| 摘要 |
In an endoscopic apparatus, when the dynamic range expansion on/off switch is turned on, a CPU changes a switch from one contact over to another. Red, green, and blue digital signals sent from a knee and gamma circuit are output to respective dynamic range expanding circuits. Thus, the dynamic ranges for the digital signals are expanded. On the other hand, when the CPU changes another switch from one contact over to the other, a light adjustment signal output from an operational amplifier is then driven to a level causing a diaphragm in a light source unit to open further. Consequently, an increased amount of illumination light is supplied to the incident end of a light guide running through an endoscope. Thus, when a dynamic range is expanded, a halation effect will not occur in imaging of an object located at a point near the distal end of the endoscope. Moreover, insufficiency of illumination light will not occur in the imaging of an object located at a point far from the endoscope distal end. The dynamic range can therefore be expanded efficiently. An endoscopic image of the interior of a body cavity can be viewed with the body cavity set to a desired brightness level all points ranging from a near point to a far point within the body cavity.
|
