Key assembly and portable electronic device using the same

A key assembly comprises a base plate, two elastic elements and a key body. Each elastic element has a securing portion and two compressing portions protruding from two ends of the securing portion. The securing portions are latched to the base plate. The key body is slidably mounted to the base plate between the two elastic elements. The key body includes a first key section resisting one of the two elastic elements and a second key section resisting another elastic element. When the first key section slides toward and compresses the corresponding elastic element, the second key section slide away from the corresponding elastic element.

This application is related to co-pending U.S. Patent Applications (Publication No. US2010/0128460, US2010/0127899, US2010/0134965), entitled “KEY ASSEMBLY AND PORTABLE ELECTRONIC DEVICE USING THE SAME”, by Mu-Wen Yang et al. Such applications have the same assignee and inventorship as the present application and have been concurrently filed herewith. The above-identified applications are incorporated herein by reference.

BACKGROUND

1. Technical Field

The exemplary disclosure generally relates to key assemblies, and particularly to key assemblies used in portable electronic devices.

2. Description of Related Art

With the development of smaller and lighter electronic devices for portable use, key assemblies become more compact with individual keys more tightly spaced. Unfortunately, users of these portable electronics sometimes experience difficulty in activating keys that are close together; multiple and/or erroneous keys may be activated at the same time. This drawback exists not only in cellular telephones, but other portable electronic devices with key assemblies.

Therefore, there is room for improvement within the art.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, an exemplary embodiment of a key assembly10can be used on a portable electronic device100, such as a cellular phone or any electronic device where a key is desirable. The portable electronic device100includes a key assembly10and a circuit board20. The circuit board20has a first switch22and a second switch24spaced from the first switch22. The key assembly10is configured to press the first switch22and the second switch24, to control the circuit board20.

The key assembly10includes a key body12, two elastic elements14and a base plate16. The key body12and the elastic elements14are both mounted to the base plate16. The base plate16may be a portion of the housing of the portable electronic device100or may be a separate element mounted to the housing of the portable electronic device100. In this exemplary embodiment, the base plate16is a portion of the housing of the portable electronic device100.

The key body12includes an operating surface1221facing the outside of the portable electronic device, a contacting surface1222opposite to the operating surface1221, a first side surface1223, a second side surface1224opposite to the first side surface1223, a first end1225and a second end1226opposite to the first end1225. The operating surface1221has a trough1227transversely defined near a center thereof, thus the key body12is divided into a first key section124located one end of the trough1227and a second key section126located another end of the trough1227. The first key section124corresponds to the first switch22, the second key section126corresponds to the second switch24. The key body12further has two guiding blocks1228protruding from the first side surface1223and the second side surface1224, respectively. The guiding blocks1228are coaxial and are slidably assembled to the base plate16.

The operating surface1221has indicia1229respectively defined in the first key section124and the second key section126, to indicate the function of the first key section124and the second key section126. The indicia1229of the first key section124may be a “−”, to indicate the function of the second key section126is decreasing volume. The indicia1229of the second key section126may be a “+”, to indicate the function of the first key section124is increasing volume.

The key body12has a first arcuate contacting portion1242protruding from the contacting surface1222at the first key section124. The first contacting portion1242corresponds to and is configured to trigger the first switch22. The key body12has a second arcuate contacting portion1262protruding from the contacting surface1222at the second key section126. The second contacting portion1262corresponds to and is configured to trigger the second switch24. The first contacting portion1242and the second contacting portion1262may be constructed from an injection-molded thermoplastic elastomer and configured to produce a point contact sensation in a user's fingertip to provide tactile feedback when a user presses the key body12.

The key body12has a first securing section1230and a second securing section1231protruding outwardly from the first end1225thereof. The first securing section1230is spaced from and parallel to the second securing section1231, so a first securing space1232is formed between the first securing section1230and the second securing section1231. The key body12has a third securing section1233and a fourth securing section1234protruding outwardly from the first end1225thereof. The third securing section1233is spaced from and parallel to the fourth securing section1234, thus a second securing space1235is formed between the third securing section1233and the fourth securing section1234. In this exemplary embodiment, the first securing section1230and the third securing section1233are made of flexible material (e.g., thermoplastic elastomer), to facilitate assembling the key body12to the base plate16. The rationale of assembling the key body12to the base plate16will describe hereinafter.

