TWI774418B - Camera module, focus adjustment system and focusing method - Google Patents

Abstract

A camera module, a focus adjustment system, and a focusing method are provided. The tested data and to-be-test data are obtained. The tested data includes calibrated focus position, corresponding modulation transfer function (MTF) peak, and corresponding tested ratio of the tested camera module. The to-be-test data includes motor position, corresponding MTF value, and to-be-test ratio. Each calibrated focus position means that the location where the motor drives the lens to move to has the MTF peak. The ratio is related to the area of a reference region in the image. The variation relation is determined according to the calibrated focus position and corresponding to-be-test ratio. The variation relation is a ratio of lens shifting variation and ratio variation. The next motor position is determined according to the to-be-test data and the variation relation.

Description

Camera module, focus adjustment system and focus method

The present invention relates to a focusing technology, and more particularly, to a camera module, a focusing adjustment system and a focusing method.

Generally speaking, the relatively clear range of the image before and after the focus point of the camera is called the depth of field (Depth of Field, DoF). In optical imaging, especially video or photography, the depth of field is the range of distances that can be clearly imaged in space. It's worth noting that a camera's lens can only focus light to a certain distance, and moving away from the focus point will cause the image to gradually blur. However, at a certain distance, the blur of the image is imperceptible to the naked eye. This distance is called the depth of field. Figure 1 is a schematic diagram of the depth of field DoF of camera C. The imaging of the object O at the depth of field DoF is relatively clear. Also, when the focus is set at the hyperfocal distance, the depth of field extends from half the hyperfocal distance to infinity, which is the maximum depth of field for a fixed f-stop. Before the camera leaves the factory, it is necessary to find the best clear point (or quasi-focus) of its imaging.

It is worth noting that there are many variables during the assembly phase of the lens. For example, the baking time and temperature of the dispensing operation, the flatness of the circuit board, and the positioning center of the Surface-Mount Technology (SMT), etc. These variables may cause the corresponding quasi-focus positions of the lenses produced in the same batch to be different after being assembled into the camera module.

However, the process of finding the right focus is now long, which affects the production efficiency of the overall production line. For example, the existing focusing method needs to use two stages of focusing: one is a coarse adjustment stage and the other is a fine adjustment stage. The disadvantage of two-stage focusing is that the parameters set by the two cannot be controlled. For example, in the fine adjustment stage, the focus adjustment value related to the coarse adjustment stage cannot be obtained, and further optimization actions cannot be performed. Also, using two-stage focusing will take too much time.

In view of this, embodiments of the present invention provide a camera module, a focus adjustment system, and a focus method, which refer to the measured data of the measured focus, so as to improve the focus speed.

The focusing method of the embodiment of the present invention includes (but is not limited to) the following steps: obtaining measured data and to-be-measured data. The measured data includes the focal position of one or more measured camera modules, the corresponding Modulation Transfer Function (MTF) peak value and the corresponding measured ratio value. The data to be tested includes the motor position of the camera module to be tested, the corresponding modulation transfer function value, and the corresponding proportional value to be tested. Each focus position means that there is a corresponding peak value of the modulation transfer function at the position to which the motor of the camera module under test drives the lens displacement. The measured scale value and the to-be-measured scale value are related to the area of the reference region in the captured image. The variation relationship is determined according to the focal positions of the tested camera modules in the tested data and the corresponding measured scale values. This change is the ratio of the lens shift change to the scale value change. The next motor position of the camera module to be tested is determined according to the data to be tested and the changing relationship.

The focus adjustment system of the embodiment of the present invention includes (but is not limited to) a processor. The processor is configured to obtain the measured data and the data to be measured, determine the change relationship according to the focus positions of the measured camera modules in the measured data and the corresponding measured scale values, and determine the change relationship according to the data to be measured and the change relationship. Measure the next motor position of the camera module. The measured data includes the focal position of one or more measured camera modules, the corresponding peak value of the modulation transfer function, and the corresponding measured ratio value. The data to be tested includes the motor position of the camera module to be tested, the corresponding modulation transfer function value, and the corresponding proportional value to be tested. Each focus position means that there is a corresponding peak value of the modulation transfer function at the position to which the motor of the camera module under test drives the lens displacement. The measured scale value and the to-be-measured scale value are related to the area of the reference region in the captured image. The change relationship is the ratio of the lens shift change to the scale value change.

