JP2007272105A - Zoom lens barrel unit, imaging device, camera, portable information terminal device and mobile phone - Google Patents

Abstract

A drive mechanism is simplified and both zooming and focus adjustment are achieved simultaneously.
At least a negative first lens group, a positive second lens group, and a negative third lens group are provided. The first lens group is fixed, and the second lens group and the third lens are provided. The group 13 is linearly moved in the optical axis direction. The pedestal 2 having the fixed frame 3, the second lens frame 12c holding the second lens group 12 and forming an outer helicoid screw, and the third lens holding the third lens group 13 and forming an outer helicoid screw. An inner helicoid screw is formed in which the lens frame 13c, the outer helicoid screw of the second lens frame 12c and the outer helicoid screw of the third lens frame 13c are screwed together, and the main mirror is rotatable with respect to the fixed frame 3 A tube 4, a guide shaft 10 that is implanted in the pedestal 2, is parallel to the optical axis O, passes through the main barrel 4, and moves the second and third lens frames in the optical axis direction, and the pedestal 2 And a single drive motor 7 that rotationally drives the main barrel 4 via the speed reduction mechanism 9.
[Selection] Figure 1

Description

  The present invention relates to a zoom lens barrel that can be mounted on a portable information terminal device such as a thin digital camera or a mobile phone equipped with an image sensor, and in particular, a focal length can be freely selected and set by zooming. Further, the present invention relates to a zoom lens barrel unit, an imaging device, a camera, a portable information terminal device, and a mobile phone that can be further adjusted in focus (focusing).

The recent trend toward commercialization of portable information terminal devices such as digital cameras and mobile phones
On the other hand, as the functions become more and more functional, the tendency of thinning and miniaturization is remarkable with respect to the external thickness.

  In particular, with regard to digital camera imaging optical systems, zoom magnification tends to increase, and along with this, the number of lenses in the optical system increases, and the drive mechanism of the zoom lens barrel becomes more complicated and more accurate. It is in.

  As a result, each component is required to have a high degree of dimensional accuracy and a high degree of accuracy with respect to drive control. In mobile phones as well, there is an increasing demand for mounting a zoom lens function as a photographing lens system as the functionality increases.

  However, in spite of the demand for thinner and lighter weight, the lens configuration and zoom lens barrel drive mechanism are complicated, so the entire zoom lens barrel unit is enlarged and only stored. The current situation is that there is limited space.

  Recently, a so-called digital zoom system has been proposed as a solution to compensate for these shortcomings as much as possible, by processing an image of a digital signal obtained by single lens photography to give an impression that the angle of view changes. As is well known, according to this method, it is possible to obtain a feeling of zooming effect.

  However, if the magnification is increased more than necessary, there is a disadvantage that the image quality is deteriorated. By combining the zoom lens barrel mechanism with an optical system capable of selectively setting the two focal lengths (wide angle, telephoto) and digital zooming as a means to eliminate and supplement these shortcomings as much as possible. In addition, a method for minimizing image degradation and obtaining a continuous zooming effect has been proposed.

  However, in this method, a space for arranging a plurality of actuators for switching to two focal lengths (wide angle, telephoto) and actuators for adjusting the focal point is necessary, and the entire unit is enlarged. There is a point.

  As still another method, the photographic optical lens configuration includes a first lens group having a negative focal length from the subject side, a second lens group having a positive focal length, and a third lens group having a negative focal length. The first lens group is fixed, and the second lens group and the third lens group move on the optical axis in a straight line according to the rotation of the cylindrical cam device so that zooming and focusing adjustment can be performed. Yes.

  At the time of zooming, the second lens group and the third lens group move straight in the optical axis direction according to the rotation of the cam device while maintaining a predetermined air interval on the cylindrical cam. During focus adjustment, the second lens group is disposed on a flat surface that does not move in the front-rear direction even when the cylindrical cam device rotates.

  On the other hand, the third lens group moves straight in the optical axis direction while sliding on the tapered surface as the cylindrical cam device rotates, so that the air in the second lens group and the third lens group is moved. The question changes. As a result, focus adjustment can be adjusted.

  At this time, if the air space between the second lens group and the third lens group is narrowed, that is, the third lens group moves from the imaging surface side to the subject side direction, the subject distance is changed from the closest side to the infinite side, On the other hand, when the air space between the second lens group and the third lens group increases, that is, when the object moves straight from the subject side to the imaging surface side, the subject distance moves from the infinite side to the near side (focus movement). (See Patent Document 1 and Patent Document 2.)

  Certainly, according to this method, zooming and focusing adjustment can be performed with only one actuator. However, since there is a limit to the amount of movement of the second lens group and the third lens group in the optical axis direction, it is difficult to arrange a large number of flat cam portions necessary for focus matching adjustment. For these reasons, even if it is desired to select step zoom with a multifocal length, there is a difficulty that only about three points of wide angle, intermediate and telephoto can be set and selected.

