JP4142363B2 - Autofocus electronic endoscope - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an autofocus electronic endoscope whose focal length is automatically adjusted in conjunction with magnified observation.
[0002]
[Prior art and its problems]
In recent years, various electronic endoscopes having an autofocus (AF) function in which the position of the focus adjustment lens is automatically adjusted according to the position of the distal end of the insertion portion of the endoscope have been proposed. In such an AF electronic endoscope, it is difficult to detect the optimum focus position when water or air is supplied within the observation range. Therefore, the air / water supply operation is temporarily suspended during the AF operation. However, when the AF operation time is long, the drive time of the drive motor that moves the focus adjustment lens is also long, and there is a problem that the temperature in the distal end of the insertion portion rises due to heat generated from the drive motor. This temperature rise not only deteriorates the drive characteristics of the drive motor, but also affects the CCD arranged in the vicinity of the drive motor, leading to an increase in dark current and white spot damage, and a decrease in the CCD output voltage. Endoscopic image quality is degraded.
[0003]
OBJECT OF THE INVENTION
An object of the present invention is to obtain an autofocus electronic endoscope capable of suppressing a temperature rise in the distal end of an insertion portion.
[0004]
SUMMARY OF THE INVENTION
An autofocus electronic endoscope according to the present invention includes a focus adjustment lens that is movable along the optical axis of an objective optical system provided at the distal end of the insertion section; the focus adjustment lens provided at the distal end of the insertion section has a wide angle of view. A drive motor that moves between a normal observation position and an enlarged observation position with a narrow angle of view; a focus detection means that detects the focus state of the observation object; and a drive motor that is driven based on the focus state detected by the focus detection means; Motor control means for adjusting the position of the focus adjustment lens; AF switching for switching between an AF mode for adjusting the position of the focus adjustment lens by operating the motor control means and a fixed focus mode for fixing the focus adjustment lens at the normal observation position member; and limiting means for limiting the AF operation time by the motor control unit; provided with, this restriction means, AF mode is set is the AF switching member When a predetermined timer time has elapsed since the, it is characterized by stopping the AF operation by the motor control unit.
[0005]
According to the above configuration, driving of the drive motor can be stopped before the temperature in the distal end of the insertion portion rises excessively due to heat generated from the drive motor. As a result, the operation of the CCD arranged in the vicinity of the drive motor is not adversely affected, and observation and inspection can be performed with a good quality endoscope image.
[0007]
In addition, when the limiting unit includes a temperature sensor that detects the ambient temperature of the drive motor, it is preferable that the AF operation time by the motor control unit is changed according to the ambient temperature detected by the temperature sensor. Alternatively, it is preferable to stop the AF operation by the motor control means when the ambient temperature detected by the temperature sensor reaches the first temperature, and the ambient temperature becomes lower than the second temperature lower than the first temperature. It is also possible to stop the AF operation by the motor control means.
[0008]
When the AF control is stopped by the limiting unit, the motor control unit preferably stops the drive motor after returning the focus adjustment lens to the normal observation position. That is, the fixed focus mode is set while the AF operation is stopped.
[0009]
The above autofocus electronic endoscope can be provided with a TV monitor that displays AF operation information indicating whether or not the AF operation is being performed together with the endoscope image.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing the overall configuration of an autofocus (AF) electronic endoscope 1 to which the present invention is applied. The AF electronic endoscope 1 includes an electronic endoscope main body 10 that captures an image of a body cavity of a subject, a processor 20 that processes an endoscopic image captured by the electronic endoscope main body 10, and a processing performed by the processor 20. And a TV monitor 40 for displaying an endoscopic image.
[0011]
The electronic endoscope main body 10 includes a flexible internal insertion portion 11, a grip operation portion 12 held by an operator, a universal tube 13 extended from the grip operation portion 12, and a distal end of the universal tube 13. It has the connector part 14 which was provided and can be attached or detached to the processor 20.
