JP4933961B2 - Camera module focus adjustment apparatus and focus adjustment method - Google Patents

Description

  The present invention relates to a focus adjustment device and a focus adjustment method for bringing a focus lens of a camera module into focus.

  In recent years, the mounting rate of a camera module for capturing a still image or a moving image in a mobile phone or the like is increasing, which is a factor in increasing the demand for the camera module. As a camera module, a CCD (charge coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor is mainly used, and the demand for the CCD sensor and the CMOS sensor is increasing.

  In recent years, camera modules mounted on mobile phones and the like have been demanded to have higher pixels, higher performance, and higher functionality from the viewpoint of improving image quality, etc., and focus adjustment of the focus lens of the camera module is optimally performed. It is demanded. In particular, in the case of a camera module mounted on a mobile phone, it is usually manufactured on the assumption that the focus is at least at infinity or a predetermined close-up distance, and the focus can be adjusted well at the time of manufacture. It has been demanded.

  Conventionally, focus adjustment at the time of manufacturing is generally performed by the operator manually checking the captured image of the camera module displayed on the display unit of the tester while manually moving the focus lens of the camera module in the optical axis direction. To adjust the focus position. Alternatively, the operator adjusts the focus while confirming the indicator indicating the sharpness of the captured image displayed on the display unit of the tester by manual operation.

  However, when the focus is adjusted manually by an operator, there is a problem that the manufacturing cost is drastically increased due to a high labor cost. Further, there is a problem in that the focus adjustment accuracy differs depending on the worker, that is, the quality of the camera module is affected by the worker, and it is difficult to sufficiently stabilize the quality.

  On the other hand, the focus adjustment technology of the camera module, for example, captures a video signal, extracts a sharpness signal indicating that the higher the level is in focus from the video signal, and detects the maximum level of the sharpness signal A focus adjustment device that stores the maximum level and the position of the focus lens at this time, and reverses the moving direction of the focus lens when the level of the sharpness signal is lower than the maximum level by a predetermined determination level or more. Yes (see, for example, Patent Document 1). This focus adjustment device obtains the number of peak crossings based on the number of determinations in the moving direction, and when the number of peak crossings exceeds a predetermined number of determinations, the focus lens is positioned at the focus lens position corresponding to the stored maximum level. Move.

Hereinafter, a conventional focus adjustment apparatus will be briefly described with reference to FIGS. 10 and 11. Here, FIG. 10 shows a processing procedure of automatic focusing processing (mountain climbing autofocus processing) of the focus adjustment apparatus according to the conventional technology. FIG. 11A shows the relationship between the level L of the sharpness signal and the position (tightening angle) θ of the focus lens FL. FIG. 11 (b), tightening the angle theta _U of the focus lens FL to the lens holder LH is shows a state less than the tightening angles theta _J in a state where is in focus (under-focus). FIG. 11 (c), tightening the angle of the focus lens FL to the lens holder LH is shows a state (just focus) matching the fastening angle theta _J. FIG. 11D shows a state (overfocus) in which the tightening angle θ _O of the focus lens FL with respect to the lens holder LH exceeds the tightening angle θ _J.

  As shown in FIG. 10, in the automatic focusing process, the focus adjustment device according to the conventional technique first initializes the maximum value Lmax of the level of the sharpness signal, a variable for storing the number of times of peak crossing, and the like (step # 200). ). Subsequently, the focus lens FL is moved in the optical axis direction by a preset unit movement amount (step # 201), and position information indicating the position of the focus lens FL at this time, here, a tightening angle θ is obtained ( Step # 202).

  Subsequently, the focus adjustment device acquires a focus adjustment image from the image sensor of the camera module (step # 203), generates a sharpness signal from the acquired focus adjustment image, and obtains a level L of the sharpness signal (step # 203). # 204). Further, the level L of the sharpness signal is compared with the value of the maximum value Lmax of the level of the sharpness signal. If the level L of the newly calculated sharpness signal is larger, the value of the maximum value Lmax is newly set. The calculated sharpness signal is replaced with the level L value, and the tightening angle θ at this time is stored as the tightening angle θmax in the best focus state.

  Further, the focus adjustment device determines whether or not the calculated level L of the sharpness signal has decreased from a stored maximum value Lmax by a predetermined determination level or higher (step # 205). If it is determined that the level is lower than the determination level from Lmax, the driving direction of the focus lens FL is reversed (step # 206). More specifically, for example, in FIG. 11A, when the focus lens FL is moved in the direction in which the tightening angle θ is increased to reach the Po state, the sharpness signal level Lo is the maximum value Lmax. The driving direction is reversed because it becomes lower than the determination level La. In addition, the movement amount is set again in the direction in which the tightening angle decreases. Further, the focus adjustment device determines that there is a peak crossing, and increases the value of a variable indicating the number of peak crossings by one.

  Subsequently, when the number of peak crossings is equal to or less than the predetermined determination number ("NG" branch in step # 207), the focus adjustment device repeatedly executes the processing of step # 201 to step # 206, and the number of peak crossings is preset. If the determined number of determinations is exceeded ("OK" branch in step # 207), the focus lens FL is moved to the tightening angle θmax corresponding to the stored maximum value Lmax, and the automatic focusing process is terminated (step #). 208). As a result, the focus lens FL can finally be moved to the state shown in FIG. 11C, and the focus of the camera module can be adjusted with high accuracy.

JP-A-6-62305

  However, the focus adjustment device described in Patent Document 1 is configured to repeatedly execute focus lens movement processing, video signal capture processing, sharpness signal extraction processing, and determination processing using the level of the sharpness signal. In particular, from the viewpoint of focus adjustment accuracy, the focus lens movement amount is set more finely as the focus position is approached, so it is difficult to reduce the number of steps related to focus adjustment. There is a problem that it takes a considerable time to complete the adjustment.

  Furthermore, as described above, the production quantity of camera modules is increasing in response to the recent increase in the mounting rate of camera modules in mobile phones and the like. For this reason, when the focus adjustment apparatus described in Patent Document 1 is applied to a camera module manufacturing apparatus, there is a possibility that the increase in the production quantity may not be appropriately handled from the viewpoint of manufacturing time, and it is necessary to manufacture the camera module. A technique for shortening the time is desired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a focus adjustment device capable of reducing the focus adjustment time of the camera module without reducing the focus adjustment accuracy. It is in. Furthermore, a focus adjustment method is provided that can reduce the focus adjustment time of the camera module without reducing the focus adjustment accuracy.

