JP2014190776A - Eccentricity adjustment amount measurement device, eccentricity adjustment amount measurement method and eccentricity adjustment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow use of a simple device to measure an amount of an eccentricity adjustment required for adjusting eccentricity of a lens assembly in short time in an eccentricity adjustment amount measurement device.SOLUTION: An eccentricity adjustment amount system 1 measuring an amount of an eccentricity adjustment of a lens assembly including a movement lens adjusting a focus position is configured to comprise: a chart for focus that has a focus evaluation pattern; an image pickup element 3a that photographs the chart for focus through the lens assembly; a focus position detection part 101 and a focus position detection control part 110 that designate a plurality of preliminarily determined different measurement areas in image data on the chart for focus, calculate an image contrast for each measurement area as a focus evaluation value as moving the movement lens, and detect a focus position of the movement lens by a hill-climbing method in each of the measurement areas; and an eccentricity adjustment amount calculation part 111 that calculates the amount of the eccentricity adjustment of the lens assembly on the basis of the detected focus position for each measurement area.

Description

  The present invention relates to an eccentricity adjustment amount measuring device, an eccentricity adjustment amount measuring method, and an eccentricity adjustment method.

For example, in the manufacture of a lens unit composed of a plurality of lenses, the deviation (eccentricity) of the optical axis of the lens unit with respect to a reference axis determined by the mounting reference of the lens frame component due to manufacturing variations of the lens component and the lens frame component, etc. Arise.
When such an eccentricity occurs, the resolution of one of the peripheral portions of the image taken using the lens unit is reduced, or the image plane rotates around the central portion of the image, thereby causing the image to be centered on the image. It may cause the resolution of both peripherals to decrease.
Conventionally, in order to suppress such blurring of the image due to the eccentricity of the lens unit, for example, the MTF measurement of the lens unit is performed corresponding to each image position, and the eccentricity is adjusted based on the distribution of the MTF. ing.
Moreover, although it is not an eccentricity adjustment amount measuring device, for example, Patent Document 1 uses a lens to be adjusted and an image sensor to photograph a focus adjustment chart and measure a focus position for each divided area of the photographing screen. The lens to be adjusted is moved and decentered based on the difference in focus position between the divided areas at both ends in the left and right direction of the shooting screen and the difference in focus position between the divided areas at both ends in the upper direction of the shooting screen. An eccentricity adjusting method and an eccentricity adjusting device for adjusting are described.

Japanese Patent No. 4860378

However, the conventional techniques as described above have the following problems.
In the eccentricity adjustment by MTF measurement, since an MTF inspection machine is used, the MTF inspection machine is an expensive device, and the measurement time is long. For this reason, when the MTF inspection machine is used to adjust the eccentricity in the manufacturing process in the mass production of lenses, there is a problem that the manufacturing cost of the lens unit increases.
On the other hand, in the technique described in Patent Document 1, an in-focus position is obtained using an autofocus mechanism of a camera without using an MTF inspection machine, and a movement amount for correcting eccentricity is obtained from the in-focus position. For this reason, the eccentricity adjustment can be performed at a lower cost and in a shorter time as compared with the case of using the MTF inspection machine.
However, in Patent Document 1, since it is necessary to obtain in-focus positions in at least eight divided areas, the focus of the lens to be adjusted within a certain range so that the in-focus positions can be detected in all of these divided areas. Defocus shooting is performed by changing the position. For this reason, although it is improved compared with the case of using an MTF inspection machine, there is a strong demand for further reduction in measurement time.
Moreover, since the technique described in Patent Document 1 is adjusted only by moving one of the lenses to be adjusted in a direction orthogonal to the optical axis from the difference in focus position, a problem that good correction accuracy cannot be obtained. There is.

The present invention has been made in view of the above problems, and measures the amount of eccentricity adjustment necessary for the eccentricity adjustment of a lens assembly including a moving lens for adjusting the focus position in a short time using a simple device. An object of the present invention is to provide an eccentricity adjustment amount measuring apparatus and an eccentricity adjustment amount measurement method that can be performed.
Another object of the present invention is to provide an eccentricity adjustment method capable of performing eccentricity adjustment in a short time and easily.

  In order to solve the above problems, an eccentricity adjustment amount measuring apparatus according to a first aspect of the present invention is an eccentricity adjustment amount measuring apparatus that measures an eccentricity adjustment amount of a lens assembly including a moving lens that adjusts a focus position. An in-focus chart having an in-focus evaluation pattern for detecting an in-focus position, an imaging unit for imaging the in-focus chart through the lens assembly, and the in-focus imaged by the imaging unit. In the chart image data, a plurality of different predetermined measurement areas are designated, the image contrast for each measurement area is calculated as a focus evaluation value while moving the moving lens, and hill climbing is performed in each of the measurement areas. Based on the in-focus position detected for each measurement area, the in-focus position detection processing unit for detecting the in-focus position of the moving lens by the method An eccentric adjustment amount calculation section for calculating an eccentricity adjustment amount of the body, the arrangement comprising for.

  In the eccentricity adjustment amount measuring apparatus, the measurement area includes a central area centered on the optical axis of the lens assembly, and peripheral areas respectively positioned at four corners of the imaging region by the lens assembly and the imaging unit. It is possible to become.

  In the eccentricity adjustment amount measuring apparatus, the focusing evaluation pattern of the focusing chart is a lattice pattern in which white lines and black lines are arranged at equal intervals provided at positions corresponding to the measurement areas. It is possible that there is.

  In the eccentricity adjustment amount measuring apparatus, the white line and the black line of the lattice pattern can be extended along a tangent of a concentric circle with respect to the center of the focusing chart.

  In the eccentricity adjustment amount measuring apparatus, the focusing evaluation pattern of the focusing chart can be formed in a wider range than the measurement area.

  The eccentricity adjustment amount measuring apparatus includes a camera to which the lens assembly can be attached, and the camera moves a built-in imaging unit that captures an image of a subject by the lens assembly and the moving lens of the lens assembly. A built-in in-focus position detector that calculates a contrast of an image captured by the in-built image capturing unit as a focus evaluation value, and detects a focus position of the moving lens by a hill-climbing method; and the in-focus position detector A communication connection unit for performing communication, wherein the imaging unit includes the built-in imaging unit, and the focusing position detection processing unit includes the built-in focusing position detection unit and the outside of the camera. And a focus position detection control unit connected to the built-in imaging unit and the built-in focus position detection unit through the communication connection unit so as to be communicable with each other. Above Specify the plurality of different measurement areas for the storage focus position detection unit, and perform operation control of the built-in focus position detection unit to detect the focus position of the moving lens for each measurement area, The in-focus position can be acquired from the built-in in-focus position detector.

  In the eccentricity adjustment amount measuring apparatus, the eccentricity adjustment amount calculation unit calculates a central image plane position at the center of the image and a peripheral image plane position at the periphery of the image from the in-focus position for each measurement area, The eccentricity adjustment amount can be calculated using a deviation between the central image plane position and the peripheral image plane position.

  An eccentricity adjustment amount measuring method according to a second aspect of the present invention is an eccentricity adjustment amount measurement method for measuring an eccentricity adjustment amount of a lens assembly including a moving lens for adjusting a focus position, and for detecting a focus position. A measurement area setting step of setting a plurality of different measurement areas for detecting a focus position from image data of a focus chart having a focus evaluation pattern of the focus, and moving the moving lens while moving the focus through the lens assembly. A focusing chart is imaged, image data corresponding to each of the measurement areas is acquired, an image contrast for each measurement area is calculated as a focus evaluation value, and a hill-climbing method is used for each of the measurement areas. Based on the in-focus position detecting step for detecting the in-focus position and the in-focus position detected for each of the measurement areas, the lens assembly is biased. An eccentric adjustment amount calculation step of calculating an adjustment amount, a method comprising.

  In the eccentricity adjustment amount measurement method, the eccentricity adjustment amount calculation step calculates a central image plane position at the center of the image and a peripheral image plane position at the periphery of the image from the in-focus position for each measurement area, The eccentricity adjustment amount can be calculated using a deviation between the central image plane position and the peripheral image plane position.

  The eccentricity adjustment amount measuring method of the second aspect of the present invention is a method of measuring the eccentricity adjustment amount by the eccentricity adjustment amount measurement method and changing the lens position of the lens assembly based on the eccentricity adjustment amount. .

According to the eccentricity adjustment amount measuring apparatus and the eccentricity adjustment amount measurement method of the present invention, the focus chart is picked up and the focus position is measured by the hill-climbing method in a plurality of different measurement areas on the image of the focus chart. In order to calculate the adjustment amount, the eccentric adjustment amount necessary for the eccentric adjustment of the lens assembly including the moving lens for adjusting the focus position can be measured in a short time using a simple device.
Further, according to the eccentricity adjustment method of the present invention, since the eccentricity adjustment amount measuring method of the present invention is used, there is an effect that the eccentricity adjustment can be easily performed in a short time.

