CN108762539A - capacitive pressure detection method - Google Patents

Abstract

A capacitive pressure detection method, used for detecting the pressing force applied on the display screen, setting the first base material and the second base material with electrodes, and bonding the first base material and the second base material face to face Together, a gap is formed between the respective electrodes, and the gap communicates with the air outside the first base material and the second base material; at least one of the first base material and the second base material is used as a pressure bearing surface, and the pressure The bearing surface is attached under the display module of the display screen. The present invention does not need to rely on components in the display screen to form a pressure detection capacitor, and can be applied to most current display screens; the present invention provides physical support for the gap forming the pressure detection capacitor, ensuring that the thickness of the gap is controllable; The cotton medium ensures the capacitance change rate of the pressure detection capacitor and improves the sensitivity of pressure detection.

Description

Capacitive Pressure Sensing Method

technical field

The invention relates to a method for collecting and converting force into an electrical signal, in particular to a method for processing an electrical signal reflecting pressure into pressure data using capacitance as a conversion medium.

Background technique

In the prior art, a display screen capable of detecting pressing force applied thereon based on the capacitance principle includes a display module for image display, pressure detection electrodes, and a backlight module with an iron frame. One implementation is that the pressure detection electrode is bonded to the display module, an air gap is formed between the pressure detection electrode and the backlight module, and the pressure detection capacitor is formed between the pressure detection electrode and the backlight module with the iron frame of the backlight module as the reference plane. . When a pressing force is applied on the display screen, the pressure detection electrode deforms along with the deformation of the pressed display module, and the distance between the pressure detection electrode and the iron frame of the backlight module changes, so that the distance between the two The pressure detection capacitance changes, and the change amount of the pressure detection capacitance is converted into a pressure value of the pressing force through data processing. Another implementation scheme is that the pressure detection electrode is bonded to the backlight module, an air gap is formed between the pressure detection electrode and the display module, and the display module is used as a reference plane, and a pressure detection capacitor is formed between the pressure detection electrode and the display module. . When a pressing force is applied on the display screen, the display module as a reference plane deforms, and the pressure detection capacitance between the two changes due to the change in the distance between the pressure detection electrode and the display module. The data processing converts the change amount of the pressure detection capacitance into the pressure value of the pressing force. There are following defects and deficiencies in the prior art:

1. There needs to be an air gap of sufficient thickness between the display module and the backlight module to ensure that the pressure detection capacitance change that is sufficiently different from the interference signal can be generated when the pressing action occurs, but the air cannot resist the change between the structures and make the air gap The thickness is not easy to control;

2. Not all displays are equipped with backlight modules with iron frames;

When the display module adopts a Thin Film Transistor Liquid CrystalDisplay display module, some applications use a backlight module with a non-metal frame, so that the backlight module with a non-metal frame cannot be used as a reference plane and a pressure detection electrode. Pressure detection capacitance is formed, so pressure detection cannot be realized; thin film transistor liquid crystal display Thin Film Transistor Liquid Crystal Display is referred to as TFT-LCD;

When the display module adopts the active matrix organic light emitting diode Active Matrix Organic Light Emitting Diode display module, there is no need to set the backlight module, and the pressure detection electrode cannot realize pressure detection because the reference plane of the pressure detection capacitor is not formed; the active matrix organic light emitting diode Active Matrix Organic LightEmitting Diode is referred to as AMOLED.

Contents of the invention

The technical problem to be solved by the present invention is to avoid the shortcomings of the prior art and propose a capacitive pressure detection method that can be used for most current display screens.

The present invention solves described technical problem and can realize by adopting following technical scheme:

A capacitive pressure detection method is proposed for detecting a pressing force applied on a display screen, the display screen includes a display module capable of being deformed due to the pressing applied on the display screen; the method includes:

Selecting a first base material and a second base material capable of compressive deformation;

At least one first electrode is arranged on the front of the first substrate; at least one second electrode is arranged on the front of the second substrate;

Lay the first substrate and the second substrate facing each other so that a gap is formed between the surfaces where all the first electrodes are located and the surfaces where all the second electrodes are located, and the gap is connected to the first substrate and the second substrate. The outer air is connected; the distance between the surfaces where all the first electrodes are located and the surfaces where all the second electrodes are located is the thickness of the gap, and the thickness of the gap when the first substrate and the second substrate are not compressed and deformed is the normal thickness;

At least one of the first base material and the second base material is used as a pressure-bearing surface, and the pressure-bearing surface is attached under the display module of the display screen, so that the pressure-bearing surface can be deformed with the deformation of the display screen;

Applying electrical signals to the first electrode and the second electrode respectively, so that a voltage difference is formed between the first electrode and the second electrode, thereby forming a pressure detection capacitance between the first electrode and the second electrode;

When there is a pressing action on the display screen, the pressure bearing surface is deformed, the thickness of the gap changes, and the pressure detection capacitance between the first electrode and the second electrode changes, and the change of the pressure detection capacitance is obtained through data processing. Obtains pressure data for the pressing force on the display.

