KR100905269B1 - Image sensor with infrared ray correction - Google Patents

Abstract

An image sensor having an infrared correction function is provided to switch the general photographing and infrared photographing electronically without a motor for attaching/detaching an IR(Infrared Ray) cut-off filter to/from the image sensor. R, G and B cells(100) have the spectral sensitivity corresponding to respectively different colors and correspond to each pixel which is arranged on the same plane in the check pattern form. An IR cell(200) has the spectral sensitivity corresponding to the infrared light, and is arranged vertically to the surface of the R, G and B cells. A color corrector detects R, G and B values photographed by a photographing unit, and then corrects the detected R, G and B value based on the IR value.

Description

Image sensor with infrared ray correction

The present invention relates to an image sensor that can be used without an IR (infrared ray) cut-off filter used in a camera module, and can be taken in low light, so that the IR cut-off filter can be removed and mounted during low-light shooting in a surveillance camera. It eliminates the use of a motor for the purpose of lowering the price of the product and making it possible to shoot low-light infrared light, which was impossible with a small camera.

Recently, portable devices (eg, digital cameras, mobile communication terminals, etc.) equipped with image sensors have been developed and sold. The image sensor is configured as an array of small photosensitive diodes called pixels or photosites. The pixels themselves usually do not extract color from the light and convert photons from the broad spectral band into electrons. Thus, in order to record color images with a single sensor, the sensor is filtered so that different pixels receive different color illumination. This type of sensor is known as a color filter array or color filter array (CFA), where each different color filter is arranged in a predefined pattern across the sensor.

The color filter array (CFA) includes a primary color filter set having transmitted light of red (R), green (G), and blue (B), or a complementary filter of cyan (Cy), magenta (Mg), and yellow (Ye). There is a set. These color filters are based on an organic material, for example, are formed by coloring them, and transmit visible light of a corresponding color, respectively, but also transmit infrared light on the material. The transmittance of the color filter of each color shows intrinsic spectral characteristics in accordance with the respective coloring in the visible light region, but shows almost common spectral characteristics in the infrared light region.

On the other hand, the photosite constituting the image sensor has a sensitivity up to the near-infrared region of the long wavelength, in addition to the visible region in the wavelength range of about 380 to 780 nm. Therefore, when the infrared component (IR component) enters the light receiving pixel, the infrared component passes through the color filter to generate signal charges at the photosite.

1 is a graph showing the spectral sensitivity characteristics of each RGB light-receiving pixel in which respective RGB filters are disposed. At this time, the x axis represents the wavelength (nm), the y axis represents the transparency (%).

As shown in FIG. 1, since each of the light receiving pixels 10, 20, 30 is also sensitive to the infrared (IR) component 40, it is accurate to incident light including the infrared ray component 40. The problem of not being able to express colors occurs. That is, in the case of the B (Blue) component 10, the signal charge 12 according to the IR component 40 is generated in the 850 nm wavelength band in addition to the 450 nm wavelength band, and in the G (Green) component 20 in the 850 nm wavelength band in addition to the 550 nm wavelength band. It can be seen that the signal charge 22 occurs in accordance with the IR component 40. In addition, in the case of the R (Red) component 30, it can be seen that the signal charge 32 is generated according to the IR component 40 in the 950 nm wavelength band in addition to the 850 nm wavelength band.

For this reason, image sensors typically have a separate IR cut-off filter between the lens and the color filter that can block infrared light.

However, the IR cut-off filter cuts infrared light and attenuates visible light by about 10 to 20%. As a result, the intensity of visible light incident on the light receiving pixel is reduced, and accordingly, the S / N ratio (signal-to-noise ratio) of the output signal decreases, resulting in a problem of deterioration of image quality. In addition, in small portable cameras such as mobile communication terminals, there is no space for removing or mounting the IR cut-off filter and it cannot be applied due to the price burden, and the camera implemented without the IR cut-off filter can be used during the day. In this case, there is a problem that a normal camera function cannot be performed due to color inversion.