The camera module of the embodiment of the present invention includes (but is not limited to) a lens, a motor, a motor driving circuit, an image sensor, and a processor. The motor is coupled to the lens and used to drive the lens to move. The motor driving circuit is coupled to the motor and used to control the motor. The image capturing device is used for capturing images. The processor is coupled to the motor driving circuit and the image sensor. The processor is also configured to obtain the measured data and the data to be measured, determine the change relationship according to the focus positions of the measured camera modules in the measured data and the corresponding measured scale values, and determine the relationship between the data to be measured and the change The next motor position of the camera module to be tested. The measured data includes the focal position of one or more measured camera modules, the corresponding peak value of the modulation transfer function, and the corresponding measured ratio value. The data to be tested includes the motor position of the camera module to be tested, the corresponding modulation transfer function value, and the corresponding proportional value to be tested. Each focus position means that there is a corresponding peak value of the modulation transfer function at the position to which the motor of the camera module under test drives the lens displacement. The measured scale value and the to-be-measured scale value are related to the area of the reference region in the captured image. The change relationship is the ratio of the lens shift change to the scale value change.

Based on the above, according to the camera module, the focus adjustment system, and the focus method according to the embodiments of the present invention, the camera module to be tested can be determined based on the change relationship between the focal position of the measured data of the measured camera module and the area of the reference area in the image. Motor movement position of the group. In this way, the number of times of repeatedly moving the lens and measuring the value can be reduced, thereby improving the production efficiency of the camera module.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, the following embodiments are given and described in detail with the accompanying drawings as follows.

FIG. 2 is a block diagram of components of the focus adjustment system 1 according to an embodiment of the present invention. Referring to FIG. 2 , the focus adjustment system 1 includes (but is not limited to) a computing device 50 and one or more camera modules 100 .

The computing device 50 may be an electronic device such as a desktop computer, a notebook computer, a server, a smart phone, and a tablet computer. The computing device 50 includes, but is not limited to, a processor 59 .

The processor 59 can be a central processing unit (CPU), or other programmable general-purpose or special-purpose microprocessors (Microprocessors), digital signal processors (DSPs), programmable controllers, Application-Specific Integrated Circuit (ASIC) or other similar components or a combination of the above components. In one embodiment, the processor 59 is used to execute all or part of the operations of the computing device 50 .

The camera module 100 includes (but is not limited to) a lens 110 , a motor 130 , a motor driving circuit 150 , an image sensor 170 and a processor 190 . The camera module 100 can be used in mobile phones, tablet computers, notebook computers, monitors or other types of cameras.

The lens 110 may include one or more lenses, and the lenses may be made of plastic, glass or other materials. It should be noted that the embodiment of the present invention does not limit the focal length, angle of view or other specifications of the lens 110 .

The motor 130 may be a voice coil motor (VCM), a piezoelectric (piezoelectric) motor, a step motor, an ultrasonic motor, or other types of motors. The motor 130 is coupled to the lens 110 , and the motor 130 is used to drive the lens or lens group in the lens 110 to displace/move.

The motor driving circuit 150 may be a digital-to-analog converter (DAC), an analog driver, or other drivers supported by the motor 130 . The motor driving circuit 150 is coupled to the motor 130 , and the motor driving circuit 150 is used to control the motor 130 and then control the movement of the lens 110 . For example, by changing the current output from the motor driving circuit 150 to the motor 130 , the position of the lens 110 relative to the image sensor 170 will be changed.

The image sensor 170 may be a Charge-Coupled Device (CCD), a Complementary Metal-Oxide-Semiconductor (CMOS), or other photosensitive elements. In one embodiment, the image sensor 170 is used to obtain sensing data related to light intensity in response to the light incident through the lens 110 . That is, images are captured through the pixel array.

The processor 190 is coupled to the motor driving circuit 150 and the image sensor 170 . The processor 59 can be a central processing unit, or other programmable general-purpose or special-purpose microprocessors, digital signal processors, image signal processors (ISP), programmable controllers, special Application of integrated circuits or other similar elements or combinations of the above elements. In one embodiment, the processor 190 is used to execute all or part of the operations of the camera module 100 . For example, the processor 190 transmits a signal to the motor driving circuit 150 based on the sensing data (eg, the captured image) of the image sensor 170 , so that the motor 130 drives the lens 110 to move.

In one embodiment, the computing device 50 and the camera module 100 are integrated into a single device. For example, processor 59 and processor 190 are the same or both configured for different functions. In another embodiment, the computing device 50 and the camera module 100 can communicate with each other through wired or wireless communication (eg, Universal Serial Bus (USB), I2C, or Wi-Fi).

Hereinafter, the method described in the embodiment of the present invention will be described in conjunction with various components and modules in the focus adjustment system 1 . Each process of the method can be adjusted according to the implementation situation, and is not limited to this.

FIG. 3 is a flowchart of a focusing method according to an embodiment of the present invention. Referring to FIG. 3, the processor 59 or the processor 190 can obtain the measured data and the data to be measured (step S610). Specifically, the measured data includes the focal position and modulation transfer function (Modulation Transfer Function, MTF) peak value of one or more measured camera modules, and the corresponding measured ratio values.

