JP2008009261A - Focus adjusting mechanism and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To rapidly and accurately adjust the focal position of a lens regardless of the resolving power and the brightness of the lens. <P>SOLUTION: The focus adjusting mechanism is equipped with: a first adjusting mechanism which moves a lens holding frame 206 holding the lens 101 in an optical axis direction relative to a main lens barrel 201 holding the lens holding frame 206 movably in the optical axis direction with the rotation of a focus ring 105 relative to the main lens barrel 201; and a second adjusting mechanism which abuts on a sub lens barrel comprising the focus ring 105 and a first lens barrel 203 in the optical axis direction and moves the sub lens barrel in the optical axis direction relative to the main lens barrel 201 with the rotation of a fine adjustment ring 106 provided to freely rotate around an optical axis relative to the main lens barrel 201. The moving amount of the lens holding frame 206 in accordance with the rotational amount of the fine adjustment ring 106 relative to the main lens barrel 201 is set to be smaller than that of the lens holding frame 206 in accordance with the rotational amount of the focus ring 105 relative to the main lens barrel 201. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a focus adjustment mechanism and an imaging apparatus.

  2. Description of the Related Art Conventionally, there is an image pickup apparatus that converts external light imaged on a CCD using a lens into an electric signal and stores it in a storage medium as digital data. Such an imaging apparatus includes a focus adjustment mechanism that adjusts the position of the lens on the optical axis and adjusts the focus of the lens by positioning the focal position of the image formed by the lens on the imaging surface of the CCD. ing.

  There are a plurality of types of adjustment methods in the focus adjustment mechanism as described above. Among them, for example, in a focus adjustment mechanism of an imaging apparatus equipped with a varifocal lens that is a variable focus lens capable of continuously changing the magnification, a coma member attached to a lens holding frame that holds the lens is used with an optical axis. By engaging with a spiral cam groove provided on the inner peripheral surface of the focus ring as an axis, and rotating the focus ring around the optical axis to change the engagement position of the top member with respect to the cam groove, the optical axis There is one that moves the lens in the direction to adjust the focal position of the lens.

  In the varifocal lens, an operator adjusts the focal position of the lens by manually rotating the focus ring to move the lens in the optical axis direction. When adjusting the focus position of a lens using such a focus adjustment mechanism, it is necessary to rotate the focus ring by a minute amount near the focus position in order to position the lens at the position where the focus of the lens is the most accurate. is there.

  Among the focus adjustment mechanisms described above, for example, in a focus adjustment mechanism of an imaging apparatus including an FA (factory automation) lens, the lens is moved in the optical axis direction using an electronically controlled motor, and the focal position of the lens is adjusted. Some have been adjusted. In the FA lens, for example, a cylindrical lens barrel positioned inside the support barrel is connected to a helicoid provided on the inner peripheral surface of the cylindrical support barrel by a screw mechanism, and provided on the support barrel. There is a linear helicoid mechanism that moves the lens only in the optical axis direction by screwing a screw into the lens barrel from the outer peripheral side of the support barrel through an opening that opens with the optical axis direction as the longitudinal direction. Used.

  In the conventional varifocal lens as described above, a lens having an F value of 1.3 or more is often used, and a lens with a particularly shallow depth of field is not used. Even in focus adjustment in which the ring is rotated around the optical axis to adjust the focus of the lens, defects in optical performance such as out-of-focus (so-called “out-of-focus”) tend not to occur.

  On the other hand, in an imaging apparatus equipped with a CCD having a high pixel count that has been remarkably popular in recent years, it is required to mount a lens having a high resolving power corresponding to the increase in the number of pixels of the CCD. A lens having a high resolving power is called, for example, a megapixel-compatible lens, and has an optical characteristic that the F value is small and the depth of field tends to be shallow. Further, in recent years, there has been an increasing demand for an imaging device equipped with a bright lens for an imaging device equipped with a CCD. In general, a bright lens has an optical characteristic that the F value is small and the depth of field tends to be shallow.

  Further, as a conventional technique, for example, a technique for adjusting the focal position of an image output to a display or the like by correcting image data generated by a CCD, or a support arm having an elastic lens holder for holding a lens. The lens is electronically controlled to apply a voltage to the piezoelectric element provided on the support arm, and the lens is moved in the optical axis direction by elastic deformation of the support arm to perform focus adjustment (for example, (See Patent Document 1 below), or an eccentric pin is engaged with a groove with a lead provided on the outer peripheral surface of a rotatable lens barrel that holds the lens, and the eccentric pin with respect to the groove with the lead is rotated as the lens barrel rotates. There is a technique in which focus adjustment is performed by changing the engagement position (see, for example, Patent Document 2 below).

JP-A-10-301013 JP 2000-75183 A

  A lens having a small F-number and a shallow depth of field has a large focal position shift width associated with the movement of the lens, so that the focal position of the lens needs to be adjusted with high accuracy. As described above, in a varifocal lens that adjusts the focal position of the lens by rotating the focus ring by the operator, when a lens with a shallow depth of field and a high resolution is mounted, the focus is near the focal position. It is necessary to rotate the ring little by little.

  However, there is a limit for the operator to manually adjust a small amount of rotation commensurate with the high resolution of the lens, and the conventional varifocal lens as described above has a small F value and a shallow depth of field. When a lens is mounted, there is a problem that it is difficult to adjust the focal position of the lens with high accuracy. Further, the conventional varifocal lens has a problem in that the adjustment accuracy of the focal position of the lens varies depending on the proficiency level of the operator.

  As a countermeasure, it is possible to improve the adjustment accuracy of the focal position of the lens by reducing the cam groove pitch and reducing the movement amount of the lens with respect to the rotation amount of the focus ring. However, in this case, there is a problem that it takes time to move the lens to the vicinity of the focal position, and the efficiency of adjusting the focal position of the lens is lowered.

  Further, by adjusting the focal position of the lens using electronic control as in the above-described FA lens and the technique described in Patent Document 1, it is possible to improve the adjustment accuracy of the focal position of the lens. However, the varifocal lens, which is positioned in the low-priced market than the FA lens, has a problem that an increase in manufacturing cost by using electronic control is not desirable. In addition, with the increase in the number of pixels of a CCD, there is a problem that there is a limit to adjusting the focal position of an image by correcting image data.

