JP3538296B2 - Electronic endoscope system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a scope unit provided with a color image sensor and a signal processing device, and an electronic endoscope system using the scope unit.

[0002]

2. Description of the Related Art Conventionally, an image processor unit processes an output video signal of a scope unit provided with a color image pickup device, for example, a CCD (Charge Coupled Device) at the tip of an insertion portion, to generate a video signal, and converts the video signal to a CRT. An electronic endoscope system configured to display the information on a display device such as an electronic device is known.

In such an electronic endoscope system, a color CCD is arranged as an image pickup device in a scope unit, and
One that acquires a color video signal from D is known.

[0004] Generally, the scope unit is configured to be detachable from the image processor unit, and various scope units can be replaced and used depending on the application.

[0005] In order to attach various kinds of scope units to the image processor, it is necessary to ensure signal consistency between the scope unit and the image processor. That is, the color video signal sent from the scope unit to the image processor needs to be output as a signal that satisfies a predetermined specification. For this reason, a signal processing device is built in a scope unit that employs a color CCD, and a predetermined processing is performed on an output signal from the CCD to output a standardized color video signal to an image processor. It has become. Here, the predetermined processing is, for example, clipping processing, γ correction processing, synchronization signal addition processing, and the like. Generally, signals output from the scope unit are a luminance signal (Y) and two color difference signals (RY) and (BY). Where R
Is a red component video signal, and B is a blue component video signal.

Normally, an image processor is provided with a light source device for emitting light for irradiating an object to be observed, and a scope unit is provided with a light guide (for transmitting light emitted from the light source). An optical fiber bundle) is provided.

[0007] Light incident on the light guide from the light source passes through the light guide and irradiates the observation target, and the reflected light is imaged on the light receiving surface of the CCD via the imaging optical system. CC
The output signal of D is subjected to predetermined processing as described above,
It is input to the image processor as a standardized color video signal. After storing the color video signal received from the scope unit in the memory, the image processor stores the video signal of a predetermined format (for example, NTSC or PA).
L-compliant video signal) and output to a monitor device connected to the image processor.

To adjust the brightness of the screen displayed on the monitor device, the amount of light incident on the light guide from the light source device is adjusted (dimming is performed). For this reason, an aperture mechanism is provided in the light source device, and usually, automatic dimming using feedback control is performed so that the brightness of the observation target displayed on the screen is substantially constant.

Conventionally, a luminance signal output from a scope unit has been used for feedback control of automatic light control. That is, the intensity of the luminance signal is compared with a preset reference value, and the aperture mechanism is driven and controlled so that the luminance signal matches the reference value.

[0010]

However, since the luminance signal output from the scope unit is a signal that has been subjected to various processes as described above, the luminance signal output from the CCD has a dynamic range and characteristics. Is different from
The dimming state for the observation target (imaging target) is not accurately shown. In order to use this as a signal for dimming,
It is necessary to provide a signal correction circuit to correct the luminance signal, but such a correction circuit results in the complexity of the circuit of the image processor. Moreover, a signal whose dynamic range has been changed by the signal processing device on the scope unit side cannot be restored. For this reason, the feedback control system of automatic light control becomes non-linear, causing a delay in the response of the entire electronic endoscope system.

In view of the above circumstances, the present invention has a simple configuration and an electronic endoscope system capable of performing accurate automatic light control, and is configured to output a signal suitable for accurate automatic light control. Another object of the present invention is to provide a scope unit for an electronic endoscope system.

[0012]

According to the present invention, there is provided an electronic endoscope.
The mirror system has a scope unit and a light source device
In the electronic endoscope system, the scope unit
Is a line for transmitting illumination light emitted from the light source device.
Guide, a color image sensor, and the color image sensor.
Processing that satisfies the specified standard has been performed based on the output signal
A signal processing device for outputting a luminance signal and a color difference signal.
And the signal processing device performs processing that satisfies the predetermined standard.
In addition to the luminance and color difference signals
A process that satisfies the above-mentioned specified standard for dynamic light control is performed.
Is also configured to output the luminance signal before
The light source device emits light to be incident on the light guide.
And a process that satisfies the predetermined standard is performed.
The lamp emitted from the lamp based on the previous luminance signal
Control means for controlling the amount of light incident on the light guide;
(Claim 1).

The light source device complies with the predetermined standard.
Based on the luminance and chrominance signals that have been processed
A second signal processing device for generating and outputting a video signal
(Claim 2).

That is, the light source device is an independent light source device.
You may meet in a place.

Further , the light source device processes a video signal.
Light sources are built into image processors
May be.

[0016] The scope unit is a standardized video signal.
It has a built-in signal processor to output signals. Follow
And excellent compatibility.

The control means has a diaphragm device.
Before the drawing device is subjected to the processing that satisfies the predetermined standard.
Drive control based on the luminance signal of
It is possible to adopt a configuration (claim 3).

