BACKGROUND OF THE INVENTION

1. Field of the Invention

The current invention is generally related to modular devices, and particularly modular devices requiring radio frequency connectors for radio frequency connections between modules of the device.

2. Description of Related Art

Different types of modular computing devices have been presented, each with their own benefits and drawbacks. Despite that many different designs have been brought to market, modular computing devices are not common at the time of writing of this specification. There are many practical difficulties with modular designs. Insertion and removal of a module in many designs requires precision, which makes such a design not very suited for everyday use by laypersons. Mechanical durability is another difficult area. It is difficult to create a modular structure where a module is easy to insert and remove, while being sturdy enough for everyday use.

One important reason for need for precision in insertion of a module is electrical connectors. Modem devices may need connectors with a large number of digital signal lines, as well as radio frequency connectors. Most connector types require accurate, strictly one-directional movement for making the connection. A good example of connectors which require accurate one-directional movements are common coaxial radio frequency connectors used for antenna connections in wireless devices.

Coaxial radio frequency (RF) connectors typically consist of a cylindrical plug with a correspondingly shaped socket. The plug typically has a center contact for carrying the RF signal, and a cylindrical shield contact surrounding the center contact.

There are miniature coaxial connectors that have been developed for use between printed circuit boards. Current miniature coaxial connectors have substantial thickness because they use cylindrical plug-in connectors that slide inside each other. Although there are rather small versions of such connectors available, they still are of substantial thickness, and they require accurate alignment of the connector halves. Further, such cylindrical coaxial connectors do not allow any sideways movement during insertion.

The patent US7221960 describes an arrangement, where a coaxial RF connection is formed using an array of pogo pins. This structure has the advantage that it is tolerant of small sideways movements during insertion into place, and is not as strict with alignment as a connector with a cylindrical plug and socket. However, the pogo pin array structure does not have a very good RF performance, as the shield which is formed by a small number of pogo pins, does not form a tight enough shield due to the distance between the pogo pins. Also a pogo pin array compromises the critical relationship between the centre contact diameter and the shield internal diameter which effects and is used to set the impedance of the coaxial structure, as known by a man skilled in the art.

SUMMARY OF THE INVENTION

The invention provides a module structure that allows for easy insertion and removal of a module from a base unit of a modular device. The module structure does not require high precision from the user in the insertion of a module, as the structure guides the movement of the module during insertion, whereby the placement of the module is accurate even if the user does not insert the module perfectly.

In an embodiment of the invention, a module has a notch at an end of each of two opposing sides, which notches mate with two pins in a slot into which the module is to be placed. This pin-and-notch structure allows the module to rotate around the pins. The module also has a notch on each of the same two sides, that mate with corresponding ridges in the slot, guiding the module towards the correct end position, when the module is rotated towards the slot and the final position. This structure will be described in more detail later in this specification.

An embodiment of the invention a module comprises a low profile coaxial connector structure which is simple in structure and economical to manufacture, which yet provides a good connection with low leakage to contact pads on a printed circuit board surface or other structure offering face-to-face pad contacts. The structure comprises a central contact in the form of a sprung pin, such as a so- called pogo pin, inserted into a backing surface such as a printed circuit board or another contact pad carrier having contact pads, and being in contact with an electrical conductor on the surface. The shield connection is formed with a shield ring, which is biased using a ring spring. The ring spring is in electrical contact with a contact pad on the surface, and the shield ring is in electrical contact with the ring spring. The ring spring can be for example a wavy washer i.e. a metallic ring pressed into a wavy shape. The ring spring, shield ring and shield ring contact face need to be wide enough to act as a choke to any RF signals escaping through spaces left by the wavy shape between the ring spring and the shield ring, as well as those between the ring spring and the contact pad on the surface of the printed circuit board or another contact pad carrier. Other shapes for a ring spring that provide a wide enough contact area can also be used in other embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention will be described in detail below, by way of example only, with reference to the accompanying drawings, of which figures 1A and 1B illustrate a section view of a structure according to an embodiment of the invention, figure 2 illustrates a computing device with an inventive connector structure, and figure 3 illustrates a base unit of a computing device.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s), this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Features of different embodiments may be combined to provide further embodiments. In the following, features of the invention will be described with simple examples of module structures with which various embodiments of the invention may be implemented. Only elements relevant for illustrating the embodiments are described in detail. Details that are generally known to a person skilled in the art may not be specifically described herein.

