KR101097145B1 - Device and method for controlling quantity of incident light - Google Patents

Abstract

PURPOSE: An incident light controlling device and a controlling method thereof are provided to control an amount of incident light in an image sensor by controlling the transmittance of an LCD substrate through the control of a voltage of both electrodes. CONSTITUTION: An LCD substrate(110) controls the transmittance of a liquid crystal layer according to the size of a voltage on both sides thereof. An illumination measuring unit(130) measures brightness around an imaging device. A transmittance control unit(120) outputs a driving signal for moving the LCD substrate according to the comparison result of the surrounding brightness and the preset reference brightness. The transmittance control unit controls the size of the voltage on both sides of the LCD substrate. A substrate driving unit moves to a first position or a second position according to the driving signal.

Description

Device and method for controlling quantity of incident light

The present invention relates to an imaging device, and more particularly, to an incident light amount adjusting device applicable to an imaging device and a control method thereof.

In an imaging device such as a video camera or a camcorder for photographing a moving image, a DC IRIS lens (or an automatic IRIS lens, hereinafter referred to as a "DC IRIS lens") is used as an apparatus for adjusting the amount of incident light. The DC IRIS lens controls the amount of light incident on the image sensor by using an aperture for the light incident through the lens.

FIG. 1 is a cross-sectional view illustrating a configuration of an imaging device equipped with a DC IRIS lens, and FIG. 2 is a conceptual view illustrating a method of adjusting an incident light amount by an aperture in the DC IRIS lens of FIG. 1. In the drawings, it is assumed that light is incident from the upward direction to the downward direction.

The image sensor 5 is installed at the lower part of the body 2 supporting the upper lens 3 and the lower lens 4, so that light passing through the upper lens 3 and the lower lens 4 is electrically received. Convert to a signal. A filter unit 1, such as an optical low pass filter (OLPF) or an IR cut filter, may be interposed between the lower lens 4 and the image sensor 5.

In FIG. 1, the diaphragm 7 is disposed between the upper lens 3 and the lower lens 4, and the opening degree of the diaphragm 7 is adjusted according to the driving of the driving unit 8 connected to the diaphragm 7. The amount of light incident on the image sensor 5 is adjusted.

Referring to FIG. 2, the aperture 7 includes a first shutter member 11 fixed at a specific position, a second shutter member 12 that is movable back and forth relative to the first shutter member 11, and a second An arm member 14 for transmitting a driving force for moving the shutter member 12 back and forth, and a magnet member 15 coupled to one end of the arm member 14 to generate a driving force.

The driving unit 8 is disposed adjacent to the magnet member 15 of the aperture 7 to provide a magnetic force to the magnet member 15, and the magnitude and direction of the current flowing through the coil member 16. It includes a driving circuit 17 for adjusting, and may be, for example, a servo motor or a galvano meter.

The opening degree of the opening 13 is determined according to the magnitude of the current of the driving circuit 17, and when the amount of data output from the image sensor 5 is too dark based on the appropriate brightness, the aperture is opened. In the direction. If too bright, the position of the arm member 14 is changed in the direction of closing the iris. That is, when the DC value of the appropriate brightness is used as the reference value, and the brightness data of the image sensor is converted into the DC value and input to the differential amplifier, the magnet member 15 changes the direction of the current when the voltage is larger or smaller than the DC reference value. The direction of the force applied to the change is changed and the opening degree of the aperture can be changed by changing the position of the arm member 14 coupled to the magnet member 15.

For example, when a current flows in one direction (clockwise in FIG. 2A) by the driving circuit 17, a magnetic field formed in the coil member 16 is a magnet member 15. When acting as a repulsive force to push the magnet member 15 generates a driving force in the direction of movement away from the coil member 16, the arm member 14 and the arm member 14 connected to the magnet member 15 The connected second shutter member 12 also receives a driving force and moves in the same direction, so that the opening 13 between the first shutter member 11 and the second shutter member 12 is opened.

On the contrary, when a current flows to the coil member 16 in the other direction (counterclockwise in FIG. 2B) by the driving circuit 17, the magnetic field formed in the coil member 16 is a magnetic member ( 15 acts as a attracting force, the magnet member 15 generates a driving force in the moving direction closer to the coil member 16, the arm member 14 and the arm member (14) connected to the magnet member 15 ( The second shutter member 12 connected to the 14 also receives a driving force and moves in the same direction so that the opening 13 between the first shutter member 11 and the second shutter member 12 is closed.

