WO2015034217A1 - Optical filter, and imaging device comprising same - Google Patents

Abstract

The present invention provides an optical filter that comprises an optical absorption layer and a near-infrared reflection layer, the optical absorption layer having an absorption maximum in the wavelength range of 670-720nm, the wavelength at which the light transmittance of the near-infrared reflection layer is 50% being in the range of 690-720nm, and the filter satisfying mathematical formula (1). The present invention also provides an imaging device comprising the optical filter. [Mathematical formula (1)] ΔE*≤1.5. In mathematical formula (1) ΔE* represents the colour difference between light that has entered in the vertical direction of the optical filter and passed through the optical filter, and light that has entered in the direction at an angle of 30° to the vertical direction of the optical filter and passed through the optical filter.

Description

Optical filter and imaging device including same

The present invention relates to an optical filter and an imaging device including the same.

An imaging device such as a camera uses a CMOS sensor to convert incident light into an electrical signal to produce an image. The newly developed BSI type (Back Side Illuminated type) CMOS sensor instead of the FSI type (Front Side Illuminated type) CMOS sensor, which has been widely used for realizing high quality images due to the high pixel resolution of the camera. Is the trend for main cameras. In the FSI type CMOS sensor, some light is blocked by forming a wiring on the top of a photodiode (PD). On the other hand, the BSI-type CMOS sensor can receive more incident light than the FSI-type CMOS sensor by placing the wiring under the photodiode so as to receive more light, thereby brightening the image by 70% or more. Thus, in general, cameras of 8 million pixels or more are mostly BSI type CMOS sensors.

Such a BSI type CMOS sensor can be structurally reached to a photodiode having a larger angle of incidence than an FSI type CMOS sensor.

 In general, the CMOS sensor can detect the light intensity in the wavelength region which cannot be seen by the naked eye. The light of the wavelength region causes distortion of the image, and thus looks different in color. To block this, an optical filter is used in front of the CMOS sensor. However, in the conventional optical filter, the transmission spectrum of the optical filter is changed as the angle of incidence of the light is changed, which causes a problem of distortion of the image.

[Preceding technical literature]

(Patent Document 1) Japanese Laid-Open Patent No. 2008-106836

Accordingly, an object of the present invention is to provide an optical filter capable of improving color reproducibility by eliminating color differences according to incident angles of light.

Another object of the present invention is to provide an imaging device including the optical filter.

An optical filter according to an embodiment for realizing the object of the present invention,

An optical filter comprising a light absorbing layer and a near infrared reflecting layer,

The light absorption layer has an absorption maximum in the wavelength range of 670 to 720 nm,

The wavelength at which the light transmittance of the near infrared reflecting layer is 50% is present in the range of 690 to 720 nm,

It may include an optical filter characterized in that to satisfy the following equation (1).

[Equation 1]

ΔE ^* ≤ 1.5

In Equation 1,

ΔE ^* denotes a color difference between light incident in the vertical direction of the optical filter and transmitted through the optical filter and light incident at an angle of 30 ° with the vertical direction of the optical filter and transmitted through the optical filter.

In one embodiment for realizing another object of the present invention, it may include an imaging device comprising a broad filter according to the present invention.

Such an optical filter can prevent a shift phenomenon of the transmission spectrum of the optical filter due to the change in the incident angle of light without impairing the transmittance of the visible light region.

1 is a cross-sectional view showing a laminated structure of an optical filter according to an embodiment of the present invention.

2 and 6 are graphs showing light transmittance spectra of optical filters according to the present invention, respectively, in one embodiment.

7 and 8 are graphs showing light transmittance spectra of an optical filter according to a comparative example, respectively.

9 is a graph showing ΔE ^* according to the absorption maximum wavelength λ of the light absorption layer and the thickness of the light absorption layer of the optical filter according to the embodiment.

Hereinafter, in the present invention, the "incidence angle" means an angle at which light incident on the optical filter is perpendicular to the optical filter. As the number of pixels of the imaging device is increased, the amount of incident light required also increases. Therefore, the recent imaging apparatus needs to accommodate not only light incident in the vertical direction to the optical filter but also light having 30 degrees or more with respect to the angle formed with the vertical direction.

In the present invention, “ΔE ^* ” means light incident in the vertical direction of the optical filter and transmitted through the optical filter, and light incident at an angle of 30 ° with the vertical direction of the optical filter and transmitted through the optical filter. It means color difference.

In general, the light transmitted through the optical filter can be divided into components that are substantially parallel to the incident light and scattered components. In this case, the transmittance of the components substantially parallel to the incident light is called transmittance, and the transmittance of the scattered components is called diffuse transmittance. In general, the transmittance of light is a concept including a transmittance of permeability and diffusion, but in the present invention, the transmittance of light is used as a concept that means only transmittance.

Specifically, ΔE ^* is a concept used in the CIE Lab color space, which is a color value defined by CIE (Commission Internationale de l'Eclairage), and this concept is used in the present invention. The CIE Lab color space is a color coordinate space capable of expressing color differences that can be detected by human eyesight. The distance between two different colors in the CIE Lab color space is designed to be proportional to the color difference perceived by humans.

The color difference in the CIE Lab color space means the distance between two colors in the CIE Lab color space. In other words, the farther the distance, the larger the color difference, and the shorter the distance, the less the color difference. This color difference can be represented by ΔE ^* .

Any position in the CIE color space is represented by three coordinate values: L ^* , a ^* , b ^* . The L ^* value represents the brightness. If L ^* = 0, it represents black, and if L ^* = 100, it represents white. a ^* indicates whether the color with the corresponding color coordinates is pure magenta or pure green, and b ^* indicates that the color with the color coordinates is pure yellow and pure blue ( pure blue).

a * ranges from -a to + a. The maximum value of a ^* (a ^* max) denotes the pure magenta (pure magenta), minimum value (a ^* min) of a ^* indicates a pure green (pure green). For example, if a ^* is negative, the color is pure green, and positive is the color of pure magenta. a ^* = 80 and compared to a ^* = 50, means that a ^* = 80 a ^* = yi than 50 located close to the pure magenta.

b ^* ranges from -b to + b. b ^* max value (b ^* max) represents a pure yellow color (pure yellow), the minimum value b ^* (b ^* min) of the denotes a pure blue (pure blue). For example, a negative b ^* means a pure yellow color and a positive number means a pure blue color. Comparing b ^* = 50 and b ^* = 20, it means that b ^* = 80 is closer to pure yellow than b ^* = 50.

