JP2000358170A - Video signal processor and endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce video signals having accurate DC components of small errors corresponding to each CCD even when the different noises are added to the optical black levels of the video signals by the different CCDs. SOLUTION: An OB correction part consists of a filter part 22 which inputs the luminance and line sequential color difference signals separated from each other via a selector switch 21 after branching these signals on the lines for correction of their optical black levels, a CCD detection circuit 23 which performs switching control of the switch 21 by means of a CCD detection signal, a clamp pulse generation circuit 24 which generates a clamp pulse for an optical black period of a video signal, an averaging circuit 25 which extracts the optical black level of the video signal by the clamp pulse via the part 22 and averages the extracted optical black signals to output a correction potential and a subtracter 26 which subtracts the correction potential from the video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing device and an endoscope system, and more particularly to a video signal processing device and an endoscope system having a characteristic of a signal level correcting portion of an optical black section.

[0002]

2. Description of the Related Art In recent years, endoscope apparatuses have been widely used for diagnosis and medical treatment in the medical field. Above all, a solid-state image sensor (hereinafter abbreviated as CCD) is provided at the tip of the elongated insertion portion.
The electronic endoscope provided with is more advantageous than a conventional fiberscope in terms of resolution, simplicity of image recording and image processing, and the like. In the electronic endoscope, information of a subject is photoelectrically converted by using a CCD, and an observation image is obtained by performing signal processing on an obtained electrical signal.

In order to constitute a single-chip color image pickup apparatus using one CCD, it is necessary to provide a color separation filter in which filters of different color components are arranged in a mosaic or the like on the image pickup surface of the CCD. .

As color separation filters, a primary color system using a combination of three primary colors of red (R), green (G) and blue (B) and a complementary color system using a combination of complementary colors of magenta, cyan and yellow However, the information of the subject is optically color-separated by the color separation filter, converted into electric charge by the photoelectric conversion element of the light receiving unit, and two-line simultaneous reading is performed to simultaneously read two vertically adjacent pixels. Obtained as an imaging signal.

In a conventional video signal clamping circuit of an electronic endoscope in a video signal processing circuit of a CCD having a color separation filter, a video signal converted into a digital signal by an A / D converter 101 is used as shown in FIG. Branch to register 102
The difference between the optical black level stored in the register 102 and the prescribed optical black level is detected by the subtraction circuit 103, and the obtained error and the correction potential before a predetermined period are added by the addition circuit 104. A new correction potential is stored in the register 105, the new correction potential stored in the register 105 is converted into an analog value by the D / A converter 106, and the differential amplifier 107
And the correction is performed with a new correction potential by feeding back to the analog input video signal.
This was performed by a timing signal from.

However, in the above circuit configuration, correction can be made to follow the fluctuation of the signal input to the video signal clamping circuit. However, when noise is added to the optical black level of the video signal, the noise is reduced. Is recognized as the correction potential, so that accurate reproduction of the DC component is not performed, and the high-quality image required for the endoscope observation image cannot be obtained.

Therefore, for example, Japanese Patent Application Laid-Open No. 8-98057 proposes a conventional video signal clamp circuit for an electronic endoscope in which the above-mentioned disadvantages are improved. This Japanese Patent Laid-Open No. 8-9
In the video signal clamp circuit disclosed in Japanese Patent No. 8057, as shown in FIG. 11, an image pickup signal from a CCD is amplified by an amplifier 121 and a video signal is extracted by a sample and hold circuit 122.
The signal is output to one end of the capacitor 123. Capacitor 12
The other end (point A) of switch 3 is connected to switch 124 and A / D converter 12.
5 is connected.

Here, the switch 124 is turned on when a clamp pulse is generated from the clamp pulse generating circuit 126 during the horizontal blanking period.

The output of the A / D converter 125 branches and is connected to an error detection circuit 127. The output of the error detection circuit 127 is connected to a loop filter 128. The output of the loop filter 128 is a D / A converter. 129. The output of the D / A converter 129 is connected to the switch 124, and the point A is disconnected by opening and closing the switch 124.