In order to achieve the above object, a focus adjustment apparatus according to the present invention is a focus adjustment apparatus used for focus adjustment of a camera module at the time of manufacture, and the focus lens of the camera module is connected to an image sensor of the camera module. In the first focus adjustment process for achieving the in-focus state, a drive control unit that controls a drive device that moves the focus lens in the optical axis direction, and the focus lens every time the focus lens is moved by the drive control unit Position detection means for detecting position information indicating the position of the image sensor, image acquisition means for acquiring a focus adjustment image from the image sensor for each movement of the focus lens by the drive control means, and the image acquisition means For each focus adjustment image, from the focus adjustment image The first calculation means for calculating a degree of focus indicating the focus state of the focus lens and the first calculation means respectively obtain the degrees of focus at different positions of three or more focus lenses, and obtain the acquired Using the in-focus degree, the in-focus degree is maximized from the second calculating means for obtaining an approximate curve indicating the relationship between the position information and the in-focus degree, and the approximate curve obtained by the second calculating means. Third calculation means for obtaining the optimum position information that is the position information at the time, and a part of the driving range of the focus lens capable of acquiring an image from the image sensor as a reference range, before execution of the first focus adjustment process In the pre-processing for adjusting the position of the focus lens within the reference range, the position information is acquired from the position detection unit every time the focus lens is moved by the drive control unit. Position determining means for determining whether or not the position of the focus lens is within the reference range based on the acquired position information, wherein the drive control means is calculated by the third calculation means. The driving device is controlled based on the optimum position information, and the focus lens is moved to the position indicated by the optimum position information, and the drive control means further includes the position determination means in the preprocessing. The driving device is configured to be repeatedly controlled until it is determined that the position of the focus lens is within the reference range, and the position determination unit determines that the position of the focus lens is within the reference range. When the first focus adjustment process is started , the reference range is preliminarily set within a range including the optimum position where the focus degree is maximum. The image acquisition means acquires the focus adjustment image when the position indicated by the position information acquired by the position detection means is within the reference range in the first focus adjustment processing; In the first focus adjustment process, the driving means performs the approximation by the second computing means based on the focus information obtained by the first computing means and the position information corresponding to each of the focus degrees. It is determined whether or not a curve can be calculated, and when it is determined that the approximate curve cannot be calculated by the second calculation means, the reference range is expanded to a predetermined range set in advance. Features.

More preferably, in the focus adjustment apparatus according to the present invention having the above characteristics, in the second focus adjustment processing for the drive control means to bring the focus lens into a focused state, the focus before the movement of the focus lens is performed. A difference value between the degree of focus and the degree of focus after movement, and the drive direction and unit movement amount of the drive device are set based on the difference value, and the drive control means in the second focus adjustment process A degree-of-focus determination means for determining whether or not the focus lens is in focus based on the degree of focus calculated by the first calculation means for each movement of the focus lens; and the first focus adjustment In the processing, based on the focus information obtained by the first calculation means and the position information corresponding to each of the focus degrees, the second calculation means A focus process switching unit that determines whether or not the approximate curve can be calculated, and starts the second focus adjustment process when it is determined that the approximate curve cannot be calculated by the second calculation unit. And comprising .

More preferably, in the focus adjustment apparatus according to the present invention having any one of the above features, the second calculation means uses the degree of focus as a dependent variable, and a secondary or higher order having a position variable indicating the position information as an independent variable. The polynomial of is calculated. More preferably, in the focus adjustment apparatus according to the present invention having any one of the above characteristics, the drive control unit moves the focus lens by a predetermined first unit movement amount in the preprocessing, and the first focus adjustment is performed. In the processing, the focus lens is moved by a second unit movement amount smaller than the first unit movement amount.

A focus adjustment method according to the present invention for achieving the above object is a focus adjustment method used for focus adjustment of a camera module at the time of manufacture, wherein the focus lens of the camera module is aligned with the image sensor of the camera module. In the first focus adjustment step for bringing the focus lens into the focus state, the first lens driving step for controlling the driving device that moves the focus lens in the optical axis direction and the focus lens of the focus lens each time the first lens driving step is executed. A calculation preparation step consisting of a first position detection step of detecting position information indicating a position and an image acquisition step of acquiring a focus adjustment image from the image sensor every time the first lens driving step is executed three times. The focus is repeated for each of the focus adjustment images acquired in the image acquisition step. Using the first calculation step for calculating the degree of focus indicating the focus state of the focus lens from the adjustment image, and using the degree of focus calculated in the first calculation step, the position information and the degree of focus are calculated. A second calculation step for obtaining an approximate curve indicating the relationship; and a third calculation step for obtaining optimum position information which is the position information when the degree of focus is maximized from the approximate curve obtained in the second calculation step. And a lens adjustment step of controlling the driving device based on the optimum position information obtained in the third calculation step and moving the focus lens to a position indicated by the optimum position information. , A part of the driving range of the focus lens capable of acquiring an image from the image sensor as a reference range, and the position of the focus lens before the execution of the first focus adjustment process In a pre-processing step of adjusting within a sub-range, a second lens driving step for controlling the driving device, and a second position detecting step for detecting the position information of the focus lens every time the second lens driving step is executed. And a position determination step of determining whether or not the position of the focus lens is within a predetermined reference range set in advance based on the position information detected in the second position detection step. Configured and repeatedly executing a pre-processing step until the position determination step determines that the position of the focus lens is within the reference range in the position determination step before the first focus adjustment step . In the image acquisition step, in the first focus adjustment step, in the first focus adjustment step, the first position detection step When the position indicated by the position information acquired in step 1 is within the reference range, the focus adjustment image is acquired, and the second calculation step obtains the first calculation step before derivation of the approximate curve. Based on the position information corresponding to each of the in-focus level and the in-focus level, it is determined whether the approximate curve can be calculated in the second calculation step, and the approximate curve is calculated. When it is determined that it is not possible, the reference range is expanded to a predetermined range set in advance .

