JP2006180350A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus performing stable photographing without being affected by the capacity decline of a battery under a photographing environment wherein the capacity of the battery rapidly declines, which is represented by a cold photographing environment. <P>SOLUTION: In the imaging apparatus, the temperature of the battery which is a power source for the operation of an imaging apparatus main body is detected in a temperature detection means, the drive signal frequency of a drive control signal generation means is decelerated in a reference signal generation means on the basis of the detected result, and power consumption in the imaging apparatus is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention, for example, reduces the pixel transfer clock of the image sensor or the backlight illumination of the LCD display under shooting conditions at a low temperature where battery consumption is remarkably low, such as shooting at a snow festival venue or a ski resort. The present invention relates to an imaging apparatus that can perform stable photographing even when a battery is exhausted by reducing a current for use.

  2. Description of the Related Art In recent years, imaging devices such as electronic cameras and digital video cameras have come to be required to have high resolution and high definition as the performance of imaging devices represented by CCD (Charge Coupled Device) as performance increases. . For example, the image pickup device when the electronic camera was first commercialized was mainly VGA (Video Graphics Array; number of pixels = 640 × 480 pixels), but recently, SXGA (Super Extended Graphics Array; pixels). Number = 1280 × 1024 pixels) and 5 million pixel class image sensors.

  In addition, a large display device with backlight illumination is adopted as a display device represented by an LCD (Liquid Crystal Display) used for visually recognizing a shooting standby image and a reproduced image. Image display is now possible. In particular, the high pixel graphics subsystem such as VGA and SVGA (Super Video Graphics Array: 800 × 600 pixels) is used for the need to perform operations such as visual recognition and focus adjustment on the display device as with the optical viewfinder. It is being considered for use in display devices.

  On the other hand, an image sensor with a high pixel density increases the frequency of the drive signal so that it can handle high-speed driving. However, if the drive signal is increased in speed, the power consumption increases and the battery is consumed relatively quickly. is there. In addition, large LCDs with backlight illumination also consume battery power because of the high power consumption of backlight illumination.

  As described above, the increase in power consumption due to the high-speed driving of the high-pixel image sensor and the increase in the size of the backlight illumination device of the LCD display device has a great influence on the number of shots, and energy saving measures are required. Various imaging devices that consider energy saving measures have been studied.

Specifically, by detecting the output voltage of the battery installed in the digital camera and the temperature inside the digital camera, and reducing the time until the sleep operation is started based on the detection result, the consumption of the battery is suppressed. There is a technique (for example, refer to Patent Document 1) for performing energy saving measures. In addition, there is a video camera technique (for example, Patent Document 2) that detects a decrease in illuminance of a subject and automatically reduces the frame rate to reduce power consumption. As described above, various techniques for imaging devices that have reduced power consumption and have been designed to save energy have been studied.
JP 2001-69397 A (see paragraph 0010 etc.) JP 2000-23003 (see paragraph 0019, etc.)

  By the way, there are cases where digital cameras are used in cold temperature environments such as snow festival venues and ski resorts, but the batteries normally used in digital cameras are alkaline primary batteries, nickel metal hydride secondary batteries, lithium ion secondary batteries. These are batteries, etc., and these tend to rapidly decrease in capacity when used at low temperatures. For this reason, when a digital camera is used in a low temperature environment, the number of images that can be photographed is greatly reduced due to a decrease in battery capacity, which may hinder photography. In particular, the problem is serious in an image pickup apparatus that drives a high-pixel image pickup element at a high speed or has a large LCD display device with backlight illumination. In addition, the above-mentioned energy-saving technology cannot fully exhibit its effect in a low-temperature environment where the battery characteristics are significantly deteriorated. Therefore, it is hoped that the energy-saving technology will not hinder shooting even in a low-temperature environment. It was rare.

  The present invention has been made in view of the above problems, and can perform stable shooting without drastically reducing the battery capacity even under shooting conditions in which the battery capacity is significantly reduced, such as in a cold shooting environment. An object is to provide a possible imaging device.

