filter 7 is bonded to the surface of the glass sheet. The filter 7 may be attached to the surface of the light-transmitting carrier in the form of a film. The filters 7 may be provided on both the upper and lower surfaces of the light-transmitting support.

Alternatively, the optical filter 7 may be implanted in a light-transmissive carrier. That is, the optical filter 7 is integrated with the light-transmitting carrier, and the light-transmitting carrier has a function of filtering noise light. The light-transmitting support may be a single-layer member and the optical filter 7 may be formed in the light-transmitting support in the form of an optical filter coating. Also, the optical filter coating may be distributed discretely or continuously in the light-transmissive carrier.

Alternatively, the light-transmitting carrier may be plural. The optical filter 7 may be attached between two adjacent light-transmitting carriers in the form of a film, or may be formed in one or more light-transmitting carriers in the form of an optical filter coating.

Similarly, as long as the optical filter 7 is located between the light sensing element 6 and the substrate 4, the relative positional relationship and the contact relationship between the optical filter 7 and the second film unit 2 and the light sensing element 6 may not be limited.

For example, the filter 7 may be located above the second membrane unit 2 (as in the embodiments illustrated in fig. 4 and 6). Alternatively, the filter 7 may be located below the second membrane unit 2 (as in the embodiments illustrated in fig. 5, 7 to 9). Alternatively, the optical filter 7 may also be located between the second linear polarizer 2b and the second 1/4 wave plate 2a (not shown), i.e. the optical filter 7 is sandwiched in the second membrane unit 2.

The filter 7 and the second membrane unit 2 may be stacked on each other or spaced apart from each other. Similarly, the optical filter 7 and the light sensing element 6 may be stacked on each other or spaced apart from each other.

In addition, in order to make the projection of the second film unit 2 at least partially cover the light sensing element 6, so as to attenuate the brightness of the noise light (light emitted from the substrate 4 of the electronic device directly towards the light sensing element 6, which does not carry fingerprint information because it is not reflected by the finger, and makes the light sensing element 6 reach the light saturation in advance, and reduce the amount of signal light reflected by the finger received by the light sensing element 6, thereby reducing the signal-to-noise ratio of the light received by the light sensing element 6 and deteriorating the imaging quality) directed to the light sensing element 6 as much as possible, a light condensing structure may be adopted to realize the convergence of the wide-angle light before the light reaches the light sensing element 6.

Specifically, the light-collecting structure is composed of a plurality of optical lenses 8, and the plurality of optical lenses 8 are located between the light-sensing element 6 and the substrate 4. The optical lens 8 may include convex, micro, and concave lenses, etc., and the convex, micro, and concave lenses may be aspherical convex, micro, and concave lenses. I.e. the optical lens 8 is an unconventional lens.

Like this, optical lens piece 8 not only can assemble light to can realize assembling the comparatively dispersed signal light of wide angle within range to light sense element 6 on, can also correct optical distortion, carry out optical imaging, thereby can make things convenient for light sense element 6 to the collection of fingerprint figure, promote the imaging quality.

The plurality of optical lenses 8 may be disposed on the lower surface of the substrate 4, and the substrate 4 may provide a position and support for the plurality of optical lenses 8. Alternatively, a plurality of optical lenses 8 may be disposed on the light sensing element 6, so that the light sensing element 6 may provide a disposing position and support for the plurality of optical lenses 8.

Of course, the plurality of optical lenses 8 may be spaced apart from the light-sensing element 6. Specifically, a light-transmitting plate or a light-transmitting sheet for disposing the plurality of optical lenses 8 may be disposed above the light-sensing element 6, thereby achieving the spaced disposition of the plurality of optical lenses 8 and the light-sensing element 6.

Or, when the light sensing element 6 of the off-screen optical fingerprint imaging device of the embodiment of the invention is disposed in the fingerprint module 9, the plurality of optical lenses 8 may be isolated from the light sensing element 6 by being fixed in the accommodating space 11a of the bracket 11.

