JPH09253044A - Noise elimination structure for light source device for electronic endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a noise current transmitted from the lighting circuit of a light source to the light source and to reduce high frequency noise generated from a device. SOLUTION: Inside the case body 11 of a light source device, a xenon lamp 14 is connected to an ignitor 17 by an anode ray 16A and a cathode ray 16B and the ignitor 17 is connected to the lighting circuit 20 by the anode ray 18A and the cathode ray 18B. Then, respectively to the anode ray 16A and the cathode ray 16B, a ferrite core 26 is attached while winding the respective rays for two times. By the ferrite core 26, the noise current transmitted from the lighting circuit 20 to the xenon lamp 14 is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for an electronic endoscope, and more particularly to a structure for removing noise generated from a light source device for controlling lighting of a xenon lamp.

[0002]

2. Description of the Related Art An electronic endoscope apparatus is a CCD (Charge Coupl) which is a solid-state image pickup device arranged at the tip of an electronic scope.
ed Device), an image of the inside of the observed body is imaged, and the irradiation light for imaging the inside of the observed body is supplied from a light source device to a tip end of a light guide.

FIG. 4 shows an example of the structure of a conventional light source device. In a housing 1 of this light source device, a lamp house (case body) 3 in which a xenon lamp 2 is housed and arranged.
The lamp house 3 is provided with a lighting circuit (member) 5 via an igniter 4. This lighting circuit 5
Is attached to a circuit board 7 supported by an L-shaped support 6 made of aluminum, and the support 6 is attached to a bottom plate of the housing 1 via an insulating plate 8 such as bakelite. The withstand voltage of 4 kV or higher is maintained by the insulating plate 8. Further, a connector receiving portion 9 for connecting a light guide connector on the electronic scope side is provided on the front panel of the housing 1.

FIG. 5 shows a signal waveform formed by the lighting circuit 5, and when the switching operation is performed based on the control pulse shown in FIG. 5A, it is shown in FIG. The switching current is formed at a high frequency of about 110 kHz. This switching current is given to the igniter 4 in FIG. 4, and an igniter discharge is generated there, whereby the xenon lamp 2 in the lamp house 3 is discharged.
Lights up. Then, the light from the xenon lamp 2 is supplied to the light guide of the electronic-scope-side connector arranged in the connector receiving portion 9, and is guided to the tip through the light guide.
Can be imaged.

[0005]

By the way, in the above-mentioned conventional light source device, high-frequency noise is generated due to the switching current of the lighting circuit 5 shown in FIG. 5 (B) and the high-voltage pulse current from the igniter 4. There is a problem that noise adversely affects images. That is, FIG. 6 shows the noise generation state of the lighting circuit 5, and as can be understood from this figure, the switching current is formed at a frequency of about 110 kHz, and a high voltage (ignition) pulse is output by this. Therefore, noise with a frequency that is an integral multiple of 110 kHz occurs, and this noise is several tens of MH.
It has the characteristic of maintaining a certain level up to the high frequency region of z.

Then, such a noise current is transmitted to each component through the conductive wire connecting the lighting circuit 5 and the igniter 4, and the conductive wire connecting the igniter 4 and the xenon lamp 2 to each other in the apparatus. It also causes noise from the components. In addition, since the lighting circuit 5 of the light source device is not close to the processor circuit that processes the video signal, the countermeasure against the noise generated in the lighting circuit 5 is not sufficiently taken under the present circumstances. is there.

The present invention has been made in view of the above problems, and an object thereof is to eliminate a noise current transmitted from a lighting circuit of a light source to a light source and reduce high frequency noise generated from the device. Another object of the present invention is to provide a noise removing structure for a light source device for an electronic endoscope that can perform the above-mentioned operation.

[0008]

In order to achieve the above object, the invention described in claim 1 is a light source for irradiating light from a tip portion of an electronic endoscope, and a lighting for controlling lighting of the light source. In a light source device for an electronic endoscope including a circuit, a ferrite core (magnetic ring) for removing noise is arranged on both an anode line and a cathode line connecting the light source and the lighting circuit or only on the anode line. It is characterized by having done.

According to the above construction, the ferrite core removes the noise current transmitted through the conductive wire from the lighting circuit to the xenon lamp which is the light source, and the high frequency noise generated by the switching current and the igniter discharge current can be reduced. . Therefore, noise is less likely to be induced and accumulated in the lighting circuit section, the igniter section, the light source section, and the like.

[0010]

1 and 2 show a noise removing structure of a light source device for an electronic endoscope, which is an example of an embodiment. In FIG. 1, the light source device 10 includes a housing 11 made of a conductive material, and the housing 11 is grounded to a ground (frame ground GND). As described above, the front panel 12 of the housing 11 is provided with the connector receiving portion 13 for connecting the light guide connector on the electronic scope side.

