JP2011019628A - Lens position controlling device of electronic endoscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the diameter of an insertion portion by a simple and compact structure, and to control the lens position with a high degree of accuracy in an electronic endoscope apparatus which drives a lens by using a torque wire. <P>SOLUTION: In the electronic endoscope, feedback control for keeping the rotational speed of a lens driving motor constant is performed. In the power activation, the motor is rotated to a Tele side until a point P1 where a motor command voltage is higher than a threshold value. Then, the motor is rotated to a Wide side until a point P2 where the motor command voltage is higher than a threshold value. The amount A1 of rotations corresponding to a rotatable range is detected in the rotation from the point P1 to the point P2. A region A2 used for the control of the motor in the lens position control is set from the number of rotations corresponding to a mechanical movable range A3 of a cam ring which is obtained in terms of the design by considering that the center of the mechanical movable range A3 of the cam ring coincides with the center of the rotatable range of the motor. The end point P3 of the Wide side in the use region A2 is determined as the origin in the processing of the lens position control. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic endoscope having a moving mechanism in an optical system, and more particularly to a lens position control mechanism 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, the configuration as in Patent Document 1 cannot cope with a speed change due to deterioration of a motor or a torque wire over time. It is also possible to grasp the lens position from the rotation angle of the motor, but since the wire is twisted, the rotation range of the motor is wider than the mechanical movable range of the lens, so accurate lens position control is possible. This must be taken into account to do so.

  It is an object of the present invention to reduce the diameter of an insertion portion with a simple and small configuration and to perform lens position control with high accuracy in an electronic endoscope apparatus that drives a lens using a torque wire. It is said.

  The lens position control device for an electronic endoscope according to the present invention includes a lens position adjustment mechanism for adjusting the position of the lens, a motor for supplying power to the lens position adjustment mechanism, and the power of the motor to the lens position adjustment mechanism. A torque wire to be transmitted; a rotation amount detection means for detecting rotation of the motor and calculating a rotation amount; and a speed control means for detecting an actual rotation speed of the motor and controlling the rotation speed of the motor to be constant. The end point detecting means for detecting the end point of the movable range of the motor, and the motor is driven from one end of the movable range of the motor detected by the end point detecting means to the other end to detect the rotation amount corresponding to the movable range of the motor Initialization means for controlling the rotation of the motor within the rotation range corresponding to the movable range of the lens from the rotation amount corresponding to the movable range of the lens and the rotation amount corresponding to the movable range of the motor. Adjust the position of the lens and, the end point detection in end point detection means, and characterized by being performed based on the value of the command signal in the speed control means.

  The end point detecting means detects the end point by comparing the value of the command signal with a threshold value, for example. Alternatively, the end point detection means detects the end point by monitoring increase / decrease in the value of the command signal, for example. The actual rotation speed is monitored based on, for example, the number of reference clocks counted during a predetermined rotation of the motor.

  In the initialization unit, it is preferable that the correspondence between the lens movable range and the motor rotation amount is specified on the assumption that the center of the lens movable range coincides with the center of the motor movable range. It is preferable that a margin area is provided on both sides of the rotation range corresponding to the movable range of the lens whose rotation of the motor is controlled.

  The motor is preferably a sensorless DC brushless motor or a DC brushless motor in order to reduce the size. In the case of a sensorless DC brushless motor, the rotation of the motor is preferably detected using a pulse signal generated based on an induced electromotive force of one phase.

  The lens position adjustment mechanism is, for example, a lens position adjustment mechanism for zooming. At this time, it is preferable that the lens is positioned at the zoom-out side end of the movable range of the lens at the end of the initialization operation.

  According to the present invention, in an electronic endoscope apparatus that drives a lens using a torque wire, it is possible to reduce the diameter of an insertion portion and perform lens position control with high accuracy with a simple and small configuration. it can.

