JPS626593A - Video signal processing circuit - Google Patents

Abstract

PURPOSE:To constant adjust a color tone and a brightness to an optimum value even when the type of a connected camera is different by discriminating the type of the connected camera and automatically correcting the color tone and the brightness according thereto. CONSTITUTION:A television camera 4 has a CCD 24 as a solid-state image pickup element picking up an image of an object to be photographed which is transferred to an eye piece part of an endoscope mirror 10 and terminals A, B for discriminating the type of the camera. As the discriminating circuit of the type of the camera in a video signal processing circuit 16, for instance, a terminal to which the detecting terminal A is connected is connected to a power source 5V through a resistance R and a terminal to which the terminal B is connected is earthed, and from the connecting point of the resistance R and the terminal A, a detecting signal is outputted. Herein, an image pickup signal from the CCD 24 is supplied to an image process circuit 32 to have a video signal and it is outputted through an AGC circuit 34. The gain of the AGC circuit 34 is controlled by a gain setting circuit 40 in accordance with the detecting signal. A timing generating circuit 36 supplies a timing signal to the gain setting circuit 40, a motor 30 and the driver 38 of the CCD 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal processing circuit, and particularly to a video signal processing circuit connectable to different types of cameras.

[Prior Art] As such a video signal processing circuit, there is a video signal processing circuit for an endoscope. 2. Description of the Related Art Conventionally, there has been an endoscope imaging system in which a television camera is connected to an eyepiece of an endoscope, and an optical image of the inside of a body cavity is captured, which is transmitted to the eyepiece via an image guide, and displayed on an external monitor. However, with the recent development of solid-state imaging devices, systems have been developed in which a solid-state imaging device is built into the tip of an endoscope, and an imaging signal is transmitted through the endoscope to an external monitor for display.

As an example of this, there is a system as shown in Japanese Patent Application Laid-open No. 59-151591. Here, if a solid-state image sensor is used as the imaging section of the television camera of the former system, and this solid-state image sensor is the same as that of the latter system, a common video signal processing circuit can be used. This is because the clock frequency and signal level are the same, but the color tone and brightness are not completely the same.The former solid-state image sensor is transmitted via an image guide made of optical fiber. The difference is that the latter solid-state image sensor directly captures an incident optical image, whereas the solid-state image sensor directly captures an incident optical image. For this reason, if the video signal processing circuit is adjusted to obtain correct color reproducibility in the latter system, when processing the imaging signal of the former system, the colors will be shifted by the amount of coloring caused by the image guide.

Furthermore, in the former system, the same solid-state imaging device may be connected to endoscopes having image guides with different diameters. In this case, the area of the subject image formed on the solid-state image sensor differs depending on the diameter of the image guide. Here, there is no problem if the object image is larger than the image forming surface of the solid-state image sensor, but if the object image is smaller than the image forming surface of the solid-state image sensor, the following problem occurs. If the subject image is smaller than the solid-state image sensor, the area other than the subject image on the solid-state image sensor will be completely dark, resulting in the erroneous determination that the subject is dark even though it is actually bright. , the amount of illumination light is increased to brighten the subject, resulting in the subject being overexposed.

[Problems to be Solved by the Invention] As described above, in the conventional technology, the video processing circuit can be used in common for different cameras, but there are problems in adjusting the color tone and brightness.

This invention was made with attention to these problems, and an object of the present invention is to provide a video signal processing circuit that can always adjust the color tone and brightness to optimal values even if the types of cameras connected are different. .

[Means and actions for solving the problem] This device determines the type of camera connected and adjusts the color tone and color accordingly.
Brightness is automatically corrected.

[Embodiment] An embodiment of the video signal processing circuit according to the present invention will be described below with reference to the drawings. Here, a video signal processing circuit connected to the above-mentioned endoscope imaging system will be explained as an example. FIGS. 1(a) and 1(b) are block diagrams showing the configurations of two types of endoscopic imaging systems configured using the same video signal processing circuit according to the first embodiment. 1st
The system in Figure (a) includes an endoscope 10 and a light source unit 12.
, a television camera 14 connected to the eyepiece of the endoscope IO, and a video signal processing circuit 16. The endoscope 10 includes a light guide 18 made of an optical fiber bundle that transmits illumination light from a light source unit 12 to the distal end and illuminates a subject within the body cavity, and transmits a subject image formed by an objective lens 20 to an eyepiece. It has an image guide 22 made of an optical fiber bundle. The television camera 14 has a CCD 24 as a solid-state image sensor that captures a subject image transmitted to the eyepiece of the endoscope 10, and terminals A and B for determining the type of camera, which will be described later.

