JP2006222806A - Photographing device, and method and program of controlling photographing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographing device capable of maximally suppressing the power consumption by light emission of a light emitting means such as a strobe while the power consumption should be suppressed, and to provide a method and program of controlling the photographing device. <P>SOLUTION: When the power consumption is to be suppressed, a CPU 40 inhibits emission of light from a light emission tube 64, and when the photographing is executed and exposure is deficient and in the case of the state in which the power consumption should be suppressed, the CPU 40 adjusts the sensitivity of a CCD 24 higher by a prescribed rate than that of the other cases. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image capturing apparatus, an image capturing apparatus control method, and a control program, and more particularly, to an image capturing apparatus having light emitting means such as a strobe light and an image sensor, and a control method and control program for the image capturing apparatus.

  In recent years, the demand for digital cameras has been rapidly increasing with the increase in resolution of imaging devices such as CCD (Charge Coupled Device) area sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors.

  By the way, in this kind of digital camera, underexposure may occur at the time of shooting due to the darkness of the subject. As a conventional technique that can be applied to solve this, the gain of the signal processing system is increased electrically. As a result, there have been techniques for increasing the apparent sensitivity of the image sensor (see, for example, Patent Document 1 and Patent Document 2), a technique for forcibly emitting a strobe light, and the like.

  On the other hand, when using a battery as a power source, a digital camera may want to reduce power consumption, such as when the remaining battery level is low. When using a digital camera equipped with a strobe that emits light and illuminates the subject when shooting, the power consumption of the strobe is large when shooting in a relatively dark place where the strobe must be fired. It was difficult to suppress power consumption.

  Therefore, as a technique that can be applied to solve this problem, conventionally, when it is predicted that the power consumption of the strobe will increase and cause inconvenience, the aperture will be reduced so as to reduce the amount of light of the strobe more than other cases. There has been a technique in which guide number control is performed with a small aperture value opened (see, for example, Patent Document 3).

By applying this technique to a digital camera, it is possible to suppress power consumption.
JP 61-32668 A JP-A-61-32670 JP-A-9-297340

  However, although the power consumption can be suppressed to some extent by reducing the amount of light from the strobe, the above-described conventional technology cannot stop the light emission of the strobe. There was a problem that it was not always sufficient.

  The present invention has been made in order to solve the above-described problems, and an imaging device capable of suppressing power consumption due to light emission of a light emitting means such as a strobe to the maximum when power consumption should be suppressed, An object of the present invention is to provide a control method and a control program for an imaging apparatus.

  In order to achieve the above object, an imaging device according to claim 1 is an imaging device that captures an image of a subject and outputs an image signal indicating the image of the subject, and when shooting is performed and exposure is insufficient. By determining whether or not the remaining amount of a battery as a power source is less than a predetermined amount, light emitting means for emitting photographing auxiliary light to the subject, and sensitivity adjusting means for adjusting sensitivity of the image sensor Determining means for determining whether or not power consumption should be suppressed, and prohibition for prohibiting light emission of the light emitting means when the determination means determines that power consumption should be suppressed And when the photographing is performed and the exposure is insufficient, when the determination means determines that the power consumption should be suppressed, the sensitivity is higher by a predetermined degree than in other cases. Expensive And a, and control means for controlling the sensitivity adjustment means so.

  According to another aspect of the present invention, a photographing device captures a subject and outputs an image signal indicating a subject image. When the photographing is performed and the exposure is insufficient, the light emitting unit is provided. Is emitted, and the subject is irradiated with photographing auxiliary light. Note that the imaging element includes a solid-state imaging element such as a CCD area sensor or a CMOS image sensor. Further, the light emitting means includes not only a light emitting tube for generating irradiation light but also an LED (light emitting diode) for generating irradiation light.

  According to the first aspect of the present invention, the sensitivity of the image sensor is adjusted by the sensitivity adjusting means, and the power consumption is reduced by determining whether the remaining amount of the battery as the power source is less than a predetermined amount. It is assumed that the determination means determines whether or not the state should be suppressed.

  Here, in the photographing apparatus of the present invention, when the prohibiting means determines that the power consumption should be suppressed by the determining means, the light emission of the light emitting means is prohibited, and the control means takes a picture. When performing and when exposure is insufficient, when the determination means determines that power consumption should be suppressed, the sensitivity is increased by a predetermined degree compared to other cases. The sensitivity adjusting means is controlled.

  As described above, according to the photographing apparatus of the first aspect, when the power consumption is to be suppressed, the light emitting unit is prohibited from emitting light, and when photographing is performed, the exposure is insufficient. When the power consumption is in a state where power consumption should be suppressed, the sensitivity of the image sensor is adjusted to be higher by a predetermined degree than in other cases. Power consumption due to light emission of the light emitting means can be suppressed to the maximum.

