JPH06125495A - Video camera equipment - Google Patents

Abstract

PURPOSE:To provide a video camera equipment in which fluorescent light flicker is surely detected and corrected without an external sensor. CONSTITUTION:The video camera equipment at least provided with an image pickup element 21 photoelectric converting an optical image obtained via a lens system L, an A/D converter 23 converting an analog signal from the image pickup element into a digital signal, a luminance signal processing circuit 4 separating and generating respectively a luminance signal and a chrominance signal from an output of the A/D converter, a chrominance signal processing circuit 5, and a shutter speed change means 14 changing the shutter speed in the image pickup element is provided with integration data output means 10 detecting a flicker component by a fluorescent light or the like and a means 8 applying a control signal to the shutter speed change means to coincide the shutter speed with a blink period of the fluorescent light or the like when the flicker component is detected. Thus, possibility of mis-discrimination is precluded even when the camera equipment is used for a district with a different power supply frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera device configured to digitally process a video signal obtained by an image pickup device, and more particularly, to detect a fluorescent lamp flicker when recording indoors. The present invention relates to a video camera device configured to perform brightness correction well.

[0002]

[Technical background] As is well known as a fluorescent light flicker, 1/2 f in a light source that uses a commercial power source with a frequency f (East Japan has 1 f
(/ 100, 1/120 in western Japan) The output image changes due to the illuminance change of the second cycle and the beat component of the field sweep period of the video camera, and this image also causes flicker due to the afterimage characteristics of the human eye. It is a phenomenon that becomes. In particular, it is extremely harmful in the eastern Japan where the field frequency is 60Hz and f = 50Hz in the eastern Japan, and in the PAL system where the field frequency is 50Hz and in the f = 60Hz region. It is remarkable above.

[0003]

2. Description of the Related Art Conventionally, the following means have been used in order to prevent such fluorescent lamp flicker. The signal processing was performed in analog. (1) A luminance measurement sensor is attached to the outer surface of the video camera device, and the presence or absence of a harmful light source exhibiting a flicker phenomenon is detected from the state of the output fluctuation, and if there is, an image sensor (hereinafter referred to as "CCD") ) The shutter mode is switched according to the blinking cycle of the light source {100Hz in the 50Hz power supply area using the NTSC system} to correct it.

(2) Instead of installing an external sensor, a CCD
Flicker is reduced by controlling the brightness gain with an AGC (automatic gain control) circuit having a fast response speed with respect to the brightness signal being output. (3) Considering the flicker correction by the shutter in the TTL (Through the Lens) system, once the flicker is detected and the correction mode is entered, the flicker component completely disappears from the original signal. For this reason, even if the user moves outdoors, the shutter operation remains the same and the sensitivity is slightly lowered. In order to solve this, it is necessary to cancel the correction mode when it is determined that the subject is outdoors by using the information of the automatic white balance.

[0005]

In the conventional video camera device, the means (1) requires an external sensor and a peripheral circuit, resulting in a relatively high cost. In addition, there is a problem that an erroneous judgment is made when used in an area where the power supply frequency is different. On the other hand, the means of (2) has a drawback that it is not possible to make sufficient correction even with a considerably high speed control because it is a gain control method. It should be noted that, as described in (3) above, there has not yet been realized a device that has a means for canceling the correction mode when it is determined that the subject is outdoors using the information on the automatic white balance.

[0006]

A video camera device according to the present invention includes an image pickup device for photoelectrically converting an optical image obtained through a lens system, and an A for converting an analog image signal from the image pickup device into a digital signal. An A / D converter, a luminance signal processing circuit and a color signal processing circuit that separate and generate a luminance signal and a color signal from the A / D conversion output, and a shutter speed changing unit that changes the shutter speed in the image sensor. A control signal is provided to the means for detecting at least the flicker component of the fluorescent lamp for illumination and the shutter speed changing means for adjusting the shutter speed to the blinking cycle of the fluorescent lamp when the flicker component is detected. By solving the above problems, the above problems are solved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the video camera device of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram of a video camera device 1 of the present invention. An optical image from a subject (not shown) is placed on a CCD 21 via a lens system L composed of a plurality of concave and convex lenses and an iris 11 and the like. The image is formed on and photoelectrically converted. Reference numeral 14 is a timing generator (TG) for changing the shutter speed for the CCD 21.

