JPH04104686A - Video signal processing system of endoscope - Google Patents

Abstract

PURPOSE:To reduce the size of a solid image pickup element by reading an odd numbered-line signal and an even numbered-line signal individually and storing them in a field memory, and reading the odd numbered--line signal and even numbered-line signal out alternately, line by line. CONSTITUTION:After illumination light irradiation of each color, the odd numbered-line signal and even numbered-line signal are read out of the solid image pickup element 40 individually and stored in the field memory 43 through a processor 41 and the odd numbered-line signal and even numbered-line signal are read out of the field memory 43 alternately, line by line. In a one-field period of a display system, image data of one frame consisting of two field signals of an odd numbered and an even numbered field is obtained. Consequently, the number of picture elements of the solid image pickup element 40 is decreased and the size is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a video signal processing method for processing video signals obtained by a solid-state image pickup device mounted on an electronic endoscope.

[Prior art 1] In an electronic endoscope, a solid-state imaging device made of a CCD or the like is provided at the tip of an insertion section inserted into the body, etc., and the solid-state imaging device images the area to be observed and displays it on a monitor device. This allows the display to be displayed as a color image.

Here, since this endoscope is inserted into a dark place such as inside the body, it is necessary to illuminate the observation site when performing observation 1 diagnosis and the like. For this purpose, the endoscope is connected to a light source device, and the illumination light from this light source device is transmitted to the distal end of the insertion section via a light guide built into the endoscope. Illumination light is emitted from a lighting window provided at the tip.

In this way, under illumination from the light source device, an image of the observation target is formed on the solid-state image sensor, thereby accumulating signal charges in each pixel that makes up the solid-state image sensor, and reading out the signal charges. Therefore, as an imaging method using a solid-state image sensor, since it is necessary to reduce the diameter of the insertion section of the endoscope, a single-plate element is usually used, and this solid-state image sensor is driven in a field-sequential manner. Red (R), Green (G), Blue (
B) A system in which field images of each color are acquired, image data is generated from these three field images, and the image data is displayed as a color image on a monitor device is generally used.

Thus, the endoscope device is equipped with an endoscope S as shown in FIG.
, a control device C, and a monitor device M.

The endoscope S includes an insertion section 1 inserted into a body cavity or the like, a main body operation section 2 connected to the proximal end of the insertion section 1, one end connected to the main body operation section 2, and the other end connected to the main body operation section 2. The control device C& is configured to include a universal cord 3 that is detachably connected. Further, the control device C includes a video signal processing device P and a light source device.

An illumination window and an observation window are provided at the distal end of the insertion section l in the endoscope S, and the output end of a light guide for transmitting illumination light faces the illumination window, and an objective provided in the observation window faces the illumination window. A solid-state image pickup device such as a CCD is provided at the image forming position of the lens, but since the configuration of these devices is well known, illustration and specific explanation thereof will be omitted.

A cable connected to the light guide and the solid-state image sensor is inserted from the insertion section l of the endoscope S through the main body operation section 2 and into the universal cord 3.
includes an electrical connector portion 3a for detachably connecting the cable to the video signal processing device P in the control device C;
It branches into a light source connector section 3b for connecting the light guide to the light source device of the control device C. Further, on the control device C side, a socket 4a for connecting these electrical connector sections 3a and a socket 4b for connecting the light source connector section 3b are provided.

Next, as is clear from FIG. 5, the light source device built into the control device C has a light source lamp 10, and in order to condense the illumination light from the light source lamp IO onto the light guide ll, A condensing lens 12 is provided so as to face the optical path of the illumination light. In order to control the amount of light from the light source depending on the position of the observation target, etc., a light source lamp IO and a condensing lens 1 are used.
A light amount diaphragm member 13 is interposed between the two. Further, a rotating color filter device 20 is installed between the condenser lens 12 and the incident end 11a of the light guide 11.

The rotating color filter device 20 is for filtering the white light emitted from the light source lamp IO and inputting it into the light guide 11, and as is clear from FIG. The color wheel 21 has filter regions 21R, 121G and 21B that selectively transmit R, G, and B wavelength light, and these adjacent One light beam @21BL is formed on the filter mounting area. This color wheel 21 is attached to a rotating shaft 22, and the color wheel 21 is moved by a motor 23.
By rotationally driving the light source using the light source, sequential illumination with R, G, and B wavelength light is performed.