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. 4 is a timing chart showing the relationship between a single rotation detection signal FG and a reference clock (pulse) signal CLK output at a constant period. It is a control block diagram in connection with the speed control of a motor. 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. It is a graph which shows the change of the motor rotation frequency after the rotation of a motor is started until a torque wire is twisted and stops, and the change of a motor command voltage. It is a flowchart of Tele / Wide end detection processing 1 in the first embodiment. It is a graph which shows the change of the motor rotation frequency after the rotation of a motor is started until a torque wire is twisted and stops, and the change of a motor command voltage. It is a flowchart of Tele / Wide end detection processing 2 in the second 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 body 11 includes a flexible tube, an insertion portion 13 that is inserted into a body or a tube hole, an operation portion 14 that is gripped / 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 reduction gear 23. 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 DC brushless motor, and a three-phase drive signal (U, V, W) sent from the motor drive circuit 24 provided in the connector unit 15 via the universal cord 16 (see FIG. 1). ). 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 a startup sequence of the motor 22 and digital values of U, V, and W phases to be given to the motor 22, and the drive circuit 33, based on the digital values, 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 (or FPGA) 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. FIG. 5 is a timing chart showing the relationship between the one-rotation detection signal FG and the reference clock (pulse) signal CLK. In the reference clock counting circuit 37, every time the motor 22 makes one rotation and the rising edge of the FG pulse is detected. In addition, the number of clock pulses during that time is counted, and the number of pulses of the reference clock signal CLK during one rotation is output to the microcomputer 36 (note that the falling edge of the FG pulse may be used).

  The count value of the reference clock signal CLK counted by the reference clock counting circuit 37 is proportional to the time required for the motor 22 to make one rotation. That is, the rotation frequency corresponds to the reciprocal of the count value of the reference clock signal CLK. Therefore, the microcomputer 36 can monitor the rotation frequency, that is, the rotation speed, from the count value of the reference clock counting circuit 37.

  Next, the speed control of the motor 22 in this embodiment will be described with reference to FIG. FIG. 6 is a control block diagram related to the speed control of the motor 22. In the speed control of the motor 22 of the present embodiment, the voltage applied to the motor 22 is controlled so as to maintain the rotation speed at the target frequency (rotation speed) v. As described above, the phase detection circuit 34 generates the one rotation detection signal FG (block 40), and the microcomputer 36 calculates the rotation frequency vf of the motor 22 from the one rotation detection signal FG and the reference clock signal CLK (block 41). ), Used as a feedback signal.

  That is, the deviation between the target rotational frequency (target speed) v and the rotational frequency vf of the motor 22 is output from, for example, the microcomputer 36 to the three-phase sensorless motor control logic circuit 32. P and integration operation I are performed (block 42), and a digital value Mv indicating the voltage value applied to the UVW phase of the motor 22 is calculated. Further, the digital value Mv is limited to a predetermined value (upper limit value) or less by a limiter (block 43) provided in the three-phase sensorless motor control logic circuit 32, and at a timing for each UVW phase according to the rotation direction. It is output to the drive circuit 33.

  In the drive circuit 33, the value of the digital value Mv is converted into a voltage that is actually applied to each of the UVW phases of the motor 22 (block 44), and output to each UVW phase of the motor 22 at the timing shown in FIG. Is done. At this time, as described with reference to FIG. 3, each UVW phase terminal voltage of the motor 22 is input to the phase detection circuit 34, and the phase of the motor 22 is detected (block 40). Generated. In the above control, the reference clock counting circuit 37 can be incorporated in the three-phase sensorless motor control logic circuit 32 and, for example, only the target rotational speed can be input from the microcomputer 36. (Or FPGA) 36, and various arrangements and configurations are possible.

  With the above configuration, the motor 22 is controlled to rotate at a set predetermined rotation frequency. For example, the voltage applied to the motor 22 increases or decreases as the load torque increases or decreases. Also, the applied voltage is limited by the limiter so as not to exceed a predetermined voltage.

