JPS6079323A - Endoscope video system - Google Patents

Abstract

PURPOSE:To realize an optimum brightness of a picture by determining a photometric system in accordance with brightness of the center part of the picture, and adjusting a light quantity in accordance with its photometric value. CONSTITUTION:An output signal of a CCD20 has some blanking period between each frame, and in this period, low-pass filters 44, 46 are reset. As a result, the low-pass filter 44 integrates a signal of the center part of a picture, a photometric value of the center part is obtained in its output, the low-pass filter 46 integrates a signal of the circumferential part of the picture, and a photometric value of the circumferential part is obtained in its output. Both outputs are compared by a comparator 50, a selector 52 is controlled so that a brighter one is selected, and in case the center part is brighter, it is decided to be a plane- shaped object to be photographed, and it is made a center part photometry. On the contrary, in case the circumferential part is brighter, it is decided to be a pipe-shaped object to be photographed, and it is made a circumferential part photometry. An output signal of this selector 52 is supplied to a diaphragm driving circuit 34, and in accordance with a photometric value, a diaphragm value of an aperture blade 32 is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an endoscopic imaging system that has a solid-state image sensor at the objective end of an endoscope and compares an internal image on a monitor.

[Prior art]

In general, an endoscope is a light source for illuminating the inside of the body, endoscope optics 1#! It has a large number of fibers called image guide optical fibers that transmit the optical image from the objective lens to the eyepiece lens. In recent years, with the development of solid-state imaging devices such as charge-coupled devices (CODs), endoscopic imaging systems have been developed that use solid-state imaging device CRT monitors instead of conventional image guides and eyepieces. There is. Movie 1# like this! In the 7-stem system, the brightness of the optical image incident on the image sensor must be constant regardless of the brightness (reflectance) of the observation site. For this purpose, the amount of illumination light from the light source must be adjusted depending on the reflectance of the observation site. Usually, a light source is separately provided as a light source device outside the endoscope, and light from the light source device is irradiated into the body through a large number of six-dimensional fibers called an optical light guide inside the endoscope. In this case, the amount of light from the light source is adjusted using an aperture. Aperture blades are provided in front of the lamp in the light source device, that is, between the lamp and the light guide, and the aperture is manually adjusted while checking the brightness of the image on the monitor. As described above, conventional light amount adjustment was performed manually, which had the disadvantage of being time consuming. This is particularly problematic when the observation site changes frequently.

〔the purpose〕

The purpose of this invention is to optimize the brightness of the screen.
An object of the present invention is to provide an endoscopic imaging system that automatically adjusts the amount of illumination light.

[Roughly broken] This purpose is to use a first photometer that measures the brightness of the center of the screen from the output signal of the solid-state image sensor, and a solid-state sensor that measures the brightness of a predetermined portion of the screen according to the output signal of the first photometer. This is realized by an endoscopic imaging system that has a second photometric means that receives an output signal from an image sensor, and adjusts the amount of illumination light according to the output signal of the second photometric device.

〔Example〕

An embodiment of the endoscopic imaging system according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of this implementation. This system basically includes an endoscope 10, a light source device 12, and a CRT monitor 14. 16 is disposed within the endoscope 10 from the connection end with the light source device 12 to the objective end of the endoscope. An objective lens 18 is provided at the objective end to obtain an optical image of the inside of the body. A solid-state image sensor (for example, C
CD) 20 is placed, and the optical image obtained by the objective lens 18 is converted into an electrical signal. The light-receiving surface of the CCD 20 has R, G, and B color sensors for color imaging. - A color separation filter 22 is provided in which components are arranged in a mosaic pattern. In the endoscope 1O, an electronic viewfinder 24 consisting of a 1-inch white dot CRT or the like is placed in the place where an eyepiece was conventionally placed. This electronic viewfinder 24 is provided to enable the same operation mode as the conventional endoscope, that is, to determine the composition while placing the eye on the eyepiece, and is not necessary. There is no need to provide one. Alternatively, only the electronic viewfinder 24 may be provided and the CRT monitor 14 may be omitted.

