CN114420485A - membrane keyboard - Google Patents

Abstract

The present application relates to the technical field of keyboards, and aims to solve the problems of poor key feel or poor corner function of known membrane keyboards, and provides a membrane keyboard, including a support plate, a conductive film, a flexible circuit board and multiple sets of pressing components. The conductive film is provided with a first area and a second area. The conductive film is distributed with contact pairs in the first area, and the contact pairs can be electrically connected to generate key signals at corresponding positions. The pressing component is divided into a first pressing component and a second pressing component. The second pressing assembly includes a second keycap, a sensed member and a second support structure, and the sensed member is disposed on the second keycap. The flexible circuit board is integrated with a capacitance sensing circuit, the capacitance sensing circuit includes a capacitance sensing structure, the capacitance sensing structure corresponds to the sensed part, and when the second keycap is pressed, a key position signal corresponding to the position is generated through capacitance detection. The beneficial effect of the present application is that the problem of poor function of the button corner can be solved at low cost.

Description

membrane keyboard

technical field

The present application relates to the technical field of keyboards, and in particular, to membrane keyboards.

Background technique

Membrane keyboards have become the most popular keyboards due to their advantages of lightness, thinness, low price, and low noise. They can be used with personal desktop computers or integrated in notebook computers as the keyboard part of notebook computers.

However, known membrane keyboards still suffer from poor key feel or poor corner function.

SUMMARY OF THE INVENTION

The embodiments of the present application provide a membrane keyboard to solve the problems of poor key feel or poor corner function of the known membrane keyboard.

Embodiments of the present application provide a membrane keyboard, which includes a support plate, a conductive membrane, a flexible circuit board, and multiple sets of pressing components. The support plate has opposing first and second surfaces. The conductive film is stacked on one side of the first surface of the support plate; the conductive film is provided with a first area and a second area, and the conductive film is distributed with contact pairs in the first area, and the contact pairs can be connected by piezoelectricity to generate corresponding position key signal. The flexible circuit board is arranged on one side of the second surface of the support plate and extends to at least a part corresponding to the second area. Some of the multiple sets of pressing components are first pressing components and some are second pressing components. The first pressing component includes a first keycap and a first support structure, the first keycap is compressibly supported on the support plate by the first support structure and corresponds to the contact pair, and the first keycap can be pressed to make the contact The point pair is turned on, and the key position signal of the corresponding position is generated. The second pressing assembly includes a second keycap, a sensed member and a second support structure, the second keycap is supported on the support plate by the second support structure, and the sensed member is disposed on the second keycap. The flexible circuit board is integrated with a capacitive sensing circuit, and the capacitive sensing circuit includes a capacitive sensing structure. The capacitive sensing structure corresponds to the second area and corresponds to the sensing element in the pressing direction along the second keycap, and when the second keycap is pressed, The capacitance sensing circuit can sense the change of the capacitance value between the capacitance sensing structure and the sensed part, and when the capacitance value reaches the capacitance conduction threshold of the capacitance sensing circuit, a key position signal at the corresponding position is generated.

Part of the pressing component (the second pressing component) of the membrane keyboard in the embodiment of the present application is provided by the flexible circuit board and the capacitive sensing circuit on it, and the sensing member and the corresponding capacitive sensing structure provided on the second keycap when pressing the button. The change in capacitance value between the two can realize the non-contact triggering of the key position signal, especially suitable for long keys (such as space bar, etc.) that are prone to poor corner functions. It can be realized at low cost while maintaining the key stroke and the overall thickness of the keyboard , to solve the problem of poor corner function, improve the reliability of keys, and have broad application prospects.

In a possible implementation manner, the sensed part is made of conductive silicone or conductive foam.

In this implementation, the sensed piece is made of conductive silica gel or conductive foam, and when it approaches or moves away from the capacitance sensing structure, the capacitance value between the sensed piece and the capacitance sensing structure changes gradually, which can be processed to obtain the key position signal.

In a possible implementation manner, the sensing member is in the shape of a sheet or a strip, and the sensing member is bonded or clamped to the surface of the second keycap on the side facing the conductive film.