The higher the modulation transfer function value is, the clearer the result of imaging through the lens 110 is. Therefore, the motor position (corresponding to the distance of the lens 110 relative to the image sensor 170 ) corresponding to the peak value of the modulation transfer function (ie, the highest value of the modulation transfer function) can be used as the focus position. In other words, the on-focus position means that there is a corresponding modulation transfer function peak at the position to which the motor 130 of the camera module under test drives the lens 110 to move. The modulation transfer function peak value represents the highest value of the modulation transfer function corresponding to all motor positions of the camera module under test. The measured camera module refers to that a certain camera module 100 has been measured and found in advance to find the modulation transfer function peak and its corresponding quasi-focus position. It should be noted that the embodiment of the present invention does not limit the number of camera modules that have been tested.

The modulation transfer function value is, for example, the ratio of the difference between the maximum light intensity and the minimum light intensity measured in the image captured by the image sensor 170 and the sum of the two, but not limited thereto.

FIG. 4 is a flow chart of obtaining measured data according to an embodiment of the present invention. Referring to FIG. 4 , for the camera module 100 that is about to be the tested camera module, the processor 59 or the processor 190 can determine whether the modulation transfer function value of the tested camera module reaches the fine tuning threshold (step S410 ). Generally speaking, the focusing process is divided into coarse adjustment and fine adjustment stages. The MTF value in the fine tuning stage should be closer to the MTF peak value than the MTF value in the coarse tuning stage. The fine-tuning threshold can be a specific percentage (eg, percent) of a statistical indicator (eg, mean, median, or mode) based on the modulation transfer function peak (completed focus process) of other tested camera modules Eighty, seventy-five, etc.), or based on a rule of thumb or past data from the relevant person.

If the modulation transfer function value of the tested camera module does not reach the fine tuning threshold, it has not entered the fine tuning stage (ie, remains in the coarse tuning stage), and the processor 59 or the processor 190 can be driven by the motor driving circuit 150 The motor 130 changes the position of the lens 110 accordingly. That is, the processor 59 controls the motor 130 to drive the lens 110 according to the next motor position. In the coarse adjustment stage, the next motor position may be a position away from the current motor position by a specific distance (ie, the determined moving distance), and may be changed according to actual needs (step S420 ). In some embodiments, the moving distance of the motor 130 may also be related to a mathematical function based on the current modulation transfer function value, but is not limited thereto. Steps S410 and S420 may be repeated until the modulation transfer function value of the camera module 100 reaches (eg, is greater than or equal to) the fine tuning threshold.

If the modulation transfer function value of the measured camera module does not reach the fine tuning threshold, the fine tuning stage is entered, and the processor 59 or the processor 190 can still drive the motor 130 through the motor driving circuit 150 and change the lens 110 accordingly. Location. In addition, the processor 59 or the processor 190 can record the modulation transfer function value corresponding to each motor position in the fine adjustment stage and the corresponding measured ratio value.

The measured scale value is related to the area of the reference region in the image captured by the image sensor 170 . For example, FIG. 5 is a schematic diagram of determining a ratio value according to an embodiment of the present invention. Referring to FIG. 5 , it is assumed that the target position to be photographed by the lens module 100 has a target pattern (take a black square as an example, but other shapes or colors are also possible, and not limited thereto). The image captured by the image sensor 170 includes the target pattern. The processor 59 or the processor 190 can use the target pattern in the image as the reference area RA, and determine the area of the reference area RA in the image (for example, the number of pixels occupied in the image, the ratio of the number, or the unit of length). metering). The scale value is the area of the reference area RA. The measured scale value is the area of the reference area RA obtained by the measured camera module at a specific motor position. In some embodiments, the ratio value may also be a value obtained by converting the area of the reference region RA through a specific mathematical function, but it is not limited thereto.

Each ratio value is used to confirm the relative position (or relative distance) of the lens 110 and the object to be measured, and then to know the position of the motor (or the position of the lens 110 relative to the image sensor 170 ).

In addition, in one embodiment, the modulation transfer function value in the measured data may be the modulation transfer function value measured in the central region CP in the captured image. In another embodiment, the modulation transfer function value in the measured data may be the modulation transfer function measured at the four-corner region CP (take the upper left corner as an example, but may be other positions) in the captured image value. In some embodiments, the MTF value in the measured data can be the MTF value measured at any position in the captured image or a statistical indicator of the MTF values at multiple positions (eg, , mean, median or mode).

The processor 59 or the processor 190 may collect the modulation transfer function values corresponding to each motor position in the fine-tuning stage to form and obtain the focus curve (step S430 ). For example, FIGS. 6A and 6B are schematic diagrams of complete curves according to an embodiment of the present invention. Referring to FIG. 6A , it is assumed that the modulation transfer function values TD measured by a certain camera module under different motor positions are as shown in the figure. Referring to FIG. 6B , the processor 59 or the processor 190 may perform curve fitting based on the measured modulation transfer function value TD to determine the focus curve FC. With the coordinate system formed by the modulation transfer function value and the motor position, the focus curve FC may be represented by a cubic or other power equation (eg, forming a parabola). However, the equation is not limited to a cubic equation or a polynomial curve, and a function or other geometric fit related to the data can be applied to determine the focus curve FC.