[0012]
As shown in FIG. 2, an objective lens 15 and a first illumination lens 16 are disposed at the insertion portion distal end 11 a of the in-vivo insertion portion 11, and move behind the objective lens 15 along the optical axis of the objective lens 15. A possible focusing lens 17 and CCD 18 are arranged. The image formed by the objective lens 15 and the focus adjustment lens 17 is converted into an electronic image by the CCD 18 and can be observed on the TV monitor 40 via the processor 20.
[0013]
The focus adjustment lens 17 is driven by forward / reverse rotation of the drive motor M, and is between a normal observation position having a minimum focal length (maximum field angle) and a maximum magnification observation position having a maximum focal distance (minimum field angle). Can move. In the present embodiment, the rotation direction of the drive motor M when moving the focus adjustment lens 17 in the magnification observation position direction (telephoto direction) is referred to as normal rotation, and the focus adjustment lens 17 is moved in the normal observation position direction (wide angle direction). The direction of rotation of the drive motor M at the time of making it is called reverse rotation. In the vicinity of the drive motor M, a temperature sensor S for detecting the temperature in the insertion portion distal end 11a (ambient temperature of the motor M) is provided.
[0014]
Behind the first illumination lens 16, illumination light from a lamp 30 provided in the processor 20 is transmitted from the connector unit 14 through the universal tube 13, the grasping operation unit 12, and the light guide 19 passing through the body insertion unit 11. Given.
[0015]
The grip operation unit 12 is provided with an AF changeover switch 12a for switching the presence or absence of the AF function. That is, an AF mode (enlarged observation mode) in which the position of the focus adjustment lens 17 is automatically adjusted according to the position of the insertion portion tip 11a by turning on / off the AF changeover switch 12a, and the focus adjustment lens 17 in the normal observation position. Can be switched to a fixed focus mode (normal observation mode).
[0016]
The processor 20 includes a CCD drive circuit 21 that outputs a synchronization signal to the CCD 18 and the CCD process circuit 22 and scans the CCD 18 based on the synchronization signal. The CCD process circuit 22 is a circuit that reads the output signal of the CCD 18 in synchronization with the synchronization signal input from the CCD drive circuit 21 and pre-processes the read signal (signal amplification processing, noise removal processing, etc.). The signal output from the CCD process circuit 22 is converted into a digital signal by the A / D conversion circuit 23, the gamma correction circuit 24 corrects the gamma characteristic of each pixel, and then the video signal processing circuit 25 performs various processing. Are processed and combined with AF operation information output from the motor control circuit 33 by the OSD (character information display circuit) 35, converted into an analog signal by the D / A conversion circuit 26, and sent to the TV monitor 40. Is output.
[0017]
The output signal of the CCD 18 is also input to the photometry circuit 27 and the focus information detection circuit 32 via the CCD process circuit 22 and the A / D conversion circuit 23, respectively. The photometry circuit 27 obtains luminance information from the input signal, calculates the number of aperture driving pulses based on the luminance information, drives the aperture driving motor 28 by the calculated number of aperture driving pulses, and opens / closes the aperture 29. The illumination light emitted from the lamp 30 is adjusted to an optimum light amount by the diaphragm 29 and then supplied to the first illumination lens 16 via the second illumination lens 31 and the light guide 19.
[0018]
The focus information detection circuit 32 and the motor control circuit 33 are circuits that operate when the AF mode is set by the AF selector switch 12a. The focus information detection circuit 32 obtains contrast information from the input signal, calculates optimum focus information based on the contrast information, and outputs it to the motor control circuit 33. The motor control circuit 33 operates the motor drive circuit 34 based on the optimum focus information input from the focus information detection circuit 32 and moves the focus adjustment lens 17 through the drive motor M. The motor control circuit 33 is connected to a temperature sensor S provided at the distal end 11a of the insertion portion, and a predetermined timer time from when the AF changeover switch 12a is turned on (when the motor control circuit 33 starts operating). A built-in timer 33a that measures the time until T elapses is provided. The motor control circuit 33 outputs AF operation information for displaying on the TV monitor 40 whether or not the AF operation is being performed to the OSD 35.
