JP5288913B2 - Optical equipment - Google Patents

Description

  The present invention relates to an optical apparatus, and more particularly to an optical apparatus having a moving lens group that moves on an optical axis during focusing or zooming.

  In recent years, in optical devices such as cameras, the size of lens barrels and the image size of solid-state image sensors have been rapidly reduced, and many synthetic resin materials are used for the lens barrel and optical system holding members. Has been. When synthetic resin materials are used for the lens barrel and the holding member of the optical system, these members can be easily molded by a mold, and the shape is highly arbitrary, and the cost merit is large compared to other materials. There are many advantages such as.

  When synthetic resin materials are used for the lens barrel and the holding member of the optical system, there are many advantages as described above. On the other hand, there are changes in physical properties and dimensions with respect to environmental changes, particularly temperature changes and humidity changes. There is a problem of being big. For example, if synthetic resin is used for the structural material of the lens barrel, the adverse effect on the performance that the focal length, the focus position, etc. change greatly depending on the temperature, compared to the case where a metal material is used. .

  FIG. 11 is an explanatory diagram of the cam locus when the position of each moving lens group is controlled, with the horizontal axis as the position of the variator lens group and the vertical axis as the position of the focus lens group (RR). . The left end of the horizontal axis indicates the focal length at the wide angle position (hereinafter “WIDE”), and the right end of the horizontal axis indicates the focal length at the telephoto position (hereinafter “TELE”). Below the vertical axis is the infinite focus position, and above the vertical axis is the closest focus position.

  In general, the shape of the cam trajectory is the cam trajectory A when the subject distance is infinite. In other words, it rises gently from the WIDE end to the MIDDLE position, passes through a gentle apex at the MIDDLE position, and forms a continuous mountain-shaped curve from the MIDDLE position to the TELE end.

  As a feature of this cam locus, it is known that the slope from the MIDDLE position to the TELE end becomes steeper as it approaches the TELE end. The steepest inclination is expressed by [dy / dx] at a position where the zoom state is TELE and the subject distance is infinity. The fact that this numerical value is large indicates that the focus lens group (RR) must be moved greatly with respect to the movement of the variator lens group. Furthermore, it is known that the slope becomes steep when the magnification becomes higher.

As close to the present invention, Patent Document 1 proposes a method of obtaining the shift amount of the imaging plane position from the temperature change and correcting the position of the focus lens group (RR).
Japanese Patent No. 3581513

  However, as the optical system is increased in magnification and the lens barrel is further reduced, the steep slope [dy / dx] near the TELE end of the cam locus suddenly increases as described above. . As specific numerical examples, (1) the inclination [dy / dx] is about −11 to −13 when the optical magnification is about 20 to 35 times, and (2) the inclination [dy is when the optical magnification is about 40 times. / Dx] = about -30. In the prior art disclosed in the above-mentioned patent document, when the position of the variator lens group is displaced due to the influence of temperature, the amount of displacement of 30 times must be moved. Furthermore, since a space in which the focus lens group (RR) can move is required, the problem arises that the total length of the lens barrel increases.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical apparatus that solves the above-described problems, maintains a high magnification even when a temperature change occurs, and does not defocus.

In order to achieve the above object, the present invention provides a first driving means for driving a variator lens, a second driving means for driving a focus lens, a temperature detection means, and an image formed by the movement of the variator lens. An optical apparatus comprising: control means for controlling the focus lens to move so as to correct a change in the surface; and storage means for storing a cam locus indicating the position of the focus lens corresponding to the position of the variator lens. Because
When the moving position or movable range of the focus lens that is driven to correct a change in the image plane due to the movement of the variator lens is within the infinite end of the focus lens , the control means detects the temperature. The focus lens is driven without driving the variator lens in order to correct the change in the image plane due to the movement of the variator lens based on the correction amount calculated based on the temperature detected by the means,
When the moving position or movable range of the focus lens that is driven to correct the change in the image plane due to the movement of the variator lens is outside the infinite end of the focus lens , the control means detects the temperature. The variator lens and the focus lens are driven on a cam trajectory corrected based on the temperature detected by the means.

