Abstract: A method for controlling backlight of portable electronic device in hysteresis manner pre-sets the portable electronic device in a default mode and senses a background brightness. The portable electronic device is operated at a daylight mode when the sensed background brightness is larger than a first threshold. When the portable electronic device is operated at the daylight mode and the sensed background brightness is smaller than a second threshold, the portable electronic device is again operated at the default mode, where the second threshold is much smaller then the first threshold to provide hysteresis effect. Therefore, the backlight can be turned off when the background brightness is sufficient. A rapid switch between default mode and daylight mode can be prevented by the hysteresis-manner control and user dizziness caused by rapid modes switch can also be prevented.

Abstract: A method for controlling backlight of portable electronic device in hysteresis manner pre-sets the portable electronic device in a default mode and senses a background brightness. The portable electronic device is operated at a daylight mode when the sensed background brightness is larger than a first threshold. When the portable electronic device is operated at the daylight mode and the sensed background brightness is smaller than a second threshold, the portable electronic device is again operated at the default mode, where the second threshold is much smaller then the first threshold to provide hysteresis effect. Therefore, the backlight can be turned off when the background brightness is sufficient. A rapid switch between default mode and daylight mode can be prevented by the hysteresis-manner control and user dizziness caused by rapid modes switch can also be prevented.

Abstract: An illuminating device for hand-held bar code reader that installs a light emitting device next to a reading window of a bar code reader. The light projection direction of the light emitting device is parallel to a scanning light emitted from the interior of the reading window. The light emitting device is controlled by a switch. The switch is a two-stage press-type switch. When the switch is pressed into a first stage, the light emitting device is activated to illuminate. When the switch is pressed into a second stage, the scanning light is emitted for bar code reading. Thereby, the bar code can be read in an environment with insufficient light.

Abstract: A bar code scanner with lighting device for illumination is disclosed, The bar code scanner includes a case plate, a housing, a main body and a lighting device. The housing has an opening formed in the front end thereof. The main body has a circuit board, a scanning unit and a scanning window. The main body is accommodated in the housing with the case plate covered thereon. The lighting device electrically connected with the circuit board to provide the illumination for reading a bar code pattern. Therefore, it is more convenient for the operation of the bar code scanner in an insufficiently lighting environment.