  In particular, an imaging device that can perform high-speed imaging of a high-pixel imaging device and can perform good shooting without drastic decrease in battery capacity even in a low-temperature environment even with a large LCD display device with backlight illumination The purpose is to do.

  The object is achieved by the invention described in any one of claims 1 to 4 below.

(Claim 1)
Imaging means for photoelectrically converting a subject light image to generate an image signal;
Drive control signal generating means for generating a control signal for controlling driving of the imaging means;
Reference signal generating means for generating a reference signal used in the drive control signal generating means;
Reference signal control means for controlling the operation of the reference signal generation means;
A battery as a power source for operation;
Detecting means for detecting the temperature of the battery, the reference signal control means based on the detection result of the detecting means,
An image pickup apparatus that controls an operation of the reference signal generating means.

(Claim 2)
The reference signal control means includes
Comparing a preset reference temperature of the battery and the temperature of the battery detected by the detection means,
The imaging apparatus according to claim 1, wherein control is performed so as to change a frequency of a reference signal generated by the reference signal generation unit based on a comparison result.

(Claim 3)
Imaging means for photoelectrically converting a subject light image to generate an image signal;
Display means having a backlight illumination section for illuminating an image display section for displaying the image signal captured by the imaging means;
Backlight drive current generation means for generating a drive current used in the backlight illumination unit;
Backlight drive current control means for controlling the operation of the backlight drive current generation means;
A battery as a power source for operation;
Detecting means for detecting the temperature of the battery,
The backlight drive current control means is based on the detection result of the detection means,
An image pickup apparatus that controls an operation of the backlight drive current generating means.

(Claim 4)
The backlight drive current control means includes
Comparing a preset reference temperature of the battery and the temperature of the battery detected by the detection means,
The imaging apparatus according to claim 3, wherein control is performed so as to change a drive current generated by the backlight drive current generation unit based on a comparison result.

  According to the first and second aspects of the present invention, the frequency of the reference signal formed by the reference signal generating means can be varied, for example, only under photographing conditions under low temperature where the battery capacity is significantly reduced. . Therefore, the power consumption can be reduced by controlling the frequency of the drive control signal when shooting at low temperatures where the battery is extremely consumed.

  In addition, according to the third and fourth aspects of the present invention, fluctuations such as reducing the drive current formed by the backlight drive current generating means are performed only under photographing conditions under low temperature where the battery capacity is significantly reduced. be able to. As a result, it has become possible to provide an imaging device that realizes more efficient energy saving by reducing the power consumption in the backlight illumination section of the LCD display when shooting at low temperatures.

  The present invention is an invention of an image pickup apparatus having means for preventing the battery from being consumed under shooting conditions in which the battery is extremely consumed, such as shooting at a low temperature. That is, the present invention compares the temperature of the battery provided in the image pickup device with the reference temperature, and when the temperature at the time of shooting is lower than the reference temperature, the pixel transfer clock of the image pickup device is slowed down or the LCD display By reducing the current for backlight illumination, battery consumption is reduced in low-temperature shooting environments.

  As a specific embodiment of the imaging apparatus according to the present invention, a digital camera is typical, but a mobile phone with a camera, a digital video camera, and the like are also included.

  The appearance of a digital camera that is one of the representative embodiments of the imaging apparatus according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1A is a front view of a digital camera 1 according to the present invention, and FIG. 2A is a top view of the digital camera 1, and FIG. 2B is a side view. As shown in the figure, the digital camera 1 includes an imaging unit 2 and a camera body unit 3.

  The imaging unit 2 includes an imaging unit including a macro zoom and an imaging unit including a photoelectric conversion element such as a CCD and a signal processing circuit, and converts an optical image of the subject (subject optical image) into an image signal (photoelectrically converted at each pixel of the CCD). Converted into an image signal composed of the generated charge signal) and then A / D converted and output.