In general, when ΔE ^* is 1.5 or less, color vision is hardly recognized by human eyesight, and when ΔE ^* is 0.5 or less, color difference cannot be recognized by human eyesight. However, if ΔE ^* exceeds 1.5, there is a possibility of recognizing the color difference with human eyesight, and if ΔE ^* is 2.0 or more, the color difference can be clearly recognized with human eyesight. For example, when producing a product in a factory, if the ΔE ^* value is maintained at 0.8 to 1.2, it may mean that the color deviation between products is managed at a level that cannot be recognized by human eyesight.

The color difference ΔE ^{*, which} is an arbitrary color E1 with color coordinates of (L1 ^* , a1 ^* , b1 ^* ) and another arbitrary color E2 with color coordinates of (L2 ^* , a2 ^* , b2 ^* ), is calculated by the following equation a can do.

Equation a

ΔL ^* in Equation a means a difference between L1 ^* and L2 ^* of color coordinates of two arbitrary colors E1 and E2. In addition, Δa ^* means the difference between a1 ^* and a2 ^* in the color coordinates of E1 and E2, and Δb ^* means the difference between b1 ^* and b2 ^* among the color coordinates of E1 and E2.

In the present invention, the "dynamic width of the visible light region" refers to the range of light that the CMOS sensor can faithfully express on the screen. When the light in the infrared region irrelevant to the color expression is transmitted through the optical filter and incident on the CMOS sensor, the dynamic width of the visible light region required for color is reduced. As the dynamic width of the visible light region becomes smaller, the image of the dark portion cannot be distinguished, so that it is difficult to realize an accurate image. Therefore, the optical filter must minimize light transmittance in the infrared region. In addition, noise in CMOS sensors is mainly caused by the circuit structure, especially thermal noise. Since the light in the infrared region passing through the optical filter acts as a major cause for the heat generation of the CMOS sensor, the optical filter should minimize the light transmittance in the infrared region.

The present invention relates to an optical filter, and as an example, an optical filter including a light absorbing layer and a near infrared reflecting layer, the absorption maximum wavelength of the light absorbing layer is present in the wavelength range of 670 to 720 nm, the light transmittance of the near infrared reflecting layer is 50 The wavelength which is% is present in the wavelength range of 690 to 720 nm, and may include an optical filter characterized in that the following Equation 1 is satisfied.

[Equation 1]

ΔE ^* ≤ 1.5

In Equation 1,

ΔE ^* denotes a color difference between light incident in the vertical direction of the optical filter and transmitted through the optical filter and light incident at an angle of 30 ° with the vertical direction of the optical filter and transmitted through the optical filter.

The light absorption layer of the optical filter has an absorption maximum in the wavelength range of 670 to 720 nm. This may be implemented by adjusting the type and content of the light absorbing agent included in the light absorbing layer. In addition, the near infrared reflecting layer of the optical filter has a wavelength of 50% light transmittance within a wavelength range of 690 to 720 nm. This may be implemented by adjusting the thickness and the laminated structure of the dielectric multilayer film forming the near infrared reflecting layer. By controlling the absorption maximum wavelength of the light absorbing layer and the wavelength at which the light transmittance of the near infrared reflecting layer is 50% within the above range, even if the incident angle of light incident on the optical filter is changed, the image is prevented from being discolored. The same level of color reproduction may be possible.

This can be confirmed through Equation 1 above.

Specifically, in Equation 1, ΔE ^* is a color coordinate (L1 ^* , a1 ^* , b1 ^* ) and the optical coordinates of light E1 incident in the vertical direction to the optical filter according to the present invention and transmitted through the optical filter. It means the color difference calculated by substituting the color coordinates L2 ^* , a2 ^* , b2 ^* of the light E2 incident at an angle of 30 ° with the vertical direction of the filter and passing through the optical filter.

As such, when the optical filter is implemented such that the color difference ΔE ^* is 1.5 or less, the human eye cannot perceive the distortion of the color present in the image represented by the display device.

For example, the ΔE ^* may be 0.001 to 1.5, 0.001 to 1.2, 0.001 to 1.0, or 0.001 to 0.8.

In another embodiment, the optical filter has a wavelength in the range of 600 to 750 nm, the transmittance of light incident in the vertical direction is 30% and the transmittance of light incident at an angle of 30 ° with respect to the vertical direction is 30%. The absolute value (ΔT _30% ) of the wavelength difference may be 15 nm or less.

This may mean the transmission of the optical filter for light in the 600 to 750 nm wavelength range. Specifically, it may mean that the absolute value of the wavelength difference at which the transmittance of light incident in the vertical direction with respect to the optical filter and light incident at an angle of 30 ° with respect to the vertical direction is 30% is 15 nm or less. For example, the absolute value of the wavelength difference may be 1 nm to 15 nm, 1 nm to 8 nm, or 1 nm to 5 nm. Through this, the optical filter may prevent the image from discoloring even when the incident angle of the light incident through the lens of the solid-state imaging device is changed, thereby enabling the same level of color reproduction as the image observed with the naked eye. In addition, by controlling the absolute value of the wavelength difference within the range to minimize the color difference can be controlled to a level that can not be recognized by human eyesight.

In another embodiment, the optical filter according to the present invention may have an average transmittance of 80% or more for the visible light region (450 to 600 nm).

When the optical filter is applied to an imaging device, a camera module, or the like, it is preferable that the optical transmittance is high in the visible light region. When the optical filter has an average transmittance of 80% or more in the visible light region, the image represented by the imaging device or the camera module to which the optical filter is applied may be expressed in the same color as the image observed by the naked eye.

In another embodiment, the optical filter according to the present invention may have an average transmittance of 10% or less in the infrared region (750 to 1000 nm).

Specifically, the condition may mean that the transmittance of the optical filter with respect to light in the infrared region is 10% or less. By controlling the transmittance of the optical filter to the light in the infrared region within the above range, it is possible to prevent a reduction in the dynamic range of the visible light region, an increase in noise, a decrease in color reproducibility and resolution.

In another embodiment, the light absorbing layer of the optical filter may include a binder resin and a light absorbing agent dispersed in the binder resin. For example, if the light absorbing agent of the binder resin is easily dispersed, there is no particular limitation, and for example, cyclic olefin resin, polyarylate resin, polysulfone resin, polyethersulfone resin, polyparaphenylene resin At least one of polyarylene ether phosphine oxide resin, polyimide resin, polyetherimide resin, polyamideimide resin, acrylic resin, polycarbonate resin, polyethylene naphthalate resin, and various organic-inorganic hybrid series resins. Can be used.

