JP2534996B2 - Electronic endoscopic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic endoscope apparatus that increases the amount of illumination light and performs frame sequential illumination.

[Prior Art] In recent years, an electronic endoscope device has been realized in which an electronic image pickup unit is formed using a solid-state image pickup device in an endoscope and a subject image can be displayed on a display device such as a cathode ray tube. Has been done.

In the electronic endoscope apparatus using the solid-state image pickup device, it is easier to record an image as compared with a device that forms an optical image on an image guide fiber, and with the progress of high integration technology, It has the advantage that it can be made smaller and smaller.

Examples of the above-mentioned electronic endoscope apparatus include those disclosed in Japanese Patent Laid-Open No. 61-90636 and the conventional example shown in FIG. 12, which have the following configurations.

The electronic endoscope apparatus 1 includes an electronic endoscope 2 incorporating an image pickup means, a light source unit 3 for supplying illumination light to the electronic endoscope 2, and a signal picked up by the electronic endoscope 2. The signal processing unit 4 converts the video signal to be displayed on the display device.

The electronic endoscope 2 is formed with an elongated insertion portion 5 so that it can be easily inserted into a body cavity, and an objective lens 6 and a solid-state image pickup element 7 are arranged on the distal end side of the insertion portion 5 to incorporate an image pickup means. Has been.

Further, a ride guide 8 for transmitting irradiation light is inserted into the insertion portion 5, transmits the illumination light supplied from the light source portion 3 and is emitted from the tip end surface, and the emitted illumination light is distributed. It is expanded by the lens 9 to illuminate the subject 11 side.

The light source unit 3 that supplies illumination light to the end face of the light guide 8 on the hand side includes a light source lamp 12, and a lens 13 that condenses and illuminates the illumination light of the light source lamp 12 onto the end face of the light guide 8.
The rotary filter 14 is provided in the optical path between the lens 13 and the end surface of the light guide 8, and the motor 15 that drives the rotary filter 14 to rotate.

The rotary filter 14 is light in each wavelength band of red, green and blue,
That is, each of the red, green, and blue transmission filters 14R, 14G, and 14B that transmit R, G, and B respectively are formed in a fan shape, and by rotating the rotary filter 14, each of these R, G, and B three primary colors It is arranged to illuminate in frame order with light. This rotation filter
The rotation servo circuit 17 controls the rotation of the motor 15 that rotates the motor 14. With this rotation servo circuit 17, the motor
The rotation of 15 is synchronized with the frame frequency of the video signal.

The subject 11 illuminated by the above R, G, and B lights in a frame-sequential manner is imaged by the objective lens 6 on the imaging surface of the solid-state image sensor 7 such as a CCD, and the CCD driver (when the solid-state image sensor 7 is a CCD). 18
, A signal that has been photoelectrically converted by the application of the read clock signal is read. The clock signal and the signal from the rotary servo circuit 17 are input to the sync signal generator 19 to generate a sync signal for displaying the read signal.

The output signal of the solid-state imaging device 7 is amplified by the preamplifier 21 forming the signal processing unit 4, and is input to the reset noise removing circuit 23 via the isolation circuit 22 that protects the patient from electric shock and the like, and the reset noise is removed. Done. After that, unnecessary high frequencies such as CCD carriers are removed through the low-pass filter 24, vertical contour correction is performed by the vertical contour correction circuit 25, and further γ correction is performed by the γ correction circuit 26, that is, when displayed on the display tube. The non-linearity correction of the electric / optical conversion system is performed and the result is input to the A / D converter 27. This A / D converter 27 converts it into a digital signal and supports frame sequential irradiation
The read signals are written to 28R, 28G, and 28B for one frame. That is, for example, a signal read and imaged while being illuminated with red light through the red transmission filter 14R is written in the frame memory 28R. When one frame of image data is written in each frame memory 28R, 28G, 28B, these are read out at the same time,
The analog signal is converted by the D / A converter 29, unnecessary high frequencies are removed by the low-pass filter 31, and the analog high-frequency signal is input to the horizontal contour correction circuit 32. Above A / D converter 2
The conversion speed of 7 and writing / reading of data to / from each frame memory 28R, 28G, 28B are controlled by an output signal from the memory control circuit 33. The output signal of the memory control circuit 33 is generated in synchronization with the sync signal of the sync signal generator 19.

The signals subjected to the horizontal contour correction in the horizontal contour correction circuit 32 are respectively amplified by the output amplifier 34, and are output from the output end as R, G, B3 primary color signals having an output impedance of 75Ω, for example. is there. The composite sync signal of the sync signal generator 19 is also output from the sync signal output terminal through the output amplifier 35.

