JPH0321888B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an endoscopic photographing device, and in particular,
This invention relates to a photographic device that can arbitrarily change the photometry range.

Generally, in the case of endoscopic photography, a camera is attached to the eyepiece of the endoscope and images captured in a field frame at the eyepiece end of the endoscope's image guide. The camera's light receiving circuit measures average light. here,
The thickness of the image guide, that is, the size of the field frame, differs depending on the endoscope. Therefore, in conventional endoscope photography devices, even if the same region is photographed, the photometric value of the light receiving circuit differs depending on the type of endoscope. Therefore, in order to prevent this, in conventional devices, a variable resistor is provided in the light receiving circuit, and the level of the photometric signal output from the light receiving circuit is adjusted by passing through the variable resistor. However, such adjustment operations are troublesome for the photographer.

On the other hand, when photographing the lumen or the angle of the stomach, the illumination conditions may also differ between the central part and the peripheral part because the photographing distance is different even within the same field of view. Therefore, with average photometry, there is a risk that the photographic region that the photographer most desires to photograph and places at the center of the field of view will be underexposed. To solve this problem, it may be possible to install a center-weighted metering camera. but,
Because the endoscope's image guide is small compared to the camera screen, it is difficult to precisely align the center of the camera with the center of the image guide's field of view. Further, the mounting portion between the camera and the endoscope may also become loose due to aging, making it difficult to accurately measure light at the center of the field of view.

The present invention has been made in order to address the above-mentioned circumstances, and its purpose is to provide an endoscopic photographing device that can always take photographs with proper exposure regardless of the size of the field of view frame of the image guide or the location of the photographed part. That is.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an endoscopic photographing apparatus according to the present invention will be described below with reference to the drawings. In this embodiment, it is assumed that exposure is automatically controlled. FIG. 1 is a schematic diagram of the configuration. Endoscope 10 has a light guide 12 and an image guide 14. One end of the light guide 12 is guided to a light source 16, and the other end is guided to an objective section of an endoscope, and has an illumination window 18 at its tip. One end of the image guide 14 is arranged parallel to the light guide 12 in the objective section, and the object 1 is placed at the tip.
It has an objective lens 20 into which the light from 9 is incident. The other end of the image guide 14 is guided to the eyepiece section 22 of the endoscope, and a field frame 24 is attached to the tip. An objective lens 26 is provided within the eyepiece section 22 at the tip of a field frame 24 .

On the other hand, the camera 28 includes the eyepiece section 22 of the endoscope 10.
A concave adhesive portion 30 into which is fitted is provided. The eyepiece section 22 and the mounting section 30 each have an opening, so that an optical image of the subject in the field frame 24 is transmitted to the camera 28 side. Inside the camera 28, in order from the mounting part 30, a beam splitter 32 consisting of a half prism etc., a shutter 34,
A film 36 is provided. Beam splitter 3
2 allows a part of the light incident from the attachment part 30 to go straight to the shutter 34, and changes the direction of the remaining light by 90 degrees. A solid-state image sensor 38 is provided on the side of the beam splitter 32 and receives the redirected light. An imaging lens 40 is disposed between the beam splitter 32 and the solid-state image sensor 38, and an optical image from the beam splitter 32 is transmitted to the solid-state image sensor 3.
The image is formed on 8. Further, an optical image in the field frame 24 within the endoscope 10 is formed on a film 36 by the eyepiece 26. The solid-state image sensor 38 is a charge-coupled device, and is shown in FIG.
As shown in the figure, it has X and Y photoelectric conversion elements P (X, Y) arranged two-dimensionally in the x and y directions.
The size of the solid-state image sensor 38 is set to a size that sufficiently includes the image in the largest field of view.
The output signal of the solid-state image sensor 38 is supplied to the light source 16 via a lead wire 42.

In endoscopic photography, since the subject is in total darkness, exposure control does not have to be by controlling the shutter, but rather by controlling the light emission from the light source. In this embodiment, the exposure control is provided within the light source 16. FIG. 3 shows a block diagram inside the light source 16. The output signal of the solid-state image sensor 38 is supplied to a memory 48 via an amplifier 44 and an A/D converter 46 in series. The memory 48 includes X and Y memory cells two-dimensionally arranged in the x and y directions, corresponding to the photoelectric conversion elements P (x, y) in the solid-state image sensor 38, as shown in FIG. 2b. Data M(x,y) is stored in . The memory 48 includes a control circuit 50 that determines the input/output timing of signals.
An output signal is also provided. The output signal of memory 48 is provided to an arithmetic logic unit (ALU) 52. The output signal of the arithmetic logic circuit 52 is supplied to an exposure control circuit 54 that controls the light emission of the light source.

