KR20090107858A - Photographing apparatus and method for controlling the photographing apparatus - Google Patents

Abstract

PURPOSE: A photographing apparatus and a method for controlling the photographing apparatus are provided to suitably adjust a light amount of AF sub light according to surrounding brightness, thereby reducing power consumption of the photographing apparatus. CONSTITUTION: A photographing apparatus(100) includes a lens unit(111), a focus tool, a shutter, a photographing device, a CDS(Correlated Double Sampling) circuit, an A/D converter, an image input controller, a white balance controller, a compression processing circuit, a display unit driver, a display unit, a timing generator, a controller, an input unit(132), a memory, a VRAM(Video Random Access Memory), a media controller, recording media, a battery, a view finder, a flash(170), a sub light emitting unit(182), a light amount controller, and a light metering sensor(190). The photographing device receives image light transmitting an optical unit. The sub light emitting unit emits sub light for an automatic focus operation. The light amount controller determines a light amount of sub light based on surrounding brightness of the photographing apparatus.

Description

Imaging Apparatus and Control Method therefor {Photographing apparatus and method for controlling the photographing apparatus}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device and a control method thereof, and more particularly, to an imaging device and a control method thereof, in which the amount of emitted light of the AF auxiliary light is adjusted according to the brightness of the surroundings of the imaging device.

An imaging device is a device for imaging a subject, and in recent years, many imaging devices, such as a digital still camera and a digital video camera, have become popular.

In recent imaging devices, a function of an autofocus operation (hereinafter referred to as "AF (Auto Focus)") is common.

In performing AF, since AF is performed by analyzing the image data while moving the focus lens little by little and searching for a focusing point, it is necessary to have a somewhat bright shooting environment during AF.

Thus, an imaging device having an AF function is provided with an auxiliary light emitting device that emits a focusing auxiliary light (hereinafter referred to as "AF auxiliary light") when performing AF in a dark environment.

By the way, the conventional auxiliary light-emitting device was comprised so that when a sensor judges that the periphery of an imaging device is dark, it emits a fixed amount of light without considering the grade of ambient brightness. That is, even when the surroundings of the imaging device are dark as clay and when there is a little external light such as a street light, AF is performed by emitting the AF auxiliary light of the same amount of light.

By adopting such a conventional technique, even when a small amount of light of the AF auxiliary light is consumed, the same power as in the case where a large amount of light is required is consumed, which makes it difficult to use power efficiently.

Therefore, there is a need for the development of a technology capable of efficiently managing power consumption by appropriately adjusting the light emission amount of the AF auxiliary light according to the brightness around the imaging device.

This invention makes it a main subject to provide the imaging device which can control power quantity of AF auxiliary light suitably, and can reduce power consumption.

According to an aspect of the present invention, there is provided an image pickup apparatus for performing an autofocus operation, comprising: an optical unit for transmitting image light; an image pickup device for receiving image light passing through the optical unit; and an auxiliary light for the autofocus operation; An auxiliary light emitting unit; and an emission amount control unit for determining the size of the amount of light of the auxiliary light on the basis of the brightness of the surrounding of the imaging device.

Here, the optical unit may include a focus lens that performs the auto focus operation.

The auxiliary light emitting unit may include a light source including a light emitting diode (LED).

Here, the optical measuring sensor for measuring the brightness of the surroundings of the imaging device may be further provided.

Here, the light emission amount control unit may determine the size of the light emission amount based on the brightness around the imaging device measured by the optical measuring sensor.

In addition, the present invention provides a control method of an imaging device that performs an autofocus operation, comprising the steps of: (a) measuring the brightness of the periphery of the imaging device; and (b) Determining the magnitude of the amount of light of the auxiliary light required to perform the autofocus operation; and (c) emitting the auxiliary light according to the size of the determined amount of the auxiliary light; and (d) the light emission. And performing the auto focus operation with the supplementary auxiliary light.

Here, step (a) may be performed by an optical measuring sensor of the imaging device.

Here, step (a) may be performed by an auto exposure function of the imaging device.

Here, the step (c) may be made by a light source consisting of a light emitting diode.

Here, step (d) may be performed by moving the focus lens in the optical axis direction.

According to the image capturing apparatus and the control method thereof according to the present invention, the power consumption of the image capturing apparatus can be reduced by adjusting the amount of light of the AF auxiliary light in accordance with the brightness around the image capturing apparatus.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of an imaging device according to an embodiment of the present invention, FIG. 2 is a rear view of the imaging device shown in FIG. 1, and FIG. 3 is a schematic diagram showing an internal configuration of the imaging device shown in FIG. 1. Drawing.