It is a typical perspective view showing a schematic structure of an eccentricity adjustment amount measuring device of an embodiment of the present invention. It is the typical front view which shows an example of the lens assembly of the measuring object of the eccentricity adjustment amount measuring apparatus of embodiment of this invention, and its AA sectional drawing. It is a typical front view of the eccentricity adjustment amount measuring apparatus of the embodiment of the present invention. It is a B view in FIG. It is a functional block diagram which shows the function structure of the eccentricity adjustment amount measuring apparatus of embodiment of this invention. It is the elements on larger scale which show the focusing evaluation pattern of the chart for focusing used for the eccentricity adjustment amount measuring apparatus of embodiment of this invention. It is a flowchart which shows the measurement flow of the eccentricity adjustment amount measuring method of embodiment of this invention. It is a schematic diagram which shows the relationship between the image of the chart for a focusing image | photographed with the camera of embodiment of this invention, and a measurement area. It is a flowchart which shows the flow of the focus position detection process in the eccentricity adjustment amount measuring method of embodiment of this invention. It is a typical graph for demonstrating the hill-climbing method in the eccentricity adjustment amount measuring method of embodiment of this invention. It is a flowchart which shows the processing flow of the correction value calculation process in the eccentricity adjustment amount measuring method of embodiment of this invention. It is a flowchart which shows the measurement flow of the eccentricity adjustment amount measuring method of the modification of embodiment of this invention. It is a flowchart which shows the flow of the focus position detection process in the eccentricity adjustment amount measuring method of the modification of embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, an eccentricity adjustment amount measuring apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a schematic perspective view showing a schematic configuration of an eccentricity adjustment amount measuring apparatus according to an embodiment of the present invention. Fig.2 (a) is a typical front view which shows an example of the lens assembly of the measuring object of the eccentricity adjustment amount measuring apparatus of embodiment of this invention. FIG.2 (b) is AA sectional drawing in Fig.2 (a). FIG. 3 is a schematic front view of the eccentricity adjustment amount measuring apparatus according to the embodiment of the present invention. FIG. 4 is a B view in FIG. FIG. 5 is a functional block diagram showing a functional configuration of the eccentricity adjustment amount measuring apparatus according to the embodiment of the present invention. 6A, 6 </ b> B, and 6 </ b> C are partial enlarged views showing the focus evaluation pattern of the focus chart used in the eccentricity adjustment amount measuring apparatus according to the embodiment of the present invention.

As shown in FIG. 1, an eccentricity adjustment amount measuring system 1 according to this embodiment includes an eccentricity adjustment amount measuring device that measures an eccentricity adjustment amount of a lens unit 10 (lens assembly) that includes a moving lens that adjusts a focus position. It is.
The test lens unit 10 is not particularly limited as long as it is a lens assembly including a plurality of lenses including a moving lens that adjusts the focus position. The subject lens unit 10 may be, for example, an interchangeable lens of a single-lens reflex digital camera or a mirrorless single-lens digital camera, or a lens unit for a compact digital camera. Further, the lens unit 10 may be an interchangeable lens for an analog camera.
Hereinafter, as an example, the case where the lens unit 10 is an interchangeable lens for a digital camera having a three-group configuration as schematically shown in FIGS. 2A and 2B will be described. To do.

In the subject lens unit 10, a first lens L1, a second lens L2, and a third lens L3 (moving lens) are arranged in this order from the object side to the image side.
FIGS. 2A and 2B are schematic diagrams, and the shape of each lens is shown as a biconvex single lens. However, the configuration of the first lens L1, the second lens L2, and the third lens L3 is illustrated. The shape is not limited to a biconvex single lens.
As the first lens L1, the second lens L2, and the third lens L3, a lens or a lens group having an appropriate shape and refractive power can be adopted.
Further, the group configuration of the lens unit 10 to be measured is not limited to such a three-group configuration, and an appropriate group configuration of two or more groups can be adopted.

The first lens L1 is a lens or a lens group constituting a fixed group, and is held by the adjustment lens frame 12.
The second lens L <b> 2 is a lens or a lens group constituting a fixed group, and is held by the fixed lens frame 11.
The third lens L3 is a lens or a lens group constituting a moving group, and is held by the moving lens frame 13.

The fixed lens frame 11 has an adjustment lens frame 12 on the first end 11g which is the object side (the left side in FIG. 2B) of the lens unit 10 to be tested, and a second end opposite to the first end 11g. The movable lens frame 13 is a cylindrical member attached to the inner periphery of the portion 11h.
In the inner peripheral portion between the first end portion 11 g and the second end portion 11 h of the fixed lens frame 11, the second lens L <b> 2 is located at a position coaxial with the optical axis O that is the reference axis line of the lens unit 10 to be tested. A lens receiving portion 11a for fixing and holding is provided.
The method for fixing the second lens L2 to the lens receiving portion 11a is not particularly limited. For example, direct fixation by adhesion or caulking, fixation by a pressing ring bonded to the fixed lens frame 11, or fixing by a pressing ring that can be screwed to the fixed lens frame 11 can be employed.

An insertion opening 11 c for inserting the image side end of the adjustment lens frame 12 is formed in the first end 11 g of the fixed lens frame 11.
A female threaded portion 11e (FIG. 2) to which a fixing screw 15 for fixing the adjustment lens frame 12 to the fixed lens frame 11 is screwed onto a tip end surface 11d which is an axial end surface of the first end portion 11g of the fixed lens frame 11. (See (b)) is provided on the circumference of the radius R at a position that divides the circumferential direction into three equal parts.

At the second end portion 11h of the fixed lens frame 11, a mounting portion 11b that can be attached to and detached from a body mount 3c of the camera body 3 to be described later is provided. Although not shown, the attachment portion 11b is provided with an electrical contact that is electrically connected to a camera body 3 described later when attached to the body mount 3c.
The attachment portion 11b constitutes a reference for attachment of the lens unit 10 to be tested, and the central axis of the attachment portion 11b coincides with the optical axis O.
A movable holding portion 11 f that holds the movable lens frame 13 movably along the optical axis O is provided on the inner peripheral portion of the second end portion 11 h of the fixed lens frame 11.
As the configuration of the movement holding unit 11f, all known configurations of the interchangeable lens for performing automatic focus position adjustment (AF) can be adopted.
For example, it is possible to adopt a configuration in which a movement guide portion such as a cam groove (not shown) is provided and a locking projection (not shown) provided on the outer peripheral portion of the moving lens frame 13 is movably locked.

The fixed lens frame 11 is provided with a lens driving unit 11i that is communicably connected to a camera control unit 3d of the camera body 3 to be described later.
The lens drive unit 11i adjusts the focus position of the test lens unit 10 mounted on the body mount 3c based on a control signal from a camera control unit 3d described later when the test lens unit 10 is mounted. The moving lens frame 13 is moved in a direction along the optical axis O of the lens unit 10 to be tested.
As a specific configuration of the lens driving unit 11i, for example, a stepping motor connected to the moving lens frame 13 through an appropriate transmission mechanism can be employed.
The lens driving unit 11i has, for example, a position detection unit such as an encoder (not shown). For this reason, the lens driving unit 11i can detect the movement position of the moving lens frame 13, and thus the third lens L3, by the position detection unit, and transmit information on the movement position to the camera control unit 3d described later.

The adjustment lens frame 12 is a substantially cylindrical member that fixes and holds the first lens L1.
The adjustment lens frame 12 is provided with a lens receiving portion 12a for fixing the first lens L1 at the first end portion 12g on the object side of the lens unit 10 to be tested.
The method for fixing the first lens L1 to the lens receiving portion 12a is not particularly limited. For example, direct fixing by bonding or caulking, fixing by a pressing ring bonded to the adjustment lens frame 12, or fixing by a pressing ring that can be screwed to the adjustment lens frame 12 can be employed.
A cylindrical insertion portion 12 b having an outer diameter smaller than the insertion opening 11 c of the fixed lens frame 11 is formed on the outer peripheral portion of the second end portion 12 h opposite to the first end portion 12 g of the adjustment lens frame 12. ing. The outer diameter of the insertion portion 12b is set to a size that does not come into contact with the insertion opening 11c even if the adjustment lens frame 12 is tilted by eccentricity adjustment described later.

On the side surface on the outer peripheral side between the first end portion 12g and the second end portion 12h of the adjustment lens frame 12, there are projecting piece-like flanges projecting sideways from the side surface at three locations that divide the circumferential direction into three equal parts. Parts 12A, 12B, and 12C are provided.
Through the flange portions 12A, 12B, and 12C, a fixing screw 15 is inserted in the thickness direction, and the adjustment lens frame 12 is positioned in the radial direction and the circumferential direction with respect to the optical axis O at the screwing position of the fixing screw 15. A hole 12c (see FIG. 2B) is provided.
The through hole 12 c is formed at a position that divides the circumference of the radius R into three equal parts with the central axis of the adjustment lens frame 12 as the center. As a result, when the insertion portion 12b is inserted into the insertion opening 11c from the first end side of the fixed lens frame 11 and assembled, the insertion portion 12b can be opposed to each female screw portion 11e of the fixed lens frame 11.

In the test lens unit 10, the adjustment lens frame 12 has an insertion portion 12 b inserted into the insertion opening 11 c of the fixed lens frame 11, and between the flange portions 12 A, 12 B, 12 C and the distal end surface 11 d of the fixed lens frame 11. These screws are fastened to the fixed lens frame 11 by fixing screws 15 with the spacers 14A, 14B, and 14C interposed therebetween.
The spacers 14A, 14B, and 14C are plate members for adjusting the lens interval between the first lens L1 and the second lens L2, and in the present embodiment, the spacers 14A, 14B, and 14C have an annular plate shape having an appropriate thickness. .
The spacers 14A, 14B, and 14C are prepared in advance with a plurality of thicknesses corresponding to the eccentricity adjustment amount described later, and the spacers 14A, 14B, and 14C are selected according to the lens position correction value described later. Can be installed.
In this embodiment, when the range of the eccentricity adjustment amount is ± t, the spacers 14A, 14B, and 14C to be attached before the eccentricity adjustment are attached with a thickness of t.
For this reason, when the eccentricity adjustment amount becomes −t, the spacers 14A, 14B, and 14C at the position where the eccentricity adjustment amount is −t are not attached to the lens unit 10 after the eccentricity adjustment.

