JP2002369795A - Electronic endoscopic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce an optical image on the whole surface of a monitor screen with uniform brightness by correcting a brightness signal in electronic endoscopic equipment. SOLUTION: An image pickup sensor 14 is provided to the leading end of a scope 10 and the image pickup signal obtained from the image pickup sensor 14 is outputted to a processor 100. The processor 100 forms a video signal on the basis of the obtained image pickup signal. The processor 100 detects zooming operation and a focus matching state to automatically output an image of high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention obtains a video signal corresponding to a subject image from a distal end portion of a flexible tube of a scope, performs video signal processing by a processor, and reproduces the subject image based on the video signal by a monitor device. The present invention relates to an electronic endoscope device.

[0002]

2. Description of the Related Art In such an electronic endoscope apparatus,
A CCD image sensor is provided at the tip of the scope, and this CCD image sensor is combined with an objective lens system. A light guide composed of a bundle of optical fibers is inserted through the scope, and illumination light is supplied from the light source lamp in the processor connected to the base end of the scope to the distal end of the scope via the light guide. When the scope is inserted into the patient's body cavity, the front of the objective lens system is illuminated by illumination light emitted from the distal end face of the light guide, and an optical image is formed on the light receiving surface of the CCD image sensor, where electrical signals are generated. Is photoelectrically converted to CCD
An electric signal, that is, a video signal, obtained from the image sensor is sent to a video signal processing circuit of a processor, and a video signal is generated based on the video signal. Further, the video signal is output to a monitor device, where an optical image is reproduced on a monitor screen.

Recently, an electronic endoscope apparatus for magnifying and displaying an affected part for the purpose of early detection of a lesion, for example, an electronic endoscope having a variable focus lens for an objective lens system of a scope and having a zoom function and an autofocus function. Mirror devices are also contemplated.

Generally, when photographing a digestive organ or the like, an image having a high contrast such that the center is dark and the periphery is bright may be obtained. For this reason, the conversion range is set large in A / D conversion or D / A conversion performed when processing a video signal. However, when the conversion range of the A / D converter or the D / A converter is large, there is a disadvantage that the resolution is reduced and a so-called coarse image is formed.

[0005] In applications in which the affected part is magnified and displayed by zooming, this drawback is a major obstacle to early detection of a lesion.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to automatically obtain a high-precision image when performing zooming.

[0007]

According to the present invention, there is provided an electronic endoscope apparatus comprising: a scope having a solid-state image pickup device; a photographing optical system having a variable focus and magnification; an upper reference voltage and a lower reference voltage inputted from outside; A / D converter for sequentially converting an analog video signal obtained from a solid-state image sensor into a digital video signal, a memory for storing a digital video signal, and a digital video signal in the memory being converted to a predetermined standard. A digital-to-analog (D / A) converter for converting an analog video signal into an analog video signal; focus detection means for detecting a focus state of the photographing optical system; Reference voltage changing means for narrowing the conversion range by changing at least one of the reference voltages, and for matching the signal level of the analog video signal with the signal level of the analog video signal A processor and a level correcting means for bell correction, based on the analog video signals output by the processor, characterized in that it comprises a monitor device for reproducing the object image on the screen.

Further, a processor of the electronic endoscope apparatus according to the present invention is a processor to which a scope having a solid-state image pickup device and a photographing optical system having a variable focus and magnification is connected. An A / D converter for sequentially converting an analog video signal obtained from the solid-state imaging device into a digital video signal using a potential difference between the reference voltage and the lower reference voltage as a conversion range; a memory for storing the digital video signal; A D / A converter for converting a digital video signal into an analog video signal of a predetermined standard; a focus detection means for detecting a focus state of the photographing optical system; and an A / D converter when the focus state is detected Reference voltage changing means for narrowing the conversion range by changing at least one of the upper reference voltage and the lower reference voltage of the analog video signal; Characterized in that it comprises a level correcting means for correcting to match the signal level of the image signal.

[0009]

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

FIG. 1 is a block diagram showing an embodiment of an electronic endoscope apparatus according to the present invention. The electronic endoscope apparatus includes a scope 10 having a flexible tube, a processor 100 detachable from the scope 10, and a monitor device 200 connected to the processor 100. A light guide member 12 composed of an optical fiber bundle is provided on the scope 10.
The proximal end of the light guide member 12 is attached to the processor 1 when the scope 10 is mounted on the processor 100.
00 is optically connected to a light source 102. Thus, the illumination light from the light source 102 is
Is guided to the scope distal end portion 10a to illuminate a subject in front, for example, the internal organ X.

An image sensor 14 comprising a solid-state image sensor, for example, a CCD, is provided at the distal end portion 10a of the scope. The image sensor 14 includes an objective lens system 16 combined with the CCD. The scope 10 has a zooming function and an autofocus function. More specifically, the objective lens system 16 includes a plurality of lenses, and the movable lens included therein is driven by the zoom / focus control circuit 114 of the processor 100 to change the relative position in the optical axis direction, thereby changing the focus. Is changed and the image magnification is changed.