In order to cope with this problem, the IR cut-off filter is eliminated, and in addition to a light receiving pixel (color light receiving pixel) in which a color filter that transmits light components of a specific color such as R, G, and B is disposed, An infrared light filter (IR filter) which transmits only an IR component is disposed, and a solid-state imaging device having a light receiving pixel (infrared light receiving pixel) that basically detects only an IR component has been proposed.

The signal output by the infrared light receiving pixel becomes a reference signal for giving information on the signal amount generated due to the IR component in each light receiving pixel. Using this reference signal, color signal processing for removing the influence of the IR component included in each color signal output from the color light receiving pixel can be performed.

FIG. 2 is a schematic plan view showing an image sensor having a configuration of a color filter array having a conventional Bayer arrangement, and FIG. 3 is a schematic view showing an image sensor having an IR filter without the IR cut-off filter in FIG. Top view.

As shown in FIG. 3, the color filter array improved to solve the problem of FIG. 2 is an iteration unit of a filter array of 2 × 2 pixels in a Bayer array, and one side of a G filter disposed at two pixels in a diagonal direction is IR (Infrared). Ray) filter has a substitution configuration.

However, using the conventional filter array shown in Fig. 3, the G pixels in the repeating unit of the filter array of 2x2 pixels are composed of only one pixel. That is, when the G pixel is composed of two pixels as in the Bayer arrangement shown in Fig. 2, and the IR filter is configured in one pixel as shown in Fig. 3, the configuration of the G pixel is reduced to one pixel.

In this way, as the G pixel is reduced by the configuration of the IR filter, the resolution of the image signal obtained from the solid-state imaging device equipped with the color filter array is obtained, while the cost and space can be easily obtained by removing the IR cut-off filter. There is an additional problem of degradation.

Accordingly, the present invention has been made to solve the above problems, and the resolution and the resolution of the image signal obtained from the solid-state image pickup device equipped with a color filter array with the ease of cost and space through the removal of the IR cut-off filter It is an object of the present invention to provide an image sensor having an infrared correction function having an array of color filters capable of improving the sensitivity.

Another object of the present invention is to avoid the use of the IR cut-off filter used in the camera module, and also to use the motor for removing and mounting the IR cut-off filter in the camera module capable of infrared imaging in low light To provide an image sensor that can lower the price of.

Another object of the present invention is to provide an easy price and space by removing the IR cut-off filter, and to suppress the occurrence of color reversal even during the day to be applicable to a small portable camera such as a mobile communication terminal An image sensor having an infrared correction function is provided.

It is still another object of the present invention to provide an image sensor that can be configured as an on-chip by integrating a proximity sensor and an illumination sensor together without using an IR cut-off filter.

Still another object of the present invention is to use a two-band filter to exclude only the wavelength range where the sensitivity of the R, G, B cells and IR cells are different, and to correct only the wavelength range where the sensitivity is almost the same. An image sensor is provided.

A feature of an image sensor with an infrared correction function applicable according to the present invention for achieving the above object is that in the image sensor having a plurality of light receiving pixels arranged two-dimensionally on a substrate, the color filter R, G, and B cells corresponding to different pixels having spectral sensitivity corresponding to different colors and arranged in a checkered pattern on the same plane, and spectral sensitivity corresponding to infrared light. IR cells arranged on a vertical line below and below the surface of the B cell, and detecting R, G, and B values captured by the image pickup unit, and correcting the detected R, G, and B values by color values based on IR values. And a two-band filter positioned at an upper end of the color correction unit and passing only a 400-650 wavelength (nm) region and a 850-950 wavelength (nm) region. With image sensor There is. In this case, the IR cells are positioned under the R, G, and B cells because infrared rays reach a deeper portion of the semiconductor because they have a longer wavelength than visible rays, but visible rays do not.

