JP2006301150A - Autofocus device - Google Patents

Abstract

An AF device is provided that continues focus adjustment appropriately even if the focus adjustment state cannot be temporarily detected during focus adjustment by a phase difference type focus detection means.
A lens drive control unit of an AF apparatus does not immediately perform a scanning operation when a defocus amount DF cannot be calculated by a defocus amount calculation unit, but contrast information calculated by a contrast calculation unit. Performed when Cnt is less than the predetermined value. The lens drive control unit 8 performs a maximum contrast detection operation by the contrast detection AF method during the periodic pattern. Further, the lens drive control unit 8 stops the driving of the focus lens when the contrast information Cnt is reduced in the process in which the contrast information Cnt is not less than a predetermined value, the defocus amount DF cannot be calculated and the focus lens is being driven. On the other hand, when the contrast information Cnt does not decrease, the driving of the focus lens is continued. In contrast, when the contrast information Cnt is greater than or equal to a predetermined value and the defocus amount DF can be calculated and the process proceeds when the aperiodic pattern is used, the driving of the focus lens is stopped when the contrast information Cnt decreases.
[Selection] Figure 1

Description

  The present invention relates to an autofocus device that detects a focus adjustment state of a photographing lens by a plurality of different methods.

  Separately from the contrast detection autofocus (AF) method for detecting the focus adjustment state of the photographing lens based on the contrast information by the image signal imaged through the photographing lens, and the contrast detection AF method, a plurality of images passing through different regions of the photographing lens. There is known a hybrid AF camera that is equipped with a phase difference detection AF method that detects a focus adjustment state of a photographing lens based on a shift amount of a plurality of images by a focus detection light beam (see Patent Document 1).

  In the technique described in Patent Document 1, focusing is performed by an AF method that can detect the focus adjustment state of both AF methods, or an AF method that has a higher reliability of the detected focus adjustment state.

JP 2001-330767 A

  In the technique described in Patent Document 1, when the focus adjustment state by the phase difference detection AF method cannot be detected temporarily during the focus adjustment, the method shifts to the other contrast method. However, since the methods are independent from each other, lens driving for searching for a state in which the focus adjustment state can be detected is started, and there is a problem that when the subject is temporarily lost, the subject is out of focus.

An autofocus device according to a first aspect of the present invention includes a phase difference type focus detection means for detecting a light flux from a subject to determine a focus adjustment state of the photographing optical system, and an image of the subject light flux that has passed through the photographing optical system. An image pickup means for picking up an image, a contrast detection means for obtaining contrast information based on an image picked up by the image pickup means, and a focus adjustment means for controlling the focus adjustment of the photographing optical system based on the focus adjustment state according to the contrast information. It is characterized by that.
In the autofocus device according to the first aspect, the focus adjustment unit may perform the focus adjustment according to the contrast information when the signal detected by the focus detection unit indicates a subject having a periodic pattern.
2. The autofocus device according to claim 1, wherein when the focus adjustment state cannot be detected, the focus detection unit performs an operation of detecting the focus adjustment state while moving the focus adjustment lens of the photographing optical system according to the contrast information. It can also be determined whether or not.
In the autofocus device according to claim 1 or 2, the focus adjustment unit may stop the focus adjustment when the contrast value detected by the contrast detection unit during the focus adjustment decreases.
5. The autofocus device according to claim 1, wherein the imaging area captured by the imaging unit is wider than the focus area where the focus detection unit detects the focus adjustment state, and includes the focus area. Also good.
According to a sixth aspect of the present invention, there is provided an autofocus device that detects a light flux from a subject and obtains a focus adjustment state of a photographic optical system, a phase difference type focus detection means, and an image of the subject light flux that passes through the photographic optical system. Imaging means for imaging, contrast detecting means for obtaining contrast information based on an image taken by the imaging means, focus adjusting means for adjusting the focus of the photographing optical system according to the focus adjustment state and contrast information, and focus detection And a timing control means for matching the detection time of the luminous flux by the means and the central time of the imaging time by the imaging means.