  The present invention provides a focus adjustment mechanism and an imaging apparatus capable of quickly and accurately adjusting the focal position of a lens regardless of the resolution and brightness of the lens in order to eliminate the above-described problems caused by the conventional technology. For the purpose.

  Furthermore, the present invention provides a focus adjustment mechanism and an imaging apparatus that can adjust the focal position of a lens quickly and with high accuracy regardless of the resolution and brightness of the lens while suppressing an increase in manufacturing cost. Objective.

  A focus adjusting mechanism according to the present invention has a cylindrical shape with an optical axis as an axial direction, a main barrel that holds a lens holding frame that holds a lens movably in the optical axis direction, and the optical axis as an axis. With a rotation of the adjustment ring with respect to the main barrel, and a sub-lens barrel having an adjustment ring that has a cylindrical shape as a central direction and is provided to be rotatable about the optical axis with respect to the main barrel. A first adjusting mechanism for moving the lens holding frame in the optical axis direction with respect to the main barrel; and abutting the sub-barrel in the optical axis direction, and around the optical axis with respect to the main barrel An adjustment member that is freely rotatable, and a second adjustment mechanism that moves the auxiliary lens barrel in the optical axis direction with respect to the main lens barrel as the adjustment member rotates. The adjusting mechanism 2 is configured to adjust the rotation amount of the adjusting member relative to the main barrel. The amount of movement of the lens holding frame, the main mirror to be smaller than the moving amount of the lens holding frame corresponding to the rotation amount of the adjustment ring relative to barrel, and wherein the moving the secondary mirror barrel.

  According to the present invention, when the rotation amounts of the adjustment ring and the adjustment member with respect to the main lens barrel are equal, the rotation amount of the lens holding frame accompanying the rotation of the adjustment ring is greater than the movement amount of the lens holding frame in the optical axis direction. Since the movement amount of the lens holding frame in the optical axis direction due to the movement of the secondary lens barrel in the optical axis direction is smaller, the operator rotates the adjustment ring with respect to the main lens barrel to rotate the lens in the optical axis direction. The focus position of the lens can be roughly adjusted and the focus position of the lens in the optical axis direction can be finely adjusted by rotating the adjustment member with respect to the main lens barrel. Can be adjusted quickly and with high accuracy.

  In addition, according to the present invention, since the focal position of the lens in the optical axis direction can be finely adjusted just by rotating the adjustment member in the same manner as the adjustment ring, the lens does not depend on the skill level of the operator. Regardless of the resolution and brightness of the lens, the focal position of the lens can be adjusted quickly and with high accuracy.

  Further, according to the present invention, the focal position of the lens in the optical axis direction can be finely adjusted without correcting the image data for focusing or moving the lens holding frame using a motor. Regardless of the resolving power and brightness of the lens, it is possible to adjust the focal position of the lens quickly and with high accuracy while suppressing an increase in the manufacturing cost of the focus adjustment mechanism and an imaging device equipped with the focus adjustment mechanism.

  In addition, the focus adjustment mechanism according to the present invention includes an urging member that urges the sub-barrel in a direction in contact with the adjustment member.

  According to the present invention, since the secondary lens barrel can be stably brought into contact with the adjustment member, it is possible to suppress the shakiness of the secondary lens barrel in the optical axis direction, regardless of the resolution and brightness of the lens. The focal position of the lens can be adjusted quickly and with high accuracy.

  Further, the first adjustment mechanism in the focus adjustment mechanism of the present invention includes an engagement member that engages at an arbitrary position in a spiral groove provided in the sub-lens barrel with the optical axis as an axis. The lens holding frame is moved in the optical axis direction with respect to the main barrel by changing the position of the engaging member with respect to the groove.

  According to the present invention, since the lens holding frame can be moved in the optical axis direction with respect to the main barrel with a simple configuration, the structure of the varifocal lens can be simplified and the increase in manufacturing cost can be suppressed. Can do.

  Further, the second adjustment mechanism in the focus adjustment mechanism of the present invention is a screw mechanism that connects the main barrel and the adjustment member via a screw, and the screw with respect to the screw pitch or the optical axis direction. The lead angle is adjusted in accordance with the pitch of the groove or the lead angle of the groove with respect to the optical axis direction.

  According to this invention, since the position of the lens holding frame in the optical axis direction can be finely adjusted by connecting the adjusting member to the main barrel, the resolving power and brightness of the lens can be reduced with a small number of parts and a simple configuration. Nevertheless, the focal position of the lens can be adjusted quickly and with high accuracy.

  Further, the second adjustment mechanism in the focus adjustment mechanism of the present invention is provided at a position opposed to the sub-barrel or the adjustment member in the adjustment member or the sub-barrel, with respect to a plane orthogonal to the optical axis. An inclined surface having an angle smaller than an angle formed by the plane and the groove, and an abutting member that is provided on the sub-barrel or the adjustment member and contacts the inclined surface.

  According to the present invention, the second adjustment mechanism can be realized only by setting the position of the adjustment member or the sub-lens that faces the sub-lens or the adjustment member as an inclined surface. Regardless of resolution or brightness, the focal position of the lens can be adjusted quickly and with high accuracy.

  An imaging apparatus according to the present invention includes a lens holding frame that holds a lens, a photoelectric conversion element for imaging that generates image data according to the intensity of external light incident on the lens, and an optical axis in the axial direction. A main barrel that holds the lens holding frame so as to be movable in the optical axis direction, and a cylindrical shape that has the optical axis as an axial direction. A secondary lens barrel having an adjustment ring rotatably provided around the optical axis, and the lens holding frame is moved in the optical axis direction with respect to the main lens barrel as the adjustment ring rotates relative to the main lens barrel A first adjusting mechanism to be adjusted, an adjusting member that is in contact with the secondary lens barrel in the optical axis direction and is rotatable about the optical axis with respect to the main lens barrel, and the rotation of the adjusting member. The sub-barrel is moved in the optical axis direction with respect to the main barrel A second adjustment mechanism that moves the lens holding frame in accordance with the amount of rotation of the adjustment member relative to the main barrel, the adjustment ring relative to the main barrel. The sub-barrel is moved so as to be smaller than the amount of movement of the lens holding frame according to the amount of rotation.

  According to the present invention, since the focal position of a bright and high-resolution lens can be adjusted with high accuracy, the lens position is not affected by the brightness and resolution of the lens or the number of pixels in the photoelectric conversion element for imaging. Image quality image data can be obtained.