In the video signal clamping circuit shown in FIG. 11, an optical black level extracting means is constituted by the capacitor 123 and the switch 124. The optical black level extracting means converts the optical black level of the video signal extracted by the optical black level extracting means into a digital signal. A /
Correction means for branching and inputting a digital video signal output from the D converter 125 and feeding back a correction potential for correcting the optical black level of the video signal to a potential to be originally fixed to the optical black level extraction means; Are provided, an error detection circuit 127 and a D / A converter 129 are provided, and a loop filter 128 for removing high-frequency noise is connected to the correction means, and correction is performed with a new correction potential.

According to this, the influence of the noise component included in the optical black level on the reproduction of the DC component can be reduced.

[0012]

The above-mentioned JP-A-8-98
In the case of the circuit disclosed in Japanese Patent Application Laid-Open No. 057, even if noise is added to the optical black level of the video signal, a video signal having an accurate DC component with a small error can be reproduced. Means that different types of CCDs are connected for each observation site, or various CCDs such as CCDs with different numbers of pixels even if the observation site is the same.
May be connected, and the frequency component of noise mixed into the optical black level is also CC
All types of CC that are different for each D and are connected
There is a problem that it is very difficult to accurately reproduce a DC component for D.

The present invention has been made in view of the above circumstances, and has an accurate DC component with little error corresponding to each CCD even when different noises are added to the optical black level of a video signal by different CCDs. An object of the present invention is to provide an optical black level correction circuit of an electronic endoscope that can reproduce a video signal.

[0014]

According to a first aspect of the present invention, there is provided a video signal processing apparatus for processing an image signal output from a solid-state image sensor for capturing an object image. A timing signal generating means for generating a timing signal synchronized with an optical black portion in the image signal, and an average value of signal levels of the optical black portion in the image signal based on the timing signal generated from the timing signal generating means. Average value calculating means for calculating, correcting means for correcting the signal level of the image signal based on the average value calculated by the average value calculating means, and display means displayed on the display means based on the image signal processed by the correcting means. Video signal generating means for generating a video signal.

In the video signal processing apparatus according to the present invention, the timing signal generating means generates a timing signal synchronized with an optical black portion in an image signal output from the solid-state image sensor, and the average value calculating means outputs the timing signal. The average value of the signal level of the optical black portion in the image signal is calculated based on the timing signal generated from the timing signal generating means, and the correction means calculates the average value of the image signal based on the average value calculated by the average value calculating means. By correcting the signal level, even if different noise is added to the optical black level of the video signal by different CCDs, it is possible to reproduce video signals with accurate DC components with little error corresponding to each CCD I do.

According to a second aspect of the present invention, there is provided a video signal processing apparatus comprising: a first solid-state imaging device for capturing a subject image; a second solid-state imaging device for capturing the subject image; and the first or second solid-state imaging device. And a timing signal generator for generating a timing signal synchronized with an optical black portion in an imaging signal output from the first or second solid-state imaging device connected to the connection portion. Means, average value calculating means for calculating an average value of the signal level of the optical black portion in the image signal based on the timing signal generated from the timing signal generating means, and average value calculated by the average value calculating means Correcting means for correcting the signal level of the image signal based on the image signal; and generating a video signal to be displayed on the display means based on the image signal processed by the correcting means. Configured by comprising a video signal generating means.

According to a second aspect of the present invention, the timing signal generating means is synchronized with an optical black portion in an image signal output from the first or second solid-state image sensor connected to the connection portion. A timing signal is generated, the average value calculation means calculates an average value of a signal level of an optical black portion in the imaging signal based on the timing signal generated from the timing signal generation means, and the correction means calculates the average value. By correcting the signal level of the imaging signal based on the average value calculated by the calculation means, even if different noises are added to the optical black level of the video signal by different CCDs, accurate DC with little error corresponding to each CCD is obtained. It is possible to reproduce a video signal having a component.