In this implementation manner, the sheet-shaped or strip-shaped sensing element is connected to the side of the second keycap facing the conductive film by means of bonding or clamping, which is convenient for connection.

In a possible implementation manner, the capacitive sensing structure includes a chevron-shaped first line and a U-shaped second line, the first line and the second line are spaced apart from each other, and the first line is electrically connected to the system-side capacitive signal processing unit. VCC+ interface, the second line is electrically connected to the GND interface of the capacitive signal processing unit at the system side, so that an electric field is formed between the first line and the second line. Capacitance between the sensed element and the capacitive sensing structure.

In the capacitive sensing structure in this implementation manner, the first lines of the three branches and the second lines of the two branches are arranged at intervals to form multiple sets of spaced capacitance structures, which can be sensitively adjusted according to the position change of the sensed part. By changing the capacitance value, the key position signal can be given sensitively according to the displacement of the second key cap.

In a possible implementation manner, the support plate is a metal plate, and the support plate is provided with a through hole corresponding to the sensed part.

In this implementation, the support plate is a metal plate, and only through holes are opened at the corresponding parts to be sensed. On the one hand, the metal plate can shield the displacement of the metal parts that may exist in other positions of the membrane keyboard from interfering with the sensing of the capacitive sensing structure. In one aspect, the opened through holes can prevent the support plate from affecting the sensing of the sensing element by the capacitive sensing structure, thereby ensuring that the capacitive sensing structure can accurately sense the displacement of the sensing element.

In a possible implementation manner, the second pressing component includes a space bar pressing component, and the space bar pressing component includes a space bar cap, two scissor support structures, and an elastic support member, and the two scissor support structures are respectively supported on the space bar cap. At both ends in the lengthwise direction, the elastic support member is supported at the middle position in the lengthwise direction of the space bar cap, and the elastic support member and the two scissor support structures together constitute the second support structure of the space bar pressing assembly. There are two sensed parts of the space bar pressing assembly, and the two sensed parts are respectively located between the elastic support part and the two scissor support structures. The flexible circuit board includes a first board section, the first board section extends parallel to the long direction of the space bar and corresponds to the space bar cap, and the first board section is provided with capacitive sensing structures corresponding to the two sensed parts respectively.

In this implementation mode, the space bar is used as a long key, and it is more difficult to improve its corner function by using the existing technology (for example, it needs to be realized by increasing the wall thickness of the space bar cap, improving the structural rigidity of the support plate, etc.), and in the implementation mode, The scissor supports on both sides and the elastic support in the middle are used as supports, which improves the feel of the keys to a certain extent. In addition, by setting the sensed parts and the corresponding capacitive sensing structures on both sides of the elastic support, there is no need to press the space bar in place. The contacts are in contact with each other, and the desired key-press effect can be achieved only by properly setting the capacitance conduction threshold. In addition, during the key press process, the elastic support member can provide elastic support, and the key feel can be set to be consistent with the conventional keys. Moreover, structurally, only the first board segment corresponding to the space bar needs to be additionally provided on the surface of the flexible circuit board, so that the corner function of the space bar can be better solved, and the increased cost is small.

In a possible implementation manner, the membrane keyboard includes a backlight module, and the backlight module includes a backlight plate and a light source assembly. The backlight board is arranged on the second surface side of the support board, the light source assembly includes a light source circuit integrated in the flexible circuit board, and the light source circuit includes an LED lamp capable of energizing and emitting light; the flexible circuit board is located on the side of the backlight board away from the support board.

In this implementation manner, the light source component of the backlight module and the aforementioned capacitive sensing circuit are integrated on the flexible circuit board on the back of the backlight board, which improves the utilization efficiency of the flexible circuit board. In other words, for a backlight module originally provided with a flexible circuit board for integrating light source components, the capacitive sensing circuit used by some of the pressing components (the second pressing component) is integrated into the flexible circuit board to realize the capacitive sensing button function. The cost increase to the membrane keyboard is small.

In a possible implementation manner, the flexible circuit board includes a second board segment, the second board segment is connected to one end of the first board segment, and forms an L-shaped flexible circuit board with the first board segment. There are a plurality of LED lights, and the plurality of LED lights are arranged at intervals along the width of the space bar cap.

