JP2009271428A - Focus detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform exact automatic focus detection even in a state where dust exists. <P>SOLUTION: A focus detection area is divided into a plurality of blocks L, C and R, defocus amount is detected per each block L, C or R, and also existence of the dust is decided per each block L, C or R, and only output from the block L decided as the one in which the dust exists is made ineffective, so that the exact automatic focus detection is achieved by utilizing the remaining blocks C and R even in such a state that the dust exists. The ineffective state of the output from the block L decided as the one in which the dust exists is continued until it is released by an ineffectiveness releasing means, so as to prevent focus detection operation from getting unstable and causing false focusing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a focus detection apparatus for a camera, for example.

  Conventionally, Patent Document 1 discloses a countermeasure when there is dust in an AF optical system in a camera. According to Patent Document 1, when a distance measurement result that is considered to have dust is obtained, after the distance measurement point is treated as invalid, and a distance measurement result that is considered to be correct again is obtained, The distance measuring point is made effective.

Japanese Patent Laid-Open No. 10-55009

  However, according to the technique disclosed in Patent Document 1, the corresponding distance measuring point cannot be used completely while dust is present. Therefore, when the photographer designates a distance measuring point and there is dust at the designated distance measuring point, distance measurement becomes impossible. As a result, the photographer may miss a photo opportunity.

  In addition, when the distance measurement result of the distance measurement point that is marked as dust indicates a distance measurement result by a subject other than the dust, the distance measurement point is regarded as an effective distance measurement point. In this case, the distance is measured with a pattern in which dust and the subject are mixed. For this reason, the distance measurement results of the distance measurement points that have been validated again are in a mixed perspective state, and there is a possibility that correct distance measurement is not performed and false focusing is performed.

  The present invention has been made in view of the above, and an object of the present invention is to provide a focus detection apparatus that can perform accurate automatic focus detection even in a dusty state.

  In order to solve the above-described problems and achieve the object, a focus detection apparatus according to the present invention detects a defocus amount of a photographing lens based on a light beam that has passed through a focus detection optical system and is guided to a focus detection sensor. In the focus detection device that adjusts the focus of the photographing lens based on the detected defocus amount, the defocus amount is divided into a plurality of blocks, and the defocus amount is detected for each block. Corresponding to the amount detection means, the dust presence / absence determination means for determining the presence / absence of dust existing in the focus detection optical system for each of the divided blocks, and the block determined as having dust by the dust presence / absence determination means Invalidation means for invalidating the output of the defocus amount detection means, and the defocus amount detection corresponding to the block determined to have dust Characterized in that it comprises a and disabling continuation means for continuing the invalidation of the output stage.

  Moreover, the focus detection apparatus according to the present invention is characterized in that, in the above invention, the focus detection apparatus further comprises invalidation cancellation means for canceling the continuation of invalidation by the invalidation continuation means.

  In the focus detection apparatus according to the present invention, in the above invention, the invalidation canceling unit cancels the continuation of invalidation when an operation member operated to start a focus adjustment operation is in a non-operation state. It is characterized by that.

  In the focus detection apparatus according to the present invention as set forth in the invention described above, the invalidation canceling unit cancels the continuation of invalidation each time the power switch is turned on.

  The focus detection apparatus according to the present invention divides the focus detection area into a plurality of blocks, detects the defocus amount in units of blocks, determines the presence / absence of dust in units of blocks, and invalidates only the output of blocks with dust Therefore, there is an effect that accurate automatic focus detection can be performed using the remaining blocks even in a dusty state.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a focus detection apparatus according to the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram including a schematic mechanism in a configuration example around an AF of a camera system to which a multi-AF focus detection apparatus according to the present embodiment is applied. Here, an example in which the present invention is applied to a single-lens reflex camera as a camera system is shown. As shown in FIG. 1, the camera system of the present embodiment includes an interchangeable lens 101 and a camera body 110.

  The interchangeable lens 101 is detachable from the camera body 110 via a camera mount (not shown) provided on the front surface of the camera body 110. The interchangeable lens 101 includes a photographing lens 102, a lens driving unit 103, and a lens CPU 104 therein.

