JP3986914B2 - Digital camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital camera, and more particularly to imaging by proper exposure when zooming is performed.
[0002]
[Prior art]
Digital cameras having a strobe light control function are used as disclosed in, for example, Japanese Patent Laid-Open Nos. 10-301172 and 2000-314911. When using this digital camera to zoom and stroboscope, the photometric angle of the imaging system that determines the amount of light to be captured changes following the angle of view that changes with zoom, whereas the photoelectric conversion element of the stroboscopic light control section The photometric angle is always constant without following the angle of view that changes with zoom.
[0003]
[Problems to be solved by the invention]
As described above, the metering angle of the flash metering unit is always constant, but the metering angle of the imaging system changes with zooming. There is a difference between the angle and the photometric angle of the imaging system, and the difference in the photometric amount is caused by the difference between the photometric angles, making it difficult to capture images with appropriate exposure.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a digital camera that can improve such disadvantages and can always take an image with proper exposure when performing strobe photography with zooming.
[0005]
[Means for Solving the Problems]
The digital camera of the present invention includes strobe photometry means for measuring light of a strobe, imaging system photometry means for performing photometry of an imaging system, and photometry angle control means for controlling a photometry angle of the imaging system photometry means, The angle control means is characterized in that when taking a stroboscopic image by zooming, the photometry angle of the imaging system photometry means is controlled to be the telephoto angle of the photometry in both the wide and telephoto systems .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an external view of a digital camera. As shown in FIG. 1A, the surface on the imaging side of the digital camera 1 has a lens 2, an optical finder 3 and a strobe 4, and a shutter button 5 on the upper surface. As shown in FIG. 1B, the back surface of the digital camera 1 has a plurality of setting buttons 6 for setting an imaging mode and a display unit 7 including a liquid crystal display, and a storage unit for the memory card 8 on the side surface. Have
[0009]
As shown in the block diagram of FIG. 2, the digital camera 1 includes a lens group 11, a diaphragm 12 that adjusts the amount of light incident from the lens group 11, a CCD 13 that converts incident light into an electrical signal, and an output of the CCD 13. A CDS / A / D converter 14 that removes noise components included in the signal, amplifies the signal component, and converts the amplified analog signal into a digital signal, and pixel interpolation, gain correction for each color, γ correction, and aperture A signal processing unit 15 that performs various processes such as correction, a frame memory 16 that temporarily stores image data processed by the signal processing unit 15, a DCT / coder 17 that compresses and expands image data, and an SRAM that stores image data D / A conversion that converts image data, which is a digital signal, into an analog signal and outputs it as a video signal 19, a lens driving unit 20 that changes the focus position of an image formed on the CCD 3 by moving a lens group with a motor or a solenoid, a diaphragm driving unit 21 that changes the aperture of the aperture 12 with a solenoid or the like, and the CCD 13 And a timing generator 22 that generates drive pulses for the CDS / A / D converter 14, an automatic exposure controller 23 that controls the amount of incident light on the CCD 3 from the output of the signal processor 15, and an image from the output of the signal processor 15. An automatic focus detection unit 24 that detects the focus position of the image, a white balance control unit 25 that controls the white balance of the image to be captured from the output of the signal processing unit 15, a CPU 26 that controls the operation of the entire apparatus, and the amount of light at the time of imaging A light amount input unit 27 for detecting and inputting the light.
[0010]
As shown in the block diagram of FIG. 3, the light quantity input unit 27 includes strobe photometry means 28, imaging system photometry means 29, and photometry angle control means 30. The strobe photometry means 28 measures the strobe 4. The imaging system photometry unit 29 performs photometry to determine the amount of light to be imaged by the imaging system. The photometry angle control means 30 controls the photometry angle by the photometry angle of the strobe photometry means 28 by the imaging system photometry means 29 when photographing by zooming.
[0011]
An operation of recording an image of the digital still camera configured as described above will be described.