The imaging device 100 according to the present embodiment is a compact digital camera, which is a digital camera having a lens unit integrated with a main body.

As shown in FIGS. 1 to 3, the imaging device 100 includes a lens unit 111, a focus mechanism 112, a shutter 113, an imaging device 114, and a CDS (Correlated Double Sampling) circuit integrated with an amplifier. 115, A / D converter 116, image input controller 117, white balance adjusting unit 118, compression processing circuit 120, display unit driver 122, display unit 124, timing generator 126, Control unit 128, input unit 132, memory 134, VRAM (Video Random Access Memory) 136, media controller 138, recording media 140, battery 150, view finder 160, flash 170, an auxiliary light emitting unit 182, an emission amount control unit 184, an optical measuring sensor 190, and the like.

The lens unit 111 performs a function of transmitting image light of a subject, and includes a zoom lens and an aperture. Among them, the zoom lens is a lens in which the focal length is continuously changed by moving back and forth in the optical axis direction. In addition, the aperture adjusts the amount of light entering the imaging device 114 when the image is taken.

The focus mechanism 112 includes a focus lens 112a, a focus motor 112b, and a motor driver 112c.

The focus mechanism 112 drives the motor driver 112c by the signal of the control part 128, and the motor driver 112c drives the focus motor 112b to move the focus lens 112a back and forth in the optical axis direction. By doing so, the subject is operated to be in focus.

The shutter 113 performs a function of controlling the light entering the imaging device 114.

The lens unit 111, the focus mechanism 112, and the shutter 113 of the present embodiment constitute the optical unit of the imaging device 100. That is, the optical unit transmits the image light to the image pickup device 114 by transmitting the image light.

The imaging device 114 is arranged at a position where the image light passing through the lens unit 111 is formed into an image, thereby converting the formed image into an electrical signal.

Charge imaging devices (CCD) devices are used as the imaging device 114, but the present invention is not limited thereto. That is, a complementary metal oxide semiconductor (CMOS) may be used as the image pickup device according to the present invention, or another image sensor may be used.

The CDS circuit 115 is a circuit in which a CDS circuit, which is a type of sampling circuit for removing noise of an electrical signal output from the imaging element 114, and an amplifier for amplifying an electrical signal after removing noise, are integrated. In the present embodiment, the CDS circuit 115 is configured using a circuit in which the CDS circuit and the amplifier are integrated, but the CDS circuit and the amplifier may be configured as separate circuits.

The A / D converter 116 is a device that converts an analog electric signal generated by the imaging device 114 into a digital signal.

The image input controller 117 performs a function of transmitting a digital image signal to the controller 128 or the like.

The white balance adjusting unit 118 is a circuit for adjusting the value of the white balance using the captured image data output from the imaging element 114.

The white balance adjusting unit 118 according to the present embodiment is configured by a circuit separate from the control unit 128, but the present invention is not limited thereto. That is, according to the present invention, the white balance adjusting unit may be configured as a part of the controller 128.

In addition, although the white balance adjustment part 118 which concerns on this embodiment is comprised by the electric circuit itself, this invention is not limited to this. That is, according to the present invention, the white balance adjusting unit may be configured by software.

The compression processing circuit 120 performs compression processing to compress the data of the captured image into an appropriate format. The compressed format of the image may be a reversible format or an irreversible format. As an example of a suitable format, you may convert into the JPEG (Joint Photographic Experts Group) format or the JPEG 2000 format.

An LCD (Liquid Crystal Display) device is used as the display unit 124 to perform live view display before performing a photographing operation, various setting screens of the imaging device 100, and an indicator of a photographed image. The display of the image data and various information of the imaging device 100 on the display unit 124 is performed via the display unit driver 122.

Although the LCD device is used as the display unit 124 in this embodiment, the present invention is not limited thereto. That is, in the present invention, an organic light-emitting diode, a field emission display (FED), or the like may be used as the display unit.

The timing generator 126 inputs a timing signal to the imaging device 114. The shutter speed is determined by the timing signal from the timing generator 126. That is, the driving of the imaging device 114 is controlled by the timing signal from the timing generator 126, and the image light from the subject is incident within the time driven by the imaging device 114, thereby providing the basis of the image data. The signal is generated.

The control unit 128 issues a signal system command to the focus mechanism 112, the imaging device 114, the CDS circuit 115, the light emission control unit 184, or the like, or commands an operation system for the operation of the input unit 132. Do it. In the present embodiment, only one control unit is included, but the command of the signal system and the command of the operation system may be performed by separate control units.