Intermittent video signal output from the CCD 21 is output to the correlating double sampling (Cor-related Double) in the next stage.
Sampling; hereinafter referred to as "CDS") circuit 12 converts the video signal into a continuous video signal, and AGC (gain control) circuit 13 controls the gain to an appropriate level. Further, after signal processing such as known gamma correction is performed by a γ (gamma) correction circuit (45 in FIG. 2, which will be described later), a digital signal is converted into a digital signal by the A / D (analog / digital) converter 23 in the next stage. The converted signal is supplied to the luminance signal processing circuit 4.

The luminance signal processing circuit 4 carries out predetermined signal processing which will be described later, and the signals branched therefrom are subjected to predetermined signal processing in the color signal processing circuit 5. The signal processed here and the output signal of the luminance signal processing circuit 4 are supplied to an encoder processing circuit 6 where they are subjected to encoder processing such as modulation. Then, this signal is converted back into an analog signal by the D / A (digital / analog) converter 7. Since the signal processing is performed digitally from the subsequent stage of the A / D converter 23 to the preceding stage of the D / A converter 7, these circuits are collectively referred to as
Hereinafter, it may be referred to as "DSP" (Disital Signal Processor).

An automatic signal processing circuit 10 which is one component of the DSP has functions such as screen division photometry, brightness peak detection and integrated data output.
Upon receiving signal amplitude data being processed from the color signal processing circuit 5, a microcomputer (hereinafter also referred to as “CPU”)
The data for system control is output to 8 via the data bus 9. Further, the data bus 9 is also connected to the luminance signal processing circuit 4, the color signal processing circuit 5, and the encoder processing circuit 6, and transmits the signal states of the respective parts to the CPU 8 and C
The PU 8 can control each processing circuit.

Flicker detection, which is the main operation of the present invention, is also controlled by this CPU 8. In general, the auto signal processing circuit 10 causes the CPU 8 to display the luminance 1 screen integrated value at every VD (vertical synchronization signal) timing. VD is input and the level comparison of each integrated value is performed for each VD as shown in FIG.
Then, the peak pattern at every 3VD is detected. If the number of detections exceeds a predetermined probability within a certain period, it is determined that there is flicker.

Specific detection and correction operations in flicker detection and flicker correction will be described below in detail with reference to FIGS. This FIG. 3 is a schematic diagram showing the principle of detecting the peak pattern in the fluctuation of the brightness level,
(A) shows the fluctuation process (possible value) of the level (luminance 1 screen integrated value) in 3 vertical scanning periods (hereinafter referred to as "3VD"), and (B) and (C) show Two types of peak patterns are shown respectively. Further, FIG. 4 is a measurement diagram showing an example of the brightness level fluctuation, and FIG. 5 is a flowchart for explaining the flicker detection operation. In this case, the video camera device 1 uses the NTSC system with a commercial power source of 50 Hz, such as East Japan.
It will be described as being used indoors in an area where flicker is likely to occur.

First, the detection method will be described. (1) Immediately after the power of the video camera device is turned on, the constants in the CPU 8 and DSP are initialized (step). (2) At 1VD of the video signal supplied from the input terminal In1 to the luminance signal processing circuit 4, the luminance of the 1-field screen is sampled by the CPU 8 by, for example, adding the 1-field screen integrated average luminance level. The integrated value of the brightness of the field screen, the integrated value of the brightness of the screen one field before, and each integrated value of the brightness of the screen one field before are level-compared (step).

(3) As a result of comparing the latest integrated luminance values of 3VD, it is checked whether or not it corresponds to the peak pattern 1 or 2 shown in FIG. 3 (B) or (C) (step,
). (4) If one peak pattern is detected and the period until the next peak pattern is 3VD, it is determined as the flicker component for the reason described in the principle of the flicker occurrence (see FIG. 4). , While counting up a flicker counter (not shown) in the CPU 8,
Set carry flag (CYF) (step ,,
). If none of the above, the carry flag is cleared (step).

(5) When the carry flag is set, the peak pattern is stored in a storage unit (not shown) such as RAM,
By connecting the stored data to the carry flag and shifting it, the past VD peak pattern is stored (step). At this time, the detection sensitivity can be changed by changing the past number of VDs to be observed according to the number of bytes for securing the memory. For example, the memory is 16 bytes (= 12
If it is 8 bits, it will be judged by observing for past 128 VD (for about 2 seconds). (6) As a result of the above shift, if there is no carry flag, it remains as it is, and if it exists (CYF = 1), the flicker counter is counted down, and the value of the flicker counter is compared with the reference value {steps (10) to (12 )}.

