CN114420485B

CN114420485B - Film keyboard

Info

Publication number: CN114420485B
Application number: CN202210049424.1A
Authority: CN
Inventors: 李海涛; 雷平平; 许慧杰
Original assignee: Honor Device Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2022-01-17
Filing date: 2022-01-17
Publication date: 2023-08-22
Anticipated expiration: 2042-01-17
Also published as: WO2023134384A1; CN114420485A

Abstract

The application relates to the technical field of keyboards, and aims to solve the problems of poor key handfeel or poor corner functions of a known film keyboard. The conductive film is provided with a first area and a second area, contact pairs are distributed in the first area, and the contact pairs can be electrically conducted under pressure to generate key signals at corresponding positions. The pressing assembly is divided into a first pressing assembly and a second pressing assembly. The second pressing component comprises a second keycap, a sensed piece and a second supporting structure, wherein the sensed piece is arranged on the second keycap. The flexible circuit board is integrated with a capacitance sensing circuit, the capacitance sensing circuit comprises a capacitance sensing structure, the capacitance sensing structure corresponds to the sensed piece, and when the second keycap is pressed, a key position signal at a corresponding position is generated through capacitance detection. The application has the beneficial effect of solving the problem of poor functions of the corners of the keys with low cost.

Description

Film keyboard

Technical Field

The application relates to the technical field of keyboards, in particular to a thin film keyboard.

Background

The thin film keyboard is a keyboard which is more sold due to the advantages of light weight, low price, low noise and the like, can be matched with a personal desktop computer to be used, and can be integrally arranged on a notebook computer to be used as a keyboard part of the notebook computer.

However, the known thin film keyboard still has the problems of poor key touch or corner function.

Disclosure of Invention

The embodiment of the application provides a thin film keyboard to solve the problems of poor key hand feeling or poor corner function of the conventional thin film keyboard.

The embodiment of the application provides a film keyboard which comprises a supporting plate, a conductive film, a flexible circuit board and a plurality of groups of pressing components. The support plate has first and second opposite surfaces. The conductive film is overlapped on one side of the first surface of the supporting plate; the conductive film is provided with a first area and a second area, contact pairs are distributed in the first area, and the contact pairs can be electrically conducted under pressure to generate key signals at corresponding positions. The flexible circuit board is arranged on one side of the second surface of the supporting plate and extends to at least partially correspond to the second area. The parts of the pressing assemblies are the first pressing assemblies and the second pressing assemblies. The first pressing component comprises a first keycap and a first supporting structure, the first keycap is compressibly supported on the supporting plate by the first supporting structure and corresponds to the contact pairs, and the first keycap can be pressed to enable the contact pairs to be conducted and generate key position signals of corresponding positions. The second pressing assembly comprises a second keycap, a sensed piece and a second supporting structure, wherein the second keycap is supported by the second supporting structure on the supporting plate, and the sensed piece is arranged on the second keycap. The flexible circuit board is integrated with a capacitance sensing circuit, the capacitance sensing circuit comprises a capacitance sensing structure, the capacitance sensing structure corresponds to the second area and corresponds to the sensed piece in the pressing direction along the second key cap, when the second key cap is pressed, the capacitance sensing circuit can sense the capacitance value change between the capacitance sensing structure and the sensed piece, and when the capacitance value reaches the capacitance conduction threshold value of the capacitance sensing circuit, a key position signal at a corresponding position is generated.

The part of the pressing component (the second pressing component) of the thin film keyboard in the embodiment of the application realizes non-contact triggering of key position signals through the flexible circuit board and the capacitance sensing circuit arranged on the flexible circuit board and through the capacitance value change between the sensed piece of the second key cap and the corresponding capacitance sensing structure when the key is pressed, is particularly suitable for long keys (such as space keys and the like) with easily bad corner functions, can solve the problem of bad corner functions on the premise of keeping the stroke of the key and the whole thickness of the keyboard with low cost, improves the reliability of the key and has wide application prospect.

In one possible implementation, the sensed member is composed of conductive silicone or conductive foam.

In the implementation mode, the sensed piece adopts conductive silica gel or conductive foam, and when the sensed piece is close to or far away from the capacitance sensing structure, the capacitance value between the sensed piece and the capacitance sensing structure is gradually changed, so that a key position signal can be obtained through processing.

In one possible implementation manner, the sensed member is in a sheet shape or a strip shape, and is adhered or clamped on the surface of the second keycap, which faces the conductive film.