In particular, the controller 128 receives and calculates data on the brightness of the external periphery of the image capturing apparatus 100 from the photometric sensor 190, and then transmits the data to the light emission controller 184. .

In addition, the controller 128 also performs an image processing function. That is, a function of processing the imaging data received from the imaging device 114 is also performed. Typically, the controller 128 performs gamma correction of the transmitted photographing data.

Gamma correction means encoding information in accordance with nonlinearity of human vision. In other words, since human vision reacts nonlinearly to brightness according to Weber's law, when a limited bit depth is given, linearly recording the brightness of light results in posterization ( Posterization) occurs. Therefore, in order to show the maximum image quality under a given bit depth, it must be encoded using a nonlinear function, which is called gamma correction.

The gamma correction of the controller 128 gamma corrects and outputs an image signal input by a gamma curve. For example, the input luminance level of a 12-bit image signal is corrected to an 8-bit luminance level.

The input unit 132 includes a function as a photographing mode selection unit, and a member for performing an operation of the imaging device 100 or for performing various settings at the time of photographing is disposed. On the member disposed in the input unit 132, a power button, a cross key for selecting a shooting mode or a shooting drive mode and setting effect parameters, a shutter button for starting a shooting operation, and the like are disposed. In addition, the shape and format of the input unit 132 is not particularly limited. That is, it may be formed in a button shape or may have a form of a touch screen device linked to the display unit 124.

The memory 134 is an example of an image storage section, which temporarily stores data of photographed images and data necessary for operation. The memory 134 has a storage capacity as long as it can store a plurality of images. The reading / writing of the image into the memory 134 is controlled by the image input controller 117.

The VRAM 136 holds contents displayed on the display unit 124, and the resolution and the maximum number of colors of the display unit 124 depend on the capacity of the VRAM 136.

The recording medium 140 is an example of an image recording unit that records a photographed image. Input and output to the recording medium 140 are controlled by the media controller 138. As the recording medium 140, a SD card (secure digital card), a multimedia card (MMC), or the like, which is a card-type storage device for recording data, may be used.

The battery 150 performs a function of supplying power to the imaging device 100.

As the battery 150, a disposable battery or a rechargeable battery may be used. As the disposable battery, a manganese battery or an alkaline battery may be used. The rechargeable battery may be a nickel cadmium (Ni-Cd) battery or a nickel hydrogen (Ni-MH) battery. Batteries, Li-ion batteries and the like can be used.

On the other hand, the view finder 160 is a device for the user to check the position of the subject for imaging, the flash 170 is a device used to secure the required amount of light when shooting in low illumination.

The auxiliary light emitting unit 182 emits the AF auxiliary light, and includes a lamp 182a and a lens 182b.

The lamp 182a uses a light emitting diode (LED). A single light emitting diode may be used, and a plurality of light emitting diodes may be used.

A light emitting diode is used as the lamp 182a of the auxiliary light emitting unit 182 according to the present embodiment, but the present invention is not limited thereto. That is, various types of lamps such as a fluorescent lamp and a light emitting tube may be used as the lamp of the auxiliary light emitting unit according to the present invention.

The lens 182b is disposed in front of the lamp 182a. The lens 182b protects the lamp 182a, and projects the light from the lamp 182a to be directed to the front of the subject. As the lens 182b, a Fresnel lens may be used.

On the other hand, the light emission amount control unit 184 is composed of an electrical circuit, and is electrically connected to the lamp 182a.

The light emission amount control unit 184 determines the size of the light amount of the AF auxiliary light based on the brightness around the outside of the imaging apparatus 100, and accordingly performs the function of adjusting the light amount of the AF auxiliary light accordingly.

To this end, the light emission amount control unit 184 receives the information on the brightness around the outside of the imaging device 100 from the control unit 128 and calculates the amount of current required for the lamp 182a by calculating based on the information. Thereafter, by sending the adjusted current to the lamp 182a by using a variable resistor, the amount of light of the AF auxiliary light emitted by the lamp 182a is adjusted.

In the present embodiment, the light emission amount control unit 184 is configured to be separated from the control unit 128, but the present invention is not limited thereto. That is, according to the present invention, the light emission amount control unit 184 may be included in the control unit 128.

The optical measuring sensor 190 has a function of measuring the brightness (luminance) of the outer periphery of the imaging device 100 and transmitting the same to the controller 128. As the optical measuring sensor 190, a sensor such as a photodiode, a photo transistor, a photo IC, and the like, which are commonly used, may be used.

