Capacitive pressure sensor and electronic pen

Abstract

The utility model particularly relates to a capacitive pressure sensor and an electronic pen, the capacitive pressure sensor comprises a variable capacitor and two signal lines connected with the variable capacitor, the variable capacitor comprises a buffer pad, a conducting strip, an annular gasket and a dielectric layer which are stacked in sequence, and one side of the buffer pad is arranged to be in contact with an outer pressure part; the conducting strip is attached to one side, back to the external pressure piece, of the buffer pad and is connected with a signal line; the annular gasket is arranged on one side, back to the buffer pad, of the conducting strip, and a through hole for deformation of the conducting strip is formed in the middle of the annular gasket; the dielectric layer is arranged on the side, back to the conducting strip, of the annular gasket, a conducting layer is arranged on the side, back to the annular gasket, of the dielectric layer, and the conducting layer is connected with the other signal line. According to the capacitive pressure sensor provided by the invention, the buffer pad, the conducting strip and the annular gasket are arranged as independent individuals, and each component can be flexibly arranged according to the respective fatigue use condition, so that the risk of fatigue failure after long-time use is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electronic equipment, and in particular to a capacitive pressure sensor and an electronic pen. Background Art

[0002] This section merely provides background information related to the present disclosure and is not necessarily prior art.

[0003] Currently, capacitive pressure sensors in electronic devices such as electronic pens mostly use a design that combines a conductive soft film with a conductive ceramic plate. The conductive soft film needs to have both the ability to buffer external forces and the ability to conduct electricity. However, the conductivity of the conductive soft film is relatively poor, and its wear resistance and flexibility deteriorate with age, which adversely affects its conductivity. This results in poor performance of the capacitive pressure sensor in the electronic pen, affecting its sensitivity and normal performance. Utility Model Content

[0004] The purpose of this application is to at least solve the technical problem that capacitive pressure sensors are prone to fatigue failure after long-term use. This purpose is achieved through the following technical solutions:

[0005] The first aspect of the present application provides a capacitive pressure sensor, which includes a variable capacitor and two signal lines connecting the variable capacitor. The variable capacitor includes a buffer pad, a conductive sheet, an annular gasket and a dielectric layer stacked in sequence. One side of the buffer pad is configured to contact the external pressure piece; the conductive sheet is attached to the side of the buffer pad facing away from the external pressure piece and is connected to a signal line; the annular gasket is arranged on the side of the conductive sheet facing away from the buffer pad, and a through hole is formed in the middle of the annular gasket for the conductive sheet to deform; the dielectric layer is arranged on the side of the annular gasket facing away from the conductive sheet, and a conductive layer is arranged on the side of the dielectric layer facing away from the annular gasket, and the conductive layer is connected to another signal line.

[0006] It will be understood by those skilled in the art that the capacitive pressure sensor proposed in this application sets the buffer pad, conductive sheet, and annular gasket as independent individuals. Compared with an integrated structure, each component can be flexibly set according to its respective fatigue usage conditions, thereby reducing the risk of fatigue failure after long-term use.

[0007] Specifically, when the external pressure member squeezes the buffer pad, the buffer pad will squeeze the conductive sheet, and the conductive sheet will deform as the pressure of the buffer pad deforms. The deformed part of the conductive sheet will pass through the through hole of the annular gasket and contact the dielectric layer. As the pressure of the external pressure member changes, the contact area between the conductive sheet and the dielectric layer will also change accordingly, which will cause the capacitance value of the capacitive pressure sensor to change accordingly. The change in the capacitance value of the capacitive pressure sensor represents the pressure change of the external pressure member.

[0008] In some embodiments, the conductive sheet includes a polyimide substrate and a copper plating layer and a nickel-chromium alloy plating layer disposed on the polyimide substrate.

[0009] In some embodiments, the through hole is formed with a deformation space in the direction of the conductive sheet toward the dielectric layer, and the stroke of the deformation space is set to be consistent with the fatigue resistance deformation limit of the conductive sheet.

[0010] In some embodiments, the travel range of the deformation space is set to 0.02mm-0.05mm.