According to a third aspect of the present invention, there is provided a video signal processing apparatus comprising: a first endoscope having a first solid-state imaging device for capturing an image of a subject; and a second endoscope having a second solid-state imaging device for capturing the image of the subject. An endoscope, a connection portion to which the first or second endoscope is detachably connected, and a solid-state imaging device provided in the first or second endoscope connected to the connection portion A timing signal generating means for generating a timing signal synchronized with an optical black part in the image signal output from the image signal; and a signal level of the optical black part in the image signal based on the timing signal generated from the timing signal generating means. Average value calculation means for calculating an average value, correction means for correcting the signal level of the image signal based on the average value calculated by the average value calculation means, and imaging performed by the correction means Configured by comprising a video signal generating means for generating a video signal to be displayed on the display means based on the item.

According to a third aspect of the present invention, in the video signal processing apparatus, the timing signal generating means is provided in the image pickup signal output from the solid-state image pickup device provided in the first or second endoscope connected to the connection section. Generating a timing signal synchronized with the optical black portion, the average value calculating means calculates an average value of a signal level of the optical black portion in the imaging signal based on the timing signal generated from the timing signal generating means, Correction means corrects the signal level of the imaging signal based on the average value calculated by the average value calculation means, so that even if different noise is added to the optical black level of the video signal by different CCDs, it is possible to correspond to each CCD. It is possible to reproduce a video signal having an accurate DC component with few errors.

According to a fourth aspect of the present invention, there is provided an endoscope system comprising: a first endoscope having a first solid-state image pickup device for picking up a subject image;
A second endoscope having a second solid-state imaging device for imaging the subject image, a connection portion to which the first or second endoscope is detachably connected, and the first solid-state imaging device A first average value calculating unit that calculates an average value of the imaging signal output from the second solid-state imaging device; a second average value calculating unit that calculates an average value of the imaging signal output from the second solid-state imaging device; Identification means for identifying the first or second solid-state imaging device of the endoscope connected to the connection part, and solid-state imaging of the endoscope connected to the connection part based on the identification result of the identification means Selecting means for selecting the first or second average value calculating means corresponding to the element, timing signal generating means for generating a timing signal synchronized with an optical black portion in the image signal, and generating by the timing signal generating means Taimi Average value output means for calculating and outputting an average value of a signal level of an optical black portion in the image signal based on the first signal or the first or second average value calculation means selected by the selection means; Correction means for correcting the signal level of the imaging signal based on the average value output from the value output means, and video signal generation means for generating a video signal displayable on a display means based on the imaging signal corrected by the correction means And is provided.

In the endoscope system according to a fourth aspect, the first
Average value calculating means calculates an average value of the image signals output from the first solid-state image sensor, and the second average value calculating means calculates the average value of the image signals output from the second solid-state image sensor. Calculating a value, the identifying unit identifies the first or second solid-state imaging device of the endoscope connected to the connecting unit, and the selecting unit determines the connecting unit based on an identification result of the identifying unit. And selecting the first or second average value calculating means corresponding to the solid-state imaging device of the endoscope connected to the endoscope, and the timing signal generating means generates a timing signal synchronized with an optical black portion in the imaging signal The average value output unit outputs an optical signal in the image signal based on the timing signal generated by the timing signal generation unit and the first or second average value calculation unit selected by the selection unit. The average value of the signal level of the rack section is calculated and output, and the correcting means corrects the signal level of the image pickup signal based on the average value output from the average value output means, so that the video signal of the different CCD is Even if different noise is added to the optical black level,
It is possible to reproduce a video signal having an accurate DC component with a small error corresponding to each CCD.