Next, FIG. 7 shows the circuit configuration of the video signal processing device P.

A CCD 30 as a solid-state image sensor is attached to the tip of the insertion section 1 of the endoscope S, and signals from the CCD 30 are sent to the power supply connector 3a via the insertion section 11, main body operation section 2, and universal cord 3 in sequence. The signal is transmitted from the control device C to the video signal processing device P in the control device C.

When imaging a subject with the CCD 30, the light source device sequentially emits illumination light in the R, G, and B wavelength ranges every 16.6 ms, as shown in FIG. 8(a). During this period, the CCD 30 is exposed. Then, when the light shielding area 21BL faces the illumination optical path, the CCD
Signal charges are read from 30. The signals read out in this way are transmitted to the video processor 31, where they are subjected to processing such as clamping, blanking, gamma correction 1 contour correction, and white balance. As shown in Figure (b), image signals of each color of R, G, and B are sequentially output.

The output signal from this video processor 31 is
The R memory area 33R, G memory area 33G, and B memory area 33B are converted into digital signals through the A/D converter 32 and constitute the field memory 33.
are written sequentially. When the color data for each color for one frame is written, the D/A converters 34R, 34
G, 34B, these data are simultaneously read out and mixed in the color encoder 35, and the NTS
It is output as a composite video signal such as C.

Here, as is clear from FIG. 8(C), in the field memory 33, when image data of each color of R, G, and B is input, only the data of this color is updated.
This and the data of the other two colors in the previous field recorded in the field memory 33 are read out simultaneously.

Further, the composite video signal outputted from the color encoder 35 consists of an odd field (0) signal and an even field (E) signal, as shown in FIG. 8(d).

[Problem to be solved by the invention 1 By the way, solid-state image sensors used in endoscopes include:
In general, an accumulation area has approximately half the number of pixels in the vertical direction as the light receiving area. For this reason, when obtaining color data for one color, two-pixel portion reading is performed by adding two pixels in the vertical direction.

Generally, when performing an interlacing operation and mixing two pixels in the vertical direction, a certain point on the scanning line is
For each line, an odd field signal and an even field signal can be obtained by adding the previous line or the next line, and interlaced display can be performed based on these two types of field signals. I try to do it. However, in an endoscope, usually only one of these two types of field signals, for example, an odd field signal, is read out.

By the way, since endoscopes are inserted into the body, the outer diameter of the insertion part l should be as large as possible in order to smoothly pass through narrowed areas and in consideration of alleviating patient pain. It must be made thinner. Since the solid-state imaging device such as a CCD constituting the imaging means is built into the distal end of the insertion section 1,
There is a significant demand for miniaturization of this solid-state image sensor. In order to meet the demand for miniaturization of solid-state image sensors,
It is possible to reduce the number of pixels or reduce the area of the unit pixels that make up the element. However,
If the number of pixels in the element is reduced (there is a problem that the resolution will be significantly reduced), and if the area of the unit pixel is reduced, the sensitivity will be reduced and the dynamic range will also be significantly reduced. There is a limit to reducing the area of this unit pixel.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a video signal processing method that has high resolution and can use a compact solid-state image sensor. It's about doing.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a solid-state imaging device and a system that exposes the solid-state imaging device to sequential illumination of each color of R, G, and B. It has a video processor for reading out the obtained signal charge and processing the signal, and a field memory for storing output data from the video processor, and reads an image signal from this field memory and displays it on a monitor device. In the device, after irradiation with illumination light of each color, signals of odd lines and signals of even lines in the solid-state image sensor are read out separately, these signals are stored in the field memory via a processor, and the signals are read out from the field memory. The readout is characterized in that the odd line signal and the even line signal are alternately read out for each line.

[Effect 1] In recent years, high-sensitivity solid-state imaging devices have been developed, and compared to conventional CCDs, they have approximately twice the sensitivity, have an excellent dynamic range, and have a higher R, G, and H spectral sensitivity ratio. Products with improved properties are now being used. Therefore, with such a highly sensitive element, conventional CCD
In comparison, the number of pixels in the vertical direction is approximately half, and the number of pixels in the horizontal direction is approximately the same. If this element is driven at high speed, two field data can be obtained in the imaging system within one field period in the display system. Therefore, during this time, odd field signals are obtained by reading odd lines in the scanning line, and the next field data is as follows.
Read out even lines to obtain even field signals.