The light absorbing agent may be used one or more of various kinds of dyes, pigments or metal complex system compounds, it is not particularly limited. For example, the light absorbing agent may be a cyanine compound, a phthalocyanine compound, a naphthalocyanine compound, or a dithiol metal complex system compound.

The said light absorbing agent can be used individually by 1 type, and can mix and use 2 or more types as needed.

The content of the light absorbing agent may be, for example, in a range of 0.001 to 10 parts by weight, 0.01 to 10 parts by weight, or 0.1 to 5 parts by weight based on 100 parts by weight of the binder resin. By adjusting the content of the light absorbing agent in the above range it is possible to correct the shift (shift) phenomenon of the transmission spectrum according to the angle of incidence, and implement an excellent near-infrared blocking effect. In addition, when two or more kinds of the light absorbing agent are used in combination, the absorption wavelength range (half-width) of the light absorption layer may be increased to minimize transmission of light that may occur in the wavelength range of the near infrared region.

In another embodiment, the optical filter may satisfy the following Equation 2.

[Equation 2]

t _abs ≤ 0.13 μm

t _abs means the thickness when the light absorber layer is formed in the same area as the light absorbing layer by using the same amount of light absorbing agent contained in the light absorbing layer.

Specifically, the light absorbing layer of the optical filter includes a binder resin and a light absorbing agent. Here, the thickness t _abs when the light absorber layer is formed using the same amount of the light absorbent contained in the light absorbing layer may mean the concentration or content of the light absorbing agent in the light absorbing layer. When t _abs is 0.13 μm or less, the above-described color difference ΔE ^* may be 0.8 or less. For example, the color difference may range from 0.1 to 0.8, 0.4 to 0.8, or 0.5 to 0.6. As such, by controlling ΔE ^* of the optical filter to 0.8 or less, the human eye cannot perceive the distortion of the color present in the image represented by the display apparatus including the optical filter.

In the optical filter according to the present invention, when the absorption layer has a predetermined absorption maximum wavelength and thickness, the color difference ΔE ^* of the optical filter is changed when the reflection characteristic of the near infrared reflecting layer included in the optical filter is changed. Specifically, when the wavelength W1 of which the transmittance becomes 50% among the characteristics of the near infrared reflecting layer is changed, the color difference ΔE ^* is changed. In this case, optimizing W1 such that ΔE ^* ) has a minimum value can prevent distortion of the image.

The light absorbing layer may have a thickness in the range of 1 to 100 μm. For example, the thickness of the light absorption layer may be in the range of 1 to 10 μm, 3 to 20 μm, or 5 to 30 μm. By adjusting the thickness of the light absorption layer within the above range, ΔE ^* of the optical filter can be effectively controlled within the above range.

In another embodiment, the optical filter may satisfy Equation 3 below.

[Equation 3]

W2-W1 ≤ 20 nm

In Equation 3,

W1 means a wavelength in the wavelength range of 600 to 800 nm, the transmittance of the near-infrared reflecting layer to the light incident in the direction perpendicular to the optical filter is 50%,

W2 means the absorption maximum wavelength of the light absorption layer.

Specifically, in Equation 3, in the wavelength range of 600 to 800 nm, the wavelength W1 at which the transmittance of the near-infrared reflecting layer with respect to light incident in the direction perpendicular to the optical filter is 50% and the light absorbing layer have an absorption maximum. The wavelength, that is, the difference between the wavelengths W2 at which the light absorbing layer has the lowest transmittance may be 20 nm or less. For example, the W2-W1 may be 0 to 20 nm, 5 to 15 nm or 10 to 13 nm. Through the W2-W1 value within the above range, it is possible to prevent the shift phenomenon of the transmission spectrum due to the change of the incident angle, and excellent near-infrared blocking effect can be expected. In addition, by reflecting a part of the light incident to the light absorbing layer by the near-infrared reflecting layer, it is possible to prevent problems such as deterioration of the optical filter or efficiency degradation of the optical filter that may be generated due to the light absorbing layer absorbs excessive amounts of light.

In another embodiment, the optical filter may satisfy Equation 4 below.

[Equation 4]

0 nm ≤ W1- (W2-W3 / 2) ≤ 65 nm

In Equation 4,

W1 means a wavelength in the wavelength range of 600 to 800 nm, the transmittance of the near-infrared reflecting layer with respect to light incident in the direction perpendicular to the optical filter is 50%,

W2 means the absorption maximum wavelength of the light absorption layer,

W3 means the absolute value of the difference between the two wavelengths in which the light absorption layer has a transmittance of 50% in the wavelength range of 600 nm or more.

Specifically, Equation 4 is a wavelength (W1) of the light transmittance of the near-infrared reflecting layer 50% to the light incident in the direction perpendicular to the optical filter in the 600 to 800 nm wavelength range, the light absorbing layer has an absorption maximum The relationship between the wavelength W2 and the full width at half maximum (FWHM) W3 at a wavelength at which the transmittance of the light absorbing layer is 50% can be shown. For example, the W1- (W2-W3 / 2) value may have a range of 1 to 65 nm, 5 to 40, or 10 to 30 nm. Specifically, by adjusting the value of W1- (W2-W3 / 2) within the above range, it is possible to minimize the transmittance of light in the near infrared region. In this case, when the W1- (W2-W3 / 2) value is less than 0 nm, the shift of the transmission spectrum of the optical filter due to the change of the incident angle may not be prevented, and the transmittance of light in the near infrared region may increase, thereby displaying the display. There arises a problem that the user can recognize the distortion of the color present in the image represented by the device.

On the other hand, when the W1- (W2-W3 / 2) value exceeds 65 nm, the formulation stability of the light absorbing layer may be impaired, but rather the distortion of the image by inhibiting the light transmittance in the visible light region contributing to the generation of the image. Can be generated. When Equations 2 to 4 together with Equation 1 are satisfied at the same time, even if the incident angle of the light incident on the optical filter is changed, distortion of the image can be minimized, so that color can be reduced to the same level as the image observed by the naked eye. I can reproduce it. In this case, Equations 1 to 4 control the wavelength representing the absorption maximum of the light absorbing layer in the range of 670 to 720 nm, and the wavelength at which the light transmittance of the near infrared reflecting layer becomes 50% is controlled in the range of 690 to 720 nm. Can be.

In such an optical filter structure, unnecessary transmission peaks may be generated in the wavelength range of the near infrared region (700 to 750 nm) according to the absorption characteristics of the light absorption layer.

As another embodiment of the optical filter according to the present invention for preventing this, Equation 5 may be satisfied.

