Light Supply Device for an Endoscope

This invention relates to a light supply device for an endoscope which emits a light toward an endoscope.

According to a conventional endoscope system, a connector of a universal cord of an endoscope is detachably inserted into the socket of a light supply device. A light of observation is incident from the lamp of the light supply device onto the end surface of the light guide of the endoscope which extends through the socket. The light incident on the end surface of the light guide is transmitted through the light guide to the distal end of the endoscope to permit a region of interest of a subject to be illuminated thereby.

In such conventional light supply device, if the connector of the universal cord is removed from the socket of the light supply device during the lighting of the lamp, the light of the lamp leaks to the outside through the socket. When such light reaches the user's eyes (for example, the doctor's eyes or the patient's eyes), the user's eyes are dazzled by the light and there is a possibility that a bad effect will be imparted to his eyes.

It is accordingly an object of this invention to provide a light supply device for an endoscope which prevents the user's eyes from being dazzled by light leaking through the socket of the light supply device.

According to the light supply device of this invention, a connector of a universal cord of the endoscope is detachably inserted into the socket of a light supply device. The light supply device includes a lamp for emitting a predetermined amount of light into a light guide of the endoscope. A light control means is provided for decreasing an amount of light which leaks through the socket of the light supply device when the connector is removed from the socket of the light supply device.

FIG. 1 is a block diagram showing a light supply device for an endoscope according to one embodiment of this invention;

FIG. 2 is a block diagram showing a light supply device for an endoscope according to another embodiment of this invention; and

FIG. 3 is a block diagram showing a light supply device for an endoscope according to another embodiment of this invention.

In FIG. 1, an universal cord 13 in which a light guide 12 for transmitting a light of observation is received is provided at one end with a connector 10. The other end of the universal cord 13 is connected to an operation section of an endoscope 14. The light guide 12 is formed by bundling together a predetermined number of optical fibers. A light source device 20 includes a light source, for example, a lamp 22 such as a halogen lamp, Xenon lamp or arc lamp. The lamp 22 is connected to a power source 28 through a relay switch 24 and dimmer circuit 26. A reflective mirror 30 is provided behind the lamp 22. Mirror 30 is bowl-shaped such that it has, for example, an elliptical outer configuration. The focal point of the reflective mirror 30 is set such that it is located opposite to the distal end 12a of the light guide 12 which extends through the socket 40 into the light supply device 20. In consequence, light emitted from the lamp 22 is reflected on the inner surface of the reflective mirror 30, condensed toward the distal end 12a of the light guide 12 and transmitted to the proximal end of the endoscope 14 through the light guide 12. The dinner circuit 26 is comprised of, for example, a phase-control dimmer circuit using a conventionally known thyristor. An amount of light emitted from the lamp 22 can be continuously controlled by operating a knob 51 of a variable resistor (volume) 50 which is connected to the dimmer circuit 26. The variable resistor 50, together with the socket 40, is fixed to the housing of the light supply device 20.

The relay switch 24 includes a normal closed contact 24a, a normal open contact 24b connected to the lamp 22 and a movable contact 24c connected to the dimmer circuit 26. The relay switch 24 is operated by a solenoid 60. That is, the movable contact 24c is connected to the contact 24b when the solenoid 60 is energized and connected to the contact 24a when the solenoid 60 is deenergized. The solenoid 60 is connected to a power source 62 through a detector 64. The detector 64 comprises contacts 64a and a movable contact 66 which extends from an abutting surface between the socket 40 and the connector 10. The contacts of the detector 64 are closed by the movable contact 66 when the connector 10 is inserted into the socket 40 and opened when the connector 10 is removed from the socket 40.

While the connector 10 is inserted into the socket 40, the movable contact 66 of the detector 64 is projected toward the inside of the housing 20 to cause the contacts of the detector 64 to be closed. At this time, an electric current from the power source 62 flows through the solenoid 60 to cause the solenoid to be energized. As a result, the movable contact 24c of the relay switch 24 is connected to the contact 24b, causing the electric current from the power source 28 to be supplied to the lamp 22 through the dimmer circuit 26 to permit the lamp 22 to be lit. While, on the other hand, the connector 10 is detached from the socket 40, the contacts of the detector 64 are opened. Since the solenoid 60 is deenergized, the movable contact 24c of the relay switch 24 is returned to the side of the contact 24a. As a result, the electric current flowing from the power source 28 through the dimmer circuit 26 to the lamp 22 is interrupted by the relay switch 24, extinguishing the lamp 22. For this reason, the light emission through the socket 40 to the outside of the light supply device 20 is prevented, thereby preventing the user's eyes (for example, doctor's eyes of patient's eyes) from being exposed to leaking light.