In this system, terminals A and B are electrically connected. The output end of the CCD 24, terminals A and B, are connected to the video signal processing circuit 16. Light source 2) 12 is an endoscope lO
The illumination light from the lamp 26 is transmitted through the rotating color filter 2.
8, red (R
), green (G), and blue (B) component light, CC
D24 is a 0-rotation color filter 28 that performs color imaging using a field sequential method, and has R and G along the circumferential direction.

It consists of a disk-shaped filter in which areas B are arranged, and its rotation is controlled by a motor 3o in synchronization with the imaging period of the CCD 24.

The system shown in FIG. 1(b) includes an endoscope 10, a light source unit 12, and a video signal processing circuit 16.

Although the endoscope IO has a light guide 18, the light guide 18 shown in FIG.
), it does not have an image guide, but instead has a built-in CCD 24 at its tip that captures a subject image formed through an objective lens 20. Further, terminals A and B for determining the type of camera connected to the video signal processing circuit 16 are provided on the endoscope 10. In this system, terminals A and B are not connected, and the other configuration is the same as the configuration in FIG. 1(a).

The details of the camera type discrimination circuit in the video signal processing circuit 16 will be explained with reference to FIG. The terminal to which the detection terminal A is connected is connected to the power source 5■ via a resistor R, and the terminal to which the terminal B is connected is grounded. Resistor R and terminal A
A detection signal is output from the connection point. This allows the first
In a system where detection terminals A and B are electrically connected as shown in Figure 2(a), a current of 5V flows from a power source of 5V through a resistor R as shown in Figure 2(a). Detection signals are obtained. On the other hand, in a system where terminals A and B are not connected as shown in Figure 1(b), Figure 2(b)
As shown in the figure, no current flows from the power source 5V to the resistor H, and a detection signal of Ov is obtained.

FIG. 3 is a block diagram showing the detailed configuration of the video signal processing circuit 16. The video signal processing circuit 16 includes a video processing circuit 323, an automatic gain adjustment (AGC) circuit 34. It consists of a timing generation circuit 36 and a gain setting circuit 40. CCD
The imaging signal from 24 is supplied to the video processing circuit 32, converted into a video signal, and outputted via the AGC circuit 34.

The gain of the AGC circuit 34 is controlled by a gain setting circuit 40 in response to detection signals as shown in FIGS. 2(a) and 2(b). The timing generation circuit 36 is connected to a gain setting circuit 40. Motor 30. A timing signal is supplied to the driver 38 of the CCD 24. As a result, the gain of the AGC circuit 34 can be adjusted at the appropriate timing for each color component video signal of R, G, and B sequentially output from the CCD 24.
The gain of each G and B color component video signal can be varied,
You can adjust the image tone and brightness.

As a result, even if the video signal processing circuit 16 is connected to a television camera with an eyepiece of the internal value as shown in FIG. Even when connected directly to an endoscope, the color tone and brightness of the image can be automatically adjusted, and video signals with optimal color tone and brightness can always be obtained even if the types of cameras connected are different.

Next, a second embodiment of the invention will be described. In the second embodiment, when a signal from a television camera connected to the eyepiece of an endoscope as shown in Fig. 1(a) is input, the video signal is adjusted according to the diameter of the image guide. By automatically adjusting the color tone and brightness, the above-mentioned problems can be solved. Here, with reference to FIG. 4, the problem caused by the difference in diameter of the image guide of the endoscope will be explained again. If the image guide diameter is large, see Figure 4 (
As shown in a), since the subject image (circular) is larger than the imaging surface (rectangular) of the solid-state imaging device, the optical image is incident on the entire imaging surface of the solid-state imaging device. On the other hand, when the image guide diameter is small, the object image (circular) is smaller than the imaging surface (rectangular) of the solid-state image sensor, as shown in FIG. The optical image is incident on only a portion. Since the part of the imaging surface other than the optical image (the shaded area) is completely dark, the brightness of the subject is detected as being darker than it actually is. Therefore, in this case, the detected value of the subject's brightness is corrected. If you don't do this, you won't be able to get proper exposure.