[0022]

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

FIGS. 1 to 7 relate to a first embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope apparatus, and FIG. 2 is disposed on an imaging surface of a CCD in FIG. FIG. 3 is a configuration diagram showing a configuration of a color separation filter, FIG. 3 is an explanatory diagram for explaining an image pickup signal read from the CCD in FIG. 1, FIG. 4 is a block diagram showing a configuration of the video signal processing device in FIG. 1, and FIG. 5 is a block diagram showing the configuration of the OB correction unit, FIG. 6 is a block diagram showing the configuration of the filter of the filter unit in FIG. 5, and FIG.
FIG. 14 is a block diagram illustrating a configuration of a modified example of the OB correction unit of FIG.

As shown in FIG. 1, an electronic endoscope apparatus 1 according to the present embodiment has an electronic endoscope provided with a CCD 3 as a solid-state image pickup device at a distal end in an elongated insertion section 2 inserted into a lumen. A mirror 4, a light source device 5 for supplying illumination light to the electronic endoscope 4,
A video signal processing device 7 for processing an image pickup signal from the electronic endoscope 4 and displaying an endoscope image on a monitor 6, and illuminating light supplied from the light source device 5 is arranged in the electronic endoscope 4. The light is transmitted by the provided light guide 8, emitted from the tip of the insertion section 2, illuminates the subject, and an image of the subject is picked up by the CCD 3.

Here, the video signal processing device 7 can detachably connect a plurality of types of electronic endoscopes 4 having different types of CCDs 3 via a connector (not shown). Is output to the video signal processing device 7.

Since the electronic endoscope apparatus 1 constitutes a single-chip type color image pickup device using one CCD 3, a color separation filter in which filters of different color components are arranged in a mosaic or the like is provided on the image pickup surface of the CCD 3. As shown in FIG. 2, a complementary color separation filter using a combination of complementary colors of magenta, cyan, and yellow is arranged on the imaging surface of the CCD 3. Then, the information of the subject is optically color-separated by the color separation filter, converted into electric charges by the photoelectric conversion element of the light receiving section of the CCD 3, and obtained as an image pickup signal.

The CCD 3 performs two-line simultaneous readout for simultaneously reading out two pixels that are adjacent in the vertical direction, and the imaging signals in the permutation shown in FIG. 3 are transmitted to the video signal processing device 7.

As shown in FIG. 4, the video signal processing device 7 drives the CCD 3 and pre-processes the image signal.
A secondary video signal processing unit 11 for processing the signal pre-processed by the primary video signal processing unit 11 into a standard video signal and displaying an endoscopic image on the monitor 6 Have been.

The primary video signal processing unit 11 generates various timing pulses for driving the CCD 3 and
And a pre-amplifier 1 for performing desired gain adjustment on an image signal from the CCD 3
4, a CDS 15 for performing correlated double sampling of the imaging signal whose gain has been adjusted by the preamplifier 14,
An A / D converter 16 for converting the correlated double-sampled signal into a digital signal by the A / D converter 15;
Circuit 17 for separating the video signal converted into a digital signal into a luminance signal YH and a line-sequential color difference signal CR / CB
And the luminance signal YH and the line-sequential color difference signals CR / CB separated by the separation circuit 17 are subjected to black balance processing to correct the black level in the dark, and the secondary video signal processing unit 12
And an optical black correction unit (hereinafter, referred to as an OB correction unit) 18 which outputs the data to the OB correction unit.

The secondary video signal processing unit 12 converts the video signal from the primary video signal processing unit 11 into a desired RGB signal, performs white balance correction and gamma correction in the subsequent stage, and performs endoscope using a digital encoder or the like. Monitor 6 mirror image
Is displayed.

As shown in FIG. 5, the OB correction unit 18 branches the luminance signal and the line-sequential color difference signal separated by the separation circuit 17 into lines for optical black level correction, and inputs them via the selector switch 21 to digitally input the signals. A filter section 22 for reducing signal noise, a CCD detection circuit 23 for detecting the type of CCD based on the CCD detection signal and controlling switching of the selector switch 21, and a clamp pulse for generating a clamp pulse during an optical black period of a video signal A generating circuit 24, an averaging circuit 25 that extracts an optical black level of the video signal through the filter unit 22 by the clamp pulse, averages the extracted optical black signal, and outputs a correction potential;
Averaging circuit 2 from one of the video signals branched at the output terminal 7
And a subtractor 26 that subtracts the correction potential from the output signal 5 and outputs the result to the secondary video signal processing unit 12.

