Patent Description:
This application relates to the field of terminal technologies, and in particular, to a foldable electronic device.

In recent years, with the continuous development of screen technologies, especially the emergence of flexible screens, more product forms have been developed for electronic devices. A folding display phone is a currently emerging product form. The folding display phone generally includes a shaft cap and a body on both sides of the shaft cap. The body on each side may be connected to the shaft cap through at least one swing arm. The swing arm may rotate around a rotation shaft in the shaft cap. When a user applies a force to the body to rotate the body, the body may rotate around the rotation shaft to implement unfolding and folding.

In order to provide a damping force when the user opens and closes the body, to improve the hand feeling, a damping component connected to the swing arm is further arranged in the shaft cap. The damping component includes a pair of cam components in pressure contact along a direction of the rotation shaft. The damping force is provided by a friction force generated by surface design of the cam component and the pressure contact, and a pressure that implements the pressure contact of the cam components is provided by an elastic force generated when a spring arranged in the shaft cap deforms.

Technicians hope that the existing folding display phone can have a freestop characteristic, that is, the body of the folding display phone under no external force can stay in the current position, to improve the user experience. One feasible manner for implementing the freestop characteristic is to increase a friction coefficient of a damping component system, where the friction coefficient is related to the quantity and size of springs: the more the springs, the larger the friction coefficient, otherwise, the less the springs, the smaller the friction coefficient; and the larger the spring size, the larger the friction coefficient, otherwise, the smaller the spring size, the smaller the friction coefficient. Therefore, the existing folding display phone generally implements the freestop characteristic by increasing the quantity of springs and the diameter of the springs. However, with an increase of the quantity of springs and the size of the springs, the springs take up more space of the body, resulting in an increase of the overall thickness and weight of the folding display phone, which is not conducive to thinning of the body.

<CIT> relates to an arm structure of an electronic device. The arm structure includes an arm body, a first cam disposed on one side of the arm body and including a first hole into which at least a portion of a rotating shaft providing a folding operation of the electronic device is inserted, a peak and a valley being formed around the first hole, a second cam arranged side-by-side on a same axis as the one side of the arm body, spaced apart from the first cam, and including a second hole into which at least a portion of the rotating shaft is inserted, a peak and a valley being formed around the second hole, and a connecting part disposed on another side of the arm body and fastened with a rotating part providing rotation of the electronic device.

Embodiments of this application provide a foldable electronic device, which can implement the freestop characteristic while maintaining a thin body. The foldable electronic device includes a shaft cap, a body, a swing arm, a first cam component, a second cam component, and an elastomer. The first cam component and the second cam component are coaxially arranged in the shaft cap; the first cam component is connected to the body through the swing arm and is configured to be rotatable around a central shaft of the first cam component, so that the body is folded or unfolded around the central shaft under the action of an external force; the first cam component includes a first end surface facing the second cam component, the second cam component includes a second end surface facing the first cam component, and the first end surface and the second end surface each include at least one cam surface; the second cam component is configured to be slidable along a direction of the central shaft; the elastomer is connected to the second cam component and is configured to apply an elastic force to the second cam component, so that the first end surface of the first cam component maintains in contact with the second end surface of the second cam component under the action of the elastic force; and in a case that the body is unfolded or folded to a position between fully unfolded and fully folded, the first cam component and the second cam component are in contact with a locking section of the cam surface, and an angle between a normal direction of the locking section and the central shaft is less than or equal to arctan µ, where µ is a friction coefficient between the first cam component and the second cam component.

In the foldable electronic device provided in the embodiments of this application, a contact surface of the first cam component and the second cam component includes at least one cam surface that matches with each other. The cam surface includes a locking section, an angle between a normal direction of the locking section and the central shaft is less than or equal to an arctan function of µ, where µ is a friction coefficient between the first cam component and the second cam component, and a resultant force of a cam driving member in a rotation direction of the cam driving member is <NUM>, so that the body is not automatically unfolded or folded, thereby implementing the freestop characteristic.

The cam surface includes a rise travel section and a return travel section, and the locking section is a part of the rise travel section; and the locking section rise travel section includes a plurality of locking planes along a lifting direction of the rise travel section, and an angle between a normal direction of any of the locking planes and the central shaft is less than or equal to arctan µ. In this way, with the rotation of the body to different positions, the first cam component and the second cam component can implement surface contact in different locking planes. While the freestop characteristic is provided, a contact stress between the first cam component and the second cam component can be reduced through the surface contact, which improves the service life of the first cam component and the second cam component.

