JPS6136928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light source device for an endoscope used for observing and photographing inside a body cavity.

In an endoscopic device, a small-diameter flexible tube is inserted into a body cavity, and an optical fiber bundle such as a class fiber incorporated into the tube is passed through an endoscopic window at the tip of the tube that reaches the area to be examined. Observation or photography is performed optically, and for this purpose an artificial light source is required to illuminate the inside of the body cavity. In this type of light source device for an endoscope, since the optical fiber bundle incorporated in the flexible tube, like the observation optical system, guides the illumination light to the area to be examined in the body cavity, this limited Since it is necessary to provide high-intensity illumination light source light to the optical fiber bundle in the light guiding area, and it is also necessary to prevent thermal damage inside the body cavity caused by the illumination light as much as possible, xenon discharge tubes have conventionally been used. etc. are used as the light source.

On the other hand, when taking a photograph, high-speed shutter control is necessary to obtain a clear image of the subject, and for this purpose, more powerful illumination light than the observation illumination is required. Moreover, when considering the above-mentioned thermal disturbance within the body cavity, it is desirable to limit the illumination time of the subject surface to the shortest possible time, especially the time necessary for photographing, for such high-intensity illumination for photographing.

In response to such requests from the subject to the light source device, the mechanical requirements of the light source device are desired to correspond to a wide variety of imaging conditions depending on various parts within the body cavity and the conditions of each part. Therefore,
This type of light source device must have a strong enough light emitting capacity to enable photographing under high-speed shutter control and to be able to respond to a wide range of photographic conditions.

On the other hand, when photographing under illumination using a light source device with such strong luminous ability, the tire lag of the shutter operation becomes a major factor in exposure errors when ultra-high-speed photography is required, such as close-up photography. An effective light source device can only be obtained by solving the above complications.

To this end, the present invention provides an operation for controlling the closing of a mechanical shutter when a normal exposure condition is obtained, depending on the brightness of the subject illuminated with a strong artificial light source, and a separate operation for controlling the closing of the mechanical shutter when the subject is illuminated with a strong artificial light source. By controlling the light source in at least two or three ways, including an operation of controlling only the artificial light source and the mechanical shutter or the artificial light source using a predicted signal according to the brightness of the An object of the present invention is to provide a device that corrects exposure errors based on time lag in a mechanical shutter and obtains proper exposure.

The illustrated embodiment will be described in detail below.

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, in which a light receiving element 2 that receives reflected light from a body cavity to be examined illuminated by a light source bulb 1 such as a xenon discharge tube is used as a sensing element. An appropriate exposure time adjustment circuit 4 and an appropriate exposure time prediction circuit 5 are arranged in parallel to the light amount detection circuit 3. The light amount detection circuit 3 integrates the brightness information current corresponding to the brightness of the subject from the light receiving element 2, and transmits the integrated state value to the appropriate exposure time adjustment circuit comprising, for example, a switching circuit. 4 and a differential circuit configuration.

The adjustment circuit 4 sends an appropriate exposure signal via a sequence circuit 6 to a mechanical shutter 8 whose shutter blades 7 are exposed to the amount of light illuminated by the light source bulb 1, while the prediction circuit 5 sends a prediction signal The signal is supplied to the lighting control circuit 9 of the light source bulb 1 and also to the mechanical shutter 8 via the sequence circuit 6.

Furthermore, an output line for a signal output from the sequence circuit 6 in response to the proper exposure signal is connected to the lighting control circuit 9. Additionally, reference numeral 10 indicates a synchronization contact mechanism on the camera side, and an output line is extended from the mechanism 10 toward the sequence circuit 6.

The operation of the apparatus of the present invention having such a configuration will be explained with reference to the sequence time chart shown in the second figure.

First, under the control of its lighting control circuit 9, the light source bulb 1 is in a light emitting state as normal observation illumination light in a low level range shown as the observation light amount level in the section of artificial illumination light amount in FIG. When the observation state shifts to the shooting state and the camera shutter is operated (at time t ₁ ), a synchronization signal is sent from the synchronization contact mechanism 10 to the sequence circuit 6, and the circuit 6 starts operating. do. The control operation of the sequence circuit 6 begins with applying a high-level signal to the mechanical shutter 8 (t ₂ ), the shutter blade 7 is closed for a certain period of time (20 ms in the diagram). After this predetermined time has elapsed, the mechanical shutter 8 starts to open when the close signal changes to a low level.