In an embodiment shown in FIG. 2, a normally closed contact 24a of a relay switch 24 is connected to the lamp 22 through a resistor 70 of a predetermined value (for example, five times the resistance of the lamp 22). A normally open contact 24b of the relay switch 24 is connected directly to the lamp 22. The remaining arrangement of this embodiment is the same as that of the first embodiment and further explanation thereof is omitted for brevity.

According to the embodiment of FIG. 2, when a connector 10 is detached from the socket 40, the contacts 64a of a detector 64 are closed by a movable contact 66, causing an electric current from a power source 62 to flow through and energize a solenoid 60. As a result, a movable contact 24c is switched from the contact 24b to the contact 24a. As a result, an electric current from a power source 28 flows into the lamp 22 through the resistor 70 which is connected to the contact 24a of the relay switch 24, thus decreasing an amount of light emitted from the lamp 22. Since an amount of light leaking through a socket 40 is decreased, the user's eyes are prevented from being dazzled and thus the user's eyes are protected against an otherwise intense light.

According to this embodiment, as a smaller amount of light is emitted through the socket 40 during a time period in which the connector 10 is removed from the socket 40, if the filament of the lamp 22 is burned out, the user can readily discover the faulty lamp 22 before the endoscope is used.

Although in the above-mentioned embodiments the light from the light supply device is interrupted or attenuated by controlling a power supply to the light source, it is possible to shield or attenuate the light from the light supply device by using a shield plate or a filter. That is, according to an embodiment shown in FIG. 3, a lamp 22 in a light supply device 20 is connected to a power source 28 through a dimmer circuit 26. Behind the lamp 22 is disposed a reflective mirror 30 which is the same as that of the preceding embodiments. A solenoid 60 is connected to the power source 62 and a detector 80 is connected in series between the solenoid 60 and the power source 62. The detector 80 comprises a pair of projection pins 81a, 81b mounted on a connector 10 and a pair of pin sockets 82a, 82b which are provided on the socket 40 and into which the projection pins are inserted. A shutter plate 84 is mounted on a movable rod 60a of the solenoid 60 and, when the solenoid 60 is demagnetized, the shutter plate 84 is inserted by a spring 86 between the lamp 22 and a distal end 12a of a light guide 12. The remaining arrangement of the FIG. 3 embodiment is the same as that of the preceding embodiment and further explanation is therefore omitted.

According to this embodiment, when the connector 10 is removed from the socket 40, the pins 81a and 81b of the detector 80 are respectively disconnected from the sockets 82a and 82b, causing the detector 80 to be opened to permit the solenoid 60 to be demagnetized. Since at this time the shutter plate 84 is inserted under the urging force of the spring 86 between the lamp 22 and the distal end 12a of the light guide 12, all the light reflected on the reflective mirror 30 is shielded by the shutter plate 84. As a result, no light leaks through the socket 40 and thus the user's eyes are prevented from being dazzled by the light. Where the shutter plate 84 is formed of a light attenuating filter, an amount of light from the lamp 22 is attenuated by the light attenuating filter so that the user's eyes are not dazzled by the light leaking through the socket 40. Where the light attenuating filter is used, if the filament of the lamp 22 is burned out, the user can discover a faulty lamp 22 before the endoscope is used.

Although this invention has been shown and described in connection with particular embodiments, variations, changes and modifications may be made within the spirit and scope of the invention. For example, the solenoid may be excited during the time period in which the connector is removed from the socket so that the movable contact of the relay switch can be moved into contact with the normally open contact. Alternatively, the shutter plate may be projected between the lamp and the distal end of the light guide so as to decrease an amount of light leaking through the socket of the light supply device. Even if in this case a mechanism such as a solenoid is faulty, a light transmission to an endoscope now in use is maintained, permitting examination under the endoscope and improving the reliability of the light source for the endoscope. A liquid crystal or a mechanical shutter mechanism may be used in place of the shutter plate of FIG. 3. A motor may be used in place of the solenoid to drive a relay switch and shutter plate. In this case, the motor is connected to an electronic detection circuit adapted to be operated during the time period in which the connector is removed from the socket. In summary, it is only necessary that a mechanism be provided for attenuating an amount of light emitted through the socket of the light supply device during the time period in which the connector of the endoscope is removed from the socket.