In an implementation, the first end surface and the second end surface are matched annular end surfaces; and the first end surface and the second end surface each include an equal quantity of a plurality of cam surfaces, and the plurality of cam surfaces are distributed in an annular array. In this way, the forces on the first cam component and the second cam component along the direction of the central shaft C1 are relatively uniform, which improves the service life of the components. In an implementation, an angle βby which the locking section rotates around the central shaft C1 is greater than or equal to <NUM>°. Because an angle by which the body on each side of the folding display phone rotates from a fully folded state to a fully unfolded state is <NUM>°, if the angle β by which the locking section rotates around the central shaft C1 is greater than or equal to <NUM>°, the first cam component and the second cam component may be always in contact with the locking section during folding or unfolding of the body, so that the body has the freestop characteristic at any position.

In an implementation, angles between normal directions of the plurality of locking planes and the central shaft decrease sequentially in the lifting direction of the rise travel section. In this way, slopes of the rise travel section can be gradually smooth in the lifting direction of the rise travel section, and finally a smooth transition between a top of the rise travel section and the return travel section can be implemented.

In an implementation, lengths of the plurality of locking planes decrease sequentially in the lifting direction of the rise travel section. In this way, with the slopes of the rise travel section are gradually smooth in the lifting direction of the rise travel section, the locking planes is divided in more detail, so that the slope change at the top of the rise travel section is smoother, which is beneficial to improving the hand feeling when a user rotates the body.

In an implementation, two adj acent locking planes are transitionally connected by a curved surface. In this way, when the user rotates the body to cause the first cam component and the second cam component to slide relative to each other, the contact surface of the first cam component and the second cam component can smoothly transit between the locking planes, thereby avoiding vibration when sliding between two adjacent locking planes, which is beneficial to improving the hand feeling when the user rotates the body.

In an implementation, the locking section starts from a middle and lower part of the rise travel section, is formed to a top of the cam surface along the lifting direction of the rise travel section, and is connected to the return travel section at the top of the cam surface. In this way, compared with the conventional solution, the locking section covers most of the rise travel section and all of a stop section. When the body of the electronic device rotates from the fully unfolded state to the fully unfolded state, the first cam component and the second cam component can be in contact with the locking section in the entire process, to implement the freestop characteristic.

In an implementation, the locking section is connected to the return travel section through a curved surface. In this way, when the user rotates the body to cause the first cam component and the second cam component to slide relative to each other, the contact surface of the first cam component and the second cam component can smoothly transit between the locking section and the return travel section, thereby avoiding vibration when sliding between the locking section and the return travel section, which is beneficial to improving the hand feeling when the user rotates the body.

In an implementation, a length of the locking section is greater than half of the rise travel section. In an implementation, the elastomer is a spring, and the spring is arranged coaxially with the second cam component and in a compressed state along the direction of the central shaft to apply the elastic force to the second cam component along the direction of the central shaft.

In an implementation, the locking section is arranged on the at least one cam surface of the first end surface and/or the second end surface.

Illustration of the drawings:
<NUM>-body, <NUM>-display screen, <NUM>-shaft cap, <NUM>-swing arm, <NUM>-damping component, <NUM>-cam driving member, <NUM>-cam driven member, <NUM>-spring, <NUM>-cam surface, <NUM>-rise travel section, <NUM>-stop section, <NUM>-return travel section, <NUM>-first cam component, <NUM>-second cam component, <NUM>-elastomer, <NUM>-cam surface, <NUM>-rise travel section, <NUM>-locking section, <NUM>-locking plane, <NUM>-return travel section, <NUM>-curved surface, <NUM>-curved surface.

In recent years, with the continuous development of screen technologies, especially the emergence of flexible screens that can be freely bent, more product forms have been developed for electronic devices. A folding display phone is a currently emerging product form.

<FIG> is a schematic diagram of a form of an existing folding display phone. As shown in <FIG>, the existing folding display phone may include an in-folding display phone and an out-folding display phone according to a bending direction of the screen of the folding display phone. The in-folding display phone is shown as structure a in <FIG>, and the out-folding display phone is shown as structure b in <FIG>. A body <NUM> of the in-folding display phone can be folded to a side of a display screen <NUM>, and the display screen <NUM> is hidden at an inner side of the body <NUM> after the body <NUM> is folded, thereby forming an effect that the display screen <NUM> is hidden in a folded state of the body <NUM> and presented in an unfolded state of the body <NUM>. A body <NUM> of the out-folding display phone can be folded to a back side of a display screen <NUM>, and the display screen <NUM> surrounds an outer side of the body <NUM> after the body <NUM> is folded, thereby forming an effect that the display screen <NUM> surrounds the body <NUM> in a folded state of the body <NUM> and presents a normal direct screen in an unfolded state of the body <NUM>.