For simplicity, the block diagram of the entire system of the second embodiment is shown in Fig. 5(a) when the diameter of the image guide is set to two types.
, (b), and Fig. 5 (a) and (b) are respectively when the image guide is connected to an endoscope with a large diameter,
This is the case when the image guide is connected to an endoscope with a small diameter. In the second embodiment, a terminal C1D for determining the size of the image guide is provided in the endoscope IO, and these terminals C, D
is the video signal processing circuit 1 via the television camera 14.
Connected to 6. These terminals C and D are electrically connected in an endoscope 10 with a large diameter image guide as shown in FIG. 5(a). In an endoscope 10 with a narrow diameter image guide as shown in FIG. 5(b), this terminal is not connected.

The video signal processing circuit 16 can determine the size of the diameter of the image guide using a determination circuit as shown in FIG. 2, and adjust the exposure value accordingly. Therefore, the above-mentioned problems can be solved.

Note that this invention is not limited to the embodiments described above, and can be modified in various ways. Although the above-mentioned embodiment has been described as an endoscope imaging device, the present invention is not limited thereto. Furthermore, the camera section is not limited to having a solid-state image sensor, and the solid-state image sensor is not limited to a CCD. Furthermore, although the number of types of cameras to be discriminated is two, it goes without saying that three or more types may be used.

[Effects of the Invention] As explained above, according to the present invention, the type of connected camera is determined and the color tone and brightness are automatically corrected accordingly. Provided is a video signal processing circuit that can always adjust color tone and brightness to optimal values even if the colors are different.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are system configuration diagrams when the first embodiment of the video signal processing circuit according to the present invention is connected to different cameras, and FIGS. 2(a) and (b) are system configuration diagrams when the first embodiment of the video signal processing circuit according to the present invention is connected to different cameras. A circuit diagram of a camera type discrimination circuit in the signal processing circuit, FIG. 3 is the first circuit diagram of the video signal processing circuit according to the present invention.
The block diagram of the embodiment, FIGS. 4(a) and 4(b), shows the size relationship between the diameter of the image guide and the imaging surface of the solid-state image sensor in order to explain the second embodiment of the video signal processing circuit according to the present invention. 5(a) and 5(b) are system configuration diagrams when a second embodiment of the video signal processing circuit according to the present invention is connected to different cameras. 12... Light source unit 14... Camera 16... Video signal processing circuit 22... Image guide 24... Solid-state image sensor 34... AGC circuit 36... Timing generation circuit 40... Gain Setting circuit applicant's agent Patent attorney Atsushi Tsuboi Diagram 5 Procedure amendment Showa 4I March-4th Patent Office Commissioner Michibe Uga 1, Indication of the case Patent application No. 144929/1988 2, Title video of the invention Signal processing circuit 3, relationship with the amended person case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent 17 Mori Building 6, 1-26-5 Toranomon, Minato-ku, Tokyo;
Specification subject to amendment, Drawing 7, Contents of amendment (1) Detection of r5V stated in page 6, line 19 of specification inner cylinder.”
is corrected to "OV detection". (2) As stated in the second and third lines of page 7 of the specification, "As shown in , no current flows from the power supply 5 to the resistor R and the voltage is OV."
Correct it to "5V as shown in". (3) "Total image guide" written on page 7, line 15 of the specification is corrected to "diameter of image guide." (4) Correct the drawings (a) and (b) as shown in the attached sheet. pt〉 Procedural amendment 1, Indication of the case Japanese Patent Application No. 60-144929 2, Title of the invention Video signal processing circuit 3, Person making the amendment Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4. Agent UBE Building, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo 1
05 Telephone 03 (502>3181 (main representative)
6. Subject of correction: Akira 11111 Ex. 7. Contents of correction (1) "Flare" written in Mei III, page 5, line 13 is corrected to "field." In the 15th line of page 5 of the specification, next to ``Perform color decoy imaging'', ``V, that is, the rotating color filter 28 is 3
It rotates at a rotational speed of 0 revolutions/second. ” is inserted. (3) Next to "is controlled." written on page 5, line 19 of AkiraS, [Here, this system removes the television camera 14 and directly observes the image at the eyepiece with the naked eye. It is also possible to do so. However, in this case, the light source light is sequentially R, G
, B, so it may feel a little strange to the eye. In that case, if the rotation speed of the rotating color filter 28 is increased somewhat (for example, 60 rotations/second), the strange feeling can be completely eliminated. ” is inserted.

Claims (1)

[Claims] In a video signal processing circuit that can be connected to different types of cameras, the video signal processing circuit determines the type of connected camera and corrects the color tone and brightness accordingly.