JP2917292B2 - Light source light amount adjustment device for endoscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an endoscope used for medical or industrial use, particularly an electronic endoscope, which is designed to improve the color reproducibility of a subject. The present invention relates to an illumination light amount adjusting device for an endoscope that adjusts the light amount of light.

[Related Art] An endoscope is inserted into a patient's body, inside a mechanical device, or the like, and is used for inspection, observation, and the like. Are provided with an illumination window for illuminating the site to be observed and an observation window for observing the site illuminated in this way.
In the case of an electronic endoscope, the subject image incident on the observation window is converted into an electric signal and transmitted to a processor.
After a predetermined signal processing is performed by the processor, the signal is displayed on a monitor screen.

Here, in order to clearly display the subject image on the monitor screen, it is necessary to irradiate the subject with illumination light with an appropriate amount of light. When the illumination light amount is insufficient, the light amount reflected from the subject and incident on the solid-state imaging device becomes weak, and the image displayed on the monitor screen lacks sharpness. If the amount of illumination is too large and the amount of light reflected from the subject is too strong, the image quality of the image displayed on the monitor screen also deteriorates due to halation and the like.

However, even if the amount of illumination light illuminated on the subject is constant, the distance from the tip of the insertion section to the subject is different, or the reflectance of the subject is different, and so on. Is not uniform. Therefore,
When actually observing, in order to keep the illumination light amount in an appropriate state, an aperture member is interposed between the light source and the light guide that transmits the illumination light from this light source, and the distance and reflectance of the subject, etc. The illuminating light amount is adjusted by appropriately operating the aperture member in accordance with the above. Therefore,
FIG. 1 shows a conventional light source light amount adjusting device.

In the drawing, reference numeral 1 denotes a light guide, one end 1a of the light guide 1 is an incident end of illumination light, the incident end 1a faces a light source portion L in a processor, and the illumination light emitted from the light source 2 is a condenser. The light is incident on an incident end 1a of the light guide 1 via a lens 3 and a rotary color filter 4 sequentially. The other end of the light guide 1 is an emission end 1b of the illumination light, and the emission end 1b faces an illumination window provided at a distal end of the insertion section of the endoscope S. Further, an observation window provided with an objective lens 5 is provided at a distal end portion of the insertion portion.
A solid-state imaging device 6 made of D or the like is provided. The solid-state imaging device 6 is configured to be able to form an image signal by photoelectrically converting an optical image of the observation target portion.

In order to drive the solid-state imaging device 6, the solid-state imaging device 6
Is connected to a drive circuit 7. The solid-state image sensor 6 is driven based on a drive signal from the drive circuit 7, and R formed in the solid-state image sensor 6 with the rotation of the color filter 4. , G, and B color image signals are output. Each color image signal output in this manner is input to a process amplifier 9 via a video signal detection circuit 8 and is amplified at a predetermined amplification factor.
The data is sequentially stored in the memory 11 from the D converter 10. When the R, G, and B color image signals are loaded into the memory 11, these color image signals are simultaneously read out from the memory 11, and are read via the D / A converter 12 to the encoder 13.
, And output as a composite video signal. In order to input a timing signal to the drive circuit 7, the memory 11, and the encoder 13, a timing signal generation circuit 14 is provided.

The video signal detecting circuit 8 includes a reflected light amount detecting circuit 15.
The reflected light amount detection circuit 15 can detect the reflected light amount from the subject by a detection signal from the solid-state imaging device 6 or an independent reflected light amount detector. The signal of the reflected light amount detected in this way is input to the subtraction unit 16, and the difference between the detected light amount and the target light amount value from the target value setting unit 17 is calculated, whereby the actually measured light amount value and the target light amount value are calculated. And the deviation is determined. Then, based on the deviation signal, the illumination light amount from the light source unit is adjusted to an optimal value.

Here, the target light amount value set in the target value setting unit 17 may be a fixed value, or may be configured to be adjustable by a volume or the like. further,
As shown in FIG. 2, it is also possible to configure a target value setting section 17 'which can switch the target value to a plurality of stages such as three stages of high, middle and low by switching means.