(7) As a result of comparison, if the flicker counter value> reference value, it is determined that the probability of detecting a flicker component is high (flicker is present) and a flicker flag is set. The flicker flag is not set {steps (13), (14)}. (8) If all the operations of the above steps to (14) are performed within 1 VD and the next vertical synchronizing signal is supplied to the CPU 8 through, for example, the input terminal port (not shown), {step (1
5)}, and all the operations from step to (14) are performed again (the same applies hereinafter).

Next, the correction operation in the flicker correction section (in the CPU 8) (not shown) will be described. If the CPU 8 or the flicker detector (not shown) determines that the flicker flag is raised, that is, "flicker is present", the CPU 8 causes the timing generator (TG) 1
A control signal is supplied to 4 to switch the shutter speed for the CCD 21 to 1/100 second. When using a video camera device designed for a field frequency of 50Hz under the lighting with a commercial power supply of 60Hz, switch to 1/60. As a result, the output level fluctuation of the luminance signal as shown in FIG. 4 is greatly reduced.

Instead of software processing by the CPU 8, a flicker detection circuit 42 is provided in the brightness signal processing circuit 4 as shown in the block diagram of FIG. A flicker component may be detected and a control signal may be supplied to the TG 14 to implement a hardware configuration. Since the configuration of the OB clamp circuit 41 and the like in FIG. 2 is well known, a detailed description thereof will be omitted.

A circuit (not shown) for detecting a change in color temperature is provided in the CPU 8 or the color signal processing circuit 5, and a large change in color temperature is detected by this circuit or the luminance signal processing circuit 4 is provided. If the CPU 8 detects that the output level of the luminance signal has significantly increased, the CPU 8 determines that the video camera device 1 has been placed outdoors, and causes the flicker correction unit to cancel the correction operation. Alternatively, if the control signal is supplied from the CPU 8 so that the shutter speed is returned to the standard speed directly to the timing generator 14, the device becomes more convenient.

[0020]

As described above, according to the video camera device of the present invention, an external sensor for detecting a fluorescent lamp flicker is not required, and therefore a peripheral circuit for that is also required, which reduces design restrictions and reduces costs. Can be made compact. Also, FIG.
Since the flicker is detected as shown in the flowchart in Figure 3, it can be realized with a relatively simple program by an assembler, and it is not necessary to configure high-quality filter software such as IIR and FIR, and effective use of CPU resources is possible. You can Furthermore, it has various excellent features that there is no risk of making an erroneous judgment even if it is used in an area where the power supply frequency is different, and the algorithms and software can be commonly used.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a video camera device of the present invention.

FIG. 2 is a block diagram of a luminance signal processing circuit that constitutes the device of the present invention.

FIG. 3 is a schematic diagram showing a principle of detecting a peak pattern in a change in brightness level.

FIG. 4 is a measurement diagram showing an example of luminance level fluctuation observed by the device of the present invention.

FIG. 5 is a flowchart for explaining a flicker detection operation in the device of the present invention.

[Explanation of symbols]

1 ... Video camera device, 4 ... Luminance signal processing circuit, 5 ... Color signal processing circuit, 6 ... Encoder processing circuit, 7 ... D / A converter, 8 ... CPU, 9 ... Data bus, 10 ... Auto signal processing circuit, 14 ... TG, 21 ... CCD, 23 ... A / D converter, L ... Lens system.

Claims (1)

[Claims] 1. An image pickup device for photoelectrically converting an optical image obtained through a lens system, an A / D converter for converting an analog image signal from the image pickup device into a digital signal, and the A / D converter.
A video camera device comprising at least a luminance signal processing circuit and a color signal processing circuit for respectively separating and generating a luminance signal and a color signal from an output of a converter, and a shutter speed changing means for changing a shutter speed in the image pickup device. Supplying a control signal to the shutter speed changing means for adjusting the shutter speed to the blinking cycle of the fluorescent lamp when the flicker component is detected, and the flicker detecting means for detecting the flicker component by the fluorescent lamp as an illumination tool. And a flicker correcting means for controlling the video camera device.