The input signals shown in FIG. 5 are separately constituted of the luminance signal YH and the line-sequential color difference signals CR / CB.

The filter section 22 includes a plurality of filters (first filter 22 (1) to third filter 22 (1) in the drawing).
(3)), and this filter 22 (i)
It is configured as shown in FIG. That is, a video signal input as a digital signal is delayed by one clock by a plurality of stages of delay circuits 31, and a predetermined coefficient K 1, K 2, K 3, K 4 is added to each output signal by a multiplier 32 and then added by an adder 33. And outputs the result to the averaging circuit 25. At this time, the optimum number of taps is selected for the filter 22 (i) according to the CCD3.

(Operation) The drive pulse generation circuit 13
Various timing pulses for driving D3 are generated.
After the desired gain adjustment is performed, correlated double sampling is performed by the CDS 15 to remove reset noise. The video signal after correlated double sampling is R / A
The analog-to-digital conversion is performed by the D converter 16, and thereafter, the digital signal is processed.

The video signal after analog / digital conversion is
The separating circuit 17 converts the luminance signal YH into a line-sequential color difference signal CR.
/ CB.

YH and CR / CB can be obtained by the following equations (see FIG. 3).

(1) Luminance signal YH of n lines YH = DATA (n) + DATA (n−1) = (Mg + Ye) + (G + Cy) = 2R + 3G + 2B (1) (2) Luminance signal YH YH = DATA of n + 1 line (N) + DATA (n-1) = (Mg + Ye) + (G + Cy) = 2R + 3G + 2B (2) (2) Line-sequential color difference signals CR / CB CR / CB of n lines = DATA (n) -DATA (n-1) ) = (Mg + Ye) − (G + Cy) = 2R−G (3) (2) Line sequential color difference signal CR / CB CR / CB of n + 1 line = DATA (n) −DATA (n−1) = (Mg + Cy) − (G + Ye) = 2B−G (4) As shown in the equations (3) to (4), the color difference signal CR / CB
Is a line-sequential signal in which different color components are switched for each line.

The luminance signal YH and the line-sequential color difference signals CR / CB are input to an OB correction unit 18 where black balance processing is performed to correct the black level in darkness. The line-sequential color difference signal CR / CB of the luminance signal YH subjected to black balance processing by the OB correction unit 18 is converted into a desired RGB signal by the secondary video signal processing unit 12, and white balance correction and gamma correction are performed in the subsequent stage. Is output to the monitor 6 by a digital encoder or the like.

In the OB correction unit 18, the luminance signal YH and the line-sequential color difference signal CR / CB separated by the separation circuit 17 are line-branched for optical black level correction, and the branched luminance signal YH and the line-sequential color difference signal CR / CB. / CB is C
The selector switch 21 operates according to the switching signal generated by the CD detection circuit 23, and is input to the filter unit 22. In the control of the selector switch 21, a filter 22 (i) of the filter unit 22 that matches the characteristics of the CCD is selected according to the type of the CCD according to the CCD detection signal.

In the filter 22 (i), the video signal input as a digital signal is delayed by one clock by a delay circuit 31, and each output signal is given a predetermined coefficient K 1, K
After performing 2, K3, and K4, the result is added by the adder 33 and output to the averaging circuit 25.

The averaging circuit 25 extracts the optical black level of the video signal by the clamp pulse generated from the clamp pulse generation circuit 24 during the optical black period of the video signal, and averages the extracted optical black signal. As a result, the correction potential corresponding to the optical black level of the digital video signal for correcting to the potential that should be originally fixed is subtracted from the subtractor 2.
6 is output.