In order not to affect the imaging quality of the light sensing element 6, when the plurality of optical lenses 8 are spaced apart from the light sensing element 6, the spacing distance between the optical lens 8 positioned at the lowest position in the plurality of optical lenses 8 and the light sensing element 6 is equal to or close to the focal length of the optical lens 8.

Specifically, the difference between the spacing distance between the lowermost optical lens 8 and the light sensing element 6 is within the predetermined range [0, Φ ], i.e., the spacing distance between the lowermost optical lens 8 and the light sensing element 6 is considered to be equal to or close to the focal length of the optical lens 8. The upper limit value Φ of the predetermined range may be set according to actual conditions, which is not limited in the embodiment of the present invention.

Similarly, as long as the plurality of optical lenses 8 are located between the light sensing element 6 and the substrate 4, the relative positional relationship and the contact relationship between the plurality of optical lenses 8 and the second film unit 2 and the light sensing element 6 may not be limited.

For example, the second membrane unit 2 may be located above all the optical lenses 8 (as in the embodiments illustrated in fig. 8 to 9). Alternatively, the second membrane unit 2 may be located below all optical lenses 8 (as in the embodiments illustrated in fig. 4 to 6). Alternatively, the second film unit 2 is located between any two adjacent optical lenses 8 (as in the embodiment illustrated in fig. 7). Still alternatively, one or more optical lenses 8 (not shown) are spaced between the second linear polarizer 2b and the second 1/4 wave plate 2 a.

Thereby, by providing a plurality of optical lenses 8 having a light condensing function, even if the second film unit 2 of a smaller size is arranged, it is possible to achieve at least partial coverage of the photosensitive element 6 by the projection of the second film unit 2. That is to say, through a plurality of optical lens 8 that the configuration has the function of assembling to wide angle light, can reduce the size of second diaphragm unit 2 to be favorable to fingerprint module 9's structure to integrate.

The filter 7 and the plurality of optical lenses 8 are both located above the second membrane unit 2, and the positional relationship therebetween may be relatively free. Specifically, the optical filter 7 may be located above or below all the optical lenses 8, or may be inserted between the optical lenses 8, which is not limited in the embodiment of the present invention.

Further, the optical filter 7 and the plurality of optical lenses 8 may be disposed in the accommodating space 11a of the holder 11. Alternatively, when the lens barrel 10 is provided in the accommodating space 11a, the optical filter 7 and the plurality of optical lenses 8 may be provided in the lens barrel 10.

Further, the lens barrel 10 can move in the accommodating space 11a of the holder 11 in a direction to approach or separate from the light-sensing element 6. Specifically, the outer wall of the lens barrel 10 may be screw-fitted with the inner wall of the accommodating space 11 a. In this way, the up-and-down movement of the lens barrel 10 is achieved by changing the screwing length of the lens barrel 10 in the accommodation space 11 a.

Thereby, when the plurality of optical lenses 8 are provided in the lens barrel 10, by the movement of the lens barrel 10, the change of the distance between the optical lens 8 positioned lowermost among the plurality of optical lenses 8 and the light sensing element 6 can be achieved, so that the focusing of the optical lens 8 positioned lowermost can be performed.

It should be noted that, in the description of the present invention, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is considered as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

Any numerical value recited herein includes all values from the lower value to the upper value that are incremented by one unit, provided that there is a separation of at least two units between any lower value and any higher value. For example, if it is stated that the number of a component or a value of a process variable (e.g., temperature, pressure, time, etc.) is from 1 to 90, preferably from 21 to 80, and more preferably from 30 to 70, it is intended that equivalents such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also expressly enumerated in this specification. For values less than 1, one unit is suitably considered to be 0.0001, 0.001, 0.01, 0.1. These are only examples of what is intended to be explicitly recited, and all possible combinations of numerical values between the lowest value and the highest value that are explicitly recited in the specification in a similar manner are to be considered.

Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. The use of "about" or "approximately" with a range applies to both endpoints of the range. Thus, "about 20 to about 30" is intended to cover "about 20 to about 30", including at least the endpoints specified.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the applicant consider that such subject matter is not considered part of the disclosed subject matter.

