JP3247189B2 - Automatic dimmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic light control device for automatically controlling the amount of light from a light source according to an input image signal.

[0002]

2. Description of the Related Art In recent years, endoscopes have been widely used not only in the medical field but also in the industrial field.

[0003] Further, as solid-state imaging devices such as CCDs have been miniaturized due to progress in integration technology, electronic endoscopes using solid-state imaging devices as imaging means have become widespread.

In an image pickup apparatus using a solid-state image pickup element as an image pickup means, such as the above-mentioned electronic endoscope, the dynamic range is narrower than the optical type at present. Image quality is deteriorated. For this reason, various automatic light control means have been proposed which automatically control the amount of light incident on the image pickup means to an appropriate level.

Hereinafter, a conventional example will be described with reference to the drawings.

As shown in FIG. 8, a conventional endoscope observation system provided with automatic light control means irradiates an object with illumination light, transmits an object image to an eyepiece unit 100 through an image guide, and observes the image. A mirror 101 and a light source device 10 for supplying illumination light to an incident end face of a light guide inserted through the endoscope 101
2, an external camera head 103 which is detachably attached to the eyepiece unit 100 and captures a subject image, and an external camera CCU 104 and an external camera CCU 104 which drive and control the external camera head 103 to signal-process an image signal.
And a monitor 105 for inputting a video signal processed by the external camera C and displaying a subject image.
The CU 104 includes a dimming circuit 106 for remotely controlling the light amount of the light source device 102 based on an imaging signal. An output of the dimming circuit 106 is an AUTO terminal of a dimming unit 107 in the light source device 102 (a in the figure). Terminal, and feedback-controls the light amount of the lamp 108 in the light source device 102 to control the brightness of the display image on the monitor 105 to an appropriate level. The external camera CCU 104 is
Power is supplied by the AC / DC adapter 109.

[0007]

However, in such a conventional example, the automatic dimming is possible because the light source device 102 is combined with an external camera CCU 104 having a dedicated dimming circuit 106. Only if That is, in the case of an external camera CCU that does not have the dimming circuit 106 dedicated to the light source device 102, the light source device 102
However, there is only a means for switching the dimming unit 107 to a manual terminal (terminal b in the figure) and performing a manual dimming operation, and there is a problem that automatic dimming cannot be performed.

Also, in a combination of another light source device different from the light amount control characteristic of the light source device 102 and the external camera CCU 104, the light amount control characteristic of the external camera CCU 104 does not conform to the light amount control characteristic of the light source device. A disadvantage arises in that feedback control of a large amount of light cannot be performed.

Further, the external camera head 103 and the external camera CCU 104 are connected to another external camera head and an external camera CCU having different sensitivities and response characteristics of AGC (auto gain control) with another dimming circuit. When the light source device 102 is controlled by using the camera, there is a problem that an optimum automatic light control characteristic cannot be obtained because the sensitivity characteristics of the camera are different.

Therefore, the conventional automatic light control characteristics cannot be obtained unless the external camera CCU has a dedicated light control circuit with respect to the light control characteristics of each light source device. Was.

Therefore, for example, Japanese Patent Application Laid-Open No. HEI 3-118022
As disclosed in Japanese Unexamined Patent Application Publication No. H11-163, a method of automatically dimming a plurality of light source devices by switching a plurality of predetermined dimming circuits has been proposed. Although automatic dimming is enabled for a plurality of light source devices, no consideration is given to the other light source devices, and the above-described description is applied to all combinations of the light source devices and the external camera CCU. Not only has the problem not been solved basically, but also a plurality of dimming circuits must be prepared for the combination of the light source device to be controlled and the external camera CCU, and the circuit becomes complicated.

The present invention has been made in view of the above circumstances, and has a simple configuration based on the light amount characteristics of a light source.
It is an object of the present invention to provide an automatic light control device that can realize optimum light amount control.

[0013]

According to the present invention, there is provided an automatic light control apparatus comprising: a DC converter for generating a DC signal corresponding to an output signal level of an imager for imaging a subject; and an output signal from the DC converter. Phase varying means for varying the phase advance / delay, level varying means for varying the level of the output signal from the DC converting means, dimming based on the output of the phase varying means or level varying means, and illuminating the object A light source for irradiating light, a predetermined disturbance signal, a disturbance signal generating unit that applies the disturbance signal to an output of the phase variable unit, and a phase variable unit or a level variable unit to which the disturbance signal is applied. Setting means for setting a level of a DC signal generated by the DC conversion means and a variable amount of the phase variable means in accordance with an imaging signal of the illumination light modulated by an output.