  A macro zoom lens 201 (to be described later) is provided inside the imaging unit 2, and an imaging circuit (not shown) including a CCD area sensor 202 (to be described later) is provided behind the location where the macro zoom lens 201 is provided. It has been.

  In addition, a dimming circuit (not shown) including a dimming sensor that receives reflected light from the subject of flash light is provided inside the image pickup unit 2.

  The camera body unit 3 includes an LCD display unit 6 including an LCD (Liquid Crystal Display), an EVF (Electronic View Finder) 7, and an external connection terminal 12 for connecting the digital camera 1 to a personal computer (not shown). The image signal captured by the imaging unit 2 is subjected to predetermined signal processing, image display on the LCD display unit 6 and EVF 7, image recording on a recording medium such as a memory card 13 described later, or personal Processing such as image transfer to a computer is performed.

  As shown in FIG. 1A, a flash 4 is provided at an appropriate position on the front surface of the camera body 3. As shown in FIG. 1B, an LCD display unit 6 and an EVF 7 for displaying a photographed image and reproducing and displaying a recorded image are provided at a substantially central portion on the back of the camera body unit 3. The LCD display unit 6 includes an image display unit (not shown) that displays an image signal captured by the CCD area sensor 202 and a backlight illumination unit (not shown) that illuminates the image display unit.

  On the upper surface of the camera body 3, as shown in FIG. 2A, a shutter button 5 that captures a captured image and records it on the memory card 13, and a “recording mode” (REC in the figure) near the shutter button 5. ) And “playback mode” (PLAY in the figure) are provided. The recording mode is a mode for taking a picture from the shooting standby state through the exposure control process to the shooting, and the playback mode is a mode for playing back and displaying the shot image recorded on the memory card 13 on the LCD display unit 6 or the EVF 7. It is.

  Further, as shown in FIG. 2A, a photographing sensitivity changeover switch 10 for switching photographing sensitivity is provided on the upper surface of the camera body 3. The shooting sensitivity changeover switch 10 can be switched from ISO 100 to ISO 800, for example, every time the switch is pressed, and the sensitivity suitable for the situation at the time of shooting can be selected.

  As shown in FIG. 1B, a playback frame advance switch / zoom switch 9 is provided on the rear surface of the camera body 3 for performing frame advance of a playback image and zooming operation during shooting. The frame advance of the playback image by the playback frame advance switch / zoom switch 9 is a mode in which the camera is set to the playback mode and the images recorded on the memory card 13 are sequentially displayed on the LCD display unit 6 together with the frame number. . Note that it is possible to instruct to change the image display on the LCD display unit 6 in the ascending order direction (direction of photographing order) or the descending order direction (direction opposite to the photographing order). The zoom operation at the time of shooting is to zoom the macro zoom lens 201 in the tele direction or the wide direction by operating the playback frame advance switch / zoom switch 9.

  Further, an EVF changeover switch 8 for selecting an LCD display unit 6 and an EVF 7 which are display means for displaying an image is provided on the back surface of the camera body unit 3.

  In addition, a battery 316 (not shown) as an operation power source of the digital camera 1 and a battery temperature detection unit 315 (not shown) are provided near the battery 316 inside the bottom surface of the camera body 3. .

  Next, the control system of the digital camera 1 will be described with reference to FIG. FIG. 3 is a block diagram of a control system of the digital camera 1 according to the present invention. In FIG. 3, the same members as those shown in FIGS. 1 and 2 are given the same numbers.

  The macro zoom lens 201 in the imaging unit 2 is provided with a diaphragm member (fixed diaphragm) having a fixed aperture. The CCD area sensor 202 (hereinafter abbreviated as CCD 202) has R (red) light, G (green) light, and B (blue) light transmission filters arranged in a checkered pattern in pixel units (pixel units). The object light image formed by the macro zoom lens 201 by the color area image sensor is received as an image signal (each pixel unit) of each color component of R (red) light, G (green) light, and B (blue) light. The signal is converted into a signal comprising a signal string of the pixel signals thus obtained. That is, the CCD 202 functions as an imaging unit in the imaging apparatus according to the present invention.

