Patent Application
20120043191
1. Field of the Invention
The described embodiments relate generally to peripheral devices for use with computing devices and similar information processing devices. More particularly, the present embodiments relate a thin profile, aesthetically pleasing keyboard well suited for use with computing devices, and methods of assembling such thin profile, aesthetically pleasing keyboards.
2. Description of the Related Art
The outward appearance, as well as functionality, of a computing device and its peripheral devices is important to a user of the computing device. In particular, the outward appearance of a computing device and peripheral devices, including their design and heft, is important, as the outward appearance contributes to the overall impression that the user has of the computing device. One design challenge associated with these devices, especially with portable computing devices, generally arises from a number of conflicting design goals, including the desirability of making the device attractive, smaller, lighter, and thinner while maintaining user functionality.
Therefore, it would be beneficial to provide a keyboard for a portable computing device that is aesthetically pleasing, yet still provides the stability for each key that users desire. It would also be beneficial to provide methods for manufacturing the keyboard having an especially aesthetic design as well as functionality for the portable computing device.
This paper describes various embodiments that relate to systems, methods, and apparatus for providing a trapdoor keyboard mechanism for a low-travel footprint keyboard that allows the use of aesthetically pleasing key caps and also provides key stability for use in computing applications.
According to one embodiment, a thin profile keyboard for a computing device is described. The keyboard includes a plurality of keys arranged in a plurality of rows. Each row includes a plurality of keys and the keys in a first row are offset from the keys in a second row. Each key includes a key cap and an actuator attached to a base plate. The actuator is configured to deform to activate electrical switch circuitry when it is deformed. A portion of a rigid support lever is positioned over the actuator, which can be a metal dome. The support lever has one end that is attached to a bottom surface of the key cap and a second end that is attached to a substrate at a pivot point. When a force is applied to the top surface of the key cap, the force causes the support lever to rotate about the pivot point, causing a bottom surface of the support lever to contact and deform the actuator. In an embodiment, the key cap can be in the form of a flat slab. An elastomeric spacer may be provided on the support lever over the metal dome such that the elastomeric spacer deforms the metal dome when the key is depressed by a user. The use of a single support lever allows the key cap to be simply adhered to the support lever and the support lever also reduces instability when the key is depressed by a user. As the key cap can be adhered to the support lever, intricate attachment features on the underside of the key cap are unnecessary, thereby allowing the key cap to be formed of a variety of materials, including glass and metal.
A method of assembling at least a portion of a low-travel keyboard for a computing device is disclosed. The method can be carried out by the following operations: providing a metal dome configured to deform when depressed from above, disposing a support lever over the metal dome, and adhering a key cap to the support lever. The metal dome can activate electrical switch circuitry of the keyboard when the metal dome is deformed. The support lever is coupled with a substrate at a point on a first end of the support lever. The bottom of the key cap is adhered to a top surface of the second end of the support lever, which is positioned over the metal dome to deform the dome when depressed from above. In an embodiment, the support lever is formed of a rigid material and is pivotally coupled to the substrate such that the support lever deforms the metal dome when the support lever is depressed from above, as the support lever rotates slightly about the pivot point where it is coupled to the substrate. In another embodiment, the support lever is formed of a flexible material and fixedly coupled to the substrate on one end.
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which:
Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiments as defined by the appended claims.
The embodiments herein relate to a thin profile peripheral input device that is both efficient and aesthetically pleasing. In particular, the thin profile peripheral input device can take the form of a keyboard that can include at least a low profile key cap assembly. The low profile key cap assembly can, in turn, be formed of a key cap connected to one end of a beam or lever, the beam or lever having another end pivotally connected to base portion. The key cap can be positioned proximate to a switch mechanism that can be engaged by the key cap impinging thereupon. In one embodiment, the beam can be rigid in nature and formed of, for example, stainless steel, aluminum, or any other suitable material. The rigid beam can be pivotally connected to the base portion at a pivot point using, for example, bushings. In this way, in order to engage the actuator, a force can be applied to the key cap causing the beam and the key cap to rotate about the pivot point resulting in the key cap moving in an arc-like manner. However, due to the relatively long distance between the pivot point and the key cap and the reduced Z stack of the key cap assembly, the angle of rotation of the key cap is small enough and any rotational wobble is substantially reduced.
