Patent ID: 12223131

DETAILED DESCRIPTION

Embodiments of this application are described in detail below, and examples of the embodiments are shown in accompanying drawings, where the same or similar elements or the elements having same or similar functions are denoted by the same or similar reference numerals throughout the description. The embodiments described below with reference to the accompanying drawings are exemplary and used only for explaining this application, and should not be construed as a limitation on this application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the protection scope of this application.

A feature defined by terms “first” or “second” in this specification and claims of this application can explicitly or implicitly include one or more features. In the description of this application, unless otherwise stated, “a plurality of” means two or more than two. In addition, in this specification and the claims, “and/or” means at least one of the connected objects, and the character “/” generally indicates an “or” relationship between the associated objects.

In the description of this application, it should be noted that unless otherwise explicitly specified or defined, the terms such as “mount,” “install,” “connect,” and “connection” should be understood in a broad sense. For example, the connection may be a fixed connection, a detachable connection, or an integral connection; or the connection may be a mechanical connection or an electrical connection; or the connection may be a direct connection, an indirect connection through an intermediary, or internal communication between two components. A person of ordinary skill in the art may understand the specific meanings of the foregoing terms in this application according to specific situations.

As shown inFIG.1toFIG.10, an embodiment of this application provides a force sensing module100, including: a first flexible circuit board10, a substrate20, and a second flexible circuit board30stacked in sequence. The substrate20includes a first surface21and a second surface22disposed opposite to each other, and the first surface21is provided with a first groove23.

One side of the first flexible circuit board10facing the first surface21is disposed with a first force sensing resistor11and a second force sensing resistor12, and both the first force sensing resistor11and the second force sensing resistor12are across the first groove23and attached to the first surface21.

One side of the second flexible circuit board30facing the second surface22is disposed with a third force sensing resistor31and a fourth force sensing resistor32, the third force sensing resistor31corresponds to the first force sensing resistor11, the fourth force sensing resistor32corresponds to the second force sensing resistor12, and both the third force sensing resistor31and the fourth force sensing resistor32are attached to the second surface22.

The first force sensing resistor11, the second force sensing resistor12, the third force sensing resistor31, and the fourth force sensing resistor32constitute a Wheatstone bridge structure200, the force sensing module100further includes a detection circuit40electrically connected to the Wheatstone bridge structure200, and the detection circuit40is configured to detect a differential voltage of the Wheatstone bridge structure200.

In this embodiment, providing the first groove23on the substrate20to form an accommodating space required for deformation of the first force sensing resistor11and the second force sensing resistor12can effectively simplify the assembly process of the force sensing module100compared with providing a gap provided between two substrates. Moreover, due to the poor stiffness of the first flexible circuit board10and the second flexible circuit board30, stacking the first flexible circuit board10and the second flexible circuit board30on the substrate20with an integral structure can improve the structural strength of the force sensing module100.

In addition, since the force sensing resistor itself is brittle and has poor stress resistance, arranging a fixed structure between the first flexible circuit board10and the second flexible circuit board30as the substrate20including the first groove23can avoid the phenomenon that the force sensing resistor is easily pulled off due to the stiffness difference between the first flexible circuit board10and the second flexible circuit board30, thereby improving the yield of the force sensing module in the assembly process.

Moreover, compared with using two spaced substrates as a support structure of the first flexible circuit board10and the second flexible circuit board30, using the substrate20in this application as the support structure of the first flexible circuit board10and the second flexible circuit board30can not only enable the substrate20to effectively support the first flexible circuit board10and the second flexible circuit board30, but also avoid displacement between the spaced two substrates in the assembly process, which affects the sensitivity and assembly yield of the force sensing module; and can further improve the reliability of the force sensing module in the transportation process, and avoid the phenomenon that the force sensing resistor of the force sensing module is pulled off.

Further, providing the first groove23on the substrate20can improve the opening precision of the first groove23, so that the width of the first groove23can be designed as small as possible to improve the sensitivity of the force sensing module by reducing the width of the first groove23.

In some implementations, a width of the first groove23is negatively correlated with a sensitivity of the force sensing module100, that is, the sensitivity of the force sensing module100can be increased by reducing the width of the first groove23; and/or a depth of the first groove23is positively correlated with the sensitivity of the force sensing module100, that is, the sensitivity of the force sensing module100can be increased by increasing the depth of the first groove23.

For example, when a thickness of the substrate20is small, the sensitivity of the force sensing module100can be increased by increasing the width of the first groove23. When the substrate20is thick, the sensitivity of the force sensing module100can be increased by increasing the depth of the first groove23.

It can be understood that when the force sensing module100senses deformation, which leads to a change of bridge resistance, a differential voltage of the Wheatstone bridge structure200detected by the detection circuit40also changes, and the change of the differential voltage can be transmitted to a processor, and amplified internally by the processor to sense the pressure sensed by the force sensing module100, thereby achieving corresponding functions of the force sensing module100, such as a power button function.

In an example, the detection circuit40is electrically connected to the Wheatstone bridge structure200, which can be understood as that the detection circuit40is electrically connected to the first force sensing resistor11, the second force sensing resistor12, the third force sensing resistor31, and the fourth force sensing resistor32.

The processor and the detection circuit40can be disposed on the first flexible circuit board10, or on the second flexible circuit board30, or on the first flexible circuit board10and the second flexible circuit board30respectively. Moreover, the processor and the detection circuit40are electrically connected to implement signal transmission, thereby achieving the sensing function of the force sensing module100.