  According to the present invention, it is possible to maintain magnification and focus even when a temperature change occurs in an optical apparatus.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Reference Example 1)
FIG. 1 is a schematic explanatory diagram of Reference Example 1 of the optical apparatus of the present invention.

  In FIG. 1, reference numeral 1 denotes a lens barrel, which includes a four-group rear focus zoom lens (hereinafter referred to as an “RFZ lens”) including four lens groups.

  The RFZ lens 1 includes a first lens group (hereinafter “front lens”) 101 which is a fixed lens group, a second lens group (hereinafter referred to as “variator lens group”) 102 which is a moving lens group having a zooming function, and a fixed lens. A third lens group (hereinafter referred to as “afocal”) 103 which is a group is disposed.

  The movable lens group is composed of a fourth lens group (hereinafter referred to as “RR”) 104 having a focus function and a function as a compensator that corrects an image plane variation due to zooming by the second group.

  Actually, the lens group is composed of a plurality of lenses, and the number of lenses in each lens group is not particularly limited.

  102a is a holding member (hereinafter referred to as “V moving ring”) for holding the variator lens group 102, 104a is a holding member (hereinafter referred to as “RR moving ring”) for holding the focus lens group (RR) 104, A plastic material such as polycarbonate mixed with glass fibers is used for molding by molding or cutting.

  Reference numeral 110 denotes a lens group holding member (hereinafter referred to as “lens barrel”), which is manufactured by molding or cutting using a plastic material such as polycarbonate.

  In the present invention, the lens barrel and the moving ring are not particularly limited to the above materials and manufacturing methods, and for example, a metal material such as aluminum or titanium may be formed by die casting. Moreover, what was manufactured by secondary processing after die-casting, or what was directly cut from the block may be used.

  In addition, the lens barrel 110 may be divided into several members, and the number of members is not particularly limited. For example, it may be formed of two members divided parallel to the optical axis 105 of the RFZ lens 1, or may be formed of two members divided perpendicularly to the optical axis 105. You may form from.

  Reference numeral 111 denotes a diaphragm member for adjusting the amount of light incident on the photoelectric conversion element 2 such as a CCD. By driving the diaphragm blades in the diaphragm member 111 substantially perpendicularly to the optical axis 105 by driving means such as an iG meter or a step motor, the area of the opening of the diaphragm member 3 is varied to adjust the light amount.

In this reference example 1 , the amount of light is adjusted by the mechanical diaphragm member 111. However, the diaphragm unit is not limited to this, and has an electrochromy function for controlling the light transmittance by an electrochemical action. A so-called physical property stop may be used.

  An optical low-pass filter 106 such as quartz and an infrared removing filter 107 are installed in front of the photoelectric conversion element 2.

  Reference numerals 108 and 109 denote driving means (lens driving means) such as step motors for driving the moving lens groups 102 and 104. Reference numerals 108a and 109a denote lead screw screws whose surfaces are threaded at a predetermined pitch. Reference numerals 108b and 109b denote racks, which are formed as the same members as the V moving ring 102a and the RR moving ring 104a. The racks 108b and 109b mesh with the lead screw screws 108a and 109a, and when the step motors 108 and 109 are rotated forward and backward, the V moving ring 102a and the RR moving ring 104a move in parallel with the optical axis 105, and the variator lens group 102 And RR104 move in parallel along the optical axis.

Reference numerals 112 and 113 denote photo interrupters. 112a and 113a are light shielding plates, respectively, which are the same member as the V moving ring 102a and the RR moving ring 104a, or are separately disposed as a single member on the V moving ring 102a and the RR moving ring 104a. The light shielding plates 112a and 113a change the signals of the photo interrupters 112 and 113 due to the movement of the V moving ring 102a and the RR moving ring 104a. “Lens initial reset position”). In the first reference example , relative position information from the initial reset position of each lens is detected by counting the number of drive pulses for driving the step motor with respect to the lens initial reset position.

In the first reference example , the combination of the photo interrupter and the light shielding plate is used as the lens initial reset position detecting means. Instead, for example, a combination of a Hall element and a magnet, a combination of PSD and iRED, or the like. May be used.

Further, in this reference example 1 , the combination of the step motor and the lens initial reset position detecting means is adopted. However, it is not particularly limited to the configuration of Reference Example 1 .

