Patent Grant
9831612
Embodiments of the present disclosure relate to shielding, and more particularly, the embodiments relate to shielding for a connector that prevents electromagnetic interference.
Today, devices, such as consumer electronics, are exposed to a plethora of electromagnetic interference. Electromagnetic interference can adversely affect the performance of these devices especially devices that handle high frequency data signals. Accordingly, most such devices typically comprise at least one shielding enclosure.
However, electronic devices must typically include features such as apertures, slots, cabling, connector ports, and the like in order to connect to other devices. In addition, openings or breaks in the shielding enclosure may be needed for cooling or ventilation of the electronic components. These features cause openings or breaks in the shielding enclosure through which electromagnetic interference can penetrate. Thus, the design of such features can be important to the performance of the device.
In high-frequency data transfer applications, it is becoming very challenging to keep electromagnetic emission within acceptable limits, especially without the need for an external shielding. Various mechanical shield designs and EMI suppressing tapes have been used in electronic devices. These solutions, however, are often inadequate in sufficiently reducing electromagnetic interference and increase the cost of the product.
In accordance with an embodiment of the present invention, a universal serial bus (USB) connector comprises a housing configured to accept at least one male USB connector and connect the USB connector to a set of electrical connections. The connector also comprises a shielding shell, coupled to the housing, comprising a set of structures for mounting the connector and defining a plurality of apertures through which the set of electrical connections may pass. The shielding shell includes at least one grounding structure configured to reduce electromagnetic interference (EMI) generated from signals over the set of electrical connections.
In accordance with another embodiment of the present invention, a female USB connector comprises an insulative housing having a front side and a rear side, an electrically conductive shell, a first set of contacts, and a second set of contacts. The electrically conductive shell encloses the insulative housing and cooperates with the insulative housing to define a front receiving cavity adapted for receiving a complementary male USB connector and a set of apertures on the rear side. The first set of contacts are held in the insulative housing and are provided for transmitting a first set of signals carrying data at a first data rate, wherein the first set of contacts have respective portions exposed in the receiving cavity and extending rearward through a first aperture on the rear side. The second set of contacts are held in the insulative housing and are provided for transmitting a second set of signals carrying data at a second rate that is higher than the first data rate, wherein the second set of contacts have respective portions exposed in the receiving cavity and extending rearward through a second aperture on the rear side. The first and second apertures are separated by a grounding structure that extends from the electrically conductive shell.
Additional features of the embodiments will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the embodiments. The advantages of the embodiments can be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the embodiment, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the embodiment. In the Figures:
The embodiments of the present invention provide a shielded connector having improved shielding effectiveness to reduce electromagnetic interference (EMI). Some of the various embodiments provide high-speed electrical connectors capable of carrying very large (e.g., gigabyte and higher) data rate signals. The shielding may employ, among other things, one or more shielding structures to reduce the EMI associated with these and other signals. The shielding structures may be configured, or oriented, to reduce or limit the exposure to apertures within the connector through which EMI can penetrate. For example, some embodiments for a universal serial bus (USB) connector may support a USB 3.0 connector, USB 2.0 connector, or both. For these embodiments, a grounding tab or peg may be placed in the rear of the connector between the USB 3.0 and the USB 2.0 connections to divide the aperture for the port into a plurality of sections. The grounding tab or peg may also serve as a structural support for the connector.
For purposes of illustration, embodiments for a USB connector, such as a connector supporting USB 3.0, is described to illustrate the principles of the invention. One skilled in the art will recognize that the various embodiments can be applied to other types of connectors. Reference will now be made in detail to exemplary embodiments of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
In the Figures,
For example, the upper shield 102 and lower shield 104 may be welded, such as laser welded, together to form a shielding shell around the housing structure 106. Accordingly, in assembled form as a female USB, the connector 100 provides a receiving cavity (or opening) 110 to accept complimentary male USB connectors.
For purposes of illustration, the connector 100 is shown mounted on to a printed circuit board 108 to show how connector 100 may be implemented within an electronic device (not shown). The components of connector 100 will now be further described.
External shield 102 serves as part of the shielding shell and provides shielding for the connector 100. External shielding 102 may be constructed from a low impedance material, such as a metal. In some embodiments, external shield 102 is produced from a sheet metal material to facilitate production. The dimensions of external shield 102 may be based on a variety of factors, such as, dimensions needed for the connector engagement, allowance for re-work during manufacturing, and the like.
Internal shield 104 of the shielding shell serves as a complimentary part to external shield 102 and also may provide shielding for the connector 100. Internal shield 104 may be constructed from a low impedance material, such as a metal. Likewise, internal shield 104 may be produced from a sheet metal material.
Housing 106 provides the structural foundation for connector 100. In some embodiments, the housing 106 is constructed from an insulative material, such as plastic. For example, as noted above, housing 106 may be configured and shaped for a female USB connector. In the embodiment shown, the housing 106 is configured to accept a USB 3.0 and USB 2.0 connector in a side-by-side configuration. Of course, connector 100 and housing 106 may be configured to accommodate other types of connectors and other types of arrangements within the principles of the present invention.