In the implementation mode, the sheet or strip induction piece is connected to one side of the second keycap, which faces the conductive film, in an adhesive or clamping mode, so that the connection is convenient.

In one possible implementation, the capacitive sensing structure includes a first line in a shape of a Chinese character 'shan' and a second line in a shape of a Chinese character 'U', the first line and the second line are spaced apart from each other, the first line is electrically connected to a vcc+ interface of the capacitive signal processing unit at the system end, and the second line is electrically connected to a GND interface of the capacitive signal processing unit at the system end, so that an electric field is formed between the first line and the second line, and when the sensed member approaches or approaches the capacitive sensing structure, the electric field is cut, thereby changing a capacitance between the sensed member and the capacitive sensing structure.

According to the capacitance sensing structure in the implementation mode, the first circuits of the three branches and the second circuits of the two branches are alternately arranged at intervals to form a plurality of groups of capacitance structures at intervals, the capacitance value can be sensitively changed according to the position change of the sensed piece, and then key position signals can be sensitively given according to the displacement of the second key cap.

In one possible implementation manner, the supporting plate is a metal plate, and the through hole is formed at the position of the supporting plate corresponding to the sensed piece.

In this implementation mode, the backup pad is the metal sheet, and only corresponds by the through-hole of seting up of induction spare department, on the one hand, the displacement of metal piece that the metal sheet can shield other positions of film keyboard and probably exist disturbs the response of electric capacity induction structure, on the other hand, and the through-hole of seting up can avoid the backup pad to influence the response of electric capacity induction structure to by the induction spare to ensure that electric capacity induction structure can accurately respond to by the displacement of induction spare.

In one possible implementation, the second pressing component includes a space bar pressing component, the space bar pressing component includes a space bar cap, two scissors supporting structures and an elastic supporting piece, the two scissors supporting structures are respectively supported at two long-direction ends of the space bar cap, the elastic supporting piece is supported at a long-direction middle position of the space bar cap, and the elastic supporting piece and the two scissors supporting structures jointly form a second supporting structure of the space bar pressing component. The space key pressing assembly is provided with two sensed parts, and the two sensed parts are respectively positioned between the elastic supporting part and the two scissor supporting structures. The flexible circuit board comprises a first board section which extends along the long direction parallel to the space key and corresponds to the space key cap, and a capacitance induction structure which corresponds to the two induction parts respectively is arranged on the first board section.

In the implementation mode, the space key is used as a longer key, the difficulty of improving the corner function of the space key is high (if the space key is realized by improving the wall thickness of the space key cap, improving the structural rigidity of the supporting plate and the like), in the implementation mode, the scissors support on two sides and the elastic supporting piece in the middle are used as supports, the key hand feeling is improved to a certain extent, and in addition, the inductive piece and the corresponding capacitance induction structure are respectively arranged on two sides of the elastic supporting piece, so that the space key is not required to press in place to enable the contacts to be in contact, and only the capacitance conduction threshold value of the space key is required to be properly set, so that the required key effect can be achieved. And, in the key process, the elastic support piece can provide elastic support, and the key hand feeling can be set to be consistent with that of a conventional key. In addition, in the structure, only the first plate section corresponding to the space key is additionally arranged on the plate surface of the flexible circuit board, so that the space key corner function can be well solved, and the added cost is low.

In one possible implementation, the thin film keyboard includes a backlight module including a backlight plate and a light source assembly. The backlight plate is arranged on one side of the second surface of the support plate, the light source assembly comprises a light source circuit integrated on the flexible circuit board, and the light source circuit comprises an LED lamp capable of electrified luminescence; the flexible circuit board is positioned on one side of the backlight board far away from the supporting plate.

In the implementation mode, the light source component of the backlight module and the capacitance sensing circuit are integrated on the flexible circuit board on the back of the backlight board, so that the utilization efficiency of the flexible circuit board is improved. Or, for the backlight module originally provided with the flexible circuit board for integrating the light source component, the capacitive sensing circuit adopted by the partial pressing component (the second pressing component) is integrated on the flexible circuit board to realize the capacitive sensing key function, so that the cost increase of the thin film keyboard is small.

In one possible implementation, the flexible circuit board includes a second board section connected to one end of the first board section and forming an L-shaped flexible circuit board with the first board section. The LED lamps are arranged at intervals along the width direction of the space key cap.