[0014]

The level of the DC signal generated by the DC converting means is determined by the setting means by the imaging signal of the illumination light adjusted by the output of the phase varying means or the level varying means to which the disturbance signal is applied. By setting the variable amount of the phase varying means, it is possible to perform optimal light amount control based on the light amount characteristics of the light source.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 relate to a first embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of an endoscope observation system provided with automatic light control means. FIG. 2 is an endoscope of FIG. FIG. 3 is a configuration diagram showing a detailed configuration of the observation system, FIG. 3 is a waveform diagram illustrating the dimming process in mode 1 in the endoscope observation system in FIG. 2, and FIG. 4 is mode 2 in the endoscope observation system in FIG.
FIG. 9 is a waveform diagram illustrating the light control processing of FIG.

As shown in FIG. 1, an endoscope observation system 1 including an automatic light control device according to a first embodiment irradiates a subject with illumination light and transmits a subject image to an eyepiece 2 by an image guide. The endoscope 3 to be observed and the universal cord 4 are detachably attached to the guide connector 5 so that the endoscope 3
A light source device 6 for supplying illumination light to an incident end face of a light guide passing through the inside, an external camera head 7 which is detachably attached to the eyepiece 2 and captures a subject image, and drive control of the external camera head 7 When the image pickup signal is signal-processed, an external camera CCU8, a monitor 9 for inputting a video signal (video signal) processed by the external camera CCU8 and displaying a subject image, and a video signal processed by the external camera CCU8 The image processing apparatus 1 includes an image processing apparatus 10 that controls the light amount of the light source device 6 so that the brightness of an image is at an appropriate level by a signal (video signal).
0 outputs a light control signal, which is a light amount control signal, to the light source device 6. Therefore, the automatic light control device includes the light source device 6 and the image processing device 10.
The external camera CCU 8 is supplied with power by an AC / DC adapter 11.

In the image processing apparatus 10, as shown in FIG. 2, a video signal (video signal) signal-processed by the external camera CCU 8 is clamped by a clamp circuit 21, and the clamped signal is integrated by an integrator 22. And input to the variable amplifier 23. The output of the variable amplifier 23 is output to a delay circuit 24 that delays a predetermined time to change the phase, and then is output as a dimming signal Z to an adder 29 and is converted into a digital signal by an A / D converter 25 and input to a CPU 26. Is done.

The CPU 26 controls a disturbance generator 27 and a switch 28 to output a predetermined disturbance signal X to the light source device 6 via an adder 29.
The light guide 3 is inserted into the endoscope 3 through the optical system 30 of the light guide connector 5 by causing the lamp 6a inside to emit light.
Illumination light based on the disturbance signal X is supplied to the incident end face of the light-emitting device 1.

In the endoscope 3, the illumination light is transmitted to the distal end portion by the light guide 31 and is radiated to the subject 33 through the illumination optical system 32 provided on the outgoing end surface of the light guide 31. The reflected light forms an image on the incident end face of the image guide 35 via the objective optical system 34 provided at the end of the endoscope 3. The formed subject image is transmitted to the eyepiece unit 2 by the image guide 35, and is captured by an external camera head mounted on the eyepiece unit 2. The captured image of the subject is subjected to signal processing by the external camera CCU, and the signal-processed video signal is output to the monitor 9 and output to the clamp circuit 21 of the image processing device 10.

Thus, the video signal based on the disturbance signal X is fed back to the CPU 26 via the integrator 22, the variable amplifier 23, the delay circuit 24, and the A / D converter 25. CPU26
Reads out a predetermined response table stored in the ROM 36 in advance from a predetermined operation value of the video signal based on the feedback disturbance signal X, and controls the variable resistors 37 and 38 of the variable amplifier 23 and the delay circuit 24 to adjust the variable amount. It is supposed to.

Next, the operation of the first embodiment will be described.

The image processing apparatus 10 has a plurality of processing modes of mode 1 and mode 2. In mode 1, the endoscope 3, the light source device 6, the external camera 7, the external camera CCU 8, and the image In this mode, the disturbance signal X from the disturbance generator 27 is input by closing the switch 28 in the feedback loop formed by the processing device 10, and the response to the disturbance signal X is measured.

In the mode 2, the variable amount (ie, gain) of the variable amplifier 23 and the delay amount (ie, phase) of the delay circuit in the image processing apparatus 10 are set according to the result of the mode 1, and the gain of the dimming signal Z is set. And a mode for setting the phase.

