Capacitive fingerprint detection device and terminal equipment

Abstract

The present disclosure relates to a capacitive fingerprint detection device and a terminal device. The capacitive fingerprint detection device includes a packaging layer and a chip packaged in the packaging layer. The thickness of the packaging layer gradually decreases from the middle to the sides. The chip includes a capacitive fingerprint sensor and a processing component. The capacitance detection signal generated by the capacitive fingerprint sensor is output to the processing component. The processing component amplifies the capacitance detection signal corresponding to different areas of the packaging layer obtained by the capacitive fingerprint sensor with different gain values, obtains fingerprint images corresponding to each area based on the amplified capacitance detection signal, and obtains a synthesized fingerprint image based on the fingerprint images corresponding to each area. The synthesized fingerprint image is used for fingerprint recognition, wherein the gain value corresponding to the area located in the middle of the packaging layer is greater than the gain value corresponding to the areas located on both sides of the packaging layer, thereby overcoming the problem of uneven fingerprint signal strength caused by the uneven packaging layer and improving fingerprint detection capability.

Description

Technical Field

[0001] The present disclosure relates to the field of fingerprint recognition technology, and in particular to a capacitive fingerprint detection device and terminal equipment. Background Art

[0002] With the rapid development of communications and electronic information technology, smart terminal devices such as smartphones and / or tablet computers have become essential in people's daily lives. In addition to basic functions such as calls, text messages, videos, and entertainment, these terminal devices usually also have transaction functions such as payment, transfers, and top-ups, thus bringing great convenience to people's lives. However, at the same time, these convenient functions also pose certain security risks. This is because the implementation of these functions requires the bundling of sensitive private information on the terminal devices. Once this private information is leaked or misused, it will cause certain troubles to users and even cause serious losses. Therefore, by providing a fingerprint detection device such as a capacitive fingerprint detection device on the terminal device, fingerprint unlocking, login, payment, etc. can be realized, providing security protection for users.

[0003] Traditional capacitive fingerprint sensors are typically located directly below or on the back of a smartphone's screen. With the advancement of smartphone and other terminal technologies, manufacturers are increasing the screen-to-body ratio to enhance aesthetics, practicality, and consumer appeal. Consequently, capacitive fingerprint sensors are beginning to move from directly below the screen to the side. Side-mounted fingerprint sensors also offer advantages such as eliminating the need for a punch hole, enabling functional reuse, and providing a novel user experience.

[0004] Figure 1 This is a schematic diagram of a capacitive fingerprint unlocking device installed on the side of a terminal device in the prior art, where A, B, C, and D represent four directions. The diagram on the right shows the capacitive fingerprint detection device when the terminal device is viewed from direction A. As can be seen, to conform to the curvature of the terminal device's side, the capacitive fingerprint unlocking device has an uneven thickness, thicker in the middle and thinner at the sides. This uneven thickness results in uneven fingerprint signal strength, which reduces fingerprint detection capabilities. Summary of the Invention

[0005] In view of this, the present invention provides a capacitive fingerprint detection device and a terminal device.

[0006] On the one hand, a capacitive fingerprint detection device is proposed, which includes a packaging layer and a chip encapsulated in the packaging layer, the thickness of the packaging layer gradually decreases from the middle to the two sides, the chip includes a capacitive fingerprint sensor and a processing component, and the capacitance detection signal generated by the capacitive fingerprint sensor is output to the processing component; the processing component amplifies the capacitance detection signal corresponding to different areas of the packaging layer obtained by the capacitive fingerprint sensor with different gain values, obtains fingerprint images corresponding to each area according to the amplified capacitance detection signal, and obtains a synthesized fingerprint image according to the fingerprint images corresponding to each area, and the synthesized fingerprint image is used for fingerprint recognition, wherein the gain value corresponding to the area located in the middle of the packaging layer is greater than the gain value corresponding to the areas located on both sides of the packaging layer.

[0007] In a possible implementation, the region includes a second region located in the middle of the encapsulation layer, and a first region and a third region located on both sides of the encapsulation layer, wherein the first region and the third region are symmetrical with respect to the second region.