In this implementation manner, the flexible circuit board integrates the light source circuit and the capacitance sensing circuit at the same time, and the utilization rate of the flexible circuit board is high.

In a possible implementation manner, the light source circuit further includes a plurality of resistors, and the LED lights and the resistors are connected in series to the power supply of the light source circuit in parallel.

In this implementation, the resistor and the LED board are integrated into the flexible circuit board, the structure is simple, the size is small, and the cost of providing the light source is low.

In a possible implementation manner, the second pressing component is used for each key of the membrane keyboard whose length is greater than the width.

In this implementation, the second pressing component is used for the keys with long length, and the key is triggered by the capacitive sensing method, which can solve the problem that the corners of these keys have poor function and affect the feel at a low cost.

In a possible implementation manner, the flexible circuit board includes a fourth board part, a fifth board part and a sixth board part. The fourth plate portion corresponds to the column where the left shift key of the membrane keyboard is located, the fifth plate portion corresponds to the column where the right shift key of the membrane keyboard is located, the sixth plate portion corresponds to the row where the space bar of the membrane keyboard is located, and the fourth plate portion, The sixth plate part and the fifth plate part are connected in sequence.

In this implementation, by covering the fourth board portion, the fifth board portion, and the sixth board portion of the column where the left shift key is located, the column where the right shift key is located, and the row where the space bar is located, the area of the flexible circuit board is small, and the performance is better. It covers the common long keys of membrane keyboards.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present application more clearly, the accompanying drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be viewed as This is to limit the scope. For those of ordinary skill in the art, other related drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a membrane keyboard according to an embodiment of the application;

2 is a three-dimensional view of a key assembly of the membrane keyboard in FIG. 1;

Fig. 3 is another perspective view of the key assembly of Fig. 2;

4 is an expanded view of the key assembly of FIG. 2;

5 shows a schematic diagram of the cooperation relationship between the space bar pressing assembly and the conductive film, the support plate, the flexible circuit board, and the backlight module;

A plan view of the conductive film is shown in FIG. 6;

A plan view of the support plate is shown in Figure 7;

Figure 8 shows the layout of the capacitive sensing circuit and the light source circuit on the flexible circuit board;

Fig. 9 is the enlarged view of A place of Fig. 8;

FIG. 10 is a schematic diagram of the capacitive sensing circuit and the light source circuit on the flexible circuit board;

11 is a three-dimensional view of a key assembly of a membrane keyboard according to another embodiment of the application;

FIG. 12 is a plan view of the back surface of FIG. 11 .

Description of main component symbols:

membrane keyboard 10

Housing 11

trackpad 12

Button assembly 20,20a

Support plate 21

Conductive film 22

Flexible circuit board 23

Press assembly 24

The first pressing component 24a

The second pressing member 24b

Spacebar Press Assembly 24c

Backlight Module 25

Backlight 26

Light source assembly 27

first keycap 28

first support structure 29

Second keycap 30

Second Support Structure 31

Sensitive parts 32

scissor support structure 33

elastic support 34

Capacitive Sensing Circuits 35

Capacitive Sensing Architecture 36

first plate segment 37

Second plate section 38

Light source circuit 39

LED light 40

Resistor 41

Goldfinger 42

first line 43

Second line 44

System side capacitive signal processing unit 45

Tab key 46a

caps lock key 46b

Left shift key 46c

Left CTRL key 46d

space bar 46e

Backspace 46f

Enter key 46g

right shift key 46h

Right CTRL key 46i

Fourth Board Section 47

Fifth Board Section 48

Sixth Board Section 49

Keyhole K1

Avoidance hole K2

Through hole K3

Combined electric field M1

first surface P1

second surface P2

Internal space Q1

The first area S1

Second area S2

Pressing direction Y1

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments.

It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly disposed on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and similar expressions are used herein for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art of this application. The terms used herein in the specification of the present application are for the purpose of describing particular embodiments only, and are not intended to limit the present application. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Some embodiments of the present application are described in detail. The following embodiments and features of the embodiments may be combined with each other without conflict.

Example

This embodiment provides a membrane keyboard 10, which can be an independent keyboard or a keyboard attached to a whole machine such as a notebook computer.

