JP2576596Y2 - Light amount adjusting device for TV endoscope - Google Patents

Description

[Detailed description of the invention] [Industrial application field] In the invention, the light amount diaphragm member of the TV endoscope is automatically set using the R, G, B field sequential video signal from the solid-state imaging device. The present invention relates to a light amount adjusting device for a TV endoscope.

[Conventional technology]

As is well known, a TV endoscope has a light guide fiber bundle as an illumination system, an objective lens and a CCD as an imaging system.
The solid-state image sensor is illuminated with the illumination light from an external light source through a light guide fiber bundle, the video signal from the solid-state image sensor is taken out, processed, and displayed on a TV monitor. Things. In addition, since the brightness of the subject changes based on the distance from the subject and the like, the TV endoscope uses a light guide according to the change in the brightness of the subject so that an image with a constant brightness is always displayed. A field stop video signal of an R (red) signal, a G (green) signal, and a B (blue) signal obtained from the solid-state image sensor is formed by using a light amount stop member arranged between the incident end of the fiber bundle and the light source. It is configured to perform opening and closing control based on.

[Problems to be solved by the invention]

However, the above-described light amount adjusting device for a TV endoscope has a difference in output signal level between the R signal, the G signal, and the B signal obtained from the solid-state image sensor due to the characteristics of the solid-state image sensor. In addition, because of the field sequential video signal, there is one field delay in the field sequential system. For these reasons, there are drawbacks that the change of the video signal for controlling the light amount diaphragm member is large and the control response speed is slow.

An object of the present invention is to eliminate these drawbacks and to perform appropriate light amount adjustment according to the brightness of a subject.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a solid-state imaging device for a light amount adjusting means such as a light amount stop member disposed between an incident end of a light guide fiber bundle for illumination of a TV endoscope and a light source. In the light amount adjusting device for a TV endoscope configured to be controlled by the video signal from the TV endoscope, the R signal, the G signal, and the B signal included in the field sequential type TV endoscope are provided.
Each signal output of the signal field memory circuit is D / A-converted in each signal system, R, G, and B are each given a predetermined weight, and each signal is added so that the loop gain becomes substantially constant. Light amount adjustment control such as control of the light amount stop member by the signal is performed.

[Action]

The light amount adjusting device for a TV endoscope configured as described above has a small change between fields of a video signal for controlling a light amount diaphragm member, that is, for controlling light amount adjustment,
The control response speed can be increased, and the above R,
According to the weighted ratio of each of the G and B video signals, the ratio of each contribution to the light amount adjustment control can be made substantially constant.

〔Example〕

Hereinafter, an embodiment of a light amount adjusting device for a TV endoscope according to the present invention will be described in detail with reference to the schematic block diagram shown in FIG.

In FIG. 1, A shows a TV endoscope, B shows a light source device,
The endoscope A includes a fiber bundle 1 for a light guide as an illumination system, an objective lens 2 as an imaging system, and a CCD.
It has a well-known configuration including the solid-state imaging device 3 as described above. The light source device B is a light source 4, such as a xenon lamp, disposed opposite to the incident end 1a of the light guide fiber bundle 1, and is disposed in an optical path between the light source 4 and the incident end 1a of the light guide fiber bundle 1. The light amount aperture blade 5 thus set, a servomotor 6 for controlling the light amount aperture blade 5 to enter and exit the optical path, a color disk 7 for converting the light from the light source 4 into R, G, and B light, and a color circle It has a servomotor 8 for controlling the plate 7. As control of the servo motor 6,
An amplifier 9 for amplifying a video signal from the solid-state imaging device 3, an A / D converter 10 for converting an output of the video amplifier 9 into a digital signal, and an A / D converted output signal for each of R, G, and B fields. Via field changeover switches 11, 11, and 14, D / A converters 15, 16, which convert output signals from the respective field memories 12, 13, 14 into analog signals. 17, D / A converter 15,16,17
R, G, and B output signals are each weighted with a predetermined value, and an addition circuit 18 that adds the weighted signals, a comparison circuit 19 that receives a signal from the addition circuit 18 from one input terminal, A position detecting potentiometer 20 for inputting a rotational position signal of the servo motor 6 from the other input terminal of the comparison circuit 19 in conjunction with the motor 6, and a comparison circuit 19
And an amplifier 21 for driving the servo motor 6 according to a comparison signal. A video output amplifier 22 is provided for image output.