Each elastic element14is an elastic plate including a U-shaped securing portion142, two compressing portions144and two rectangular resisting portions146. The compressing portions144respectively protrude from two opposite ends of the securing portion142. The distance between the compressing portions144gradually increases from the end near the securing portion142to the distal ends thereof. The resisting portions146oppositely protrude from a distal end of each compressing portion144.

The base plate16includes a peripheral wall162and a bottom wall164substantially perpendicularly connected to the peripheral wall162. The peripheral wall162has a hole1621defined therein corresponding to the key body12. The hole1621is sized and configured to engage with the key body12. The peripheral wall162has a first inner wall1622, a second inner wall1623opposite to the first inner wall1622, a third inner wall1624and a fourth inner wall1625, all of which are defined in the hole1621. The first inner wall1622is level with the bottom wall164and the second inner wall1623is parallel to the bottom wall164. The third inner wall1624and the fourth inner wall1625respectively connect the first inner wall1622with second inner wall1623.

The peripheral wall162further has two guiding grooves1626defined in the first inner wall1622and the second inner wall1623, respectively. The guiding grooves1626correspond to and are configured to accommodate the guiding blocks1228therein. The peripheral wall162has two securing grooves1627respectively defined in the third inner wall1624and the second inner wall1623, and the securing grooves1627is defined through an inner surface of the peripheral wall162. The securing grooves1627are configured to accommodate the securing portions142of the elastic elements14. Additionally, the peripheral wall162has a first receiving groove1628defined in the third inner wall1624and a second receiving groove1629defined in the fourth inner wall1625. The first receiving groove1628and the second receiving groove1629are both defined through an outer surface of the peripheral wall162. The first receiving groove1628is larger than and configured for accommodating the second securing section1231, so the second securing section1231can slide in the first receiving groove1628. The second receiving groove1629is larger than and configured for accommodating the fourth securing section1234, so the fourth securing section1234can slide in the second receiving groove1629.

Referring toFIGS. 3 and 5, to assemble the portable electronic device100, firstly, the securing portions142of the elastic elements14are latched in the securing grooves1627of the peripheral wall162, so the elastic elements14are latched to the base plate16. Secondly, the first securing section1230and the third securing section1233are bent to pass through the hole1621. Thirdly, the guiding blocks1228of the key body12are accommodated in the guiding grooves1626of the base plate16. At this time, the first securing section1230and the third securing section1233entirely enter into the base plate16and restore to their original state, the first securing space1232and the second securing space1235respectively accommodate one elastic element therein, the second securing section1231is accommodated in the first receiving groove1628, the fourth securing section1234is accommodated in the second receiving groove1629. Moreover, the compressing portions144of the elastic element are compressed to resist first end1225and the second end1226, respectively. Thus, the key body12is securely mounted to the base plate16.

After that, the circuit board20is mounted to the bottom wall164. At this stage, the first switch22is resisted against the area of the first contacting portion1242adjacent to the contacting surface1222. In other words, the first switch22is resisted against the first contacting portion1242but not against the high-point of the first contacting portion1242. The second switch24is resisted against the area of the second contacting portion1262adjacent to the contacting surface1222. In other words, the second switch24is resisted against the second contacting portion1262but not against the high-point of the second contacting portion1262.

Referring further toFIGS. 6 and 7, the function first key section124is described herein, but can also apply to the second key section126. Firstly, the first key section124is pushed in the direction of the arrow shown inFIG. 4, so the key body12is slid in the hole1621in the direction of the arrow shown inFIG. 4. At this time, the guiding blocks1228slide in the guiding grooves1626, the first end1225of key body12compress the compressing portion144in the first securing space1232to accumulate elastic force, thus the key body12can rebound when released. The first switch22moves toward to the high-point of the first contacting portion1242, i.e., the first contacting portion1242presses and triggers the first switch22in the direction of arrow shown inFIG. 6. Simultaneously, the second key section126moves in the direction of arrow shown inFIG. 4, i.e., the second switch24moves away from the high-point of the second contacting portion1262, to prevent from triggering the second switch24. Thus, a user's fingertip touches only one key section at a time, thus removing the possibility of hitting two keys simultaneously.