JP3813411B2 - Electronic endoscope device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus, and more particularly to an apparatus in which a light-emitting element for irradiating a body to be observed is disposed at an endoscope tip having an imaging element.
[0002]
[Prior art]
In many electronic endoscope apparatuses, light from an external light source device is guided to a distal end portion through a light guide and illuminates the light into a body to be observed, but recently, an LED (light emission) is applied to the endoscope distal end portion. A light source such as a diode is disposed and the light of the LED is used as illumination light (for example, Japanese Patent Publication No. 4-9526). As such a light source, for example, an LED for white light is used.
[0003]
[Problems to be solved by the invention]
Incidentally, in the white light LED, generally, as shown in FIG. 5, the emission spectrum is distorted, and there is a fact that accurate white light is not irradiated on the object to be observed. That is, FIG. 5 shows an example of the emission spectrum of a conventional LED, which has a characteristic in which the intensity near the wavelength of 500 nm is lowered. Even with such characteristics, the color cannot be accurately identified by the human eye, so if multiple colors are mixed at a constant luminance, the color appears white according to the principle of the additive color method.
[0004]
However, in an electronic endoscope, an object to be observed is picked up using a solid-state image pickup device such as a CCD (Charge Coupled Device), so that distortion of irradiation light characteristics adversely affects color reproducibility. Therefore, it is preferable to pick up an image using white light having uniform characteristics without distortion, and this makes it possible to reproduce and display the inside of the observation object with an accurate color.
[0005]
The present invention has been made in view of the above-described problems, and the purpose thereof is to irradiate white light having a distortion-free characteristic even when a light emitting element is arranged at the distal end portion of an endoscope. An object of the present invention is to provide an electronic endoscope apparatus capable of obtaining an image with good color reproducibility.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an electronic endoscope apparatus including a plurality of light emitting elements for irradiating light toward an object to be observed at an endoscope distal end portion. As the light emitting element, a white light emitting element for white light emission and a green light emitting element for green light emission are provided.
The invention according to claim 2 is characterized in that the white light emitting element or the green light emitting element is provided with an adjuster for adjusting the balance of light emission intensity between the light emitting elements.
[0007]
According to the above configuration, the green light of the green light emitting element compensates for the insufficient wavelength region of the light output from the white light emitting element, and the distortion of the emission spectrum of the white light emitting element is eliminated. Can do. At this time, for example, the output of the light emitting element for white light is slightly reduced with an adjuster such as a variable resistor, and the output of the green light emitting element is set to the full rating by adjusting the output of both elements, for example, the emission spectrum. Uniformity of characteristics can be ensured.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a light source and a lighting circuit of an electronic endoscope apparatus according to an embodiment, and FIGS. 2 and 3 show a configuration of a finger-mounted endoscope used as a rectoscope or the like of the example. It is shown. First, in FIG. 2, the finger-wearing endoscope 10 is arranged at the tip of a glove (index finger) 11, and has a structure in which a cover 13 is attached to the support portion 12. A lens 14, a CCD 15 as an image sensor, and a circuit board 16 on which the lens 15 is mounted are disposed. Then, the outer peripheral portion of the photographing lens 14, light-emitting diodes _D 1 to D ₈ is mounted as the light source, the light-emitting diodes _D 1 to D ₈ is connected to the circuit board 16.
[0009]
A cable 18 is connected to the circuit board 16, and the cable 18 is wired to a power supply unit on the main body side and a video signal processing unit. In addition, an air / water supply tube 19 for supplying air or water to the object to be observed is attached to the cover 13.
[0010]
According to such a finger wearing endoscope 10, for example, the endoscope 10 attached to the index finger 20 is inserted into the body to be observed, and light irradiation is performed by lighting control of the light emitting diodes D _{1 to} D ₈ at the distal end. As a result, it becomes possible to image and observe the inside of the observation object via the CCD 15.
[0011]
FIG. 3 shows an enlarged cross section of a portion where the light emitting diodes D _{1 to} D ₈ of the endoscope of FIG. 2 are cut in the radial direction. As shown in the drawing, the eight light emitting diodes D _{1 to} D ₈ are arranged at equal intervals around the photographing lens 14, and the six diodes D _{2 to} D ₄ and D _{6 to} D ₈ among them are arranged. for white light, the two diodes D ₁ and D ₅ and has a green light. The green light emitting diodes D ₁ and D ₅ are preferably arranged at opposite positions as in the above example, and the number of arrangement and the arrangement ratio of white light are arbitrary such as 5 to 5, It will be changed and set as appropriate.
[0012]
In FIG. 1, the white light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ described above include a first transistor Q ₁ for increasing operational stability, a second transistor Q ₂ having a current mirror configuration, and a second transistor Q ₂ . A constant current circuit including three transistors Q ₃ and a variable resistor VR ₁ is connected, and a battery 24 which is a voltage source generated by a DC / DC converter is connected to the constant current circuit. The variable resistor VR _{1 serving as a} regulator may be an electronic volume or the like.
[0013]