  In the autofocus device according to the present invention, even if the focus adjustment state cannot be temporarily detected during focus adjustment by the phase difference type focus detection means, the focus adjustment can be continued appropriately.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining a main configuration of an autofocus (AF) apparatus provided in a camera according to an embodiment of the present invention. In FIG. 1, the AF apparatus includes a half mirror 2, an image sensor 3, a contrast calculation unit 4, an AF sensor 5, a defocus amount calculation unit 6, an accumulation control unit 7, and a lens drive control unit 8. An interchangeable photographic lens 1 is mounted.

  The subject luminous flux that has passed through the photographing lens 1 enters the half mirror 2. The half mirror 2 divides the incident light beam into a transmitted light beam that passes through the half mirror 2 and a reflected light beam that reflects off the half mirror 2. The transmitted light beam (contrast detection light beam) is guided to the image sensor 3, and the reflected light beam (defocus amount detection light beam) is guided to the AF sensor 5. The image sensor 3 is a charge accumulation type area sensor for contrast detection AF, and is constituted by a CCD image sensor, a CMOS image sensor, or the like. The AF sensor 5 is a charge accumulation type image sensor for phase difference detection AF, and is constituted by a CCD image sensor, a CMOS image sensor, or the like.

  The contrast calculation unit 4 performs a known focus evaluation value calculation based on the image pickup signal output from the image pickup device 3 to thereby obtain a focus evaluation value (hereinafter referred to as contrast information) obtained by replacing the high frequency component of the image with the sharpness. calculate. The contrast is maximized when the photographing lens 1 is in a focused state where a sharp image is formed on the image sensor 3, that is, when the blur of the edge of the subject image captured by the image sensor 3 is minimal.

  The defocus amount calculation unit 6 performs a known defocus amount calculation based on the accumulated signal output from the AF sensor 5. Specifically, it is an image of a pair of defocus amount detection light beams incident through different regions of the focus detection optical system (in this example, the photographic lens 1), each at a different position on the AF sensor 5. A relative positional deviation amount (relative interval) between two captured images is obtained. The pair of subject images are close to each other in a so-called front pin state in which the photographing lens 1 connects a sharp image of the subject before the planned focal plane, and conversely, a so-called rear pin state in which the sharp image of the subject is connected behind the planned focal plane. Then move away from each other. A pair of subject images on the AF sensor 5 relatively coincide with the in-focus state connecting the sharp image of the subject on the planned focal plane. Therefore, the focus adjustment state of the photographic lens 1, that is, the defocus amount can be obtained by obtaining the relative positional deviation amount between the pair of subject images.

  The accumulation control unit 7 generates a timing signal for controlling the charge accumulation timing of the image sensor 3 and the AF sensor 5 and sends the generated timing signal to each of the image sensor 3 and the AF sensor 5. Details of the charge accumulation timing of the image sensor 3 and the AF sensor 5 will be described later.

  The lens drive control unit 8 drives the focus lens (not shown) constituting the photographing lens 1 based on the defocus amount calculated by the defocus amount calculation unit 6 and the contrast information calculated by the contrast calculation unit 4. And a lens drive signal is sent to a focus lens drive mechanism (not shown). The focus driving mechanism moves the focus lens forward and backward in the optical axis direction in accordance with the lens drive signal, thereby adjusting the focus of the photographing lens 1. The lens drive control unit 8 is also configured to perform sequence control for each block constituting the AF apparatus during the focus adjustment process.

  FIG. 2 shows a defocus amount detection area (that is, a focus area where a defocus amount calculation is performed based on an image signal captured by the AF sensor 5) 23 and a contrast detection area (that is, the image sensor 3) on the shooting screen 21. It is a figure explaining the relationship with the focus area) 22 where contrast calculation is performed based on the imaging signal imaged by 1). As shown in FIG. 2, the contrast detection area 22 is configured to include a defocus amount detection area 23.

  The flow of the focus adjustment process performed by the AF apparatus described above will be described with reference to the flowchart of FIG. The processing in FIG. 3 is activated by the lens drive control unit 8 when an operation signal from a focus adjustment execution switch (not shown) is input to the AF device, for example.

  In step S <b> 1, the lens drive control unit 8 sends a command to the accumulation control unit 7 to start supplying timing signals to the image sensor 3 and the AF sensor 5, and accumulates charges in the image sensor 3 and the AF sensor 5. Start and go to step S2.