  Apart from this, there is a zoom lens barrel of a two-group method (first lens group, second lens group) as a generally well-known method. The outer lens barrel, inner lens barrel, two-group moving frame, rectilinear key, fixed frame, and the like, and the outer lens barrel that is screwed into the helicoid screw formed in the fixed frame are powered by a motor disposed outside. To move straight forward.

  Further, it is screwed with the inner helicoid screw of the outer lens barrel, and is screwed with the helicoid screw disposed inside the outer lens barrel and the inner lens barrel containing the first lens group moving frame and shutter unit housing the first lens group. At the same time, the second group moving frame that slides on the cam groove provided on the inner helicoid screw of the outer barrel and mounts the second lens group has a predetermined air interval between the first lens group and the second lens group. While holding, it moves straight on the optical axis. The moving amount of the first lens group at this time is structured to move back and forth by the sum of the lead amounts of the respective helicoid screws formed around the outer barrel and the inner barrel.

  The second lens group is a system that moves back and forth based on the sum of the displacement amount of the cam attached to the inner wall of the outer barrel and the helicoid lead amount of the outer barrel (Patent Document 3, Patent). Reference 4 and Patent Document 5).

  As a result, in these cases, in order to accurately manage the air spacing, back focus, etc. of the first lens group and the second lens group, the occurrence of cumulative errors in each helicoid component is suppressed, and at the same time, the cam groove, cam It is required to strictly manage the accuracy of components such as follower pins.

  In addition, in the focus matching adjustment, in addition to the drive motor for zooming, it is necessary to move straight by another actuator, and a flexible wiring for sending a drive signal and current is required. As a result, a large amount of space is required for the arrangement of parts and the like, and at the same time, the structure becomes more and more complicated, which not only increases the overall structural dimensions, but also increases the unit price of the parts. There is a problem that assembly time longer than expected is required.

When such a zoom lens barrel structure is adopted as a driving mechanism for a photographing lens system in a mobile phone or the like, as a result of a complex barrel configuration, in a camera compatible with a silver salt film, there was no problem. Accumulated errors such as eccentricity errors and inclination errors become more serious problems than expected, and it can be imagined that it is difficult to ensure the machining and assembly accuracy of cam grooves and the like.
In addition, the outer surface spiral screw portion of the deployment cylinder is screwed with the inner surface spiral thread portion of the frame cylinder, and at the same time the deployment cylinder rotates, it moves linearly with respect to the frame cylinder, and the outer surface spiral split screw and screw formed on the front cylinder. An inner surface spiral screw portion is provided, and by rotating and driving a single zoom motor, the development cylinder rotates to move the front cylinder without rotating along the optical axis, and an outer lens group disposed on the front cylinder and There is known a linear movement mechanism that moves the lens group by a so-called female screw / male screw mechanism that moves the intermediate lens group from the wide-angle position to the telephoto position (see Patent Documents 6 and 7).

Furthermore, in the lens group linear movement mechanism using such a female screw / male screw mechanism, the outer lens group and the intermediate lens group are simply moved straight from the wide-angle position to the telephoto position without rotating, and from the first zoom position. In order to reach the second zoom position, a complicated cam mechanism is used so that the front lens frame and the rear lens frame continue to move toward the subject while the intermediate lens frame can move in the opposite direction. .
JP-A-2005-77713 JP 2005-77714 A Utility Model Registration No. 2535052 JP-A-5-297259 JP-A-8-313784 JP 2000-292675 A ([0028], [0031], [0035], [0036], [0037] FIGS. 16 and 17) Japanese Unexamined Patent Publication No. 2000-292676 ([0023], [0026], [0030], [0031], [0042])

  As described above, when the conventional technique is adopted, a multi-layered lens barrel is used as a driving unit of the optical lens system, and thus a driving mechanism having a complicated configuration is required to obtain a zooming function and a focus matching adjustment function. In addition to enlargement of the outer diameter, there is a problem that an actuator for zooming and focusing adjustment is required independently of each other.

  In order to solve such a problem, the present invention simplifies the drive mechanism using a single-layer structure lens barrel instead of the conventional multilayer structure lens barrel, and also provides a drive mechanism for a single drive motor. The goal is to achieve both continuous zooming and focus adjustment functions at the same time.

  In addition, the movement change during the driving of the lens system is uniformly and smoothly managed to simplify the driving structure, facilitate the securing of accuracy, and move straightly without rotating the lens group. Another object of the present invention is to prevent the eccentricity and inclination of the group, and to achieve a reduction in size, weight and thickness.

The zoom lens barrel unit according to claim 1 includes at least a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a negative focal length. A zoom lens barrel unit in which a lens group is fixed and the second lens group and the third lens group are linearly moved in the optical axis direction;
A pedestal having a fixed frame, a second lens frame that holds the second lens group and has an outer helicoid screw formed at the periphery, and an outer helicoid screw that holds the third lens group and is formed at the periphery. The third lens frame, an inner helicoid screw in which the outer helicoid screw of the second lens frame and the outer helicoid screw of the third lens frame are screwed are formed on the inner peripheral portion and rotated with respect to the fixed frame. A main lens barrel which is made possible, and which extends in parallel to the optical axis and which is implanted in the pedestal and penetrates the inside of the main lens barrel, and extends the second lens frame and the third lens frame in the optical axis direction. A guide shaft to be moved, and a single drive motor fixed to the pedestal and configured to rotate the main barrel through a rotation transmission mechanism.