  The imaging unit 2 can perform exposure control (adjustment of the exposure amount of the CCD 202) in the shooting standby state. However, in the shooting standby state, the aperture is set to an open fixed aperture by the aperture driver 208, so that exposure is performed by adjusting the charge accumulation time of the CCD 202. Control is performed. That is, the exposure control in the photographing standby state is performed by adjusting the charge accumulation time of the CCD 202 corresponding to the shutter speed.

  The charge accumulation time is adjusted as follows.

  First, exposure control data is calculated by a camera control CPU 311 provided in the camera body 3 based on a photometric area selected from light quantity data measured by the CCD 202. Based on the calculated exposure control data and preset program diagram data, exposure time data is calculated and sent to the timing generator 209. Based on these data, the timing generator 209 feeds back to the CCD 202 information on the charge accumulation time that is an appropriate exposure time, and the charge accumulation time is adjusted.

  Note that when the subject brightness is low, an appropriate shutter speed cannot be set and appropriate exposure control cannot be performed. In such a case, the gain adjustment of the AGC circuit 205 is performed along with the adjustment of the shutter speed. By doing so, it is possible to achieve proper exposure control.

  That is, in the case of low luminance, by combining the gain adjustment of the AGC circuit 205 in the signal processing circuit 203 with the shutter speed adjustment, a synergistic effect by both adjustments can be obtained, and the image signal level can be adjusted. Appropriate exposure control is realized.

  Further, the exposure control at the time of photographing is performed by determining the appropriate exposure amount to the CCD 202 by the aperture driver 208 and the timing generator 209 based on the exposure control data calculated by the camera control CPU 311 and information based on a preset program diagram. Be controlled.

  The timing generator 209 generates a drive control signal for the CCD 202 on the basis of a reference clock transmitted from a reference clock generation unit 308 of the camera main body 3 described later. The drive control signal generated by the timing generator 209 includes, for example, an integration start / end timing signal for controlling the exposure start and end timing in the CCD 202, and a readout control signal (horizontal synchronization signal, vertical synchronization signal) of the light reception signal of each pixel. Clock signal such as a transfer signal). When these clock signals are supplied to the CCD 202, the CCD 202 performs drive control corresponding to each clock signal. In this manner, the timing generator 209 functions as a drive control signal generation unit in the imaging apparatus according to the present invention.

  When the charge accumulation is completed (that is, when the exposure control of the digital camera 1 is completed), the image signal formed by the photoelectric conversion is shifted to the light-shielded transfer path in the CCD 202 and read out through the buffer. The image signal read from the CCD 202 is taken into the signal processing circuit 203 and subjected to predetermined processing.

  As shown in FIG. 3, the signal processing circuit 203 includes a CDS circuit 204 and an AGC circuit 205, and a predetermined process is performed on the image signal via these components. Hereinafter, the predetermined processing for the image signal performed by the signal processing circuit 203 will be described.

  A CDS (Correlated Double Sampling) circuit 204 reduces noise generated at the time of reading from an image signal read from the CCD 202 and corrects dark noise by an OB clamp operation.

  The AGC circuit 205 performs gain adjustment on the image signal processed by the CDS circuit 204 based on the photographing sensitivity selected by the photographing sensitivity changeover switch 10 described above, and controls photographing sensitivity.

  The A / D converter 206 converts each pixel signal constituting the image signal input from the AGC circuit 205 into a 14-bit digital signal. The A / D converter 206 converts each pixel signal of the analog signal into a 14-bit digital signal based on the A / D conversion clock input from the reference clock generation unit 311.

  The image signal read by the CCD 202 is subjected to predetermined processing by the signal processing circuit 203 and the A / D converter 206 and converted into a digital image signal. The digitized image signal is captured by the image processing CPU 301 and subjected to predetermined processing.