  According to the focus adjustment mechanism and the imaging apparatus according to the present invention, there is an effect that the focus position of a lens having a bright and high resolving power can be adjusted with high accuracy.

  Exemplary embodiments of a focus adjustment mechanism and an imaging apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings. The embodiment is an example in which the focus adjustment mechanism according to the present invention is applied to a varifocal lens. The varifocal lens is used by being connected to an imaging device such as a digital camera, for example.

(Embodiment 1)
FIG. 1 is a perspective view showing the varifocal lens of the first embodiment. As shown in FIG. 1, the varifocal lens 100 according to Embodiment 1 includes a lens 101 that can move in the optical axis direction of the varifocal lens 100. The lens 101 is held by a cylindrical barrel 102 having the optical axis of the varifocal lens 100 as an axis.

  The lens barrel 102 includes a rear lens barrel 103 attached to a mount (not shown) and a front lens barrel 104 attached to the rear lens barrel 103. The front barrel 104 is provided on the opposite side of the mount with the rear barrel 103 in between. The lens 101 described above is held by the front lens barrel 104.

  A focus ring 105 as an adjustment ring and a fine adjustment ring 106 as an adjustment member are provided on the outer peripheral portion of the front side barrel 104. The focus ring 105 has a cylindrical shape with the optical axis of the varifocal lens 100 as an axial center direction, and is provided to be rotatable around the optical axis. The fine adjustment ring 106 is provided so as to be rotatable around the optical axis of the varifocal lens 100. Reference numeral 107 in FIG. 1 is a focus lock screw that restricts the rotation of the focus ring 105.

  FIG. 2 is a longitudinal side view showing the varifocal lens 100. FIG. 2 shows a state in which the front side barrel 104 and each member held by the front side barrel 104 are cut along a plane passing through the optical axis. In the front side barrel 104 shown in FIG. 2, a rear side barrel 103 is attached to the front side barrel 104 on the right side in FIG. FIG. 3 is a cross-sectional front view showing the varifocal lens 100.

  As shown in FIGS. 2 and 3, the front lens barrel 104 is connected to the rear lens barrel 103 described above, and includes a cylindrical main lens barrel 201 having the optical axis of the varifocal lens 100 as an axis. I have. The main barrel 201 is provided with a first rectilinear hole 202 that passes through the main barrel 201 in a direction perpendicular to the optical axis of the varifocal lens 100 and has the optical axis direction of the varifocal lens 100 as a longitudinal direction. .

  A cylindrical first lens barrel 203 having the optical axis of the varifocal lens 100 as an axis is provided on the outer peripheral side of the main lens barrel 201. The first lens barrel 203 is provided with a second rectilinear hole 204 that passes through the first lens barrel 203 in a direction perpendicular to the optical axis of the varifocal lens 100 and whose longitudinal direction is the optical axis direction of the varifocal lens 100. ing. The focus ring 105 described above is provided on the outer peripheral side of the first lens barrel 203 so as to be rotatable with respect to the first lens barrel 203 around the optical axis of the varifocal lens 100.

  On the inner peripheral surface of the focus ring 105, a cam groove 205 is provided as a spiral groove having the optical axis of the varifocal lens 100 as an axis. The cam groove 205 is provided for a plurality of circumferences around the axis, for example, for 3 pitches. The cam groove 205 is engaged with a top member 207 as an engaging member provided on the lens holding frame 206 that holds the lens 101 described above.

  The top member 207 is engaged with the cam groove 205 via the first rectilinear hole 202 and the second rectilinear hole 204 described above. In the first embodiment, a secondary lens barrel is realized by the first lens barrel 203 and the focus ring 105. A space is provided between the outer peripheral surface of the lens holding frame 206 and the inner peripheral surface of the main barrel 201, and the lens holding frame 206 is suspended in the main barrel 201 by the frame member 207. Yes.

  When the focus ring 105 rotates around the optical axis with respect to the first lens barrel 203, the top member 207 tries to rotate around the optical axis as the focus ring 105 rotates. Since the movement in the direction of rotation around the optical axis is restricted by the 202 and the second rectilinear hole 204, the varifocal lens 100 moves in the optical axis direction while changing the engagement position with the cam groove 205.

  As described above, in the varifocal lens 100, the focus ring 105 rotates around the optical axis with respect to the first lens barrel 203 to move the position of the lens 101 in the optical axis direction of the varifocal lens 100. it can. In the first embodiment, the first adjusting mechanism is realized by the main lens barrel 201, the first lens barrel 203, the focus ring 105, the cam groove 205, and the top member 207.

  When the focus ring 105 is fixed to the first lens barrel 203 by the focus lock screw 107 described above, the rotation with respect to the first lens barrel 203 is restricted. The focus lock screw 107 is screwed into a screw hole 208 provided in the focus ring 105 with the direction orthogonal to the optical axis of the varifocal lens 100 as the axial direction. The screw hole 208 passes through the focus ring 105 in the axial direction of the focus lock screw 107. As a result, the tip of the focus lock screw 107 can be brought into contact with the first lens barrel 203.

  Here, the positional relationship between the top member 207 and the focus lock screw 107 will be described with reference to FIG. As shown in FIG. 3, the varifocal lens 100 includes three piece members 207. The top members 207 are arranged at equal intervals on a concentric circle centered on the optical axis. Thereby, the inclination of the optical axis of the lens 101 with respect to the optical axis of the varifocal lens 100 can be prevented, and the load applied to the top member 207 when the top member 207 is moved can be minimized. The focus lock screw 107 described above is provided at an intermediate position between any two of the three top members 207.

  The fine adjustment ring 106 described above is provided at the end of the main barrel 201 opposite to the rear side barrel 103. The fine adjustment ring 106 is provided on the outer peripheral side of the main barrel 201 so as to be rotatable with respect to the main barrel 201 around the optical axis of the varifocal lens 100. The fine adjustment ring 106 rotates with respect to the main lens barrel 201 by screwing a screw 209 provided on the inner peripheral surface of the fine adjustment ring 106 with a screw 210 provided on the outer peripheral surface of the main lens barrel 201. It is connected freely. The pitch of the screw 209 provided on the inner peripheral surface of the fine adjustment ring 106 and the screw 210 provided on the outer peripheral surface of the main barrel 201 is smaller than the pitch of the cam groove 205 described above.