[Equation 5]

% T _NIR-peak ≤ 10%

In Equation 5,

% T _NIR-peak means the maximum transmittance in the 700 to 750 nm wavelength range.

Specifically, the% T _NIR-peak means the maximum transmittance in the wavelength range of the near infrared region,% T _NIR-peak may be 10% or less. For example, the% T _NIR-peak may be represented by 0.1% to 8%, 1% to 5% or 1% to 2% or less, preferably 0%. As the% T _NIR-peak approaches 0%, the distortion of the image can be reduced.

As a high pixel image pickup device employing a high sensitivity sensor such as a BSI type CMOS sensor has been developed, the transmission spectrum of the optical filter is changed when the incident angle of light incident on the optical filter applied to the image pickup device is changed. Serious distortion occurred in the image provided by the imaging device. In order to prevent such a serious distortion, the transmittance of light incident to the optical filter vertically and transmitted through the optical filter and light incident to the optical filter in a direction perpendicular to the optical filter at 30 ° is 50%. A scheme for controlling the difference in wavelengths has been introduced. However, there is a limit in preventing distortion of the image only by controlling the difference in wavelengths at which the transmittance of light incident at each angle is 50%. That is, at the wavelength at which the transmittance of light incident at each angle becomes 30%, when the incident angle of light is changed, the transmittance of the optical filter is suddenly changed, and there is still a problem that image distortion occurs.

In order to solve the conventional problems as described above, in the optical filter according to the present invention, not only the wavelength at which the transmittance of light incident at the respective incident angles is 50% according to Equations 1 to 5, but also the transmittance of light is 30%. The wavelength was controlled at the same time. Absolute value (ΔT ₃₀₎ of the difference between the light incident perpendicularly to the optical filter and transmitted through the optical filter and the wavelength of light incident on the optical filter in a direction perpendicular to the optical filter at 30 ° and having a transmittance of 30%. _As a result of controlling _% ) to 15 nm or less, the optical filter of the present invention was able to further reduce the distortion of the image than the conventional optical filter.

Hereinafter, the structure of the optical filter according to the present invention will be described in more detail.

The optical filter according to the present invention may include a light absorbing layer and a near infrared reflecting layer including at least one light absorbing agent. Therefore, light in the near infrared region incident on the optical filter is mostly reflected by the near infrared reflecting layer.

In another embodiment, the optical filter may further include a transparent substrate formed on one surface of the light absorption layer. For example, the transparent substrate may be a transparent glass substrate or a transparent resin substrate.

Specifically, a transparent glass substrate may be used as the transparent substrate, and if necessary, a phosphate-based glass containing copper oxide (CuO) may be used. When using glass as a board | substrate, there exists an effect which prevents heat deformation and suppresses curvature at the time of manufacture of a filter, without impairing the transmittance | permeability of visible light.

It is preferable that the said transparent resin substrate is excellent in intensity | strength, For example, the transparent resin which the inorganic filler disperse | distributed can be used. The kind of light transmissive resin is not particularly limited, and a binder resin mentioned as applicable to the light absorbing layer can be used. For example, by controlling the kind of the binder resin of the light absorption layer and the resin used as the transparent substrate, the interface peeling can be reduced.

The near infrared reflecting layer may be formed of a dielectric multilayer. The near infrared reflecting layer serves to reflect light in the near infrared region. For example, the near-infrared reflection layer can use the dielectric multilayer film etc. which alternately laminated the high refractive index layer and the low refractive index layer. The near-infrared reflecting layer may include an aluminum vapor deposition film if necessary; Precious metal thin film; Or a resin film in which at least one fine particle of indium oxide and tin oxide is dispersed.

As one example, the near infrared reflecting layer may have a structure in which a dielectric layer having a first refractive index and a dielectric layer having a second refractive index are alternately stacked. The refractive index difference between the dielectric layer having the first refractive index and the dielectric layer having the second refractive index may be 0.2 or more, 0.3 or more, or 0.2 to 1.0.

For example, the dielectric layer having the first refractive index may be a layer having a relatively high refractive index, and the dielectric layer having the second refractive index may be a layer having a relatively low refractive index. In this case, the refractive index of the dielectric layer having the first refractive index may range from 1.6 to 2.4, and the refractive index of the dielectric layer having the second refractive index may range from 1.3 to 1.6.

The dielectric layer having the first refractive index may be formed of one or more selected from the group consisting of titanium oxide, alumina, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide and indium oxide. . The indium oxide may further contain a small amount of titanium oxide, tin oxide, cerium oxide, and the like as necessary.

The dielectric layer having the second refractive index may be formed of one or more selected from the group consisting of silica, lanthanum fluoride, magnesium fluoride, and sodium alumina fluoride.

The method for forming the near infrared reflecting layer is not particularly limited, and for example, a CVD method, a sputtering method, a vacuum deposition method, or the like may be applied.

The near-infrared reflective layer may have a structure in which a dielectric layer having a first refractive index and a dielectric layer having a second refractive index are alternately stacked into 5 to 61 layers, 11 to 51 layers, or 21 to 41 layers. The near-infrared reflecting layer can be designed in consideration of a range of desired transmittance to refractive index and a region of a wavelength to be blocked.

The near-infrared reflective layer may further include a light absorbing agent dispersed in the dielectric multilayer. For example, the light absorbing agent dispersed in the dielectric multilayer film is not particularly limited as long as it is a light absorbing agent capable of absorbing a near infrared to infrared wavelength region of 500 nm or more. By dispersing the light absorbing agent in the dielectric multilayer film, the number of alternating stacks of the dielectric multilayer film can be reduced, and the thickness of the near infrared reflecting layer can be reduced. In this way, when applied to the imaging apparatus, it is possible to realize miniaturization of the imaging apparatus.

In an embodiment, when the dielectric multilayer film further includes a light absorbing agent, the thickness of the dielectric multilayer film may be manufactured to be thinner, thereby miniaturizing the device.

The present invention may include an imaging device including the optical filter according to the present invention. The optical filter according to the present invention is also applicable to display devices such as PDPs. However, the present invention is more preferably applicable to an imaging device that requires a high pixel, for example, a camera of 8 million pixels or more. For example, the optical filter according to the present invention can be effectively applied to a camera for a mobile device.

Hereinafter, the optical filter of the novel structure according to the present invention will be described in detail through specific embodiments of the present invention. The embodiments exemplified below are only for the detailed description of the present invention, and are not intended to limit the scope of the rights.

