KR102639980B1 - Electrical Light Control Unit of CAMERA MODULE - Google Patents

Abstract

The present invention relates to a liquid crystal light quantity control device that can minimize optical distortion occurring in an image sensor in a camera module when a larger amount of light is incident than usual, and to a light quantity control device for a camera module using the same.
The light quantity control device according to the present invention is provided in a camera module to control the light quantity, and includes a transparent upper plate and a transparent lower plate arranged to face each other at a certain distance apart. a mixed liquid crystal layer filled with a mixture of liquid crystal, dichroic dye, and chiral dopant between the upper and lower plates; And an electrode layer for applying an electric field to the mixed liquid crystal layer; Under the condition that the mixed liquid crystal layer satisfies [Equation 1] and [Equation 2] below, the chiral dopant is 0.1% to 13% It is characterized in that it is configured to satisfy a concentration within the range.
[Equation 1]
1/P = H * C
(Where, P: pitch of liquid crystal, H: helical twisting power (HTP) of chiral dopant, C: concentration of chiral dopant (%))
[Equation 2]
T _R = (Δn * d) / λ _R
T _G = (Δn * d) / λ _G
T _B = (Δn * d) / λ _B

Description

Electronic light control unit of camera module {Electrical Light Control Unit of CAMERA MODULE}

The present invention relates to a camera module, and more specifically, to an electronic light intensity control device for a camera module that provides an optimal amount of light to an image sensor, thereby enabling a clear image to always be obtained.

In general, camera modules (camera modules) are applied in various industries such as portable terminals including tablet PCs and smartphones, toy cameras, automobiles, medical industries, security industries, and other industries (drones, wearable devices, 3D printers, etc.) CCM (COMPACT CAMERA MOUDULE) is manufactured in a small size, and in recent years, the number of products being launched is gradually increasing as it is equipped with camera modules with various functions to suit the various tastes of customers.

Such camera modules are manufactured using image sensors such as CCD or CMOS as main components. They provide light brightness information and color information about the image of the subject to these image sensors, and then process the image within the device to determine the color of the image within the device. Ensure that images are displayed in close to natural colors through display media.

Meanwhile, as the design of portable terminals diversifies, product differentiation, and the diverse needs of consumers lead to rapid development of component technology, including camera modules built into portable terminals, camera modules for automobiles, medical industries, security industries, and other industries are also being developed. Products with various functions are being developed one after another to meet the diverse needs of consumers and manufacturers.

Recently, camera modules equipped with megapixel lenses have been installed in portable terminals, automobiles, drones, robots, CCTV and other related products in different packages depending on their components and are being operated in a variety of ways. At the same time as running the camera, it has a flash function for night shooting or illuminating dark places, HDR (High Dynamic Range), a macro function for shooting close-range subjects by manually changing the lens focus, and magnifying specific parts of the image and subject. Products with optional digital zoom and optical zoom functions are available on the market.

This is explained with the accompanying drawings as follows.

Figure 1 is a block diagram showing a conventional camera module decomposed into several main functional blocks.

1A is a schematic diagram of a camera module including an auto-focusing function, where the image sensor and the printed circuit board are spaced apart;

Figure 1b is a schematic configuration diagram of a camera module including an auto-focusing function with an image sensor mounted on a printed circuit board;

Figure 1C is a schematic configuration diagram of a camera module without an auto-focusing function.

As can be seen in FIG. 1A, a conventional camera module consists of a lens unit, an actuator, a filter unit, an image sensor, and a printed circuit board.

The lens unit 10 consists of a casing consisting of a head case and a base case for storing the lens 11, and a carrier 12 consisting of a panel and a bobbin.

The actuator 20 is a module that moves the lens in the vertical direction and provides an auto-focusing function, and is composed of an upper spring, lower spring, yoke, magnet, coil, etc.

The filter unit 30 is located below the actuator 20 and serves to block light in an unnecessary wavelength range.

The image sensor 40 is located below the filter unit 30 and serves to recognize the image received through the lens 11.

The printed circuit board 50 transmits the brightness information and color information of the light recognized by the image sensor 40 to the image processor, thereby allowing the user to recognize the object.

