JP4026890B2 - Electronic camera and electronic shutter control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic camera capable of moving image shooting and still image shooting and an electronic shutter control method thereof.
[0002]
[Prior art]
Conventionally, in an electronic camera such as a video camera that shoots moving images and still images, 1/60 seconds are synchronized with a vertical blanking period (60 Hz: V cycle) of a normal TV (television) signal during moving image shooting. Controlled by electronic shutter speed (speed).
[0003]
Further, in an area where the commercial AC power frequency is 50 Hz, a periodic luminance change (flicker component) occurs at the time of shooting at an electronic shutter speed of 1/60 seconds. Therefore, flicker detection means is provided to detect flicker. Sometimes the electronic shutter speed is controlled to switch to 1/100 second.
[0004]
The 50 Hz flicker detection at the actual electronic shutter speed of 1/60 seconds is performed by software, which is performed as follows (see the flowchart of FIG. 3).
[0005]
That is, the flicker detection has a data buffer for storing 11 cycles of luminance component integral data (referred to as Ys data) updated in the above-described V cycle, and the data is applied to a 20 Hz band-pass filter. Then, the past three periods of the Ys data subjected to the band pass filter are held, and when the difference between the maximum value and the minimum value of the three data exceeds the flicker detection threshold level, “the flicker component is present”. Deciding.
[0006]
[Problems to be solved by the invention]
However, in the conventional electronic camera as described above, camera shake occurs when shooting at a shutter speed of 1/60 seconds as in the case of moving image shooting during still image shooting. However, there is a problem that a clear image cannot be obtained.
[0007]
In this case, it is possible to prevent camera shake by switching to a shutter speed of 1/100 seconds under normal circumstances, but in this case, lighting flicker under a fluorescent lamp in a room is eliminated in an area where the AC power frequency is 50 Hz. Conversely, a flicker component occurs in the 60 Hz region.
[0008]
In order to cope with this, in addition to the 50 Hz flicker detection means at a shutter speed of 1/60 seconds, a 60 Hz flicker detection means at a shutter speed of 1/100 seconds must be provided. There was a problem that the scale of the.
[0009]
The present invention has been made by paying attention to the above-described problems, and can prevent camera shake during still image shooting, and at the same time prevent camera shake and avoid the influence of flicker with a simple configuration. It is an object to provide a camera and an electronic shutter control method thereof.
[0010]
[Means for Solving the Problems]
The electronic camera and its electronic shutter control method according to the present invention are configured as follows.
[0011]
(1) An electronic camera that can shoot moving images and still images, and is shared between an electronic shutter speed of 1/60 seconds and a faster speed of 1/120 seconds. Detecting means for performing flicker detection by the camera, and when switching to still image shooting at the time of moving image shooting, 1/120 that is faster than the electronic shutter speed of 1/60 second synchronized with the vertical blanking period at the time of moving image shooting Control means for switching to an electronic shutter speed of 1/100 seconds when flicker is detected at the electronic shutter speed of 1/120 seconds is switched to the electronic shutter speed of seconds.
(2) Commonly used when the electronic shutter speed is 1/60 seconds and faster than 1/120 seconds, and has a detecting means for detecting flicker by the AC power supply frequency of the illuminating lamp. In the electronic shutter control method of an electronic camera capable of image shooting, when switching to still image shooting at the time of moving image shooting, the electronic shutter speed of 1/60 seconds synchronized with the vertical blanking period at the time of moving image shooting The electronic shutter speed is switched to a high speed of 1/120 seconds, and when flicker is detected at the electronic shutter speed of 1/120 seconds, the electronic shutter speed is switched to 1/100 seconds.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a block diagram showing a basic configuration of an electronic camera according to the present invention.
[0022]
In FIG. 1, the light incident from the lens 1 is imaged on a CCD 3 that is an image pickup device after the amount of light is limited by a diaphragm 2, and is photoelectrically converted by the CCD 3 and accumulated as a video signal. At this time, the time (electronic shutter speed) accumulated in the CCD 3 is determined by the pulse output from the timing signal generator 8 based on the time data transmitted from the camera control unit 7.