The processor 59 or the processor 190 may determine whether there is a complete curve based on the currently collected data (step S440). The determination of the complete curve is, for example, that the difference between the focusing curve FC and the near-focus position (corresponding to the peak value of the modulation transfer function) is smaller than the corresponding threshold value, or the focusing curve FC passes through the peak value of the modulation transfer function. If there is no complete curve, the processor 59 or the processor 190 continues to determine the moving distance of the motor 130 of the camera module 100 (ie, determine the next motor) (step S450 ) until a complete curve is formed (that is, the end).

In one embodiment, when the four-corner area (for example, the four-corner area SP shown in FIG. 5 ) has a focal position, the processor 59 or the processor 190 may record and collect all relevant data (for example, the measured ratio) of the four-corner area. value and modulation transfer function value). After the complete curve is obtained, the processor 59 or the processor 190 may record all relevant data of the collected central area (eg, the central area CP shown in FIG. 5 ), and the ratio value of the best clear position (ie, the quasi-focus), Then, the motor 130 is moved to the clear position, so as to complete the focusing. In some embodiments, processor 59 or processor 190 may only target data for the central region.

On the other hand, the data to be tested includes the motor position of the camera module to be tested, the corresponding modulation transfer function value, and the corresponding value of the ratio to be tested. The camera module to be tested refers to a certain camera module 100 currently undergoing focus adjustment (the peak value of the modulation transfer function and its corresponding quasi-focus position have not yet been determined or determined again). When the motor 130 moves the lens 110 to the designated position, the camera module 100 captures the image, and the processor 190 or the processor 59 calculates the modulation transfer based on the sensing data of the image sensor 170 (ie, the captured image) The function value and the scale value to be measured are recorded according to a one-to-one set of data (that is, the motor position and the modulation transfer function value and the scale value to be measured obtained by imaging through the lens 110 at this position) in the data to be measured middle. The scale value to be measured is related to the area of the reference area obtained by the camera module to be measured at a specific motor position. For example, the area of the reference region RA is shown in FIG. 5 .

The processor 59 or the processor 190 may determine the variation relationship according to the focal position of one or more measured camera modules in the measured data and the corresponding measured scale values (step S330 ). Specifically, the change relationship is the ratio of the lens shift change to the scale value change. The lens shift change is the amount of change in one of the focal position and one or more motor positions in the measured data. For example, the numerical difference between the in-focus position and the position of another motor. The scale value change is the amount of change between the scale value corresponding to the focal position and one of one or more scale values in the measured data (ie, the measured scale value). For example, the numerical difference between the scale value of the in-focus position and another measured scale value. The change relationship can be the lens shift change divided by the scale value change or its reciprocal.

In one embodiment, the processor 59 or the processor 190 can compare the one or more fine motor positions and the corresponding one or more fine motor positions of the measured camera module after its modulation transfer function value exceeds the fine tuning threshold. A second measured scale value is available as data. Of course, the measured data has recorded these fine motor positions and the corresponding second measured scale values (corresponding to the area of the reference region in the measured image corresponding to the fine motor positions). That is, the aforementioned motor position includes the fine motor position, and the measured scale value includes the second measured scale value. The processor 59 or the processor 190 may determine the variation relationship according to the representative motor position and the corresponding representative scale value among those fine-tuned motor positions. The lens shift change is the difference between the representative motor position and the focus position, and the scale value change is the difference between the representative scale value and the measured scale value.

In one embodiment, the modulation transfer function value representing the corresponding motor position is the smallest of those fine tuning motor positions or the position of the first step of the fine tuning phase. For example, Table (1) shows the motor 130 of a tested camera module moving 8 positions and its corresponding modulation transfer function values: Table (1) Step count Motor position Modulation transfer function value Measured scale value position change Scale value change 1 0 1.061 518.42 18490 -63.76 2 17176 47.362 460.05 1314 -5.39 3 18276 82.348 454.79 214 -0.13 4 18496 83.618 454.28 -6 0.38 5 18716 79.84 454.92 -226 -0.26 6 18936 82.137 453.95 -446 0.71 7 19156 81.278 453.15 -666 1.51 8 18490 83.878 454.66 0 0

…(1) 其中，PeakPos 為準焦位置對應的調變傳遞函數峰值，FirstPos 為代表馬達位置(以其調變傳遞函數值大於細調門檻值的第一步的馬達位置為例，但在其他實施例可能是其他步數的馬達位置)，PeakScale 為準焦位置對應已測比例值，且FirstScale 為代表馬達位置對應的已測比例值。由此可知，PeakPos-FirstPos 所得的值為鏡頭位移變化，且PeakScale-FirstScale 所得的值為比例值變化。Assuming that the fine adjustment threshold is 30, the motor positions corresponding to the steps of 2 to 8 are the fine adjustment motor positions, and the measured scale value is the second measured scale value. In addition, the mathematical expression of the variation relationship ScaleRatio is:

…(1) Among them, PeakPos is the peak value of the modulation transfer function corresponding to the quasi-focus position, and FirstPos represents the motor position (for example, the motor position of the first step whose modulation transfer function value is greater than the fine adjustment threshold, but in other The embodiment may be motor positions of other steps), PeakScale is the measured scale value corresponding to the quasi-focus position, and FirstScale is the measured scale value corresponding to the motor position. It can be seen that the value obtained by PeakPos-FirstPos is the lens shift change, and the value obtained by PeakScale-FirstScale is the scale value change.

