JPH07241270A - Light source voltage variable electronic endoscope device - Google Patents

Abstract

PURPOSE:To provide an image with superior color reproducibility by correcting the level difference of each signal generated due to the difference of color temperature of a light source. CONSTITUTION:A halogen lamp 12, a power source control part 14 which variably controls a supply voltage to the halogen lamp 12, a signal processing circuit 16 which performs the image processing of a video signal obtained by a CCD 11, a correction circuit 17 which corrects the video signal corresponding to the color temperature of the light source to which lighting control is applied by the power source control part 14, a comparator 20 which compares a luminance signal with a reference value and a microcomputer 22 which outputs a correction coefficient signal to the correction circuit 17 by the output of the comparator 20 are provided. In this way, the level difference in each of video signals generated due to the color temperature can be eliminated even when automatic light quantity control is performed by varying a light source voltage, and the image with superior color reproducibility can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly to video signal processing of a variable light source voltage type apparatus for changing the output itself of a light source for illuminating an observation region.

[0002]

2. Description of the Related Art A CCD (Charge Cou
2. Description of the Related Art An electronic endoscope device in which a pled device) is arranged at the tip of an electronic scope to observe the inside of a body cavity such as the digestive tract or the inside of thin tubes of various structures is well known. FIG. 3 shows a schematic configuration of a conventional electronic endoscope apparatus, and the light guide 1 and CCD 2 in the figure are arranged in an electronic scope. A lamp (halogen lamp or xenon lamp) 4 is optically connected to the light guide 1 via a diaphragm member 3 arranged in the light source device, and automatic light amount control (ALC) is applied to the diaphragm member 3. The diaphragm drive circuit 5 is connected to the lamp 4
The power source 6 is connected to. On the other hand, a signal processing circuit 7 for performing gamma correction, white balance and the like on the video signal is connected to the CCD 2 and a luminance signal is supplied from the signal processing circuit 7 to the diaphragm drive circuit 5.

With the above arrangement, the illumination light of the lamp 4 passes through the light guide 1 and is irradiated from the tip of the electronic scope into the body under observation, whereby the image of the body under observation 8 is CCD.
Caught in 2. Then, the video signal obtained by the CCD 2 is supplied to the signal processing circuit 7, where after the predetermined signal processing is performed, the image of the observed object 8 is displayed on the monitor. The brightness signal obtained by the signal processing circuit 7 is supplied to the diaphragm drive circuit 5, and the diaphragm drive circuit 5 controls the aperture amount of the diaphragm member 3 so that the brightness signal becomes constant. Therefore, the amount of light supplied from the lamp 4 to the light guide 1 is adjusted by driving the diaphragm member 3, so that the image displayed on the monitor is maintained at a constant brightness.

[0004]

By the way, in the light quantity control of the electronic endoscope apparatus, the diaphragm driving circuit 5 is used for the diaphragm member 3.
Since it is driven by, there is a problem that the configuration becomes complicated. Therefore, it has been proposed that the output (supply voltage) of the lamp 4 itself is adjusted without using the diaphragm member 3 to control the amount of light with which the body to be observed is irradiated. However, when the supply voltage of the lamp 4 is changed, the color temperature of the lamp output is changed, and for example, R (red) and G obtained by the CCD 2 are obtained.
There is a problem that a difference occurs between the signal levels of (green) and B (blue).

That is, due to the optical characteristics of the CCD 2 and the optical system members, for example, the color temperature of a halogen lamp is 3200 ° K.
Then, the signal level increases in the order of B signal → G signal → R signal, but each signal level changes corresponding to the change of the color temperature of the light source. Therefore, in this case, the white balance of the video signal is lost and the color reproducibility of the image is deteriorated.

The present invention has been made in view of the above problems, and an object thereof is to correct a level difference of each signal caused by a difference in color temperature of a light source to obtain an image with good color reproducibility. An object is to provide a light source voltage variable electronic endoscope apparatus.

[0007]

In order to achieve the above object, the present invention provides an electronic endoscope apparatus for processing a video signal obtained by a solid-state image pickup device and displaying an image inside a body under observation on a monitor. A power supply control circuit for variably controlling a voltage supplied to a light source for illumination in order to adjust the brightness of an image, and a correction circuit for correcting a video signal in accordance with a color temperature of a light source whose lighting is controlled by the variable voltage. And are provided.

[0008]

According to the above construction, for example, when a correction coefficient corresponding to the light source voltage corresponding to the color temperature of the light source is stored and set, and when R, G and B video signals are formed, each of them is formed. The signal is gain controlled by the correction coefficient. Therefore, even if the output of the light source changes, the video signal is corrected according to the color temperature, and an image with good color reproducibility is displayed on the monitor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a light source voltage variable electronic endoscope apparatus according to an embodiment. In FIG. 1, a light guide 10 and a CCD 11 are arranged in an electronic scope, and a halogen lamp 12 in a light source device is optically connected to the light guide 10. A power supply controller 14 is connected to the halogen lamp 12, and the power supply controller 14 variably controls the voltage supplied to the halogen lamp 12. On the other hand, in the processor unit 15, a signal processing circuit 16 for inputting a video signal from the CCD 11 is provided, where signal processing such as gamma correction is performed. A signal correction circuit 17 for performing correction corresponding to color temperature, an output circuit 18 including an encoder, and the like are arranged in a subsequent stage of the signal processing circuit 16, and a comparator 20 for inputting a luminance signal obtained by the signal processing circuit 16 is arranged. To be done.