[0023]
The video signal accumulated and output by the CCD 3 is amplified by the AGC circuit 4, converted from an analog signal to a digital signal by the A / D converter 5, and then subjected to signal processing by the camera signal processing unit 6. Output as a signal.
[0024]
The camera signal processing unit 6 has an integration circuit for integrating the luminance component (Y signal) of the video signal. The camera control unit 7 opens the aperture 2 based on the level of the integrated luminance component. The exposure control is performed by controlling the shutter speed of the CCD 3 and the gain of the AGC circuit 4.
[0025]
Also, switching between the moving image and still image recording modes is set by a moving image / still image shooting switching SW (switch) 9. In the case of moving image shooting, the shutter speed is basically controlled to operate at 1/60 seconds, and in the case of still image shooting, the shutter speed is 1/100 seconds.
[0026]
Next, the operation of this embodiment will be described with reference to the flowchart of FIG. This operation is processed by a CPU (not shown) in accordance with a program stored in the camera control unit 7.
[0027]
First, the moving image / still image shooting switch SW9 is checked to determine the shooting mode (step 101), and if SW9 is moving image shooting, it is checked whether the shutter speed is operating at 1/60 seconds ( Step 102), if the shutter speed is already 1/60 seconds, it is left as it is. If the shutter speed is not 1/60 seconds, the shutter speed is changed to 1/60 seconds (Step 103).
[0028]
If the moving image / still image shooting switch SW9 is still image shooting, it is checked whether or not the shutter speed is 1/100 second (step 104). If the shutter speed is not 1/100 second, the setting is changed to 1/100 second (step 105).
[0029]
In this way, the control means (camera control unit 7) for switching the shutter speed is provided, and the shutter speed is automatically set to a speed (in this case, 1/100 seconds) faster than 1/60 seconds during moving image shooting during still image shooting. By switching, camera shake during still image shooting can be prevented, and a clear and good image can be obtained.
[0030]
(Second embodiment)
Since the basic configuration of the electronic camera in this embodiment is the same as that shown in FIG. 1, repeated description is omitted. In this embodiment, the shutter speed is 1/60 seconds and the higher speed is 1/120 seconds. The common flicker detection means (camera signal processing unit 6) is provided to detect flicker by the AC power supply frequency of the fluorescent lamp as the illumination lamp, and to switch the shutter speed according to the detection result.
[0031]
FIG. 4 is a flowchart showing the operation of the present embodiment. This operation is processed by the CPU in the camera control unit 7 as in the above-described embodiment.
[0032]
First, the moving image / still image shooting switch SW9 in FIG. 1 is checked to determine the shooting mode (step 201). If SW9 is moving image shooting, the previous shooting mode is determined (step 202). If the previous mode is still image shooting, the shutter speed is set to 1/60 seconds (step 203), and flicker detection processing is started (step 205).
[0033]
If the previous mode is movie shooting in step 202, there is no need to change the shutter speed, so the shutter speed is not changed as it is, and it is checked whether the flicker component has already been detected (step 204). If not detected, flicker detection processing is performed (step 205).
[0034]
If SW9 is still image shooting by checking the moving image / still image shooting switching SW9 in step 201, the previous mode is determined (step 208), and if moving image shooting, the shutter speed is set to 1/120 second. (Step 209), flicker detection processing is started (Step 205).
[0035]
If the previous mode is still image shooting in step 208, there is no need to change the shutter speed, so the shutter speed is not changed as it is, and it is checked whether the flicker component has already been detected (step 210). If not, flicker detection processing is performed (step 205).
[0036]
In step 205, flicker detection is started. When a flicker component is detected (step 206), the shutter speed is set to 1/100 second (step 207).
[0037]
As described above, when the still image is shot, the shutter speed is increased from 1/60 seconds during moving image shooting to prevent camera shake of the shot image, and at the same time, only one type of flicker detection means can be used at the high shutter speed. Therefore, first, the shutter speed control for 1/120 second is performed, the 50 Hz flicker detection means at the shutter speed of 1/60 second is shared, the 50 Hz flicker detection at 1/120 second is performed, and the flicker component is By performing control to switch the shutter speed from 1/120 seconds to 1/100 seconds when it is detected, it is possible to obtain an appropriate image by camera shake prevention and flickerless still image shooting.
