JP3257638B2 - Light source device for endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for an endoscope for irradiating light to a subject which is an object to be photographed and observed by an endoscope.

[0002]

2. Description of the Related Art Conventionally, as a light source device for an endoscope for irradiating an object which is an object to be photographed and observed by an endoscope, one of a video signal and an EE signal is used for dimming the irradiation light. There is one that performs dimming control for adjusting the amount of irradiation light based on one of the video signal and the EE signal (described in Japanese Utility Model Publication No. 51-16286). The EE signal is a DC signal that is proportional to the brightness of the subject.

[0003] Among these endoscope light source devices, an endoscope light source device that performs dimming control based on a video signal includes a first-stage amplifier 1 that amplifies an input video signal, as shown in FIG. . The video signal amplified by the first-stage amplifier 1 is supplied to a detection / smoothing circuit 2, and the detection / smoothing circuit 2 converts the video signal input thereto into a DC signal.

[0004] The DC signal from the detection / smoothing circuit 2 is supplied to a comparator 3, which compares the DC signal from the detection / smoothing circuit 2 with a reference voltage from a reference power supply 4, and the result of the comparison. And outputs an aperture control signal corresponding to. An aperture control signal output from the comparator 3 is supplied to a drive circuit 5, and the drive circuit 5 drives the aperture actuator 6 based on the aperture control signal so as to match an aperture value corresponding to a reference voltage from the reference power supply 4. .

On the other hand, in an endoscope light source device that performs dimming control based on the EE signal, the EE signal is a DC signal that is already proportional to the brightness of the subject.
An aperture control signal corresponding to a result of the comparison is generated by comparing the signal with a reference voltage, and an aperture actuator is driven based on the aperture control signal so as to match an aperture value corresponding to the reference voltage.

In the former light source device for an endoscope, the standard of a video signal used for dimming control is NTSC system, PA
Since it is unified by the L system or the like, versatility can be given by adapting to the standard of the input video signal. However, the DC signal from the detection / smoothing circuit 2 is proportional to the amount of energy in one field. Therefore, as the screen size, that is, the size of the visual field on the screen decreases, the black level region increases and the amount of energy in one field increases. Becomes smaller. In other words, the level of the DC signal decreases as the amount of energy in one field decreases, and the illuminance is lower than the actual illuminance level, that is, a "dark" signal.

When the DC signal, which is a "dark" signal, is input to the comparator 3, the comparator 3 outputs a control signal for instructing opening of the aperture to the aperture actuator 6 so as to increase the amount of light. May rise, causing saturation and overexposure. Therefore, it is difficult to obtain accurate brightness information from a video signal, and dimming control cannot be performed properly.

On the other hand, in the latter light source device for an endoscope, since the EE signal used for dimming control is a DC signal proportional to the brightness of the subject, the EE signal is independent of the size of the screen. The brightness information of the subject can be accurately obtained from the DC signal, and the dimming control can be appropriately performed.

[0009] However, since the standard for the EE signal is not standardized, the E-signal used for a certain device is not used.
The E signal and the EE signal used in other devices may be different from each other, and it is difficult to provide versatility.

[0010]

As described above, in an endoscope light source device using a video signal for dimming control, it is difficult to obtain accurate brightness information from the video signal.
Dimming control cannot be performed properly.

It is difficult for the endoscope light source device using the EE signal for dimming control to have versatility.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an endoscope light source device that can appropriately control dimming without impairing versatility.

[0013]

According to the present invention, there is provided an image pickup apparatus for outputting an image pickup signal corresponding to a subject image captured by an endoscope, and performing predetermined signal processing on the image pickup signal from the image pickup apparatus. A camera control unit that generates and outputs a brightness signal indicating a brightness of the subject image and a predetermined video signal, and is used for an endoscope apparatus having an endoscope that irradiates the subject with illumination light. in the light source device, a first input means for inputting the brightness signal generated by the camera control unit, a second input means for inputting the image signal generated by the camera control unit, the second Video signal detection means for detecting the video signal input by the input means, and the first and second video signal detection means.
Input state determining means for determining the input state of the input means,
A signal selection unit that selects a brightness signal input by the first input unit and a detection signal detected by the video signal detection unit based on a determination result of the input state determination unit; Dimming control means for dimming the illumination light based on a signal.

[0014]

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

FIG. 1 is a block diagram showing an endoscope apparatus using an embodiment of the endoscope light source device of the present invention, and FIG. 2 is a block diagram showing a dimming circuit of the endoscope light source apparatus shown in FIG. FIG.