  In step S2, the lens drive controller 8 instructs the defocus amount calculator 6 to calculate the defocus amount DF, and instructs the contrast calculator 4 to calculate the contrast information Cnt, and then proceeds to step S3. move on. The defocus amount DF corresponds to the focus adjustment information of the phase difference detection AF method. The contrast information Cnt corresponds to the focus adjustment information of the contrast detection AF method.

  In step S3, the lens drive control unit 8 determines whether or not the defocus amount DF can be calculated. If the defocus amount calculation unit 6 calculates the defocus amount DF, the lens drive control unit 8 makes a positive determination in step S3 and proceeds to step S6. If the defocus amount DF cannot be calculated, the lens drive control unit 8 proceeds to step S6. A negative determination is made in S3 and the process proceeds to step S4. The state in which the defocus amount DF cannot be calculated is, for example, a state in which the main subject is not included in the defocus amount detection area 23 or the focus adjustment state of the photographing lens 1 (focus lens) is far away from the in-focus position. It is in a state.

  In step S4, the lens drive control unit 8 determines whether or not the value of the contrast information Cnt calculated by the contrast calculation unit 4 is greater than or equal to a predetermined value. If the contrast information Cnt is greater than or equal to a predetermined value, the lens drive control unit 8 makes a positive determination in step S4 and proceeds to step S6. If the contrast information Cnt is less than the predetermined value, the lens drive control unit 8 makes a negative determination in step S4 and proceeds to step S5. move on.

  In step S5, the lens drive control unit 8 performs a scanning operation and proceeds to step S9. Details of the scanning operation will be described later. In step S6, the lens drive control unit 8 performs a lens drive control operation to be described later, and proceeds to step S7.

  In step S <b> 7, the lens drive control unit 8 sends a command to the accumulation control unit 7 to start supplying timing signals to the image sensor 3 and the AF sensor 5, and accumulates charges in the image sensor 3 and the AF sensor 5. Start and go to step S8.

  In step S8, the lens drive controller 8 instructs the defocus amount calculator 6 to calculate the defocus amount DF, and instructs the contrast calculator 4 to calculate the contrast information Cnt, and then proceeds to step S9. move on.

  In step S9, the lens drive control unit 8 determines whether or not to end the focus adjustment process in FIG. When the operation signal from the focus adjustment execution switch (not shown) is canceled, the lens drive control unit 8 makes a positive determination in step S9 and ends the process of FIG. If the operation signal from the focus adjustment execution switch is continued, the lens drive control unit 8 makes a negative determination in step S9, returns to step S6, and repeats the processes in steps S6 to S8.

  Details of the scanning operation will be described with reference to a flowchart shown in FIG. In step S101, the lens drive controller 8 sends a lens drive signal to a focus lens drive mechanism (not shown), starts driving the focus lens in a predetermined direction (for example, the closest direction), and proceeds to step S102. Note that the initial setting of the driving direction of the focus lens may be set to infinity.

  In step S102, the lens drive control unit 8 sends a command to the accumulation control unit 7 to start supplying a timing signal to the AF sensor 5, and causes the AF sensor 5 to start charge accumulation, and then proceeds to step S103. In step S103, the lens drive control unit 8 instructs the defocus amount calculation unit 6 to calculate the defocus amount DF, and proceeds to step S104.

  In step S104, the lens drive control unit 8 determines whether or not the defocus amount DF can be calculated. The lens drive control unit 8 makes a positive determination in step S104 when the defocus amount calculation unit 6 calculates the defocus amount DF, and proceeds to step S106. If the defocus amount DF cannot be calculated, the lens drive control unit 8 performs step. A negative determination is made in S104, and the process proceeds to Step S105. When the focus lens that has started driving in the close-up direction reaches the close end, the lens drive control unit 8 in the case of proceeding to step S105 switches the drive direction of the focus lens to the infinity direction and continues to drive the focus lens. On the contrary, when the focus lens starts to be driven in the infinity direction, when the focus lens reaches the infinity end, the drive direction of the focus lens is switched to the closest direction, and the drive of the focus lens is continued.