Referring to FIG. 1 , the membrane keyboard 10 in this embodiment includes a casing 11 and a key assembly 20 mounted on the casing 11 . The user can input information by pressing the keys of the key assembly 20 . The number and arrangement of the keys of the key assembly 20 can be arranged in the form of 79 keys, 83 keys, 87 keys, 93 keys, 96 keys, 101 keys, 102 keys, 104 keys, and 107 keys of common keyboards. The keys of the membrane keyboard 10 in this embodiment include several common keys with substantially equal lengths and widths and several long keys whose lengths are longer than their widths. A typical long key press mainly consists of the space bar.

In some implementation manners, the membrane keyboard 10 in this embodiment further includes a touchpad 12 for replacing a common mouse. The touch panel 12 is a conventional structure, and details are not described here. In other embodiments, the touch panel 12 may not be provided.

In this embodiment, the housing 11 encloses an internal space Q1 , and the housing 11 is provided with key holes K1 corresponding to the number of keys, and each key hole K1 is respectively connected to the internal space Q1 of the housing 11 for exposing the key assembly 20 .

Referring to FIG. 2 to FIG. 4 , the key assembly 20 provided in the embodiment of the present application includes a support plate 21 , a conductive film 22 , a flexible circuit board 23 and multiple sets of pressing assemblies 24 . In some embodiments, the key assembly 20 is further provided with a backlight module 25 , and the backlight module 25 includes a backlight plate 26 and a light source assembly 27 .

Referring to FIG. 4 and FIG. 5 , the support plate 21 has a first surface P1 and a second surface P2 opposite to each other, the conductive film 22 is stacked on the side of the first surface P1 of the support plate 21 , and the flexible circuit board 23 is arranged on the support plate. 21 on the side of the second surface P2. Each set of pressing components 24 is arranged on the side of the first surface P1 of the support plate 21 .

For the embodiment in which the backlight module 25 is provided, the backlight board 26 may be provided between the support board 21 and the flexible circuit board 23 , and the light source assembly 27 is integrated on the flexible circuit board 23 . The light source provided by the light source assembly 27 is passed through the backlight panel 26 to provide backlight. By integrating the light source assembly 27 of the backlight module 25 on the flexible circuit board 23, the backlight effect can be achieved with a smaller structural design, the structure arrangement is reasonable, and the cost is low, which is beneficial to market promotion.

In this embodiment, optionally, the backlight plate 26 , the support plate 21 , and the conductive film 22 are generally rectangular plate-like structures, and the three are stacked in sequence from bottom to top and connected to the bottom surface of the inner space Q1 of the housing 11 . , each group of pressing components 24 are respectively connected to the support plate 21 or the conductive film 22, and are respectively exposed from the corresponding key holes K1 on the casing 11, so as to facilitate the user's key operation.

In this embodiment, the flexible circuit board 23 only needs to cover part of the position (described in detail later), and the size of the board surface can be set to be much smaller than the size of the board surface of the backlight board 26/supporting board 21/conductive film 22, so as to have Smaller structural cost. In addition, in order to accommodate the flexible circuit board 23 in thickness, a groove (not shown in the figure) for accommodating the flexible circuit board 23 can be concavely formed in the position of the casing 11 or the backlight plate 26 corresponding to the flexible circuit board 23 . , so as to prevent the flexible circuit board 23 from increasing the overall thickness of the membrane keyboard 10 . Since the size of the surface of the flexible circuit board 23 can be set to be smaller, the setting of the groove has little effect on the overall structural performance of the membrane keyboard 10 .

Referring to FIG. 5 and FIG. 6 , in some embodiments, an escape hole K2 needs to be opened on the conductive film 22 to allow the pressing component 24 to pass through and be connected to the support plate 21 . Due to the limited space on the board surface of the conductive film 22, the arrangement of the avoidance hole K2 may easily affect the arrangement of the conductive circuit thereon. In addition, the position of the avoidance hole K2 needs to have high accuracy, so as to avoid the interference between the pressing component 24 and the conductive film 22 during assembling and affect the connection with the support plate 21 . Especially for keys with the same length as the space bar (referring to keys whose keycaps are longer than the width), in order to improve the corner function, more or more complex supporting structures need to be set up, so that the conductive film 22 has correspondingly more avoidance holes K2, which further increases the number of escape holes K2. This increases the difficulty of the shape and circuit design of the conductive film 22 and increases the difficulty of assembly.