  The image processing CPU 301 is composed of a microcomputer and controls the photographing operation of the digital camera 1 by controlling the operation of each member constituting the imaging unit 2 and the camera body unit 3 described above. In the following, processing for a digital image signal performed by the image processing CPU 301 will be described.

  First, the image signal captured by the image processing CPU 301 is written into the image memory 314 in synchronization with the reading of the image signal output from the CCD 202. That is, the digital image signal used for the processing in the image processing CPU 301 is once recorded in the image memory 314, taken out from the image memory 314, and used for processing in each block.

  The image processing CPU 301 performs predetermined processing on the digital image signal extracted from the image memory 314. The image processing CPU 301 performs predetermined processing at a portion from the pixel interpolation unit 302 to the matrix calculation unit 306 shown in FIG.

  The pixel interpolation unit 302 masks image data recorded in the image memory 314 with R, G, and B pixel filter patterns, and then performs average interpolation (also referred to as pixel interpolation). Among these, the G pixel filter pattern having pixels up to a high band is a median filter that performs average interpolation by substituting the average value of the intermediate binary values of the surrounding four pixels, and the R and B pixel filters. The pattern is an average interpolation for the same color from the surrounding nine pixels.

  The resolution conversion unit 303 performs a reduction process and a thinning process in the horizontal direction and the vertical direction on the image signal subjected to the pixel interpolation by the pixel interpolation unit 302, and the recorded image pixel set by the imaging unit 2 of the digital camera 1. The resolution is converted to a resolution corresponding to the number. At the same time, it is also possible to perform a horizontal pixel thinning process on the monitor display image signal and convert it to a low resolution image signal that can be displayed on the LCD display unit 6 or the EVF 7.

  A white balance control unit (WB control unit) 304 performs level conversion on the image signals of the R, G, and B color components subjected to resolution conversion processing by the resolution conversion unit 303. This is called processing. In the white balance processing, for example, image data relating to a colorimetric area on the imaging surface that is set in advance is read from data written in the image memory 314 during shooting standby, and the luminance and saturation of the read image data are read out. From the above data, etc., the part originally supposed to be white is estimated, the average intensity of each part, the G / R ratio, and the G / B ratio are obtained and corrected as R and B correction gains. Control is performed.

  The gamma correction unit 305 corrects the γ characteristic of the image signal and converts the image signal into a signal suitable for the characteristics of the output device. As a specific processing method, for example, a non-linear conversion process is performed and 8-bit data is converted. The method of converting into the image signal of this is mentioned.

  The matrix calculation unit 306 converts the image signals R, G, and B subjected to the gamma correction processing into a luminance signal (Y signal) and a color difference signal (Cr (R−Y) signal, Cb (B−Y) signal). .

  Then, the digital image signal that has undergone predetermined processing at these parts is stored in the image memory 316 again.

  The reference clock generation unit 308 is a circuit that generates a reference clock used for driving control of the digital camera 1 and supplies the reference clock to each circuit. Specific examples of the reference clock in the present invention include a reference clock used for the timing generator 209, an A / D conversion clock used for the A / D converter 206, and the like. Generated by the unit 308. Thus, the reference clock generation unit 308 functions as a reference signal generation unit in the imaging apparatus according to the present invention. Further, the frequency of the reference clock generated by the reference clock generation unit 308 is controlled so as to be changed by a camera control CPU 311 described later.

  The LCD driver 309 encodes the image signal read from the image memory 314 by the image processing CPU 301 into NTSC / PAL, and displays the image on the LCD display unit 6 and the EVF 7 as a field image. The LCD driver 309 generates an illumination driving current used in the backlight illumination unit of the LCD display unit 6, and the illumination driving current generated by the LCD driver 309 is controlled by a camera control CPU 311 described later. In this way, the LCD driver 309 functions as a backlight drive current generating unit in the imaging apparatus according to the present invention.

