JP2009014850A - Photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device where the display state of a through-image is kept nearly uniform even when luminance in field is changed while achieving speeding-up in AF and reduction of power consumption as in the conventional manner. <P>SOLUTION: A contrast AF means is constituted of an AF control part in a CPU 110, a motor driver, a focus lens and a CCD, and is equipped with a wobbling mode instead of a continuous AF mode, and then the focus lens is operated in the wobbling mode when luminance shows brightness darker than predetermined brightness (under Ev6). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photographing apparatus that forms an image of a subject by forming an image of the subject on an image sensor with a photographing optical system.

  When the photographic optical system provided in the digital camera includes a focus adjustment element that adjusts the focus by movement, the focus is adjusted by detecting the contrast peak of the image obtained by the image sensor while moving the focus adjustment element. In many cases, AF called contrast AF (Auto Focus) is performed.

  In this contrast AF, the focus adjustment element is normally stopped before the release button is operated, and the focus adjustment element is moved from one end of the moving range to the other when the release button is operated. A focus adjustment element is disposed where the in-focus position is detected. At this time, the contrast of the image obtained by the imaging element is detected at predetermined intervals while moving the focus adjustment element from one end of the moving range toward the other, and the detected contrast difference is obtained at predetermined intervals. Therefore, so-called hill-climbing control is performed in which the focus adjustment element is arranged at the position where the difference has changed from positive to negative at the peak of contrast.

  However, when the focus adjustment element is moved from one end of the moving range to the other when the release button is operated, for example, when the subject brightness is low, the focus is once for obtaining contrast due to insufficient light quantity. If the photographing time is long, it may take a long time to detect the in-focus position, and the photo opportunity may be missed. Therefore, in situations where it takes a long time to detect the in-focus position, including situations where the subject brightness is low, the focus lens is continuously moved to the in-focus position before the release button is operated, and There has been proposed a technique that enables the focus adjustment element to be immediately placed at the in-focus position even if the orientation to be changed is changed. This technique is called continuous AF, and when this continuous AF is used, high-speed AF is realized. In the following description, normal contrast AF is referred to as single AF in order to distinguish it from continuous AF.

  The applicant adopts the above-mentioned continuous AF, and when the subject brightness is darker than a predetermined brightness, the single AF is not used but the continuous AF is used to speed up the AF. A technique for achieving this is proposed in an unpublished Japanese Patent Application No. 2006-230338.

  Further, Patent Document 1 proposes a technique for speeding up AF at the time of moving image shooting by performing a wobbling operation of a focus adjustment element without using the above-described continuous AF. In this patent document 1, when the contrast of the in-focus position is lowered, for example, when the direction of the taking lens is changed after focusing once in moving image shooting, the start of the wobbling operation is delayed to drive the lens after panning. Techniques have been proposed for preventing the wrong direction. However, the above-mentioned Patent Document 1 has a problem that the power consumption increases as in the case of continuous AF because the focus adjustment element constantly performs a wobbling operation in order to increase the AF speed in moving image shooting. Yes.

  Further, Patent Document 2 proposes a technique for switching the continuous AF mode to the single AF mode when the subject brightness is darker than a predetermined value and increasing the distance measurement accuracy using AF auxiliary light. In Patent Document 2, nothing is considered about speeding up AF.

  By the way, in the camera proposed in the application of Japanese Patent Application No. 2006-230338 that has not been disclosed by the present applicant, when the subject brightness becomes darker than the predetermined brightness, the AF mode is changed to the single AF mode by the contrast AF means. The continuous AF mode is automatically switched to the continuous AF mode, and the through image that is in focus is immediately displayed on the display screen regardless of which direction the photographing lens provided in the camera is directed.

For this reason, when the user carries the camera proposed in the application of Japanese Patent Application No. 2006-230338 and walks while taking the photographic lens in various directions, the field of view may move from a bright place to a dark place. If the scene is bright, a blurred live view may be displayed each time the direction of the taking lens is changed.On the other hand, as soon as the scene gets dark, Even if it is pointed at, the focus-through image will always be displayed. This difference in the display state on the display screen may make the user feel confused.
JP-A-6-86142 JP 2003-295039 A

  In view of the above circumstances, the present invention aims to increase the AF speed and reduce power consumption in the same manner as in the past, and to ensure that the display state of a through image is maintained substantially uniform even when the field luminance changes. The purpose is to provide.

A first imaging device of the present invention that achieves the above object is an imaging device that forms an image of an object on an image sensor with an imaging optical system to generate an image representing the object.
The photographing optical system includes a focus adjustment element that performs focus adjustment by movement,
A release button for receiving shooting instructions,
Contrast AF means for detecting the in-focus position by detecting the contrast of an image obtained by the image sensor while moving the focus adjustment element, and before the release button is operated. Single AF mode in which the focus position is detected by moving from one end of the moving range to the other when the release button is operated, and the focus adjustment element is set to a middle position in the moving range. Before the release button is operated, a wobbling operation is performed to recognize the in-focus direction, and when the release button is operated, the focus adjustment element is moved from the current position to the in-focus direction. Contrast AF means having two modes, a wobbling mode for detecting the in-focus position,
Photometric means for measuring the brightness of the subject,
The contrast AF unit is configured to perform the single AF according to whether the brightness of the subject measured by the photometry unit is equal to or higher than a predetermined brightness, or less than the predetermined brightness. It operates in the mode or operates in the wobbling mode.

  According to the first photographing apparatus of the present invention, the brightness of the subject measured by the photometry unit is greater than or less than a predetermined brightness by the contrast AF unit. The single AF mode and the wobbling mode are respectively switched depending on whether it is true.

