KR20210009457A - Fingerprint sensing unit using variable retarder and electronic device with the same - Google Patents

Abstract

The present invention provides a fingerprint recognition unit using a variable retarder capable of extracting only pure fingerprint information by separating a fingerprint signal and noise mixed in an optical signal without increasing required pixels or reducing the size of a photo sensor, and an electronic device providing the same. According to the present invention, the fingerprint recognition unit comprises: a transparent cover; a polarizing portion provided under the transparent cover; a light emitting portion provided under the polarizing portion to emit light; a photo sensor portion provided under the light emitting portion; and a variable retarder provided between the light emitting portion and the photo sensor portion. The variable retarder may include: an electrode part to which a first voltage and a second voltage are selectively applied, and which forms an electric field according to the first voltage or the second voltage; and a liquid crystal layer provided in a region to which the electric field is applied and which includes liquid crystal.

Description

Fingerprint recognition unit using a variable retarder, and an electronic device having the same TECHNICAL FIELD [FINGERPRINT SENSING UNIT USING VARIABLE RETARDER AND ELECTRONIC DEVICE WITH THE SAME}

The present invention relates to a fingerprint recognition device, and more particularly, to a fingerprint recognition unit using a variable retarder that detects fingerprint information using light reflected from a fingerprint, and an electronic device having the same.

In the case of electronic devices, such as mobile devices such as smartphones, that are essential belongings of users, user authentication for personal information protection is becoming an important function, and technologies related to user authentication are being actively developed.

Among the most commonly used technologies for user authentication technology, fingerprint recognition technology is included. An electronic device equipped with a fingerprint sensor to which fingerprint recognition technology is applied may authenticate a user by comparing fingerprint information collected during user authentication with fingerprint information registered through a fingerprint registration process.

Meanwhile, as users who prefer a large screen are increasing in recent years, research and development for increasing the size of the screen in electronic devices such as smart phones has been continuously conducted. For example, the electronic device may have an infinity display occupying most of the front area.

Since an electronic device equipped with an infinity display does not have a non-display area such as a bezel or the like, an optical fingerprint sensor that is normally disposed in the non-display area of the screen may be disposed in the display area of the screen. In addition, by arranging the optical fingerprint sensor, light sources included in the display (e.g., backlight unit (BLU), light emitting diode (LED), organic light emitting diode (OLED)), etc., without having to arrange a separate light source for the optical fingerprint sensor ) Can be used.

The optical fingerprint sensor includes a photo sensor that detects light (ie, an optical signal) that is reflected in the fingerprint of a finger in contact with the transparent cover.

However, the optical signal flowing into the photo sensor unit is mixed with noise as well as the signal for the fingerprint information. That is, the light emitted from the light emitting unit and then reflected to the fingerprint corresponds to an optical signal corresponding to the fingerprint information, but the light emitted from the light emitting unit and reflected to the polarizing unit enters the photo sensor unit as a noise component. Therefore, it is possible to accurately recognize a fingerprint only when the noise component of the optical signal detected by the photo sensor unit can be removed.

In order to solve the noise mixing problem, a method of removing noise by alternately arranging a plurality of film pieces polarized at +45 degrees and a plurality of film pieces polarized at -45 degrees has been proposed. However, according to this conventional method, a photosensor corresponding to one polarizing film piece at +45 degrees and a photosensor corresponding to one polarizing film piece at -45 degrees, that is, a pair of photosensors are paired with one pixel. Since it has to be designed in a structure that constitutes a structure, it takes twice as many pixels as before, and since the size of the photosensor needs to be smaller, there is a problem in that sensitivity is lowered and cost is increased.

Korean Patent Publication No. 10-2019-0036194 (published on April 4, 2019)

The present invention is to solve the above problems, and an object of the present invention is a variable retarder capable of measuring a noise component mixed in a photo sensor without increasing the required pixels and reducing the size of the photosensor accompanying the conventional method. It is to provide a fingerprint recognition unit using and an electronic device having the same.