  Next, with reference to FIGS. 7 and 8, the lens position initialization operation in the present embodiment will be described. FIG. 7 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. 8 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. 7, 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 region (rotatable range) of the motor 22 including displacement due to torsion of the torque wire 21, and section A3 shows the rotation ratio of the motor 22 and the cam ring 19 (gear including gears 20 and 23). The rotation range of the motor 22 corresponding to the movable range of the cam ring 19 calculated from the 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 <b> 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 the point P0 in FIG. 7 at the time of activation, in the initialization operation processing 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. The center of A3 coincides with the centers of points P1 and P2. From this, in the initialization operation of the present embodiment, in step S110, the position P3 moved by 90 pulses (60 pulses which is half of the movable range A3 + 30 margins on the wide side) from the center between the end points P1 and P2 to the Wide side. Is the origin in the lens position control process, and the motor 22 is rotated to this position.

  That is, the motor 22 is rotated again from the Wide end point P2 to the Tele side, and the total number of pulses between the end points P1 and P2 is subtracted from the number of pulses in the half section of the cam ring movable range A3 and the number of pulses in the Wide side margin. The rotation of the motor 22 is returned as many times as the number of pulses, and the count value of the FG pulse at this time is stored in the nonvolatile memory or the like as the position information, and the initialization operation process ends.

  Thereafter, with the point P3 as the origin, lens position control is executed in the section A2 based on the operation of the Tele / Wide switches 26 and 27, and the count value of the FG pulse is updated and stored in the memory as position information as needed. . It should be noted that when the count number of the one-rotation detection signal FG over the movable range of the cam ring 19 is 118.5, the Tele end side margin is 20 pulses, and the Wide end side margin is 30 pulses, the area used for control (section) A2) is an interval of 168 pulses (20 + 118 + 30).

  Next, with reference to FIG. 9, the principle of endpoint detection in the tele end point and wide end point detection processing (tele / wide end detection processing) of the present embodiment will be described.

  In FIG. 9A, under the control described with reference to FIG. 6, the rotation of the cam ring 19 is stopped by the locking mechanism after the motor 22 starts rotating in the Tele direction or Wide direction. FIG. 6 is a graph schematically showing a change over time in the rotation frequency (rotation speed) of the motor 22 until the torque wire 21 is twisted and the rotation of the motor 22 is substantially stopped. That is, in FIG. 9A, the horizontal axis represents time, and the vertical axis represents the rotation frequency of the motor 22. On the other hand, FIG. 9B is a graph showing a time-series change of the motor command voltage Mv corresponding to the motor control of FIG.

When the rotation of the motor 22 is started, the motor command voltage Mv rises rapidly, and the rotation frequency (rotation speed) also rises rapidly in accordance with this (motor rise time T ₀ ). When the rotational frequency of the motor 22 reaches the target rotational frequency v, the motor command voltage becomes substantially constant, and the rotation is stabilized at the substantially target rotational frequency v. Thereafter, when the cam ring 19 hits the locking mechanism at t _{0 and} the rotation of the cam ring 19 is stopped, the torque wire 21 starts to be twisted and the load torque of the motor 22 starts to increase.

In this case the motor command voltage Mv is increased to maintain the rotational frequency to the target rotational frequency v, between the speed holding area T _1, the motor command voltage Mv increases rapidly. Thereafter, when the torsional torque of the torque wire 21 reaches a predetermined value, the rotational frequency (rotational speed) starts to decrease even when the motor command voltage Mv is increased (section T ₂ ). Actually, motor command voltage Mv is limited to a predetermined value or less by a limiter.

  From the above, in this embodiment, while controlling to keep the rotation frequency of the motor 22 constant, the increase in the motor command voltage is monitored to detect the application to the cam ring, and the Tele side end point P1, The Wide end point P2 is detected.