  The shape of the adjustment lens frame 12 and the fixed lens frame 11 is such that when the spacers 14A, 14B, and 14C having such a thickness t are mounted, the lens interval between the first lens L1 and the second lens L2 is the designed lens interval. Designed to be However, in actuality, since the adjustment lens frame 12, the fixed lens frame 11, the first lens L1, and the second lens L2 have manufacturing errors and assembly errors, the spacers 14A, 14B, and 14C have a thickness t. However, eccentricity may occur.

The moving lens frame 13 is a substantially cylindrical member that holds the third lens L <b> 3 so as to be movable in the axial direction with respect to the fixed lens frame 11.
A lens receiving portion 13 a for fixing and holding the third lens L <b> 3 is provided on the inner peripheral portion of the moving lens frame 13.
The method for fixing the third lens L3 to the lens receiving portion 13a is not particularly limited. For example, direct fixation by adhesion or caulking, fixation by a pressing ring bonded to the moving lens frame 13, or fixing by a pressing ring that can be screwed to the moving lens frame 13 can be employed.

The outer peripheral portion of the moving lens frame 13 is movably fitted inside the movement holding portion 11f of the fixed lens frame 11, and a locking projection (not shown) is provided on the movement guide portion (not shown) of the movement holding portion 11f, for example. It is locked through.
The moving lens frame 13 is connected to the lens driving unit 11i, and receives a driving force from the lens driving unit 11i that has received a control signal from the camera body 3 side when mounted on a body mount 3c of the camera body 3 to be described later. Be able to.

  As shown in FIGS. 1, 3, and 4, the schematic configuration of the eccentricity adjustment amount measuring system 1 for measuring the eccentricity adjustment amount of the lens unit 10 having such a configuration is as follows. 2, the illumination part 4, and the measurement control apparatus 5 are provided.

The camera body 3 is detachably mounted with the test lens unit 10, and the focus position is adjusted by moving the position of the moving lens frame 13 of the test lens unit 10 during mounting, and the camera body 3 passes through the test lens unit 10. It is a device portion that performs imaging.
The camera body 3 may employ a dedicated device that satisfies such requirements, but in the present embodiment, the test lens unit 10 can be attached as an interchangeable lens, and various subjects can be photographed. A commercially available or scheduled camera body is used by being placed on the gantry 8 (see FIG. 3) of the eccentricity adjustment amount measuring system 1.
The camera body 3 can be replaced with another camera body 3 that matches the type of the lens unit 10 to be measured when the type of the lens unit 10 to be measured is changed.

  The schematic configuration of the camera body 3 includes a body mount 3c, an image sensor 3a (built-in image capturing unit, image capturing unit), a camera control unit 3d, and a communication connection unit 3e.

  The body mount 3c is detachably mounted in a state where the optical axis O of the lens unit 10 to be tested is positioned at the center of the image pickup surface of the image pickup element 3a, and a known appropriate mount method can be adopted.

  The image pickup device 3a picks up an image of a subject through the lens unit 10 mounted on the body mount 3c. For example, a photoelectric conversion device such as a CCD or a CMOS device can be adopted.

The camera control unit 3d controls the overall operation of the camera body 3 (not shown) in response to an operation input from an operation unit (not shown) provided in the camera body 3 or a control signal input from an external device. is there.
The camera control unit 3d is electrically connected to the image sensor 3a and the communication connection unit 3e. The camera control unit 3d is also communicably connected to the lens driving unit 11i via the body mount 3c and the attachment unit 11b of the fixed lens frame 11 when the lens unit 10 is mounted.
The control performed by the camera control unit 3d can be well-known control as a digital camera product necessary for photographing a subject.
Examples of the control performed by the camera control unit 3d include, for example, an imaging operation control by the imaging device 3a, a focus position adjustment control performed by moving the moving lens frame 13 via the lens driving unit 11i, and an imaging device. An AF operation control for performing AF by the so-called hill-climbing method can be given by using the contrast of the image captured by 3a as a focus evaluation value.

As shown in FIG. 5, the main functional configuration of the camera control unit 3d includes an image processing unit 100, a focus position detection unit 101, a storage unit 102, and an external command analysis unit 103.
The image processing unit 100 acquires image data photoelectrically converted by the image sensor 3a, and performs image processing such as white balance control, noise removal processing, and gradation processing as necessary.
The image data processed by the image processing unit 100 can be stored in, for example, the storage unit 102 or displayed on a liquid crystal panel, which is a display unit of the camera body 3 (not shown).

The in-focus position detection unit 101 calculates the contrast of the image captured by the image sensor 3a as the in-focus evaluation value while moving the third lens L3, which is the moving lens of the lens unit 10 to be tested. The in-focus position of the three lenses L3 is detected.
The in-focus position detection unit 101 is communicably connected to the lens driving unit 11i via the body mount 3c and the attachment unit 11b, and acquires information on the amount of movement of the moving lens frame 13 by the lens driving unit 11i. The moving position of the third lens L3 is detected.
The focus position detection unit 101 is used for AF in the normal shooting mode of the camera body 3. That is, if it is detected that the maximum value of the focus evaluation value has been exceeded, control is performed to return the position of the third lens L3 to the focus position at which the maximum value of the focus evaluation value is reached, and the focus position is set to the focus position. Adjust.
However, in the present embodiment, the in-focus position detection unit 101 only needs to detect the in-focus position with respect to the in-focus chart 2 in the operation based on the control signal of the measurement control device 5 described later. The function of moving the third lens L3 to the focused position is not essential.

The storage unit 102 stores image data output from the image processing unit 100.
The external command analysis unit 103 analyzes a signal received from the measurement control device 5 via a communication connection unit 3e described later, and determines whether the analyzed signal is a control signal such as a command or a data signal. Is.
When the received signal is a control signal, the external command analysis unit 103 sends a control signal necessary for the control operation to the image processing unit 100 or the focus position detection unit 101.
If the received signal is a data signal, the external command analysis unit 103 transfers the data signal to the in-focus position detection unit 101 as a data signal.

  The device configuration of the camera control unit 3d is a computer including a CPU, a memory, an input / output interface, a removable storage device, and the like. Thereby, the control functions as described above are realized by executing appropriate control programs corresponding to the respective control functions.

The communication connection unit 3e is an external connection terminal that performs communication with an external device via an input / output interface in the camera control unit 3d.
In the present embodiment, a control signal is received from a measurement control device 5 to be described later, which is an external device for the camera body 3, and, for example, via image data acquired by the image sensor 3a, the body mount 3c, and the attachment portion 11b. Thus, data acquired from the lens driving unit 11i, data obtained by performing arithmetic processing on these data, and the like can be transmitted to an external device via the camera control unit 3d.
The communication method of the communication connection part 3e is not specifically limited, A well-known communication method can be employ | adopted suitably. For example, a serial communication method or a parallel communication method may be used. Further, a wired communication system or a wireless communication system may be used.
In the present embodiment, as an example, a USB (Universal Serial Bus) terminal is employed.

In such a configuration of the camera body 3, the imaging device 3 a constitutes a built-in imaging unit that captures an image of the subject by the lens unit 10 to be tested.
Further, the in-focus position detecting unit 101 calculates the contrast of the image captured by the built-in image capturing unit as the in-focus evaluation value while moving the third lens L3 that is the moving lens of the lens unit 10 to be tested. Constitutes a built-in in-focus position detector that detects the in-focus position of the third lens L3.
The communication connection unit 3e constitutes a communication connection unit for communicating with the built-in in-focus position detection unit.

  As shown in FIGS. 3 and 4, the focusing chart 2 is photographed by the camera body 3 to which the lens unit 10 is mounted, and is used to detect the in-focus positions at a plurality of positions in different photographing areas. It is a chart which has several focus evaluation pattern part 2A, 2B, 2C, 2D, 2E (focus evaluation pattern). Hereinafter, for the sake of simplicity, the focus evaluation pattern portions 2A, 2B, 2C, 2D, and 2E may be abbreviated as the focus evaluation pattern portions 2A to 2E.

In this embodiment, the focusing chart 2 is separated from the camera body 3 disposed on the gantry 8 with the optical axis O of the lens unit 10 to be horizontal, by an imaging distance d (see FIG. 3). It is a rectangular plate-like member erected at the front position.
The size of the focusing chart 2 is set so as to cover the entire photographing range determined by the focal length of the lens unit 10 to be examined, the photographing distance d, and the size of the effective imaging range of the image sensor 3a.
In this embodiment, the camera body 3 is arranged such that the long side of the shooting range is aligned in the horizontal direction and the short side of the shooting range is aligned in the vertical direction (Y-axis direction in FIG. 4). In accordance with this, the focusing chart 2 is also arranged such that the long side is aligned in the horizontal direction (X-axis direction in FIG. 4) and the short side is aligned in the vertical direction.

The pattern shape of the focus evaluation pattern portions 2A to 2E is not particularly limited as long as it can accurately detect a change in contrast of an image acquired by the image sensor 3a. In this embodiment, as an example, as shown in FIGS. 6A, 6 </ b> _B, and 6 </ _b > _C , a lattice pattern in which white lines _LW and black lines LB are arranged in a rectangular region at equal intervals. Is adopted.
The size of the focus evaluation pattern portions 2A to 2E is not particularly limited as long as it can accurately detect the change in contrast of the image acquired by the image sensor 3a.