  Further, the battery temperature conversion circuit 312 converts the temperature of the place where the battery is detected, which is detected by the battery temperature detection unit 315 provided in the vicinity of the battery 316, into an electrical signal, and sends it to the camera control CPU 311 as temperature information. Is. As described above, the battery temperature detection unit 315 functions as a detection unit in the imaging apparatus according to the present invention, and the battery temperature conversion circuit 312 functions as a temperature conversion unit in the imaging apparatus according to the present invention.

  The camera control CPU 311 is composed of a microcomputer, and based on switch signals generated by switch operations of a switch group 317 described later, the driving of each member of the imaging unit 2 and the camera body unit 3 is sequentially controlled to perform the shooting operation of the digital camera 1. Oversee and control.

  Further, the camera control CPU 311 compares the battery temperature information sent from the battery temperature conversion circuit 312 with a preset reference temperature value (threshold value), and a reference generated by the reference clock generation unit 308 based on the comparison result. Control the frequency of the clock. As described above, the camera control CPU 311 functions as a reference signal control unit in the imaging apparatus according to the present invention.

  Further, the camera control CPU 311 compares the battery temperature information sent from the battery temperature conversion circuit 312 with a preset reference temperature value (threshold value), and the LCD display generated by the LCD driver 309 based on the comparison result. The drive current for illumination used in the backlight illumination unit of the unit 6 is controlled. As described above, the camera control CPU 311 functions as a backlight drive current control unit in the imaging apparatus according to the present invention.

  The image processing CPU 301 includes an image compression unit 307 that compresses a captured image. The image compression unit 307 performs image compression processing such as a JPEG (Joint Photographic Coding Experts Group) method on the captured image, and performs predetermined processing. The image data compressed to the compression ratio is generated. The compressed image data is recorded on the memory card 13 via the memory card driver 310.

  As described above, in the digital camera 1, the image processing CPU 301 performs the signal processing as described above on the image signal captured from the imaging unit 2, and records the image signal subjected to these processing in the image memory 314. ing.

  The digital camera 1 according to the present invention records the image signal captured by the imaging unit 2 in the image memory 314 or displays it on the LCD display unit 6 or the EVF 7 under the mode set by the shooting mode switch 11.

  In a photographing standby state (a state in which the recording mode (REC) is set with the photographing mode switch 11), image signals are taken into the camera body 3 from the imaging unit 2 at a predetermined interval such as every 1/30 seconds. As described above, the captured image signal is subjected to predetermined signal processing at a portion from the pixel interpolation unit 302 to the matrix calculation unit 306 in the image processing CPU 301, and then recorded in the image memory 314 as a digital image signal. The

  Then, the image signal recorded in the image memory 314 is read out, the read image signal is encoded into NTSC / PAL by the LCD driver 309, and this is displayed as an image on the LCD display unit 6 or the EVF 7 as a field image.

  Further, at the time of image recording, the image signal is compressed by the image compression unit 307 in order to obtain an image of the set recording resolution as described above, and the obtained compressed image is stored in the memory card via the memory card driver 310. 13 is recorded.

  In the reproduction mode (the state in which the reproduction mode (PLAY) is set by the photographing mode switch 11), the image signal read from the memory card 13 is a part from the pixel interpolation unit 302 to the matrix calculation unit 306 in the image processing CPU 301. Then, predetermined signal processing is performed and the image is displayed on the LCD display unit 6 and the EVF 7 via the LCD driver 309. The LCD display unit 6 functions as display means in the imaging apparatus according to the present invention.

  A switch group 317 in FIG. 3 corresponds to the shutter button 5, EVF change switch 8, playback frame advance switch / zoom switch 9, shooting sensitivity change switch 10, and shooting mode change switch 11 in FIGS. 1 and 2. Switch.

