JP2956915B2 - Surface-sequential electronic endoscope device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame sequential type electronic endoscope apparatus, and more particularly, to an apparatus for processing a video signal obtained by a solid-state image pickup device in an electronic endoscope.

[0002]

2. Description of the Related Art In an electronic endoscope apparatus, an electronic endoscope (scope) is inserted into a body to be observed, such as a body cavity, and a CCD, which is a solid-state image pickup device provided at the tip of the electronic scope.
(Charge Coupled Device) or the like to image the inside of the object to be observed, thereby displaying an image of the inside of the object to be observed in color on a monitor.

FIG. 4 shows a schematic configuration of a conventional electronic endoscope device, in which an electronic endoscope 1 is detachably connected to an external device 2. In the figure, a CCD 4 is attached to an image forming position of an objective lens 3 disposed at the tip of an electronic endoscope 1, and a video signal obtained by the CCD 4 is supplied to an external device 2. A light guide (optical fiber) 5 is provided in the electronic endoscope 1, and irradiation light is output from the tip of the light guide 5 toward the body to be observed. On the other hand, in the external device 2, the light guide 5 is optically connected to the light guide 5, and a condensing lens 6, R (red), G (green), B (blue) color filters 7 in the field sequential method, and a light source 8 The output light from the light source 8 is converted by the color filter 7 into RGB color lights, and the RGB lights are sequentially radiated into the body to be observed via the light guide 5.

Also, a variable gain amplifier 10 for amplifying a video signal is provided in the external device 2, and the variable gain amplifier 10 amplifies the video signal with a different gain (amplification factor) for each color of RGB. . That is, in the electronic endoscope, the amplitude of each color signal in the video signal differs due to the spectral sensitivity characteristics of the CCD 4 and the spectral characteristics of the light guide 5, the color filter 7, and the like. The video signal is amplified with a different gain for each color. Further, a gamma correction circuit 11 is connected to the variable gain amplifier 10, and the gamma correction circuit 11 performs correction so that an electric output that is non-linear with respect to an optical input becomes linear. The output of the gamma correction circuit 11 is temporarily stored in the memory 13 via the A / D converter 12, and the video information in the memory 13 is connected to the external device 2 via the D / A converter 14. By being output to the monitor, a color image of the inside of the object to be observed is displayed on the monitor.

[0005]

However, in the above-mentioned electronic endoscope apparatus, the spectral sensitivity characteristics of the CCD 4 and the spectral characteristics of the light guide 5 are different between the individual electronic endoscopes 1, and various types of plural electronic endoscopes are required. When the electronic endoscope 1 is connected to the external device 2, it is necessary to correct the variation in the characteristics, and there is a problem that it is difficult to reproduce a faithful color. In particular, recently, various types of electronic endoscopes have been manufactured for various purposes, and many types of electronic endoscopes are frequently connected to one external device 2. It is difficult to connect a mirror to form a color image under favorable conditions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to eliminate variations in characteristics existing in individual electronic endoscopes, and to obtain a good color even when different electronic endoscopes are connected. An object of the present invention is to provide a field sequential electronic endoscope apparatus which can easily obtain reproducibility.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electronic endoscope having a solid-state imaging device having a built-in tip inserted into a body to be observed, and an electronic endoscope detachably attached to the endoscope. And an external device connected to the external device.
A light source unit having a color filter for sequentially outputting light of different colors, and a processor for performing an amplification process on a video signal for each color obtained by the solid-state imaging device and displaying an image on a monitor, In the field sequential type electronic endoscope device provided, the video signal is set to a different gain for each color signal in order to eliminate the variation in the characteristics regarding the color reproducibility of the electronic endoscope and obtain a predetermined color balance. A variable gain amplifier for amplifying the gain is provided on the electronic endoscope side.

[0008]

According to the above arrangement, the video signal is amplified by the electronic endoscope with the gain corrected in consideration of the characteristics such as the spectral sensitivity characteristic of the solid-state imaging device in the electronic endoscope. In addition, it is possible to supply a video signal in a state where the variation is corrected to an external device. Therefore, even when various electronic endoscopes are used, a video signal in a uniform processing state can be obtained, and correction processing in an external device can be simplified to improve color reproducibility.

[0009]

FIG. 1 shows the configuration of a frame sequential electronic endoscope apparatus according to a first embodiment. As shown in the drawing, the electronic endoscope apparatus is connected to an external device by an electronic endoscope (FIG. 1). (Electronic scope) is connected. There are various types of electronic endoscopes according to the purpose (part) of observation, and the electronic endoscope is detachable from an external device. In the electronic endoscope shown in the figure, a CCD 4 which is the above-described solid-state imaging device is provided, and a drive circuit 16 is connected to the CCD 4.
The drive of the CCD 4 is controlled by the drive circuit 16.

The present invention provides a variable gain amplifier (GCA-Gain Controlled Amplifier) 18 in such an electronic endoscope.
The variable gain amplifier 18 has a voltage source VG for setting the gain of a G (green) signal in a video signal,
(Red) A variable voltage source VR for setting the signal gain and B
(Blue) A variable voltage source VB for setting the signal gain is connected. The variable voltage sources VR and VB have R. ENE. (Enable) signal; Switches S1 and S2 operated by the ENE. Signal are connected, and in the embodiment, the gains of the other R and B signals are variably controlled based on the G signal. For example, as shown in FIG. 2 (a), the video signal is output from the CCD 4 as a signal whose amplitude decreases in the order of R, G, B. Amplification is performed with a gain controlled so as to increase in the order of G and B. The gain in this case is a value obtained by correcting variations due to the spectral sensitivity characteristics of the CCD 4 and the spectral characteristics of the light guide, which are peculiar to the electronic endoscope, thereby eliminating differences in characteristics of individual electronic endoscopes. As shown in FIG. 2B, a signal in which the amplitude of each color signal in the video signal is uniform can be obtained.