[0019]
The AF electronic endoscope 1 having the above configuration is characterized in that the AF operation time by the motor control circuit 33 is limited in order to suppress the temperature rise of the insertion portion distal end 11a. Specifically, as shown in the timing chart of FIG. 3, the motor control circuit 33 is operated by the motor control circuit 33 from the time t1 when the AF mode is set when the AF switch 12a is turned on to the time t2 when a predetermined timer time T elapses. The drive motor M can be driven via the drive circuit 34, that is, the AF operation can be executed. When the timer time T has elapsed (t2), the driving of the drive motor M is stopped by the motor control circuit 33, and the AF operation is not executed until time t3 when the AF switch 12a is next detected. Furthermore, the AF electronic endoscope 1 constantly monitors the ambient temperature of the drive motor M based on the output of the temperature sensor S, and the output of the temperature sensor S is the first specified value P1 even within the timer time T during which AF operation is possible. (T4), the motor control circuit 33 stops the drive motor M via the motor drive circuit 34. Then, the AF operation is not executed until the output of the temperature sensor S falls below the second specified value P2 that is lower than the first specified value P1 (t5).
[0020]
In the following, the flow of the AF operation of the AF electronic endoscope 1 will be described in more detail with reference to FIG. This AF operation is started by the ON interruption of the AF selector switch 12a. When the AF operation is started, first, it is determined whether or not the output of the temperature sensor S is less than the second specified value P2 (S11). If the output of the temperature sensor S is not less than the second specified value P2, the AF operation is not performed (S11; N). The second specified value P2 is set to a value (lower temperature) that is smaller than the first specified value P1 that interrupts the AF operation.
[0021]
If the output of the temperature sensor S is less than the second specified value P2 (S11; Y), the focus information detection circuit 32 and the motor control circuit 33 are activated to start the AF operation (S13), and the timer by the built-in timer 33a Measurement of time T is started (S15). Subsequently, as shown in FIG. 5, AF operation information 41 indicating that the AF operation is in progress is displayed on the TV monitor 40 together with the endoscopic image 42 (S17). In the AF operation, the focus information detection circuit 32 detects the optimum focus position based on the signal input from the A / D conversion circuit 23, and the motor control circuit 33 is driven via the motor drive circuit 34 based on the optimum focus position information. The motor M is driven to adjust the position of the focus adjustment lens 17 between the normal observation position and the magnified observation position.
[0022]
During the AF operation, the motor control circuit 33 determines whether or not the output of the temperature sensor S is equal to or less than the first specified value P1 (S19). It is determined whether the time is up (S19; Y, S21). If the time has not expired, the process returns to S19, and the determinations of S19 and S21 are repeated while executing the AF operation (S21; N).
[0023]
When the output of the temperature sensor S exceeds the first specified value P1 (S19; N), or when the built-in timer 33a times out (S21; Y), the motor control circuit 33 reverses the drive motor M. After the focus adjustment lens 17 is returned to the normal observation position, the drive motor M is stopped (S23), and the AF operation information 41 is erased from the TV monitor 40 (S25). After the process of S23, the process returns to S11 and is executed again from S11.
[0024]
According to the present embodiment described above, even when the AF mode is set by the AF selector switch 12a, when the timer time T has elapsed from the start of the AF operation or the output of the temperature sensor S reaches the first specified value P1. At that time, the AF operation is stopped. That is, the drive of the drive motor M is stopped before the ambient temperature of the drive motor M increases excessively. Thereby, the temperature rise of the insertion portion distal end 11a is suppressed, and as a result of the CCD 18 operating well, observation and inspection can be performed with a good quality endoscopic image. Further, according to the present embodiment, the AF operation is not always actually performed even when the changeover switch 12a is turned on, but the TV monitor 40 displays whether or not the AF operation is being performed. The operator can easily confirm the AF operation status. Furthermore, according to this embodiment, since the burden on the drive motor M due to long-time driving is reduced, there is an advantage that the life of the drive motor M is extended.
