JP2009145516A - Simplified zoom lens mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the simplification of a photographic lens barrel and a zoom lens mechanism, the miniaturization of equipment, the increase of assembling efficiency and the reduction of cost, in response to the requirement of demand for maintaining performance and moreover making the equipment smaller in size and easier to use than an advanced specification, depending on use conditions in optical equipment on which a zoom lens is mounted. <P>SOLUTION: The simplified zoom lens mechanism adopts such a method that a main driving shaft 5 and a receiving shaft 6 are disposed in parallel to an optical axis L, respectively, a main driving body 8 integrated to the lens frame 4 of a moving lens group for focusing is slidably inserted into the main driving shaft 5, a receiving body 9 integrated to the lens frame of a moving lens group for zooming 3 is slidably inserted into the receiving shaft 6, and in two moving lens groups, the main driving body 8 holding the moving lens group for focusing has a main driving function and the receiving body 9 holding the moving lens group for zooming 3 is driven by the main driving body 8 by receiving the moving force of the moving lens group for focusing. A driving source for the moving lens group for zooming 3 is eliminated and a piezoelectric linear actuator is adapted to the driving source of the main driving body 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a zoom mechanism in a zoom lens barrel mounted on a small optical device, and more particularly to a simple zoom lens mechanism made possible by a simple mechanism.

  When general optical equipment that mounts a zoom lens barrel and targets a subject image requires portability, not only miniaturization of the equipment housing but also compactness and simplification of the mounted zoom lens are required.

  The zoom lens is composed of a plurality of lens groups on the optical axis, and each lens group for zooming and focusing is moved along the optical axis between fixed lens groups on the objective and focus sides. An in-focus zoom lens that can be arranged in a possible manner is common. Among the moving lens groups, the zoom lens group can be moved along the optical axis to continuously change the magnification of the subject image, and the other focusing lens group can focus the subject distance at the desired image magnification position. The best image point is obtained by adjustment and is obtained by moving along the optical axis.

  In such a zoom lens configuration, it is common to use two power sources to move the two moving lens groups respectively, and to use separate moving means. However, further downsizing and simplicity are possible. There was a limit when asked.

  As a solution to this problem, Patent Document 1 proposes a method that can perform zooming and focusing with a single drive source. However, a rotary motor is used as the drive source, and a cam ring arrangement or a clutch mechanism in series with the speed reduction mechanism is large. Therefore, it was not necessarily the best for compactness and cost reduction.

  On the other hand, when a rotary motor is used as a power source and used in a lens zoom mechanism or the like, conversion means for making the rotation go straight has been required. It is common to use a cam or screw mechanism as the means, but there have been practical problems of conversion efficiency and occupied space. In recent years, piezoelectric linear actuators have attracted attention as a method for solving this power source problem, and one of the operating principles is disclosed in Patent Document 2. That is, a piezoelectric element 10 is formed by laminating and integrating a polarized piezoelectric substrate 10b and a disk-shaped metal elastic plate 10a shown in FIG. 7, and the piezoelectric element 10 expands due to the polarity of a signal applied to the electrodes A and B of the piezoelectric substrate 10b. The phenomenon of contraction occurs, and distortion occurs between the metal elastic plate 10a and the piezoelectric substrate 10b. For this reason, if an alternating signal is applied between the electrodes A and B of the piezoelectric substrate 10b, the distortion operation in which the center of the disk-like piezoelectric element 10 is deformed into a concavo-convex shape is repeated. That is, if a voltage of + is applied to the A electrode and a voltage of-is applied to the B electrode, the piezoelectric substrate 10b contracts and the metal elastic plate 10a warps in a convex shape as Z1, and if a voltage of-is applied to the A electrode and a voltage of + is applied to the B electrode. Since the piezoelectric substrate 10b expands and the metal elastic plate 10a changes into a concave shape like Z2, if the vibration shaft 11 is fixed upright at the center of the disk, the vibration shaft 11 is vertically displaced by a small amount Δx1 according to the applied alternating signal. And a vibration accompanied by Δx2.

  As shown in FIG. 8, a movable body 12 that is slidable with respect to the vibration shaft 11 and has sufficient friction in the press-contact state is fitted, and the relationship between the inertia of the movable body 12 and the friction between the vibration shaft 11 and the like. If a sawtooth wave pulse signal is applied to the electrodes A and B of the piezoelectric element 10 in a state in which is appropriately set, the vibration shaft 11 is swung up and down with a slow acceleration and a steep acceleration. In response to this, the moving body 12 inserted is also shaken, but when the acceleration is slow, it is moved by the displacement Δx1 or Δx2 along with the shaft by the frictional force, and when the acceleration is steep, the inertial force of the moving body 12 is used. Since it slides without responding to the movement of the vibration shaft 11 and keeps the current position, if the vibration cycle is repeated n times, the moving body moves in one direction along the vibration shaft 11 by a distance of nΔx1 or nΔx2. The principle of operation of the piezoelectric linear actuator is that it can be moved.

