KR20010087951A - A device for controlling inputting linght in optical device - Google Patents

Abstract

PURPOSE: An optical amount controller of an optical device is provided to be capable of realizing an accurate brightness control by controlling the array angle of liquid crystal of an LCD panel using a digital signal, and to simplify the structure and save power consumption by simultaneously performing an iris function and an electron shutter function. CONSTITUTION: An LCD panel(100) comprises a first electrode for applying a common voltage, a second electrode for applying a first voltage, and liquid crystal between the first and second electrodes, and controls optical amount incident through the liquid crystal. Light passing through the LCD panel(100) is focused with a constant refraction rate by a lens part(200) A CCD part(300) converts an image focused by the lens part(200) into electrical signals. A control part(400) calculates an average brightness of incident light using signals output from the CCD part(300), and compares the average brightness with a preset brightness to output a control signal for performing an exposure correction process corresponding to the compared result. An exposure control part(500) outputs a digital signal for the first voltage corresponding to the control signal. A D/A converter(600) converts a digital signal output from the exposure control part(500) into the first analog voltage applied to the second electrode of the LCD panel.

Description

A DEVICE FOR CONTROLLING INPUTTING LINGHT IN OPTICAL DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device, and more particularly, to a light amount adjusting device for adjusting an amount of light incident on an optical device.

In digital image reproducing apparatus including a digital camera, exposure control was performed using an aperture mounted outside the lens and an electronic shutter controlled inside the CCD. In the case of using a mechanical aperture, it is impossible to precisely control the amount of light that can automatically compensate for the exposure of a moving image, and in the case of using the electronic shutter, it is difficult to control the amount of light for a large exposure and a small exposure.

Therefore, in the case of a general digital camera, a mechanical aperture and an electronic shutter are used at the same time to perform automatic exposure compensation using the electronic shutter with the aperture open indoors, and an electronic shutter with the aperture reduced outdoors. It consists of an exposure compensation system that compensates for automatic exposure.

If more than two exposure control means are used for the exposure control, the exposure control system becomes complicated and difficult to configure. When using a mechanical aperture, various problems occur such as a large amount of power is consumed by the electric motor driving the aperture. do.

Therefore, the present invention is to solve the conventional problems, the configuration of the system is simple, low power consumption and so as not to have a spatial discrimination for exposure compensation.

1 is a block diagram of a light quantity control device of an optical device according to a first embodiment of the present invention.

2 is a block diagram of a light quantity control device of the optical device according to the second embodiment of the present invention.

A light amount control apparatus of an optical apparatus according to a feature of the present invention for achieving the above object is to position the liquid crystal panel in front of the photographing lens system, and adjust the angle of the liquid crystal of the liquid crystal panel to adjust the amount of light incident to the photographing lens system. Here, the liquid crystal is positioned between two electrodes, a common voltage is applied to the first electrode and a variable voltage is applied to the second electrode. Accordingly, the liquid crystal blocks or passes incident light by varying an angle positioned according to a voltage difference between two substrates, that is, an electric field intensity. In this case, the light quantity control device of the optical device according to the characteristics of the present invention subdivids the level of the variable voltage applied to the second electrode to adjust the intensity of the electric field on the liquid crystal, and the level of the variable variable voltage is determined by the user. Alternatively, the reference light amount automatically set is compared with the incident light amount, and the value corresponding to the comparison difference is determined.

Here, the light quantity control device of the optical device according to the characteristics of the present invention, in order to subdivide the intensity of the electric field applied to the liquid crystal so that the value corresponding to the comparison difference is an n-bit digital signal, and the n-bit digital signal is analog again. The signal is converted into a signal so as to be a variable voltage applied to the second electrode. Therefore, the light quantity control device of the optical device according to the feature of the present invention It has three variable voltage levels, which enables fine light amount adjustment.