In order to form the pressure detection mutual capacitance, a driving signal is applied to one group of all the first electrodes and all the second electrodes, and a response signal is collected in the other group, so as to detect the pressure detection mutual capacitance formed between the first electrode and the second electrode. capacitance changes.

To detect the self-capacitance for the first pressure, apply a reference potential to one group of all the first electrodes and all the second electrodes, apply an electrical signal to the other group and detect the change of the electricity on it, so as to detect the first electrode and the second electrode The pressure developed between the electrodes detects the self-capacitance change.

In order to realize a non-closed gap, the method specifically includes:

Fit and close the front edge of the first base material and the front edge of the second base material with an annular glue;

Selecting at least one air flow hole in the first base material and the second base material to process at least one communicating gap, so that the gap communicates with the air outside the first base material and the second base material.

In order to improve the deformation of the pressure-bearing surface, the Young's modulus of the material used to manufacture the first base material is smaller than the Young's modulus of the material used to manufacture the second base material; the first base material is attached as the pressure-bearing surface Below the display module of the display screen.

Another method for improving the deformation of the pressure-bearing surface is that the Young's modulus of the material used to manufacture the second base material is less than the Young's modulus of the material used to manufacture the first base material; the second base material is used as a pressure-bearing The surface is attached under the display module of the display screen.

In order to increase the rate of capacitance change, the method uses a foam medium made of a material with a higher dielectric constant than air to fill the gap.

Specifically, the material with a higher dielectric constant than air is a high-density polyurethane material.

An application scheme, the display module of the display screen is a display module of a thin film transistor liquid crystal display, and the display screen also includes a layer of backlight module arranged under the thin film transistor liquid crystal display module, then the first substrate or the second The second base material is attached under the backlight module as a pressure bearing surface.

In another application scheme, the display module of the display screen is an active matrix organic light emitting diode display module, then the first substrate or the second substrate is attached to the active matrix organic light emitting diode display module as a pressure bearing surface. cathode side.

Compared with the prior art, the technical effect of the "capacitive pressure detection method" of the present invention is:

1. The present invention does not need to rely on the components in the display screen to form a pressure detection capacitor, and the pressure bearing surface can be attached to the deformation device of the display screen to realize pressure detection, which can be applied to most current display screens;

2. The present invention provides physical support for the gap forming the pressure detection capacitor, ensuring that the thickness of the gap is controllable;

3. The present invention ensures the capacitance change rate of the pressure detection capacitor through the base material and the foam medium, and improves the sensitivity of the pressure detection.

Description of drawings

Fig. 1 is a schematic front view of the first embodiment of the "capacitive pressure detection method" of the present invention;

Fig. 2 is a schematic plan view of the orthographic projection of the first embodiment; wherein the first substrate 11 is cut in half;

Fig. 3 is a schematic sectional view of A-A shown in Fig. 2;

Fig. 4 is a schematic cross-sectional view along the direction A-A shown in Fig. 2 when the first embodiment is pressed;

Fig. 5 is a schematic cross-sectional view along the A-A direction shown in Fig. 2 when the first embodiment is used for a TFT-LCD display;

Fig. 6 is a schematic cross-sectional view along the direction A-A shown in Fig. 2 when the first embodiment is used for an AMOLED display;

FIG. 7 is a schematic plan view of the second embodiment of the present invention in an orthographic projection; wherein the first substrate 11 is cut in half.

Detailed ways

Further details will be given below in conjunction with various embodiments shown in the accompanying drawings.