The subtraction unit 16 subtracts the corrected potential value obtained as described above from one of the video signals branched at the output terminal of the separation circuit 17, so that the optical black level of the video signal should be originally fixed. Approach potential.

(Effects) As described above, in the present embodiment, the correction value of the optical black level reaches the ideal level by repeating the correction operation of the OB correction unit 18 during the clamp pulse period, thereby achieving high precision. Can be reproduced.

At this time, even if the video signal contains noise corresponding to the CCD, the optical black level is averaged without responding to steep noise by selecting a filter corresponding to the CCD. Therefore, even if the optical black level of the video signal approaches the ideal optical black level and different noises are added to the optical black level of the video signal by different CCDs, an image having an accurate DC component with little error corresponding to each CCD. The signal can be reproduced.

As shown in FIG. 7, the same effect can be obtained by directly inputting a luminance signal and a line-sequential color difference signal branched for optical black correction to the filter section 22. However, the filter unit 22 multiplies K1, K2, K3, and K4 as shown in FIG. 6 by switching coefficients according to the CCD 3, and adds their outputs. As the coefficient at this time, an optimum coefficient is selected from a plurality of coefficients stored in the LUT 41 according to the CCD 3.

(Second Embodiment) FIGS. 8 and 9 relate to a second embodiment of the present invention. FIG. 8 is a block diagram showing a configuration of an OB correction unit, and FIG. FIG.
FIG. 3 is a configuration diagram illustrating a configuration of a filter unit.

Since the second embodiment is almost the same as the first embodiment, only different points will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

(Construction) As shown in FIG. 8, the OB correction unit 18a according to the present embodiment includes a clamp pulse generation circuit 24 and an averaging circuit 25 which constitute the optical black extracting means according to the first embodiment. In contrast to the configuration provided in the subsequent stage of the section 22, the clamp pulse generating circuit 2 constituting the optical black extracting means in the preceding stage of the filter section 22
4 and a switch 51. Other configurations are the same as those of the first embodiment.

(Operation) In the OB correction section 18a, the luminance signal YH branched for optical black level correction
When the clamp pulse is generated from the clamp pulse generating circuit 24 during the horizontal blanking period, the switch 51 is closed and turned on for the line-sequential color difference signal CR / CB, and the optical black level of the video signal is extracted. The extracted optical black level signal is supplied to the filter unit 22 by the operation of the selector switch 21 in response to a switching signal generated by the CCD detection circuit 23. At this time, the filter unit 22 calculates the average value of the optical black level extracted by the clamp pulse generation circuit 24 and the switch 51. This filter unit 22
As a result, a correction potential for correcting the potential to be originally fixed is output to the subtractor 16.

The correction potential value obtained as described above is subtracted from one of the video signals branched at the output terminal of the separation circuit 5 by a subtractor 1.
By subtracting at 6, the optical black level of the video signal approaches the potential that should be fixed. Other operations are the same as those of the first embodiment.

(Effect) As described above, even if the OB correction unit 18a is constructed by providing the clamp pulse generation circuit 24 and the switch 51 constituting the optical black extracting means in the preceding stage of the filter unit 22, the first embodiment will be described. The same effect as described above can be obtained.

When the filter section 22 performs analog processing, a branching means for branching the video signal for optical black processing is provided at a stage preceding the A / D converter 16 shown in FIG. Just connect. In that case, the filter can be configured by, for example, an RC circuit as shown in FIG.

The OB correction in each of the above embodiments is performed by
The case of the simultaneous imaging method using a complementary color chip filter on the front of the CD is described, but it is also applicable to the simultaneous imaging method using a primary color chip filter and the sequential imaging method without a complementary color chip filter. Clearly, it is possible to do so.