The two field signals obtained in this way are stored in respective field memories, and are read out alternately line by line from the field memories. As a result, image data for one frame consisting of two field signals of an odd field and an odd field in the solid-state image sensor can be acquired within one field period in the display system.

Therefore, based on the image data for one frame obtained in this way, the field data of odd and even fields in the display system is transmitted to the monitor device and displayed on the monitor device. As a result, compared to the conventional endoscope system that uses the aforementioned conventional CCD and performs two-pixel mixed readout by adding two lines in the vertical direction, and reads out only one field signal, the vertical Resolution improves. Moreover, since the number of pixels in the solid-state image sensor can be reduced in this way, it is possible to downsize the solid-state image sensor. Also,
Also, since the area of the unit pixel can be increased,
There is no reduction in dynamic range.

[Embodiment 1] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, FIG. 1 shows the configuration of an apparatus for implementing the video signal processing method according to the present invention.

In the figure, 40 is a CCD, 41 is a video processor that processes video signals obtained by the CCD 40;
42 is a D/A converter, 43 is a field memory for storing signals from the D/A converter 42, 44R144G, 44
B indicates a D/A converter, and 45 indicates a color encoder.

Here, the CCD 40 constituting the imaging means uses a so-called frame interline transfer method (FIT
) is used. That is, as is clear from Figure 2,
The CCD 40 has light receiving sections P and vertical transfer paths VCCO arranged alternately, and a horizontal transfer path HCCD connected to the vertical transfer path VCCD.
Compared to the CCD 30 described in the prior art, a CCD 30 having twice the sensitivity is used, and the number of pixels in the light receiving section P is approximately half in the vertical direction. Further, the horizontal transfer path HCCD is half the length of the vertical transfer path VCCD. However, in order to maintain good resolution in the horizontal direction, the number of pixels in the horizontal direction is
It should not be much different from 30.

Therefore, when such a small and highly sensitive CCD 40 is used, signal processing must be performed using a method different from that of the CCD 30.

That is, from the light source device, as shown in FIG. 3(a),
For example, the illumination light by the wavelength range light of each color of R, G, and B is 1
The light is irradiated sequentially every 6.6 ms, and the CCD 40 is exposed during this period. For example, signal charges are accumulated in the light receiving part P by illumination using the R filter region, but when the light-blocking period begins, as shown in FIGS. The pixel signal at is moved to the vertical transfer path VCC[), and then transfer from the vertical transfer path VCCD to the storage section S starts to be transferred tROVT). When this transfer to the storage section S is completed, a horizontal transfer pulse causes a 1
The signal charge is transferred line by line to the horizontal transfer path HCCD (ROMTI), and this signal charge is read out to the video processor 4.
1. Immediately after the signals on the odd lines are transferred to the horizontal transfer path HCCD, the pixel signals on the even lines are transferred to the empty vertical transfer path VC.
The horizontal transfer path HCC after the odd line signals are transferred to the CD, further transferred to the storage section S (REVT), and the odd line signals are read out.
The signals are read out from the horizontal transfer path HCCD by transferring (REHTI) one line at a time to D. As a result, the readout of signal charges from the CCD 40 in the R field is completed, and two lines of odd and even lines are read out.
Image data of an R field consisting of two fields is obtained.

Thereafter, the G filter area and the B filter area are sequentially and repeatedly exposed to the illumination optical path, and image data of these G and R fields are acquired.

Here, in acquiring the image data of each field in the CCD 40, the pixel signals of the odd lines are moved to the vertical transfer path VCCO, and the pixel signals of the odd lines are
, CD to the storage section S, the pixel signals of even-numbered lines must be shielded from light until the transfer to the storage section S is completed. However, from the perspective of improving sensitivity,
The shading period must be shortened as much as possible. For this purpose, a transfer pulse from the vertical transfer path vcco to the storage section S,
Shorten the pulse interval of the transfer pulse from the storage section S to the horizontal transfer path HCCD and the read pulse from the horizontal transfer path HCCD. By performing high-speed transfer in this manner, the light-blocking period can be shortened.

