JP2011112861A - Lens position controller of endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate changing and adjusting imaging magnification while securing sufficient torque to rotate a torque wire in an endoscope which drives lenses using the torque wire. <P>SOLUTION: The torque of a motor 22 is transmitted to a gear 20 engaging with a cam ring 19 through the torque wire 21. The position of a lens 18 is adjusted by detecting rotation of the motor 22 and determining the position of the cam ring 19 from the detected amount of rotation. Driving signals U, V and W are periodically applied to the motor 22 at a predetermined duty ratio to rotate the motor 22 intermittently. The tip of the torque wire 21 is rotated smoothly and continuously at low speed using the lag of rotational rate change at the tip of the torque wire 21 to facilitate adjustment of the position of the lens 18. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens position control device that controls a lens position of an endoscope using a torque wire.

  A magnifying endoscope in which an imaging optical system of an electronic endoscope is provided with a zoom mechanism and the observation magnification is variable is known. The zoom lens provided at the distal end of the endoscope insertion portion is driven, for example, by transmitting the rotational driving force of a motor provided at the operation portion to the distal end of the insertion portion via a torque wire. The position of the zoom lens is detected using, for example, an encoder provided at the distal end of the insertion portion. However, the configuration in which the sensor is provided at the distal end of the insertion portion is disadvantageous in reducing the diameter of the endoscope insertion portion, and the structure becomes complicated. In order to solve such a problem, a configuration has been proposed in which the lens position is grasped from the time required for the zoom lens to move between the driving ends and the operation time of the zoom switch (Patent Document 1).

Japanese Patent No. 3936512

  However, since the torque wire is passed through an insertion portion as long as several meters, a large torque is required to rotate the torque wire. In order to increase the torque applied to the torque wire, there are a method of increasing the output torque of the motor itself and a method of rotating the motor at a high speed and using a speed reducer. However, in order to increase the output torque of the motor, it is necessary to increase the number of windings, and even when using a reduction gear, it is necessary to use a large reduction gear as such, which is disadvantageous for downsizing. On the other hand, when a motor that rotates at high speed is used directly, the imaging magnification changes rapidly and the operability deteriorates. For example, when re-shooting at a desired magnification is necessary, it is difficult to reproduce shooting at the same magnification when the rotation is fast.

  That is, when driving a lens of an endoscope using a torque wire, it is difficult to simultaneously satisfy torque, lens moving speed, and downsizing.

  The present invention provides an endoscope apparatus that drives a lens using a torque wire, and obtains a small lens position control device that can easily adjust the position of the lens while obtaining sufficient torque for rotating the torque wire. It is an issue.

  The lens position control device for an endoscope of the present invention includes a lens position adjustment mechanism for adjusting the position of the lens, a motor that supplies power to the lens position adjustment mechanism, and the power of the motor is transmitted to the lens position adjustment mechanism. A torque wire and motor control means for continuously rotating the tip of the torque wire at a rotational speed lower than the rotational speed of the motor by controlling at least one of the period and duty ratio of the voltage signal applied to the motor. It is characterized by providing.

  The lens position adjustment mechanism is a zoom mechanism that changes the imaging magnification, and the motor control means is configured such that the rotational speed of the tip of the torque wire is relatively high in a section where the change in imaging magnification is relatively large with respect to the rotation angle of the tip. Slow and relatively fast in relatively small sections. The lens position adjusting mechanism is a zoom mechanism that changes the imaging magnification, and the motor control unit controls at least one of the motor operation rotation speed and the motor stop time of each step so that the change in the imaging magnification becomes constant. The motor control means has a movement time mode from a plurality of telephoto (zoom in / tele) to wide angle (zoom out / wide), and the rotational speed of the tip of the torque wire is different in each mode.

  The lens position control device further includes a rotation amount detection unit that detects rotation of the motor and calculates a rotation amount, an end point detection unit that detects an end point of the movable range of the motor, and a movable range of the motor detected by the end point detection unit. And an initialization means for detecting a rotation amount corresponding to the movable range of the motor by driving the motor from one end to the other end of the lens, and a rotation amount corresponding to the movable range of the lens and a rotation corresponding to the movable range of the motor From the amount, the position of the lens is adjusted by controlling the rotation of the motor within the rotation range corresponding to the movable range of the lens.

