JPH069392B2 - Endoscopic imaging device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an endoscope image pickup apparatus, and more particularly to an endoscope image pickup apparatus that performs color image pickup by a frame sequential method.

[Prior art]

In recent years, a solid-state image sensor such as a CCD is provided at the tip of an endoscope,
An endoscopic image pickup apparatus has been developed that performs color imaging of an image inside a body cavity and performs diagnosis based on the image displayed on a monitor device. Here, the number of pixels cannot be increased because the image sensor is provided in a narrow place such as the tip of the endoscope. Therefore, color photography is performed by a frame sequential method in which all pixels can be effectively used. That is, the RGB three-color component images are sequentially captured, and the three-color component signals are combined for each pixel to obtain 1
It is for generating a single color image signal. However,
With this method, it is necessary to capture three color component images to capture one image, so it takes time,
Image color shift is likely to occur due to subject movement or camera shake. If the color shift occurs in the endoscopic image, it becomes difficult to detect the lesion and accurate diagnosis becomes impossible.

〔Purpose〕

This invention has been made to deal with the above-mentioned circumstances,
An object of the present invention is to prevent color misregistration in an endoscopic image pickup apparatus of a frame sequential color photographing system.

〔Overview〕

This object is realized by detecting the color shift and varying the imaging speed according to the degree of the color shift.

〔Example〕

An embodiment of an endoscope imaging apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. The endoscope body 10 is a light guide 1.
2, objective raise 14, solid-state image sensor (eg CCD)
Have 16. One end of the light guide 12 is connected to the light source unit 20, the other end is guided to the tip of the endoscope body 10, and is composed of an optical fiber bundle that guides the illumination light from the lamp 22 in the light source unit 20 into the body cavity. A rotary disk 24 is provided between one end of the light guide 12 and the lamp 22 and is divided into three equal parts in a fan shape along the circumferential direction and R, G, and B color filters are arranged in each part. The rotating disk 24 is rotated by 120 ° by the step motor 26, and the lamp 22
The illumination light radiated from is sequentially colored into R, G, and B. As a result, the solid-state image pickup device 16 causes the R, G, and
A color component image of B is photographed, and color photographing is performed by a frame sequential method. The output signal of the solid-state image sensor 16 is supplied to the video processor 30. The output signal of the solid-state image sensor 16 is first input to the sample / hold circuit 32. The output signal of the sample / hold circuit 32 is supplied to the input terminal of the selector 36 via the A / D converter 34.
The selector 36 has four output terminals, and each output terminal is connected to the frame memories 40, 42, 44 and 46, respectively. The selector 36 is controlled so that the color component signals of R, G, B and R (= R ') are written in the frame memories 40, 42, 44 and 46, respectively. Here, R and R'are
The red component signals taken at odd and even numbers are shown, respectively. Sample / hold circuit 32, A / D converter 34
The timing controller 38 controls the timing, switching of the selector 36, and writing to the frame memories 40, 42, 44, 46. The output terminals of the frame memories 40, 42, 44 and 46 are connected to the input terminals of the D / A converters 50, 52, 54 and 56, respectively. D /
One of the outputs of the A converters 50 and 56 is supplied via the selector 58 to the outputs of the D / A converters 52 and 54 as they are, and the color image is displayed as a moving image. Reading from frame memories 40, 42, 44, 46, D / A
The timing controller 62 controls the timing of the converters 50, 52, 54 and 56 and the switching of the selector 48.

