JPH0691881B2 - Endoscope system - Google Patents

Description

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

[Prior art]

In recent years, an endoscope apparatus has been developed in which a solid-state image sensor such as a CCD is provided at the tip of an endoscope to perform color imaging. 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, the illumination light from the light source lamp is sequentially filtered by red, green, and blue, and the images are sequentially photographed under the illumination light of three colors.
A color image signal is generated by obtaining three color component images of red, green and blue, and synthesizing the three color component signals for each pixel.

Here, in the case where a plurality of endoscopes are used at the same time, such as a parent-child type endoscope in which a child endoscope is inserted into a forceps channel, inside the parent endoscope, in the frame sequential imaging method, the following is performed. Problems arise. In the frame-sequential imaging method, the illumination light is sequentially red, green,
The color is switched to blue, but since there is no synchronization among the plurality of endoscopes, the color switching timing of the illumination light may shift between the plurality of light sources. For this reason, illumination lights of different colors are simultaneously emitted from a plurality of light sources, the colors of the illumination lights are mixed, and actual imaging is performed with a component different from the color component to be imaged. This makes it impossible to capture an image with a faithful color.

〔Purpose〕

This invention has been made to deal with the above-mentioned circumstances,
An object of the present invention is to provide an endoscope system capable of capturing an image in a correct color when performing color image capturing in a frame sequential method by simultaneously using a plurality of endoscopes.

〔Overview〕

This object is realized by an endoscope system configured to selectively use either a reference signal generated internally or a reference signal supplied from the outside as a reference signal for switching the color of illumination light.

〔Example〕

An embodiment of an endoscope system according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a single endoscope device that constitutes this system. This endoscope device alone comprises an endoscope body 10, a light source unit 12, and a video processor 14. The endoscope body 10 is provided at the distal end inside the body cavity,
Alternatively, a solid-state image sensor (for example, CCD) 16 that images the inside of the cavity
And a light guide 20 formed of an optical fiber bundle that guides the illumination light from the light source unit 12 to the tip and irradiates the illumination light into the body cavity or the cavity from the tip. Since the tip of the endoscope is narrow, the solid-state image sensor 16 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 image sensor 16 is a preamplifier
CM in video processor 14 as a two-phase signal via 18
It is supplied to the R amplifier 22.

The output signal of the CMR amplifier 22 is the sample / hold circuit 24, A
The frame memory 30-1, through the / D converter 26 and the selector 28,
It is written in either 30-2 or 30-3. Image signals of red (R), green (G), and blue (B) color components are written in the frame memories 30-1, 30-2, and 30-3. The outputs of the frame memories 30-1, 30-2, 30-3 are D / A converters 32-
The signals are output from the R, G, B signal output terminals 35-1, 35-2, 35-3 via 1, 32-2, 32-3 and low pass filters 34-1, 34-2, 34-3. These signal output terminals 35-1, 35-2, 35-3 are supplied to, for example, a color monitor device, a magnetic disk recording device, or the like.

A driver 36 that generates a clock pulse for driving the solid-state imaging device 16 is also provided in the video processor 14.
Timing of each circuit in the video processor 14 is controlled by timing generators 38 and 40. The writing speed to the frame memory 30 and the reading speed from the frame memory 30 are different, the writing to the frame memories 30-1, 30-2, 30-3 is controlled by the timing generator 38, and the timing generator 40 is used. Frame memory
Reading from 30-1, 30-2, 30-3 is controlled.