  In step S105, the lens drive control unit 8 determines whether or not the focus lens has been driven over the entire lens drive range. The lens drive control unit 8 makes an affirmative decision in step S105 when the focus lens is moved over the entire lens drive range and proceeds to step S106. If the entire lens drive range is not moved, the lens drive control unit 8 denies step S105. Determine and return to step S102. Accordingly, when the defocus amount DF cannot be calculated and the contrast information Cnt is less than a predetermined value, a scanning operation for calculating the defocus amount DF while moving the focus lens is performed.

  In step S106, the lens drive control unit 8 stops sending the lens drive signal to the focus lens drive mechanism (not shown), stops the drive of the focus lens, ends the processing in FIG. 4, and proceeds to step S9 in FIG. move on.

  Details of the lens drive control operation will be described with reference to the flowchart shown in FIG. In step S201, the lens drive control unit 8 determines whether or not the defocus amount DF can be calculated. The lens drive control unit 8 makes an affirmative decision in step S201 when the defocus amount calculation unit 6 calculates the defocus amount DF, and proceeds to step S205. If the defocus amount DF cannot be calculated, the lens drive control unit 8 proceeds to step S205. A negative determination is made in S201 and the process proceeds to step S202.

  In step S202, the lens drive control unit 8 determines whether or not the focus lens is being driven. If the focus lens is being driven, the lens drive control unit 8 makes a positive determination in step S202 and proceeds to step S204. If the focus lens is not being driven, the lens drive control unit 8 makes a negative determination in step S202 and proceeds to step S203.

  In step S203, the lens drive control unit 8 stops sending the lens drive signal to the focus lens drive mechanism (not shown), stops the drive of the focus lens, ends the processing in FIG. 5, and proceeds to step S7 in FIG. move on.

  In step S204, the lens drive control unit 8 executes the process of condition 1, ends the process of FIG. 5, and proceeds to step S7 of FIG. Details of the condition 1 processing will be described later.

  In step S205, which proceeds after making an affirmative determination in step S201 described above, the lens drive control unit 8 determines whether the image captured by the AF sensor 5 includes a periodic pattern such as a lattice pattern, for example. To do. When the signal indicating that the periodic pattern is included is input from the defocus amount calculation unit 6, the lens drive control unit 8 makes an affirmative determination in step S205 and proceeds to step S207 to include the periodic pattern. If a signal indicating this is not input, a negative determination is made in step S205, and the process proceeds to step S206. A technique in which the defocus amount calculation unit 6 determines the presence or absence of a periodic pattern is disclosed in, for example, Japanese Patent Laid-Open No. 6-94987. When the process proceeds to step S207, acquisition of focus adjustment information (defocus amount DF) by the phase difference detection AF method is not suitable in principle.

  In step S206, the lens drive control unit 8 executes the process of condition 2, ends the process of FIG. 5, and proceeds to step S7 of FIG. Details of the condition 2 processing will be described later.

  In step S207, the lens drive control unit 8 executes the maximum contrast detection operation, ends the processing in FIG. 5, and proceeds to step S7 in FIG. Details of the maximum contrast detection process will be described later.

  Details of the condition 1 processing will be described with reference to the flowchart shown in FIG. In step S301, the lens drive control unit 8 determines whether or not the calculated contrast information Cnt has decreased. If the contrast information Cnt calculated along with the movement of the focus lens has decreased this time, the lens drive control unit 8 makes an affirmative decision in step S301 and proceeds to step S302. If the contrast information Cnt has not decreased, the lens drive control unit 8 proceeds to step S301. A negative determination is made and processing proceeds to step S303.

  When the process proceeds to step S302, the focus adjustment state of the photographic lens 1 (focus lens) is a state of moving away from the in-focus position. In step S302, the lens drive control unit 8 stops the driving of the focus lens, ends the processing of FIGS. 6 and 5, and proceeds to step S7 of FIG.

  When the process proceeds to step S303, when the main subject is out of the defocus amount detection area 23, the single tone portion of the main subject (the portion where the contrast information necessary for calculating the defocus amount DF is insufficient) is the defocus amount. This is a state located within the detection region 23. In step S303, the lens drive control unit 8 continues to drive the focus lens, ends the processing of FIGS. 6 and 5, and proceeds to step S7 of FIG.