In addition, the position change in Table (1) is the numerical difference between the quasi-focus position and the current motor position, and the scale change is the numerical difference between the measured scale value corresponding to the quasi-focus position and the measured scale value measured at the current motor position .

In another embodiment, the representative motor position may be other of those motor positions in the measured data (ie, not limited to the position of the first step of the fine tuning phase).

In one embodiment, the processor 59 or the processor 190 can respectively classify the relative distances between the fine adjustment motor positions and the focal position into one of several fine adjustment intervals according to the corresponding modulation transfer function values. The relative distance is, for example, the position change in the aforementioned table (1) (ie, the numerical difference between the focus position and the current motor position).

In one embodiment, the processor 59 or the processor 190 equally divides the measured data in the fine tuning stage into several fine tuning intervals according to their modulation transfer function values. For example, if the modulation transfer function value of the measured data is between 30 and 90, the size of the fine tuning interval is 4 and can be divided into 15 equal parts (to form 15 data). Among them, the first data is the data corresponding to the modulation transfer function value of 30, the second data is the data corresponding to the modulation transfer function value of 34, and so on. In another embodiment, the size and variation of the fine adjustment interval (for example, may not be divided equally) can still be changed according to actual needs, which is not limited by the embodiment of the present invention.

Each fine tuning interval corresponds to one of those relative distances. The processor 59 or the processor 190 confirms the fine tuning interval corresponding to a certain modulation transfer function value in the measured data, and maps the modulation transfer function value to the corresponding fine tuning interval. The number Item_Index of the fine adjustment interval can be obtained from formula (2): Item_Index = [(MTF-30)/Interval]…(2) MTF is the modulation transfer function value, and Interval is the size of the fine tuning interval (eg, 4 or other values).

For example, assuming that the size of the fine adjustment interval is 4, Table (2) is the relative distance data of the fine adjustment interval: Table (2) Numbering 1 2 3 4 5 6 7 8 relative distance 2200 2090 1942.88 1813.08 1694 1592.21 1498.74 1336.22 Numbering 9 10 11 12 13 14 15 relative distance 1260.77 1135.96 980.041 844.475 605.798 291.335 144.354 Suppose the focal position is 2013.08. When the fine motor position is at 200, its modulation transfer function value is 49, and from formula (2), it can be obtained that the modulation transfer function value is brought into formula (2) to obtain [(49-30)/4 ]=4. That is, when the modulation transfer function value is 49, the relative distance of moving to the focal position is 2013.08-200=1813.08. Fill in the value of 1813.08 in the fine adjustment interval of No. 4 (as shown in Table (2)). By analogy, processor 59 or processor 190 may classify the modulation transfer function values in all fine tuning stages into each numbered fine tuning interval and record their relative distances (eg, form table (2)).

For example, FIG. 7 is a diagram illustrating a relationship between a modulation transfer function value and a motor position in a focusing process according to an embodiment of the present invention. Referring to FIG. 7, it is assumed that the motor position x in the measured data is {0, 2200, 4400, 6600, 8800, 11000, 11110, 11220, 11330, 11440}, and the corresponding modulation transfer function value y(x) is {1.3184, 1.0017, 1.367, 2.2299, 11.6538, 69.2429, 72.0549, 73.5307, 73.5189, 72.9504} (that is, the modulation transfer function value corresponding to the motor position x).

8 is a graph showing the relationship between the measured scale value and the motor position in the focusing process according to an embodiment of the present invention. Referring to FIG. 8, it is assumed that the motor position x is the same as that of FIG. 7, and the corresponding measured scale value z(x) is {472.91, 468, 460.78, 453.46, 446.18, 438.84, 438.25, 438, 437.44, 437.04}.