The invention proposes a capacitive pressure detection method for detecting the pressing force applied on the display screen. The pressing force applied on the display screen is different from the touch input to the screen. The pressing force is to exert pressure on the display screen, while the touch input does not need to apply pressure, but only needs to have contact with the display screen. The display screen includes a display module capable of being deformed by pressing on the display screen. As shown in Figures 1 to 7, the capacitive pressure detection method includes the following processes:

Select the first base material 11 and the second base material 12 that can be deformed under pressure;

At least one first electrode 21 is arranged on the front of the first substrate 11; at least one second electrode 22 is arranged on the front of the second substrate 12; the first substrate 11 and the second substrate 12 can be flexibly printed by FPC for short. The circuit board Flexible Printed Circuit can also be made of film; the first electrode 21 and the second electrode 22 can be made of silver-plated materials, or metal-coated copper materials, or Indium Tin Oxide (ITO for short). made of material;

The first base material 11 and the second base material 12 are face-to-face bonded together, so that a gap 5 is formed between the surfaces where all the first electrodes 21 are located and the surfaces where all the second electrodes 22 are located, and the gap 5 is connected to the first base material. Material 11 communicates with the air outside the second base material 12, that is, the gap 5 is a non-closed space; the present invention regards the distance between the surfaces where all the first electrodes 21 are located and the surfaces where all the second electrodes 22 are located as the thickness of the gap 5, Then the thickness of the gap 5 when the first base material and the second base material are not deformed under pressure is the normal thickness; when the surface where the first electrode 21 is located and the surface where the second electrode is located are both plane and parallel to each other, the normal thickness is a definite value; And when the surface where the first electrode 21 is located and the surface where the second electrode is located are not flat, or when the surface where the first electrode 21 is located and the surface where the second electrode is located are not parallel to each other, the normal thickness is a variable that varies according to the relative positions of the two surfaces. That is, the shape of the respective surfaces of the first electrode 21 and the second electrode 22 changes continuously. Therefore, the normal thickness can not only be understood as a fixed quantity, but a functional variable associated with the shapes of the surfaces where the first electrode 21 and the second electrode 22 are located respectively;

At least one of the first base material 11 and the second base material 12 is used as a pressure bearing surface, and the pressure bearing surface is attached under the display module of the display screen, so that the pressure bearing surface can be deformed with the deformation of the display screen. In most cases, one of the first substrate 11 and the second substrate 12 is used as a pressure bearing surface, but in special cases, such as when a capacitive pressure detection component is used for a double-sided screen, the first substrate 11 Both the first base material 11 and the second base material 12 are used as the pressure bearing surface; the first embodiment and the second embodiment of the present invention both use the first base material 11 as the pressure bearing surface;

Applying electrical signals to the first electrode 21 and the second electrode 22 respectively, so that a voltage difference is formed between the first electrode 21 and the second electrode 22, thereby forming a pressure detection capacitance between the first electrode 21 and the second electrode 22;

When there is a pressing action on the display screen, the pressure bearing surface is deformed, and the thickness of the gap 5 changes relative to the normal thickness, and then the pressure detection capacitance between the first electrode 21 and the second electrode 22 will also change, and the pressure will be The pressure data of the pressing force on the display screen is obtained through data processing by detecting the change of capacitance.

In the first embodiment of the present invention, as shown in FIG. 4, when a pressure is applied on the display screen, the first base material 11 deforms as a pressure bearing surface, and the second base material 12 also deforms at the same time. Acting on the first base material 11, the deformation amount of the second base material 12 is smaller than the deformation amount of the first base material 11, and the thickness of the gap 5 changes relative to the normal thickness, as shown in the direction of the arrow in FIG. The air is squeezed and discharged from each air flow hole 4. Normal thickness changes mean that the distance between the first electrode 21 and the second electrode 22 changes, and the pressure detection capacitance formed between them will also change, and the change of the pressure detection capacitance can be converted into pressing force through data processing pressure value. When no pressing is applied on the display screen, the first base material 11 and the second base material 12 return to the normal state, from the state shown in Figure 4 to the state shown in Figure 3, the gap 5 returns to the normal thickness, the first base material 11 and the air outside the second substrate 12 is sucked into the gap 5 .

According to the principle of forming capacitance, the pressure detection capacitance can be self-capacitance or mutual capacitance.

In order to realize self-capacitance for pressure detection, apply a reference potential to one group of all first electrodes 21 and all second electrodes 22, apply an electrical signal to the other group and detect the change of the electric quantity on it, thereby detecting the first electrode 21 and all second electrodes 22. The pressure formed between the second electrodes 22 detects a change in self-capacitance. Applying the electrical signal and detecting the change of the electric quantity can be completed by the data processing module, and the data processing module can also provide a reference potential. In the first embodiment of the present invention, as shown in Figures 1 to 6, three first electrodes 21 and one second electrode 22 are provided, the first electrodes 21 are respectively facing the second electrodes 22, and all the first electrodes 21 are electrically connected to the data The self-capacitance data processing module of the processing module, the self-capacitance data processing module applies an electric signal to the electrically connected electrode and detects the change of the electric quantity on the electrode. All the second electrodes 22 are electrically connected to the reference potential, forming a self-capacitance for pressure detection between the first electrodes 21 and the second electrodes 22 .