In another embodiment, the beam can be formed of a more compliant material fixedly connected to the base. In this way, when the force is applied to the key cap, the beam can bend allowing a more compliant feel to the key cap. It should be noted that, in some cases, a compliant material layer formed of, for example, silicone rubber can be positioned between the key cap and the actuator providing a distinctive feel to the key cap. In some cases, this distinctive feel can be customized to a particular application by using various materials. For example, a harder material can provide a more firm feel whereas softer, more compliant materials, such as silicone rubber, a more compliant feel. In this way, it is contemplated that selected key cap assemblies can be fashioned to have their own associated “feel” that can depend upon a number of factors such as a position on the keyboard, function associated with key cap, and so on.
Furthermore, since there is no restriction on the material used to form an observable portion of the key cap, the key caps can be formed to include an upper layer formed of materials heretofore deemed unsuitable for use in keyboards. Such materials as wood, stone, polished meteorite (watch dials have been made from polished meteorite), glass, etc. can be used as opposed to standard key caps that rely on plastic material.
There are several types of keyboards, usually differentiated by the switch technology employed in their operation. The choice of switch technology affects the keys' responses (i.e., the positive feedback that a key has been depressed) and travel (i.e., the distance needed to push the key to enter a character reliably). One of the most common keyboard types is a “dome-switch” keyboard, which works as described below. When a key is depressed, the key pushes down on a rubber dome sitting beneath the key. The rubber dome collapses, which gives tactile feedback to the user depressing the key, and causes a pair of conductive lines on the printed circuit board (PCB) below the dome to contact, thereby closing the switch. A chip in the keyboard emits a scanning signal along the pairs of lines on the PCB to all the keys. When the signal in one pair of lines changes due to the contact, the chip generates a code corresponding to the key connected to that pair of lines. This code is sent to the computer either through a keyboard cable or over a wireless connection, where it is received and decoded into the appropriate key. The computer then decides what to do based on the particular key depressed, such as display a character on the screen, or perform some other type of action. Other types of keyboards operate in a similar manner, with the main difference being how the individual key switches work. Some examples of other keyboards include capacitive keyboards, mechanical-switch keyboards, Hall-effect keyboards, membrane keyboards, roll-up keyboards, and so on.
As shown in
When the key cap 110 is pressed down by a user in the direction of arrow A, it depresses the rubber dome 140 underneath the key cap 110. The rubber dome 140, in turn, collapses, giving a tactile response to the user. The scissor-mechanism 130 also transfers the load to the center to collapse the rubber dome 140 when the key cap 110 is depressed by the user. The rubber dome also dampens the keystroke in addition to providing the tactile response. The rubber dome 140 can contact a membrane 150, which serves as the electrical component of the switch. The collapsing rubber dome 140 closes the switch when it depresses the membrane 150 on the PCB, which also includes a base plate 120 for mechanical support. The total travel of a scissor-switch key is shorter than that of a typical rubber dome-switch key. As shown in
The following description relates to a single support lever keyboard mechanism for a low-travel keyboard suitable for a small, thin-profile computing device, such as a laptop computer, netbook computer, desktop computer, etc. The use of a single support lever to support the key cap and to activate the switch circuitry not only allows for the key cap to be formed of almost any material but also provides stability to each key, as will be described in more detail below. The aesthetic appearance of a keyboard therefore depends greatly on the key caps, which form most of the visible portion of a keyboard. It will be understood that the material of the key caps will be important, not only because the key caps are highly visible but also because the material should have a desired tactile feel to a user's fingers.