As shown in FIG. 4, the focus evaluation pattern portion 2C is formed in a rectangular area centered with the point P0 at the center position of the focus chart 2 located on the extension line of the optical axis O of the lens unit 10 to be tested. It is a pattern.
In the present embodiment, as shown in FIG. 6 (a), and black line L _B of the line width d _B, Mashimashi white line L _W and are extended in the vertical directions of the line width d _W, alternately in the horizontal direction An arranged lattice pattern is adopted. The line widths d _B and d _W are preferably equal to each other.

As shown in FIG. 4, the focus evaluation pattern portion 2A (2D) is a point P1 (P3) at the peripheral position of the corner of the photographing range on the right (left) diagonally upper (lower) side with respect to the center position P0. ) At the center of the rectangular area.
In the present embodiment, as shown in FIG. 6 (b), consists of grid pattern similar to the black line L _B and evaluation pattern portion 2C focus and white lines L _W are alternately arranged, extends in the line The only difference is that the direction is perpendicular to the straight line 2a (2d) passing through the points P0 and P1 (P3).

As shown in FIG. 4, the focus evaluation pattern portion 2B (2E) is a point P2 (P4) at a peripheral position at the corner of the shooting range that is on the left (right) diagonally upper (lower) side with respect to the center position P0. ) At the center of the rectangular area.
In the present embodiment, as shown in FIG. 6 (c), consists of grid pattern similar to the black line L _B and evaluation pattern portion 2C focus and white lines L _W are alternately arranged, extends in the line The only difference is that the direction is perpendicular to the straight line 2b (2e) passing through the points P0 and P2 (P4).

With this configuration, in the present embodiment, as shown in FIG. 4, when the XY coordinate system having the point P0 as the origin is taken, the focus evaluation pattern portions 2A, 2B, 2D, and 2E are respectively in the XY coordinate system. Arranged in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant.
The in-focus evaluation pattern portions 2A, 2B, 2D, and 2E may be arranged at the same distance from each other in the present embodiment although the distance from the point P0 may be different from each other. Further, the focus evaluation pattern portion 2A, 2B, 2D, the extending direction of the black line L _B and the white lines L _W in 2E is matched in the tangential direction of the concentric circle centered on the point P0.

  As shown in FIGS. 1 and 3, the illumination unit 4 irradiates the focusing chart 2 with white illumination light. In the example shown in the figure, a pair of linear light sources are disposed between the focusing chart 2 and the camera body 3 so as to extend in the vertical direction with the optical axis O of the lens unit 10 to be tested interposed therebetween. The shape and arrangement of the light source are not limited as long as the illumination light can be evenly applied to the focus evaluation pattern portions 2A, 2B, 2C, 2D, and 2E.

  As shown in FIG. 6, the functional configuration of the measurement control device 5 includes an in-focus position detection control unit 110, an eccentricity adjustment amount calculation unit 111, a lens position correction value calculation unit 112, and a display control unit 113.

The focus position detection control unit 110 designates a plurality of different measurement areas for the focus position detection unit 101 and detects the focus position of the third lens L3 for each measurement area. 101 is controlled to acquire each in-focus position from the in-focus position detector 101. For this reason, the focus position detection control unit 110 is connected to the focus position detection unit 101 via the communication connection unit 3e of the camera body 3 so as to be communicable.
Further, the focus position detection control unit 110 is connected to an operation unit 7 including a keyboard 7a and a mouse 7b (see FIG. 1) connected to the measurement control device 5, and through these operation units 7, A measurement area can be designated by an operation input by a measurer.

  In the eccentricity adjustment amount measurement system 1, the focus position detection unit 101 and the focus position detection control unit 110 of the measurement control device 5 are determined in advance in the image data of the focus chart 2 imaged by the image sensor 3a. A plurality of different measurement areas are designated, and the image contrast for each of these measurement areas is calculated as a focus evaluation value while moving the third lens L3. In each of these measurement areas, the third lens L3 is measured by a hill-climbing method. An in-focus position detection processing unit for detecting the in-focus position is configured.

The decentering adjustment amount calculation unit 111 calculates the decentering adjustment amount of the lens unit 10 to be detected based on the in-focus position detected for each measurement area, and is connected to the in-focus position detection control unit 110 so as to be communicable. Has been.
The eccentricity adjustment amount calculation unit 111 is communicably connected to a display control unit 113 described later, and can send the eccentricity adjustment amount calculated by the eccentricity adjustment amount calculation unit 111 to the display control unit 113.

The lens position correction value calculation unit 112 calculates a lens position correction value for correcting the decentration adjustment amount of the lens unit 10 to be measured, which is calculated by the decentration adjustment amount calculation unit 111.
In the present embodiment, by changing the thicknesses of the spacers 14A, 14B, and 14C in the range of 0 to 2t, the position and orientation of the adjustment lens frame 12 with respect to the fixed lens frame 11, and thus with respect to the optical axis O and the second lens L2. The position and posture of the first lens L1 can be changed. Therefore, the lens position correction value is calculated as the thickness of the spacers 14A, 14B, and 14C.
The lens position correction value calculation unit 112 is communicably connected to a display control unit 113 described later, and can transmit the lens position correction value calculated by the lens position correction value calculation unit 112 to the display control unit 113.

  Detailed control operations and calculations performed by the in-focus position detection control unit 110, the eccentricity adjustment amount calculation unit 111, and the lens position correction value calculation unit 112 will be described in the operation description to be described later.

The display control unit 113 sends data sent from the camera body 3 via the communication connection unit 5e described later, data on the eccentricity adjustment amount sent from the eccentricity adjustment amount calculation unit 111, and lens position correction value calculation unit 112. The lens position correction value data is converted into, for example, an appropriate video signal and displayed on the display unit 6 including, for example, a liquid crystal display connected to the measurement control device 5.
Each data to be displayed on the display unit 6 can be displayed by character information such as numerical data, or converted into image information such as a graph and displayed.

The device configuration of the measurement control device 5 is a computer including a CPU, a memory, an input / output interface, an external storage device, and the like. Thus, the control function or calculation function as described above is realized by executing an appropriate control program and calculation program corresponding to each control function and calculation function.
Further, the measurement control device 5 is provided with a communication connection unit 5e that employs the same communication method as the communication connection unit 3e of the camera body 3.
The communication connection unit 5 e is an external connection terminal that performs communication with an external device via an input / output interface in the measurement control device 5.
In the present embodiment, the communication connection unit 5 e is connected to the communication connection unit 3 e of the camera body 3 via the USB connection cable 9.
Therefore, the measurement control device 5 can transmit and receive control signals and data to and from the camera body 3 that is an external device.

Next, an eccentricity adjustment amount measuring method of this embodiment using such an eccentricity adjustment amount measurement system 1 and an eccentricity adjustment method using the same will be described.
FIG. 7 is a flowchart showing a measurement flow of the eccentricity adjustment amount measuring method according to the embodiment of the present invention. FIG. 8 is a schematic diagram showing the relationship between the image of the focusing chart imaged by the camera of the embodiment of the present invention and the measurement area. FIG. 9 is a flowchart showing a flow of focus position detection processing in the eccentricity adjustment amount measuring method according to the embodiment of the present invention. FIG. 10 is a schematic graph for explaining the hill-climbing method in the eccentricity adjustment amount measuring method of the embodiment of the present invention. FIG. 11 is a flowchart showing a processing flow of correction value calculation processing in the eccentricity adjustment amount measuring method according to the embodiment of the present invention.

  In order to measure the eccentricity adjustment amount of the lens unit 10 to be measured using the eccentricity adjustment amount measurement system 1, steps S1 to S10 are executed according to the flow shown in FIG.

Step S <b> 1 is a step in which the measurer sets the test lens unit 10 in the eccentricity adjustment amount measurement system 1.
The test lens unit 10 used in this step is assembled by sandwiching the spacers 14A, 14B, and 14C having a thickness t between the fixed lens frame 11 and the adjustment lens frame 12.
Then, as shown in FIG. 3, the lens unit 10 to be tested is attached to the body mount 3 c of the camera body 3 on the gantry 8 disposed at a position away from the focusing chart 2 by the photographing distance d. Here, the shooting distance d is set to a value determined in advance according to the focal length of the lens unit 10 so that substantially the entire focusing chart 2 falls within the shooting range.

Here, in the following description, an xyz coordinate system used for calculation and direction reference will be described.
As shown in FIGS. 2A and 2B, the z axis is a coordinate axis aligned with the optical axis O of the lens unit 10 to be tested, the object side of the lens unit 10 being the negative direction, and the image side being the positive direction. .
The x-axis is a coordinate axis extending in the horizontal direction intersecting the z-axis. When the lens unit 10 is viewed from the object side to the image side, the left side is the positive direction and the right side is the negative direction. is there.
The y-axis is a coordinate axis extending in the vertical direction intersecting the z-axis, with the vertical upper side being the positive direction and the vertical lower side being the negative direction.
The origin of the xyz coordinate system can be appropriately determined according to the necessity of calculation.