In the present embodiment, a simultaneous method is employed to reproduce a color image, and an optical image of a subject illuminated by white illumination light is formed on a light receiving surface of a CCD by an objective lens system 16. The optical object image formed on the CCD is photoelectrically converted into an analog video signal for one frame by the image sensor 14, and is sequentially read from the image sensor 14 by a drive / process circuit 22 built in the connector unit 20 of the scope 10. It is.

The analog video signal read from the image sensor 14 is processed by a drive / process circuit 22 built in the connector section 20 in accordance with the characteristics of the image sensor 14 and the optical characteristics of the scope 10, for example, a clamp process or the like. Sample hold processing, gamma correction processing, white balance correction processing, contour enhancement processing, amplification processing, and the like are performed, and the result is output to the video signal processing circuit 104 of the processor 100. A read-only memory (ROM) 26 provided in the connector section 20 stores information on optical characteristics unique to the scope 10. Since the scope 10 is composed of high-precision parts, even a small mechanical error greatly affects the optical characteristics of each scope 10. For this reason, the scope 10 has data so that the processor 100 does not need to perform an adjustment operation according to the optical characteristics of each scope 10 when the scope 10 is replaced.

The video signal processing circuit 10 of the processor 100
In 4, the analog video signal for one frame is converted into a digital signal and subjected to digital signal processing. The digital signal after the signal processing is further converted into an analog signal such as an NTSC composite video signal in which a luminance signal and a color difference signal are multiplexed. It is converted to a color video signal.

The analog color video signal is supplied to the processor 1
00 to the recording device 30 such as the monitor device 200 or VCR
Output to 0. The monitor device 200 reproduces a subject image on a screen based on the analog color video signal, and the recording device 300 records the analog color video signal as a still image or a moving image. A keyboard 400 is connected to the processor 100, and character information such as a patient name input from the keyboard 400 and a medical examination date and time obtained from a timer circuit (not shown) is transmitted to the system control circuit 1.
The signal is converted into a character pattern signal by 06 and output to the video signal processing circuit 104, where it is added to the component digital signal. Thus, the character information is displayed on the screen of the monitor device 200 together with the reproduced image of the optical subject image.

The system control circuit 106 is a microcomputer for controlling the entire operation of the processor 100. The system control circuit 106 includes a CPU, a ROM for storing programs and parameters for executing various routines, and a RAM for temporarily storing data and the like. Prepare.

The processor 100 is provided with a stop 112 for adjusting the amount of illumination light supplied from the light source 102 to the light guide member 12. The aperture of the aperture 112 is adjusted by an aperture adjustment circuit (not shown), whereby the light amount is adjusted. The processor 100 includes the video signal processing circuit 1
It has an automatic dimming function that calculates the average luminance level of the video signal for one frame output from the image signal 04 and adjusts the aperture to an appropriate value based on the average luminance level.

In the electronic endoscope apparatus according to the present embodiment,
A contrast method is adopted for autofocus.
When the signal amplitude of the specific frequency component is extracted from the video signal obtained from the image sensor 14, the signal amplitude for the same subject becomes maximum at the time of focusing, and decreases as the defocus increases. The contrast method utilizes this characteristic, in which the movable lens is moved by the zoom / focus control circuit 114, and the change amount of the amplitude of the video signal is detected by the focus detection circuit 108.
06 determines in-focus when the signal amplitude takes the maximum value based on the detection result.

The auto focus function and the automatic light control function are set or canceled by a panel switch 110 provided on the surface of the processor 100.

FIG. 2 is a block diagram showing details of the video signal processing circuit 104. The analog video signal is amplified by the preamplifier 120 and converted to a digital video signal by the A / D converter 122. That is, the A / D converter 122
, The upper reference voltage Vt and the lower reference voltage Vb are applied from the reference voltage generation circuit 130, and the potential difference between them is A / D
The conversion range of the converter 122 is set, and a signal level obtained by equally dividing the band from the upper reference voltage Vt to the lower reference voltage Vb into, for example, 256 gradations (8 bits) is set. The amplitude of the input analog video signal is detected at regular intervals, it is determined which gray level corresponds to each amplitude, and the analog video signal is encoded into an 8-bit digital code. Thus, the data is stored in the memory 124.

The digital video signal for one frame read from the memory 124 is converted into an analog video signal by the D / A converter 126, and the signal level is adjusted by the amplifier 128.

The output of the A / D converter 122 is input to the focus detection circuit 108, where the in-focus state is detected.
The detection result is output to the system control circuit 106. When the system control circuit 106 determines that zooming is being performed and the camera is in focus, the value of the lower reference voltage Vb output from the reference voltage generation circuit 130 is set to narrow the conversion range of the A / D converter 122. Is set higher by a predetermined value α. At this time, since the signal level output from the A / D converter 122 is decreased by the rise α of the lower reference voltage Vb as a whole, the adder 134 at the subsequent stage of the D / A converter 126 adds only the voltage value α. To return the signal level. Specifically, a voltage having a constant value α is applied to the adder 134 from the setup level generating circuit 132 according to a command signal from the system control circuit 106.

