JP3038838B2 - Endoscope video signal processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video signal processing method for processing a video signal obtained by a solid-state imaging device mounted on an electronic endoscope.

[Prior Art] In an electronic endoscope, a solid-state imaging device made of a CCD or the like is provided at the tip of an insertion portion to be inserted into a body or the like, and an image of a part to be observed is taken by the solid-state imaging device. It can be displayed as a color image.

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

As described above, under the illumination from the light source device, the image of the observation target portion is formed on the solid-state imaging device to accumulate signal charges in each pixel constituting the solid-state imaging device, and the signal charges are read out. In the imaging method using the solid-state imaging device, since it is necessary to reduce the diameter of the insertion portion of the endoscope, usually, a single-plate device is used, and the solid-state imaging device is driven by a plane sequential method. A field image of each color of red (R), green (G), and blue (B) is obtained, image data is generated from these three field images, and displayed as a color image on a monitor device. It is commonly used.

As shown in FIG. 4, the endoscope apparatus generally includes an endoscope S, a control device C, and a monitor device M. The endoscope S includes an insertion portion 1 inserted into a body cavity or the like,
A structure including a main body operating portion 2 connected to a base end portion of the insertion portion 1 and a universal cord 3 having one end connected to the main body operating portion 2 and the other end detachably connected to the control device C. It has become. Further, the control device C includes a video signal processing device P and a light source device L.

An illumination window and an observation window are provided at a distal end portion of the insertion section 1 of the endoscope S, an emission end of a light guide for transmitting illumination light faces the illumination window, and an objective provided in the observation window. A solid-state image pickup device such as a CCD is provided at the image forming position of the lens. However, since these structures are well known, their illustration and specific description are omitted.

A cable connected to the light guide and the solid-state imaging device is inserted from the insertion section 1 of the endoscope S through the main body operation section 2 to the universal cord 3. Electric connector 3a for detachably connecting to video signal processing device P
And a light source connector 3b for connecting the light guide to the light source device L of the control device C. On the control device C side, a socket 4a for connecting the electric connector 3a and a socket 4b for connecting the light source connector 3b are provided.

Next, as is apparent from FIG. 5, the light source device L incorporated in the control device C has a light source lamp 10, and in order to collect illumination light from the light source lamp 10 to the light guide 11, The condenser lens 12 is provided so as to face the optical path of the illumination light. In order to control the light source light amount according to the position of the observation target portion and the like, a light amount stop member 13 is interposed between the light source lamp 10 and the condenser lens 12. Further, a rotating color filter device 20 is mounted between the condenser lens 12 and the incident end 11a of the light guide 11.

The rotary color filter device 20 is for filtering white light emitted from the light source lamp 10 and entering the light guide 11, and as is apparent from FIG. 6, a plurality of filter areas are formed in an arc shape. A color wheel 21 having a filter track formed thereon. The color wheel 21 has a filter area 2 for selectively transmitting light of each wavelength of R, G, and B.
1R, 21G, and 21B are formed, and a light shielding area 21BL is formed between these adjacent filter areas. The color wheel 21 is mounted on a rotating shaft 22, and the color wheel 21 is rotationally driven by using a motor 23, so that R,
Illumination is sequentially performed with light of each wavelength of G and B.

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

The CCD 30 as a solid-state image pickup device has an insertion section 1 for the endoscope S.
The signal from the CCD 30 is transmitted from the power supply connector 3a to the video signal processing device P in the control device C via the insertion portion 1, the main body operation portion 2 and the universal cord 3 sequentially. Has become.

When imaging an object with the CCD 30, the light source device L
Thereafter, as shown in FIG. 8 (a), the illumination light of the wavelength region light of each color of R, G, B is sequentially irradiated, for example, every 16.6 ms, and the CCD 30 is exposed during this time. And the light-blocking area 21BL
Is read from the CCD 30 when the light beam approaches the illumination light path. The signal read in this way is transmitted to the video processor 31 and the video processor 31
, After processing such as clamping, blanking, gamma correction, contour correction, and white balance is performed,
As shown in FIG. 7B, image signals of each color of R, G, B are sequentially output. The output signal from the video processor 31 is converted into a digital signal through an A / D converter 32, and is converted into a digital signal.
The data is sequentially written to the memory area 33R, the G memory area 33G, and the B memory area 33B. When the color data of each color for one field is written, these data are simultaneously read out via the D / A converters 34R, 34G, and 34B, mixed in the color encoder 35, and mixed with a composite such as NTSC. It is output as a video signal.

