JP4699436B2 - Imaging device and mobile phone - Google Patents

Description

  The present invention relates to an imaging device mounted on a mobile terminal such as a mobile phone.

  Currently, most portable wireless terminals such as mobile phones are equipped with an imaging device, and this imaging device is equipped with an autofocus function that automatically measures the distance from the subject and adjusts the position of the lens to focus. (For example, refer to Patent Document 1).

  Generally, the auto focus (hereinafter abbreviated as “AF”) method is divided into an active method and a passive method. The active method is a method in which a subject is irradiated with infrared rays, ultrasonic waves, or the like, and the distance is detected based on the time until the reflected wave returns and the irradiation angle. The passive method is a method in which the lens is moved by evaluating the focus state from the image, and the lens is moved so that the AF evaluation value using contrast or the like is maximized.

  In an imaging device for still image shooting, both methods may be used together, but in an imaging device for moving image shooting, a passive method is generally used. In particular, in the case of an image pickup apparatus mounted on a mobile phone, the active method is mostly used because the active method has large size and cost restrictions.

  The AF has two modes, a single AF (hereinafter abbreviated as “SAF”) mode and a continuous AF (hereinafter abbreviated as “CAF”) mode. The SAF mode is a mode in which the lens is moved in order of coarse to fine adjustment until the AF evaluation value correlated with the focal length with the subject reaches a maximum, and once the focus is achieved, the lens is locked at that position. Used for still image shooting. The CAF mode is a mode in which the lens is continuously moved in fine adjustment until the AF evaluation value reaches the maximum, and the direction of the lens that is in focus is sequentially detected after the focus is achieved, the lens is moved in fine adjustment, and the focus is continuously adjusted. It is mainly used for video shooting.

In the SAF mode, when the subject moves or the subject changes, since it is not suitable for the subject that has moved or changed, it is necessary to perform focus again by performing SAF. CAF mode has been used.
JP 2006-276699 A

  However, in the moving picture recording method using the conventional CAF mode, when the subject condition suddenly changes when starting moving picture recording (for example, when the subject in the focus determination area 11 in FIG. 12 is changed from A to B). ) Has a problem in that it takes a long time from the start of moving image recording until the subject is brought into focus, and an out-of-focus image is recorded. In addition, when recording a moving image, the focus is conventionally adjusted using the CAF mode even during the preview before starting the moving image recording. Therefore, the CAF mode always finely moves the lens, which increases power consumption. There is a problem.

  The present invention has been made in view of the above points, and can reduce the time from when the user gives an instruction to start recording a moving image until focusing is achieved, without recording a defocused image. An object of the present invention is to provide an imaging apparatus that can suppress power consumption by the AF function.

An imaging apparatus according to the present invention has a function of adjusting the position of a lens to adjust a focus, forms an object image, generates an image signal, and records it in a memory, and drives the lens An evaluation value calculating unit that calculates an evaluation value that correlates with a focal distance between the lens driving unit and a subject using the image signal, and the lens driving unit with respect to the lens driving unit until the evaluation value reaches a maximum. The lens is fixed at the position once in focus, the first control means for performing the first control, and the lens driving means, the lens is moved until the evaluation value is maximized, and once the focus is reached. And a second control means for performing a second control that moves the lens and keeps the focus in accordance with the movement of the subject even after the image is matched, and instructs to start moving image recording after the moving image mode is selected. Until The serial focus and fixed focus, based on the instruction of the moving image recording start, the rough adjustment moving the lens in the order of the fine performs the first control, starts the moving image recording after the first control is finished, the fine The second control for moving the lens continuously is adopted.
In addition, an imaging apparatus according to the present invention includes a photographing unit that photographs a still image or a moving image, a recording unit that records information photographed by the photographing unit, a photographing key that causes the recording unit to record the photographed information, and a subject A lens driving means for adjusting the position of the lens for focusing, and a first control means for performing a first control for fixing the lens at the position once focused on the lens driving means. A second control unit that performs a second control to move the lens and keep the focus in accordance with the movement of the subject even after the lens is focused once. There between the selected until the moving image recording start is instructed by pressing the photographing key, the focus and fixed focus, based on the moving image recording start instruction by pressing the photographing key, a coarse adjustment Performs the first control for sequentially with moving the lens adjustment, starts the moving image recording after the first control is finished, a configuration for performing the second control to move continuously said lens in fine tuning.

