JP2006242678A - Rotational position detector and endoscope device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the rotational position of a rotating body at all times and to rapidly and accurately position the rotating body in a state of rotation at a prescribed position. <P>SOLUTION: This electronic endoscope device employs an imaging method wherein a rotary shutter 15 is provided between a lamp 12 and an incident end 51A of a light guide 51, and is rotated at a constant speed so as to adjust exposure periods. When a videoscope having an electronic shutter function is connected thereto, the rotational position (angle) of its rotary shutter 15 is detected by a rotational position detection sensor 32 in order to position the rotary shutter 15 at a prescribed rotational position. An ND filter is formed on the periphery of the detection sensor 32, the ND filter having a spectral transmission characteristic and continuously changing the level of a detection signal according to its rotational position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sensor that detects the position of a rotating body driven by a motor or the like, and more particularly to an apparatus that detects the rotational position (angle) of a rotating body using an optical sensor.

  When a rotating body is rotated by an actuator such as a motor, a photo-type rotary encoder is attached for speed detection and position detection. The rotary encoder includes a photo interrupter and a slit disk in which a light receiving unit and a light emitting unit are integrated. When the slit rotates around the rotation axis, light intermittently reaches the light interrupting unit of the photo interrupter, and a pulse signal Will occur. Based on the A-phase, B-phase, and Z-phase pulse signals, the rotational position and amount of rotation of the rotating body are detected (see Patent Document 1). Further, when a rotational position sensor such as a potentiometer is used, the rotational position sensor is attached to the rotation shaft.

  When a rotary body is positioned at a specific position using a rotary encoder, the rotational position is detected based on the Z-phase pulse signal, but the Z-phase pulse signal is detected only once per rotation. For this reason, a state in which the rotation state continues for a while occurs due to the detection of the Z-phase pulse signal, and stationary control from the rotation state cannot be performed quickly. In addition, when the rotational position sensor is mounted coaxially, a signal is detected only at a specific rotational position, and the sensor itself also requires durability because of rotation, and further requires space in the direction of the rotational axis.

  The rotational position detection device of the present invention is a device that detects the rotational position of a rotating body that is rotated by a motor or the like, and is particularly a device that can be used when positioning from a rotational state to a predetermined position. The rotational position detection device receives a light passing through the light transmitting unit, a light emitting unit that emits light toward the light transmitting medium of the rotating body, and outputs a detection signal having a level corresponding to the amount of received light. And a rotational position detecting means for detecting the rotational position of the rotating body based on the detection signal output from the light receiving unit. The light transmission medium is formed so as to make one turn along the circumferential direction. For example, a motor is coaxially connected to the rotating body, and is rotated as necessary. The light emitting unit is configured by, for example, a laser diode (LD), and the light receiving unit is configured by, for example, a photodiode (PD).

  The spectral transmission characteristics of the light transmission medium in the present invention continuously vary depending on the rotational position, and the light transmission is performed so that the level of the detection signal output from the light receiving unit changes in a one-to-one correspondence relationship depending on the rotational position. The spectral transmission characteristics of the medium are defined. Here, “continuously” means outputting a non-intermittent signal such as a pulse signal, and “one-to-one correspondence” means that the detection signal level differs for each rotational position (angle). To express. For example, the spectral transmission characteristic may increase as long as the angle increases while maintaining linearity. In this case, the intensity of the light reaching the light receiving unit continuously increases while maintaining linearity, and the level of the detection signal follows a distribution along the rotation position of the light intensity.

  While the rotating body is rotating, a continuous detection signal is obtained, and the rotational position of the rotating body is always detected. And it can be made to stop instantaneously from a rotation state, and a rotary body is predetermined-positioned by feedback control.

  For example, the light transmission medium includes a neutral density (ND) filter. In order to arrange the light receiving unit and the light emitting unit with a simple configuration, it is desirable that the light transmission medium be formed along the circumference.