[0012]
When the power button of the digital camera 1 is turned on to enter the image recording mode and then the shutter button is pressed halfway, the light of the image incident on the lens group 11 is adjusted by the aperture 12 and formed on the CCD 13. The image formed on the CCD 13 is converted into an electrical signal in accordance with the amount of light for each pixel, and sequentially sent to the CDS / A / D converter 14 at regular intervals. The CDS / A / D converter 14 removes and amplifies the noise component of the sent signal, converts it into image data of a digital signal, and sends it to the signal processor 15. The image data sent to the signal processing unit 15 is once stored in the frame memory 16. The frame memory 16 has a capacity capable of storing the image of the CCD 13 for two screens or more, stores the image data sent from the signal processing unit 15, and outputs the previously stored image data to the signal processing unit 15. An area for storing image data and an area for outputting in the frame memory 16 are switched for each screen of the image sent from the signal processing unit 15. The image data of the previous screen output from the frame memory 16 is a color formed on the light receiving element of the CCD 13 such as red R, green G, blue B or yellow Y, cyan C, magenta M, green G for each pixel. Has filter color data. The signal processing unit 15 interpolates the transmitted image data and performs conversion to R, G, B when the color filter of the CCD 13 is other than R, G, B. For each pixel, the R, G, B colors are converted. Have a signal. Then, image processing such as gain correction, γ correction, and aperture correction for each color is performed, and further converted into a luminance signal and a color difference signal, and the converted image data is sent to the display unit 7 to display a monitor image. The monitor image displayed on the display unit 7 is updated at regular intervals. In addition to the output to the display unit 7, the signal processing unit 15 outputs R, G, and B color signals for each pixel to the white balance control unit 25, and R to the automatic exposure control unit 23 and the automatic focus detection unit 24. , G, and B are used to create a luminance signal and output it.
[0013]
The light quantity input unit 27 detects the amount of received light within a preset range in the input image data and sends it to the signal processing unit 15. The automatic exposure control unit 23 calculates the exposure amount of the CCD 13 from the received light amount sent from the signal processing unit 15, and sends the calculated exposure amount calculation value to the CPU 26. The CPU 26 changes the gain of the amplifier of the CDS / A / D conversion unit 14 so that the exposure amount of the CCD 13 is appropriate based on the sent exposure amount calculation value, and operates the aperture drive unit 21 to adjust the aperture 12. The electronic shutter speed of the CCD 13 is changed via the timing generator 22. When the image data obtained by converting the R, G, and B color signals for each pixel into luminance signals is input from the signal processing unit 15 to the automatic focus detection unit 24, the automatic focus detection unit 24 converts the input image data into image data for a preset range. The amount of the high frequency component contained is calculated. This operation is performed for a plurality of positions while moving the lens group 11 by the lens driving unit 20 and changing the focus position of the image formed on the CCD 13 from the infinity toward the close distance or from the close distance to the infinity. Then, the position where the calculation result is maximized is output to the CPU 26 as the focus position of the image formed on the CCD 13. The CPU 26 moves the position of the lens group 11 by operating the lens driving unit 20 so that the input focus position is obtained. When the R, G, B color image data for each pixel is input from the signal processing unit 15 to the white balance control unit 25, the white balance control unit 25 inputs from the R, G, B color distribution for a preset range in the input image data. The image color deviation is calculated and output to the CPU 26. The CPU 26 changes the gain correction gain for each color of the image processing unit 15 so as to eliminate the color deviation from the calculation result of the color deviation sent.
[0014]
Thus, after the imaging conditions are determined by the automatic exposure control unit 23, the automatic focus detection unit 24, and the white balance control unit 25, the photographer is notified by turning on the LED or the like. In this state, the photographer further presses the shutter button to capture an image, and the image data processed by the signal processing unit 15 is compressed by the DCT / coder 17 and stored in the memory 18. When displaying the image data stored in the memory 18 on the display unit 7, the data compressed by the DCT / coder 17 is expanded, and if necessary, the signal processing unit 15 adds characters, numbers, and pictograms of imaging information to the image. Is displayed on the display unit 7. The image data stored in the memory 18 is converted to analog data by the D / A converter 19 and output to the outside as a video output.