In the implementation mode, the flexible circuit board integrates the light source circuit and the capacitance sensing circuit at the same time, and the flexible circuit board has high utilization rate.

In one possible implementation manner, the light source circuit further comprises a plurality of resistors, and the LED lamps and the resistors are connected in series one by one and then connected in parallel with a power supply of the light source circuit.

In this implementation, through resistance and LED board integration in flexible circuit board, simple structure and size are little, provide the low cost of light source.

In one possible implementation, the second pressing assembly is for each key of the membrane keypad having a length greater than a width.

In the implementation mode, the second pressing component is adopted for keys with larger length, and the key triggering is carried out in a capacitive sensing mode, so that the problems that the corner functions of the keys are poor and the hand feeling is influenced can be solved at low cost.

In one possible implementation, the flexible circuit board includes a fourth board portion, a fifth board portion, and a sixth board portion. The fourth plate part corresponds to the column of the left shift key of the thin film keyboard, the fifth plate part corresponds to the column of the right shift key of the thin film keyboard, the sixth plate part corresponds to the row of the space keys of the thin film keyboard, and the fourth plate part, the sixth plate part and the fifth plate part are sequentially connected.

In the implementation mode, the flexible circuit board area is smaller by covering the fourth board part, the fifth board part and the sixth board part of the row where the left shift key is located, the right shift key is located and the space key is located, and common long keys of the thin film keyboard can be well covered.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly describe the drawings in the embodiments, it being understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a thin film keyboard according to an embodiment of the present application;

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

FIG. 3 is another view of the key assembly of FIG. 2;

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

FIG. 5 is a schematic diagram showing the matching relationship between the space key 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 fig. 7;

the layout of the capacitive sensing circuit and the light source circuit on the flexible circuit board is shown in fig. 8;

FIG. 9 is an enlarged view at A of FIG. 8;

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

FIG. 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 side of fig. 11.

Description of main reference numerals:

film keyboard 10

Housing 11

Touch panel 12

Key assembly 20,20a

Support plate 21

Conductive film 22

Flexible printed circuit board 23

Pressing assembly 24

First pressing assembly 24a

Second pressing assembly 24b

Space key press assembly 24c

Backlight module 25

Backlight plate 26

Light source assembly 27

First keycap 28

First support structure 29

Second keycap 30

Second support structure 31

Sensed member 32

Scissor support structure 33

Elastic support 34

Capacitance sensing circuit 35

Capacitance sensing arrangement 36

First plate segment 37

Second plate segment 38

Light source circuit 39

LED lamp 40

Resistor 41

Golden finger 42

First line 43

Second line 44

System side capacitance signal processing unit 45

Tab bond 46a

Capital lock key 46b

Left shift key 46c

Left CTRL key 46d

Space bar 46e

Check key 46f

Enter key 46g

Right shift key 46h

Right CTRL key 46i

Fourth plate portion 47

Fifth plate portion 48

Sixth plate portion 49

Keyhole K1

Avoidance hole K2

Through hole K3

Combined electric field M1

First surface P1

Second surface P2

Interior space Q1

First region S1

Second region S2

Pressing direction Y1

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments.

It will be understood 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 on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.

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

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

Examples

The present embodiment provides a thin film keyboard 10, which may be a keyboard for independent use or a keyboard attached to a notebook computer or the like.

Referring to fig. 1, a membrane keypad 10 in this embodiment includes a housing 11 and a key assembly 20 mounted to the housing 11. The user can input information by pressing a key of the key assembly 20. The number and arrangement of the keys of the key assembly 20 may be arranged according to the 79 key, 83 key, 87 key, 93 key, 96 key, 101 key, 102 key, 104 key, 107 key, etc. of the conventional keyboard. The keys of the membrane keypad 10 in this embodiment include a plurality of normal keys having substantially equal length and width and a plurality of long keys having a length longer than the width. Typical long keys have mainly a space key.

In some embodiments, the thin film keyboard 10 of the present embodiment further includes a touch pad 12 for replacing a common mouse. The touch pad 12 is a conventional structure, and is not described herein. In other embodiments, the touch pad 12 may not be provided.

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

Referring to fig. 2 to 4, a key assembly 20 according to an embodiment of the present application includes a support plate 21, a conductive film 22, a flexible circuit board 23, and a plurality of 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 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 first surface P1 side of the support plate 21, and the flexible circuit board 23 is disposed on the second surface P2 side of the support plate 21. Each set of pressing members 24 is disposed on the first surface P1 side of the support plate 21.