  The zoom lens barrel unit according to claim 2, wherein the optical system includes a fourth lens group having a positive focal length, the first lens group and the fourth lens group are fixed, and the second lens group is fixed. The lens group and the third lens group are configured to move straight in the optical axis direction during zooming.

  The zoom lens barrel unit according to claim 3 is characterized in that an outer helicoid screw is formed in the main barrel, and rotational driving from the drive motor is transmitted to the main barrel via a speed reduction mechanism. And

  According to a fourth aspect of the present invention, in the zoom lens barrel unit, a rotation drive frame is rotatably provided on the fixed frame, and rotation drive from the drive motor is transmitted to the rotation drive frame via a speed reduction mechanism. The rotation of the frame is transmitted to the main lens barrel.

  According to a fifth aspect of the present invention, there is provided an imaging apparatus using the zoom lens barrel unit according to any one of the first to fourth aspects.

  The camera described in claim 6 uses the zoom lens barrel unit described in any one of claims 1 to 4.

  According to a seventh aspect of the present invention, a portable information terminal device uses the zoom lens barrel unit according to any one of the first to fourth aspects.

  A cellular phone according to an eighth aspect is characterized in that the zoom lens barrel unit according to any one of the first to fourth aspects is used.

  According to the present invention, the second lens frame and the third lens frame are commonly screwed into the main lens barrel to realize a single-layer structure of the lens barrel structure, and can be continuously driven only by a single drive motor. Scaling and focusing adjustment operations can be realized, and by moving the lens units straight without rotating during zooming, each lens unit is prevented from decentering and tilting, with improved operability and image quality. Thus, it is possible to provide a zoom lens barrel unit that can realize a reduction in size, weight, reduction in the number of parts, reduction in cumulative errors of parts, and shortening of assembly time.

  In addition, by mounting the zoom lens barrel according to the present invention, the size and weight of the zoom lens itself can be reduced, the number of parts can be reduced, and the cumulative error of parts can be reduced, while the change is excellent in operability. An imaging device, a camera, a portable information terminal device, and a mobile phone having both a magnification function and a focus matching adjustment function can be provided at low cost.

  Embodiments of the present invention will be described below with reference to the drawings.

  Note that the embodiments of the invention described below are merely examples of implementation, and the components (components), shapes, and arrangements shown in the drawings are not limited to these. .

  FIG. 1 is an exploded perspective view of a zoom lens barrel unit according to Embodiment 1 of the present invention as viewed from diagonally upward on the front side, and FIG. 2 is an explanatory view showing an assembled state of the zoom lens barrel unit shown in FIG. 2A is a sectional view of the lens barrel unit shown in FIG. 1 in an assembled state, and FIG. 2B is an enlarged view of the zoom lens barrel unit shown in FIG. FIG. 2C is a front view of the zoom lens barrel unit shown in FIG. 2B. FIG. 2D is a zoom lens barrel unit shown in FIG. It is the figure which looked at from the side.

  The zoom lens barrel unit 1 has a pedestal 2 as shown in FIG. A cylindrical fixed frame 3 is formed on the base 2. In the cylindrical fixed frame 3, arc-shaped openings 3a and 3b extending in the circumferential direction are formed on the outer periphery of the cylindrical fixed frame 3 at different angles in the circumferential direction.

  As shown in FIG. 2A, the main barrel 4 is rotatably supported on the cylindrical fixed frame 3. Reference numeral 4n denotes an annular sliding contact portion that smoothly contacts the inner peripheral portion of the cylindrical fixed frame 3. The main barrel 4 has a reduced diameter portion 4n 'between the annular sliding contact portions 4n and 4n, thereby reducing the friction area with respect to the cylindrical fixed frame 3.

  The main barrel 4 is provided with a gear 4a extending in the circumferential direction on the outer peripheral portion thereof. A part of the gear 4a is exposed to the outside through the arc-shaped opening 3a. The outer peripheral portion of the main barrel 4 is painted black, and a white belt portion 4b extending in the extending direction of the gear 4a is formed adjacent to the gear 4a on the outer peripheral portion. The white band portion 4b is exposed to the outside through the arc-shaped opening 3b by the rotation of the main barrel 4. Note that a white paint, a white seal, or the like is used for the white belt portion 4b.

  A motor mounting member 5 is fixed to the base 2 using screws 6. One drive motor 7 is fixed to the motor mounting member 5 via a bracket 7a '. A pinion gear 8 is fixed to the output shaft 7 a of the drive motor 7.