<FIG> is a schematic diagram of an internal structure of an existing folding display phone. How the body of the existing folding display phone is folded or unfolded is described exemplarily below with reference to <FIG>. As shown in <FIG>, the folding display phone includes: a shaft cap <NUM> and a body <NUM>. The body <NUM> of the folding display phone that can be folded once may include two parts, respectively arranged on both sides of the shaft cap <NUM>, and the body <NUM> on each side of the folding display phone may be connected to the shaft cap <NUM> through at least one swing arm <NUM>. One end of the swing arm <NUM> is located in the shaft cap <NUM> and is configured to be rotatable around a rotation shaft in the shaft cap <NUM>, and the other end of the swing arm <NUM> extends to the body <NUM> on one side to be connected to the body <NUM>. In this way, when a user applies a force to the body <NUM> to rotate the body <NUM>, the body <NUM> may rotate around the rotation shaft to implement unfolding and folding.

In addition, in order to provide a damping force when the user opens and closes the body <NUM>, to improve the hand feeling, a damping component <NUM> connected to the swing arm <NUM> is further arranged in the shaft cap <NUM>. The damping component <NUM> may, for example, be a cam damping component or a gear damping component, and is configured to apply a damping force opposite to a rotation direction to the swing arm <NUM> when the body <NUM> drives the swing arm <NUM> to rotate. The damping force may be transmitted to a hand of the user through the swing arm <NUM> and the body <NUM>, thereby improving the hand feeling of the user and the classic sense of the device.

<FIG> further exemplarily shows a specific structure of the damping component. As shown in <FIG>, the damping component <NUM> includes a cam driving member <NUM>, a cam driven member <NUM>, and a spring <NUM>. The swing arm <NUM> uses a central shaft C1 of the cam driving member <NUM> as the rotation shaft when the swing arm <NUM> rotates, and the cam driving member <NUM> and the cam driven member <NUM> are arranged side by side and coaxially along a direction of the central shaft C1. The cam driving member <NUM> is connected to one end of the swing arm <NUM> located in the shaft cap <NUM>, and the cam driving member <NUM> is configured to be fixed along the direction of central shaft C1, but rotatable around the central shaft C1. The cam driven member <NUM> is configured to be non-rotatable around the central shaft C1, but slidable along the direction of the central shaft C1. The spring <NUM> is connected to the cam driven member <NUM> and is configured to apply an elastic force Ft to the cam driven member <NUM>. A direction of the elastic force Ft may be parallel to the central shaft C1 and towards the cam driving member <NUM>. In this way, the cam driven member <NUM> can maintain pressure contact with the cam driving member <NUM> along the direction of the central shaft C1 under the action of the elastic force Ft. When the user rotates the body <NUM>, the swing arm <NUM> drives the cam driving member <NUM> to rotate around the central shaft C1, thereby generating relative sliding with the cam driven member <NUM> at a contact surface.

In order to provide the damping force, the contact surface of the cam driving member <NUM> and the cam driven member <NUM> may include cam surfaces <NUM> that match with each other. <FIG> is a schematic diagram of an existing cam surface <NUM>. In <FIG>, when the body of the folding display device is unfolded from the folded state, the cam driving member <NUM> slides relative to the cam driven member <NUM> to the left side in <FIG>, and the cam driven member <NUM> slides relative to the cam driving member <NUM> to the right side in <FIG>. As shown in <FIG>, the cam surface <NUM> sequentially includes, along a sliding direction of the cam driving member <NUM> or the cam driven member <NUM>, a rise travel section <NUM>, a stop section <NUM>, and a return travel section <NUM>. The rise travel section, the stop section, and the return travel section are technical terms for describing a cam structure in a mechanical field. The rise travel section <NUM> refers to a section in which the cam driven member <NUM> is far away from the cam driving member <NUM> when the cam driving member <NUM> slides relative to the cam driven member <NUM>, so that the rise travel section <NUM> has a rising angle along the sliding direction of the cam driving member <NUM>/the cam driven member <NUM>. The stop section <NUM> refers to a section in which a distance from the cam driven member <NUM> relative to the cam driving member <NUM> is constant when the cam driving member <NUM> slides relative to the cam driven member <NUM>, so that the stop section <NUM> is perpendicular to the central shaft C1. The return travel section <NUM> refers to a section in which the cam driven member <NUM> is brought close to the cam driving member <NUM> when the cam driving member <NUM> slides relative to the cam driven member <NUM>, so that the return travel section <NUM> has a falling angle along the sliding direction of the cam driving member <NUM>/cam driven member <NUM>. Generally, when the body of the folding display phone rotates between a fully folded state and a fully unfolded state, the cam driving member <NUM> and the cam driven member <NUM> are in pressure contact and slide at the rise travel section <NUM> or the stop section <NUM> of the cam surface.