In order to achieve the characteristics of the present invention as described above, the light amount control apparatus of the optical device according to the characteristics of the present invention,

A liquid crystal panel including a first electrode to which a common voltage is applied, a second electrode to which a first voltage is applied, and a liquid crystal positioned between the first electrode and the second electrode, and controlling an amount of light incident through the liquid crystal;

An imaging lens system for imaging light passing through the liquid crystal panel with a constant refractive power;

An imaging element unit for converting an image formed by the photographing lens system into an electrical signal and outputting the electrical signal;

A control unit for calculating an average brightness of light incident on the signal output from the imaging device unit, and outputting a control signal for performing exposure correction corresponding to a comparison result by comparing the calculated average brightness with a set brightness;

An exposure adjuster configured to output a digital signal corresponding to the first voltage corresponding to the control signal output from the controller; And

And a digital / analog converter converting the digital signal output from the exposure controller into an analog first voltage and applying the same to the second electrode of the liquid crystal panel.

Hereinafter, a light quantity control device of an optical device according to a first embodiment of the present invention will be described with reference to FIG.

1 is a block diagram of a light quantity control device of an optical device according to an embodiment of the present invention. As shown in FIG. 1, a light amount control apparatus of an optical device according to an exemplary embodiment of the present invention includes a liquid crystal display (LCD) panel 100, a lens unit 200, a charge coupled device (CCD) unit 300, and a control unit. 400, an automatic exposure control unit 500, and a D / A converter 600.

Light incident on the light amount control device of the optical device according to the embodiment of the present invention configured as described above primarily passes through the LCD panel 100.

The LCD panel 100 is a transmissive monochrome LCD panel and includes two electrodes and a plurality of liquid crystals positioned between the two electrodes. A common voltage is applied to the first electrode of the two electrodes, and a variable voltage output from the D / A converter 600 is applied to the second electrode. Therefore, the intensity of the electric field formed between the two electrodes is adjusted and determined according to the level of the variable voltage applied to the second electrode. It is already known that the liquid crystal has an arrangement angle determined by the strength of the electric field formed around it. Therefore, the arrangement angle of the liquid crystal of the LCD panel 100 is determined according to the variable voltage applied to the second electrode.

Here, the liquid crystal of the initial LCD panel 100 is said to be arranged at a corresponding angle in accordance with the user or automatically set exposure amount. At this time, a voltage corresponding to the set exposure amount will be applied to the second electrode.

In this state, the light incident on the LCD panel 100 is incident to the lens unit 200 by the remaining light blocked by a predetermined amount by the alignment angle of the liquid crystal.

The lens unit 200 is composed of a plurality of lenses, and the incident light having a predetermined refractive power is imaged to the CCD unit 300.

The CCD unit 300 includes a plurality of CCD elements, and light is formed on the CCD elements. In this case, the position of the CCD element may be located in various ways depending on the situation, but it is preferable to be located in the center of the image. The CCD unit 300 converts the intensity of light incident through the CCD device into an electrical signal and outputs the electrical signal to the controller 400.

The control unit 400 basically controls the operation by outputting a control signal to the CCD unit 300, the automatic exposure control unit 500, and other electric operation units when the main power switch (not shown) is turned on. In addition, the controller 400 according to an aspect of the present invention receives a signal regarding the intensity of incident light output from the CCD unit 300, determines the luminance of the incident light, and calculates an average luminance. Then, the controller 400 compares the calculated average brightness with the brightness set by the user or by the automatic exposure operation, and calculates a comparison difference. The controller 400 determines whether the average luminance of the light incident as the comparison difference is higher or lower than the set luminance.

At this time, the control unit 400 outputs a control signal to the automatic exposure control unit 500 so that the average luminance is lowered by one level when the determined difference is higher than the set luminance, that is, the average luminance is higher than the set luminance, and the determined difference is negative. That is, when the average luminance is lower than the set luminance, a control signal for raising the average luminance by one class is output to the automatic exposure controller 500.

The automatic exposure controller 500 stores digital values for the variable voltage Va applied to the second electrode, and the digital values for the variable voltage Va are subdivided into 1024 pieces. Therefore, the range between the maximum value and the minimum value of the variable voltage Va is differentiated to 1024, so that the light quantity control device of the optical device according to the embodiment of the present invention has 1024 grades of adjustable luminance.

On the other hand, the automatic exposure control unit 500 has a digital value for the set luminance set in the control unit 400 by the user or by automatic exposure compensation, and outputs the set digital value to the D / A converter 600. The liquid crystals of the LCD panel 100 are arranged at corresponding angles so that the set luminance is incident.