The unexplained symbol 41 is a signal line for transmitting a signal from the image sensor to the printed circuit board 50, and is usually composed of a flexible printed circuit board (commonly referred to as 'FPCB').

The above-described signal line 41 may be omitted by mounting the image sensor 40 on the printed circuit board 50, as shown in FIG. 1B.

Meanwhile, in the case of a camera module that does not provide an auto-focusing function, the actuator 20 may be omitted, as shown in FIG. 1C.

In a conventional camera module configured in this way, there is a difference in the amount of light even when shooting at the same time depending on the morning, noon, and afternoon of the day, day and night, and season, and the amount of incident light according to this difference in light amount cannot be properly adjusted in hardware. There wasn't.

Accordingly, the optical distortion caused by the incident light has been controlled in a software manner using a program, but there is a problem in that clear image quality cannot be obtained due to limitations in processing by the software method.

In particular, as mentioned above, as image sensors require increasingly higher specifications and higher resolution, they react sensitively to even small differences in light amount, generating noise, and optical processing for this is not possible, resulting in the problem of not being able to obtain clear image quality. There is.

In this way, a method of applying a liquid crystal display panel of a liquid crystal display device can be considered as a way to hardware control the amount of incident light. However, a passive element display panel uses two polarizers, so in a state where no voltage is applied, the display panel uses two polarizers. The transmittance (Toff/Ton) is 1% to 5%, and the transmittance (Ton/Toff) in the voltage applied state is 42% to 45%. And to obtain the maximum transmittance, use the following equation:

T = (Δn * d) / λ

Here, Δn is the refractive index of the liquid crystal, d is the thickness of the liquid crystal layer, and λ uses a single wavelength of 550 nm.

However, when a typical liquid crystal display panel with such transmittance characteristics is applied to a camera module, only light brightness information is displayed. In particular, when operating in the light quantity increase mode according to voltage application, the transmittance is too low to allow the camera to capture images. Due to inappropriate conditions, such conventional liquid crystal display panels had a problem in that it was difficult to apply them to camera modules.

Patent Document 1: Korean Patent Publication No. 10-2009-0105018 (published on October 7, 2009)

The present invention was invented to solve the above problems, and the purpose of the present invention is to provide light brightness information and color ( The goal is to provide an electronic light intensity control device for a camera module that provides color information.

The electronic light quantity control device of the camera module according to the present invention to achieve the above object is a device provided in the camera module to control the light quantity,

In the camera module,

It consists of an upper plate, a lower plate, and a mixed liquid crystal layer.

The top plate contains an electrode layer and an alignment agent and is coated with an anti-reflective film.

The lower plate contains an electrode layer and an alignment agent and is coated with an anti-reflective film.

The upper and lower plates are spaced at a certain distance, and a mixed liquid crystal layer is formed between them.

The mixed liquid crystal layer is composed of a mixture of liquid crystal, dichroic dye, and chiral dopant.

Under the condition that the mixed liquid crystal layer satisfies [Equation 1] below, the chiral dopant is configured to satisfy a weight percentage concentration within the range of 0.1% to 1.5%.

[Equation 1]

1/P = H * C

(Where, P: Pitch of liquid crystal, H: Helical Twisting Power (HTP) of chiral dopant, C: Concentration of chiral dopant (%))

In addition, under the condition that the mixed liquid crystal layer satisfies [Equation 2] below, the mixed liquid crystals and the dichroic dye are configured to satisfy a weight percentage concentration within the range of 5% to 20%.

[Equation 2]

T _R = (Δn * d) / λ _R

T _G = (Δn * d) / λ _G

T _B = (Δn * d) / λ _B

(Here, Δn is the refractive index of the liquid crystal, d is the thickness of the liquid crystal layer, and λ uses the wavelengths of R, G, and B.)

Additionally, to improve transmittance, the antireflection coating is made of a combination of the following materials.

SiO ₂ , ZrO ₂ , TiO ₂ , Mg ₂ O, Al ₂ O ₃ , SiO.

SV5, SV7, SV8, SV10, SV20, SV21, SV55, SV71.