As described above, in the method of adjusting the opening degree of the aperture, the depth of focus is changed by changing the opening and closing states of the aperture. When the structure of the aperture is simple, as shown in FIG. 2, a two-leafed aperture is used. In this case, the shape of the opening 13 is changed according to the open and closed states of the aperture. In addition, there is a problem in that the deterioration of the image is induced in the angled portion of the opening 13 when it proceeds to the closed state, and the phenomenon that the image is defocused than the open state occurs.

As another method of adjusting the incident light amount, an electronic shutter function provided by the image sensor may be used. The electronic shutter is a feature used because it is difficult to operate the mechanical shutter every frame due to the characteristics of an imaging device such as a video camera, and the principle thereof will be described with reference to FIGS. 3 and 4.

3 is a circuit diagram showing an electronic shutter structure using a photodiode in the image sensor, and FIG. 4 is a signal diagram of the electronic shutter.

The discharge function of the photo diode is used to store the amount of charge generated in the photo diode only for a specific time (for example, for a time corresponding to the shutter speed) and output as image data. Before output, discharge is prohibited for a time corresponding to the shutter speed, and the amount of charge accumulated in the photodiode during that time is the amount of incident light per frame of the photodiode (or image sensor).

Referring to FIG. 4, the time corresponding to the shutter speed for each frame, that is, the electronic shutter time is until the readout pulse is input after the reset pulse, and the charge accumulated in the photodiode during the electronic shutter time when the readout pulse is input. Is output as pixel data. That is, by adjusting the timing of the reset pulse to adjust the accumulation time of the photodiode for each frame, the amount of charge accumulated in the photodiode is adjusted, and as a result, the incident light amount may be controlled.

As described above, when the incident light amount of the imaging device is adjusted using the electronic shutter, the following problems may occur under a fluorescent lamp environment.

Fluorescent light basically has the same frequency as the frequency of the power supply, so there is a flicker phenomenon. As a result, the brightness of the light and the color temperature of the light source change in synchronization with the power supply frequency. This is not well detected. However, for video cameras, the frame rate is not exactly synchronized with the frequency of the power supply. For video cameras, the NTSC standard frame rate is 59.94 Hz (50 Hz for PAL), which is a frequency that has its own phase divided by the oscillator circuit of the video camera itself. This is because errors in the range of several Hz occur at 60 Hz (NTSC region) or 50 Hz (PAL region) depending on the transmission path.

In this case, only a portion of the electronic shutter is used as incident light every frame time, so the change in brightness and color temperature caused by the flicker phenomenon of the fluorescent lamp vibrates at the harmonic frequency of the power frequency and the frame frequency of the video camera. The phenomenon occurs, and there is a problem in that a phenomenon in which a light is brightened and darkened in the captured image, and a color rolling phenomenon in which the color of the light source changes is generated. This phenomenon has a problem in that the image is brighter and becomes more severe when a smaller shutter speed value is used. If the shutter speed is greater than the flicker frequency of the fluorescent lamp, the change of the brightness and the color temperature of the light source accumulates and the problem of the change of the brightness or the color temperature is alleviated.

In addition, as another method of controlling the amount of incident light, Korean Laid-Open Patent Publication No. 2010-0010669 has a polarization pattern formed on two of the lenses that receive light from a subject, thereby opening and closing the lens opening according to the rotation of the lens. Technical information is disclosed, and Korean Patent No. 1010269 has two polarizers arranged between lenses in an optical system, and rotates one polarizer to adjust the amount of light incident on the optical system without changing the aperture size of the aperture. Is disclosed.

Korean Patent Publication No. 2010-0010669 Korean Registered Patent No.1024269

An object of the present invention is to provide an incident light amount adjusting device for controlling the amount of light incident on an image sensor by controlling a transmittance of an LCD substrate by adjusting a voltage across the electrodes of a liquid crystal display (LCD) substrate, and a method of controlling the same.

In addition, the present invention prevents the change in focus and lens depth unnecessarily by changing the aperture shape of the aperture by using the LCD substrate, and does not cause the bleeding or color rolling phenomenon by fixing the accumulation time of the image sensor. It is to provide an incident light amount adjusting device and a control method thereof.

In addition, the present invention is to control the incident light amount through the control of the transmittance of the LCD substrate, while removing the LCD substrate from the incident light path under a specific low light situation to prevent the lowering of transmittance due to the LCD substrate and the incident light amount control device and its control It is to provide a method.