As shown in FIG. 1, the endoscope apparatus 11 includes an endoscope 12, a camera head 14 (imaging device) mounted on an eyepiece 13 of the endoscope 12, and a camera head 14. Camera control unit (hereinafter referred to as CCU) 15 for performing predetermined processing on the video signal (imaging signal)
And a light source device 16 that supplies illumination light to the endoscope 12.

The endoscope 12 has an elongated insertion portion 17 inserted into a body cavity or the like, and a light guide (not shown) for transmitting illumination light is inserted through the insertion portion 17. The light guide is led out through a light guide cable 18, and the light guide cable 18 is connected to the light source device 16 by a connector 19 provided at an end thereof.

The CCU 15 generates a video signal (video signal) corresponding to an image captured by the endoscope 12, and generates an EE signal ( EE signal ) composed of a DC signal proportional to the brightness of a subject in the field of view of the endoscope 12. Brightness signal) .

The light source device 16 includes a lamp 20 and a lamp 2.
An aperture actuator 21 for adjusting the amount of light traveling from 0 to the light guide cable 18. The aperture actuator 21 regulates the amount of light transmitted through the lamp 20 in accordance with the amount of aperture. Controlled by the circuit 22.

The dimming circuit 22 includes two terminals 23 and 24. A video signal from the CCU 15 is supplied to a terminal 23 via a video signal cable 25, and a C
An EE signal from the CU 15 is supplied via an EE signal cable 26.

The video signal supplied from the terminal 23 is applied to a first-stage video signal amplifier 27 and signal discriminating means 30, as shown in FIG. 2, and the first-stage video signal amplifier 27 amplifies the video signal. The video signal amplified by the first-stage video amplifier 27 is supplied to a detection / smoothing circuit 28, which converts the video signal into a DC signal. The DC signal from the detection / smoothing circuit 28 is supplied to a switch 29.

The signal discriminating means 30 outputs the video signal to the terminal 2
3 is detected, and a control signal for instructing the switching operation of the switch 29 is generated based on the result of the detection.

On the other hand, the EE signal supplied via the terminal 24 is supplied to the first-stage EE signal amplifier 31. The first-stage EE signal amplifier 31 amplifies the EE signal, and the EE signal amplified by the first-stage EE signal amplifier 31 is provided to a low-pass filter (hereinafter, referred to as LPF) 32. LPF32
Removes a high frequency component such as a noise component included in the EE signal, and outputs an EE signal from which the high frequency component has been removed. The EE signal from the LPF 32 is provided to the switch 29.

The switch 29 has an input terminal 29a to which a DC signal from the detection / smoothing circuit 28 is input, and an LPF 32
And an input terminal 29b for receiving the EE signal from the input terminal 29b. The switch 29 switches the input terminals 29a and 29b based on the detection signal from the signal determination unit 30. When it is determined that the video signal is input, the switch 2
Reference numeral 9 selects an input terminal 29a based on a control signal from the signal discriminating means 30, and a video signal is output from an output terminal 29c of the switch 29. If it is determined that there is no input of the video signal, the switch 29 selects the input terminal 29b based on the control signal, and the output terminal 29c of the switch 29.
Outputs an EE signal.

The output signal from the switch 29 is supplied to a comparator 33
Given to. The comparator 33 compares the output signal from the switch 29 with the voltage generated from the reference power supply 34, and generates a control signal for controlling the diaphragm amount of the diaphragm actuator 21 from the result of the comparison. The reference power supply 34 generates a reference voltage that can be varied within a predetermined range.

Next, the operation of the light source device will be described.

When observing or imaging a predetermined body cavity with the endoscope 12, the lamp 20 of the light source device 16 is driven,
Light from the lamp 20 travels toward the light guide cable 18 via the aperture actuator 21. The light guide cable 18 transmits light to a light guide in the endoscope 12, and the light transmitted to the light guide is emitted toward the subject from the tip of the insertion section 17. The CCU 15 generates a video signal corresponding to an image captured by the camera head 14 via the endoscope 12 and an EE signal indicating the brightness of the subject. The video signal is supplied from the video signal cable 25 and the terminal 23.
The EE signal is supplied to the dimming circuit 22 through the EE signal cable 26 and the terminal 24.

The video signal supplied to the terminal 23 is supplied to the first stage video signal amplifier 27 and the signal discriminating means 30. The signal discriminating means 30 detects that a video signal is input, and outputs a control signal corresponding to a result of the detection to the switch 29. The switch 29 selects the input terminal 29a based on the control signal. With the selection of the input terminal 29 a of the switch 29, the DC signal converted from the video signal via the first-stage video signal signal amplifier 27 and the detection / smoothing circuit 28 is output to the comparator 33 from the output terminal 29 c of the switch 29. The comparator 33 compares the DC signal from the switch 29 with the reference voltage of the reference power supply 34, and outputs a corresponding aperture control signal based on the result of the comparison.