  Flange 211 and 212 are provided at the end of the main barrel 201 on the rear barrel 103 side and the end of the first barrel 203 on the rear barrel side 103. A bias spring 213 as an urging member is provided between the flange 211 and the flange 212. The biasing spring 213 urges the first lens barrel 203 in the direction in which the first lens barrel 203 contacts the fine adjustment ring 106 in the optical axis direction (the direction from the right side to the left side in FIG. 2). For example, a wave washer can be used as the one-sided spring 213. The one-sided spring 213 is not limited to the wave washer, and the shape and the material are not limited as long as the biasing force is applied to the first lens barrel 203 described above.

  When the fine adjustment ring 106 rotates around the optical axis with respect to the main barrel 201, the screwing state of the fine adjustment ring 106 and the main barrel 201 changes with the rotation of the fine adjustment ring 106, and the varifocal lens The position of the fine adjustment ring 106 with respect to the main barrel 201 in the direction of the optical axis 100 changes. As described above, the fine adjustment ring 106 moves in the optical axis direction of the varifocal lens 100 by changing the screwing state with respect to the main barrel 201.

  Since the first lens barrel 203 is urged in the direction in which it abuts on the fine adjustment ring 106 by the bias spring 213, when the fine adjustment ring 106 moves in the optical axis direction of the varifocal lens 100, Along with the movement, the varifocal lens 100 moves in the optical axis direction.

  As described above, the pitch of the screw 209 provided on the inner peripheral surface of the fine adjustment ring 106 and the screw 210 provided on the outer peripheral surface of the main barrel 201 is smaller than the pitch of the cam groove 205. If the amount of rotation of the fine adjustment ring 106 with respect to the main lens barrel 201 is the same, the fine adjustment ring 106 is more than the amount of movement of the first lens barrel 203 by rotating the focus ring 105 in the optical axis direction of the varifocal lens 100. The amount of movement of the first lens barrel 203 by rotating is smaller.

  In the first embodiment, for example, each part constituting the varifocal lens 100 such as the fine adjustment ring 106, the main lens barrel 201, the first lens barrel 203, and the lens holding frame 206 is formed using a plastic material. By using a plastic material, the manufacturing cost of the varifocal lens 100 can be reduced as compared with the case of using a metal material.

  Although illustration is omitted, when the varifocal lens 100 is manufactured, the focal position of the lens 101 is adjusted in a state where the varifocal lens 100 is connected to a main body of a digital camera or an inspection device having an imaging device such as a CCD. . The focal position of the lens 101 is adjusted using image data generated by causing external light that has passed through the varifocal lens 100 to enter the above-described imaging device and photoelectrically converting the imaging device, or an image based on the image data. . Specifically, when adjusting the focal position of the lens 101, the operator first loosens the focus lock screw 107 in a state where the fine adjustment ring 106 is fastened to the main barrel 201 by a certain amount. Here, the fixed amount is, for example, an amount in which both screws 209 and 210 are screwed about half way.

  The operator loosens the focus lock screw 107 and then rotates the focus ring 105 with respect to the first lens barrel 203. As a result, the lens holding frame 206 moves in the optical axis direction of the varifocal lens 100, and the lens 101 moves in the optical axis direction of the varifocal lens 100 as the lens holding frame 206 moves. The operator tightens the focus lock screw 107 in a state where the focal position of the lens 101 is approximately matched. By tightening the focus lock screw 107, the engagement position of the top member 207 with respect to the cam groove 205 is fixed.

  Subsequently, the operator rotates the fine adjustment ring 106 with respect to the main barrel 201. As a result, the first lens barrel 203 moves relative to the main lens barrel 201 in the optical axis direction of the varifocal lens 100. When the first lens barrel 203 moves with respect to the main lens barrel 201, the lens holding frame 206 moves with respect to the main lens barrel 201 in the optical axis direction of the varifocal lens 100, and the lens holding frame 206 moves. Thus, the lens 101 moves in the optical axis direction of the varifocal lens 100. The operator stops the rotation of the fine adjustment ring 106 in a state where the focus position of the lens 101 is in alignment, and ends the adjustment of the focus position of the lens 101.

  As described above, when the rotation amounts of the focus ring 105 and the fine adjustment ring 106 with respect to the main barrel 201 are the same, the fine adjustment is made more than the movement amount of the lens holding frame 206 in the optical axis direction accompanying the rotation of the focus ring 105. The amount of movement of the lens holding frame 206 in the optical axis direction due to the movement of the first lens barrel 203 in the optical axis direction with the rotation of the ring 106 is smaller. As a result, the operator roughly adjusts the focal position of the lens 101 in the optical axis direction by rotating the focus ring 105 with respect to the main barrel 201, and rotates the fine adjustment ring 106 with respect to the main barrel 201. By doing so, the focal position of the lens 101 in the optical axis direction can be finely adjusted.

  As described above, according to the varifocal lens 100 of the first embodiment, the focal position of the lens 101 can be quickly and accurately adjusted regardless of the resolution and brightness of the lens 101 mounted on the varifocal lens 100. it can.

  Further, according to the varifocal lens 100 of the first embodiment, when the focal position of the lens 101 is started, the screws 209 and 210 are screwed about half and then the fine adjustment ring 106 and the main barrel 201 are screwed. In the combined state, when finely adjusting the focal position of the lens 101, the lens 101 can be moved to both the fine adjustment ring 106 side and the biasing spring 213 side. Thereby, it is possible to further speed up the adjustment operation of the focal position of the lens 101.

  A general surveillance camera is installed in a place where it is difficult to reach, such as a ceiling or a recessed part in a room. For this reason, the operator may have to adjust the lens of the surveillance camera in an environment where it is difficult to work, and it is assumed that it is difficult to rotate the focus ring minutely to ensure adjustment accuracy. The

  On the other hand, according to the surveillance camera equipped with the varifocal lens 100 according to the embodiment, after the focus position of the lens 101 is roughly adjusted, the fine adjustment ring 106 is rotated to thereby rotate the lens 101 in the optical axis direction. Since the focal position can be finely adjusted, the focal position of the lens 101 can be adjusted quickly and with high accuracy even in a situation where the working environment is not prepared.