In the mode 1, the CPU 26 closes the switch 28 and outputs a trigger signal to the disturbance generator 27. The disturbance generator 27 generates a disturbance signal X, and the disturbance signal X is output to the light source device 6 via the adder 29.
A response in the case where, for example, a square wave step pulse is applied as the disturbance signal X will be described.

At the rise of the disturbance signal X, which is a step pulse, the light source device 6 operates to rapidly increase the illumination light, and operates so as to rapidly decrease the illumination light at the fall of the disturbance signal X. The video signal from the external camera CCU 8 having received the step response illumination light in mode 1 is output to the image processing device 10 and the clamp circuit 2
Enter 1 After passing through the clamp circuit 21, the video signal is input to the integration circuit 22, where it is converted into a DC potential. The converted DC potential has a DC value representing the average level of the image, and operates so as to have a low DC level when the image is dark and a high DC level when the image is bright.

In the mode 1, the variable amplifier 23 and the delay circuit 24 are initialized. The signal that has passed through the variable amplifier 23 and the delay circuit 24 in this initial setting state is the dimming signal Z, and the response is shown in FIG. FIG. 3 (a)
Represents a disturbance signal X which is a step pulse, and FIG. 3B shows a dimming signal Z which is a response thereof. And this dimming signal Z
Is converted to a digital value by the A / D converter 25, and CP
The delay time T1 with respect to the rise of the disturbance signal X, the delay time T2 with respect to the fall of the disturbance signal X, and the feedback control amount A1 with respect to the disturbance signal X in the dimming signal Z are calculated by U26 and stored in a storage unit in the CPU 26. Based on the calculated values T1, T2, and A1, the optimal amplification amount of the variable amplifier 23 and the delay amount of the delay circuit are obtained by referring to the response table of the ROM 36, and are set in the variable resistors 37 and 38.

When the mode 1 is completed, the process proceeds to a mode 2 process. In the mode 2, the disturbance signal X is applied to the feedback control loop by closing the switch 28 again under the set conditions determined in the previous mode. In mode 2, similarly to mode 1, the image processing apparatus 10 clamps and integrates the video signal having received the step response, and then passes through the newly set variable amplifier 23 and delay circuit 24, and
A new dimming signal Z ′ as shown in FIG. The dimming signal Z ′ is converted into a digital value by the A / D converter 25,
The CPU 26 calculates the delay time T1 'for the rise of the disturbance signal X in the dimming signal Z', the delay time T2 'for the fall of the disturbance signal X, and the feedback control amount A1' for the disturbance signal X, and calculates T1 ', T2' , A1 'is determined to be an optimal value.

When T1 ', T2', and A1 'are at optimal values, the mode 2 is terminated, and the settings of the variable amplifier 23 and the delay circuit 24 are held as they are. Also, T
If 1 ', T2' and A1 'are not optimal values,
The optimum amplification amount of the variable amplifier 23 and the optimum delay amount of the delay circuit are obtained by referring to the response table of the ROM 36 again using T1 ', T2', and A1 ', and are reset to the variable resistors 37 and 38.
The mode 2 processing is again performed on the reset variable amplifier 23 and delay circuit 24 in this manner, and the processing is repeated until an optimum response is obtained.

As described above, according to the first embodiment, the amount of amplification of the variable amplifier 23 and the amount of delay of the delay circuit are set so that the response characteristic thereof becomes optimum with respect to a predetermined disturbance signal. Optimum light quantity control can always be performed based on the light quantity characteristics of

Although the first embodiment has been described using a step pulse as a disturbance signal, the present invention is not limited to this. A sine wave signal is input, and the phase advance, delay and response gain of each frequency are obtained. A Bode diagram may be created by the CPU, and the variable amplifier and the delay circuit may be set based on the result.

Further, a damping factor or a natural oscillation frequency existing in the ringing portion of the dimming signal Z 'when the step pulse is applied is obtained, and the variable amplifier and the delay circuit are set so as to obtain an optimum response. Is also good.

Further, the image processing device and the light source device are configured separately, but may be integrated.

Further, an electronic endoscope may be used instead of the endoscope, the external camera head, and the external camera CCU.

The signal processing in the image processing apparatus may be performed by hardware processing or may be entirely converted into digital signals and processed by software.

Next, a second embodiment will be described. FIG.
7 to FIG. 7 relate to the second embodiment, FIG. 5 is a block diagram showing a configuration of an endoscope observation system provided with an automatic light control device,
6 is a configuration diagram showing a detailed configuration of the endoscope observation system of FIG. 5, and FIG. 7 is a characteristic diagram showing output characteristics of the solar cell panel of FIG.