The drive circuit 35 controls the aperture amount of the aperture actuator 21 based on the aperture control signal from the comparator 33, and the transmitted light amount from the lamp 20 is regulated so that the illuminance of the subject becomes appropriate.

When the video signal is not supplied due to the disconnection of the video signal cable 25 and the EE signal is supplied, the signal discriminating means 30 detects that there is no input of the video signal, and the control corresponding to the result of this detection is performed. The signal is output to the switch 29.

The switch 29 selects the input terminal 29b based on a control signal from the signal discriminating means 30. When the input terminal 29b of the switch 29 is selected, an EE signal is supplied to the comparator 33 from the output terminal 29c of the switch 29c.
The comparator 33 compares the EE signal with a reference voltage from the reference power supply 34, and outputs a signal indicating the result of the comparison to the drive circuit 35. The drive circuit 35 controls the aperture amount of the aperture actuator 21 based on a signal from the comparator 33.

When the EE signal is not supplied due to the disconnection of the EE signal cable 26 and the video signal is supplied,
The signal discriminating means 30 detects that a video signal is input, and outputs a control signal corresponding to the result of the detection to the switch 29.
Output to

Since the switch 29 selects the input terminal 29a based on the control signal from the signal discriminating means 30, the aperture of the aperture actuator 21 is controlled based on the video signal.

Therefore, when there is a video signal input, dimming is performed based on the video signal. When there is no video signal input and there is an EE signal input, dimming is performed based on the EE signal, and the dimming control is performed. Is performed properly without interruption.

That is, in this embodiment, the dimming control using the signal selected from these signals is performed while monitoring the output state of the video signal and the EE signal.
Dimming control can be properly continued without interruption of dimming control due to interruption of one signal supply.

In addition to the versatile video signal,
The E signal can be used for dimming control, and versatility can be improved. Further, when a video signal and an EE signal are supplied simultaneously, an EE having accurate brightness information is provided.
By selecting a signal, more accurate and appropriate dimming control can be performed.

Although this embodiment is used in the endoscope apparatus 11 provided with the camera head 14, FIG.
As shown in the figure, the camera head and the CCU are integrated into T
It can also be used for the endoscope apparatus 11 having the V camera 81.

Next, another light source device for an endoscope will be described with reference to the drawings. 4 is a block diagram showing another embodiment of the endoscope light source device of the present invention, FIG. 5 is a block diagram showing a screen size detection circuit of the dimming circuit of FIG. 4, and FIG.
7 for explaining the operation of the screen size detection circuit of FIG.
5 is a block diagram showing an EE detection signal detection circuit of the dimming circuit of FIG.

As shown in FIG. 4, the light source device for an endoscope
It has a diaphragm actuator 21 for regulating the amount of light from a lamp (not shown) and a dimming circuit 36 for controlling the diaphragm amount of the diaphragm actuator 21.

The dimming circuit 36 determines whether or not a video signal is captured at the terminal 23 and determines whether or not an EE signal is captured at the terminal 24.
Having.

The signal discriminating means 37 comprises a video signal detecting circuit 38 for detecting whether or not a video signal is taken in the terminal 23, and a screen size detecting circuit 39 for detecting a screen size from the video signal taken in the terminal 23. And terminal 2
4 to detect whether or not the EE signal is taken in
And a signal detection circuit 40.

As shown in FIG. 5, the screen size detection circuit 39 has a trap filter 41 for removing a burst signal included in the video signal. Trap filter 4
The video signal output from 1 is supplied to each of the comparators 42 and 43.

The comparator 42 compares the video signal input thereto with the reference voltage from the reference power supply 44 and extracts a signal indicating a period during which the video signal is at a level higher than the reference voltage. The reference voltage from the reference power supply 44 is set to a video signal detection level substantially equal to the setup level (pedestal level) as shown in FIG.

A signal indicating a period during which the video signal extracted by the comparator 42 is at a level higher than the reference voltage is given to a counter 45, and the counter 45 is based on the clock signal and the video signal is at a level higher than the reference voltage. The duration of the signal indicating the period is measured, and a signal indicating the measurement time A (shown in FIG. 6) is output.

On the other hand, the comparator 43 compares the video signal input thereto with the reference voltage from the reference power supply 46, and extracts a signal indicating a period during which the video signal is at a level higher than the reference voltage. The reference voltage from the reference power supply 46 is
As shown in FIG. 6, the level is set to a synchronization signal detection level at which a horizontal synchronization signal can be detected.