  In the rotational position detection device as another feature of the present invention, a light reflecting medium is formed in the rotating body so as to make one turn along the circumferential direction, and light is emitted toward the light reflecting medium of the rotating body. A light-emitting unit, a light-receiving unit that receives light reflected by the light reflecting medium, outputs a detection signal at a level corresponding to the amount of received light, and detects the rotational position of the rotating body based on the detection signal output from the light-receiving unit And a rotational position detecting means that continuously varies the light reflection characteristics of the light reflecting medium according to the rotational position, and the level of the detection signal output from the light receiving unit changes in a one-to-one correspondence according to the rotational position. As described above, the light reflection characteristics of the light reflection medium are defined. The light reflecting medium is configured by, for example, covering a light absorbing material on a surface coated with a metallic material.

  An endoscope apparatus according to the present invention is an endoscope apparatus whose brightness can be adjusted by either mechanical control or an electronic shutter, and a light source that emits illumination light toward a distal end portion of a videoscope having an image sensor. The rotary shutter is arranged in the optical path of the illumination light and is formed with an opening and a light shielding portion so as to adjust the exposure time by alternately passing and blocking the illumination light, and the rotational position of the rotary shutter is detected. A rotational position detector. The rotary shutter has a light transmission medium formed so as to make one turn along the circumferential direction. The rotational position detection unit includes a light emitting unit that emits light toward the light transmitting medium of the rotating body, a light receiving unit that receives light passing through the light transmitting medium, and outputs a detection signal at a level corresponding to the amount of received light. And a rotational position detecting means for detecting the rotational position of the rotating body based on the detection signal output from the light receiving unit. The spectral transmission characteristics of the light transmission medium continuously vary depending on the rotation position, and the spectral characteristics of the light transmission medium are changed so that the level of the detection signal output from the light receiving unit changes in a one-to-one correspondence according to the rotation position. Transmission characteristics are defined. When the electronic shutter function is used, the rotary shutter is controlled so that the rotary shutter is positioned at a predetermined position.

  In order to automatically switch according to the scope, a determination means for determining whether or not the video scope to be used has an electronic shutter function, and when the video scope has an electronic shutter function, the illumination light is continuously irradiated to the subject. It is preferable to further provide a rotary shutter control means for positioning the rotary shutter to a predetermined position.

  An endoscope apparatus according to the present invention is arranged in a light source that emits illumination light toward a distal end portion of a videoscope having an image sensor, and an exposure time by alternately passing and blocking illumination light, which is disposed in an optical path of the illumination light. A rotary shutter formed with an opening and a light-shielding part, and a rotational position detector for detecting the rotational position of the rotary shutter, so that the rotary shutter makes one turn along the circumferential direction. A rotating position detector that emits light toward the rotating light reflecting medium; and a light that is reflected by the light reflecting medium. A light receiving unit that outputs a level detection signal, and a rotational position detection unit that detects the rotational position of the rotating body based on the detection signal output from the light receiving unit. The light reflection characteristics of the light reflection medium are such that the light reflection characteristics of the light reflection medium continuously vary depending on the rotation position, and the level of the detection signal output from the light receiving unit changes in a one-to-one correspondence according to the rotation position. The characteristic is defined.

  The rotational position of the rotating body can be detected at all times, and the rotating body can be quickly and accurately positioned from the rotating state to a predetermined position.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of an electronic endoscope apparatus according to this embodiment.

  The electronic endoscope apparatus includes a video scope 50 having a CCD 54 and a processor 10 that processes a pixel signal read from the CCD 54 and is integrally provided with a light source unit. The video scope 50 is detachably connected to the processor 10, and a monitor 52 that displays a subject image is connected to the processor 10.