  Further, according to the varifocal lens 100 of the first embodiment, when adjusting the focal position of the lens 101, the focal position of the lens 101 is finely adjusted by rotating the fine adjustment ring 106 in the same manner as the focus ring 105. Therefore, the focus position of the lens 101 can be quickly and accurately determined regardless of the resolving power and brightness of the lens 101 mounted on the varifocal lens 100 without depending on the proficiency level or intuition of the operator who performs the adjustment work. Can be adjusted.

  Further, according to the varifocal lens 100 of the first embodiment, instead of adjusting the focal position of the lens 101, the image data is corrected, or the lens holding frame 206 is moved using a motor to adjust the focal position of the lens 101. Since the focal position of the lens 101 can be finely adjusted without adjustment, the increase in the manufacturing cost of the varifocal lens 100 can be suppressed, and the focal position of the lens 101 can be controlled regardless of the resolution and brightness of the lens 101. Can be adjusted quickly and with high accuracy.

  Further, according to the varifocal lens 100 of the first embodiment, even when each part constituting the varifocal lens 100 is formed using a plastic material, the resolving power and brightness of the lens 101 mounted on the varifocal lens 100 are improved. Regardless, since the focal position of the lens 101 can be adjusted quickly and with high accuracy, for example, the varifocal lens 100, which is positioned in the low-priced market compared to the FA lens market, has a high manufacturing cost. Adjustment accuracy can be maintained.

  In the first embodiment, each part constituting the varifocal lens 100 is formed using a plastic material. However, the material forming each part constituting the varifocal lens 100 is not limited to a plastic material, and may be a metal material. It may be. Since each part constituting the varifocal lens 100 is formed of a metal material, the manufacturing accuracy of each component can be improved. Therefore, regardless of the resolution and brightness of the lens 101 mounted on the varifocal lens 100, the lens 101 Can be adjusted quickly and with higher accuracy.

  Further, according to the varifocal lens 100 of the first embodiment, the first barrel 203 is stably abutted against the fine adjustment ring 106 by the biasing spring 213 provided between the flange 211 and the flange 212. By making contact, it is possible to suppress the shakiness of the first lens barrel 203 in the optical axis direction, so that the focal position of the lens 101 due to the shakiness of the lens 101 coming from the shakiness of the first lens barrel 203 It is possible to prevent the deviation.

  Further, according to the varifocal lens 100 of the first embodiment, the engaging position of the top member 207 with respect to the cam groove 205 provided in the first lens barrel is changed, so that the main lens barrel 201 can be configured with a simple configuration. Since the lens holding frame 206 can be moved in the optical axis direction, the structure of the varifocal lens 100 can be simplified and an increase in manufacturing cost can be suppressed.

  In the first embodiment, the lens holding frame 206 is moved in the optical axis direction by changing the engagement position of the top member 207 with respect to the cam groove 205. However, the present invention is not limited to this. For example, the first lens barrel 203 and the lens holding frame 206 are connected by a helicoid screw mechanism having a spiral screw having the optical axis as an axis, and the lens holding frame 206 is moved around the optical axis with respect to the first lens barrel 203. The lens holding frame 206 may be moved in the optical axis direction.

  Further, according to the varifocal lens 100 of the first embodiment, the main lens barrel 201 and the fine adjustment ring 106 are connected by the screw mechanism having the screws 209 and 210 having a pitch smaller than the pitch of the cam groove 205, Since the position of the fine adjustment ring 106 with respect to the lens barrel 201 can be finely adjusted, the focal position of the lens 101 can be quickly and easily increased with a small number of parts and a simple configuration regardless of the resolution and brightness of the lens 101. The accuracy can be adjusted.

  Further, according to the varifocal lens 100 of the first embodiment, since the top member 207 is engaged with the cam groove 205 via the first and second straight advance holes 202 and 204, the movement range of the top member 207 is increased. The lens holding frame 206 is moved only in the optical axis direction by being restricted by the first and second rectilinear holes 202 and 204, so that the optical axis of the lens 101 deviates from the normal optical axis as the lens holding frame 206 moves. Therefore, the optical axis shift of the lens 101 accompanying the movement of the lens 101 can be prevented with a simple configuration.

  Further, according to the varifocal lens 100 of the first embodiment, since the main lens barrel 201 and the fine adjustment ring 106 are connected via the screw mechanism, the lens 101 is used for fine adjustment of the focal position of the lens 101. It can be moved smoothly in the direction of the optical axis.

  Although not shown, according to an imaging apparatus such as a digital camera equipped with the varifocal lens 100 according to the first embodiment, the focal position of the lens can be adjusted with high accuracy to an imaging element such as a CCD provided in the imaging apparatus. Therefore, high-quality image data can be generated using the lens 101 with improved resolution and brightness.

(Embodiment 2)
FIG. 4 is a longitudinal sectional side view showing the varifocal lens of the second embodiment. Next, the varifocal lens of Embodiment 2 will be described with reference to FIG. In the second embodiment, a front lens barrel 400 is provided instead of the front lens barrel 104 in the first embodiment. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 4 shows a state in which the front lens barrel 400 and each member held by the front lens barrel 400 in the varifocal lens of the second embodiment are cut along a plane passing through the optical axis. As shown in FIG. 4, on the outer peripheral side of the main barrel 201, instead of the first barrel 203 in the first embodiment described above, a cylindrical cam barrel having the optical axis of the varifocal lens as an axis. 401 is provided. The cam barrel 401 is provided so as to be rotatable around the optical axis of the varifocal lens with respect to the main barrel 201.

  The cam barrel 401 is provided with a cam groove 402 as a spiral groove having the optical axis of the varifocal lens as an axis. The pitch of the cam grooves 402 is larger than the pitch of the screws 209 provided on the inner peripheral surface of the fine adjustment ring 106 and the screws 210 provided on the outer peripheral surface of the main barrel 201. The cam groove 402 passes through the cam cylinder 401 in a direction perpendicular to the optical axis of the varifocal lens, and has a tapered shape that expands greatly as it is separated from the optical axis.

  A frame member 404 provided on the lens holding frame 403 is engaged with the cam groove 402. The frame member 404 is slidable with respect to the cam groove 402, and is fixed to the lens holding frame 403 by a fixing screw 405 that is screwed into the lens holding frame 403. The frame member 404 is fixed in a state of being inserted into the lens holding frame 403 from the outer peripheral side of the cam cylinder 401 through the first rectilinear hole 202. A cover ring 406 that covers the outer peripheral side of the cam cylinder 401 is provided on the outer peripheral side of the cam cylinder 401.