  Reference numerals 3 and 4 denote RR / variator lens group drive units, which are drive circuits for driving the variator lens group 102 and RR104.

  Reference numeral 114 denotes temperature detection means (temperature sensor, environment detection means) such as a thermistor and a temperature sensitive resistor. The temperature detection circuit 5 outputs an output signal corresponding to the temperature to the control circuit 13 such as a microcomputer.

In the first reference example , the temperature detecting means 114 is arranged in front of the lens. This is because the front lens 101 and the variator lens group 102 have a greater influence on the temperature change than the other lens groups.

  A camera signal processing unit 6 processes an output signal from the photoelectric conversion element 2 and outputs it as an image signal. In addition, an evaluation value necessary for autofocus or the like is generated from the video signal. Reference numeral 14 denotes storage means (first storage means) such as a ROM for storing control information of the variator lens group 102 and the RR 104.

  The control information storage unit 8 stores the positional relationship between the focus lens group (RR) and the variator lens group to be satisfied during the zoom operation, calculates the correction amount of the focus lens group (RR) and the variator lens group based on the temperature change amount, and the focus lens group (RR). Data necessary for control such as a movable range) is stored.

  Reference numeral 7 denotes a focus lens group (RR) / variator lens group calculator. The focus lens group (RR) / variator lens group calculation unit 7 calculates the designated positions of the variator lens group and the focus lens group (RR) based on the control information in the control information storage unit 8, and the variator lens group drive unit 4 or the focus A zoom operation is performed via the lens group (RR) drive unit 3. Further, overall control of the variator lens group and the focus lens group (RR) such as calculation of the position of the focus lens group (RR) from the evaluation value from the camera signal processing unit 6 is performed.

  Reference numeral 9 denotes an angle-of-view designation unit, which is a manually-operated angle-of-view designation member, or a unit that transmits a command from the outside such as a PC. When performing a zoom operation, a focus lens group (RR) / variator lens group calculation unit 7 specifies the angle of view information.

  In order to perform zooming while maintaining the focus state, the RFZ lens 1 has a lens stop position on the optical axis of the variator lens group 102 for each subject distance, that is, a stop position on the optical axis of the RR 104 with respect to the zoom position. Yes.

  FIG. 2 is a diagram in which stop positions on the optical axis of the variator lens group 102 and the RR 104 are plotted for each subject distance (hereinafter, these curves are “cam loci”).

  In FIG. 2, for example, when the subject distance is infinity (or 2 m), when the variator lens group 102 moves from WIDE to TELE on the optical axis, the RR lens 104 has a locus convex toward the object side on the optical axis. It moves along the curve Y∞ (or Y2).

As described above, in the first reference example , when zooming from WIDE to TELE or from TELE to WIDE, the variator lens group 102 and the RR 104 are driven and controlled so as to trace the cam locus according to the subject distance. A good image without focus error is obtained.

  However, in the optical system, generally, a change in the shape of the lens holding member is caused by an environmental change such as a temperature change, the distance between the lenses is expanded and contracted, and the image plane is displaced.

For this reason, the focal length of each lens group changes, and the total focal length of the RFZ lens 1 also changes. As a result, the imaging plane position is deviated from the imaging plane at the reference temperature T0. That is, a focus shift occurs. Therefore, during the zoom operation, when the temperature change ΔT occurs with respect to the reference temperature T0, the cam locus traced by the moving lens group is corrected so as to correct the image plane position shift caused by the temperature change ΔT. There is a need to. In the reference example 1 , the reference temperature T0 is set to 20 ° C. However, it is not particularly limited to this temperature. Since the RFZ lens 1 has a solid variation, it is necessary to adjust the relative positional relationship between the variator lens group 102 and the RR 103 for each lens. The reference temperature T0 may be the temperature at the time of the adjustment.

  FIG. 3 shows an example of a cam locus (however, the subject distance is infinite) when the temperature is (T0 + 30) ° C. and (T0−30) ° C. with respect to the reference temperature T0.