Other objects of the present invention will be readily understood through the following description.

According to an aspect of the present invention, an apparatus for controlling the amount of light incident to the image sensor is installed in the image pickup device, the LCD substrate positioned on the incident light path, the transmittance of the liquid crystal layer is adjusted according to the magnitude of the voltage across both ends; And a transmittance control unit controlling a magnitude of a voltage across both ends of the LCD substrate.

An illuminance measuring unit may further include an illuminance measuring unit configured to measure ambient brightness of the imaging device, wherein the transmittance controller may calculate a difference between the ambient brightness and the required brightness, and adjust the magnitude of the voltage according to the result.

The LCD substrate includes a first polarizing plate, a first glass plate, a first transparent electrode, a first liquid crystal alignment film, a liquid crystal layer, a second liquid crystal alignment film, a second transparent electrode, a second glass plate, and a second polarizing plate, According to the magnitude of the voltage applied between the first transparent electrode and the second transparent electrode, an alignment state of liquid crystal molecules in the liquid crystal layer may change, and thus transmittance may vary.

According to another aspect of the present invention, an apparatus for adjusting the amount of light incident to the image sensor is installed in the scratch device, the LCD substrate for controlling the transmittance of the liquid crystal layer according to the magnitude of the voltage across the; An illuminance measuring unit for measuring the ambient brightness of the image capturing apparatus in which the incident light amount adjusting device is installed; A transmittance controller configured to output a driving signal for moving the LCD substrate according to a result of comparing the predetermined reference brightness with the ambient brightness, and to control the magnitude of the voltage across the LCD substrate; And a substrate driver for moving the LCD substrate to one of a first position and a second position according to the driving signal, wherein the first position is on an incident light path and the second position is an arbitrary position removed from the incident light path. An incident light amount adjusting device is provided.

The transmittance controller outputs a driving signal for operating the substrate driver to remove the LCD substrate on the incident light path when the ambient brightness is less than or equal to a predetermined reference brightness, and when the ambient brightness is higher than the reference brightness, the LCD substrate The driving signal for operating the substrate driver to be positioned on the incident light path may be output.

When the ambient brightness is higher than the reference brightness, the transmittance controller may calculate a difference between the ambient brightness and the required brightness, and adjust the magnitude of the voltage according to the result.

The LCD substrate includes a first polarizing plate, a first glass plate, a first transparent electrode, a first liquid crystal alignment film, a liquid crystal layer, a second liquid crystal alignment film, a second transparent electrode, a second glass plate, and a second polarizing plate, According to the magnitude of the voltage applied between the first transparent electrode and the second transparent electrode, an alignment state of liquid crystal molecules in the liquid crystal layer may change, and thus transmittance may vary.

According to still another aspect of the present invention, there is provided a control method of an incident light amount adjusting device installed in an image capturing apparatus to adjust an amount of light incident on an image sensor by adjusting a transmittance of an LCD substrate, and a recording medium having a program for performing the same. do.

According to an embodiment, there is provided a method of controlling an incident light amount adjusting apparatus, the method including measuring ambient brightness of the imaging device; Calculating a difference between the ambient brightness and the required brightness; And adjusting the magnitude of voltage applied to both ends of the LCD substrate according to the calculation result.

According to another exemplary embodiment, a method of controlling an incident light amount adjusting apparatus includes: measuring ambient brightness of the imaging device; Determining whether the ambient brightness is below a predetermined reference brightness; And removing the LCD substrate from the incident light path when the ambient brightness is less than the reference brightness as a result of the determination, and positioning the LCD substrate on the incident light path when the ambient brightness is higher than the reference brightness as a result of the determination. Can be.

Determining the position of the LCD substrate when the ambient brightness is less than or equal to the reference brightness; Only when the LCD substrate is located on the incident light path, the method may include outputting a driving signal to the substrate driver to move the LCD substrate away from the incident light path.

Determining a position of the LCD substrate when the ambient brightness is higher than the reference brightness; The method may include outputting a driving signal to the substrate driver to move the LCD substrate to be positioned on the incident light path only when the LCD substrate is located away from the incident light path.

Calculating a difference between the ambient brightness and the required brightness when the ambient brightness is higher than the reference brightness; And adjusting the magnitude of voltage applied to both ends of the LCD substrate according to the calculation result.

Other aspects, features, and advantages will become apparent from the following drawings, claims, and detailed description of the invention.

According to the exemplary embodiment of the present invention, the amount of light incident on the image sensor may be adjusted by controlling the transmittance of the LCD substrate by adjusting the voltage across the electrodes of the LCD substrate.