On the other hand, the outputs of the D / A converters 50 and 56 are supplied to the subtractor 64, and the output of the D / A converter 50 is changed to the D / A converter 56.
The output of is subtracted. The output of the subtractor 64 is the absolute value circuit 6
6, and is supplied to the charge storage circuit 70 via the comparator 68. The comparator 68 extracts a signal of the reference level E or higher from the output of the absolute value circuit 66. Charge storage circuit 7
0 integrates the output of the comparator 68 every read cycle of the frame memories 40 and 46 in response to the integration start pulse P from the timing controller 62. The integration result of the charge storage circuit 70 is supplied to the color misregistration prevention signal generation circuit 72. The color shift prevention signal generation circuit 72 controls the intensity of the illumination light emitted from the lamp 22 by the lamp drive circuit 74 and the motor drive circuit 76 and the rotation speed of the step motor 26 according to the output signal of the charge storage circuit 70. To do. The output signal of the color misregistration prevention signal generation circuit 72 also controls the timing controller 38.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2A shows the speed of movement of the subject. Monitor 6
0 displays an image of 30 frames per second. Therefore, the RGB color component signals are read from the frame memories 40, 42, 44, 46 every 1/30 second as shown in FIG. Then, the frame memories 40, 42, 4
Writing to 4, 46 is normally such that the component signals of the three colors of RGB are written within this 1/30 second cycle. FIG. 2B shows the color component of the image signal from the solid-state image sensor 16, which is proportional to the rotation speed of the rotary disc 24. That is, normally, each color component image of RGB is 1/90
The pictures are taken every second. The image signal is written in a predetermined frame memory for each color component as shown in FIG. Here, the red color component signal is alternately written into the frame memories 40 and 46 (R, R ') for each frame by the timing controller 38 and the selector 36. Therefore, the red component image signal is also read from the frame memories 40 and 46 alternately for each frame. That is, as shown in FIG. 2D, the R, G and B component signals in the frame memories 40, 42 and 44 and the R ′, G and The B component signals are read alternately.

As described above, the frame memories 40 and 46 store image signals which are shifted by the photographing time of three frames (usually 1/30 seconds). Therefore, the color shift of the image can be detected by comparing these two image signals. In order to remove the noise component, the frame memory 40,
Of the absolute value of the difference between the output signals of 46 (| R−R ′ |),
Components having a reference level E or higher are input to the charge storage circuit 70. As shown in FIG. 2E, the timing controller 62 supplies an integration start pulse P to the charge storage circuit 70 every 1/30 seconds in synchronization with the reading of signals from the frame memories 40, 42, 44 and 46. . The charge storage circuit 70 integrates the input signal according to the integration start pulse P and outputs the difference between the two image signals according to the color shift as shown in FIG. 2 (f). When the integrated value exceeds a predetermined value, the color shift prevention signal generation circuit 72 generates a color shift prevention signal as shown in FIG. Here, the discriminating integration start pulse P of the integrated value
It is performed at the timing of. In response to the generation of the color shift prevention signal, the lamp drive circuit 74 and the motor drive circuit 76
Respectively increase the intensity of the illumination light emitted by the lamp 22 and increase the rotation speed of the step motor 26. Further, due to this color misregistration prevention signal, the operation speed of the timing controller 38 is also increased, and the switching of the selector 36 is speeded up in synchronization with the switching of the filter by the rotary disc 24. As a result, the shooting speed of the solid-state image sensor 16 is increased, and color shift does not occur even if the subject moves fast. When the movement of the subject becomes slow, the generation of the color misregistration prevention signal ends, the intensity of the illumination light emitted by the lamp 22 weakens, and the rotation speed of the step motor 26 slows. Further, the switching of the selector 36 is delayed in synchronization with the switching of the filter by the rotary disc 24, and the imaging speed of the solid-state imaging device 16 returns to the standard speed.

As described above, according to this embodiment, the operating speed of the solid-state image sensor changes according to the operating speed of the subject, and color shift does not occur even in the case of a fast moving subject. Therefore, accurate diagnosis is possible without overlooking the lesion. The present invention is not limited to the above-mentioned embodiments, but can be variously modified. Although the color misregistration prevention signal is a binary signal and the imaging speed is changed in two steps in the above-described embodiment, the color misregistration prevention signal may be a multilevel signal and the imaging speed may be changed in multiple steps.

〔The invention's effect〕

As described above, according to the present invention, there is provided an endoscope image pickup apparatus which can obtain a color image without color shift and is useful for accurate diagnosis.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the device according to the present invention, and FIG. 2 is a diagram showing its operation. 16 ... Fixed image pickup device 22 ... Lamp 24 ... Rotating disk 36, 58 ... Selector 40, 42, 44, 46 ... Frame memory 60 ... Monitor device 64 ... Subtractor 70 ... Charge storage circuit 72 ...... Color shift prevention signal generation circuit 74 ...... Lamp drive circuit 76 ...... Motor drive circuit

Claims (1)

[Claims] 1. A color misregistration of an image is detected based on a difference between field-sequential image pickup means for picking up color component images of at least three colors and the same color component signal of images picked up by the image pickup means at different times. And an image pickup device for controlling the image pickup speed of the image pickup unit according to the output of the detection unit.