For the embodiment in which the backlight unit 25 is provided, the backlight 26 may be disposed between the support plate 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 provides backlight after passing through the backlight plate 26. Through integrating the light source subassembly 27 of backlight unit 25 on flexible circuit board 23, can realize the effect in a poor light with less structural design, structural arrangement is reasonable and the cost is lower, is favorable to marketing.

In this embodiment, alternatively, the backlight plate 26, the support plate 21 and the conductive film 22 are in a substantially rectangular plate structure, and are sequentially stacked from bottom to top and connected to the bottom surface of the internal space Q1 of the housing 11, and each group of pressing assemblies 24 is respectively connected to the support plate 21 or the conductive film 22 and is respectively exposed from the corresponding key hole K1 on the housing 11, so as to facilitate the key operation of the user.

In this embodiment, the flexible circuit board 23 only needs to cover part of the positions (described in detail later), and the board surface size can be set to be far smaller than that of the backlight 26/the supporting board 21/the conductive film 22, so that the cost of the structure is low. In addition, in order to accommodate the flexible circuit board 23 in thickness, a recess (not shown) for accommodating the flexible circuit board 23 may be concavely formed at a position of the housing 11 or the backlight 26 corresponding to the flexible circuit board 23, thereby avoiding the flexible circuit board 23 from increasing the overall thickness of the membrane keypad 10. Since the board surface size of the flexible circuit board 23 can be set smaller, the provision of the recess has less influence on the overall structural performance of the membrane keyboard 10.

Referring to fig. 5 and 6 in combination, in some embodiments, it may be desirable to provide relief holes K2 in the conductive film 22 to allow the pressing assembly 24 to pass through and attach to the support plate 21. The plate surface space of the conductive film 22 is limited, and the arrangement of the avoiding holes K2 easily influences the arrangement of conductive circuits on the conductive film. Moreover, the position of the avoiding hole K2 needs to have high accuracy to avoid interference between the pressing member 24 and the conductive film 22 during assembly from affecting the connection with the support plate 21. Particularly, for space key equal-length keys (keys with the length of the finger key cap being greater than the width), more or more complex supporting structures are required to be arranged to improve corner functions, so that the avoiding holes K2 are correspondingly more formed in the conductive film 22, and the difficulties of the shape and circuit design of the conductive film 22 and assembly are further increased.

In this embodiment, the conductive film 22 is provided with a first area S1 and a second area S2, and a plurality of contact pairs (not shown in the figure) are distributed on the conductive film 22 in the first area S1, corresponding to a plurality of pressing assemblies 24 in the first area S1. The contact pairs can be electrically energized to generate key signals at corresponding locations. The specific arrangement of the contact pairs and the corresponding conductive traces of the conductive film 22 in the first area S1 may be set as required, which is not described herein. In general, each contact corresponds to one pressing component 24, and when the pressing component 24 is pressed down, the two contacts of the contact pair can be contacted and conducted, so that a corresponding key position signal is generated. In this embodiment, the flexible circuit board 23 extends to at least partially correspond to the second region S2.

The plurality of pressing members 24 are partially defined by a first pressing member 24a and partially defined by a second pressing member 24b. In one implementation of this embodiment, the pressing component 24 of the space key adopts the second pressing component 24b, and the pressing components 24 of the other keys adopt the first pressing component 24a.

Referring again to fig. 4, in the present embodiment, the first pressing component 24a includes a first keycap 28 and a first supporting structure 29, the first keycap 28 is compressibly supported on the supporting plate 21 by the first supporting structure 29 and corresponds to the contact pair, and the first keycap 28 can be pressed to make the contact pair conductive and generate a key position signal of the corresponding position. To avoid the first support structure 29, the conductive film 22 is provided with corresponding holes.

Referring to fig. 4 and 5 in the present embodiment, the second pressing component 24b is a space key pressing component 24c, and the space key pressing component 24c includes a second keycap 30 (i.e. space key cap), a sensed member 32 and a second supporting structure 31, where the second keycap 30 is supported by the second supporting structure 31 on the supporting plate 21, and the sensed member 32 is disposed on the second keycap 30. In order to improve the key feel of the second pressing component 24b, the second supporting structure 31 includes two scissors supporting structures 33 and an elastic supporting member 34, where the two scissors supporting structures 33 are respectively supported at two longitudinal ends of the space key cap, and the elastic supporting member 34 is supported at a longitudinal middle position of the space key cap. The resilient support 34 in this embodiment may be a rubber spring (rubber dome) on the known membrane keyboard 10 that provides some resilient support to facilitate the depression and rebound of the second key cap 30. The rubber elastic member may be supported on the surface of the conductive film 22 or the support plate 21.