On the other hand, a processor 19 for processing a video signal is provided on the external device side. The processor 19 performs processing such as amplification and gamma correction shown in FIG. 4 and temporarily stores the video signal in a memory. Processing for outputting to the monitor will be performed. Note that the variable gain amplifier 18
It can be housed in a connector section or an operation section of the electronic endoscope.

The first embodiment has the above configuration, and its operation will be briefly described below. First, the electronic endoscope is used
When inserted into the RGB, the light guide (5)
The light is radiated sequentially into the object to be observed, whereby an image of the object to be observed can be captured by the CCD 4. The drive circuit 16 controls the driving of the CCD.
4 transmits the video signal shown in FIG. 2A to the variable gain amplifier 18. In the variable gain amplifier 18, the R.D. ENE. Signal, B. The switches S1 and S2 are switched by the ENE. Signal, whereby a control voltage for different gain control for each of the RGB color signals is supplied to the variable gain amplifier 18 from the voltage sources VG, VR and VB. As a result, the variable gain amplifier 18 amplifies with a different gain for each of the RGB color signals, and the variable gain amplifier 18 outputs a video signal whose amplitude has been corrected as shown in FIG. , And a video signal with white balance can be obtained.

As described above, in the present invention, the variable gain amplifier 18 is provided on the electronic endoscope side, and the variable gain amplifier 18 is provided.
It is possible to correct the characteristics of individual electronic endoscopes, so that even if various electronic endoscopes are used, the video signal output from the electronic endoscope can be in a color corrected state. Yes, without the need for complicated color correction on external devices,
A video signal with good color reproducibility can be formed.

FIG. 3 shows a configuration of a second embodiment for automatically controlling a variable voltage (control voltage) for gain control. This second embodiment corresponds to each color of RGB. Connected sample and hold circuits 20a, 20
b and 20c, and the sample and hold circuits 20a and 20c.
comparators 22a and 22 for comparing the outputs of b and 20c
b. Each of the sample-and-hold circuits 20a, 20b, and 20c respectively controls the R in the video signal.
Each color signal of GB is extracted and its average value (or peak value) is extracted.
Since the G signal is used as a reference in the embodiment, the output of the sample and hold circuit 20b for the G signal is supplied to the positive input terminals of the comparators 22a and 22b as a reference voltage. On the other hand, the output of the sample and hold circuit 20a for the R signal is output to the negative input terminal of the comparator 22a, and the output of the sample and hold circuit 20c for the B signal is output to the negative input terminal of the comparator 22b.

Therefore, according to the above configuration, the sample hold value (average value or peak value) of the R signal is input to the comparator 22a and compared with the sample hold value of the G signal, and the comparison voltage is used as the control voltage vr. Output to the variable gain amplifier 18. Similarly, the sample and hold value of the B signal is also input to the comparator 22b, compared with the sample and hold value of the G signal, and the comparison voltage is output to the variable gain amplifier 18 as the control voltage vb. As a result, the gain is controlled by the variable control voltages vr and vb so that the R signal and the B signal in the video signal become equal to the G signal (amplitude value).

In the above embodiment, the gain control of the variable gain amplifier 18 is such that a variable voltage is applied to the R and B signals with reference to the G signal.
The signal or the B signal can be used as a reference. In the embodiment, the gain of each color signal is set so as to obtain a white balance. However, this also emphasizes a specific color depending on conditions of an observation part, conditions of an external device, and the like. It is also possible to control the gain so that

[0017]

As described above, according to the present invention,
In a field sequential electronic endoscope apparatus that performs image processing on a video signal obtained by a solid-state imaging device, a variable gain amplifier that amplifies the video signal as a different gain for each color signal is provided on the electronic endoscope side. So, on the electronic endoscope side,
Spectral sensitivity characteristics of the solid-state imaging device, it is possible to correct variations unique to the electronic endoscope due to differences in the spectral characteristics of the light guide, etc. , even if multiple electronic endoscopes are connected to the external device,
It is possible to display an image of the inside of the observed body with good color reproducibility.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram illustrating a configuration of a frame sequential electronic endoscope apparatus according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram showing a processing state of a video signal in the circuit of FIG.

FIG. 3 is a circuit block diagram showing a configuration of a second embodiment.

FIG. 4 is a circuit block diagram showing a schematic configuration of a conventional electronic endoscope apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope, 2 ... External device, 4 ... CCD, 5 ... Light guide, 10, 18 ... Variable gain amplifier, 20a, 20b, 20c ... Sample hold, 22a, 22b ... Comparator, VG ... Voltage source, VR , VB ... variable voltage source, S2, S2 ... switch.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁶ , DB name) H04N 7/18 A61B 1/04 372

Claims (1)

(57) [Claims] 1. An electronic endoscope which inserts a distal end portion having a built-in solid-state imaging device into a body to be observed, and an external device which detachably connects the electronic endoscope. A light source unit having a color filter for sequentially outputting color light, and a processor for performing an amplification process on a video signal for each color obtained by the solid-state imaging device and displaying an image on a monitor. In the field sequential type electronic endoscope device, in order to eliminate the variation in the characteristics relating to the color reproducibility of the electronic endoscope and obtain a predetermined color balance, the video signal is set to a different gain for each color signal. A field-sequential electronic endoscope apparatus, wherein a variable gain amplifier for amplification is provided on the electronic endoscope side.