By not opening or closing the iris, it is possible to prevent the lens from being unnecessarily changed due to the shape change of the opening and to unnecessarily change the accumulation time of the image sensor, thereby making the light brighter and darker in the captured image. There is no color rolling phenomenon in which the color changes depending on a light source such as a breeding phenomenon or a fluorescent lamp.

In addition, while adjusting the amount of incident light by adjusting the transmittance of the LCD substrate, under low light conditions, the LCD substrate may be removed from the incident light path to prevent a decrease in transmittance due to the LCD substrate, thereby improving low light characteristics.

1 is a cross-sectional view showing the configuration of an imaging device equipped with a DC IRIS lens;
FIG. 2 is a conceptual diagram illustrating a method of adjusting an incident light amount by an aperture in the DC IRIS lens of FIG. 1;
3 is a circuit diagram showing an electronic shutter structure using a photodiode in the image sensor;
4 is a signal diagram of an electronic shutter,
5 is a block diagram illustrating an apparatus for adjusting incident light amount according to an embodiment of the present invention;
6 is a cross-sectional view showing the structure of an LCD substrate;
7 is a conceptual diagram for explaining a principle of controlling transmittance of an LCD substrate;
8 is a graph showing a correlation between transmit voltage and transmittance of an LCD substrate;
9 is a cross-sectional view showing the configuration of an imaging device including an incident light amount adjusting device according to an embodiment of the present invention;
10 is a flow chart of a control method of the incident light amount control apparatus according to an embodiment of the present invention,
11 is a block diagram of an incident light amount adjusting device according to another embodiment of the present invention;
12 is a cross-sectional view for describing a method for adjusting an incident light amount in an imaging apparatus including an incident light amount adjusting device according to another embodiment of the present invention;
13 is a flowchart illustrating a control method of an incident light amount adjusting apparatus according to another embodiment of the present invention.

The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated and described in the drawings. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof. In the present specification, when a part is "connected" to another part, this includes not only "directly connected" but also "indirectly connected" between other components in between. do.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 5 is a block diagram illustrating a configuration of an incident light amount control apparatus according to an embodiment of the present invention. FIG. 6 is a cross-sectional view illustrating a structure of an LCD substrate. FIG. 7 is a conceptual diagram illustrating a principle of transmittance control of an LCD substrate. 8 is a graph showing the correlation between the applied voltage and the transmittance of the LCD substrate.

The incident light amount adjusting apparatus 100 according to an exemplary embodiment of the present invention may be applied to an image capturing apparatus including an image sensor such as a video camera or a camcorder to capture a moving image or a still image.

Referring to FIG. 5, the incident light amount adjusting apparatus 100 according to an exemplary embodiment of the present invention includes an LCD substrate 110 and a transmittance controller 120.

The LCD substrate 110 is basically positioned in the optical path and the incident light path where light is incident on the image sensor of the imaging device, and the transmittance is changed according to the magnitude of the voltage applied to both ends. The incident light amount of light may be adjusted according to the change in transmittance of the LCD substrate 110.

The transmittance controller 120 controls the transmittance of the LCD substrate 110 by changing a voltage applied to both ends of the LCD substrate 110. The correlation between the voltage applied to both ends of the LCD substrate 110 and the transmittance may be defined in the form of, for example, a graph, a formula, a lookup table, and the like.

The transmittance control unit 120 determines the transmittance of the LCD substrate 110 to allow sufficient light to be incident on the image sensor, and calculates or looks up the magnitude of the voltage to be the transmittance using a predefined graph or equation. It can be retrieved from the table and applied to both ends of the LCD substrate 110.

The incident light amount adjusting device 100 may further include an illuminance measuring unit 130 measuring peripheral illuminance. The illuminance measuring unit 130 may obtain brightness information from a result of analyzing image data output from the image sensor or may obtain brightness information from a signal sensed by an illuminance sensor separately provided in the imaging apparatus.

If the image data has the YCbCr format or YUV format, the brightness information can be calculated using the arithmetic mean of the Y value indicating the brightness of each pixel.If the image data has the RGB format, the YCbCr format or YUV format can be used. Through the format conversion process of converting to, Y value can be obtained and brightness information can be calculated therefrom. Format conversion will be apparent to those skilled in the art, and a detailed description thereof will be omitted.