In this state, when the automatic exposure control unit 500 receives a control signal from the control unit 400, the automatic exposure control unit 500 increases or decreases the digital value by one according to the control signal. That is, when the average luminance is higher than the set luminance, the automatic exposure controller 500 outputs a digital value for the variable voltage Va, which decreases the average luminance level by '1', to the D / A converter 600. . On the other hand, when the average luminance is lower than the set luminance, the automatic exposure controller 500 outputs a digital value for the variable voltage Va, which increases the average luminance level by '1', to the D / A converter 600. . At this time, the digital signal output from the automatic exposure control unit 500 is 10 bits.

The D / A converter 600 receives a 10-bit digital signal output from the automatic exposure controller 500, converts it into an analog signal, and outputs the analog signal to the second electrode of the LCD panel 100. In this case, the converted analog signal is a variable voltage Va. Therefore, the variable voltage Va output from the D / A converter 600 has 1024 levels corresponding to the 10-bit digital signal.

The variable voltage Va applied to the second electrode of the LCD panel 100 forms an electric field according to the potential difference with the common voltage, changes the arrangement angle of the liquid crystal, and changes the transmittance of incident light. The variable transmittance at this time is one of 1024 grades.

The average luminance of the incident light according to the variable transmittance is compared with the set luminance by the control unit 400 again, and if the average luminance is not equal to the set luminance, the automatic exposure control unit may be used to change the transmittance of the LCD panel 100 again. The control signal is output to the control unit 500, and accordingly, the automatic exposure control unit 500 increases or decreases the set digital value by 1 according to the control signal of the control unit 400, and outputs it to the D / A converter 600. The / A converter 600 forms an analog variable voltage corresponding to the input digital signal and applies it to the second electrode.

As a result, the light quantity control apparatus of the optical device according to the first embodiment of the present invention as described above has a transmittance of the LCD panel 100 of 1024 grade, and by performing such transmittance control according to the digital value, precise transmittance control and minute light quantity Adjustment is made.

Hereinafter, the light quantity control device of the optical device according to the second embodiment of the present invention will be described with reference to FIG.

2 is a block diagram of a light quantity control device of the optical device according to the second embodiment of the present invention. As shown in Fig. 2, the light amount control apparatus of the optical device according to the second embodiment of the present invention includes the first and second LCD panels 110 and 120, the lens unit 200, the CCD unit 300, and the control unit. 400, the first and second automatic exposure control units 510 and 520 and the first and second D / A converters 610 and 620.

The configuration according to the second embodiment of the present invention as described above has substantially the same configuration as the configuration according to the first embodiment.

However, the second embodiment of the present invention controls the amount of light by placing two transmissive black and white LCD panels 110 and 120 in the lens unit 200, thereby controlling the amount of light with a higher transmittance grade than the first embodiment. At this time, the light amount control apparatus of the optical device according to the second embodiment of the present invention, in order to control the transmittance of the first LCD panel 100, the first automatic exposure control unit 510 and the first D / A converter ( The second automatic exposure control unit 520 and the second D / A converter 620 are used to adjust the transmittance of the second LCD panel 120.

Thus, the second embodiment of the present invention has a higher transmittance grade than the first embodiment of the present invention having one LCD panel 100.

Here, the operation of the light quantity control device of the optical device according to the second embodiment of the present invention will be described in detail.

When light enters a state where the liquid crystals of the first and second LCD panels 100 and 110 maintain their respective alignment angles by a user or by an automatic exposure operation, the light passes through the first LCD panel 100. Then, the light penetrates the second LCD panel 110 and enters the lens unit 200.

The lens unit 200 forms incident light onto the CCD unit 300 with a predetermined refractive power, and the CCD unit 300 converts the intensity of the formed light into an electrical signal and outputs the electrical signal to the controller 400.

Then, the controller 400 calculates an average luminance of the light incident from the signal input from the CCD unit 300 and determines whether the average luminance is higher or lower than the set luminance compared with the set luminance. Then, the controller 400 outputs a control signal corresponding to the determination result to the first or second automatic exposure control unit 500.