That is, by driving the diaphragm device based on a luminance signal faithfully reflecting the amount of light received by the image pickup device before the process satisfying the predetermined standard is performed, accurate and
Dimming with fast response becomes possible.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an electronic endoscope system 100 according to an embodiment of the present invention.

The electronic endoscope system 100 includes a scope unit 7, an image processor 21, and a monitor device 29. The scope unit 7 has an insertion section 4 formed of a flexible conduit. A CCD image sensor 5 (hereinafter abbreviated as a CCD) as a solid-state imaging device is provided at the tip of the insertion section 4 and an objective lens 6 is provided in front of the CCD 5. Are arranged. The CCD 5 is a so-called single-plate color CCD.
A color filter is provided on the light receiving surface. The optical image of the observation target (imaging body) is changed by the objective lens 6 to the color CCD 5.
Are formed on the light receiving surface. The light guide 1 made of an optical fiber bundle is inserted through the scope unit 7. One end (light emitting end) of the light guide 1 is disposed at an end (left end in the drawing) of the insertion section 4 and irradiates the observation target with light through the light distribution lens 2.

The scope unit 7 is detachably connected to the image processor 21 via the connection unit 8. A signal processing device 10 that performs a predetermined process on the video signal from the CCD 5 is built in the vicinity of the coupling section 8 of the scope unit 7. The other end of the light guide 1 reaches the inside of the image processor 21 via the coupling section 8 and the end face is
It is fixed at the position facing 1.

The lamp 13 is driven by the lamp power supply 16. The illumination light emitted from the lamp 13 is adjusted by the aperture mechanism 12 to adjust the amount of light.
1 impinges on the end face of the light guide 1. Light that has entered the light guide 1 passes through the light guide 1 and is inserted into the insertion portion 4.
Is emitted from the end surface on the distal end side of the lens, and is emitted toward the observation target via the irradiation lens 2.

The illumination light reflected by the observation object forms an image on the light receiving surface of the color CCD 5 by the objective lens 6. The CCD 5 transmits a color video signal corresponding to the optical image formed on the light receiving surface to the signal processing device 10. As will be described in detail later, the signal processing device 10 performs various kinds of signal processing, and sends a luminance signal (Y), a color difference signal (RY, BY) to the image processor 21, and a signal for automatic light control. And the YIRIS signal.

The above signal sent to the image processor 21 is input to the preprocessor 22. The two color difference signals (RY, B-
Y) and the luminance signal (Y) as they are in the A / D converter 1
8A, 18B, and 18C, each of which is converted into a digital signal and then synchronized with a synchronizing signal output from the timing generator 17 to the frame memory 19.
Is stored in The data stored in the memory 19 is subjected to a freeze process, an interpolation process, and the like, and then the D / A converter 2
The signals are converted into analog signals at 0A, 20B, and 20C, and output to the monitor device 29 as RGB video signals of a predetermined format by the signal processing circuit 28. Monitor device 2
9 displays a color image based on the received RGB video signal.

On the other hand, the YI input to the preprocessor 22
After the RIS signal is integrated by the integrator 22A, the difference amplifier 22B compares the RIS signal with a reference value Vref output from the system controller 27 and corresponding to the target light amount. Is input to the aperture drive circuit 22C.
The aperture drive circuit 22C drives and controls the aperture mechanism 12 based on the difference between the input integrator 22A and the reference Vref.

FIG. 2 is a block diagram showing a configuration of the signal processing device 10 built in the scope unit 7. As shown in FIG. The signal processing device 10 includes a matrix circuit 102, a signal processing circuit 103, and a timing generator 105.

The timing generator 105 generates a CCD driving pulse. The CCD 5 outputs the accumulated charges to the signal processing device 10 in synchronization with the CCD driving pulse. The video signal output from the CCD 5 is sampled by the matrix circuit 102 in synchronization with the timing pulse generated by the timing generator 105,
After being subjected to color separation processing, they are output as color difference signals RY, BY and a luminance signal Y. The intensity of the signal output from the matrix circuit 102 and the intensity of the video signal input to the matrix circuit have a linear relationship (proportional relationship). That is, the output signal of the matrix circuit 102 and C
There is a proportional relationship with the light receiving level of CD5.

However, since a portion where the voltage output with respect to the amount of light received by the CCD 5 is constant is used as a video signal, clipping processing is performed by the signal processing circuit 103 in the next stage to use the dynamic range narrowed. Therefore, for example, when the CCD 5 is exposed with high illuminance,
Although the output signal of the CD 5 itself is not saturated, the video information shows a state of being saturated at a predetermined level. For example, a triangular wave as shown in FIG.
, The Y signal output of the signal processing circuit 10 has a waveform saturated at a predetermined level as shown in FIG. 4, and the luminance information is partially lost.

As shown in FIG. 4, when a signal in which luminance information is partially lost is used as a signal for automatic dimming, the feedback function works well when dimming a part where the signal is saturated. It is known that the result is that the aperture operation of automatic light control is extremely slowed down as a result.

