JP4534197B2 - Autofocus system, autofocus module, and autofocus mechanism - Google Patents

Description

The present invention relates to a system for automatic focusing (auto-focus) for the camera apparatus having a digital camera or a portable terminal, a module for especially to assist it.

Than before, in applications such as high-performance digital camera, for automatic focusing, (see Non-Patent Document 1) in which the distance measuring sensor is used for detecting the distance to an object required. This type of sensor is referred to as an autofocus (AF) module. The module has two optical systems, each including a sensor array in which sensors are arranged in a line at a narrow pitch. Since the optical system and the sensor array are configured as a single package, the module has a horizontally long profile in which two optical systems are juxtaposed.

  The module performs a passive or active operation. In other words, the module can receive light reflected by the object and returned by the optical image of the object to be photographed or auxiliary light by the two optical systems and form an image on the sensor array.

The information detected by the sensor array is provided to the control unit of the imaging device, and the optical distance of the imaging device is calculated so that the distance to the object is calculated from the positional relationship on the sensor so that the focal point is obtained. Displace the optical components in the system. Furthermore, if necessary, the position of the optical component is finely adjusted according to information based on the contrast from the signal processing unit of the imaging device (see Patent Document 1, Patent Document 2, and Patent Document 3). As an optical system capable of changing the focal point, there is also known an optical system that changes the shape of an optical component composed of a liquid other than the one that changes the position of an optical component such as a lens (Patent Document 4 and Patent). Reference 5).
JP 2000-98217 A JP 2003-35861 A JP 2003-262789 A Special table 2001-515539 Special table 2002-540464 Fuji Times Vol.76, No.3, 2003, pp175-177

  The above-described autofocus module basically includes two optical systems and sensors, and is required to be separated from each other by a certain distance or more in order to increase the distance measurement accuracy. As a result, the size of the module increases along the direction in which the sensor array extends. If such a module is mounted on a mobile phone or a small portable terminal having a size equivalent to that, it will occupy an unnecessarily large volume.

  In addition, with respect to the manufacture of such a module, since strict symmetry is required for the performance of the two sensor arrays, high-precision optical system design and assembly accuracy are required. Therefore, it is relatively difficult to manufacture and it is desired to adopt an improved method.

The present invention aims to provide a practical system, including ease of manufacturing auxiliary module and it small for use in ranging applications for automatic focusing.

The present invention provides an imaging module including a focus adjustment mechanism of the main image, an improved system for automatic focusing system including an auxiliary module for distance measurement. The imaging module includes an imaging device, an optical system including an optical component that overlaps the imaging device, and a focus adjustment mechanism that adjusts the position of the optical component so as to be an appropriate focal position with respect to the imaging device. On the other hand, the auxiliary module includes an auxiliary imaging device, an auxiliary optical system including an auxiliary optical component overlapping the auxiliary imaging device, and an auxiliary optical system adjusting mechanism. The auxiliary optical system adjustment mechanism moves the auxiliary optical system within a range narrower than the movable range of the optical components in the imaging module, determines the focal position from the video information obtained through the auxiliary imaging element, and determines the focal point. Get distance information from position. The auxiliary optical system may move at a faster speed than the optical system of the focus adjustment mechanism. The focus adjustment mechanism performs coarse adjustment of the focal length based on this distance information, and then performs fine adjustment based on information from the image sensor.

  While the auxiliary optical component of the auxiliary module moves, the optical component of the imaging module may be stationary, but the optical component of the imaging module may be moved during the movement. According to the latter, in a fixed case, the time until focusing can be shortened.

The auxiliary module receives light of different wavelengths and can determine the focal length based on information of all the focal positions. For example, light in the wavelength range of red (R), green (G), and blue (B) is used as a reference.

  The auxiliary module can be integrated with the imaging module. In this case, the optical system of the imaging module may be supported by the optical system of the auxiliary module and movable relative to the optical system. Thereby, the optical system of the imaging module is interlocked with the optical system of the auxiliary module, and the time until focusing can be shortened.