The transmittance controller 120 may determine whether the current brightness is the required brightness based on the brightness information obtained by the illuminance measuring unit 130, and determine the transmittance so that the corresponding brightness may be achieved if the brightness is not required. .

The structure of the LCD substrate 110 included in the incident light amount adjusting device 100 of the present invention is illustrated in FIG. The LCD substrate 110 has a flat plate structure, and terminals connected to transparent electrodes at both ends thereof are connected to the transmittance controller 120 to receive a voltage for controlling the transmittance of the LCD substrate 110.

Referring to the drawings, when the incident surface of light is divided into an upper surface and an emission surface of light, the LCD substrate 110 includes the first polarizing plate 111, the first glass plate 112, and the first surface. 1 transparent electrode 113, 1st liquid crystal aligning film 114, liquid crystal layer 115, 2nd liquid crystal aligning film 116, 2nd transparent electrode 117, 2nd glass plate 118, 2nd polarizing plate ( 119).

Basically, when light passes through the first polarizing plate 111 located at the upper end, the light is polarized in one direction according to the polarization direction of the first polarizing plate 111. When the light polarized in one direction passes through the liquid crystal layer 115 whose orientation is determined by the first liquid crystal alignment film 114 and the second liquid crystal alignment film 116, the phase of polarization may be changed. The light passing through the liquid crystal layer 115 may have a predetermined polarization phase, and all or part of the light may pass through the second polarizer 119 or not pass at all according to the polarization direction of the second polarizer 119.

In this case, the physical phase alignment state of the polarizing plate and / or the liquid crystal alignment film, that is, the alignment direction between the first polarizing plate 111 and the second polarizing plate 119 positioned at both ends of the LCD substrate 110, and the first liquid crystal alignment film 114. And at least one of the alignment directions of the second liquid crystal alignment film 116 determine a major feature related to the transmittance of the LCD substrate 110. In addition, the liquid crystal directionality of the liquid crystal layer 115 is controlled according to the electrical polarization phase adjustment between the liquid crystal alignment films to change the transmittance of light. This will be described with reference to the illustration illustrated in FIG. 7.

Referring to FIG. 7A, the polarization direction of the first polarizing plate 111 is in the X-axis direction, the polarization direction of the second polarizing plate 119 is in the Y-axis direction, and the first liquid crystal alignment film 114 and the first polarizing plate 111 are formed. It is assumed that the second liquid crystal alignment film 116 has the same phase alignment state as the first polarizing plate 111 and the second polarizing plate 119, respectively. In the state in which no voltage is applied, the alignment state of the liquid crystal molecules 115a is distorted corresponding to the phase alignment state of the liquid crystal alignment films on both sides, and the liquid crystal has a 90 degree direction while descending from the top to the bottom. In this case, the light incident on the upper surface is polarized in the X-axis direction when passing through the first polarizing plate 111, and the polarization phase is changed by 90 degrees as it passes through the liquid crystal layer 115, and is polarized in the Y-axis direction so that the second polarizing plate is (119) can be passed. That is, the LCD substrate 110 is in a transparent state.

Referring to FIG. 7B, when a voltage greater than or equal to a predetermined magnitude is applied between the first transparent electrode 113 and the second transparent electrode 117, the alignment state of the liquid crystal molecules 115a is changed to phase of the liquid crystal alignment film. Irrespective of the arrangement state, the light passing through the liquid crystal layer 115 is aligned so as not to have directivity so that the polarization phase does not change. In this case, the light incident on the upper surface is polarized in the X-axis direction when passing through the first polarizing plate 111, and the polarization phase is not changed even when passing through the liquid crystal layer 115, thereby maintaining the polarized state in the X-axis direction. It cannot be passed through the second polarizing plate 119. That is, the LCD substrate 110 is in an opaque state.

That is, the overall light transmission characteristic of the LCD substrate 110 is changed according to the degree of the arrangement of the liquid crystal molecules 115a in the liquid crystal layer 115.

In the above, the directions of the upper and lower polarizing plates and the liquid crystal alignment film are the same, and when the upper and lower directions are 90 degrees, the LCD substrate 110 is opaque in a transparent state as voltage is applied to both ends of the LCD substrate 110. Although the description is based on the assumption that the state changes, the reverse case is also possible. If the upper and lower directions are the same, the voltage will be changed from the opaque state to the transparent state as voltage is applied to both ends of the LCD substrate 110.

