Patent Grant
8729415
The present invention relates to a power switch, more particularly to a power switch having a light-emitting unit which can be easily installed to the power switch in a way for saving the time, labor, and materials required for producing the power switch in an automated production and, in the meanwhile, increasing the safety of use.
As more and more electric appliances are brought to the market, the various electric appliances have played an increasingly important role in our daily lives. However, fire accidents caused by such appliances have also become an issue. According to the National Fire Agency of Taiwan's Ministry of the Interior, the total number of reported fire accidents in Taiwan in 2010 is 2186, of which more than one third, or 744 cases, can be attributed to electric appliances. Therefore, in order to create a safer living environment, it is imperative for the general public to have proper concepts and habits regarding the use of electricity and to choose electric appliances that are safe in design. Generally speaking, an electric appliance is almost always provided with a power switch for controlling the electric current flowing into and out of the appliance, so that users can switch on and off the appliance conveniently.
Referring to
As shown in
Referring to
The temperature of the thermally actuated metal plate 14 rises when the power switch 1 is turned on, and the rise in the temperature varies with the current flowing through the thermally actuated metal plate 14 per unit time. Once the temperature of the thermally actuated metal plate 14 reaches a memory temperature, the thermally actuated metal plate 14 begins to deform. Therefore, referring to
While power switches similar to the power switch 1 are now in extensive use, the power switch 1 still has certain drawbacks in terms of production, as explained below with reference to
(1) As the light-emitting unit 16 is configured to have one electrode 161 clamped between the third conductive plate 133 and the inner wall of the housing 11 and the other electrode 161 clamped between the second conductive plate 132 and the spring 171, the assembly process must be conducted slowly and carefully to ensure proper electrical connection between the light-emitting unit 16, the second conductive plate 132, and the third conductive plate 133. Besides, an assembly worker often has to move several components in order to install one, thus lowering production efficiency.
(2) The foregoing assembly process cannot be done other than manually, so the quality of assembly depends mainly on the assembly workers' experience. To achieve a high yield rate, a manufacturer must take considerable time training the assembly workers, which nevertheless results in high labor costs.
(3) Given the current design trend of the power switch 1 toward increased compactness, the interior space of the housing 11 is very limited. Because of that, the electrodes 161 of the light-emitting unit 16 are often bent to save space. However, if the electrodes 161 are bent so much that they contact with the C-shaped spring 15, short circuits will occur. To prevent such short circuits, the electrodes 161 must be parted during assembly to avoid contact with the C-shaped spring 15, and this explains why the adjustment of the electrodes 161 always takes a lot of time and effort. The manual adjustment also hinders automated installation of the light-emitting unit 16 and compromises the yield rate of the power switch 1. Moreover, the light-emitting unit 16 tends to shake slightly when the key 12 is moved back and forth. As time goes on, the accumulated effect of such slight shakes may bring the electrodes 161 closer to, or even into contact with, the C-shaped spring 15, thereby causing dangerous short circuits.
(4) The second conductive plate 132 must be bent several times so as for its top end to serve as a supporting surface for the thermally actuated metal plate 14, and for its bottom end to extend out of the housing 11 and be adequately spaced from the first and the third conductive plates 131, 133. This bent structure of the second conductive plate 132, however, requires the use of more material than a straight structure and incurs higher material costs. Additionally, as the lower bent portion of the second conductive plate 132 is adjacent to the top end of the first conductive plate 131, the first conductive plate 131, if tilted when installed, is very likely to contact with the second conductive plates 132, thus rendering the power switch 1 useless. Furthermore, if the power switch 1 is used in a circuit configured for a large current, an electric arc may take place between the first and the second conductive plates 131, 132 should the lower bent portion of the second conductive plate 132 be too close to the first conductive plate 131. Such electric arcs are severe safety hazards because they not only can damage the power switch 1 but also may cause fire accidents.
Please refer to
(1) Referring to
(2) As the key 22 relies on the push/pull bar 25 to drive the thermally actuated metal plate 24 and thereby connect or separate the first and the second contacts P5, P6, the distance between the two ends of the push/pull bar 25 is crucial to the operation of the switch 2. If the distance is too great, the push/pull bar 25 will have problem pulling the thermally actuated metal plate 24; as a result, the second contact P6 will never contact with the first contact P5. If the distance between the two ends of the push/pull bar 25 is too small, the push/pull bar 25 cannot push the thermally actuated metal plate 24 properly, and because of that, the second contact P6 will not separate from the first contact P5. Since the push/pull bar 25 is a slender and hence rather fragile metal rod, it cannot be installed by an automated process. The assembly worker must take extra care in order not to bend the push/pull bar 25; otherwise, the distance between the two ends of the push/pull bar 25 may be altered, which is detrimental to the function of the switch 2.
