Mobile phone keyboard

Abstract

The utility model provides a mobile phone keyboard which is suitable for a touch control type intelligent mobile phone and comprises a keyboard and a connecting piece, the keyboard is configured to be in wireless connection with the intelligent mobile phone and input data to the intelligent mobile phone, the connecting piece comprises a base, the base is configured to be detachably attached to the back of the intelligent mobile phone, and the connecting piece is connected with the base. The base is provided with an adjusting arm capable of moving telescopically, the adjusting arm is provided with an extending end relatively far away from the base, and the keyboard is rotatably connected to the extending end. Wireless data transmission is carried out between the mobile phone keyboard and the mobile phone, the mobile phone keyboard can be attracted to the back face of the mobile phone through the magnet, and the keyboard function area can be stored and hidden to the back face of the mobile phone in a telescopic mode.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of mobile phone accessory equipment, and specifically relates to a mobile phone keyboard suitable for touch control smart phones. BACKGROUND

[0002] With the popularity of smart phones, full touch screen mobile phones have become mainstream, but for users who are used to using physical keyboards for input, full touch screen mobile phones have many inconveniences when a large amount of text input is performed, such as slow input speed and easy errors.

[0003] To solve this problem, the industry has developed independent mobile phone keyboards in the past. Existing mobile phone keyboards suitable for early mobile phones are disclosed in US Patent No. 8155713 and US Patent Application Publication Nos. US20070178852A1 and US20060066740A1. Such keyboards provide a relatively convenient input method as an independent individual, but they need to be equipped with special storage accessories when they are stored and carried, which is not conducive to portable travel. Some mobile phone keyboards are integrated with mobile phone cases and achieve data communication with the mobile phone through direct physical connection.

[0004] However, the above designs have the following inconveniences: the addition of a mobile phone keyboard will inevitably affect the size of the mobile phone when it is used, and text input is not required at all times when the mobile phone is used. Therefore, the above mobile phone keyboard is very inconvenient when switching between use, carrying, and storage scenarios, which affects the user experience. INVENTION CONTENTS

[0005] The utility model relates to a mobile phone keyboard suitable for touch control smart phones, comprising:

[0006] a base configured to be detachably attached to the back of the smart phone; and

[0007] a keyboard configured to be wirelessly connected to the smart phone and input data to the smart phone; and

[0008] an adjustment arm provided on the base for connecting the base and the keyboard;

[0009] When the base is attached to the smart phone, the keyboard can adjust the spatial position relative to the smart phone through the adjustment arm.

[0010] Preferably, the base is provided with an attachment surface connected to the smart phone, and the attachment surface is provided with a first magnetic attraction element. The base is magnetically attracted to the back of the smart phone through the first magnetic attraction element.

[0011] Preferably, the keyboard comprises a mounting block and a keyboard body shell. Keys are provided on the keyboard body shell. The mounting block is connected to the adjustment arm, and the keyboard body shell is detachably connected to the mounting block.

[0012] Preferably, a slot is formed on the keyboard body shell for inserting the mounting block, and a releasable locking mechanism is arranged on the keyboard body shell, which is used to lock the mounting block after the mounting block is inserted into the slot, and the mounting block is detachably connected to the keyboard body shell through the locking mechanism.

[0013] Preferably, a buckle slot is formed on the mounting block, and a mounting port is formed on the outer surface of the keyboard body shell and communicates with the slot, the mounting port is arranged corresponding to the position of the buckle slot when the mounting block is inserted into the slot, and the locking mechanism comprises a button arranged in the mounting port, a spring member for resetting the button after being pressed, and a buckle body arranged on the button, after the mounting block is inserted into the slot, the buckle body is buckled into the buckle slot to prevent the mounting block from being separated.

[0014] Preferably, the mounting block is rotatably connected to the adjusting arm through a hinge shaft, and the mounting block rotates around the hinge shaft to adjust the angle relative to the base.

