JPH0669439B2 - Light source device for endoscope - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an endoscope light source device for introducing illumination light into an endoscope, and particularly to various electronic devices only after a discharge lamp has finished its lighting operation. The present invention relates to a light source device for an endoscope, in which power to the circuit is not turned on and damage to an electronic circuit due to ignition noise is prevented.

[Prior Art] MOS type ICs generally used in recent years have a property of easily causing overcurrent breakdown (latch-up). Particularly, since an IC that is in operation when power is turned on is in an active state, If noise causes overvoltage or overcurrent, it may be easily damaged. Further, a bipolar IC or the like may be damaged by high-voltage noise in an operating state.

Therefore, in the case of the light source device for an endoscope, the CPU and other electronic circuits that perform various controls may be damaged by high-voltage noise generated from the ignition that lights the discharge lamp.

Therefore, in the conventional endoscope light source device, a noise removal filter is provided in the supply source of the electronic circuit, and the lighting device of the discharge lamp and the peripheral electronic circuit are each covered with a shielding material.

[Problems to be Solved by the Invention] In the above-described conventional endoscope light source device, the noise removal filter and the shielding material prevent the influence of noise on the electronic circuit. Therefore, when strong ignition noise occurs, It is not always possible to completely eliminate noise,
The electronic circuit was sometimes damaged. Further, the provision of the noise removal filter and the shielding material has a drawback that the manufacturing cost becomes high.

An object of the present invention is to provide a light source device for an endoscope which solves the above-mentioned conventional drawbacks and does not damage a CPU and other electronic circuits due to ignition noise.

[Means for Solving Problems] A light source device for an endoscope according to the present invention for solving the above problems will be described with reference to FIG. 1 corresponding to an embodiment. There is provided a lighting device 11 for lighting the lamp, an electronic circuit 8 for performing control other than the discharge lamp lighting operation, and a switching means 7 for connecting a power source to the electronic circuit 8 after a lapse of a certain time from the lighting operation of the discharge lamp 12. It is characterized by

[Operation] Until a certain period of time has passed since the lighting device 11 started the lighting operation of the discharge lamp 12, the switching means 7 is off and the electronic circuit 8 is not supplied with power.

Then, the switching means 7 is turned on and electric power is supplied to the electronic circuit 8 only after a lapse of a certain time after the lighting device 11 starts the lighting operation of the discharge lamp 12.

[Embodiment] An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing the circuit configuration of the embodiment, in which two transformers 3 and 9 are connected in parallel to an AC power source 1 via a power switch 2. The output terminal of the first transformer 3 is connected to a regulator 6 via a rectifier 4, and the output terminal of the regulator 6 is connected to a power input terminal of an electronic circuit 8 including a CPU via a delay timer 7 which is a switching means. It is connected to the. Then, the electronic circuit 8 controls operations other than the discharge lamp lighting operation, such as a light amount adjustment diaphragm or automatic exposure (not shown) during photography.

The delay timer 7 has a contact which is always OFF when the power switch 2 is OFF and after a lapse of a certain time after the power switch 2 is turned ON, and a certain time elapses after the power switch 2 is turned ON. After that (for example, 3 seconds later), the contact is turned on, and the configuration thereof may be one using a known switching circuit in which a transistor is combined with a capacitor or another known structure. A smoothing capacitor 5 is connected in parallel to the output terminal of the rectifier 4.

A discharge lamp power supply circuit 10 is connected to the output end of the second transformer 9, and a discharge lamp 12 such as a xenon lamp is connected to the output end of the discharge lamp power supply circuit 10 via a lighting device 11. Has been done.

Next, the operation of this embodiment will be described with reference to the time chart of FIG. 2. When the power switch 2 is turned on (FIG. 2a), the AC power supply 1
Is transformed into a predetermined voltage by transformers 3 and 9, respectively. And
At the same time, the output from the transformer 9 turns on the discharge lamp power supply circuit 10 (b), the lighting device 11 operates for a short time (c), and a high-frequency high-voltage ignition is applied to the discharge lamp 12 to release it. The electric lamp 12 lights up. And the discharge lamp power circuit
10 continues supplying electric power to the discharge lamp 12 (b), and the discharge lamp 12 maintains the lighting state.

On the other hand, the output from the transformer 3 is converted into a direct current by the rectifier 4, the waveform is smoothed by the smoothing capacitor 5, and then output as a constant voltage direct current by the regulator 6. However, when the power switch 2 is OFF, and when the power switch 2 is O
Immediately after it becomes N, delay timer 7 which is a switching means
Since the contact of is off, the output from the regulator 6 is not supplied to the electronic circuit 8. Then, after a lapse of a certain time from turning on the power switch 2, the contact 7 of the delay timer 7 is turned on (d), and the output from the regulator 6 is supplied to the electronic circuit 8.

Generally, after the power switch 2 is turned on, the time until the discharge lamp 12 finishes lighting is 3 seconds at the longest, so in the present embodiment, it is turned on 3 seconds after the power switch 2 is turned on. The delay timer 7 is used. Therefore, even if the power switch 2 is turned on, the illuminator 11 operates, and high-frequency high-voltage ignition noise enters the CPU or other electronic circuit 8 through radiation or through wiring, at that time, the electronic circuit 8 is still present. Since no power is supplied and it is not in operation, damage due to noise does not occur. Also, the ignition noise does not cause the CPU and other electronic circuits to malfunction.

EFFECTS OF THE INVENTION According to the light source device for an endoscope of the present invention, since electric power is not supplied to the electronic circuit until a certain time has elapsed from the lighting operation of the discharge lamp, ignition noise occurs due to the lighting operation. During this period, the electronic circuit is not in the operating state, so that the electronic circuit is not damaged by the ignition noise. Also, the malfunction of the electronic circuit due to the ignition noise does not occur. Furthermore, since no noise removal filter or the like is required, it is possible to provide an inexpensive and compact endoscope light source device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit of an embodiment of the present invention, and FIG. 2 is a time chart showing its operation. 7 ... Switching means, 8 ... Electronic circuit, 11 ... Lighting device, 12 ... Discharge lamp

Claims (2)

[Claims] 1. A light source device for an endoscope in which light of a discharge lamp is introduced into an endoscope, a lighting device for lighting the discharge lamp, and control other than the discharge lamp lighting operation. And a switching means for disconnecting the electronic circuit from a power supply until a certain time has elapsed from the lighting operation of the discharge lamp and connecting the power supply to the electronic circuit after a certain time has elapsed from the lighting operation of the discharge lamp. And a light source device for an endoscope. 2. The light source device for an endoscope according to claim 1, wherein the switching means is a delay timer.