(3) The assembly process described above must be carried out by hand and therefore relies heavily on the assembly workers' experience. In order to increase yield rate, a manufacturer must spend a lot of time training the assembly workers, and yet high labor costs ensue.
(4) The second conductive plate 232 must be bent several times so that its top end provides a supporting surface for the thermally actuated metal plate 24 and its bottom end extends out of the housing 21 and is properly spaced from the first and the third conductive plates 231, 233. This bent structure, however, increases the material required for making the second conductive plate 232 and thus incurs a high production cost.
The foregoing switches are only two examples of the conventional power switches. The various conventional power switches on the market, though different in design, have more or less the same drawbacks that make automated production impossible; consequently, the burden of high labor costs cannot be relieved from the manufacturers' shoulders. The soaring prices of metals also contribute to high material costs. More importantly, the conventional power switches have safety concerns that have yet to be properly addressed. Hence, it is a pressing issue for power switch designers and manufacturers to simplify the overall design and components of a power switch so that a light-emitting unit can be easily installed in the power switch by an automated process, thus not only reducing the labor and material costs of the power switch, but also preventing short circuits which may otherwise occur if the two electrodes of the light-emitting unit contact with a C-shaped spring.
In view of the drawbacks of the conventional power switches—namely an overly complicated structure that compromises yield rate and increases the difficulty in assembly, and the risks of short circuits caused by contact between the two electrodes of a light-emitting unit and a C-shaped spring—the inventor of the present invention conducted extensive research and experiment and finally succeeded in developing a power switch suitable for automated production. The present invention proposes a simplified power switch structure in which a light-emitting unit can be easily installed and whose third conductive plate is made of less metal material than in the prior art. Moreover, as the two electrodes of the light-emitting unit will never contact with a C-shaped spring, short circuits otherwise attributable to such contact are effectively prevented, and the time and effort otherwise required for adjusting the electrodes during the assembly process can be spared. Thus, the present invention saves the time, labor, and materials required for producing power switches and, on top of that, increases safety of use.
It is an object of the present invention to provide a power switch suitable for automated production, wherein the power switch includes a housing, a key, a first conductive plate, a thermally actuated metal plate, a C-shaped spring, a second conductive plate, an insulating seat, a light-emitting unit, and a third conductive plate. The housing forms a receiving space therein and has a top surface provided with an opening communicating with the receiving space. The middle portion of the key is pivotally connected to the inner periphery of the opening. The bottom of the key is provided with a first pushing portion and a second pushing portion, wherein the two pushing portions are proximate to two opposite ends of the key respectively and are received in the receiving space. The first conductive plate is fixedly provided adjacent to an inner lateral side of the housing. The top end of the first conductive plate is received in the receiving space while the bottom end of the first conductive plate extends out of the bottom surface of the housing. The thermally actuated metal plate has one end fixed to the top end of the first conductive plate and a free end extending toward an opposite inner lateral side (hereinafter referred to as the second inner lateral side) of the housing. The thermally actuated metal plate is formed with a generally U-shaped groove that defines a resilient tongue of the thermally actuated metal plate. The resilient tongue has a free end extending toward the first conductive plate. The free end of the resilient tongue can move above or below the groove when the free end of the thermally actuated metal plate is subjected to or not subjected to an applied force. In addition, a first contact is provided on the resilient tongue and proximate to the free end thereof. The C-shaped spring has one end engaged with the free end of the resilient tongue and an opposite end engaged with the end of the thermally actuated metal plate that is connected to the first conductive plate. Moreover, the C-shaped spring corresponds in position to the first pushing portion. The second conductive plate is fixedly provided on the housing. The top end of the second conductive plate is received in the receiving space and provided with a second contact corresponding in position to the first contact. The bottom end of the second conductive plate extends out of the bottom surface of the housing. When the first pushing portion is moved downward, the C-shaped spring is pushed by the first pushing portion and therefore drives the free end of the resilient tongue downward; as a result, the free end of the resilient tongue is moved to a position below the groove to make electrical connection between the first contact and the second contact. When the second pushing portion is moved downward, the free end of the thermally actuated metal plate is moved downward by the second pushing portion and hence generates a resilient restoring force that drives the free end of the resilient tongue upward; consequently, the first contact is separated from the second contact.