  Generally, when the temperature of the RR lens 104 becomes higher than the reference temperature T0, the focus position shifts to the infinite side, and conversely, when the temperature becomes lower, the focus position shifts to the close side. The TELE end has the largest focus shift with respect to the temperature change. This is greatly affected by the variator lens group 102 being displaced by temperature. As shown in FIG. 4, the temperature becomes high, and the position of the variator lens group 102 is shifted to the TELE side by a temperature change by dx. At the position of TELE and infinity, the RR 104 is moved in by dy more, resulting in a space inconvenience. When the optical magnification is about 40 times, the inclination [dy / dx] is about -30, and considering the mechanical variation, a large space must be provided, which is inconvenient for downsizing. Further, the amount of change in focal length with respect to the change dx of the variator lens group 102 is larger on the TELE side than on the WIDE side. Therefore, the amount of change in the focal length of TELE is larger than the amount of change in the focal length of WIDE, and the optical magnification is larger than that at normal temperature.

  In order to avoid the above problem, the variator lens group 102 may be changed when the current temperature T changes from the reference temperature T0 by a predetermined temperature ΔTth. However, if the variator lens group 102 is merely changed, the amount of focus change caused by the movement of the variator lens group 102 exceeds the depth, and thus the focus cannot be maintained. Therefore, the RR 104 may be driven for a temperature change up to the predetermined temperature ΔTth, and the variator lens group 102 may be driven when the predetermined temperature ΔTth is exceeded. Further, when the variator lens group 102 is driven, by driving the RR 104 together with the cam trajectory at the current temperature T, the pin and the surface can be maintained even while the variator lens group 102 is driven.

  The above movement will be described with reference to the flowchart of FIG.

In S501, the current temperature T is read from the temperature detecting means 114. A temperature change amount ΔT between the current temperature T and the reference temperature T0 is calculated. In S502, a correction amount ΔRR by RR is calculated from ΔT and the position of the variator lens group 102. The correction amount ΔRR by the focus lens group (RR) due to the temperature change amount ΔT varies depending on the position of the variator lens group. Therefore, the variator lens group temperature correction coefficient KRv is set for each variator lens group position, and the calculation is performed by the method of Expression (1).
ΔRR = KRv × ΔT (1)

  The setting method of the variator lens group temperature correction coefficient Kv is not limited to the above method, but the amount of data can be reduced by grouping the positions of the variator lens groups in a certain area so that each area has a variator lens group temperature correction coefficient. It becomes possible to reduce.

  In the above description, only an example of the correction amount ΔRR by the focus lens group (RR) is given, and the present invention is not limited to the above method.

In S503, a correction amount ΔV by the variator lens group is calculated. In the first reference example , calculation is performed by a method of setting the correction amount ΔV by the variator lens group for each predetermined temperature change amount ΔT. An example is as follows.
If 0 ≦ ΔT <5, ΔV = 1
If 5 ≦ ΔT <10, ΔV = 2
If 10 ≦ ΔT <15, ΔV = 3

However, the correction amount ΔV by the variator lens group also sets the temperature correction coefficient Kv in the same manner as the correction amount by the focus lens group (RR),
You may calculate like Formula (2).
ΔV = Kv × ΔT (2)

  Further, like the correction amount ΔRR by the focus lens group (RR), only an example of the correction amount ΔV by the variator lens group is given and is not limited to the above method.

In step S504, a change in the correction amount ΔV by the variator lens group is determined.
If there is no change due to ΔV, focus correction by the focus lens group (RR) is performed in S505. If there is a change due to ΔV, focus correction by the variator lens group is performed in S506. The variator lens group 102 and the RR 104 are driven so as to follow the cam locus corrected by the temperature change amount ΔT. The correction is performed as shown in FIG. 6 by the correction operation. Until the predetermined variator lens group correction amount ΔV changes, focus correction is performed by the focus lens group (RR) (1). When the temperature changes and the variator lens group correction amount ΔV changes, the variator lens group and the focus lens group (RR) are corrected based on the cam data at that temperature (cam at the reference temperature + 5 ° C.). (2). After correction, the variator lens group is positioned at a position closer to WIDE from the TELE end at room temperature, but since the lens barrel is actually extended, the focal length maintains the value at the TELE end at room temperature. can do. Therefore, it becomes possible to maintain the magnification at normal temperature. When the temperature further changes, correction is performed by the focus lens group (RR), and when the variator lens group correction amount ΔV changes, correction is performed along the cam locus at that temperature (3 → 4). Thereafter, when the temperature further changes, the above operation is repeated. When the temperature changes to low temperature, 4 → 3 → 2 → 1 and the reverse operation is performed. When the temperature rises, if the correction by the variator lens group and focus lens group (RR) is applied first as in 1 ', the focal length at the TELE end decreases before the lens barrel expands, and the magnification is maintained. become unable.