  In particular, the determination means of the present invention determines whether or not the power consumption should be suppressed by determining whether or not the remaining amount of the battery as a power source is less than a predetermined amount. Therefore, power consumption due to light emission of the light emitting means when the remaining amount of the battery is low can be suppressed to the maximum.

  Note that the determination unit of the present invention may determine whether or not the power consumption should be suppressed by determining whether or not a power saving mode is set. Thereby, the power consumption by light emission of the light emission means when the power saving mode is set can be suppressed to the maximum.

  Further, according to the present invention, as in the invention described in claim 2, the predetermined degree may be a degree corresponding to the insufficient amount of exposure. Thereby, the sensitivity of an image pick-up element can be adjusted simply and appropriately.

  In addition, as in the invention described in claim 3, the present invention provides notification means for notifying that the exposure is inappropriate when the exposure is not appropriate even if the sensitivity is increased by the control by the control means. Further, it may be provided. Thereby, it can be made to grasp | ascertain that an exposure is improper and a user can improve the convenience. Note that the notification by the notification means includes notification by sound such as sounding of a buzzer sound or reading of a message, in addition to notification by display by a display device.

  Further, according to the present invention, as in the invention described in claim 4, when the sensitivity is increased by the control by the control means, if the exposure is not appropriate, the light emission means has a light emission amount with an appropriate exposure. It may be further provided with permission means for allowing light emission. Thereby, even when the exposure cannot be optimized only by adjusting the sensitivity, the exposure can be optimized while maximizing the power consumption by the light emission of the light emitting means.

  Further, the sensitivity adjusting means of the present invention may adjust the sensitivity by adjusting an amplification factor of an image signal output from the imaging device, as in the invention described in claim 5. Thereby, it is possible to avoid the influence due to camera shake that occurs when adjusting the sensitivity by adjusting the shutter speed of the image sensor, and it is possible to obtain a good captured image.

  Note that, since the photographing apparatus is usually provided with a gain control amplifier (GCA) that corrects the gain for each color signal of the image signal output from the image sensor, sensitivity adjustment is performed using the GCA. If comprised in this way, this invention is realizable, without causing a cost increase.

  According to a sixth aspect of the present invention, as in the sixth aspect of the present invention, a lens that forms an image of light carrying the subject image on a light receiving surface of the imaging device, and an aperture that adjusts the amount of light passing through the lens The sensitivity adjusting means may adjust the sensitivity by adjusting the diaphragm. Also by this, it is possible to avoid the influence due to camera shake that occurs when the sensitivity is adjusted by adjusting the shutter speed of the image sensor, and a good captured image can be obtained.

  Further, as in the invention according to claim 7, the sensitivity adjusting means of the present invention adjusts the amplification factor of the image signal output from the image sensor and receives the light carrying the subject image by the image sensor. The sensitivity may be adjusted by a combination of two adjustments for adjusting the diaphragm for adjusting the amount of light passing through the lens that forms an image on the surface. Thereby, compared with the case where the sensitivity is adjusted by either the amplification factor for the output signal from the image sensor and the diaphragm, the adjustable sensitivity range is widened, and the convenience can be improved.

  On the other hand, in order to achieve the above object, a method for controlling an imaging apparatus according to an eighth aspect of the present invention includes an imaging device that captures an image of a subject and outputs an image signal indicating the subject image; And a light emitting unit that emits light when it is in shortage and emits photographing auxiliary light to the subject, and the light emission when the remaining amount of a battery as a power source is less than a predetermined amount When the photographing is performed and the exposure is insufficient, the imaging is performed so that the remaining amount of the battery is higher by a predetermined degree than the other cases when the remaining amount of the battery is smaller than the predetermined amount. The sensitivity of the element is adjusted.

  Therefore, according to the control method of the photographing apparatus according to the eighth aspect, since it operates in the same manner as the invention according to the first aspect, the power consumption should be suppressed as in the first aspect. Sometimes power consumption due to light emission of the light emitting means can be suppressed to the maximum.

  On the other hand, in order to achieve the above object, a control program for an imaging device according to claim 9 includes: an imaging device that images a subject and outputs an image signal indicating a subject image; And a light emitting means for emitting photographing auxiliary light to the subject to emit light when there is a shortage, and the light emission when the remaining amount of a battery as a power source is less than a predetermined amount A prohibiting step for prohibiting the light emission of the means, and when performing shooting and underexposure, so that when the remaining amount of the battery is less than the predetermined amount, it becomes higher by a predetermined degree than in other cases An adjustment step for adjusting the sensitivity of the image sensor is executed by a computer.

