Abstract: A control circuit computes relative horizontal and vertical inclination angles between a screen and a projector by a line-type passive range-finding device. A display driving section adjusts a projection optical system including a condensing lens on the basis of the vertical and horizontal inclination angles computed by the control circuit, thereby correcting for a keystone distortion in an image projected.

Abstract: A control circuit computes relative horizontal and vertical inclination angles between a screen and a projector by a line-type passive range-finding device. A display driving section adjusts a projection optical system including a condensing lens on the basis of the vertical and horizontal inclination angles computed by the control circuit, thereby correcting for a keystone distortion in an image projected.

Abstract: To provide an image pick-up device in which a lens does not need to be driven when information corresponding to the distance to an object to be photographed is obtained by using image information output by an image pick-up part. When a control part determines that an image is darker than a prescribed value based on a luminance signal contained in image information output by an image pick-up part, the control part stores the luminance signal in the image information input from the image pick-up part while a light emitting part does not emit light and then controls the light emitting part to emit light with a prescribed quantity. The control part stores the luminance signal in the image information output by the image pick-up art to obtain the luminance difference between the two luminance signals. When the luminance difference is not larger than a prescribed value, the control part controls the light emitting part to emit light with a prescribed quantity of light.

Abstract: To reduce power consumption of an image pick-up device in which an object to be photographed is illuminated, during a period until a release switch is operated, a control part controls a light emitting part to emit a smaller quantity of light than that necessary for photographing the object. When a photographing instruction is output by the release switch, the control part controls the light emitting part to emit light with the quantity of light necessary for photographing the object.

Abstract: An alarm clock has an ambient light detector for controlling the illumination of a time displaying section. An alarm time which is selected by a user is stored in a memory. An alarm set switch is used to switch between alarm-on and alarm-off conditions. A photosensor detects the ambient light surrounding the alarm clock. The illumination of the displaying section is controlled so that the displaying section is illuminated only when the current time is within a predetermined time zone before the alarm time set by the user, the alarm set switch is in the alarm-on condition and the detected ambient light is below a predetermined level. The illumination of the displaying section is also controlled so that the display is illuminated while an alarm sound is being generated.