Figures 1A and 1B illustrate a connector structure according to an embodiment of the invention. Figure 1A shows a cross section of a structure comprising a backing surface in the form of the surface of a first printed circuit board (PCB) 110, contact pads 112 on the PCB 110, a pogo pin 120, a ring spring 130, a shield ring 140, and a retaining member 150.

Figure 1B illustrates a situation in which this structure mates with a mating PCB 160 by contacting with contact pads 162 on the mating PCB 160. The inventive structure can also mate with contact pads on other surfaces as PCB surfaces as well.

In the embodiment illustrated in figures 1A and IB, the pogo pin 120 is soldered to a central contact pad 112 on the first PCB 110. In this embodiment of the invention the body of the pogo pin passes through the PCB. It is conceivable that in other embodiments of the invention, the pogo pin does not pass through the first printed circuit board, but is merely soldered to one side of the PCB.

The contact pads 112 are connected to other circuits on the PCB for connection to radio transmission and receiving functions, which are for clarity not shown in figures 1A and 1B.

In various embodiments of the invention, the backing surface may be a surface of another part or component other than a PCB.

Pogo pins, i.e. contact pins with internal spring action, are well known to a man skilled in the art, whereby they are not described in any further detail in this specification. The ring spring 130 pushes the shield ring 140 towards the mating contact pads 162, and connects the shield ring 140 electrically to contact pads 112 on the first circuit board 110. The ring spring 130 has a greater width than thickness, i.e. the difference between the outer radius and the inner radius of the ring spring is greater than the thickness of the ring spring. The width is needed to choke the RF signal from leaking through any possible gaps between the ring spring and the contact pads on the first printed circuit board, and through any possible gaps between the ring spring and the shield ring.

The ring spring 130 can be implemented for example as a wavy washer 130 or a wavy spring 130. A wavy washer is a known type of circular washers, shaped into a number of waves around its perimeter. A wavy washer cannot in practice be designed and manufactured to compress completely flat due to manufacturing tolerances, whereby small gaps will remain between the wavy washer and the PCB, as well as wavy washer and the shield ring. The width of the ring of the wavy washer 130, i.e. the difference between the inner and outer radius of the wavy washer 130, needs to be large enough to choke any signal from leaking through these gaps. Naturally, the width needed for choking any such leaking signals is dependent on signal frequency and the size of the gaps, and is therefore implementation dependent.

The wavy washer is only an example of a form of the ring spring according to an embodiment of the invention. The ring spring can be implemented using also a different forms of a springy washer, such as a serrated washer, finger spring washer, or a belleville washer, as long as the washer provides a spring action, and is wide enough to quash any signals from leaking through any gaps between contacting surfaces.

The material of the ring spring can advantageously be copper, copper alloy, or for example copper or copper alloy with a metal plating. For example, in an embodiment of the invention, the ring spring is manufactured of beryllium copper. However, the invention is not limited to any specific material for the ring spring, as a man skilled in the art can select its material from many different suitable materials.

The shield ring 140 provides a contact area for mating with a contact pad on a mating PCB or other surface. Similarly to the ring spring, the shield ring is advantageously wide enough to quash any RF signal from leaking through any gaps between the shield ring and the ring spring, as well as through any gaps between the shield ring and the mating contact pads on the mating surface. A further benefit of a wide ring is that it less easily catches on the edges of contact pads on the mating surface, if the connector structure is brought into contact with the mating surface in a sliding fashion.

The shield ring can be for example turned brass with metal plating. The material of the shield ring is mainly implementation dependent, chosen on the basis of desired cost and quality by a man skilled in the art. Therefore the invention is not limited to any specific material or material combination for the shield ring.

The inner diameter of the shield ring and the ring spring and the outer diameter of the signal carrying pogo pin determine the impedance of the connector, similarly as with a coaxial conductor, as known by a man skilled in the art. The inventive structure has the benefit that the structure has a very low profile while simultaneously allowing the structure to be wide enough to accommodate any desired impedance of the structure.

The retaining member 150 holds the ring spring and the shield ring in place. In the example shown in figure 1, the retaining member is a component of a stand-alone connector structure. In a further embodiment of the invention, the retaining member is part of the outer casing of the device comprising the inventive structure.