  Reference numeral 407 in FIG. 4 is a focus lock screw screwed into a screw hole (not shown) provided in the cam cylinder 401 and the cover ring 406. When adjusting the focal position of the lens 101, when the operator rotates the focus lock screw 407 around the optical axis, the cam barrel 401 and the cover ring 406 rotate around the optical axis along with the focus lock screw 407. The focus lock screw 407 is provided such that the tip thereof is detachable from the main barrel 201 according to the screwed state with respect to the cam barrel 401 and the cover ring 406, and the main barrel is in contact with the main barrel 201. The rotation of the cam cylinder 401 and the cover ring 406 with respect to 201 is restricted.

  In the varifocal lens, when the cover ring 406 rotates around the optical axis with respect to the main lens tube 201, the top member 404 tries to rotate with the rotation of the cover ring 406. However, the top member 404 has the first straight advance hole. The movement in the direction of rotation around the optical axis is restricted by 202. Therefore, the top member 404 moves in the optical axis direction of the varifocal lens while changing the position of engagement with the cam groove 402.

  As described above, in the varifocal lens, the cover ring 406 rotates around the optical axis with respect to the cam barrel 401, whereby the position of the lens 101 can be moved in the optical axis direction of the varifocal lens. In the second embodiment, the first adjustment mechanism is realized by the main barrel 201, the cam barrel 401, the cam groove 402, and the top member 404.

  As described above, since the pitch of the cam groove 402 is larger than the pitch of the screw 209 provided on the inner peripheral surface of the fine adjustment ring 106 and the screw 210 provided on the outer peripheral surface of the main barrel 201, the cover ring When the amount of rotation of 406 and fine adjustment ring 106 with respect to main barrel 201 is equal, the amount of movement of lens holding frame 206 in the optical axis direction accompanying the rotation of cover ring 406 is accompanied by the rotation of fine adjustment ring 106. The amount of movement of the lens holding frame 206 in the optical axis direction due to the movement of the cam cylinder 401 in the optical axis direction becomes smaller.

  As described above, in the second embodiment, the operator roughly adjusts the focal position of the lens 101 in the optical axis direction by rotating the cover ring 406 with respect to the main lens barrel 201. By rotating the fine adjustment ring 106, the focal position of the lens 101 in the optical axis direction can be finely adjusted. As a result, according to the varifocal lens of the second embodiment, the focal position of the lens 101 can be quickly and accurately adjusted regardless of the resolution and brightness of the lens 101 mounted on the varifocal lens.

  Although not shown, according to the imaging device such as a digital camera equipped with the varifocal lens according to the second embodiment, as in the varifocal lens 100 according to the first embodiment, the imaging device such as a CCD included in the imaging device is used. Since the focal position of the lens can be adjusted with high accuracy, high-quality image data can be generated using a lens with improved resolution and brightness.

(Embodiment 3)
FIG. 5 is a perspective view showing the varifocal lens of the third embodiment. Next, the varifocal lens of Embodiment 3 will be described with reference to FIG. In the third embodiment, the same parts as those in the first or second embodiment described above are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 5, the varifocal lens 500 according to the third embodiment includes a rear lens barrel 501 and a front lens barrel 502 attached to the rear lens barrel 501.

  The front-side lens barrel 502 includes a focus ring 503 and a fine adjustment ring 504 that are rotatably provided around the optical axis of the varifocal lens 500. The focus ring 503 is rotatable around the optical axis of the varifocal lens 500 in accordance with the screwed state of the focus lock screw 107 with respect to the focus ring 503.

  Reference numeral 505 in FIG. 5 is a focus cover index mark (hereinafter referred to as “F cover index mark”) that serves as an index for guiding the rotation amount of the focus ring 503. The F cover index mark 505 is displaced around the optical axis as the focus ring 503 rotates. Although not shown, a recess that engages when the focus ring 503 rotating around the optical axis is positioned at the reference position between the focus ring 503 and the cam barrel (see reference numeral 401 in FIG. 6) and Protrusions are provided.

  The operator can determine whether or not the focus ring 503 is positioned at the reference position based on whether or not the concave portion and the convex portion are engaged. The engaging force between the concave portion and the convex portion is set so as not to hinder the rotating operation of the focus ring 503 by the operator.

  Further, reference numeral 506 in FIG. 5 is an index position guide mark serving as an index for guiding the rotation amount of the fine adjustment ring 504. The index position guide mark 506 is displaced around the optical axis as the fine adjustment ring 504 rotates. The rotation amount of the fine adjustment ring 504 relative to the focus ring 503 can be guided by the positional relationship between the F cover index mark 505 and the index position guide mark 506.

  Reference numeral 507 in FIG. 5 is a fine adjustment ring lock screw for fixing the fine adjustment ring 504 to the focus ring 503. The tip of the fine adjustment ring lock screw 507 is provided so as to come into contact with and separate from the focus ring 503 in accordance with the screwed state with respect to the fine adjustment ring 504. The rotation of the fine adjustment ring 504 with respect to 503 is restricted. Although not shown, the varifocal lens 500 is connected to an image pickup apparatus including an image pickup device such as a CCD that generates an electric signal according to the intensity of incident external light.

  Reference numeral 508 in FIG. 5 is a second lock screw that moves a lens (see reference numeral 605 in FIG. 6) different from the lens 101 in the optical axis direction. By moving the second lock screw 508 around the optical axis of the varifocal lens 500 while the second lock screw 508 is loosened, the lens can be moved.

  FIG. 6 is a longitudinal side view showing the varifocal lens 500. FIG. 6 shows a state in which the varifocal lens 500 is sectioned along a plane passing through the optical axis of the varifocal lens 500. As shown in FIG. 6, the fine adjustment ring 504 is fitted to one end side of the main barrel 201 and is rotatable about the optical axis of the varifocal lens 500 with respect to the main barrel 201. .

  The fine adjustment ring 504 is provided with an inclined surface 601 that is inclined with respect to a plane perpendicular to the optical axis of the varifocal lens 500 at a position facing the cam cylinder (see reference numeral 401 in FIG. 6) in the optical axis direction. Yes. The inclined surface 601 is provided such that an angle with respect to a plane orthogonal to the optical axis of the varifocal lens 500 is smaller than an angle formed by the plane and the cam groove 402 described above.

