KR100219558B1 - Iris control apparatus of CCD camera system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCD (Charge Coupled Device) camera system, and more particularly, to an iris control device capable of automatically discriminating and correcting backlight and manually controlling a backlight correction function, Means for determining whether or not backlight is present according to an integral value obtained by integrating the peripheral portion as a backlight region, and means for controlling the opening and closing of the diaphragm by selectively integrating the center portion of the effective screen and the entire effective screen depending on the presence or absence of backlight Means. According to the present invention, when there is backlight in the peripheral portion of the screen, the presence or absence of backlight is automatically determined, and when there is no backlight only in the central portion of the effective screen, the iris is controlled to a value obtained by integrating the entire effective screen to obtain more stable and uniform brightness Even when the backlight and the second subject are simultaneously present around the screen, it is possible to recognize the backlight itself as an effective screen area by a manual operation, so that it is possible to perform an improved shooting even for the second subject have.

Description

[0001] The present invention relates to an iris control apparatus for a CCD camera system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CCD (Charge Coupled Device) camera system, and more particularly, to an iris control device capable of automatically discriminating and correcting backlight and manually controlling a backlight correction function when necessary.

In general, backlight compensation (or window control) function in camera signal processing technology using color and black / white CCD image sensor is a necessary technique in order to protect a subject to be photographed from backlighting to ensure correct shooting. Backlight is generated when a subject is photographed using a CCD camera. In indoor shooting, the sunlight outside the window or a fluorescent light that illuminates the room is used. In outdoor photography, the sun or street light is used. There are various reasons depending on the types of signal processing methods and techniques of the CCD camera, but the biggest factor is the limitation of the dynamic range of the output voltage to the incident amount of the CCD image sensor, which is an important factor of the CCD camera to be. Therefore, it is necessary to adjust the amount of incident light in order to avoid or compensate for excessive or underexposure of backlight. For this purpose, it is necessary to use means such as IRIS and automatic gain control (AGC) The iris is controlled and corrected.

FIG. 1 is a block diagram showing an iris control apparatus of a conventional CCD camera system. A reverse-phase asynchronous video signal is inverted in positive polarity through a negative polarity amplifying unit 110 and input to a blank unit 120. The blank section 120 blankets a video signal generated in the amplification section 110 according to a combination of an H / V blank signal generated from the timing generator and a window (WND) blank signal window for displaying a backlight portion. The integration section 130 integrates the captured video signal during the effective image period occurring in the blank section 120 for several to several tens frames. The comparators 140 and 150 compare the average level of the video signal obtained by the integrator 130 with the reference direct current (DC) levels Vth1 and Vth2 to open the iris if the integrated value of the CCD output is low, And outputs a control signal for closing. However, in the prior art, as shown in FIG. 1, the effective image period is divided under the unconditional condition that the subject is always located at the center of the screen and the backlight is located at the periphery of the screen so that only the central portion excluding the peripheral portion of the screen, The iris is controlled by one value. Therefore, in the related art, as shown in Fig. 2, the backlight function is effective only when the backlight area (WND blank area) is in the peripheral part of the screen and the object area is always in the central part. If the backlight area or relatively bright light or object is in the center of the screen and the subject area is in the periphery, the peripheral area becomes relatively dark because the integral value becomes large and the iris is closed. Even if there is a bright light such as backlight in the periphery of the second screen When the subject is at the periphery of the screen at the same time, the iris is controlled only by the central portion of the screen, so that the second subject is relatively bright and can not be identified.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a CCD camera capable of automatically detecting the presence or absence of backlight to control the diaphragm, And to provide an iris control device.

1 is a block diagram showing an iris control apparatus of a conventional CCD camera system.

Fig. 2 shows a screen division area according to the configuration of Fig.

3 is a block diagram showing an iris control device in a CCD camera system according to the present invention.

FIG. 4 is a timing diagram showing the output waveforms of the respective units of FIG. 3; FIG.

FIG. 5 shows the relation of the video signal level to the reference potential for the iris control of FIG. 3; FIG.

Fig. 6 shows a screen division area according to the configuration of Fig. 3. Fig.