That is, in the present invention, when the transmittance of the LCD substrate 110 is changed according to the voltage applied to both ends, the amount of incident light is adjusted by using a portion (part A of FIG. 8) in which the transmittance changes according to the voltage adjustment. do. Referring to part A of FIG. 8, the voltage and the transmittance follow a monotone function correlation.

Correlation in which the transmittance changes according to voltages applied to both sides may be stored in the transmittance control unit 120 in the form of a graph as illustrated in FIG. 8 or in the form of an equation or a lookup table.

9 is a cross-sectional view illustrating a configuration of an imaging device including an incident light amount adjusting device according to an embodiment of the present invention.

The incident light amount adjusting device 100 according to the present exemplary embodiment adjusts the amount of light incident on the light path before the light is incident on the image sensor 5, that is, on the incident light path. To this end, the LCD substrate 110 of the incident light amount adjusting device 100 is disposed between the lower lens 4 and the image sensor 5 (see FIG. 9A), and between the upper lens 3 and the lower lens 4. (See FIG. 9B), the upper portion of the upper lens 3 (see FIG. 9C).

In addition, the LCD substrate 110 of the incident light amount adjusting device 100 is disposed at an arbitrary position on a path through which light incident to the image sensor 5 passes, thereby adjusting the amount of light before light is incident on the image sensor 5. Could be.

10 is a flowchart illustrating a control method of an incident light amount adjusting apparatus according to an embodiment of the present invention. Each step described below may be performed by each internal component of the incident light amount adjusting device 100.

In operation S210, the incident light amount adjusting device 100 measures the peripheral illuminance. The measurement of the peripheral illuminance may be performed by analyzing brightness of the image data output from the image sensor or by obtaining brightness information from a sensing signal of the illuminance sensor included in the imaging device.

In step S220, it is determined whether the measured ambient illuminance is the required brightness, and when the brightness is not required, the transmittance of the LCD substrate for obtaining the corresponding brightness is determined. The correlation between transmittance and brightness of the LCD substrate may be statistically determined through experiments.

In step S230 to calculate the magnitude of the voltage to be applied to the LCD substrate in order to obtain the determined transmittance of the LCD substrate, the corresponding voltage is applied to both ends of the LCD substrate to adjust the amount of incident light. The correlation between the transmittance and the applied voltage of the LCD substrate may be determined in the form of a graph as described with reference to FIG. 8 or in the form of an equation, a lookup table, or the like.

FIG. 11 is a block diagram illustrating an incident light amount adjusting device according to another embodiment of the present invention, and FIG. 12 illustrates a method for adjusting incident light amount in an imaging device including an incident light amount adjusting device according to another embodiment of the present invention. It is a section for.

The incident light amount adjusting device 300 according to another exemplary embodiment of the present invention may also be applied to an image capturing apparatus including an image sensor such as a video camera or a camcorder to capture a moving image or a still image.

Referring to FIG. 11, the incident light amount adjusting apparatus 300 according to another embodiment of the present invention includes an LCD substrate 310, a transmittance controller 320, an illuminance measuring unit 330, and a substrate driver 340.

The LCD substrate 310 is basically positioned in an optical path where light is incident on the image sensor of the imaging device, that is, in the incident optical path, and transmittance is changed according to the magnitude of the voltage applied to both ends. The incident light amount of light may be adjusted according to the change in transmittance of the LCD substrate 310. In this embodiment, the position of the LCD substrate 310 may be changed by moving according to the driving of the substrate driver 340 which will be described later.

The illuminance measuring unit 330 acquires information about brightness around the device. The ambient brightness information may be obtained from an analysis result of the image data output from the image sensor or from a signal sensed by an illuminance sensor provided in the imaging device.

The transmittance controller 320 controls the transmittance of the LCD substrate 310 by changing a voltage applied to both ends of the LCD substrate 310. For example, the correlation between the voltage applied to both ends of the LCD substrate 310 and the transmittance may be defined in the form of a graph, a formula, a lookup table, or the like.

In addition, the transmittance control unit 320 may determine that the image pickup device is placed in or out of a predetermined low light condition based on the ambient brightness information acquired by the illuminance measurement unit 330, that is, a light state that is brighter than a predetermined reference brightness. When it is changed to or is changed to a bright state in a state darker than the predetermined reference brightness to output a driving signal to the substrate driver 340.

The substrate driver 340 moves the LCD substrate 310 from the first position to the second position or from the second position to the first position according to the driving signal output from the transmittance controller 320. The substrate driver 340 may be a driving device that rotates by a predetermined angle in one direction or the other direction according to a driving signal, for example, a servo motor or a galvanometer.