The light source unit 12 has a lamp 42 that causes the illumination light to enter the light guide 20. A rotary filter 44 having a shutter function and a function of coloring the illumination light into R, G, B is provided between the light guide 20 and the lamp 42. Rotary filter 44
2 is composed of a disc in which R, G, B color filters 70, 72, 74 are discontinuously arranged on a concentric ring as shown in FIG.
The non-continuous portion between the color filters functions as a shutter that blocks illumination light, that is, light to the solid-state image sensor 16, for reading signals from the solid-state image sensor 16. Through holes 76, 78, 80 for generating read pulses are provided outside the rearmost portion of each color filter 70, 72, 74 in the rotation direction, and outside the light transmitting 76 of the R filter 70 for generating start pulses. Through hole 82
Is provided. The rotary filter 44 is controlled by the speed control circuit 48.
It is driven by a step motor 46 controlled by PLL. At the edge of the rotary filter 44, a photodetector 50 which is composed of an emitting element and a photodetector and which generates a read pulse and a start pulse by receiving the light transmitted through the light transmissions 76, 78, 80, 82 is provided. The start pulse and read pulse output from the photodetector 50 are supplied to the timing generator 38 in the video processor 14 via amplifiers 52 and 54, respectively.
In the light source unit 12, a sync signal generator 56 for generating a sync signal is provided as a reference signal for the speed control circuit 48. The signal from the sync signal generator 56 is supplied to the first input terminal of the selector 58 and the sync signal output terminal 62. A synchronization signal input terminal 60 to which a synchronization signal is supplied from the outside is connected to the second input terminal of the selector 58. The output signal of the selector 58 is PL
It is supplied to the speed control circuit 48 as an L control synchronizing signal.

The operation of this embodiment will be described. First, FIG. 3 (a)-
The principle of the frame sequential imaging method will be described with reference to (e). A synchronizing signal as shown in FIG. 3A is supplied to the speed control circuit 48 via the selector 58. The speed control circuit 48 controls the rotation of the step motor 46 at a speed according to this synchronizing signal. As a result, the rotation filter has the same cycle as this synchronization signal.
44 is rotated and a start pulse is generated at the same cycle as the synchronizing signal as shown in FIG. 3 (b). Rotary filter 44
R, G, and B color filters 70, 72, and 74 are sequentially inserted in the optical path from the lamp 42 to the light guide 20 with the rotation of the lamp, and the illumination light is as shown in FIG. 3 (d). , R, G, and B are sequentially colored at predetermined intervals with the light-shielding period interposed. While the illumination light is colored in each of these colors, the component image of each color is captured. In general, the sensitivity of the solid-state image sensor 16 varies depending on the color and becomes worse in the order of R, G, B. Therefore, the size of the color filters 70, 72, 74 increases in the order of R, G, B. preferable. However, here, for convenience of explanation, the color filters 70, 72, and 74 have the same size, and the illumination time of each component light is uniform.

At each rotation of the rotary filter 44 (at the end of the R illumination), the third
A start pulse is generated as shown in FIG. 3B, and a read pulse is generated at the end of illumination of each component light as shown in FIG. 3C. 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 taken under each color component light is written in the frame memory 30 as shown in FIG. 3 (e). . As a result, frame sequential color imaging is executed.

Next, the entire endoscope system according to this embodiment will be described with reference to FIG. FIG. 4 is a block diagram of a parent-child type endoscope apparatus. Here, the same reference numerals are used for the same parts as in FIG. 1, the constituent elements of the parent endoscope are suffixed with 1, and the constituent elements of the child endoscope are suffixed with 2. The endoscope body is the same as that shown in FIG. 1 and is not shown. The light source unit 12-1 of the parent endoscope and the light source unit 12-2 of the child endoscope are connected by the sync signal output terminal 62-1 and the sync signal input terminal 60-2. Selector 58 in the light source unit 12-1 of the parent endoscope
-1 is switched to the first input side, and the output terminal of the synchronization signal generator 56-1 connected to the first input terminal is connected to the speed control circuit.
Connect to 48-1. The selector 58-2 in the light source unit 12-2 of the child endoscope is switched to the second input side, and the synchronization signal input terminal 60-2 connected to the second input terminal is connected to the speed control circuit 48-2. . As a result, the synchronization signal output from the synchronization signal generator 56-1 in the light source unit 12-1 of the parent endoscope is supplied to the speed control circuit 48-1 via the selector 58-1 and the synchronization signal is generated. It is also supplied to the speed control circuit 48-2 via the output terminal 62-1, the synchronizing signal input terminal 60-2, and the selector 58-2. That is, the rotations of the rotary filters 44-1 and 44-2 of the two light source units 12-1 and 12-2 are PLL-controlled with the same synchronizing signal as a reference. For this reason,
The color switching of the illumination light emitted from the light guides 20-1 and 20-2 is performed synchronously, and the same illumination light is always emitted into the body cavity or the cavity, and the solid-state imaging device of the field sequential imaging method is used. Even if a plurality of images are used at the same time, an image is taken with a faithful color.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, since the start pulse is generated through the through hole 82 similar to that for generating the lead panel, the duty ratio of the start pulse is as low as several percent. Generally, it is preferable that the duty ratio of the reference pulse for PLL control is high. Therefore, in the second embodiment, as shown in FIG.
0 is provided, and the slit 90 generates a start pulse with a duty ratio of 50%.