By driving the CCD 40 as described above, the output signal from the video processor 41 is transmitted to one of the CCDs 30.
Odd line data and even line data for each of R, G, and H colors are sequentially obtained in time series during a period corresponding to one field.

Then, this data is converted into a digital signal by the A/D converter 42, and the R, G and G signals are stored in the field memory 43.
, B are written in the respective memory areas 43R, 43G, and 43B. Here, memory areas tiji 43R and 43G.

43B are odd memory areas 43RO, 43GO, and
43BO and even memory area 43RE, 43GE, 4
It can be divided into 3GE. However, in reality, the odd memory area and even memory area are processed by processing addresses in the memory area, and the memory area is not divided into two. Note that each of these memory areas 43R
, 43G, and 43B is performed for each frame of data of each color, including two pieces of odd and even data.

When the data of each color written in the field memory 43 in this way is read out to the color encoder 45 via the D/A converters 44R, 44G, and 44B,
Lines are read alternately from the odd memory area and the even memory area. As a result, the color encoder 45 has the following information:
As shown in FIG. 3(ri), each D/A converter 4
The data of each color is read out simultaneously through 4R, 44G, and 44B, and as a result, a composite video signal of odd and even fields is obtained as shown in FIG. 3(e), and this signal is monitored. It will be displayed on the screen.

With this configuration, the resolution in the vertical direction becomes extremely good, and the dynamic range and the spectral sensitivity ratio of R, G, and B can also be maintained at a high level. In an endoscope, even if the outer diameter of the insertion part is reduced only slightly, a remarkable effect can be achieved, so even with this level of miniaturization, It's advantageous.

[Effects of the Invention 1] As explained above, the present invention reads out signals of odd lines and signals of even lines in a solid-state image sensor separately after irradiation with illumination light of each color, and processes these signals through a processor. Since the signals are stored in the field memory and read from the field memory, odd line signals and even line signals are alternately performed for each line.
The number of pixels in a solid-state image sensor can be reduced, making it possible to downsize the solid-state image sensor, and as a result, it is possible to reduce the outer diameter of the insertion section of the endoscope as a whole. becomes.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a circuit configuration diagram of a signal processing device, and FIG. 2 is a circuit diagram of a signal processing device.
An explanatory diagram of the operation of D, Fig. 3 (a) shows the irradiation period of the illumination light,
Figure (b) shows the transfer timing from the light receiving section to the storage section.
Figure 4 (C) shows the read timing from the KCCD, Figure 4 (d) shows the output signal from the memory, and Figure 4 (d) shows the output signal of the color encoder.
Figures to Figures 8 show the prior art, in which Figure 4 is an overall configuration diagram of an endoscope device, Figure 5 is an explanatory diagram of the configuration of a light source device, Figure 6 is an explanatory diagram of the configuration of a color wheel, Figure 7 is a circuit configuration diagram of the signal processing device, Figure 8 (a) shows the illumination light irradiation period, Figure 8 (b) shows the output signal of the video processor at that time, and Figure 8 (c) shows the output signal from the memory. The output signal is shown in the same figure (
d) is a characteristic diagram showing the output signals of the color encoder. 1: Insertion section, 2. Main unit operation section, 3 universal cord, 3a: Electrical connector section, 3b = Light source connector section, lO
:Light source lamp, 11 light guide, 30: CCD, 4
0: CCD, 41: Video processor, 44: Field memory, 46: Color encoder. Figure 1 Patent Applicant Fuji Shakoki Co., Ltd. Agent Patent Attorney Advocate Toshitsugu - Figure 1G Figure 1G Procedural Amendment December 7, 1990

Claims (1)

[Claims] A solid-state image sensor, a video processor for reading signal charges obtained by exposing the solid-state image sensor under sequential illumination of each color of R, G, and B, and processing the signal; and a field memory for storing output data of the solid-state image sensor, and reads image signals from the field memory and displays them on a monitor device, after irradiation with illumination light of each color, signals of odd lines and even lines of the solid-state image sensor are read out and displayed on a monitor device. and the signals are read out separately and stored in the field memory via a processor, and reading from the field memory is performed alternately for each line of the odd line signal and the even line signal. Features video signal processing method for endoscopes.