In addition, table (3) is all the focusing data of the 10 tested camera modules (it should be noted that the data shown in table (3) is only for illustration, and the tested camera modules corresponding to these data are different from The tested camera modules in Figure 7 and Figure 8): Table (3) Focus position The measured ratio value corresponding to the focal position Modulation transfer function peak represents the motor position represents the scale value Represents the modulation transfer function value corresponding to the motor position alternative relation 17050 449.35 84.9901 15400 454.66 46.4455 -310.734 18260 453.58 86.5307 16500 459.17 43.3647 -314.848 15180 450.58 83.361 13200 457.54 38.1871 -284.483 15180 451.83 87.0328 13200 458.7 38.6606 -288.21 14410 450.21 84.6829 12650 455.64 43.1075 -324.125 14850 452.11 87.3083 13200 457.94 49.5041 -281.57 17160 453.14 87.7189 15400 458.88 47.6689 -306.62 16280 451.58 84.7532 14300 458.13 42.6817 -330.29 15840 452.95 87.4093 14300 457.61 46.8523 -330.472 16500 452.85 86.8734 14300 460.01 30.6997 -307.263

)/n…(3) 其中，

為調變傳遞函數峰值，n為那些已測相機模組的數量。以表(3)為例，峰值代表為(84.9901+86.5307+83.361+87.0328+84.6829+87.3083+87.7189+84.7532+87.4093+86.8734)/10=86.0661。 此外，關係代表為其平均值AvgScale_Ratio： AvgScale_Ratio=

/n…(4) 其中，

為變化關係(例如由公式(1)得出)。以表(3)為例，關係代表為(-310.734-314.848-284.483-288.21-324.125-281.57-306.62-302.29-330.472-307.263)/10=-305.062。The processor 59 or the processor 190 can determine the peak representation of these modulation transfer function peaks and the relationship representation of the variation relationship. In one embodiment, the peak is represented as its average AvgValue: AvgValue=(

)/n…(3) where,

is the peak modulation transfer function, and n is the number of those camera modules that have been tested. Taking Table (3) as an example, the peak value is (84.9901+86.5307+83.361+87.0328+84.6829+87.3083+87.7189+84.7532+87.4093+86.8734)/10=86.0661. Also, the relationship is represented by its mean AvgScale_Ratio: AvgScale_Ratio=

/n…(4) where,

is a variation relationship (eg derived from formula (1)). Taking Table (3) as an example, the relationship representation is (-310.734-314.848-284.483-288.21-324.125-281.57-306.62-302.29-330.472-307.263)/10=-305.062.

In another embodiment, the peak representation may be other statistical indicators (eg, median, or mode) or any of those modulation transfer function peaks in the measured data, and the relational representation may be the measured data Other statistical measures of the relationship (eg, median, or mode) or any of those in the relationship.

The processor 59 or the processor 190 can determine the next motor position of the camera module to be tested according to the data to be tested and the change relationship (step S350). Specifically, FIG. 9 is a flowchart of a focusing method according to an embodiment of the present invention. Referring to FIG. 9 , for the camera module to be tested, the processor 59 or the processor 190 can analyze the change relationship (step S910 ). Similar to the measured scale value, for the camera module to be tested, the processor 59 or the processor 190 can be based on the target pattern in the image captured by the image sensor 170 (the black square shown in FIG. 5 as an example, But not limited to this), and calculate the scale value to be measured based on the area of the target area corresponding to the target pattern in the image (for example, the number of pixels occupied in the image, the ratio of the number, or measured in length units) .

In one embodiment, the processor 59 or the processor 190 may use the variation relationship between the scale value to be measured and the scale value measured to obtain the next motor position. Specifically, the ratio of the lens shift change (the numerical difference between the focal position and other motor positions) and the scale value change (the numerical difference between the scale value corresponding to the focal position and other scale values) (that is, the change relationship ) are roughly the same. Therefore, the in-focus position can be predicted using the variation relationship. And the numerical difference and proportional value change between the current motor position and this next motor position (related to the numerical difference between the measured proportional value corresponding to the next motor position and the unmeasured proportional value corresponding to the current motor position) should also be equal to or close to the variation based on the measured data.

The next motor position Next_Pos can be derived from equation (5): Next_Pos = ((Peak_Scale – Current_Scale) * Scale_Ratio) + Current_Pos…(5) Wherein, Peak_Scale is the scale representation of the measured scale value in the measured data (for example, the statistical index of the measured scale value corresponding to the quasi-focus position of one or more measured camera modules in the measured data or Any of them), Current_Scale is the measured ratio value of the camera module to be tested, Scale_Ratio is the relationship representation of the change relationship of one or more tested camera modules in the measured data, and Current_Pos is the current motor position .

The processor 59 or the processor 190 can drive the motor 130 to move to the predicted position (ie, the predicted position with the peak value of the modulation transfer function) by controlling the motor driving circuit 150 according to the next motor position (step S920 ). The image is captured by the image sensor 170, and the corresponding modulation transfer function value and the scale value to be measured are obtained accordingly.

The processor 59 or the processor 190 can determine whether the modulation transfer function value corresponding to the current motor position reaches the fine tuning threshold (which may be the same as or different from the fine tuning threshold used for the measured data). If the current MTF value does not reach the fine adjustment threshold, the coarse adjustment stage is maintained, and the processor 59 or the processor 190 can again use the variation relationship and the measured proportional value corresponding to the current motor position to determine the next motor position .