[Supplementary note] (Supplementary note 1) An electronic endoscope apparatus having an insertion portion having a CCD at a distal end thereof and a video signal processing means for processing an electric signal of the CCD into a video signal is obtained from the CCD. Timing pulse generating means for generating a pulse indicating the position of the optical black portion included in the video signal to be obtained, averaging means for averaging the optical black level of the video signal specified by the timing pulse generating means, A filtering unit for removing high-frequency components at a stage preceding the averaging unit; and a DC level correction unit for correcting a DC level of the video signal using the average value obtained by the averaging unit. Endoscope device.

(Additional Item 2) The endoscope apparatus according to additional item 1, wherein the filtering means can switch its characteristics according to the type of the CCD to be connected.

[0056]

As described above, according to the video signal processing apparatus of the first aspect, the timing signal generating means generates the timing signal synchronized with the optical black portion in the image signal output from the solid-state image sensor. Average value calculating means calculates the average value of the signal level of the optical black portion in the image signal based on the timing signal generated from the timing signal generating means, and correcting means calculates the average value based on the average value calculated by the average value calculating means. Since the signal level of the imaging signal is corrected, even if different noises are added to the optical black level of the video signal by different CCDs, each CC
There is an effect that a video signal having an accurate DC component with a small error corresponding to D can be reproduced.

According to the video signal processing device of the second aspect, the timing signal generating means is synchronized with the optical black portion in the image signal output from the first or second solid-state image sensor connected to the connection portion. Generate a signal,
Average value calculating means calculates the average value of the signal level of the optical black portion in the image signal based on the timing signal generated from the timing signal generating means, and correcting means calculates the average value based on the average value calculated by the average value calculating means. Since the signal level of the imaging signal is corrected, even if different noises are added to the optical black level of the video signal by different CCDs, it is possible to reproduce a video signal having an accurate DC component with little error corresponding to each CCD. This has the effect.

According to the video signal processing device of the third aspect, the optical signal in the imaging signal output from the solid-state imaging device provided in the first or second endoscope connected to the connection portion by the timing signal generating means. A timing signal synchronized with the black portion is generated, and the average value calculating means calculates the average value of the signal level of the optical black portion in the imaging signal based on the timing signal generated from the timing signal generating means, and the correcting means calculates the average value. Since the signal level of the image pickup signal is corrected based on the average value calculated by the calculation means,
Even if different noises are added to the optical black level of the video signal due to D, it is possible to reproduce a video signal having an accurate DC component with little error corresponding to each CCD.

According to the endoscope system of the fourth aspect, the first
Average value calculating means calculates the average value of the imaging signal output from the first solid-state imaging device, and the second average value calculating means calculates the average value of the imaging signal output from the second solid-state imaging device The identification unit identifies the first or second solid-state imaging device of the endoscope connected to the connection unit, and the selection unit has the endoscope connected to the connection unit based on the identification result of the identification unit. The first or second average value calculation means corresponding to the solid-state imaging device is selected, the timing signal generation means generates a timing signal synchronized with the optical black portion in the imaging signal, and the average value output means outputs the timing signal generation means The average value of the signal level of the optical black portion in the image pickup signal is calculated and output based on the timing signal generated in step (1) and the first or second average value calculation unit selected by the selection unit. Since correcting the signal level of the image signal based on the average value output from the average value output means,
Even if different noises are added to the optical black level of the video signal by different CCDs, it is possible to reproduce a video signal having an accurate DC component with a small error corresponding to each CCD.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a color separation filter arranged on an imaging surface of the CCD in FIG. 1;

FIG. 3 is an explanatory diagram illustrating an imaging signal read from the CCD in FIG. 1;

FIG. 4 is a block diagram showing a configuration of the video signal processing device of FIG. 1;

FIG. 5 is a block diagram showing a configuration of an OB correction unit in FIG. 4;

FIG. 6 is a block diagram showing a configuration of a filter of a filter unit in FIG. 5;

FIG. 7 is a block diagram showing a configuration of a modification of the OB correction unit in FIG. 5;

FIG. 8 is a block diagram illustrating a configuration of an OB correction unit according to a second embodiment of the present invention.