The light amount in the light source unit is adjusted based on the above-described deviation signal. In order to perform the light amount adjustment, an aperture plate 18 is provided between the light source 2 and the condenser lens 3. An aperture driving circuit 19 is provided to control the driving of the aperture plate 18. The deviation signal is input to the aperture driving circuit 19 as a control operation signal, and the motor is controlled by the aperture driving circuit 19. By controlling the operation of 20, the aperture plate 18 is moved forward and backward with respect to the optical path, so that the illumination light can be adjusted to have a predetermined target light amount.

Next, a diaphragm driving mechanism of the optical path of the illumination light by the diaphragm plate 18 is illustrated in FIG. As is apparent from FIG.
Is movable along the guide groove 21 in a direction orthogonal to the optical axis of the illumination light.
The cam follower 22 is attached to the aperture plate 18 in order to displace the cam follower 22, and the cam follower 22 is in contact with a spiral cam 23. A driven gear 25 is provided on a rotating shaft 24 of the spiral cam 23.
The driven gear 25 is meshed with a driving gear 26 connected to an output shaft of the motor 20. By operating the motor 20, the helical cam 23 is rotated, and the diaphragm plate is rotated.
18 positions can be adjusted. A potentiometer 27 for detecting the rotation angle is mounted on the rotating shaft 24, and the potentiometer 27 constitutes a diaphragm position detecting means.

Thus, as described above, the diaphragm plate 18 is driven based on the amount of reflected light from the subject to adjust the amount of illumination light to a target value. Even if the illumination light incident on the
The amount of reflected light changes due to a change in the distance between the tip of the insertion section and the subject, and the amount of reflected light also changes due to the reflectance of the light in the subject and other factors. When this is expressed by an equation, the detected light amount I = J (ξ, η, d) · RG · (x) where J (ξ, η, d) is, as shown in FIG.
Illumination lens L ₁ and the solid angle on a plane from the installation position of the objective lens L ₂ and the operating means comprising an imaging plane F in a position spaced apart by a distance d (ξ, η) illumination light as viewed from the objective lens in Intensity, R is reflectance (0 ≦ R ≦ 1), G (x) is aperture position x
, The aperture gain (0 ≦ G (x) ≦ 1) is shown.

Becomes Of these, J (ξ, η, d) · R is a value that changes depending on the subject, and if J (ξ, η, d) · R = K,
I = K · G (x).

Therefore, when the value of K is varied by changing the aperture position x, by changing the aperture gain G (x), and the target value I _T to detected light intensity I is set by the target value setting unit 17 Adjust so that To make this adjustment, first,
The reflected light amount currently detected from the reflected light amount detection circuit 15,
That is, by entering the detected light intensity I to the subtraction unit 16 by subtracting from the target value I _T set by the target value setting unit 17 to this,
A deviation ΔI (= I−I _T ) of the light amount at that time is obtained. Then, the deviation signal is transmitted as a control operation signal to the aperture drive circuit 19, and the aperture drive circuit 19 operates the motor 20 with an adjustment signal amplified so as to be proportional to the control operation signal, a so-called operation (P Operation) or the motor 20 is operated by an adjustment signal proportional to the time derivative of the control operation signal.
By performing the differential operation (PD operation), the position of the aperture plate 18 is changed, and the deviation ΔI is adjusted to be zero.

[Problems to be Solved by the Invention] By moving the diaphragm plate 18, the diaphragm gain changes. However, as described above, when the diaphragm plate 18 that can be displaced in a direction perpendicular to the illumination optical path is used, Movement amount x of diaphragm plate 18
The change of the aperture gain G (x) with respect to the curve shown in FIG. FIG. 6 shows the relationship between the aperture position x and the detected light amount I when the reflectivity of the subject or the distance from the tip of the insertion section to the subject changes.