  A speed reduction mechanism 9 is disposed between the motor attachment member 5 and the base 2. The speed reduction mechanism 9 includes support shafts 9a and 9b, a two-stage gear 9c, and a gear 9d. The two-stage gear 9c is roughly composed of a large-diameter gear portion 9e and a small-diameter gear portion 9f. The two-stage gear 9c is rotatably supported on the support shaft 9a, and the gear 9d is rotatably supported on the support shaft 9b. The gear 9d can mesh with the small-diameter gear portion 9f, and the large-diameter gear portion 9e can mesh with the gear 4a via the arc-shaped opening 3a.

  An insertion hole 5a is formed in the motor attachment member 5, a bearing member 5b is provided in the insertion hole 5a, and the pinion gear 8 is attached to the output shaft 7a in a state where the output shaft 7a is rotatably supported by the bearing 5b. Fixed. The pinion gear 8 can be engaged with the gear 9d, and the engagement between the pinion gear 8 and the gear 9d is adjusted by adjusting the bearing member 5b.

  As shown in FIG. 1, an inner helicoid screw 4 c is formed on the inner periphery of the main barrel 4. A pair of guide shafts 10 extending in parallel with each other in the direction of the optical axis O are planted on the base 2. The guide shaft 10 passes through the inside of the main barrel 4.

  The zoom lens barrel 1 includes a first lens group 11, a second lens group 12, a third lens group 13, and a fourth lens group 14.

  The first lens group 11 is mainly composed of a lens 11a having at least a negative focal length and a ring-shaped first lens frame 11b for holding the lens 11a. The lens 11a is fixed to the first lens frame 11b.

  The first lens frame 11 b has an annular fitting portion 11 c that fits into the open end 3 c of the cylindrical fixed frame 3. A pair of fitting holes 11d into which the ends of the pair of guide shafts 10 are fitted at symmetrical positions with respect to the optical axis O are formed on the surface portion of the first lens frame 11b. A ring-shaped decorative plate 15 is attached and fixed to the front surface of the first lens frame 11b in order to shield unnecessary light incident from the periphery of the lens 11a and to prevent the lens 11a from falling off.

  The second lens group 12 includes lenses 12a and 12b having a positive focal length as synthetic lenses and a ring-shaped second lens frame 12c that holds the lenses 12a and 12b.

  An outer helicoid screw 12d is formed on the outer periphery of the second lens frame 12c. In the second lens frame 12c, a pair of arc-shaped through-holes 12e penetrating in the thickness direction is formed on the disk surface portion at symmetrical positions with the optical axis O in between. Lenses 12a and 12b are held and fixed to the second lens frame 12c so that their optical axes coincide with the optical axis O. Although the lens diaphragm is also provided in the second lens frame 12c, the illustration thereof is omitted here.

  The third lens group 13 includes a lens 13a having a negative focal length and a ring-shaped third lens frame 13c. An outer helicoid element 13d is formed on the outer periphery of the third lens frame 13c. A pair of circular through-holes 13e are formed at symmetrical positions across the optical axis O on the surface of the third lens frame 13c. A lens 13a is held and fixed to the third lens frame 13c so that its optical axis coincides with the optical axis O. Although the lens diaphragm is also provided in the third lens frame 13c, the illustration thereof is omitted here.

  The pair of guide shafts 10 and 10 pass through the circular through holes 13e and 13e of the third lens frame 13c and the pair of arc-shaped through holes 12e and 12e of the second lens frame 12c, and the end portions thereof are the first lens frame. It is fitted in a pair of fitting holes 11d of 11b. The pair of guide shafts 10 and 10 are configured not to contact the arc-shaped peripheral walls 12f and 12f of the arc-shaped through holes 12e and 12e when the second lens frame 12c rotates together with the rotation of the main barrel 4. The frictional force of the guide shafts 10 and 10 is prevented from acting on the second lens frame 12c.

  The fourth lens group 14 includes a cylindrical fixed frame 3 and a lens 14a as a part of the photographing optical system. The lens 14a is fixed to the base of the cylindrical fixed frame 3 so that its optical axis coincides with the optical axis O.

  The reason why the first lens group 11 has a negative focal length in the optical system of the zoom lens barrel unit 1 is that, on the wide angle side, in order to guarantee a wide angle of view, an image surface on the wide field angle side or a negative focal length. This is to improve the distortion aberration performance and to design the outer diameter of the lens 11a as small as possible.

  If the second lens group 12 is composed of two lenses 12a and 12b having a positive focal length and a negative focal length, the correction performance for chromatic aberration and spherical aberration is improved.

  When the second lens group 12 and the third lens group 13 are moved linearly along the optical axis O, the zooming function and the correction (compensator) function are compensated. Further, by moving the third lens group 13 straightly with respect to the second lens group 12, a focus matching adjustment function is achieved.

  Zooming is performed by moving the second lens group 12 and the third lens group 13 straight together to form a pair of movable lens groups in a state where the air gap between the second lens group 12 and the third lens group 13 is as small as possible. The function of the optical system is fulfilled.