FIG. 9 is a diagram illustrating a configuration of a filter unit of FIG. 8 when performing analog processing;

FIG. 10 is a configuration diagram showing a first configuration example of a conventional video signal clamp circuit.

FIG. 11 is a configuration diagram showing a second configuration example of a conventional video signal clamp circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope device 2 ... Insertion part 3 ... CCD 4 ... Electronic endoscope 5 ... Light source device 6 ... Monitor 7 ... Video signal processing device 8 ... Light guide 11 ... Primary video signal processing unit 12 ... Secondary video Signal processing unit 13 Drive pulse generation circuit 14 Preamplifier 15 CDS 16 A / D converter 17 Separation circuit 18 OB correction unit 21 Selector switch 22 Filter unit 22 (i) Filter 23 CCD detection circuit 24 clamp pulse generation circuit 25 averaging circuit 26 subtractor 31 delay circuit 32 multiplier 33 adder

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Claims (4)

[Claims] 1. A video signal processing apparatus for processing an image signal output from a solid-state image sensor that has picked up an object image, wherein a timing signal synchronized with an optical black portion in the image signal output from the solid-state image sensor is provided. A timing signal generating means for generating, an average value calculating means for calculating an average value of a signal level of an optical black portion in the imaging signal based on the timing signal generated from the timing signal generating means, and the average value calculating means Correction means for correcting the signal level of the imaging signal based on the average value calculated in the above, and video signal generation means for generating a video signal to be displayed on the display means based on the imaging signal processed by the correction means. A video signal processing device characterized in that: 2. A first solid-state imaging device for imaging a subject image, a second solid-state imaging device for imaging the subject image, and a connection in which the first or second solid-state imaging device is detachably connected. A timing signal generating means for generating a timing signal synchronized with an optical black part in an imaging signal output from the first or second solid-state imaging device connected to the connection part; and the timing signal generating means Average value calculating means for calculating an average value of a signal level of an optical black portion in the image signal based on a timing signal generated from the image signal; and a signal of the image signal based on the average value calculated by the average value calculating means. Correction means for correcting the level; and video signal generation means for generating a video signal to be displayed on the display means based on the image signal processed by the correction means. A video signal processing device comprising: 3. A first endoscope having a first solid-state imaging device for imaging a subject image; a second endoscope having a second solid-state imaging device for imaging the subject image; A connection unit to which the first or second endoscope is detachably connected; and an imaging signal output from a solid-state imaging device of the first or second endoscope connected to the connection unit. A timing signal generating means for generating a timing signal synchronized with the optical black portion; and an average value for calculating an average value of a signal level of the optical black portion in the imaging signal based on the timing signal generated from the timing signal generating means. Calculation means; correction means for correcting the signal level of the image signal based on the average value calculated by the average value calculation means; and display means based on the image signal processed by the correction means. A video signal generating means for generating the video signal shown. 4. A first endoscope having a first solid-state imaging device for imaging a subject image; a second endoscope having a second solid-state imaging device for imaging the subject image; A connection unit to which the first or second endoscope is detachably connected, a first average value calculation unit that calculates an average value of an imaging signal output from the first solid-state imaging device, Second average value calculating means for calculating an average value of an image signal output from the solid-state imaging device, and identifying the first or second solid-state imaging device included in the endoscope connected to the connection portion. An identification unit; a selection unit that selects a first or second average value calculation unit corresponding to a solid-state imaging device of an endoscope connected to the connection unit based on an identification result of the identification unit; Timing signal synchronized with optical black part in signal A timing signal generating unit, a timing signal generated by the timing signal generating unit, and a first or second average value calculating unit selected by the selecting unit. An average value output unit that calculates and outputs an average value of the signal level; a correction unit that corrects a signal level of the imaging signal based on the average value output from the average value output unit; An endoscope system comprising: a video signal generation unit that generates a video signal that can be displayed on a display unit based on an imaging signal.