  According to the present invention, in an endoscope apparatus that drives a lens using a torque wire, a small lens that allows an operator to easily change and adjust an imaging magnification while obtaining sufficient torque for rotating the torque wire. A position control device can be obtained.

1 is a schematic diagram illustrating a configuration of an electronic endoscope system according to an embodiment of the present invention. It is a block diagram which shows typically the electrical and mechanical structure of the electronic endoscope (scope main body) of this embodiment. It is a block diagram which shows the structure of a motor drive circuit and a control part. 6 is a timing chart showing a correspondence between a three-phase drive signal (U, V, W) output from the motor drive circuit and a single rotation detection signal generated in the motor drive circuit. It is a figure which shows the relationship between the rotation of the motor in initialization operation | movement, and the position (lens position) of a cam ring. It is a flowchart of the initialization operation | movement process of this embodiment. The difference between the output timing of the motor drive command (drive signal), the rotational speed change at a certain position on the motor side of the torque wire corresponding thereto, and the rotational speed change at the cam ring side tip of the torque wire is shown. It is a graph which shows the mode of the motor control in the lens position control of 1st Embodiment. It is a flowchart of the lens position control process in this embodiment. It is a graph which shows the mode of the motor control in the lens position control of the modification of 1st Embodiment. It is a graph which shows the mode of the motor control in the lens position control of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the electronic endoscope system according to the first embodiment of the present invention.

  The electronic endoscope system generally includes a scope main body (electronic endoscope) 10, a processor device 11 to which the scope main body is detachably attached, and a monitor device 12 that displays an endoscopic image. The scope main body 10 includes a flexible tube, an insertion portion 13 that is inserted into the body or a tube hole, an operation portion 14 that is gripped and operated by a user and to which a proximal end portion of the insertion portion 13 is coupled, and a processor device 11. And a connector portion 15 that electrically and optically connects the scope main body 10 and the processor device 11 and a universal cord 16 that communicates between the operation portion 14 and the connector portion 15.

  The processor device 11 includes, for example, a light source unit (not shown) together with the image processing unit, and a light guide fiber (not shown) disposed from the light source unit to the distal end of the insertion unit 13 from the connector unit 15. Illumination light is transmitted through and irradiated. The video imaged by the image sensor provided at the distal end of the insertion unit 13 is sent to the processor device 11 via the insertion unit 13, the operation unit 14, the universal cord 16, and the connector unit 15, and predetermined image processing is performed. After being applied, it is displayed on the monitor device 12.

  FIG. 2 is a block diagram schematically showing the electrical configuration of the scope body 10 and the mechanical configuration of the lens driving system shown in FIG.

  An image sensor 17 such as a CCD or CMOS is disposed at the distal end of the insertion portion 13. In the present embodiment, the image pickup device 17 is a CCD, and an image through a lens (lens group) 18 is projected onto the image pickup surface of the CCD 17. The lens 18 includes a zoom lens (lens group) (not shown), and the zoom lens is held by a lens holding frame (not shown) that is slidable in the optical axis direction. As is well known in the art, due to the engagement between the pin provided on the lens holding frame and the cam groove provided on the cam ring 19, the rotational movement around the optical axis of the cam ring 19 is caused in the optical axis direction of the lens holding frame. It is converted into a linear motion, and the position of the zoom lens is adjusted (lens position adjusting mechanism). As a result, the CCD 17 captures an image with a magnification corresponding to the position of a zoom lens (not shown).

  A gear portion (not shown) is formed on the outer peripheral surface of the cam ring 19 along the circumferential direction, and the gear 20 is engaged with the gear portion. One end of a torque wire 21 disposed in the insertion portion 13 is connected to the gear 20, and the other end is connected to a motor 22 provided in the operation portion 14 via a small reduction gear 23 (note that The reduction gear 23 can be omitted). That is, the rotational force of the motor 22 is transmitted to the gear 20 via the torque wire 21, and the cam ring 19 is rotated around the optical axis.

  The motor 22 is, for example, a three-phase sensorless / brushless / DC motor, and a three-phase drive signal (U, V) sent from the motor drive circuit 24 provided in the connector unit 15 via the universal cord 16 (see FIG. 1). , W). The motor drive circuit 24 is controlled by a control unit 25 provided in the connector unit 15, and the motor drive circuit 24 detects the rotation of the motor 22 and outputs it to the control unit 25 as described later.