The electronic light intensity control device of the camera module configured as described above is installed in front of the lens part of the camera module or in front of the image sensor, and transmits excessively bright external light to the image sensor by adjusting the brightness information and color information. You can do it.

The electronic light amount control device of the camera module according to the present invention detects that the amount of light of the image to be captured is high and ensures that the optimal amount of light is incident on the image sensor, thereby minimizing optical distortion of transmittance distortion and image distortion occurring in the image sensor. there is.

In addition, through the combination of liquid crystal and other additives and their concentration and pitch control, it was possible to implement the appropriate total transmittance and color transmittance required when adjusting the light amount of the camera module, and stable operation of the device (i.e., liquid crystal It has the effect of ensuring the implementation of a stable second orientation state.

Figure 1 is a block diagram showing a conventional camera module decomposed into several main functional blocks.
1A is a schematic diagram of a camera module including an auto-focusing function, where the image sensor and the printed circuit board are spaced apart;
Figure 1b is a schematic configuration diagram of a camera module including an auto-focusing function with an image sensor mounted on a printed circuit board;
Figure 1C is a schematic configuration diagram of a camera module without an auto-focusing function.
Figure 2 is a cross-sectional configuration diagram of the electronic light intensity control device according to the present invention installed between the subject and the image sensor.
Figure 3 is a photograph showing the change in transmittance when the electronic light amount control device of the camera module manufactured according to an embodiment of the present invention is turned on and off.
Figure 4 shows the standard transmittance of 90% and 60%, respectively, as measured in the on/off operating state of the electronic light intensity control device of the camera module manufactured according to an embodiment of the present invention. This is the result of comparing optical characteristics compared to ND-Filter.
Figure 5 shows that the electronic light intensity control device of the camera module manufactured according to an embodiment of the present invention has a total transmittance of 90% and 60%, and the transmittance when the applied voltage is turned on/off at the R/G/B wavelength is R/G of natural light. /B It is an optical measurement value that indicates a wavelength similar to the wavelength and indicates the result of obtaining a natural image (video) using natural light.
Figure 6 is a photograph showing backlight correction by applying the electronic light amount control device of the present invention to an autonomous vehicle.
Figure 7 is a diagram illustrating that when applying the electronic light quantity control device of the present invention to an autonomous vehicle, the vehicle's field of view is divided into multiple areas and the electronic light quantity control device is operated only in areas where the light quantity is excessive.
Figure 8 is a photograph showing that the electronic light quantity control device of the present invention is applied to a smart window to control the light quantity.

The terms used in the present invention are only used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “comprise” or “have” are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that this does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

In addition, in this specification, “on or above” means located above or below the target portion, and does not necessarily mean located above the direction of gravity. Additionally, when a part of a region, plate, etc. is said to be “on or above” another part, this does not only mean that it is in contact with or at a distance “directly on or above” another part, but also that there is another part in between. Also includes cases where there are.

In addition, in this specification, when a component is referred to as "connected" or "connected" to another component, the component may be directly connected or directly connected to the other component, but specifically Unless there is a contrary description, it should be understood that it may be connected or connected through another component in the middle.

Additionally, in this specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

In addition, in this specification, since there are positive and negative methods due to the characteristics of LCDs, the description of one method as an example does not exclude the other method.

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

Figure 2 is a configuration diagram of the electronic light intensity control device according to the present invention installed in a conventional camera module.

A camera module including an electronic light intensity control device according to the present invention includes a control unit 150 on a printed circuit board 50 for sending a signal to the light intensity adjustment device 100.

The light quantity control device 100 of the invention includes an upper plate, a lower plate, and a mixed liquid crystal layer.

The upper plate includes an electrode layer and an aligning agent,

The lower plate includes an electrode layer and an aligning agent,

A mixed liquid crystal layer is disposed between the upper and lower plates.

The mixed liquid crystal layer is composed of liquid crystal mixed with a dichroic dye and chiral dopant at a certain ratio.