In the signal applied to the piezoelectric element 10, if the acceleration at which the vibration shaft 11 moves upward is slowed and the downward movement is steep, the moving body 12 moves upward, and if the opposite signal is applied, the moving body Since 12 can be moved downward, a simple zoom lens mechanism that moves the zooming moving lens and the focusing moving lens using one piezoelectric linear actuator that can be driven by this principle. Is to provide.
JP-A-4-317015 Special table 2007-516688 gazette

  Among optical equipment equipped with a zoom lens, there is a demand for equipment that requires miniaturization and simplicity of equipment while maintaining performance rather than advanced specifications depending on usage conditions. It simplifies the cylinder and zoom lens mechanism, and solves the problems of downsizing the equipment, improving assembly efficiency, and reducing costs.

  A lens barrel of an internal focus type zoom lens in which two moving lens groups, a zooming moving lens group and a focusing moving lens group, are arranged between fixed lens groups installed at both ends, around the optical axis, A main axis and a passive axis parallel to the optical axis are arranged, and a main body integrated with a lens frame of a focusing moving lens group is slidably fitted on the main axis, and a zooming moving lens is provided on the passive axis. A passive body integral with the lens frame of the group is slidably inserted, and the main moving body and the passive body are movable along the optical axis, and the focusing moving lens group is selected from the two moving lens groups. The main moving body to be held has a main dynamic function, and the passive body holding the moving lens group for zooming is driven by the main moving body in response to the moving force of the moving lens group for focusing. Lens group movement The source was omitted.

  For this reason, the lens operation mode is divided into the operation sequence of starting the zooming operation after moving to the infinite position or the closest position, which is the focusing adjustment limit point, and the subject is located between the closest and infinite positions. When the main moving body moves with the passive body united after moving and reaches the desired magnification, the moving zoom lens group of the passive body remains stationary at the arrival position, and the focusing moving lens group A method in which the main moving body is separated from the passive body by reversing and performing a focusing operation is adopted.

  As a driving means for the main moving body, the main driving shaft is used as the vibration axis of the piezoelectric linear actuator with one end fixed to the piezoelectric element, and the piezoelectric linear actuator that can move the main moving body by the vibration of the vibration shaft is applied to solve the problem. planned.

  With a structure that enables a single drive source, the drive source is also a simple piezoelectric linear actuator, so the mechanism is extremely simple, reducing the number of parts, reducing space and reducing the cost, and reducing costs. large.

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of the zoom lens mechanism of the present invention, FIG. 2 is a perspective view of the mechanism as viewed from the main driving shaft and the passive shaft side, FIG. 3 is an operation explanatory diagram of the main driving body and the passive body, and FIG. FIG. 5 is a schematic diagram of an electronic circuit for operating the mechanism, FIG. 6 is a flowchart for explaining the operation, and FIG. 7 is an explanation of the principle of vibration by the piezoelectric element of the piezoelectric linear actuator. FIG. 8 and FIG. 8 are diagrams of the piezoelectric linear actuator main body.

  As shown in FIG. 4, the zoom lens according to the present invention has a zooming moving lens group 3 and a focusing moving lens between the first fixed lens group 1 on the objective side and the second fixed lens 2 on the focal side with the optical axis L as the center. With the configuration in which the groups 4 are arranged in series, the photographing magnification can be continuously changed by moving the moving lens group 3 along the optical axis L, and the subject can be moved by moving the moving lens group 4 along the optical axis L. The focus can be adjusted at a distance. The present invention provides a simple method for the moving mechanism of the zooming moving lens group 3 and the focusing moving lens group 4.

  FIG. 1 shows the zoom mechanism, in which three axes are erected around the optical axis L in parallel with the optical axis L, one of which is a main driving shaft 5 on the side for actively supplying power. One is a passive shaft 6 on the power receiving side, and these two are a shared shaft 7 for preventing rotation and guiding. A piezoelectric element 10 is fixed to the lower end of the main driving shaft 5 so that the main driving shaft 5 vibrates up and down in accordance with the vibration of the piezoelectric element. That is, the vibration shaft 11 of the piezoelectric linear actuator constituted by the piezoelectric element 10, the vibration shaft 11 and the moving body 12 shown in FIG. 8 is the main driving shaft 5, and the moving body 12 is equivalent to the main moving body 8.