[0011] In some embodiments, the conductive sheet is configured to at least cover the through hole, and / or a projection of the conductive layer onto the annular gasket is configured to at least cover the through hole.

[0012] In some embodiments, the conductive sheet includes a deformable portion covering the through hole, and a lap portion arranged around the deformable portion and lapped to the annular gasket. The deformable portion can be deformed toward the dielectric layer through the through hole under the pressure of the buffer pad.

[0013] In some embodiments, the conductive sheet is provided with a tab located at the periphery of the annular gasket, and the signal line includes a positive signal line connected to the tab.

[0014] In some embodiments, the other signal line includes a negative signal line connected to the conductive layer, the negative signal line is provided with a patch connected to the conductive layer, and a projection of the patch onto the annular gasket is configured to at least cover the through hole.

[0015] The second aspect of the application provides an electronic pen, which is a capacitive pressure sensor according to the first aspect of the application. The external pressure member includes a core assembly of the electronic pen, and both signal lines are connected to the electronic control board of the electronic pen.

[0016] In some embodiments, the refill assembly includes a refill and a refill clip sleeved onto an end of the refill, wherein the refill clip is provided with an arc-shaped contact head that contacts the buffer pad. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0018] Figure 1 This is a schematic diagram of the disassembled structure of an electronic pen according to an embodiment of the present application;

[0019] Figure 2 for Figure 1 The schematic diagram of the assembly structure of the electronic pen shown;

[0020] Figure 3 for Figure 2 A bottom view of the electronic pen shown;

[0021] Figure 4 for Figure 2 A cross-sectional view of the electronic pen shown;

[0022] Figure 5 for Figure 4 A partial structural cross-sectional view of the electronic pen shown;

[0023] Figure 6 This is a schematic structural diagram of an electronic pen in a natural state according to an embodiment of the present application;

[0024] Figure 7 This is a schematic structural diagram of an electronic pen in a lightly pressed state according to an embodiment of the present application;

[0025] Figure 8 This is a structural schematic diagram of an electronic pen in a heavily pressed state according to an embodiment of the present application.

[0026] The accompanying drawings are numerals as follows:

[0027] 100. Electronic pen;

[0028] 10. External pressure member (pen core assembly); 11. Pen core; 12. Pen core clip;

[0029] 20. Cushion;

[0030] 30. Conductive sheet; 31. Deformation portion; 32. Lapping portion; 33. Tab;

[0031] 40. annular gasket; 41. through hole;

[0032] 50. Dielectric layer; 51. Conductive layer;

[0033] 60. A signal line (positive signal line); 61. A connection point;

[0034] 70. Another signal line (negative signal line); 71. Another connection point;

[0035] 80. Electric control panel;

[0036] 90. Pen stand; 91. Inner stand; 92. Outer stand. DETAILED DESCRIPTION

[0037] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that the capacitive pressure sensor of the present application described in this application through an electronic pen is only a preferred embodiment and does not limit the scope of application of the capacitive pressure sensor. For example, the capacitive pressure sensor of the present application can also be used in electronic devices such as touch screens, and this adjustment does not deviate from the scope of protection of the capacitive pressure sensor of the present application.

[0038] It should be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, as used herein, the singular forms "a," "an," and "the" may also be intended to include the plural forms. The terms "comprise," "include," and "have" are inclusive and, therefore, specify the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0039] Although the terms first, second, etc. may be used herein to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply a sequence or order when used herein. In addition, in the description of this application, unless otherwise clearly specified and limited, the terms "set" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0040] For ease of description, spatial relative terms can be used in the text to describe the relationship of an element or feature relative to another element or feature as shown in the figure, and these relative terms are, for example, "end", "length", "inside", "outside", etc. Such spatial relative terms are intended to include different orientations of the mechanism in use or operation except the orientation depicted in the figure. For example, if the mechanism in the figure flips, the element described as "below other elements or features" or "below other elements or features" will then be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." can include the orientation on and below. The mechanism can be oriented in addition (rotated 90 degrees or in other directions) and the spatial relative descriptors used in the text are interpreted accordingly.