  The photographing lens 102 is a focus adjusting lens included in the imaging optical system, and is driven in the optical axis direction (the arrow direction shown in FIG. 1) by a motor (not shown) in the lens driving unit 103. Here, the actual imaging optical system is composed of a combination of a plurality of lenses, but only the photographing lens 102 is shown in FIG. The lens driving unit 103 includes a motor and its driving circuit (motor driver). The lens CPU 104 is a control circuit that controls the lens driving unit 103 and the like, and is configured to be able to communicate with the AF controller 121 in the camera body 110 via the communication connector 105. For example, lens data such as manufacturing variation information and aberration information of the photographing lens 102 stored in advance in the lens CPU 104 is communicated from the lens CPU 104 to the AF controller 121.

  On the other hand, a main mirror 111 is provided in the camera body 110 so as to be positioned on the optical axis of the photographing lens 102. The main mirror 111 is formed of a half mirror at the center, and is rotatably provided as a movable mirror. When the main mirror 111 is in the down position as shown in FIG. 1, a part of a light beam from a subject (not shown) that enters the camera body 110 via the photographing lens 102 in the interchangeable lens 101 is reflected by the main mirror 111. Then, it reaches the eyepiece lens 114 through the focusing screen 112 and the pentaprism 113. Thereby, it is possible to observe the state of a subject (not shown).

  On the other hand, in FIG. 1, when the main mirror 111 is at the up position where it is retracted from the optical path of the photographic lens 102, the light flux from the subject incident through the photographic lens 102 forms an image on the image sensor 123 and is photoelectrically converted. . The image sensor 123 is a solid-state image sensor such as a CCD or CMOS sensor. A signal obtained by the image sensor 123 is input to the system controller 122 and subjected to predetermined image processing.

  When the main mirror 111 is in the down position, a part of the light beam incident on the main mirror 111 is transmitted through the half mirror part and reflected by the sub-mirror 111a disposed on the back surface of the main mirror 111, thereby automatically detecting the focus. The light is guided to an AF optical system 115 as a focus detection optical system for performing (AF). The AF optical system 115 includes a condenser lens 116, a total reflection mirror 117, a separator diaphragm 118, and a separator lens 119. The light beam that has passed through the AF optical system 115 is guided to an AF sensor 120 as a focus detection sensor. The light beam incident on the AF sensor 120 is converted into an electrical signal and input to the AF controller 121 as a sensor output.

  The AF controller 121 realizes functions of a defocus amount detection unit that performs a distance measurement calculation to be described later based on the sensor output input from the AF sensor 120, and further, functions of dust presence / absence determination unit, invalidation unit, and invalidation continuation unit. . Information on the defocus amount, which is a distance measurement result by the AF controller 121, is transmitted to the lens CPU 104. The lens CPU 104 receives the information on the defocus amount and drives the photographing lens 102 to focus through the lens driving unit 103.

  The system controller 122 controls each part in the camera body 110, and transmits a control signal, various adjustment parameters, and the like to the AF controller 121 to control its operation. In addition, the system controller 122 according to the present embodiment realizes the function of the invalidation cancellation unit.

  Next, a configuration example of the electrical system of the camera system according to the present embodiment will be described. FIG. 2 is a schematic block diagram illustrating a configuration example of the electrical system of the camera system according to the present embodiment. This block diagram includes the AF sensor 120, the AF controller 121, the system controller 122, the image sensor 123, and the like described above. Image data obtained from the image sensor 123 is subjected to necessary processing such as AGC processing by the imaging circuit 124, A / D converted by the A / D converter 125, and once taken into the RAM 126 or the like. The RAM 126 stores various types of information and temporarily stores image data obtained from the image sensor 123 side for image processing and the like. The ROM 127 stores a control program executed by the system controller 122 in advance.

  Further, the switch unit 130 includes an operation member 130a for photographing such as a 1st release and a 2nd release, a power switch 130b, and the like. The dial unit 131 is an operation member for various shooting modes, parameter settings, menu selections, and the like. The switch unit 130 and the dial unit 131 are connected to the system controller 122 via the operation unit driver 132 and input operation information. The strobe light emitting unit 133 is controlled by the system controller 122 and is used as auxiliary light for AF in addition to the strobe light emission for photographing, and performs a distance measuring operation while intermittently emitting the strobe light. Furthermore, a power supply unit 134 for supplying power is connected to the system controller 122.