Here, the liquid crystal of the mixed liquid crystal layer is composed of nematic liquid crystal, preferably a negative (N-type) nematic liquid crystal with negative dielectric anisotropy,

It can also be composed of positive (P-type) nematic liquid crystal with positive dielectric anisotropy.

More specifically, the electronic light quantity control device 100 according to the present invention is a plate body in which the upper plate and the lower plate are arranged to face each other with opposing surfaces spaced a certain distance apart, and is a transparent substrate with excellent light transmittance and no birefringence effect. In addition, the electrode layer and the aligning agent may also be made of glass, film, or plastic, which are materials with excellent light transmittance, or a combination thereof.

The thickness (D) of the upper and lower plates is in the range of 0 < D <= 1.5mm, and is preferably in the range of 0.1 to 0.4mm.

The mixed liquid crystal layer is filled at regular intervals between the upper and lower plates and plays the role of controlling the amount of light, that is, the light transmittance, by the applied voltage. The mixed liquid crystal layer contains liquid crystal, dichroic dye, and chiral dopant at a uniform ratio. It is included and mixed together.

Here, the liquid crystal is composed of nematic liquid crystal, and is preferably composed of negative (N-type) nematic liquid crystal with negative dielectric anisotropy, so that it can implement a transparent state when no voltage is applied.

Dichroic dye is used to absorb light incident on the mixed liquid crystal layer when the light quantity reduction mode of the mixed liquid crystal layer is driven by voltage application.

Therefore, dichroic dyes having the following characteristics are used.

In other words, dichroic dyes have dichroism with a large difference in absorbance between the long and short axis directions of the molecule, dyeing ability with high affinity for the liquid crystal as the host material, and can be easily oriented in conjunction with the orientation of the liquid crystal according to voltage control. Use one that has acceptable orientation and durability that can sufficiently withstand the manufacturing process and usage conditions.

According to a preferred embodiment, the dichroic dye is preferably a P-type, black-colored dichroic dye that has a high absorption rate of light polarized in the long axis direction.

The chiral dopant combines the pitch of the liquid crystal with the thickness of the mixed liquid crystal layer to guide the rotation of the optical axis to occur stably in one direction during the second orientation of the liquid crystal according to the application of an electric field, and the liquid crystal in the second orientation state, which will be described later, It is a configuration that allows it to be arranged in a twisted structure to achieve a transmittance suitable for the camera module.

The mixed liquid crystal layer allows the liquid crystals to form a first alignment state, which will be described later, when no voltage is applied, and to form a second alignment state, which will be described later, when voltage is applied, thereby controlling the amount of light. In particular, the liquid crystal light amount adjusting device of the present invention can be used as a general display device. In order to use it in a camera module that does not have a camera module, the transmittance in the first orientation must be in the range of 60% to 95%, and the transmittance in the second orientation must be in the range of 20% to 60%.

For reference, the liquid crystal display panel of the passive device (active device) has a transmittance of 42% to 45% in the initial orientation state (the first orientation state of the present invention) according to the non-application of voltage, and the transmittance in the rotated orientation state (the first orientation state of the present invention) according to the application of voltage. The transmittance of the second orientation state) is configured to have characteristics of 1% to 5%.

However, if a typical liquid crystal display panel with such transmittance characteristics is applied to a camera module as is, it is unsuitable for the conditions for imaging of the camera, especially when operating in a voltage-free mode, so such a conventional liquid crystal display panel cannot be used in a camera module. .

Ultimately, in order to control the amount of light and perform imaging when mounted on a camera module, a transmittance of 60% to 95% in non-driving mode, and especially a transmittance of 20% to 60% in driving mode, can be achieved to provide light brightness information. In addition, it must provide color (R/G/B) information similar to natural light. In order to implement such transmittance characteristics, the liquid crystal light intensity control device of the present invention must provide the mixed liquid crystal layer under the condition that the following equation 1 is satisfied. , the chiral dopant is characterized in that it is configured to satisfy a concentration within the range of 0.1% to 2% (preferably 0.5% to 1.5%).

