Digital photo frame with power saving function and related power saving method
A digital photo frame having power saving functions includes a display panel, a power generation unit for switching a system power according to a power control signal, a user detection unit installed on the display panel for detecting whether a user exists within a specific range to generate a user detection signal, a central processing unit for adjusting backlight intensity of the display panel when the system power is provided by the power generation unit according to the user detection signal and for generating a power switch-off signal when the backlight intensity of the display panel is turned off according to the user detection signal, and a power control unit for generating the power control signal to switch off the system power when the backlight intensity of the display panel is adjusted to be switched off according to the power switch-off signal.
1. A method of saving power for a digital photo frame, the method comprising:
computing a first idle time of the digital photo frame according to a user trigger signal and determining whether the first idle time is greater than a first default value;
switching on a passive infrared sensor when the first idle time is greater than the first default value, wherein the passive infrared sensor detects whether a user exists within a specific range by detecting changes in infrared radiation occurring when there is movement by the user whose temperature is different from surroundings of the digital photo frame, to generate a user detection signal;
computing a second idle time of the digital photo frame according to the user detection signal indicating that the user is not within the specific range or the user trigger signal and determining whether the second idle time is greater than a second default value;
switching off a backlight of a display panel on the digital photo frame when the second idle time is greater than the second default value;
computing a third idle time of the digital photo frame according to the user detection signal indicating that the user is not within the specific range or the user trigger signal and determining whether the third idle time is greater than a third default value; and
switching off a system power of the digital photo frame when the third idle time is greater than the third default value.
2. The method of claim 1 further comprising:
generating a power-saving warning signal for reminding users that the digital photo frame has entered a power saving process when the first idle time is greater than the first default value.
3. The method of claim 2 further comprising:
switching on the system power of the digital photo frame and the backlight of the display panel again and switching off the passive infrared sensor according to the user detection signal generated by the passive infrared sensor or the user trigger signal after the system power of the digital photo frame is switched off.
4. The method of claim 3 , wherein the user trigger signal comprises:
a clock trigger signal generated by a clock generator according to a predetermined time;
a power trigger signal generated by a power switch; and
a plurality of functional button trigger signals respectively generated by a plurality of functional buttons.
5. A method of saving power for a digital photo frame, the method comprising:
computing a first idle time of the digital photo frame according to a user trigger signal and determining whether the first idle time is greater than a first default value;
switching on a passive infrared sensor and dimming backlight intensity of a display panel of the digital photo frame when the first idle time is greater than the first default value, wherein the passive infrared sensor detects whether a user exists within a specific range by detecting changes in infrared radiation occurring when there is movement by the user whose temperature is different from surroundings of the digital photo frame, to generate a user detection signal;
computing a second idle time of the digital photo frame according to the user detection signal indicating that the user is not within the specific range or the user trigger signal and determining whether the second idle time is greater than a second default value;
determining whether the backlight intensity of the display panel is dimmed to be off when the second idle time is greater than the second default value;
computing a third idle time of the digital photo frame according to the user detection signal indicating that the user is not within the specific range or the user trigger signal after the backlight intensity of the display panel is dimmed to be off and determining whether the third idle time is greater than a third default value; and
switching off a system power of the digital photo frame when the third idle time is greater than the third default value.
6. The method of claim 5 further comprising:
dimming the backlight intensity of the display panel again when the backlight of the display panel is not yet dimmed to be off.
7. The method of claim 6 further comprising:
switching on the system power of the digital photo frame and the backlight of the display panel again and switching off the passive infrared sensor according to the user detection signal generated by the passive infrared sensor or the user trigger signal after the system power of the digital photo frame is switched off.
8. The method of claim 7 , wherein the user trigger signal comprises:
a clock trigger signal generated by a clock generator according to a predetermined time;
a power trigger signal generated by a power switch; and
a plurality of functional button trigger signals respectively generated by a plurality of functional buttons.