The R, G, B outputs through the output amplifiers 34 and the sync signal output through the output amplifier 35 can be input to an RGB compatible monitor to display a subject image in color.

By the way, the R, G, and B color signals corrected for each horizontal contour are
Input to Y matrix circuit 36, 0.59G + 0.3R + 0.11B
And the luminance signal Y is generated. Further, the color signal R and the luminance signal Y are subjected to RY calculation by the RY matrix circuit 37 to generate RY color difference signals. Similarly, the color signal B and the luminance signal Y are input to the BY matrix circuit 38, the BY operation is performed, and B is calculated.
A -Y color difference signal is generated.

The color difference signals RY and BY are encoders, respectively.
39 and 40, which have a phase difference of 90 °, are balanced-modulated by a subcarrier of 3.579545 MHz, and adder 41 performs vector combination to generate a chrominance signal C. Then, the chrominance signal C is multiplexed with the luminance signal Y by the mixed output amplifier 42, and the composite synchronizing signal and the color burst are added to generate an NTSC composite video signal, which is output from the NTSC output terminal. .

In the above-mentioned conventional example, it is necessary to reduce the outer diameter of the insertion portion 5 to be inserted into the body cavity to minimize the pain to the patient when inserting into the body cavity.
As a lighting means,
The R, G, B frame-sequential illumination system is often used. This is because in the case of the white illumination method, it is necessary to dispose a mosaic color filter in the solid-state image sensor for color imaging, and this mosaic color filter has a larger number of pixels than in the case of monochrome. It will be doubled. Therefore, when a mosaic filter that is not a frame sequential method is used, the number of pixels of the solid-state image pickup device must be increased in order to achieve the same resolution, which is not suitable for downsizing, and particularly downsizing is performed. Therefore, the field sequential illumination method is advantageous.

[Problems to be Solved by the Invention] However, in the above-mentioned frame sequential illumination method, white light from the light source lamp 12 such as a xenon lamp is transmitted through red, green, and blue transmission filters 14R, 14G, and 14B. Since illumination is performed only with light in each of the G and B wavelength ranges, there is a limit to improving the amount of illumination light, which is disadvantageous for displaying a color image with a high S / N.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electronic endoscope apparatus capable of increasing the illumination light amount even in a frame sequential illumination system.

[Means and Actions for Solving Problems] An electronic endoscope apparatus according to the present invention includes an image pickup means using a solid-state image pickup element, and a specific wavelength component for causing the image pickup means to output a luminance signal of a subject image. And a lighting means for sequentially generating a plurality of types of illumination light including the illumination light consisting of, the illumination light consisting of the specific wavelength component,
0.3, 0.59, 0.1 for red, green and blue wavelengths respectively
It is characterized in that the light has a transmission characteristic multiplied by a factor of 1.

EXAMPLES The present invention will be specifically described below with reference to the drawings.

1 to 3 relate to a first embodiment of the present invention, FIG. 1 shows an electronic endoscope apparatus of the first embodiment, and FIG. 2 shows a rotary filter used in the first embodiment. The transmission characteristics of each filter are shown in FIG. 3, and FIG.

The electronic endoscope apparatus 41 of the first embodiment has an electronic endoscope 42 incorporating an image pickup means, a light source unit 43 for supplying illumination light to the electronic endoscope 42, and an image taken by the electronic endoscope 42. And a signal processing unit 44 that converts the generated signal into a video signal that can be displayed on a display device.

In the electronic endoscope 42, an elongated insertion portion 45 is formed so that it can be easily inserted into a body cavity, and an objective lens 46 and a solid-state imaging device 47 are arranged on the distal end side of the insertion portion 45 to incorporate an imaging means. Has been.

Further, a light guide 48 for transmitting illumination light is inserted into the insertion portion 45, transmits the illumination light supplied from the light source portion 43, and is emitted from the tip surface, and the emitted illumination light is distributed. It is expanded by the lens 49 and illuminates the subject 51 side.

The light source unit 43 that supplies illumination light to the proximal end surface of the light guide 48 is a light source lamp 52, and a lens 53 that collects and illuminates the illumination light of the light source lamp 52 onto the end surface of the light guide 48.
A circuit filter 54 is provided in the optical path between the lens 53 and the end surface of the light guide 48, and a motor 55 that rotationally drives the rotary filter 54.

The light source lamp 52 emits white light such as a xenon lamp and has an emission spectrum distribution close to that of black body radiation.