These and other embodiments of the invention are discussed below with reference to
The keyboard can include a key cap 210, such as the one shown in
A standard key, such as the one shown in
According to one embodiment, the support lever 220 can be formed of a rigid material, such as stainless steel or ceramic. Stainless steel has a number of characteristics that make it a good choice for the support lever 220. For example, stainless steel is rigid, durable and fairly resistant to corrosion, and it is a relatively inexpensive metal that can be easily machined and has well known metallurgical characteristics. Furthermore, stainless steel can be recycled. According to an alternative embodiment, the support lever 220 is formed of a ceramic material.
According to some embodiments, the support lever 220 is fixedly attached at one end to the underside of the key cap 210. The fixed attachment provides rotational stability to the key 200 because there is essentially only one moving part when the key cap 210 is depressed by a user. In other words, the support lever 220 and the attached key cap 210 together form the single moving part. A standard key, such as the one shown in
The rigid support lever 220 provides stability to the key by reducing wobble from side to side. The key 200 may rotate slightly forward when depressed, which may be ergonomically desirable. However, such slight rotation is virtually imperceptible for low-travel keys, as is described in more detail below. As shown in
The support lever 220, which, on one end, has its top surface attached to the underside of the key cap 210, can also dictate the height of the key cap 210 or the distance between the key cap 210 and the base plate 270. In the embodiment shown in
In this embodiment, the support lever 220 is formed of a rigid material and rotatably or pivotally coupled, at its other lower end, with the topcase 260 at a pivot point at a distance from the key cap 210. In some embodiments, the distance is about one key pitch. As illustrated in
As shown in
According to some embodiments, the keys 200 are low-travel keys that have a total travel in a range of about 0.2 mm to about 1.85 mm. In other embodiments, the keys have a total travel in a range of about 0.2 mm to about 0.5 mm.
According to another embodiment, the support lever 220 is formed of a flexible material that can be fixedly adhered to the underside of the key cap 210 on its upper end and is fixedly attached to the topcase 260 at the lower end. In this embodiment, the support lever 220 can be formed of spring steel and does not rotate about a pivot point. Instead, the flexible nature of the support lever material allows a similar motion when the key is depressed, like a linear flex-spring.
As shown in
As illustrated in
The skilled artisan will appreciate that it is desirable to make the keyboard (and computing device) thinner, but users still want the tactile feel to which users are accustomed. It is desirable for the keys to have some “bounce-back” or “snappy” feel. As can be appreciated by the skilled artisan, substantially flat keyboards, such as membrane keyboards, do not provide the tactile feel that is desirable for a keyboard. Similarly, simply reducing the travel of a typical rubber dome scissor-switch keyboard also reduces the tactile or “snappy” feel that a conventional dome-switch keyboard provides.
Metal domes can provide very low travel as well as a crisp tactile feel. Like a rubber dome, a metal dome also dampens the keystroke in addition to providing a very crisp tactile response to the user. A metal dome typically has a good tactile force drop with a relatively short travel distance, which is typically about 0.1-0.2 mm.
The skilled artisan will appreciate that a metal dome has a quick force drop over a short travel distance relative to an elastomeric dome. Elastomeric domes lack the quick force drop and therefore the crisp snap of metal domes. Thus, elastomeric domes do not provide the positive crisp tactile response of metal domes, especially when the amount of travel is reduced. However, although a metal dome can provide a positive crisp tactile feel, a metal dome alone cannot provide the desired tactile feel and travel distance for a keyboard suitable for typing or otherwise inputting text. The skilled artisan will appreciate that a metal dome cannot achieve travel greater than about 0.7 mm, as the metal is difficult to deform and would require a large amount of force for deformation. Even if enough force were applied to the metal dome, it would not be able to achieve a travel distance greater than about 0.7 mm unless the metal dome is quite large. A larger metal dome would cause each individual key to also be quite large, which can be undesirable and impractical, especially in portable devices.
According to some embodiments, the support lever 220 can be provided with an elastomeric spacer 225, as shown in
As shown in
In this embodiment, the elastomeric spacer 225 also provides the ability for longer travel. The metal dome 240 provides the majority of the tactile force drop and also activates the switch circuitry of the membrane 250 on the base plate 270. The abrupt or quick force drop of the metal dome 240 provides the crisp “snappy” feel for the user. It provides the kind of force drop that the metal dome allows, and also the initial compliancy and force build-up that are absent in metal domes.