  Details of the condition 2 processing will be described with reference to the flowchart shown in FIG. In step S501, the lens drive control unit 8 determines whether the focus lens is being driven. If the focus lens is being driven, the lens drive control unit 8 makes a positive determination in step S501 and proceeds to step S502. If the focus lens is not being driven, the lens drive control unit 8 makes a negative determination in step S501 and proceeds to step S503.

  In step S502, the lens drive control unit 8 determines whether or not the calculated contrast information Cnt is decreased. If the contrast information Cnt calculated along with the movement of the focus lens has decreased this time, the lens drive control unit 8 makes an affirmative decision in step S502 and proceeds to step S504. If the contrast information Cnt has not decreased, the lens drive control unit 8 proceeds to step S502. A negative determination is made and processing proceeds to step S503.

  When the process proceeds to step S504, the focus adjustment state of the photographic lens 1 (focus lens) is a state away from the in-focus position. In step S504, the lens drive control unit 8 stops the drive of the focus lens, ends the processing of FIGS. 7 and 5, and proceeds to step S7 of FIG.

  When the process proceeds to step S503, when the main subject is out of the defocus amount detection region 23, or when the single tone portion of the main subject (the portion where the contrast information necessary for calculating the defocus amount DF is insufficient) is the defocus amount. This is a state located within the detection region 23. In step S503, the lens drive control unit 8 determines whether or not the value of the defocus amount DF calculated by the defocus amount calculation unit 6 is within a predetermined value. If the defocus amount DF is within the predetermined value, the lens drive control unit 8 makes a positive determination in step S503 and proceeds to step S505. If the defocus amount DF exceeds the predetermined value, the lens drive control unit 8 makes a negative determination in step S503. The process proceeds to S506.

  When the process proceeds to step S505, the focus adjustment state of the photographing lens 1 (focus lens) is in the vicinity of the in-focus position. In step S505, the lens drive control unit 8 executes the maximum contrast detection operation, ends the processing of FIGS. 7 and 5, and proceeds to step S7 of FIG. Details of the maximum contrast detection process will be described later.

  In step S506, the lens drive controller 8 calculates the drive amount of the focus lens (not shown) according to the value of the defocus amount DF calculated by the defocus amount calculator 6, and the focus lens drive mechanism (not shown). ), The lens driving signal is sent to the processing, the processing shown in FIGS. As a result, the focus lens is driven to the in-focus position calculated based on the defocus amount calculation value.

  Details of the processing of the maximum contrast detection operation will be described with reference to the flowchart shown in FIG. In step S601, when the drive of the focus lens is stopped, the lens drive control unit 8 sends a lens drive signal to a focus lens drive mechanism (not shown), starts driving the focus lens, and proceeds to step S602. move on.

  In step S602, the lens drive control unit 8 sends a command to the accumulation control unit 7 to start supplying a timing signal to the image sensor 3, and to start charge accumulation in the image sensor 3, and the process proceeds to step S603.

  In step S603, the lens drive control unit 8 instructs the contrast calculation unit 4 to calculate contrast information Cnt, and the process proceeds to step S604. In step S604, the lens drive control unit 8 determines whether or not the contrast information Cnt is maximum. If the contrast information Cnt is maximum, the lens drive control unit 8 makes a positive determination in step S604 and proceeds to step S605. If the contrast information Cnt is not maximum, the lens drive control unit 8 makes a negative determination in step S604 and returns to step S602. When returning to step S602, the operation of calculating the contrast information Cnt is repeated while moving the focus lens, and the focus lens is driven to the in-focus position based on the calculated contrast value.

  In step S605, the lens drive control unit 8 stops the drive of the focus lens, ends the processes of FIGS. 8, 7, and 5, and proceeds to step S7 of FIG.

  FIG. 9 is a time chart for explaining the charge accumulation timing of the image sensor 3 and the AF sensor 5. At timing t1 after an operation signal from a focus adjustment execution switch (not shown) is input to the AF device, the image sensor 3 starts charge accumulation for the first time. The image sensor 3 ends the first charge accumulation at timing t4 when the charge accumulation time for the image sensor 3 has elapsed, and outputs the image signal to the contrast calculation unit 4. The charge accumulation time (imaging time) for the image sensor 3 is determined by the accumulation controller 7 according to the sensitivity set in the image sensor 3 and the subject brightness detected by a photometric device (not shown).

