Electronic-endoscope light source unit for setting shading period

Abstract

The present invention is a unit for eliminating the fluctuation of luminous energy reduction by keeping the response time of a shading mechanism constant even if a diaphragm opening degree differs when reading every pixel by setting a shading period. This unit is provided with a shading mask having a quadrangular or V-shaped opening and moves a shading shutter in the horizontal direction perpendicular to the vertically moving direction of a diaphragm plate. Therefore, a shading period is set in accordance with the constant response time of the shading shutter and the rate of luminous energy reduction becomes constant. Moreover, a high-quality static image having a stable brightness can be obtained by reading the signal of every pixel obtained by a CCD through one-time exposure while using the shading period and then pixel-mixing signals. Furthermore, it is possible to use the Archimedean spiral for the outer periphery of the diaphragm plate or the shading shutter.

Description

[0001] This application claims the priority of Japanese Patent Application No. 10-96785 filed on Mar. 25, 1998 and Nos. 10-103792 and 10-103793 filed on Mar. 30, 1998 which are incorporated herein by reference.[0002] 1. Field of the Invention[0003] The present invention relates to an electronic-endoscope light source unit, particularly to a structure for adjusting the luminous energy of video signals for reading every pixel by an electronic endoscope for reading the signal of every pixel accumulated in an image pickup device by setting a shading period.[0004] 2. Description of the Prior Art[0005] In the case of an electronic endoscope system, a video signal is formed by reading electric charges accumulated by a photoelectric conversion device in pixels by a CCD (Charge Coupled Device) serving as a solid-state image pickup device. Moreover, in the case of a simultaneous-type electronic endoscope system, color filters are arranged on the CCD in pixels and thereby, a color image can be...

AI Technical Summary

Benefits of technology

[0017] Therefore, the luminous energy when setting a shading period is reduced to 94% of the normal luminous energy (luminous energy reduction of 6%) and also, the brightness of an image lowers by 6%.

[0035] According to the above structure, the rotation axis of the fan-shaped shading shutter of the full-closed shading mechanism is set to the V-shape intersection of the opening of the shading mask and the shading shutter rotates from one side toward the other side of the V shape of the opening. However, the diaphragm plate of the diaphragming mechanism linearly moves from the V-shaped-opening expanded side (upper side) toward the intersection. Thereby, even if the diaphragm plate moves to any diaphragm position, the shading shutter rotates by the V-shape opening angle whenever completely shading a light-source luminous flux and thereby, the luminous-flux shading time, that is, the response time of the shading shutter becomes constant. As a result, the luminous energy deficiency caused by the response (response delay) time becomes constant and the fluctuation of the luminous energy reduction under the exposure immediately before setting a shading period is eliminated.

Problems solved by technology

However, the above simultaneous electronic endoscope system has a problem that the quality (resolution or color shift) of, particularly, a static image is deteriorated if there is a time shift of {fraction (1 / 60)} sec between an odd-field signal and an even-field signal for forming a one-frame image and an endoscope or an object to be observed is moved during the time shift.

However, by driving a shading shutter for setting the shading period, a mechanical (such as a gear) response delay occurs.

Moreover, when adjusting the luminous energy emitted from a light source by a diaphragming mechanism, problems occur that the response time of the shading shutter changes depending on the opening state of the diaphragm and insufficient luminous energy changes.

Images