  Therefore, the control program for the photographing apparatus according to claim 9 can cause the computer to act similarly to the invention according to claim 1, so that the power consumption should be suppressed similarly to the invention according to claim 1. When in the state, power consumption due to light emission of the light emitting means can be suppressed to the maximum.

  According to the present invention, when the power consumption should be suppressed, the light emission of the light emitting means is prohibited, and the power consumption should be suppressed when shooting is performed and when the exposure is insufficient. Since the sensitivity of the image sensor is adjusted so that it is higher by a certain degree when it is in the state than in other cases, the power consumption due to the light emission of the light emitting means is maximized when the power consumption should be suppressed It is possible to obtain an effect of being able to be suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, a case where the present invention is applied to a digital camera will be described.

[First Embodiment]
First, an external configuration of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  In front of the digital camera 10, there are provided a lens 21 for forming a subject image and a light emitting tube 64 (not shown in FIG. 1, not shown in FIG. 2) that emits light for irradiating the subject as necessary during photographing. And a finder 20 used to determine the composition of the subject to be photographed. Further, the upper surface of the digital camera 10 is provided with a release button 56A, a power switch 56B, and a mode changeover switch 56C that are pressed when shooting.

  Note that the release button 56A of the digital camera 10 according to the present embodiment is pressed down to an intermediate position (hereinafter referred to as “half-pressed state”) and to a final pressed position beyond the intermediate position. A two-stage pressing operation of a state (hereinafter referred to as a “fully pressed state”) can be detected.

  In the digital camera 10, the release button 56A is pressed halfway to activate the AE (Automatic Exposure) function to set the exposure state (shutter speed, aperture state), and then AF (Auto Focus). , Automatic focusing) function is performed to control focusing, and then exposure (photographing) is performed when the button is fully pressed.

  The mode changeover switch 56C is rotated when setting to any one of a shooting mode that is a mode for performing shooting and a playback mode that is a mode for playing back a subject image by the LCD 38 described later.

  On the other hand, on the back of the digital camera 10, an eyepiece of the finder 20 described above, a liquid crystal display (hereinafter referred to as “LCD”) 38 for displaying a photographed subject image, a menu screen, and the like, and a cross cursor A button 56D. The cross-cursor button 56D includes four arrow buttons that indicate four moving directions of up, down, left, and right in the display area of the LCD 38.

  Further, on the back of the digital camera 10, a menu button that is pressed when displaying the menu screen on the LCD 38, a determination button that is pressed when confirming the operation content up to that point, and the previous operation content are displayed. A cancel button that is pressed when canceling and a strobe button that is pressed when setting the light emission state of the strobe 44 are provided.

  Next, the main configuration of the electrical system of the digital camera 10 according to the present embodiment will be described with reference to FIG.

  The digital camera 10 includes an optical unit 22 including the lens 21 described above, a charge coupled device (hereinafter referred to as “CCD”) 24 disposed behind the optical axis of the lens 21, and an input analog. And an analog signal processing unit 26 that performs various analog signal processing on the signal.

  The digital camera 10 includes a gain control amplifier (hereinafter referred to as “GCA”) 27 that corrects a gain error of an input analog signal, and an analog / digital converter (hereinafter referred to as “GCA”) that converts the input analog signal into digital data. (Hereinafter referred to as “ADC”) 28, and a digital signal processing unit 30 that performs various digital signal processing on the input digital data.

  The digital signal processing unit 30 has a built-in line buffer having a predetermined capacity, and also performs control to directly store the input digital data in a predetermined area of the memory 48 described later.

  The output end of the CCD 24 is the input end of the analog signal processing unit 26, the output end of the analog signal processing unit 26 is the input end of the GCA 27, the output end of the GCA 27 is the input end of the ADC 28, and the output end of the ADC 28 is the digital signal processing unit. 30 input terminals are connected to each other. Therefore, the analog signal indicating the subject image output from the CCD 24 is subjected to predetermined analog signal processing by the analog signal processing unit 26, the gain error is corrected by the GCA 27, converted into digital image data by the ADC 28, and then digitally processed. The signal is input to the signal processing unit 30.

  On the other hand, the digital camera 10 generates a signal for displaying a subject image, a menu screen or the like on the LCD 38 and supplies the signal to the LCD 38, and a CPU (Central Processing Unit) 40 that controls the operation of the entire digital camera 10. A memory 48 for storing digital image data obtained by photographing, and a memory interface 46 for controlling access to the memory 48 are included.