  At timing t2 after the image pickup device 3 starts the first charge accumulation, the AF sensor 5 starts the first charge accumulation. The AF sensor 5 ends the first charge accumulation at timing t3 when the charge accumulation time for the AF sensor 5 has elapsed, and outputs an accumulation signal to the defocus amount calculation unit 6. The charge accumulation time (imaging time) for the AF sensor 5 is determined by the accumulation control unit 7 in accordance with the sensitivity set in the AF sensor 5 and the subject brightness.

  The accumulation control unit 7 controls the image sensor 3 and the image sensor 3 so that the central time of the charge accumulation time (t1-t4) for the image sensor 3 matches the central time of the charge accumulation time (t2-t3) for the AF sensor 5. The charge accumulation timing of the AF sensor 5 is controlled.

  After the first charge accumulation by the image sensor 3 and the AF sensor 5, the contrast calculation unit 4 calculates the contrast information Cnt, and the defocus amount calculation unit 6 calculates the defocus amount DF. Driving is started.

  Thereafter, similarly, during the driving of the focus lens, the charge accumulation by the imaging device 3 and the AF sensor 5 and the calculation of the contrast information Cnt by the contrast calculation unit 4 and the defocus amount DF by the defocus amount calculation unit 6 are repeatedly performed.

According to the embodiment described above, the following operational effects can be obtained.
(1) Since the contrast detection region 22 is wider than the defocus amount detection region 23 so as to include the defocus amount detection region 23, focus adjustment information (defocus amount DF) by the phase difference detection AF method cannot be calculated (defocus amount detection region 23). Even if the contrast information necessary for the calculation of the focus amount DF is insufficient, it is possible to calculate the focus adjustment information (contrast information Cnt) by the contrast detection AF method.

(2) When the defocus amount DF cannot be calculated, the scanning operation (step S5) is not performed immediately, but the necessity of the scanning operation is determined according to the value of the contrast information Cnt. Since it is performed when the value of the contrast information Cnt is less than the predetermined value (determination is negative in step S4), the single-tone portion of the main subject happens to happen while the focus adjustment state of the photographing lens 1 is near the in-focus position ( When the contrast information necessary for calculating the defocus amount DF is located in the defocus amount detection area 23, the focus lens is not wasted.

(3) When the defocus amount DF can be calculated and a periodic pattern (Yes in step S205), the maximum contrast detection operation (step S207) by the contrast detection AF method is performed, so the phase difference detection AF method is used. There is no false focus.

(4) In the process of condition 1 in which the contrast information Cnt is equal to or greater than a predetermined value (Yes in step S4), the defocus amount DF cannot be calculated and the focus lens is being driven (Yes in step S202), the contrast information Cnt is When it decreases, driving of the focus lens is stopped (step S302), which is effective for a shooting scene in which a fast-moving subject approaches the camera, for example, crosses immediately and moves away instantly. On the other hand, if the contrast information Cnt does not decrease, the focus lens continues to be driven (step S303), so that the phase difference is detected, for example, when the main subject is temporarily out of the defocus amount detection area 23. Even when the focus adjustment information by AF method (defocus amount DF) cannot be calculated, by continuing lens driving while acquiring focus adjustment information (contrast information Cnt) by contrast detection AF method, the movement of the main subject If there is little change from before the temporary disengagement, the in-focus state can be maintained. That is, since the state close to focusing can be maintained by continuing the lens driving, if the main subject is captured again in the defocus amount detection area, focusing can be performed quickly.

(5) In the process of condition 2 in which the contrast information Cnt is equal to or greater than a predetermined value (Yes in step S4), the defocus amount DF can be calculated, and the process proceeds to a non-periodic pattern (determination is negative in step S205), the contrast information Cnt is When it decreases, the driving of the focus lens is stopped (step S504). Thus, even in a situation where the focus adjustment information (defocus amount DF) by the phase difference detection AF method can be calculated, the focus adjustment is performed according to the change state of the focus adjustment information (contrast information Cnt) acquired by the contrast detection AF method. By doing so, for example, when the main subject is temporarily out of the defocus amount detection area 23, it is possible to prevent focusing on another subject.