More preferably, in the focus adjusting method according to the present invention having the above characteristics, the focus calculation after the movement is obtained by executing the first calculation step every time the focus lens is moved by the drive device , and the drive device uses the focus adjustment method. A third lens driving step of obtaining a difference value between the in-focus degree before movement of the focus lens and the in-focus degree after movement, and setting a driving direction and a unit movement amount of the driving device based on the difference value; A second focus adjustment step comprising: a focus degree determination step for determining whether or not the focus lens is in focus based on the focus degree calculated in the third lens driving step can be executed. Configured and based on the position information corresponding to each of the in-focus degree and the in-focus degree calculated in the first operation step before the execution of the second operation step in the first focus adjustment step. When it is determined whether or not the approximate curve can be calculated in the second calculation step, and it is determined that the approximate curve cannot be calculated in the second calculation step, the second focus adjustment process And a focus process switching step for starting the process .

More preferably, in the focus adjustment method according to the present invention having any one of the above features, in the second calculation step, the degree of focus is used as a dependent variable, and a second or higher order using the position variable indicating the position information as an independent variable. The polynomial of is calculated. More preferably, in any one of the above-described focus adjustment methods according to the present invention, the second lens driving step moves the focus lens by a predetermined first unit movement amount, and the first lens driving step includes: The focus lens is moved by a second unit movement amount smaller than the first unit movement amount.

  According to the focus adjustment device having the above characteristics, since the focus lens focus position is determined based on the relationship between the position information and the focus degree, the position information and the focus lens are adjusted in order to adjust the focus lens focus. It is possible to adjust the focus lens to the optimum focus position simply by obtaining the data necessary for obtaining the relationship between the focus levels, that is, the focus level at different positions of three or more focus lenses. Become. In the conventional focus adjustment device, it is necessary to finely set the movement amount of the focus lens from the viewpoint of focusing accuracy of the focus lens. Acquisition of the focus adjustment image, calculation of the degree of focus, A considerable number of settings such as drive direction and movement amount must be performed. On the other hand, in the focus adjusting apparatus having the above characteristics, it is possible to greatly reduce the number of executions such as driving of the focus lens, acquisition of a focus adjustment image, and calculation of the degree of focus.

  Therefore, if the focus adjustment apparatus having the above characteristics is applied to a camera module manufacturing apparatus, the number of executions such as driving of a focus lens, acquisition of a focus adjustment image, and calculation of the degree of focus can be greatly reduced. The time required for focus adjustment can be greatly reduced.

  In particular, if the focus adjustment device having the above characteristics is applied to a camera module manufacturing apparatus, it is possible to significantly reduce the manufacturing time of the camera module, and more appropriately by increasing the production quantity due to the increase in demand for the camera module. It becomes possible to respond. In the focus adjusting apparatus having the above characteristics, it is necessary to store a plurality of degrees of focus and the position information in calculating an approximate curve indicating the relationship between the position information and the degree of focus. In the module manufacturing apparatus, since the capacity of the storage device is sufficient, shortening the manufacturing time is a priority issue.

  In addition, according to the focus adjustment device of the above feature, since the approximate position indicating the relationship between the position information and the degree of focus is derived and the optimum position information that is in focus is obtained, the focusing accuracy of the focus lens can be maintained, Since the focus is automatically adjusted, the quality of the camera module can be maintained stably.

Further, the focus lens moving direction (driving direction of the driving device) and unit moving amount are set from the difference value of the in-focus level before and after the movement of the focus lens, and the setting of the movement and movement of the focus lens is repeated a certain number of times. With this configuration, even when it is difficult to derive an approximate curve, the focus lens can be brought into focus.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a focus adjustment apparatus and a focus adjustment method according to the present invention (hereinafter simply referred to as “the present invention apparatus” and “the present invention method” as appropriate) will be described below with reference to the drawings.

<Configuration of the device of the present invention>
The configuration of the apparatus of the present invention will be described with reference to FIGS. In the present embodiment, description will be made assuming that the apparatus of the present invention is applied to a camera module manufacturing apparatus.

  Here, FIG. 1 shows a schematic configuration of a part for adjusting and inspecting the focus of the camera module M in the manufacturing apparatus 100 of the camera module M to which the apparatus 1 of the present invention is applied, and FIG. FIG. 11 schematically illustrates the relationship between the position of the focus lens FL and the degree of focus.

  As shown in FIGS. 1 and 2, the manufacturing apparatus 100 for the camera module M adjusts the camera module M and a transport device 133 that transports the camera module M to the attachment position of the focus adjustment jig 138 that performs focus adjustment processing. The image display device 130 for adjustment which provides the image 131, and the socket board 132 which transfers the captured image data imaged by the image sensor of the camera module M are configured.

  More specifically, as shown in FIG. 2, the manufacturing apparatus 100 of the camera module M converts the captured image data transferred from the socket board 132 into a digital focus adjustment image as a configuration related to normal manufacturing and inspection. AD conversion unit 101 for conversion, image storage unit 102 for storing the image for focus adjustment digitally converted by the AD conversion unit 101, information on the camera module M such as a lot number and focus adjustment from an external input device 134 such as a keyboard and a mouse External I / F 104 that receives processing execution start requests, etc., conveyance control unit 103 that controls the conveyance device 133 of the camera module M, illumination control unit 105 that controls the illumination device 135, DC inspection, dust stain inspection, and the like for the camera module M Inspection system that controls the inspection device 136 that performs resolution inspection and the like Unit 106, a focus adjustment jig controller that controls the focus adjustment jig 138 based on information from the line sensor 140, and a ROM 112 (Read Only Memory) that stores a program and setting values for executing focus adjustment processing. A RAM 113 (Random Access Memory) that temporarily stores variables and the like in a focus adjustment process and the like, and a CPU 110 (Central Processing Unit) that controls each of these functions are provided.

  The device 1 of the present embodiment of the present embodiment has a first focus adjustment process for bringing the focus lens FL of the camera module M into focus with respect to the image sensor of the camera module M, and before executing the first focus adjustment process. When it is difficult to adjust the focus lens FL within the predetermined reference range and the focus adjustment by the first focus process, the focus lens FL of the camera module M is aligned with the image sensor of the camera module M. It is configured to execute a series of focusing processes including a second focus adjustment process for achieving a focus state, and each process executes a CPU 110 and a focus adjustment program installed in the manufacturing apparatus 100 of the camera module M. This is realized by being executed by the arithmetic processing unit 120.