  When ΔV changes as described above, correction is performed by the variator lens group 102 and RR104. However, since ΔV is determined by the temperature change amount ΔT, as shown in FIG. Correction using the variator lens group 102 and the RR 104 is also possible.

  At low temperatures, at the TELE / infinity position, the focus lens group (RR) is corrected to the closest side as shown in FIG. 3, and there is sufficient mechanical space, so there is no need to make corrections using the variator lens group. It does not matter as the correction. However, considering that the lens barrel contracts when the temperature is low, it is desirable to perform correction using the variator lens group in order to maintain the magnification.

As in Reference Example 1 , first, correction is performed by the focus lens group (RR), and correction is performed by the variator lens group when a predetermined temperature change amount is reached. In addition, it is possible to provide a focused image while maintaining the magnification.

As mentioned above, although the preferable reference example of this invention was demonstrated, this invention is not limited to these reference examples , A various deformation | transformation and change are possible within the range of the summary.

Example 1
Since it is the same as that of the reference example 1 in a block diagram, description is omitted.

  Generally, when the temperature of the RR lens 104 becomes higher than the reference temperature T0, the focus position shifts to the infinite side, and conversely, when the temperature becomes lower, the focus position shifts to the close side. The TELE end has the largest focus shift with respect to the temperature change. This is greatly affected by the variator lens group 102 being displaced by temperature. As shown in FIG. 4, the temperature becomes high, and the position of the variator lens group 102 is shifted to the TELE side by a temperature change by dx. At the position of TELE and infinity, the RR 104 is moved in by dy more, resulting in a space inconvenience. When the optical magnification is about 40 times, the inclination [dy / dx] is about −30, and considering the mechanical variation, a large space must be provided, which is inconvenient for downsizing. Further, the amount of change in focal length with respect to the change dx of the variator lens group 102 is larger on the TELE side than on the WIDE side. Therefore, the focal length of TELE is larger than that of WIDE, and the optical magnification is larger than that at normal temperature. Further, in a high-power lens, the individual variation of the lens also increases. As the individual variation, there are mainly the spherical variation of the lens, the mounting variation of the photo interrupters 112 and 113, and the like. As described above, in a high magnification lens, the tilt on the TELE side is as large as about −30, and the variation of the photo interrupter of the variator lens group has a great influence. Furthermore, because of the size reduction, there is not enough room on the infinite side, so if the focus lens group (RR) performs temperature correction without being aware of the end on the infinite side, it will hit the end and cannot be corrected, or There is a possibility of stepping out. The term “end” here may be either a mechanical end or an end provided so as not to hit the mechanical end in software. In general, the ends are uniformly provided regardless of the temperature. As shown in FIG. 8, when the correction is performed by the RR 104 and the focus lens group (RR) hits the end, a correction method using the variator lens group and the focus lens group (RR) will be described with reference to the flowchart of FIG. explain.

In step S901, the current temperature T is read from the temperature detecting unit 114. A temperature change amount ΔT between the current temperature T and the reference temperature T0 is calculated. In S902, a correction amount ΔRR by the focus lens group (RR) is calculated from ΔT and the position of the variator lens group 102. The correction amount ΔRR by the focus lens group (RR) due to the temperature change amount ΔT varies depending on the position of the variator lens group. Therefore, the variator lens group temperature correction coefficient KRv is set for each variator lens group position, and the calculation is performed by the method of Expression (1).
ΔRR = KRv × ΔT (1)
The setting method of the variator lens group temperature correction coefficient Kv is not limited to the above method, but the variator lens group positions in a certain area are grouped together so that each area has a variator lens group temperature correction coefficient. It becomes possible to reduce.

  In the above description, only an example of the correction amount ΔRR by the focus lens group (RR) is given, and the present invention is not limited to the above method.

