JPH0665335B2 - Endoscope device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an endoscope apparatus, and more particularly to an endoscope apparatus for recording a still image of a color image captured 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 to perform color imaging, and a still image is recorded on a magnetic disk or a still image displayed on a monitor device is photographed. An endoscopic device for making a diagnosis has been developed. The number of pixels cannot be increased because the image sensor is provided in a narrow space such as the tip of the endoscope. Therefore, color imaging is performed by a frame sequential method in which all pixels can be effectively used. An example of such a device is described in JP-A-53-90685. That is, shooting is performed sequentially under the illumination light of three colors of red, green, and blue to obtain three-color component images of red, green, and blue, and the three-color component signals are combined for each pixel to produce a color image. It is for generating a signal. However, with this method, 1
Since it is necessary to capture the three-color component images to capture one color image, it takes much time, and the color shift of the image easily occurs due to the movement of the subject, camera shake, or the like. 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 endoscope apparatus that records a still image of an image captured in color by a frame sequential method.

〔Overview〕

This object is realized by increasing the imaging speed of each component image when recording a still image of the image.

〔Example〕

An embodiment of an endoscope apparatus according to the present invention will be described below with reference to the drawings. As shown in FIG. 1, this embodiment comprises an endoscope body 10, a light source unit 12, a video processor 14, a still image recording device 16, and a release switch 18. The endoscope body 10 guides the illumination light from the light source unit 12 to the tip and irradiates the inside of the body cavity or cavity from the tip with a light guide 22 and a light guide 22 that is provided at the tip and images the inside of the body cavity or the cavity. It has a solid-state image sensor (for example, CCD) 20 that operates. Here, since the tip of the endoscope is narrow, the solid-state imaging device 20 does not have a light-shielding storage section that functions as a shutter, and the shutter mechanism is provided in the light source unit 12 as described later. The output signal of the solid-state imaging device 20 is supplied to the video processor 14,
Input to the amplifier 24. In reality, a preamplifier is provided in the endoscope body 10, and the image signal is supplied from the preamplifier to the amplifier (CMR amplifier) 24 via the two-phase signal line.

The output signal of the amplifier 24 is written in the frame memory 28 via the A / D converter 26. Although the frame memory 28 is illustrated as one, it is actually divided into three areas, and image signals of red (R), green (G), and blue (B) color components are provided for each area. Remembered. From the frame memory 28, R, G and B image signals are simultaneously read out for each frame,
It is supplied to the D / A converter 32 via the selector 30. The selector 30 selectively connects either the output terminal or the ground terminal of the frame memory 28 to the D / A converter 32. The output of the D / A converter 32 is passed through the NTSC decoder 34 to the still image recording device 16
Is supplied to. As the still image recording device 16, a photographing device including a CRT monitor and a still camera, a magnetic disk recording device, a floppy disk recording device, a VTR or the like is used. Also provided in the video processor 14 is a driver 36 that generates clock pulses for the solid-state imaging device 20. The timing of each circuit in the video processor 14 is controlled by the control circuit 38. The writing speed to the frame memory 28 and the reading speed from the frame memory 28 are different, and different timing signals are generated from the control circuit 38. A release pulse from the release switch 18 is supplied to the control circuit 38, and a release signal is supplied from the control circuit 38 to the still image recording device 16.

The light source unit 12 includes a lamp 40 that causes the illumination light to enter the light guide 22. A rotary filter 42 having a shutter function and a function of coloring the illumination light into R, G, and B is provided between the light guide 22 and the lamp 40. As shown in FIG. 2, the rotary filter 42 is a disc in which R, G and B color filters 50, 52 and 54 are discontinuously arranged on a concentric ring. The non-continuous portion between the color filters is illuminated by the illumination light, that is,
It functions as a shutter that blocks the light to the solid-state image sensor 20.
Through holes 56, 58, 60 for generating a read pulse are provided outside the rearmost portion of each color filter 50, 52, 54 in the rotation direction, and outside the through hole 56 of the R filter 50 for generating a start pulse. A through hole 62 is provided. The rotation filter 42 is driven by a motor whose rotation is controlled by a PLL speed control circuit 46, for example, a step motor 44. Rotary filter 42
A photodetector 48, which is composed of a light emitting element and a photodetector and generates a read pulse and a start pulse by receiving light through the through hole, is provided in the green part of the. The start pulse and read pulse output from the photodetector 48 are supplied to the control circuit 38 in the video processor 14. A light amount control signal is supplied from the control circuit 38 to the lamp 40, and a motor reference pulse serving as a reference for PLL speed control of the step motor 44 is supplied to the speed control circuit 46.

The operation of this embodiment will be described. First, FIG. 3 (a)-
The principle of the field sequential imaging method will be described with reference to (d). As the rotary filter 42 rotates, the R, G, and B color filters 5 are sequentially arranged in the optical path from the lamp 40 to the light guide 22.
0, 52, and 54 are interposed, and the illumination light is sequentially colored in R, G, and B at predetermined intervals with a light-shielding period interposed, as shown in FIG. 3 (c). Each component image is captured while the illumination light is colored in each of these colors. Generally, the solid-state image sensor 20
Since the sensitivity depends on the color and becomes worse in the order of R, G, B, it is preferable that the size of each color filter 50, 52, 54 increases in the order of R, G, B.
However, here, for convenience of explanation, the color filters 50, 52, and 54 have the same size, and the illumination time of each component light is uniform.