Here, the first position is any position on the incident light path that allows incident light to pass through the LCD substrate 310, and the second position allows incident light to enter the image sensor without passing through the LCD substrate 310. An arbitrary position other than the incident light path is shown, and the movement of the LCD substrate 310 may vary depending on the design structure of the imaging device, such as, for example, rotation or forward and backward movement.

That is, the substrate driver 340 may position or remove the LCD substrate 310 on the incident light path according to the driving signal from the illuminance measuring unit 330.

When the LCD substrate 310 is on the incident light path, even if the LCD substrate 310 is in a transparent state, light transmittance itself may not be high while passing through the polarizing plate, the transparent electrode, and the liquid crystal layer. As the transmission efficiency decreases by about 50% while passing through the first polarizing plate, the transmission efficiency decreases further while passing through the transparent electrode and the liquid crystal layer.

If the dynamic range of the input image is larger than the dynamic range of the image sensor in a high light quantity environment, it does not cause a big problem in the representation of the image output from the image sensor. However, under low light amount, low light characteristics are deteriorated due to a decrease in transmittance due to the presence of the LCD substrate 310.

Accordingly, the incident light amount adjusting device 300 according to the present embodiment basically positions the LCD substrate 310 on the incident light path to enable continuous incident light adjustment, but when the brightness is lower than a predetermined reference brightness, the LCD substrate 310 ) Is removed from the incident light path, thereby eliminating the decrease in transmittance caused by the LCD substrate 310, thereby improving low light characteristics.

Referring to FIG. 12, when the LCD substrate 310 is positioned in the incident light path according to the operation of the substrate driver 340 (see FIG. 12A) and when the LCD substrate 310 is removed from the incident light path. (See FIG. 12B) is illustrated. In FIG. 12, the LCD substrate 310 of the incident light amount adjusting apparatus 300 according to another embodiment of the present invention is illustrated as being disposed between the lower lens 4 and the image sensor 5. According to the embodiment, as shown in FIG. 9, the display device may be disposed anywhere between the upper lens 3 and the lower lens 4 or on the path through which light is incident to the image sensor 5, such as the upper portion of the upper lens 3. Could be.

An infrared cut filter may be included in the LCD substrate 310 of the incident light amount adjusting apparatus 300 according to the present embodiment. The infrared cut filter may be attached on the polarizing plate or the glass plate of the LCD substrate 310.

The infrared cut-off filter is a filter for blocking infrared light in the entrance light, and it is necessary to be removed from the incident light path so that the transmittance of the infrared light does not deteriorate when photographing using the infrared light at low illumination. When included, the position is changed according to the driving of the substrate driver 340, so that the light is removed from the incident light path in a low light condition to prevent a decrease in transmittance of infrared light.

13 is a flowchart illustrating a control method of an incident light amount adjusting apparatus according to another embodiment of the present invention. Each step described below may be performed by each internal component of the incident light amount control device 300 according to another embodiment of the present invention.

In operation S410, the incident light amount adjusting device 300 measures peripheral illuminance. The measurement of the peripheral illuminance may be performed by analyzing brightness of the image data output from the image sensor or by obtaining brightness information from a sensing signal of the illuminance sensor included in the imaging device.

In operation S420, it is determined whether the measured ambient illuminance is equal to or less than a predetermined reference brightness. Under certain low light conditions, the presence of the LCD substrate itself degrades the characteristics of the output image, to prevent this phenomenon.

If the ambient illuminance is lower than or equal to the reference brightness, the process proceeds to step S430 to determine the position of the LCD substrate. If the position of the LCD substrate is located on the L1 position, that is, the incident light path, the process proceeds to step S440 to generate a drive signal in the substrate driver to remove the LCD substrate on the incident light path. If the position of the LCD substrate is located outside the L2 position, that is, the incident light path, the LCD substrate is already removed on the incident light path, and the flow proceeds to step S450 to maintain the position of the LCD substrate.

If the ambient illuminance is higher than the reference brightness, that is, not in a low illuminance situation, the flow advances to step S460 to determine the position of the LCD substrate.

If the position of the LCD substrate is located outside the L2 position, that is, the incident light path, in step S470, the driving unit generates a drive signal to move the LCD substrate to the L1 position, that is, the incident light path, and then proceeds to step S480. do. If the position of the LCD substrate is located at the L1 position, that is, the incident light path, step S470 is skipped and the process proceeds directly to step S480.