Claims

1. An underscreen optical fingerprint imaging apparatus, comprising:

a substrate provided with a light emitting unit;

2. The underscreen optical fingerprint imaging apparatus of claim 1 wherein said light emitting unit emits light directed toward said light transmissive region that passes through said first 1/4 wave plate and first linear polarizer and then exits first linearly polarized light; the first linearly polarized light passes through the third 1/4 wave plate and then emits first circularly polarized light;

3. The underscreen optical fingerprint imaging apparatus of claim 2 wherein the user's finger has a fingerprint surface layer and a fingerprint deep layer, and both the fingerprint surface layer and the fingerprint deep layer have ridges and valleys;

4. The underscreen optical fingerprint imaging apparatus of claim 3 wherein said target signal light comprises a first natural light and a second natural light; the first natural light is formed by retroreflecting the first circularly polarized light after the first circularly polarized light is subjected to diffuse reflection at valleys of the surface layer and the deep layer of the fingerprint, and the second natural light is formed by retroreflecting the first circularly polarized light after the first circularly polarized light is subjected to diffuse reflection at ridges of the surface layer and the deep layer of the fingerprint; the brightness of the first natural light is greater than the brightness of the second natural light.

5. The underscreen optical fingerprint imager of claim 1 wherein a second diaphragm unit is disposed between the substrate and the light-sensing element, the second diaphragm unit comprising a second 1/4 wave plate and a second linear polarizer, the second 1/4 wave plate being disposed between the second linear polarizer and the substrate;

6. The underscreen optical fingerprint imaging apparatus of claim 5 wherein the first diaphragm element and the second diaphragm element at least partially overlap.

7. The underscreen optical fingerprint imaging apparatus of claim 5 wherein a projection of the second diaphragm unit toward the first diaphragm unit at least partially covers the first diaphragm unit.

8. The device as claimed in claim 5, wherein the light-sensing element is disposed in a fingerprint module, and the second membrane unit forms a part of the fingerprint module.

9. The underscreen optical fingerprint imaging apparatus of claim 8 wherein the fingerprint module is configured with a support supporting the light-sensing element, the second membrane unit being disposed on the support.

10. The underscreen optical fingerprint imaging apparatus of claim 9 wherein the bracket defines an accommodation space in which a lens barrel is disposed; the light can reach the light sensing element through the lens cone;

the second membrane unit is at least partially accommodated in the accommodating space; or,

the second diaphragm unit is at least partially disposed in the lens barrel.

11. The underscreen optical fingerprint imaging apparatus of claim 9,

the second diaphragm unit is supported at the end of the bracket; or,

the second linear polarizer is accommodated in an accommodating space defined by the bracket, and the second 1/4 wave plate is supported at the end of the bracket.

12. The underscreen optical fingerprint imaging apparatus of claim 10 wherein a plurality of optical lenses are further disposed between said light-sensing elements and said substrate.

13. The underscreen optical fingerprint imaging apparatus of claim 12,

the second membrane unit is positioned above all the optical lenses; or,

the second diaphragm unit is positioned below all the optical lenses; or,

the second membrane unit is positioned between any two adjacent optical lenses; or;

one or more optical lenses are spaced between the second 1/4 wave plate and the second linear polarizer.

14. The underscreen optical fingerprint imaging apparatus of claim 12,

a plurality of optical lenses are arranged in the accommodating space; or,

a plurality of the optical lenses are disposed in the lens barrel.

15. The underscreen optical fingerprint imager of claim 10 wherein an optical filter is further disposed between the substrate and the light-sensing element, the optical filter being configured to at least partially filter noise light in the target signal light.

16. The underscreen optical fingerprint imaging apparatus of claim 15,

the optical filter is positioned above the second membrane unit; or,

the optical filter is positioned between the second 1/4 wave plate and the second linear polarizer; or,

the optical filter is positioned between the second membrane unit and the light sensing element.

17. The underscreen optical fingerprint imaging apparatus of claim 15,

the optical filter is arranged in the accommodating space; or,

the optical filter is disposed in the lens barrel.