The fingerprint recognition unit according to the present invention for achieving the above object includes: a transparent cover; A polarizing unit provided under the transparent cover; A light emitting unit provided under the polarizing unit to emit light; A photo sensor unit provided under the light emitting unit; And a variable retarder provided between the light emitting part and the photo sensor part.

The variable retarder may include: an electrode unit selectively applying a first voltage and a second voltage and forming an electric field according to the first voltage or the second voltage; And a liquid crystal layer provided in a region to which the electric field is applied and including a liquid crystal.

The liquid crystal layer, when the first voltage is applied, is converted into a liquid crystal array state according to the application of the first voltage, and is configured to emit only the light of the first polarization component among the light incident on the liquid crystal layer to the photo sensor unit. .

And, when the second voltage is applied, the liquid crystal layer is converted into a liquid crystal arrangement state according to the application of the second voltage, and only light of the second polarization component among the light incident on the liquid crystal layer is emitted to the photo sensor unit. Is configured to

According to the fingerprint recognition unit using the variable retarder according to the present invention and the electronic device having the same, in designing a unit for removing noise from an optical fingerprint sensor, as in the prior art, the required pixels are increased or the size of the photosensor is reduced. Without doing so, it is possible to extract only pure fingerprint information by separating the fingerprint signal and noise mixed in the optical signal.

Accordingly, it is possible to increase the S/N ratio without reducing the size of the photosensor, and thus there is an effect of solving the problem of reducing sensitivity and increasing cost of the conventional method.

In addition, since a retarder is not manufactured for each photo sensor and a single voltage variable retarder is manufactured as a whole, there is an advantage of reducing manufacturing cost.

In addition, since the difference in the deflection angle according to the set product can be adjusted with a voltage, there is an advantage of being able to easily correct minute deviations for each product that may occur during the product manufacturing process.

1 is a cross-sectional view schematically showing the structure of a fingerprint recognition unit using a variable retarder according to the present invention.
2 is a cross-sectional view of a variable retarder according to a first embodiment of the present invention.
3 is a cross-sectional view of a variable retarder according to a second embodiment of the present invention.
4 is a view for explaining an operation when a first voltage (V1) is applied of a fingerprint recognition unit using a variable retarder according to the present invention.
5 is a view for explaining an operation when a second voltage (V2) is applied of the fingerprint recognition unit using a variable retarder according to the present invention.

The terms used in the present specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described above, but one or more other features or It is to be understood that the presence or addition of numbers, steps, actions, components, parts, or combinations thereof does not preclude the possibility of preliminary exclusion.

In addition, in the present specification, the term "on or above" means to be located above or below the target portion, but this does not necessarily mean that it is located on the upper side with respect to the direction of gravity. That is, the term "on or on the top of" referred to in the present specification includes not only a case that is located above or below the target part, but also a case that is located before or after the target part.

In addition, when a part of a region, plate, etc. is said to be "on or on" another part, it is not only in contact with or spaced apart from another part "directly on or on", but also another part in the middle This includes cases where there is.

In addition, in the present specification, when one component is referred to as "connected" or "connected" to another component, the one component may be directly connected or directly connected to the other component, but specially It should be understood that as long as there is no opposing substrate, it may be connected or may be connected via another component in the middle.

In addition, in the present specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component.

Hereinafter, preferred embodiments, advantages and features of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view schematically showing the structure of a fingerprint recognition unit using a variable retarder according to the present invention.

Referring to FIG. 1, a fingerprint recognition unit using a variable retarder according to the present invention includes a housing, a transparent cover 10, a polarizing section 20, a light emitting section 30, a photo sensor section 60, and a variable retarder. 100), a voltage applying unit 50 and a control unit (not shown).

The housing is a case in which a space capable of accommodating a plurality of components is provided.

The transparent cover 10 is a transparent and thin plate to which the fingers of a person attempting fingerprint authentication come into contact.

The transparent cover 10 may be combined with the housing with a space in the housing in which components of the fingerprint recognition unit can be accommodated.