<FIG> is a force analysis diagram of a cam driving member and a cam driven member. When the cam driving member <NUM> and the cam driven member <NUM> are in contact with the rise travel section <NUM> of the cam surface, the cam driven member <NUM> applies a pressure Fn to the cam driving member <NUM> under the action of the elastic force Ft. The pressure Fn acts on a normal direction of the rise travel section <NUM> of the cam driving member <NUM>, and Fn=Ft×cos α, where Ft is the elastic force of the spring, and α is an angle between the normal direction of the rise travel section <NUM> and the elastic force Ft. In this way, Fn generates a component Fn×sin α in an opposite direction in which the cam driving member <NUM> slides, and the component is a part of the damping force. When the user rotates the body, the force applied to the body needs to overcome the component to rotate the cam driving member <NUM>.

Further, as shown in <FIG>, when the cam driving member <NUM> and the cam driven member <NUM> are in contact with the rise travel section <NUM>, a component of the elastic force Ft received by the cam driven member <NUM> is Ft×sin α in a tangential direction of the rise travel section <NUM>, and a component of the elastic force Ft in the normal direction of the rise travel section is Ft×cos α. Therefore, the cam driven member <NUM> has a tendency to slide in the tangential direction of the rise travel section <NUM> under the action of Ft×sin α. In this case, the cam driven member <NUM> is subjected to a friction force Fm opposite to the direction of Ft×sin α under the action of Ft×cos α, and the friction force Fm is used for preventing the cam driven member <NUM> from sliding in the tangential direction of the rise travel section. According to the mechanical knowledge, it can be learnt that: a magnitude of the friction force Fm is related to the friction coefficient µ between the cam driving member <NUM> and the cam driven member <NUM> (the friction coefficient µ herein integrates a system friction of an overall shafting structure used for implementing rotation of the body in the folding display phone) and a motion state of the cam driving member <NUM> and the cam driven member <NUM>. When the cam driven member <NUM> is at rest relative to the cam driving member <NUM>, the friction force Fm exists in the form of a static friction force with a magnitude equal to Ft×sin α and a direction opposite to Ft×sin α, but not greater than µ×Fn (that is, µ×Ft×cos α). When the cam driven member <NUM> slides relative to the cam driving member <NUM>, the friction force Fm exists in the form of a sliding friction force with a magnitude equal to µ×Ft×cos α and a direction opposite to the sliding direction of the cam driven member <NUM>.

Technicians hope that the existing folding display phone can have a freestop characteristic, that is, the body of the folding display phone under no external force can stay in the current position. According to the mechanical knowledge, it can be seen that: when Ft×sin α>µ×Ft×cos α, it means that a maximum static friction force between the cam driving member <NUM> and the cam driven member <NUM> in the rise travel section <NUM> is less than Ft×sin α, which is insufficient for the cam driven member <NUM> to reach force balance along the tangential direction of the rise travel section <NUM>, so that the cam driven member <NUM> and the cam driving member <NUM> slide relative to each other and cannot implement the freestop characteristic. When Ft×sin α≤µ×Ft×cos α, the maximum static friction between the cam driving member <NUM> and the cam driven member <NUM> in the rise travel section <NUM> is greater than or equal to Ft×sin α, which makes the cam driven member <NUM> reach the force balance along the tangential direction of the rise travel section <NUM>, so that the cam driving member <NUM> and the cam driven member <NUM> maintain a relatively static state to implement the freestop characteristic.

Based on the foregoing conditions for implementing the freestop characteristic, increasing the friction coefficient µ to make Ft×sinα≤µ×Ft×cosα is a feasible means for implementing the freestop characteristic. In the damping component, the friction coefficient µ is related to the quantity and size of springs: the more the springs, the larger the friction coefficient, and the less the springs; and the larger the spring size, the larger the friction coefficient, and the smaller the spring size, the smaller the friction coefficient. Therefore, the existing folding display phone generally implements the freestop characteristic by increasing the quantity of springs and the diameter of the springs to obtain a larger friction coefficient. However, with an increase of the quantity of springs and the size of the springs, the springs take up more space of the body, resulting in an increase of the overall thickness and weight of the folding display phone, which is not conducive to thinning of the body.