A signal indicating a period during which the video signal extracted by the comparator 43 is at a level higher than this reference voltage is given to a counter 47, and the counter 47 has a video signal at a level higher than this reference voltage based on a clock signal. The duration of the signal indicating the period is measured, and a signal indicating the measurement time B (shown in FIG. 6) is output.

Signal from Counter 45 and Counter 4
The signal from 7 is supplied to the operation / judgment circuit 48. The calculation / determination circuit 48 calculates a ratio between the measurement time A and the measurement time B, and generates a screen size detection signal corresponding to the screen size from the value of the ratio. In other words, calculating the value of the ratio between the measurement time A and the measurement time B means calculating the screen size.

As shown in FIG. 7, the EE signal detection circuit 40 has an amplifier 50 for amplifying the EE signal received from the input terminal 49. The EE signal amplified by the amplifier 50 is provided to the comparator 51. The comparator 51 compares the EE signal input thereto with the reference voltage from the reference power supply 52, and outputs a detection signal indicating whether or not the EE signal is detected based on the result of the comparison. The reference voltage from the reference power supply 52 is set to a value substantially equal to 0V.

A detection signal from the video signal detection circuit 38;
The screen size detection signal from the screen size detection circuit 39 and the detection signal from the EE signal detection circuit 40 are
3 given. The determination circuit 53 generates a control signal for controlling the switching operation of the switch 29 based on the content indicated by each detection signal input thereto.

When the detection signal from the video signal detection circuit 38 indicates that a video signal has been input and the screen size detection signal from the screen size detection circuit indicates that the screen size is larger than the specified size, the switch 29 is connected to an input terminal. 29a
Is generated.

When the screen size detection signal from the screen size detection circuit 39 indicates that the screen size is smaller than the specified size, and when the detection signal from the EE signal detection circuit 40 indicates that an EE signal has been input, the input to the switch 29 is performed. Terminal 29b
Is generated.

When the detection signal from the video signal detection circuit 38 indicates that no video signal is input and the detection signal from the EE signal detection circuit 40 indicates that an EE signal is input, the switch 2
9, a control signal for instructing an operation of selecting the input terminal 29b is generated.

Next, the operation of the endoscope light source device will be described.

When the imaging of the subject in the body cavity is started, T
The V camera (not shown) outputs a video signal and an EE signal, and the video signal and the EE signal are taken into the dimming circuit 36.

When the screen size becomes smaller than a predetermined size during imaging of the subject in the body cavity, the screen size detection circuit 39 detects a screen size corresponding to the screen size based on the video signal input thereto. Output a signal. The screen size detection signal is provided to the determination circuit 53. The determination circuit 53 determines that the screen size is smaller than the specified size based on the screen size indicated by the screen size detection signal, and generates a control signal instructing the switch 29 to select the input terminal 29b. The switch 29 outputs an EE signal taken into the input terminal 29b from the output terminal 29c based on the control signal, and the EE signal is given to the comparator 33. The comparator 33 compares the EE signal with a reference voltage from the reference power supply 34 and outputs a signal indicating the result of the comparison to the driving circuit 3.
5 is output. The drive circuit 35 controls the aperture amount of the aperture actuator 21 based on a signal from the comparator 33.

Therefore, by the dimming control using the EE signal, it is possible to prevent the occurrence of overexposure due to the saturation of the video signal due to the reduction in the screen size.

In this embodiment, the detection result of the screen size is used to prevent the occurrence of overexposure, but a circuit for detecting the saturation of the video signal may be used instead of the screen size detection circuit. This method of detecting the saturation of the video signal is performed by comparing the video signal with a reference level (for example, 120 IRE) set near 100 IRE. When the video signal exceeds the reference level, it is determined that the video signal is saturated. The setting of the reference level is based on the fact that the guaranteed range of the current video signal is less than 100 IRE.

Next, another light source device for an endoscope will be described with reference to the drawings. FIG. 8 is a block diagram showing still another embodiment of the endoscope light source device of the present invention.

The endoscope light source device, as shown in FIG.
The diaphragm actuator 21 for regulating the amount of light from a lamp (not shown) and a dimming circuit 54 for controlling the diaphragm amount of the diaphragm actuator 21 are provided.

The dimming circuit 54 determines whether or not a video signal is captured in the terminal 23, and determines whether or not the EE signal is captured in the terminal 24.
Having.

The signal discriminating means 55 includes a video signal detecting circuit 38 for detecting whether or not a video signal is taken into the terminal 23, and a screen size detecting circuit 39 for detecting a screen size from the video signal taken into the terminal 23. And terminal 2
4 to detect whether or not the EE signal is taken in
And a signal detection circuit 40.