  The operation unit 14 is provided with an input unit 28 including a tele switch 26 and a wide switch 27 for instructing telephoto (zoom-in / tele) and wide-angle (zoom-out / wide) in the zoom function, respectively. The operation signals of the tele switch 26 and the wide switch 27 are sent to the control unit 25, and the control unit 25 controls the driving including the rotation direction of the motor 22 through the motor drive circuit 24 according to the operation signal.

  The driving of the CCD 17 is controlled by a CCD driving pulse signal output from a CCD driving circuit 29 provided in the connector unit 15, and the CCD driving circuit 29 is controlled by the control unit 25. The image signal generated by the CCD 17 is output to a CCD signal processing unit 30 provided in the connector unit 15. The CCD signal processing unit 30 corresponds to an analog front end, performs first-stage amplification, correlated double sampling, and AD conversion on the analog image signal from the CCD 17 and outputs the result to the control unit 25.

  In addition, a communication control unit 31 is connected to the control unit 25, and the communication control unit 31 receives digital image signals and various control signals input to the control unit 25 as images of the processor device 11 (see FIG. 1). While outputting to a processing unit, the various control signals received from the processor apparatus 11 are input into the control part 25. FIG.

  Next, with reference to FIG. 3 and FIG. 4, the details of the configuration of the motor drive circuit 24 and the control unit 25 in the present embodiment will be described. 3 is a block diagram showing the configuration of the motor drive circuit 24 and the control unit 25, and FIG. 4 shows a three-phase drive signal (U, V, W) output from the motor drive circuit 24 and the motor drive circuit. 24 is a timing chart showing correspondence of one rotation detection signal FG generated at 24. FIG.

In the present embodiment, the motor drive circuit 24 includes a three-phase sensorless motor control logic circuit 32, a drive circuit 33, a phase detection circuit 34, and the like. The three-phase sensorless motor control logic circuit 32 generates the startup sequence of the motor 22 and the U, V, and W phase pulse waveforms to be given to the motor 22, and the drive circuit 33 generates the U, The U, V, and W phase voltages that are actually applied to the V and W terminals are output. The U, V, and W signal lines connecting the motor 22 and the three-phase sensorless motor control logic circuit 32 are connected to one input terminal of each of the three comparators 35U, 35V, and 35W, and the other input terminal has a reference voltage. V _REF is input.

  When the voltage applied to each phase of the UVW is in an off state, a voltage is generated by an induced electromotive force corresponding to the rotation speed in the corresponding phase. In the present embodiment, each of the comparators 35U, 35V, and 35W detects the generation of the induced electromotive force of each phase, and the phase detection circuit 34 detects the phase of the motor 22. In addition, since the output from the comparator for one phase is a pulse signal having a period corresponding to one rotation of the motor 22, this is output to the control unit 25 as a one-rotation detection signal FG in this embodiment. FIG. 4 also shows the timing of phase detection in each phase.

  The control unit 25 includes a microcomputer (or FPGA) 36 and a reference clock counting circuit 37, and the three-phase sensorless motor control logic circuit 32 is controlled by the microcomputer 36. For example, at least one of induced electromotive force detection pulses corresponding to each phase of UVW is input to the microcomputer 36 from the phase detection circuit 34. In the present embodiment, the U phase is used as the single rotation detection signal FG and input to the microcomputer 36. In the microcomputer 36, a rotation amount corresponding to the rotation angle of the motor 22 is calculated based on the one rotation detection signal FG, and the lens position is controlled from the motor rotation amount.

  The reference clock counting circuit 37 is supplied with a reference clock signal CLK from a timing generator (not shown) and a one-rotation detection signal FG from the phase detection circuit 34. In the reference clock counting circuit 37, each time the motor 22 rotates once and the rising edge of the FG pulse is detected, the number of clock pulses is counted, and the number of pulses of the reference clock signal CLK during one rotation is sent to the microcomputer 36. (Note that the falling edge of the FG pulse may be used). This count value corresponds to the rotation speed and rotation frequency of the motor 22, and is used in the detection processing of the end points P1 and P2 described later.

  Next, with reference to FIGS. 5 and 6, the lens position initialization operation in the present embodiment will be described. FIG. 5 shows the relationship between the rotation of the motor 22 and the position of the cam ring 19 (lens position) in the initialization operation. The horizontal axis corresponds to the rotation amount of the motor 22 and the vertical axis corresponds to time. FIG. 6 is a flowchart of the initialization operation process of this embodiment. The initialization operation is executed in the microcomputer 36 prior to the lens position control process such as when the electronic endoscope is powered on.