In this embodiment, the sensed member 32 is made of conductive silica gel, conductive foam, metal sheet or other conductive structure. Alternatively, the sensed member 32 is in a sheet shape or a strip shape, and the sensed member 32 is adhered or clamped to the surface of the second keycap 30 facing the conductive film 22. In some embodiments, the sensed member 32 may also be integrally formed with the second key cap 30.

In this embodiment, the space key pressing assembly 24c has two sensed members 32, and the two sensed members 32 are respectively located between the elastic supporting member 34 and the two scissors supporting structures 33 and symmetrically arranged.

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

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

The first board section 37 extends along a length direction parallel to the space bar and corresponds to the space bar cap, and the first board section 37 is provided with capacitance sensing structures 36 corresponding to the two sensed members 32 respectively. For the thin film keyboard 10 provided with the backlight module 25 as described above, the light source assembly 27 includes the light source circuit 39 integrated with the flexible circuit board 23, the light source circuit 39 includes the LED lamp 40 capable of being energized to emit light, and the flexible circuit board 23 is located on the side of the backlight board 26 away from the support plate 21. The second plate section 38 is connected to one end of the first plate section 37, and forms an L-shaped flexible circuit board 23 with the first plate section 37. The LED lamps 40 are arranged in plurality, and the LED lamps 40 are arranged at intervals along the width direction of the space key cap. Optionally, the light source circuit 39 further includes a plurality of resistors 41, and the led lamp 40 and the resistors 41 are connected in series and then connected in parallel to the power supply of the light source circuit 39. The flexible circuit board can be connected to the host through the golden finger 42, and can also be connected through other connection modes.

In this embodiment, the light source circuit 39 of the backlight module 25 and the capacitance sensing circuit 35 are integrated on the flexible circuit board 23 on the back surface of the backlight board 26, so that the utilization rate of the flexible circuit board 23 is improved. In other words, in the backlight module 25 which is used in some of the applicant's technologies and is provided with the flexible circuit board 23 for integrating the light source module 27, the capacitive sensing circuit 35 used in the partial pressing module 24 (the second pressing module 24 b) is integrated in the flexible circuit board 23 to realize the capacitive sensing key function, and thus the cost increase of the thin film keyboard 10 is small.

The part of the pressing component 24 (the second pressing component 24 b) of the thin film keyboard 10 in the embodiment of the application realizes non-contact triggering of key signals through the flexible circuit board 23 and the capacitance sensing circuit 35 arranged on the flexible circuit board and through the capacitance value change between the sensed piece 32 and the corresponding capacitance sensing structure 36 arranged on the second key cap 30 during key pressing, is particularly suitable for long keys (such as space keys and the like) with easily bad corner functions, can solve the problem of bad corner functions on the premise of keeping the key stroke and the whole thickness of the keyboard with low cost, improves the key reliability, and has wide application prospect. Particularly, for the space key equal-length keys, the difficulty of improving the corner functions of the space key equal-length keys in the prior art is high (for example, the space key cap wall thickness is required to be improved, the structural rigidity of the supporting plate 21 is required to be improved, and the like), in the embodiment, the scissor supporting structures 33 on two sides and the elastic supporting piece 34 in the middle are used as supports, so that the key hand feeling is improved to a certain extent, and the inductive pieces 32 and the corresponding capacitance inductive structures 36 are respectively arranged on two sides of the elastic supporting piece 34, so that the space key is not required to press in place to enable the contacts to be in contact, and only the capacitance conduction threshold value is required to be properly set, so that the required key effect can be achieved. Also, the elastic support 34 may provide elastic support during key pressing, and the key touch thereof may be set to be consistent with conventional keys. Meanwhile, in the structure, the space key corner function can be well solved only by additionally arranging the first plate section 37 corresponding to the space key on the plate surface of the flexible circuit board 23, and the added cost is low.