The embodiments of this application provide an improved foldable electronic device, which can implement the freestop characteristic while maintaining a thin body. The electronic device may, for example, be a folding display phone, a tablet computer, a laptop computer, an e-book reader, a wireless headset compartment, a wearable device (such as, virtual reality VR glasses, a smartwatch, a smartband, or a head-mounted display device), an electronic device connected to two or more parts in a hinge structure, or an electronic device in another product form. This is not specifically limited herein.

<FIG> is a schematic diagram of a partial structure of a foldable electronic device according to an embodiment of this application. As shown in <FIG>, the electronic device includes: a body <NUM>, a shaft cap <NUM>, a swing arm <NUM>, a first cam component <NUM>, a second cam component <NUM>, and an elastomer <NUM>. The first cam component <NUM> and the second cam component <NUM> may be cylindrical structures, arranged coaxially and side by side in the shaft cap <NUM>. The first cam component <NUM> may, for example, be a cam driving member, and the second cam component <NUM> may, for example, be a cam driven member. The first cam component <NUM> is configured to be fixed along a direction of a central shaft C1 of the first cam component <NUM>, but rotatable around the central shaft C1, and the first cam component <NUM> is connected to the body <NUM> on one side of the shaft cap <NUM> through the swing arm <NUM>. In this way, when a user applies a bending force to the body <NUM>, the body <NUM> can drive the swing arm <NUM> to rotate around the central shaft C1 of the first cam component <NUM>, so that the body <NUM> is unfolded or folded around the central shaft C1. The second cam component <NUM> is configured to be fixed in a direction perpendicular to the central shaft C1, but slidable along the direction of the central shaft C1. The elastomer <NUM> is connected to the second cam component <NUM>, and is configured to apply an elastic force Ft to the second cam component <NUM>. A direction of the elastic force Ft is parallel to the central shaft C1 and towards the first cam component <NUM>. In this way, the second cam component <NUM> can maintain pressure contact with the first cam component <NUM> along the direction of the central shaft C1 under the action of the elastic force Ft. When the first cam component <NUM> rotates around the central shaft C1, the first cam component <NUM> and the second cam component <NUM> slide relative to each other on a contact surface of the first cam component <NUM> and the second cam component <NUM>.

Further, as shown in <FIG>, the contact surface of the first cam component <NUM> and the second cam component <NUM> may include at least one cam surface <NUM> that matches with each other. The cam surface <NUM> includes a locking section <NUM> (a section with bold lines in <FIG>), and an angle α between a normal direction of the locking section <NUM> and the central shaft C1 is less than or equal to an arctan function of µ, that is, α≤arctan µ, where µ is a friction coefficient between the first cam component <NUM> and the second cam component <NUM>, and the friction coefficient integrates a system friction of an overall shafting structure used for implementing rotation of the body in the electronic device.

In this way, when the first cam component <NUM> comes into contact with the second cam component <NUM> in the locking section <NUM>, because α≤arctan µ, a component Ft×sin α of the elastic force Ft in a tangential direction of the locking section <NUM> and a component Ft×cos α in the normal direction can satisfy Ft×sin α≤µ×Ft×cos α, a maximum static friction force between the first cam component <NUM> and the second cam component <NUM> in the locking section <NUM> is greater than or equal to Ft×sin α, which makes the second cam component <NUM> reach force balance along the tangential direction of the locking section <NUM>, so that the first cam component <NUM> and the second cam component <NUM> can maintain a relatively static state to implement the freestop characteristic.

In this embodiment of this application, the elastomer <NUM> may be a component that can generate an elastic force by deformation, such as a spring or an elastic piece. When the elastomer <NUM> is implemented by using the spring, the spring is arranged on one end of the second cam component <NUM> opposite to the first cam component <NUM>, and is arranged coaxially with the second cam component <NUM>. One end of the spring is in contact with the second cam component <NUM>, and is configured in a compressed state along the direction of the central shaft C1. In this way, the spring can apply an elastic force Ft to the second cam component <NUM> along the direction of the central shaft C1, and the elastic force Ft is proportional to an amount of compression of the spring, that is, Ft=kx, where k is a stiffness coefficient of the spring and x is the amount of compression of the spring.