  Further, the digital camera 10 includes an external memory interface 50 for enabling the portable memory card 52 to be accessed by the digital camera 10, and a compression / decompression processing circuit 54 for performing compression processing and decompression processing on the digital image data. It is configured to include.

  In the digital camera 10 of the present embodiment, a flash memory is used as the memory 48, and a smart media (Smart Media (registered trademark)) is used as the memory card 52.

  The digital signal processing unit 30, the LCD interface 36, the CPU 40, the memory interface 46, the external memory interface 50, and the compression / decompression processing circuit 54 are connected to each other via a system bus BUS. Therefore, the CPU 40 controls the operation of the digital signal processing unit 30 and the compression / decompression processing circuit 54, displays various information via the LCD interface 36 to the LCD 38, the memory interface 46 to the memory 48 and the memory card 52, and the external memory interface. Each access via 50 can be made.

  On the other hand, the digital camera 10 includes a timing generator 32 that mainly generates a timing signal for driving the CCD 24 and supplies the timing signal to the CCD 24, and the driving of the CCD 24 is controlled by the CPU 40 via the timing generator 32.

  Further, the digital camera 10 is provided with a motor drive unit 34, and driving of a focus adjustment motor, a zoom motor, and an aperture drive motor (not shown) provided in the optical unit 22 is also controlled by the CPU 40 via the motor drive unit 34. The

  In other words, the lens 21 according to the present embodiment has a plurality of lenses, is configured as a zoom lens that can change (magnify) the focal length, and includes a lens driving mechanism (not shown). The lens drive mechanism includes the focus adjustment motor, the zoom motor, and the aperture drive motor, and these motors are each driven by a drive signal supplied from the motor drive unit 34 under the control of the CPU 40.

  The optical unit 22 is provided with a diaphragm 22A for adjusting the amount of light passing through the lens 21, and the amount of light passing through the lens 21 is controlled by the CPU 40 via the diaphragm driving motor of the lens driving mechanism. Can be adjusted.

  Further, the release button 56A, the power switch 56B, the mode switch 56C, the cross cursor button 56D, various buttons such as a menu button, and switches (generically referred to as “operation unit 56” in the figure) are connected to the CPU 40. The CPU 40 can always grasp the operation state of the operation unit 56.

  On the other hand, the digital camera 10 has a trigger circuit 60 that is interposed between the arc tube 64 and the CPU 40 and controls the start of light emission of the arc tube 64 under the control of the CPU 40, and the charge of the arc tube 64. A main capacitor 66 that accumulates and a photocurrent control unit 62 that controls the photocurrent supplied from the main capacitor 66 to the arc tube 64 under the control of the CPU 40 are provided.

  When the release button 56A is fully pressed, the CPU 40 forcibly causes the arc tube 64 to emit light when the forced light emission mode is set by the strobe button. Even if the forced light emission mode is not set, the CPU 40 causes the arc tube 64 to emit light when it is determined that the release button 56A is fully pressed and the exposure is insufficient.

  By the way, in the digital camera 10 according to the present embodiment, on the menu screen displayed on the LCD 38 in response to the pressing operation of the menu button, the normal power mode that is a mode that does not particularly suppress power consumption and the power consumption are suppressed as much as possible. One of the two power modes of the power saving mode that is the mode to be selected can be selected. The normal power mode is a mode that consumes more power than the power saving mode, but can operate the digital camera 10 with the maximum capability. On the other hand, the power saving mode is the normal power mode. This is a mode in which the power consumption can be reduced to the maximum although the operating capability is inferior.

  On the other hand, the digital camera 10 according to the present embodiment maximizes the power consumption by the strobe light emission when the power consumption should be suppressed (here, the power saving mode is set). The power reduction function to suppress is installed.

  In the power reduction function according to the present embodiment, the light emission of the strobe 44 is prohibited when power consumption is to be suppressed, and the CCD 24 is used to compensate for the lack of exposure caused by the strobe 44 not emitting light. The apparent sensitivity of is increased by a predetermined degree.

  Here, in the power reduction function according to the present embodiment, the degree according to the insufficient amount of exposure is applied as the predetermined degree. For this reason, in this power reduction function, an underexposure amount / sensitivity increase amount characteristic as shown in FIG. 3 is applied as an example, and the sensitivity increase amount increases as the underexposure amount increases.

  In the digital camera 10 according to the present embodiment, a conversion table (hereinafter referred to as “underexposure amount / sensitivity”) converts the underexposure amount into the sensitivity increase amount according to the underexposure amount / sensitivity increase amount characteristic shown in FIG. "Increase conversion table") is stored in a predetermined area of the memory 48 in advance.