That is, the synchronizing signal generator 56 of the second embodiment generates a synchronizing signal with a duty ratio of 50% as shown in FIG. 6 (a). The speed control circuit 48 controls the rotation of the step motor 46 at a speed according to this synchronizing signal. As a result, when the rotation of the step motor 46 is synchronized with the synchronizing signal, the photodetector 50 generates a start pulse with a duty ratio of 50% synchronized with the synchronizing signal as shown in FIG. 6 (b). . Other operations are the same as those in the first embodiment.

According to the second embodiment as described above, the PLL control is more accurately performed and the image is captured with the accurate color.

The present invention is not limited to the above-mentioned embodiments, but can be variously modified. In the above description, the plurality of endoscopes are both endoscopes in which the solid-state image sensor is built in the tip, but one is the one in which the solid-state image sensor is built in and the other is the conventional endoscope with an image guide. An image pickup camera may be attached to the eyepiece of the mirror. Furthermore, the relationship between a plurality of endoscopes is not limited to the parent-child type, and a plurality of endoscopes may be used in parallel.
Further, without providing the signal output terminal 62 for outputting the signal from the synchronization signal generator 56 in the light source unit 12 to the outside, when using a plurality of endoscopes, the output of the external synchronization signal generator provided separately is PLL. It may be used as a control reference. That is, in this case, the output of this external synchronization signal generator is connected to the synchronization signal input terminal 60 of all the light source units, the selector 58 in the light source unit is switched to the second input side, and this synchronization signal input terminal 60 is The output of the external synchronization signal generator supplied via the above may be supplied to the speed control circuit 48 as a reference signal.

〔The invention's effect〕

As described above, according to the present invention, when color imaging is performed in a frame sequential method by simultaneously using a plurality of endoscopes, the color switching of illumination light emitted from a plurality of light sources is performed synchronously. An endoscope system capable of capturing an image with a faithful color is provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an endoscope alone which constitutes an embodiment of an endoscope system according to the present invention, and FIG. 2 is a diagram showing a rotary filter in a light source unit of this embodiment,
3 (a) to 3 (e) are timing charts showing the principle of the frame-sequential imaging method in this embodiment, FIG. 4 is a block diagram of the entire endoscope system of this embodiment, and FIG. FIGS. 6 (a) to 6 (e) are timing charts showing the principle of the frame sequential imaging system in the second embodiment, showing the rotary filter in the light source unit in the second embodiment. 10 ... Endoscope body, 12 ... Light source unit, 14 ... Video processor, 16 ... Solid-state image sensor, 20 ... Light guide, 30-1,30-2,30-3 ... Frame memory, 38 , 40 ...
… Timing generator, 42 …… Lamp, 44 …… Rotary filter, 46 …… Step motor, 48 …… Speed control circuit, 56 …… Synchronization signal generator, 58 …… Selector, 60 …… Synchronization signal input terminal, 62 ...... Synchronization signal output terminal.

Claims (1)

[Claims] 1. An endoscope system for picking up color images by a field sequential method, in which illumination light is sequentially switched to at least three colors at predetermined time intervals and imaged for each color component image, the timing of color switching of the illumination light is set. Timing control means for controlling, reference signal generating means for generating a first reference signal indicating the timing of color switching, means for inputting a second reference signal supplied from the outside, and the first reference signal Switching means for selectively supplying one of the second reference signals to the timing control means, and timing control for color switching of illumination light by the first reference signal and illumination by the second reference signal. An endoscope system characterized in that it can be switched with the timing control of light color switching.