  According to the present invention, it is possible to reduce the time from when the user gives an instruction to start moving image recording to when the image is focused, without recording a defocused image, and further suppressing power consumption by the AF function. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a case where an imaging device is mounted on a mobile phone will be described.

(Embodiment 1)
FIG. 1 is a block diagram showing an outline of a hardware configuration of a mobile phone equipped with an imaging apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, a mobile phone 100 includes an antenna 101, a transmission / reception processing unit 102, a modulation / demodulation processing unit 103, a data processing unit 104, and a D / A converter as components for a call unique to the mobile phone. 105, a speaker 106, an A / D converter 107, and a microphone 108. Since these components are realized by a conventionally known technique, detailed description thereof is omitted.

  Furthermore, the mobile phone 100 includes a display unit 109, an operation unit 110, a CPU (Central Processing Unit) 111, and a memory 112. The display unit 109 displays data such as a captured image on the screen. The operation unit 110 has operation buttons and transmits instructions based on user button operations to each component. In particular, in this embodiment, the operation buttons include an operation mode key for shifting to the operation mode and a shooting key for starting moving image recording. The CPU 111 controls each component. The memory 112 is used as a temporary storage area for data.

  Furthermore, the mobile phone 100 includes an imaging device 113 that captures still images and moving images. The imaging device 113 includes an optical unit 131, an image processing unit 132, an AF evaluation unit 133, a SAF control unit 134, a CAF control unit 135, and a lens driving unit 136. The optical unit 131 includes a lens unit 151 and an image sensor 152. In general, the optical unit 131 also includes an aperture, a mechanical shutter, and the like, and the imaging device 113 includes an aperture drive unit that drives the aperture, a shutter drive unit that drives the mechanical shutter, and the like in addition to those illustrated in FIG. However, the description thereof is omitted in this embodiment.

  The optical unit 131 forms a subject image on the light receiving surface of the image sensor 152 by the lens unit 151, and converts the subject image into an image signal by the image sensor 152. The imaging element is, for example, a CCD (charge-coupled device).

  The image processing unit 132 performs signal processing such as digital conversion on the image signal of the subject image output from the optical unit 131. The image signal processed in the image processing unit 132 is output to the display unit 109 or the memory 112 based on the control of the CPU 111, thinned out at a predetermined interval, and output to the AF evaluation unit 133.

  The AF evaluation unit 133 calculates an AF evaluation value using the image signal output from the image processing unit 132, and outputs the AF evaluation value to the SAF control unit 134 or the CAF control unit 135. As the AF evaluation value, for example, the contrast value of the subject image formed on the image sensor at every predetermined interval (for example, 30 fps) while driving the lens unit 151 is used.

  The SAF control unit 134 controls the lens driving unit 136 so as to detect the maximum value of the AF evaluation value in the SAF mode. Further, when the SAF control unit 134 detects the maximum value, the SAF control unit 134 controls the lens driving unit 136 to lock the lens unit 151 on the assumption that the focus is in that position. Then, when the SAF control unit 134 detects the maximum value, the SAF control unit 134 outputs a signal indicating this to the CAF control unit 135.

  The CAF control unit 135 controls the lens driving unit 136 so as to detect the maximum value of the AF evaluation value in the CAF mode. Further, the CAF control unit 135 controls the lens driving unit 136 so as to move the lens unit 151 with fine adjustment even after detecting the maximum value, and keeps focusing.

  The lens driving unit 136 drives the lens unit 151 in the optical unit 131 based on an instruction from the SAF control unit 134 or the CAF control unit 135.

  Next, the operation of the imaging apparatus 113 according to the present embodiment will be described using the flowchart of FIG.