For each rotation of the rotary filter 42 (at the end of the R illumination), the third
A start pulse is generated as shown in FIG. At the end of illumination of each component light, a read pulse is generated as shown in FIG. 3 (b). That is, the cycle of the read pulse is 1/3 of the cycle of the start pulse. During the light-shielding period from the generation of the read pulse to the illumination of the next color component, the component image captured under each color component light is written in the frame memory 28 as shown in FIG. 3 (d). . As a result, frame sequential color imaging is executed.

Next, a still image recording operation of a color image according to this embodiment will be described with reference to FIGS. Until the release switch 18 is pressed, the step motor 44 is rotating at a predetermined constant speed, and R, G, B illumination is performed at a constant cycle as shown in FIG. Is imaged and each color component image signal is written in the frame memory 28 at a constant cycle. Frame memory 28
From, the R, G, and B color component images for one frame are simultaneously read and supplied to the still image recording device 16. The rotation speed of the step motor 44 (shown in FIG. 4 (d)) is determined by the frequency of the motor reference pulse from the control circuit 38 (shown in FIG. 4 (c)). Further, it is assumed that the light quantity of the lamp 40 is set to a certain small light quantity as shown in FIG.

When the release switch 18 is pressed and a release pulse is generated as shown in FIG. 4 (b), the frequency of the motor reference pulse is increased as shown in FIG. 4 (c), and FIG. As shown in, the rotation speed of the step motor 44 is increased. Further, as the frequency of the motor reference pulse becomes higher, the phase lock of the step motor 44 under PLL control is released as shown in FIG. 4 (e). After the release pulse is generated, the light quantity of the lamp 40 is increased as shown in FIG. 4 (j). This is to compensate for the relative decrease in the amount of illumination light when the imaging speed increases.

When the rotation speed of the step motor 44 reaches a predetermined high speed determined by the frequency of the motor reference pulse, the phase of the step motor 44 returns to the locked state as shown in FIG. 4 (e). As the rotation speed of the step motor 44 is increased, the cycle of switching the illumination light to R, G, B is also increased as shown in FIG. 4 (a). As a result, the image pickup time of each color component image is shortened, and the writing speed of each color component image to the frame memory 28 is also increased as shown in FIG. 4 (f). This represents a reduction in the image pickup time for each color component image, and as a result, color misregistration is prevented.

After the rotation speed of the step motor 44 is phase-locked at a high speed, the rotation filter 42 makes one rotation and one color image is picked up. As shown in FIG.
Writing of the image signal to 28 is stopped, and a release signal is supplied to the still image recording device 16 as shown in FIG. Thereafter, the data in the frame memory 28 is frozen as shown in FIG. 4 (g), and the frequency of the motor reference pulse returns to a low frequency as shown in FIG. 4 (c). As a result, the rotation speed of the step motor 44 decreases as shown in FIG.
The phase lock of is released. At this time, the light quantity of the lamp 40 returns to a small light quantity as shown in FIG. Then, as shown in FIG. 4 (i), the frozen image is recorded by the still image recording device 16 as a still image. As described above, since the frozen image is an image captured at high speed, there is no color shift. Therefore, according to this embodiment, a still image free from color misregistration can be recorded, and an endoscopic device useful for endoscopic diagnosis is provided. When the still image recording is completed and the phase of the step motor 44 is locked again as shown in FIG. 4 (e), the frame memory is displayed as shown in FIG. 4 (g).
The freeze of 28 is released, and imaging is performed at a low constant speed as shown in FIGS. 4 (a) and 4 (f).

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made. For example, in order to improve operability, the release switch may be provided on the endoscope main body side, or the release switch may be configured by a foot switch.

〔The invention's effect〕

As described above, according to the present invention, there is provided an endoscope device which can record a still image without color shift and is useful for endoscopic diagnosis.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an endoscope apparatus according to the present invention, FIG. 2 is a diagram showing a rotary filter therein, and FIGS. 3 (a) to 3 (d) are frame sequential imaging systems. FIG. 4A to FIG. 4J are time charts showing the principle of FIG. 4 and the time charts showing the operation of this embodiment. 10 …… Endoscope body, 12 …… Light source unit 14 …… Video processor 16 …… Still image recorder 18 …… Release switch 20 …… Solid-state image sensor, 28 …… Frame memory 38 …… Control circuit, 40… … Lamp 42 …… Rotary filter, 44 …… Step motor

Claims (1)

[Claims] 1. An illuminating means having a rotary filter for sequentially irradiating at least three colors of illuminating light, and an image pickup means of a frame-sequential system for sequentially photographing each color component image in synchronization with the rotation of the rotary filter. An endoscope apparatus comprising: a unit for recording a still image of the image obtained by the image capturing unit; and a speed control unit for increasing the driving speed of the rotary filter when the still image is recorded by the recording unit.