[0015]
As shown in FIG. 4, when the digital camera 1 captures an image, the photometry angle for detecting the amount of light received by the imaging system photometry means 29 of the light quantity input unit 27 is a wide photometry angle α and a telephoto system photometry angle β. To change. Therefore, the imaging system photometry means 29 is composed of a plurality of photoelectric conversion elements, and has a telephoto photometry range 31 and a wide photometry range 32 as shown in FIG. The photometric range can be arbitrarily changed by a signal. Here, FIG. 5A shows a case where the telephoto metering range 31 and the wide photometry range 32 are provided concentrically, and FIG. 5B shows that the telephoto metering range 31 and the wide photometry range 32 are provided separately. Show the case. Further, the photometric angle θ of the strobe photometry means 28 is constant without being changed by the zoom. As shown in FIG. 4A, when the strobe photometry means 28 is fixed at the wide photometry angle α of the imaging system photometry means 29, when taking a stroboscopic image by zooming, the photometry angle The control means 30 performs control so that the photometry angle of the imaging system photometry means 29 becomes the telemetry photometry angle β regardless of whether the zoom is wide or telephoto. In addition, when the stroboscopic photometry means 28 is fixed at the telephoto metric angle β of the imaging system photometry means 29 as shown in FIG. The control means 30 performs control so that the photometry angle of the imaging system photometry means 29 becomes the telemetry photometry angle β regardless of whether the zoom is wide or telephoto.
[0016]
In this way, when taking a stroboscopic image with zooming, it is possible to take an image with proper exposure by variably controlling the photometric angle of the imaging system photometric means 29.
[0017]
In the above description, the case where control is performed so that the photometry angle of the imaging system photometry unit 29 becomes the telephoto metering angle β when taking a stroboscopic image by zooming has been described. However, the photometry angle of the imaging system photometry unit 29 and the flash photometry unit 28 are controlled. Alternatively, the photometric angle of the imaging system photometric means 29 may be variably controlled so that the photometric angles are equal.
[0018]
Further, the photometric range of the imaging system photometric means 29 when taking a stroboscopic image by zooming can be expressed as the area of the photoelectric conversion element. Therefore, for example, the photometry angle θ of the flash metering means 28 is fixed at the telephoto metering angle β of the imaging system photometry means 29, and when taking a stroboscopic image by zooming, the photometry angle of the imaging system photometry means 29 is not changed and the imaging system photometry is not changed. The photometric signal detected by the means 29 is corrected by the photometric angle control means 30 for the wide and telephoto photometric areas, and the photometric angle θ of the strobe photometric means 28 is fixed at the wide photometric angle α of the imaging system photometric means 29. In this case, the photometry signal detected by the flash photometry means 28 may be corrected by the photometry angle control means 30 by the photometry area of the wide and telephoto system and output to the signal processing unit 27.
[0019]
【The invention's effect】
As described above, the present invention performs zooming by controlling so that the photometry angle of the imaging system photometry means becomes the telephoto system photometry angle in both the wide and telephoto systems when performing zoom and strobe photography. Therefore, when shooting with a stroboscope, images can always be taken with appropriate exposure, and high-quality images can be taken stably.
[Brief description of the drawings]
FIG. 1 is an external view of a digital camera.
FIG. 2 is a block diagram illustrating a configuration of a digital camera.
FIG. 3 is a block diagram illustrating a configuration of a light amount input unit.
FIG. 4 is an explanatory diagram showing a photometric angle of an imaging system photometric unit and a photometric angle of a strobe photometric unit.
FIG. 5 is a perspective view showing a photometric area of an imaging system photometric unit.
[Explanation of symbols]
1; digital camera, 2; lens, 3; optical viewfinder, 4; strobe,
5; shutter button, 6; setting button, 7; display section, 8; memory card,
11: Lens group, 12: Aperture, 13: CCD,
14; CDS / A / D converter, 15; signal processor, 16; frame memory,
17; DCT / coder, 18; memory, 19; D / A converter,
20; Lens drive unit, 21; Aperture drive unit, 22; Timing generator,
23; automatic exposure control unit, 24; automatic focus detection unit, 25; white balance control unit,
26; CPU, 27; light quantity input unit, 28; strobe photometry means,
29; Imaging system photometry means; 30; Photometry angle control means.

Claims (1)

  A flash metering unit that performs flash metering; an imaging system metering unit that performs metering of the imaging system; and a metering angle control unit that controls a metering angle of the imaging system metering unit, the metering angle control unit performing zooming A digital camera characterized by controlling the photometry angle of the imaging system photometry means to be a telephoto system photometry angle in both wide and telephoto systems.

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