  In the configuration in which the rotational force is transmitted to the lens driving mechanism using the torque wire, even if the movement of the lens (rotation of the cam ring in this embodiment) is stopped by the locking mechanism, the motor is twisted to a constant torque. Rotates until occurs. For this reason, the rotation range (movable range) of the motor is wider than the mechanical movable range of the lens. That is, when the lens position is controlled from the rotation amount of the motor 22, it is necessary to obtain a correspondence between the rotation amount of the motor 22 and the position of the cam ring 19 (lens position) (see FIG. 2).

  In FIG. 5, the left side corresponds to the Tele (telephoto) side, the right side corresponds to the Wide (wide angle) side, and time elapses from top to bottom. In the present embodiment, the rotation amount of the motor 22 is the count value of the one-rotation detection signal FG (for example, the number of pulses obtained by adding when rotating to the Tele side during normal rotation and subtracting when rotating toward the Wide side during reverse rotation). As required.

Section A1 shows the movable range of the motor 22, including the displacement due to twisting of the torque wire 21 (rotatable range), the section _{A 3} is including the rotation ratio (gear 20, 23 of the motor 22 and the cam ring 19 The rotation range of the motor 22 corresponding to the movable range of the cam ring 19 calculated from the gear ratio). For example, when the motor side gear ratio is 1:79, the cam 22 is rotated once for 79 rotations of the motor 22, and when the gear ratio of the torque wire to the cam ring is 1: 3, the cam ring 19 is mechanical. When the rotatable range is 0.5 rotation (180 °), the torque wire requires 1.5 rotations. In the case of the above example, the count number of one rotation detection signal FG over the movable range of the cam ring 19 is 118.5 (= 79 × 1.5).

Section A ₂ indicates an area used for rotation control of the motor 22. That is, it is desirable to provide an extra movable range on the Tele side or Wide side with respect to the mechanical movable range in order to operate the cam ring 19 with a mechanical movable range at the Tele end or Wide end. In this embodiment, the rotatable range of the cam ring 19 calculated from the design value is provided with a margin of 20 pulses on the Tele end side and 30 pulses on the Wide end side.

  In an initial state such as when the endoscope is activated, the positions of the lens 18 and the cam ring 19 are unknown. When the cam ring 19 is at a point P0 in FIG. 5 at the time of activation, in the initialization operation process of this embodiment, first, in step S100, the rotation of the motor 22 in the Tele direction is started. Next, in step S102, detection processing of the tele end point P1 is started, and the motor 22 is rotated in the tele direction until the tele end point P1 is detected. In step S102, when the tele end point P1 is detected, the rotation of the motor in the tele direction is stopped.

  Next, in step S104, the motor 22 is rotated in the Wide direction, and almost simultaneously, in step S106, counting of one rotation detection signal (pulse signal) FG is started. In step S108, the wide end point P2 detection process is started. The motor 22 is rotated in the Wide direction until the Wide side end point P2 is detected, and when the Wide side end point P2 is detected, the rotation of the motor in the Wide direction is stopped. At this time, the number of FG pulses from point P1 to point P2 is counted.

The number of pulses between the tele-side end point P1 and the wide-side end point P2 substantially corresponds to the wire movable region A1, and the torsional characteristics of the torque wire 21 are symmetrical with respect to the left and right rotations. center of a ₃ coincides with the center of point P1, P2. Therefore, in the initialization operation of the present embodiment, in step S110, the end point P1, the center between P2 to Wide side 90 pulses (which is half of the movable range _{A 3} 60 pulses + Wide side margin 30 pulses) moved position P3 is the origin in the lens position control process, and the motor 22 is rotated to this position.

That is, the motor 22 is again rotated to the Tele side from Wide end point P2, and the pulse number of the pulse number and the Wide side margin half section of the cam ring movement range _{A 3} from the total number of pulses between the end points P1, P2 The rotation of the motor 22 is returned by the number of subtracted pulses, the count value of the FG pulse at this time is stored in the non-volatile memory or the like as position information, and this initialization operation process ends.

  The Tele end and Wide end detection processing (steps S102 and S108) is performed, for example, by monitoring the motor rotation speed, setting a threshold value to detect a decrease in speed, or calculating the rate of change. .