Preparation Example 1

On one surface of the glass substrate, TiO ₂ and SiO ₂ were alternately deposited using an E-beam evaporator to form a near-infrared reflective layer to have a thickness of 4.210 μm.

Separately, commercially available light absorbers with a maximum absorption of 670 nm, cyclic olefin resins and toluene (manufactured by Sigma Aldrich), which are binder resin raw materials, are mixed and stirred for at least one day using a magnetic stirrer to prepare a near-infrared absorbing solution. It was.

Thereafter, the prepared near-infrared absorbing solution was spin coated on the opposite surface of the glass substrate on which the near-infrared reflective layer was formed to form a light absorbing layer.

Through the above process, an optical filter according to the present invention was prepared. The laminated structure of the manufactured optical filter is shown in FIG. Referring to FIG. 1, a near infrared reflecting layer 20 is formed on a lower surface of the glass substrate 10, and a light absorption layer 30 is formed on an upper surface of the glass substrate 10.

For the optical filter manufactured in Preparation Example 1, the light transmittance experiment was performed by varying the angle of incidence of light to (a) 0 ° and (b) 30 °. The results are shown in FIG.

Preparation Example 2

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near infrared reflecting layer was changed to 4.238 μm. In addition, the optical transmittance measurement experiment was performed by changing the incident angle of light to (a) 0 ° and (b) 30 ° with respect to the optical filter prepared in Preparation Example 2. The results are shown in FIG.

Preparation Example 3

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near-infrared reflection layer was changed to 4.269 μm, and the incidence angles of light with respect to the optical filter prepared in Preparation Example 3 were (a) 0 ° and (b) 30. Light transmission measurement experiments were performed at different degrees. The results are shown in FIG.

Preparation Example 4

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near infrared reflecting layer was changed to 4.299 μm. In addition, the optical transmittance measurement experiment was performed by varying the angle of incidence of light to (a) 0 ° and (b) 30 ° with respect to the optical filter prepared in Preparation Example 4. The results are shown in FIG.

Preparation Example 5

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near infrared reflecting layer was changed to 4.331 μm. In addition, the optical transmittance measurement experiment was performed by varying the angle of incidence of light to (a) 0 ° and (b) 30 ° with respect to the optical filter prepared in Preparation Example 5. The results are shown in FIG.

Preparation Example 6

Prepared in the same manner as in Preparation Example 1, but commercially available and the optical filter was prepared by differently using a light absorber having an absorption maximum wavelength of 700 nm.

Comparative Example 1

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near infrared reflecting layer was changed to 4.073 μm. In addition, the optical transmittance measurement experiment was performed by varying the angle of incidence of light to (a) 0 ° and (b) 30 ° with respect to the optical filter prepared in Comparative Example 1. The results are shown in FIG.

Comparative Example 2

An optical filter was manufactured in the same manner as in Preparation Example 1, except that the thickness of the near infrared reflecting layer was changed to 4.110 μm. In addition, the optical transmittance measurement experiment was performed by varying the angle of incidence of light to (a) 0 ° and (b) 30 ° with respect to the optical filter prepared in Comparative Example 2. The results are shown in FIG.

Experimental Example 1

With respect to the optical filters prepared in Preparation Examples 1 to 5 and Comparative Examples 1 and 2, in the 600 to 750 nm wavelength region, the wavelength at which the transmittance of light incident in the vertical direction to the optical filter is 30%, and the optical filter The absolute value (ΔT _30% ) of the difference between the wavelengths of the transmittance of 30% of the incident light in the direction perpendicular to the direction of 30 ° was measured.

The results can be confirmed through Table 1 below.

Table 1

No.	ΔT 30% (nm)
Preparation Example 1	6.6
Preparation Example 2	3.0
Preparation Example 3	1.2
Preparation Example 4	1.0
Preparation Example 5	0.9
Comparative Example 1	18.7
Comparative Example 2	17.2

Through the Table 1, the optical filter according to the present invention has a wavelength of 600% in the wavelength range of 600 to 750 nm, the transmittance of light incident in the direction perpendicular to the optical filter is 30%, perpendicular to the optical filter and 30 ° It can be seen that the absolute value of the difference between the wavelengths of the transmittance of 30% for light incident in the angular direction is 15 nm or less.

Experimental Example 2

Manufactured in the same manner as in Preparation Example 1, an optical maximum wavelength was prepared by varying the absorption maximum wavelength (λ) of the light absorption layer and the thickness of the light absorption layer as shown in Table 2 below. In addition, ΔE ^* was measured for each optical filter and shown in Table 2 and FIG. 9. In FIG. 9, the horizontal axis represents wavelength W1 at which the transmittance of the near infrared reflecting layer is 50%, and the vertical axis represents ΔE ^* . Each graph in Fig. 9 shows ΔE ^* when the wavelength W1 at which the transmittance of the near-infrared reflecting layer is 50% is different when the light absorption layer has a predetermined absorption maximum wavelength λ and thickness.

Specifically, in the case where white light is irradiated perpendicularly (incident angle 0 °) to the manufactured optical filter and when irradiated at an angle of 30 ° with the vertical direction, the color coordinates L ^* , a of each light transmitted through the optical filter ^* And b ^* values were measured using a spectrophotometer Lambda 35 from Perkin Elmer and then ΔE ^* was calculated.

At this time, by varying the number of alternating stacks of TiO ₂ and SiO ₂ forming the near infrared reflecting layer, the wavelength W1 at which the transmittance of the near infrared reflecting layer was 50% was adjusted to be in the range of 650 to 750 nm.