A xenon lamp 1 is provided inside the housing 11.
A lamp house 15 incorporating 4 is arranged, and the lamp house 15 is a shield case body made of a conductive material. The light of the xenon lamp 14 is emitted from the emission port of the lamp house 15 toward the connector receiving portion 13 side. A conductive wire (lead wire) 16A is connected to the anode and a conductive wire 16B is connected to the cathode of the xenon lamp 14, and an igniter 17 is connected via the conductive wires 16A and 16B. The conductive wire is connected to the igniter 17. 18A,
The lighting circuit (plural members) 20 is connected via 18B.

The lighting circuit 20 is provided with a switch circuit such as a transistor, which forms a switching current. Based on this switching current, a high-voltage pulse current for igniter discharge is supplied from the igniter 17 to the senon lamp 14. To be done.

In this example, the lighting circuit 20 is attached to a metal support 22 via a circuit board 21, and the lighting circuit 20 and the support 22 are entirely covered with a case body 23 serving as a conductive shield. The case body 23 shields noise generated from the lighting circuit 20, the support body 22, and the like. The support 22 is attached to the housing 11 via an insulating plate 24.

A ferrite core 26 is separately provided on the two conductive wires 16 connecting the igniter 17 and the xenon lamp 14. The attachment state of the ferrite core 26 is shown in FIG. 2, and in the embodiment, the ferrite core 26 is attached by winding each wire twice in each of the anode wire 16A and the cathode wire 16B.

That is, generally, in the arrangement of the ferrite core,
A pair of the anode wire and the cathode wire is passed through the ferrite core, and when applied to the light source device, as shown in FIG. 3, the ferrite core 26 is arranged by passing the two wires of the anode wire 16A and the cathode wire 16B. You can also do it. However, in the mounting shown in FIG. 3, since the distance between the two lines is short, the high-voltage pulse is disturbed and the lighting control is adversely affected.
Moreover, it also causes the dielectric breakdown of the anode wire 16A and the cathode wire 16B.

Therefore, in this embodiment, the anode wire 16A is
Ferrite cores 26 are separately arranged to separate the cathode wire 16B and the cathode wire 16B. Further, since the conductive wire 16 has a large core diameter due to the necessity of flowing a large current, it can be passed through the ferrite core 26 only once as in the case of FIG. 3, whereas in the case of FIG. You can pass it twice,
The number of passages through the ferrite core 26 can be increased. Therefore, in such a ferrite core 26, since the impedance with respect to the noise current rises in proportion to the square of the number of turns, there is an advantage that the noise removal effect is enhanced.

This example has the above structure. According to the above ferrite core 26, the anode wire 16A and the cathode wire 16B are formed.
The noise transmitted through the switch is removed, and the generation of high-frequency noise due to the switching current used in the lighting circuit 20, the high-voltage pulse formed by the igniter 17, or the discharge of the xenon lamp 14 is suppressed.

The ferrite core 26 may be arranged only on the anode wire 16A, or the igniter 17 may be provided.
The anode line 18A and the cathode line 18B between the lighting circuit 20 and the lighting circuit 20 can also be arranged.

[0019]

As described above, according to the present invention,
Since a ferrite core for removing noise is placed on both the anode wire that connects the lighting circuit and the light source, or both the anode wire and the cathode wire, the noise current transmitted between the lighting circuit and the light source is removed, and the device It is possible to reduce high frequency noise generated from each of the constituent members.

[Brief description of drawings]

FIG. 1 is a perspective view showing a noise removing structure of a light source device for an electronic endoscope according to an example of an embodiment of the present invention.

FIG. 2 is a view showing a ferrite core mounting portion of FIG.

FIG. 3 is a view showing another state of mounting the ferrite core.

FIG. 4 is a perspective view showing a configuration of a conventional light source device for an electronic endoscope.

FIG. 5 is a waveform diagram showing signals used in a lighting circuit of the light source device.

FIG. 6 is a graph showing noise generated in a lighting circuit.

[Explanation of symbols]

 1, 11 ... Casing, 2, 14 ... Xenon lamp, 4, 17 ... Igniter, 5, 20 ... Lighting circuit, 16A, 18A ... Anode wire, 16B, 18B ... Cathode wire, 26 ... Ferrite core.

Claims (1)

[Claims] 1. A light source device for an electronic endoscope, comprising: a light source for irradiating light from a tip portion of an electronic endoscope; and a lighting circuit for controlling lighting of the light source. A noise removal structure for a light source device for an electronic endoscope, wherein a ferrite core for removing noise is arranged on both the anode line and the cathode line to be connected or only on the anode line.