On the other hand, while the mechanical shutter 8 is in the temporarily closed state, the camera shutter is opened by the control mechanism within the camera, and even when the closing signal is transferred, the lighting control circuit 9 that receives it is activated. The amount of light emitted from the light source bulb 1 is rapidly increased, and the light amount detection circuit 3 starts a detection operation. The detection circuit 3 uses the light receiving element 2 to capture the reflected light from the subject, which is strongly illuminated by the opening of the mechanical shutter 8 and the brightness increase of the light source bulb 1, and integrates the current based on the optical information. . The rise of the exposure integrated output voltage signal in the light amount detection circuit 3 is differentially detected by the appropriate exposure time prediction circuit 5, and when this rise is extremely steep (the state shown by the dotted line of the light amount detection circuit output in the figure), that is, at that time. When the brightness of the object under the illumination is extremely high under the imaging conditions, the differential output is generated as shown by the dotted line in FIG. 2 (at time _t4 ).

If this differential output is a value greater than a certain value, the lighting control circuit 9 and the sequence circuit 6 that receive the differential output
However, the amount of light emitted from the light source bulb 1 is lowered to the state shown by the dotted line, and the mechanical shutter 8 is closed as shown by the dotted line.

This action ends the photo shoot by reducing the illumination light and closing the mechanical shutter. The setting of the output level for the differential output for this control is based on the relationship between the illumination light and the time lag of the mechanical shutter closing operation calculated in advance.
The sharpness of the light intensity integrated output voltage when the brightness of the object is so bright that there is a risk of overexposure as a result of exposure control with a mechanical shutter time lag when the illumination light intensity has decreased. This is a value that occurs due to a sudden rise, and can be easily set by calculation and experiment.

When this differential output is a signal at a lower level than the previously set value, that is, when the brightness of the subject is lower than the above-mentioned imaging state, the output of the light amount detection circuit 3 is indicated by the solid line in the diagram. It will rise as shown. At the rise of the output in this state,
The differential output of the appropriate exposure time prediction circuit 5 does not occur, or even if it does occur, the signal is at a low level that is insufficient to cause the sequence circuit 6 and the lighting control circuit 9 to react, and as a result, the illumination state and shutter state change. A predetermined period of time (appropriate exposure time) elapses while the state is maintained as it is. As this time elapses, the integrated output of the light amount detection circuit 3 increases, and the appropriate exposure time adjustment circuit 4 that senses this increases and sends the output to the sequence circuit 6 (at time _t5 ). In response to this, the circuit 6 drives the mechanical shutter 8 to close and causes the lighting control circuit 9 to perform a reduced operation.

In the previous operation, the light source control operation by normal exposure adjustment operation is completed, but as a subsequent processing operation of the mechanism section, the camera shutter closes at time t ₆ according to the internal control operation of the camera, and t At point ₇ , according to the control set in advance to the sequence circuit 6 as the maximum possible flash time for photographing,
The light amount detection circuit 3 is reset, and the mechanical parts such as the observation aperture of the mechanical shutter 8 are returned to their initial states.

In this way, the first aspect is to control the light source and mechanical shutter using the predicted exposure time value based on the brightness state adjusted in advance according to the brightness of the object, and the integral operation of the brightness information is also possible. With the second mode of controlling the mechanical shutter by normal exposure time adjustment, it is possible to sufficiently control a wide range of changes in the brightness of the subject, but as another embodiment of the apparatus of the present invention, By providing another control operation according to the third mode between these first and second modes, it is possible to adapt to a wider variation range of brightness and to smoothly shift the control mode.

In other words, when the brightness of the subject is intermediate between the two control modes described above, and under strong illumination light from the light source bulb 1, proper exposure cannot be obtained even with the time lag of the mechanical shutter. When the determination is made, the rise of the integral output of the light amount detection circuit 3 is relatively slow as shown by the dashed line in FIG. Occurs at ₄ ′. In this case, the differential output of is at a slightly low level corresponding to the rise of the integral output of the light amount detection circuit 3, and therefore, the differential output is divided at a certain level of this differential output, and The differential output belonging to the level classification is also controlled according to the first aspect described above, and for the differential output belonging to the relatively low level classification, the lighting control circuit 9 responds and the light source bulb 1 is controlled as shown by the dashed line in the figure. However, the sequence circuit 6 does not respond and, as a result, the mechanical shutter 8 remains open. Then, under the reduction of the light source bulb 1, the integrated output of the light amount detection circuit 3 rises very gradually to the state shown in the figure, and at time t' ₅ when it reaches the trigger level of the appropriate exposure time adjustment circuit 4, as described above. The mechanical shutter 8 is controlled in a second manner.