  As shown in FIG. 2, the device 1 of the present invention has a focus lens driving device 139 (corresponding to a driving device) that moves the focus lens FL in the optical axis direction in the first focus adjustment processing as shown in FIG. ) And a position detection unit 111 (position detection unit) that detects position information indicating the position of the focus lens FL every time the focus control unit 109 moves the focus lens FL. For each focus adjustment image stored in the image storage means 102, a first calculation means 121 for calculating a degree of focus indicating a focus state of the focus lens FL from the focus adjustment image, and a first calculation means 121, the degree of focus at different positions of the three or more focus lenses FL is obtained, and the obtained degree of focus is used to obtain the position. From the second calculation means 122 for obtaining an approximate curve indicating the relationship between the information and the degree of focus, and the approximate curve obtained by the second calculation means 122, optimum position information that is position information when the degree of focus is maximized is obtained. The driving control unit 109 controls the focus lens driving device 139 based on the optimum position information calculated by the third computing means 123, and the focus lens FL is located at the position indicated by the optimum position information. Is configured to move. In the present embodiment, the AD conversion unit 101 and the image storage unit 102 constitute an image acquisition unit.

  As shown in FIG. 2, the device 1 of the present invention acquires position information from the position detection unit 111 every time the focus lens FL is moved by the drive control unit 109 in the preprocessing, as shown in FIG. Position determining means 124 for determining whether or not the position of the focus lens FL is within the reference range based on the information is provided, and the drive control unit 109 performs position determination on the position of the focus lens FL in the position determination means 124 in the preprocessing. Until the focus lens driving device 139 is repeatedly controlled until it is determined that the position of the focus lens FL is within the reference range. One focus adjustment process is started.

  The device 1 according to the present invention has a configuration related to the second focus adjustment process. In the second focus adjustment process, each time the focus lens FL is moved by the drive control unit 109, the focus calculation is performed by the first calculation unit 121. The focus degree determination means 125 for determining whether or not the focus lens FL is in focus, and the focus degree and the focus degree obtained by the first calculation means 121 in the first focus adjustment processing, respectively. Based on the position information, it is determined whether or not the approximate curve can be calculated by the second calculating means 122, and when it is determined that the approximate curve cannot be calculated by the second calculating means 122, the second focus Focus processing switching means 126 for starting adjustment processing is provided, and the drive control unit 109 performs focus lens F in the second focus adjustment processing. It obtains a difference value of the focus degree after movement previous degree of focus and the movement, and is configured to set a driving direction and a unit moving distance of the focus lens drive device 139 based on the difference value.

  More specifically, in the present embodiment, the drive control unit 109 moves the focus lens FL by a predetermined first unit movement amount in the pre-processing, and moves the focus lens FL to the first unit in the first focus adjustment processing. It is configured to move by a second unit movement amount smaller than the movement amount. Similarly, in the second focus adjustment process, the drive control unit 109 moves the focus lens FL by a predetermined third unit movement amount when the focus degree is smaller than a preset reference value, and the focus degree is The focus lens FL is moved by a fourth unit movement amount smaller than the third unit movement amount when the reference value is equal to or greater than the reference value.

  In the present embodiment, the second calculation unit 122 calculates a second-order polynomial having the degree of focus as a dependent variable and the position variable indicating the position information as an independent variable.

<Processing procedure of the method of the present invention>
Next, the processing procedure of the method of the present invention will be described with reference to FIGS.

  Here, FIG. 3 shows an example of the processing procedure of the pre-processing and the first focus adjustment process in the method of the present invention, and FIG. 4 shows the relationship between the degree of focus and the position information in the first focus adjustment process. Yes. FIG. 5 shows an example of the processing procedure of the second focus adjustment process in the method of the present invention, and FIG. 6 shows the relationship between the degree of focus and the position information in the second focus adjustment process. The position information of the present embodiment will be described using the tightening angle θ corresponding to the distance between the imaging element and the focus lens FL as the position of the focus lens FL with respect to the imaging element.

  First, the manufacturing apparatus 100 of the camera module M controls the transport device 133 by the transport control unit 103, transports the camera module M to the attachment position of the focus adjustment jig 138, and is controlled by the focus adjustment jig control unit. A focus adjustment jig 138 is attached using information from the licensor. At this time, the camera module M is in an underfocus state. Further, the illumination device 135 is set to an appropriate brightness under the control of the illumination control unit 105, and the inspection device 136 performs DC inspection, dust spot inspection, resolution inspection, and the like under the control of the inspection control unit 106. When the execution request for the focusing process is input via the external input device 134, the inventive apparatus 1 starts the focusing process.

As shown in FIG. 3, the device 1 of the present invention first initializes various variables used in the preprocessing and the first focus adjustment processing in the RAM 113 and acquires various parameters used in the preprocessing and the first focus adjustment processing. (Step # 100). More specifically, here, the value of a variable that stores the number of times of calculation of the degree of focus in the first focus adjustment process described later is initialized to zero. The parameter as to obtain the reference range [Delta] [theta], the focus lens second unit moving distance [Delta] [theta] ₂ in the first unit moving distance [Delta] [theta] ₁ and the first focus adjustment process in the pretreatment of the FL used in the pretreatment. In the present embodiment, it is assumed that these parameters are stored in the ROM 112, but the parameters may be set from the external input device 134.

<Processing procedure of the method of the present invention: pretreatment>
In pre-processing (step # 101, pre-processing step), the device 1 of the present invention controls the focus lens driving device 139 by the drive control unit 109 to move the focus lens FL in the optical axis direction (step # 102, second processing). Lens driving process). Specifically, immediately after the camera module M is attached to the focus adjustment jig 138, it is in an underfocus state, and as shown in FIG. 4B, the focus lens FL is rotated clockwise with respect to the lens holder LH. The first unit movement amount Δθ _{1 is} sequentially tightened in the direction.