The light source device 12 includes a lamp 26, a video circuit 28, an automatic dimming circuit 30, an aperture blade 32, and an aperture drive circuit 34. Light emitted from the lamp 26 enters the light guide 16, and an aperture blade 3 is provided between the lamp 26 and the light guide 16.
2 is arranged so that the amount of light incident on the light guide 16 can be adjusted. The output signal of the C0D 20 is input to the video circuit 28, and the R, G, and B component signals are input to the CRT monitor 14 and the automatic dimming circuit 30. The output signal of the automatic light control circuit 30 is supplied to an aperture drive circuit 34. A G component signal output from the video circuit 28 is supplied to the electronic viewfinder 24.

Details of the automatic light control circuit 30 are shown in FIG. The R2O,B component signals are supplied to an adder circuit 40 and added together. The output of the adder circuit 40 is selectively supplied to one of low-pass filters 44 and 46 consisting of an OR circuit serving as an integrating means via a selector 42 with two outputs. Switching of the selector 42 is controlled by the output of the photometric pattern generator 48. Low pass filter 44
．． The output of 46 is input to a comparator 50° and a selector 52 of two-manual output. Switching of the selector 52 is controlled by the output of the comparator 50. The output of the selector 52 is supplied to the aperture drive circuit 34. The photometric pattern generator 48 is constituted by a ROM, and stores data for distributing part of the output of the adder circuit 40 for one frame to the low-pass filter 44 and the remaining low-pass filter 46.

To explain the operation of this embodiment, first, the principle will be explained. To perform automatic light control, the brightness of the screen can be calculated from the output signal of the CCD 20, and the aperture can be determined based on this brightness. Here, the photometry method that measures the brightness of the screen is not always constant, but is determined depending on the type of subject. The types of objects to be photographed can be divided into tubular objects such as the intestine and flat objects such as the stomach wall. A characteristic of flat objects is that the light distribution may be dimmed at the periphery, making the center of the screen bright and the periphery dark. Furthermore, in this case, the observation site is generally located in the center. Therefore, if full-plane photometry is performed on a planar object, the observed area in the center will be overexposed. Therefore, the central partial metering method is preferable for planar objects. Conversely, in a tubular object, the center is dark and the tube wall (periphery) is bright. Furthermore, since the observation site of the tubular object is the stomach wall, it is the peripheral area.

Therefore, in this case, the central portion photometry method results in overexposure of the peripheral observation area.

Therefore, for tubular objects, it is preferable to use the peripheral partial photometry method or the overall average photometry method. In this embodiment, the type of subject is determined by comparing the brightness at the center of the screen with the brightness at the periphery of the screen. For tubular objects, a peripheral partial metering method is adopted.

Next, the operation of this -implementation sequence will be explained in detail.

An RGB composite signal for each frame is continuously output from the CCD 20, and R, () is output via the video circuit 28.
The signal is made into an IB component signal and displayed as a moving image on the CRT monitor 14.

These R, G, and B component signals are transmitted to the automatic dimming circuit 30.
The signals are also supplied to the adder circuit 40 and added together. The output signal of the adder circuit 40 indicates the brightness of each pixel. The photometric pattern generator 48 is in charge of reading and outputting signals of one frame from the CCD 20, and sends the signal components of the pixels in the center to the low-pass filter 44, and sends the signal components of the pixels in the other riverside parts to the low-pass filter 46. A control signal is supplied to the selector 42 so as to distribute the signals to the selector 42. The photometric pattern generator 4B is made of a ROM having the same memory element configuration as the pixel configuration of the C0D20, and different identification information is written in the memory element corresponding to the pixel corresponding to the center of the screen and the other memory elements. This is achieved by synchronizing the readout of the CCD 20 and the readout of the ROIJ in the same order.

Here, the output signal of the C0D 20 has some blanking period between each frame, and the low-pass filters 44 and 46 are reset during this period. As a result, the four-pass filter 44 integrates the signal at the center of the screen and outputs the photometric value at the center, and the low-pass filter 46 integrates the signal at the periphery of the screen and outputs the photometric value at the periphery. Both obtained outputs are compared by a comparator 50, and a selector 52 is controlled to select the brighter one based on the output of the comparator 50.

That is, if the center part is brighter, it is determined that the object is planar, and central part photometry is performed. Conversely, if the peripheral area is brighter, it is determined that the object is tubular, and peripheral partial photometry is performed. The output signal of the selector 52 is supplied to the aperture drive circuit 34, and the aperture value of the aperture blade 32 is determined according to the photometric value.