For example, the transparent cover 10 may form at least a part or all of the front surface of the fingerprint recognition unit.

As another example, the transparent cover 10 may form a part of the side surface or a part of the front surface and the side surface of the fingerprint recognition unit. As another example, the transparent cover 10 may form a part of the rear surface of the fingerprint recognition unit.

The transparent cover 10 may be formed in a substantially flat shape, and at least a portion of the upper, lower, left and/or right ends may have a curved surface.

At least a portion of the transparent cover 10 may be formed of a transparent material, and an image output through the light emitting unit 30 may pass through the transparent area of the transparent cover 10 and be displayed to the outside.

The transparent cover 10 may be made of, for example, a material such as tempered glass, plastic, or reinforced plastic.

Meanwhile, the fingerprint recognition unit of the present invention may be mounted on an electronic device such as a smart phone. In this case, the transparent cover 10 may form at least a part or all of the front surface of the electronic device. As another example, the transparent cover 10 may form part of the front and side surfaces of the electronic device.

The polarizing unit 20 is a member in the form of a film provided on one surface of the transparent cover 10 to prevent reflection.

The fingerprint recognition unit may reflect external light by means of metal electrodes and metal wirings formed on the light emitting device panel, and visibility and contrast ratio may be deteriorated by the reflected external light, resulting in a decrease in display quality.

The polarizing unit 20 is disposed on one surface of the transparent cover 10 to prevent the above-described reflected external light from leaking out of the transparent cover 10.

As an example, the polarizing part 20 may be formed of a circular polarizing plate, and may be attached to the lower surface of the transparent cover 10.

As another example, the polarizing unit 20 may include a polarizer, a first retardation film, and a second retardation film. The polarizer may be a linear polarizer that converts incident light into linearly polarized light.

In this case, the first retardation film is disposed on one surface of the polarizer to have a reverse wavelength dispersion phase delay. For example, the first retardation film may be a retardation film having a λ/4 retardation.

The second retardation film may be a polymer film disposed on at least one surface of the first retardation film.

According to the polarizing unit 20 as described above, when external light is incident on the polarizer, only the first polarization component of the two polarization components passes, and then, passing through the first retardation film and the second retardation film, it may be converted into circularly polarized light. . The circularly polarized light is reflected from a display panel including a substrate and an electrode, so that the circularly polarized direction is changed, and the circularly polarized light passes through the second retardation film and the first retardation film again, and only the second polarization component is directed toward the polarizer Will be released. However, since the second polarization component does not pass through the polarizer and is not emitted to the outside, it is possible to implement an external light reflection prevention function.

The light emitting part 30 is provided under the polarizing part 20 inside the housing and includes an element that emits light. According to an embodiment, the light emitting unit 30 may be configured in the form of a display panel capable of displaying an image or the like.

In this case, the light emitting unit 30 may include a plurality of display devices and conductive lines, and the plurality of display devices may be arranged on the substrate 40 in a matrix form to form a pixel.

As an example, the display device may include an organic light emitting diode (OLED). The conductive line may include at least one gate signal line or at least one data signal line. In this case, the plurality of gate signal lines and the plurality of data signal lines may be arranged in a matrix form, and display elements may be arranged adjacent to a point where the lines intersect to be electrically connected.

The photo sensor unit 60 includes a photo sensor that detects light (ie, an optical signal) in which light reflected by a fingerprint of a finger in contact with the transparent cover 10 is introduced.

The porter sensor unit 60 functions to recognize the fingerprint by detecting the reflected light of the fingerprint in this way. Accordingly, the photo sensor unit 60 is disposed under the transparent cover 10 and is specifically configured to be disposed under at least a partial area of the light emitting unit 30.

However, the optical signal flowing into the photo sensor unit 60 is mixed with noise as well as a signal for fingerprint information. That is, the light emitted from the light emitting unit 30 and then reflected on the fingerprint corresponds to an optical signal corresponding to the fingerprint information, but the light emitted from the light emitting unit 30 and then reflected on the polarizing unit 20 is a photo sensor unit. The noise component is entered at (60). Accordingly, it is possible to accurately recognize a fingerprint only when such noise components can be removed from the optical signal detected by the photo sensor unit 60.