It is determined whether the ambient illuminance measured in step S480 is the required brightness, and when the brightness is not required, the transmittance of the LCD substrate for obtaining the corresponding brightness is determined. The correlation between transmittance and brightness of the LCD substrate may be statistically determined through experiments.

In operation S490, the magnitude of the voltage to be applied to the LCD substrate is calculated to obtain the determined transmittance of the LCD substrate, and the corresponding voltage is applied to both ends of the LCD substrate to adjust the amount of incident light. The correlation between the transmittance and the applied voltage of the LCD substrate may be determined in the form of a graph as described with reference to FIG. 8 or in the form of an equation, a lookup table, or the like.

It is apparent that the above-described method for controlling the incident light amount adjusting device may be performed by an automated procedure according to a time series sequence by a software program or the like embedded in the incident light amount adjusting device 300. The codes and code segments that make up the program can be easily deduced by a computer programmer in the field. In addition, the program is stored in a computer-readable information storage medium, and the program is read and executed by a computer to implement the method. The information storage medium includes a magnetic recording medium, an optical recording medium, and a carrier wave medium.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims And changes may be made without departing from the spirit and scope of the invention.

100, 300: incident light amount adjusting device
110, 310: LCD substrate
120, 320: transmittance control unit
130, 330: illuminance measuring unit
340: substrate driver

Claims (13)

delete delete delete A device installed in the imaging device to adjust the amount of light incident on the image sensor,
An LCD substrate whose transmittance of the liquid crystal layer is adjusted according to the magnitude of the voltage across the both ends;
An illuminance measuring unit for measuring the ambient brightness of the image capturing apparatus in which the incident light amount adjusting device is installed;
A transmittance controller configured to output a driving signal for moving the LCD substrate according to a result of comparing the predetermined reference brightness with the ambient brightness, and to control the magnitude of the voltage across the LCD substrate; And
A substrate driving unit for moving the LCD substrate to one of a first position and a second position in accordance with the drive signal,
And the first position is on the incident light path, and the second position is an arbitrary position removed from the incident light path.
The method of claim 4, wherein
The transmittance controller outputs a driving signal for operating the substrate driver to remove the LCD substrate on the incident light path when the ambient brightness is less than or equal to a predetermined reference brightness, and when the ambient brightness is higher than the reference brightness, the LCD substrate And a driving signal for operating the substrate driver to be positioned on the incident light path.
The method of claim 4, wherein
If the ambient brightness is higher than the reference brightness,
And the transmittance controller calculates a difference between the ambient brightness and the required brightness, and adjusts the magnitude of the voltage according to the result.
The method of claim 4, wherein
The LCD substrate includes a first polarizing plate, a first glass plate, a first transparent electrode, a first liquid crystal alignment film, a liquid crystal layer, a second liquid crystal alignment film, a second transparent electrode, a second glass plate, and a second polarizing plate,
And a light transmittance of the liquid crystal molecules in the liquid crystal layer is changed according to the magnitude of the voltage applied between the first transparent electrode and the second transparent electrode.
delete A control method of an incident light amount adjusting device installed in an imaging device to adjust an amount of light incident on an image sensor by adjusting a transmittance of an LCD substrate,
Measuring ambient brightness of the imaging device;
Determining whether the ambient brightness is below a predetermined reference brightness; And
And removing the LCD substrate from the incident light path when the ambient brightness is less than the reference brightness as a result of the determination, and placing the LCD substrate on the incident light path when the ambient brightness is higher than the reference brightness as a result of the determination. Control method of light intensity control device.
10. The method of claim 9,
If the ambient brightness is less than the reference brightness,
Determining the position of the LCD substrate;
And outputting a driving signal to a substrate driver to move the LCD substrate out of the incident light path only when the LCD substrate is located on the incident light path.
10. The method of claim 9,
If the ambient brightness is higher than the reference brightness,
Determining the position of the LCD substrate;
And outputting a driving signal to a substrate driver to move the LCD substrate to be positioned on the incident light path only when the LCD substrate is located away from the incident light path.
10. The method of claim 9,
If the ambient brightness is higher than the reference brightness,
Calculating a difference between the ambient brightness and the required brightness; And
And controlling the magnitude of the voltage applied to both ends of the LCD substrate according to the calculation result.
A program of instructions that can be executed by the digital processing apparatus for performing the control method of the incident light amount adjusting apparatus according to any one of claims 9 to 12 is tangibly implemented and can be read by the digital processing apparatus. Record carrier.

Images