As described above, when zooming is performed and the subject is in focus, the average luminance level of the image is assumed to be relatively high, so that the lower reference voltage Vb of the A / D converter 122 is Increase the value to narrow the conversion range. As a result, a high-definition image can be obtained. When the value of the lower reference voltage Vb is increased, the signal level is reduced by the increased value α.
The level is returned by the adder 134, so that the video signal can be output at the same signal level as when the video signal is not zoomed.

FIG. 3 is a flowchart showing a video signal processing routine executed in the system control circuit 106 of the processor 100.

In step S102, the panel switch 10
At 0, it is determined whether the zoom function and the autofocus function are set, and whether or not zooming is instructed by the zoom dial 18 to display an enlarged image.
If the enlarged display is not set, the process proceeds to step S114, and the normal lower reference voltage V
In step S116, the video signal processing circuit 104 is driven and controlled so as to output the value of b (NORMAL) and output an image with standard accuracy in step S116 without applying the voltage α from the setup level generating circuit 132.

If it is determined in step S102 that the enlarged display has been set, the zooming / focus control circuit 114 starts the zooming and autofocus operations in step S104, and the focus detection circuit 108 detects the in-focus state. In step S106, it is determined whether or not the camera is in focus. If not, the camera is in focus from step S102 to step S10.
6 is repeatedly executed, and if it is determined that the subject is in focus, the process proceeds to step S108. In step S108, the reference voltage generation circuit 130 outputs a value (AF) obtained by adding α to the lower reference voltage Vb, and the setup level generation circuit 132 applies the voltage α. Then, in step S112, the video signal processing circuit 104 is driven and controlled to output a high-definition image.

As described above, according to the electronic endoscope apparatus of the present embodiment, when zooming is performed and the subject is in focus, a high-precision image can be automatically output.

[0028]

As described above, an object of the electronic endoscope apparatus of the present invention is to automatically obtain a high-accuracy image when zooming is performed.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an electronic endoscope system to which an electronic endoscope device according to the present invention is applied.

FIG. 2 is a block diagram illustrating details of a video signal processing circuit illustrated in FIG. 1;

FIG. 3 is a flowchart showing a video signal processing routine executed in a system control circuit of the processor.

[Explanation of symbols]

 Reference Signs List 10 scope 14 imaging sensor 100 processor 200 monitoring device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 7/18 H04N 7/18 MF term (Reference) 2H040 GA02 GA06 GA11 4C061 AA00 BB02 CC06 DD03 HH51 JJ17 LL02 NN01 NN05 PP12 PP13 RR06 SS11 TT01 TT12 WW03 WW08 YY02 YY12 5C022 AA09 AB22 AB66 AC31 5C024 BX02 CX37 CY50 EX54 HX18 HX24 5C054 AA01 CC02 CC07 CD03 CG02 CH02 EA01 EA05 EB05 ED03 FF03 FC12

Claims (2)

[Claims] 1. A scope having a solid-state imaging device, a photographing optical system having a variable focus and magnification, and a potential difference between an upper reference voltage and a lower reference voltage input from outside as a conversion range. An A / D converter for sequentially converting an analog video signal into a digital video signal, a memory for storing the digital video signal, and a D / A converter for converting the digital video signal in the memory into an analog video signal of a predetermined standard Focus detection means for detecting a focus state of the photographing optical system, and conversion by changing at least one of an upper reference voltage and a lower reference voltage of the A / D converter when the focus state is detected. A reference voltage changing means for narrowing the range; and a level correcting means for level correcting the signal level of the analog video signal so as to match the signal level of the analog video signal. A processor and a correction means, wherein on the basis of the analog video signal output by the processor, the electronic endoscope apparatus, characterized in that it comprises a monitor device for reproducing the object image on the screen. 2. A processor of an electronic endoscope apparatus to which a scope having a solid-state image pickup device and a photographing optical system having a variable focus and magnification is connected, comprising an upper reference voltage and a lower reference voltage inputted from outside. A / D which converts an analog video signal obtained from the solid-state imaging device into a digital video signal sequentially,
A D converter, a memory for storing the digital video signal, a D / A converter for converting the digital video signal in the memory to an analog video signal of a predetermined standard, and a D / A converter for detecting a focus state of the photographing optical system. Focus detection means; reference voltage changing means for changing at least one of an upper reference voltage and a lower reference voltage of the A / D converter when a focus state is detected, thereby narrowing a conversion range; A processor for the electronic endoscope apparatus, comprising: level correction means for correcting the signal level of the signal to match the signal level of the analog video signal.