In an example, when the force sensing module100is applied to an electronic device, the processor may be a central processing unit or a microprocessor of the electronic device, and the processor may be disposed on a main board of the electronic device and electrically connected to the detection circuit40disposed on the first flexible circuit board10or the second flexible circuit board30.

When the first force sensing resistor11, the second force sensing resistor12, the third force sensing resistor31, and the fourth force sensing resistor32constitute the Wheatstone bridge structure200shown inFIG.2, and an external force acts on one side of the first flexible circuit board10of the force sensing module100, the resistance of the first force sensing resistor11and the second force sensing resistor12being pressed decreases, and the resistance of the third force sensing resistor31and the fourth force sensing resistor32being pressed increases. Based on the working principle of the Wheatstone bridge, a voltage U can be obtained. Moreover, under the same pressure condition, the larger the voltage U, the higher the sensitivity of the force sensing module100.

In an example, when the width of the first groove23is a, the length of the force sensing resistor being pressed changes to Δa, the length of the substrate20is L, the thickness of the substrate20is t, and the resistance change coefficient of the resistor is ε.

A formula of the resistance change coefficient of the resistor is ε=k*t/2*(L/a+1).

In this formula, k is related to the pressure of pressing. Under the same pressure condition, the voltage U and the change coefficient ε are positively correlated and in a linear relationship. Therefore, the sensitivity of the force sensing module100can be increased by increasing the thickness t of the substrate20, or decreasing the width a of the first groove23, or increasing the length L of the substrate20.

In some implementations, the third force sensing resistor31and the fourth force sensing resistor32are across a projection area of the first groove23on the second surface22, so that the sensitivity of the force sensing module100can be further increased.

In some implementations, the second surface22is provided with a second groove24, the first groove23at least partially overlaps the second groove24in the projection area of the second surface22, and the third force sensing resistor31and the fourth force sensing resistor32are across the second groove24.

In this embodiment, the second groove24can form an accommodating space required for deformation of the third force sensing resistor31and the fourth force sensing resistor32. Moreover, by providing the second groove24, deformation points of the substrate20corresponding to the area of the second groove24is closer to the action area of the external force, so that the substrate20can produce greater deformation, even if the resistance change amount of the third force sensing resistor31and the fourth force sensing resistor34being pressed increases, thereby further improving the sensitivity of the force sensing module100.

In an example, the second groove24may coincide with the projection area of the first groove23on the second surface22.

In some implementations, the side of the first flexible circuit board10facing the first surface21are further disposed with a first temperature compensation resistor13and a second temperature compensation resistor14, the first temperature compensation resistor13and the second temperature compensation resistor14are distributed on two opposite sides of the first groove23, and both the first temperature compensation resistor13and the second temperature compensation resistor14are attached to the first surface21.

In this embodiment, since the structures of the substrate20located on both sides of the first groove23are integrated, the accuracy of temperature compensation for the substrate20by the first temperature compensation resistor13and the second temperature compensation resistor14can be improved.

Furthermore, the side of the second flexible circuit board30facing the second surface22is further disposed with a third temperature compensation resistor33and a fourth temperature compensation resistor34, the third temperature compensation resistor33and the fourth temperature compensation resistor34are distributed on two opposite sides of the second groove24, and both the third temperature compensation resistor33and the fourth temperature compensation resistor34are attached to the second surface22.

In this embodiment, since the structures of the substrate20located on both sides of the second groove24are integrated, the accuracy of temperature compensation for the substrate20by the third temperature compensation resistor33and the fourth temperature compensation resistor34can be improved.

In addition, the substrate20in this application may be a thermally conductive metal plate, so that the thermal conductivity of the substrate20can be improved, thereby improving the temperature consistency of the temperature compensation resistor and the force sensing resistor, and improving the accuracy of temperature compensation.

As shown inFIG.11, an embodiment of this application further provides an electronic device, including a display screen300and the above force sensing module100, where the force sensing module100is located at an inner side of the display screen300.

In an example, the first flexible circuit board of the force sensing module100is attached to the display screen300, that is, the first groove of the force sensing module100is disposed close to the display screen300. In this way, an under-screen pressure sensing function of the electronic device can be achieved.

In another example, the second flexible circuit board of the force sensing module100is attached to the display screen300, that is, the first groove of the force sensing module100is disposed away from the display screen300. In this way, the under-screen pressure sensing function of the electronic device can be achieved. Moreover, since the first groove is disposed away from the display screen300, the distance between the pressure deformation points of the substrate and the display screen300is closer, leading to larger deformation of the substrate. It means the voltage U detected by the detection circuit40of the force sensing module100is larger, so that the sensitivity of the force sensing module100can be further improved.

In addition, the implementations of the above embodiments of the force sensing module100are also applicable to the embodiments of the electronic device and can achieve the same technical effect. Details are not described herein again.

The electronic device may be a mobile phone, a tablet computer, a notebook computer, a palmtop computer, a vehicle-mounted electronic device, a wearable device, an Ultra-Mobile Personal Computer (UMPC), a netbook, a Personal Digital Assistant (PDA), or the like.

In the descriptions of this specification, descriptions using reference terms “an embodiment,” “some embodiments,” “an exemplary embodiment,” “an example,” “a specific example,” or “some examples” mean that specific characteristics, structures, materials, or features described with reference to the embodiment or example are included in at least one embodiment or example of this application. In this specification, exemplary descriptions of the foregoing terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials, or characteristics may be combined in a proper manner in any one or more embodiments or examples.

Although the embodiments of this application have been shown and described, a person of ordinary skill in the art should understand that various changes, modifications, replacements and variations may be made to the embodiments without departing from the principles and spirit of this application, and the scope of this application is as defined by the appended claims and their equivalents.