[0025]
In the present embodiment, the timer time T during which the AF operation can be performed is constant, and the AF operation is stopped when the output of the temperature sensor S reaches the first specified value P1 within the timer time T. Various modifications are possible. For example, the timer time T may be set according to the output of the temperature sensor S before the AF operation starts, and when the output of the temperature sensor S reaches the first specified value P1, the remaining timer time is shortened. It is good also as an aspect.
[0026]
Furthermore, in this embodiment, the AF operation is stopped until the output of the temperature sensor S becomes less than the second specified value P2, but if the output of the temperature sensor S does not reach the first specified value P1, the AF operation is stopped. It is good also as an aspect which restarts.
[0027]
In this embodiment, the temperature sensor S is disposed in the vicinity of the drive motor M to detect the ambient temperature of the drive motor M. However, the temperature sensor S may be disposed in the vicinity of the CCD 18 so that the ambient temperature of the CCD 18 can be detected. .
[0028]
【The invention's effect】
According to the autofocus electronic endoscope of the present invention, since the autofocus operation is stopped before the ambient temperature of the drive motor rises excessively, it is possible to suppress the temperature rise in the distal end of the insertion portion, and to improve the quality. Observation and inspection can be performed with an endoscopic image.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an AF electronic endoscope to which the present invention is applied.
2 is a partial cross-sectional view showing a distal end structure of an in-vivo insertion portion of the electronic endoscope main body shown in FIG. 1. FIG.
FIG. 3 is a timing chart of AF operation.
FIG. 4 is a flowchart showing a flow of AF operation.
FIG. 5 is an example of a monitor image displayed on a TV monitor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 AF electronic endoscope 10 Electronic endoscope main body 11a Insert part front-end | tip 12a AF changeover switch 15 Objective lens 17 Focus adjustment lens 18 CCD
20 processor 32 focus information detection circuit 33 motor control circuit 34 motor drive circuit 40 TV monitor 41 AF operation information 42 endoscope image M drive motor S temperature sensor

Claims (6)

A focus adjustment lens movable along the optical axis of the objective optical system provided at the distal end of the insertion section;
A drive motor which is provided at the distal end of the insertion section and moves the focusing lens between a normal observation position with a wide angle of view and an enlarged observation position with a narrow angle of view;
Focus detection means for detecting the focus state of the observation object;
Motor control means for driving the drive motor based on the focus state detected by the focus detection means to adjust the position of the focus adjustment lens;
An AF switching member that switches between an AF mode in which the motor control means is operated to adjust the position of the focus adjustment lens, and a fixed focus mode in which the focus adjustment lens is fixed at a normal observation position;
Comprising a; limiting means for limiting the AF operation time by the motor control means
The limiting means stops the AF operation by the motor control means when a predetermined timer time has elapsed since the AF mode was set by the AF switching member . The autofocus electronic endoscope according to claim 1 , further comprising a temperature sensor that detects an ambient temperature of the drive motor,
The auto-focus electronic endoscope, wherein the limiting means changes an AF operation time by the motor control means in accordance with an ambient temperature detected by the temperature sensor. 3. The autofocus electronic endoscope according to claim 2 , wherein the limiting means stops the AF operation by the motor control means when the ambient temperature detected by the temperature sensor reaches a first temperature. Electronic endoscope. 4. The autofocus electronic endoscope according to claim 3 , wherein the limiting means is controlled by the motor control means until an ambient temperature detected by the temperature sensor becomes lower than a second temperature lower than the first temperature. Autofocus electronic endoscope that stops AF operation. In claims 1 to autofocus electronic endoscope according to any one of 4, the motor control means, when stopping the AF operation by the limiting means, by returning the focusing lens to the normal viewing position An autofocus electronic endoscope for stopping the drive motor. The autofocus electronic endoscope according to any one of claims 1 to 5, wherein the autofocus electronic endoscope includes a TV monitor that displays AF operation information indicating whether or not an AF operation is being performed together with an endoscopic image. Endoscope.

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