  In the wobbling mode, before the release button is operated by the contrast AF means, the focus adjustment element moves back and forth around the halfway position before the release button is operated. Since only the direction of the focus is recognized, the focus adjustment element may be continuously moved and placed at the in-focus position before the release button is operated as in the conventional continuous AF mode. Absent. For this reason, the load of the contrast AF means is reduced more than before, and the power consumption of the photographing apparatus is suppressed.

  Also, in the wobbling mode, the focus adjustment element is moved back and forth around the middle position of the moving range before the release button is operated, so that the direction of focus is recognized by the contrast AF means. When operated, the focus adjustment element quickly moves in the in-focus direction recognized in advance, and the contrast AF is completed within a short time.

  Further, in the wobbling mode, the focus adjustment element moves back and forth before the release operation is performed, so that the focusing direction is recognized only by the contrast AF means, and the focus adjustment is performed as in the conventional continuous AF mode. Since the element is not constantly moved to the in-focus position, even if the single AF mode and the wobbling mode are switched according to the brightness of the subject brightness, the through image is displayed in almost the same display state, which is confusing to the user. No longer make you feel.

In addition, a second imaging device of the present invention that achieves the above-described problem is an imaging device that forms an image of a subject on an image sensor with a photographing optical system and generates an image representing the subject.
The photographing optical system includes a focus adjustment element that performs focus adjustment by movement,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element;
Distance recognition means different from the contrast AF means for recognizing the subject distance;
A photometric means for measuring the brightness of the subject;
With a release button for receiving shooting instructions,
The contrast AF means is
The focus adjustment element is stopped before the release button is operated, and when the release button is operated, the focus adjustment element is moved from one end of the moving range to the other to detect the in-focus position. 1 single AF mode,
Before the release button is operated, the focus adjustment element is stopped at a position in the middle of the movement range of the focus adjustment element to obtain subject distance information recognized by the distance recognition means, and the release button is operated. In response, the second single AF mode for detecting the in-focus position by moving the focus adjustment element from the current position in the in-focus direction;
The focus adjustment element is placed in the middle of the moving range, a wobbling operation is performed before the release button is operated to recognize the in-focus direction, and the focus adjustment element is moved in response to the operation of the release button. It has three modes, the wobbling mode for detecting the in-focus position by moving from the current position in the in-focus direction,
The contrast AF means is
When the subject measured by the photometric means is brighter than a predetermined brightness, it operates in the first single AF mode,
When the subject measured by the photometry means has a brightness less than a predetermined brightness and subject distance information is obtained from the distance recognition means, the second single AF mode is operated.
When the subject measured by the photometry means has a brightness less than a predetermined brightness and subject distance information cannot be obtained from the distance recognition means, it operates in the wobbling mode. .

  According to the second imaging device for achieving the above object, in addition to the configuration of the first imaging device of the present invention, a distance recognition unit different from the contrast AF unit for recognizing the subject distance is provided. . When the object distance is recognized by the other distance recognition unit, the contrast AF unit executes contrast AF called the second single AF mode.

  Accordingly, the contrast AF means executes contrast AF in the second single AF mode when the subject distance is recognized by the other distance recognition means. In the second single AF mode, instead of moving the focus adjustment element back and forth in the wobbling mode to detect the focus direction, the focus adjustment element is recognized by the other distance recognition means. Since the lens is moved in that direction, it is possible to obtain an effect that power consumption is reduced by not driving the focus adjustment element.

  That is, in the second photographing apparatus of the present invention, when the other distance recognition means can be used, the second single AF mode is executed based on the recognition result of the other distance recognition means. Thus, it is possible to further reduce power consumption by reducing the number of times of contrast AF in both the single AF mode and the wobbling mode of the first photographing apparatus of the present invention.

Here, the distance recognition means may be a distance measurement means provided separately from the contrast AF means,
The distance recognizing means includes a face recognizing means for recognizing a face from an image obtained by the image sensor, and recognizes a subject distance based on a size of the face recognized by the face recognizing means. There may be.

A third photographing apparatus of the present invention that achieves the above-described object is a photographing apparatus that forms an image of a subject by forming an image of the subject on an image sensor with a photographing optical system.
The photographing optical system includes a zooming element that changes a focal length by movement and a focus adjustment element that performs focus adjustment by movement,
A release button for receiving shooting instructions,
Contrast AF means for detecting the in-focus position by detecting the contrast of an image obtained by the image sensor while moving the focus adjustment element, and before the release button is operated. Single AF mode in which the focus position is detected by moving from one end of the moving range to the other when the release button is operated, and the focus adjustment element is set to a middle position in the moving range. Before the release button is operated, a wobbling operation is performed to recognize the in-focus direction, and when the release button is operated, the focus adjustment element is moved from the current position to the in-focus direction. Contrast AF means having two modes, i.e., a wobbling mode for detecting the in-focus position,
The contrast AF means operates in the single AF mode depending on whether the focal length of the photographing optical system is a focal length greater than or equal to a predetermined focal length or less than the predetermined focal length, respectively. Alternatively, it operates in the wobbling mode.

  As is well known, when the focal length of the photographing optical system is equal to or greater than a predetermined focal length, the depth of field becomes shallow, and the focus lens must be moved at finer intervals during contrast AF. The time required for AF is longer than when shooting with a distance shooting optical system.

  Therefore, in the third photographing apparatus of the present invention, the contrast AF unit is configured to perform the single AF mode depending on whether or not the focal length of the photographing optical system is equal to or larger than a predetermined focal length. , Operate in the wobbling mode.