  First, when the user enters the moving image mode by depressing the operation mode key of the operation unit 110 (ST201; YES), the mobile phone 100 enters a preview state (ST202). Specifically, the CPU 111 stops the control of the SAF control unit 134 and the CAF control unit 135 and the driving of the lens driving unit 136, the optical unit 131 captures a subject image with a fixed focus, and the image processing unit 132 sets the optical unit. The image signal of the subject image captured in 131 is processed, and the display unit 109 displays the image signal processed by the image processing unit 132. At this time, no image signal is recorded in the memory 112.

  During the preview, when the user instructs to start moving image recording by depressing the shooting key of the operation unit 110 (ST203; YES), the imaging device 113 executes the SAF operation until the focus is achieved (ST204). Specifically, the lens driving unit 136 drives the lens unit 151 of the optical unit 131, the optical unit 131 and the image processing unit 132 generate an image signal of the subject image, and the AF evaluation unit 133 uses the image signal to focus. A series of operations in which the state is evaluated and the SAF control unit 134 controls the lens driving unit 136 based on the AF evaluation value is repeated until the maximum value of the AF evaluation value is detected. Note that an in-focus determination notification indicating whether or not focus is achieved during the SAF operation is displayed on the display unit 109.

  When the SAF control unit 134 detects the maximum value of the AF evaluation value, the SAF control unit 135 notifies the CAF control unit 135 of a signal indicating that the SAF operation has ended (ST205; YES), and the imaging device 113 records the moving image and the CAF operation. Is executed (ST206). Specifically, the lens driving unit 136 drives the lens unit 151 of the optical unit 131, the optical unit 131 and the image processing unit 132 generate an image signal of the subject image and record it in the memory 112, and the AF evaluation unit 133 A series of operations is repeated in which the focus state is evaluated using the image signal, and the CAF control unit 135 controls the lens driving unit 136 based on the AF evaluation value. Note that the CAF operation may be executed in a state where the focus is not achieved in the SAF.

  Note that the CAF operation and moving image recording are continued until the user instructs the end of shooting (ST207).

  As described above, while the auto focus is conventionally performed in the CAF mode from the preview (FIG. 3A), in the present embodiment, the fixed focus is set during the preview, and when the moving image recording start instruction is given, First, after focusing in the SAF mode, the mode is shifted to the CAF mode and moving image recording is started (FIG. 3B).

  As a result, according to the present embodiment, since focusing is performed in the SAF mode at the time of moving image recording start instruction, it is possible to shorten the time from when the user instructs to start moving image recording until focusing is achieved. Further, according to the present embodiment, since moving image recording is started after focusing, an image with a defocused image is not recorded. Further, according to the present embodiment, since the CAF mode is not used during the preview, power consumption by the AF function can be suppressed.

(Embodiment 2)
In the second embodiment, a case where the user can select the AF mode during preview before moving image recording will be described. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as that shown in FIG.

  FIG. 4 is a flowchart showing the operation of the imaging apparatus 113 according to the present embodiment. In FIG. 4, steps common to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, as shown in FIG. 4, in the preview state (ST202), the user can select either the SAF mode or the fixed focus mode and instruct the CPU 111 (ST401). There are two fixed focus modes: a pan side mode in which the lens unit 151 is fixed to the infinity side, and a macro side mode in which the lens unit 151 is fixed to the macro side, and the user selects one of these. Note that when the AF mode default value is set to SAF mode or fixed focus mode (either pan side or macro side), and the user depresses the shooting key without performing AF mode selection during preview. (ST203; YES), the following operation is executed in the AF mode set to the default value.

  Next, when the user instructs to start moving image recording by depressing the shooting key of the operation unit 110 in the preview state (ST203; YES), if the AF mode is the SAF mode (ST402; NO), the CPU 111 The imaging apparatus 113 is instructed to execute the SAF mode, and the imaging apparatus 113 executes the SAF operation until it is in focus (ST204). When the SAF operation ends (ST205; YES), the imaging apparatus 113 performs moving image recording and CAF operation. Execute (ST206, ST207).

  On the other hand, when the AF mode is the fixed focus mode (ST402; YES), the CPU 111 instructs the image pickup apparatus 113 to execute the fixed focus mode, and the image pickup apparatus 113 does not perform the SAF operation and performs moving image recording and CAF. The operation is executed (ST206, ST207).