[0015] Preferably, the base is provided with a first track, the adjusting arm comprises a first arm portion and a second arm portion, the first arm portion is slidingly arranged on the first track, the first arm portion is provided with a second track, the second arm portion is slidingly arranged on the second track, and the keyboard is rotatably connected to one end of the second arm portion away from the base, and the one end of the second arm portion away from the base constitutes an extending end.

[0016] Preferably, the first arm portion and the second arm portion are both plate-shaped, the first track comprises a first guide block arranged on the base, the first guide block is arranged along the surface of the base to define the extension direction of the first arm portion, the first arm portion is provided with a first guide slot slidingly connected with the first guide block, and the second track comprises a second guide block arranged on the first arm portion, the second guide block is arranged along the extension direction to define the extension direction of the second arm portion, and the second arm portion is provided with a second guide slot slidingly connected with the second guide block.

[0017] The second guide block comprises a guide column and a sliding table arranged on the first arm portion, the sliding table is provided with guide rails on both sides, the second arm portion is provided with a pin slot matched with the guide column and a sliding slot matched with the guide rails on both sides of the sliding table, and the pin slot and the sliding slot jointly constitute the second guide slot.

[0018] Preferably, a cavity capable of accommodating the adjusting arm and an opening communicating with the cavity are formed in the base, the first track is arranged in the cavity and extends towards the opening, and the adjusting arm is arranged in the cavity and extends out or retracts from the opening.

[0019] Preferably, the base is provided with a second magnetic member, the second magnetic member is arranged in the cavity near the opening position, the first arm is provided with a third magnetic member, the second magnetic member and the third magnetic member are attracted to each other when the first arm is stretched out to keep the length of the first arm stretched out relative to the base, the first arm is provided with at least one fourth magnetic member, the second arm is provided with a fifth magnetic member, the fifth magnetic member and the fourth magnetic member are attracted to each other when the second arm is stretched out to keep the length of the second arm stretched out relative to the first arm.

[0020] Compared with the prior art, the utility model has the beneficial effects that:

[0021] The mobile phone keyboard and the mobile phone perform wireless data transmission, the keyboard can be adsorbed on the back of the mobile phone, and the keyboard can be hidden in the back of the mobile phone through the movable base, and the adjusting arm has sufficient movement stroke to meet the different distances of the keyboard moving to the base, and more preferably, the keyboard can be adjusted in the angle of use by rotating relative to the adjusting arm to meet the use requirement of the user. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification provide further understanding of the utility model, the schematic embodiment of the utility model and the explanation thereof are used to explain the utility model, and do not constitute improper limitation to the utility model. In the drawings:

[0023] Figure 1 The structure schematic view of the embodiment of the mobile phone keyboard according to the utility model is shown;

[0024] Figure 2 Another view structure schematic view of the mobile phone keyboard in Figure 1 is shown;

[0025] Figure 3 The internal structure schematic view of the base in Figure 1 is shown;

[0026] Figure 4 The structure schematic view of the adjusting arm in Figure 1 is shown;

[0027] Figure 5 Another view structure schematic view of the adjusting arm in Figure 4 is shown;

[0028] Figure 6 The structure schematic view of the mounting block in Figure 1 is shown;

[0029] Figure 7 Another view structure schematic view of the mounting block in Figure 6 is shown;

[0030] Figure 8The internal structure of the keyboard in Figure 1 is shown.

[0031] Wherein, the above drawings include the following reference signs:

[0032] Keyboard (1); base (2); adjusting arm (3); button (11); mounting block (12); keyboard body shell (13); power switch (14); charging interface (15); buckle groove (121); slot (131); button (132); spring piece (133); buckle body (134); attachment surface (21); cavity (22); opening (23); first guide block (24); first arm (31); second arm (32); hinge shaft (33); first guide groove (311); guide column (312); sliding table (313); pin groove (321); sliding groove (322); first magnetic attraction piece (41); second magnetic attraction piece (42); third magnetic attraction piece (43); fourth magnetic attraction piece (44); fifth magnetic attraction piece (45). DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0034] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0035] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless otherwise specifically indicated. At the same time, it should be understood that the sizes of the various parts shown in the drawings are not drawn in accordance with the actual proportional relationship for the convenience of description. The technology, methods and equipment known to those skilled in the related art can not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as part of the authorized description. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0036] As Figure 1 , Figure 4 and Figure 5 The utility model provides a mobile phone keyboard, be applicable to touch -control intelligent mobile phone, including keyboard 1 and connecting piece, wherein keyboard 1 is configured to be wirelessly connected with intelligent mobile phone and input data to intelligent mobile phone, connecting piece includes base 2, wherein base 2 is configured to be detachably attached to the back of intelligent mobile phone, when base 2 is attached to intelligent mobile phone, keyboard 1 can be adjusted the spatial position relative to intelligent mobile phone through adjusting arm 3.

[0037] The intelligent mobile phone can be a general term of mobile phone type with independent operating system, independent running space, can be installed by user software, game, navigation and third party service provider provided equipment, and can realize wireless network access through mobile communication network.

[0038] Adjusting arm 3 with the extension end away from base 2 is arranged on base 2, and keyboard 1 is rotatably connected to the extension end. Wireless data transmission between mobile phone keyboard and mobile phone is used, the mobile phone keyboard can be adsorbed on the back of the mobile phone by magnet, and the function area of keyboard 1 can expose the keys by telescopic mode, and adjusting arm 3 has enough telescopic stroke to meet keyboard 1 moving to different distances relative to base 2, and keyboard 1 rotates relative to adjusting arm 3 to adjust the angle during use to meet the use demand of user.

[0039] As Figure 1 and Figure 2As shown, the base 2 is provided with an attachment surface 21 connected with the smart phone, the attachment surface 21 is provided with a first magnetic member 41, and the base 2 is magnetically attracted to the back of the smart phone through the first magnetic member 41. The problem of the inconvenience of the integrated design of the phone keyboard and the phone shell in the prior art is solved, the phone keyboard of the utility model can be magnetically attracted to the back of the phone, is not limited by the phone shell, and will not increase the overall size of the phone. In some embodiments (not shown in the figure), the base 2 and the smart phone can be connected through a quick release structure formed by components such as adhesive, magic tape, fastener and suction cup, etc. which are convenient and quick to assemble and disassemble. In addition, the base 2 and the smart phone can also be connected indirectly, and the base 2 can be connected to the phone shell or the phone cover on the smart phone. This connection can also be achieved through the quick release structure mentioned above.

[0040] It should be further pointed out that the magnetic base 2 of the present embodiment is mainly suitable for smart phones with internal magnetic blocks. Of course, this magnetic base 2 is also suitable for other phones with internal magnetic blocks or magnetic metal blocks. For phones without internal magnetic blocks or magnetic metal blocks, external magnetic blocks or external magnetic metal blocks can be fixed on the phone through pasting, covering and other methods, and then used with the magnetic base 2. Obviously, the magnetic metal block is a metal block that can be attracted by a magnet.

[0041] As shown in Figures 3 to 5 The base 2 is provided with a cavity 22 capable of accommodating the adjusting arm 3 and an opening 23 communicating with the cavity 22, the first track is arranged in the cavity 22 and extends to the opening 23, and the adjusting arm 3 is arranged in the cavity 22 and extends out or retracts from the opening 23. The adjusting arm 3 can be accommodated in the cavity 22 of the base 2 through telescopic movement, so that in the fully retracted state of the adjusting arm 3, the keyboard 1 can be accommodated in abutment with the base 2, reducing the overall size in the accommodated state. The above-mentioned cavity 22 can be relatively open, or it can be closed as in the present embodiment, that is, the base 2 can have more than one opening 23 communicating with the cavity 22. This facilitates the switching of the phone keyboard between use and storage scenarios, and also provides a component for accommodating the keyboard 1.