According to another aspect of the present invention, there is provided an apparatus for controlling a diaphragm for correcting backlight of a CCD camera system, the apparatus comprising: first blank means for windowing a peripheral portion of a backlight region of an input video signal; A first comparison means for comparing the integrated value obtained by integrating the signal obtained by the first comparison means with a predetermined reference value to discriminate the presence or absence of the backlight, a blank signal generating means for generating a blank signal for windowing the backlight region when there is backlight in the first comparison means, A second blanking means for blanking the video signal in accordance with each blank signal of the blanking signal generating means to selectively output the central portion of the effective screen and the entire effective screen, , A device for opening and closing the diaphragm according to the presence or absence of backlight generated in the first comparison means A switch for selecting a voltage value, an integrator for integrating a signal output from the second blank means and a predetermined reference voltage value selected by the switch means, 2 comparing means for comparing the first and second reference values.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

3 is a block diagram showing an iris control apparatus in a CCD camera system according to the present invention, which is connected to an output of an amplifier 332 for inverting and amplifying an asynchronous video signal, a first inverter 312 for inputting a WND blank signal , A first blank signal generator 310 having a first end gate 314 for receiving a horizontal (H) / vertical (V) blank signal to generate a combined blank signal, a first blank signal generator The first blank part 316 includes a first blank part 316, a resistor Rl and a capacitor C1 for blanking a video signal output from the amplifier 332 in accordance with a blank signal generated in the first blank part 310, A first switch SW1 for selecting the contact b as a contact point a, a first integrator 318 for integrating a video signal output from the first switch SW1, a contact b connected to a power source and a window potential Wwnd, 1 integrator 318 with the voltage value selected by the first switch SW1 A first comparator 320 for outputting a control signal for determining the presence or absence of backlight, a second comparator 320 for comparing the control signal of the first comparator 320 and the H / V and WND blank signals to a second inverter 324, : A second blank signal generator 323 for generating a blank signal by a combination of a gate 322, a third end gate 326, a fourth end gate 328, and an OR gate (OR) A second blank unit 334 for blanking the video signal output from the amplifier 334 according to a blanking signal generated by the second blank signal generating unit 350, A second integrator 336 having a capacitor C2 for integrating the video signal output from the second blank portion 334, a contact b connected to the reference potentials Vopen1 and Vopen2, A second switch SW2 for selecting the contact point c according to the output control signal of the first comparator 320 and a contact point b and a contact point c connected to the reference potentials Vclose1 and Vclose2, A third switch SW3 for selecting a contact point c according to an output control signal of the comparator 320 and a third switch SW2 for comparing the voltage value selected by the second switch SW2 with the value integrated by the second integrator 336 A second comparator 338 for outputting a control signal for opening the diaphragm, a comparator 338 for comparing a value integrated in the second integrator 336 with a voltage value selected by the third switch SW2, and outputting a control signal for closing the diaphragm And a third comparator 340 for comparing the first and second signals.

3 is a waveform diagram of an asynchronous video signal input to the negative polarity amplifying unit 110 of FIG. 3, and FIG. 4 (B) (C) is a waveform of a window (WND) blank signal input to the terminal 2 of FIG. 3, and (D) is a waveform of a horizontal / vertical blank signal input to the first end gate 314 (E) is a peripheral portion waveform of a video signal generated in the first blank portion 316 in FIG. 3, and (F) is a waveform of a combined blank signal in which the output of the first comparator 320 in FIG. 3 is high (G) is a waveform of a blank signal generated when the output of the first comparator 320 of FIG. 3 is low (L), and (H) is a waveform of the blank signal generated when the first comparator (I) is a waveform of a video signal generated when the output of the first comparator 320 of FIG. 3 is low (L).

FIG. 5 shows the relationship between the video signal level and the reference potential for the diaphragm control in FIG. 3, and the relationship between the video signal level on the vertical axis and the reference potentials Vclose1, Vclose2, Vopen1 and Vopen2 on the horizontal axis, Is adjusted to close, hold, and open.