TABLE 2

λ (nm)	Thickness (㎛)	W1 (nm)
		650	660	670	680	690	700	710	720	730	740	750
670	4	7.5	4.1	1.7	0.8	0.5	0.6	0.9	1.3	1.8	2.7	4.2
670	5	7.1	3.8	1.6	0.8	0.5	0.6	0.9	1.3	1.8	2.7	4.1
680	6	7.8	4.4	1.9	0.8	0.6	0.8	1.0	1.3	1.8	2.7	4.1
680	7	7.5	4.2	1.8	0.8	0.6	0.8	1.0	1.3	1.8	2.7	4.1
680	8	7.2	4.0	1.7	0.8	0.6	0.7	1.0	1.3	1.8	2.7	4.1
680	9	6.9	3.8	1.7	0.8	0.6	0.7	0.9	1.3	1.7	2.7	4.1
690	10	7.5	4.4	2.1	0.8	0.6	0.8	1.0	1.3	1.7	2.6	4.0
690	11	7.3	4.3	2.0	0.8	0.6	0.7	1.0	1.3	1.7	2.6	4.0
690	12	7.1	4.2	1.9	0.8	0.6	0.7	1.0	1.3	1.7	2.6	3.9
690	13	7.0	4.1	1.9	0.8	0.6	0.7	1.0	1.3	1.7	2.6	3.9
700	15	7.5	4.5	2.3	1.1	0.5	0.6	0.9	1.2	1.6	2.5	3.8
700	16	7.4	4.4	2.3	1.1	0.5	0.6	0.9	1.2	1.6	2.5	3.7
700	17	7.2	4.4	2.2	1.1	0.5	0.6	0.8	1.2	1.6	2.4	3.7
700	18	7.1	4.3	2.2	1.1	0.5	0.6	0.8	1.2	1.6	2.4	3.7
710	19	8.2	5.0	2.8	1.5	0.7	0.5	0.7	1.0	1.5	2.3	3.6
710	20	8.1	5.0	2.7	1.5	0.7	0.5	0.7	1.0	1.4	2.3	3.5
710	21	8.1	4.9	2.7	1.5	0.8	0.5	0.6	1.0	1.4	2.3	3.5
710	22	8.0	4.9	2.7	1.5	0.8	0.5	0.6	0.9	1.4	2.2	3.5
710	23	7.9	4.8	2.7	1.5	0.8	0.5	0.6	0.9	1.4	2.2	3.4
710	24	7.9	4.8	2.7	1.6	0.8	0.6	0.6	0.9	1.4	2.2	3.4
710	25	7.8	4.8	2.7	1.6	0.9	0.6	0.6	0.9	1.4	2.2	3.4
720	27	9.3	5.9	3.5	2.2	1.4	1.0	0.8	0.8	1.2	2.0	3.2
720	28	9.3	5.9	3.5	2.2	1.4	1.0	0.8	0.9	1.2	2.0	3.2
720	29	9.3	5.9	3.5	2.3	1.5	1.0	0.9	0.9	1.2	2.0	3.2
720	30	9.2	5.9	3.5	2.3	1.5	1.1	0.9	0.9	1.2	2.0	3.2
720	31	9.2	5.9	3.5	2.3	1.6	1.1	0.9	1.0	1.2	2.0	3.1
720	32	9.2	5.9	3.6	2.4	1.6	1.2	1.0	1.0	1.3	2.0	3.1
720	33	9.2	5.9	3.6	2.4	1.7	1.2	1.0	1.0	1.3	2.0	3.1
720	34	9.2	5.9	3.6	2.5	1.7	1.3	1.1	1.1	1.3	2.0	3.1
720	35	9.2	5.9	3.6	2.5	1.7	1.3	1.1	1.1	1.3	2.0	3.1
720	36	9.2	5.9	3.6	2.5	1.8	1.4	1.2	1.2	1.4	2.0	3.1
720	37	9.2	5.9	3.7	2.6	1.8	1.4	1.2	1.2	1.4	2.0	3.1
720	38	9.2	5.9	3.7	2.6	1.9	1.5	1.3	1.2	1.4	2.0	3.0
720	39	9.1	5.9	3.7	2.6	1.9	1.5	1.3	1.3	1.5	2.0	3.0
720	40	9.1	5.9	3.7	2.7	2.0	1.6	1.4	1.3	1.5	2.0	3.0
720	41	9.1	5.9	3.8	2.7	2.0	1.6	1.4	1.4	1.5	2.0	3.0
720	42	9.1	5.9	3.8	2.7	2.1	1.7	1.5	1.4	1.6	2.0	3.0
720	43	9.1	5.9	3.8	2.8	2.1	1.7	1.5	1.5	1.6	2.1	3.0

Table 2 and FIG. 9 show ΔE ^* when the absorption maximum wavelength (W1) of the light absorption layer is different when the light absorption layer has a predetermined absorption maximum wavelength (λ) and thickness. according to the optical filter when the absorption maximum wavelength of the light absorbing layer exists in the 670 to 720 nm range, and the wavelength (W1) is transmittance of the near-infrared reflection layer is 50% is present in 690 to 720 nm range, the light absorption layer ΔE ^* is 1.5 It confirmed that it appeared below. As a result, even if the incident angle is changed from 0 ° to 30 ° it was confirmed that the difference in color is so low that it is not recognized by the naked eye.

On the other hand, when the absorption maximum wavelength of the light absorption layer is 670 to 710 nm, when the absorption maximum wavelength (W1) of the light absorption layer is 690 to 710 nm, ΔE ^* can be adjusted to 0.8 or less, and as a result, color difference is visually recognized. When ΔE ^* has a value of 0.8 or less, for example, a value of 0.478 to 0.572, t _abs (the same amount of light absorbing agent as the light absorbing agent contained in the light absorbing layer) was confirmed. The thickness in the case of forming the light absorber layer in the same area as the light absorbing layer using the same) was confirmed to have the values shown in Table 3.

TABLE 3

ΔE *	t abs (μm)
0.478	0.020
0.493	0.025
0.567	0.030
0.573	0.035
0.575	0.040
0.573	0.045
0.550	0.050
0.551	0.055
0.551	0.060
0.551	0.065
0.502	0.075
0.505	0.080
0.508	0.085
0.511	0.090
0.511	0.095
0.517	0.100
0.525	0.105
0.534	0.110
0.545	0.115
0.558	0.120
0.572	0.125

Experimental Example 3

With respect to the optical filters prepared in Preparation Examples 1 and 6, the light having a transmittance of 30% for light incident in a direction perpendicular to the optical filter, and light incident in a direction forming an angle of 30 ° with the direction perpendicular to the optical filter The absolute value (ΔT _30% ) of the difference in wavelengths for which the transmittance of the resin becomes 30% was measured.

In addition, W1, W2, and W3 were measured to calculate W2-W1 described in Equation 2 and W1- (W2-W3 / 2) described in Equation 3 above.

At this time, by varying the number of alternating stacks of TiO ₂ and SiO ₂ forming the near infrared reflecting layer, the wavelength (W1) that the transmittance of the near infrared reflecting layer is 50% was adjusted to exist within the range of 650 to 750 nm.

In addition, the thickness of the light absorption layer was measured to be different from 7, 11 and 15 μm, and the results are shown in Tables 4 to 6 below.