  In the wobbling mode, before the release button is operated by the contrast AF means, the focus adjustment element moves back and forth around the halfway position before the release button is operated. Since only the direction of the focus is recognized, the focus adjustment element may be continuously moved and placed at the in-focus position before the release button is operated as in the conventional continuous AF mode. Absent. For this reason, the load of the contrast AF means is reduced more than before, and the power consumption of the photographing apparatus is suppressed.

  Also, in the wobbling mode, the focus adjustment element is moved back and forth around the middle position of the moving range before the release button is operated, so that the direction of focus is recognized by the contrast AF means. When operated, the focus adjustment element quickly moves in the in-focus direction recognized in advance, and the contrast AF is completed within a short time.

  Further, in the wobbling mode, the focus adjustment element moves back and forth before the release operation is performed, so that the focusing direction is recognized only by the contrast AF means, and the focus adjustment is performed as in the conventional continuous AF mode. Since the element is not constantly moved to the in-focus position, even if the single AF mode and the wobbling mode are switched depending on the brightness of the subject brightness, a through image in almost the same state is displayed, and the user is confused. There is no feeling.

In addition, a fourth imaging device of the present invention that achieves the above-described problem is an imaging device that forms an image of a subject on the image sensor with a photographing optical system and generates an image representing the subject.
The photographing optical system includes a zooming element that changes a focal length by movement and a focus adjustment element that performs focus adjustment by movement,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element;
Distance recognition means different from the contrast AF means for recognizing the subject distance;
With a release button for receiving shooting instructions,
The contrast AF means is
The focus adjustment element is stopped before the release button is operated, and when the release button is operated, the focus adjustment element is moved from one end of the moving range to the other to detect the in-focus position. 1 single AF mode,
Before the release button is operated, the focus adjustment element is stopped at a position in the middle of the movement range of the focus adjustment element to obtain subject distance information recognized by the distance recognition means, and the release button is operated. In response, the second single AF mode for detecting the in-focus position by moving the focus adjustment element from the current position in the in-focus direction;
The focus adjustment element is placed in the middle of the moving range, a wobbling operation is performed before the release button is operated to recognize the in-focus direction, and the focus adjustment element is moved in response to the operation of the release button. It has three modes, the wobbling mode for detecting the in-focus position by moving from the current position in the in-focus direction,
The contrast AF means is
When the focal length of the photographing optical system is less than a predetermined distance, the first single AF mode is operated.
When the focal length of the photographing optical system is not less than a predetermined distance and subject distance information is obtained from the distance recognizing means, the second single AF mode is operated.
When the focal length of the photographing optical system is not less than a predetermined distance and subject distance information cannot be obtained from the distance recognizing means, the photographing optical system operates in the wobbling mode.

  According to the fourth imaging apparatus for achieving the above object, in addition to the configuration of the third imaging apparatus of the present invention, a distance recognition means different from the contrast AF means for recognizing the subject distance is provided. . When the object distance is recognized by the other distance recognition unit, the contrast AF unit executes contrast AF called the second single AF mode.

  Accordingly, the contrast AF means executes contrast AF in the second single AF mode when the subject distance is recognized by the other distance recognition means. In the second single AF mode, instead of moving the focus adjustment element back and forth in the wobbling mode to detect the focus direction, the focus adjustment element is recognized by the other distance recognition means. As a result, the power consumption is further reduced.

  That is, in the fourth photographing apparatus of the present invention, when the other distance recognition unit can be used, the second single AF mode is executed based on the recognition result of the other distance recognition unit. Thus, it is possible to further reduce power consumption by reducing the number of times of contrast AF in both the single AF mode and the wobbling mode of the first photographing apparatus of the present invention.

Here, even if the distance recognition means is a distance measurement means provided separately from the contrast AF means,
The distance recognition means includes face recognition means for recognizing a face from an image obtained by the image sensor, and recognizes a subject distance based on the size of the face recognized by the face recognition means. Also good.

  Further, in the first photographing apparatus or the third photographing apparatus of the present invention, a photographed image obtained by focus adjustment in the single AF mode is added to the photographed image generated in response to the operation of the release button. It is preferable that the recording apparatus further includes a recording unit for storing information indicating whether the image is an image or a captured image obtained by focus adjustment in the wobbling mode.

  In the second photographing apparatus or the fourth photographing apparatus of the present invention, the photographed image is obtained by focus adjustment in the first single AF mode on the photographed image generated in response to the operation of the release button. Information indicating whether it is a captured image, a captured image obtained by focus adjustment in the second single AF mode, or a captured image obtained by focus adjustment in the wobbling mode. It is preferable that the recording device stores recording means.

  As described above, as in the conventional case, an AF device that achieves higher AF speed and lowers power consumption, and realizes an imaging device that can maintain the display state of a through image almost uniformly even if the field luminance changes. To do.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a digital camera which is an embodiment of a photographing apparatus of the present invention.

  FIG. 1 is a perspective view of a digital camera 100 according to an embodiment of the present invention. FIG. 1A shows a perspective view seen from above the front, and FIG. 1B shows a perspective view seen from above the back.

  As shown in FIG. 1A, a lens barrel 111 is provided at the center of the body of the digital camera 100 of the present embodiment, and a finder 105 is provided above the lens barrel 111. A shooting auxiliary light emission window 161 is provided on the side of the viewfinder 105.

  As shown in FIG. 1B, an operation unit 101 for performing various operations when the user uses the digital camera 100 is provided on the back and top surfaces of the digital camera 100 of the present embodiment. .