[0041] The capacitive pressure sensors of existing electronic devices such as electronic pens use a conductive soft film that combines a buffer pad and a conductive sheet. The conductive soft film is made of a combination of flexible and conductive materials, and its conductivity is inherently poor. In addition, after long-term use, the conductive soft film will wear out, and its conductivity will become worse, affecting its sensitivity and normal performance.

[0042] For example, taking an electronic pen as an example, in a test of the use of the electronic pen, after the electronic pen is clicked 5,000 times, the output capacitance value of the capacitive pressure sensor of the electronic pen will have an error of about 20%. The reason is that during the use of the electronic pen, the pen core assembly of the electronic pen directly presses the conductive soft film, causing the middle part of the conductive soft film to be stretched and thinned, and the deformation is large. After the electronic pen is repeatedly clicked, the conductive soft film is worn and the internal molecular structure changes. Compared with the conductive soft film before wear, under the same pressure, the deformation of the conductive soft film after wear will increase significantly, resulting in a significant deviation in the external pressure represented by the conductive soft film.

[0043] In order to address the problem of detection distortion caused by wear of the conductive soft film in existing electronic devices such as electronic pens after long-term use, this application proposes to set the buffer pad, conductive sheet, and annular gasket of the capacitive pressure sensor as independent individuals. Compared with an integrated structure, each component can be flexibly set according to its own fatigue usage conditions, reducing the risk of fatigue failure after long-term use.

[0044] like Figures 1 to 8As shown, the capacitive pressure sensor provided in the embodiment of the present application includes a variable capacitor and two signal lines connecting the variable capacitor. The variable capacitor includes a buffer pad 20, a conductive sheet 30, an annular gasket 40 and a dielectric layer 50 stacked in sequence. One side of the buffer pad 20 is set to contact the external pressure member 10; the conductive sheet 30 is attached to the side of the buffer pad 20 facing away from the external pressure member 10 and is connected to a signal line 60; the annular gasket 40 is arranged on the side of the conductive sheet 30 facing away from the buffer pad 20, and a through hole 41 is formed in the middle of the annular gasket 40 for the conductive sheet 30 to deform; the dielectric layer 50 is arranged on the side of the annular gasket 40 facing away from the conductive sheet 30, and a conductive layer 51 is provided on the side of the dielectric layer 50 facing away from the annular gasket 40, and the conductive layer 51 is connected to another signal line 70.

[0045] In this embodiment, the capacitive pressure sensor proposed in this application sets the buffer pad 20, the conductive sheet 30, and the annular gasket 40 as independent individuals. Compared with the integrated structure, each component can be flexibly set according to its respective fatigue usage conditions, thereby reducing the risk of fatigue failure after long-term use.

[0046] Specifically, when the external pressure member 10 squeezes the buffer pad 20, the buffer pad 20 will squeeze the conductive sheet 30, and the conductive sheet 30 will be deformed as the pressure of the buffer pad 20 deforms. The deformed part of the conductive sheet 30 will pass through the through hole 41 of the annular gasket 40 and contact the dielectric layer 50. As the pressure of the external pressure member 10 changes, the contact area between the conductive sheet 30 and the dielectric layer 50 will also change accordingly, which will cause the capacitance value of the capacitive pressure sensor to change accordingly. The pressure change of the external pressure member 10 is represented by the change in the capacitance value of the capacitive pressure sensor.

[0047] The output capacitance value of the capacitive pressure sensor is only related to the contact area between the front of the conductive sheet 30 and the dielectric layer 50. The buffer pad 20 on the back of the conductive sheet 30 only plays a buffering role. The deformation of the buffer pad 20 does not affect the force conduction of the capacitive pressure sensor, and has little effect on the effective contact area between the conductive sheet 30 and the dielectric layer 50. This can reduce the impact of the buffer pad 20 on the conductive sheet 30 and the output capacitance value of the capacitive pressure sensor after long-term use and wear.