That is, in the comparator 20, the reference voltage Vref is applied to one input side from the reference voltage source 21, and the reference voltage Vref is compared with the luminance signal supplied to the other input side to obtain the luminance. The control voltage Vs is supplied to the power supply controller 14 so that the signal becomes constant. In addition, a microcomputer (M
PU) 22 is provided, and in this microcomputer 22,
A correction coefficient corresponding to the color temperature of the halogen lamp 12 is stored in the storage unit.

FIG. 2 shows the color temperature value (schematic correspondence) with respect to the voltage supplied to the halogen lamp 20. As shown in the drawing, for example, a rated value of 15 V for lighting with a DC voltage is used. For example, the supply voltage is 13V
When the temperature rises in the range of -18V, the color temperature also rises from about 3200 ° K to about 4000 ° K. Then, depending on this change in color temperature, for example, R (red), G
Since the levels of the green (green) and B (blue) video signals are different, the levels depend on the supply voltage corresponding to this color temperature, and in the embodiment, the control voltage Vs output from the comparator 20. The correction coefficient is stored in the microcomputer 22. A monitor 24 is connected to the output circuit 18.

The embodiment has the above construction, and its operation will be described below. First, the device operates, and the power control unit 14
When a predetermined voltage is applied to the halogen lamp 14, the halogen lamp 12 is turned on. The illumination light of the halogen lamp 12 is emitted from the tip of the electronic scope into the object to be observed through the light guide 13. Then,
The image of the observed object 8 is captured by the CCD 11, and the C
The video signal output from the CD 11 is a signal processing circuit 16
Is supplied to. In the signal processing circuit 16, the video signal is subjected to clamp processing, gamma correction, etc. to form a luminance signal, and at the same time, R, G, and B signals are formed.

The brightness signal obtained by the signal processing circuit 16 is also supplied to the comparator 20, which compares it with the reference voltage Vref. This comparison voltage controls the lamp voltage of the halogen lamp 12. Voltage V
It is output as s. For example, when the image is dark, the lamp voltage is increased by the negative control voltage Vs, and when the image is too bright, the lamp voltage is decreased by the positive control voltage Vs, which maintains the brightness of the image constant. To be done.

At the same time, the output of the comparator 20 is supplied to the microcomputer 22, and the microcomputer 22 supplies a correction coefficient signal corresponding to the control voltage Vs to the signal correction circuit 17. That is, in FIG. 2, conceptually, assuming that the supply voltage of the halogen lamp 12 is 13 V and the color temperature is 3200 ° K, the correction coefficient of the RGB signal corresponds to the control voltage Vs at this time. For example, R signal = 1.8, G signal = 1.4, and B signal = 1.
Further, the voltage of the halogen lamp 12 is 15 V and the color temperature is 3
If it is 500 ° K, the control voltage Vs at this time is
Corresponding to, the correction coefficient of the RGB signal is, for example, R signal =
It suffices if 1.5, G signal = 1.2, and B signal = 1.

Then, the signal correction circuit 17 executes gain control for each RGB signal by the above-mentioned correction coefficient signal, whereby the level difference caused by the difference in color temperature of the RGB signal is eliminated. The video signal output from the signal correction circuit 17 is output to the output circuit 1
8 is input to the monitor 24, and the monitor 24
Will display an image with good color reproducibility.

In the above embodiment, the signal processing circuit 16 uses R
The case of forming a GB video signal has been described, but even in the case of forming a color difference signal, similarly, a correction coefficient set in advance is given to each color difference signal to perform correction corresponding to the color temperature change of the light source. It can be carried out. Further, although the case where the light source is the halogen lamp 12 has been described above, the present invention can be similarly applied to the case where another light source such as a xenon lamp is used. Further, although the signal correction circuit 17 is arranged in front of the output circuit 18, it may be arranged at another suitable place in the signal processing circuit 16 or may be shared with other correction circuits. .

[0017]

As described above, according to the present invention,
A power supply control circuit that variably controls the voltage supplied to the light source for illumination to adjust the brightness of the image, and a correction circuit that corrects the video signal in accordance with the color temperature of the light source whose lighting is controlled by the variable voltage. Since it is provided, it is possible to correct the level difference of each video signal caused by the difference in color temperature of the light source. Therefore, even when the light source voltage is changed to perform the automatic light amount control, there is an advantage that an easy-to-see image with good color reproducibility can be displayed on the monitor.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a light source voltage variable electronic endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a graph diagram conceptually showing the relationship between the light source voltage and the color temperature in the example.

FIG. 3 is a block diagram showing a configuration of a conventional electronic endoscope apparatus.

[Explanation of symbols]

 1, 10 ... Light guide, 2, 11 ... CCD, 12 ... Halogen lamp, 14 ... Power supply control section, 16 ... Signal processing circuit, 17 ... Signal correction circuit, 20 ... Comparator, 22 ... Microcomputer.

Claims (1)

[Claims] 1. In an electronic endoscope apparatus for processing a video signal obtained by a solid-state image pickup device to display an image of an inside of an object to be observed on a monitor, an electronic light source for illumination is provided to adjust the brightness of the image. A light source voltage variable electronic endoscope apparatus provided with a power supply control circuit that variably controls a supply voltage and a correction circuit that corrects a video signal according to a color temperature of a light source whose lighting is controlled by the variable voltage.