In this embodiment, the conductive film 22 is provided with a first area S1 and a second area S2, and the conductive film 22 is distributed with a plurality of contact pairs (not shown in the figure) in the first area S1, corresponding to the contacts in the first area S1. A plurality of pressing assemblies 24 . The contact pair can be electrically connected to generate a key signal corresponding to the position. The specific arrangement of the contact pairs of the conductive film 22 in the first region S1 and the corresponding conductive lines can be arranged as required, which will not be repeated here. In general, each contact pair corresponds to a pressing component 24, and when the pressing component 24 is pressed, the two contacts of the contact pair can be brought into contact and conduction, thereby generating a corresponding key signal. In this embodiment, the flexible circuit board 23 extends to at least partially correspond to the second area S2.

Some of the multiple sets of pressing components 24 are the first pressing components 24a and some are the second pressing components 24b. In an implementation of this embodiment, the pressing component 24 of the space bar adopts the second pressing component 24b, and the pressing component 24 of other keys adopts the first pressing component 24a.

Referring to FIG. 4 again, in this embodiment, the first pressing component 24a includes a first key cap 28 and a first support structure 29, and the first key cap 28 is compressibly supported on the support plate 21 by the first support structure 29 and corresponds to the contact point pair, and the first key cap 28 can be pressed to make the contact pair conductive, and generate a key position signal at the corresponding position. In order to avoid the first support structure 29 , corresponding holes are formed on the conductive film 22 .

Referring to FIG. 4 and FIG. 5 , in this embodiment, the second pressing component 24b is the space bar pressing component 24c, and the space bar pressing component 24c includes the second key cap 30 (ie the space bar key cap), the sensed member 32 and the first key cap 30 . Two supporting structures 31 , the second keycap 30 is supported on the support plate 21 by the second supporting structure 31 , and the sensing element 32 is disposed on the second keycap 30 . Wherein, in order to improve the key feel of the second pressing component 24b, the second support structure 31 includes two scissor support structures 33 and an elastic support 34, and the two scissor support structures 33 are respectively supported on the long ends of the space bar cap, elastic The support member 34 is supported at the longitudinal middle position of the space bar cap. The elastic support 34 in this embodiment may be a rubber dome on the known membrane keyboard 10 , which can provide a certain elastic support, which is beneficial to the depression and rebound of the second keycap 30 . The rubber elastic member can be supported on the surface of the conductive film 22 or the support plate 21 .

In this embodiment, the sensing member 32 is formed of conductive silica gel, conductive foam, metal sheet or other conductive structures. Optionally, the sensing member 32 is in the shape of a sheet or a strip, and the sensing member 32 is bonded or clamped to the surface of the second keycap 30 on the side facing the conductive film 22 . In some embodiments, the sensing member 32 may also be integrally formed with the second keycap 30 .

In this embodiment, there are two sensed parts 32 of the space bar pressing assembly 24c, and the two sensed parts 32 are respectively located between the elastic support part 34 and the two scissor support structures 33 and are symmetrically arranged.

Referring to FIG. 8 , FIG. 9 and FIG. 10 , the flexible circuit board 23 is integrated with a capacitive sensing circuit 35 , and the capacitive sensing circuit 35 includes a capacitive sensing structure 36 . The capacitive sensing structure 36 corresponds to the second area S2 and is adjacent to the sensed member 32 . The pressing direction Y1 (see FIG. 5 ) of the second key cap 30 corresponds to, and when the second key cap 30 is pressed, the capacitance sensing circuit 35 can sense the capacitance value change between the capacitance sensing structure 36 and the sensed member 32 , and when the second key cap 30 is pressed When the capacitance value reaches the capacitance conduction threshold of the capacitance sensing circuit 35, a key signal corresponding to the position is generated.

In this embodiment, the flexible circuit board 23 includes a first board segment 37 and a second board segment 38, and the first board segment 37 and the second board segment 38 are connected to form an L-shape.