[0008] In one possible implementation, the processing component is configured to: amplify a first capacitance detection signal corresponding to a first area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signal; amplify a second capacitance detection signal corresponding to a second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; amplify a third capacitance detection signal corresponding to a third area with a third gain value, and obtain a third fingerprint image based on the amplified third capacitance detection signal; and splice the first fingerprint image, the second fingerprint image, and the third fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value, and the second gain value is greater than the third gain value.

[0009] In a possible implementation manner, the first gain value is equal to the third gain value.

[0010] In one possible implementation, the processing component is configured to: amplify a first capacitance detection signal corresponding to the first area and a third capacitance detection signal corresponding to the third area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signal; obtain a third fingerprint image based on the amplified third capacitance detection signal; amplify a second capacitance detection signal corresponding to the second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; and splice the first fingerprint image, the second fingerprint image, and the third fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value.

[0011] In one possible implementation, the processing component is configured to: amplify first capacitance detection signals corresponding to the first, second, and third regions with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signals; amplify second capacitance detection signals corresponding to the second region with a second gain value; obtain a second fingerprint image based on the amplified second capacitance detection signals, and replace a portion of the first fingerprint image corresponding to a position of the second fingerprint image with the second fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value.

[0012] In a possible implementation, obtaining a synthesized fingerprint image based on the fingerprint images corresponding to the respective regions further includes:

[0013] The pixel values ​​of each column in the fingerprint image corresponding to each area are added to the adjustment values ​​corresponding to each column, and a synthesized fingerprint image is obtained based on the fingerprint images corresponding to each area obtained after the addition.

[0014] In a possible implementation, in a cross section perpendicular to the column, the surface of the encapsulation layer is a curve, and the adjustment value is negatively correlated with the slope of the curve portion corresponding to the corresponding column.

[0015] In a possible implementation, in a cross section perpendicular to the columns, the surface of the encapsulation layer is a curve, and the adjustment value is negatively correlated with the distance of the corresponding column pair relative to the midpoint of the curve.

[0016] On the other hand, a terminal device is provided, which includes the capacitive fingerprint detection device described above.

[0017] By amplifying the capacitance detection signals corresponding to different areas of the packaging layer with different gain values, the capacitance detection signal obtained by the thicker area in the middle of the packaging layer can be amplified with a larger gain value, and the capacitance detection signal obtained by the thinner areas on both sides of the packaging layer can be amplified with a smaller gain value. This balances the stronger signals obtained by the thinner areas on both sides of the packaging layer and the weaker signals obtained by the thicker middle area, making the fingerprint image obtained by synthesizing the fingerprint images corresponding to each area uniform in intensity, while improving the accuracy and efficiency of fingerprint recognition.

[0018] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a capacitive fingerprint unlocking device arranged on the side of a terminal device in the prior art.

[0020] Figure 2Schematic diagrams of several exemplary capacitive fingerprint detection devices.

[0021] Figure 3a and Figure 3b FIG. 4 is a structural diagram of a capacitive fingerprint detection device according to an embodiment of the present disclosure.

[0022] Figure 4a and Figure 4b 、 Figure 5a and Figure 5b 、 Figure 6a and Figure 6b A schematic diagram showing a workflow of a processing component of a capacitive fingerprint detection device according to an embodiment of the present application is shown.

[0023] Figure 7 A structural diagram of an example of a processing component according to an embodiment of the present application is shown.

[0024] Figure 8 and Figure 9 2 is a schematic diagram of pixel values ​​in each column corresponding to adjustment values ​​according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0026] The word "exemplary" is used here exclusively to mean "serving as an example, embodiment or illustration". Any embodiment described here as "exemplary" is not necessarily to be construed as being superior or better than other embodiments. In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some instances, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present disclosure. In the following specific embodiments, a mobile phone is taken as an example to introduce the mobile terminal with side fingerprint recognition of the present invention, but the mobile terminal of the present invention is not limited to a mobile phone, and may also be a tablet computer, a laptop computer, and the like.