A detection signal from the video signal detection circuit 38,
The screen size detection signal from the screen size detection circuit 39 and the detection signal from the EE signal detection circuit 40 are
3 given. The determination circuit 53 performs a switching operation of the switch 29 and a switching operation of the switch 56 for selecting a reference voltage from the reference power sources 56 and 57 input to the comparator 33 based on the contents indicated by the respective detection signals input thereto. Generate a control signal for controlling. The reference voltage from the reference power supply 57 is a reference voltage for the video signal, and this reference voltage is applied to the input terminal 56a of the switch 56. The reference voltage from the reference power supply 58 is a reference voltage for the EE signal, and this reference voltage is applied to the input terminal 56b of the switch 56.

When the detection signal from the video signal detection circuit 38 indicates that a video signal has been input and the screen size detection signal from the screen size detection circuit indicates that the screen size is larger than the specified size, the switch 29 is connected to an input terminal. 29a
Is selected and the switch 56 is connected to the input terminal 5
A control signal instructing the operation of selecting 6a is generated, the video signal is compared with the reference voltage from the reference power supply 57, and the aperture control corresponding to the result of the comparison is performed.

When the screen size detection signal from the screen size detection circuit 39 indicates that the screen size is larger than the specified size, and when the detection signal from the EE signal detection circuit 40 indicates that an EE signal has been input, the input to the switch 29 is performed. Terminal 29b
Is selected and the switch 56 is connected to the input terminal 5
6b is generated, and a control signal instructing the operation of selecting
The E signal is compared with a reference voltage from the reference power supply 58, and aperture control corresponding to the result of the comparison is performed.

When the detection signal from the video signal detection circuit 38 indicates that no video signal has been input and the detection signal from the EE signal detection circuit 40 indicates that an EE signal has been input, the switch 2
9, a control signal instructing an operation of selecting the input terminal 29b to the input terminal 29b and an instruction of an operation of selecting the input terminal 56b to the switch 56 are generated, and the EE signal is compared with a reference voltage from the reference power supply 58. Aperture control corresponding to the result of the comparison is performed.

Although the video signal and the EE signal are used for dimming control in this embodiment, other signals indicating the brightness of the subject may be used instead.

[0067]

As described above, according to the light source device for an endoscope of the present invention, dimming control can be properly performed without impairing versatility.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an endoscope apparatus using an endoscope light source device of the present invention.

FIG. 2 is a block diagram showing a dimming circuit of the endoscope light source device of FIG.

FIG. 3 is a diagram showing a configuration of another endoscope apparatus to which the endoscope light source device of FIG. 1 is applied.

FIG. 4 is a block diagram showing a dimming circuit used in another embodiment of the endoscope light source device of the present invention.

FIG. 5 is a block diagram illustrating a screen size detection circuit of the dimming circuit of FIG. 4;

FIG. 6 is a diagram for explaining the operation of the screen size detection circuit in FIG. 5;

FIG. 7 is a block diagram illustrating an EE detection signal detection circuit of the dimming circuit of FIG. 4;

FIG. 8 is a block diagram showing a dimming circuit used in still another embodiment of the endoscope light source device of the present invention.

FIG. 9 is a block diagram showing a dimming circuit of a conventional endoscope light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Endoscope apparatus 12 Endoscope 14 Camera head 15 CCU 16 Light source device for endoscope 20 Lamp 21 Aperture actuator 22, 36, 54 Light control circuit 30, 37, 55 Signal discriminating means 35 Drive circuit 38 Video signal detection circuit 39 Screen size detection circuit 40 EE signal detection circuit 53 Judgment circuit

Claims (1)

(57) [Claims] 1. An imaging device that outputs an imaging signal corresponding to a subject image captured by an endoscope, and performs predetermined signal processing on the imaging signal from the imaging device to indicate brightness of the subject image. A camera control unit that generates and outputs a brightness signal and a predetermined video signal; and an endoscope light source device that irradiates the subject with illumination light, the camera control unit being used in an endoscope device having the camera control unit. in a first input means for inputting the brightness signal produced, a second input means for inputting the video signal generated by the camera control unit, said image inputted by said second input means Video signal detecting means for detecting a signal, input state determining means for determining an input state of the first and second input means, and a determination result of the input state determining means. Signal selection means for selecting a brightness signal input by the first input means and a detection signal detected by the video signal detection means; and dimming control of the illumination light based on the signal selected by the signal selection means. A light control device for an endoscope, comprising: dimming control means.