The light amount adjusting device for a TV endoscope configured as described above is
Light guide fiber bundle 1 to color disk 7
With respect to light that is controlled and output in the R, G, and B fields in sequence, the video signal in the R, G, and B fields output from the solid-state imaging device 3 is amplified by the video amplifier 9 and then A / A D
The signal is converted into a digital signal by the converter 10 and the changeover switch 11
Are stored in the field memories 12, 13, and 14 for R, G, and B for each field. Field memory 12, 13, 14
R, G, and B digital video signals read out from each of the fields are converted into analog signals by respective D / A converters 15, 16, and 17, and then added by an adder circuit 18 to output R, G, and B signals, respectively. Is given a predetermined weight and added. The video signal to which R, G, and B have been added is compared by the comparison circuit 19 with the servo motor 6.
The difference from the rotational position detection potentiometer 20 is detected.
In accordance with the detection level, the diaphragm blades 5 are servo-controlled to enter and exit the optical path, and the amount of illumination is automatically positioned so that the brightness of the subject becomes constant.

[Effect of the invention]

As is clear from the above, according to the present invention
Light control device for TV endoscope is obtained from solid-state image sensor
By eliminating the difference in output signal level due to the characteristics of the solid-state image sensor between the R, G, and B video signals, and reducing the change in the video signal due to the field delay in the field sequential method, the amount of light control by the aperture stop member is reduced. The response speed can be increased, and the ratio of each contribution to the light amount adjustment control can be made substantially constant according to the weighted ratio of the R, G, and B video signals.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an embodiment of a light amount adjusting device for a TV endoscope according to the present invention. 1: fiber bundle for light guide, 3: solid-state image sensor,
4: Light source, 5: Aperture blade, 6: Servo motor, 9: Video amplifier, 10: A
/ D converter, 11: changeover switch, 12, 13, 14: field memory, 15, 16, 17: D / A converter, 18: addition circuit, 19: comparison circuit, 20:
Potentiometer for position detection, 21: amplifier.

Claims (2)

(57) [Scope of request for utility model registration] 1. A TV endoscope comprising at least a light source and a light amount control means for controlling a light amount incident on an incident end of the light guide fiber bundle of a TV endoscope having a light guide fiber bundle for illumination and a solid-state imaging device. In the light amount adjusting device for an endoscope, R, G,
A field memory circuit for storing video signals in the order of B fields, a D / A conversion circuit for converting video signals read from these field memory circuits into analog signals, and R, An adding circuit for adding the G and B video signals with predetermined weights so that the loop gains become substantially constant; and an automatic circuit for automatically setting the light amount control means based on the video signals obtained by the adding circuits. A light amount adjusting device for a TV endoscope, comprising a level setting means. 2. A television endoscope having at least a light source, a light guide fiber bundle for illumination and a solid-state imaging device, and disposed between an incident end of the light guide fiber bundle and a light source, and obtained from the solid-state imaging device. A field memory circuit for storing R, G, and B field sequential video signals obtained from the solid-state imaging device in a TV endoscope light quantity adjustment device including a light quantity stop member that is controlled to open and close based on a video signal received And the respective D / A converters that convert the video signals read from these field memory circuits into analog signals, and the loop gains of the R, G, and B video signals converted to these analog signals become almost constant And a video signal obtained by the addition circuit.
A light amount adjusting device for a TV endoscope, comprising an automatic level setting means for automatically setting the light amount stop member.