[0027] Capacitive fingerprint detection devices are commonly used in mobile phones and other terminal devices. They can include the following modules: coating, molding, and chip (die). The chip can integrate a capacitive fingerprint sensor and processing components. The coating and molding layers primarily protect the fragile chip underneath from damage from water stains, sweat, and scratches. The capacitive fingerprint sensor generates a charge difference based on the peaks and troughs of the fingerprint wave, forming a capacitive detection signal. The processing component converts the capacitive detection signal into a digital signal using its analog-to-digital converter (ADC). This digital signal is then processed to form a fingerprint image, enabling fingerprint recognition.

[0028] Figure 2 Schematic diagrams of several exemplary capacitive fingerprint detection devices. Figure 2 (a) is a schematic diagram of a commonly used capacitive fingerprint detection device. Commonly used capacitive fingerprint detection devices are usually set just below or on the back of the front screen. Since the encapsulation layer is flat and uniform, a uniform fingerprint signal can be obtained. However, due to the trend of thinner and thinner mobile phones in recent years, the curvature of the side surfaces is getting larger and larger, resulting in an uneven encapsulation layer, which is thick in the middle and thin on both sides. Figure 2 As shown in (b), the uneven encapsulation layer makes the fingerprint signal intensity uneven, which reduces the fingerprint detection capability.

[0029] Figure 3a and Figure 3b The capacitive fingerprint detection device of one embodiment of the present disclosure is a structural diagram. The capacitive fingerprint detection device can be applied to terminal devices such as smartphones, tablet computers, etc. For example, the capacitive fingerprint detection device can be arranged on the side of a smartphone, see Figure 1 shown.

[0030] The capacitive fingerprint detection device includes an encapsulation layer 401 and a chip 402 encapsulated within the encapsulation layer. The thickness of the encapsulation layer 401 gradually decreases from the center to the sides. The chip 402 includes a capacitive fingerprint sensor 4021 and a processing component 4022. The capacitive fingerprint sensor 4021 and the processing component 4022 can be independently provided or integrated into the same chip. Optionally, the capacitive fingerprint detection device may further include a coating (not shown).

[0031] The capacitance detection signal generated by the capacitive fingerprint sensor 4021 is output to the processing component 4022. The processing component 4022 amplifies the capacitance detection signal corresponding to different areas of the packaging layer 401 obtained by the capacitive fingerprint sensor 4021 with different gain values, obtains the fingerprint image corresponding to each area based on the amplified capacitance detection signal, and obtains a synthesized fingerprint image based on the fingerprint image corresponding to each area. The synthesized fingerprint image is used for fingerprint recognition, wherein the gain value corresponding to the area located in the middle of the packaging layer is greater than the gain value corresponding to the areas located on both sides of the packaging layer.

[0032] By amplifying the capacitance detection signals corresponding to different areas of the packaging layer with different gain values, the capacitance detection signal obtained by the thicker area in the middle of the packaging layer can be amplified with a larger gain value, and the capacitance detection signal obtained by the thinner areas on both sides of the packaging layer can be amplified with a smaller gain value. This balances the stronger signals obtained by the thinner areas on both sides of the packaging layer and the weaker signals obtained by the thicker middle area, making the fingerprint image obtained by synthesizing the fingerprint images corresponding to each area uniform in intensity, while improving the accuracy and efficiency of fingerprint recognition.

[0033] The encapsulation layer 401 may include at least three regions located in the middle and on both sides of the encapsulation layer. The regions on both sides may be symmetrical with respect to the middle region. Figure 1 The “middle” and “both sides” in the cross section perpendicular to the A direction (the A direction is usually the length direction of the side of the terminal device). Figure 3b As shown, the capacitive fingerprint sensor 4021 can be divided into three areas: a second area located in the middle of the encapsulation layer, and a first area and a third area located on both sides of the encapsulation layer. The first area and the third area are symmetrical with respect to the second area. Those skilled in the art will appreciate that the encapsulation layer 401 can also be divided into more than three areas, for example, five or seven areas. More areas can improve the accuracy of balancing, while fewer areas can reduce processing difficulty and cost. The embodiments of the present application do not limit the specific number of areas.

[0034] The processing component 4022 amplifies the capacitance detection signals corresponding to different areas of the packaging layer 401 obtained by the capacitive fingerprint sensor 4021 with different gain values, obtains fingerprint images corresponding to each area based on the amplified capacitance detection signals, and obtains a synthesized fingerprint image based on the fingerprint images corresponding to each area, which can be achieved in different ways.