  In other cases, the auxiliary optical component is continuously deformed without moving, thereby determining the focal position from the video information obtained by detection while changing the focal length of the optical system. It is configured to obtain distance information from the focal position. Also in this case, while the auxiliary optical component is deformed, the optical component of the imaging module may be stationary or may be moved. The auxiliary module may separately detect a plurality of wavelengths, typically RGB.

  Furthermore, the present invention provides a small ranging auxiliary module that cooperates with the focus adjustment mechanism of the imaging module. The auxiliary module includes an auxiliary imaging device, an auxiliary optical system, and an auxiliary optical system adjustment mechanism, and determines the focal position by moving the auxiliary optical component within a range narrower than the moving range of the optical component in the imaging module. The distance information is determined from the focal position and output to the imaging module.

  The auxiliary imaging element may include an element capable of detecting light having different wavelengths, and the focal length may be determined based on the detection value of each wavelength. For example, the light in the red, green, and blue wavelength ranges can be used as a reference.

  The auxiliary optical system of the auxiliary module may be modified without moving the optical system in order to change the focal length. For example, a liquid lens that can change the interface shape of the liquid by voltage driving is used.

  According to the present invention, since the auxiliary module is realized by a single optical system, the package mounting dimension can be reduced. Therefore, it is suitable for applications that require further miniaturization, such as application to camera devices in mobile devices such as mobile phones. In addition, the auxiliary optical system adjustment mechanism moves the auxiliary optical system within a range shorter than the main image focus adjustment mechanism or changes the focal position from the video information obtained via the auxiliary image sensor. However, as will be described later in the embodiment, the time for focusing can be shortened by adopting this configuration. Therefore, the delay in time from when the shutter is pressed to when shooting can be further reduced.

Hereinafter, an automatic focusing system and an auxiliary module used in the automatic focusing system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a schematic diagram showing a configuration of an automatic focusing system which is a first preferred embodiment of the present invention. The system includes an imaging module 20 incorporated in the camera device 50 and an auxiliary module 10 used as an auxiliary thereto. Imaging module 20 is a module for photographing an object, the auxiliary module 10 provides the distance information to the imaging module 20 is the module used as an auxiliary for the action of the automatic focusing (automatic focusing) . Both optical axes are shown as C1 and C2, respectively. Communication means is provided for signal transmission from the auxiliary module 10 to the imaging module 20. Moreover, although not shown in figure, in order to fix both relative position, a suitable positioning means is provided. Communication means and positioning means are also included in the camera device 50.

  The auxiliary module 10 and the imaging module 20 have a similar configuration. The imaging module 20 includes an imaging element 22 and a lens (optical component) 23. The lens 23 is supported by a support body 26, and the support body 26 is movable along the rail 25. An optical system including the movable range of the lens 23 is indicated by a broken line 24. As a means for moving the support 26, typically, a slider mechanism using an electric motor or actuator can be considered.

  Image information from the image sensor 22 is provided to the signal processing means 21. The position of the lens 23 in the direction along the rail 25 is also detected by means such as a sensor (not shown) and provided to the signal processing means 21. In the signal processing means 21, signal processing is performed on image information such as contrast information and lightness information and position information of the lens 23. Based on the signal, position adjustment for placing the support 26, that is, the lens 23 at the focal position is performed. Further, the signal processing means 21 can process image information when the lens 23 is placed at an appropriate focal position and output it in an appropriate format.

  On the other hand, the auxiliary module 10 also includes an image sensor 12 and a lens 13. The lens 13 is supported by a support body 16, and the support body 16 is movable along the rail 15. Here, the movable range of the lens 13 is shorter than the movable range of the lens 23 of the imaging module 20, and as described later, the focal length is designed to be shorter than that of the imaging module 20 for subjects at the same distance. It should be noted that. An optical system including the movable range of the lens 23 is indicated by a broken line 14.

Image information from the image sensor 12 is provided to the signal processing means 11. In the signal processing unit 11 , signal processing is performed on image information such as contrast information and brightness information and position information of the lens 13. Based on the signal, position adjustment for placing the support 16, that is, the lens 13 at the focal position is performed. The signal processing unit 11 provides distance information when the lens 13 is placed at an appropriate focal position to the signal processing unit 21 of the imaging module 20.