  The fourth lens group 14 has a function of suppressing an increase in the incident angle of the chief ray to the image pickup device (described later), particularly on the wide-angle side, and at the same time, positive distortion on the telephoto side. It plays a role of suppressing the increase.

  In the embodiment of the present invention, the fourth lens group 14 is provided. However, when a lens system having a long total length is used, the incident angle of the image sensor 15a may be somewhat relaxed, or the back focus may be long. For example, a zoom optical system can be configured using the first lens group 11, the second lens group 12, and the third lens group 13 without providing the fourth lens group 14.

  An imaging element unit 15 is attached to the pedestal 1 on the back side of the cylindrical fixed frame 3, 15 a is an imaging element of the imaging element unit 15, and a CCD, a CMOS sensor, or the like is used for the imaging element 15 a. . The image sensor 15a is disposed on the image plane formed by the lens 14a.

  The outer helicoid screw 12d of the second lens frame 12c and the outer helicoid screw 13d of the third lens frame 13c have the same pitch as the inner helicoid screw 4c of the main barrel 4, and the outer helicoid screw 12d and the outer helicoid screw 13d are The second lens frame 12c and the third lens frame 13c are held by the main barrel 4 by being screwed into the inner helicoid screw 4c.

  A light-emitting / light-receiving photosensor 16 is fixed to the pedestal 2, and this photosensor 16 is exposed to the rotation area of the white belt portion 4b through the arc-shaped opening 3b. The photosensor 16 serves as a rotation drive start switch. Play a role.

  Since the rotation of the second lens frame 12c and the third lens frame 13c is restricted by the guide shaft 10, the second lens frame 12c and the third lens frame 13c operate so as to move straight in the optical axis direction in accordance with the zooming operation by the rotation of the main barrel 10, and will be described later. During the focus matching adjustment, the second lens frame 12c rotates integrally with the main lens barrel 10 in the rotation region between the end wall 12e ′ and the end wall 12e ″ of the arc-shaped through hole 12e of the second lens frame 12c. Therefore, the second lens frame 12c operates so that the third lens frame 13c moves straight in the optical axis direction while holding the movement stop in the optical axis direction.

  Next, the white belt portion 4b will be described with reference to FIG. FIG. 3 is a development view of the white belt portion 4b.

  In FIG. 3, symbol A indicates the telephoto end position during normal magnification operation, and symbol B indicates the wide-angle end position during normal magnification operation. Reference symbol A ′ indicates a movement end position on the telephoto side of the second lens frame 12c, which is a useless position in a normal zooming operation. For example, a circuit or a drive mechanism has an abnormality during a drive rotation operation. This is the position where the drive is forcibly stopped when it occurs.

  Similarly, symbol B ′ is a movement end position on the wide-angle side of the second lens frame 12 and is a useless position in a normal zooming operation. For example, an abnormality occurs in a circuit or a drive mechanism during a drive rotation operation. This is the position where the drive is forcibly stopped when it occurs.

  Note that the position indicated by symbol A may be the wide-angle end position during normal magnification operation, and the position indicated by symbol B may be the telephoto end position during normal magnification operation.

  The end 4b ′ of the white band 4b is used to obtain a reset signal for detecting the home position after the second lens frame 12c rotates. When the end 4b ′ is detected by the photosensor 16, the end 4b ′ is illustrated. The drive motor 7 is rotated by a predetermined number of count pulses by a drive circuit that omits the symbol, and the second lens group 12 and the third lens group 13 are positioned at a reference position (home position). This home position can be determined as appropriate.

  Next, the zooming function and the correction function when the second lens group 12 and the third lens group 13 are linearly moved along the optical axis O will be described with reference to FIG.

  First, the wide-angle shooting optical position and the telephoto shooting optical position will be described.

  In a general photographing optical system, at the time of zooming, the second lens group 12 and the third lens group 13 located on the wide angle side move to the telephoto side while maintaining a constant air interval. The function of correcting the air gap between the second lens group 12 and the third lens group 13 in order for a specific subject existing at a finite distance to be photographed while being focused on the imaging surface during zooming operation. is necessary.

  In general, with the zooming operation from the wide-angle position to the telephoto position, the air distance between the second lens group 12 and the third lens group 13 is the wide-angle position and the telephoto position regardless of infinite distance or finite distance. It spreads out and approaches at an intermediate position. FIG. 4 is a diagram for explaining this, and the vertical axis indicates the reference position (home position) of the second lens group 12 and the third lens group 13 at the wide position (W), the intermediate position (N), and the telephoto position. The amount of movement from

  The air space between the second lens group 12 and the third lens group 13 shown in FIG. 2A will be described using the curve shown in FIG. FIG. 4 is a diagram showing the amount of movement of the second lens group 12 and the third lens group 13 from the reference position and the amount of change in the air interval at the wide angle position (W), the intermediate position (N), and the telephoto position (T). is there.

