Patent Application
20070279811
The invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein:
As shown in
The setting unit 210 is used for setting a predetermined period (T). The setting unit 210 is a setting circuit composed of a resistor and a capacitor. The predetermined period (T) is determined by the resistance of the resistor and the capacitance of the capacitor. That is to say, the predetermined period (T) can be changed according to actual requirements by changing a charging and discharging time value of the resistor and the capacitor.
The processing unit 211 is electrically connected to the operating unit 20 and the setting unit 210. The processing unit 211 outputs a trigger signal to turn on/off the electronic device when receiving the on/off signal output by the operating unit 20 for the first time during the predetermined period (T). On the other hand, when receiving another on/off signal during the predetermined period (T), the processing unit 211 no longer outputs any trigger signal. More particularly, the processing unit 211 produces a single-pulse signal (PWRBT) which is a low pulse signal to trigger the SOC 22 of the electronic device to start a power on timing and do a corresponding power switching operation when receiving the on/off signal (PWIN) of the power button for the very first time during the predetermined period (T). In the present embodiment, the processing unit 211 is a signal processor, for example, a dual retriggerable monostable multivibrator typed as DM74LS123; additionally, the power of the processing unit 211 (the signal processor) is provided by the electronic device or an extra power supply.
A preferred circuit structure of the protection device 2 is illustrated in the following description in conjunction with
As shown in
The processing unit 211 is a signal processor 212. A power (PWR2) is further provided for the signal processor 212. In the present embodiment, the signal processor 212 is a dual retriggerable monostable multivibrator typed as DM74LS123.
As shown in
One end of a resistor (R1) of the setting unit 210 is connected to the power (PWR2), and the other end of the resistor (R1) is connected to a pin (Rext/Cext1) of the DM74LS123; one end of a capacitor (C1) is connected to a pin (Cext1) of the DM74LS123, and the other end of the capacitor (C1) is connected to the pin (Rext/Cext1) of the DM74LS123.
It should be noted that in the prior art a single-low-pulse signal is produced by the operating unit 20 when the user presses the operating unit 20 of the electronic device. However a plurality of multi-low-pulse signals which may result in circuit damage, misoperation and downtime of the electronic device are produced if the user continuously presses the operating unit 20.
As shown in
The functions of the signal processor (DM74LS123) 212 are described as follows: when the input pins (B1) and (CLR1) are high (connected to the power PWR2), if the input pin (A1) produces a first falling-edged signal, the output pin (/Q1) is triggered to output a low-pulse signal, which has a width calculated based on the resistor (R1) and the capacitor (C1) of the setting unit 210; and the output pin (/Q1) is no longer triggered by continuous high to low edges of the input pin (A1) in the predetermined period set by the setting unit 20. In other words, only the first falling-edged signal of the on/off signal (PWIN) can trigger a low-pulse signal (PWRBT) even if the on/off signal (PWIN) has a plurality of falling-edged signals (produced by mechanical bounce or continuous pressing the operating unit 20).
As a result, the protection device of the present invention can eliminate the button debounce caused by mechanical bounce or manmade bounce through the processing unit which is a dual retriggerable monostable multivibrator typed as DM74LS123 and a setting unit which is consisted of a resistance and a capacitance, and change debounce time range by changing the charging and discharging time value of the resistance and the capacitance. Therefore, the present invention can eliminate not only mechanical bounce but also manmade bounce through the simple circuit structure; meanwhile, software controlling is not needed by using the protection device of the present invention, thus the debounce program can also be omitted to simplify the software design of the electronic device.
In summary, the foregoing descriptions are only the preferred embodiment and not restrictive of the technical scope of the present invention. The essential technical contents of the present invention are widely defined in the appended claims. All embodiments or methods accomplished by others which are the same as the definitions of the following claims or other equivalents should be considered as falling within the scope of the claims.
