Patent ID: 7450159
Filing Date: 2008-11-11
Classification: A61B

Abstract:
1. An image pick-up apparatus comprising: an image pick-up device which picks-up an image of a subject and outputs an image signal; a first-amplitude changing portion which varies an amplitude of the image signal outputted from the image pick-up device by varying an exposure amount of the image pick-up device; a second-amplitude changing portion which varies an amplitude of the image signal to be outputted by the image pick-up device; a comparing portion which compares an amplitude of the image signal with a value related to target amplitude; and a control portion which controls the first- and second-amplitude changing portions based on the comparison result of the comparing portion so that an observed image of the subject displayed on display means has a desired brightness, and changes the amplitude of the image signal in order to approximate to the target amplitude, wherein when the control portion controls the operation for increasing the amplitude of the image signal to be inputted to the display means to increase the brightness of the observed image of the subject on the display means based on the comparison result, the control portion performs the control for varying the amplitude by the first-amplitude changing portion prior to the control for varying the amplitude by the second-amplitude changing portion until the value for varying the amplitude reaches a first value, and performs the control for varying the amplitude of the image signal by the second-amplitude control portion upon controlling the operation for increasing the amplitude of the image signal when the value reaches the first value and when further increasing the amplitude of the image signal, and when the control portion controls the operation for reducing the amplitude of the image signal inputted to the display means to decrease the brightness of the observed image of the subject displayed on the display means, the control portion performs the operation for controlling the amplitude by the second-amplitude control portion prior to the operation for controlling the amplitude of the image signal by the first amplitude changing portion until the value for varying the amplitude reaches a second value, and performs the operation for varying the amplitude of the image signal by the first-amplitude control portion when farther reducing the amplitude of the image signal and when the value reaches the second value.