Here, when the light reflectance of the subject is high, or when the distance between the observation window and the subject is short, that is, when the value of K is large, the detected light amount is represented by a curve according to the aperture position as shown by a curve. When the value of K is small, for example, when the reflectance of the subject is low or when the subject is far from the observation window, the detected light amount changes like a curve. Become. As a result, even if the detected light amount deviation ΔI is the same, the necessary movement amount x ₁ of the diaphragm plate 18 in the state of the curve is obtained.
If, differs from the required amount of movement x ₂ stop plate 18 in the state of the curve. That is, when the detection light is strong (in the case of a curved line), the rate of change in the amount of light with respect to the moving amount of the aperture plate 18 is large. Conversely, when the detection light is weak (in the case of a curved line), The rate of change in the amount of light with respect to the amount of movement becomes smaller.

From the above, for example, by changing the observation field of view, the distance between the tip of the insertion portion and the subject changes, and when the detected light amount changes, in order to adjust the detected light amount to a predetermined value, As shown by the curve, when the amount of reflected light from the subject is large, for example, when the tip of the insertion portion is close to the subject, the aperture gain for the movement of the aperture plate 18 becomes excessive, and hunting occurs near the target value. As a result, the operation of the diaphragm plate 18 becomes unstable. Also, as shown by the curve, when the amount of reflected light from the subject is small, for example, when the distal end of the insertion section is moved away from the subject, the aperture gain with respect to the movement of the aperture plate 18 becomes too small, and the response of the aperture plate 18 becomes small. In addition to the poor performance, friction and gear 2
Due to the backlash of 4, 25, etc., there is a difficulty in controllability of the diaphragm mechanism, for example, the stopping accuracy of the diaphragm plate 18 is deteriorated or it is impossible to reach the target value. In particular, when the configuration is such that the target light quantity is variable, the aperture gain changes according to the target set value, so that the controllability of the aperture mechanism further deteriorates according to the target set value.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to quickly and surely adjust a target light quantity when a detected light quantity changes. An object of the present invention is to provide an endoscope light source light amount adjusting device.

Means for Solving the Problems In order to achieve the above-described object, the present invention provides an optical path interposed in an optical path from an illumination light source in an endoscope, and an opening area of the optical path changes almost exponentially depending on the position. An aperture member, aperture control means for controlling the operation of the aperture member, target value setting means for setting a target illumination light quantity, and reflected light quantity detection means for detecting the quantity of reflected light from the subject; The amount of reflected light detected by the reflected light amount detector is compared with the amount of illumination light targeted by the target value setting unit, and a deviation signal is transmitted to the aperture control unit as a control operation signal to control the operation of the aperture member. An endoscope light source light quantity adjusting device, wherein a target light quantity by the target value setting means is variable, and when the target light quantity is changed, a deviation signal sampled at each target light quantity is calculated. In contrast, a control signal corrected by a predetermined correction signal is provided to the aperture control means.

[Operation] By adopting such a configuration, when the optical path stop member is moved, the stop gain near the target light amount does not change depending on the position or state of the subject and becomes substantially constant. . Therefore, when a control operation signal based on the deviation between the actually measured light amount and the target light amount is given to diaphragm control means for controlling the operation of the optical path diaphragm member, when controlling the operation of the optical path diaphragm member, an amplification factor for the control operation signal is given. Is set so as to be stable in the vicinity of the target light amount, the controllability of the operation of the optical path stop member is improved, and hunting, an operation delay, and other inconveniences can be reliably prevented. .

The target light amount can be changed. In this case, however, the aperture gain changes in accordance with the target set value, which deteriorates the controllability of the aperture mechanism. In order to prevent this, a predetermined correction signal may be added to the deviation signal according to each target value. Here, since the aperture gain changes almost exponentially, it is most preferable that the correction signal be inversely proportional to the target set value.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In the present embodiment, the same or equivalent members as the constituent members shown in the above-described related art are denoted by the same reference numerals, and description thereof will be omitted.

Thus, in the present embodiment, similarly to the above-described prior art, for example, the reflected light amount detecting circuit 15 detects the reflected light amount from the subject, and the detected light amount and the target light amount set in the target value setting unit 17 are compared. Is subtracted by the subtractor 16,
A deviation between them is obtained, and the deviation signal is input to the aperture driving circuit 19 as a control operation signal, thereby making the aperture amount variable.