When a user presses down on the key cap 210, it causes the support lever 220 to which the key cap 210 is rigidly attached to rotate slightly and move downward. As the support lever 220 moves downward, the elastomeric spacer 225 contacts and collapses the elastomeric dome 220. As shown in
According to an embodiment, the support lever 220 has a thickness of about 0.5 mm. In other embodiments, the support lever may have a thickness that is less than 0.5 mm. In some embodiments, the elastomeric spacer can have a thickness in a range of about 0.3 to 1 mm. In other embodiments, the elastomeric spacer can have a thickness in a range of about 0.5 to 1 mm. The metal dome 240 can have a height in a range of about 0.3 mm to about 0.7 mm. According to another embodiment, the metal dome 240 has a height in a range of about 0.3 mm to about 0.5 mm. In still another embodiment, the metal dome 240 has a height in a range of about 0.5 mm to about 0.7 mm.
In an embodiment, the metal dome 240 has a thickness in a range of about 0.03 mm to about 0.1 mm. It will be understood that the metal dome 240 typically has a uniform thickness if it is formed from a sheet of metal. The skilled artisan will appreciate that the thicknesses of the dome 240 and elastomeric spacer 225 can be adjusted and/or varied to obtain the desired force drop. The base diameter of the dome 240 can be in the range of about 3 mm to 7 mm.
According to an embodiment, as shown in
Under “normal” conditions when the key pad is not depressed by a user (as shown on the left side of
A process for assembling the key switch 200, such as the one shown in
A process for forming the three-layer membrane 250 on the base plate 270 will be described below with reference to steps 810-830. In step 810, the bottom layer 256 of the membrane 250 can be positioned over the base plate 270. Next, in step 820, the spacer layer 254 can be positioned over the bottom layer 256 such that the voids 260 are in the areas of the contact pads 258. In step 830, the top layer 252 can be positioned over the spacer layer 254 such that the contact pads 258 on the underside of the top layer 252 are positioned directly over the contact pads 258 on top side of the bottom layer 256 so that they can contact each other when the metal dome 240 is deformed. The layers 252, 254, 256 can be laminated together with adhesive. It will be understood that steps 810-830 can be combined into a single step by providing a three-layer membrane 250 that is pre-assembled or pre-laminated. The membrane 250 is positioned over the base plate 270 and held in place by one or more other components of the key switch 200, such as the scissor mechanism 230.
According to this embodiment, in step 840, the metal dome 240 can be attached to the top side of the top layer 252 of the membrane 250 such that the concave dome portion is positioned over the contact pads 258 and the void 260. In step 850, the support lever 220 is positioned over the metal dome such that the elastomeric spacer 225 is positioned directly over the center of the metal dome 240. In step 860, the support lever 220 is coupled to the topcase 260 at a point at a distance from the key switch 200. In an embodiment, the support lever 220 may be formed of a rigid material and has bearings 222 and the support lever 220 is pivotally coupled, at one end, to the topcase 260 at the point so that the support lever 220 can rotate slightly when a downward force is applied from above. In another embodiment, the support lever 220 may be formed of a flexible material and is fixedly coupled, at one end, to the topcase 260. In this embodiment, in step 870, to complete the key switch 200, the key cap 210 is positioned over and attached to the support lever 220. According to an embodiment, the underside of the key cap 210 can be adhered to the top side of the support lever 220.
The advantages of the invention are numerous. Different aspects, embodiments or implementations may yield one or more of the following advantages. One advantage of the invention is that a low-travel keyboard yet may be provided for a thin-profile computing device without compromising the tactile feel of the keyboard.
The many features and advantages of the described embodiments are apparent from the written description and, thus, it is intended by the appended claims to cover such features and advantages. Further, since numerous modifications and changes will readily occur to those skilled in the art, the invention should not be limited to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.