  The LCD 140 provided on the rear side of the camera is controlled by the system controller 122 via the video encoder 141, the LCD driver 142, and the bus 143. In addition to displaying a photographed image, photographing information such as an exposure parameter and focusing by AF. Display and so on. The video encoder 141 outputs image data for display to an external device connected to the video signal output terminal 142a as necessary. Further, an external I / F 144 having a USB terminal 144a to which a USB cable is connected is connected to the bus 143. Furthermore, a media drive 146 for driving a recording medium 145 such as a memory card is provided. The media drive 146 is connected to the system controller 122 via a drive controller 147 and a bus 143.

  Next, the AF optical system 115 and the AF sensor 120 will be described in detail. FIG. 3 is a perspective view schematically showing a secondary image forming system of the AF optical system 115. The light beam reflected by the sub-mirror 111a forms an image on the primary image plane. The luminous flux of the subject imaged on the primary imaging plane is condensed by the condenser lens 116, totally reflected by the total reflection mirror 117, then divided and condensed by the separator lens 119, and the AF optical system 115. The light enters a predetermined area of the AF sensor 120 disposed behind. Here, the AF sensor 120 is assumed to be capable of detecting the focus states of a plurality of distance measuring points (focus detection areas) P1 to P15 in the photographing screen 151 as shown in FIG. 5, for example. Here, the AF sensor 120 includes a horizontal line detection sensor array (vertical pixel array) 120a and a vertical line detection sensor array (horizontal pixel array) 120b arranged in a cross shape.

  FIG. 4 is a conceptual diagram of distance measurement of the AF optical system 115 and the AF sensor 120. In FIG. 4, the total reflection mirror 117 is not shown. For the light beam, only the horizontal line detection light beam for detecting the focus state in the horizontal direction of the photographing screen 151 is shown, and the vertical line detection light beam orthogonal to the horizontal line detection light beam is not shown. In the following description, the horizontal line detection light beam is contrasted, but the same applies to the vertical line detection light beam.

  First, in FIG. 4, a pair of horizontal line detection light beams that have passed through different exit pupils of the photographic lens 102 are reflected by the sub mirror 111a and then imaged on the primary imaging plane. The pair of horizontal line detection light beams imaged on the primary image plane is incident on the condenser lens 116 and condensed. The collected pair of horizontal line detection light beams are totally reflected by the total reflection mirror 117 and then enter the separator lens 119 via the separator diaphragm 118. Each horizontal line detection light beam incident on the separator lens 119 enters a specific region of the horizontal line detection sensor array 120a arranged in the vertical direction.

  Here, with respect to the horizontal line detection light beam, the AF sensor 120 causes one of the pair of horizontal line detection sensor arrays 120a to function as a reference unit and the other as a reference unit. Similarly, the AF sensor 120 causes one of the pair of vertical line detection sensor arrays 120b to function as a reference part and the other as a reference part for the vertical line detection light beam. Further, the AF sensor 120 has a sensor array arrangement as shown in FIG. 6 in order to detect the focus states of 15 distance measuring points P1 to P15 on the photographing screen 150 as shown in FIG. . FIG. 6 is an explanatory view showing a sensor array arrangement in the AF sensor 120 together with a partial enlarged view thereof. That is, the horizontal line detection sensor row 120a is composed of five sensor rows arranged in parallel to each other at equal intervals. The vertical line detection sensor row 120b includes three sensor rows arranged in parallel to each other at equal intervals. Although details will be described later, at each of the distance measuring points P1 to P15, as extracted and shown in the partial enlarged view in FIG. 6, each of the vertical line detection sensor row 120b and the horizontal line detection sensor row 120a is represented by a block L ( The block is divided into three blocks: a left correlation calculation block), a block C (central correlation calculation block), and a block R (right correlation calculation block), and the correlation calculation is performed in units of each block.