At this time, the control unit 400 according to the second embodiment of the present invention is stored information on the transmittance grade adjustment. The information on adjusting the transmittance rating includes information on which of the first and second LCD panels 110 and 120 should be adjusted when increasing or decreasing the transmittance rating by 1, and the difference between the average brightness and the set brightness. If it is large, it is information on how to adjust the transmittance of the first and second LCD panels 110 and 120 so that the change in the overall transmittance grade is large. In this case, the controller 400 according to the second exemplary embodiment of the present invention preferably sets information on how much the transmittance grade is to be set if the difference between the two luminances is greater than the reference luminance difference.

Accordingly, the first or second automatic exposure adjusting units 510 and 520 drive the digital signal for varying the angle of the liquid crystal of each LCD panel 100 by driving according to the control signal output from the controller 400. Output to the first or second D / A converter (610, 620).

Then, the first or second D / A converters 610 and 620 convert the input digital signals into analog variable voltages Va1 and Va2 and apply them to the second electrodes of the respective LCD panels 110 or 120. .

As a result, the first and second LCD panels 110 and 120 adjust the amount of light incident on the lens unit 200 by varying the transmittance of the incident light according to the arrangement angle of the liquid crystals.

Here, when the number of bits of the digital signal output from the first and second automatic exposure controllers 510 and 520 is 10 bits, the variable voltage applied to the second electrodes of the first and second LCD panels 110 and 120 ( The level of Va) is 1024 levels, respectively, and becomes a total of 1024x1024 levels. If the number of bits of the digital signal is 8 bits, it is 256x256 level.

Therefore, it is apparent that the light quantity control device of the optical device according to the second embodiment of the present invention can control the transmittance more precisely than the light amount control device of the optical device according to the first embodiment.

The present invention is capable of precise brightness adjustment by placing a transmissive black and white LCD panel in front of the photographing lens system and controlling the alignment angle of the liquid crystal of the LCD panel as a digital signal. There is little effect of consumption.

Claims (6)

A liquid crystal panel including a first electrode to which a common voltage is applied, a second electrode to which a first voltage is applied, and a liquid crystal positioned between the first electrode and the second electrode, and controlling an amount of light incident through the liquid crystal; An imaging lens system for imaging light passing through the liquid crystal panel with a constant refractive power; An imaging element unit for converting an image formed by the photographing lens system into an electrical signal and outputting the electrical signal; A control unit for calculating an average brightness of light incident on the signal output from the imaging device unit, and outputting a control signal for performing exposure correction corresponding to a comparison result by comparing the calculated average brightness with a set brightness; An exposure adjuster configured to output a digital signal corresponding to the first voltage corresponding to the control signal output from the controller; And And a digital / analog converter for converting the digital signal output from the exposure controller into an analog first voltage and applying the digital signal to the second electrode of the liquid crystal panel. The method of claim 1, The exposure control unit, The digital value of the variable voltage applied to the second electrode of the liquid crystal panel is stored, and the digital value set according to the control signal output from the controller increases or decreases by one. Light quantity control device. The method of claim 2, The exposure control unit, And an information obtained by dividing the variable voltage by 256 or more, and outputting 8-bit or more digital signals to the digital / analog converter. The method of claim 1, The liquid crystal panel, An apparatus for controlling the amount of light of an optical apparatus, comprising a first liquid crystal panel and a second liquid crystal panel arranged side by side perpendicular to the incident optical axis. The method of claim 4, wherein The exposure control unit, Applying the voltage to be applied to the second electrode of the first liquid crystal panel having information divided into 256 grades or more and outputting 8-bit or more digital signals to the first exposure controller and the second electrode of the second liquid crystal panel. And a second exposure control unit for outputting a digital signal of 8 bits or more, having information divided into 256 or more classes of the applied voltage. The method of claim 5, The digital to analog converter, A first digital analog converter configured to convert the digital signal output from the first exposure controller into an analog signal and apply the analog signal to the second electrode of the first liquid crystal panel, and the digital signal output from the second exposure controller And a second digital / analog converter for converting the signal into a second electrode of the second liquid crystal panel.