The differential output can be divided by using a comparator or the like based on the previous output level, or by interposing a gate circuit in the input line to the sequence circuit 6 based on the time of occurrence. It may be divided.

In this way, the device of the present invention is equipped with a function section that predicts the exposure time using a differential operation, in addition to detecting the amount of light by an integral operation based on brightness information from artificial illumination of the subject. When shooting, the illumination light source and shutter are controlled before the proper exposure signal is generated by the integral operation, so that the illumination light source operates for as short a time as possible and exposure errors due to time lag in the mechanical shutter are minimized. High-precision exposure control is possible, and with this control means, it is possible to use a light source that is strong enough to adapt the brightness of artificial illumination light to a wide range of shooting conditions, resulting in exposure The range of adjustable shooting conditions can be expanded. Furthermore, by dividing the predicted values and controlling the light source and mechanical shutter, or controlling only the light source, according to the divided predicted values, it is possible to further expand the range of conditions under which photography can be performed, and to improve the control mode. The device of the present invention is extremely useful as a light source device in an endoscope, as it can smoothly shift the exposure rate and perform exposure control with higher precision within the control range.

Further, for combinations of different aspects of exposure control in the apparatus of the present invention, another aspect may be incorporated between the combinations of these aspects, for example, intermediate means such as closing the shutter after a predetermined period of time after controlling the light source. is also possible, and the device of the invention does not in any way prevent the incorporation of such intermediate means.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention, and FIG. 2 is a time chart showing the operating state of the main parts of the apparatus of the present invention. DESCRIPTION OF SYMBOLS 1... Light source bulb, 2... Light receiving element, 3... Light amount detection circuit, 4... Appropriate exposure time adjustment circuit, 5... Appropriate exposure time prediction circuit, 6... Sequence circuit, 7
... Shutter blade, 8 ... Mechanical shutter, 9
...Lighting control circuit, 10...Synchro contact mechanism on the camera side.

Claims (1)

[Scope of Claims] 1. A light-receiving element that receives reflected light from a test part in a body cavity illuminated by a light source, and receives an information current from the light-receiving element according to the brightness of the test part, and receives the information from the light-receiving element. a light amount detection circuit that integrates a current and outputs the integrated state value; a proper exposure time adjustment circuit that outputs a proper exposure signal when the output from the light amount detection circuit increases and reaches a proper exposure level; A sequence circuit for receiving a signal and closing a mechanical shutter with a shutter blade facing into the illumination optical path of the light source, and a sequence circuit for reducing the lighting control circuit of the light source. In the lighting device, an appropriate exposure time prediction circuit that receives the output of the light amount detection circuit is installed in parallel with the appropriate exposure time adjustment circuit, and the rise of the output from the light amount detection circuit is differentiated by the appropriate exposure time prediction circuit. A light source device for an endoscope, characterized in that when the differential output is detected and the differential output is above a certain value, the sequence circuit and the lighting control circuit are activated to reduce the amount of light emitted from the light source and close a mechanical shutter. . 2. A light-receiving element that receives reflected light from the examined part in the body cavity illuminated by a light source, receives an information current according to the brightness of the examined part from the light-receiving element, integrates the information current, and calculates the a light amount detection circuit that outputs an integral state value, a proper exposure time adjustment circuit that outputs a proper exposure signal when the output from the light amount detection circuit increases and reaches a proper exposure level, and a light source that receives the proper exposure signal. An illumination device for photographing in an endoscope, comprising a sequence circuit that closes a mechanical shutter with shutter blades facing into the illumination optical path of the light source, and a sequence circuit that reduces the lighting control circuit of the light source, the light amount as described above. An appropriate exposure time prediction circuit that receives the output of the detection circuit is installed in parallel with the above-mentioned appropriate exposure time adjustment circuit, and the appropriate exposure time prediction circuit differentially detects the rise of the output from the light amount detection circuit, and calculates the differential output. Depending on whether the level is higher or lower than a certain value, if the level is high, the sequence circuit and lighting control circuit are activated to reduce the amount of light emitted from the light source and close the mechanical shutter. A light source device for an endoscope, characterized in that, in the case of a low level classification, only a lighting control circuit is operated to reduce only the amount of light emitted from the light source.