  A control example of a distance measurement (focus detection) operation executed by the AF controller 121 in the focus detection apparatus having such a configuration will be described. FIG. 7 is a schematic flowchart showing a control example of the distance measurement calculation operation executed by the AF controller 121. This process is executed as a process in step S102 in the imaging sequence of FIG. In addition, the distance measuring point loop of step S201 to step S215 shown in FIG. 7 is a loop for causing the distance measurement calculation to be executed in a predetermined order for the 15 distance measuring points P1 to P15.

  First, the AF controller 121 converts the sensor output signal input from the A / F sensor 123 into a digital signal by an A / D converter and then executes sensor data acquisition processing for storing the data in an internal memory (step). S202). Here, in the present embodiment, the detection of the focus state of each of the distance measuring points P1 to P15 based on the sensor output of the AF sensor 123 is performed by a correlation calculation method. Therefore, prior to performing the correlation operation, the illuminance correction of the stored sensor data is performed using the correction data for correcting the non-uniformity of the output of the photodiode constituting the pixel column of each distance measuring point of each sensor column. (Step S203). The correction data in this case may be data that corrects variations in sensor data when a uniform luminance surface is observed, for example.

  After the illuminance correction of the sensor data is completed, a correlation calculation is performed (step S204). Here, the correlation calculation is performed between the sensor rows forming a pair, for example, between the sensor rows forming each pair of the horizontal line detection sensor row 120a and the horizontal line detection sensor row 120a, or between the vertical line detection sensor row 120b and the vertical line detection sensor row 120b. This is an arithmetic process for calculating the interval Iz between the two images incident between the sensor rows forming the respective pairs, that is, the amount of image shift. In this correlation calculation, sensor data comparison (correlation value calculation calculation) is performed between paired sensor arrays, and as a result of this comparison, the correlation value is the smallest (correlation value 蛾 the highest). Is calculated (step S205).

  Here, in more detail, the correlation calculation of the present embodiment, as extracted and shown in the enlarged portion in FIG. 6, is a vertical line detection sensor array (horizontal pixel array) 120 b and horizontal line detection at each distance measuring point. The sensor output of the effective pixel portion of the sensor column (vertical pixel column) 120a is divided into three blocks L, C, and R of left (L), center (C), and right (R). For example, as shown in the figure, at the distance measurement point P1, at the corresponding vertical line detection sensor row S1, the pair of correlation calculation blocks L, C, and R, and at the distance measurement point P1, the corresponding horizontal line detection sensor. In the column S1, the correlation calculation is performed for each of the pair of correlation calculation blocks L, C, and R.

  Then, the subject distance and the defocus amount when driving the photographing lens 102 are calculated for each block based on the calculated image shift amount (step S206). The defocus amount is calculated using a defocus coefficient optically calculated with respect to the image shift amount. Further, with respect to the calculated defocus amount of each block, conditions such as correction of variations related to the camera body 110 during manufacture, correction of variations related to the interchangeable lens 101 during manufacture, and the focus lens position and zoom position of the interchangeable lens 101 Various corrections such as aberration correction and temperature correction according to the environmental temperature are performed (step S207).

  Here, when the reliability of the image shift amount calculated as a result of the correlation calculation is low, an erroneous defocus amount may be calculated. Therefore, it is preferable to determine the reliability of the result of the correlation calculation. . Therefore, three blocks L, C, and R of the horizontal pixel row (vertical line detection sensor row 10b) and three blocks L, C, and R of the vertical pixel row (horizontal line detection sensor row 10a) related to each distance measuring point. The determination of reliability regarding a total of six R blocks is sequentially performed (steps S208 to S213).

  After the reliability determination process, the block having the highest reliability is selected from the blocks determined to have reliability among these six blocks (step S214). If it is determined that all of the six blocks are not reliable, the distance measurement point is determined to be unmeasurable (invalid).

  After performing the above processing for 15 distance measuring points P1 to P15 (steps S201 to S215), from among the 15 distance measuring points P1 to P15, excluding those that cannot be measured (invalid), A defocus amount at a distance measuring point indicating the maximum defocus amount (closest distance) is selected (step S216). The AF controller 121 executes such distance measurement calculation processing shown in FIG. 7 as a function of the defocus amount detection means. This example shows an operation example when the closest distance measuring point is automatically selected from among the 15 distance measuring points P1 to P15 in the distance measuring point automatic selection mode. When the final defocus amount is detected in this way, thereafter, as will be described later, determination of whether or not the focus is achieved and driving of the photographing lens 102 are performed.