The insulating seat is received in the receiving space and adjacent to the second inner lateral side of the housing. The light-emitting unit is located in the key and has two electrodes connected to the insulating seat such that the light-emitting unit and the insulating seat form a single piece. One of the electrodes is pressed against the second conductive plate, and the other electrode (hereinafter referred to as the second electrode) is exposed on the bottom of the insulating seat. The third conductive plate is fixedly provided adjacent to the second inner lateral side of the housing. The top end of the third conductive plate lies against the bottom of the insulating seat and is connected to the second electrode of the light-emitting unit. The bottom end of the third conductive plate extends out of the bottom surface of the housing.
Compared with the conventional power switches, the power switch described above has substantially simplified components to facilitate installation of the light-emitting unit. More specifically, the power switch can be manufactured by an automated process that begins by connecting the electrodes of the light-emitting unit to the insulating seat and then installs all the components into the housing. Thus, the assembly process is simple and smooth and spares the time and effort otherwise required in a complicated assembly operation, such as manual adjustment of the electrodes of the light-emitting unit to avoid contact with the C-shaped spring. In a nutshell, the power switch disclosed herein is suitable for automated production. Furthermore, the material required for making the third conductive plate is substantially reduced, so the production cost of the power switch can be effectively cut. Now that the two electrodes of the light-emitting unit will by no means contact with the C-shaped spring, short circuits otherwise attributable to such contact are also effectively prevented. Therefore, the present invention not only saves time, effort, and materials during the manufacturing process, but also enhances safety of use.
It is another object of the present invention to provide the foregoing power switch, wherein the housing is further provided therein with a plurality of positioning grooves corresponding in configuration to the top ends of the first and the second conductive plates respectively, so that the first and the second conductive plates can be securely assembled to the housing. With the top ends of the first and the second conductive plates being positioned in the positioning grooves respectively, the bending angles of both conductive plates will not be altered during the assembly process as a result of the elasticity of the metal material of which these conductive plates are made; hence, the distance between the first and the second contacts is prevented from deviating from the design value. More particularly, the two contacts will not be rendered so far apart that they cannot contact with each other to make a circuit. Nor will the two contacts be so close that, should a current overload take place, the thermally actuated metal plate cannot separate the first contact from the second contact to prevent safety hazards.
The structure as well as a preferred mode of use, further objects, and advantages of the present invention will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, in which:
The present invention discloses a power switch suitable for automated production. Referring to
The first conductive plate 331 is fixedly provided at a position adjacent to an inner lateral side of the housing 31. The top end of the first conductive plate 331 is received in the receiving space 311 and positioned in one of the positioning grooves 313. The bottom end of the first conductive plate 331 extends out of the bottom surface of the housing 31. The thermally actuated metal plate 34 has one end fixedly connected to the top end of the first conductive plate 331 and a free end extending toward an opposite inner lateral side (hereinafter referred to as the second inner lateral side) of the housing 31. As shown more clearly in
The insulating seat 36 is received in the receiving space 311 and adjacent to the second inner lateral side of the housing 31. The light-emitting unit 37 is located in the key 32, but the light emitted by the light-emitting unit 37 can be seen from outside the power switch 3 through the light-permeable portion 323. As shown in the embodiment of
The components of the power switch 3 have much simpler structures than those of their prior art counterparts so that the light-emitting unit 37 can be easily installed in the power switch 3. Besides, the third conductive plate 333 is so configured that it can be made of less metal material than in the prior art. As the two electrodes 371 of the light-emitting unit 37 are kept from making any contact with the C-shaped spring 35, short circuits which may otherwise result from such contact are effectively prevented. The time and effort otherwise required to adjust each electrode 371 during the assembly process in order to avoid contact with the C-shaped spring 35 can also be spared. Thus, the present invention increases the safety of use of power switches while saving the time, effort, and materials needed in their production.
While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
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| Number | Date | Country | |
|---|---|---|---|
| 20130112540 A1 | May 2013 | US |