Here, as is apparent from FIG. 8 (c), when image data of each color of R, G, and B is input to the field memory 33, only the data of this color is updated. The data of the other two colors in the previous field recorded in the memory 33 are simultaneously read. Also,
The composite video signal output from the color encoder 35 includes an odd field (O) signal and an even field (E) signal, as shown in FIG. 8 (d).

[Problems to be Solved by the Invention] By the way, a solid-state imaging device used for an endoscope generally has a storage area having approximately half the number of pixels in a vertical direction with respect to a light receiving area. For this reason, when obtaining color data of one color, a two-pixel mixed read in which two pixels in the vertical direction are added is performed.

Generally, when two pixels in the vertical direction are mixed by performing an interlace operation, one line on a scanning line is added with a line before the line, or
Depending on whether the next line is added, an odd field signal and an even field signal can be obtained,
Interlaced display is performed based on these two types of field signals. However, in the endoscope, usually, only one field signal, for example, an odd field signal is read out of these two types of field signals.

By the way, since the endoscope is inserted into the body or the like,
The outer diameter of the insertion section 1 must be made as small as possible in order to smoothly pass through a stenotic site and in consideration of alleviation of pain of the patient. Since the solid-state imaging device such as a CCD constituting the imaging means is built in the distal end portion of the insertion section 1,
The demand for miniaturization of this solid-state imaging device is extremely large. In order to cope with such a demand for downsizing the solid-state imaging device, it is conceivable to reduce the number of pixels or reduce the area of a unit pixel constituting the device. However, when the number of pixels of the element is reduced, there is a problem that the resolution is remarkably reduced, and when the area of the unit pixel is reduced, there is a disadvantage that the sensitivity is reduced and the dynamic range is significantly reduced. There is a limit in reducing the area of the unit pixel.

The present invention has been made in view of the above points, and has as its object to provide a video signal processing method having a high resolution and capable of using a small solid-state imaging device. Is to do.

[Means for Solving the Problems] In order to achieve the above-described object, the present invention provides a solid-state imaging device including a storage unit in which the number of pixels in a direction perpendicular to a light-receiving unit is approximately half, and each of R, G, and B An illumination means for sequentially illuminating the subject with a light-blocking period in between, and a video processor, and exposing the light-receiving unit in each lighting period, and a signal from the light-receiving unit via the storage unit in the subsequent light-blocking period. The electric charge is read out, an image signal is generated by the video processor and written in a field memory, and the image signal from the field memory is read out to display an image of a subject on a monitor device. The signal charge is read twice from the solid-state imaging device by frame interline transfer during the light shielding period,
One of them reads the signal charges accumulated in the odd lines in the horizontal line of the light receiving section, and the other reads the signal signals of the even lines, and writes them to the field memory as odd line signals and even line signals, respectively. The odd-line signal and the even-line signal are alternately read from the field memory line by line.

[Operation] In recent years, high-sensitivity solid-state imaging devices have been developed,
Compared to conventional CCDs, those having approximately twice the sensitivity, excellent dynamic range, and a good spectral sensitivity ratio of R, G, and B have come to be used.
Accordingly, such a high-sensitivity element having a pixel number in the vertical direction that is approximately half the number of pixels in the conventional CCD and having substantially the same number of pixels in the horizontal direction is used. 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, an odd-numbered field signal is obtained by reading out an odd-numbered line in the scanning line, and an even-numbered field signal is obtained as the next field data by reading out an even-numbered line.