[0042] As shown in Figures 3 to 5 The base 2 is provided with a first track, and the adjusting arm 3 is slidingly arranged on the first track. The adjusting arm 3 includes a first arm portion 31 and a second arm portion 32, the first arm portion 31 is slidingly arranged on the first track, the first arm portion 31 is provided with a second track, the second arm portion 32 is slidingly arranged on the second track, and the keyboard 1 is rotatably connected to one end of the second arm portion 32 away from the base 2, and the one end of the second arm portion 32 away from the base 2 constitutes the extending end.

[0043] As shown in Figures 3 to 5As shown, the first arm portion 31 and the second arm portion 32 are both plate-shaped, the first track includes a first guide block 24 arranged on the base 2, the first guide block 24 is arranged along the surface of the base 2 to define the extension direction of the first arm portion 31, and a first guide groove 311 is arranged on the first arm portion 31 to slide with the first guide block 24, the second track includes a second guide block arranged on the first arm portion 31, the second guide block is arranged along the extension direction to define the extension direction of the second arm portion 32, and a second guide groove is arranged on the second arm portion 32 to slide with the second guide block. The second guide block includes a guide column 312 and a sliding table 313 arranged on the first arm portion 31, the sliding table 313 is provided with guide rails on both sides, and the bottom of the second arm portion 32 is provided with a pin groove 321 matched with the guide column 312 and a sliding groove 322 matched with the guide rails on both sides of the sliding table 313.

[0044] The extension and retraction of the adjustment arm 3 described above is mainly realized by the track sliding mode, and the extension and retraction is mainly to realize the linear movement of the keyboard 1 connected with the adjustment arm 3 relative to the base 2, so as to adjust the distance between the keyboard 1 and the base 2. Therefore, in some embodiments (not shown in the figure), the extension and retraction can also be realized by setting the adjustment arm 3 in a connection mode such as sleeve type extension and retraction, rack type extension, and hinged fork, etc.

[0045] In some embodiments (not shown in the figure), the adjustment arm 3 can be designed to rotate relative to the base 2. More preferably, one end of the adjustment arm 3 is rotationally connected with the base 2, and the other end is rotationally connected with the keyboard 1, so as to form a structure similar to a three-section rotating support, and further, each section can also be designed to be extendable, so as to increase the activity range and provide more flexible adjustment function.

[0046] On the basis that the adjustment arm 3 can be designed to rotate relative to the base 2, the adjustment arm 3 can also slide relative to the base 2. The implementation is that one end of the adjustment arm 3 is provided with a rotating shaft for sliding connection with the base 2, and the adjustment arm 3 slides relative to the base 2 through the rotating shaft. After sliding to a suitable position, the adjustment arm 3 is rotated around the rotating shaft to a suitable angle, so as to realize more accurate adjustment. Similarly, similar structures can also be arranged between the first arm portion 31 and the second arm portion 32, so as to realize the sliding and rotation of the adjustment arm 3 relative to the base 2.

[0047] As Figures 3 to 5As shown, the adjusting arm 3 has a magnetic locking function with the base 2, and the magnetic locking is used to keep the telescopic length of the adjusting arm 3, which is equivalent to maintaining the keyboard 1 at a required distance relative to the base 2. The base 2 is provided with a second magnetic member 42, and the second magnetic member is arranged in the cavity 22 close to the opening 23. The first arm 31 is provided with a third magnetic member 43, and the second magnetic member 42 and the third magnetic member 43 are attracted to each other when the first arm 31 is extended to keep the length of the first arm 31 extended relative to the base 2. The first arm 31 is provided with at least one fourth magnetic member 44, and the second arm 32 is provided with a fifth magnetic member 45. The fifth magnetic member 45 and the fourth magnetic member 44 are attracted to each other when the second arm 32 is extended to keep the length of the second arm 32 extended relative to the first arm 31.