In this manner, according to this implementation sequence, the type of subject is automatically determined, and the optimal photometry method is determined accordingly. Then, the aperture adjusts the light value according to this photometric value. Therefore, an endoscopic imaging system is provided in which the amount of illumination light is automatically adjusted according to the subject, and the brightness of the screen is optimal.

Next, a second embodiment of the invention will be described. The overall configuration of the second embodiment is the same as that of the first embodiment, and is shown in FIG.
It will be done. The second embodiment differs from the first embodiment only in the configuration of the automatic optical circuit. The details of the automatic dimming circuit of the @2 embodiment are shown in the 3rd section.
As shown in the figure. The R2O+B component signal is input to summing circuit 60. The output of the addition circuit l11860 is supplied to one input end of a selector 62 with two inputs and one output, and to a low-pass filter 64 as an integrating means.

The other input end of the selector 62 is grounded.

Switching of the selector 62 is controlled by the output of the photometric pattern generator 66 similar to the first embodiment 1]. The output of the selector 62 is supplied to a low pass filter 68. The outputs of the low-pass filters 64 and 68 are supplied to respective input ends of a selector 70 with two inputs and one output. Selector 7
The switching of 0 is controlled by the output of the comparator 12 which compares the output of the low-pass filter 68 with the reference level vref. The output of the selector 70 is supplied to the aperture drive circuit 34.

The operation of the second implementation column will be explained. Photometric pattern generator 66
The selector 62 is switched to the adder circuit 60 side during the period when the signal component corresponding to the pixel at the center of the screen is output from the adder circuit 60, and is switched to the ground end side during the other periods. As a result, the output of the low-pass filter 68 is
'l11 original value is obtained. The type of subject is determined based on the reference level of this central portion photometric value. That is, in the case of a planar object, the central part is bright, so the central part photometric value is larger than Vref. Conversely, in the case of a tubular object, the center portion photometry value also has a smaller VrefJ:D. As a result, the selector 70 is switched to the low-pass filter 68 side in the former case, and switched to the low-pass filter 6491Q in the latter case. Since all of the 18 frames of l frame are input to the low-pass filter 64, the overall average photometric value is obtained as the output of the low-pass filter 64. As a result, in this implementation column, the selector 70 selects the central portion photometric value for a flat object, and selects the overall average photometric value for a tubular object. selector 10
The output signal is the first fruit! Control the aperture as in the case of the heart.

In this way, Konomi/A! With IeilJ, the amount of light is adjusted depending on the type of subject and the photometric value for J, providing an optimal system for displaying the palm of your hand on the screen.

〔Effect of the invention〕

As explained above, according to the present invention, the photometry method is determined according to the brightness at the center of the screen, and the amount of light is adjusted according to the photometry value obtained by this photometry method, so that the screen can be Brightness can always be optimized.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the first embodiment of the internal reflection system according to the present invention, Fig. 2 is a detailed circuit diagram of the automatic dimming circuit in this embodiment, and Fig. 3 is a detailed circuit diagram of the automatic dimming circuit in the second embodiment. FIG. 3 is a detailed circuit diagram of an automatic dimming circuit. 14...CRT monitor, 16...Light guide, 1
8...Objective lens, 20...CCD124...Electronic viewfinder, 26...Lamp, 30...Automatic light control circuit, 32...Aperture blade. Applicant's representative Patent attorney Atsushi Tsuboi Figure 2, Continuation of Figure 3, page 4 [Part] Inventor Shin Kato - [Part] Inventor Hagiwara 0 hostility Akira Ka Tadashi Fuji @ Inventor Hiroki Hibino @ Inventor Akifumi Ishikawa

Claims (1)

[Scope of Claims] (A solid-state image sensor provided in an objective section of an endoscope; a first photometer that measures brightness at the center of the screen from an output signal of the solid-state image sensor; A second photometric device that determines the brightness of a predetermined portion of the screen according to an output signal of the device from an output signal of the solid-state image sensor, and a light source device that adjusts the amount of light in accordance with the output signal of the second photometric device. A non-direction endoscope video system. (2) The second photometering means measures the brightness of the central part of the screen or the peripheral part of the screen according to the output signal of the first photometry means. The endoscopic imaging system according to item 1. (3) The second photometric means adjusts the brightness of the entire screen from the center of the screen according to the output signal of the first photometric means. An endoscopic imaging system according to claim 1.