KR950000413Y1 - Ccd auto-iris driving circuit - Google Patents

Abstract

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Description

CCD Auto Iris Driving Circuit

1 is a block diagram of a conventional CCD aperture driving circuit.

2 is a detailed circuit diagram of FIG.

3 is a diagram showing a shutter speed control according to FIG.

4 is a block diagram of a CCD auto-iris driving circuit of the present invention.

5 is a detailed circuit diagram of FIG.

Sixth turn (a) to (c) is also the fourth operational amplifier _{(OP 11), (OP 11} ) and a stop signal and the comparison timing diagram.

(A) to (e) of FIG. 7 are output timing diagrams according to FIG.

* Explanation of symbols for main parts of the drawings

11: image processor 12: integrator

13 amplifier 14 synchronization signal generator

15: triangular wave oscillator 16: comparison unit

17: shutter speed control unit OP ₁₁ -OP ₁₃ : operational amplifier

Q ₁₁ , Q ₁₂ : PNP transistor R _11- R ₁₉ : resistance

VR ₁₁ , VR ₁₂ : Variable resistors C ₁₁ , C ₁₂ : Condenser

The present invention is to adjust the sensitivity of the CCD according to the brightness of the rain incident on the CCD in camcorders, CCD (Charge Coupled Device) cameras, cameras for video door phones, in particular, it is not possible to adjust the aperture by the shutter speed control The present invention relates to a CCD auto-aperture driving circuit adapted to perform an auto-aperture function by using an integrated circuit for driving a CCD.

In general, depending on the amount of light incident on the CCD, a large amount of light appears on the screen, such as a TV screen.

By integrating such a signal, a DC voltage corresponding to the signal of light can be obtained. The DC voltage is used to adjust the shutter speed to the CCD so as to obtain an appropriate DC voltage (that is, a TV screen having an appropriate brightness).

The principle of changing the brightness of the screen as the shutter speed is adjusted is as follows.

The CCD is configured to charge according to the amount of incident light, so that a large amount of light is formed, and a small amount is formed. Therefore, the shutter is how fast to adjust the light incident on the film in a normal camera, if you want to shoot a fast object at a fast shutter speed (1/60 → 1/500 seconds) to obtain the instant picture, CCD How quickly the charge is formed to discharge the shutter, so to take a fast object to take a quick discharge and a new picture to form a charge. This principle makes it possible to shoot fast objects, but it also controls the amount of light incident.

In other words, the charge that depends on the amount of light depends not only on the amount of light, but also on the charging time. It receives a lot of light when charged for a long time and receives less light when charged for a short time.

In the conventional CCD iris driving circuit, as illustrated in FIGS. 1 and 2, the signal IRIS output from the image processor 1 may include the resistors R ₁ , R ₂ , and the ground capacitor C _1. The output of the integrator 2 is output from the integrator 2 that is integrated by? And the operational amplifier OP ₁ that performs offset adjustment by the resistors R ₃ , R ₄ , and the variable resistor VR ₁ . receiving via a resistor (R _5), (R ₆₎ amplifier 3 and an output voltage to each resistor (R _11), (R ₁₂₎ of the amplifier 3, which is amplified by the operational amplifier ((OP ₂ ) Is input to the non-inverting input terminal (+) of the op amp and the operational amplifier (OP ₃ ) and the variable resistance and resistance (VR ₂ , R ₇ ,) to the inverting input terminal (-) and the non-inverting input terminal (+). R ₈ ), the first and second comparison units 4, and (M), which compare the minimum and maximum values set by (VR ₃ , R ₉ , R ₁₀ ) and output them through the resistors R _13- R ₁₆ . 5) and shutter speeds according to the outputs EEUA and EENR of the first and second comparators 4 and 5, respectively. It is composed of a CCD driving unit 6 to adjust the brightness of the screen to determine the conventional technology operation configured in this way, first, the aperture signal (IRIS) corresponding to the image signal of the image processing unit 1, the resistance (R ₁ ), ( R ₂ ) and the ground capacitor C ₁ are integrated to direct current.

The DC voltage is different depending on the input image signal. That is, the DC voltage is different depending on the amount of light input to the CCD. Therefore, the DC voltage is applied to the inverting input terminal (-) of the operational amplifier OP ₁ so as to be within the control range. A DC offset circuit consisting of resistors (R ₃ ), (R ₄ ) and variable resistor (VR ₁ ) is used to amplify by the connected resistors (R ₅ ) and (R ₆ ) and to freely position them within the control range. use.

This direct-current voltage varies depending on the amount of light output is the inverting input terminal of the non-inverting input terminal (+) and an operational amplifier (OP ₃₎ of the operational amplifier (OP ₂₎ by a resistor (R ₁₁ -R ₁₆₎ -, respectively () Is entered. The DC voltages inputted to the operational amplifiers OP ₂ and OP ₃ are the minimum values set by the variable resistors VR ₂ and resistors R ₇ and R ₈ , and the variable resistors VR ₃ and The shutter speed is controlled by controlling the input terminals EEUA and EENR in the CCD driver 6 by the maximum limit values set by the resistors R ₉ and R ₁₀ .

That is, with reference to the diagram shown in Figure 3 as follows.

The output of the operational amplifier (OP ₁₎ beyond the upper limit value in writing the operational amplifier (OP ₃₎ set the output voltage to the amount of light continues to increase much by the variable resistor (VR ₃₎ is of the "low level". At the same time, since this value far exceeds the minimum value set by the variable resistor VR ₂ , the output of the operational amplifier OP ₂ becomes “high level” and the shutter speed starts to increase.