In order to realize the pressure detection mutual capacitance, a driving signal is applied to one group of electrodes in all the first electrodes 21 and all the second electrodes 22, and the response signal formed on the other group is collected due to the driving signal, thereby detecting the first electrode The pressure formed between the first electrode 21 and the second electrode 22 detects changes in mutual capacitance. Applying the driving signal and collecting the response signal can be completed by using the data processing module. The data processing module not only detects the change of the mutual capacitance of the pressure detection, but also processes the change of the mutual capacitance of the pressure detection to reflect the pressing force applied on the display screen. pressure data. In the second embodiment of the present invention, as shown in FIG. 7 , three first electrodes 21 and four second electrodes 22 are provided. The first electrodes 21 and the second electrodes 22 are arranged orthogonally to each other, and all the first electrodes 21 are electrically connected. The driving module of the data processing module capable of sending driving signals, all the second electrodes 22 are electrically connected to the sensing module of the data processing module capable of collecting response signals, forming a pressure detection mutual capacitance between the first electrode 21 and the second electrode 22 .

The data processing module may be a data processing module solely used for pressure detection data processing. The data processing module can also use the data processing module of the display screen, which not only completes the data processing of the display screen, but also completes the data processing of the capacitive pressure detection device. That is to say, the data processing module is not limited to a physical or hardware independent module, but can be a functional module in separate hardware for processing pressure detection data, or two or more hardware modules can cooperate to complete pressure detection data processing function modules. Appropriate physical devices or hardware configurations should be used according to the specific application environment.

The first embodiment and the second embodiment of the present invention, as shown in Fig. 1, Fig. 2 and Fig. 7, the method for constructing the non-closed gap 5 specifically adopts the following process:

The front edge of the first base material 11 and the front edge of the second base material 12 are bonded and closed with the annular glue 3;

Select at least one airflow hole 4 connecting the gap 5 in the first substrate 11 and the second substrate 12 , so that the gap 5 communicates with the air outside the first substrate 11 and the second substrate 12 . In the first embodiment and the second embodiment of the present invention, as shown in Fig. 2 and Fig. 7, air flow holes 4 are processed on the second base material 12, which are communication gaps 5, and some air flow holes 4 run through the second base material 12 , some air passage holes 4 penetrate through the second substrate 12 and the second electrode 22 .

The method improves the deformation of the pressure bearing surface by using different materials, specifically:

In the first embodiment of the present invention, the Young's modulus of the material used to manufacture the first substrate 11 is smaller than the Young's modulus of the material used to manufacture the second substrate 12;

The first base material 11 is attached under the display module of the display screen as a pressure bearing surface.

The Young's modulus of the first base material 11 is smaller than the Young's modulus of the second base material 12, so that the first base material 11 as the pressure bearing surface is more easily deformed than the second base material 12, thereby increasing the thickness of the gap 5 The change range increases the capacitance change rate of the pressure detection capacitor and improves the pressure detection sensitivity.

Similarly, another specific method to increase the deformation of the pressure-bearing surface by using different materials is:

Making the Young's modulus of the material used to make the second base material 12 smaller than the Young's modulus of the material used to make the first base material 11;

Attaching the second base material 12 as a pressure bearing surface under the display module of the display screen can also increase the capacitance change rate of the pressure detection capacitor and improve the pressure detection sensitivity.

In the above solution, as well as the first embodiment and the second embodiment, the method can also increase the capacitance change rate through the dielectric medium, specifically:

The gap 5 is filled with a foam medium made of a material with a dielectric constant higher than that of air, so that the capacitance change rate of the pressure detection capacitor can be further improved, and the pressure detection sensitivity can be improved. In addition, filling the gap 5 with a foam medium also helps to improve the flatness of the first base material 11 and the second base material 12 , further improving the pressure detection sensitivity.

The material with a higher dielectric constant than air may be a high-density polyurethane material.

As shown in Figure 5, when the capacitive pressure detection method of the first embodiment of the present invention is used in a TFT-LCD display screen, that is, the display module of the display screen is a display module 61 of a thin film transistor liquid crystal display TFT-LCD, The display screen also includes a layer of backlight module 62 disposed under the display module 61 of the TFT-LCD, so the first substrate 11 of the first embodiment of the present invention is attached under the backlight module 62 as a pressure bearing surface. Obviously, when the second base material 12 is used as a pressure bearing surface, the second base material 12 should be attached under the backlight module 62 . With the capacitive pressure detection method of the present invention, no matter whether the backlight module 62 is provided with a metal frame or not, the capacitive pressure detection method can work normally without being affected by the backlight module 62, and does not need the backlight module 62 to provide a reference for forming a pressure detection capacitance. flat.