In order to solve the noise mixing problem, a method of removing noise by alternately arranging a plurality of film pieces polarized at +45 degrees and a plurality of film pieces polarized at -45 degrees has been proposed. However, according to this conventional method, a photosensor corresponding to one polarizing film piece at +45 degrees and a photosensor corresponding to one polarizing film piece at -45 degrees, that is, a pair of photosensors are paired with one pixel. Since it has to be designed in a structure that constitutes a structure, it takes twice as many pixels as before, and since the pixel size is reduced, there is a problem in that sensitivity is lowered and cost is increased.

The inventor of the present invention has developed a variable retarder 100 in order to solve the problem of reducing the sensitivity and increasing the cost due to the increase in the required pixels and the decrease in the size of the photosensor of the conventional method. That is, when the variable retarder 100 of the present invention is used, noise components mixed in the photo sensor unit 60 can be removed without increasing the required pixels and reducing the size of the photosensor as in the conventional method.

The variable retarder 100 is provided between the light emitting unit 30 and the photo sensor. Accordingly, the fingerprint recognition unit may be configured such that the variable retarder 100 is disposed vertically above the photo sensor, and at least a partial region of the light emitting unit 30 is disposed vertically above the variable retarder 100. The variable retarder 100 includes electrode portions 120 and 121 ′ and a liquid crystal layer 130.

The electrode portions 120 and 121 ′ of the variable retarder 100 are configured to form an electric field when a voltage is applied. That is, the electrode units 120 and 121 ′ respond to the liquid crystal 131 by applying an electric field to the liquid crystal layer 130 so that the first polarization component and the second polarization component selectively pass.

According to an embodiment, the electrode unit 120 may be formed of an electrode layer of a vertical electric field type. 2 is a cross-sectional view of a variable retarder according to a first embodiment of the present invention. Referring to FIG. 2, the vertical electric field type electrode unit 120 according to the first embodiment of the present invention includes an upper electrode 121 and a lower electrode 123, and a lower electrode 123 to form a vertical electric field. ), the upper electrode 121 is positioned vertically above and the liquid crystal layer 130 is interposed between the lower electrode 123 and the upper electrode 121.

The lower electrode 123 is formed on the upper surface of the lower substrate 140, and the upper electrode 121 is formed on the lower surface of the upper substrate 110. A liquid crystal layer 130 is provided on the lower electrode 123, and an upper electrode 121 is disposed on the liquid crystal layer 130. In addition, the upper electrode 121 and the lower electrode 123 may be formed of a transparent conductive material such as ITO (Indium Tin Oxide).

The vertical electric field electrode unit 120 generates an electric field in a first direction when the first voltage V1 is applied to respond to the liquid crystal 131 of the liquid crystal layer 130, thereby It serves to emit only light of the first polarization component toward the photo sensor unit 60.

The vertical electric field type electrode unit 120 generates an electric field in a second direction when the second voltage V2 is applied to respond to the liquid crystal 131 of the liquid crystal layer 130, thereby It serves to emit only light of the second polarization component toward the photo sensor unit 60. Here, the first electric field direction and the second electric field direction may be configured to be orthogonal to each other.

According to another embodiment, the electrode unit 120 ′ may be formed of an electrode layer of a transverse electric field method. 3 is a cross-sectional view of a variable retarder according to a second embodiment of the present invention. Referring to FIG. 3, a transverse electric field type electrode unit 120 ′ according to the second exemplary embodiment of the present invention includes a first electrode 125, a second electrode 127, and a common electrode 129. In order to form an electric field, the first electrode 125 pattern and the common electrode 129 pattern may be disposed on different layers, and an insulating layer may be interposed therebetween, having a FFS (Fringe-Field Switching) structure.