  Next, an overall operation at the time of shooting of the digital camera 10 according to the present embodiment will be briefly described.

  First, the CCD 24 performs imaging through the optical unit 22 and sequentially outputs analog signals for R (red), G (green), and B (blue) indicating the subject image to the analog signal processing unit 26. The analog signal processing unit 26 subjects the analog signal input from the CCD 24 to analog signal processing such as correlated double sampling processing, and then sequentially outputs it to the GCA 27.

  The GCA 27 corrects the gain error for each of R, G, and B with respect to the analog signal input from the analog signal processing unit 26, and then sequentially outputs it to the ADC 28. The ADC 28 converts the R, G, and B analog signals input from the GCA 27 into 12-bit R, G, and B signals (digital image data) and sequentially outputs them to the digital signal processing unit 30. The digital signal processing unit 30 accumulates digital image data sequentially input from the ADC 28 in a built-in line buffer and temporarily stores the digital image data directly in a predetermined area of the memory 48.

  The digital image data stored in a predetermined area of the memory 48 is read out by the digital signal processing unit 30 under the control of the CPU 40, and white balance adjustment is performed by applying a digital gain according to a predetermined physical quantity. Processing and sharpness processing are performed to generate 8-bit digital image data.

  The digital signal processing unit 30 performs YC signal processing on the generated 8-bit digital image data to generate a luminance signal Y and chroma signals Cr and Cb (hereinafter referred to as “YC signal”), and the YC signal. Are stored in an area different from the predetermined area of the memory 48.

  The LCD 38 is configured to display a moving image (through image) obtained by continuous imaging by the CCD 24 and can be used as a finder. When the LCD 38 is used as a finder, the LCD 38 is generated. The YC signals thus output are sequentially output to the LCD 38 via the LCD interface 36. As a result, a through image is displayed on the LCD 38.

  Here, at the timing when the release button 56A is half-pressed by the user, after the AE function is activated and the exposure state is set as described above, the AF function is activated and focus control is performed, and then the fully-pressed state continues. Then, the above-described power reduction function is executed, and then the YC signal stored in the memory 48 at that time is converted by the compression / decompression processing circuit 54 into a predetermined compression format (in this embodiment, After being compressed in the JPEG format), it is recorded as an electronic file on the memory card 52 via the external memory interface 50.

  Next, the operation of the digital camera 10 when the power reduction function is executed will be described with reference to FIG. FIG. 4 is a flowchart showing the flow of processing of the power reduction processing program executed by the CPU 40 when executing the power reduction function, and the program is stored in a predetermined area of the memory 48 in advance.

  First, in step 100, a photometric level indicating the brightness of the subject is obtained from the digital image data indicating the subject image obtained via the CCD 24, and in the next step 102, it is determined whether or not the power saving mode is set. If the determination is affirmative, the process proceeds to step 104.

  In step 104, settings are made so as to prohibit the subsequent flash 44 from emitting light. In the digital camera 10 according to the present embodiment, as a setting for prohibiting the light emission of the strobe 44, a setting for invalidating the trigger signal indicating the start of light emission of the arc tube 64 output from the CPU 40 to the trigger circuit 60 is provided. Although it is applied, the present invention is not limited to this. Settings other than the trigger signal for causing the flash 44 to emit light are invalidated, connection lines from the CPU 40 to the trigger circuit 60, and from the CPU 40 to the photocurrent control unit 62. It is also possible to provide a switch that can be electrically connected / disconnected to any one of the connecting line extending from the main capacitor 66 to the arc tube 64, and applying a setting for turning off the switch. it can.

  In the next step 106, it is determined whether or not the exposure is insufficient by determining whether or not the photometry level acquired in step 100 is lower than a predetermined level. If the program ends and the determination is affirmative, the routine proceeds to step 108.

  In step 108, using the underexposure / sensitivity increase conversion table (see also FIG. 3) stored in the memory 48, a sensitivity increase corresponding to the underexposure at this point is derived, and the next step At 110, a sensitivity increase process for increasing the apparent sensitivity of the CCD 24 by the derived sensitivity increase amount is executed.

  In the digital camera 10 according to the present embodiment, the sensitivity increasing process is performed by increasing the gain control gain in the GCA 27.

  That is, here, each of the gains of R, G, and B (the gains of R, G, and B for achieving the original purpose of GCA27) for correcting the gain error of the analog image signal of each color by GCA27. In addition, a sensitivity increase process is performed by adding an amplification factor corresponding to the sensitivity increase amount derived in step 108.

  Incidentally, as shown in FIG. 3, since there is an upper limit to the amount of increase in sensitivity due to the processing of step 110, there is a region where underexposure occurs even when the sensitivity is increased to the maximum.