In S903, the corrected focus lens group (RR) position RRcomp is calculated from the current focus lens group (RR) position RRnow and the correction amount ΔR.
RRcomp = RRnow + ΔRR (3)
In step S904, it is determined whether the corrected focus lens group (RR) position RRcomp has hit the end. If not, a correction operation by the focus lens group (RR) is performed in S905 as shown in 1 of FIG. In the case of collision, in S906, the variator lens group 102 and RR104 are driven so as to follow the cam locus corrected by the temperature change amount ΔT as indicated by 2 in FIG. The correction amount of ΔV may be corrected for each minimum unit, or may be calculated according to the temperature change amount ΔT as in Reference Example 1 .

  Also, as an application in AF or MF, the movable range of the focus lens group (RR) is often set based on cam locus data in accordance with the subject distance that can be focused. As an example, when it is possible to focus on an object distance of 2 m to infinity, the result is as shown in FIG. This movable range also needs to be changed according to the temperature change amount ΔT. Since the subject distance that can be focused changes when the movable range hits the end, correction by the variator lens group may be performed when the movable range hits the end.

When the correction is first performed by the focus lens group (RR) as in the first embodiment and the corrected focus lens group (RR) position hits the end, the variator is followed so as to follow the cam corrected by the temperature change amount ΔT. By correcting the lens group 102 and the RR 104, even when the end changes according to the individual difference of the lenses, it is possible to correct without malfunction.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

Schematic explanatory diagram of the optical apparatus of the present invention Cam trajectory for each subject distance High and low temperature cam trajectory relative to the reference temperature Explanatory drawing of change of variator lens group and focus lens group (RR) at TELE end at high temperature Operation flowchart in Reference Example 1 Operation explanatory diagram in Reference Example 1 Operation flowchart in Reference Example 1 Operation explanatory diagram in the first embodiment Operation Flowchart in Embodiment 1 Focus lens group (RR) movable range explanatory diagram according to the cam trajectory Cam locus explanatory diagram

1 Lens barrel 102 Variator lens group 104 Focus lens group (RR)
114 Temperature Detection Unit 2 Image Sensor 3 Focus Lens Group (RR) Drive Unit 4 Variator Lens Group Drive Unit 5 Temperature Detection Unit 6 Camera Signal Processing Unit 7 Focus Lens Group (RR) / Variator Lens Group Calculation Unit 8 Control Information Storage Unit

Claims (4)

A first driving means for driving the variator lens; a second driving means for driving the focus lens; a temperature detecting means; and the focus lens so as to correct a change in the image plane as the variator lens moves. An optical apparatus comprising: control means for controlling movement; and storage means for storing a cam locus indicating the position of the focus lens corresponding to the position of the variator lens,
When the moving position or movable range of the focus lens that is driven to correct a change in the image plane due to the movement of the variator lens is within the infinite end of the focus lens , the control means detects the temperature. The focus lens is driven without driving the variator lens in order to correct the change in the image plane due to the movement of the variator lens based on the correction amount calculated based on the temperature detected by the means,
When the moving position or movable range of the focus lens that is driven to correct the change in the image plane due to the movement of the variator lens is outside the infinite end of the focus lens , the control means detects the temperature. An optical apparatus characterized in that the variator lens and the focus lens are driven on a cam trajectory corrected based on the temperature detected by the means. The optical apparatus according to claim 1, wherein the infinite end is a mechanical end or a soft end. A control method for an optical device for controlling the focus lens to move on a cam trajectory indicating the position of the focus lens corresponding to the position of the variator lens so as to correct the change of the imaging plane accompanying the movement of the variator lens Because
The temperature detected by the temperature detecting means when the moving position or movable range of the focus lens that is driven to correct the change of the imaging plane accompanying the movement of the variator lens is within the infinite end of the focus lens. The focus lens is driven without driving the variator lens in order to correct the change in the image plane due to the movement of the variator lens based on the correction amount calculated based on
When the moving position or movable range of the focus lens that is driven to correct the change in the image plane due to the movement of the variator lens is outside the infinite end of the focus lens , the temperature detecting means detects A control method for an optical apparatus, wherein the variator lens and the focus lens are driven on a cam trajectory corrected based on temperature. The method of controlling an optical apparatus according to claim 3, wherein the infinite end is a mechanical end or a soft end.

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