<FIG> is a schematic structural diagram of a contact surface according to an embodiment of this application. As shown in <FIG>, the first cam component <NUM> and the second cam component <NUM> may each include an annular end surface that matches with each other. For ease of description, herein, the annular end surface of the first cam component <NUM> is referred to as a first end surface <NUM> and the annular end surface of the second cam component <NUM> is referred to as a second end surface <NUM>. The first end surface <NUM> and the second end surface <NUM> may include an equal quantity of a plurality of cam surfaces <NUM> (represented by shadows of different depths in <FIG>), and the plurality of cam surfaces <NUM> are sequentially connected end to end and distributed in an annular array around the direction of the central shaft C1. When the first end surface <NUM> and the second end surface <NUM> include the equal quantity of the plurality of cam surfaces <NUM>, the plurality of cam surfaces <NUM> on the first end surface <NUM> may form pressure contact with the plurality of cam surfaces <NUM> on the second end surface <NUM> in a one-to-one correspondence. When the first cam component <NUM> rotates around the central shaft C1, the first cam component <NUM> and the second cam component <NUM> are relatively twisted around the central shaft C1, thereby generating relative sliding.

Further, as shown in <FIG>, in an implementation, the first end surface <NUM> and the second end surface <NUM> may each include three cam surfaces <NUM>, and an angle between two adjacent cam surfaces <NUM> is <NUM>°. In this way, a projection of each cam surface <NUM> along the direction of the central shaft C1 is an arc with a central angle of <NUM>°, each cam surface <NUM> forms one-third of the annular end surface, and the first end surface <NUM> and the second end surface <NUM> may uniformly form three pressure contacts around the central shaft C1, so that the forces on the first cam component <NUM> and the second cam component <NUM> along the direction of the central shaft C1 are relatively uniform, which improves the service life of the components.

<FIG> is a schematic structural diagram of a cam surface <NUM> according to an embodiment of this application.

<FIG> is a schematic diagram of a first cam component <NUM> and a second cam component <NUM> in contact with a locking section <NUM> according to an embodiment of this application.

In order to facilitate the description of a structure of the cam surface <NUM>, the cam surface <NUM> is expanded from the arc in <FIG>.

As shown in <FIG>, in an implementation, the cam surface <NUM> sequentially includes, along a sliding direction of the first cam component <NUM> or the second cam component <NUM>, a rise travel section <NUM> and a return travel section <NUM>. The rise travel section <NUM> refers to a section in which the second cam component <NUM> is far away from the first cam component <NUM> when the first cam component <NUM> slides relative to the second cam component <NUM>, and the rise travel section <NUM> has a rising angle along the sliding direction of the second cam component <NUM> relative to the first cam component <NUM>. The return travel section <NUM> refers to a section in which the second cam component <NUM> is brought close to the first cam component <NUM> when the first cam component <NUM> slides relative to the second cam component <NUM>, and the return travel section <NUM> has a falling angle along the sliding direction of the second cam component <NUM> relative to the first cam component <NUM>.

Compared with the cam surface shown in <FIG>, the cam surface <NUM> shown in <FIG> of the embodiments of this application includes only the rise travel section <NUM> and the return travel section <NUM>, but does not include the stop section, and the rise travel section <NUM> is directly connected to the return travel section <NUM>. For the cam surface <NUM> shown in <FIG>, it can be considered that, based on the cam surface <NUM> shown in <FIG>, the rise travel section <NUM> is extended to the region of the original stop section to replace the original stop section, thereby increasing the length of the rise travel section <NUM>. When a lifting height of the rise travel section <NUM> is unchanged, increasing the length of the rise travel section <NUM> is beneficial to making the slope of the rise travel section <NUM> smoother and reducing an angle α between the normal direction of the rise travel section <NUM> and the central shaft C1.

In the embodiments of this application, the locking section <NUM> (represented by a shadow in <FIG> and a solid line in <FIG>) may extend along the lifting direction of the rise travel section <NUM> from the middle and lower part of the rise travel section <NUM> all the way to a top of the rise travel section <NUM> and be connected to the return travel section <NUM> at the top of the rise travel section <NUM>. Compared with the structure shown in <FIG>, the locking section <NUM> covers most of the rise travel section <NUM> and all of the stop section <NUM>. In this way, when the body of the electronic device rotates from the fully unfolded state to the fully unfolded state, the first cam component <NUM> and the second cam component <NUM> can be in contact with the locking section <NUM> almost in the entire process.

Further, as shown in <FIG>, in an implementation, the locking section <NUM> includes a plurality of locking planes <NUM> along the lifting direction of the rise travel section <NUM>. Angles α between normal directions of different locking planes <NUM> and the central shaft C1 are different, but the angle α between the normal direction of any locking plane <NUM> and the central shaft C1 is less than or equal to arctan µ. In this way, with the rotation of the body to different positions, the first cam component <NUM> and the second cam component <NUM> can implement surface contact in different locking planes <NUM>. While the freestop characteristic is provided, a contact stress between the first cam component <NUM> and the second cam component <NUM> can be reduced through the surface contact, which improves the service life of the first cam component <NUM> and the second cam component <NUM>.