  Here, in the reliability determination processing for each block in steps S208 to S213, in addition to determining whether there is sufficient contrast or whether the correlation calculation result is appropriate, in the present embodiment, the presence / absence of dust is determined. The process to do is also performed. Therefore, the reliability determination process for each correlation calculation block will be described. FIG. 8 is a schematic flowchart showing a control example of reliability determination processing for each correlation calculation block executed by the AF controller 121. As described above, this process is executed in the reliability determination process for each block in steps S208 to S213. The outline of the dust presence / absence determination method in the present embodiment is that the defocus amount corresponding to the case where distance measurement is performed with a pattern on the most dust-receiving surface (here, the condenser lens 116) in the AF optical system 115. When three consecutive times are detected, it is determined that there is dust on the corresponding AF optical system 115 corresponding to the correlation calculation block. The determination method for determining that there is dust on the condenser lens 116 is a case where the defocus amount is almost on the condenser lens 116 and the contrast is small as a result of the correlation calculation in each block.

  First, it is determined whether or not there is contrast in the block (step S301). The determination of the presence / absence of contrast is performed by comparing the difference between the maximum value and the minimum value of sensor data in the block, the integrated value of the difference between adjacent sensor data in the block, and the like with a predetermined contrast determination value 1. If it is smaller, it is determined that there is no contrast. If there is no contrast (step S301; No), the process is terminated with no reliability (step S313). That is, the correlation calculation result of the block is invalidated.

  On the other hand, when there is contrast (step S301; Yes), it is determined whether or not the minimum correlation value Fmimi calculated in the block is smaller than a predetermined threshold (step S302). When it is large, that is, when the degree of correlation is low (step S302; No), the process is terminated without reliability (step S313). That is, the correlation calculation result of the block is invalidated.

  If it is smaller than the predetermined threshold, that is, if the degree of correlation is high (step S302; Yes), it is determined whether or not the dust flag is set to 1 (step S312). Although the dust flag is described later, if the dust flag is 1 (step S312; Yes), the process is terminated with no reliability (step S313). That is, the correlation calculation result of the block is invalidated.

  When the garbage flag is not set (step S312; No), it is determined whether or not the contrast is smaller than a predetermined contrast determination value 2 (step S303). Here, the contrast determination value 2 is a determination value having a larger contrast than the contrast determination value 1, and is set for dust determination. If the contrast is larger than the contrast determination value 2 (step S303; No), the dust presence data provided corresponding to each block is initialized to 0 (step S307). Then, the process ends with reliability (step S308). That is, the correlation calculation result of the block is valid.

  On the other hand, when the contrast is smaller than the contrast determination value 2 (step S303; Yes), it is determined whether or not the defocus amount detected in the block is within a predetermined specified value range (step S304). The predetermined specified value range is set within a range in which the defocus amount is almost on the condenser lens 116. If the focus amount is not within the predetermined specified value range (step S304; No), the dust presence data provided corresponding to each block is initialized to 0 (step S307). Then, the process ends with reliability (step S308). That is, the correlation calculation result of the block is valid.

  If the defocus amount is within the predetermined specified value range (step S304; Yes), 1 is added to the dust presence data for the block (step S305). Then, it is determined whether or not the cumulative value of the data with dust for the block is 3 or more (step S306). When the accumulated value of the dust presence data is 3 or more (step S306; Yes), the defocus amount is measured with the pattern on the condenser lens 116 continuously three times or more, and it is determined that there is dust. If the cumulative value of the data with dust is smaller than 3 (step S306; No), the process ends as reliable (step S308). That is, the correlation calculation result of the block is valid. The AF controller 121 executes the processing of steps S303 to S306 as a function of the dust presence / absence determination means.

  If the accumulated value of the data with dust is 3 or more (step S306; Yes) and it is determined that there is dust, it is determined that there is no reliability (step S310). That is, the correlation calculation result of the block is invalidated. The AF controller 121 executes the processing of step S310 as a function of invalidating means for invalidating the correlation calculation value corresponding to the block determined to have dust.