The rotary filter 54 is composed of three fan-shaped color transmission filters 54R, 54Y, 54B.
As shown in Fig. 2, Y and 54B are red, luminance and blue wavelength ranges R and
It has a characteristic of transmitting Y and B respectively. still,
Here, the wavelength range of luminance means that which shows the color transmission characteristics of 0.59G + 0.3R + 0.11B with respect to the color transmission characteristics of blue, green and blue wavelength areas R, G and B respectively.

As shown in FIG. 3, the illumination light of the light source lamp 52 is a lens.
The light is condensed by 53 and irradiated toward the incident end surface of the light guide 48, but the rotary filter 54 rotated by the motor 55 is interposed in the optical path. That is, the rotation filter
By rotating 54, lens 53 and light guide
The subject 51 is sequentially (for example, R, Y, B, R) by the light in the wavelength range passed through the color transmission filter (blue transmission filter 54B in FIG. 3) to be interposed between the incident end face of 48. …so)
Illuminated.

The rotation speed of the motor 55 that rotates the rotary filter 54 is
The rotation servo circuit 57 controls to synchronize the phase with the frame frequency (for example, 29.97 MHz) of the synchronization signal generation circuit 58.

A subject 51 illuminated in a frame-sequential manner with each of the R, Y, and B lights is imaged on an image pickup surface of a solid-state image sensor 47 such as a CCD by an objective lens 46, and a CCD driver (when the solid-state image sensor 47 is a CCD). By applying the read clock signal by 59, the signal photoelectrically converted is read. The clock signal and rotation filter servo circuit 57 operates in synchronization with the signal supplied from the synchronization signal generator 58. Also, a composite sync signal for displaying the read signal is similarly supplied.

The output signal of the solid-state imaging device 47 is amplified by the preamplifier 61 forming the signal processing unit 44, is input to the reset noise removal circuit 63 via the isolation circuit 62 that protects the patient from electric shock, etc., to improve S / N. Therefore, reset noise and the like are removed. Then low pass filter 64
Unnecessary high frequencies such as CCD carriers are removed through the vertical contour correction circuit 65 to perform vertical contour correction of the subject image, and the γ correction circuit 66 further performs γ correction, that is, in the case of displaying on the display tube. The non-linearity (usually γ = 2.2) of the electrical / optical conversion system is corrected and input to the A / D converter 67. The A / D converter 67 converts the signals into digital signals, and the signals picked up under frame-sequential illumination are written in the frame memories 68R, 68Y, and 68G for one frame, respectively. That is, for example, a signal read from the solid-state image sensor 47 after being imaged under illumination of red light through the red transmission filter 54R is written in the frame memory 68R. Then, when one frame of image data is written in each of the frame memories 68R, 68Y, and 68B, these are read out at the same time, converted into analog signals by the D / A converter 69, respectively, and further by the low-pass filter 71, unnecessary high-frequency waves. Is removed, and the discontinuity of the signal generated at the time of D / A conversion is smoothed, and then input to the horizontal contour correction circuit 72. Conversion speed of the A / D converter 67 and each frame memory 68
Writing and reading of data to and from R, 68Y, 68B are controlled by output signals from the memory control circuit 73. The output signal of the memory control circuit 73 is generated in synchronization with the sync signal of the sync signal generator 58.

In the signals Y, R, and G for which horizontal contour correction has been performed by the horizontal contour correction circuit 72, the luminance signal Y and chrominance signal are input to the RY matrix circuit 83 and RY calculation is performed. A color difference signal R-Y is generated, the luminance signal Y and the color signal B are input to a BY matrix circuit 84, and B-
The color difference signal BY is generated by the calculation of Y.

The color difference signals RY and BY are encoders, respectively.
85 and 86 have a phase difference of 90 °, are balanced-modulated by a subcarrier of 3.579545 MHz, and adder 87 performs spectrum synthesis to generate a chrominance signal C. Then, the chrominance signal C is supplied to the luminance signal Y by the mixed output amplifier 88.
Then, the composite sync signal and the color burst are added to generate an NTSC composite video signal, which is output from the NTSC output end having an output impedance of 75Ω.

The horizontal contour corrected signals Y, R and G are input to the G matrix circuit 91 and Y-0.3R-0.11B is calculated to generate the color signal G. These color signals G, R, B are respectively amplified through the output amplifier 92, and the three primary color signals are output from the G, R, B output terminals. The composite sync signal of the sync signal generator 58 is also output from the sync signal output terminal via the output amplifier 93.

The G, R, B outputs through the output amplifiers 92 and the sync signal output through the output amplifier 35 can be input to an RGB compatible monitor to display a subject image in color. In addition, the normal NTSC may be generated by the composite video signal output from the NTSC output terminal.
It is also possible to display in color on the system monitor. The first
The right side of the dotted line portion in the figure shows the light source unit 43 and the signal processing unit 44.