Next, the operation of one embodiment configured as described above will be explained. Light from the light source 16 is transmitted to the endoscope objective section via the light guide 12 and illuminates the subject 19. A subject image based on the reflected light from the subject 19 is obtained by the objective lens 20 and further transmitted to the camera 28 side via the image guide 14. When a release button (not shown) is pressed, the shutter 34 is opened, an image of the subject is projected onto the film 36, and photographing begins. Exposure information for photographing is generated by the arithmetic logic circuit 52, and in response to this, the exposure control circuit 54 blocks the light from entering the light guide 12 from the light source, thereby completing photographing.

An example of the operation of the arithmetic logic circuit 52 will be described below with reference to the flowchart shown in FIG. Here, the arithmetic logic circuit 52 is switched by a switch (not shown) to generate either an average photometric value or a center-weighted photometric value. First, in the case of average photometry, calculations as shown in FIG. 4 are performed. memory 48
Of the data M(x,y), M(0,0) is read first. As described above, since the solid-state image sensor 38 is sufficiently larger than the field of view frame 24 of the image guide, the XY pieces of data in the memory 48 also include data outside the field of view frame. Therefore, data M(x,y) is compared with a signal α of a predetermined brightness.
If the comparison result is M'(x, y), then M(x, y)
If is larger than α, M'(x, y)=1, and if smaller, M'(x, y)=0. In order to find the area within the field of view necessary to find the average photometric value, the number of data items within the field of view is determined. That is, M′(x,
A=A+M'(x, y) only when y)=1.
Here, the initial value of A is 0. In other words, A=
ΣM′(x,y). In order to add the data of the photoelectric conversion elements within the field of view frame, M ^* (x, y) = M (x,
y) × M′ (x, y), then B = B + M ^* (x, y)
seek. Here, the initial value of B is 0. That is, B=ΣM(x,y)×M′(x,y). Repeat this operation by scanning x and y respectively,
=X, y=Y is all performed for X.Y data to find C=B/A. B is the sum of the data of the charging conversion elements within the field of view frame, that is, the brightness of the subject, and A is the number of memories corresponding to the area within the field of view frame, so C obtained in this way is the average photometric value of the subject. It is.

Next, in the case of center-weighted photometry, it is determined whether the read data M(x, y) is within the field of view frame, as in the case of average light metering, and it is determined that it is within the field of view frame. Center-weighted photometry may be performed using the data obtained.

As described above, according to this embodiment, average photometry and center-weighted photometry can be performed with one light receiving element, so that any part to be imaged can be photographed with proper exposure. In addition, the light-receiving element is finely divided two-dimensionally, and an output signal is obtained from each divided part, and the level is judged based on this, so even if there is play in the mounting part of the camera and endoscope, The center of the field of view always matches the center of the camera, and only data within the field of view is calculated. Therefore, even if the size of the field frame of the image guide changes, center-weighted photometry or average photometry can be accurately obtained without level adjustment using a variable resistor.

Although this embodiment has been described with reference to automatic exposure control, manual exposure control may also be used.

As described above, according to the present invention, it is possible to provide an endoscopic photographing device that can always take images with proper exposure regardless of the size of the field frame of the image guide and the location of the photographed region.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of an endoscopic photographing device according to the present invention, FIG. 2a is a pattern diagram of the solid-state image sensing device, FIG. FIG. 3 is a block diagram of the exposure control section of this embodiment, and FIG. 4 is a flowchart showing the operation in the case of average photometry. 12...Light guide, 14...Image guide, 16...Light source, 22...Eye piece, 24...Field frame, 30... Mounting part, 32...Beam splitter, 36...Film, 38... ...solid-state image sensor,
48...Memory, 50...Control circuit, 52...Arithmetic logic circuit.

Claims (1)

[Claims] 1. An endoscope photographing device that is connected to an eyepiece of an endoscope and that photographs a subject image incident through an image guide, which has a predetermined light receiving section larger than the field of view of the eyepiece. a photoelectric conversion means for outputting a photoelectric conversion signal for each point in the light receiving section; a comparison means for comparing the photoelectric conversion signal for each point with a predetermined reference value; determining means for determining whether or not the point is within the field of view of the eyepiece, and calculating only a photoelectric conversion signal of a point determined by the determination means to be within the field of view of the eyepiece of the endoscope. an endoscopic photographing device, comprising: arithmetic means for determining exposure;