Power-saving method and device

1. A power-saving method, used in a device, comprising:

measuring, by a light sensor of the device, luminous intensity of ambient light and generating a measurement value of ambient light;

determining whether the measurement value of ambient light is greater than a threshold;

when determining that the measurement value of ambient light is less than or equal to the threshold, controlling the device to operate in a standby mode; and

when determining that the measurement value of ambient light is greater than the threshold, performing the steps of:

detecting, by a motion sensor of the device, movement in a predefined area;

generating, by the motion sensor, a motion-detection signal when detecting the movement;

controlling the device to operate in a quick-start mode when receiving the motion-detection signal, wherein when the device operates in the quick-start mode and keeps receiving the motion-detection signal, performing the steps of:

starting a timer;

switching the device from the quick-start mode to the standby mode when the timer has expired and the device is not turned on; and

determining, after the device has switched to the standby mode, whether the device receives the motion detection signal, and switching the device back to the quick-start mode when it is determined that the motion detection signal is received; and

controlling the device to operate in the standby mode when not receiving the motion-detection signal.

2. The power-saving method as claimed in claim 1 , wherein when the device operates in the quick-start mode, the method further comprises:

switching the device from the quick-start mode to the standby mode when the measurement value of ambient light is less than or equal to the threshold.

3. A power-saving device, comprising:

a light sensor, measuring luminous intensity of ambient light and generating a measurement value of ambient light;

a motion sensor, generating a motion-detection signal when detecting movement in a predefined area;

a control circuit, comprising a processor and a memory, wherein the control circuit is coupled to the light sensor and the motion sensor;

wherein the processor is configured to execute a program code stored in the memory to:

receive the measurement value of ambient light;

determine whether the measurement value of ambient light is greater than a threshold;

when it is determined that the measurement value of ambient light is less than or equal to the threshold, control the device to operate in a standby mode; and

when it is determined that the measurement value of ambient light is greater than the threshold:

detect, by a motion sensor of the device, movement in a predefined area;

generate, by the motion sensor, a motion-detection signal when the movement is detected;

control the device to operate in a quick-start mode when the motion-detection signal is received, wherein when the device operates in the quick-start mode and keeps receiving the motion-detection signal the processor:

starts a timer;

switches the device from the quick-start mode to the standby mode when the timer has expired and the device is not turned on; and

determines, after the device has switched to the standby mode, whether the device receives the motion detection signal, and switches the device back to the quick-start mode when it is determined that the motion detection signal is received; and

control the device to operate in the standby mode when the motion detection signal is not received.

4. The power-saving device as claimed in claim 3 , wherein when the device operates in the quick-start mode, the processor is further configured to execute the program code to:

switch the device from the quick-start mode to the standby mode when the measurement value of ambient light is less than or equal to the threshold.