[0048] In addition to the magnetic locking function, the adjusting arm 3 has other locking modes: a sliding connection with damping is arranged between the adjusting arm 3 and the base 2, and an elastic pin is arranged between the adjusting arm 3 and the base 2.

[0049] As shown in Figures 6 to 8 The keyboard 1 includes a mounting block 12 rotatably connected with the adjusting arm 3 and a keyboard body shell 13 detachably connected with the mounting block 12. The mounting block 12 is rotatably connected with the adjusting arm 3 through a hinge shaft 33, so that the keyboard 1 is rotatably connected with the adjusting arm 3, and the mounting block 12 rotates around the hinge shaft 33 to adjust the angle relative to the base 2. In this embodiment, a slot is arranged on the end of the second arm 32 to accommodate the hinge shaft 33.

[0050] The keyboard body shell 13 is provided with a slot 131 for inserting the mounting block 12, and is also provided with a releasable locking mechanism for locking the mounting block 12 after the mounting block 12 is inserted into the slot 131. The mounting block 12 is detachably connected to the keyboard body shell 13 through the locking mechanism.

[0051] As shown in Figure 8As shown, the mounting block 12 is provided with a buckle groove 121, and the outer surface of the keyboard body shell 13 is provided with a mounting port in communication with the insertion groove 131, the buckle groove 121 is arranged at the position corresponding to the insertion of the mounting block 12 into the insertion groove 131, the locking mechanism comprises a button 11 arranged in the mounting port, a spring member for restoring the button 11 after being pressed, and a buckle body 134 arranged on the button 11, after the mounting block 12 is inserted into the insertion groove 131, the buckle body 134 is buckled into the buckle groove 121 to prevent the mounting block 12 from being separated, and the locking of the mounting block 12 after being inserted is generally realized by arranging the elastic pin. The above-mentioned locking mechanism can also be realized by a magnetic locking mechanism, magnets are embedded in the mounting block 12 and the insertion groove 131, and the fixing of the mounting block 12 is realized by magnetic force adsorption; the locking mechanism is realized by rotating, threaded structures are designed on the mounting block 12 and the insertion groove 131, and the mounting block 12 is tightly combined with the insertion groove 131 by rotating the mounting block 12. This way can provide stronger locking force and is easy to operate; the locking mechanism is realized by a buckle type, buckle structures are designed on the mounting block 12 and the insertion groove 131, and the fixing of the mounting block 12 is realized by the elastic deformation of the buckle. This way is easy to operate and is suitable for frequently disassembled occasions.

[0052] The wireless module in the keyboard 1 establishes a wireless connection with the smart phone through a wireless local area network (WLAN), Zigbee (IEEE 802.15.4), Bluetooth, infrared communication, worldwide interoperability for microwave access (WiMAX), global system for mobile communication (GSM), general packet radio service (GPRS), third generation (3G), or actor network theory + (Ant+) technology, and realizes the input of information such as text into the smart phone. The wireless data transmission between the keyboard and the smart phone of the present application improves the flexibility.

[0053] The keyboard 1 is provided with a rechargeable power supply, and the keyboard 1 is provided with a corresponding power switch 14 and a charging interface 15. The keyboard 1 has a text input keypad, which is equivalent to the commonly used 26-key form, and is shown as a Roman alphabet typewriter or computer keyboard (commonly known as "QWERTY") configuration.

[0054] In the description of the present application, it should be understood that the orientation words such as "front, rear, upper, lower, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicate the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and in the absence of the opposite description, these orientation words do not indicate and imply that the indicated device or element must have a specific orientation or be constructed and operated in a specific orientation, therefore it cannot be understood as a limitation on the protection scope of the present application; the orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0055] For purposes of the description hereinafter, spatial relative terms, such as "above", "below", "upper", "lower", and the like, can be used to describe the relative position of one element or feature to another as illustrated in the figures. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0056] In addition, it should be noted that the use of "first", "second", and the like words of resemblance to define parts, only for the convenience of the corresponding parts are distinguished, such as no other declaration, the above words have no special meaning, therefore can not be understood as the restriction of the scope of protection of the utility model.

