JPH0693779B2 - Video signal processing circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing circuit, and more 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, an optical image in a body cavity transmitted to an eyepiece through an image guide is taken, and the image is displayed on an external monitor. However, with the recent development of the solid-state image pickup device, a system has been developed in which the solid-state image pickup device is built in the tip of the endoscope and an image pickup signal is transmitted to an external monitor via the endoscope and displayed.
As an example of this, there is a system as shown in JP-A-59-151591. Here, if a solid-state image sensor is used as the image pickup 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 the signal level are the same, but the color tone and the brightness are not completely the same. The former solid-state image pickup device picks up an optical image transmitted through an image guide made of an optical fiber bundle, whereas the latter solid-state image pickup device directly takes an incident optical image. For this reason, if the video signal processing circuit is adjusted so that correct color reproducibility is obtained in the latter system, when the image pickup signal of the former system is processed, the color shifts by the amount of coloring by the image guide.

In the former system, the same solid-state image sensor 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 is different due to the difference in the diameter of the image guide. Here, there is no problem if the subject image is larger than the image plane of the solid-state image sensor, but if the subject image is smaller than the image plane of the solid-state image sensor, the following problem occurs. When the subject image is smaller than the solid-state image sensor, the portion other than the subject image on the solid-state image sensor is dark, and therefore a bright subject may be wrongly determined to be a dark subject. As a result, the amount of illumination light is increased to brighten the subject, and the subject becomes overexposed.

[Problems to be Solved by the Invention] As described above, in the conventional technique, the image processing circuit can be commonly used for different cameras, but there is a problem in adjusting the color tone.

The present invention has been made in view of such a problem, and an object thereof is to provide a video signal processing circuit capable of always adjusting a color tone to an optimum value even if the type of connected camera is different.

[Means and Actions for Solving Problems] According to the present invention, an image that can be combined with a videoscope having a solid-state imaging device at its tip or a fiberscope having a television camera connected to an eyepiece section In the signal processing circuit, a means for judging whether the combined scope is a videoscope or a fiberscope, and when this judgment means detects a combination with the fiberscope, the video signal from the scope is colored by an image guide. And a means for correcting the color tone so as to compensate for the above.

[Embodiment] An embodiment of a 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-described endoscope imaging system will be described as an example. 1 (a) and 1 (b) are block diagrams showing the configurations of two types of endoscope imaging systems configured by using the same video signal processing circuit according to the first embodiment. First
The system shown in FIG. 1A includes an endoscope 10, a light source unit 12, and
A television camera 14 connected to the eyepiece of the endoscope 10.
And a video signal processing circuit 16. The endoscope 10 is a light guide 18 including an optical fiber bundle that transmits the illumination light from the light source unit 12 to the tip and illuminates a subject in the body cavity.
And an image guide 22 composed of an optical fiber bundle for transmitting the subject image formed by the objective lens 20 to the eyepiece. The television camera 14 is a CC as a solid-state image sensor that captures the subject image transmitted to the eyepiece of the endoscope 10.
D24 and a terminal A for distinguishing the type of camera described later,
Have B. In this system, terminals A and B are electrically connected. The output end of the CCD 24 and terminals A and B are connected to the video signal processing circuit 16. The light source unit 12 is an endoscope
The light guide 18 of 10 has a lamp 26 for making the illumination light incident, and the illumination light from the lamp 26 is rotated by the rotating color filter 28 in red (R), green (G), and blue (for each image pickup period of one frame of the CCD 24). The component light of B) is sequentially colored, and the CCD 24 carries out color imaging by the field sequential method. Rotating color filter 28
Is a disk-shaped filter in which R, G, and B regions are arrayed along the circumferential direction, and the motor 30 controls the rotation in synchronization with the imaging cycle of the CCD 24.

The system of FIG. 1 (b) includes an endoscope 10 and a light source unit 12
And a video signal processing circuit 16. The endoscope 10 has a light guide 18, but does not have an image guide unlike the configuration shown in FIG. 1 (a). Instead, the objective lens 20 at the tip
A CCD 24 that captures a subject image formed through the camera is built in. Further, terminals A and B for discriminating the type of camera connected to the video signal processing circuit 16 are provided in the endoscope 10. In this system, terminals A and B are not connected. The other structure is the same as the structure shown in FIG.

The details of the camera type determination circuit in the video signal processing circuit 16 will be described with reference to FIG. The terminal to which the terminal A for detection is connected is connected to the power source 5V via the resistor R, and the terminal to which the terminal B is connected is grounded. A detection signal is output from the connection point between the resistor R and the terminal A. As a result, in the system in which the detection terminals A and B are electrically connected as shown in FIG. 1 (a), the current is supplied from the power source 5V through the resistor R as shown in FIG. 2 (a). And a detection signal of 0V is obtained. On the other hand, in the system in which the terminals A and B are not connected as shown in FIG. 1 (b), a 5V detection signal is obtained as shown in FIG. 2 (b).