  As described above, in the present embodiment, during the preview, the user can select the SAF mode (FIG. 5A) or the fixed focus mode (pan side (FIG. 5B, macro side (FIG. 5C))). When the fixed focus mode is selected, moving image recording can be started when the shooting key is pressed down.

(Embodiment 3)
In the third embodiment, a case will be described in which during the preview before moving image recording, the user presses the AF key to focus in advance and start moving image recording. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as that shown in FIG.

  FIG. 6 is a flowchart showing the operation of the imaging device 113 according to the present embodiment. In FIG. 6, steps common to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, as shown in FIG. 6, in the preview state (ST202), when the user depresses the AF key (ST601), the imaging device 113 executes the SAF operation until the focus is achieved (ST204).

  If the photographing key cannot be depressed (ST602; NO), the imaging device 113 repeats the process from ST202 again.

  On the other hand, when the shooting key is pressed down (ST602; YES), the imaging device 113 performs moving image recording and CAF operation (ST206, ST207).

  As described above, in the present embodiment, during the preview, the user can adjust the focus at any timing by pressing down the AF key (FIG. 7). Even if the moving image recording is started without a time lag from the time when the photographing key is pressed, the image that is out of focus is not recorded.

(Embodiment 4)
In the fourth embodiment, a case will be described in which whether or not the SAF operation is to be executed based on the remaining battery level and the AF evaluation value when the user depresses the shooting key during the preview before moving image recording is described. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as in FIG.

  FIG. 8 is a flowchart showing the operation of the imaging apparatus 113 according to the present embodiment. In FIG. 8, steps common to those in FIG.

  In the present embodiment, as shown in FIG. 8, in the preview state (ST202), when the user instructs to start moving image recording by depressing the shooting key of operation unit 110 (ST203; YES), CPU 111 causes battery remaining When the remaining battery level is equal to or higher than the first threshold value or the AF evaluation value is equal to or lower than the second threshold value (ST801; YES), the CPU 111 compares the amount and the AF evaluation value with a preset threshold value. The imaging apparatus 113 is instructed to perform a SAF operation. The imaging device 113 executes the SAF operation until it is in focus (ST204), and when the SAF operation ends (ST205; YES), the imaging device 113 executes the moving image recording and the CAF operation (ST206, ST207).

  On the other hand, when the remaining battery level is less than the first threshold value and the AF evaluation value is higher than the second threshold value (ST801; NO), the imaging device 113 performs the moving image recording and the CAF operation without performing the SAF operation. (ST206, ST207).

  As described above, in this embodiment, when the user instructs to start moving image recording during the preview, it is determined whether or not to perform the SAF operation based on the remaining battery level and the AF evaluation value. When the remaining battery level is high and the AF evaluation value is high, the remaining battery level is sufficient even when the CAF operation is executed, and the time until focusing is short. Even if moving image recording is started without a time lag, recording of a defocused image is almost eliminated.

  In the present embodiment, the case where the remaining battery level and the AF evaluation value are used as the determination criteria has been described. However, the present invention is not limited to this, and only one of the remaining battery level or the AF evaluation value is used. It may be used.

(Embodiment 5)
In the fifth embodiment, a case will be described in which the SAF operation is executed by increasing the frame rate when the user depresses the shooting key during the preview before moving image recording. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as that shown in FIG.

  FIG. 9 is a flowchart showing the operation of the imaging apparatus 113 according to the present embodiment. In FIG. 9, steps common to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, as shown in FIG. 9, in the preview state (ST202), when the user instructs to start moving image recording by depressing the shooting key of the operation unit 110 (ST203; YES), the imaging device 113 In a state where the frame rate is increased (ST901), the SAF operation is executed until the focus is achieved (ST204). When the SAF operation is completed (ST205; YES), the frame rate is returned, and the imaging device 113 performs moving image recording and CAF operation. Are executed (ST206, ST207).

  As described above, in this embodiment, since the in-focus speed of SAF depends on the frame rate, the time from when the shooting key is pressed down to the start of moving image recording is shortened by increasing the frame rate during SAF. be able to.