  Therefore, in the next step 112, it is determined whether or not the exposure is insufficient even after the sensitivity is increased by the processing in step 110. If the determination is affirmative, the process proceeds to step 114 and is shown in FIG. 5 as an example. As shown, notification indicating that the exposure will be insufficient is performed, and then the power reduction processing program is terminated. If a negative determination is made in step 112, the power reduction processing program is terminated without executing the processing in step 114.

  On the other hand, if a negative determination is made in step 102, it is assumed that the normal power mode is set, the process proceeds to step 116, and it is determined whether the photometric level acquired in step 100 is lower than a predetermined level. In this case, it is determined whether or not the exposure is insufficient. If a negative determination is made, the power reduction processing program is terminated. If the determination is affirmative, the process proceeds to step 120 and the arc tube 64 emits light. After the trigger circuit 60 and the photocurrent control unit 62 are controlled to start, the power reduction processing program is terminated.

  As described above in detail, in the present embodiment, when the power consumption is to be suppressed, the light emission means (here, the strobe 44) is prohibited from emitting light and when photographing is performed. And when the exposure is insufficient, the sensitivity of the image sensor (here, the CCD 24) is adjusted so as to be higher by a predetermined degree than in other cases when the power consumption should be suppressed. When the power consumption should be suppressed, the power consumption due to the light emission of the light emitting means can be suppressed to the maximum.

  In this embodiment, since it is determined whether or not the power consumption should be suppressed by determining whether or not the power saving mode is set, the power saving mode is set. The power consumption due to the light emission of the light emitting means can be suppressed to the maximum.

  In the present embodiment, the predetermined degree is set to a degree corresponding to an insufficient amount of exposure, so that the apparent sensitivity of the image sensor can be adjusted easily and appropriately.

  Further, in the present embodiment, since it is informed that the exposure is not appropriate even when the apparent sensitivity of the image sensor is increased and the appropriate exposure is not obtained, the user is informed that the exposure is inappropriate. Can improve the convenience.

  Furthermore, in the present embodiment, since the sensitivity is adjusted by adjusting the amplification factor of the image signal output from the image sensor, the sensitivity is adjusted by adjusting the shutter speed of the image sensor. It is possible to avoid the influence due to the hand shake that occurs and to obtain a good captured image.

[Second Embodiment]
In the first embodiment, the state where the power saving mode is set as the state where power consumption should be suppressed is applied, and the apparent sensitivity of the CCD 24 is increased by increasing the gain control gain in the GCA 27. In the second embodiment, the state in which the remaining amount of the battery is low is applied and the opening state of the aperture 22A is adjusted in the second embodiment. A case where the apparent sensitivity of the CCD 24 is adjusted will be described.

  Since the configuration of the digital camera 10 according to the second embodiment is substantially the same as that of the digital camera 10 according to the first embodiment (see FIGS. 1 and 2), a detailed description thereof will be given here. Although omitted, the CPU 40 is configured to be able to detect the output voltage level of the attached power supply battery (not shown), and the CPU 40 determines the detected output voltage level based on the remaining amount of the power supply battery. Only the point used as the physical quantity shown is different from the digital camera 10 according to the first embodiment.

  That is, as shown in FIG. 6 as an example, the characteristics of the battery are generally such that the output voltage gradually decreases until a certain discharge capacity, and the output voltage decreases rapidly when the discharge capacity increases and the remaining battery capacity decreases. Tend. Therefore, it is possible to detect the magnitude of the discharge capacity, that is, the remaining battery level using the output voltage level of the battery. When the remaining battery level is low, the change in output voltage is large, so that the measurement error is small.

  Then, in digital camera 10 according to the present embodiment, when the remaining amount of the power battery indicated by the detected output voltage of the power battery is less than a predetermined amount, it is determined that power consumption should be suppressed. .

  On the other hand, in the digital camera 10 according to the second embodiment, if the power reduction function is underexposed even if the apparent sensitivity of the CCD 24 is increased to the maximum, the exposure of the strobe 44 is appropriate. It is assumed that light emission with a light emission amount of

  In the power reduction function according to the second embodiment, the underexposure amount / light emission amount characteristic as shown in FIG. 7 is applied as an example, and the light emission amount of the strobe 44 is increased as the underexposure amount increases. I am doing so.

  For this reason, in the digital camera 10 according to the second embodiment, a conversion table (hereinafter referred to as “underexposure amount”) that converts the underexposure amount into the light emission amount according to the underexposure amount / light emission amount characteristics shown in FIG. “Light emission amount conversion table”) is stored in a predetermined area of the memory 48 in advance.