  FIG. 2 is a diagram illustrating lens shift amounts in the optical systems of the imaging module and the auxiliary module corresponding to the position of the subject. With reference to FIG. 2, the effect | action of the focus detection by the auxiliary | assistant module 10 and the imaging module 20 in this embodiment is demonstrated.

  In the initial stage, the auxiliary module 10 and the imaging module 20 are placed at positions closest to the imaging elements 12 and 22 where the object image is focused at infinity, and each of the imaging elements 12 and 22 is This is detected. The signal processing means 11 and 21 refer to the information of the video.

  In the first stage of focus detection, the lens 13 of the auxiliary module 10 observes video information such as contrast while extending forward in a predetermined step. The signal processing means 11 detects the focal position with respect to the optical system 14 of the auxiliary module 10 by processing the video information signal in each step. For example, the focal position is determined as a position where the contrast of the image shows a peak. As shown in FIG. 2, the optical system 14 of the auxiliary module 10 has a short optical length and is focused by passing through a distance F <b> 1 shorter than the optical system 24 of the imaging module 20, or passes through that position. In the latter case, for example, the passage of the focal position is determined by a decrease in contrast. By determining the focal position or detecting the passage, the signal processing unit 11 can determine the approximate position of the subject from the point A1 corresponding to F1 in FIG.

  In the second stage of focus detection, information on the focal position roughly determined in the previous stage is provided to the signal processing means 21 of the imaging module 20, and the lens 23 of the imaging module 20 is aligned with the corresponding focal position. This position is determined by the transition step of the lens 13 in the auxiliary module 10, and is a position roughly determined so as to include an error. As shown in FIG. 2, the point A <b> 2 intersects the subject distance of the point A <b> 1 in the auxiliary module 10 in the imaging module 20. Therefore, the lens 23 is moved by the shift amount of F2 corresponding to the point A2. The correlation of the shift amounts of the lenses 13 and 23 of the optical systems 14 and 24 in the auxiliary module 10 and the imaging module 20 shown in FIG. 2 can be stored in a storage device (not shown) built in the camera device 30.

  The movement of the lens 23 can also be performed while the lens 13 in the auxiliary module 10 is moved in the first stage. In this case, the lens 23 may be moved at a predetermined speed corresponding to the amount of displacement. In other cases, the signal processing means 21 provides information about the position of the lens 13 to the auxiliary module. The moving speed of the lens 23 may be determined based on the ten signal processing units 11.

  In the third stage of focus detection, the lens 23 is finely adjusted based on the video information detected by the image sensor 22 of the imaging module 20 from the roughly determined focus position, and displaced to an appropriate focal length. Thereby, accurate positioning to the focal position is achieved, and the subject can be photographed by the imaging module 20.

  According to this method, the distance of movement of the lens 13 of the auxiliary module 10 can be shortened in addition to the fact that the auxiliary module as a distance measuring sensor can be configured in a small size as compared with this type of conventional system. Ranging can be performed in a relatively short time, and as a result, the time until photographing can be sufficiently shortened.

Figure 3 is a second preferred embodiment of the present invention, light of different wavelengths is a schematic diagram showing a configuration of an automatic focusing system using ie, a different color of the auxiliary light. FIG. 4 is a diagram showing an example of the contrast signal value for each color detected by the auxiliary module in the system of FIG. In FIG. 3, the auxiliary light source 170 and the auxiliary module 110 in the camera device 150 are shown, and the imaging module is omitted. Since the cooperative action of the auxiliary module 110 and the imaging module is the same as that of the first embodiment, a method for determining the focal length by the auxiliary module 110 when the auxiliary light source 170 is used will be described below. Among the auxiliary modules 110, the same function as that of the auxiliary module 10 of the first embodiment is indicated by adding 100 to the reference number.

  As the auxiliary light source 170, a light source that emits three colors of R (red), G (green), and B (blue) as light of different wavelengths is prepared. A typical light source is a light emitting diode (LED). The auxiliary light source 170 in the figure is shown by integrating three color light sources, but may be of a type in which light emitting diodes of each color are mounted on the same substrate, for example.