In an embodiment of the invention the structure also comprises an infill member between the pogo pin and the shield ring. Figure 1 shows an infill member 170 surrounding the central pogo pin 120 and extending to the inner surfaces of the ring spring 130 and the shield ring 140. As is well understood by a man skilled in the art of coaxial design, the infill can preferably be made of a material that is close to the same magnetic permeability m/mq and electric permittivity e/eq of air, so is typically but not exclusively constructed of nylon, PTFE or Teflon. The infill member can be fastened to the structure in many different ways known to a man skilled in the art. In the example of figure 1, the infill member is heatstaked to the first printed circuit board 110. By filling the space between the pogo pin and the interior surfaces of the ring spring and shield ring, the infill member has the benefit that the surface of the connector structure is smoother than without without the infill. The infill also provides mechanical support for the ring spring and the shield ring.

Figure 2 illustrates a module 210 of a communication device. The module comprises radio transmitter and receiver circuits which are connected to the connector structure 220. In an embodiment of the invention, the module 210 comprises also a processor unit and memory such as random access memory (RAM). The module 210 can advantageously be a processor module of a communication device. The communication device can be a modular smartphone, or for example a router device. Figure 2 also illustrates an example of an embodiment, in which the outer casing of the device where the connector structure is implemented, forms the retaining member of the structure, allowing the shield ring and the pogo pin to be raised above the surface of the outer casing.

Figure 2 also schematically illustrates a connector 222 for a plurality of digital signals.

Further, figure 2 also illustrates the structural features in the module 210 providing easy insertion into a slot of a base unit of a computing device. Figure 2 illustrates notches 240 at the ends of two opposing side faces 211 that match with corresponding pins in the slot, into which the user inserts the module. This notch- and-pin arrangement allows rotational movement of the module towards the slot. Close to the end of the rotational movement, second notches 250 engage with ridges in the slot, which guide the module into the final, accurate position.

Figure 3 illustrates a base unit 310 of a computing device. Figure 3 is an example, in which the base unit is a base unit of a mobile communication device. Figure 3 shows the base unit showing the face with two module slots 320. Figure 3 also shows pins 350 that mate with the notches 240 of a module 210. Ridges 360 mate with corresponding notches 250 of a module 210.

The two slots 320 of the base unit 310 can receive two different modules. In the example of figure 3, the base unit comprises at least a display. The display is not illustrated in figure 3, as in this example it is located on the face not visible in figure 3. The two modules in this example are a processor module 210 as illustrated in figure 2, and a battery module comprising at least a rechargeable battery. The base unit 310 combined with these two modules is capable of providing the functionality of a cellular mobile communications device. In the example of figure 3, at least a part of the antennas of the device can be implemented in the base unit 310, and the RF connection with the processor module 210 is implemented using the connector structure 220 of module 220, and with matching contact pads in the slot 320 of the base unit 310. Communication between the processor unit and the second module in the other slot can be implemented using signals carried through the digital signal connector 222 and its matching structure in the slot of the base unit 310. Also, connections to any functionalities such as switches in the base unit 310 can be implemented using signals carried through the digital signal connector 222.

Figure 3 shows a base unit and figure 2 a module such that one side of the module 210 forms a part of the outer surface of the computing device, when the module is in a slot 320 in the base unit 310 of the computing device.

CERTAIN FURTHER CONSIDERATIONS

The invention has a number of benefits. The invention provides a module structure that allows for easy insertion and removal of a module from a base unit of a modular device. The module structure does not require high precision from the user in the insertion of a module, as the structure guides the movement of the module during insertion, whereby the placement of the module is accurate even if the user does not insert the module perfectly.

The module structure combined with the RF connector structure described in this specification together provide an exceptionally well performing modular structure for computing devices requiring a wireless communication capability. The structure of the module provides an easy mechanism for insertion and removal, while the RF connector structure provides a high quality connection for RF signals that can be used with the semi-rotational insertion movement of the inventive module structure. This combination is very valuable for modular computing devices having communication functionality, as prior art solutions for modular structures with RF connections have not been good enough for practical use.