As shown in Figure 6, when the capacitive pressure detection method of the first embodiment of the present invention is used in an AMOLED display screen, the display module of the display screen is the display module 71 of the active matrix organic light emitting diode AMOLED, then this The first substrate 11 of the first embodiment of the invention is attached to the cathode surface of the AMOLED display module 71 as a pressure bearing surface. Apparently, when the second substrate 12 is used as the pressure bearing surface, the second substrate 12 should be attached to the cathode surface of the AMOLED display module 71 . By adopting the capacitive pressure detection method of the present invention, the pressure detection capacitor can be formed without the AMOLED display screen providing a reference plane for forming the pressure detection capacitor.

Claims (10)

1. A capacitive pressure detection method for detecting a pressing force applied on a display screen, the display screen comprising a display module capable of deforming due to the pressing applied on the display screen; characterized in that: Selecting a first base material and a second base material capable of compressive deformation; At least one first electrode is arranged on the front of the first substrate; at least one second electrode is arranged on the front of the second substrate; Lay the first substrate and the second substrate facing each other so that a gap is formed between the surfaces where all the first electrodes are located and the surfaces where all the second electrodes are located, and the gap is connected to the first substrate and the second substrate. The outer air is connected; the distance between the surfaces where all the first electrodes are located and the surfaces where all the second electrodes are located is the thickness of the gap, and the thickness of the gap is the normal thickness when the first substrate and the second substrate are not compressed and deformed; At least one of the first base material and the second base material is used as a pressure-bearing surface, and the pressure-bearing surface is attached under the display module of the display screen, so that the pressure-bearing surface can be deformed with the deformation of the display screen; Applying electrical signals to the first electrode and the second electrode respectively, so that a voltage difference is formed between the first electrode and the second electrode, thereby forming a pressure detection capacitance between the first electrode and the second electrode; When there is a pressing action on the display screen, the pressure bearing surface is deformed, the thickness of the gap changes, and the pressure detection capacitance between the first electrode and the second electrode changes, and the change of the pressure detection capacitance is obtained through data processing. Obtains pressure data for the pressing force on the display. 2. The capacitive pressure detection method according to claim 1, characterized in that: A driving signal is applied to one group of all the first electrodes and all the second electrodes, and a response signal is collected in the other group, so as to detect the pressure detection mutual capacitance change formed between the first electrode and the second electrode. 3. The capacitive pressure detection method according to claim 1, characterized in that: Apply a reference potential to one group of all the first electrodes and all the second electrodes, apply an electrical signal to the other group and detect the change of the electric quantity on it, so as to detect the pressure formed between the first electrode and the second electrode. capacitance changes. 4. The capacitive pressure detection method according to claim 1, characterized in that: Fit and close the front edge of the first base material and the front edge of the second base material with an annular glue; Selecting at least one air flow hole in the first base material and the second base material to process at least one communicating gap, so that the gap communicates with the air outside the first base material and the second base material. 5. The capacitive pressure detection method according to claim 1, characterized in that: the Young's modulus of the material used to make the first substrate is less than the Young's modulus of the material used to make the second substrate; The first base material is attached under the display module of the display screen as a pressure bearing surface. 6. The capacitive pressure detection method according to claim 1, characterized in that: the Young's modulus of the material used to make the second substrate is less than the Young's modulus of the material used to make the first substrate; The second base material is attached under the display module of the display screen as a pressure bearing surface. 7. The capacitive pressure detection method according to claim 1, 3 or 4, characterized in that: A foam medium made of a material with a higher dielectric constant than air is filled in the gap. 8. The capacitive pressure detection method according to claim 5, characterized in that: The material with a higher dielectric constant than air is a high-density polyurethane material. 9. The capacitive pressure detection method according to claim 1, characterized in that: The display module of the display screen is a display module of a thin film transistor liquid crystal display, and the display screen also includes a layer of backlight module arranged under the thin film transistor liquid crystal display module, so the first substrate or the second substrate is used as a pressure The bearing surface is attached under the backlight module. 10. The capacitive pressure detection method according to claim 1, characterized in that: The display module of the display screen is an active matrix organic light emitting diode display module, then the first substrate or the second substrate is attached to the cathode surface of the active matrix organic light emitting diode display module as a pressure bearing surface.