The transverse electric field type electrode unit 120 ′ is characterized in that it is configured to selectively generate a transverse electric field in a first electric field direction and a second electric field direction different from the first electric field direction, and to realize this, a common electrode ( 129, a first insulating layer 160, a first electrode 125, a second insulating layer 161, and a second electrode 127 are sequentially stacked.

The common electrode 129 is formed on the upper surface of the substrate 170, the first electrode 125 is patterned on a layer higher than the common electrode 129, and the first insulating layer 160 is formed with the common electrode 129 It is interposed between the first electrodes 125. In addition, a second insulating layer 161 is formed on the first electrode 125 again, and a second electrode 127 is patterned on the second insulating layer 161.

When the first voltage is applied, a transverse electric field is generated between the first electrode 125 and the common electrode 129 in a first direction to respond to the liquid crystal 131 of the liquid crystal layer 130, thereby entering the liquid crystal layer 130 It serves to emit only light of the first polarization component among the light to be emitted toward the photo sensor unit 60.

When the second voltage is applied, a transverse electric field is generated between the second electrode 127 and the common electrode 129 in a second direction to respond to the liquid crystal 131 of the liquid crystal layer 130, thereby incident on the liquid crystal layer 130. Among the light, only the light of the second polarization component is emitted toward the photo sensor unit 60. Here, the second direction when the second voltage is applied may be a direction orthogonal to the first direction when the first voltage is applied.

The protective layer 150 is a component for protecting the outer surface of the liquid crystal layer 130 from damage such as scratches, etc., and is made of a coating layer made of a transparent resin material having excellent light transmittance and is attached to the outer surface of the liquid crystal layer 130 do.

The liquid crystal layer 130 includes an upper alignment layer and a lower alignment layer, and a liquid crystal 131 provided between a pair of alignment layers.

The liquid crystal layer 130 is provided in an area where the electric field of the electrode units 120 and 120 ′ is applied, is configured to allow reflected light to be incident, and selectively selects only one of the two polarization components of the light. It functions to send it out to the side. For reference, the'reflected light' includes light emitted from the light emitting unit 30 and reflected on the fingerprint, and light emitted from the light emitting unit 30 and then reflected on the polarizing unit 20.

When the first voltage V1 is applied to the electrode portions 120 and 120', the liquid crystal layer 130 changes the arrangement state of the liquid crystal 131 due to the influence of the first electric field formed at this time, thereby changing the liquid crystal layer 130 ) Of the incident light, only the light of the first polarization component is emitted toward the photo sensor unit 60.

In addition, when the second voltage V2 is applied to the electrode portions 120 and 120', the liquid crystal layer 130 changes the arrangement state of the liquid crystal 131 due to the effect of the second electric field formed at this time, thereby changing the liquid crystal layer ( Among the light incident on 130), only the light of the second polarization component is emitted to the photo sensor unit 60.

Preferably, the first polarization component selectively emitted by the liquid crystal layer 130 according to the applied voltages V1 and V2 may be left circularly polarized light, and the second polarized light may be right circularly polarized light.

Preferably, the liquid crystal layer 130 is arranged along the electric field direction (hereinafter referred to as'first electric field direction') formed by the application of the first voltage V1 to the electrode portions 120 and 120', When a second voltage is applied to the electrode parts 120 and 120 ′, they are arranged along an electric field direction (hereinafter referred to as a “second electric field direction”) formed thereby, wherein the first electric field direction and the second electric field direction are It can be configured to be orthogonal to each other.

Preferably, when the liquid crystal layer 130 changes to the first arrangement state of the liquid crystal 131 according to the application of the first voltage V1, a phase delay effect occurs in the direction of 45° with respect to the incident light, and the second voltage V2 ) When the liquid crystal 131 changes to the second arrangement state according to the application, the phase delay effect may be generated in the direction of -45° with respect to the incident light. Here, the second arrangement state of the liquid crystal 131 may be a state in which the first arrangement state and the arrangement direction are different.

The voltage applying unit 50 is configured to selectively apply the first voltage V1 and the second voltage V2 to the electrode units 120 and 120'. Specifically, the voltage applying unit 50 is configured to sequentially apply the first voltage and the second voltage at least once when a user attempts to recognize a fingerprint.