In the lens unit 10 of this embodiment, the center of the fixing position of the spacer 14C sandwiched between the flange portion 12C and the tip surface 11d is x with respect to such an xyz coordinate system as shown in FIG. It is arranged in a direction located on the axis.
For this reason, the center of the fixing position of the spacer 14A sandwiched between the flange portion 12A and the distal end surface 11d is a position obtained by rotating the center of the spacer 14C by 120 ° in the clockwise direction around the z axis. Therefore, the straight line intersecting the center of the spacer 14A and the z-axis is inclined by θ _A = 30 (°) with respect to the y-axis.
The center of the fixed position of the spacer 14B sandwiched between the flange portion 12B and the distal end surface 11d is a position obtained by rotating the center of the spacer 14C by 120 ° counterclockwise in the figure around the z axis. Therefore, the straight line intersecting the center of the spacer 14B and the z-axis is inclined by θ _B = 30 (°) with respect to the y-axis.

The lens unit 10 thus arranged has its optical axis O directed to the point P0 at the center of the focusing chart 2 and includes a focusing evaluation pattern portion 2A to 2E. An almost entire area of 2 falls within the shooting range.
Thus, step S1 is completed.

Next, in step S2, initial setting of the eccentricity adjustment amount measurement is performed.
In this step, information necessary for measuring the eccentricity adjustment amount is set in the measurement control device 5.
Information necessary for the measurement of the eccentricity adjustment amount includes measurement areas A1, A2, A0, A3, and A4 for calculating the focus positions in the focus evaluation pattern portions 2A to 2E of the focus chart 2 (FIG. 8). Position information) and information on the optical design of the lens unit 10 to be examined.
Such information can be input to the measurement control device 5 by the measurer through the operation unit 7. In addition, a database of information necessary for various test lens units 10 is stored in advance in the measurement control device 5 so that the measurer can select initial setting information according to the type of the test lens unit 10. It is also possible.
Hereinafter, as an example, a case where a measurer inputs to the measurement control device 5 through the operation unit 7 will be described.

When the subject chart unit 10 is set on the camera body 3 and the focusing chart 2 is imaged, an image as shown in FIG. 8 is captured. That is, the lattice pattern images I _2A , I _2B , I _2C corresponding to the focus evaluation pattern portions 2A, 2B, 2C, 2D, 2E around the positions p1, p2, p0, p3, p4 on the image sensor 3a. , I _2D , I _2E are imaged.
The measurement areas A1, A2, A0, A3, and A4 are set so as to be inside these images I _2A , I _2B , I _2C , I _2D , and I _2E even when the installation error of the camera body 3 is taken into consideration. .
That is, the measurement areas A1, A2, A0, A3, and A4 are on the image sensor 3a corresponding to the points P1, P2, P0, P3, and P4 on the focusing chart 2 when there is no installation error of the camera body 3. This is a rectangular area centered at points p1, p2, p0, p3, and p4.
For this reason, the measurement area A0 constitutes a central area with the optical axis O as the center, and the measurement areas A1 to A4 constitute peripheral areas located at the four corners of the imaging region.

Further, the measurement areas A1, A2, A0, A3, and A4 are set as rectangular areas that are smaller than the sizes of the images I _2A , I _2B , I _2C , I _2D , and I _2E in consideration of installation errors of the camera body 3. To do.
As a setting method, for example, the position coordinates of the pixel positions that are the four corners of the measurement areas A1, A2, A0, A3, and A4 are set.
However, if the installation error of camera body 3 is negligible, measurement area A1, A2, A0, A3, A4, the image _{I 2A, I 2B, I 2C} , I 2D, I 2E is on the image sensor 3a which occupies You may make it correspond with an area | region.

When the measurer inputs the position information of the measurement areas A1, A2, A0, A3, and A4 from the operation unit 7, the focus position detection control unit 110 transmits the position information to the camera body connected by the USB connection cable 9. 3 to send.
In the camera body 3, the received signal is analyzed by the external command analysis unit 103, and is sent to the in-focus position detection unit 101 as position information of the measurement areas A1, A2, A0, A3, and A4.
As a result, the focus position detection unit 101 can execute the focus position detection operation for each of the measurement areas A1, A2, A0, A3, and A4.

As information on the optical design of the lens unit 10 to be measured necessary for the eccentricity adjustment amount measurement, for example, design image plane positions I0 to I4 at image height positions corresponding to the points P0 to P4 of the focusing chart 2 The movement amount conversion coefficient k, the correction coefficients W _x and W _y , the inclination correction coefficients x _c and y _c, and the peripheral image plane deviation amount correction coefficient z _c can be mentioned.
The design image plane positions I0 to I4 will be described below using an example in which the aberration correction is designed so that the field curvature aberration of the lens unit 10 is negligible for the sake of simplicity. In this case, since the designed image plane positions I0 to I4 are parallel to the xy plane orthogonal to the optical axis O, each is set to 0 by appropriately setting the coordinate origin along the z axis. Can do.
Further, the movement amount conversion coefficient k, the correction coefficients W _x and W _y , the inclination correction coefficients x _c and y _c , and the peripheral image plane deviation amount correction coefficient z _c will be described later.

  When the initial setting is completed, the measurer inputs the start of measurement through the operation unit 7, whereby Step S2 is completed, and the process proceeds to Step S3.

  Note that it is not essential for the measurer to perform this step. For example, when the test lens unit 10 to be measured is determined to be one type, such as when the test lens unit 10 is mass-produced, the initial setting information is stored in the measurement control device 5 in advance, and the operation unit 7 It is also possible to automatically load an initial set value when an operation input for starting measurement is performed.

  Step S2 constitutes a measurement area setting step for setting a plurality of different measurement areas A0 to A4 for detecting the focus position from the image data of the focus chart 2.

  Step S3 is a step of setting the eccentricity adjustment amount measurement counter i in the in-focus position detection control unit 110 of the measurement control device 5 to i = 0.

Next, step S4 is performed. This step is a step of setting the measurement area of the focus position to the measurement area Ai.
Specifically, a command for setting the measurement area to the measurement area Ai and detecting the in-focus position from the in-focus position detection control unit 110 of the measurement control device 5 to the camera body 3 together with the value of the counter i. Sent out.

Next, in step S5, focus position detection processing is performed.
This step is performed by executing steps S11 to S13 according to the flow shown in FIG.

Step S11 is a step in which the focus position of the lens unit 10 to be tested is set to infinity.
In this step, a process start control signal is sent to the focus position detection unit 101 by the external command analysis unit 103 that has received a signal from the focus position detection control unit 110.
Thereby, the focus position detection unit 101 controls the lens driving unit 11i to move the moving lens frame 13 to which the third lens L3 is fixed so that the focus position of the lens unit 10 to be inspected is at infinity. Send a signal.
The lens driving unit 11i moves the moving lens frame 13 and sets the focus position to infinity. At this time, the lens driving unit 11i sets the moving position of the moving lens frame 13, that is, the current position of the moving position of the third lens L3, as a movement start origin in a position detection unit (not shown). Hereinafter, unless there is a possibility of misunderstanding, the moving position and moving amount of the moving lens frame 13 are simply referred to as the moving position and moving amount of the third lens L3.
Above, step S11 is complete | finished.

Next, step S12 is performed. This step is a step of starting the focus position movement toward the closest position.
That is, the focus position detection unit 101 sends a control signal for moving the third lens L3 by a unit movement amount so that the focus position of the lens unit 10 to be moved moves toward the closest position to the lens driving unit 11i. . Here, the unit movement amount can be appropriately set according to the focusing accuracy. For example, when a stepping motor is used as the lens driving unit 11i, an integral multiple of the movement amount of the unit step can be set as the unit movement amount.
As a result, the third lens L3 moves and the focus position moves toward the closest side. The movement amount of the third lens L3 is sequentially measured by the position detection unit of the lens driving unit 11i. The amount of movement of the third lens L3 is sent to the focus position detection unit 101.
The movement amount of the third lens L3 can be converted into the movement amount of the focus position based on the optical design value of the lens unit 10 to be tested.

When the third lens L3 starts moving in this way, step S13 is performed. This step is a step of searching for the focus position by the hill-climbing method and obtaining the focus position Gi of the measurement area Ai.
The focus position detection unit 101 acquires the image data of the measurement area Ai from the image data captured by the image sensor 3a from the image processing unit 100, and obtains a focus evaluation value from the contrast (brightness / darkness difference) of the image. calculate. As the calculation method of the focus evaluation value, the same method as the calculation method of the focus evaluation value in the AF operation when the camera body 3 captures another subject can be employed.
When this step is executed for the first time, since i = 0, the focus evaluation value of the measurement area A0 at the current position is calculated.
Such a focus evaluation value is calculated every time the third lens L3 moves by a unit movement amount. This focus evaluation value takes a small value when the contrast is low, and increases as the contrast increases. When the focus position coincides with the in-focus chart 2, the contrast becomes maximum and the in-focus evaluation value also takes the maximum value.
Therefore, for example, as shown in FIG. 10, the focus evaluation value gradually increases from a small value indicating that the contrast is low as the focus position moves from the infinity side to the close side, and corresponds to the position of the subject. After reaching the peak value, it shows a change in the mountain shape, such as decreasing.

The focus position detection unit 101 checks the change in the focus evaluation value, and stops the movement by the lens driving unit 11i when a peak is detected. Then, with reference to the information on the movement position of the third lens L3 sent from the lens driving unit 11i, the movement position of the third lens L3 where the peak is detected is set as the focusing position Gi.
Above, step S13 is complete | finished. Thereby, step S5 is completed.