  In addition to the power switch 101a for operating the digital camera 100, the operation unit 101 includes a cross key 101b, a menu / OK key 101c, a cancel key 101d, a mode lever 101e, and the like. Depending on the mode lever 101e in the operation unit 101, switching between the reproduction mode and the shooting mode, and further switching between the moving image mode and the still image mode in the shooting mode are performed. When the power switch 101a is turned on while the mode lever 101e is switched to the shooting mode, a through image is displayed on the LCD 150, and the shutter release button 102 is pressed at a photo opportunity while viewing the through image. The subject is photographed. In the moving image mode, when the release button 102 is toggled and the release button is pressed once, the moving image shooting is started, and when the release button is pressed again, the moving image shooting is ended. When the mode lever 101e is switched to the reproduction side, the already captured image is reproduced and displayed on the LCD 150.

  FIG. 2 is a block diagram showing an internal configuration of the digital camera shown in FIG.

  The flash light emitting device that emits flash light from the finder 105 and the flash light emission window 161 described in FIG. 1 is not shown in FIG. 2 because it is not directly related to the present invention.

  As shown in FIG. 2, the operation of the digital camera 100 shown in FIG. 1 is comprehensively controlled by the CPU 110, and the CPU 110 has a built-in memory 110A. The memory 110A stores a program indicating a processing procedure, and the CPU 110 executes the processing according to the program procedure in the memory 110A.

  In this embodiment, the CPU 110 functions as a supervisor, and comprehensively manages the progress of the processes of the image processing circuit 142 and the compression / decompression circuit 144. Therefore, when a signal indicating a process start is supplied from the CPU 110 to the image processing circuit 142, the image processing circuit 142 starts image processing, and receives a signal of the operation end of the image processing circuit 142 from the CPU 110 to the compression / decompression circuit 144. When a signal indicating a process start is supplied to the compression / decompression circuit 144, the compression / decompression circuit 144 starts the compression process. Further, the CPU 110 performs a recording process when the compression / decompression circuit 144 receives a signal to end the operation of the compression process.

  The CPU 110 also includes an AE (Auto Exposure) control unit 110B and an AF (Auto Focus) control unit 110C. The AE control unit is based on image data transferred to the CPU 110 via the bus Bus. The photometry is performed at 110B, and the distance is measured by the AF control unit 110C.

  An operation unit 101 such as a release button 102 and a power switch 101 a is provided on the input side of the CPU 110, and a timing generator (hereinafter referred to as TG) 1101 and a motor driver 1102 are provided on the output side. In response to the operation of the operation unit 101, the CPU 110 sets predetermined parameters in each circuit of FIG. 2, and controls the operation of the TG 1101 and the motor driver 1102 in accordance with the operation of the release button 102 to perform shooting processing. Execute.

  Here, the internal configuration and operation of the digital camera 100 of FIG. 1 will be briefly described with reference to FIG.

  The imaging optical system 1110 shown on the left side of FIG. 2 includes a zoom lens 1111 for changing the focal length, a focus lens 1112 for adjusting the focal length, and a diaphragm 1113 for adjusting the exposure. Yes. The zoom lens 1111 is moved along the photographing optical axis by being driven by the zoom motor ZM to adjust the focal length, and the focus lens 1112 is moved back and forth along the photographing optical axis by being driven by the focus motor FM. Thus, the focal point is adjusted, and the iris 1113 is driven by the iris motor IM, whereby the aperture diameter changes to adjust the amount of light given to the image sensor, that is, the exposure.

  Each motor ZM, FM, IM is connected to the CPU 110 via the motor driver 1102 described above, and operates in accordance with an instruction from the CPU 110.

  A CCD image sensor (hereinafter referred to as CCD) 120 is provided behind the photographing optical system. The CCD 120 includes a photoelectric conversion surface on which a plurality of photoelectric conversion elements are arranged as is well known, photoelectrically converts subject light incident on the photoelectric conversion surface, obtains image data, and outputs the image data. A TG 1101 controlled by the CPU 110 is connected to the CCD 120, and the shutter speed of the electronic shutter (the charge accumulation time in each photoelectric conversion element) is determined by a timing signal (clock pulse) input from the TG 1101. When the mode lever 101e provided in the digital camera of FIG. 1 is switched to the shooting mode, the image data for the through image with the reduced number of pixels is output from the CCD 120, and the through image based on the image data for the through image is output on the LCD 150. Is displayed. When the release button 102 is fully pressed while the through image is displayed, the output of the image data for the through image is interrupted and the image data of all the pixels representing the photographed image is output from the CCD 120.

  The image data output from the CCD 120 is sequentially input to the analog signal processing circuit 130 at the subsequent stage. The analog signal processing circuit 130 includes a correlated double sampling circuit (hereinafter referred to as CDS) 131, an amplifier (hereinafter referred to as AMP) 132, and an A / D converter (hereinafter referred to as A / D) 133. To generate red (R), green (G), and blue (B) single-color image data accurately corresponding to the accumulated charge amount of each pixel, and the generated image data is amplified by the AMP 132 in the middle stage. The amplified image data is converted into digital signal image data by the A / D 133 at the subsequent stage. The image data thus converted into a digital signal is guided to the bus Bus under the control of the CPU 110, and temporarily recorded in the SDRAM 141 which is a working image memory via the bus Bus.

  Then, the image data is read from the SDRAM 141 by the image processing circuit 142, subjected to various image processing such as gradation conversion, white balance correction, γ correction processing, YC conversion processing, etc., and stored in the SDRAM 141 again.

  Of the image data stored in the SDRAM 141 and processed by the image processing circuit 142, the image data acquired as a through image is supplied to the LCD driver 143 via the bus bus and supplied to the LCD driver 143. A through image based on the image data is displayed on the LCD 150 after being converted to an image signal that can be displayed by the driver 143. Among the image data that has been subjected to image processing by the image processing circuit 142, image data acquired as a captured image is: The data is read by the compression / decompression circuit 144 and compressed by the compression / decompression circuit 144 in a predetermined compression format (for example, JPEG format).