  On the other hand, the image sensor 112 of the auxiliary module 110 is constituted by, for example, a CCD or CMOS sensor, and RGB color filters are arranged on the pixel surface. Thereby, the image sensor 112 can individually detect the light of the emission color of the auxiliary light source 170.

  In the step of determining the focal length by the auxiliary module 110 corresponding to the first stage in the first embodiment, the subject is irradiated with light from the auxiliary light source. In this case, since the focal length depends on the wavelength with respect to the lens 113 of the optical system 114, when the lens 113 is moved, as shown in FIG. 4, there is a slight shift in the detection peak position of the contrast signal for each color. Arise. Therefore, the focal length of the auxiliary module can be determined with higher resolution by continuously observing the contrast signal and adding correction based on this deviation value.

Figure 5 is a schematic diagram showing a third configuration of the autofocus system to which the preferred embodiments of the present invention. The system of the present embodiment incorporates in the camera device 250 a composite module 210 in which the auxiliary module and the imaging module described in the above-described embodiments are integrated.

  The composite module 210 includes an optical system 214 that includes a first lens 213 corresponding to the lens of the auxiliary module and a second lens 223 corresponding to the lens of the imaging module. The light passing through the lens 213 is detected by the first image sensor 212, and the light passing through the lens 223 is detected by the second image sensor 222. The first and second image sensors 212 and 222 are connected to the first and second signal processing units 211 and 221, respectively. The first and second signal processing means 211 and 221 may be configured as a single means.

  The basic operation of this embodiment is the same as that of the other embodiments described above. That is, according to the focus detection method of the present embodiment, in the first step, the focal length is roughly determined from the contrast and other video information detected by the image sensor 212 corresponding to the first lens 213, Based on the image information obtained by moving the second lens 223 used for photographing to the focal position determined roughly based on the image, and then detecting it by the image sensor 222 corresponding to the second lens 223, Therefore, fine adjustment is performed by moving the second lens 223 to an appropriate focal length. The captured image is processed by the signal processing unit 221 and output in a predetermined format.

  A characteristic point in this embodiment is the structure of the movable means of the first and second lenses 213 and 223. As shown in the drawing, the first lens 213 is supported by a support body 216 that can move on a rail 215. The support body 216 integrally includes a rail 225 on which the support body 217 that supports the second lens 223 can move. According to this configuration, firstly, the volume occupied by the entire module can be reduced. Second, similarly to the above-described modification of the first embodiment, the second lens 223 is moved while the first lens 213 is moved, so that the focal length is aligned for a relatively short time. be able to. In particular, the present embodiment is advantageous in that unnecessary signal processing for preventing an excessive amount of displacement is not required.

Figure 6 is a schematic diagram showing a configuration of an automatic focusing system which is a fourth preferred embodiment of the present invention. Autofocus system 350, as in the first preferred embodiment, comprises an auxiliary module 310 cooperating with the imaging module. The operation of the imaging module is not shown because it is common to the first embodiment. That is, the auxiliary module 310 roughly detects distance information and provides the distance information to an imaging module (not shown).

A characteristic point of this embodiment is that a lens device 314 using a liquid is used for the optical system of the auxiliary module. This lens device has an oil 380 and a conductive aqueous solution 370 in a sealed space defined inside a concave member 340 and a lid member 362 that are combined with each other. The oil 380 is attached to the inner surface of the lid member 362 that is an insulator. The condensing action of the lens is provided by utilizing refraction at the interface shape between the oil 380 and the conductive aqueous solution. As shown in the drawing, in the vicinity of the center of the concave member 340 and the lid member 362, additional lens portions 341 and 363 for correcting the lens effect due to the liquid are provided.

  An optical system using this type of liquid lens has the same principle as that described in Patent Documents 4 and 5 described above. An electric field is used to control the interface shape between the oil 380 and the conductive aqueous solution 370. As illustrated, the first electrode 391 is provided along the circumferential direction of the outer surface of the lid member 362, and the second electrode 392 is provided along the inclined inner surface of the concave member 340. That is, the first and second electrodes 391 and 392 are disposed on both sides of the inner surface of the lid member 362.