[0048] The buffer pad 20 is made of a flexible material such as rubber that is not conductive. The buffer pad 20 plays a buffering role on the external pressure member 10. When the pressure of the external pressure member 10 increases, the contact area between the conductive sheet 30 and the dielectric layer 50 gradually increases. The output capacitance value of the capacitive pressure sensor changes with the contact area between the conductive sheet 30 and the dielectric layer 50, thereby representing the pressure change of the external pressure member 10 through the output capacitance value of the capacitive pressure sensor.

[0049] The dielectric layer 50 is made of a ceramic body, and the conductive layer 51 is sintered on the side of the ceramic body, forming two electrodes of the capacitive pressure sensor together with the conductive sheet 30. The two signal lines are composed of metal connectors such as copper needles. The two copper needles are respectively connected to the conductive sheet 30 and the conductive layer 51, serving as the two electrode leads output by the capacitive pressure sensor. One end of a signal line 60 is connected to the conductive sheet 30, and the other end is welded to the positive input point of the circuit board through a connection point 61. One end of another signal line 70 is connected to the conductive layer 51, and the other end is welded to the negative input point of the circuit board through another connection point 71, which is convenient for welding and assembly.

[0050] It should be noted that the embodiments of the present application do not limit the specific shape and material of the conductive sheet 30, because the invention point of the present application is to set the buffer pad 20, the conductive sheet 30, and the annular gasket 40 as independent individuals. As for the specific shape and material of the conductive sheet 30, it includes a variety of embodiments. For example, the conductive sheet 30 can be set as a square copper sheet or a circular aluminum sheet. These embodiments all fall within the protection scope of the conductive sheet 30 of the present application. As for other embodiments of the conductive sheet 30, they will not be elaborated one by one here.

[0051] The specific structure and material of the conductive sheet 30 according to the embodiment of the present application are described in detail below.

[0052] In some embodiments, the conductive sheet 30 includes a polyimide substrate and a copper plating layer and a nickel-chromium alloy plating layer disposed on the polyimide substrate.

[0053] In this embodiment, the conductive sheet 30 is manufactured using a polyimide substrate and a copper plating and a nickel-chromium alloy plating process. The polyimide substrate has good flexibility, the copper plating has good conductivity, and the nickel-chromium alloy plating has good wear resistance. These properties of the conductive sheet 30 can improve the stability of the capacitive pressure sensor. The use of the conductive sheet 30 can enhance the sensitivity of the capacitive pressure sensor in electronic devices such as the electronic pen 100, and can provide customers with a better user experience.

[0054] Specifically, the polyimide substrate of the conductive sheet 30 has good elasticity. For example, the elastic modulus of biphenyl polyimide (UpilexS) is 400 MPa, and the elastic modulus of polyimide fiber can reach 500 MPa, which is second only to carbon fiber. As a result, the conductive sheet 30 has good elastic properties and is not prone to plastic deformation during long-term use.

[0055] like Figures 6 to 8 As shown, in some embodiments, the through hole 41 forms a deformation space for the conductive sheet 30 toward the dielectric layer 50 , and the stroke L of the deformation space is set to be consistent with the fatigue deformation limit of the conductive sheet 30 .

[0056] In this embodiment, the external pressure member 10 (such as the refill assembly 10) pushes the conductive sheet 30 into contact with the dielectric layer 50 after being buffered by the buffer pad 20. The deformation size of the conductive sheet 30 toward the dielectric layer 50 is determined by the deformation space inside the through hole 41. In order to maintain the deformation size of the conductive sheet 30 toward the dielectric layer 50 within the anti-fatigue deformation limit, the embodiment of the present application proposes setting the stroke L of the deformation space of the through hole 41 to be consistent with the anti-fatigue deformation limit of the conductive sheet 30, so that the conductive sheet 30 can have better sensitivity and it can also make it difficult for the conductive sheet 30 to produce fatigue and no plastic deformation, thereby improving the working reliability and stability of the capacitive pressure sensor.

[0057] Specifically, since the fatigue deformation limits of different types of conductive sheets 30 are inconsistent, the embodiment of the present application does not limit the fatigue deformation limit of the conductive sheet 30 and the travel L of the deformation space of the through hole 41 .