However, a feature of the present invention is that, unlike the conventional diaphragm plate 18, a flexible belt-shaped diaphragm strip 30 is used as the light amount diaphragm member, as shown in FIG. A plurality of rows of a plurality of circular aperture openings 31 are formed in the aperture strip 30 in the longitudinal direction, and the apertures 31 of each row have a diameter that varies from left to right in the drawing. Is getting bigger. The opening area of each of the aperture openings 31 increases substantially exponentially from one side to the other side in the longitudinal direction.
Then, as shown in FIG. 8, the stop strip 30 is wound around winding shafts 33a and 33b connected to upper and lower motors 32a and 32b at a position between the light source 2 and the condenser lens 3. Is provided.

Accordingly, by driving the motors 32a and 32b, the aperture area of the aperture strip 31 in the aperture strip 31 facing the optical path from the light source 2 changes, and as shown in FIG. It changes almost exponentially from the fully closed state to the fully open state. Therefore, assuming that the aperture characteristic of the aperture strip 30 is G (x), G (x) = exp (−
αx) (where x> 0, and α is a constant greater than 0). Therefore, the rate of change of the reflected light amount I with respect to the aperture position x is dI / dx = K · dG / dx = −α · K · exp (−αx) = − αI. Becomes As is apparent from this equation, the element K, ie, J (ξ, η, d) · R, which changes depending on the position or state of the subject can be removed from the deviation of the light amount due to the aperture position, and the subject can be removed. Even if the reflectance, the distance, and the like change, the change in the amount of light depending on the aperture position becomes substantially constant.

Therefore, in order to perform the P operation or the PD operation based on the control operation signal input to the aperture drive circuit 19, the amplification factor of the adjustment signal output from the aperture drive circuit 19 with respect to the control operation signal, that is, the proportional gain Is set so that the motors 32a and 32b for driving the aperture strip 30 in the vicinity of the above-mentioned target light quantity are stably operated, so that the operation controllability of the light quantity aperture mechanism is remarkably improved, and hunting and response delay are caused. The light amount can be adjusted smoothly, reliably, and quickly without causing any problems.

By the way, when the target light amount set by the target setting means is fixed, the amplification factor between the control operation signal and the adjustment signal may be kept constant, but the target light amount is changed. in case, as shown in FIG. 11, at the when the target light quantity is time and I _T2 of I _T1, the change amount of the throttle position with respect to the amount of light deviation in the target value near the
x ₁ , x _{2 and} so on. Therefore, the aperture strip 30
In order to further stabilize the operation and improve the controllability, it is preferable to perform a predetermined correction for each target value.

To this end, as shown in FIG. 11, an attenuating circuit 40 including a voltage-controlled attenuator, a D / A converter, and the like is interposed on the output side of the attenuator 16, and the amount of light detected and the target The deviation ΔI from the light amount is corrected by attenuating the signal voltage x corresponding to the stop position corresponding to the target light amount in the aperture gain G (x), and the control operation signal of ΔI / x is corrected. Is input.

As a result, when the target light quantity is low, the amplification factor for the control operation signal is increased, and when the target light quantity is high, the amplification factor for the control operation signal is corrected to be small. In addition, since this correction signal is inversely proportional to the target light amount, it is extremely effective for correcting the aperture gain G (x) that changes exponentially. As a result, the throttle strip 3 of the motors 32a and 32b is set according to the set target value.
There is no possibility that the driving operation of 0 becomes unstable.

In addition, the target set value is high, middle, low, etc.
When using the target value setting unit 17 'which can be switched to a plurality of stages, the correction value for the target light amount is, as shown in FIG. 12, a deviation signal output from the subtractor 16 as shown in FIG. Switching means 41 for providing an attenuation signal in inverse proportion to each target value may be used, and the switching means 41 may be set to be switched in conjunction with the switching of the target setting unit 17 '.