That is, the output voltage of the operational amplifier OP ₁ goes down because it is high when there is much light and low when there is little light.

In this manner, the function of the CCD aperture in the CCD driver 6 is performed.

However, such a conventional CCD aperture driving circuit can be used only by using a CCD driving integrated circuit, but a CCD and driving integrated circuit produced in Korea, which is late in technology development, does not have a shutter speed control function and thus cannot perform a CCD aperture. There was a problem.

The present invention provides a CCD auto-iris driving circuit capable of performing the auto iris function by performing shutter speed control using an integrated circuit for driving a CCD that cannot adjust aperture by shutter speed control. The invention is described with reference to the accompanying drawings as follows.

4 and turning block diagram of a CCD auto iris drive circuit of the subject innovation, the fifth turn as the described this illustrated at 4 degrees detailed circuit diagram, a resistance to the video output signal (IRIS) of the image processing unit ₍₁₁₎ (R 11), The integrator 12 integrated by R ₁₂ and the ground capacitor C ₁₁ and the output voltage of the integrator 12 are inverted in the operational amplifier OP ₁₁ by the resistors R ₁₃ and R ₁₄ . Amplifier 13 for amplifying and offset-adjusting through grounded variable resistor VR ₁₁ and resistor R ₁₁ , and a synchronization signal generator 14 for outputting a vertical drive signal VD generated in the camera circuit. ) And the collector and emitter stages of the PNP transistor Q ₁₁ controlled by the output of the synchronization signal generator 14 and the capacitor C ₁₂ and the ground resistor R ₁₆ of the operational amplifier OP ₁₂ . inverting input (-) and connected to the output side and is connected to the ground, the foregoing variable (VR _12), the non-inverting input terminal (+) that outputs the three triangular waveform Haifa cliché 15 and the operational amplifier (OP _13), a non-inverting input terminal (+) and the inverting input terminal of through the amplifier 15 and the output voltage resistance (R _17), (R ₁₈₎ of the triangular wave oscillation unit (15) A comparator 16 for receiving and comparing the negative signal and outputting the negative voltage to the base of the PNP transistor Q ₁₂ receiving the fixed shutter signal FSS at the emitter stage. The shutter speed controller 17 is configured to output the variable shutter signal VSS from the collector end. The operation and effects of the present invention constructed as described above will be described with reference to FIG. 6 and FIG.

First, the image output signal IRIS of the image processing unit 11 is integrated by the resistors R ₁₁ , R ₁₂ , and the condenser C ₁₁ to form a DC value.

Thus, in order to amplify the voltage DC by the integrator 12, it is input to the inverting input terminal (-) of the operational amplifier OP ₁₁ whose amplification degree is determined by the resistors R ₁₃ and R ₁₄ . It is proportional to the brightness of the light, so if the light is bright, the DC value is low, and if it is dark, the DC value is changed to a high value.

Accordingly, in order to give a reference value, the non-inverting input terminal (+) of the operational amplifier OP ₁₁ is adjusted by giving a DC offset by the variable resistor VR ₁₁ and the resistor R ₁₅ .

Also, the vertical drive signal VD output from the synchronization generating unit 14 is converted into a triangular wave oscillation unit by the PNP transistor Q ₁₁ , the resistor R ₆ , the capacitor C ₂ , and the operational amplifier OP ₁₂ . 15) to be converted into a triangular wave and output.

In addition, the DC signal A of the amplified image signal of the operational amplifier OP ₁ output in this manner is input to the non-inverting input terminal (+) of the operational amplifier OP ₁₃ through the resistor R ₁₇ . (-), the operational amplifier inverting input terminal of the operational amplifier (OP ₁₃₎ through (OP _12), a triangular wave output (B) of the resistance (R ₁₈₎ to the input is compared to a DC voltage by the video signal.

That is, when the light is dark compared to the aperture signal as shown in the timing diagram of FIG. 6, the respective output signals A ₁ and C ₁ are output from the operational amplifiers OP ₁₁ and OP ₁₃ , and the light is When bright, the respective output signals A ₂ and C ₂ are output from the operational amplifiers OP ₁₁ and OP ₁₃ .

Since the output of the compared signal is input to the base of the switching PNP transistor Q ₁₂ , the fixed shutter signal FSS of the emitter stage is cut off to be a variable shutter signal VSS, which is outputted to the collector stage, and then shuttered by the signal. Performs auto iris function by speed control.

That is, when the pulses C ₁ and C ₂ having different duty ratios according to the brightness of light as shown in the timing diagram shown in FIG. 7 are output from the operational amplifier OP ₁₃ as in (b) and (d), The PN transistor Q ₁₂ is turned on only when the output of the operational amplifier OP ₁₃ is low to output the variable shutter signal VSS as in (c) and (e).

As described in detail above, in the related art, the automatic iris function is performed by the shutter speed control using a dedicated integrated circuit for driving a CCD, but the present invention performs the auto iris function without using a dedicated integrated circuit.

That is, in general, CCD and peripheral integrated circuit do not have auto iris function, so it can't be applied to CCD camera for video door phone. do.

Claims (1)

Integrator 12 for integrating and directing the video output signal of image processing unit 1, amplifier 13 for inverting and amplifying the integrated signal by offset adjustment, and vertical output from synchronization generator 14 The triangular wave oscillator 15 for converting the driving signal into triangular waves and outputting the output signal, the comparator 16 for comparing and outputting the output voltages of the amplifier 13 and the triangular wave oscillator 15, and the compared voltages of the comparator 16 And a shutter speed control unit (17) for outputting a fixed shutter signal input as a variable shutter signal to perform an auto iris function.