  Here, the energy saving method performed by the digital camera 1 according to the present invention will be described in detail. In the present invention, when shooting is performed in a low temperature environment in which the capacity of the battery is significantly reduced, the operation of reducing the pixel transfer clock of the image sensor or the operation of reducing the backlight illumination current of the LCD display is performed. Prevent capacity loss. Hereinafter, each of these operations will be described.

  First, the operation of reducing the pixel transfer clock of the image sensor at the time of shooting in a low temperature environment will be described with reference to the flowchart of FIG.

  First, the digital camera 1 is set to a recording mode to enter a shooting standby state, and a shooting standby image is displayed on the LCD display unit 6 of the digital camera 1 (step S1). In this state, the battery temperature detection unit 315 detects the temperature of the location where the battery 316 is installed (this is called the battery temperature) (step S2), and the battery temperature conversion circuit 312 is detected by the battery temperature detection unit 315. The battery temperature is converted into an electrical signal (step S3), and the converted electrical signal is sent to the camera control CPU 311 as temperature information (step S4).

  In the camera control CPU 311, the temperature at which the pixel transfer clock is slowed down is set in advance as a threshold value, and this is set as the reference temperature value (for example, in the present invention, 0 ° C. is set as the reference temperature value). This threshold value is compared with the temperature information sent from the battery temperature detection circuit 312 (step S5), and it is determined whether or not the measured battery temperature is lower than the threshold value (step S6).

  If it is determined that the temperature of the battery is lower than the threshold (step S6; Yes), the camera control CPU 311 assumes that there is a possibility that the battery capacity may be significantly reduced by shooting in a low temperature environment, and the camera control CPU 311 performs the reference clock generation unit 308. Is controlled so as to reduce the frequency of the reference clock generated in step S7.

  Then, a reference clock whose frequency is reduced is transmitted from the reference clock generator 308 to the timing generator 209 (step S8), and the timing generator 209 generates a drive control signal for the CCD 202 based on this reference clock (step S9). . In this way, the pixel transfer clock of the CCD 202 is slowed down, and the power consumption in the CCD 202 is reduced.

  On the other hand, when it is determined that the battery temperature is higher than the threshold value (step S6; No), it is determined that the battery capacity reduction due to the low temperature environment has little influence, and the camera control CPU 311 uses the reference clock generator 308 to perform a normal reference clock. (Step S10).

  Then, the reference clock generator 308 transmits a normal speed reference clock to the timing generator 308 (step S11), and the timing generator 209 generates a drive control signal for the CCD 202 based on the reference clock (step S12).

  Next, the operation of reducing the current for backlight illumination of the LCD display 6 at the time of photographing in a low temperature environment will be described with reference to the flowchart of FIG.

  First, since the flow from step S1 to step S5 in FIG. 5 is the same as the above-described reduction in the pixel transfer clock speed, description thereof is omitted.

  If the battery temperature is lower than the threshold value in step S6 (step S6; Yes), it is assumed that the battery capacity may be significantly reduced by shooting in a low temperature environment, and the camera control CPU 311 uses the LCD driver 309. Control is performed so that the drive current for backlight illumination of the LCD display unit 6 to be generated becomes smaller than a predetermined value (step S7). In this way, the drive current for the backlight illumination is reduced, and the power consumption of the backlight illumination is reduced.

  On the other hand, when the temperature of the battery is higher than the threshold value (step S4; No), it is determined that the influence of the battery capacity reduction is not so great due to the influence of the temperature, and the camera control CPU 311 generates a predetermined drive current. The LCD driver 309 is controlled (step S8).

  In the flowcharts of FIG. 4 and FIG. 5, it has been explained that the battery temperature is controlled based on the comparison result with one threshold temperature. In the present invention, a plurality of threshold values are set and the battery temperature is set. Accordingly, the control may be performed step by step. By controlling in stages, it is possible to provide more efficient energy saving and better imaging environment.