  In the present embodiment, the same effect can be obtained by roughening the lens operation in the SAF mode instead of increasing the frame rate.

  Since no moving image is recorded during the SAF operation, increasing the frame rate or roughening the lens operation has little effect on the image quality.

  Note that the method of increasing the frame rate during SAF and reducing the AF operation time is not limited to moving image shooting, and can also be used as means for reducing the SAF operation time in still image shooting.

(Embodiment 6)
In the sixth embodiment, a case will be described in which it is determined whether or not to execute the CAF operation based on the remaining battery level when the user presses the shooting key during the preview before moving image recording and the SAF operation is completed. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as that shown in FIG.

  FIG. 10 is a flowchart showing the operation of the imaging device 113 according to the present embodiment. In FIG. 10, steps common to those in FIG. 2 are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, as shown in FIG. 10, in the preview state (ST202), when the user instructs to start moving image recording by depressing the shooting key of the operation unit 110 (ST203; YES), the imaging device 113 The SAF operation is executed until focus is achieved (ST204).

  When the SAF operation ends (ST205; YES), the CPU 111 compares the remaining battery level with a preset threshold value. When the remaining battery level is equal to or less than the third threshold value (ST1001; YES), the CPU 111 captures an image. The apparatus 113 is instructed not to execute the CAF operation, and only the moving image recording is executed (ST1002).

  On the other hand, when the remaining battery level is greater than the third threshold (ST1001; NO), the CPU 111 instructs the imaging device 113 to execute the CAF operation, and executes moving image recording (ST206, ST207).

  As described above, in the present embodiment, when the user instructs to start moving image recording during the preview, it is determined whether or not to execute the CAF operation based on the remaining battery level. When the remaining battery level is low, the CAF operation is not executed. As a result, power consumption can be suppressed when the remaining battery level is low.

(Embodiment 7)
In the seventh embodiment, during the preview before moving image recording, the user depresses the shooting key, and when the SAF operation is completed, it is determined whether or not to execute the CAF operation based on the shooting size and the zoom magnification. A case will be described in which it is determined whether or not to start / continue the CAF operation when there is an operation. Note that the hardware configuration of a mobile phone equipped with the imaging device of the present embodiment is the same as that shown in FIG.

  FIG. 11 is a flowchart showing the operation of the imaging device 113 according to the present embodiment. In FIG. 11, the steps common to those in FIG.

  In the present embodiment, as shown in FIG. 11, in the preview state (ST202), when the user instructs to start moving image recording by depressing the shooting key of the operation unit 110 (ST203; YES), the imaging device 113 The SAF operation is executed until focus is achieved (ST204).

  When the SAF operation ends (ST205; YES), the CPU 111 compares the shooting size and zoom magnification with preset threshold values, and the shooting size is equal to or smaller than the fourth threshold value and the zoom magnification is equal to or smaller than the fifth threshold value. In some cases (ST1101; YES), the CPU 111 instructs the imaging device 113 not to execute the CAF operation and executes only moving image recording (ST1102).

  On the other hand, when the shooting size is larger than the fourth threshold value or the zoom magnification is larger than the fifth threshold value (ST1101; NO), the CPU 111 instructs the imaging device 113 to execute the CAF operation and executes moving image recording (ST206).

  After that, when there is a zoom operation (ST1103; YES), the CPU 111 compares the zoom magnification with a preset threshold value, and when the zoom magnification is equal to or less than the fifth threshold value (ST1104; YES), a predetermined time. (ST1105), the imaging apparatus 113 is instructed to stop the CAF operation (ST1106).

  On the other hand, when the zoom magnification is larger than the fifth threshold (ST1104; NO), the CPU 111 instructs the imaging device 113 to start or continue the CAF operation. (ST1107).

  Note that the imaging device 113 may be provided with a determination function based on the above threshold.

  As described above, in this embodiment, when the user instructs to start moving image recording during the preview, the focus shift is not conspicuous depending on the reduction ratio. Therefore, the CAF operation is executed based on the shooting size and the zoom magnification. Determine whether or not. Then, when the shooting size is small and the zoom magnification is small, the CAF operation is not executed, so that power consumption can be suppressed when the remaining battery level is low.

