JP2567847B2 - Imaging device for endoscope - Google Patents

Description

The present invention relates to a color balance adjustment system for an electronic endoscope or a television camera for an endoscope.

[Problems to be Solved by Prior Art and Invention]

Up to now, in a general household video camera, as shown in FIG. 14, a white cap 3 is attached in front of the lens 2 of the video camera 1 to adjust the color of the camera by performing white balance. Incidentally, 4 is an image pickup tube and 5 is a VTR.

However, in the conventional white balance adjustment of the electronic endoscope or the video camera for an endoscope, the color balance adjustment is not performed with the display monitor included, and thus there is a problem that the adjustment accuracy is insufficient.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an endoscope imaging apparatus that enables accurate color balance adjustment of a display monitor.

[Means and Actions for Solving Problems]

An image pickup apparatus for an endoscope according to the present invention includes an illumination unit that projects illumination light of an endoscope onto a reference object, and an image pickup unit that receives reflected light from the reference object via an objective lens of the endoscope. In an endoscope image pickup device in which a video signal output from the image pickup means is displayed on the display means via a signal processing means including a color balance adjusting means, the color of the image of the reference object displayed on the display means. A chromaticity sensor for measuring the balance, and controlling the color balance adjusting means in the signal processing means so that the color of the image of the reference object is displayed in the same color as the predetermined color on the display means by the measured value. It has a feature. That is, the color balance adjusting means including the monitor device is controlled so that the image displayed on the display means is displayed in the same color as that of the reference object, and for the sake of further accuracy, simply In addition to the visual adjustment, the chromaticity sensor is used to measure the chromaticity of the image appearing on the monitor device for adjustment.

〔Example〕

Hereinafter, the present invention will be described in detail based on the illustrated embodiments by assigning the same reference numerals to the same members as those in the conventional example.

FIG. 1 shows a reference example in which a reflector 10 having an integrating spherical surface 10a (reference object) is used instead of the white plate. The integrating sphere 10a is coated with white paint having a good diffusibility such as MgO. Then, the distal end portion of the endoscope 6 is arranged in the spherical surface 10a. By doing so, the illuminance of the integrating sphere 10a becomes constant regardless of the position of the integrating sphere 10a in proportion to the total amount of light emitted from the illumination optical system of the electronic endoscope 6 by the principle of the integrating sphere. The image 11 on the television monitor 9 becomes white with the same brightness and color tone on any part of the screen, and as a result, white balance is extremely easy to obtain. A white display 12 may be attached to the reflector 10, and the color adjustment device is configured by the reflector 10 alone or by the reflector 10 and the white display 12.

The white display 12 has a diffuser plate 14 (for example, a white acrylic plate) placed in front of the high color rendering fluorescent lamp 13 as shown in the internal structure of FIGS. 2 (a) and 2 (b). 14 colors and images
White balance can be obtained by comparing the 11 colors and turning the color adjusting knobs 15 and 16 of the camera control unit 8 so that the colors are the same.

In the white display 12, a filter 17 may be placed in front of the high color rendering fluorescent lamp 13 to change the color and adjust the illuminance. The color adjusting device may be integrated with the camera control unit 8. Alternatively, the color adjusting device may be integrated with the television monitor 9.

FIG. 3 shows the first embodiment, in which the reflector 10 having the integrating spherical surface 10a is replaced by a reflector 18 having a white conical surface 18a and a lid 18b. The conical surface 18a is inferior in uniformity of illuminance to a spherical surface, but has an advantage that it is easy to manufacture. Further, in this embodiment, a reduced image 19 of the electronic endoscopic image on the conical surface 18a is further displayed on a part of the screen of the television monitor 9, and the chromaticity sensor 20 receives the light to measure the chromaticity, If the chromaticity deviates from the reference value, the color adjustment circuit in the camera control unit 8 is automatically controlled to adjust to the reference chromaticity.