According to the first embodiment, in the conventional example, the field sequential illumination is performed by R, G, B, while the field sequential illumination is performed by R, Y, B.
The image signal picked up by this frame sequential illumination can be displayed.

In the first embodiment, since the luminance filter 54Y is used, temporally identical R, G, B information can be obtained, so that the image blur (image shift) of the luminance signal is reduced and the resolution for the moving image is improved. it can. In addition, NTSC composite video signals can be obtained without complicated signal processing, and R, G, B
It is also possible to simplify the conversion processing from the conventional conversion to a PAL system signal. Further, in the case of a white light source such as a xenon lamp, the brightness filter can effectively increase the illumination light amount for the image pickup system by the solid-state image pickup device 47 such as a CCD, as compared with the case where the green transmission filter is used. , Images with high S / N can be obtained.

FIG. 4 shows the main part of the second embodiment of the present invention. In the second embodiment, as shown in FIG. 5, R, G: G, B: B,
A rotary filter 101 that passes light in each wavelength region of R, that is, includes R + G, G + B, and B + R transmission filters 101a, 101b, and 101c.
Is used instead of the rotary filter 54 of FIG.

The second embodiment using the rotary filter 101 is as follows.
In the first embodiment shown in FIG. 1, the A / D converter 6
The output of 7 is R + G memory 102a, G + B memory 102b, B +
It is written in the R memory 102c. Each memory 102a, 102b, 102c
Data is read out simultaneously, and the D / A converter 6
9. Color signals R + G, G + B, and B + R are respectively generated through the low-pass filter 71 and the horizontal contour correction circuit 72. These color signals are input to the adder 103 to be added and also multiplied by the double multiplier 104. After that, they are respectively input to the subtractor 105.

After the color signal of 2 (G + R + B) is obtained by the adder 103, the color signal of the other color signal 2 is inputted to each subtractor 105.
(R + G), 2 (G + B) and 2 (B + R) are respectively subtracted to obtain the three primary color signals 2B, 2R and 2G.

In the second embodiment, since it is possible to illuminate with an amount of transmitted light that is twice as large as that of normal illumination light, the amount of illumination light can be significantly increased, and an image with high S / N can be obtained. Also, the three primary colors R,
Since the illumination is performed with two colors as compared with the case of sequentially illuminating with G and B single colors, the color shift can be reduced.

FIG. 6 shows the main part of the third embodiment of the present invention. In the third embodiment, instead of the rotary filter 54 in the embodiment shown in FIG. 1, R, G, B; R, G; G, B as shown in FIG.
Of the R + G + B, R + G, and G + B transmission filters 111a, 111b, and 111c.
1 is used.

Then, in the case of using this rotary filter 111, the third
The electronic endoscope apparatus of the embodiment has substantially the same configuration until the horizontal contour correction in FIG. 1 (memory 68Y, 68R, 68B).
Will change. ), In this case, the color signal after horizontal contour correction is R +
G + B, R + G, G + B.

Then, the color signals R + G + B, R + G and G + B are input to the subtractors 112a, 112b and 112c, respectively. In addition, each signal R + G, G
+ B is added by the adder 113 to generate the color signal R + 2G + B, and the signal R + 2G + B is subtracted from the color signal R + G + B by the subtractor 112a to generate the color signal G.

Further, the color signal R + G + B is subtracted from the color signal R + G by the subtractor 112b to generate the color signal B. Further, the color signal R + G + B is subtracted from the color signal G + B by the subtractor 112c to generate the color signal R.

The third embodiment can increase the amount of illumination light more than the second embodiment. In this case, an infrared cut filter may be used instead of the filter 101a in some cases.

FIG. 8 shows the main part of the fourth embodiment of the present invention. In the fourth embodiment, the rotary filter 54 shown in FIG. 1 is replaced with 0.3R + 0.59G, 0.59G + 0.11B, 0.11B + as shown in FIG.
A rotary filter 121 including filters 121a, 121b, 121c exhibiting a transmission characteristic of 0.3R is used. In the fourth embodiment, the horizontal contour corrected signals are 0.3R + 0.59G, 0.59G + 0.11B, 0.1.
It becomes the signal represented by 1B + 0.3R, and these signals are adder
122 is added to generate a double luminance signal 2Y, and then 1
The luminance signal Y is generated by the / 2 coefficient unit 123. This luminance signal Y
Subtracts signal 0.3R + 0.59G by subtractor 124 to produce color signal 0.11B with a factor of 0.11. This color signal
0.11B is divided by 0.11 by the coefficient unit 125,
The color signal B is generated. The luminance signal Y is subtracted from the color signal B by the subtractor 126 to generate a color difference signal RY.
Also, the luminance signal Y is a signal of 0.59G + 0.11B by the subtractor 127.
Is subtracted to produce a color signal 0.3R with a factor of 0.3. This signal 0.3R is divided by 0.3 in the coefficient unit 128 to generate the color signal R, and the color signal R is subtracted from the luminance signal Y in the subtractor 129 to generate the color difference signal RY.