  Next, with reference to FIG. 9B and FIG. 10, a method for detecting the tele side and wide end points (tele / wide end detection processing 1) according to the first embodiment will be described. FIG. 10 is a flowchart of the Tele / Wide end detection process 1, and the Tele / Wide end detection process 1 in FIG. 10 is a Tele end detection process (Step S102) and a Wide end detection process (Step S108) in FIG. It corresponds to both.

  As shown in FIG. 9B, in the first embodiment, when the command voltage Mv of the motor 22 increases and reaches the predetermined command voltage Mvc, the end points (detection points) P1 and P2 are reached. To do.

  As shown in FIG. 10, first, in step S200, it is determined whether or not an FG pulse has been detected, and a standby state is maintained from the start of rotation of the motor 22 until the first FG pulse is detected. . When the first FG pulse is detected after the motor 22 is started, the value of the motor command voltage Mv is updated in the microcomputer 36 (FIG. 3) in step S202. That is, in the present embodiment, the motor command voltage Mv is input from the three-phase sensorless motor control logic circuit 32 shown in FIG.

  In step S204, it is determined whether or not the motor command voltage Mv is greater than a predetermined value (threshold value) Mvc. The rotational frequency threshold Mvc is set by examining the behavior of the motor 22 in the vicinity of the end in the section where the torque wire is twisted. When the motor command voltage Mv is less than or equal to the predetermined value Mvc, it cannot be said that the end point has been reached yet, the process returns to step S202, and the motor command voltage Mv is updated.

  The processing in steps S202 and 204 is continued until it is determined in step S204 that motor command voltage Mv is larger than threshold value Mvc. When Mv> Mvc, it means that the load torque of the motor 22 has reached a certain value or more, and it is determined that the end point P1 or P2 has been reached. That is, in step S206, the drive of the motor 22 is stopped, and this Tele / Wide end detection process 1 ends.

  As described above, according to the first embodiment of the present invention, while using a sensorless and DC brushless motor, the rotation of the motor is grasped with a simple configuration, and the cam ring or lens is taken into consideration in consideration of the twist of the wire. Since it is possible to take correspondence with the position, it is possible to control the lens position with high accuracy without providing a sensor at the distal end of the insertion portion, to reduce the diameter of the insertion portion, and to reduce the size of the drive portion. Can be planned.

  Moreover, in this embodiment, since the load increase of a torque wire can be detected by monitoring a motor command voltage, the position where a cam ring is applied can be detected more accurately. Thereby, it is possible to detect the end point without overloading the torque wire, and it is possible to suppress the burden on the motor and the torque wire related to the end point detection and to improve the durability.

  Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is different from the first embodiment only in the method for detecting the tele end point and the wide end point, and the mechanical and electrical configuration is the same as that of the first embodiment, and the description thereof is omitted.

  FIG. 11 corresponds to FIG. 9 in the first embodiment, and FIG. 11A is a graph showing a temporal change in the rotational frequency of the motor 22 from the start of driving of the motor 22 to one end point. FIG. 11B is a graph showing a change in the motor command voltage Mv at that time. In the first embodiment, only the current motor command voltage Mv is monitored, but in the second embodiment, the end point is detected by monitoring the difference value of the motor command voltage Mv. That is, as shown in FIG. 11B, an end point is detected by detecting an increase in the value of the motor command voltage Mv.

  FIG. 12 is a flowchart of Tele / Wide end detection processing 2 employed in the second embodiment. In step S300, as in step S200 (FIG. 10) of the first embodiment, it is determined whether or not the first FG pulse since the start of rotation of the motor 22 has been detected (waveform rising or falling). This process is repeated until the first FG pulse is detected.

