Abstract: A zoom lens includes, from the image side to the subject side, a first lens group having a negative overall power and a second lens group having a positive overall power. The lens groups are movable relative to each other in opposite directions so as to increasingly and decreasingly change an axial air spacing between the two lens groups, thereby continuously varying the focal length of the zoom lens. The zoom lens satisfies the following conditions:2.5<bf.sub.w /f.sub.w, and0.68<f.sub.1 /f.sub.2 <0.98,where bf.sub.w is the axial distance measured from the rearmost surface of the second lens group to a conjugate point at a long conjugate length of the second lens group for the wide-angle end, f.sub.w is the overall focal length of the zoom lens for the wide-angle end, f.sub.1 is the overall focal length of the first lens group, and f.sub.2 is the overall focal length of the second lens group.

Abstract: An endoscope apparatus having an end section provided with an image forming optical system, a self-scanning type solid state image pickup device at which cyan and yellow color filters are positioned alternately to correspond to respective picture elements of the image pickup device, and a light guide. When green light is emitted from the light guide to an object, image signals corresponding to the green component of the object are picked up from all picture elements. When white light is emitted, cyan component image signals are picked up from the picture elements where the cyan filters are positioned, and yellow component signals form those where the yellow filters are positioned.

Abstract: A color video endoscope system including a light source, color wheel and light guide for directing sequential fields of red, green and blue (RGB) light into a cavity, a solid state image sensor for transmitting a signal in response to the intensity of the reflected fields of light, a video processor for converting the signal from the image sensor into a composite RGB video signal compatible with a color monitor, and a plurality of electronic color filters for altering the true color of the image on the monitor.

Abstract: A compact optical imaging system with application to a viewing head of an endoscope. A lens assembly gathers and focuses light into parallel rays which are turned 90.degree. from the lens assembly optical axis. A planar image sensor is oriented parallel to the lens assembly optical axis and receives the light which has been turned. The light enters a glass plate serving as the back side of the image sensor and impinges on active light-sensitive elements on a silicon layer deposited on the glass plate. A substrate is bonded on the silicon layer and supports circuitry for buffering and driving signals to and from the image snsor. The substrate has a plurality of slots aligned with the bonding pads of the image sensor to permit electrical connection between the buffering and driving circuitry and the image sensor.

Abstract: An endoscope subsystem, for a video endoscope system of the type having an insertion tube employing a video sensor, an optical imaging system for forming images on the sensor, and a video display for displaying an image derived from the sensor, which subsystem is for electronically correcting the side-to-side image reversal of the image represented by signals derived from the sensor in response to light intensities in a scene viewed by the endoscope, which reversal may result from the use of a folded optic imaging system in order to achieve compactness in the distal end of the endoscope.

Abstract: A color video endoscope system having a control unit compatible with various endoscopes. Each endoscope generates unique signals to the control unit to optimize the clocking out of data from the solid state image sensor, to optimize the processing of data received from the image sensor, and to identify the size and location of the image formed on the image sensor so as to control the image formed on the monitor. The control unit generates alternating fields of red, green and blue light through the endoscope light guide with blank fields between the color fields, during which time data is clocked out of the image sensor, thereby preventing image "smear" caused by immediately successive color fields.