In addition, connector 100 may comprise a shielding grounding structure 120 and mounting structures 122. In the embodiment shown, shielding grounding structure 120 may be a peg-like structure that extends from external shield 102 for attachment to a through-hole provided in board 108. In the embodiment shown, shielding grounding structure 120 is shown as a single, solid structure. In other embodiments, shielding grounding structure 120 may comprise multiple structures and features. For example, shielding grounding structure 120 may comprise two or more peg-like structures, or a single peg-like structure with a slit cut in it. In addition, in one embodiment, the shielding grounding structure 120 may be positioned in proximity to the second set of contacts 114 to assist in reducing EMI generated by the USB 3.0 signals.
Mounting structures 122 may be structures that extend from external shield 102 and provide a retention and grounding feature for connector 100. For example, mounting structures 122 may be provided at the corners of external shield 102 and configured as peg-like structures that extend from the external shield 102 and configured for attachment to respective through-holes provided in the printed circuit board 108. Of note, shielding grounding structure 120 can provide additional retention strength and grounding paths that compliment mounting structures 122.
The ability of a shield to reduce EMI or improve the immunity of a device to EMI and other high frequency interference can be characterized by a parameter known as shielding effectiveness (SE). In the embodiments, the shielding shell formed from upper shield 102 and lower shield 104 may be configured to achieve a desired SE. SE can be defined as the ratio of the strength of an EMI field within two different enclosures. For convenience, SE can be expressed in units of decibels according to the formula:
SE=20 log(λ/2 L), where λ is the wavelength of the signal and L is the length of the aperture being studied. For USB 3.0 signals, a frequency of about 3-5 GHz is relevant, which results in a λ range that is approximately 60-100 mm.
As noted above, connector 100 provides an overall opening having a length L1 and a height H. In the absence of shielding grounding structure 120, connector 100 thus provides an aperture of L1 by H through which EMI generated by the USB 2.0 and USB 3.0 signals may emanate. In some embodiments, connector 100 may provide a total aperture length L1 of about 13 mm. As to the height H, it may be configured based on providing an opening of about 1/20th of the relevant wavelength λ, while also allowing sufficient clearance for re-work (if needed). In the present disclosure, it was discovered that the USB 3.0 signals, due to their higher frequency, were generating EMI that would affect the performance of an electronic device. As noted above, conventional solutions, such as grounding tape, and the like, were either cost prohibitive or ineffective in reducing the EMI to sufficient levels.
With shielding grounding structure 120 in place, however, the aperture of otherwise unshielded connector 100 is structurally compartmentalized or physically separated into two (or more) smaller apertures, i.e., apertures 116 and 118. As shown, aperture 116 may have a length L2 and also a height H. In some embodiments, shielding grounding structure 120 was placed to provide a length L2 of about 4-5 mm to place the structure in proximity to the USB 3.0 signals, while also providing sufficient clearance for re-work (if needed). For example, in one embodiment, shielding grounding structure 120 was placed to provide a length L2 of 4.8 mm for aperture 118.
Referring now back to the equation above, the shielding effectiveness (SE) of connector 100 as it relates especially to EMI for USB 3.0 signals may now be studied. In particular, since both apertures have the same height in the embodiment, the SE of the embodiment shown essentially varies based on the lengths of the relevant apertures. Accordingly, assuming L1=13 mm and L2=4.8 mm, the SE for each scenario becomes:
Without shielding grounding structure 120, L1=13 mm, thus . . . .
SE=20 log(100 mm/(2×13 mm))
SE=11.7 dB
With shielding grounding structure 120, L2=4.8 mm, thus . . .
SE=20 log (100 mm/(2×4.8 mm))
SE=20.2 dB
Accordingly, based on these and other calculations as well as testing, the embodiments of the present invention were found to dramatically improve EMI suppression, e.g., by over 8 dB, of the connector 100.
Shielding grounding structure 120 may be configured with different shapes. For example, shielding grounding structure 120 may have various depths, widths, and lengths depending on the EMI characteristics or manufacturing characteristics desired. In addition, shielding grounding structure 120 may have various features, such as curves, surface treatments, and other shapes, depending on the desired features.
It is contemplated that any number of grounding structures and mounting structures may be provided with the shielding shell of the present invention. Although a single grounding structure 120 is shown in the embodiment described herein, it is understood that two or more grounding structures may also be provided, in order to provide additional physical barriers and further compartmentalize or separate the set of contacts 112, 114 from one another. One skilled in the art will recognize that the number of grounding structures 120 that can be employed is limited by the physical exposure required of each aperture to allow the set of contacts 112, 114 sufficient room to attach to other electrical devices.
Further, as previously mentioned, the grounding structures 120 may be formed of any shape or size, so long as the structures 120 are capable of providing sufficient physical barriers to EMI for the apertures. As shown and described above, the grounding structure 120 extends from the external shield 102. However, the grounding structure 120 may also be formed as a separate component and attached to the shielding.
Other aspects of the embodiment will be apparent to those skilled in the art from consideration of the specification and practice of the embodiment disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the embodiment being indicated by the following claims.
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