In this embodiment, the information measured by the optical measuring sensor 190 is transmitted to the control unit 128, the control unit 128 has such a configuration to transmit such information back to the light emission amount control unit 184, the present invention is limited thereto. I never do that. That is, according to the present invention, the photometric sensor 190 and the light emission amount control unit 184 may be directly electrically connected, and if so, the information measured by the light measurement sensor 190 is directly transmitted to the light emission amount control unit 184. Done.

In the present exemplary embodiment, the optical measuring sensor 190 is used to measure the brightness (luminance) of the outside of the imaging apparatus 100, but the present invention is not limited thereto. That is, according to the present invention, when there is an auto exposure function of the imaging device 100, brightness information of the external periphery of the imaging device 100 measured while performing the auto exposure function may be used. In that case, a separate optical measuring sensor 190 is not necessary.

Hereinafter, with reference to FIG. 4, operation | movement of the imaging device 100 of this embodiment is demonstrated.

4 is a schematic flowchart illustrating an operation of an imaging device according to an embodiment of the present invention.

In step S1, the power supply of the imaging device 100 is turned on. When the power is turned on, the imaging device 114 is controlled to perform exposure and reading of the image at regular intervals (1/30 second unit). Here, one image acquired in 1/30 second units is called one frame.

The read-out image is displayed in real time on the display part 124 arrange | positioned at the back surface of the imaging device as a live view. In this case, the photometer sensor 190 measures the brightness (luminance) of the surroundings of the imaging device 100, and the measured brightness data is transmitted to the controller 128.

In the present embodiment, in step S1, the optical sensor 190 measures the brightness of the surroundings of the imaging device 100, the measured brightness data is transmitted to the controller 128, but the present invention is not limited thereto. . That is, according to the present invention, the luminance around the imaging apparatus 100 and the luminance of the subject may be extracted from the image data acquired in the preview mode and transmitted to the controller 128 without using the photometric sensor 190.

Then, in step S2, the B1 operation is performed by the photographer. The B1 operation is also referred to as a half-press operation of the shutter button. The user does not press the shutter button completely, but presses it halfway to perform the B1 operation.

Next, in step S3, the light emission amount control unit 184 determines the magnitude of the amount of light of the auxiliary light for AF based on the data of the brightness of the surroundings of the imaging device 100 obtained in step S1. That is, the data of the brightness around the imaging device 100 transmitted to the control unit 128 in step S1 is transmitted to the light emission amount control unit 184 and calculated in step S3 to determine the optimal amount of AF auxiliary light for AF.

In the present embodiment, the brightness data of the surroundings of the imaging device 100 is measured in step S1, and the measured brightness data is transferred to the light emitting amount control unit 184 and calculated in step S3, but the present invention is not limited thereto. That is, according to the present invention, there is no particular limitation at the time when the brightness data around the imaging device is measured. For example, both the time point at which the brightness data around the imaging device is measured and the time point at which the measured brightness data is transmitted to the light emission amount control unit may be performed at step S3.

Specifically, the amount of light of the AF auxiliary light emitted can be continuously changed in accordance with the brightness around the imaging device 100. In addition, after determining two to four levels according to the magnitude of the brightness around the imaging device 100 in advance, when the measured brightness reaches each level, the amount of light of the AF auxiliary light may be determined to match each level.

For example, if the brightness of the surroundings of the imaging device 100 is divided into two stages (first stage is very dark, and the second stage is slightly dark), when the measured peripheral brightness corresponds to the first stage, The amount of light of the AF auxiliary light is controlled to be larger than that of the second step.

Of course, if the peripheral brightness of the imaging device 100 is sufficiently bright and the AF operation is sufficiently performed without using the AF auxiliary light, the required amount of the AF auxiliary light is zero, and it is not necessary to irradiate the AF auxiliary light.

In the next step S4, the AF auxiliary light is emitted. To this end, the power is applied to the lamp 182a of the auxiliary light emitting unit 182, but by adjusting the current input to the lamp 182a, the AF auxiliary light irradiated to the subject has the amount of light determined in step S3.

Then, in step S5, AF is performed.

The AF of step S5 consists of an AF evaluation value calculation process, a focal position calculation process, and a focus mechanism driving process. The AF performed here is video AF which performs AF based on the contrast of the image data read out by the imaging element 114. That is, the image light of the subject irradiated with the AF auxiliary light is received by the imaging device 114, and AF is started based on the contrast data of the received image light.

The AF evaluation value calculation step is a step of sequentially calculating the contrast value (AF evaluation value) of the image of each frame read while driving the focus lens 112a in conjunction with the control of the imaging device 114 at the same time that AF is started. to be. Here, the positions of the focus lens 112a correspond to the data of these contrast values, respectively.