  In FIG. 2A, the second lens frame 12c and the third lens frame 13c are present at the telephoto position (W). The reference position is assumed to be at an appropriate position.

  At the wide position (W), the second lens frame 12c and the third lens frame 13c are driven by a predetermined pulse from the reference position, and then the second lens frame 12c is stopped driving, while the third lens frame 13c is The focus is returned from the position focused at infinity to the close range, and thereby the focus adjustment is performed in the range from the infinity focus position (∞) at the wide angle position to the close range.

  At the intermediate position (N), the second lens frame 12c and the third lens frame 13c are pulse-driven more than the wide position (W) from the reference position, and then the second lens frame 12c is stopped driving, On the other hand, the lens frame 13c is returned from the position focused at infinity to the closest distance, and thereby the focus adjustment is performed in the range from the infinite focus position (∞) at the wide angle position to the closest distance. .

  At the telephoto position (T), the second lens frame 12c and the third lens frame 13c are pulse-driven more than the intermediate position (N) from the reference position, and then the second lens frame 12c is stopped driving, On the other hand, the lens frame 13c is returned from the position focused at infinity to the closest distance, and thereby the focus adjustment is performed in the range from the infinite focus position (∞) at the wide angle position to the closest distance. .

  The position of the minimum air interval exists at an intermediate position (N) between the wide angle position (W) and the telephoto position (T).

  Here, the symbol P1 indicates a curve connecting the movement positions of the second lens frame 12c at each of the wide angle (W), middle (N), and telephoto (T) positions, and the symbol P2 is a wide angle (W), middle ( N) shows a curve connecting the maximum movement stop position of the third lens frame 13c at the time of zooming at each position of telephoto (T), P3 being wide angle (W), intermediate (N), telephoto (T) The moving position of the third lens frame 13c when the focus is adjusted to infinity at each of the positions is indicated, and the symbol P4 indicates the close distance at each of the wide angle (W), middle (N), and telephoto (T) positions. The movement position of the third lens frame 13c when focus adjustment is performed is shown.

  As can be understood from FIG. 4, the minimum value of the air separation distance between the second lens group 12 and the third lens group 13 is a substantially intermediate position of the photographing optical system and the focus matching position is an infinite distance. It is in.

  The maximum value of the air separation distance between the second lens group 12 and the third lens group 13 is the wide-angle position or the telephoto position of the photographing optical system, and the focus matching adjustment distance is at a close distance.

  That is, at the time of zooming from the wide-angle position to the telephoto position, the air distance is the minimum amount in the movement range from the minimum amount to the maximum amount of the air interval between the second lens group 12 and the third lens group 13. Is the intermediate position of the photographic optical system, and when the focal position is at infinity, and the position where the air gap is the maximum is the wide-angle position or the telephoto position of the photographic optical system. This is when the focus matching position is at a close distance.

  As a result, if the moving distance can be compensated at least within the range from the minimum amount to the maximum amount in which the air separation distance between the second lens group 12 and the third lens group 13 changes, it is possible to adjust the focus adjustment over the entire zoom range. become.

  During the focus matching adjustment, the second lens frame 12 and the third lens frame 13 are released from the integral movement, and the third lens group 12 is stopped in the state where the movement of the second lens group 12 in the optical axis direction is stopped. Only 13 straight movements are performed.

  At that time, when the subject distance is changed from infinity to the closest distance, the third lens group 13 moves straight, that is, the focal distance is increased while the air distance between the second lens group 12 and the third lens group 13 is increased. Mate adjustment is performed.

  Next, the power transmission of the drive motor 7 will be described with reference to FIGS. 1 and 2 (a).

  When the drive motor 7 rotates, the rotation of the pinion gear 8 is transmitted to the gear 9d, the rotation of the gear 9d is transmitted to the two-stage gear 9c, and the rotation of the large-diameter gear portion 9e of the two-stage gear 9c is transmitted to the gear 4a. Thus, the main lens barrel 4 is rotated within the cylindrical fixed frame 3.

  Assuming that the guide shaft 10 is in contact with the end wall 12e 'of the arc-shaped through hole 12e of the second lens frame 12, when the main barrel 4 rotates counterclockwise, the second lens frame 12 is integrated with the guide lens 10 Since the main lens barrel 4 and the second lens frame 12 are rotated together in a direction away from the end wall 12e ′, the movement of the second lens frame 12 in the optical axis direction remains stopped.

  On the other hand, since the third lens frame 13 is prevented from rotating by the pair of guide shafts 10 even when the main lens barrel 4 rotates, the direction in which the pair of guide shafts 10 extend relatively by the action of the helicoid. Move straight ahead.

  When the guide shaft 10 comes into contact with the end wall 12e ″ of the arc-shaped through hole 12e of the second lens frame 12, the second lens frame 12 and the third lens frame 13 start to move linearly integrally. At this time, the air distance between the second lens frame 12 and the third lens frame 13 is set to the minimum distance.

  Since the pair of guide shafts 10 are disposed at symmetrical positions with respect to the optical axis O, the second lens frame 12 and the third lens frame 13 move straight without causing any eccentricity or inclination.