The two field signals thus obtained are stored in respective field memories, and are alternately read from the field memories line by line. This makes it possible to acquire one frame of image data composed of two field signals of the odd field and the even field in the solid-state imaging device 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 the odd field and the even field in the display system are transmitted to the monitor device,
The information is displayed on the monitor device. As a result, compared with the conventional endoscope in which the conventional CCD described above is used to perform two-pixel mixed readout by adding two lines in the vertical direction and read out only one field signal, the endoscope in the vertical direction is used. Resolution is improved. In addition, since the number of pixels in the solid-state imaging device can be reduced as described above, the size of the solid-state imaging device can be reduced. Also,
Because the area of the unit pixel can be increased,
It does not reduce the dynamic range.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows a device configuration for implementing a video signal processing method according to the present invention.

In the figure, 40 is a CCD, 41 is a video processor for processing a video signal obtained by the CCD 40, 42 is a D / A converter, 43 is a field memory for storing a signal from the D / A converter 42, 44R , 44G, and 44B indicate D / A converters, and 45 indicates a color encoder.

Here, a so-called frame interline transfer method (FIT) is used as the CCD 40 constituting the imaging means. That is, as is apparent from FIG.
And the vertical transfer path VCCD are alternately provided.
The CCD 40 is provided with a horizontal transfer path HCCD so as to be connected to the CCD.
Compared to CD30, use one with almost twice the sensitivity,
In addition, the number of pixels in the light receiving portion P is substantially halved in the vertical direction. The horizontal transfer path HCCD is half 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 not so different from that of the CCD 30.

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

That is, as shown in FIG. 3 (a), the illumination light from the wavelength region light of each color of R, G, B is emitted from the light source device, for example, as shown in FIG.
Irradiation is performed every 6 ms, and the CCD 40 is exposed during this time. Then, for example, signal charges are accumulated in the light receiving portion P by performing illumination by the R filter area. When the light receiving section P enters a light shielding period, first, as shown in FIGS. Move to the vertical transfer path VCCD, and then start transfer (ROVT) from the vertical transfer path VCCD to the storage unit S. When the transfer to the storage section S is completed, the horizontal transfer pulse HC is transferred line by line by the horizontal transfer pulse.
Transfer (ROHT) to CD, this signal charge is read out,
The data is transmitted to the video processor 41. Immediately after the signals on the odd lines are transferred to the horizontal transfer path HCCD,
The pixel signal in the even line is moved to the empty vertical transfer path VCCD, and further transferred to the accumulation unit S (REV
T) and the horizontal transfer path H after the odd line signal is read out
The horizontal transfer path HCC is transferred (REHT) line by line to the CCD.
A signal is read from D. That is, two signal charges are read from the CCD 40 during one light-shielding period, and one of them reads the signal charges in the odd-numbered horizontal lines of the light-receiving unit P, Another time, the signal charges of the even lines are read. In this manner, in the R field, when the reading of the signal charges from the CCD 40 is completed twice, the R field composed of the two fields of the odd line and the even line is obtained.
Field image data is generated.

Hereinafter, the G filter area and the B filter area sequentially and repeatedly face the illumination light path, and the image data of these G fields and R fields are acquired.

Here, in obtaining the image data of each field in the CCD 40, at least the pixel signals of the odd lines move to the vertical transfer path VCCD, and after the transfer from the vertical transfer path VCCD to the storage unit S starts, Until the transfer of the pixel signal of the line to the storage unit S is completed, the light must be shielded. However, from the standpoint of improving sensitivity, the light-shielding period must be reduced as much as possible. For this purpose, the pulse intervals of the transfer pulse from the vertical transfer path VCCD to the storage section S, the transfer pulse from the storage section S to the horizontal transfer path HCCD, and the read pulse from the horizontal transfer path HCCD are shortened. By performing the high-speed transfer in this manner, the light-shielding period can be shortened.

By driving the CCD 40 as described above, the output signal from the video processor 41 can output the odd-line data and the even-line data for each color of R, G, and B during one field of the CCD 30. Are sequentially obtained in time series. Then, this data is converted into a digital signal by the A / D converter 42, and
The data is written to the R, G, and B memory areas 43R, 43G, and 43B. Here, the memory areas 43R, 43G, and 43B are respectively odd-numbered memory areas 4
3RO, 43GO, 43BO and even memory areas 43RE, 43GE, 43GE. However, in practice, the odd-numbered memory area and the even-numbered memory area are performed by processing on addresses in the memory area, and do not divide the memory area into two. Rewriting of data in each of the memory areas 43R, 43G, and 43B is performed for each frame of data of each color including two data of odd and even numbers.