 (3-1) Absorption layer thickness of 7 µm (W3 = 57 nm)

Table 4

W1 (nm)	Preparation Example 1			Preparation Example 6
	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)
650	19	30	-2	21	50	-22
660	17	21	8	21	41	-12
670	10	10	19	20	30	-One
680	4	0	28	17	20	8
690	One	-10	39	11	10	19
700	One	-20	49	4	0	29
710	One	-30	58	One	-10	38
720	One	-40	69	One	-20	49
730	One	-50	78	One	-30	58
740	One	-60	89	One	-40	69
750	One	-70	98	One	-50	78

Referring to Table 4, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 670 to 750 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT _{30% in} the range 690-750 nm The value was found to be less than 10 nm. In addition, the optical filter of Preparation Example 1 has a wavelength of 670 to 750 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 680 to 750 nm in which the transmittance of the near infrared reflecting layer is 50%. The W2-W1 value was found to be less than 20 nm. In addition, the optical filter of Preparation Example 1 has a wavelength of 680 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 700 to 730 nm in which the transmittance of the near infrared reflecting layer is 50%. It was shown that the value of W1- (W2-W3 / 2) in the range had a range from 20 to 65 nm.

(3-2) Absorption Layer Thickness of 11 μm (W3 = 71 nm)

Table 5

W1 (nm)	Preparation Example 1			Preparation Example 6
	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)
650	18	30	5	20	50	-15
660	13	21	15	18	41	-5
670	6	10	25	14	30	5
680	One	0	35	6	20	15
690	One	-10	46	2	10	26
700	One	-20	55	One	0	35
710	One	-30	65	One	-10	45
720	One	-40	76	One	-20	56
730	One	-50	85	One	-30	65
740	One	-60	96	One	-40	76
750	One	-70	105	One	-50	85

Referring to Table 5, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 660 to 750 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT _{30% in} the range of 680 to 750 nm. The value was found to be less than 10 nm. In addition, the optical filter of Preparation Example 1 has a wavelength of 670 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 690 to 730 nm in which the transmittance of the near infrared reflecting layer is 50%. It was shown that the value of W1- (W2-W3 / 2) in the range had a range from 20 nm to 65 nm.

(3-3) Formation of Absorption Layer at 15 µm (W3 = 83 nm)

Table 6

W1 (nm)	Preparation Example 1			Preparation Example 6
	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)	ΔT 30% (nm)	W2-W1 (nm)	W1- (W2-W3 / 2) (nm)
650	16	30	12	20	50	-8
660	9	21	21	20	41	One
670	3	10	32	16	30	12
680	One	0	41	10	20	21
690	One	-10	52	3	10	32
700	One	-20	62	One	0	42
710	One	-30	71	One	-10	51
720	One	-40	82	One	-20	62
730	One	-50	91	One	-30	71
740	One	-60	102	One	-40	82
750	One	-70	112	One	-50	92

Referring to Table 6, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 660 to 700 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT _30% in the 680 to 720 nm range The numerical value was found to be 10 nm or less, and the value of W1- (W2-W3 / 2) was found to range from 20 nm to 65 nm.

Experimental Example 4

With respect to the optical filters prepared in Preparation Examples 1 and 6, the light having a transmittance of 30% for light incident in a direction perpendicular to the optical filter, and light incident in a direction forming an angle of 30 ° with the direction perpendicular to the optical filter Absolute values (ΔT _30% ) and% T _NIR-peak values of the wavelength difference between which the transmittance was about 30% were measured.

At this time, by varying the number of alternating stacks of TiO ₂ and SiO ₂ forming the near infrared reflecting layer, the wavelength W1 at which the transmittance of the near infrared reflecting layer was 50% was adjusted to be in the range of 650 to 750 nm.

In addition, the thickness of the light absorbing layer was measured to be different from 7, 11 and 15 μm, and the results are shown in Tables 7 to 9 below.

(4-1) Absorption layer thickness of 7 μm (W3 = 57 nm)

TABLE 7

W1 (nm)	Preparation Example 1		Preparation Example 6
	ΔT 30% (nm)	% T NIR-peak (%)	ΔT 30% (nm)	% T NIR-peak (%)
650	19	One	21	0
660	17	One	21	0
670	10	One	20	One
680	4	One	17	0
690	One	5	11	One
700	One	21	4	2
710	One	50	One	5
720	One	76	One	21
730	One	87	One	49
740	One	92	One	76
750	One	95	One	87

Referring to Table 7, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 670 to 750 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT _30% in the 700 to 750 nm range The value was found to be less than 10 nm. Further, the optical filter of Preparation Example 1 has a wavelength of 650 to 690 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 650 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%. The% T _NIR-peak value was found to be less than 10% in the range.

Further, the optical filter of Preparation Example 1 has a wavelength of 670 to 690 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 700 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%. In the range of ΔT _30% The numerical value was below 10 nm and% T _NIR-peak value was below 10%.

(4-2) Absorption layer thickness of 11 μm (W3 = 71 nm)

Table 8

W1 (nm)	Preparation Example 1		Preparation Example 6
	ΔT 30% (nm)	% T NIR-peak (%)	ΔT 30% (nm)	% T NIR-peak (%)
650	18	One	20	0
660	13	One	18	0
670	6	One	14	One
680	One	2	6	0
690	One	8	2	One
700	One	34	One	One
710	One	68	One	3
720	One	84	One	13
730	One	91	One	39
740	One	93	One	68
750	One	94	One	84

Referring to Table 8, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 670 to 750 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT _{30% in} the range of 680 to 750 nm. The value was found to be less than 10 nm. Further, the optical filter of Preparation Example 1 has a wavelength of 650 to 690 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 650 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%. The% T _NIR-peak value was found to be less than 10% in the range.

In addition, the optical filter of Preparation Example 1 has a wavelength of 670 to 690 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 680 to 710 nm in which the transmittance of the near infrared reflecting layer is 50%. In the range of ΔT _30% The numerical value was below 10 nm and% T _NIR-peak value was below 10%.

(4-3) Formation of Absorption Layer Thickness of 15 µm (W3 = 83 nm)

Table 9

W1 (nm)	Preparation Example 1		Preparation Example 6
	ΔT 30% (nm)	% T NIR-peak (%)	ΔT 30% (nm)	% T NIR-peak (%)
650	16	0	20	0
660	9	One	20	0
670	3	One	16	One
680	One	One	10	0
690	One	2	3	One
700	One	9	One	One
710	One	32	One	2
720	One	63	One	10
730	One	80	One	32
740	One	89	One	63
750	One	93	One	80

Referring to Table 9, the optical filter of Preparation Example 1 has a wavelength at which the transmittance of the near infrared reflecting layer is 50% in the range of 660 to 700 nm, and the optical filter of Preparation Example 6 has a wavelength at which the transmittance of the near infrared reflecting layer is 50%. ΔT in the 680 to 720 nm range_30%of The value was found to be less than 10 nm. Further, the optical filter of Preparation Example 1 has a wavelength of 650 to 700 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 650 to 720 nm in which the transmittance of the near infrared reflecting layer is 50%. % T in range_NIR-peakThe value was found to be less than 10%.

