Abstract: Groove formation portions that define insertion grooves are located in two opposing inner sides of an opening of a main cover. Engagement shafts are located on side portions of the sub-cover that oppose the inner sides. The engagement shafts are insertable into the insertion grooves from an outside and have a thickness that is larger than a groove width of the insertion grooves. The groove formation portions are elastic and deformable to allow insertion of the engagement shafts when the engagement shafts are inserted from the outside. The groove formation portions elastically return to their original forms after insertion of the engagement shafts to engage the engagement shafts and restrict separation of the engagement shafts in a reverse direction. The groove formation portions support the sub-cover to allow the sub-cover to open while engaged with the engagement shafts.

Abstract: A luminance control device and a luminance control method for controlling luminance of a light emitting member are provided in order to reduce the amount of information to be stored while preventing the user from feeling uncomfortable. The CPU divides by the interpolation division number a value obtained subtracting the reference duty ratio from the reference duty ratio so as to calculate an interpolation variation width, and integrates the interpolation variation width to the reference duty ratio every time the interpolation period elapses, and the variation width in the luminance of the LED is therefore reduced, preventing users to feel uncomfortable, which allows for suppressing the amount of information to be stored.

Abstract: Groove formation portions that define insertion grooves are located in two opposing inner sides of an opening of a main cover. Engagement shafts are located on side portions of the sub-cover that oppose the inner sides. The engagement shafts are insertable into the insertion grooves from an outside and have a thickness that is larger than a groove width of the insertion grooves. The groove formation portions are elastic and deformable to allow insertion of the engagement shafts when the engagement shafts are inserted from the outside. The groove formation portions elastically return to their original forms after insertion of the engagement shafts to engage the engagement shafts and restrict separation of the engagement shafts in a reverse direction. The groove formation portions support the sub-cover to allow the sub-cover to open while engaged with the engagement shafts.

Abstract: A luminance control device and a luminance control method for controlling luminance of a light emitting member are provided in order to reduce the amount of information to be stored while preventing the user from feeling uncomfortable. The CPU divides by the interpolation division number a value obtained subtracting the reference duty ratio from the reference duty ratio so as to calculate an interpolation variation width, and integrates the interpolation variation width to the reference duty ratio every time the interpolation period elapses, and the variation width in the luminance of the LED is therefore reduced, preventing users to feel uncomfortable, which allows for suppressing the amount of information to be stored.

Abstract: A vehicle interior illumination device includes an illumination lamp that is provided in a vehicle interior and is configured to be turned on to illuminate the vehicle interior, a detector that detects a condition to have the illumination lamp to be turned on, and a controller that controls a lighting of the illumination lamp. When the condition is detected by the detector, the controller lights the illumination lamp with a first light amount and when the condition is not detected by the detector, the controller lights the illumination lamp with a second light amount smaller than the first light amount.

Abstract: A vehicle interior illumination device includes an illumination lamp that is provided in a vehicle interior and is configured to be turned on to illuminate the vehicle interior, a detector that detects a condition to have the illumination lamp to be turned on, and a controller that controls a lighting of the illumination lamp. When the condition is detected by the detector, the controller lights the illumination lamp with a first light amount and when the condition is not detected by the detector, the controller lights the illumination lamp with a second light amount smaller than the first light amount.