  The inclined surface 601 is provided at a plurality of locations on a concentric circumference centering on the optical axis of the varifocal lens 500. The shape of the end surface on the cam tube 401 side of the fine adjustment ring 504 by the inclined surface 601 is such that the cam tube 401 gradually moves in the optical axis direction when the end surface is traced around the optical axis from an arbitrary position on the end surface. It has a sawtooth shape in which it is inclined in a direction away from (or approached from) and approaches (or separated from) the cam cylinder at a stroke when it reaches another inclined surface 601. The inclination angles of the inclined surfaces 601 with respect to the plane orthogonal to the optical axis of the varifocal lens 500 are the same.

  In the cam barrel 401, a protrusion 602 that contacts the inclined surface 601 of the fine adjustment ring 504 is provided on the surface of the varifocal lens 500 that faces the fine adjustment ring 504 in the optical axis direction. In the third embodiment, the second adjustment mechanism is realized by the inclined surface 601 and the protrusion 602. Reference numeral 603 in FIG. 6 denotes a drop-off prevention screw that prevents the fine adjustment ring 504 from dropping from the main barrel 201. The drop-off prevention screw 603 is engaged with a groove 604 provided on the outer peripheral surface of the main barrel 201 via a fine adjustment ring 504.

  The drop-off prevention screw 603 is slidably engaged with the groove 604 and is engaged with the groove 604 at an arbitrary position in the groove 604 according to the rotation amount of the fine adjustment ring 504 with respect to the main barrel 201. The fine adjustment ring 504 can be connected to the main barrel 201 by the groove 604 and the drop-off prevention screw 603 regardless of the amount of rotation of the fine adjustment ring 504 with respect to the main barrel 201.

  Reference numeral 605 in FIG. 6 is a lens that transmits external light incident on the lens 101 to the side of an image sensor (not shown) such as a CCD. Similarly to the lens 101 described above, the lens 605 is a varifocal lens by engaging a frame member 607 provided on the lens holding frame 606 that supports the lens 605 with a cam groove 609 provided on the cam barrel 608. 500 is provided to be movable in the direction of the optical axis. On the outer peripheral side of the cam barrel 608, a cylindrical zoom ring 610 that is rotatable around the optical axis of the varifocal lens 500 is provided with respect to the cam barrel 608. The zoom ring 610 rotates around the optical axis in accordance with the operation of the second lock screw 508 described above.

  7 to 9 are explanatory views (No. 1) to (No. 3) for explaining the adjustment procedure of the focal position of the lens 101. FIG. 7 to 9 show the procedure for adjusting the focal position of the lens 101 step by step. When adjusting the focal position of the lens 101, the operator first rotates the focus ring 503 and the fine adjustment ring 504 around the optical axis to position the focus ring 503 at the reference position as shown in FIG. The fine adjustment ring 504 is positioned at a position where the index position guide mark 506 is aligned with the F cover index mark 505 in the state (see reference numeral 701 in FIG. 7).

  Subsequently, the operator tightens the fine adjustment ring lock screw 507, rotates the focus ring 503 around the optical axis with the focus lock screw 107 loosened, and moves the lens holding frame 403 in the optical axis direction. At this time, since the fine adjustment ring lock screw 507 is tightened, the fine adjustment ring 504 rotates as the focus ring 503 rotates, as shown in FIG. The operator tightens the focus lock screw 107 with the lens holding frame 403 moved to a position where the focal position of the lens 101 is approximately matched.

  Subsequently, the operator loosens the fine adjustment ring lock screw 507 and rotates the fine adjustment ring 504 with respect to the cam barrel 401 to finely adjust the focal position of the lens 101. At this time, since the focus lock screw 107 is in a tightened state, the fine adjustment ring 504 rotates relative to the focus ring 503 and the cam barrel 401 as shown in FIG. When the fine adjustment ring 504 rotates around the optical axis with respect to the cam cylinder 401, the contact position of the protrusion 602 on the inclined surface 601 changes as the fine adjustment ring 504 rotates.

  When the contact position of the protrusion 602 on the inclined surface 601 changes, the cam barrel 401 moves in the optical axis direction of the varifocal lens 500 with respect to the main barrel 201. At this time, the position of the fine adjustment ring 504 with respect to the main barrel 201 in the optical axis direction is constant. When the cam cylinder 401 moves, the lens holding frame 403 moves in the optical axis direction along with the movement.

  As described above, the inclined surface 601 is provided such that the angle with respect to the plane orthogonal to the optical axis of the varifocal lens 500 is smaller than the angle formed by the plane and the cam groove 402 described above. When the rotation amount of the tube 401 and the fine adjustment ring 504 with respect to the main barrel 201 is equal, the fine adjustment ring 504 is rotated more than the amount of movement of the lens holding frame 403 in the optical axis direction due to the rotation of the cam tube 401. Thus, the amount of movement of the lens holding frame 403 in the optical axis direction due to the movement of the cam cylinder 401 in the optical axis direction is smaller. The operator tightens the fine adjustment ring lock screw 507 when the fine adjustment of the focal position of the lens 101 is completed. By such a work procedure, the focal position of the lens 101 in the varifocal lens 500 can be adjusted.

  As described above, in the varifocal lens 500, the fine adjustment ring 504 rotates around the optical axis with respect to the main barrel 201, thereby finely adjusting the focal position of the lens 101 in the optical axis direction of the varifocal lens 500. can do. In the third embodiment, the second adjustment mechanism is realized by the fine adjustment ring 504, the inclined surface 601, the cam cylinder 401, and the protrusion 602. Thus, the operator roughly adjusts the focal position of the lens 101 in the optical axis direction by rotating the cam barrel 401 with respect to the main barrel 201, and rotates the fine adjustment ring 504 with respect to the main barrel 201. By doing so, the focal position of the lens 101 in the optical axis direction can be finely adjusted.

  Similar to the first or second embodiment described above, according to the varifocal lens 500 of the third embodiment, during fine adjustment, the fine adjustment ring 504 is rotated from a state in which the protrusion 602 is in contact with a certain inclined surface 601. Since the projection 602 moves along the inclined surface 601, the lens 101 can be moved smoothly in the optical axis direction. In addition, the varifocal lens 500 of Embodiment 3 can keep the distance between the cam barrel 401 and the fine adjustment ring 504 within a certain range even when the fine adjustment ring 504 continues to rotate in the same direction. Therefore, it is possible to prevent the focal position of the lens 101 from being far from the normal focal position in the optical axis direction.