(6) The image sensor 3 and the AF sensor 5 so that the center time of the charge accumulation time (t1-t4) for the image sensor 3 and the center time of the charge accumulation time (t2-t3) for the AF sensor 5 match. Since the charge accumulation timing is controlled, the acquisition timing of the focus adjustment information (defocus amount DF) by the phase difference detection AF method matches the acquisition timing of the focus adjustment information (contrast information Cnt) by the contrast detection AF method. Thereby, when the focus adjustment information cannot be acquired by the phase difference detection AF method, it can be supplemented by the focus adjustment information acquired by the contrast detection AF method at the same timing.

  In the above description, the AF sensor 5 and the image sensor 3 both receive the image of the light beam that has passed through the photographing lens 1 that is a photographing optical system. However, the AF sensor 5 is different from the photographing lens 1 in the focus detection optical system. It may be configured to receive an image of a light beam that has passed through (so-called external light type). Even in this case, the contrast detection area 22 by the image sensor 3 is configured to include the defocus amount detection area 23 by the AF sensor 5.

  The camera equipped with the AF device may be a silver salt camera or an electronic camera. When the electronic camera includes an AF device, the image sensor 3 may be used also as an image sensor for photographing.

It is a block diagram explaining the principal part structure of the AF apparatus of the camera by one Embodiment of this invention. It is a figure explaining the defocus amount detection area | region and contrast detection area | region in an imaging | photography screen. It is a flowchart explaining the flow of the focus adjustment process performed with AF apparatus. It is a flowchart explaining the detail of scanning operation | movement. It is a flowchart explaining the detail of a lens drive control operation | movement. 10 is a flowchart for explaining details of processing of condition 1; 10 is a flowchart for explaining details of processing of condition 2; It is a flowchart explaining the detail of the process of maximum contrast detection operation | movement. It is a figure explaining an electric charge accumulation timing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shooting lens 3 ... Image sensor 4 ... Contrast calculation part 5 ... AF sensor 6 ... Defocus amount calculating part 7 ... Accumulation control part 8 ... Lens drive control part

Claims (6)

A phase difference type focus detection means for detecting a light flux from a subject and obtaining a focus adjustment state of the photographing optical system;
Imaging means for capturing an image of a subject light flux that has passed through the imaging optical system;
Contrast detection means for obtaining contrast information based on an image captured by the imaging means;
An autofocus apparatus comprising: a focus adjustment unit that controls focus adjustment of the photographing optical system based on the focus adjustment state according to the contrast information. The autofocus device according to claim 1,
The autofocus apparatus, wherein the focus adjustment unit performs the focus adjustment according to the contrast information when the signal detected by the focus detection unit indicates a subject having a periodic pattern. The autofocus device according to claim 1,
When the focus detection unit cannot detect the focus adjustment state, the focus detection unit determines whether to perform an operation of detecting the focus adjustment state while moving the focus adjustment lens of the photographing optical system according to the contrast information. Features an autofocus device. The autofocus device according to claim 1 or 2,
The autofocus apparatus, wherein the focus adjustment unit stops the focus adjustment when a contrast value detected by the contrast detection unit decreases during the focus adjustment. In the autofocus device according to any one of claims 1 to 4,
An autofocus device characterized in that an image pickup area picked up by the image pickup means is wider than a focus area in which the focus detection means detects a focus adjustment state and includes the focus area. A phase difference type focus detection means for detecting a light flux from a subject and obtaining a focus adjustment state of the photographing optical system;
Imaging means for capturing an image of a subject light flux that has passed through the imaging optical system;
Contrast detection means for obtaining contrast information based on an image captured by the imaging means;
Focus adjusting means for adjusting the focus of the photographing optical system in accordance with the focus adjustment state and the contrast information;
An autofocus apparatus comprising: a timing control unit that matches a detection time of the light flux by the focus detection unit with a central time of an imaging time by the imaging unit.

Images