[0038]
Next, the operation of the flicker detection process will be described with reference to the flowchart of FIG.
[0039]
This detection process is performed using a 20 Hz band-pass filter, and the detection process itself is a case of 50 Hz fluorescent lamp flicker detection when the shutter speed is 1/60 sec. By setting the shutter speed to 1/120 seconds instead of 1/100 seconds, the appearance of 60Hz fluorescent light flicker is also eliminated, and the shutter speed is 1/2 cycle of 1/60 seconds. Detection is possible with a 20 Hz bandpass filter.
[0040]
Therefore, it is not necessary to newly prepare a dedicated flicker detection processing means when the shutter speed is 1/120 seconds, and the same processing means can be shared. Thereby, when a 50 Hz fluorescent lamp flicker component is detected (step 206 in FIG. 4), the 50 Hz fluorescent lamp flicker can be eliminated by setting the shutter speed to 1/100 second.
[0041]
First, the aforementioned luminance component integration data (buf [i] = buf [i−1] (i = 10 to 1)) is shifted to the buffer (step 11), and the new luminance component integration data (buf [0]). ] ← New Data) is stored (step 12). Then, the integral data of the luminance components of each of the 11 buffers is multiplied by a filter coefficient (step 13), and the filter output data (F [i] ← F [i-1] (i = 2 to 1)) is buffered. (Step 14) and new filter output data F [0] (F [0] = (buf [10] + buf [0]) − (buf [9] + buf [1]) + (buf [8] + buf [2]) − (buf [7] + buf [3]) + (buf [6] + buf [4]) + buf [5]) is calculated (step 15).
[0042]
Next, the maximum data (MAX) and the minimum data (MIN) are extracted from the past two filter output data (F [1], F [2]) and the current filter output data (F [0]) (steps). 16) It is determined whether or not the difference is larger than the threshold level (MAX-MIN> threshold) (step 17). If the difference is large, the flicker component is detected as described above (step 18), and flicker correction is started (step 19).
[0043]
【The invention's effect】
As described above, according to the present invention, there is an effect that camera shake during still image shooting can be prevented.
[0044]
In addition, the effect of flicker can be avoided with a simple configuration as in the case of camera shake prevention.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the basic configuration of an electronic camera according to the present invention. FIG. 2 is a flowchart showing the operation in the first embodiment. FIG. 3 is a flowchart showing the operation of flicker detection processing. Flow chart showing operation in the embodiment [Explanation of symbols]
1 Lens 2 Aperture 3 CCD
4 AGC circuit 5 A / D converter 6 Camera signal processing section (detection means)
7 Camera control unit (control means)
8 CCD timing signal generator (timing generator)
9 Video / still image shooting switch

Claims (2)

An electronic camera that can shoot movies and still images,
A detection means that is shared between the electronic shutter speed of 1/60 seconds and a faster speed of 1/120 seconds, and performs flicker detection by the AC power supply frequency of the illumination lamp;
When switching to still image shooting at the time of moving image shooting, the electronic shutter speed is switched from 1/160 second electronic shutter speed synchronized with the vertical blanking period at the time of moving image shooting to 1/120 second electronic shutter speed, An electronic camera comprising control means for switching to an electronic shutter speed of 1/100 seconds when flicker is detected at the electronic shutter speed of 1/120 seconds. The electronic shutter speed is shared between 1/60 seconds and faster than 1/120 seconds, and has a detecting means for detecting flicker by the AC power supply frequency of the illumination lamp. In an electronic shutter control method of a possible electronic camera,
When switching to still image shooting at the time of moving image shooting, the electronic shutter speed is switched from 1/160 second electronic shutter speed synchronized with the vertical blanking period at the time of moving image shooting to 1/120 second electronic shutter speed, An electronic shutter control method for an electronic camera, wherein flicker is detected at the electronic shutter speed of 1/120 seconds, and the electronic shutter speed is switched to 1/100 seconds.

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