  As described above, in the imaging apparatus according to the present invention, the pixel transfer clock of the imaging device is slowed down and the backlight illumination current of the LCD display is reduced only under low-temperature shooting conditions in which the battery capacity is significantly reduced. As a result, power consumption at low temperatures can be greatly reduced, and efficient energy-saving measures can be implemented.

  That is, in the present invention, it is determined whether or not the imaging apparatus is under a condition where the battery capacity is significantly reduced, such as in a cold imaging environment, and it is determined that the imaging apparatus is under an imaging condition where the battery capacity may be significantly reduced. When this happens, the pixel transfer clock speed of the image sensor and the current for backlight illumination of the LCD display are reduced so that stable shooting can be performed without causing a decrease in battery capacity. In addition, when it is determined that there is a shooting condition in which the battery capacity is not so low, pixel transfer and backlight illumination can be performed under normal setting conditions.

  According to the present invention, in particular, there is a concern that high-capacity image pickup devices can be driven at high speeds, and that sudden battery capacity reduction may occur in a low-temperature environment that includes a large LCD display device with backlight illumination. Appropriately adapted to the shooting environment for the easy-to-spec imaging device, it is now possible to reliably perform stable shooting.

It is the front view and back view of the digital camera which concern on this invention. It is the top view and side view of the digital camera which concern on this invention. It is a block block diagram in the digital camera which concerns on this invention. It is a flowchart which shows the flow of CCD drive signal frequency control. It is a flowchart which shows the flow of LCD display part backlight electric current control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 2 Imaging part 201 Macro zoom lens 202 CCD area sensor 203 Signal processing circuit 204 CDS circuit 205 AGC circuit 206 A / D converter 207 Focus motor driver 208 Aperture driver 209 Timing generator 3 Camera main body 301 Image processing CPU
302 Pixel Interpolation Unit 303 Resolution Conversion Unit 304 White Balance Control Unit 305 Gamma Correction Unit 306 Matrix Operation Unit 307 Image Compression Unit 308 Reference Clock Generation Unit 309 LCD Driver 310 Memory Card Driver 311 Camera Control CPU
312 Battery temperature detection circuit 313 DC / DC converter 314 Image memory 315 Battery temperature detection unit 316 Battery 317 Switch group 4 Flash 5 Shutter button 6 LCD display unit 7 EVF
8 EVF selector switch 9 Playback frame advance switch / zoom switch 10 Shooting sensitivity selector switch 11 Shooting mode selector switch 12 External connection terminal 13 Memory card

Claims (4)

Imaging means for photoelectrically converting a subject light image to generate an image signal;
Drive control signal generating means for generating a control signal for controlling driving of the imaging means;
Reference signal generating means for generating a reference signal used in the drive control signal generating means;
Reference signal control means for controlling the operation of the reference signal generation means;
A battery as a power source for operation;
Detecting means for detecting the temperature of the battery, the reference signal control means based on the detection result of the detecting means,
An image pickup apparatus that controls an operation of the reference signal generating means. The reference signal control means includes
Comparing a preset reference temperature of the battery and the temperature of the battery detected by the detection means,
The imaging apparatus according to claim 1, wherein control is performed so as to change a frequency of a reference signal generated by the reference signal generation unit based on a comparison result. Imaging means for photoelectrically converting a subject light image to generate an image signal;
Display means having a backlight illumination section for illuminating an image display section for displaying the image signal captured by the imaging means;
Backlight drive current generation means for generating a drive current used in the backlight illumination unit;
Backlight drive current control means for controlling the operation of the backlight drive current generation means;
A battery as a power source for operation;
Detecting means for detecting the temperature of the battery,
The backlight drive current control means is based on the detection result of the detection means,
An image pickup apparatus that controls an operation of the backlight drive current generating means. The backlight drive current control means includes
Comparing a preset reference temperature of the battery and the temperature of the battery detected by the detection means,
The imaging apparatus according to claim 3, wherein control is performed so as to change a drive current generated by the backlight drive current generation unit based on a comparison result.

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