[0035] Figure 4a and Figure 4bA schematic diagram illustrates a workflow of a processing component of a capacitive fingerprint detection device according to an embodiment of the present application. Taking the packaging layer 401 including a first region, a second region, and a third region as an example, in one possible implementation, the processor may amplify a first capacitance detection signal corresponding to the first region using a first gain value; obtain a first fingerprint image based on the amplified first capacitance detection signal; amplify a second capacitance detection signal obtained via the second region using a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; amplify a third capacitance detection signal corresponding to the third region using a third gain value, and obtain a third fingerprint image based on the amplified third capacitance detection signal; and splice the first, second, and third fingerprint images to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value, and the second gain value is greater than the third gain value.

[0036] In this way, three frames of fingerprint images corresponding to the first area, the second area, and the third area can be obtained. Each frame of fingerprint image is amplified with a different gain, and the image intensity tends to be uniform. The fingerprint images can be spliced ​​in sequence according to the positional relationship to obtain a complete fingerprint image, and fingerprint recognition can be performed.

[0037] The first gain value may be equal to the third gain value. In this case, the first region and the third region may be symmetrical with respect to the second region.

[0038] Figure 5a and Figure 5b A schematic diagram showing a workflow of a processing component of a capacitive fingerprint detection device according to an embodiment of the present application is shown. Figure 5a and Figure 5b The processing component 4022 can amplify the first capacitance detection signal corresponding to the first area and the third capacitance detection signal corresponding to the third area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signal; obtain a third fingerprint image based on the amplified third capacitance detection signal; amplify the second capacitance detection signal corresponding to the second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; and splice the first fingerprint image, the second fingerprint image, and the third fingerprint image to obtain the synthesized fingerprint image.

[0039] In this way, the processing component can complete the acquisition of three fingerprint images by setting the first gain value and the second gain value. The fingerprint images corresponding to each area can be obtained while reducing one gain value setting operation. The first and third fingerprint images corresponding to the first and third areas are obtained by the first gain value, and the second fingerprint image corresponding to the second area is obtained by the second gain value. The fingerprint images are spliced ​​to obtain a complete fingerprint image with uniform intensity.

[0040] Figure 6a and Figure 6b A schematic diagram showing a workflow of a processing component of a capacitive fingerprint detection device according to an embodiment of the present application is shown. Figure 6a and Figure 6b The processing component 4022 can amplify the first capacitance detection signals corresponding to the first area, the second area, and the third area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signals; amplify the second capacitance detection signal corresponding to the second area with a second gain value; obtain a second fingerprint image based on the amplified second capacitance detection signal, and replace the part of the first fingerprint image corresponding to the position of the second fingerprint image with the second fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value.

[0041] In this way, the processing component first obtains a complete fingerprint image, i.e., a first fingerprint image, with a first gain value, and then obtains a fingerprint image of the middle area, i.e., a second fingerprint image, with a second gain value. By replacing the corresponding portion of the first fingerprint image with the second fingerprint image, a synthetic fingerprint image with uniform intensity can be obtained.

[0042] The processing component 4022 amplifies the capacitance detection signals corresponding to different areas of the packaging layer 401 with different gain values, which can also be achieved in different ways.

[0043] Figure 7 FIG. 4 is a block diagram illustrating an example of a processing component according to an embodiment of the present application. The processing component 4022 may include an analog-to-digital converter (ADC) 4022a, a digital signal processing module 4022b, and a register 4022c.

[0044] The register 4022c may store gain values ​​corresponding to different regions of the encapsulation layer 401, for example, a first gain value corresponding to the first region and the third region, and a second gain value corresponding to the second region.

[0045] The output of the capacitive fingerprint sensor 4021 can be an array of capacitance detection signals corresponding to each pixel point of the fingerprint image, and the analog-to-digital converter 4022a can convert the capacitance detection signals column by column, where the thickness of the packaging layer corresponding to each column of capacitance detection signals is the same. Figure 1 The distribution of pixels in each column can be seen in the A direction. Figure 3b .