The control unit is a central processing unit for extracting fingerprint information, and is configured to compare the first optical signal and the second optical signal to remove noise mixed in the input signal. Here, the first optical signal is a signal detected by the photo sensor unit 60 when the first voltage V1 is applied to the electrode units 120 and 120 ′, and does not include light reflected from the fingerprint (ie, fingerprint signal). , Only light (ie, noise) reflected by the polarizing unit 20 is included. In addition, the second optical signal is a signal detected by the photo sensor unit 60 when the second voltage V2 is applied to the electrode units 120 and 120', and includes both a fingerprint signal and noise.

Accordingly, the control unit may measure and remove the noise component and its amount mixed in the fingerprint information by comparing the first optical signal and the second optical signal.

Hereinafter, an operation of extracting fingerprint information from which noise is removed by the fingerprint recognition unit of the present invention using the variable retarder 100 described above will be described.

4 is a view for explaining an operation when a first voltage (V1) is applied of a fingerprint recognition unit using a variable retarder according to the present invention, and FIG. 5 is a second fingerprint recognition unit using a variable retarder according to the present invention. A diagram for explaining an operation when voltage V2 is applied.

When a user touches a finger on the transparent cover 10, light emitted from the light emitting unit 30 is reflected on the fingerprint and then directed to the liquid crystal layer 130. The optical signal directed to the liquid crystal layer 130 is introduced by mixing not only a signal for fingerprint information but also light reflected by the polarizing unit 20, that is, a noise component K2.

At this time, when the first voltage V1 is applied to the electrode parts 120 and 120', the liquid crystal 131 is changed to the first arrangement state, and the first polarization component (for example, the left circle) of the light incident on the liquid crystal layer 130 Only light of polarized light) is emitted to the photo sensor unit 60 side.

However, the light corresponding to the pure fingerprint signal K1 passes through the polarization unit 20 and only the second polarization component exists, so that it cannot pass through the liquid crystal layer 130. On the other hand, the noise component K2 has both the first and second polarization components, so that the first polarization component passes through the liquid crystal layer 130 (see FIG. 4). Therefore, the optical signal (hereinafter, referred to as the first optical signal) detected by the photosensor corresponds to the pure noise component K2.

After measuring the pure noise component (K2) by applying the first voltage, immediately after applying the second voltage (V2) to the electrode parts (120, 120'), the liquid crystal 131 is changed to the second array state, Of the light incident on the layer 130, only light of the second polarization component (eg, right-circular polarization) is emitted to the photo sensor unit 60. Here, the second arrangement state of the liquid crystal 131 may be a state in which the first arrangement state and the arrangement direction are different.

In this case, the light corresponding to the fingerprint signal K1 consists of the second polarization component, and the noise component K2 also has both the first and second polarization components, so that both the fingerprint signal K1 and the noise K2 It passes through the liquid crystal layer 130 (see FIG. 5). Accordingly, the fingerprint signal K1 and the noise component K2 are mixed in the optical signal (hereinafter, referred to as the second optical signal) detected by the photosensor.

When the detection of the above-described first and second optical signals is completed, the controller can remove noise mixed in the fingerprint information by comparing the first and second optical signals, thereby extracting only pure fingerprint signals and performing fingerprint recognition. There will be.

The above-described fingerprint recognition unit may be mounted on an electronic device. In this case, the electronic device may be, for example, a portable terminal such as a smart phone or a smart pad, a computer such as a notebook computer or a desktop, or a separate fingerprint recognition device connected to these devices and used for security purposes such as personal authentication.

In the above, preferred embodiments of the present invention have been described and illustrated using specific terms, but such terms are only for clarifying the present invention, and embodiments of the present invention and terms described are the technical spirit and scope of the following claims. It is obvious that various changes and changes can be made without departing from. These modified embodiments should not be individually understood from the spirit and scope of the present invention, but should be said to fall within the scope of the claims of the present invention.