[0058] like Figures 6 to 8 As shown, in some embodiments, the stroke L range of the deformation space is set to 0.02mm-0.05mm.

[0059] In this embodiment, the conductive sheet 30 is manufactured using a polyimide substrate and copper and nickel-chromium alloy plating processes. The present application proposes setting the thickness of the annular gasket 40 to a range of 0.02mm-0.05mm. Specifically, using a deformation range of 0.025mm as an example, tests have shown that after 500,000 clicks of the electronic pen 100 and a writing pressure of 0.5N, the output capacitance deviation rate of the capacitive pressure sensor is only 5%.

[0060] like Figures 6 to 8 As shown, in some embodiments, the conductive sheet 30 is configured to at least cover the through hole 41 , and / or the projection of the conductive layer 51 onto the annular gasket 40 is configured to at least cover the through hole 41 .

[0061] In this embodiment, since the capacitance value of the capacitive pressure sensor is determined by the contact area between the conductive sheet 30 and the dielectric layer 50, and the contact area between the conductive sheet 30 and the dielectric layer 50 is related to the size of the through hole 41 and the size of the external pressure, under the premise that the size of the through hole 41 is determined, in order to enable the capacitance value of the capacitive pressure sensor to accurately represent the external pressure and reduce the radial gap between the conductive sheet 30 and the through hole 41 to produce unstable interference factors on the capacitance value of the capacitive pressure sensor, the embodiment of the present application proposes to set the conductive sheet 30 to at least cover the through hole 41, so that in the process of external pressure change, the conductive sheet 30 always covers the through hole 41. At this time, the change in the capacitance value of the capacitive pressure sensor is determined by the change in external pressure, thereby improving the accuracy of the characterization of the capacitance value change of the capacitive pressure sensor to the external pressure change.

[0062] Furthermore, an embodiment of the present application proposes that the projection of the conductive layer 51 onto the annular gasket 40 is set to at least cover the through hole 41, so that the conductive layer 51 can cooperate with the conductive sheet 30, thereby reducing the unstable interference factor caused by the through hole 41 to the capacitance value of the capacitive pressure sensor.

[0063] like Figure 1 As shown, in some embodiments, the conductive sheet 30 includes a deformation portion 31 covering the through hole 41, and a lap portion 32 arranged around the deformation portion 31 and lapped to the annular gasket 40. The deformation portion 31 can be deformed toward the dielectric layer 50 through the through hole 41 under the push of the buffer pad 20.

[0064] In this embodiment, by setting the overlapping portion 32 of the conductive sheet 30 on the annular gasket 40, and then determining the contact area between the conductive sheet 30 and the dielectric layer 50 and the capacitance value of the capacitive pressure sensor through the deformation portion 31 of the conductive sheet 30, the deformation size of the deformation portion 31 of the conductive sheet 30 can represent the magnitude of the external pressure, thereby achieving accurate transmission of the external pressure to the deformation portion 31, the contact area between the deformation portion 31 and the dielectric layer 50, and the capacitance value of the capacitive pressure sensor, thereby reducing the movement or shaking of the conductive sheet 30 under the action of the external pressure, which affects the accurate characterization between the capacitance value of the capacitive pressure sensor and the external pressure.

[0065] like Figure 1 As shown, in some embodiments, the conductive sheet 30 is provided with a tab 33 located at the periphery of the annular gasket 40 , and a signal line 60 includes a positive signal line connected to the tab 33 .

[0066] In this embodiment, by connecting the positive signal line to the tab 33 of the conductive sheet 30 located on the periphery of the annular gasket 40, the positive signal line is reduced from scratching the annular gasket 40 and causing pulling on the conductive sheet 30, thereby reducing the interference of the positive signal line on the relative movement between the conductive sheet 30 and the annular gasket 40.

[0067] In addition, by connecting the positive signal line to the tab 33 of the conductive sheet 30 located outside the annular gasket 40, the positive signal line does not need to bend to avoid the annular gasket 40 and the dielectric layer 50, thereby reducing the risk of the positive signal line being damaged or broken due to bending.