[Equation 1]

1/P = H * C

(Where, P: pitch of liquid crystal, H: chiral herical twisting power (HTP), C: concentration of chiral dopant (%))

[Equation 2]

T _R = (Δn * d) / λ _R

T _G = (Δn * d) / λ _G

T _B = (Δn * d) / λ _B

(Here, Δn is the refractive index of the liquid crystal, d is the thickness of the liquid crystal layer, and λ uses the wavelengths of R, G, and B.)

Meanwhile, the chiral dopant 135 may be configured to have left-handedness or right-handedness, or may be configured to have both left-handedness and right-handedness.

In addition, since the liquid crystal light quantity control device of the present invention can be exposed to various temperature environments, temperature compensation is required considering the temperature range to which the liquid crystal light quantity control device can be exposed, and this temperature range setting is necessary. Accordingly, the concentration range of the chiral dopant 135 can be determined by Equation 1 and Equation 3 below.

[Equation 3]

(P ^-1 )(T _L ) = (P ^-1 )(T _U ) = (-)1/5 ~ (-)1/20

(Where, P: pitch of liquid crystal, T _L : lowest temperature, T _U : highest temperature)

As an example, if the difference between the highest and lowest temperature of the temperature environment to which the liquid crystal light intensity control device can be exposed is expected to be 80°C, the chiral dopant can be configured to have a concentration in the range of 0.2% to 9%.

Here, if the chiral dopant is composed of a form in which both left-handedness and right-handedness coexist, the left-handed chiral dopant is composed of a concentration in the range of 0.1% to 5%, and the right-handed chiral dopant is composed of a concentration in the range of 0.1% to 4%. It is preferable to configure it by concentration (% by weight).

As another example, if the difference between the highest and lowest temperature of the temperature environment to which the liquid crystal light intensity control device can be exposed is expected to be 50°C, the chiral dopant can be configured to have a concentration in the range of 0.1% to 7%. .

Here, if the chiral dopant is composed of a form in which both left-handedness and right-handedness coexist, the left-handed chiral dopant is composed of a concentration in the range of 0.1% to 4%, and the right-handed chiral dopant is composed of a concentration in the range of 0.0% to 3%. It is desirable to configure it by concentration.

Meanwhile, these chiral dopants may be mixed in either a cholesteric phase or a nematic phase.

As described above, the mixed liquid crystal layer according to the present invention is composed of a mixture of chiral dopants along with the liquid crystal, so that the pitch of the liquid crystal is combined with the thickness of the mixed liquid crystal layer, so that the optical axis changes during the second alignment operation of the liquid crystal according to the application of power. It guides the rotation to occur stably in one direction, and is configured so that the liquid crystals can be arranged to form a twisted structure in the second orientation state, where the 'pitch of the liquid crystal is combined with the thickness of the mixed liquid crystal layer' is specifically defined as follows. means.

[Equation 4]

Under the conditions of Equation 4, the thickness of the mixed liquid crystal layer (hereinafter referred to as 'cell gap') needs to satisfy 1.5um~15um, and is preferably 4um~12um. Under the condition of Equation 4, the pitch (pitch:P) of the liquid crystal is in the second orientation state where an electric field is applied.

i) When the twist angle (Φ) of the liquid crystal is = 90, the range is 0.2 <= d/P <= 0.3

ii) When the twist angle (Φ) of the liquid crystal is = 180, the range is 0.25 <= d/P <= 0.6

ⅲ) When the twist angle (Φ) of the liquid crystal is = 270, the range is 0.6 <= d/P <= 0.8

iv) When the twist angle (Φ) of the liquid crystal is = 360, the range is 0.8 <= d/P <= 1

Just select a liquid crystal that satisfies.

In addition, the dielectric anisotropy (△ε) of liquid crystal has a negative value, and if it has "-15 < -△ε< 0" at 1 kHz and 25°C, it can be used as a liquid crystal light quantity control device, and is preferably the same. It is good to have a dielectric anisotropy of "-14 <= -△ε<= -0.5" under the condition.