  Then, a dust flag provided corresponding to each block is set to 1 (step S311). The garbage flag is a flag for continuing the invalidation process in accordance with the determination result that there is no reliability. As a result, in the reliability determination processing related to the distance measurement calculation results from the next time, the dust flag is set to 1 (step S312; Yes), and therefore the dust presence / absence determination processing in steps S303 to S306 is performed for the block. Without performing the process, the process immediately ends without reliability (step S313). That is, the correlation calculation result of the block is invalidated. As described above, the AF controller 121 executes the processing of steps S311, S312, and S313 as a function of an invalidation continuation unit that continues invalidation of the correlation calculation value corresponding to the block determined to have dust.

  Here, an example of operation when there is such dust will be described with reference to a schematic diagram shown in FIG. FIG. 9 shows the three blocks L, C, and R at a certain distance measuring point, with the horizontal axis as time, and after the 1st release as the operation member 130a is turned on and the AF operation is started, the AF operation is performed. The situation is shown schematically. Here, it is assumed that there is dust on the AF optical system 115 corresponding to the block L.

  First, in ranging 1, the defocus amount is calculated in each correlation calculation block L, C, R. If the calculated defocus amount is within the in-focus range, in-focus display is performed, and the process ends without driving the photographing lens 102. On the other hand, when the calculated defocus amount is out of the focus range, dust is also detected by the reliability determination process (data with dust corresponding to block L = 0 → 1). Then, lens drive 1 is performed for the photographing lens 102 based on the selected defocus amount. In the following description, the case where the defocus amount is within the in-focus range will be omitted.

  Even in the distance measurement 2, even if the photographic lens 102 is driven, an image due to dust located on the condenser lens 116 does not change on the AF sensor 120, so that the defocus amount is determined to be within a predetermined range and dust detection is performed. (Dust data corresponding to block L = 1 → 2). Then, the lens drive 2 is performed with respect to the photographing lens 102 based on the selected defocus amount.

  Even in the distance measurement 3, even if the photographing lens 102 is driven, an image due to dust located on the condenser lens 116 does not change on the AF sensor 120, so that the defocus amount is determined to be within a predetermined range, and dust detection is performed. (Dust data corresponding to block L = 2 → 3). In this case, there is dust for the block L three times continuously in ranging 1 to ranging 3, and the data with dust is 3 or more. Therefore, the ranging result of the block L is invalid as being unreliable. Is done. Then, based on the defocus amount selected from the blocks C and R, the lens driving 3 is performed for the photographing lens 102. Further, the dust flag corresponding to the block L is set to 1, and the ranging result of the block L is continuously invalidated.

  Therefore, after ranging 4, the invalidation of the ranging result is continued without performing the dust presence determination for the block L, and the lens driving 4 and later are performed based on the ranging results of the remaining block C or block R. Is done.

  Here, usually, if there is only one garbage, it is only present in one or two blocks, and the remaining two or one block often shows a correct distance measurement result. Therefore, as in this embodiment, only the blocks with dust are invalidated, and the distance is measured with the remaining blocks where there is no dust. Accurate automatic focus detection can be performed. Therefore, it is possible to avoid missing a photo opportunity.

  Next, an imaging sequence operation executed by the system controller 122 will be described. FIG. 10 is a schematic flowchart showing the photographing sequence operation. This photographing sequence operation is started when the first release, which is the operation member 130a in the switch unit 130, is turned on. Therefore, it is determined whether or not the first release is on (step S101). If the 1st release is turned on (step S101; Yes), the AF controller 121 is controlled to execute the ranging calculation process shown in FIG. 7 (step S102). Then, as a result of the distance calculation, it is determined whether or not there is a distance measuring point capable of distance measurement (step S103). If there is a distance measuring point that can be measured (step S103; Yes), it is determined whether or not the defocus amount of the selected distance measuring point is within a predetermined focusing range (step S104). If it is within the focus range (step S104; Yes), focus display is performed through the LCD 140 (step S105). Then, it is determined whether or not the 2nd release is turned on (step S106). If the 2nd release is turned on (step S106; Yes), the imaging sequence is executed (step S107).