Subsequently, the device 1 of the present invention detects position information (tightening angle θ) of the moved focus lens FL by the position detector 111 (step # 103, second position detection step). The position determination unit 124 determines whether or not the tightening angle θ _k (k is an arbitrary integer) detected by the position detection unit 111 is within the reference range Δθ (step # 104, position determination step), and the reference range If it is outside Δθ (“NO” branch at step # 104), the process proceeds to step # 102. When the tightening angle θ _k is within the reference range Δθ (“YES” branch at step # 104), the first focus adjustment process is executed.

<Processing Procedure of the Method of the Present Invention: First Focus Adjustment Process>
In the first focus adjustment process (step # 110), the device 1 of the present invention controls the focus lens driving device 139 by the drive control unit 109 to move the focus lens FL in the optical axis direction (step # 111, first lens). Driving process). Here, as shown in FIG. 4B, the focus lens FL is sequentially tightened by the second unit movement amount Δθ _{2 in the} clockwise direction with respect to the lens holder LH. Here, it is assumed that the second unit movement amount Δθ ₂ is set more finely than the first unit movement amount Δθ ₁ in the preprocessing. However, depending on the configuration of the camera module M, the same unit movement amount is assumed. An amount may be used.

Subsequently, the device 1 of the present invention, as the position information of the focus lens FL after moving the position detection unit 111 detects the tightening angle theta _k (step # 112, the first position detection step). Subsequently, the device 1 of the present invention acquires a focus adjustment image from the image sensor of the camera module M (step # 113, image acquisition process). Specifically, image data of the image sensor transferred by the socket board 132 is digitally converted by the AD conversion unit 101, and the digitally converted focus adjustment image is stored in the image storage unit 102.

  Furthermore, in the present embodiment, the first calculation unit 121 calculates the degree of focus indicating the focus state of the focus lens FL for each focus adjustment image using the focus adjustment image stored in the image storage unit 102. (Step # 114, first calculation step). The calculated focus degree F is stored in the RAM 113 in association with the position information.

In the present embodiment, in order to calculate an approximate curve, the in-focus degrees for five different positions are acquired. The device 1 of the present invention executes the calculation preparation process of step # 111 to step # 113 and the first calculation process of step # 114 five times, and five different positions θ _h (in the reference range Δθ shown in FIG. The degree of focus F corresponding to each of h = i to i + 4) is acquired (step # 115).

  Subsequently, when the device 1 of the present invention acquires the in-focus degrees for the five different positions ("YES" branch in step # 115), it corresponds to each of the in-focus degree and the in-focus degree calculated in the first calculation step. Based on the position information to be determined, it is determined whether or not an approximate curve indicating the relationship between the position information and the degree of focus can be calculated (step # 116).

  Here, FIG. 4A shows an example of the relationship between the degree of focus and position information when the approximate curve can be calculated, and FIG. 4C shows the case where the approximate curve cannot be calculated. An example of the relationship between the degree of focus and position information is shown. In FIG. 4A, the peak value is near the approximate center of the reference range Δθ. In such a case, an approximate curve can be calculated. On the other hand, as shown in FIG. 4 (c), the degree of focus obtained in the first calculation step is approximated due to manufacturing variations such as tightening when the camera module M is connected to the focus adjustment jig 138. In some cases, the peak value is difficult to calculate (the peak value cannot be calculated or the accuracy of the peak value is very low). .

  In the present embodiment, in order to determine whether or not the approximate curve can be derived, the second calculation means 122 uses the five obtained degrees of focus as the focus F as a dependent variable (object variable), and as a position variable. A quadratic polynomial having the tightening angle θ as an independent variable (explanatory variable) is calculated (step # 117, second calculation step). This polynomial is expressed by the following equation (1).

[Equation 1]
F (θ) = a ₂ θ ² + a ₁ θ + a ₀

The coefficients a ₂ , a ₁ , and a ₀ are calculated by regression analysis using the degree of focus F at five different positions θ _h (h = i to i + 4) in FIG. Here, FIG. 4C shows an example of a case where it is difficult to derive an approximate curve capable of calculating a peak value as described above. In this case, the five in-focus degrees F are arranged on a substantially straight line instead of an approximate curve, and the value of the coefficient a ₂ shown in Equation 1 is as close to 0 as possible.

Therefore, in the present embodiment, the focus processing switching unit 126 determines that the approximate curve cannot be calculated when the value of the coefficient a ₂ shown in Equation 1 is smaller than the preset determination value, and the first focus The adjustment process is terminated and the second focus adjustment process is started (step # 120, focus process switching step). In the present embodiment, the determination value R uses a value stored in advance in the ROM 112, but may be configured to be set from the external input device 134 or the like.

  In step # 116 shown in FIG. 3, when the focus process switching unit 126 determines that the approximate curve can be calculated (“YES” branch in step # 116), the third calculation unit 123 sets the second calculation unit 122. Is obtained from the approximate curve derived from the optimal position information, which is position information when the degree of focus is maximized (step # 117, third calculation step). Specifically, in FIG. 4A, the optimum position information θmax when the peak value Fmax is obtained is obtained by the following formula 2.

[Equation 2]
θmax = −a ₁ / (2 × a ₂ )

  The device 1 of the present invention stores the optimum position information θmax calculated by the third calculation means 123 in the RAM 113, and further controls the focus lens driving device 139 by the drive control unit 109 to tighten the focus lens FL on the lens holder LH. The focus lens FL is moved so that the insertion angle becomes θmax (step # 118, lens adjustment step), and the first focus adjustment process is terminated. As described above, by executing the first focus adjustment process, the focus lens FL can be moved to a position where the degree of focus takes the maximum value Fmax, that is, theoretically, the best focus position.

<Processing Procedure of Method of Present Invention: Second Focus Adjustment Process>
In step # 116 of the first focus adjustment process, when the focus process switching unit 126 determines that the approximate curve cannot be calculated ("NO" branch in step # 116), the device 1 of the present invention performs the first focus adjustment. The process is terminated and the second focus adjustment process is started (step # 120, focus process switching step).