Referring again to fig. 9 and 10, in an alternative embodiment, the capacitance sensing structure 36 includes a first line 43 having a mountain shape and a second line 44 having a U shape, the first line 43 and the second line 44 being spaced apart from each other, the first line 43 being electrically connected to a vcc+ interface (power interface) of the system side capacitance signal processing unit 45, the second line 44 being electrically connected to a GND interface (ground interface) of the system side capacitance signal processing unit 45 such that an electric field is formed between the first line 43 and the second line 44, and the sensed member 32 will cut the electric field when approaching or separating from the capacitance sensing structure 36, thereby changing the capacitance between the sensed member 32 and the capacitance sensing structure 36. The capacitance sensing structure 36 in this implementation manner is formed by alternately arranging the first lines 43 of the three branches and the second lines 44 of the two branches at intervals, so as to form a multi-group capacitance structure with intervals, so that the capacitance value can be sensitively changed according to the position change of the sensed member 32, and further, the key position signal can be sensitively given according to the displacement of the second key cap 30, meanwhile, when the capacitance sensing line of the structure is connected with alternating current, the combined electric field M1 with two electric field lines approximately in an arch shape can be generated, as shown in fig. 5, so that the sensed member 32 can reliably sense the displacement of the sensed member 32 when the key is pressed even if a certain deviation exists in the lateral (long or wide) arrangement position of the space key.

Referring to fig. 4, 5 or 7, in one possible implementation, the supporting plate 21 is a metal plate, and a through hole K3 is formed at a position of the supporting plate 21 corresponding to the sensed member 32. In this implementation manner, the supporting plate 21 is a metal plate, and the through hole K3 is only formed at the position corresponding to the sensed piece 32, so that on one hand, the metal plate can shield the sensing of the capacitive sensing structure 36 by the displacement of the metal piece possibly existing at other positions of the thin film keyboard 10, and on the other hand, the formed through hole K3 can avoid the supporting plate 21 from affecting the sensing of the capacitive sensing structure 36 to the sensed piece 32, thereby ensuring that the capacitive sensing structure 36 can accurately sense the displacement of the sensed piece 32.

In some embodiments, no contact pairs are provided within the second region S2, and key position signals are generated in other ways (specifically described below). Because the second area S2 does not need to be provided with a contact pair to generate a key position signal, the design of the avoidance hole K2 on the second area is not affected by the contact pair or the circuit thereof, and the avoidance hole K2 can be reasonably arranged as required to maximally improve the key feel of the pressing assembly 24. In other implementations, the second region S2 of the conductive film 22 may be partially or completely cut away as desired, so that the corresponding pressing assembly 24 can be conveniently connected directly to the support plate 21 without being blocked by the conductive film 22.

The second area S2 may also retain a contact pair and a corresponding circuit, so that a key signal may be obtained by one of contact pair contact and capacitance detection, thereby further improving the reliability of the key.

Referring to fig. 11 and 12 in combination, in another implementation of the present embodiment, the second pressing component 24b of the key assembly 20a is used for each key of the membrane keyboard 10 with a length greater than a width, including a Tab key 46a, a capital lock key 46b, a left shift key 46c and a left CTRL key 46d, a space key 46e of the membrane keyboard 10 downstream, a return key 46f, a carriage return key 46g, a right shift key 46h and a right CTRL key 46i of the membrane keyboard 10, and so on the left side of the membrane keyboard 10. For this embodiment, the flexible circuit board 23 includes a fourth plate portion 47, a fifth plate portion 48, and a sixth plate portion 49. The fourth plate portion 47 corresponds to a column where the left shift key 46c of the membrane keyboard 10 is located, the fifth plate portion 48 corresponds to a column where the right shift key 46h of the membrane keyboard 10 is located, the sixth plate portion 49 corresponds to a row where the space key 46e of the membrane keyboard 10 is located, and the fourth plate portion 47, the sixth plate portion 49, and the fifth plate portion 48 are connected in order. In this implementation, the flexible circuit board 23 has a smaller area and can better cover the common long keys of the thin-film keyboard 10 by covering the fourth plate portion 47, the fifth plate portion 48 and the sixth plate 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 key 46e is located.