  On the contrary, when the main lens barrel 4 is driven to rotate clockwise as viewed from the object side, the second lens frame 12 is rotated in a direction away from the end wall 12e ″ together with this, Since the lens barrel 4 and the second lens frame 12 rotate integrally, the movement of the second lens frame 12 in the optical axis direction remains stopped, whereas the third lens frame 13 is the main mirror. Even if the cylinder 4 rotates, the rotation is prevented by the pair of guide shafts 10, so that the cylinder 4 is relatively moved straight in the extending direction of the pair of guide shafts 10 by the action of the helicoid.

  When the guide shaft 10 comes into contact with the end wall 12e 'of the arc-shaped through hole 12e of the second lens frame 12, the second lens frame 12 and the third lens frame 13 start to move linearly integrally. At this time, the air gap distance between the second lens frame 12 and the third lens frame 13 is set to the maximum distance.

  Here, the set minimum approach value of the air distance between the second lens group 12 and the third lens group 13 employs the minimum value distance value at the infinity distance of the subject from the wide-angle position to the telephoto position in the zooming range.

  In addition, the maximum separation value of the air distance between the second lens frame 12 and the third lens frame 13 employs the maximum distance value at the close distance of the subject from the wide angle position to the telephoto position in the zooming range. These values can be arbitrarily set.

  As a result, when the main lens barrel 4 rotates counterclockwise, that is, when zooming in the direction from the wide-angle position to the telephoto position, the second lens group 12 and the third lens group 13 minimize the air distance. While keeping the interval value, it moves straight in one.

  Next, at the time of focusing adjustment, after the zooming operation is completed, the second lens frame 12c is temporarily held in a state where the linear movement is stopped, and only the third lens frame 13c is linearly moved in a direction away from the subject. Thus, the straight movement is performed in the direction in which the air distance between the second lens group 12 and the third lens group 13 is increased. That is, the focus adjustment adjustment of the subject is performed by moving only the third lens frame 13 from the infinite edge side to the closest distance side.

  Here, according to the embodiment of the present invention, zooming is performed by using the single drive motor 7 to move the second lens frame 12c and the third lens frame 13c in a straight line without rotating. it can. Further, by rotating the second lens frame 12c integrally with the main barrel 4 within a predetermined angle range, the movement in the direction along the optical axis O is stopped, while only the third lens frame 13c is irradiated with light. By moving along the axial direction, the focus matching adjustment can be performed.

  In addition, since the second lens group 12 and the third lens group 13 are guided by the two guide shafts 10 during the magnification change and are moved straight, the optical axes of the second lens 12a and the third lenses 13a and 13b. The zooming operation can be performed in a state where the two are accurately matched. As a result, it is possible to obtain the effect of preventing the eccentricity and the inclination when the second lens group 12 and the third lens group 13 are moved straight by the rotation of the main barrel 4.

  Next, an embodiment of the invention in which the zoom lens barrel unit according to the present invention is applied to a mobile phone will be described with reference to FIGS.

  FIG. 5 is an external view of a cellular phone 17 according to the present invention, and this cellular phone 17 is composed of a main body portion 17a and an openable / closable lid portion 17b. FIG. 6 shows a state in which the cover 17b of the mobile phone 17 is opened.

  The main body portion 17a is provided with a zoom lens barrel unit 1 constituting a camera, and a dust-proof glass 17c for protecting the lens is provided at the tip of the zoom lens barrel unit 1.

  As shown in FIG. 6, in addition to the zoom lens barrel unit 1 and various operation keys and buttons, a release button 17d, a wide-angle switching button 17e, and a telephoto switching button 17f are disposed in the main body 17a. A liquid crystal monitor 17g is disposed on the lid portion 17b. On the liquid crystal monitor 17g, the video imaged by the camera is signal-processed and displayed.

  The wide-angle switching button 17e performs a function of moving the second lens group 12 and the third lens group 13 straight to the wide-angle end position by continuing to press this, and the telephoto switching button 17f continues to press the second lens group 12 and 13 The group 12 and the third lens group 13 function to move straight from the wide-angle end position toward the telephoto end position. The release button 7 performs a function of executing shooting.

  Since the details of the operation of the mobile phone 17 are not directly related to the present invention, the detailed description thereof is omitted.

  Thus, the zoom lens barrel unit according to the present invention can be applied to a barrel mechanism of a portable information terminal device such as a mobile phone or a PDA (Personal Digital Assistant), or a barrel mechanism of a digital camera or a silver salt camera. It is.

  In the first embodiment, the arc-shaped hole 12e is formed in the second lens frame 12c. However, the circular hole may be provided in the second lens frame 12c and the arc-shaped hole may be provided in the third lens frame 13c. good.

  FIG. 7 is an exploded perspective view of the zoom lens barrel unit according to the second embodiment of the present invention, as viewed from diagonally upward on the front side.