In the second focus adjustment process, the device 1 of the present invention initializes various variables used in the second focus adjustment process and acquires various parameters used in the second focus adjustment process in the RAM 113 as shown in FIG. (Step # 121). More specifically, here, the maximum value Fmax of the degree of focus and the value of the number of peak crossings C, which will be described later, are initialized to zero. Further, as the parameters, the third unit movement amount Δθ ₃ and the fourth unit movement amount Δθ ₄ of the focus lens FL, and the reference value Fb of the in-focus level that is a determination reference for switching the unit movement amount are acquired. In the present embodiment, it is assumed that these parameters are stored in the ROM 112, but the parameters may be set from the external input device 134.

Subsequently, the device 1 of the present invention controls the focus lens driving device 139 by the drive control unit 109 to move the focus lens FL in the optical axis direction (step # 122). Specifically, in the present embodiment, as shown in FIG. 6B, the focus lens FL is sequentially tightened by Δθ _{3 in the} clockwise direction with respect to the lens holder LH.

  Subsequently, the device 1 of the present invention detects the tightening angle θ as the position information of the focus lens FL after movement by the position detection unit 111 (step # 123), and acquires the focus adjustment image from the image sensor of the camera module M. In step # 124, the first calculation means calculates the degree of focus (step # 125). If the in-focus degree F calculated by the first calculating means is smaller than the in-focus degree reference value Fb ("NO" branch in step # 126), the inventive device 1 proceeds to step # 122.

In step # 126, when the in-focus degree F calculated by the first calculating means is larger than the in-focus degree reference value Fb ("YES" branch in step # 126), the unit movement amount of the focus lens driving device 139 is determined. Is set to Δθ ₄ finer than Δθ ₃ (step # 127).

Subsequently, the device 1 of the present invention controls the focus lens driving device 139 by the drive control unit 109 to move the focus lens FL in the optical axis direction (step # 128). Specifically, here, as shown in FIG. 6B, the focus lens FL is sequentially tightened by the unit movement amount Δθ _{4 in the} clockwise direction with respect to the lens holder LH. Furthermore, the device 1 of the present invention detects the tightening angle θ _k as the position information of the focus lens FL after the movement by the position detection unit 111 (step # 129), and outputs the focus adjustment image from the image sensor of the camera module M. Obtain (step # 130).

Subsequently, the device 1 of the present invention calculates the degree of focus F by the first calculation means (step # 131). Further, when the focus degree determination means 125 has a value of the maximum focus degree Fmax stored in the RAM 113 smaller than the calculated focus degree F, the maximum value Fmax of the focus degree in the RAM 113 is determined. It replaces with the calculated value of the focus degree F, and the position information at this time, that is, the tightening angle θ _k (θmax) is stored in the RAM 113 together.

Subsequently, in the device 1 of the present invention, the drive control unit 109 obtains a difference value between the focus degree before the focus lens FL is moved by the focus lens drive device 139 and the focus degree after the movement, and the focus lens based on the difference value. The driving direction and unit movement amount of the driving device 139 are set (step # 131, third lens driving step). Here, the focus degree F ′ _k−1 corresponding to the previous tightening angle θ _k−1 stored in the ROM 112 is acquired, and the difference value from the focus degree F ′ _k after the movement is obtained. If the difference value is a positive value, it is determined that the direction is in the just focus direction, and the settings of the drive direction and unit movement amount are not changed. On the other hand, when the difference value takes a negative value, it is determined that the state of just focus has been exceeded, the value of the number of times C is exceeded by 1 (step # 133), and the driving direction is determined. Note that the driving direction may be reversed when the difference value continuously becomes a negative value a predetermined number of times or more.

More specifically, for example, as shown in FIG. 6A, when the focus lens FL is moved from the tightening angle θ ′ _i to the tightening angle θ ′ _{i + 1} , the focus degree F ′ _i before the movement is obtained. The difference value between the in-focus degree F ′ _{i + 1} after the movement is a positive value. At this time, since the focus lens FL is moving from P ′ _i to P ′ _{i + 1} , that is, in the direction of just focus, the setting of the drive direction and the unit movement amount is not changed. On the other hand, as shown in FIG. 6A, when the focus lens FL is moved from the tightening angle θ ′ _{i + 2} to the tightening angle θ ′ _{i + 3} , the in-focus degree F ′ _{i + 2} (Fmax) before the movement is obtained. The difference value of the focus degree F ′ _{i + 1} after the movement is a negative value. At this time, since the focus lens FL moves in the direction from P ′ _{i + 2} to P ′ _{i + 3} , that is, in the direction opposite to the just focus direction, the drive direction is reversed and the unit movement amount Δθ ₄ Reset the value of to a smaller value.

  Subsequently, the device 1 according to the present invention compares the number C of peak crossings with a preset determination number (for example, five times) (step # 134, in-focus degree determination step). In step # 134, "NO" branch), the process proceeds to step # 128. In step # 134, when the peak crossing count C is equal to or greater than the determination count ("YES" branch in step # 134), the focus degree determination means 125 determines that the focus lens FL is in focus. Then, the maximum value Fmax of the degree of focus and the tightening angle θmax at this time are acquired from the RAM 113.

  The device 1 of the present invention controls the focus lens driving device 139 by the drive control unit 109 to move the focus lens FL so that the tightening angle of the focus lens FL with respect to the lens holder LH becomes θmax (step # 135). .

In the present embodiment, in the second focus adjustment process, the reference value Fb of the in-focus degree is set, and the coarse unit movement amount Δθ ₃ until the reference value Fb is exceeded, that is, until the state is close to the just focus state. After the focus lens FL is moved by the step of FIG. 5B, the focus lens FL is moved by the unit movement amount Δθ ₄ smaller than the unit movement amount Δθ ₃ after the reference value Fb is exceeded and the state is close to the just focus state. The time required for the second focus adjustment process can be reduced without degrading the quality as compared with the focus adjustment by the focus.

<Another embodiment>
<1> In the above embodiment, the case where the device 1 of the present invention is applied to the manufacturing apparatus 100 for the camera module M has been described, but the present invention is not limited to this. You may mount as an autofocus function with respect to the apparatus which mounts the camera module M with which the processing capacity of a central processing unit and the storage capacity of an image memory | storage means have margins.