  When a lamp lighting switch (not shown) is turned on, power is supplied from the lamp controller 11 to the lamp 12 and the lamp 12 is lit. The light emitted from the lamp 12 enters the incident end 51 </ b> A of the light guide 51 provided in the video scope 50 via the rotary shutter 15 and the condenser lens 16. The light guide 51 is an optical fiber bundle that transmits the light emitted from the lamp 12 to the distal end side of the video scope 50. The light that has passed through the light guide 51 is emitted from the emission end 51B, and is a light distribution lens (diffuse lens). Light is irradiated to the observation site via a not shown).

  The light reflected at the observation site reaches the CCD 54 through an objective lens (not shown), and an image of the observation site is formed on the light receiving surface of the CCD 54. In this embodiment, a single-plate simultaneous type and a color difference line sequential method are applied as color imaging methods, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) are provided on the light receiving surface of the CCD. Complementary color filters (not shown) in which the color elements are arranged in a checkered pattern are arranged so as to correspond to the respective pixels on the light receiving surface. In the CCD 54 having a light-shielded charge storage unit, a pixel signal of a subject image corresponding to a color passing through a complementary color filter is generated by photoelectric conversion.

  For example, the NTSC system is applied as a color television system, and when a moving image is displayed on the monitor 52, field reading is performed and according to a drive signal sent from the CCD driver 59 every 1/60 second time interval. In the state where adjacent pixels are added to each other, the image signals of the odd field and the even field are sequentially read out and sent to the amplifier circuit 55. Note that the PAL method may be applied.

  In the amplification circuit 55, the pixel signal is subjected to amplification processing and the like, and sent to the initial signal processing circuit 57 as an image elementary signal. In the initial signal processing circuit 57, predetermined processing is performed on the image signal, and the image signal is sent to the processor-side signal processing circuit 28 of the processor 10.

  The processor-side signal processing circuit 28 performs various processes such as white balance adjustment and gamma correction on the image signal sent from the initial signal processing circuit 57 to generate an analog video signal. The analog video signal is output to the monitor 52, whereby the observation image is displayed on the monitor 52 as a moving image.

  A system control circuit 22 including a CPU controls the operation of the processor 10 and outputs a control signal to each circuit such as the lamp control unit 11 and the processor side signal processing circuit 28. In a timing control circuit (not shown) on the processor side, a clock pulse signal for adjusting the processing timing of the signal is output to each circuit in the processor 10, and a synchronization signal accompanying the video signal is a processor side signal processing circuit. 28.

  The video scope 50 is provided with a scope controller 56 that controls the video scope 50 and controls an initial signal processing circuit 57 and a timing control circuit 58. The timing control circuit 58 outputs a drive signal to the CCD driver 59 based on the control signal sent from the scope controller 56 and controls the pixel signal reading process of the CCD 54. When the video scope 50 is connected to the processor 10, data is transmitted and received between the scope controller 56 and the system control circuit 22.

  A rotary shutter 15 for adjusting the exposure period is provided between the lamp 12 and the condenser lens 16, and a stepping motor (not shown) is attached to the central axis of the rotary shutter 15. As the motor rotates based on the drive signal sent from the motor driver 23, the rotary shutter 15 rotates at a constant speed. A rotation position detection sensor 32 is provided around the rotary shutter 15 to detect the rotation position of the rotary shutter 15.

  FIG. 2 is a plan view of the rotary shutter. FIG. 3 is a plan view of the rotational position detection sensor.

  The rotary shutter 15 is a member that rotates about a shaft 15T, and a semicircular portion 15P is configured by a pair of an opening 15A that transmits illumination light and a light shielding portion 15B that blocks illumination light. The semicircular portion 15P corresponds to one field period (1/60 seconds in the NTSC system), and the rotary shutter 15 makes one rotation in one frame readout period (1/30 seconds in the NTSC system) and is emitted from the lamp 12. The opening 15A and the light shielding part 15B pass one after another on the optical path LB of the illumination light. As a result, light transmission and light shielding are repeated twice over one frame readout period, and pixel signals for one field accumulated by the exposure time defined by the size of the opening 15A are sequentially output from the CCD 54. . An exposure period and a light shielding period are provided in one field period, and the size of the opening 15A can be varied according to the required exposure time. Brightness adjustment is performed.