According to the fourth embodiment, the NTSC color difference signals RY and BY or the luminance signal Y can be obtained relatively easily, and an image with little color shift can be obtained.

FIG. 10 shows the main part of the fifth embodiment of the present invention. In the fifth embodiment, a rotary filter 131 using a luminance filter 131c is used instead of the 0.11B + 0.3R filter 121c in the rotary filter 121 in the fourth embodiment (see FIG. 11).

In the fifth embodiment, the horizontal contour corrected signal is the luminance signal Y and the signals 0.3R + 0.59G, 0.59G + 0.1 as shown in FIG.
1B, and the luminance signal Y is immediately obtained.

Further, the luminance signal Y is subtracted by a signal 0.3R + 0.59G by a subtractor 132 to obtain a color signal of 0.11B, and a color signal of 0.11B is obtained through a multiplier 133.
After dividing by 11 to obtain the color signal B, the luminance signal Y is subtracted by the subtractor 134 to obtain the color difference signal BY.

Also, the luminance signal Y is a signal of 0.59G + 0.11B in the subtractor 135.
Is subtracted to form a 0.3R color signal, and the coefficient unit 136
The color difference signal RY is obtained by dividing by 0.3.

According to the fifth embodiment, NTSC color difference signals RY,
The BY or the luminance signal Y can be obtained more easily than in the fourth embodiment. Also, an image with little color shift can be obtained.

Incidentally, for example, in the first embodiment, the transmission filter 54
As a Y transmission characteristic, a filter having a transmission characteristic of (0.3R + 0.59G + 0.11B) /0.59 may be used. By doing so, the amount of illumination light can be improved and the color shift can be reduced. This can be applied to other embodiments.

Incidentally, other embodiments can be formed by partially combining the above-mentioned embodiments.

[Effect of the Invention] As described above, according to the present invention, since at least one of the illumination lights that are illuminated in the field-sequential direction on the subject side is illuminated with mixed light of two or more colors, the illumination light amount can be improved.

[Brief description of drawings]

1 to 3 relate to a first embodiment of the present invention.
FIG. 1 is a block diagram showing the electronic endoscope apparatus of the first embodiment, FIG. 2 is a characteristic diagram showing transmission characteristics of a color transmission filter used for illuminating in a frame sequential manner, and FIG. FIG. 4 is an enlarged schematic explanatory view, FIG. 4 is a configuration diagram showing a main part of the second embodiment of the present invention, FIG. 5 is a front view showing a rotary filter used in the second embodiment, and FIG. Explanatory drawing which shows a part of signal processing part in 3rd Example of this invention, 7th
FIG. 8 is a front view showing a rotary filter used in the third embodiment, FIG. 8 is an explanatory view showing a part of a signal processing unit in the fourth embodiment of the present invention, and FIG. 9 is used in the fourth embodiment. FIG. 10 is a front view showing a rotary filter, FIG. 10 is an explanatory view showing a part of a signal processing unit in the fifth embodiment of the present invention, and FIG.
FIG. 12 is a front view showing a rotary filter used in Examples, and FIG. 12 is a configuration diagram showing a conventional electronic endoscope apparatus. 41 …… Electron endoscope device, 42 …… Electronic endoscope 43 …… Light source section, 44 …… Signal processing section 45 …… Insertion section, 47 …… Solid-state image sensor 48 …… Light guide, 52 …… Light source Lamp 54 …… Rotating filter 54R, 54B, 54Y …… Transparent filter

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Akira Osawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Yutaka Takahashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Tadashi Kato 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (56) Reference JP-A-61-82731 (JP, A) Sho 60-139383 (JP, U)

Claims (2)

(57) [Claims] 1. An image pickup means using a solid-state image pickup device, and an illumination means for sequentially generating a plurality of types of illumination light including illumination light having a specific wavelength component for causing the image pickup means to output a luminance signal of a subject image. An electronic endoscope apparatus characterized by comprising: 2. The illumination light composed of the specific wavelength component,
0.3, 0.59, 0.1 for red, green and blue wavelengths respectively
The electronic endoscope apparatus according to claim 1, wherein the light has a transmission characteristic multiplied by a factor of 1.