If the current modulation transfer function value has reached the fine tuning threshold (for example, the modulation transfer function value corresponding to the motor position of the camera module to be tested is greater than or equal to the fine tuning threshold), the fine tuning stage is entered, and processing is performed. The device 59 or the processor 190 can obtain the relative distance corresponding to the fine tuning interval to which the current modulation transfer function value belongs (step S930 ). For the cutting method of the fine adjustment interval, reference may be made to the foregoing description, and details are not repeated here. The processor 59 or the processor 190 can use the formula (2) to obtain the number of the fine adjustment interval to which the current modulation transfer function value belongs, and according to the relative distance corresponding to the fine adjustment interval in the measured data (as shown in Table (2). ) shown). During the fine-tuning phase, the processor 59 or the processor 190 can determine the next motor position based on the relative distance without using a variation relationship. That is, the next motor position is the sum of the current motor position and the relative distance. Taking Table (2) as an example, assuming that the current modulation transfer function value belongs to number 5, and the current motor position is 18000, the next motor position is 18000+1694=19694.

The modulation transfer function value and the ratio value to be measured obtained from the aforementioned motor positions can be used as the data to be measured, and the processor 59 or the processor 190 can determine whether the current data to be measured has a complete curve (step S940 ). Similar to step S440, the determination of the complete curve is, for example, the difference between the focus curve formed by the motor position and one or more modulation transfer function values in the data to be measured and the quasi-focus position (corresponding to the modulation transfer function peak value). The difference is less than the corresponding threshold value, or the focus curve passes through the modulation transfer function peak.

If there is no complete curve yet, the processor 59 or the processor 190 continues to determine the moving distance of the motor 130 of the camera module 100 (ie, determine the next motor) (step S930 ), until a complete curve is formed (ie, the test to be tested is found) the focal position of the camera module). At this time, the representative motor 130 can be moved to the clear position (ie, the focus position) (step S950 ), and the focusing is completed accordingly (step S960 ).

To sum up, in the camera module, focus adjustment system, and focus method according to the embodiments of the present invention, the measured data of the measured camera module are collected, and the change relationship related to the change of the lens displacement and the change of the scale value and The relative distance from the focus position. The changing relationship and relative distance can be used to estimate the focus position, so that the focus adjustment process can be performed quickly.

Although the present invention has been disclosed above by the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the scope of the appended patent application.

C: camera DoF: Depth of Field O: object 1: Focus adjustment system 50: Computing device 59: Processor 100: Camera Module 110: Lens 130: Motor 150: Motor drive circuit 170: Image Sensor 190: Processor S310~S350, S410~S450, S910~S960: Steps RA: Reference area SP: Four Corners Area CP: Central area TD: Modulation transfer function value FC: focus curve

Figure 1 is a schematic diagram of the depth of field of a camera. FIG. 2 is a block diagram of components of a focus adjustment system according to an embodiment of the present invention. FIG. 3 is a flowchart of a focusing method according to an embodiment of the present invention. FIG. 4 is a flow chart of obtaining measured data according to an embodiment of the present invention. FIG. 5 is a schematic diagram of determining a scale value according to an embodiment of the present invention. 6A and 6B are schematic diagrams of complete curves according to an embodiment of the present invention. 7 is a diagram illustrating a relationship between a Modulation Transfer Function (MTF) value and a motor position in a focusing process according to an embodiment of the present invention. 8 is a graph showing the relationship between the measured scale value and the motor position in the focusing process according to an embodiment of the present invention. FIG. 9 is a flowchart of a focusing method according to an embodiment of the present invention.

S310~S350: Steps

Claims (14)