  <2> In the above embodiment, in the first focus adjustment process (step # 110), the degree of focus is calculated every time the focus adjustment image is acquired. However, the present invention is not limited to this. The calculation of the degree of focus (step # 114) may be performed simultaneously with the movement of the focus lens FL for acquiring the next focus adjustment image (step # 111). Further, the position detection of the focus lens FL (step # 112) may also be performed simultaneously with the capture of the focus adjustment image (step # 113) and the calculation of the degree of focus (step # 114).

  <3> In the above embodiment, the degree of focus F when the position of the focus lens FL is within the reference range Δθ is used for calculating the approximate curve, but the present invention is not limited to this. For example, when the focus lens FL is moved from the underfocus state (initial state) to the just focus side, a fixed number (for example, five) is obtained after the focus degree F becomes equal to or higher than a predetermined reference focus degree Fb. ) May be obtained.

  Further, by combining the reference range Δθ and the reference focus degree Fb, as shown in FIG. 7, the position of the focus lens FL is within the reference range Δθ, and the focus degree F is a predetermined reference focus degree Fb. When it is above, you may comprise so that it may be used for calculation of an approximated curve.

  <4> Further, in the above-described embodiment, in the first focus adjustment process (step # 110 in FIG. 3), the degrees of focus at five different positions are used for calculating the approximate curve. However, the present invention is not limited to this. In consideration of the use of the camera module M, the focus adjustment accuracy, the calculation time of the focus degree, the production quantity of the camera module M in the manufacturing apparatus, and the like, the camera module M is set to use an appropriate number of focus degrees.

<5> Further, when it is determined in the first focus adjustment process (step # 110) that the approximate curve can be derived (step # 116), it is determined that the approximate curve cannot be derived, as shown in FIG. The focus degree F at the tightening angle θ _r (r = i + 5 or more integer) closer to the overfocus side than θ _{i + 4} is added to the calculation of the approximate curve (the reference range Δθ is expanded to Δθ ′). Also good.

  Specifically, in the first focus adjustment process (step # 110), as shown in FIG. 8, the number X of focus degrees F used for calculating the approximate curve is set (for example, X = 5), and X When one or more focus degrees F are calculated (steps # 115 and # 140), it is determined whether or not an approximate curve can be derived (step # 116). If it is determined that the approximate curve can be derived ("YES" branch in step # 116), the process proceeds to step # 117.

  If it is determined that the approximate curve cannot be derived ("NO" branch at step # 116), the number of approximate curve derivation determinations is counted. Subsequently, the device 1 of the present invention determines the number of derivation impossible determinations, and when the number of derivation determinations is less than a predetermined number ("NO" branch in step # 142), the degree of focus F used to calculate the approximate curve. The number X is increased (step # 143), and the process proceeds to step # 111. As a result, the focus degree F at the tightening angle θ closer to the overfocus side can be added to the calculation of the approximate curve. In step # 142, if the number of derivation impossible determinations is equal to or greater than a certain number ("YES" branch in step # 142), the second focus process (step # 120) is executed.

  If executed in this way, the probability of performing the focus adjustment by the first focus adjustment process having a relatively short processing time is increased, and therefore it is possible to further reduce the time required for adjusting the focus of the camera module M. Become.

Schematic diagram showing a partial schematic configuration example of a camera module manufacturing apparatus to which the focus adjustment apparatus according to the present invention is applied. Schematic partial block diagram showing a schematic configuration example of a portion related to the focusing processing of the focus adjustment device and its peripheral devices according to the present invention 7 is a flowchart showing an example of a processing procedure of the focus adjustment method according to the present invention. Explanatory drawing which shows the relationship between a focus degree and a position in the 1st focus adjustment process of the focus adjustment apparatus and focus adjustment method which concern on this invention. 7 is a flowchart showing an example of a processing procedure of the focus adjustment method according to the present invention. Explanatory drawing which shows the relationship between a focus degree and a position in the 2nd focus adjustment process of the focus adjustment apparatus and focus adjustment method which concern on this invention. Explanatory drawing which shows the relationship between a focus degree and a position in 1st focus adjustment processing in another embodiment of the focus adjustment apparatus and focus adjustment method which concern on this invention. The flowchart which shows an example of the process sequence in another embodiment of the focus adjustment method which concerns on this invention. Explanatory drawing which shows the relationship between a focus degree and a position in 1st focus adjustment processing in another embodiment of the focus adjustment apparatus and focus adjustment method which concern on this invention. The flowchart which shows the process sequence of the automatic focusing process of the focus adjustment apparatus which concerns on a prior art. Schematic schematic diagram explaining each state of the focus lens in the automatic focusing process of the focus adjustment device according to the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Focus adjustment apparatus 100 Camera module manufacturing apparatus 101 AD conversion part 102 Image storage means 103 Conveyance control part 104 External I / F
105 Illumination control unit 106 Inspection control unit 107 Display control unit 108 Jig control unit for focus adjustment 109 Drive control unit (drive control means)
110 CPU
111 Position detection unit (position detection means)
112 ROM
113 RAM
120 calculation processing unit 121 first calculation unit 122 second calculation unit 123 third calculation unit 124 position determination unit 125 focusing degree determination unit 126 focus processing switching unit 130 image display device for adjustment 131 image 132 for adjustment socket board 133 transport device 134 External input device 135 Illumination device 136 Inspection device 137 CRT
138 Focus Adjustment Jig 139 Focus Lens Drive Device (Drive Device)
140 Line sensor M Camera module LH Lens holder FL Focus lens

Claims (8)