The first plate segment 37 extends parallel to the long direction of the space bar and corresponds to the space bar cap. The first plate segment 37 is provided with capacitive sensing structures 36 corresponding to the two sensed members 32 respectively. For the membrane keyboard 10 provided with the aforementioned backlight module 25, the light source assembly 27 includes a light source circuit 39 integrated in the flexible circuit board 23, the light source circuit 39 includes an LED lamp 40 capable of energizing and emitting light, and the flexible circuit board 23 is located at a distance from the backlight board 26. support plate 21 side. The second board section 38 is connected to one end of the first board section 37 and forms an L-shaped flexible circuit board 23 with the first board section 37 . There are multiple LED lights 40 , and the multiple LED lights 40 are arranged at intervals along the width of the space bar cap. Optionally, the light source circuit 39 further includes a plurality of resistors 41 , and the LED lamps 40 and the resistors 41 are connected in series to the power supply of the light source circuit 39 in parallel. The flexible circuit board can be connected to the host through the gold fingers 42, or can be connected through other connection methods.

In this embodiment, the light source circuit 39 of the backlight module 25 and the aforementioned capacitance sensing circuit 35 are integrated on the flexible circuit board 23 on the back of the backlight board 26 , which improves the utilization rate of the flexible circuit board 23 . In other words, for the backlight module 25 originally provided with the flexible circuit board 23 for integrating the light source assembly 27 used in some of the applicant's technologies, the capacitive sensing circuit 35 used in part of the pressing member 24 (the second pressing member 24b) is integrated. The flexible circuit board 23 realizes the function of capacitive sensing keys, and the cost of the membrane keyboard 10 increases little.

The partial pressing component 24 (the second pressing component 24b) of the membrane keyboard 10 in the embodiment of the present application is provided with the flexible circuit board 23 and the capacitive sensing circuit 35 thereon, and is arranged on the second keycap 30 when the key is pressed. The change of the capacitance value between the component 32 and the corresponding capacitance sensing structure 36 realizes the non-contact triggering of the key position signal, especially suitable for long keys (such as the space bar, etc.) that are prone to poor corner functions, and can be realized at low cost while maintaining the key Under the premise of the stroke and the overall thickness of the keyboard, it can solve the problem of poor corner function, improve the reliability of the keys, and has wide application prospects. Especially for the space bar and other long keys, it is more difficult to improve the corner function by using the existing technology (if it needs to be realized by increasing the wall thickness of the space bar cap, improving the structural rigidity of the support plate 21, etc.), and in this embodiment, through two The scissor support structure 33 on the side and the elastic support member 34 in the middle are used as supports, which improves the feel of the keys to a certain extent. In addition, by using the sensing member 32 and the corresponding capacitive sensing structure 36 on both sides of the elastic support member 34, no space is required. The key is pressed in place to make the contact pair contact, and the desired key effect can be achieved only by properly setting the capacitance conduction threshold. In addition, during the key press process, the elastic support member 34 can provide elastic support, and the key feel can be set to be consistent with the conventional keys. At the same time, structurally, only the first board section 37 corresponding to the space bar is additionally provided on the surface of the flexible circuit board 23, so that the corner function of the space bar can be better solved, and the increased cost is small.

Referring again to FIGS. 9 and 10 , in an optional embodiment, the capacitive sensing structure 36 includes a chevron-shaped first line 43 and a U-shaped second line 44 , and the first line 43 and the second line 44 are spaced apart from each other , the first line 43 is electrically connected to the VCC+ interface (power supply interface) of the system-side capacitance signal processing unit 45, and the second line 44 is electrically connected to the GND interface (ground interface) of the system-side capacitance signal processing unit 45, so that the first line An electric field is formed between 43 and the second line 44 . When the sensing element 32 approaches or moves away from the capacitive sensing structure 36 , the electric field will be cut, thereby changing the capacitance between the sensing element 32 and the capacitive sensing structure 36 . The capacitive sensing structure 36 in this implementation manner is formed by intersecting the first lines 43 of the three branches and the second lines 44 of the two branches at intervals to form multiple groups of spaced capacitive structures, which can sensitively respond to the sensing element 32 The capacitance value changes due to the change of the position of the second keycap 30, and then the key position signal can be given sensitively according to the displacement of the second keycap 30. At the same time, when the capacitance sensing circuit of this structure is connected to the alternating current, it can generate the signal shown in FIG. 5 . The combined electric field M1 of the two electric field lines is roughly arched, so that even if there is a certain deviation in the lateral (long or wide) setting position of the space bar, the sensed member 32 can still reliably sense the movement of the sensed member 32 when the key is pressed. displacement.