[0068] like Figure 4 and Figure 5 As shown, in some embodiments, another signal line 70 includes a negative signal line connected to the conductive layer 51 , the negative signal line is provided with a patch connected to the conductive layer 51 , and the projection of the patch onto the annular gasket 40 is set to at least cover the through hole 41 .

[0069] In this embodiment, the projection of the patch of the negative signal line onto the annular gasket 40 is set to at least cover the through hole 41, so that the patch of the negative signal line can cooperate with the conductive sheet 30, so that the capacitance value of the capacitive pressure sensor is determined by the corresponding areas of the conductive sheet 30 and the patch of the negative signal line. On the premise that the size of the through hole 41 is determined, the radial gap between the patch of the negative signal line and the through hole 41 is reduced to reduce the unstable interference factor on the capacitance value of the capacitive pressure sensor, thereby improving the accuracy of the characterization of the capacitance value change of the capacitive pressure sensor to the external pressure change.

[0070] like Figures 1 to 8 As shown, the second aspect of the present application provides an electronic pen 100, which is a capacitive pressure sensor according to the first aspect of the present application, the external pressure member 10 is the refill assembly 10 of the electronic pen 100, and both signal lines are connected to the electronic control board 80 of the electronic pen 100.

[0071] In this embodiment, the working principle of the electronic pen 100 is as follows: when the refill assembly 10, i.e., the external pressure member 10, receives writing pressure, the refill assembly 10 can squeeze and contact the buffer pad 20 under the pressure of the pen tip, and then the buffer pad 20 will squeeze and contact the conductive sheet 30. The conductive sheet 30 will deform as the pressure of the buffer pad 20 deforms, and the deformed portion 31 of the conductive sheet 30 will pass through the through hole 41 of the annular gasket 40 to contact the dielectric layer 50. As the writing pressure of the refill assembly 10 changes, the contact area between the conductive sheet 30 and the dielectric layer 50 will also change accordingly, which will cause the capacitance value of the dielectric layer 50 connected to the PCB circuit of the electronic pen 100 to change. The change in the capacitance value of the capacitive pressure sensor can accurately represent the writing pressure of the refill assembly 10.

[0072] Specifically, the electronic pen 100 using the capacitive pressure sensor of the embodiment of the present application has relatively rich pressure feedback: the output capacitance value of the capacitive pressure sensor is linearly related to the writing pressure of the electronic pen 100. Moreover, since the thickness of the conductive sheet 30 of the capacitive pressure sensor is relatively small, the deformation of the conductive sheet 30 in contact with the dielectric layer 50 is relatively small. A pressure within a force of 2g can cause the conductive sheet 30 to contact the dielectric layer 50 and generate a capacitance output change value. The capacitance value output by the capacitive pressure sensor can increase linearly with the increase of the writing pressure of the electronic pen 100, and then a rich pressure sensitivity curve is output through the sampling circuit inside the electronic pen 100.

[0073] Furthermore, due to the mechanical properties of the conductive sheet 30, the pressure sensitivity output thereof is highly consistent. Under the same writing pressure, the pressure sensitivity output value of the electronic pen 100 is fixed, thus avoiding the phenomenon in which, when a conductive soft film is used as an electrode, the pressure sensitivity output value of the electronic pen 100 may be offset due to factors such as the force application speed and the duration of pressure due to the nonlinear elastic properties of rubber.

[0074] like Figures 1 to 5 As shown, in some embodiments, the refill assembly 10 includes a refill 11 and a refill clip 12 sleeved onto the end of the refill 11 , and the refill clip 12 is provided with an arc-shaped contact head that contacts the buffer pad 20 .

[0075] In this embodiment, the arc-shaped contact head can lightly press the buffer pad 20 downward and press the conductive sheet 30, so that the deformed portion 31 of the conductive sheet 30 passes through the through hole 41 of the annular gasket 40 and contacts the dielectric layer 50. When the pressure of the refill assembly 10 continues to increase, the edge of the arc-shaped contact head of the refill clip 12 contacts the buffer pad 20 and applies pressure to the conductive sheet 30, thereby squeezing the edge of the deformed portion 31 of the conductive sheet 30 to contact the dielectric layer 50, so that the change in the contact area between the conductive sheet 30 and the dielectric layer 50 can be accurately reflected throughout the process of external pressure change, thereby improving the correlation between the change in the contact area between the conductive sheet 30 and the dielectric layer 50 and the change in external pressure.