FIG. 3 is a block diagram showing a detailed configuration of the video signal processing circuit 16. The video signal processing circuit 16 is the video processing circuit 3
2, automatic gain adjustment (AGC) circuit 34, timing generation circuit
36 and a gain setting circuit 40. The image pickup signal from the CCD 24 is supplied to the image processing circuit 32, and is converted into an image signal, which is the AGC.
It is output via the circuit 34. The gain of the AGC circuit 34 is the second
It is controlled by the gain setting circuit 40 according to the detection signal as shown in FIGS. Timing generator 36
Supplies a timing signal to the gain setting circuit 40, the motor 30, and the driver 38 of the CCD 24. As a result, the gain of the AGC circuit 34 can be adjusted with timing for each of the R, G, and B color component video signals sequentially output from the CCD 24.
The gain of each color component video signal can be changed, and the color tone and brightness of the image can be adjusted.

As a result, even when the video signal processing circuit 16 is connected to the television camera of the eyepiece part of the endoscope as shown in FIG. 1 (a), the CCD is built in at the tip as shown in FIG. 1 (b). Even when directly connected to the endoscope, the color tone and brightness of the image can be automatically adjusted, and a video signal of optimum color tone and brightness can always be obtained even if the type of connected camera is different.

Next, a second embodiment of the present invention will be described. In the second embodiment, when a signal from a television camera connected to the eyepiece of the endoscope as shown in FIG. 1 (a) is input, the color tone of the video signal according to the image guide diameter, By automatically adjusting the brightness, the above-mentioned problems are solved. Here, with reference to FIG. 4, the problem caused by the difference in the diameter of the image guide of the endoscope will be described again. When the image guide diameter is large, the subject image (circle) is larger than the image pickup surface (rectangle) of the solid-state image pickup element as shown in FIG. 4A, so that the optical image is incident on the entire image pickup surface of the solid-state image pickup element. . On the other hand, when the image guide diameter is small, the subject image (circular) is smaller than the image pickup surface (rectangle) of the solid-state image pickup element as shown in FIG. An optical image is incident on only a part. And the part other than the optical image of the imaging surface (hatched area)
Is completely dark, the brightness of the subject is detected as being darker than it actually is. For this reason, in this case, proper exposure cannot be obtained unless the detected value of the brightness of the subject is corrected.

For the sake of simplicity, FIG. 5 (a) is a block diagram of the entire system of the second embodiment when the image guide has two diameters.
It shows in (b). FIGS. 5A and 5B show the case where the image guide is connected to the endoscope having a large diameter and the case where the image guide is connected to the endoscope having a small diameter. Second
In the embodiment, terminals C and D for determining the diameter of the image guide are provided in the endoscope 10, and these terminals C and D are connected to the video signal processing circuit 16 via the television camera 14. The terminals C and D are electrically connected in the endoscope 10 having a large diameter image guide as shown in FIG.
Then, in the endoscope 10 having a small diameter image guide as shown in FIG. 5B, this terminal is not connected.

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

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made. Although the above embodiment has been described as an endoscope imaging apparatus, the present invention is not limited to this. The camera unit is not limited to one having a solid-state image sensor, and the solid-state image sensor is not limited to the CCD. Further, although there are two types of cameras to be discriminated, it goes without saying that three or more types may be used.

[Effects of the Invention] As described above, according to the present invention, the type of connected camera is discriminated and the color tone is automatically corrected in accordance with the type, so that even if the type of connected camera is different, the color tone is changed. There is provided a video signal processing circuit capable of always adjusting the optimum value.

[Brief description of drawings]

1 (a) and 1 (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 2 (b) are images according to the present invention. A circuit diagram of a camera type discrimination circuit in the signal processing circuit, FIG. 3 is a block diagram of a first embodiment of a video signal processing circuit according to the present invention, and FIGS. 4 (a) and 4 (b) are video images according to the present invention. FIG. 5 (a) and FIG. 5 (b) are views showing the relationship between the diameter of the image guide and the image pickup surface of the solid-state image pickup device in order to explain the second embodiment of the signal processing circuit. It is a system block diagram when connecting a 2nd Example to a different camera. 12 ... Light source unit 14 ... Camera 16 ... Image signal processing circuit 22 ... Image guide 24 ... Solid-state image sensor 34 ... AGC circuit 36 ... Timing generation circuit 40 ... Gain setting circuit

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Masahiko Sasaki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (56) Reference JP-A-59-69720 (JP, A) JP Sho 61-2120 (JP, A) JP 61-48333 (JP, A)

Claims (1)

[Claims] 1. A video scope having a solid-state image sensor at its tip, or a video signal processing circuit which can be combined with a fiber scope having a television camera connected to an eyepiece, wherein the combined scope is a video scope, And a means for judging which of the fiberscopes, and a means for correcting the color tone of the video signal from the scope so as to compensate the coloring by the image guide when the judgment means detects a combination with the fiberscope. A video signal processing circuit characterized by the above.