  A main moving body 8 is inserted into the main driving shaft 5. The main moving body 8 has a lens barrel 8 a that holds the focusing moving lens group 4 at the center and a slidable gripping portion 8 b that holds the main driving shaft 5. The guide shaft 7 is sandwiched between the U-shaped portions, and a slidable sandwiching portion 8c is integrated. The main shaft 5 is pressed against the main shaft 5 by a leaf spring 8d installed in a missing portion of the through hole 8e to generate a frictional force. Therefore, it has a holding force at a stationary position. In addition, a magnet scaler 20 is fixed to the main moving body 8, and there is a magnet sensor 21 (not shown) installed close to the fixed side, and the position and amount of movement of the main moving body 8 can be detected by this sensor 21. It is like that.

  A passive body 9 is inserted into one of the passive shafts 6. The passive body 9 has a slidable gripper that grips the passive shaft 6 and a lens frame 9 a that holds the moving lens group 3 for zooming at the center. The portion 9b and the guide shaft 7 are sandwiched by a U-shaped portion, and a slidable sandwiching portion 9c is integrated. Since a force is applied, it has a holding force at a stationary position.

  The main driving shaft 5 and the passive shaft 6 are juxtaposed in a close state, and the passive shaft inserted into the main driving shaft 5 with respect to the recess 9f of the passive body 9 inserted into the passive shaft 6 as shown in FIG. The protrusions 8f of the body 8 are engaged with each other with play in the axial direction. For this reason, when the main moving body 8 moves on the main driving shaft 5, when the convex portion 8f rises and comes into contact with the upper limit 9fu of the concave portion 9f of the passive body, the passive body 9 receives the thrust of the main moving body 8 and rises in the combined state. In the downward movement of the main moving body 8, when the convex portion 8f comes into contact with the lower limit 9fd of the passive body concave portion 9f, the passive body 9 receives the downward thrust of the main moving body 8 and descends in the combined state. Yes.

  Specifically, the movement of the passive body 9 holding the zooming moving lens group 3 changes the photographing magnification, and the movement of the main moving body 8 holding the focusing moving lens group 4 is the focus of the subject at each magnification. Although it is for adjustment, in order to zoom, the convex part 8f of the main moving body 8 must be moved to the upper limit 9fu or the lower limit 9fd. In other words, the play amount of the concave portion 9f of the passive body 9 with respect to the convex portion 8f of the main moving body 8 becomes the focus adjustment range with respect to the subject distance at the photographing magnification. This is the range of X shown in FIG. For example, the position where the convex portion 8f of the main moving body 8 is in contact with the lower limit 9fd of the concave portion 9f of the passive body 9 is an infinite position in the magnification, and the position of contact with the upper limit 9fu is the closest position. For this reason, zooming is performed after shifting the adjustment from the infinite position to the closest position with respect to the subject, and then performing the focus adjustment again at a desired zoom position.

  FIG. 3 shows a relational operation when the main moving body 8 and the passive body 9 are moved. Specifically, this figure, FIG. 5 showing a schematic circuit block for controlling this operation, and FIG. The operation standard of this method is that the origin is always at the origin when the equipment is not used, the operation start position is from the origin, and the operation condition that always returns to the origin after the operation is finished. Imposing. First, in the state where the circuit of FIG. 5 is started, the operation is started from whether or not the main moving body 8 shown in FIG. Specifically, the origin position of the main moving body 8 is a position where the moving lens group 4 for focusing and the moving lens group for zooming are close to the second fixed lens group, for example, a combined position at an infinite distance at a wide angle position in this lens specification. Thus, it is located at the lower limit in the movable range of the main moving body 8 and the passive body 9. This is when it is in the state shown in FIG.

  When the circuit is in an activated state, as shown in the flowchart of FIG. 6, the origin is first confirmed at 35 from the start 30 of the operation, but the position signal by the magnet sensor 21 from the magnet scaler 20 of the main moving body 8 shown in FIGS. In 31, the CPU 50 recognizes the current position of the main moving body 8, and if it is determined that the main moving body 8 is not at the origin position, the main moving body 8 is moved up and down by the main moving body movement 34 to return to the origin. Thus, in the zooming operation, starting from the origin is a condition for the initial operation.