In the present embodiment, since the in-focus position Gi is detected by the hill-climbing method in this way, the movement of the third lens L3 is stopped as soon as a peak is detected, and quick measurement as a whole can be performed.
In this embodiment, the focus movement position is moved to infinity in step S11 and the focus movement position is moved to the closest position in step S12. However, in step S11, the focus movement position is changed to the closest position, and the process proceeds to step S12. The focus may be moved toward the infinity position.

Next, step S6 is performed as shown in FIG. This step is a step of storing the in-focus position Gi.
When the in-focus position Gi is obtained, the in-focus position detection unit 101 notifies the measurement control device 5 that the in-focus position detection processing has ended, and transmits the detected in-focus position Gi to the measurement control device 5. .
The focus position detection control unit 110 stores the focus position Gi transmitted from the camera body 3 in the memory.
This is the end of step S6.

Next, in step S7, the focus position detection control unit 110 updates the counter i as i = i + 1.
Next, in step S8, the in-focus position detection control unit 110 determines whether the counter i exceeds 4.
If the counter i exceeds 4, the process proceeds to step S9.
When the counter i is 4 or less, the process proceeds to step S4, and the above steps S4 to S8 are repeated.

In this way, every time the counter i is updated, the in-focus position Gi at the position corresponding to the point Pi of the in-focus chart 2 is detected and stored in the memory of the measurement control device 5.
The in-focus position Gi (i = 0, 1,..., 4) takes a value corresponding to the image plane position in the lens design when the lens unit 10 is not decentered.
For example, if the designed image plane positions I0 to I4 in the lens design are 0, the in-focus positions Gi are equal to each other.
On the other hand, when the test lens unit 10 is decentered, the image plane moves from the lens design value according to the decentering, so the focus position Gi changes according to the amount of movement of the image plane.

  As described above, in steps S4 to S8, the focusing chart 2 is imaged through the lens unit 10 while moving the third lens L3, and image data corresponding to each of the measurement areas A0 to A4 is acquired and measured. An image contrast for each of the areas A0 to A4 is calculated as a focus evaluation value, and a focus position detection step for detecting the focus positions G0 to G4 of the third lens L3 by the hill climbing method in each of the measurement areas A0 to A4 is configured. ing.

Next, in step S9, correction value calculation processing is performed.
This step calculates an eccentricity adjustment amount after performing an eccentricity adjustment amount calculation step of calculating an eccentricity adjustment amount of the lens unit 10 to be measured based on the focus positions G0 to G4 detected for each of the measurement areas A0 to A4. This is a step of performing a correction value calculation step of calculating a lens position correction value for correcting the eccentricity adjustment amount measured in the step.
This step is performed by executing steps S21 to S25 according to the flow shown in FIG.
Here, steps S21 to S24 constitute an eccentricity adjustment amount calculation step, and step S25 constitutes a correction value calculation step.

In step S21, the image planes of the points p1 to p4 with respect to the image plane position (center image plane position) of the point p0 from the in-focus position Gi (i = 0,..., 4) according to the following equations (1) to (4). This is a step of calculating the image plane movement amount t _bi (i = 1,..., 4) of the position (peripheral image plane position).

t _b1 = (G1-G0) · k (1)
t _b2 = (G2-G0) · k (2)
t _b3 = (G3-G0) · k (3)
t _b4 = (G4-G0) · k (4)

Here, k is a movement amount conversion coefficient for converting the unit movement amount of the third lens L3 by the lens driving unit 11i into the image plane movement amount of the lens unit 10 to be tested, and is initially set in advance in step S2. .
The movement amount conversion coefficient k is an amount inherent to the optical system of the lens unit 10 to be measured, and can be calculated by optical simulation.

In this step, first, the movement amount conversion coefficient k and the focus positions G0 to G4 are sent from the focus position detection control unit 110 to the eccentricity adjustment amount calculation unit 111.
Next, the eccentricity adjustment amount calculation unit 111 calculates the above formulas (1) to (4), and calculates each image plane movement amount t _bi .
Above, step S21 is complete | finished.

Next, step S22 is performed. This step is a step of calculating the one-side blur amount and the peripheral image plane deviation amount of the lens unit 10 to be measured from the image plane movement amount t _bi (i = 1,..., 4).

The asymmetric blur amount, an evaluation quantity related to the resolution reduction in the specific direction of the image peripheral portion, and the asymmetric blur amount x _t in the horizontal direction of the photographing range represented by the following formula (5) (x-axis direction), consisting of a one-sided blur amount y _t in the vertical direction of the shooting range represented by the following formula (6) (y-axis direction).
Sided blur amount x _t corresponds to an image plane movement caused by shifting the eccentricity of the x-axis direction, and the y-axis tilt eccentricity.
Sided blur amount y _t corresponds to the image plane movement caused by shifting the eccentricity of the y-axis direction, and the x-axis tilt eccentricity.

Here, W _x and W _y are correction coefficients for normalizing (normalizing) the difference between the arrangement positions of the measurement areas A1 to A4 in the x-axis direction and the y-axis direction, and are initialized in advance in step S2. ing.
The correction coefficients W _x and W _y can be determined in advance according to the difference between the x coordinate and the y coordinate of the points p1 to p4, respectively. For example, when the ratio of the x coordinate and the y coordinate of the points p1 to p4 is 0.8: 0.6, W _x = 0.8 and W _y = 0.6 may be set.

The peripheral image plane shift amount, an evaluation quantity related to the overall reduction in resolution at the peripheral portion with respect to the center portion of the image, consisting of peripheral image plane shift amount z _w represented by the following formula (7). Therefore, the peripheral image plane shift amount z _w, different changes in the field curvature, which is one of the aberrations of the lens unit 10, although associated with the defocus amount, the curvature of field and the defocus amount itself amount It is.

In this step, the eccentricity adjustment amount calculation unit 111 calculates the above formulas (5) to (7) to calculate the one-side blur amount x _t , one-side blur amount y _t , and the peripheral image plane deviation amount z _w .
The calculated one-side blur amount x _t , one-side blur amount y _t , and peripheral image plane displacement amount z _w are sent to the display control unit 113 as necessary, and are displayed on the display unit 6 as image information such as numerical information and graphs. Is displayed.
Above, step S22 is complete | finished.

Next, step S23 is performed. This step-side blur amount x _t, as eccentricity amount corresponding to the one-sided blur amount y _t is caused by the tilt of the first lens L1, a lens tilt is eccentricity adjustment amount for correcting the eccentricity corresponding to the side blur component This is a step of calculating quantities E _x and E _y .
The lens tilt amounts E _x and E _y are calculated by the eccentricity adjustment amount calculation unit 111 based on the following equations (8) and (9).

E _x = x _t / x _c (8)
E _y = y _t / y _c (9)

Here, the lens tilt amount E _x (E _y ) represents an adjustment amount of the tilt of the first lens L1 around the y (x) axis.
Further, x _c (y _c ) is an inclination that is converted into the magnitude of the tilt decentering amount of the first lens L1 for correcting the decentering amount of the lens unit 10 corresponding to the one-side blur amount x _t (y _t ). Correction coefficient. The inclination correction coefficient x _c (y _c ) is initially set in advance in step S2.
The tilt correction coefficient x _c (y _c ) is an amount specific to the optical system of the lens unit 10 to be tested, and corresponds to the tilt amount of the first lens L1 and the one-side blur amount x _t (y _t ) by optical simulation. By determining the relationship with the image plane movement amount, it can be determined in advance.
The calculated lens tilt amounts E _x and E _y are sent to the lens position correction value calculation unit 112. Further, it is also sent to the display control unit 113 as necessary, and is displayed on the display unit 6 as image information such as numerical information and a graph.
Above, step S23 is complete | finished.

Next, step S24 is performed. This step, as a positional deviation of the lens corresponding to the peripheral image plane shift amount z _w are caused by positional deviation of the direction (z-axis direction) along the optical axis of the first lens L1, the peripheral image plane shift amount z _w a step of calculating the movement amount D _z of the first lens L1 be corrected.
The lens movement amount _Dz is calculated by the eccentricity adjustment amount calculation unit 111 based on the following equation (10).

D _z = z _w / z _c (10)

Here, z _c, in order to correct the movement in the direction along the peripheral image plane shift amount z _w to the optical axis O of the first lens L1, the peripheral image plane shift amount z _w to the amount of movement of the first lens L1 This is a peripheral image plane shift amount correction coefficient to be converted. Peripheral image plane shift amount correction coefficient z _c is previously initialized in step S2.
The peripheral image plane deviation correction coefficient z _c is an amount specific to the optical system of the lens unit 10 to be measured, and by obtaining the relationship between the movement amount of the first lens L1 and the image plane movement amount by optical simulation, It can be determined in advance.
The calculated lens movement amount D _z is sent to the lens position correction value calculation unit 112. Further, it is sent to the display control unit 113 as necessary, and is displayed on the display unit 6 as image information such as numerical information and a graph.
Above, step S24 is complete | finished.

Next, step S25 is performed. This step is based on the lens tilt amounts E _x and E _y that are correction values of the one-sided blur component calculated in step S23 and the lens movement amount D _z that is the correction value of the peripheral image plane deviation component calculated in step S24. This is a step of calculating a lens position correction value combining each of them.