  On the inner surface of the lid member 362, a portion 365 that is surface-treated so as to be hydrophilic along the edge is formed. Therefore, in a normal state, the conductive aqueous solution 370 contacts only the surface treatment portion 365 of the inner surface of the lid member 362. However, when a voltage is applied between the first and second electrodes 391 and 392 to generate an electric field, the chemical properties of the inner portion 355 of the surface treatment portion 365 are altered, and the wettability of the conductive aqueous solution is improved. The As a result, the conductive aqueous solution 370 also gets wet with the portion 355, and the shape of the oil 380 changes from a solid line shape to a broken line shape. The degree of change, that is, the area of the portion 355 where the wettability is improved varies depending on the strength of the electric field. Therefore, by changing the applied voltage, the degree of deformation of the oil 380 can be changed, and the light condensing characteristics can be controlled.

  Therefore, as in the case of the other embodiments described above, the voltage between the first and second electrodes 391 and 392 is gradually increased, or is changed so that the voltage is sufficiently increased and then gradually decreased. 312 detects video information. The detected video information is processed at any time by the signal processing means 311 to obtain video information such as contrast information.

  The signal processing means 311 controls the applied voltage and roughly determines the distance of the subject from the obtained information. The determined distance information is provided to an imaging module (not shown), and high-precision focusing is performed by the imaging module. According to this configuration, a mechanism for mechanically moving the optical system is unnecessary, and there is an advantage that high-speed control for focusing is possible with a relatively simple configuration.

  As described above, the preferred embodiment of the present invention has been described in detail. However, this is merely an example and does not limit the present invention, and various modifications and changes can be made by those skilled in the art. It is. For example, in the first embodiment, the auxiliary module and the imaging module may be simply mechanically coupled, or the auxiliary light source may be used in the third embodiment. In addition, the lens shown in each embodiment may not be a single lens but may be a plurality of lenses that change mechanically in cooperation. The moving means for moving the lens may be a contact type or a non-contact type. Various structures of the formula are conceivable. Furthermore, in the fourth embodiment, not only a convex lens but also a concave lens can be used as the additional optical system, and the shape of the liquid lens in the normal state can be set to various irregular shapes.

It is a schematic view showing the arrangement of an automatic focusing system which is a first preferred embodiment of the present invention. It is a figure which shows the displacement of the lens in each optical system of the imaging module and auxiliary | assistant module corresponding to a to-be-photographed object's position. The configuration of the automatic focusing system according to the second preferred embodiment of the present invention is a schematic diagram partially showing. It is a figure which shows the example of the contrast signal value with respect to each color detected by the auxiliary | assistant module in the system of FIG. It is a schematic view showing the arrangement of an automatic focusing system which is a third preferred embodiment of the present invention. The configuration of an automatic focusing system which is a fourth preferred embodiment of the present invention is a schematic diagram partially showing.

Explanation of symbols

10, 110, 310 Auxiliary module
11, 111, 211, 311 Signal processing means 12, 112, 212, 312 Imaging means 14, 114, 214, 314 Auxiliary optical system 20 Imaging module 21, 221 Signal processing means 22, 222 Imaging means 23, lens 170 Auxiliary light source 210 Compound module

Claims (10)