The connector structure has a very low profile, which is especially beneficial for RF connections between modules of a communication device. The inventive connector structure has a lot of tolerance for misalignment and sliding when making the connection. The inventive structure also allows other types of movement for mating the structure to its mating surface than only linear, as opposed to traditional coaxial connectors which typically require strictly linear insertion. The inventive structure tolerates some sideways movement during insertion, as well as rotational movement. The inventive structure allows for low precision alignment, even larger misalignments than 0,1 mm. Due to these benefits, the inventive structure is very suitable for modular devices, where users may remove and insert modules many times over the lifetime of the product. The connector structure is also very robust especially in use in a modular device, as it allows insertion with different movements. Large contact areas of the inventive structure also reduce problems related to mechanical wear.

The connector structure provides a large diameter connector that despite the large diameter, has a very low profile. In a test sample manufactured by the inventors, the connector structure was only 1,27 mm thick. The connector structure provides a one-sided connector, where the other mating side only needs contact pads.

CERTAIN FURTHER EMBODIMENTS OF THE INVENTION

In the following, we describe a number of embodiments of the invention.

In a first aspect of the invention, a computing device is provided. The computing device has a base unit and at least one detachable module and at least one slot in the base unit for a detachable module. In a first embodiment according to this first aspect of the invention, at least one slot comprises at least two pins and two ridges for mating with a module, and at least one module comprises

- at least one digital signal connector,

- a first notch at a first end of a first side edge for mating with a first pin in the slot, - a second notch at a first end of a second side edge for mating with a second pin in the slot, said first and second notches mating with said first and second pins so as to allow rotational movement of the module around said first and second pins for final insertion of the module into the slot, and

- a third notch in said first side edge and a fourth notch in said second side edge, said third and fourth notches mating with corresponding ridges in the slot when the module is inserted in the slot for guiding the module into the final inserted position.

In a second embodiment according to this first aspect of the invention, a side of at least one module forms a part of the outer surface of the computing device, when the module is in a slot in the computing device. According to a second aspect of the invention, a module of a computing device for insertion into a slot in a computing device is provided. In a first embodiment of this second aspect of the invention, the module comprises at least one digital signal connector, a first notch at a first end of a first side edge for mating with a first pin in the slot when placed in the slot, a second notch at a first end of a second side edge for mating with a second pin in said slot, said first and second notches mating with said first and second pins so as to allow rotational movement of the module around said first and second pins for final insertion of the module into the slot, and a third notch in said first side edge and a fourth notch in said second side edge, said third and fourth notches mating with corresponding ridges in the slot when the module is inserted in the slot for guiding the module into the final inserted position.

In a second embodiment of this second aspect of the invention, the module further comprises at least a processor unit and a radio frequency connector structure arranged for non-linear contacting with a mating structure.

In a third embodiment of this second aspect of the invention, the module further comprises at least a rechargeable battery and a charging circuit for controlling charging of said rechargeable battery.

In a fourth embodiment of this second aspect of the invention, a side of the module forms a part of the outer surface of a computing device, when the module is placed a slot in the computing device.

In a fifth embodiment according to this second aspect of the invention, in which the module further comprises at least a processor unit and a radio frequency connector structure arranged for non-linear contacting with a mating structure, the connector structure comprises a backing surface, a sprung pin for forming the center contact of the connector structure, a shield ring for forming the shield contact of the connector structure, a ring spring between said backing surface and said shield ring the difference between the outer radius and the inner radius of the ring spring being greater than the thickness of the ring spring, a retaining member for keeping the ring spring in contact with a contact pad on said backing surface and said shield ring in electrical contact with said ring spring, said connector structure being arranged for mating to contact pads on a substantially flat surface.

In a sixth embodiment of this second aspect of the invention, said retaining member is part of an outer case of the module.

In a seventh embodiment of this second aspect of the invention, said ring spring is a wavy washer.

In a eighth embodiment of this second aspect of the invention, said backing surface is a surface of a printed circuit board.

In a ninth embodiment of this second aspect of the invention, the module is a processor module of a modular smartphone.

In a tenth embodiment of this second aspect of the invention, the module is a processor module of a router device.

In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention. While a preferred embodiment of the invention has been described in detail, it should be apparent that many modifications and variations thereto are possible, all of which fall within the true spirit and scope of the invention.

It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

Reference throughout this specification to“one embodiment” or“an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases“in one embodiment” or“in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.

As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the previous description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.