  In the first embodiment, a gear 4a and a white belt portion 4b are provided on the outer peripheral portion of the main barrel 4, and arc-shaped openings 3a and 3b for exposing the white belt portion 4b and the gear 4a to the fixed frame 3 to the outside. In the second embodiment, instead of these, an arc-shaped cutout hole 3z is formed in the outer peripheral portion of the fixed frame 3, and the outer peripheral portion of the fixed frame 3 is rotated so as to be rotatable. A drive frame 18 is provided.

  A gear 18a is formed on the outer periphery of the rotation drive frame 18, and a light shielding plate 18b is formed. A through hole 18 c is formed in the outer peripheral portion of the rotary drive frame 18.

  On the pedestal 2, a photo sensor 18 d is fixed in the rotation area of the light shielding plate 18 b. The main barrel 4 is provided with a fitting hole 4q, and the rotation drive frame 18 and the main barrel 4 are integrally coupled through a through hole 18c, an arc-shaped cutout hole 3z, and a coupling pin 18e. The light shielding plate 18b has the same function as the white band 4b of the first embodiment, and the photosensor 18d plays a role of detecting the wide-angle end position and the telephoto end position of the first embodiment in cooperation with the white band 4b. .

  The gear 18a is meshed with the large-diameter gear portion 9e of the two-stage gear 9c, and the rotation of the drive motor 7 is transmitted to the rotary drive frame 18 via the speed reduction mechanism 9, and the main lens barrel 4 rotates integrally with the rotary drive frame 18. Driven.

  The remaining configuration is the same as that of the zoom lens barrel unit of the first embodiment, and the same components are denoted by the same reference numerals and detailed description thereof is omitted.

  Moreover, since the effect | action is also the same, the detailed description is also abbreviate | omitted.

It is a perspective view which decomposes | disassembles and shows the component of Example 1 of the invention concerning the zoom lens barrel unit of this invention. It is explanatory drawing which shows the assembly state of the zoom lens barrel unit shown in FIG. 1, (a) is the sectional drawing, (b) is the external view, (c) is the front view, (d) is the side view FIG. It is an expanded view of the white belt part shown in FIG. It is explanatory drawing which shows the variation | change_quantity of the air space | interval of the 2nd lens group and a 3rd lens group in a wide angle position (W), an intermediate position (N), and a telephoto position (T). 1 is an external view of a mobile phone according to the present invention. FIG. 6 is a perspective view showing a state in which a lid of the mobile phone shown in FIG. 5 is opened. It is a perspective view which decomposes | disassembles and shows the component of Example 2 of the invention concerning the zoom lens barrel unit of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Zoom lens barrel unit 2 ... Base 3 ... Fixed frame 4 ... Main barrel 7 ... Drive motor 10 ... Guide shaft 11 ... 1st lens group 12 ... 2nd lens group 12c ... 2nd lens frame 13 ... 3rd lens Group 13c ... Third lens frame

Claims (8)

At least a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a negative focal length, wherein the first lens group is fixed, and the second lens group and the second lens group The third lens group is a zoom lens barrel unit that is linearly moved in the optical axis direction,
A pedestal having a fixed frame;
A second lens frame holding the second lens group and having an outer helicoid screw formed in the periphery thereof;
A third lens frame holding the third lens group and having an outer helicoid screw formed in the periphery;
A main lens barrel in which an inner helicoid screw into which the outer helicoid screw of the second lens frame and the outer helicoid screw of the third lens frame are screwed is formed on the inner peripheral portion and is rotatable with respect to the fixed frame. When,
A guide shaft that is implanted in the pedestal, extends parallel to the optical axis, penetrates through the main lens barrel, and moves the second lens frame and the third lens frame in the optical axis direction;
A zoom lens barrel unit, comprising: a single drive motor fixed to the pedestal and configured to rotationally drive the main barrel through a speed reduction mechanism.   The optical system includes a fourth lens group having a positive focal length, the first lens group and the fourth lens group are fixed, and the second lens group and the third lens group are at the time of zooming. The zoom lens barrel unit according to claim 1, wherein the zoom lens barrel unit is configured to move straight in the optical axis direction.   2. The zoom according to claim 1, wherein an outer helicoid screw is formed in the main lens barrel, and rotational driving from the drive motor is transmitted to the main lens barrel via a speed reduction mechanism. Lens barrel unit.   A rotation drive frame is rotatably provided on the fixed frame, rotation drive from the drive motor is transmitted to the rotation drive frame via a speed reduction mechanism, and rotation of the rotation drive frame is transmitted to the main lens barrel. 3. The zoom lens barrel unit according to claim 1, wherein the zoom lens barrel unit is a zoom lens barrel unit.   An imaging apparatus using the zoom lens barrel unit according to any one of claims 1 to 4.   A camera using the zoom lens barrel unit according to any one of claims 1 to 4.   A portable information terminal device using the zoom lens barrel unit according to any one of claims 1 to 4.   A mobile phone using the zoom lens barrel unit according to any one of claims 1 to 4.

Images