  If the CPU 110 detects that the compression processing by the compression / decompression circuit 144 has been completed by rewriting the end flag or the like in the compression / decompression circuit 144, the compressed image data and accompanying information (tag information) relating to the image data are displayed. Is stored in the memory card 160 via the memory card slot 145. The image file is stored in a predetermined format (for example, Exif format). The tag information includes, for example, model information of the digital camera 1 and shooting conditions.

  The digital camera 100 of FIG. 1 has the above-described configuration inside and operates as described above.

  Conventionally, when the subject brightness is less than the predetermined brightness, the focus lens is constantly moved to the in-focus position by operating in the continuous AF mode in order to increase the speed of AF, so that the digital camera There has been a problem of increased power consumption. Also, when the user moves from a bright place to a dark place with a digital camera, the display of the live view that has been blurred until now is automatically switched to the continuous AF mode. As a result, the user was perplexed.

  Therefore, in the present embodiment, the AE control unit 110B and the AF control unit 110C are provided in the CPU 110, and the AE control unit 110B, the photographing optical system 1110, and the CCD 120 constitute an example of the photometric means referred to in the present invention. Similarly, the AF control unit 110C, the motor driver 1102, the focus motor FM, and the focus lens 1112 constitute an example of the contrast AF means according to the present invention, and a mode called a wobbling AF mode is used instead of the conventional continuous mode. The above problem is solved by adopting the contrast AF.

  Here, the wobbling mode according to the present invention, which is provided instead of the continuous AF mode, will be described.

  In this wobbling mode, the focus lens 1112 is placed in the middle of the moving range, the wobbling operation is performed before the release button 102 is operated, the focus direction is recognized, and the release button 102 is operated. In this mode, the focus lens 1112 is moved from the current position in the focus direction to detect the focus position.

  When this wobbling mode is used, high speed performance substantially equal to that of the conventional continuous AF mode is ensured, and the amount of movement of the focus lens 111 is reduced, thereby reducing power consumption.

  Further, when the user carries the digital camera of FIG. 1 and moves from a place where the subject brightness is bright to a place where the subject brightness is dark and the single AF mode is switched to the wobbling mode, the focus lens 1111 is moved to the in-focus position. Since it is not moved, the through image in almost the same state as in the single AF mode is displayed on the display screen of the LCD 150 so that the user does not feel confused.

  Here, the procedures of the photographing process executed by the CPU 110, the image processing circuit 142, and the compression / decompression circuit 144, which have both functions of the photometry means and the contrast AF means, and constitute a part of both means, are described. explain.

  FIG. 3 is a flowchart showing a processing procedure of a photographing process executed in sequence by the CPU 110, the image processing circuit 142, and the compression / decompression circuit 144.

  Each of the CPU 110, the image processing circuit 142, and the compression / decompression circuit 144 sequentially executes the flow process in response to the power being turned on. The process of each step in the flow is a process that is mainly performed by any of the CPU 110, the image processing circuit 142, and the compression / decompression circuit 144 while the process is in progress. Any one of the processing circuit 142 and the compression / decompression circuit 144 will be described as a subject.

  In step S301, the CPU 110 performs subject luminance measurement. If the CPU 110 determines in step S301 that the subject brightness EV is 6 or more, the process proceeds to step S302, the single AF mode is set in the AF control unit 110B in the CPU 110, and a release operation is awaited. In response to the release operation being performed in step S303, CPU 110 performs AE processing in step S304 to set the shutter speed and aperture value in an internal register or the like. In step S305, the motor driver 1102 is instructed to move the focus lens 1112 to the closest distance, and contrast AF in the single AF mode is executed while moving the focus lens 1112 from the closest distance toward the ∞ direction. When the focus position is detected by contrast AF, the motor driver 1102 is instructed to drive the focus lens 1112 to the focus position, thereby placing the focus lens 1112 at the focus position. In the next step S306, the CPU 110 instructs the motor driver 1102 based on the AE processing result in step S304 to drive the iris motor IM until the aperture 1113 reaches a predetermined opening diameter, and instructs the TG 1101 to send a timing signal to the CCD 120. Then, the CCD 120 is exposed for a predetermined shutter time. When the exposure is completed, the TG 1101 is instructed to supply a readout signal to the CCD 120 and output the image data to the CDS 131 provided in the analog signal processing circuit 130 so that the CDS 131 accurately corresponds to the amount of received light. The AMP 132 in the analog signal processing circuit 130 amplifies each color signal and causes the A / D 133 to convert each color signal into a digital signal in step S307. The CPU 110 guides each color signal converted into a digital signal by the A / D 133 to the bus bus, transfers the color signal to the SDRAM 141 via the bus bus, and temporarily stores it.

  When the CPU 110 stores all the image data composed of R, G, and B color signals composed of all pixels in the SDRAM 141, the image processing circuit 142 that has received the process start signal from the CPU 110 reads out each color signal from the SDRAM 141 and outputs an image. When the processing is completed and the image processing is completed, it is stored in the SDRAM 141 again. At this time, the RGB signal is converted by the conversion matrix to be converted into a YCC signal and stored in the SDRAM.

  Here, when the CPU 110 detects the replacement of the end flag of the image processing circuit 142, the process start signal is notified to the compression / decompression circuit 144 this time. Upon receiving the process start signal, the compression / decompression circuit 144 reads the image data including the YC signal from the SDRAM 141, starts the compression process, and rewrites the end flag when the compression is completed. When the CPU 110 detects the replacement of the end flag of the compression / decompression circuit 144, the CPU 110 receives the compression information obtained when the compression / decompression circuit 144 performs compression from the compression / decompression circuit 144, and the compression information is compressed using the compression information as a header. An image file consisting of a header and image data added to the image data is recorded in the memory card 150 via the memory card slot 145, and the processing of this flow is completed.