After calculating the AF evaluation value, calculation of the in-focus position is performed. The state in which the contrast value of the image is the highest is congruent, and the focal position is calculated as the focus position corresponding to the frame in which the contrast value is the highest.

After calculation of the in-focus position is performed, the focus mechanism 112 is driven to the calculated in-focus position. That is, the motor driver 112c is driven by the signal from the controller 128, and the focus motor 112b is driven by the motor driver 112c, thereby moving the focus lens 112a to the focusing position.

Next, in step S6, shooting exposure conditions are determined by an AE (Auto Exposure) calculation.

In a next step S7, it is determined whether the B1 operation is OFF. When the B1 operation is turned off, the photographer releases the shutter button half pressed, so that the camera moves between steps S1 and S2. On the other hand, when B1 operation is not turned off in step S7, it progresses to step S8.

In step S8, it is determined whether the B2 operation has been performed by the photographer.

When the operation B2 is performed, the process after step S9 is performed to start the photographing exposure operation, and when the operation B2 is not performed, the operation moves between the steps S6 and S7.

In step S9, the exposure is performed by opening the shutter 113.

Next, post-exposure post-processing is performed in step S10 to read out the image signal exposed in step S9, process the signal, and store the captured image data.

After the step S10, the photographing process ends.

As described above, according to the imaging apparatus 100 and the control method thereof according to the present embodiment, when irradiating the AF auxiliary light for the AF operation, the amount of light amount of the AF auxiliary light can be adjusted according to the brightness around the imaging device 100. There is an effect that the power consumption of the imaging device 100 can be reduced efficiently.

In addition, according to the present embodiment, the imaging device 100 is made of a compact digital camera, but the present invention is not limited thereto. That is, there is no particular limitation on the type and format of the imaging device according to the present invention. For example, the imaging apparatus according to the present invention may be applied to various kinds and types of imaging apparatuses such as a single-lens reflex camera and an image camcorder, which are detachable from a lens.

Although the present invention has been described with reference to the embodiments illustrated in the accompanying drawings, it is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible therefrom. Could be. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

1 is a perspective view of an imaging device according to an embodiment of the present invention.

FIG. 2 is a rear view of the imaging device shown in FIG. 1.

FIG. 3 is a schematic diagram showing an internal configuration of the imaging device shown in FIG. 1.

4 is a schematic flowchart illustrating an operation of an imaging device according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: imaging device 111: lens unit

112: focus mechanism 112a: focus lens

112b: focus motor 112c: motor driver

113: shutter 114: imaging device

115: CDS circuit 116: A / D converter

117: Image input controller 118: White balance adjustment unit

120: compression processing circuit 122: display driver

124: display unit 126: timing generator

128: control unit 132: input unit

134: memory 136: VRAM

138: media controller 140: recording media

150: battery 160: viewfinder

170: flash 182: auxiliary light emitting unit

182a: lamp 182b: lens

184: light emission control unit 190: optical measuring sensor

Claims (10)

An imaging device that performs an auto focus operation, An optical unit transmitting image light; An imaging device for receiving the image light transmitted through the optical unit; An auxiliary light emitting unit for emitting an auxiliary light for the auto focus operation; And And an emission amount controller configured to determine the magnitude of the amount of light of the auxiliary light based on the brightness of the surroundings of the imaging device. The method of claim 1, And the optical unit comprises a focus lens for performing the auto focus operation. The method of claim 1, The auxiliary light emitting unit includes a light source including a light emitting diode (LED). The method of claim 1, And an optical measuring sensor for measuring the brightness of the surroundings of the imaging device. The method of claim 4, wherein And the light emission amount control unit determines the size of the light emission amount based on the brightness around the image pickup device measured by the optical measuring sensor. In the control method of the imaging device to perform the auto focus operation, (a) measuring the brightness of the surroundings of the imaging device; (b) determining the magnitude of the amount of light of the auxiliary light required to perform the auto focus operation based on the measured brightness of the surroundings of the imaging device; (c) emitting the auxiliary light according to the amount of light of the determined auxiliary light; And and (d) performing the auto focus operation with the emitted auxiliary light. The method of claim 6, Step (a) is performed by the optical measuring sensor of the imaging device. The method of claim 6, Step (a), the control method of the imaging device made of the automatic exposure (Auto Exposure) function of the imaging device. The method of claim 6, The step (c) is a control method of an imaging device, which is performed by a light source made of a light emitting diode. The method of claim 6, Step (d), wherein the control method of the imaging device is achieved by moving the focus lens in the optical axis direction.

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