  In the varifocal lens 500 according to the third embodiment, when the fine adjustment ring 504 is continuously rotated, the position of the lens 101 in the optical axis direction when the inclined surface 601 with which the protrusion 602 abuts is switched to another inclined surface 601. However, when the operator rotates the fine adjustment ring 504 while visually confirming the position of the index position guide mark 506 with respect to the F cover index mark 505, the position of the lens in the optical axis direction is rapidly increased. Changes can be prevented.

  Although not shown, the protrusion 602 is formed at the boundary portion of each inclined surface 601 so that the protrusion 602 does not move from one inclined surface 601 to another inclined surface 601 as the fine adjustment ring 504 rotates. You may provide the rib etc. which control movement of this. In this case, if the adjustment of the focal position of the lens 101 is not completed before it hits the rib, the procedure shown in FIGS. 7 to 9 is performed again to finely adjust the focal position of the lens 101.

  As described above, according to the varifocal lens 500 of the third embodiment, the focal position of the lens 101 can be finely adjusted by changing the contact position of the protrusion 602 with respect to the inclined surface 601, and thus a simple configuration. Thus, the focal position of the lens 101 can be adjusted quickly and with high accuracy regardless of the resolution and brightness of the lens 101.

  Although illustration is omitted, according to the imaging apparatus equipped with the varifocal lens 500 of the third embodiment, the focal position of the lens 101 can be adjusted with high accuracy to an imaging element such as a CCD provided in the imaging apparatus, so that the resolving power High-quality image data can be generated using the lens 101 with increased brightness.

  As described above, the focus adjustment mechanism and the imaging apparatus according to the present invention are useful for adjusting the focal position of the lens included in the optical device, and are particularly suitable for adjusting the focal position of the lens included in the varifocal lens.

1 is a perspective view showing a varifocal lens according to Embodiment 1. FIG. It is a vertical side view which shows a varifocal lens. It is a cross-sectional front view which shows a varifocal lens. FIG. 6 is a longitudinal sectional side view showing a varifocal lens of a second embodiment. FIG. 6 is a perspective view showing a varifocal lens according to a third embodiment. It is a vertical side view which shows a varifocal lens. It is explanatory drawing (the 1) explaining the adjustment procedure of the focus position of a lens. It is explanatory drawing (the 2) explaining the adjustment procedure of the focus position of a lens. It is explanatory drawing (the 3) explaining the adjustment procedure of the focus position of a lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Lens 105 Focus ring 106 Fine adjustment ring 201 Main barrel 205 Cam groove 206 Lens holding frame 207 Frame member 213 One-way spring

Claims (6)

A main barrel that has a cylindrical shape with the optical axis as the axial direction and holds a lens holding frame that holds the lens movably in the optical axis direction;
A secondary lens barrel having an adjustment ring that has a cylindrical shape with the optical axis as an axial direction and is provided to be rotatable around the optical axis with respect to the main lens barrel;
A first adjustment mechanism for moving the lens holding frame in the optical axis direction with respect to the main barrel in accordance with the rotation of the adjustment ring with respect to the main barrel;
An adjusting member that is in contact with the sub-barrel in the optical axis direction and is rotatable about the optical axis with respect to the main barrel;
A second adjustment mechanism that moves the sub-barrel in the optical axis direction with respect to the main barrel in accordance with the rotation of the adjustment member;
With
The second adjustment mechanism is configured such that a movement amount of the lens holding frame according to a rotation amount of the adjustment member with respect to the main lens barrel corresponds to a rotation amount of the lens holding frame according to a rotation amount of the adjustment ring with respect to the main lens barrel. A focus adjustment mechanism, wherein the sub-barrel is moved so as to be smaller than a moving amount.   The focus adjustment mechanism according to claim 1, further comprising an urging member that urges the sub-barrel in a direction in contact with the adjustment member.   The first adjustment mechanism includes an engagement member that engages at an arbitrary position in a spiral groove provided in the sub-lens barrel with the optical axis as an axis, and the position of the engagement member with respect to the groove 3. The focus adjustment mechanism according to claim 1, wherein the lens holding frame is moved in the optical axis direction with respect to the main lens barrel by changing the angle.   The second adjusting mechanism is a screw mechanism that connects the main barrel and the adjusting member via a screw, and the lead angle of the screw or the lead angle with respect to the optical axis direction is the pitch of the groove. 4. The focus adjustment mechanism according to claim 3, wherein the focus adjustment mechanism is adjusted according to a lead angle of the groove with respect to the optical axis direction.   The second adjustment mechanism is provided at a position of the adjustment member or the secondary lens barrel facing the secondary lens barrel or the adjustment member, and an angle with respect to a plane perpendicular to the optical axis is such that the plane and the groove are The focus adjustment mechanism according to claim 3, further comprising an inclined surface that is smaller than an angle formed, and an abutting member that is provided on the auxiliary lens barrel or the adjusting member and abuts on the inclined surface. A lens holding frame for holding the lens;
A photoelectric conversion element for imaging that generates image data according to the intensity of external light incident on the lens;
A main barrel having a cylindrical shape with the optical axis as the axial direction, and holding the lens holding frame movably in the optical axis direction;
A secondary lens barrel having an adjustment ring that has a cylindrical shape with the optical axis as an axial direction and is provided to be rotatable around the optical axis with respect to the main lens barrel;
A first adjustment mechanism for moving the lens holding frame in the optical axis direction with respect to the main barrel in accordance with the rotation of the adjustment ring with respect to the main barrel;
An adjusting member that is in contact with the sub-barrel in the optical axis direction and is rotatable about the optical axis with respect to the main barrel;
A second adjustment mechanism for moving the sub-barrel in the optical axis direction with respect to the main barrel in accordance with the rotation of the adjustment member;
With
The second adjustment mechanism is configured such that a movement amount of the lens holding frame according to a rotation amount of the adjustment member with respect to the main lens barrel corresponds to a rotation amount of the lens holding frame according to a rotation amount of the adjustment ring with respect to the main lens barrel. An imaging apparatus, wherein the sub-barrel is moved so as to be smaller than a moving amount.

Images