The electrode layer is a component for applying an electric field to the mixed liquid crystal layer. This electrode layer applies an electric field perpendicular to the mixed liquid crystal layer between the upper plate and the lower plate. The electrode is made of indium tin oxide (ITO) or indium zinc oxide (IZO). ), Zinc Oxide, Tin Oxide, Fluorine-doped Zinc Oxide (FTO), PEDOT:PSS, Graphene, Silver Nanowire ( It may be formed of at least one selected from the group of transparent conductive materials consisting of (AgNW) and carbon nanotubes (CNT).

Meanwhile, the electrode layer may be constructed using an IPS (In-Plane Switching) method in which a pair of electrodes (e.g., a pixel electrode and a common electrode) are formed in the same layer on the same substrate (i.e., an upper and lower plate) to form an electric field. It may be possible.

As another example, the electrode layer forms a pair of electrodes (e.g., a pixel electrode and a common electrode) on the same substrate (i.e., an upper plate and a lower plate) to form an electric field, but the pixel electrode and the common electrode are formed on different layers. It can also be configured in the FFS (Fringe-Field Switching) method by placing an insulating film in between.

The electrode layer constructed in this way is one electrode in a single cell, and can be used by controlling the amount of light as a whole in a single cell. The amount of light can also be partially controlled by manufacturing the electrode layer in the form of a horizontal (or vertical) stripe, or in the form of a dot matrix. It is possible to control the amount of light by using a static driving method for each zone.

The aligning agent includes an upper plate aligning agent applied to the upper plate on which the electrode layer is formed and a lower plate aligning agent applied to the lower plate.

In this way, each alignment agent provided on each electrode may or may not be subjected to rubbing treatment.

In the electronic light quantity control device 100 configured as described above, when no voltage is applied to the mixed liquid crystal layer (i.e., electric field non-formation (OFF)), the liquid crystal and dichroic dye contained within the mixed liquid crystal layer are vertically aligned. That is, it exists in a state in which it is arranged in a direction perpendicular to the upper and lower plates (first orientation state).

Accordingly, it is possible to drive white display (light quantity increase mode) by passing most of the light incident on the mixed liquid crystal layer, that is, the liquid crystal light quantity control device, as is.

When voltage is applied to the mixed liquid crystal layer, the liquid crystals, dichroic dye, and chiral dopants present inside the mixed liquid crystal layer are oriented in a specific direction.

To be more specific, the mixed liquid crystal layer reacts to a vertical electric field formed by voltage application and arranges negative (N-type) liquid crystals in a direction perpendicular to the direction of the vertical electric field (hereinafter referred to as 'horizontal alignment operation'). The action occurs.

In this way, when the liquid crystals are horizontally aligned by applying voltage, the dichroic dyes present in the mixed liquid crystal layer along with the liquid crystals are aligned in the same direction in conjunction with the horizontal alignment operation of the liquid crystals.

This is due to the nature of substances in nature, such as dichroic dyes, to always be in the lowest energy state and the interaction caused by the horizontal alignment of liquid crystals.

That is, when the liquid crystals inside the mixed liquid crystal layer are arranged in a direction perpendicular to the electric field direction, the dichroic dye aligned along the liquid crystal direction (perpendicular to the electric field direction) corresponds to the lowest energy state, and in addition, the dichroic dye is aligned along the liquid crystal direction (perpendicular to the electric field direction). During the second alignment operation, an interaction occurs with the dichroic dye adjacent to the liquid crystal, so that the dichroic dye also undergoes an alignment operation in the same direction.

Accordingly, most of the light incident on the mixed liquid crystal layer can be absorbed by the dichroic dye, and in addition, the scattering of the incident light due to the birefringence of the liquid crystal is added, resulting in reduced light intensity or driving a black state display (light intensity reduction mode). There will be.

That is, when an electric field is applied to the mixed liquid crystal layer, a light quantity reduction mode can be driven while transitioning from the first orientation state to the second orientation state, and in this light quantity reduction mode, the liquid crystal is tilted through control of the electric field intensity to produce light. By adjusting the transmittance, the amount of light incident on the image sensor 30 can be controlled in detail.