  If the subject brightness is less than EV6 in step S301, the process proceeds to step S311 to instruct the motor driver 1102 to place the focus lens 1112 in the middle of the moving range and operate the wobbling operation before the release button 102 is operated. To start. The direction of focus is recognized by this wobbling operation. When a release operation is performed in the next step S312, in step S313, the CPU 110 executes AE processing in the internal AE control unit 110B, and sets the aperture value and shutter speed in an internal register or the like. Proceeding to the next step S314, in step S314, contrast AF in the wobbling mode is executed while moving the focus lens 1112 toward the in-focus direction grasped by the wobbling operation in step S311. When the focus position is detected by contrast AF, the motor driver 1102 is instructed to drive the focus lens 1112 to the focus position, thereby placing the focus lens 1112 at the focus position. In the next step S306, the motor driver 1102 is instructed to open the aperture 1113 until the aperture diameter grasped by the AE process in step S313 is reached, and the TG 1101 is instructed to supply a timing signal to the CCD 120, so that the CCD 120 has a predetermined shutter time. Let the exposure occur. When the CPU 110 detects that the exposure of the CCD 120 is completed, the CPU 110 instructs the TG 1101 to supply a readout signal to the CCD 120 and output the image data to the analog signal processing circuit 130. After the RGB color signals corresponding to the received light quantity are generated accurately by the CDS 131 in the analog signal processing circuit 130, the RGB signals are amplified by the AMP 132, and the A / D 133 is converted into a digital signal in step S307. Let it be done. The CPU 110 guides the image data converted into a digital signal by the A / D 133 to the bus bus, and transfers the image data to the SDRAM 141 via the bus bus for storage.

  When the CPU 110 stores the image data in the SDRAM 141, the image processing circuit 142 that has received the process start signal from the CPU 110 reads the image data, performs image processing, and stores the image data after the image processing in the SDRAM 141 again. Next, the compression / decompression circuit 144 receiving the process start signal from the CPU 110 reads the image data from the SDRAM 141 and compresses the image signal. When the compression / decompression circuit 144 finishes the compression process, the internal end flag is rewritten. When the CPU 110 detects rewriting of the end flag, the CPU 110 receives the compression information from the compression / decompression circuit 144, adds the header to the image data using the compression information as a header, and stores the image file including the header and the image data in the memory. Recording is performed on the memory card 160 via the card slot 145, and the processing of this flow is terminated.

  As described above, when the CPU 110 executes the processing of this flow, when the subject brightness is low, the CPU 110 automatically switches to the wobbling mode and performs high-speed AF that is almost the same as that in the case of continuous AF. As compared with the case where the continuous AF is performed, an effect that the power consumption is reduced by the load of the motor driver 1102 for driving the focus lens 1112 and the motor FM is obtained.

  Further, when the subject brightness becomes dark and the mode is switched to the wobbling mode, the focus lens 1112 is placed in the middle of the movement range, and the focus lens 1112 performs the wobbling operation so that the in-focus direction is recognized. The difference between the display of the through image and the display in the mode does not appear so much that the user does not feel confused.

  4 and 5 are diagrams illustrating the second embodiment.

  It is assumed that the digital camera shown in FIG. 1 is also used in the second embodiment.

  The configuration of FIG. 4 is the same as the configuration of FIG. 2 except that the AF sensor 170 is provided. The AF sensor 170 in FIG. 4 is a passive AF sensor, and when the subject distance is measured by the passive AF sensor 170, the AF sensor 170 according to the present invention is based on the subject distance information of the passive AF sensor 170. Contrast AF in the second single AF mode is performed. For this reason, the wobbling mode and the single AF mode described in the first embodiment are used only when the passive AF sensor 170 cannot be used. The power consumption can be further reduced, and the power consumption can be further reduced.

  With reference to FIG. 5, three types of contrast AF processing performed by the CPU 110, ie, a second single AF mode, a wobbling mode, and a single AF mode (corresponding to the first single mode in the present invention) will be described. Since the AF sensor of FIG. 4 is provided, processing steps from determination step S300 and steps S315 to S318 are added. Other than that, the processing is the same as that in FIG. 3, so the processing of the added portion will be described.

  In step S300, CPU 110 determines whether or not external AF sensor 170 can be used. If it is determined that the AF sensor 170 is unusable, the process proceeds to step S301 to determine the subject brightness, and the processing from step S302 to step S314 described in FIG. 3 is executed according to the determination result.

  If the CPU 110 determines in step S300 that the external AF sensor 170 can be used, the process proceeds to step S315 to set the second single AF mode in the AF control unit 110C and wait for the release operation. In response to the release operation performed in step S316, the CPU 110 performs AE processing in step S317, and performs contrast AF around the subject distance measured by the AF sensor 170 in step S318 to place the focus lens 1112 at the in-focus position. To do. The processes of steps S306 to S310 are executed, and the process of this flow is terminated.

  As described above, the wobbling mode and the single AF mode described in the first embodiment are used only when the passive AF sensor 170 cannot be used, and in the case of the second single AF mode. Since the focus lens 1112 is moved in a narrow range when the release button 102 is pressed, the amount of movement of the focus lens can be reduced as compared with the first embodiment, and the power consumption can be further reduced. Is possible.

  6 and 7 are diagrams for explaining the third embodiment.

  It is assumed that the digital camera shown in FIG. 1 is also used in the third embodiment.

