JPS6153049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light source device for an endoscope, which includes a light source for collation and a light source for photographing.

A light source device that introduces light from a collimation light source, e.g., a tungsten lamp, into the endoscope's light guide during diagnosis, and a light source device that introduces light from a photographic light source, e.g., a flash discharge tube, into the endoscope's light guide during imaging. In this case, an optical path switching mirror is placed in the light source optical path of both light sources, and this mirror is used as the camera's shutter and
A configuration is adopted in which the light source is driven in synchronization with the release, and the light source is switched from a collimation light source to a photographing light source. To drive this optical path switching mirror, 10
With a light source device in which the amount of light emitted is controlled by an automatic photometer because it is accompanied by a mechanical delay of about milliseconds, there is a risk that the subject will often be photographed with an inappropriate amount of exposure. In other words, even though the shutter opens at the same time as the shutter release is pressed, because the optical path switching mirror has the mechanical delay described above, some of the light from the illumination light source is used as photographic light. The light reaches the film surface through the guide and image guide, and during close-up photography, the small amount of light reaches the appropriate exposure, which causes the photometry circuit to act and generate a light emission stop signal for the photographic light source. . Despite this, the light source for photography, that is, the flash discharge tube, emits light after a certain period of time has elapsed after the shutter release is pressed and the shutter is opened, but by this time it has already generated a light emission stop signal. Since the charge in the commutating capacitor has been discharged, the flash discharge tube continues to emit light in an uncontrollable state, giving the maximum amount of light to the film, resulting in overexposure. The shooting will be completed in this state.

The present invention has been made in view of the above-mentioned circumstances, and the present invention promptly stops the light emission of the photographing light source when the light from the collimation light source reaches the proper exposure for the film, particularly during close-up photography. It is an object of the present invention to provide a light source device for an endoscope that can complete photographing with proper exposure.

An endoscope light source device according to an embodiment of the present invention will be described below with reference to the drawings.

As shown in the figure, the endoscope 2 is equipped with an image guide 4 and a light guide 6 as is well known, and an objective lens is mounted on the end surface of the image guide 4 facing the body cavity wall 5 to be photographed or diagnosed. 8 is positioned, and an eyepiece 10 is positioned on the end surface of the image guide 4 on the camera side. This endoscope 2 is connected to a camera 12, and a prism 1 is placed on its optical path.
4. Shutter 16 and film 18 are arranged. This camera 12 includes a shutter release 20 for opening the shutter 16 and a light receiving element 22 arranged to detect a portion of the incident light reflected by the prism 14 for detecting the amount of exposure of the film 18. Equipped with: Like the image guide 4, the light guide 6 of the endoscope 2 has one end directed toward the body cavity wall 5, and the other end connected to a light source device. This light source device is of a two-lamp switching type, and includes a collation lamp 2 for illuminating the body cavity wall 6 by introducing light into the light guide 6 during diagnosis.
4. For example, a tungsten lamp and a light source for photographing, that is, a flash discharge tube 26, are used to illuminate the body cavity wall 5 by introducing light into the light guide 6 during photography, and to form an image of the body cavity wall 5 on the film surface. We are prepared.
The collation lamp 24 is connected to a collation lamp control circuit 27 that controls this lamp, and the flash discharge tube 2
6 is connected to a discharge tube circuit including a well-known series control dimming circuit as will be explained later. An optical path switching mirror 28 is located in the light source optical path of the collimation lamp 24 and the flash discharge tube 26,
This optical path switching mirror 28 is configured by a solenoid 3 that rotates the mirror 28 and switches the optical path to the light introduction end face of the light guide 6 from the light source optical path of the collimation lamp 24 to the light source optical path of the flash discharge tube 26.
attached to 0. This solenoid 30
is connected to a solenoid drive circuit 32 that operates in response to the shutter release 20.