Meanwhile, when a voltage is applied to the mixed liquid crystal layer of the present invention, the liquid crystals are horizontally aligned and ultimately form a state in which they are aligned in the horizontal direction (second alignment state) forming a twisted structure twisted from the top to the bottom. It is characterized by

This means that when molecular asymmetry due to a chiral dopant is introduced into a nematic liquid crystal having cylindrical symmetry, torsion occurs between adjacent liquid crystal molecules and a torsional arrangement is induced in the arrangement of the liquid crystal molecules.

In addition, during the horizontal alignment operation of the liquid crystal according to the application of an electric field, the chiral dopant causes the rotation of the optical axis of the liquid crystal to occur stably in one direction, and the second alignment state thus achieved can be achieved more stably.

Here, since the double torsion structure induced by the chiral dopant cannot continuously fill the three-dimensional space, filling the three-dimensional space with the double torsion structure may be accompanied by the generation of defects or unstable arrangement, the present invention The liquid crystal light quantity control device can implement a second alignment state with a stable pitch distance depending on the chiral dopant concentration, based on the above-mentioned equation 1 and the concentration range of 0.5% to 15%.

In the end, the light quantity control device of the present invention does not simply orient the liquid crystals horizontally in the second orientation state that reduces the light quantity, but also adjusts the concentration of the chiral dopant and the pitch of the liquid crystals, so that the liquid crystals adopt a stable twisted structure and are horizontal. By configuring it to form an oriented state, it is possible to implement the appropriate transmittance required for the camera module.

Figure 3 is a photograph showing the transmittance state when the liquid crystal light quantity control device manufactured according to an embodiment of the present invention is turned on/off.

As can be seen in the photo, when no voltage is applied, more than 90% of the light can be transmitted, and when voltage is applied, only 60% of the light can be transmitted, allowing the light amount to be adjusted.

In addition, when this is used twice, a transmittance of 80% when voltage is not applied and 40% when voltage is applied can be obtained, which shows that the amount of light can be adjusted.

Figure 4 shows the standard transmittance of 90% and 60%, respectively, as measured in the on/off operating state of the electronic light intensity control device of the camera module manufactured according to an embodiment of the present invention. This is the result of comparing optical characteristics compared to ND-Filter.

In Figure 5, the electronic light intensity control device of the camera module manufactured according to an embodiment of the present invention has a total transmittance of 90% and 60%, and the transmittance when the applied voltage is turned on/off at the R/G/B wavelength is R/G of natural light. /It displays a wavelength similar to the B wavelength, creating a natural image using natural light.

Meanwhile, the electronic light intensity control device can be applied to autonomous vehicles or smart windows.

The camera module of the autonomous vehicle properly detects surrounding objects due to the black hole or white hole phenomenon that appears at the entrance and exit of the tunnel, strong light reflection from windows in the city, or strong glare from backlight, sunset, or low-altitude sun. There are cases where it cannot be done.

Therefore, if the electronic light quantity control device of the present invention is applied to the camera module of an autonomous vehicle, surrounding objects can be clearly detected by reducing the light quantity for such strong light.

Figure 6 shows backlight correction by applying the electronic light amount control device of the present invention to the camera module of an autonomous vehicle. A photo in which surrounding objects cannot be distinguished from the camera image due to backlight is included on the left, and when the electronic light intensity control device of the present invention is applied to the camera module, an image in which surrounding objects can be identified appears as shown on the right. .

In particular, when applying the electronic light quantity control device of the present invention to an autonomous vehicle, the screen can be divided, as shown in FIG. 7, so that the electronic light quantity control device operates only in areas where the light quantity is excessive.

That is, the surface of the electronic light intensity control device of the camera module corresponding to the entire field of view of the vehicle is divided into multiple parts (in this embodiment, it is divided into 9 parts), and electrodes and light sensors are arranged to be on/off for each divided surface, so that a predetermined The light quantity is corrected by turning on the electronic light quantity control device for the division surface where the light quantity abnormality is detected.

With this configuration, the camera module of the autonomous vehicle can secure a stable field of view.

Figure 8 is a photograph showing that the electronic light quantity control device of the present invention is applied to a smart window to control the light quantity.

If the electronic light quantity control device of the present invention is applied to a smart window containing multiple glasses, the light quantity can be appropriately adjusted to prevent strong light from entering the window.