  On the other hand, if it is not within the focusing range in step S104, the defocus amount calculated at the selected distance measuring point is transmitted to the lens CPU 104, and the lens driving unit 103 is sent to the lens CPU 104 according to the defocus amount. The focus driving for driving the photographing lens 102 is executed via the step (step S108).

  In step S103, if it is impossible to measure the distance at all distance measuring points, it is determined whether there is dust by referring to the dust flag (step S110). If there is dust (step S110; Yes), a warning display indicating that there is dust is displayed through the LCD 140 (step S111). Here, since the dust flag is provided corresponding to each block of each distance measuring point, for example, if there is no dust at the distance measuring point manually selected by the photographer, the distance measurement not selected by the photographer. Even if there is dust at the point, it is not necessary to display the warning that there is dust. Further, when there is no dust at the automatically selected distance measuring point, it is not necessary to display the warning that there is dust similarly at other distance measuring points.

  If no dust is present in step S110, it is determined whether or not the strobe light emitting unit 133 emits auxiliary light to perform distance measurement (step S112). If distance measurement is not performed using auxiliary light (step S112; No), emission of auxiliary light is started (step S116), and the process returns to step S101 to perform distance measurement with auxiliary light emitted. Execute.

  On the other hand, if distance measurement has been performed using auxiliary light (step S112; Yes), scan AF processing is performed to perform distance measurement while scanning the photographing lens 102 (step S113). Then, as a result of the scan AF process, it is determined whether or not there is a distance measuring point capable of distance measurement (step S114). If distance measurement is possible (step S114; Yes), the process returns to step S101, and distance measurement is performed again at the position of the photographic lens 102 that has been found by the scan AF process and becomes capable of distance measurement. On the other hand, if distance measurement is impossible (step S114; No), a warning indicating that distance measurement is not possible is displayed through the LCD 140 (step S115).

  When the first release is not turned on (step S101; No), the dust flag and the dust data set for each block are initialized (cleared) to 0 (step S120). The system controller 122 executes the process of step S120 as a function of invalidation cancellation means for canceling the continuation of invalidation based on an operator operation. That is, the continuation of the invalidation is canceled when the first release operated to start the focus adjustment operation becomes a non-operation state (off).

  As described above, in this embodiment, every time the 1st release is turned on, the presence or absence of dust is checked for each distance measurement point in units of blocks, and it is determined that there is dust once for the blocks in which the 1st release is on. Then, the distance measurement result is invalidated and the dust flag is set, and the invalidation of the distance measurement result corresponding to the corresponding block is continued. Then, the continuation of the invalidation is canceled only when the first release is turned off. Therefore, while the first release is on, the situation changes due to the movement of the subject, and an unstable situation in which the dust image and the subject image are mixed may occur, but it was once determined that there was dust. Invalidation continues for the block and will not be activated halfway under unstable circumstances. Thereby, unstable focus detection is not performed while the first release is on, and focus detection accuracy can be improved.

  In the present embodiment, the invalidation canceling unit releases the continuation of invalidation by operating the first release from the on state to the off state, but is not limited thereto. For example, the continuation of invalidation may be canceled every time the power switch 130b is turned on. FIG. 11 is a schematic flowchart showing a processing example when the power switch is turned on, which is executed by the system controller 122, as a modified example. Since the operation of the entire system starts when the power switch 130b is turned on, it is first determined whether or not the power switch 130b is turned on (step S10). If it is not turned on (step S10; No), it waits until it is turned on. On the other hand, when the power switch 130b is turned on (step S10; Yes), the dust presence flag and the dust presence data set in units of blocks are initialized (cleared) to 0 (step S11). The system controller 122 executes the process of step S11 as a function of invalidation cancellation means for canceling the continuation of invalidation based on an operator operation. That is, the continuation of invalidation is canceled every time the power switch is turned on. And each part in a camera is initialized (step S12) and various operation | movement is enabled.

  FIG. 12 is a schematic flowchart showing a photographing sequence operation executed by the system controller 122 in this modification. This process example is the same as the process example shown in FIG. 10 except that the process of step S120 is deleted, and a description thereof will be omitted.