10: transparent cover 20: polarizing unit
30: light emitting unit 40: substrate
50: voltage applying unit 60: photo sensor unit
100: variable retarder 110: upper substrate
120,120': electrode part 121: upper electrode
123: lower electrode 125: first electrode
127: second electrode 129: common electrode
130: liquid crystal layer 131: liquid crystal
140: lower substrate 150: protective layer
160: first insulating layer 161: second insulating layer

Claims (11)

Transparent cover; A polarizing unit provided under the transparent cover; A light emitting unit provided under the polarizing unit to emit light; A photo sensor unit provided under the light emitting unit; And a variable retarder provided between the light emitting part and the photo sensor part,
The variable retarder,
An electrode part selectively applying a first voltage and a second voltage and forming an electric field according to the first voltage or the second voltage; And a liquid crystal layer provided in a region to which the electric field is applied and including a liquid crystal,
The liquid crystal layer,
When the first voltage is applied, it is converted into a liquid crystal array state according to the application of the first voltage, and is configured to emit only light of a first polarization component of light incident on the liquid crystal layer to the photo sensor unit
When the second voltage is applied, it is converted into a liquid crystal array state according to the application of the second voltage, and is configured to emit only the light of the second polarization component among the light incident on the liquid crystal layer to the photo sensor unit. Fingerprint recognition unit using retarder.
The method of claim 1,
Further comprising a control unit for comparing the first optical signal and the second optical signal to extract fingerprint information from which noise has been removed,
The first optical signal is a signal detected by the photo sensor unit when the first voltage is applied, and is a signal corresponding to a noise component,
The second optical signal is a signal detected by the photo sensor unit when the second voltage is applied, and is a signal in which a fingerprint signal and a noise component are mixed. A fingerprint recognition unit using a variable retarder.
The method of claim 1,
The liquid crystal layer,
The liquid crystals are arranged along an electric field direction (hereinafter referred to as'first electric field direction') formed when the first voltage is applied,
The liquid crystals are arranged along an electric field direction (hereinafter referred to as a'second electric field direction') formed when the second voltage is applied,
The fingerprint recognition unit using a variable retarder, characterized in that the first electric field direction and the second electric field direction are configured to be orthogonal to each other.
The method of claim 1,
The first polarization component is left circularly polarized light,
The fingerprint recognition unit using a variable retarder, characterized in that the second polarization component is right circular polarization.
The method of claim 1,
A first insulating layer; And a second insulating layer formed on an upper layer than the first insulating layer,
The electrode part,
A common electrode formed under the first insulating layer; A first electrode patterned on the first insulating layer; And a second electrode patterned on the second insulating layer,
When the first voltage is applied,
By generating a transverse electric field between the first electrode and the common electrode, the liquid crystal is converted into a first arrangement state,
When the second voltage is applied,
By generating a transverse electric field between the second electrode and the common electrode, converting the liquid crystal into a second arrangement state,
The second arrangement state is a fingerprint recognition unit using a variable retarder, characterized in that the first arrangement and the arrangement direction is different.
The method of claim 1,
The electrode part,
A lower electrode; And an upper electrode facing the lower electrode,
The liquid crystal layer,
Fingerprint recognition unit using a variable retarder, characterized in that interposed between the lower electrode and the upper electrode.
The method of claim 1,
The liquid crystal layer,
When the first voltage is applied, a phase delay effect is generated in the direction of 45° for incident light,
A fingerprint recognition unit using a variable retarder, characterized in that, when the second voltage is applied, a phase delay effect is generated in a direction of -45° with respect to incident light.
The method of claim 1,
The light emitting unit,
A fingerprint recognition unit using a variable retarder, comprising a display device including a plurality of pixels.
The method of claim 1,
The fingerprint recognition unit using a variable retarder, characterized in that the polarizing unit includes a polarizer.
As an electronic device,
An electronic device comprising a fingerprint recognition unit using a variable retarder according to any one of claims 1 to 9.
The method of claim 10,
The electronic device,
Electronic device, characterized in that it is a smartphone, a smart pad or a notebook.

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