[0076] Specifically, the radius of the arc-shaped contact head of the refill clip 12 is preferably 6.3 mm.

[0077] In addition, the embodiments of the present application only focus on the structures in the electronic pen 100 related to the improvement points of the present application, and do not mean that the electronic pen 100 does not have other structures. For example, the electronic pen 100 also includes a pen holder 90 that is mounted on the refill assembly 10, and the pen holder 90 includes an inner seat 91 and an outer seat 92 that are mounted on each other. These structures all fall within the scope of protection of the embodiments of the present application and will not be elaborated one by one here.

[0078] The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A capacitive pressure sensor, characterized in that: The capacitive pressure sensor comprises a variable capacitor and two signal lines connecting the variable capacitor, wherein the variable capacitor comprises a buffer pad (20), a conductive sheet (30), an annular gasket (40) and a dielectric layer (50) stacked in sequence. One side of the buffer pad (20) is arranged to be in contact with the external pressure member (10); The conductive sheet (30) is attached to a side of the buffer pad (20) facing away from the external pressure member (10) and is connected to a signal line (60); The annular gasket (40) is arranged on a side of the conductive sheet (30) facing away from the buffer pad (20), and a through hole (41) for the conductive sheet (30) to deform is formed in the middle of the annular gasket (40); The dielectric layer (50) is arranged on a side of the annular gasket (40) facing away from the conductive sheet (30), and a conductive layer (51) is arranged on a side of the dielectric layer (50) facing away from the annular gasket (40), and the conductive layer (51) is connected to another signal line (70).

2. The capacitive pressure sensor according to claim 1, wherein: The conductive sheet (30) comprises a polyimide substrate and a copper plating layer and a nickel-chromium alloy plating layer arranged on the polyimide substrate.

3. The capacitive pressure sensor according to claim 2, wherein: The through hole (41) forms a deformation space for the conductive sheet (30) in the direction of the dielectric layer (50), and the stroke of the deformation space is set to be consistent with the fatigue resistance deformation limit of the conductive sheet (30).

4. The capacitive pressure sensor according to claim 3, wherein: The travel range of the deformation space is set to 0.02mm-0.05mm.

5. The capacitive pressure sensor according to claim 1, wherein: The conductive sheet (30) is configured to at least cover the through hole (41), and / or the projection of the conductive layer (51) onto the annular gasket (40) is configured to at least cover the through hole (41).

6. The capacitive pressure sensor according to claim 1, wherein: The conductive sheet (30) comprises a deformable portion (31) covering the through hole (41), and a lap portion (32) arranged around the deformable portion (31) and lapped to the annular gasket (40); the deformable portion (31) can be deformed toward the dielectric layer (50) through the through hole (41) under the pressure of the buffer pad (20).

7. The capacitive pressure sensor according to claim 1, wherein: The conductive sheet (30) is provided with a tab (33) located on the periphery of the annular gasket (40), and the one signal line (60) includes a positive signal line connected to the tab (33).

8. The capacitive pressure sensor according to claim 1, wherein: The other signal line (70) includes a negative signal line connected to the conductive layer (51), the negative signal line is provided with a patch connected to the conductive layer (51), and the projection of the patch onto the annular gasket (40) is arranged to at least cover the through hole (41).

9. An electronic pen, characterized in that: The electronic pen (100) comprises a capacitive pressure sensor according to any one of claims 1 to 8, the external pressure member (10) is a core assembly of the electronic pen (100), and both of the signal lines are connected to an electronic control board (80) of the electronic pen (100).

10. The electronic pen according to claim 9, characterized in that: The pen core assembly comprises a pen core (11) and a pen core clip (12) sleeved on the end of the pen core (11); the pen core clip (12) is provided with an arc-shaped contact head that contacts the buffer pad (20).

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