[0046] In one possible implementation, the capacitance detection signal can be amplified with different gain values ​​in various ways in the processing component 4022 based on relevant technologies. For example, a variable-gain analog front end can be added to the input of the analog-to-digital converter 4022a, and the gain of the analog front end can be set according to the gain value stored in the register 4022c to achieve variable-gain amplification. Alternatively, a variable-gain digital processing circuit can be added to the output of the analog-to-digital converter 4022a, and the gain of the digital circuit can be set according to the gain value stored in the register 4022c to achieve variable-gain amplification. This application does not limit the specific implementation methods.

[0047] In one possible implementation, obtaining a synthesized fingerprint image based on the fingerprint images corresponding to each region further includes: adding the pixel values ​​of each column in the fingerprint images corresponding to each region to the adjustment values ​​corresponding to each column, and obtaining a synthesized fingerprint image based on the fingerprint images corresponding to each region obtained after the addition. Obtaining a synthesized fingerprint image based on the processed fingerprint images corresponding to each region further balances the effect of the encapsulation layer thickness on the efficiency of capacitive fingerprint detection.

[0048] For example, in a cross section perpendicular to the above-mentioned columns (i.e., direction A) (see Figure 3a The encapsulation layer surface is a curve, and the adjustment value is negatively correlated with the slope of the curve portion corresponding to the corresponding column. The slope represents the speed of change of the variable at a point on the curve. The slope can be represented by the tangent of the angle between the tangent line at a point on the curve and the horizontal direction. Figure 8 Schematic diagram of the corresponding adjustment values ​​of each column of pixel values ​​according to an embodiment of the present application. Figure 8 The column where pixel a is located has a slope of K a , the slope of the column where pixel b is located is K b , the column where pixel c is located has a slope of K c From the above definition of slope, K a >K b >K c . As shown in the figure, the larger the slope, the smaller the corresponding packaging layer thickness. In order to balance the influence of the packaging layer thickness on the fingerprint image, the pixel value of each column of pixels can be added with a corresponding adjustment value Δs, and the added adjustment value Δs can be negatively correlated with the corresponding slope, that is, the slope corresponding to the middle area close to the packaging layer is smaller, and the added adjustment value is larger, and the slope corresponding to the area close to the two sides of the packaging layer is larger, and the added adjustment value is smaller, so as to compensate for the attenuation of the capacitance detection signal caused by the thicker thickness of the middle of the packaging layer. Therefore, through the above method, the influence of the packaging layer thickness on the fingerprint image obtained by the capacitive fingerprint detection device can be balanced.

[0049] Another possible implementation is Figure 9In a cross section perpendicular to the columns, the surface of the encapsulation layer is a curve, and the adjustment value is negatively correlated with the distance of the corresponding column pair relative to the midpoint of the curve.

[0050] Figure 9 Schematic diagram of the corresponding adjustment values ​​of each column of pixel values ​​according to an embodiment of the present application. Figure 9 As shown, in a cross section perpendicular to the column direction, the horizontal direction is the X-axis, the vertical direction is the Y-axis, and the intersection of the centerline of the encapsulation layer and the X-axis is the origin 0. The thickness of the encapsulation layer changes with the absolute value of the X-axis coordinate (i.e., the distance relative to the midpoint of the curve). Specifically, the larger the absolute value of the X-axis (|x|), the smaller the thickness of the encapsulation layer. Therefore, the adjustment value can be made negatively correlated with the distance of the corresponding column relative to the midpoint of the curve, that is, the closer the column is to the midpoint (e.g., column a), the larger the adjustment value added, and the farther the column is from the midpoint (e.g., column c), the larger the adjustment value added, to compensate for the attenuation of the capacitance detection signal caused by the thicker thickness in the middle of the encapsulation layer. Therefore, through the above method, the influence of the encapsulation layer thickness on the fingerprint image obtained by the capacitive fingerprint detection device can also be balanced.

[0051] Those skilled in the art should understand that the method of setting the adjustment value is not limited to the above method. The adjustment value can also be set to a negative value, or the adjustment value is not set to change column by column, but remains unchanged within a range of several columns. This application does not impose any restrictions on this.