[0057] The above only is the preferred embodiment of the utility model, and does not limit the utility model, and for the person skilled in the art, the utility model can have various changes and changes. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A mobile phone keyboard suitable for touch screen smart phone, characterized in that, The application relates to a keyboard device for a smart phone, which comprises a base configured to be detachably attached to the back of the smart phone, a keyboard configured to be wirelessly connected to the smart phone and input data to the smart phone, and an adjusting arm arranged on the base and used for connecting the base and the keyboard. The base is attached to the smart phone, and the keyboard can be adjusted in spatial position relative to the smart phone through the adjusting arm. The base is provided with an attachment surface connected to the smart phone, and a first magnetic suction element is arranged in the attachment surface. The keyboard comprises a mounting block and a keyboard body shell, keys are arranged on the keyboard body shell, the mounting block is connected to the adjusting arm, and the keyboard body shell is detachably connected to the mounting block. A locking mechanism is arranged on the keyboard body shell and used for locking the mounting block after the mounting block is inserted into the slot. The mounting block is detachably connected to the keyboard body shell through the locking mechanism. A buckle groove is arranged on the mounting block, and a mounting hole is arranged on the outer surface of the keyboard body shell and communicates with the slot.

2. The cell phone keyboard of claim 1, wherein: The locking mechanism comprises a button arranged in the mounting hole, a spring element used for restoring the button after the button is pressed, and a buckle body arranged on the button.

3. The cell phone keyboard of claim 1, wherein: The mounting block is rotatably connected to the adjusting arm through a hinge shaft, and the mounting block rotates around the hinge shaft to adjust the angle relative to the base.

4. A cell phone keypad according to claim 3, wherein: The base is provided with a first track, the adjusting arm comprises a first arm part and a second arm part, the first arm part is slidingly arranged on the first track, the first arm part is provided with a second track, the second arm part is slidingly arranged on the second track, the keyboard is rotatably connected to one end of the second arm part away from the base, and the one end of the second arm part away from the base forms an extending end.

5. A cell phone keypad according to claim 4, wherein: The first arm part and the second arm part are both plate-shaped, the first track comprises a first guide block arranged on the base, the first guide block extends along the surface of the base to limit the extension direction of the first arm part, a first guide groove is arranged on the first arm part and slidingly connected to the first guide block, the second track comprises a second guide block arranged on the first arm part, the second guide block extends along the extension direction to limit the extension direction of the second arm part, and a second guide groove is arranged on the second arm part and slidingly connected to the second guide block.

6. The cell phone keyboard of claim 3, wherein: The second guide block comprises a guide column and a sliding table arranged on the first arm part, guide rails are arranged on the two sides of the sliding table, the second guide groove comprises a pin groove matched with the guide column and a sliding groove matched with the guide rails on the two sides of the sliding table, and the pin groove and the sliding groove jointly form the second guide groove.

7. A mobile phone keyboard according to any one of claims 1-6, characterized in that: A cavity capable of accommodating the adjusting arm is arranged in the base, and an opening communicating with the cavity is arranged in the base, the first track is arranged in the cavity and extends to the opening, and the adjusting arm is arranged in the cavity and extends out of or retracts from the opening.

8. A cell phone keypad according to claim 7, wherein: ​ ​ 9. The cell phone keyboard of claim 7, wherein: ​ 10. A cell phone keypad according to claim 9, wherein: The base is provided with a second magnetic member, the second magnetic member is arranged in the cavity near the opening position, the first arm is provided with a third magnetic member, the second magnetic member and the third magnetic member are mutually adsorbed when the first arm is stretched out to keep the length of the first arm stretched out relative to the base, the first arm is provided with at least one fourth magnetic member, the second arm is provided with a fifth magnetic member, the fifth magnetic member and the fourth magnetic member are mutually adsorbed when the second arm is stretched out to keep the length of the second arm stretched out relative to the first arm.

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