FIG. 6 is a diagram showing a screen division area according to the configuration of FIG. 3, and a horizontal / vertical blank area, a backlight area (WND blank area) / a subject area, and an effective video area are allocated in a vertical and horizontal period of a video signal.

The asynchronous video signal (FIG. 4A) of the opposite phase input as shown in FIG. 3 is inverted and output in a positive polarity through the negative polarity amplifying unit 332 to be supplied to the first blank unit 334 and the second blank unit 334, (316). The blank pulse a input to the first blank portion 334 is input to the terminal 2 through the horizontal / vertical (H / V) blank signal B of FIG. 4 input from the timing generator to the terminal 1 (W) blank signal C shown in FIG. 4 is logically multiplied by the first end gate 314 to form a waveform as shown in FIG. 4C to blank the video signal (FIG. 4A) The waveform of FIG. 4 (D) shows the waveforms of the first and second inverters 312 and 312 when the horizontal and vertical blank pulses are referred to as "V" and the window (WND) blank pulse is referred to as "W" ) Gate 314 A video signal obtained by taking only the periphery of the effective screen as shown in FIG. 4 (E) can be obtained.

The video signal I (t) output from the first blank unit 316 is converted into a video signal I (t) output from the first blank unit 316 through the first integrator 318, Signal) can be obtained. The first comparator 320 compares the voltage output from the first integrator 318 with the window voltage Vwnd generated when the contact point a of the first switch SW1 is connected to the contact point c, When the video signal level shown in (E) of FIG. 5 is high and the video signal I (t), which is the integral value thereof, is high, the output becomes high (H) (F) waveform), and conversely, it becomes low (L) (waveform of FIG. 4 (G)). Here, when the output of the first comparator 320 is high (H), it is determined that backlight exists. A comparison voltage called a window voltage (Vwnd) connected to the contact (c) of the first switch (SW1) becomes a backlight discrimination reference voltage. When the contact "a" of the switch 1 (SW1) is connected to the contact "b", the power supply voltage Vcc which is the highest potential is connected and the power supply voltage Vcc does not use the backlight correction function That is, when there is backlight in the periphery of the screen, that is, when the second subject is to be photographed, that is, when the second subject is present simultaneously in the periphery of the screen together with backlight. Accordingly, when the contact 'a' of the first switch SW1 is connected to the contact 'b', the output of the first comparator 320 becomes low (L) to indicate the same output as when there is no backlight, The aperture control is performed.

The blank pulse input to the second blank portion 334 of FIG. 3 is a high (H) signal according to the backlight discrimination signal output from the first comparator 320 as shown in waveforms (F) and (G) VW "by the second end gate 322 and the fourth end gate 328, and is input to the second blank portion 334 through the OR gate 330 again. Hence, the second blank part 334 outputs a video signal having only the center part of the effective screen as shown in (H) of FIG. 4. At this time, since the output of the first comparator 320 is high (H) The output of the end gate 326 becomes low (L). As a result, the second blank portion 334 is operated by an OR gate 330 operating only on the output of the fourth end gate 328. [ When the backlight discrimination signal outputted from the first comparator 320 is low, the one end input of the fourth end gate 328 is low (L), so that the other terminal input, that is, the second end gate 322 The output of the first comparator 320, which is low (L) at the input of the third end gate 326, is high (H) through the second inverter 324, , The output of the third end gate 326 obtains the output of the blank pulse "V ". Accordingly, the second blank portion 334 can obtain a video signal except the horizontal and vertical blank regions as shown in (I) of Fig. 4 by the blank pulse which is the output of the third end gate 326, and the second integrator 336 pass through the output of the second blank portion 334