Referring to FIG. 4 , FIG. 5 or FIG. 7 , in a possible implementation manner, the support plate 21 is a metal plate, and the support plate 21 is provided with a through hole K3 corresponding to the sensed member 32 . In this implementation, the support plate 21 is a metal plate, and the through hole K3 is only opened at the position corresponding to the sensed part 32 . On the one hand, the metal plate can shield the displacement of the metal parts that may exist in other positions of the membrane keyboard 10 from interfering with the capacitive sensing structure 36 . On the other hand, the opening of the through hole K3 can prevent the support plate 21 from affecting the sensing of the sensing member 32 by the capacitive sensing structure 36 , thereby ensuring that the capacitive sensing structure 36 can accurately sense the displacement of the sensing member 32 .

In some embodiments, no contact pair is provided in the second area S2, and other methods are used to generate the key signal (the details will be described in detail below). Since the second area S2 does not need to set the contact pair to generate the key position signal, the design of the avoidance hole K2 on the second area S2 is not affected by the contact pair or its circuit, and can be reasonably set according to the needs, so as to maximize the button feel of the pressing component 24 . In other implementations, the second area S2 of the conductive film 22 can be partially or completely cut off as required, so that the corresponding pressing component 24 can be directly connected to the support plate 21 without being blocked by the conductive film 22 .

The contact pair and the corresponding circuit can also be reserved in the second area S2, so that the key position signal can be obtained through one of the contact pair contact and the capacitance value detection, which further improves the reliability of the key.

Referring to FIG. 11 and FIG. 12 , in another implementation of this embodiment, the second pressing component 24 b of the key assembly 20 a is used for each key of the membrane keyboard 10 whose length is greater than the width, including the Tab on the left side of the membrane keyboard 10 key 46a, caps lock key 46b, left shift key 46c and left CTRL key 46d, space bar 46e on the lower row of membrane keyboard 10, return key 46f on the right side of membrane keyboard 10, enter key 46g, right shift key 46h and right CTRL key 46i etc. With this embodiment, the flexible circuit board 23 includes a fourth board portion 47 , a fifth board portion 48 and a sixth board portion 49 . The fourth plate portion 47 corresponds to the column where the left shift key 46c of the membrane keyboard 10 is located, the fifth plate portion 48 corresponds to the column where the right shift key 46h of the membrane keyboard 10 is located, and the sixth plate portion 49 corresponds to the space bar 46e of the membrane keyboard 10 In the same row, the fourth plate portion 47 , the sixth plate portion 49 , and the fifth plate portion 48 are connected in sequence. In this implementation, by covering the fourth board portion 47 , the fifth board portion 48 and the sixth board portion 49 of the column where the left shift key 46c is located, the column where the right shift key 46h is located, and the row where the space bar 46e is located, the area of the flexible circuit board 23 is reduced. It is smaller and can better cover the common long keys of the membrane keyboard 10 .

The above embodiments are only used to illustrate the technical solutions of the present application rather than limitations. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced. Neither should depart from the spirit and scope of the technical solutions of the present application.