  Next, the operation of the digital camera 10 according to the second embodiment at the time of executing the power reduction function will be described with reference to FIG. FIG. 8 is a flowchart showing the flow of processing of the power reduction processing program executed by the CPU 40 when executing the power reduction function. The program is stored in a predetermined area of the memory 48 in advance. Further, steps in FIG. 8 that perform the same processes as those in FIG. 4 are denoted by the same step numbers as those in FIG.

  In step 102B, the output voltage of the power battery is detected, and it is determined whether or not the remaining amount of the power battery indicated by the output voltage is less than a predetermined amount. If the determination is affirmative, the process proceeds to step 104. If a negative determination is made, the process proceeds to step 116.

  Further, in step 110B, a sensitivity increase process for increasing the apparent sensitivity of the CCD 24 by the sensitivity increase amount derived in step 108 is executed, and then the process proceeds to step 112.

  In the digital camera 10 according to the second embodiment, the sensitivity increasing process is performed by increasing the amount of light passing through the lens 21 defined by the diaphragm 22A.

  That is, here, the sensitivity increasing process is performed by adjusting the stop 22A so that the amount of light passing through the lens 21 is increased by an amount corresponding to the sensitivity increasing amount derived in step 108.

  Further, when an affirmative determination is made at step 112, that is, when the exposure is insufficient even after the sensitivity is increased by the processing at step 110B, at step 113, the underexposure amount / light emission amount stored in the memory 48 is obtained. Using the conversion table (see also FIG. 7), the light emission amount corresponding to the underexposure amount at this time is derived, and in the next step 115, the light emitting tube 64 of the strobe 44 emits light with the derived light emission amount. After the trigger circuit 60 and the photocurrent control unit 62 are controlled, the power reduction processing program is terminated.

  As described above in detail, in the present embodiment, when the power consumption is to be suppressed, the light emission means (here, the strobe 44) is prohibited from emitting light and when photographing is performed. And when the exposure is insufficient, the sensitivity of the image sensor (here, the CCD 24) is adjusted so as to be higher by a predetermined degree than in other cases when the power consumption should be suppressed. When the power consumption should be suppressed, the power consumption due to the light emission of the light emitting means can be suppressed to the maximum.

  In the present embodiment, since it is determined whether or not the power consumption should be suppressed by determining whether or not the remaining amount of the power battery is less than a predetermined amount, Power consumption due to light emission of the light emitting means when the remaining amount is low can be suppressed to the maximum.

  In the present embodiment, the predetermined degree is set to a degree corresponding to an insufficient amount of exposure, so that the apparent sensitivity of the image sensor can be adjusted easily and appropriately.

  Further, in the present embodiment, if the exposure is not appropriate even if the apparent sensitivity of the image sensor is increased, the light emission means is allowed to emit light with the appropriate amount of light emission. Even when the exposure cannot be optimized only by adjusting the exposure, the exposure can be optimized while maximizing the power consumption due to the light emission of the light emitting means.

  Furthermore, in the present embodiment, the sensitivity is adjusted by adjusting the aperture, so that it is possible to avoid the influence of camera shake that occurs when adjusting the sensitivity by adjusting the shutter speed of the image sensor, A good captured image can be obtained.

  In the first embodiment, the apparent sensitivity of the CCD 24 is adjusted by adjusting the amplification factor of the image signal output from the CCD 24. In the second embodiment, the diaphragm 22A is adjusted. Although the case where the apparent sensitivity of the CCD 24 is adjusted by performing the above has been described, the present invention is not limited to this, and a mode in which the apparent sensitivity of the CCD 24 is adjusted by a combination of these adjustments. You can also

  Thereby, compared with each said embodiment, the range of the sensitivity which can be adjusted spreads and the convenience can be improved.

  In each of the above embodiments, the case where the conversion table (see FIGS. 3 and 7) is applied to derive the sensitivity increase amount and the light emission amount has been described, but the present invention is not limited to this. For example, an arithmetic expression (function) that can derive the same value as that of the conversion table may be applied. Also in this case, the same effects as those of the above embodiments can be obtained.

  In addition, the configuration of the digital camera 10 according to each of the above-described embodiments (see FIGS. 1 and 2) is an example, and it goes without saying that the configuration can be appropriately changed without departing from the gist of the present invention.

  The processing flow of the power reduction processing program described in each of the above embodiments (see FIGS. 4 and 8) is also an example, and it goes without saying that it can be changed as appropriate without departing from the gist of the present invention. Yes.

  The various conversion tables (see FIGS. 3 and 7) applied in the above embodiments are also examples, and it goes without saying that they can be changed as appropriate without departing from the gist of the present invention.