  According to this modification, when it is determined that there is dust for a certain block, the dust flag for the block is set at that time, and the dust flag is not cleared in the photographing sequence, and the power switch 130b is cleared. This is continued until the power switch 130b is turned on again. That is, the dust flag remains set until the power switch 130b is substantially turned off, and the invalidation of the distance measurement result of the corresponding block is continued.

  Therefore, according to the present modification, when the power switch 130b is in the ON state, the photographing sequence is repeated several times. However, once the presence of dust is detected for a certain block, normally, unless the dust is removed, It is estimated that there is no change in the situation where there is dust in the block, and invalidation is continued for the block until the power switch 130b is turned off, thereby eliminating processing such as useless reliability determination and the focus detection operation. Can be performed appropriately. In particular, when the first release is turned off and the subject situation changes, in a situation where the dust image and the subject image are mixed, unstable focus detection is determined to be reliable despite the presence of dust. Can be prevented.

  The present invention is not limited to the above-described embodiments and modifications, and various modifications can be made without departing from the spirit of the present invention. For example, when the presence of dust is detected for a certain block, a warning that dust is present is displayed on the LCD 140, the dust is removed by cleaning the surface of the condenser lens 116, etc., and the photographer indicates that the dust has been removed by setting the LCD display menu. It is also possible to leave the waste flag set until it is set, clear the dust flag at the time of this operation setting, and cancel the continuation of invalidation of the block.

  Alternatively, if the dust detection mode is prepared as one of the menu settings for the LCD display and the dust detection mode is selected, the presence / absence of dust is determined on a block basis for all distance measuring points, and which blocks at which distance measuring points have dirt. May be displayed on the screen of the LCD 140 to warn.

FIG. 2 is a block diagram illustrating a configuration example around an AF of a camera system to which a multi-AF focus detection apparatus according to an embodiment of the present invention is applied, including a schematic mechanism. It is a schematic block diagram which shows the structural example of the electrical equipment system of the camera system of this Embodiment. It is a perspective view which shows typically the secondary image formation system of AF optical system. It is a distance measuring conceptual diagram of an AF optical system and an AF sensor. It is explanatory drawing which shows the mode of the some ranging point in an imaging | photography screen. It is explanatory drawing which shows the sensor array arrangement | positioning in AF sensor with the one part enlarged view. It is a schematic flowchart which shows the example of control of ranging calculation operation | movement. It is a schematic flowchart which shows the example of control of the reliability determination process for every correlation calculation block. It is a schematic diagram which shows the operation example at the time of garbage. It is a schematic flowchart which shows imaging | photography sequence operation | movement. It is a schematic flowchart which shows the example of a process at the time of power switch turning on as a modification. It is a schematic flowchart which shows the imaging | photography sequence operation | movement of a modification.

Explanation of symbols

102 Shooting lens 115 AF optical system 120 AF sensor P1 to P15 Distance measuring point 130a Operation member 130b Power switch

Claims (4)

In a focus detection device that detects a defocus amount of a photographing lens based on a light beam that has passed through a focus detection optical system and is guided to a focus detection sensor, and performs focus adjustment of the photographing lens based on the detected defocus amount ,
A defocus amount detection unit that divides a plurality of focus detection regions into a plurality of blocks and detects a defocus amount in units of each block;
A dust presence / absence determining means for determining the presence / absence of dust existing in the focus detection optical system for each of the divided blocks;
Invalidating means for invalidating the output of the defocus amount detecting means corresponding to the block determined as having dust by the dust presence / absence determining means;
Invalidation continuation means for continuing invalidation of the output of the defocus amount detection means corresponding to the block determined to be dusty;
A focus detection apparatus comprising:   The focus detection apparatus according to claim 1, further comprising invalidation cancellation means for canceling the continuation of invalidation by the invalidation continuation means.   The focus detection apparatus according to claim 2, wherein the invalidation canceling unit cancels the continuation of invalidation when an operation member operated to start a focus adjustment operation is in a non-operation state.   The focus detection apparatus according to claim 2, wherein the invalidation canceling unit cancels continuation of invalidation each time the power switch is turned on.

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