FIG. 4 shows the electronic endoscope 6 (line transfer type shown in FIG.
FIG. 5 is a timing chart for explaining the operation thereof, which shows the configuration of (using CCD). In FIG. 4, the objective lens 23 and the illumination lens 21 are arranged in parallel at the distal end portion 6a of the endoscope 6, and the line transfer type solid-state image pickup device 24 is installed behind the objective lens 23 to receive the received optical signal. The drive circuit 25 converts the image into a video signal V, and the video signal V is sent to the next stage circuit via the preamplifier 26. A light guide 22 such as an optical fiber bundle is arranged behind the illumination lens 21, and illumination light is emitted to the rear end face thereof with a rotary filter 27 interposed. Illumination light is emitted from a light source lamp 28 through a lens 29 onto a rotary filter 27 (Fig. 7), and the illumination light is alternately arranged on the filter 27 with an appropriate light shielding period.
The light is incident on the end face of the light guide 22 through the filter. The read pulse detector 3 is provided around the rotary filter 27.
0, the start pulse detector 31 is fixed, and the rotary filter 27
Is configured to rotate at a predetermined speed on the rotating shaft. The rotating shaft is connected to the motor 33 via the transmission system 32,
The motor drive unit 35 is controlled by a signal from the rotation detection unit 54 provided in the motor 33 to keep the rotation speed of the motor 33 constant. On the other hand, the video signal V (R, G, B signals) from the preamplifier 26 is further amplified by the amplifier 36 and then input to the multiplexer unit 38. Three switches SW1 multiplexer unit 38 corresponding to the input R, G, signal B, SW2, SW3 made, these switches are gate signal SG ₁ for each switch from the multiplexer gate signal generating section 39, SG ₂ , SG ₃ are sequentially switched at a predetermined frame cycle, and the video signal V is a variable gain amplifier 48, 49, 50 described later.
Are stored in the R, G, and B frame memories 40, 41, and 42, respectively, read out from these frame memories, overlapped, and displayed in color on the color television monitor 9. In the above, the read pulse detection unit 30 detects the end position of the R, G, B filters arranged in the rotational direction of the rotary filter 27, and the read gate signal generation unit 44 detects the detected pulse (read pulse ) The read gate signal Gr is created using Pr and the signal from the oscillator 43. The read gate signal Gr is a signal for reading the video signal accumulated in the solid-state image sensor 29 in a period corresponding to a period in which the R, G, B light is not irradiated, and is input to the AND circuit 45 together with the signal from the oscillator 43. A read clock signal CKr is generated to drive the driver circuit 25 to convert the charge stored in the solid-state image pickup device 24 into a video signal V for each of R, G, B, while the read gate signal Gr is used for the start pulse detector. It is input to the multiplexer gate signal generator 39 together with the detection pulse (start pulse) Ps from 31 (detects one rotation of the rotation filter 27) and creates the switch gate signals SG ₁ , SG ₂ and SG ₃ described above. Then, the multiplexer unit 38 is switched to input the video signal to each of the frame memories 40, 41, 42 via the variable gain amplifiers 48, 49, 50 for each of R, G, B.

In such a configuration, as shown in FIG. 5, one start pulse Ps is output each time the rotary filter 27 makes one rotation, and is sent to the multiplexer gate signal generator 39.
Further, every one rotation, three read pulses Pr corresponding to the R, G, B filters are output and sent to the read gate signal generator 44. The read gate signal generator 44 uses the signal from the oscillator 43 to create a read gate signal Gr having the same period as the read pulse Pr and having a width corresponding to the period in which the R, G, B light is not irradiated. The read clock signal CKr and the switch gate signals SG ₁ , SG ₂ , and SG ₃ are created based on the period of the read gate signal Gr to obtain R, G, and B signals required for color display. In the illustrated read gate signal Gr, the shaded portions are the video signal read periods of R, G, and B, respectively, and the low-level period before each shaded portion is the solid-state image sensor 2 by the irradiation of R, G, B light.
4 is a period in which R, G, B signal charges are accumulated. Therefore,
R, G, switch gate signal SG ₁ of B frame memory 40,41,42, SG _2, SG ₃ is adapted to be a gate signal corresponding to each R, G, the video signal read period B .

Further, the signal from the chromaticity sensor 20 enters the comparison circuit 46 with the reference signal, and if there is a deviation from the reference value after comparison, the signal enters the amplifier gain conversion signal generator 47 and the amplifier gain conversion signal generator 47. The gains of the variable gain amplifiers 48, 49 and 50 are changed according to the output of the above to amplify the R, G and B signals.

