JPS6266221A - Optical pulse irradiating method in television type endoscope device - Google Patents

Abstract

PURPOSE:To widely decrease the blurring and the color dislocation to occur while the picture signal of the moving object is accumulated by irradiating the optical pulse in the shortest period ranging to two field periods or above. CONSTITUTION:The phase of the optical pulse controlled by a pulse phase control device 8 is once at the terminal part of one field period (first field period), and plural times in the short period, and once at the starting edge part of the next field period (second field period) and plural times in the short period, and the light quantity of the optical pulse generated ranging to the blanking period is the same quantity. Namely, the irradiation of the optical pulse is executed in the shortest period T2 ranging to two field periods. usually, since T2/T1 is 1/13-1/15, the picture can be easily catched at the period of about 1/10 of 1/60sec which is one field period, and the case is the equal value to the case when the camera shutter speed is cut at 1/600sec. Thus, the shading of the stationary picture can be widely decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a light pulse irradiation method in a television-type endoscope apparatus using a solid-state image sensor.

[Technical background of the invention and its problems]

Conventionally, when viewing endoscopic images on a television monitor, a television camera was attached to the eyepiece of the fiberscope. Recently, however, solid-state imaging devices have become smaller, and a method of storing them at the tip of an endoscope probe and directly displaying images of the subject on a TV monitor without going through an image fiber is now available for diagnosis and treatment. It started to be taken.

As shown in Fig. 2, an example of the structure of a solid-state image sensor includes independent photosensitive sections (pz)...(P□), vertical transfer sections (CV,'), (CV,), and , Gate (Gz
) ... (G Each photosensitive area (
Gates CG+,
)...(G□), new accumulation starts from the time this transfer is completed, and the transferred charges are sequentially sent to the horizontal transfer section (H) according to the TV system ° and taken out to the outside. It looks like this. Therefore, when a solid-state image pickup device is used, no problem occurs even if the subject is irradiated with pulsed light. For this reason, in the current light irradiation, a light pulse is irradiated in a period (T1) corresponding to the beginning of the field period, as shown in FIGS. 3(a) and 3(b). . In addition, when extracting signals from a solid-state image sensor using an interlaced method, it is generally used to simultaneously extract signals from two vertically adjacent photosensitive sections because it is advantageous in terms of afterimage characteristics. Since signals are extracted from all photosensitive areas for each field, the accumulation period is one field period (i.e., the same period as the above-mentioned period T, generally 1/6o second), and is known as field accumulation mode. It is being

By the way, diagnosis and treatment are performed by doctors observing images in real time, but it is also possible to perform a more objective diagnosis.
It is also necessary to record images to monitor the progress of treatment.
Generally, photography is used.

Therefore, when using a conventional fiberscope, a camera was attached to the eyepiece of the probe to take photographs. Since the subject was constantly moving, the shutter speed was set to 1/125 seconds or faster, and the lack of light was compensated for with a flash light source.

On the other hand, when a solid-state image sensor is used, in order to take a photograph of the image on the TV monitor, a method is used to temporarily turn the normal image into a still image. Built-in memory, 1
Frame images are stored in this memory so that the stored images can be retrieved many times. In order to capture one frame of image into the frame memory, in a normal television system, it takes 1/3o seconds equivalent to two field periods.

However, in the light pulse irradiation method in the current TV-type endoscope device as described above, the light pulse is irradiated in a period (T,) that corresponds to the beginning of the field period, as described above. There is a drawback that the still image is blurred by the movement of the subject during this period (T+).

In addition, each of the three primary colors, for example, red (R), green (G), and blue (B), is sequentially irradiated onto the subject field by field, and image signals for each light are captured from the solid-state image sensor into respective memories. An endoscope device that obtains a color image signal by combining the output signals from the memory has been put into practical use, but in the case of continuous light irradiation, it takes three field periods to capture the signals for each target into the memory. (about 1/20 seconds)
Since this method requires 200 kHz, it cannot handle moving subjects, and in fact, color breakage occurs, which is a major hindrance in recording still images. Even when pulsed light as shown in FIG.
), it took 1730 seconds to complete one set of light irradiation, so it was still not possible to obtain a sufficient still image.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide a light pulse irradiation method that can reduce blurring and color breakage in still images.

[Summary of the invention]

The outline of the present invention for achieving the above object is to irradiate light pulses within the shortest period of time spanning two or more field periods to eliminate blurring, etc. that occurs while storing image signals of a moving subject. The reason is that I tried to minimize it as much as possible.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of a television endoscope apparatus according to the present invention. First, this device will be explained.

Reference numeral 1 denotes an endoscope probe, in which an optical system such as an objective lens 2 and a solid-state image pickup device 3 are incorporated in its tip.

A specific example of the solid-state image sensor 3 is shown in FIG. 2, and the details are as described above. Further, an output end 12 of a light guide is arranged at the tip of the probe, and a light source lamp 9 is provided.
The light incident on the light guide light source side end 11 is emitted to the subject 13 as illumination light a.

Note that 10 is a cold mirror.

A video processor 5 inputs field image signals from the solid-state image sensor 3 through a transmission line 4, generates frame images from the field images, and includes a frame memory for storing the generated frame images.

Reference numeral 6 denotes a TV monitor which inputs a video signal from the video processor 5 and is capable of displaying frame images as moving images or still images.

Reference numeral 7 is a pulse power source, which lights the light source lamp 9 in pulses. The trigger of the pulse power supply 7 is
This is done by a pulse phase controller 8, with the original pulses supplied to the pulse phase controller being derived from the vertical synchronization signal of the television camera circuit built into the video processor 5.

As mentioned above, the current optical pulse irradiation method is shown in Fig. 3 (a).
), but in the light pulse irradiation method of the present invention, the light pulse irradiation is performed within the shortest period spanning two or more field periods.