Thereafter, the point P3 as the origin, on the basis of the operation of the Tele / Wide switch 26, the lens position control in the section _{A 2} is executed, the count value of the FG pulses, the memory updated at any time, is stored in the position information The When the count number of one rotation detection signal FG over the movable range of the cam ring 19 is 120, the Tele end margin is 20 pulses, and the Wide end side margin is 30 pulses, the region used for control (section A ₂ ) Is an interval of 170 pulses (20 + 120 + 30).

Next, with reference to FIGS, illustrating a lens position control in the Tele / Wide switch 26 operated based on interval (used area) _{A 2} to the origin point P3 in the first embodiment .

  Since the torque wire is passed through a flexible tube of several meters, sufficient torque is required to rotate it. However, since it is necessary to increase the number of windings of the motor to obtain a large torque, the size is increased. Even with a small motor, if the rotational speed is increased, a large torque can be obtained. However, if the rotational speed is fast, fine adjustment of the imaging magnification becomes difficult and the operability deteriorates. In order to reduce the rotational speed, it is necessary to use a large speed reducer, which is also disadvantageous for miniaturization. That is, conventionally, it has been difficult to simultaneously realize low speed and high torque with a small configuration.

  In the lens position control of the present embodiment, an interval period is provided for driving the motor, and the rotation of the torque wire is kept substantially constant while driving the motor intermittently, thereby realizing low-speed rotation and high torque with a small motor. is doing. FIG. 7 shows the output timing of the drive command (drive signal) for the motor 22, the rotational speed change at a position on the motor side (base end side) of the torque wire 21 corresponding to this, and the cam ring side of the torque wire 21. The change in rotational speed at the tip of is shown.

  As shown in FIG. 7, the motor drive command is periodically output at a predetermined duty ratio. That is, the three-phase drive signals (U, V, W) are output to the motor 22 while the motor drive command is output (while the pulse rises). As the motor drive command pulse rises, the rotational speed of the proximal end side of the torque wire 21 gradually increases toward the set rotational speed of the motor 22. On the other hand, when the motor drive command enters the interval period and the output of the drive signal is stopped, the rotation of the torque wire 21 is gradually decelerated.

  Further, the rotational speed of the distal end of the torque wire 21 is further affected by the inertia moment and resistance of the wire and the cam ring, and is further delayed with respect to the speed change on the base end side, and the change is further gradual. Therefore, the driving of the motor 22 is stopped before the rotation of the torque wire 21 reaches the rotation speed of the motor 22, and the rotation of the motor 22 is restarted before the rotation is greatly decelerated, as shown in FIG. As described above, the tip of the torque wire 21 is smoothly and continuously rotated at a substantially constant speed lower than the speed of the motor 22. Therefore, while rotating the motor 22 at high speed to obtain a high torque (that is, without lowering the applied voltage), the actual cam can be controlled by controlling the cycle and duty ratio of the motor drive command without using a reduction gear. It is possible to sufficiently reduce the rotation speed of the ring 19.

  The graph of FIG. 8 shows a specific example of lens position control (rotation control of the motor 22) of the first embodiment in the use region A2 (see FIG. 5). In FIG. 8, the horizontal axis is time (s), the scale on the left side of the vertical axis is the count value of the FG pulse, and the scale on the right side of the vertical axis is the imaging magnification of the lens group 18. Further, in FIG. 8, the detection state of the FG pulse in the lens position control, that is, the driving / stopping state of the motor 22 is shown along the time axis on the lower side of the graph (corresponding to the motor driving command pulse in FIG. To do).

  The FG pulse is detected during the hatched period, and a predetermined voltage is applied to the motor 22. That is, the motor 22 is rotationally driven at a constant speed and torque during this period. On the other hand, in other periods, the voltage application to the motor 22 is stopped, and the rotation drive of the motor 22 is stopped.

A polygonal line L1 is a graph showing the relationship between the elapsed time (s) when the Tele switch 26 is continuously pressed from the point P3 and the accumulated value of the detected FG pulse (count value of the FG pulse corresponding to the lens position). . The curve S shows the variation of the magnification of the imaging optical system when the motor 22 from the point Q ₁ is continuously rotated at the fixed rate. The point Q ₁ (number of FG pulses = 30) corresponds to a position moved by 30 pulses as a margin from the origin P ₃ (see FIG. 5) to the Tele side in the lens position control process. In the polygonal line L1, the point Q ₂ (number of FG pulses = 150) corresponds to the position moved from the point Q ₁ to the Tele side by 120 pulses (movable range A ₃ minutes). That is, the range of the points Q _{1 to} Q ₂ corresponds to the cam ring movable range A ₃ . Further, FG pulse number in the range of 0 to 170 correspond to the use area _{A 2.}