FIG. 6 is a diagram showing the details of the light guide 22, the rotary filter 27, the light source lamp 28, and the lens 29 in FIG. 4, and the light emitted from the light source lamp 28 substantially in parallel is a lens group.
After being condensed by 29a, it is collimated again by the lens group 29b and is further condensed by the lens group 29c through the rotary filter 27 on the incident end face of the light guide 22 to be incident on the light guide 22. The rotary filter 27 is mounted on the rotary shaft 51, and both sides of the rotary filter 27, that is, the lens group 29b.
And 29c, two diaphragms 52 are arranged.

Here, the rotary filter 27 is formed, for example, as shown in FIG. That is, the rotary filter 27 is provided on the same circumference so as to shield the solid-state image sensor 24 from light while the solid-state image sensor 24 of the endoscope 6 reads out image information (electric charge of each pixel) during its rotation. Three shaded areas 27a
(Angle b), and further, on the same circumference, blue,
It has transmission regions 27b, 27c, and 27d (hereinafter referred to as openings) that transmit green and red color light. The shape of the openings 27b, 27c, 27d may be a straight line in the circumferential boundary as shown by the solid line in FIG. 7, and the outer edge thereof as shown by the dotted line in FIG. Also, even if the inner edge extends in the light shielding area 27a and has an arc shape (for example, radius D / 2), the light flux passing through the rotary filter 27 has a circular shape with a diameter D as shown by a chain line 53. Therefore, it does not affect the reading of the solid-state image sensor, and the amount of light transmitted through the openings 27b, 27c, 27d can be increased. In this case, the shape of the diaphragm 52 may be a circle having substantially the same diameter as the light flux that is going to pass through the rotary filter 27, and the diaphragm 52 may be omitted.

In the second embodiment, the color balance adjustment is performed by feeding back the output of the amplifier gain conversion signal generator 47 to the variable gain amplifiers 48, 49 and 50 provided in the camera control unit 8. As a modified example, A color gain adjustment may be performed by separately providing a variable gain amplifier dedicated to the TV monitor.

That is, as shown in FIG. 8A, a color balance adjusting unit 80 provided separately from the camera control unit 8 is provided.
Is a variable gain amplifier 48 ', 49', 5 for R, G, B colors.
0'is provided so that the R, G, B outputs from the camera control unit 8 are supplied to the television monitor 9 through the variable gain amplifiers 48 ', 49', 50 ', respectively. And
The output of the amplifier gain conversion signal generator 47 is supplied to these variable gain amplifiers 48 ', 49', 50 'to control the gain for each color and adjust the color balance.

In this configuration, since the color balance adjusting hand function including the marking color of the TV monitor 9 is provided separately from the camera control unit 8, the conventional camera control unit having no such color balance adjusting function is used as it is, There is an advantage that a reproduced image having an excellent color tone can be observed only by adding the color balance adjusting unit 80.

In addition, the color balance adjusting unit 80 is not a separate body,
It may be integrated into the TV monitor 9.

Further, as another modification of the first embodiment, a part is changed as shown in FIG. 8 (B) so that the chromaticity coordinates detected by the chromaticity sensor 20 are displayed on the television monitor 9. Good. The signal from the chromaticity sensor 20 is a chromaticity coordinate calculation circuit.
The chromaticity coordinates are calculated by 54 and converted into a video signal by the video signal conversion circuit 55, and the frame memories 40, 41, 42
And is displayed on the TV monitor 9. As in the first embodiment, the chromaticity of white can be set to the chromaticity desired by the user by changing the gains of the variable gain amplifiers 48, 49, 50 by the user.

FIG. 9 shows a second embodiment, in which 56 is a hemispherical cylindrical surface 56a formed by applying a white paint with good diffusivity to the inner surface of which the bottom surface is hemispherical and the side surface is cylindrical, and the same paint is applied to the inner surface. And a closed lid 56b, which replaces the reflector having an integrating sphere. Although the uniformity of the screen illuminance of the hemispherical cylindrical surface 56a is inferior to that of the integrating sphere, it is excellent in that it is easy to manufacture and repairs easily even if the paint is peeled off. In this example, the television camera 58 is attached to the fiberscope 57. Further, in this example, a white display circuit 59 for displaying white on a part of the screen of the television monitor 9 is provided inside the camera control unit 8, and the color balance of the circuit is adjusted by a color tone varying circuit 60. I am able to change it independently. Therefore, since the color of the TV monitor 9 varies from TV monitor to TV monitor, the color tone variable circuit 60 should be adjusted so that the chromaticity of the reference white portion 61 becomes the reference chromaticity. Then, the reference white portion 61 can be used as a reference white display. That is, the color tone of the fiberscope image of the camera control unit 8 is adjusted so that the reference white portion 61 and the fiberscope image 62 have the same color.
If the adjustment is performed with, the white balance including the color variation of the monitor 9 can be obtained. Incidentally, 63 is a light source.