In the above-described embodiment, the optical path stop member is configured so that a plurality of rows of circular openings are provided in the band-shaped member, and the diameter of the openings in each row is changed from one side to the other side. In short, if the opening area changes substantially exponentially in the longitudinal direction of the strip, it can be formed by a slit or the like directed in the longitudinal direction. Also, the thirteenth
As shown in the figure, a disk-shaped aperture member 36 is used, and a large number of apertures 37 whose aperture area changes almost exponentially in the rotational direction are provided on the outer peripheral side of the aperture member 36, The aperture member 36 may be rotated using a single motor. It is most preferable that the change of the aperture area by the stop strips 30, 35 or the stop member 36 constituting these optical path stop members be changed exponentially, but it is substantially exponential. It should be able to change, for example, even if there is an error of about ± 11%,
There is no problem in practical use.

[Effects of the Invention] As described above, the present invention uses an optical path stop member in which the stop aperture changes substantially exponentially, and uses stop control means for controlling the movement of the stop member; A target value setting means for setting and a reflected light amount detecting means for detecting the reflected light amount from the subject are provided, and the detected light amount by the reflected light amount detecting means is compared with the target illumination light amount by the target value setting means. The deviation signal is transmitted to the aperture control means as a control operation signal to control the operation of the aperture member. Therefore, when the light amount aperture member is moved, the aperture gain near the target light amount becomes smaller than the object. It is almost constant without being changed by the position or state of the target, and the target light quantity by the target value setting means is made variable. When this target light quantity is changed, the target light quantity is changed at each target light quantity. Since a control signal corrected by a predetermined correction signal with respect to the sampled deviation signal is provided to the aperture control means, even if the target set value is changed, the aperture gain does not substantially change, and the actual measurement is performed. When controlling the operation of the optical path stop member based on the deviation between the position and the target light amount, the controllability of the operation of the optical path stop member is improved, and hunting, an operation delay, and the like are reliably prevented. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a conventional light source light amount adjusting device, FIG. 2 is an explanatory diagram showing another example of target value setting means, FIG. 3 is an explanatory diagram showing an optical arrangement relationship, FIG. 4 is an explanatory view of a configuration of an illumination light diaphragm mechanism, FIG. 5 is a diaphragm characteristic diagram of a diaphragm member, FIG. 6 is a diaphragm position-reflection light amount characteristic diagram, and FIGS. FIG. 7 is an explanatory view of a configuration of an optical path aperture member, FIG. 8 is an explanatory view of a configuration of an aperture mechanism, FIG. 9 is an aperture characteristic diagram of the aperture member, and FIG. FIG. 11 is a diagram illustrating the configuration of a control operation signal forming circuit showing the second and third embodiments of the present invention, and FIG. 13 is a fourth embodiment of the present invention. FIG. 4 is an explanatory diagram of a configuration of an optical path stop member showing the above. 1: light guide, 2: light source, 6: solid-state image sensor, 15: reflected light amount detection circuit, 17, 17 ': target value setting section, 18: aperture plate, 19:
Aperture drive circuit, 27: Potentiometer, 30: Aperture strip, 31:
Aperture aperture, 32a, 32b: motor, 36: aperture member, 37: aperture, 4
0: attenuation circuit, 41: switching means.

Claims (2)

(57) [Claims] 1. An optical path stop member interposed in an optical path from an illumination light source in an endoscope and having an opening area that changes substantially exponentially according to the position thereof, stop control means for controlling the operation of the stop member, There is a target value setting means for setting a target illumination light quantity, and a reflected light quantity detecting means for detecting a reflected light quantity from a subject, and a detected light quantity by the reflected light quantity detecting means and a target by the target value setting means. In comparison with the illumination light amount, the deviation signal is transmitted to the aperture control means as a control operation signal to control the operation of the aperture member. When the light amount is made variable and the target light amount is changed, a control signal obtained by correcting a deviation signal sampled at each target light amount with a predetermined correction signal is used as the aperture control. The endoscope light source light quantity adjusting device, characterized in that a structure to be applied to stage. 2. An endoscope light source light amount adjustment according to claim 1, wherein a correction signal inversely proportional to each target value by said target value setting means is given to said deviation signal. apparatus.