First, the first . A case will be described in which one frame image is generated from the second field image signal. In this case, as shown in FIGS. 3(b) and 3(c), the phase of the optical pulse controlled by the pulse phase control device 8 is changed once at the end of one field period (first field period). Or multiple times within a short period, and once at the beginning of the next field period (second field period), or multiple times within a short period, and the amount of light pulses emitted over the blanking period is the same amount. shall be.

That is, the light pulse irradiation was performed during the shortest period (T2) spanning two field periods.

Normally, T 2 / T + is 1/13 to 1/15, so by controlling the phase of the optical pulse as described above, an image can be captured in a period of approximately 1710 seconds, which is 1760 seconds, which is one field period. It is easy to capture, and in this case, it is equivalent to setting the camera shutter speed to 1/600 second. Therefore, blurring of still images can be significantly reduced.

Note that a rotating disk having a plurality of openings may be provided just before the light source side end 11 of the light guide (see 14 in Fig. 1).
, the same effect can be obtained by rotating it in synchronization with a vertical synchronizing signal and adjusting the timing of light passage to match the timing shown in FIG. 3(b).

Next, the field sequential color imaging method is adopted, that is, the first .
Second. 3. A case in which one color frame image is generated from three field image signals will be described.

In this case, in a TV-type endoscope apparatus using a field sequential color imaging method, the light source lamp 9 shown in FIG.
A disk 14 is placed in the optical path of a light source device including a cold mirror 10 and the like. The disk 14 is the first. Second. A rotating disk with a three-color filter equipped with a third color transmission filter 15°16.17; Second. The third color is, for example, red (
R), green (G), and blue (B).

Therefore, the disk 14 is rotated to guide the three types of light sequentially to the light source side end 11 of the light guide, and the pulse power source 7
and the pulse phase control device 8, each filter 15,
The light passing through 16.17 is pulsed light, and the timing of the light pulse generation is as shown in FIG. 5(b).
The R light is emitted at the end of the first field, the G light is emitted at an arbitrary time in the second field, and the B light is emitted at the start of the third field, and the subject is sequentially illuminated through the light guide. Make it.

That is, the light pulse irradiation was performed during the shortest period (Tz') spanning three field periods.

As a result, the three types of light irradiation can be performed within a period (Tz') that slightly exceeds one field period, whereas the current method can be applied within a period of two fields (Tz') as shown in Fig. 5(a). T+'
), blurring and color breakup can be significantly reduced.

Also, even in this case, image blur and color shift due to the movement of the subject that occurs within the (Tz') period are unavoidable;
By changing the phase of the G light pulse depending on the color tone within the body cavity, it is possible to actually make the color shift less noticeable.

For example, when R and G are dominant color tones, the timing of the G pulse should be close to the timing of the R light pulse. Furthermore, if image blur and color misregistration become a problem, the B light can be cut, even if it means sacrificing some color reproducibility. That is, in extreme cases, a still image may be obtained by using two colors of irradiation light depending on the color tone of the subject. However, rather than sacrificing color reproducibility, it is possible to double the field rate and complete the three types of light irradiation in half the time of the normal field period (1/60 seconds), making it possible to improve the We were able to approach the camera shutter speed of 1/125 seconds, which resulted in a significant improvement.

Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and can be modified as appropriate within the scope of the gist of the present invention.

In addition, in order to facilitate understanding of the invention, the term "minimum period" is used, but this does not strictly mean the period between the rear end of one field and the front end of another field; ) (T2') means a period with a certain degree of width within the range in which the purpose of the present invention can be achieved.

〔Effect of the invention〕

As described in detail above, according to the present invention, by irradiating light pulses within the shortest period spanning two or more field periods, blurring and color shift that occur while storing image signals of a moving subject can be avoided. It is possible to significantly reduce the amount of time required, obtain high-resolution frame still images, and make an extremely large contribution to improving efficiency and diagnostic performance at the diagnostic site.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a television-type endoscope device according to the present invention, FIG. 2 is a schematic explanatory diagram showing an example of a solid-state image sensor, and FIGS. Drawings showing the phase relationship between pulses and image signals, FIG. 4 is a front view showing an example of a three-color filter rotary plate, and FIG. It is a drawing showing a phase relationship. 3... Solid-state image sensor, 5... Video processor, 6
... TV monitor, 7... Pulse power source, 8... Pulse phase control device, (TZ) (TZ')... Minimum period.酩Z″7transferred8關

Claims (4)

[Claims] (1) A solid-state image sensor in which a large number of pixels are arranged, a means for irradiating a subject with light pulses, a means for storing one frame image generated from continuous field image signals from the solid-state image sensor; A television-type endoscope apparatus equipped with means for displaying frame images as a moving image or a still image, characterized in that the irradiation of the light pulse is performed within a shortest period of time spanning two or more field periods. A light pulse irradiation method in a type endoscope device. (2) When generating one frame image from the first, second, and second field image signals of continuous field image signals from the solid-state image sensor, the irradiation of the light pulse is
2. A method of irradiating light pulses in a TV-type endoscope apparatus according to claim 1, wherein the light pulse irradiation is performed at the end of a field period and the beginning of a second field period. (3) Continuous first, second, third,
When a color one-frame image is generated from three field image signals, the light pulse is irradiated with a first color at the end of the first field period and a second color at the position of the second field period. A light pulse irradiation method in a TV-type endoscope apparatus according to claim 1, wherein the light pulse irradiation is performed in the third color at the beginning of the third field period. (4) A light pulse irradiation method in a TV-type endoscope apparatus according to any one of claims 1 to 3, wherein a plurality of light pulses are further emitted at one time.