A focusing method includes: obtaining a measured data and a to-be-measured data, wherein the measured data includes the quasi-focus positions of a plurality of measured camera modules, the corresponding modulation transfer function (Modulation Transfer Function, MTF) peak value and The corresponding measured scale value, the data to be measured includes the motor position of a camera module to be measured, the corresponding modulation transfer function value, and the corresponding measured scale value, each of the quasi-focus positions refers to the corresponding The position to which the motor of the camera module drives the displacement of its lens corresponds to the peak value of the modulation transfer function, and the measured scale value and the to-be-measured scale value are related to the area of a reference area in the captured image; determining a change relationship according to the measured camera modules in the quasi-focus position and the corresponding measured scale value in the measured data, wherein the change relationship is a ratio of a lens shift change to a scale value change; and The next motor position of the camera module to be tested is determined according to the data to be tested and the changing relationship. The focusing method as claimed in claim 1, wherein the measured data further records a plurality of fine motor positions and a plurality of corresponding fine motor positions of the measured camera modules after their modulation transfer function values exceed a fine adjustment threshold The second measured scale value, and the step of determining the variation relationship according to the measured camera modules in the quasi-focus position and the corresponding measured scale value in the measured data includes: according to the fine adjustment motor positions A representative motor position and a corresponding representative scale value of , determine the change relationship, wherein the lens displacement change is the difference between the representative motor position and the focal position, and the scale value change is the representative scale value and the The difference between the measured scale values. The focusing method of claim 2, wherein the modulation transfer function value corresponding to the representative motor position is the smallest of the fine motor positions. The focusing method according to claim 1, wherein the step of determining the next motor position of the camera module to be tested according to the data to be tested and the changing relationship comprises: a difference between the scale value to be measured and the scale value that has been measured The difference uses the variation to obtain the next motor position. The focusing method of claim 2, further comprising: classifying the relative distances between the fine adjustment motor positions and the quasi-focus position into one of a plurality of fine adjustment intervals according to the corresponding modulation transfer function value, wherein Each of the fine tuning intervals corresponds to one of the relative distances. The focusing method according to claim 5, wherein the step of determining the next motor position of the camera module to be tested according to the data to be tested and the change relationship comprises: according to the fine tuning of the modulation transfer function value to which the value of the modulation transfer function belongs. The relative distance corresponding to the interval determines the next motor position, wherein the modulation transfer function value corresponding to the motor position of the camera module to be tested is greater than the fine adjustment threshold value. A focus adjustment system, comprising: a processor configured to: obtain a measured data and a to-be-measured data, wherein the measured data includes the quasi-focus positions of a plurality of measured camera modules and the corresponding modulation transfer The peak value of the function and the corresponding measured scale value, the data to be measured includes the motor position of a camera module to be measured, the corresponding modulation transfer function value, and the corresponding measured scale value, each of the quasi-focus positions refers to the right There should be a corresponding peak value of the modulation transfer function at the position to which the motor of the measured camera module drives its lens displacement, and the measured scale value and the to-be-measured scale value are related to a reference area in the captured image. area; a variation relationship is determined according to the measured camera modules in the quasi-focus position and the corresponding measured scale value in the measured data, wherein the change relationship is a ratio of a lens shift change to a scale value change ; and determine the next motor position of the camera module to be tested according to the data to be tested and the changing relationship. The focus adjustment system as claimed in claim 7, wherein the measured data further records a plurality of fine-adjustment motor positions and corresponding multiples of the measured camera modules after their modulation transfer function values exceed a fine-adjustment threshold. a second measured scale value, and the processor is further configured to: determine the variation relationship according to a representative motor position and a corresponding representative scale value among the fine-tuning motor positions, wherein the lens shift variation is the representative The difference between the motor position and the focal position, and the scale value change is the difference between the representative scale value and the measured scale value. The focus adjustment system of claim 8, wherein the modulation transfer function value corresponding to the representative motor position is the smallest of the fine motor positions. The focus adjustment system of claim 7, wherein the processor is further configured to: obtain the next motor position using the variation relationship for the difference between the measured scale value and the measured scale value. The focus adjustment system of claim 8, wherein the processor is further configured to: classify the relative distances between the fine adjustment motor positions and the quasi-focus position into a plurality of fine adjustment motor positions according to the corresponding modulation transfer function values. one of the pitch intervals, wherein each of the fine pitch intervals corresponds to one of the relative distances. The focus adjustment system of claim 11, wherein the processor is further configured to: determine the next motor position according to the relative distance corresponding to a fine adjustment interval to which the modulation transfer function value belongs, wherein the The modulation transfer function value corresponding to the motor position of the camera module to be tested is greater than the fine adjustment threshold value. The focus adjustment system of claim 7, further comprising: the camera module to be tested, comprising: the lens; the motor coupled to the lens and used to drive the lens according to the next motor position; and an image sensor a measuring device, wherein the processor obtains the modulation transfer function value corresponding to the next motor position and the corresponding measured scale value according to the image captured by the image sensor, as another data to be measured. A camera module includes: a lens; a motor, coupled to the lens, and used to drive the lens to move; a motor drive circuit, coupled to the motor, and used to control the motor; an image sensor for capturing images, and a processor, coupled to the motor driving circuit and the image sensor, and configured to: obtain a measured data and a to-be-measured data, wherein the measured data The measured data includes the focal positions of a plurality of tested camera modules, the corresponding modulation transfer function peaks, and the corresponding measured ratio values. The data to be tested includes the motor position of a camera module to be tested, the corresponding modulation transfer function The function value and the corresponding scale value to be measured, each of the focal positions refers to the corresponding peak value of the modulation transfer function at the position to which the motor of the camera module under test drives the lens displacement, and the The measured scale value and the to-be-measured scale value are related to the area of a reference area in the captured image; according to the measured data, the measured camera modules are at the quasi-focus position and the corresponding measured scale value determining a change relationship, wherein the change relationship is a ratio of a lens displacement change to a proportional value change; and determining the next motor position of the camera module to be tested according to the data to be tested and the change relationship.

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