Claims (11)

1. a membrane keyboard, is characterized in that, comprises: a support plate having opposing first and second surfaces; A conductive film, the conductive film is stacked on one side of the first surface of the support plate; the conductive film is provided with a first area and a second area, and the conductive film is distributed with contact pairs in the first area , the contact pair can be piezoelectrically conductive to generate a key signal at the corresponding position; a flexible circuit board, the flexible circuit board is disposed on one side of the second surface of the support plate and extends to at least partially correspond to the second area; A plurality of sets of pressing components, some of the plurality of sets of the pressing components are the first pressing components and some are the second pressing components; Wherein, the first pressing component includes a first key cap and a first support structure, the first key cap is compressibly supported on the support plate by the first support structure and corresponds to the contact pair, and The first key cap can be pressed to make the contact pair conduct, and generate a key signal at a corresponding position; The second pressing component includes a second keycap, a sensed part and a second support structure, the second keycap is supported on the support plate by the second support structure, and the sensed part is disposed on the the second keycap; The flexible circuit board is integrated with a capacitive sensing circuit, and the capacitive sensing circuit includes a capacitive sensing structure, and the capacitive sensing structure corresponds to the second area and is pressed along the second keycap by the sensed member. When the second keycap is pressed, the capacitance sensing circuit can sense the capacitance value change between the capacitance sensing structure and the sensed element, and when the capacitance value reaches the capacitance sensing circuit When the capacitance is turned on threshold, the key signal of the corresponding position is generated. 2. membrane keyboard according to claim 1 is characterized in that: The sensed part is made of conductive silica gel or conductive foam. 3. membrane keyboard according to claim 1 is characterized in that: The sensed member is in the shape of a sheet or a strip, and the sensed member is adhered or clamped to the surface of the second keycap facing the conductive film. 4. The membrane keyboard according to claim 1, wherein: The capacitance sensing structure includes a chevron-shaped first line and a U-shaped second line, the first line and the second line are spaced apart from each other, and the first line is electrically connected to the VCC+ of the system-side capacitance signal processing unit an interface, the second line is electrically connected to the GND interface of the system-side capacitive signal processing unit, so that an electric field is formed between the first line and the second line, and the sensed part is close to or far away from the When capacitively sensing the structure, the electric field will be cut, thereby changing the capacitance between the sensing object and the capacitive sensing structure. 5. The membrane keyboard according to any one of claims 1-4, wherein: The support plate is a metal plate, and the support plate is provided with a through hole corresponding to the sensed part. 6. The membrane keyboard according to any one of claims 1-5, wherein: The second pressing assembly includes a space bar pressing assembly, and the space bar pressing assembly includes a space bar cap, two scissor support structures and an elastic support, and the two scissor support structures are respectively supported on the length of the space bar cap. Towards both ends, the elastic support member is supported at the long middle position of the space bar cap, and the elastic support member and the two scissor support structures together constitute the second support structure of the space bar pressing assembly; There are two sensed parts of the space bar pressing assembly, and the two sensed parts are respectively located between the elastic support part and the two scissor support structures; The flexible circuit board includes a first board section, the first board section extends parallel to the long direction of the space bar and corresponds to the space bar cap, and the first board section is provided with two Capacitance sensing structures corresponding to the sensed parts respectively. 7. The membrane keyboard according to claim 6, wherein: The membrane keyboard includes a backlight module, and the backlight module includes a backlight plate and a light source assembly; The backlight board is arranged on one side of the second surface of the support board, the light source assembly includes a light source circuit integrated in the flexible circuit board, and the light source circuit includes an LED lamp capable of energizing and emitting light; the flexible circuit board on the side of the backlight panel away from the support panel. 8. The membrane keyboard according to claim 7, wherein: The flexible circuit board includes a second board segment, the second board segment is connected to one end of the first board segment, and forms an L-shaped flexible circuit board with the first board segment; There are a plurality of the LED lights, and the plurality of the LED lights are arranged at intervals along the width direction of the space bar cap. 9. The membrane keyboard according to claim 8, wherein: The light source circuit further includes a plurality of resistors, and the LED lamps and the resistors are connected in series to the power supply of the light source circuit in parallel. 10. The membrane keyboard according to claim 1, wherein: The second pressing component is used for each key of the membrane keyboard whose length is greater than the width. 11. The membrane keyboard according to claim 10, wherein: the flexible circuit board includes a fourth board part, a fifth board part and a sixth board part; The fourth plate portion corresponds to the column where the left shift key of the membrane keyboard is located, the fifth plate portion corresponds to the column where the right shift key of the membrane keyboard is located, and the sixth plate portion corresponds to the row where the space bar of the membrane keyboard is located, And the fourth plate portion, the sixth plate portion, and the fifth plate portion are connected in sequence.

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