Next, in step S302, the values of the four motor command voltages Mv ₀ , Mv ₋₁ , Mv ₋₂ , and Mv _{−3 in} the microcomputer 36 are continuously updated until the condition of step S304 is satisfied. Here, the motor command voltages Mv ₀ , Mv ₋₁ , Mv ₋₂ , Mv ₋₃ are values of the motor command voltage Mv detected in time series, and the subscript 0 represents the latest value, and Mv ₋₁ , Mv _-2 and Mv- ₃ in order of old values.

When the condition of step S304 is satisfied, the drive of the motor 22 is stopped in step S306, and this process is terminated. That is, in the Tele / Wide end detection process 2 of the second embodiment, when the condition of step S304, Mv ₀ > Mv ₋₁ > Mv ₋₂ > Mv ₋₃ is satisfied, that is, the value of the motor command voltage Mv is constant. It is assumed that the end point (P1 or P2) is detected when the period continues to increase monotonously.

In the microcomputer 36, 0 is given as an initial value to Mv ₀ , Mv ₋₁ , Mv ₋₂ , Mv ₋₃ , and in the first step S302, the motor command voltage Mv ₀ is set to the reference clock counting circuit 37 ( When the value from FIG. 3) is input and then the motor command voltage Mv ₀ is updated, the value of the old motor command voltage Mv ₀ is sequentially shifted to Mv ₋₁ , Mv ₋₂ and Mv ₋₃ .

  As described above, also in the second embodiment, the same effect as in the first embodiment can be obtained.

  Note that the number of time-series motor command voltages used in the second embodiment is not limited to four, and may be at least more than this. Further, it is possible to detect an end point from a comparison of differences between a plurality of motor command voltages, and it is also possible to combine these and the methods described in the embodiments.

  In this embodiment, the zoom lens is described as an example. However, the present invention is not limited to driving the zoom lens as long as the lens is driven using a torque wire. In this embodiment, the cam ring is used for driving the lens. However, the present invention can be applied to other conventional methods as long as the configuration uses a torque wire.

  In the present 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, the number of pulses of the reference clock counted during 1 / n rotation can be used 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 (9)

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;
A rotation amount detecting means for detecting rotation of the motor and calculating a rotation amount;
Speed control means for detecting the actual rotational speed of the motor and performing control so that the rotational speed of the motor is constant;
End point detecting means for detecting an end point of the movable range of the motor;
An initialization means for driving the motor from one end of the movable range of the motor detected by the end point detection means to the other end, and detecting a rotation amount corresponding to the movable range of the motor;
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. Done
The lens position control device for an electronic endoscope, wherein the detection of the end point in the end point detection unit is performed based on a value of a command signal in the speed control unit.   2. The lens position control device for an electronic endoscope according to claim 1, wherein the end point detecting means detects the end point by comparing the value of the command signal with a threshold value.   2. The lens position control device for an electronic endoscope according to claim 1, wherein the end point detection means detects the end point by monitoring an increase or decrease in the value of the command signal.   5. The lens position of the electronic endoscope according to claim 3, wherein the actual rotation speed is monitored based on a number of reference clocks counted while the motor rotates a predetermined amount. Control device.   The initialization means specifies the correspondence between the movable range of the lens and the rotation amount of the motor, assuming that the center of the movable range of the lens coincides with the center of the movable range of the motor. The lens position control device for an electronic endoscope according to any one of 3 and 4.   6. The lens position control device for an electronic endoscope according to claim 5, wherein regions serving as margins are provided on both sides of the rotation range corresponding to the movable range of the lens for which the rotation of the motor is controlled.   The said motor is a sensorless DC motor, The rotation of the said motor is detected using the pulse signal produced | generated based on the induced electromotive force of one phase. The lens position control apparatus of the electronic endoscope as described.   The lens position control device for an electronic endoscope according to any one of claims 1 to 7, wherein the lens position adjustment mechanism is a lens position adjustment mechanism for zooming. 9. The lens position control device for an electronic endoscope according to claim 8, wherein at the end of the initialization operation, the lens is positioned at an end of the movable range of the lens on the zoom-out side.

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