  Since the zoom position is Wide and the distance is an infinite position, it is determined whether or not the zoom Tele signal 32 indicated by 36 in FIG. 6 is output from the operation button 53 in FIG. If NO, the focus determination 37 is performed by measuring the subject Q in the Wide position. If the focus is not in focus, a signal is received from the CPU 50 to the driver 54 and the piezoelectric element 10 of the piezoelectric linear actuator is driven in the upward direction (+). A signal is sent and the main moving body 8 rises. Since focus adjustment is performed in the range of X shown in FIG. 3A, the upward movement is continued until the in-focus determination is obtained in 37 of FIG. In focus determination, the image of the subject Q is received by the image sensor 52, and the image signal is processed by the CPU 50 to determine whether or not it is in focus. When a determination of YES is obtained in 37 of FIG. 6, the power of the piezoelectric linear actuator is stopped by the stop signal from the CPU 50 (39 in FIG. 6), and the position of the focusing moving lens group 4 of the main moving body 8 is determined (FIG. 6). 6 END40).

  The above is the operation at the Wide position where the passive body 9 does not move. However, when the CPU 50 receives the Tele signal from the operation button 53 of FIG. 5, the transmission of the Tele signal of 32 shown in FIG. YES and the main moving body 8 is in the ascending (+) movement 41. When the main moving body 8 shown in FIG. 3B moves by the wide focus adjustment range X by continuing the upward movement, the convex portion 8f of the main moving body 8 comes into contact with the upper limit 9fu of the concave portion of the passive body 9. The main moving body 8 and the passive body 9 are combined. If the main moving body 8 continues to move upward as indicated by 43 in FIG. 6, the passive body 9 is pushed and lifted in the combined state, and continues until a zoom stop signal is received as indicated at 44. Is done.

  When reaching the Tele position, which is the maximum magnification, the operation of the operation button 53 in FIG. 5 is stopped, or the stop signal is sent from the CPU 50 by the limit signal by the magnet sensor 21 from the position of the magnet scaler 20 of the main moving body 8 shown in FIG. 54, the driving of the piezoelectric element 10 is stopped, and the piezoelectric element 10 is temporarily stopped while being united (45 in FIG. 6). 3 is the telephoto (Tele) position and the distance adjustment is a close position, so it is necessary to detect the in-focus position of the image of the subject Q. (No in 46 of FIG. 6), if NO, an inversion signal is sent from the CPU 50 to the driver 54, and a descent (-) drive signal is sent to the piezoelectric element 10 of the piezoelectric linear actuator, and the main moving body 8 is lowered. (47 in FIG. 6). At this time, only the main moving body 8 separates from the passive body 9 while the moving lens group 3 for zooming of the passive body 9 is placed at the current position (Tele position) and descends to obtain the focal point of the subject Q. (48 in FIG. 6). While the focus determination is repeated during this time, the focusing moving lens group 4 of the main moving body 8 is lowered, a stop signal is sent from the CPU 50 at a position where the focus determination is YES, the drive of the piezoelectric linear actuator is stopped, and the main drive The body 8 stops moving (49 in FIG. 6). This position is the focal point of the subject Q, the desired zoom is the telephoto (Tele) position, and the best image plane is obtained on the imaging plane of the image sensor 52 (END50 in FIG. 6). This is represented by the state (D) in FIG.

  In this state, the image of the subject Q can be confirmed on the monitor screen 51 of FIG. 5. To record the image at this time, the determination button at the center of the operation button 53 is pressed, and a shooting release signal is transmitted to the CPU 50. The image signal obtained by the element 52 is converted into a signal processed by the CPU 50 and sent to the memory circuit 55 as a recording signal to record an image.

  FIG. 3D shows an example in which the zoom is at the telephoto (Tele) position and the subject distance is at the intermediate position as described above, but the image magnification is continuously changed from the telephoto (Tele) to the wide angle (Wide). The case of changing the direction will be described below. A signal sent from the CPU 50 in response to a zoom Wide signal (33 in FIG. 6) that pushes the Wide button of the operation button 53 moves the drive of the piezoelectric linear actuator further in the downward direction. The main moving body 8 temporarily moves downward from the in-focus position shown in FIG. 3D to the in-focus infinite position, and the convex section 8f of the main moving body 8 is stationary. After contacting the lower limit 9fd of 9f, the main moving body 8 moves downward (Wide direction) while pushing the passive body 9 in the combined state. This shows the state shown in FIG. If the Wide signal from the operation button 53 is cut off at the desired zoom position, the main moving body 8 is stopped by the stop signal from the CPU 50, but the passive body 9 is stopped at the desired zoom position and separated from the passive body 9. Then, only the main moving body 8 moves in the upward direction and stops at the focal point. This is the same as the description of the dynamics from (A) to (D) described above in the state of FIG. 3 (F), and the moving direction of the main moving body 8 for control is only opposite.