  A ring-shaped ND filter 15Q is formed on the rotary shutter 15P, and is attached concentrically along the outer peripheries of the opening 15A and the light shielding portion 15B. The substantially U-shaped rotational position detection sensor 32 is fixedly disposed at a predetermined location so as to sandwich the ND filter 15Q. As shown in FIG. 3, the rotational position detection sensor 32 includes an LD (laser diode) light emitting unit 34 and a photodiode (PD) light receiving unit 36, and the light emitting unit 34 and the light receiving unit 36 are ND filters. Opposite via 15Q. The light emitted from the light emitting unit 34 is incident on the ND filter 15Q while being collected by the condenser lens 35. The light that has passed through the ND filter 15Q having a dimming effect reaches the light receiving surface of the light receiving unit 36 through the light blocking aperture 37.

  FIG. 4 is a diagram showing the light absorption power distribution (spectral transmission characteristics) of the ND filter 15Q. The vertical axis indicates the intensity of transmitted light, and the horizontal axis indicates an angle (rotational position) from a predetermined reference position.

  As shown in FIG. 4, the spectral transmission characteristic of the ND filter 15Q can be represented by a straight line K, and increases while maintaining linearity according to the rotational position. This indicates that the spectral transmission characteristics change continuously according to each rotational position, and the intensity of light reaching the light receiving unit 36 varies depending on the rotational position of the rotary shutter 15Q (in a one-to-one correspondence relationship). ). As a result, the level of the detection signal output from the light receiving unit 36 also varies depending on the position of the rotary shutter 15Q, and the rotational position is uniquely detected based on the level of the detection signal.

  FIG. 5 is a flowchart showing a control process for the rotary shutter 15.

  In step S101, it is determined whether or not a video scope is connected. If it is determined that the video scope is not connected, the process proceeds to step S104, and the rotary shutter rotation command is turned ON so that the rotary shutter 15 is rotated. On the other hand, if it is determined that the video scope is connected, the process proceeds to step S102.

  In step S102, it is determined whether or not the connected video scope is a video scope having an electronic shutter function. That is, it is determined whether or not the video scope uses an electronic shutter function for adjusting the brightness of the subject image.

  If it is determined in step S102 that the connected video scope is not a video scope having an electronic shutter function, the process proceeds to step S104, and the rotary shutter 15 is controlled to rotate as described above. At this time, the rotary shutter control system is changed from position control to rotational speed control, and rotational speed control is performed based on the output of the motor pulse encoder. Then, the process returns to step 101. On the other hand, if it is determined that the connected video scope is a video scope having an electronic shutter function, the process proceeds to step S103.

  In step S103, the rotary shutter stop command is turned ON to stop the rotary shutter. When the rotary shutter stationary command is turned ON, the rotary shutter control system is changed from rotational speed control to position control, and the rotary shutter 15 is moved so that the opening 15A is positioned in the optical path LB in order to irradiate the subject with continuous light. Operation controlled. At this time, based on a detection signal from the rotational position detection sensor 32, a comparison with a target value is performed, and feedback control is performed so as to stop at the target position. Then, the process returns to step 101.

  As described above, according to the present embodiment, the rotary shutter 15 is provided between the lamp 12 and the incident end 51A of the light guide 51, and the rotary shutter 15 is adjusted at a speed corresponding to the color television system while adjusting the exposure period. Rotate. When a video scope having an electronic shutter function is connected, the rotary shutter 15 is controlled to be positioned at a predetermined rotational position. At this time, the rotational position (angle) is detected by the rotational position detection sensor 32.

  Due to the spectral transmission characteristics of the ND filter 15Q, the level of the detection signal continuously changes according to the rotational position. Therefore, a detection signal of a level corresponding to the rotational position is detected at any rotational position, and feedback control is quickly and accurately executed in the positioning control of the rotary shutter 15. Further, the rotational position detection sensor 32 can be reduced in size, and the rotational position detection sensor can be arranged without taking a space in the rotational axis direction.