The lens tilt amounts E _x and E _y and the lens movement amount D _z are correction values that are established regardless of the decentration correction mechanism of the test lens unit 10. In order to perform the 10 eccentricity adjustment, it is preferable to convert it into a lens position correction value corresponding to a specific adjustment operation.
In this embodiment, since the eccentricity adjustment is performed by changing the thickness of the spacers 14A, 14B, 14C, the lens position correction value calculation unit 112 realizes the lens tilt amounts E _x , E _y and the lens movement amount D _z . The thicknesses of the spacers 14A, 14B, and 14C for the purpose are calculated.

The one-sided blur component Kansa amounts E _A , E _B , E _C corresponding to the thicknesses of the spacers 14A, 14B, 14C necessary for the first lens L1 to have lens tilt amounts E _x , E _y are given by It is obtained by (11), (12), (13).
However, since the one-sided blur component Kansa amounts E _A , E _B , and E _C have negative values in some cases, they do not coincide with the thicknesses of the spacers 14A, 14B, and 14C.

Further, since the lens movement amount _Dz is the lens movement amount itself of the first lens L1 in the z-axis direction, it corresponds to the thickness of the spacers 14A, 14B, and 14C by itself.
However, the lens movement amount _{D z} is to take also negative Optionally, spacers 14A, 14B, not coincide with the thickness of 14C.

The lens position correction value calculation unit 112 simultaneously corrects the tilt of the first lens L1 and the position in the direction along the optical axis as a lens position correction value for correcting the decentering and the image plane position accompanying the decentering. , Kanza amounts K _A , K _B , and K _{C according} to the following formulas (14), (15), and (16) are calculated.

K _A = E _A + D _z + t (14)
K _B = E _B + D _z + t (15)
K _C = E _C + D _z + t (16)

Here, if the range ± t of the eccentricity adjustment amount is appropriate, the Kansa amounts K _A , K _B , and K _C are numerical values of 0 or more and 2 t or less, and the lens positions representing the thicknesses of the spacers 14A, 14B, and 14C themselves. It is a correction value.

Furthermore, Kanza amount _{K A, K B, K C,} the following equation (17), (18), as in (19), the rounded fractions below P, Kanza amount _{K A ', K B',} K It is also possible to calculate as _C ′.

K _A ′ = P · ROUND (K _A / P) (17)
K _B ′ = P · ROUND (K _B / P) (18)
K _C '= P · ROUND (K _C / P) (19)

Here, P is a minimum dimensional difference in spacer thickness when the spacers 14A, 14B, and 14C are prepared by changing the thickness stepwise. ROUND (C) is a function representing an operation of rounding off the first decimal place of the argument C.
The value of P can be set as appropriate based on the required eccentricity adjustment accuracy in the lens unit 10 to be tested.
If the Kanza amounts K _A ′, K _B ′, K _C ′ are used, the types of spacer thickness corresponding to these can be reduced as compared with the case where the Kanza amounts K _A , K _B , K _C are used. preferable.

The calculated Kanza amounts K _A , K _B , K _C or the Kanza amounts K _A ′, K _B ′, K _C ′ are stored in the measurement control device 5. Then, it is sent to the display control unit 113 as necessary, and can be displayed on the display unit 6 as image information such as numerical information and graphs.
Above, step S25 is complete | finished. Thereby, step S9 shown in FIG. 7 is completed.

Next, in step S <b> 10, the lens unit 10 to be tested is removed from the camera body 3.
This is the end of the eccentricity adjustment amount measurement method of the present embodiment using the eccentricity adjustment amount measurement system 1.

In this way, according to the eccentricity adjustment amount measuring system 1, the eccentricity adjustment amount is measured according to the eccentricity of each lens unit 10 to be measured, and the position and orientation of the first lens L1 are corrected by this eccentricity adjustment amount. As the lens position correction value for this purpose, the Kanza amounts K _A , K _B , K _C or the Kanza amounts K _A ′, K _B ′, K _C ′ are calculated.

In order to adjust the eccentricity of the lens unit 10 to be detected using these lens position correction values, the lens position adjustment process is performed after the lens unit 10 is removed from the eccentricity adjustment amount measuring system 1.
In the lens position adjustment step, the spacers 14A, 14B, and 14C having the thickness t of the lens unit 10 to be tested are matched with the Kansa amounts K _A , K _B , and K _C or the Kanza amounts K _A ′, K _B ′, and K _C ′. This is a step of adjusting the eccentricity of the lens unit 10 to be tested by exchanging the spacers 14A, 14B, and 14C having the above thicknesses.

  Since this step can be performed as a separate step outside the eccentricity adjustment amount measurement system 1, it is not necessary to occupy the eccentricity adjustment amount measurement system 1. In the eccentricity adjustment amount measurement system 1, the other lens unit 10 to be tested is used. The amount of eccentricity adjustment can be measured sequentially.

According to the eccentricity adjustment amount measurement system 1 and the eccentricity adjustment amount measurement method using the same, the focusing chart 2 is imaged, and a plurality of different measurement areas A0 to A4 on the image of the focusing chart 2 are combined by the hill climbing method. In order to calculate the decentering adjustment amount by measuring the focal position Gi, the decentering adjustment amount required for the decentering adjustment of the lens unit 10 to be measured can be obtained commercially or planned to be sold without using an expensive device such as an MTF inspection machine. Measurement can be performed in a short time using a simple device such as the camera body 3.
In addition, the size of the apparatus can be reduced compared with the case of using an MTF inspection machine, and space can be saved.

  In the eccentricity adjustment amount measurement system 1, the image pickup unit and the focus position detection unit use the image pickup element 3 a provided with the camera body 3 and the focus position detection unit 101, so that the device configuration of the measurement control device 5 is simple. It becomes. Furthermore, since the body mount 3c and the like unique to the lens unit 10 to be tested are provided in the camera body 3, the versatility of the apparatus configuration of the eccentricity adjustment amount measurement system 1 excluding the camera body 3 is improved.

In eccentricity adjustment value measuring system 1, which is eccentric adjustment amount lens tilt amount E _x, E _y is the center image plane position in the image center, and calculates a peripheral image position at the periphery of the image, the central image plane position And the deviation between the image plane position and the peripheral image plane position.
For this reason, the focus position for calculating the center image plane position and the peripheral image plane position is set to one focus position G0 in the center of the image and four focus positions G1 to G4 in the periphery of the image. It is only necessary to measure a total of five in-focus positions.
Thereby, since the measurement location of the focus position Gi can be reduced compared with a prior art, it can measure more rapidly and in a short time.

In the decentering adjustment amount measuring system 1, the lens tilt amounts E _x and E _y corresponding to the decentering amount of the test lens unit 10 can be calculated and displayed on the display unit 6. Information corresponding to is also obtained. For this reason, it is useful for process management.

[Modification]
Next, an eccentricity adjustment amount measuring method according to a modification of the present embodiment will be described.
FIG. 12 is a flowchart showing a measurement flow of the eccentricity adjustment amount measuring method according to the modification of the embodiment of the present invention. FIG. 13 is a flowchart showing a flow of focus position detection processing in the eccentricity adjustment amount measuring method according to the modification of the embodiment of the present invention.

The eccentricity adjustment amount measuring method of this modification is a method for adjusting the eccentricity of the lens unit 10 to be measured using the same eccentricity adjustment amount measurement system 1 as in the above embodiment. However, the method for measuring the amount of eccentricity adjustment in the embodiment described above is that the in-focus position is obtained by repeating a plurality of steps for each measurement area, whereas the in-focus positions in all the measurement areas are obtained collectively. Different from the above embodiment.
Hereinafter, a description will be given focusing on differences from the above embodiment.

In the method of this modification, steps S31 to S35 are executed according to the flow shown in FIG.
Steps S31 and S32 are the same as steps S1 and S2 in the above embodiment.

In step S33, focus position detection processing is performed.
This step is performed by executing steps S41 to S48 according to the flow shown in FIG.
Step S41 is the same as step S11 in the above embodiment.

Next, step S42 is performed. This step is a step for setting the measurement area of the in-focus position to the measurement areas A0 to A4.
Specifically, a command for setting the measurement area to measurement areas A0 to A4 and starting detection of the focus position is sent from the focus position detection control unit 110 of the measurement control device 5 to the camera body 3. This command is analyzed by the external command analysis unit 103. Thereby, the operation | movement after the following step is performed by the camera control part 3d.
Above, step S42 is complete | finished.

Next, in step S43, the camera control unit 3d sends a control signal to the lens driving unit 11i to move the moving lens frame 13 by the unit movement amount toward the closest position. The focus position moves corresponding to the unit movement amount.
Next, in step S44, the focus position detection unit 101 calculates focus evaluation values in the measurement areas A0 to A4.

Next, step S45 is a step of determining whether or not there is a measurement area beyond the in-focus position.
In this step, the focus position detection unit 101 evaluates the change of the focus evaluation value in the measurement areas A0 to A4, and determines whether or not the focus evaluation value exceeds the peak.
If there is a measurement area beyond the in-focus position, the process proceeds to step S46.
If the in-focus position has not been exceeded, the process proceeds to step S43, and steps S43 to S45 are repeated.

  Step S46 is a step of storing the in-focus position Gj of the measurement area Aj beyond the in-focus position in the memory of the in-focus position detecting unit 101. Here, j indicates a subscript of all measurement areas beyond the in-focus position.

Next, step S47 is a step in which the focus position detection unit 101 removes the measurement area Aj beyond the focus position from the measurement area.
The excluded measurement area is not a target for calculating the focus evaluation value when step S44 is executed.