Curve S representing the characteristic of the imaging magnification is 13 times the minimum magnification at the point _{Q 1,} reaches the FG pulse number 150 is a Tele side movable limit of the cam ring 19 at point _{Q 3,} 99 of the imaging magnification is the maximum value Doubled. In general, the relationship between the position of the cam ring (number of FG pulses) and the imaging magnification is non-linear. In a section where the magnification is small, it increases in proportion to the moving distance of the cam ring (change amount of the FG pulse), but when the magnification increases. Gradually increase rate decreases.

In the example of the graph of FIG. 8, the curve S increases in a substantially linear manner at points Q ₁ to Q ₄ on the Wide side, and exhibits a non-linear increase in which the increase rate gradually decreases at points Q ₄ to Q ₃ on the Tele side. Show. Therefore, in the section corresponding to the points Q ₄ to Q ₃ , the increase in imaging magnification with respect to the rotation of the cam ring 19 (lens movement) is smaller than in the section corresponding to the points Q ₁ to Q ₄ . Therefore, in order to facilitate the adjustment and improve the operability, it is desirable that the rotational speed of the cam ring 19 in the region from the point Q ₁ to the point Q ₄ is made slower than the rotational speed of the point Q ₄ to the point Q ₃ .

Therefore, in the first embodiment, the period of the pulse signal of the motor drive command is made different between the section B1 corresponding to the section with the FG pulse number 30 to 95 and the section B2 corresponding to the section with the FG pulse number 95 to 150. The rotational speed at the tip of the torque wire 21 (the rotational speed of the cam ring 19) is varied. That is, the rotational speed of the motor 22 is the same in the sections B1 and B2, but the period of the duty control is relatively short in the section B1 (the rotation of the tip of the torque wire is relatively low), and the period of the duty control in the area B2. Is set relatively long (the rotation of the torque wire tip is relatively fast). Thus, configured such that the change in the imaging magnification with respect to the operation of the Tele / Wide switch 26 over the entire movable range _{A 3} of the cam ring 19 (FIG. 2) is constant. Note that the voltage value applied to the motor 22 is equal in both sections B1 and B2.

  FIG. 9 is a flowchart of lens position control based on the operation of the Tele / Wide switches 26 and 27 described with reference to FIGS. This control is executed in the microcomputer 36 and the like (FIGS. 2 and 3) of the control unit 25.

  In step S200, the presence / absence of an operation signal from any of the tele / wide switches 26 and 27 is determined. If neither switch is operated and there is no operation signal, the drive of the motor 22 is stopped in step S210, and the presence or absence of the operation signal is determined again in step S200. On the other hand, if any of the Tele / Wide switches 26 and 27 is operated in Step S200 and an operation signal is obtained, what is the input operation signal of the Tele / Wide switches 26 and 27 in Step S201. Is judged.

  If it is determined that the operation signal is for the wide switch 27, whether or not the current position corresponds to the wide-side end point of the use area A2 is determined from, for example, the number of FG pulses in step S202. If it is determined that it is an end point, the process returns to step S200 and the same processing is repeated. If it is determined that it is not an end point, in step S203, driving of the motor 22 toward the Wide side is started. That is, a three-phase drive signal (U, V, W) is supplied to the motor 22, and the motor 22 is rotated in a direction corresponding to the Wide side. Thereafter, in step S204, it is determined whether or not the output for one pulse of the motor drive command shown in FIG. 7 has been completed, and the determination in step S204 is repeated until the output for one pulse is completed. In this determination, the pulse width is set to a value corresponding to each section based on the number of FG pulses.

  On the other hand, if it is determined in step S201 that the input operation signal is for the tele switch 26, whether or not the current position corresponds to the tele end point of the use area A2 is determined in step S207, for example. It is determined from the number of FG pulses. If it is determined that it is an end point, the process returns to step S200 and the same processing is repeated. If it is determined that it is not an end point, driving of the motor 22 toward the Tele side is started in step S208. That is, a three-phase drive signal (U, V, W) is supplied to the motor 22, and the motor 22 is rotated in a direction corresponding to the Tele side. Thereafter, in step S209, it is determined whether or not the output of one pulse of the motor drive command shown in FIG. 7 has been completed, and the determination in step S209 is repeated until the output of one pulse is completed. In this determination, the pulse width is set to a value corresponding to each section based on the number of FG pulses.