  Next, an electronic endoscope apparatus according to the second embodiment will be described with reference to FIG. In the second embodiment, a reflective rotational position detection sensor is provided. About another structure, it is the same as 1st Embodiment.

  FIG. 6 is a plan view showing a reflective rotational position detection sensor. FIG. 7 is a diagram showing the reflection intensity distribution of the light reflecting medium.

  On the outer periphery of the rotary shutter 15, a ring-shaped light reflecting medium 15Q 'is formed. A metal material is applied to the surface of the light reflecting medium 15Q ', and is further covered with a predetermined light absorbing material. The light reflection intensity distribution of the reflection medium 15Q ′ can be represented by a straight line K ′ (see FIG. 7) having continuous linearity similar to that in FIG.

  The rotational position detection sensor 32 ′ is disposed above the rotary shutter 15 so as to face the light reflecting medium 15Q ′, and has a light emitting unit 34 ′ having a condensing lens 35 ′ and a light receiving unit 36 having an aperture 37 ′. It consists of 'and. The light emitted from the light emitting section 34 'is reflected by the reflection medium 15Q' with a reflection intensity corresponding to the reflection intensity distribution of the light of the reflection medium 15Q ', and reaches the light receiving section 36'. Then, the rotational position of the rotary shutter 15 is detected according to the level of the detection signal output from the light receiving unit 36 '.

  The ND filter 15Q and the light reflection medium 15Q 'may be formed concentrically in a region close to the axis instead of being formed along the outer periphery of the rotary shutter 15. A light transmission medium other than the ND filter may be applied, and a material having the characteristics shown in FIG. 4 may be selected for the light reflection medium. Furthermore, it may be non-linear light transmission characteristics or light reflection characteristics as represented by a curve instead of linearity. A continuous signal can be detected, and the detection signal may be uniquely output according to each rotational position.

  The rotational position detection sensor 32 may be applied to a rotating body used in addition to an electronic endoscope device.

It is a block diagram of the electronic endoscope apparatus which is this embodiment. It is a top view of a rotary shutter. It is a top view of a rotation position detection sensor. It is the figure which showed distribution (spectral transmission characteristic) of the light absorption power of ND filter. It is the flowchart which showed the control processing with respect to a rotary shutter. It is the top view which showed the reflection type rotational position detection sensor. It is the figure which showed the reflection intensity distribution of the light reflection medium.

Explanation of symbols

10 processor 12 lamp (light source)
15 Rotary shutter (Rotating body)
15Q ND filter (light transmission medium)
15Q 'light reflection medium 32 rotational position detection sensor 34 light emitting part 36 light receiving part 50 video scope 54 CCD (imaging device)

Claims (13)