An automatic focusing system comprising an imaging module and an auxiliary module,
The imaging module is
An imaging lens for overlapping the IMAGING element,
To the incident light from the Utsushitai focusing on the imaging device, and imaging focus adjustment mechanism for adjusting the position of the imaging lens,
Control means for controlling the imaging focus adjustment mechanism so as to finely adjust the position of the imaging lens using information from the imaging element;
The auxiliary module is
An auxiliary lens for overlapping the auxiliary imaging element,
Provided separately from the imaging focus adjustment mechanism, the position of the auxiliary lens is independent of the position of the imaging lens so that incident light from the subject is focused on the auxiliary imaging element. An auxiliary focus adjustment mechanism for adjusting ,
The auxiliary module provides distance information representing the distance to the subject as rough adjustment information to the imaging focus adjustment mechanism, so that the imaging focus adjustment mechanism uses the information from the imaging element. Before finely adjusting the position of the imaging lens, coarsely adjust the position of the imaging lens based on the rough adjustment information,
The automatic focus is characterized in that an adjustment range for the auxiliary focus adjustment mechanism to align the auxiliary lens is smaller than an adjustment range for the imaging focus adjustment mechanism to align the imaging lens. Alignment system. The automatic focusing system according to claim 1, wherein the imaging lens of the imaging module is stationary while the auxiliary lens of the auxiliary module moves. The automatic focusing system according to claim 1, wherein the imaging lens of the imaging module moves while the auxiliary lens of the auxiliary module moves. The automatic focusing system according to claim 1, wherein the auxiliary module is integrated with the imaging module. The auxiliary module and the imaging module is formed as an integral, and wherein the said auxiliary lens of the auxiliary module and the imaging lens of the imaging module can be moved relative to Claim 4 automatic focusing system described. An autofocus module comprising an imaging module and an auxiliary module,
The imaging module is
An imaging lens for overlapping the IMAGING element,
To the incident light from the Utsushitai focusing on the imaging device, and imaging focus adjustment mechanism for adjusting the position of the imaging lens,
Control means for determining the position of the imaging lens from fine adjustment information or coarse adjustment information and controlling the imaging focus adjustment mechanism to continuously adjust the position of the imaging lens;
The auxiliary module is
An auxiliary lens for overlapping the auxiliary imaging element,
An auxiliary focus adjustment mechanism that is provided separately from the imaging focus adjustment mechanism and adjusts the position of the auxiliary lens so that incident light from the subject is focused on the auxiliary image sensor. ,
The coarse adjustment information is obtained via the auxiliary imaging element based on distance information representing the distance to the subject in order to coarsely adjust the position of the imaging lens, and the fine adjustment information is In order to fine-tune the position of the imaging lens, obtained through the imaging element of the imaging module,
The auxiliary module provides the distance information as the coarse adjustment information;
The automatic focus is characterized in that an adjustment range for the auxiliary focus adjustment mechanism to align the auxiliary lens is smaller than an adjustment range for the imaging focus adjustment mechanism to align the imaging lens. Matching module . The automatic focusing module according to claim 6, wherein the imaging lens of the imaging module moves while the auxiliary lens of the auxiliary module moves . The auxiliary imaging element includes a detectable element the incident light of different wavelengths, and determining the position of the auxiliary lens on the basis of the detection value of each wavelength, according to claim 6 Auto focus module. An automatic focusing mechanism including an imaging module and an auxiliary module,
The imaging module is
An imaging lens for overlapping the IMAGING element,
To the incident light from the Utsushitai focusing on the imaging device, and imaging focus adjustment mechanism for adjusting the position of the imaging lens,
Control means for determining the position of the imaging lens from fine adjustment information or coarse adjustment information and controlling the imaging focus adjustment mechanism to continuously adjust the position of the imaging lens;
The auxiliary module is
An auxiliary lens for overlapping the auxiliary imaging element,
Provided separately from the imaging focus adjustment mechanism, the position of the auxiliary lens is independent of the position of the imaging lens so that incident light from the subject is focused on the auxiliary imaging element. An auxiliary focus adjustment mechanism for adjusting ,
The coarse adjustment information is obtained via the auxiliary imaging element based on distance information representing the distance to the subject in order to coarsely adjust the position of the imaging lens, and the fine adjustment information is In order to fine-tune the position of the imaging lens, obtained through the imaging element of the imaging module,
The auxiliary module provides the distance information as the coarse adjustment information;
The auxiliary focus adjustment mechanism has a first adjustment range for aligning the auxiliary lens of the auxiliary module, and the imaging focus adjustment mechanism aligns the imaging lens of the imaging module. the second comprises an adjustment range, the automatic focusing mechanism adjustment range of said first, characterized in that less than the adjustment range of the second to The auxiliary lens is characterized and-law containing a liquid to be voltage controlled, automatic focusing mechanism according to claim 9.

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