  If it is determined in steps S204 and S209 that the output of one pulse has been completed, the process proceeds to step S205, and an interval timer (not shown) built in the control unit 25 (FIG. 2) or the like is started. In S206, the end of the timer is determined. That is, the interval timer is set to the time in the interval period of FIG. 7, and in step S206, it is repeatedly determined whether or not the interval period has elapsed.

  If it is determined in step S206 that the interval period has elapsed, the process returns to step S200, and the above-described processes are repeatedly executed. Thus, the lens position control process of the present embodiment ends.

  As described above, according to the first embodiment of the present invention, a mechanism (such as a zoom mechanism) used for position control of the lens at the distal end of the endoscope via the torque wire that has passed through the endoscope insertion portion is a small motor. In the configuration driven by, the rotational speed of the tip of the torque wire is sufficiently decelerated without using a configuration such as a speed reducer while rotating a small motor at a rotational speed at which sufficient torque can be obtained to rotate the torque wire. The lens position can be easily adjusted (imaging magnification adjustment) with an extremely small configuration.

  Further, according to the present embodiment, while using a small sensorless and DC brushless motor, the rotation of the motor is grasped with a simple configuration, and the correspondence to the position of the cam ring or the lens is taken into consideration in consideration of the twist of the wire. Therefore, it is possible to control the lens position with high accuracy without providing a sensor such as an encoder at the distal end of the insertion section, to reduce the diameter of the insertion section and to reduce the size of the drive section. Can do.

  In addition, according to this embodiment, by adjusting the cycle and duty ratio of the motor drive command (drive signal), the rotational speed of the torque wire tip (cam ring) can be controlled easily and freely, and the lens moving speed can be adjusted. it can. Furthermore, in the present embodiment, the rotational speed in the section on the low magnification side of the tip of the torque wire is adjusted in the section on the high magnification side in accordance with how the imaging magnification changes with respect to the lens position (cam ring, rotational position of the tip of the torque wire). By setting it slower than the rotation speed, the change in imaging magnification is made as constant as possible. Thereby, the operability of the zoom operation is improved. For example, even when shooting at the same magnification is performed at a later date, it is possible to easily perform shooting at the same magnification.

Next, a modification of the first embodiment will be described with reference to FIG. FIG. 10 corresponds to FIG. 8 of the first embodiment, and is a graph showing a specific example of lens position control (rotation control of the motor 22) in a modified example in the use region A2 (see FIG. 5). In the first embodiment, the movable section A ₃ of the cam ring 19, the period of the divided motor drive command to the second section of the low-magnification side and the high magnification side, the duty ratio is set. However, in the modification, the section is divided more finely in correspondence with the curve S, and the change in the rate of increase / decrease of the imaging magnification due to the switch operation is further eliminated. Other configurations are the same as those in the first embodiment.

  In the example of FIG. 10, the section B3 corresponding to the number of FG pulses: 30 to 55, the section B4 corresponding to the number of FG pulses: 55 to 85, the section B5 corresponding to the number of FG pulses: 85 to 95, the number of FG pulses: 95. Four sections of section B6 corresponding to ˜150 are provided. The period of the motor drive command in each section becomes longer toward the Tele side (high magnification side), and the rotation speed at the tip of the torque wire becomes faster.

  As described above, according to the modification of the first embodiment, it is possible to perform control conforming to the curve S, to stabilize the speed of increase / decrease of the imaging magnification by the switch operation, and to improve operability. .

  Next, the lens position control apparatus of the second embodiment will be described with reference to FIG. The lens position control device of the second embodiment also has the same configuration as that of the first embodiment. However, in the lens position control of the second embodiment, for example, a plurality of patterns are provided in the cycle and duty ratio of the motor drive command, A plurality of modes are provided for the imaging magnification changing speed, that is, the cam ring rotation speed (lens moving speed).

  FIG. 11 corresponds to FIG. 8 and FIG. 10 of the first embodiment and its modifications. The elapsed time (s) and the number of FG pulses (lens position) when the Tele switch 26 is continuously pressed from the point P3. It is a graph which shows the relationship. In the second embodiment, for example, three modes of high speed, medium speed, and low speed are provided, and FIG. 11 shows polygonal lines M1, M2, and M3 corresponding to each mode.