Since the second embodiment is almost the same as the first embodiment, only different components will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 5, in the second embodiment, an external camera 51 is detachably attached to the eyepiece 2 of the endoscope 3 via a camera adapter 52. The camera connection optical cable 53 extends, and a camera connection optical connector 54 is provided at the base end of the camera connection optical cable 53. Further, a light source adapter 55 for connecting the camera connection optical connector 54 and the universal cord 4 of the endoscope 3 is provided. The light source adapter 55 includes a connection portion 56 connected to the connector 5 of the light source device 6. The video signal is output to the monitor 9 and the image processing device 10.

The light source adapter 55 is, as shown in FIG.
An illumination spectral material 61 is provided to irradiate the illumination light from the light source device 6 and divide the illumination light into two, and one of the illumination light divided by the illumination spectral material 61 is supplied to the light guide 31 of the endoscope, and the other is divided into two. The illumination light transmission fiber bundle 62 in the camera connection optical cable 53 is supplied. Illumination light transmission fiber bundle 62
Is transmitted to the solar cell panel 63 provided in the camera adapter 52, photoelectrically converted to generate electric power, and supplied to the external camera 51.

The video signal from the external camera 51 is converted into an optical signal by an electro-optical converter 64 provided in the camera adapter 52, and this optical signal is
The light source adapter 55 from the optical signal transmission fiber bundle 65 in 3
Is transmitted to the photoelectric conversion unit 66 provided in the. This photoelectrically converted signal is output to the monitor 9 and the image processing device as a video signal.

As the solar cell panel 63, Si, GaAs
An s, AlGaAs solar cell can be used, or a composite (having Si, GaAs, AlGaAs characteristics) high efficiency solar cell panel as shown in FIG. 7 can be used.

The other structure and operation are the same as in the first embodiment.

In the second embodiment configured as described above, in addition to the effects of the first embodiment, since the external camera 51 is supplied with power from the solar cell panel 63, AC / D
Since no C adapter is required and wiring can be simplified,
Operability of the endoscope operation unit can be improved.

[0044]

As described above, according to the automatic light control device of the present invention, the imaging signal by the illumination light controlled by the output of the phase variable means or the level variable means to which the disturbance signal is applied by the setting means. By setting the level of the DC signal generated by the DC conversion means and the variable amount of the phase variable means, a simple configuration is used based on the light amount characteristics of the light source.
There is an effect that optimal light quantity control can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an endoscope observation system including an automatic light control device according to a first embodiment.

FIG. 2 is a configuration diagram showing a detailed configuration of the endoscope observation system in FIG. 1;

FIG. 3 is a waveform diagram illustrating a light control process in mode 1 in the endoscope observation system in FIG. 2;

FIG. 4 is a waveform chart illustrating a light control process in mode 2 in the endoscope observation system in FIG. 2;

FIG. 5 is a block diagram illustrating a configuration of an endoscope observation system including an automatic light control device according to a second embodiment.

FIG. 6 is a configuration diagram showing a detailed configuration of the endoscope observation system of FIG. 5;

FIG. 7 is a characteristic diagram showing output characteristics of the solar cell panel of FIG.

FIG. 8 is a block diagram illustrating a configuration of an endoscope observation system including an automatic light control unit according to a conventional example.

[Explanation of symbols]

 Reference Signs List 3 endoscope 6 light source device 7 external camera head 8 external camera CCU 9 monitor 10 image processing device 21 clamp circuit 22 integrator 23 variable amplifier 24 delay circuit 25 A / D Converter 26 CPU 27 Disturbance generator 36 ROM

Continuation of the front page (56) References JP-A-3-118022 (JP, A) JP-A-3-56919 (JP, A) JP-A-5-49600 (JP, A) JP-A 1-297043 (JP) JP-A-1-250918 (JP, A) JP-A-63-271217 (JP, A) JP-A-1-213615 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB A61B 1/00-1/32 G02B 23/24-23/26

Claims (1)

(57) [Claims] 1. A DC conversion means for generating a DC signal according to an output signal level of an imaging means for imaging a subject, a phase variable means for changing a lead / lag of a phase of an output signal from the DC conversion means, A level varying means for varying a level of an output signal from the DC converting means; a light source for dimming based on an output of the phase varying means or the level varying means to irradiate the subject with illumination light; and generating a predetermined disturbance signal And a disturbance signal generating unit that applies the disturbance signal to an output of the phase varying unit; and an imaging signal by the illumination light that is dimmed by an output of the phase varying unit or the level varying unit to which the disturbance signal is applied. Setting means for setting a level of a DC signal generated by the DC converting means and a variable amount of the phase changing means.