  After the photographing or zooming operation by the device is completed, or when the device is de-energized, the main moving body 8 always moves downward, and returns to the state shown in FIG. It is programmed by the CPU.

  If the operation is taken into account as described above, the zoom lens mechanism can be completed with a very simple configuration. As shown in the exploded view of the lens barrel unit of FIG. The zoom lens barrel unit is completed simply by constructing and mounting on the lens frame 16 holding the second fixed lens group 2 and covering the outer cylinder 17 holding the first fixed lens. It can be provided as a product with good work efficiency.

It is a zoom lens mechanism diagram of the present invention. It is a perspective view from the main drive shaft and passive shaft side of this mechanism. It is operation | movement explanatory drawing of a main moving body and a passive body. It is an exploded view of the zoom lens barrel unit equipped with this mechanism. It is an electronic circuit block diagram for operating this book mechanism. It is a flowchart for operation | movement description. It is explanatory drawing of the vibration principle by the piezoelectric element of a piezoelectric linear actuator. It is a piezoelectric type linear actuator main body figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st fixed lens group 2 2nd fixed lens group 3 Zooming moving lens group 4 Focusing moving lens group Frame 5 Main driving shaft 6 Passive shaft 7 Guide shaft 8 Main moving body 9 Passive body 10 Piezoelectric element 11 Vibration shaft 12 Moving body 15 Base plate 16 Mirror frame 17 Outer cylinder 20 Magnet scaler 21 Magnet sensor

Claims (8)

A lens barrel having a fixed lens group at both ends along the optical axis and two moving lens groups in the middle of the fixed lens group. One of the moving lens groups has a variable shooting magnification of a subject. In a zoom lens mechanism in which the two movable lens groups of the lens barrel that is configured for focusing for focus adjustment and for focusing for focus adjustment can be moved along the optical axis, respectively. A main driving shaft and a passive shaft parallel to the optical axis are arranged around the center, and a main driving body integral with a lens frame of the focusing moving lens group is slidably inserted into the main driving shaft. In addition, a passive body integral with a lens frame of the zooming moving lens group is slidably fitted on the passive shaft, and the passive body of the passive shaft can be driven by driving the main body of the main driving shaft. The structure of the Zoomin A simple zoom lens mechanism characterized in that the moving lens group for focusing and the moving lens group for focusing are movable along the optical axis. The passive body integrated with the lens frame of the zooming moving lens group has a holding force to maintain a stationary position by a frictional force with respect to the passive axis, but the focusing moving lens group along the main driving axis. When a driving force when the main moving body integral with the lens frame moves reaches the passive body, the passive body also has a force relationship capable of moving together along the passive axis. Item 4. A simplified zoom lens mechanism according to Item 1. The main moving body and the passive body are in an adjacent parallel position, and are in an engaging relationship with play in the axial direction, and the movement of the main moving body along the main driving shaft is delayed by play and merges with the passive body. 3. The simple zoom lens mechanism according to claim 2, wherein a lens frame of the focusing moving lens group and the moving lens group for zooming are integrally movable along the optical axis. The main moving body and the passive body are in adjacent parallel positions and are in an engagement relationship with play in the axial direction, and the play is the focus for adjusting the focus at the moving position of the zooming moving lens group. 4. The simple zoom lens mechanism according to claim 2, wherein the movable lens group has an adjustment range that allows maximum movement. The zooming operation on the subject by the zooming moving lens group is an operation in which the main moving body moves in the engagement play portion with the passive body and moves after the uniting, and the zooming position is adjusted by the focusing moving lens group at the zoom position. 5. The simple zoom lens mechanism according to claim 4, wherein the main moving body is inverted and separated from the passive body and the movement is adjusted by moving the play portion. The position and amount of movement of the main moving body with respect to the origin position provided on the fixed side can be measured in a moving range along the main driving axis and the optical axis of the main moving body. Simple zoom lens mechanism. Around the optical axis, the main moving body moves linearly to a position substantially opposite to the main driving axis and the passive axis parallel to the optical axis with respect to the optical axis. 2. The simple zoom lens mechanism according to claim 1, further comprising a straight guide shaft that shares a guide and a guide for moving the passive body in a straight line. A main driving axis that is around the optical axis and is parallel to the optical axis is a vibration axis of a piezoelectric linear actuator in which a piezoelectric element is fixed to one end, and the main driving body that is fitted into the axis is 8. The simple zoom lens mechanism according to claim 1, wherein the zoom lens mechanism is driven by ultrasonic vibration in an axial direction of a vibration axis by a pulse signal applied to a piezoelectric element of the piezoelectric linear actuator.

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