  6 is the same as FIG. 2 except that a face detection unit 180 is provided instead of the AF sensor 170 of FIG. 7 is the same as that shown in FIG. 6 except that the face detection unit 180 is provided instead of the AF sensor 170, and the process in step S300 in FIG. 3 is changed to the process in step S300A. This is the same as the processing in FIG. Even if it is such a structure, the effect similar to the said embodiment is acquired.

  FIG. 8 is a diagram for explaining the fourth embodiment.

  It is assumed that the digital camera shown in FIGS. 1 and 2 is also used in the fourth embodiment.

  In the first embodiment, as shown in FIG. 2, depending on whether the brightness of the subject brightness is equal to or higher than the predetermined brightness or lower than the predetermined brightness in step S301, the single mode and the wobbling are respectively performed. In the fourth embodiment, the cross key 101b shown in FIG. 1 is operated in step S301A to change the focal length of the photographing optical system 1110 (see FIG. 2) and the focal length becomes a predetermined focal length in the fourth embodiment. Switching between the single mode and the wobbling mode is performed according to whether the focal length is equal to or longer than the predetermined focal length.

  As described above, if the focal length of the photographing optical system is equal to or greater than the predetermined focal length, the depth of field becomes shallow and the focus lens must be moved at finer intervals during contrast AF. Since the time required for AF is longer than when shooting with a shooting optical system with a focal length, in the fourth embodiment, the CPU 110 that constitutes a part of the contrast AF means according to the present invention performs the focus of the shooting optical system. The single AF mode and the wobbling mode set in the AF control unit are switched according to whether or not the distance is equal to or greater than a predetermined focal length. Such a configuration may be used.

  FIG. 9 is a diagram for explaining the fifth embodiment.

  It is assumed that the digital camera shown in FIGS. 1 and 2 is also used in the fifth embodiment.

  In the second embodiment shown in FIGS. 4 and 5, when the external AF sensor 170 (see FIG. 4) is provided and the external AF sensor 170 cannot be used, the subject brightness is determined in step S301 and is equal to or higher than the predetermined brightness. The single AF mode and the wobbling mode are switched according to whether the brightness is lower than the predetermined brightness. However, as shown in FIG. 9, the process of step S301 is changed to step S301A, and the photographing optical system is changed to step S301A. The single AF mode and the wobbling mode may be switched according to whether the focal length is equal to or greater than a predetermined focal length.

  FIG. 10 is a diagram for explaining the sixth embodiment.

  In the fifth embodiment shown in FIG. 9, when the external AF sensor 170 (see FIG. 4) cannot be used, a configuration for switching between the wobbling mode and the single AF mode according to the length of the focal length in step S301A will be described. However, when the face detection unit 180 (see FIG. 6) detects a face in step S300A by replacing the process in step S300 with the process in step S300A as shown in FIG. 10, the second single AF mode is set. If no face is detected after switching, the single AF mode and the wobbling mode may be switched in step S301A according to the length of the focal length.

  11 and 12 are diagrams for explaining the seventh embodiment.

  The process of FIG. 11 is the same as the process of FIG. 8 except that the process of step S311 is added. FIG. 12 is a diagram for explaining the file structure of an image file (Exif file).

  In step S311 of FIG. 11, the CPU 110 records, in the tag in the Exif file, which is an example of the image file, whether the shooting was performed in the wobbling mode, the single AF mode, or the second single AF mode. .

  In this way, for example, when a playback image is displayed on the LCD, it is displayed whether the shooting was performed in any one of the wobbling mode, the single AF mode, and the second single AF mode, and the display is a captured image. It is used as a clue to analyze the workmanship.

  As described above, as in the conventional case, an AF device is realized which can increase the speed of AF and reduce power consumption, and can maintain a through image display state substantially uniform even if the field luminance changes. .

It is a figure which shows the digital camera which is one Embodiment of the imaging device of this invention. FIG. 2 is a block diagram illustrating an internal configuration of the digital camera of FIG. 1. 6 is a flowchart illustrating a processing procedure of a photographing process executed in sequence by the CPU 110, the image processing circuit 142, and the compression / decompression circuit 144. It is a figure explaining 2nd Embodiment. It is a figure explaining 2nd Embodiment. It is a figure explaining 3rd Embodiment. It is a figure explaining 3rd Embodiment. It is a figure explaining 4th Embodiment. It is a figure explaining 5th Embodiment. It is a figure explaining 6th Embodiment. It is a figure explaining 7th Embodiment. It is a figure explaining 7th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Digital camera 101 Operation part 101a Power switch 101b Cross key 101c Menu / OK key 101d Cancel key 101e Mode lever 102 Release button 110 CPU
110A Memory 110B AE Control Unit 110C AF Control Unit 1101 TG
1102 Motor driver 111 Lens barrel 1110 Shooting optical system 1111 Zoom lens 1112 Focus lens 1113 Aperture 120 CCD
130 Analog signal processor 131 CDS
132 AMP
133 A / D
141 SDRAM
142 Image processing circuit 143 LCD driver 144 Compression / decompression circuit 145 Memory card slot 146 Memory card

Claims (10)