The above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A membrane keypad, comprising:

a support plate having first and second opposed surfaces;

the conductive film is overlapped on one side of the first surface of the supporting plate; the conductive film is provided with a first area and a second area, contact pairs are distributed in the first area, and the contact pairs can be electrically conducted under pressure to generate key position signals at corresponding positions;

the flexible circuit board is arranged on one side of the second surface of the supporting plate and extends to at least partially correspond to the second area;

the pressing assemblies are arranged in a plurality of groups, wherein part of the pressing assemblies is a first pressing assembly and part of the pressing assemblies is a second pressing assembly;

the first pressing component comprises a first keycap and a first supporting structure, the first keycap is compressibly supported on the supporting plate by the first supporting structure and corresponds to the contact pairs, and the first keycap can be pressed to conduct the contact pairs and generate key position signals of corresponding positions;

the second pressing assembly comprises a second keycap, an inducted piece and a second supporting structure, the second keycap is supported by the second supporting structure on the supporting plate, and the inducted piece is arranged on the second keycap;

the flexible circuit board is integrated with a capacitance sensing circuit, the capacitance sensing circuit comprises a capacitance sensing structure, the capacitance sensing structure corresponds to the second area and corresponds to the sensed piece in the pressing direction along the second key cap, when the second key cap is pressed, the capacitance sensing circuit can sense the capacitance value change between the capacitance sensing structure and the sensed piece, and when the capacitance value reaches the capacitance conduction threshold value of the capacitance sensing circuit, a key position signal of a corresponding position is generated;

the thin film keyboard further comprises a backlight module, wherein the backlight module comprises a backlight plate and a light source assembly;

the backlight plate is arranged on one side of the second surface of the supporting plate, the light source assembly comprises a light source circuit integrated on the flexible circuit board, and the light source circuit comprises an LED lamp capable of electrified luminescence; the flexible circuit board is positioned on one side of the backlight board far away from the supporting plate.

2. The membrane keypad of claim 1, wherein:

the sensed piece is composed of conductive silica gel or conductive foam.

3. The membrane keypad of claim 1, wherein:

the sensed piece is in a sheet shape or a strip shape, and is adhered or clamped on the surface of one side, facing the conductive film, of the second keycap.

4. The membrane keypad of claim 1, wherein:

the capacitive sensing structure comprises a first line in a mountain shape and a second line in a U shape, the first line and the second line are spaced from each other, the first line is electrically connected to a VCC+ interface of the capacitive signal processing unit at the system end, the second line is electrically connected to a GND interface of the capacitive signal processing unit at the system end, so that an electric field is formed between the first line and the second line, and when a sensed piece is close to or far away from the capacitive sensing structure, the electric field is cut, so that the capacitance between the sensed piece and the capacitive sensing structure is changed.

5. The membrane keypad of claim 1, wherein:

the supporting plate is a metal plate, and a through hole is formed in the position, corresponding to the sensed piece, of the supporting plate.

6. The membrane keypad of any of claims 1-5, wherein:

the second pressing component comprises a space key pressing component, the space key pressing component comprises a space key cap, two scissor supporting structures and an elastic supporting piece, the two scissor supporting structures are respectively supported at the two long-direction ends of the space key cap, the elastic supporting piece is supported at the middle position of the space key cap in the long-direction, and the elastic supporting piece and the two scissor supporting structures jointly form the second supporting structure of the space key pressing component;

the space key pressing assembly comprises two sensed pieces, wherein the two sensed pieces are respectively positioned between the elastic supporting piece and the two scissor supporting structures;

the flexible circuit board comprises a first board section which extends along a long direction parallel to the space key and corresponds to the space key cap, and a capacitance induction structure which corresponds to the two induction parts respectively is arranged on the first board section.

7. The membrane keypad of claim 6, wherein:

the flexible circuit board comprises a second board section, wherein the second board section is connected to one end of the first board section and forms an L-shaped flexible circuit board with the first board section;

the LED lamps are arranged in a plurality, and the LED lamps are arranged at intervals along the width direction of the space key cap.

8. The membrane keypad of claim 7, wherein:

the LED lamp is connected with the resistors in series one by one and then connected with the power supply of the light source circuit in parallel.

9. The membrane keypad of claim 1, wherein:

the second pressing component is used for each key of which the length is larger than the width of the film keyboard.

10. The membrane keypad of claim 9, wherein:

the flexible circuit board comprises a fourth board part, a fifth board part and a sixth board part;

the fourth plate part corresponds to a column where a left shift key of the thin film keyboard is located, the fifth plate part corresponds to a column where a right shift key of the thin film keyboard is located, the sixth plate part corresponds to a row where a space key of the thin film keyboard is located, and the fourth plate part, the sixth plate part and the fifth plate part are sequentially connected.