  Further, although cases have been described with the above embodiments where the present invention is applied to a digital camera, the present invention can be applied to photographing auxiliary light such as a PDA (Personal Digital Assistant), a mobile phone, a personal computer, and the like. Needless to say, the present invention can be applied to all information processing apparatuses having a light emitting means and an image sensor.

It is an external view which shows the external appearance of the digital camera 10 which concerns on embodiment. It is a block diagram which shows the main structures of the electric system of the digital camera 10 which concerns on embodiment. It is a graph which shows the underexposure amount / sensitivity increase amount characteristic which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the electric power reduction process program which concerns on 1st Embodiment. It is the schematic which shows an example of the display screen by LCD38 which alert | reports that it will become underexposure in the middle of execution of the electric power reduction process program which concerns on 1st Embodiment. It is a graph which shows an example of the change of the output voltage with respect to the discharge capacity of a general battery. It is a graph which shows the underexposure amount and light emission amount characteristic which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the electric power reduction process program which concerns on 2nd Embodiment.

Explanation of symbols

10 Digital camera 21 Lens 22A Aperture (sensitivity adjusting means)
24 CCD (imaging device)
27 GCA (sensitivity adjusting means)
38 LCD (notification means)
40 CPU (determination means, prohibition means, control means, permission means)
44 Strobe (light emission means)
64 arc tube

Claims (9)

An image sensor that images a subject and outputs an image signal indicating the subject image;
A light-emitting means that emits light when shooting is performed and when the exposure is insufficient and irradiates the subject with shooting auxiliary light;
Sensitivity adjusting means for adjusting the sensitivity of the image sensor;
Determination means for determining whether or not the power consumption should be suppressed by determining whether or not the remaining amount of the battery as the power source is less than a predetermined amount;
Prohibiting means for prohibiting light emission of the light emitting means when it is determined by the determining means that power consumption should be suppressed;
When shooting is performed and when the exposure is insufficient, the sensitivity is increased by a predetermined degree when compared with other cases when it is determined by the determination means that the power consumption should be suppressed. Control means for controlling the sensitivity adjustment means;
An imaging device with The photographing apparatus according to claim 1, wherein the predetermined degree is a degree corresponding to the insufficient amount of exposure. The photographing apparatus according to claim 1, further comprising a notifying unit that notifies that the exposure is inappropriate when the exposure is not appropriate even when the sensitivity is increased by the control by the control unit. The permission means which permits the light emission of the said light emission means by the light emission amount with which exposure becomes appropriate when the said exposure does not become appropriate exposure even if it raises the sensitivity by control by the said control means. The photographing apparatus described. The imaging apparatus according to claim 1, wherein the sensitivity adjustment unit adjusts the sensitivity by adjusting an amplification factor of an image signal output from the imaging element. A lens for forming light bearing the subject image on a light receiving surface of the image sensor;
A diaphragm for adjusting the amount of light passing through the lens;
Further comprising
The photographing apparatus according to claim 1, wherein the sensitivity adjusting unit adjusts the sensitivity by adjusting the diaphragm. The sensitivity adjusting unit adjusts the gain of the image signal output from the image sensor and adjusts the amount of light passing through a lens that forms the light carrying the subject image on the light receiving surface of the image sensor. The photographing apparatus according to any one of claims 1 to 4, wherein the sensitivity is adjusted by a combination of two adjustments of an aperture adjustment. An image sensor that captures an image of a subject and outputs an image signal indicating the image of the subject, and a light emitting unit that emits light when shooting is performed and when the exposure is insufficient, and irradiates the subject with assisting light. A method for controlling a photographing apparatus comprising:
When the remaining amount of the battery as a power source is less than a predetermined amount, the light emission of the light emitting means is prohibited, and when the photographing is performed and the exposure is insufficient, the remaining amount of the battery is less than the predetermined amount. Adjusting the sensitivity of the image sensor to be higher by a predetermined degree than in other cases when there are few,
Control method of photographing apparatus. An image sensor that captures an image of a subject and outputs an image signal indicating the image of the subject, and a light emitting unit that emits light when shooting is performed and when the exposure is insufficient, and irradiates the subject with assisting light. A control program for a photographing apparatus comprising:
A prohibiting step of prohibiting light emission of the light emitting means when the remaining amount of the battery as a power source is less than a predetermined amount;
An adjustment step for adjusting the sensitivity of the image sensor so that when the photographing is performed and the exposure is insufficient, the remaining amount of the battery is lower than the predetermined amount so that it is higher by a predetermined degree than the other cases. When,
Control program for an imaging apparatus that causes a computer to execute

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