A focus adjustment device used for focus adjustment of a camera module at the time of manufacture,
Drive control means for controlling a drive device for moving the focus lens in the optical axis direction in the first focus adjustment processing for bringing the focus lens of the camera module into focus with respect to the image sensor of the camera module;
Position detecting means for detecting position information indicating the position of the focus lens each time the focus lens is moved by the drive control means;
Image acquisition means for acquiring a focus adjustment image from the image sensor each time the focus lens is moved by the drive control means;
First calculation means for calculating a focus degree indicating a focus state of the focus lens from the focus adjustment image for each focus adjustment image acquired by the image acquisition means;
Approximation indicating the relationship between the position information and the in-focus degree using the in-focus degrees acquired from the first calculation means, respectively, for the in-focus degrees at three or more different positions of the focus lens. A second calculating means for obtaining a curve;
Third computing means for obtaining optimum position information, which is the position information when the degree of focus is maximized, from the approximate curve obtained by the second computing means;
In a pre-process for adjusting a position of the focus lens within the reference range before the execution of the first focus adjustment process, using a part of the drive range of the focus lens capable of acquiring an image from the image sensor as a reference range. Each time the focus lens is moved by the drive control unit, the position information is acquired from the position detection unit, and it is determined whether the position of the focus lens is within the reference range based on the acquired position information. A position determination means,
The drive control means is configured to control the drive device based on the optimum position information calculated by the third calculation means, and to move the focus lens to a position indicated by the optimum position information;
The drive control unit is further configured to repeatedly control the drive unit until the position determination unit determines that the position of the focus lens is within the reference range in the preprocessing, When the determination unit determines that the position of the focus lens is within the reference range, the first focus adjustment process is started ,
The reference range is defined in advance in a range including an optimum position where the degree of focus is maximum,
In the first focus adjustment process, the image acquisition unit acquires the focus adjustment image when the position indicated by the position information acquired by the position detection unit is within the reference range,
In the first focus adjustment process, the driving means performs the approximation by the second computing means based on the focus information obtained by the first computing means and the position information corresponding to each of the focus degrees. It is determined whether or not a curve can be calculated, and when it is determined that the approximate curve cannot be calculated by the second calculation means, the reference range is expanded to a predetermined range set in advance. A characteristic focus adjustment device. In the second focus adjustment process for bringing the focus lens into an in-focus state, the drive control means obtains a difference value between the focus degree before the focus lens moves and the focus degree after the move, and the difference Configured to set the driving direction and unit movement amount of the driving device based on the value,
Each time the focus lens is moved by the drive control means in the second focus adjustment process, it is determined whether or not the focus lens is in focus based on the degree of focus calculated by the first calculation means. A degree-of-focus determination means;
In the first focus adjustment process, the approximate curve can be calculated by the second calculation means based on the focus degree obtained by the first calculation means and the position information corresponding to each of the focus degrees. And a focus process switching unit that starts the second focus adjustment process when it is determined that the approximate curve cannot be calculated by the second calculation unit. The focus adjustment apparatus according to claim 1. Said second calculation means, wherein the focus level as the dependent variable, Focus of claim 1 or 2, characterized in that to calculate the second or higher polynomial as an independent variable the position variable indicating the position information Adjustment device. The drive control means moves the focus lens by a predetermined first unit movement amount in the preprocessing, and moves the focus lens by a second unit movement smaller than the first unit movement amount in the first focus adjustment processing. The focus adjustment apparatus according to claim 1 , wherein the focus adjustment apparatus is moved by an amount. A focus adjustment method used for focus adjustment of a camera module at the time of manufacture,
In the first focus adjustment step for bringing the focus lens of the camera module into focus with respect to the image sensor of the camera module,
A first lens driving step for controlling a driving device for moving the focus lens in the optical axis direction;
A first position detecting step for detecting position information indicating the position of the focus lens each time the first lens driving step is performed;
Each time the first lens driving step is performed, an image acquisition step of acquiring a focus adjustment image from the imaging device is repeatedly executed three or more times.
A first calculation step of calculating a focus degree indicating a focus state of the focus lens from the focus adjustment image for each of the focus adjustment images acquired in the image acquisition step;
A second calculation step for obtaining an approximate curve indicating a relationship between the position information and the focus degree using the focus degree calculated in the first calculation step;
A third calculation step for obtaining optimum position information, which is the position information when the degree of focus is maximized, from the approximate curve obtained in the second calculation step;
A lens adjustment step of controlling the driving device based on the optimum position information obtained in the third calculation step and moving the focus lens to a position indicated by the optimum position information,
In a pre-processing step of setting a part of the driving range of the focus lens capable of acquiring an image from the image sensor as a reference range, and adjusting the position of the focus lens within the reference range before executing the first focus adjustment process ,
A second lens driving step for controlling the driving device;
A second position detecting step of detecting the position information of the focus lens each time the second lens driving step is performed;
A position determination step for determining whether or not the position of the focus lens is within a predetermined reference range set in advance based on the position information detected in the second position detection step. ,
The pre-processing step is repeatedly executed until the position determination step determines that the position of the focus lens is within the reference range before the first focus adjustment step .
The reference range is defined in advance in a range including an optimum position where the degree of focus is maximum,
In the image acquisition step, in the first focus adjustment step, when the position indicated by the position information acquired in the first position detection step is within the reference range, the focus adjustment image is acquired,
In the second calculation step, before derivation of the approximate curve, the second calculation step is performed based on the position information corresponding to the focus degree and the focus degree obtained in the first calculation step. It is determined whether the approximate curve can be calculated, and when it is determined that the approximate curve cannot be calculated, the reference range is expanded to a predetermined range set in advance Adjustment method. Each time the focus lens is moved by the driving device, the first calculation step is executed to obtain the degree of focus after the movement, and the degree of focus before the focus lens is moved by the driving device and the degree of focus after the movement. A third lens driving step of obtaining a difference value of the degree of focus and setting a driving direction and a unit movement amount of the driving device based on the difference value;
A second focus adjustment step comprising: a focus degree determination step for determining whether or not the focus lens is in focus based on the focus degree calculated in the third lens driving step can be executed. Configured,
Before executing the second calculation step of the first focus adjustment step, based on the position information corresponding to each of the focus degree and the focus degree calculated in the first calculation step, the second It is determined whether the calculation of the approximate curve in the calculation step is possible, and when it is determined that the calculation of the approximate curve in the second calculation step is not possible, the focus for starting the second focus adjustment process 6. The focus adjustment method according to claim 5 , wherein the focus adjustment method is performed with a process switching step. 7. The focus according to claim 5, wherein in the second calculation step, a second-order or higher-order polynomial is calculated with the degree of focus as a dependent variable and the position variable indicating the position information as an independent variable. Adjustment method. The second lens driving step moves the focus lens by a predetermined first unit movement amount,
The focus adjustment method according to claim 5 , wherein the first lens driving step moves the focus lens by a second unit movement amount smaller than the first unit movement amount.

Images