The discharge tube circuit includes a flash discharge tube 2 as shown in the figure.
6. It is composed of a closed circuit consisting of a main thyristor 34 and a main capacitor 36, and a DC power supply 38 is connected to the main capacitor 36. The main thyristor 34 is connected in parallel with a series circuit consisting of a commutating capacitor 40 and a commutating thyristor 42 which apply a reverse bias to the main thyristor when light emission is stopped, as is well known as a series control dimming circuit. , a resistor 44 is connected between its anode and cathode, and a commutating thyristor 42 and
A resistor 46 is connected between the DC power supply 38 and the DC power supply 38 . A flash discharge tube trigger circuit 48 is connected to the trigger electrode of the flash discharge tube 26 , and this trigger circuit 48 is also connected to the gate of the main thyristor 34 . The trigger circuit 48 is also connected to a delay circuit 50 which operates in response to the shutter release 20 and provides a delayed signal to the trigger circuit. The gate of the commutating thyristor 42 is connected to a trigger circuit 52 that makes the thyristor conductive.
This trigger circuit 52 operates in response to the shutter release 20, and when the photometric amount of the light receiving element 22 reaches a predetermined value corresponding to the appropriate exposure amount, a photometric circuit 54 supplies a light emission stop signal to the trigger circuit 52. It is connected to the.

As shown in the figure, in this embodiment, the delay circuit 5
An inhibit circuit 56 is connected between the delay circuit 50 and the discharge tube trigger circuit 48 for inhibiting the supply of the delay signal from the flash discharge tube trigger circuit 48 to the flash discharge tube trigger circuit 48 . This prohibition circuit 56 is a circuit activated by a light emission stop signal supplied from the photometry circuit 54, and is connected to this photometry circuit similarly to the commutation thyristor trigger circuit 52. That is, in this embodiment, if the light emission stop signal is generated from the photometry circuit 54 while the shutter release 20 is pressed and the delay circuit 50 is operating, the delay circuit 50 will stop the flash after the delay time has elapsed. Even if a delay signal is generated to activate the discharge tube trigger circuit 48, the trigger circuit 48 is not activated and the flash discharge tube 26 is configured not to emit light. Since the light source device for an endoscope of the present invention is configured as described above, during diagnosis, the light from the collation lamp 24 is
The light is reflected by the mirror 28, introduced into the light guide 6, irradiated onto the body cavity wall 5, and subjected to observation via the objective lens 8, image guide 4, and eyepiece lens 10. At the time of photographing, the shutter 14 is opened at the same time as the shutter release 20 is pressed, the photometry circuit 54, the solenoid drive circuit 32, and the delay circuit 50 start operating, and the solenoid 30 almost simultaneously drives the optical path switching mirror 28. Begin to. The movement of this mirror 28 requires 10 msec.
Because there is some degree of mechanical delay, a portion of the light from the collimation lamp 24 is reflected by the body cavity wall 5 and the eyepiece 1
0 and is imaged onto the film 16 via the prism 14. A portion of this light is introduced into the light receiving element 22, but if it does not reach a predetermined amount of light corresponding to proper exposure of the film surface, the photometry circuit 54 continues to operate. When the shutter release 20 is pressed and a predetermined delay time has elapsed, the delay circuit 50
A delay signal is applied to the flash discharge tube trigger circuit through the inhibit circuit 56 which is in an inactive state, and the flash discharge tube 26 starts emitting light. At this time, the mirror 28 has already been removed from the light source optical path of the flash discharge tube 26.
has been removed, so the light from this discharge tube is
It is reflected by the body cavity wall 5 and supplied to the film surface. As a result, the light receiving element 22 detects a predetermined amount of light, and the photometry circuit 54 supplies a light emission stop signal to the commutation thyristor trigger circuit 52.
As is well known, a reverse bias is applied to the main thyristor 34 to stop the flash discharge tube 24 from emitting light.
Shooting is complete.