In addition to the above-described clipping, various signal processing such as γ correction and contour enhancement may be performed depending on the use of the image. For example, for the input waveform shown in FIG.
The waveform subjected to the γ correction is a waveform having a different amplification degree according to the luminance signal level as shown in FIG. FIG. 6 is an example of a signal waveform that has undergone both clipping and gamma correction.

As described above, when the luminance signal Y output from the signal processing circuit 103 is used as a signal for dimming, the gain of the feedback loop for automatic dimming changes according to the luminance signal level. Control becomes impossible. For example, when automatic light adjustment is performed in accordance with the γ-corrected signal, the automatic light adjustment itself has a γ characteristic.

Further, the response of the dimming is not constant, and when the dimming operation is slow, the case where the dimming operation is fast is mixed during the operation, and a stable dimming state cannot be obtained. The above problem can be dealt with by adding an inverse γ correction circuit inside the image processor 21, but the circuit configuration becomes complicated and the circuit scale becomes large, which leads to an increase in cost and size of the device. .

The reason why the signal processing circuit 103 needs to be provided on the scope unit 7 side is that, as described above, it is necessary to replace the scope unit coupled to the image processor 21 with various scope units depending on the application. Because there is. In other words, even when a scope unit having a different type of CCD or an imaging method is used, the scope unit outputs a signal satisfying a certain standard or specification, thereby maintaining compatibility between various scope units and an image processor. be able to.

As described above, the Y signal output from the matrix circuit 102 faithfully reflects the amount of light received by the CCD 5. For this reason, in the scope unit 7 of the present embodiment, the luminance signal Y output from the matrix circuit 102 and before being input to the signal processing circuit 103 is taken out and converted to another image as a YIRIS signal for automatic light control. The signal (the luminance signal Y and the color difference signals RY, BY output from the signal processing circuit) are output separately.
Since the YIRIS signal faithfully reflects the amount of light received by the CCD 5, by adjusting the amount of light based on the YIRIS signal,
The dimming error can be greatly reduced. And YIRI
Since the S signal is a signal that has not been subjected to clip processing, the range in which the feedback loop can be linearly controlled can be expanded, and therefore, high-speed automatic dimming can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an electronic endoscope system according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a signal processing device built in the scope unit.

FIG. 3 shows a signal processing device with a built-in scope unit.
5 is an example of a waveform input to a signal processing circuit.

FIG. 4 shows a signal processing device with a built-in scope unit.
4 is an example of an output waveform of the signal processing circuit when the waveform of FIG. 3 is input to the signal processing circuit.

FIG. 5 shows a signal processing device with a built-in scope unit.
4 is an example of an output waveform of the signal processing circuit when the waveform of FIG. 3 is input to the signal processing circuit.

FIG. 6 shows a signal processing device with a built-in scope unit.
4 is an example of an output waveform of the signal processing circuit when the waveform of FIG. 3 is input to the signal processing circuit.

[Explanation of symbols]

100 Electronic endoscope system 1 Light guide 2 Light distribution lens 4 Insertion part 5 color CCD 6 Objective lens 7 Scope unit 8 Joint 10 Signal processing device 11 Condenser lens 12 Aperture mechanism 13 lamp 16 Lamp power supply 17 Timing generator 18A, 18B, 18C A / D converter 19 Memory 20A, 20B, 20C D / A converter 22 Preprocessor 22A integrator 22B Difference amplifier 22C Aperture drive circuit 27 System Controller 28 signal processing circuit 29 Monitor device 102 Matrix circuit 103 signal processing circuit 105 Timing generator

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Shin Takada 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (56) References JP-A-5-236480 (JP, A) JP-A-3-153207 (JP, A) JP-A-62-155689 (JP, A) JP-A-9-37236 (JP, A) JP-A-3-109515 (JP, A) JP-A-5-168590 (JP) , A) JP-A-6-245899 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1/00-1/32

Claims (3)

(57) [Claims] 1. An electronic endoscope system having a scope unit and a light source device, wherein the scope unit includes a light guide for transmitting illumination light emitted from the light source device, a color image pickup device, and a color CCD. Meets specified standards based on output signal
A signal processing unit plus processing to output a luminance signal and color difference signals has been subjected to the signal processing device, in addition to the luminance signal and color difference signal processing has been performed to satisfy the predetermined standard, high-speed Auto dimming
The light source device is configured to also output a luminance signal before being subjected to a process that satisfies the predetermined standard, and a lamp that emits light to be incident on the light guide; An electronic endoscope system, comprising: control means for controlling the amount of light emitted from the lamp and incident on the light guide based on a luminance signal before a process satisfying a standard is performed. 2. The light source device further includes a second signal processing device that generates and outputs a video signal based on a luminance signal and a color difference signal that have been subjected to processing satisfying the predetermined standard. The electronic endoscope system according to claim 1, wherein: 3. The control device includes a diaphragm device, wherein the diaphragm device is driven and controlled based on a luminance signal before a process satisfying the predetermined standard is performed to adjust the light amount. The electronic endoscope system according to claim 1.