FIG. 10 is a block diagram of the television camera 58 and the camera control unit 8 shown in FIG. 9. The signal of the endoscopic image formed on the CCD (solid-state image pickup device) 65 by the image pickup lens 64 is CCD65 → image generation. The circuit 66 → the color tone variable circuit 67 is transmitted, and the reference white display signal is transmitted to the white display circuit 59 → the color tone variable circuit 60. These are combined into one image signal by the synthesis circuit 68 and displayed as an image on the television monitor 9. To be done.

It should be noted that, like the reflector 10 of the reference example, the reflector 18 of the first embodiment, and the reflector 56 of the second embodiment, external light is prevented from entering from a portion other than the portion into which the distal end portion of the endoscope is inserted. If this is done, more accurate color adjustment can be performed. Further, if the reflectors 10, 18, and 56 are used without turning on the light source lamp, a completely dark object is displayed, so that the black level of the television monitor 9 can be adjusted. Since the chromaticity sensor 20 can also detect the illuminance, feedback can be automatically applied to adjust the black level of the monitor 9, and automatic black level adjustment is possible. In the examples so far, the color of the concave curved surface (reference object) of the reflector was white, but yellow,
Apply an object to skin color, light pink, etc., and use the reference color display or reference color part such as yellow, skin color, light pink instead of the reference white display 12 or reference white part 61 for toning. Is also good. In particular, since there are many reddish to yellowish colors in the body, it is possible to perform more accurate color matching than white and without discomfort.

FIG. 11 shows a third embodiment, which is a development of the first embodiment, in which the concave surface of the reflector 69 having two or more colors (three colors in this example) is photographed with an electronic scope. The chromaticity on the TV monitor 9 is detected for each color, the chromaticity is compared with the reference chromaticity, and the mean square of the difference (the difference between the two colors in the CIE uniform color space ΔE = {(ΔU ^* ) The color adjustment circuit of the camera control unit 8 is moved so that ² + (ΔV ^* ) ² + (ΔW ^* ) ² } ^1/2 is minimized.

FIG. 12 is a view of the reflector 69 viewed from the right side of FIG. 11, and a hemispherical surface 69a of the reflector 69 is coated with fan-shaped paints of three colors (for example, white, yellow, magenta or blue, yellow, red, etc.). It was painted. still,
The portion shown by the dotted line of the reflector 69 is a partition wall for preventing the entry of external light.

FIG. 13 is a block diagram of the third embodiment, and parts common to those in FIG. 4 are omitted. In this example, the color sensor 71 receives the monitor images 70 of three colors, and the chromaticity calculation circuits 72, 73 and 74 calculate chromaticity coordinate signals. Then, the comparison circuit 46 compares it with the reference chromaticity value, and if the deviation is a certain value or more, calculates how much the gains of the three colors R, G, B should be increased or decreased for each color, The signal is sent to the amplifier gain conversion signal generator 47 to be converted into the amplifier gain conversion signal, and the gains of the variable gain amplifiers 48, 49, 50 are changed. Such an operation is repeated until the difference between the actually measured value of the chromaticity of the television monitor 9 and the reference value becomes equal to or less than a certain value. By doing so, much more accurate color adjustment can be performed than in the first embodiment.
In FIG. 11, the reflector 69 may be provided with a conical surface instead of the hemispherical surface 69a as long as it is a concave surface.