Further, as shown in <FIG>, in an implementation, angles α between normal direction of the plurality of locking planes <NUM> and the central shaft C1 decrease sequentially in the lifting direction of the rise travel section <NUM>. In this way, slopes of the rise travel section <NUM> can be gradually smooth in the lifting direction of the rise travel section <NUM>, and finally a smooth transition between the top of the rise travel section <NUM> and the return travel section <NUM> can be implemented. For example, if the locking section <NUM> sequentially includes, along the lifting direction of the rise travel section <NUM>, four locking planes 412a, 412b, 412c, and 412d, respectively corresponding to the angles α1, α2, α3, and α4, arctan µ>α1>α2>α3>α4≥<NUM>° is satisfied. Further, as shown in <FIG>, in an implementation, lengths of the plurality of locking planes <NUM> decrease sequentially in the lifting direction of the rise travel section <NUM>. In this way, with the slopes of the rise travel section <NUM> are gradually smooth in the lifting direction of the rise travel section <NUM>, the locking planes <NUM> is divided in more detail, so that the slope change at the top of the rise travel section <NUM> is smoother, which is beneficial to improving the hand feeling when a user rotates the body.

Further, as shown in <FIG>, in an implementation, two adjacent locking planes <NUM> are transitionally connected by a curved surface <NUM>. In this way, when the user rotates the body to cause the first cam component <NUM> and the second cam component <NUM> to slide relative to each other, the contact surface of the first cam component <NUM> and the second cam component <NUM> can smoothly transit between the locking planes <NUM>, thereby avoiding vibration when sliding between two adjacent locking planes <NUM>, which is beneficial to improving the hand feeling when the user rotates the body.

Further, as shown in <FIG>, in an implementation, the locking section <NUM> is connected to the return travel section <NUM> through a curved surface <NUM>. In this way, when the user rotates the body to cause the first cam component <NUM> and the second cam component <NUM> to slide relative to each other, the contact surface of the first cam component <NUM> and the second cam component <NUM> can smoothly transit between the locking section <NUM> and the return travel section <NUM>, thereby avoiding vibration when sliding between the locking section <NUM> and the return travel section <NUM>, which is beneficial to improving the hand feeling when the user rotates the body.

<FIG> is a force analysis diagram of a first cam component <NUM> and a second cam component <NUM> in contact with a locking section <NUM>.

As shown in <FIG>, when the first cam component <NUM> comes into contact with the second cam component <NUM> in the locking section <NUM>, on one hand, the second cam component <NUM> applies a pressure Fn, where Fn = Ft×cos α, to the first cam component <NUM> along the normal direction perpendicular to the locking section <NUM> at an elastic force Ft= k×x, the pressure Fn generates a component Fd1 in a rotation direction of the first cam component <NUM> (that is, the direction perpendicular to the rotation shaft C1), where Fd1= Fn×sin α= Ft×cos α×sin α, the component Fd1 causes the first cam component <NUM> to have a tendency to rotate to the right side in <FIG>; on the other hand, the first cam component <NUM> is also subjected to a friction force Fm on a contact surface between the first cam component <NUM> and the second cam component <NUM> under the action of the pressure Fn, a direction of the friction force Fm is parallel to the tangential direction of the locking section <NUM> for preventing the first cam component <NUM> from sliding along the tangential direction of the locking section <NUM>, and the friction force Fm generates a component Fd2, where Fd2=Fmxcos α, opposite to the direction of the component Fd1.

According to the mechanical knowledge, it can be learnt that: if the first cam component <NUM> is made to maintain at rest under no bending force of the user, that is, to implement the freestop characteristic, Fd1=Fd2, that is, Fn×sin α=Fm×cos α, where the friction force Fm is a static friction force with a maximum value of µ×Ft×cos α. Therefore, a condition that Fd1=Fd2 holds is that Ft×cos α×sin α≤µ×Ft×cos α×cos α, that is, tan α≤µ. That is,
when α≤arctan µ, a resultant force of the first cam component <NUM> in a rotation direction of the first cam component <NUM> is <NUM>, so that the body is not automatically unfolded or folded, thereby implementing the freestop characteristic;.