When the data of each color written in the field memory 43 in this manner is read out to the color encoder 45 via the D / A converters 44R, 44G, and 44B, the data is read line by line from the odd memory area and the even memory area. Read alternately. As a result, as shown in FIG. 3 (d), the data of each color is simultaneously read out via the D / A converters 44R, 44G, and 44B to the color encoder 45. As shown in FIG. 7E, a composite video signal of the odd field and the even field is obtained, and this signal is displayed on the monitor 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 be maintained at a high level. Here, in the endoscope, even if the diameter of the outer diameter of the insertion portion is extremely small, a remarkable effect can be exhibited.
It is very advantageous.

[Effects of the Invention] As described above, according to the present invention, in the light-shielding period during which illumination is sequentially performed, one horizontal line and one even number of horizontal lines of the light receiving unit constituting the solid-state imaging device are used. A signal charge is read twice, such as a line, and written into a field memory as an odd line signal and an even line signal, respectively. From this field memory, an odd line signal and an even line signal are alternately read. Therefore, it is not necessary to mix two pixels in the vertical direction when acquiring an in-vivo image using a solid-state imaging device in which the number of pixels in the vertical direction of the storage unit is halved with respect to the light receiving unit. Resolution in the vertical direction, and the number of pixels in the vertical direction of the solid-state imaging device can be reduced to approximately half, so that a compact and compact The body imaging element can be used, and as a result, the outer diameter of the insertion portion of the endoscope can be reduced as a whole.

[Brief description of the drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is a circuit diagram of a signal processing device, and FIG. 2 is a CCD.
FIG. 3 (a) shows the irradiation period of the illumination light, FIG. 3 (b) shows the transfer timing from the light receiving section to the storage section, and FIG. 3 (c) shows the readout timing from the HCCD. 4D is a characteristic diagram showing the output signal from the memory, FIG. 4E is a characteristic diagram showing the output signal of the color encoder, and FIGS. 4 to 8 show the prior art. FIG. 5 is an overall configuration diagram of an endoscope device, FIG. 5 is a configuration explanatory diagram of a light source device, FIG. 6 is a configuration explanatory diagram of a color wheel, FIG. 7 is a circuit configuration diagram of a signal processing device, and FIG. FIG. 3B shows the output signal of the video processor at that time, FIG. 3C shows the output signal from the memory, and FIG. 3D shows the output signal of the color encoder. FIG. 6 is a characteristic diagram. 1: Insertion section, 2: Main body operation section, 3: Universal cord, 3a:
Electrical connector part, 3b: light source connector part, 10: light source lamp,
11: Light guide, 30: CCD, 40: CCD, 41: Video processor, 44: Field memory, 46: Color encoder.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification symbol FI H04N 9/07 H04N 9/07 A 11/08 11/08 11/24 (58) Fields surveyed (Int.Cl. ⁷ , DB Name) H04N 7/18 M H04N 9/07 A H04N 9/04 Z H04N 11/08 A61B 1/04 372 G02B 23/26 B G02B 23/26 D

Claims (1)

(57) [Claims] 1. A solid-state image pickup device comprising a storage unit having approximately half the number of pixels in a vertical direction with respect to a light-receiving unit, and an illuminating unit for sequentially illuminating a subject with a light-blocking period between R, G, and B,
A video processor, and exposes the light receiving section during each illumination period by the illumination means, reads out signal charges from the light receiving section via the storage section during the subsequent light shielding period, and converts the image signal with the deprocessor. In an endoscope which is generated and written in a field memory, an image signal from the field memory is read out, and an image of a subject is displayed on a monitor device, a frame interline is output from the solid-state imaging device in each light shielding period. The signal charges are read twice by the transfer, and one of them is read.
One time, the signal charges stored in the odd lines of the horizontal line of the light receiving section are read, and the other time, the signal signals of the even lines are read and written as the odd line signals and the even line signals in the field memory, respectively. A video signal processing method for an endoscope, wherein the odd line signal and the even line signal are alternately read from a memory for each line.