Next, a description will be given of imaging when the body cavity wall 5 and the endoscope 2 are sufficiently close to each other. In this case, the light-receiving element 22 described above may detect a predetermined amount of light from the minute light from the collation lamp 24 that is introduced as the mirror 28 is mechanically delayed. That is, there are cases where the film 18 is exposed with proper exposure using light for collimation. In such a case, the photometry circuit 54 naturally generates a light emission stop signal, drives the normal commutation thyristor trigger circuit 52, makes the commutation thyristor 42 conductive, and discharges the charge charged in the commutation capacitor 40. There was a risk of causing a discharge. When such a situation occurs, the delay time has not yet elapsed, and the flash discharge tube 26 then starts to emit light, and the flash discharge tube 26 continues to emit light until the main capacitor 36 discharges all of its charge. continues to emit light, and as a result, the film is given an overexposed amount of light. However, in this invention, the light emission stop signal issued from the photometry circuit 54 is given to the prohibition circuit 56 as well as the commutation thyristor trigger circuit 52, and both are configured to operate, so there is no delay in close-up photography. A light emission stop signal is issued before the signal, and the commutation capacitor 40 is discharged by this signal, and the delay circuit 50 is discharged.
Even if the delay signal is issued after that, the prohibition circuit 5
6 is active, the supply of its delayed signal to the flash tube trigger circuit is prohibited. As a result, when appropriate exposure is given to the collimation light, the flash discharge tube 26 will not emit any light, eliminating the risk of overexposure.

As described above, according to the light source device for an endoscope of the present invention, when proper exposure is given to the film using only the collimation light during close-up photography, the inhibition circuit prevents the flash discharge tube from emitting light. This prevents overexposure accidents and allows proper photographs to be taken.In addition, in cases other than close-up photography, the flash discharge tube emits light as is commonly known, allowing the photographer to take photographs with proper exposure. can be completed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an endoscope imaging device including a light source device for an endoscope according to an embodiment of the present invention. 2...Endoscope, 4...Image guide, 6...
Light guide, 8... Objective lens, 10... Eyepiece, 12... Camera, 18... Film, 2
2... Light receiving element, 24... Lamp for collation, 26...
... Flash discharge tube, 28 ... Mirror, 30 ... Solenoid, 32 ... Solenoid drive circuit, 34 ... Main thyristor, 36 ... Main capacitor, 38 ...
DC power supply, 40... Commutation capacitor, 42...
... Commutation thyristor, 48 ... Flash discharge tube trigger circuit, 50 ... Delay circuit, 52 ... Trigger circuit,
54...Photometering circuit, 56...Prohibition circuit.

Claims (1)

[Claims] 1. A collimation light source used as the main light source during diagnosis and a photography flash discharge tube used as the main light source during imaging are placed in the optical path of both light sources and switch the light source light introduced into the light guide of the endoscope. means for driving the light source light switching means to switch the light source light introduced into the light guide from the illuminant light source light to the photographic light source light in response to the shutter release of the photographic camera; and the flash discharge. a switching element connected in series to the tube;
A main discharge capacitor connected to the series circuit consisting of the flash discharge tube and the switching element and supplying charge to the flash discharge tube, and a switching element that applies a reverse bias to the switching element to stop the flash discharge tube from emitting light. a trigger circuit that triggers the flash discharge tube and the switching element to cause the flash discharge tube to emit light; and a trigger circuit that operates in response to the shutter release and activates the trigger circuit after the operation of the light source light switching means is completed. It measures the amount of light introduced into the camera via a delay circuit that generates a delayed signal to activate and an image guide in the endoscope.
A photometry circuit that issues a light emission stop signal to activate the commutation circuit when a predetermined amount of light is reached; and a photometry circuit that operates in response to the light emission stop signal from the photometry circuit, and supplies a delay signal from the delay circuit to the trigger circuit. A light source device for an endoscope consisting of a prohibition circuit that prohibits