When α>arctan µ, Fd1>Fd2, and the resultant force of the first cam component <NUM> in the rotation direction of the first cam component <NUM> is greater than <NUM>. Therefore, the first cam component <NUM> rotates to cause the body to be automatically unfolded or folded without the freestop characteristic. In the embodiments of this application, θ=arctan µ is defined as a self-locking angle, and when µ ≈ <NUM>, θ ≈ <NUM>°.

<FIG> is a schematic diagram of distribution of cam surfaces on an annular end surface according to an embodiment of this application.

As shown in <FIG>, in an implementation, when the annular end surface includes a plurality of cam surfaces <NUM>, the locking section <NUM> may be arranged on at least one cam surface <NUM> of the annular end surface. Using the first end surface <NUM> as an example, when the first end surface includes a plurality of cam surfaces <NUM>, as shown in manner a in <FIG>, the locking section <NUM> may be arranged on a part of the cam surface <NUM>, and the locking section <NUM> is not arranged on the remaining cam surfaces <NUM>; and as shown in manner b in <FIG>, the locking section <NUM> may also be arranged on each cam surface <NUM>.

In addition, it may be understood that, for the folding display phone in the form shown in <FIG>, an angle by which the body on each side of the folding display phone rotates from a fully folded state to a fully unfolded state is <NUM>°. Based on this, as shown in <FIG>, in this embodiment of this application, preferably, an angle β by which each locking section <NUM> rotates around the central shaft C1 is greater than or equal to <NUM>°, or close to <NUM>°, for example, any angle between <NUM>° to <NUM>°. In this way, when the body is folded or unfolded, the first cam component and the second cam component can always or mostly be in contact with the locking section <NUM>, so that the body has the freestop characteristic in any position or most positions.

It can be learned from the above technical solutions that, in the electronic device provided in the embodiments of this application, the contact surface of the first cam component and the second cam component includes at least one cam surface that matches with each other. The cam surface includes a locking section, an angle between a normal direction of the locking section and the central shaft is less than or equal to an arctan function of µ, where µ is a friction coefficient between the first cam component and the second cam component, and a resultant force of a cam driving member in a rotation direction of the cam driving member is <NUM>, so that the body is not automatically unfolded or folded, thereby implementing the freestop characteristic.

It is easy to understand that a person skilled in the art may combine, split, recombine the embodiments of this application based on several embodiments provided in this application.

Claim 1:
A foldable electronic device, comprising:
a shaft cap (<NUM>), a body (<NUM>), a swing arm (<NUM>), a first cam component (<NUM>), a second cam component (<NUM>), and an elastomer (<NUM>), wherein
the first cam component (<NUM>) and the second cam component (<NUM>) are coaxially arranged in the shaft cap (<NUM>);
the first cam component (<NUM>) is connected to the body (<NUM>) through the swing arm (<NUM>) and is configured to be rotatable around a central shaft (C1) of the first cam component, so that the body (<NUM>) is folded or unfolded around the central shaft (C1) under the action of an external force;
the first cam component (<NUM>) comprises a first end surface (<NUM>) facing the second cam component (<NUM>), the second cam component (<NUM>) comprises a second end surface (<NUM>) facing the first cam component (<NUM>), and the first end surface (<NUM>) and the second end surface (<NUM>) each comprise at least one cam surface (<NUM>);
the second cam component (<NUM>) is configured to be slidable along a direction of the central shaft (C1);
the elastomer (<NUM>) is connected to the second cam component (<NUM>) and is configured to apply an elastic force to the second cam component (<NUM>), so that the first end surface (<NUM>) of the first cam component (<NUM>) maintains in contact with the second end surface (<NUM>) of the second cam component (<NUM>) under the action of the elastic force; and
in a case that the body (<NUM>) is unfolded or folded to a position between fully unfolded and fully folded, the first cam component (<NUM>) and the second cam component (<NUM>) are in contact with a locking section (<NUM>) of the cam surface (<NUM>), and an angle between a normal direction of the locking section (<NUM>) and the central shaft (C1) is less than or equal to arctan µ, wherein µ is a friction coefficient between the first cam component (<NUM>) and the second cam component (<NUM>), wherein
the cam surface (<NUM>) comprises a rise travel section (<NUM>) and a return travel section (<NUM>), and the locking section (<NUM>) is a part of the rise travel section (<NUM>);
characterised in that
the locking section (<NUM>) comprises a plurality of locking planes (<NUM>) along a lifting direction of the rise travel section (<NUM>), and an angle between a normal direction of any of the plurality of locking planes (<NUM>) and the central shaft (C1) is less than or equal to arctan µ.