A rotating body having a light transmission medium formed so as to make one turn along a circumferential direction;
A light emitting unit that emits light toward the light transmission medium;
A light receiving unit that receives light passing through the light transmission medium and outputs a detection signal of a level corresponding to the amount of received light;
A rotation position detecting means for detecting a rotation position of the rotating body based on a detection signal output from the light receiving unit;
The spectral transmission characteristics of the light transmission medium are continuously different depending on the rotational position,
The rotational position detecting device characterized in that the spectral transmission characteristics of the light transmission medium are determined so that the level of the detection signal output from the light receiving section changes in a one-to-one correspondence according to the rotational position. A rotating body having a light reflecting medium formed so as to make one turn along a circumferential direction;
A light emitting unit for emitting light toward the light reflecting medium;
A light receiving unit that receives light reflected by the light reflecting medium and outputs a detection signal at a level corresponding to the amount of received light;
A rotation position detecting means for detecting a rotation position of the rotating body based on a detection signal output from the light receiving unit;
The light reflection characteristics of the light reflecting medium are continuously different depending on the rotational position,
The rotational position detection device characterized in that the light reflection characteristics of the light reflection medium are determined so that the level of the detection signal output from the light receiving unit changes in a one-to-one correspondence according to the rotational position.   The rotational position detection device according to claim 1, wherein spectral transmission characteristics of the light transmission medium are determined so that a level of a detection signal output from the light receiving unit maintains linearity.   The rotational position detection device according to claim 2, wherein a light reflection characteristic of the light transmission medium is determined so that a level of a detection signal output from the light receiving unit maintains linearity.   The rotational position detection device according to claim 1, wherein the light transmission medium is a neutral density (ND) filter.   The rotational position detection device according to claim 2, wherein the light reflecting medium is configured by covering a light absorbing material on a surface coated with a metallic material.   The rotational position detection device according to claim 1, wherein the light transmission medium is formed along a circumference.   The rotational position detection device according to claim 2, wherein the light reflection medium is formed along a circumference. A rotating body having a light transmission medium formed so as to make a round along a circumferential direction,
The spectral transmission characteristics of the light transmission medium differ depending on the rotational position,
The spectral transmission characteristic of the light transmission medium is determined so that the level of a detection signal output from the light receiving unit for light detection continuously changes in a one-to-one correspondence according to the rotational position. A rotating body of the rotational position detecting device. A rotating body having a light reflecting medium formed so as to make one turn along a circumferential direction,
The light reflection characteristics of the light reflecting medium differ depending on the rotational position,
The light reflection characteristic of the light reflection medium is determined so that the level of the detection signal output from the light receiving unit for light detection continuously changes in a one-to-one correspondence according to the rotational position. A rotating body of the rotational position detecting device. A light source that emits illumination light toward the distal end of a videoscope having an image sensor;
A rotary shutter that is arranged in the optical path of the illumination light, and in which an opening and a light shielding part are formed so as to adjust the exposure time by alternately passing and blocking the illumination light;
A rotational position detector that detects a rotational position of the rotary shutter;
The rotary shutter has a light transmission medium formed so as to make one turn along a circumferential direction;
The rotational position detector is
A light emitting unit that emits light toward the light transmission medium;
A light receiving unit that receives light passing through the light transmission medium and outputs a detection signal of a level corresponding to the amount of received light;
A rotational position detecting means for detecting a rotational position of the rotating body based on a detection signal output from the light receiving unit;
The spectral transmission characteristics of the light transmission medium are continuously different depending on the rotational position,
An endoscope apparatus, wherein spectral transmission characteristics of the light transmission medium are determined so that a level of a detection signal output from the light receiving unit changes in a one-to-one correspondence according to a rotation position. A light source that emits illumination light toward the distal end of a videoscope having an image sensor;
A rotary shutter that is arranged in the optical path of the illumination light, and in which an opening and a light shielding part are formed so as to adjust the exposure time by alternately passing and blocking the illumination light;
A rotational position detector that detects a rotational position of the rotary shutter;
The rotary shutter has a light reflecting medium formed so as to make one turn along a circumferential direction;
The rotational position detector is
A light emitting unit for emitting light toward the light reflecting medium;
A light receiving unit that receives light reflected by the light reflecting medium and outputs a detection signal at a level corresponding to the amount of received light;
A rotational position detecting means for detecting a rotational position of the rotating body based on a detection signal output from the light receiving unit;
The light reflection characteristics of the light reflecting medium are continuously different depending on the rotational position,
An endoscope apparatus, wherein light reflection characteristics of the light reflection medium are determined so that a level of a detection signal output from the light receiving unit changes in a one-to-one correspondence according to a rotation position. A discriminating means for discriminating whether or not the video scope used has an electronic shutter function;
12. The rotary shutter control means for positioning the rotary shutter at a predetermined position so as to continuously irradiate the subject with illumination light when the video scope has an electronic shutter function. The endoscope apparatus according to claim 12.

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