  In the second embodiment, the change rate of the imaging magnification is varied by varying the interval period of the motor drive command in each mode. That is, the pulse width of the motor drive command is set to the same width in each section, but the interval period is set to be longer in the medium speed mode (41 ms) than in the high speed mode (10 ms) and more than in the medium speed mode (41 ms). Also, the low speed mode (60 ms) is set longer. The mode is selected by, for example, operating an operation switch (not shown) provided in the processor device 11. In addition, the other structure of 2nd Embodiment is the same as that of 1st Embodiment.

  As described above, in the second embodiment, the same effect as in the first embodiment can be obtained, and different speed modes can be provided as the changing speed of the imaging magnification. Therefore, the optimum mode according to the user's preference and situation Selection becomes possible. Further, in this embodiment, the speed is changed for each mode by changing only the interval without changing the applied voltage and pulse width of the motor drive signal. However, the difference in the mode is the applied voltage of the motor drive signal. A combination of changes may be included. These values are stored in, for example, a memory provided in the endoscope operation unit, the connector unit, or the processor device.

  Moreover, the modification of 1st Embodiment can also be employ | adopted as each mode of 2nd Embodiment, or a partial mode. Furthermore, the configuration can be such that the user can freely set the cycle and interval of the motor drive command, the voltage applied to the motor (corresponding to the slope of the line graph), and the like. The present embodiment can also be used for a lens moving mechanism other than the zoom mechanism.

  In this embodiment, the rotation of each rotation of the three-phase brushless and sensorless DC motor is detected. However, the n-phase motor may be configured to detect n pulses for each rotation. In this case, it is also possible to use the number of pulses of the reference clock counted during 1 / n rotation for detecting the rotation speed (rotation frequency) of the motor. In addition, the count value of the reference clock pulse between two or more single rotation detection signals can be used for detecting the rotation speed (rotation frequency) of the motor. Further, a motor with a sensor can be used. In this case, a sensor detection signal is used.

10 Scope body (electronic endoscope)
DESCRIPTION OF SYMBOLS 11 Processor apparatus 12 Monitor apparatus 13 Insertion part 14 Operation part 15 Connector part 17 Image pick-up element (CCD)
18 Lens 19 Cam ring (Lens position adjustment mechanism)
20 Gear 21 Torque Wire 22 Motor 24 Motor Drive Circuit 25 Control Unit 26 Tele Switch 27 Wide Switch 34 Phase Detection Circuit 36 Microcomputer 37 Reference Clock Counting Circuit

Claims (5)

A lens position adjustment mechanism for adjusting the position of the lens;
A motor for supplying power to the lens position adjusting mechanism;
A torque wire that transmits the power of the motor to the lens position adjusting mechanism;
Motor control means for continuously rotating the tip of the torque wire at a rotational speed lower than the rotational speed of the motor by controlling at least one of a period and a duty ratio of a voltage signal applied to the motor. An endoscope lens position control device characterized by the above.   The lens position adjusting mechanism is a zoom mechanism for changing an imaging magnification, and the motor control means is configured such that the rotation speed of the tip of the torque wire is relatively small with respect to the rotation of the tip. 2. The endoscope lens position control apparatus according to claim 1, wherein the lens position control device is set relatively slow in a large section and relatively fast in a relatively small section.   The lens position adjustment mechanism is a zoom mechanism that changes an imaging magnification, and the motor control unit controls at least one of the period and the duty ratio so that a change in speed of the imaging magnification change is reduced. The lens position control device for an endoscope according to any one of claims 1 and 2.   The lens position of the endoscope according to any one of claims 1 to 3, wherein the motor control unit includes a plurality of speed modes, and a rotational speed of a tip end of the torque wire is different in each mode. Control device. The lens position control device detects rotation of the motor and calculates a rotation amount;
End point detecting means for detecting an end point of the movable range of the motor;
Initialization means for detecting the amount of rotation corresponding to the movable range of the motor by driving the motor across one end of the movable range of the motor detected by the end point detecting means;
From the amount of rotation corresponding to the movable range of the lens and the amount of rotation corresponding to the movable range of the motor, the rotation of the motor is controlled within the rotational range corresponding to the movable range of the lens to adjust the position of the lens. It performs. The lens position control apparatus of the endoscope as described in any one of Claims 1-4 characterized by the above-mentioned.

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