Similarly, the green light emitting diodes D ₁ and D ₅ have a constant current comprising a fourth transistor Q ₄ , a fifth transistor Q ₅ and a sixth transistor Q ₆ in a current mirror configuration, and a resistor R _2. A circuit is connected, and the electric power of the battery 24 is supplied by this constant current circuit. Incidentally, the resistor R ₂ can be a variable resistor or the like.
[0014]
1, the white light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ have a current amplification factor β of the _{first to} third transistors Q _{1 to} Q ₃ and a current Suppose that the base current of the second and third transistors Q ₂ and Q ₃ of the mirror is i _b , the current flowing through these transistors Q ₂ and Q ₃ is I _c , and the reference current of these transistors Q ₂ and Q ₃ is I _ref . I _c having the relationship of the following formula (1) is generated, and this current I _c flows as the current i of the light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ .
I _c = β · i _b = I _ref / (1 + 2 / β ² ) (1)
[0015]
Here, from the above equation (1), I _ref = β · i _b + (2 i _b / β), the voltage of the battery 24 is Vdd, and the collector-emitter of the _{first to} third transistors Q _{1 to} Q ₃ When the voltage (V _CE ) is 0.6 V and the resistance value of the variable resistor VR ₁ is r ₁ ,
I _ref = {(Vdd−0.6V−0.6V) / r ₁ } (2)
There is a relationship.
[0016]
Accordingly, the constant current i (= Ic) set by the resistance value r ₁ of the variable resistor VR ₁ is supplied to the light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ , and a constant forward voltage is given. As a result, the light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ for white light are turned on. On the other hand, in the light emitting diodes D ₁ and D ₅ for green light, the operations of the transistors Q _{4 to} Q ₆ and the resistor R ₂ are the same as described above, and a constant current set by the value r ₂ of the resistor R ₂ is supplied. Will light up.
[0017]
FIG. 4 shows an example of the emission spectrum of the light emitting diodes D _{1 to} D ₈ , and the white light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ have characteristics indicated by G 1 (solid line). The green light emitting diodes D ₁ and D ₅ have the characteristics indicated by G2 (chain line). As a result, a light emission vector indicated by the characteristic G3 (dotted line) is obtained, and white light having a color (wavelength) distribution characteristic from which distortion has been eliminated is output.
[0018]
Further, as shown in FIG. 4, the white light emitting diodes D _{2 to} D ₄ and D _{6 to} D ₈ generally have a high light intensity. Therefore, the balance is adjusted by adjusting the variable resistor VR _1. It is preferable to take. That is, in this example, a green light-emitting diodes D _1, D ₅ sets the value r ₂ of the resistor R ₂ to be used with full rated (upper zone), for white light-emitting diodes D ₂ to D ₄ , D ₆ -D ₈ side of the variable resistor VR ₁ (the resistance value r ₁ ) is slightly lowered so that the output balance between the two light emitting diodes can be achieved. Thereby, white light with a good color distribution balance can be obtained.
[0019]
The white light is irradiated into the object to be observed, whereby the image of the object to be observed is picked up by the CCD 15, and the output of the CCD 15 is displayed on the monitor after image processing. In this example, since the object to be observed is irradiated with white light having a uniform spectral characteristic, an image within the object to be observed can be obtained with good color reproducibility.
[0020]
The number of white light and green light diodes arranged is arbitrary, but the light quantity of both light emitting elements is balanced according to the number of white light and green light by adjusting the volume of the variable resistor VR _1. It is possible.
[0021]
【The invention's effect】
As described above, according to the first aspect of the invention, since the green light emitting element is provided in addition to the white light emitting element, the electronic endoscope in which the light emitting element is arranged at the distal end portion of the endoscope. However, it is possible to irradiate white light having an emission spectrum characteristic without distortion, and an image with good color reproducibility can be obtained.
[0022]
Further, according to the invention of claim 2, since the light emitting element for white light or the light emitting element for green light is provided with an adjuster for adjusting the balance of light emission intensity, even when using light emitting elements having different light intensity, It is possible to obtain white light with a good color balance, and it is also possible to adjust the light quantity balance according to the ratio of the number of both light emitting elements.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a light emitting element and a lighting circuit of an electronic endoscope apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a finger-mounted electronic endoscope according to an embodiment.
3 is an enlarged cross-sectional view in which a portion where a light emitting diode is arranged in the electronic endoscope of FIG. 2 is cut in a radial direction.
FIG. 4 is an emission spectrum diagram of the light emitting diode of the example.
FIG. 5 is an emission spectrum diagram of a conventional white light emitting diode.
[Explanation of symbols]
10 ... Electronic endoscope,
15 ... CCD,
D ₁ , D ₅ ... green light emitting diodes,
D _{2 to} D ₄ , D _{6 to} D ₈ ... White light emitting diode,
Q ₁ ~Q ₆ ... transistor,
VR ₁ Variable resistor.

Claims (2)

An electronic endoscope apparatus comprising a plurality of light emitting elements for irradiating light toward the body to be observed at the distal end of the endoscope,
An electronic endoscope apparatus in which a white light emitting element for white light emission and a green light emitting element for green light are provided as the light emitting element. 2. The electronic endoscope apparatus according to claim 1, wherein the white light emitting element or the green light emitting element is provided with an adjuster for adjusting a balance of light emission intensity between the light emitting elements.

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