Next, step S48 is a step of determining whether or not the measurement area remains by the focus position detection unit 101.
When no measurement area remains, the focus positions G1 to G4 stored in the focus position detection unit 101 are sent to the measurement control device 5, and the focus position detection process is terminated. Thereby, step S33 shown in FIG. 12 is completed.
When the measurement area remains, the process proceeds to step S43, and steps S43 to S48 are repeated.

  In this way, in step S33, every time the focus position moves, the focus evaluation value is calculated in parallel in each measurement area, and the focus evaluation value is calculated sequentially from the measurement area beyond the focus position. Is stopped. For this reason, in this step, in the measurement areas A0 to A4, the in-focus position is searched by the hill-climbing method.

Next, steps S34 and S35 shown in FIG. 12 are performed.
These steps are similar to steps S9 and S10 in the above embodiment.

In this modification, by moving the third lens L3, the in-focus position Gi is detected by the in-focus position detector 101 only by moving the focus position from the infinite position to the closest side once. Only the embodiment is different.
For this reason, the calculation of the eccentricity adjustment amount and the eccentricity adjustment based on the eccentricity adjustment amount can be performed in exactly the same manner as in the above embodiment.
In the present modification, the number of movements of the third lens L3 is reduced as compared with the above embodiment, so that the measurement time of the eccentricity adjustment amount can be further shortened.

  In the above description of the embodiment and the modification, an example in which an image contrast is used as the focus evaluation value has been described. However, the camera control unit 3d of the camera body 3 can calculate the focus evaluation value. As long as the evaluation value is high, the contrast of the image is not limited. For example, resolution or the like may be used as the focus evaluation value.

  In the above description of the embodiment and the modification, the eccentricity adjustment amount measurement system 1 includes the camera body 3 so that the imaging unit is configured by the built-in imaging unit of the camera body 3 and the in-focus position detection processing unit is the camera. Although an example in which the built-in in-focus position detection unit of the body 3 and the in-focus position detection control unit of the measurement control device 5 are described has been described, when the device portion corresponding to the camera body 3 is configured by a dedicated device, The built-in focus position detection unit and the focus position detection control unit may be realized as a focus position detection processing unit having a single device configuration. In this case, the communication connection units 3e and 5e and the USB connection cable 9 can be omitted.

In the above description of the embodiment and the modification, the example in which the position of the first lens L1 is moved using the spacers 14A, 14B, and 14C based on the eccentricity adjustment amount has been described. However, the spacers 14A and 14B are described. , 14C number, arrangement position, shape and the like are examples. For this reason, the structure which has arrange | positioned the spacer of 4 or more appropriate shapes in the position different from said arrangement | positioning position is also possible.
Further, the means for moving the position of the first lens L1 is not limited to the spacer. For example, the holding position of the first lens L1 can be fixed with a jig or the like, and the position can be fixed by filling the adhesive with the lens receiving portion 12a. In this case, since the effort does not change even if the position of the first lens L1 is changed in an analog manner, it is preferable to use the Kansa amounts K _A , K _B , and K _C as the lens position correction values.

  In the above description of the embodiment and the modification, the example in which the lens unit 10 is used as the lens assembly has been described, but this is an example, and depending on the configuration of the lens assembly, a moving lens, The adjustment lens used for the eccentricity adjustment and the eccentricity adjusting means can be set as appropriate.

  In the above description of the embodiment and the modified examples, the lens assembly is described as an example of an interchangeable lens for a camera. However, for example, a lens used for an optical device different from a digital camera such as a video or an endoscope. The eccentricity adjustment can be performed in the same manner.

  In the above description of the embodiment and the modification, the fixed lens frame 11 has the lens driving unit 11i, and the built-in focus position detection unit of the camera body 3 sends a control signal to the lens driving unit 11i. In the example of moving the lens frame 13, the lens driving unit 11 i may be deleted, and a lens driving unit for driving the lens frame 13 may be built in the camera body 3 side.

  Moreover, all the components described in the above embodiments and modifications can be implemented by being appropriately combined or deleted within the scope of the technical idea of the present invention.

1 Eccentricity adjustment amount measuring system (Eccentricity adjustment amount measuring device)
2 In-focus charts 2A, 2B, 2C, 2D, 2E In-focus evaluation pattern portion (in-focus evaluation pattern)
3 Camera body (camera)
3a Imaging device (built-in imaging unit, imaging unit)
3c body mount 3d camera control unit 3e, 5e communication connection unit 5 measurement control device 7 operation unit 10 lens unit to be tested (lens assembly)
DESCRIPTION OF SYMBOLS 11 Fixed lens frame 11i Lens drive part 12 Adjustment lens frame 12A, 12B, 12C Flange part 13 Moving lens frame 14A, 14B, 14C Spacer 15 Fixing screw 100 Image processing part 101 Focus position detection part (Built-in focus position detection part, Focus position detection processing unit)
110 Focus position detection control unit (focus position detection processing unit)
111 Eccentricity adjustment amount calculation unit 112 Index position correction value calculation unit A0 Measurement area (center area)
A1, A2, A3, A4 Measurement area (peripheral area)
G0, G1, G2, G3, G4, Gi, Gj In-focus position L1 First lens L2 Second lens L3 Third lens (moving lens)
O Optical axis

Claims (10)

An eccentricity adjustment amount measuring device for measuring an eccentricity adjustment amount of a lens assembly including a moving lens for adjusting a focus position,
A focusing chart having a focusing evaluation pattern for detecting a focusing position;
An imaging unit for imaging the focusing chart through the lens assembly;
In the image data of the focusing chart imaged by the imaging unit, a plurality of predetermined different measurement areas are designated, and the image contrast of each measurement area is used as a focus evaluation value while moving the moving lens. An in-focus position detection processing unit that calculates and detects the in-focus position of the moving lens by a hill-climbing method in each of the measurement areas;
An eccentricity adjustment amount calculation unit that calculates an eccentricity adjustment amount of the lens assembly based on the in-focus position detected for each measurement area;
An eccentricity adjustment amount measuring device comprising: The measurement area is
A central area around the optical axis of the lens assembly;
Peripheral areas respectively located at the four corners of the imaging region by the lens assembly and the imaging unit;
The eccentricity adjustment amount measuring device according to claim 1, comprising: The in-focus evaluation pattern of the in-focus chart is:
3. The eccentricity adjustment amount measuring apparatus according to claim 1, wherein the eccentricity adjustment amount measuring apparatus is a lattice pattern provided at a position corresponding to each of the measurement areas and in which white lines and black lines are arranged at equal intervals. The white line and the black line of the lattice pattern are:
The eccentricity adjustment amount measuring apparatus according to claim 3, wherein the eccentricity adjustment amount measuring apparatus extends along a tangent line of a concentric circle with respect to a center of the focusing chart. The in-focus evaluation pattern of the in-focus chart is:
The eccentricity adjustment amount measuring apparatus according to claim 1, wherein the eccentricity adjustment amount measuring apparatus is formed in a wider range than the measurement area. A camera to which the lens assembly can be attached;
The camera
A built-in imaging unit for imaging a subject by the lens assembly;
A built-in in-focus position that calculates the contrast of an image captured by the built-in imaging unit as a focus evaluation value while moving the moving lens of the lens assembly, and detects the in-focus position of the moving lens by a hill-climbing method A detection unit;
A communication connection unit for communicating with the built-in in-focus position detection unit;
Have
The imaging unit includes the built-in imaging unit.
The in-focus position detection processing unit is connected to the built-in in-focus position detection unit and connected to the built-in imaging unit and the built-in in-focus position detection unit via the communication connection unit while being provided outside the camera. An in-focus position detection control unit,
The in-focus position detection control unit
The plurality of different measurement areas are designated for the built-in focus position detection unit, and operation control of the built-in focus position detection unit is performed so as to detect the focus position of the moving lens for each measurement area. The eccentricity adjustment amount measuring apparatus according to claim 1, wherein the focus position is acquired from the built-in focus position detection unit. The eccentricity adjustment amount calculation unit
A central image plane position at the center of the image and a peripheral image plane position at the periphery of the image are calculated from the in-focus position for each measurement area, and a deviation between the central image plane position and the peripheral image plane position is used. The eccentric adjustment amount measuring apparatus according to claim 1, wherein the eccentric adjustment amount is calculated. An eccentricity adjustment amount measuring method for measuring an eccentricity adjustment amount of a lens assembly including a moving lens for adjusting a focus position,
A measurement area setting step for setting a plurality of different measurement areas for detecting a focus position from image data of a focus chart having a focus evaluation pattern for detecting a focus position;
While moving the moving lens, the focusing chart is imaged through the lens assembly, image data corresponding to each of the measurement areas is acquired, and image contrast for each measurement area is calculated as a focus evaluation value. An in-focus position detecting step of detecting the in-focus position of the moving lens by a hill-climbing method in each of the measurement areas;
An eccentricity adjustment amount calculating step of calculating an eccentricity adjustment amount of the lens assembly based on the in-focus position detected for each measurement area;
An eccentricity adjustment amount measuring method comprising: The eccentricity adjustment amount calculating step includes:
A central image plane position at the center of the image and a peripheral image plane position at the periphery of the image are calculated from the in-focus position for each measurement area, and a deviation between the central image plane position and the peripheral image plane position is used. The eccentric adjustment amount measuring method according to claim 8, wherein the eccentric adjustment amount is calculated. The eccentric adjustment amount is measured by the eccentric adjustment amount measuring method according to claim 8 or 9,
An eccentricity adjustment method for changing a lens position of the lens assembly based on the eccentricity adjustment amount.

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