[0052] In a possible implementation, an embodiment of the present application further provides a terminal device, which includes the capacitive fingerprint detection device described above.

[0053] In an exemplary application scenario, taking the terminal device as a smartphone as an example, the user touches the surface of the capacitive fingerprint detection device on the side of the smartphone with his finger, and the capacitive fingerprint sensor generates a capacitance detection signal that is output to the processing component. The processing component amplifies the capacitance detection signals corresponding to different areas of the packaging layer according to a preset gain value, and generates the first fingerprint image, second fingerprint image and third fingerprint image mentioned above according to the amplified capacitance detection signal. When the three frames of fingerprint image acquisition are completed, the first fingerprint image, the second fingerprint image and the third fingerprint image are spliced, and the pixel value can be further adjusted by column to obtain a complete fingerprint image for fingerprint recognition to realize subsequent unlocking, payment and other applications.

[0054] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technical improvements to existing technologies, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A capacitive fingerprint detection device, characterized in that: The capacitive fingerprint detection device includes a packaging layer and a chip packaged in the packaging layer. The thickness of the packaging layer gradually decreases from the middle to both sides. The chip includes a capacitive fingerprint sensor and a processing component. The capacitance detection signal generated by the capacitive fingerprint sensor is output to the processing component; The processing component amplifies capacitance detection signals corresponding to different regions of the packaging layer obtained by the capacitive fingerprint sensor at different gain values, obtains fingerprint images corresponding to each region based on the amplified capacitance detection signals, and obtains a synthesized fingerprint image based on the fingerprint images corresponding to each region. The synthesized fingerprint image is used for fingerprint recognition, wherein the gain value corresponding to the region located in the middle of the packaging layer is greater than the gain value corresponding to the regions located on both sides of the packaging layer; The regions include a second region located in the middle of the encapsulation layer, and a first region and a third region located on both sides of the encapsulation layer, wherein the first region and the third region are symmetrical with respect to the second region; The processing component is configured to: amplify a first capacitance detection signal corresponding to a first area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signal; amplify a second capacitance detection signal corresponding to a second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; amplify a third capacitance detection signal corresponding to a third area with a third gain value, and obtain a third fingerprint image based on the amplified third capacitance detection signal; and splice the first fingerprint image, the second fingerprint image, and the third fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value, and the second gain value is greater than the third gain value; or, The processing component is configured to: amplify a first capacitance detection signal corresponding to the first area and a third capacitance detection signal corresponding to the third area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signal; obtain a third fingerprint image based on the amplified third capacitance detection signal; amplify a second capacitance detection signal corresponding to the second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signal; and splice the first fingerprint image, the second fingerprint image, and the third fingerprint image to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value; or The processing component is configured to: amplify first capacitance detection signals corresponding to the first area, the second area, and the third area with a first gain value, and obtain a first fingerprint image based on the amplified first capacitance detection signals; amplify second capacitance detection signals corresponding to the second area with a second gain value, and obtain a second fingerprint image based on the amplified second capacitance detection signals; and replace a portion of the first fingerprint image corresponding to a position of the second fingerprint image with the second fingerprint image, to obtain the synthesized fingerprint image, wherein the second gain value is greater than the first gain value.

2. The device according to claim 1, characterized in that The first gain value is equal to the third gain value.

3. The device according to claim 1 or 2, characterized in that The synthesized fingerprint image is obtained according to the fingerprint images corresponding to each area, and further includes: The pixel values ​​of each column in the fingerprint image corresponding to each area are added to the adjustment values ​​corresponding to each column, and a synthesized fingerprint image is obtained based on the fingerprint images corresponding to each area obtained after the addition.

4. The device according to claim 3, characterized in that In a cross section perpendicular to the columns, the surface of the encapsulation layer is a curve, and the adjustment value is negatively correlated with the slope of the curve portion corresponding to the corresponding column.

5. The device according to claim 3, characterized in that In a cross section perpendicular to the columns, the surface of the encapsulation layer is a curve, and the adjustment value is negatively correlated with the distance of the corresponding column pair relative to the midpoint of the curve.

6. A terminal device, characterized in that: The terminal device includes the capacitive fingerprint detection device according to any one of claims 1-5.

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