An integral value as shown in Equation (2) can be obtained. Here, V (t) is a video signal output from the second blank portion 334. The second comparator 338 and the third comparator 340 compare the output of the second integrator 336 with the reference voltage Vopen1 or Vopen2, Vclose1, or Vclose2, and compare the output of the second integrator 336 with the second switch SW2 and the third switch SW3, As shown in FIGS. 4 (H) and 4 (I), when the output signal of the first comparator 320 is HIGH (H in FIG. 4) The output of the first comparator 320 is high (H) so that the integrated voltage Vpen2 is lower than the voltage Vpen2 when the voltage of the first comparator 320 is lower than that of the first comparator 320 as shown in FIG. 5 That is, when it is determined that there is backlight, Vopen2 and Vclose2 are switched, and conversely, the comparator 320 automatically switches the comparison voltage to Vopen1 and Vclose1 when the output of the first comparator 320 is low. Here, the reference voltages Vopen1 and Vopen2 are control signals for opening the IRIS through the second comparator 338, and the reference voltages Vclose1 and Vclose2 are control signals for closing the IRIS through the third comparator 340, To achieve this, the set amount should be compared with the magnitude of the corresponding amount of the signal to determine the appropriate amount, and a gap should be given between the reference voltage Vopen and Vclose. This is because if the magnitude of the waveforms shown in FIGS. 4 (H) and 4 (I) is normal, that is, if the output of the CCD image sensor is totally dark or not too bright due to normal IRIS adjustment, It is necessary to have a hold area of the aperture control. Table 1 shows the state of the diaphragm according to the output signal of the second comparator 338 and the output signal of the third comparator 340.

The second comparator output signal The third comparator output signal iris L H Close L L Hold H L Open (Open)

6 can effectively utilize not only the center portion (object region / backlight region) of the effective screen but also the entire effective video region as the iris control region.

As described above, according to the present invention, when there is backlight in the peripheral portion of the screen, the presence or absence of backlight is automatically determined, and when there is no backlight only in the central portion of the effective screen, the iris is controlled by integrating the entire effective screen, Even when backlight and second object are simultaneously present around the screen, it is possible to recognize the backlight itself as an effective screen area by manual operation, so that the second object can be further improved There are advantages to be able to.

Claims (6)

An apparatus for controlling a diaphragm for correcting backlight of a CCD camera system, A first blanking means for blanking an input video signal and outputting a peripheral portion as a backlight region; First comparing means for comparing the integrated value obtained by integrating the peripheral signal output from the first blanking means with a predetermined reference value to determine the presence or absence of backlight; Blank signal generating means for generating a blank signal for blanking the backlight region when there is backlight in the first comparison means and generating a blank signal for blanking the horizontal and vertical synchronization regions in the absence of backlight; Second blanking means for blanking the video signal in accordance with each blank signal of the blank signal generating means to selectively output the central portion of the effective screen and the entire effective screen; Switch means for selecting reference voltage values for opening and closing the diaphragm according to the presence or absence of backlight generated in the first comparison means; And second comparing means for comparing the integrated value obtained by integrating the signal output from the second blanking means with predetermined reference voltage values selected by the switch means to thereby close the iris and generate a signal for opening the iris. Wherein the aperture stop control device is a CCD camera system. 2. The image pickup device according to claim 1, wherein the first comparing means is means for manually selecting a predetermined reference voltage value when the backlight and the second subject exist at the same time, and outputting a signal indicating that there is no backlight A device for controlling aperture of a camera system. The apparatus of claim 1, wherein the first comparison means is a means for determining that backlight exists when the integral value is higher than a predetermined reference value and that backlight is not present when the integration value is lower than a predetermined reference value. The apparatus of claim 1, wherein the second comparing means includes a first comparator for controlling the opening of the iris and a second comparator for controlling the closing of the iris. The apparatus according to claim 1, wherein the second comparing means is a means for generating a signal that the diaphragm is closed when the integral value is larger than a predetermined reference voltage value and the diaphragm is opened when the integral value is smaller than the predetermined reference voltage value The aperture stop of the CCD camera system. 2. The apparatus of claim 1, wherein the blank signal generating means comprises: a first AND gate for logically multiplying different first and second blanking signals; a second AND gate for logically multiplying the output of the first AND gate by an output of the first comparator; A third AND gate for logically multiplying the first blanking signal and a signal obtained by inverting the output of the first comparator, and a third AND gate for performing an OR operation of an output of the second AND gate and an output of the third AND gate, And a 2-ary gate.