In a photographing apparatus that forms an image of a subject on an image sensor with a photographing optical system and generates an image representing the subject,
The photographing optical system includes a focus adjustment element that performs focus adjustment by movement,
A release button for receiving shooting instructions,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element, and before the release button is operated. A single AF mode in which the focus position is detected by moving from one end of the moving range to the other when the release button is operated, and the focus adjustment element is set to a middle position in the moving range. Before the release button is operated, a wobbling operation is performed to recognize the in-focus direction, and when the release button is operated, the focus adjustment element is moved from the current position to the in-focus direction. Contrast AF means having two modes, a wobbling mode for detecting the in-focus position,
Photometric means for measuring the brightness of the subject,
The contrast AF unit is configured to perform the single AF according to whether the brightness of the subject measured by the photometry unit is equal to or higher than a predetermined brightness, or less than the predetermined brightness, respectively. An imaging apparatus that operates in a mode or operates in the wobbling mode. In a photographing apparatus that forms an image of a subject on an image sensor with a photographing optical system and generates an image representing the subject,
The photographing optical system includes a focus adjustment element that performs focus adjustment by movement,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element;
A distance recognition means different from the contrast AF means for recognizing the subject distance;
A photometric means for measuring the brightness of the subject;
With a release button for receiving shooting instructions,
The contrast AF means
The focus adjustment element is stopped before the release button is operated, and when the release button is operated, the focus adjustment element is moved from one end of the moving range to the other to detect the in-focus position. 1 single AF mode,
Before the release button is operated, the focus adjustment element is stopped at a position in the middle of the movement range of the focus adjustment element, subject distance information recognized by the distance recognition means is obtained, and the release button is operated. In response, the second single AF mode for detecting the in-focus position by moving the focus adjustment element from the current position in the in-focus direction;
The focus adjustment element is placed in the middle of the movement range, a wobbling operation is performed before the release button is operated, the focus direction is recognized, and the focus adjustment element is received in response to the operation of the release button. It has three modes, a wobbling mode for detecting the in-focus position by moving in the in-focus direction from the current position,
The contrast AF means
When the subject measured by the photometric means is brighter than a predetermined brightness, it operates in the first single AF mode,
When the subject measured by the photometric means is less than a predetermined brightness and subject distance information is obtained from the distance recognition means, the second single AF mode is operated.
When the subject measured by the photometry means has a brightness less than a predetermined brightness and subject distance information cannot be obtained from the distance recognition means, the subject operates in the wobbling mode. Shooting device.   3. The photographing apparatus according to claim 2, wherein the distance recognizing means is a distance measuring means provided separately from the contrast AF means.   The distance recognizing means includes a face recognizing means for recognizing a face from an image obtained by the image sensor, and recognizes a subject distance based on a size of the face recognized by the face recognizing means. The imaging apparatus according to claim 2. In a photographing apparatus that forms an image of a subject on an image sensor with a photographing optical system and generates an image representing the subject,
The photographing optical system includes a zooming element that changes a focal length by movement and a focus adjustment element that performs focus adjustment by movement,
A release button for receiving shooting instructions,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element, and before the release button is operated. A single AF mode in which the focus position is detected by moving from one end of the moving range to the other when the release button is operated, and the focus adjustment element is set to a middle position in the moving range. Before the release button is operated, a wobbling operation is performed to recognize the in-focus direction, and when the release button is operated, the focus adjustment element is moved from the current position to the in-focus direction. Contrast AF means having two modes, i.e., a wobbling mode for detecting the in-focus position,
The contrast AF means operates in the single AF mode depending on whether the focal length of the photographing optical system is a focal length greater than or equal to a predetermined focal length or less than the predetermined focal length, respectively. Alternatively, a photographing apparatus that operates in the wobbling mode. In a photographing apparatus that forms an image of a subject on an image sensor with a photographing optical system and generates an image representing the subject,
The photographing optical system includes a zooming element that changes a focal length by movement and a focus adjustment element that performs focus adjustment by movement,
Contrast AF means for detecting the in-focus position by detecting the contrast of the image obtained by the image sensor while moving the focus adjustment element;
A distance recognition means different from the contrast AF means for recognizing the subject distance;
With a release button for receiving shooting instructions,
The contrast AF means
The focus adjustment element is stopped before the release button is operated, and when the release button is operated, the focus adjustment element is moved from one end of the moving range to the other to detect the in-focus position. 1 single AF mode,
Before the release button is operated, the focus adjustment element is stopped at a position in the middle of the movement range of the focus adjustment element, subject distance information recognized by the distance recognition means is obtained, and the release button is operated. In response, the second single AF mode for detecting the in-focus position by moving the focus adjustment element from the current position in the in-focus direction;
The focus adjustment element is placed in the middle of the movement range, a wobbling operation is performed before the release button is operated, the focus direction is recognized, and the focus adjustment element is received in response to the operation of the release button. It has three modes, a wobbling mode for detecting the in-focus position by moving in the in-focus direction from the current position,
The contrast AF means
When the focal length of the imaging optical system is less than a predetermined distance, the first single AF mode is operated,
When the focal length of the photographing optical system is equal to or greater than a predetermined distance and subject distance information is obtained from the distance recognition unit, the second single AF mode is operated.
An imaging apparatus, wherein the imaging optical system operates in the wobbling mode when the focal length of the imaging optical system is not less than a predetermined distance and subject distance information cannot be obtained from the distance recognition means.   7. The photographing apparatus according to claim 6, wherein the distance recognizing means is a distance measuring means provided separately from the contrast AF means.   The distance recognizing means includes a face recognizing means for recognizing a face from an image obtained by the image sensor, and recognizes a subject distance based on a size of the face recognized by the face recognizing means. The imaging device according to claim 6.   The photographed image generated in response to the operation of the release button is a photographed image obtained by focus adjustment in the single AF mode, or a photographed image obtained by focus adjustment in the wobbling mode. 6. A photographing apparatus according to claim 1, further comprising recording means for recording information indicating whether or not there is information.   In the captured image generated in response to the operation of the release button, the captured image is a captured image obtained by focus adjustment in the first single AF mode, or by focus adjustment in the second single AF mode. 7. The recording apparatus according to claim 2 or 6, further comprising recording means for recording with information indicating whether the image is an obtained image or an image obtained by focus adjustment in the wobbling mode. Shooting device.

Images