As above, it is obvious that various changes and changes can be made to the embodiments and described terms of the present invention without departing from the technical spirit and scope of the following claims. These modified embodiments should not be understood individually from the spirit and scope of the present invention, but should be regarded as falling within the scope of the claims of the present invention.

10: lens unit 11: lens
12: carrier 20: actuator
30: Filter unit 40: Image sensor
41: signal line 50: printed circuit board
100: Light quantity control device

Claims (11)

An electronic light intensity control device arranged in a camera module,
The electronic light intensity control device,
top;
a lower plate spaced apart from the upper plate at a predetermined interval; and
It includes a mixed liquid crystal layer filled between the upper and lower plates,
The top plate includes a top electrode layer and a top aligner,
The lower plate includes a lower plate electrode layer and a lower plate aligning agent,
The mixed liquid crystal layer includes liquid crystal, dichroic dye, and chiral dopant,
The mixed liquid crystal layer is,
Under conditions that satisfy the following Equations 1 and 2, the chiral dopant is configured to satisfy a concentration within the range of 0.1% by weight to 13% by weight,
[Equation 1]
1/P = H * C
(Where, P: pitch of liquid crystal, H: helical twisting power (HTP) of chiral dopant, C: concentration of chiral dopant (% by weight))

[Equation 2]
T _R = (Δn * d) / λ _R
T _G = (Δn * d) / λ _G
T _B = (Δn * d) / λ _B
(Here, Δn is the refractive index of the liquid crystal, d is the thickness of the liquid crystal layer, and λ uses the wavelengths of R, G, and B.)
The liquid crystal is a negative (N-type) liquid crystal, the electrode layer applies a vertical electric field to the mixed liquid crystal layer, and the mixed liquid crystal layer is driven to increase the transmittance of incident light by forming a first alignment state when no voltage is applied, When voltage is applied, it forms a second orientation state and drives to reduce the transmittance of incident light,
The second alignment state caused by the application of the voltage is a state in which the liquid crystal forms a twisted structure and is arranged in a direction perpendicular to the vertical electric field direction,
The thickness of the mixed liquid crystal layer is 1.5um~15um,
An electronic light intensity control device arranged in a camera module, wherein the transmittance in the first orientation is in the range of 60% to 95%, and the transmittance in the second orientation is in the range of 20% to 60%.

delete delete According to paragraph 1,
An electronic light intensity control device arranged in a camera module, wherein the chiral dopant is configured to have left-handedness or right-handedness, or is composed of a form in which both left-handedness and right-handedness coexist.
According to claim 1,
The dichroic dye is black and is an electronic light intensity control device arranged in a camera module, characterized in that it is a P-type dichroic dye.
According to claim 1, as an anti-reflective coating material to improve transmittance,
SiO ₂ , ZrO ₂ , TiO ₂ , Mg ₂ O, Al ₂ O _3, SiO, SV5, SV7, SV8, SV20, SV10, SV21, SV55, SV71 combined to form an upper plate or lower plate, or an upper plate and a lower plate. An electronic light intensity control device arranged on a camera module, characterized in that it is coated on.
In the camera module,
A camera module comprising the electronic light intensity control device of any one of claims 1, 4, 5, or 6 between the front of the lens unit of the camera module and the image sensor.
In clause 7,
A camera module, wherein the filter located inside the camera module is replaced with the electronic light quantity control device, and the electronic light quantity control device also includes a filter function.
The camera module of claim 7 is a camera module characterized in that it is a camera module included in an autonomous vehicle, a tablet PC, a portable terminal including a smartphone, a toy camera, a drone, a wearable device, a robot, or a 3D printer. . The method of claim 9, wherein the electronic light intensity control device included in the camera module is:
The surface of the electronic light quantity control device corresponding to the entire field of view of the vehicle is divided into multiple parts, and each divided surface includes electrodes and light sensors that can be turned on/off, and electronic light quantity control is performed on the divided surface where more than a certain amount of light is detected. A camera module that corrects the amount of light by turning the device ON. A smart window comprising the electronic light quantity control device according to any one of claims 1 or 4 to 6.