Further, in the first embodiment and the present embodiment, the chromaticity on the screen of the monitor 9 is automatically brought close to the reference value, but the input signal entering the monitor 9 is measured and the chromaticity is set to a constant reference value. It may be automated to approach

The shape of the concave surface of the reflector in the above-mentioned reference example and each of the above-mentioned examples may be an ellipse, a paraboloid, an inner surface of a cylinder, etc., but a differentiable curved surface is superior because there is no discontinuous change in illuminance. ing. Further, instead of applying a paint having good diffusivity to the concave surface, fine concaves and convexes may be added to the concave surface by an appropriate surface treatment to substitute it.

〔The invention's effect〕

As described in each of the above embodiments, the endoscope image pickup apparatus according to the present invention enables accurate color adjustment of an image on a monitor.

[Brief description of drawings]

FIG. 1 is a diagram showing a reference example of an image pickup apparatus for an endoscope according to the present invention, FIGS. 2 (a) and 2 (b) are plan and front views of a white display used in the reference examples, respectively, and FIG. FIG. 4, FIG. 4 and FIG. 5 are block diagrams showing the configuration of the electronic endoscope shown in FIG. 3, respectively, and timing diagrams for explaining the operation thereof. FIG. 6 and FIG. FIG. 8 is a configuration diagram of the distal end portion of the electronic endoscope shown in FIG. 3 and a plan view of a filter, and FIGS. 8A and 8B are electronic diagrams used in a modification and another modification of the first embodiment, respectively. FIG. 9 is a block diagram of a main part of the endoscope, FIG. 9 is a diagram showing a second embodiment, FIG. 10 is a block diagram of a television camera used in the second embodiment, and FIG. 11 is a diagram showing a third embodiment.
12 and 13 are a front view of a reflector used in the third embodiment and a block diagram of a main part of an electronic endoscope, FIG. 14 is a view showing a conventional example, and FIG. 15 is another conventional example. FIG. 16 is a diagram showing an illuminance distribution on a white plate used in another conventional example. 6 ... Electronic endoscope, 8 ... Camera control unit, 9 ... TV monitor, 10 ... Reflector, 11 ... Image, 12 ... White display, 13 ... High color rendering fluorescent lamp, 14 ......
Diffuser, 15,16 …… Color adjustment knob, 17 …… Filter, 18
...... Reflector, 19 …… Reduced image, 20 …… Chromaticity sensor, 46…
… Comparison circuit with reference signal, 47 …… Amplifier gain conversion signal generator, 48,49,50 …… Variable gain amplifier, 54 …… Chromaticity coordinate calculation circuit, 55 …… Video signal conversion circuit, 56 …… Reflection Bowl, 59
…… White display circuit, 60 …… Color tone variable circuit, 61 …… Reference white part, 62 …… Fiberscope image, 69 …… Reflector, 70
…… Image by electronic endoscope, 71 …… Color sensor, 80…
… A color balance adjustment unit.

Claims (7)

(57) [Claims] 1. An illumination means for projecting illumination light of an endoscope onto a reference object, and an image pickup means for receiving reflected light from the reference object via an objective lens of the endoscope. In an endoscope imaging apparatus configured to display an output video signal on a display unit via a signal processing unit including a color balance adjusting unit, a color balance of an image of a reference object displayed on the display unit is adjusted. A chromaticity sensor for measuring is provided, and a color balance adjusting means in the signal processing means is provided so that the color of the image of the reference object is displayed in the same color as the predetermined color on the display means by the measurement value of the chromaticity sensor. An imaging device for an endoscope, which is controlled. 2. The image pickup apparatus for an endoscope according to claim 1, wherein the color of the reference object is white. 3. The image pickup apparatus for an endoscope according to claim 1, wherein the color of the reference object is a predetermined monochromatic color. 4. The image pickup apparatus for an endoscope according to claim 2, wherein a predetermined color is displayed on the display means. 5. The image pickup apparatus for an endoscope according to claim 1, wherein the reference object is composed of a plurality of colors. 6. The chromaticity coordinate of the image of the reference object is calculated based on the measured value, and the color balance adjusting means is controlled so as to minimize the difference from the chromaticity coordinate of a predetermined color. The imaging device for an endoscope according to claim 5, which is characterized. 7. The color balance of the image of the reference object displayed on the display means is measured by a chromaticity sensor, and the chromaticity coordinates of the image are displayed on the display means based on the measured values. The imaging device for an endoscope according to any one of claims (1), (5), and (6).