  In each of the above embodiments, the case where the imaging device is mounted on the mobile phone has been described. However, the present invention is not limited to this, and the same applies to a general digital camera or the like in which the imaging device is mounted on another device. The effect of can be obtained.

  Moreover, each said embodiment can be combined suitably and can produce a synergistic effect by combination.

  The imaging device according to the present invention is suitable for being mounted on a portable wireless terminal such as a cellular phone.

1 is a block diagram showing an outline of a hardware configuration of a mobile phone equipped with an imaging device according to Embodiment 1 of the present invention. The flowchart which shows operation | movement of the imaging device which concerns on Embodiment 1 of this invention. The figure explaining the effect of Embodiment 1 of this invention FIG. 7 is a flowchart showing the operation of the imaging apparatus according to the second embodiment of the present invention. The figure explaining Embodiment 2 effect of the present invention FIG. 9 is a flowchart showing the operation of the imaging apparatus according to the third embodiment of the present invention. The figure explaining the effect of Embodiment 3 of this invention FIG. 9 is a flowchart showing the operation of the imaging apparatus according to the fourth embodiment of the present invention. FIG. 9 is a flowchart showing the operation of the imaging apparatus according to the fifth embodiment of the present invention. FIG. 9 is a flowchart showing the operation of the imaging apparatus according to the sixth embodiment of the present invention. FIG. 7 is a flowchart showing the operation of the imaging apparatus according to the seventh embodiment of the present invention. The figure explaining the case where the condition of the subject suddenly changes when starting movie recording

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Mobile phone 109 Display part 110 Operation part 111 CPU (Central Processing Unit)
112 Memory 113 Imaging Device 131 Optical Unit 132 Image Processing Unit 133 AF Evaluation Unit 134 SAF Control Unit 135 CAF Control Unit 136 Lens Drive Unit 151 Lens Unit 152 Image Sensor

Claims (6)

An imaging device having a function of adjusting a position of a lens to adjust a focus, forming a subject image, generating an image signal, and recording the image signal in a memory;
Lens driving means for driving the lens;
An evaluation value calculating means for calculating an evaluation value correlated with a focal length with a subject using the image signal;
First control means for performing a first control for moving the lens until the evaluation value reaches a maximum with respect to the lens driving means, and fixing the lens at that position once in focus;
Second control is performed for the lens driving means to move the lens until the evaluation value reaches a maximum, and to continue focusing by moving the lens as the subject moves once the focus is achieved. 2 control means,
From the time when the video mode is selected until the start of video recording is instructed, the focus is a fixed focus,
Based on the instruction to start moving image recording, the first control is performed to move the lens in the order from coarse adjustment to fine adjustment . After the first control is completed, moving image recording is started , and the lens is continuously moved in fine adjustment. An imaging apparatus that performs the second control to move .   The imaging apparatus according to claim 1, wherein the first control is executed after increasing a frame rate.   The imaging apparatus according to claim 1, wherein the first control is executed by roughening an operation of the lens. 2. The imaging according to claim 1, wherein when the zoom magnification is equal to or smaller than a first threshold, the second control is stopped after a predetermined time has elapsed, and when the zoom magnification is larger than the first threshold, the second control is started or continued. apparatus. Photographing means for photographing a still image or a movie;
Recording means for recording information photographed by the photographing unit;
A photographing key for recording the photographed information on the recording means;
Lens driving means for adjusting the position of the lens in order to focus on the subject;
A first control means for performing a first control for fixing the lens at the position once focused on the lens driving means;
A second control unit that performs a second control to move the lens and keep the focus in accordance with the movement of the object even after the lens is focused once.
From the time when shooting of the moving image is selected until the start of moving image recording is instructed by pressing the shooting key, the focus is a fixed focus,
Based on the instruction to start moving image recording by pressing the shooting key, the first control is performed to move the lens in the order from coarse adjustment to fine adjustment . After the first control is completed, moving image recording is started and fine adjustment is performed. An imaging apparatus that performs the second control of moving the lens continuously . A mobile phone comprising the imaging device according to any one of claims 1 to 5 .

Images