Further, the optical filter of Preparation Example 1 has a wavelength of 660 to 700 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 680 to 720 nm in which the transmittance of the near infrared reflecting layer is 50%. In the range of ΔT _30% The numerical value was below 10 nm and% T _NIR-peak value was below 10%.

Experimental Example 6

With respect to the optical filters prepared in Preparation Examples 1 and 6, the light having a transmittance of 30% for light incident in a direction perpendicular to the optical filter, and light incident in a direction forming an angle of 30 ° with the direction perpendicular to the optical filter Absolute values (ΔT _30% ) and% T _NIR-peak values of the wavelength difference between which the transmittance was about 30% were measured.

In addition, in the case where white light is irradiated perpendicularly (incidence angle 0 °) with respect to the manufactured optical filter, and when irradiated at an angle of 30 ° with the vertical direction, the color coordinates L ^* , a ^* and The b ^* value was measured using a spectrophotometer Lambda 35 from Perkin Elmer and then ΔE ^* was calculated.

At this time, by varying the number of alternating stacks of TiO ₂ and SiO ₂ forming the near infrared reflecting layer, the wavelength (W1) of 50% transmittance of the near infrared reflecting layer was adjusted in the range of 650 to 750 nm, and the thickness of the light absorbing layer was 15 μm. It was measured by forming (W3 = 83 nm). The results are shown in Table 9 below.

Table 10

W1 (nm)	Preparation Example 1			Preparation Example 6
	ΔT 30% (nm)	% T NIR-peak (%)	ΔE *	ΔT 30% (nm)	% T NIR-peak (%)	ΔE *
650	16	0	5.6	20	0	7.4
660	9	One	3.0	20	0	4.5
670	3	One	1.4	16	One	2.3
680	One	One	0.8	10	0	1.0
690	One	2	0.6	3	One	0.5
700	One	9	0.7	One	One	0.6
710	One	32	0.9	One	2	0.9
720	One	63	1.2	One	10	1.2
730	One	80	1.7	One	32	1.6
740	One	89	2.4	One	63	2.4
750	One	93	3.8	One	80	3.6

Referring to Table 10, ΔT _30% and% T _NIR-peak values are the same as in Experimental Example (5-3). In addition, the optical filter of Preparation Example 1 has a wavelength of 670 to 720 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 680 to 720 nm in which the transmittance of the near infrared reflecting layer is 50%. ΔE ^* values in the range were found to be 1.5 or less.

Further, the optical filter of Preparation Example 1 has a wavelength of 670 to 700 nm in which the transmittance of the near infrared reflecting layer is 50%, and the optical filter of Preparation Example 6 has a wavelength of 680 to 720 nm in which the transmittance of the near infrared reflecting layer is 50%. In the range of ΔT _30% ,% T _NIR-peak and ΔE ^* It was confirmed that the numerical value appeared within the range according to the present invention.

Claims (13)

1. An optical filter comprising a light absorbing layer and a near infrared reflecting layer,

   The light absorption layer has an absorption maximum in the wavelength range of 670 to 720 nm,

   The wavelength at which the light transmittance of the near infrared reflecting layer becomes 50% is present in the range of 690 to 720 nm.

   An optical filter, which satisfies Equation 1 below:

   [Equation 1]

   ΔE ^* ≤ 1.5

   In Equation 1,

   ΔE ^* denotes a color difference between light incident in the vertical direction of the optical filter and transmitted through the optical filter and light incident at an angle of 30 ° with the vertical direction of the optical filter and transmitted through the optical filter.
2. The method of claim 1,

   In the 600 to 750 nm wavelength range, the absolute value (ΔT _30%) of the difference between the wavelength at which the transmittance of light incident in the vertical direction is 30% and the wavelength at which the transmittance of light incident at 30 ° with respect to the vertical direction is _30%. ) Is 15 nm or less.
3. The method of claim 1,

   The light absorption layer is a binder resin; And a light absorbing agent dispersed in the binder resin.
4. The method of claim 3, wherein

   An optical filter characterized by satisfying Equation 2 below:

   [Equation 2]

   t _abs ≤ 0.13 μm

   In Equation 2,

   The t _abs means a thickness when the light absorber layer is formed in the same area as the light absorbing layer by using the same amount of the light absorbing agent contained in the light absorbing layer.
5. The method of claim 1,

   The thickness of the light absorption layer is an optical filter, characterized in that 1 to 100 ㎛.
6. The method of claim 1,

   An optical filter satisfying Equation 3 below:

   [Equation 3]

   W2-W1 ≤ 20 nm

   In Equation 3,

   W1 refers to a wavelength in which the transmittance of the near infrared reflecting layer is 50% with respect to light incident in a direction perpendicular to the optical filter in a wavelength range of 600 to 800 nm,

   W2 means the absorption maximum wavelength of the light absorption layer.
7. The method of claim 1,

   An optical filter satisfying Equation 4 below:

   [Equation 4]

   W1- (W2-W3 / 2) ≤ 65 nm

   In Equation 4,

   W1 refers to a wavelength in which the transmittance of the near infrared reflecting layer is 50% with respect to light incident in a direction perpendicular to the optical filter in a wavelength range of 600 to 800 nm,

   W2 means the absorption maximum wavelength of the light absorption layer,

   W3 means the absolute value of the difference between two wavelengths in which the light absorption layer has a transmittance of 50% in a wavelength range of 600 nm or more.
8. The method of claim 1,

   An optical filter satisfying Equation 5 below:

   [Equation 5]

   % T _NIR-peak ≤ 10%

   In Equation 5,

   % T _NIR-peak means the maximum transmittance in the 700 to 750 nm wavelength range.
9. The method of claim 1,

   The optical filter further comprises a transparent substrate formed on one surface of the light absorption layer.
10. The method of claim 9,

    The transparent substrate is an optical filter comprising a transparent glass substrate or a transparent resin substrate.
11. The method of claim 1,

    The near-infrared reflecting layer is formed of a dielectric multilayer film.
12. The method of claim 11,

    The near-infrared reflecting layer further comprises a light absorbing agent dispersed in the dielectric multilayer.
13. An imaging device comprising the optical filter according to any one of claims 1 to 12.

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