Preferably, the color corrector calculates the detected R value by applying the formula R = r-(A * IR + B) and calculates the detected G value by applying the formula G = g-(C * IR + D). And, the detected B value is calculated by applying the formula B = b-(E * IR + F), where r is the output value of the R (Red) cell, g is the output value of the G (Green) cell , b is the output value of the B (Blue) cell, IR is the output value of the Infrared Ray (IR) cell, R, G, B are the corrected color values, and A, B, C, D, E, F are the coefficients and It is characterized by a constant value.

Preferably, the IR cell is disposed on the front surface of the R, G, B cells or selectively selected from each cell of R, G, B. In a Bayer cell of an actual image sensor, in order to reduce an area, a 2x2 cell does not become one pixel, but each cell corresponds to one pixel. Therefore, the G and B values of R cells are obtained by interpolating the values of adjacent G or B cells. Therefore, if the IR cell is configured in every cell, the resolution of the IR can be quite excellent. If placed in one of the 2x2 cells, the IR values in the remaining cells should be interpolated equally to the color values.

Another feature of an image sensor having an infrared correction function applicable according to the present invention for achieving the above object is that in the image sensor having a plurality of light receiving pixels arranged two-dimensionally on the substrate, R, G, B cells corresponding to each pixel arranged in a checkered pattern on the same plane with a spectral sensitivity corresponding to color, and spectral sensitivity corresponding to infrared light, and the planes of the R, G and B cells And IR cells arranged on a vertical line below, IR output unit for outputting infrared light, and R, G, and B values captured by the imaging unit and detected based on IR values output from the IR output unit. A color correction unit for correcting the R, G, and B values for each color value, and a 2-band filter positioned at an upper end of the color correction unit and passing only a 400 to 650 wavelength (nm) region and a 850 to 950 wavelength (nm) region And corrected through the color correction unit. It includes a color output unit for outputting the R, G, B value.

Preferably, the image sensor further comprises a proximity sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell. It features.

Preferably, the image sensor further comprises an illuminance sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell. It features.

Preferably, the image sensor is located on at least one side of the image sensor, the proximity sensor including a visible cell, and an IR cell disposed in a vertical line below and below the surface of the visible cell, and the image sensor Located on at least one side of the, characterized in that it further comprises an illumination sensor comprising a visible cell, and an IR cell disposed on a vertical line below and below the surface of the visible cell.

Preferably, the proximity sensor and the illuminance sensor is an image sensor having an infrared correction function, characterized in that composed of at least one cell unit.

Preferably, the proximity sensor and the illuminance sensor are located at the center of the side of the image sensor.

As described above, an image sensor having an infrared correction function according to the present invention has the following effects.

First, by adding IR cells in a stacked form in addition to the existing R, G, B cells to the image sensor, the R, G, B values and IR values are obtained separately, and the IR values included in the R, G, B values are corrected. This eliminates the need for an IR cut-off filter used in traditional camera modules and electronically switches between normal and infrared imaging without the need for a motor to remove and mount the IR cut-off filter. It has an effect.

Second, the degradation of the resolution and the sensitivity of the image signal can be suppressed without the IR cut-off filter, so that infrared imaging can be performed even in low light as well as in the visible light region.

Third, the IR cut-off filter can be removed without degrading the resolution or sensitivity of the image signal, which can be applied to small devices such as mobile communication terminals by eliminating the cost increase and securing the mounting space.

Fourth, the conventional image sensor uses the IR cut-off filter, so it is impossible to implement the proximity sensor function. Even if the IR cut-off filter is removed, the visible and infrared light are recognized together, so the proximity and illumination sensor functions cannot be implemented. When the image sensor of the present invention is applied to a video call camera of a mobile communication terminal, it is possible to implement the functions of a proximity sensor and an illuminance sensor that are recently applied to a smartphone.

Fifth, by using a two-band filter, the wavelength range where the R, G, B cells and IR cells have different sensitivity are excluded, and only the wavelength range with similar sensitivity is corrected.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments with reference to the accompanying drawings.

Referring to the accompanying drawings, a preferred embodiment of an image sensor having an infrared correction function according to the present invention will be described. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. It is provided to inform you.

4 is a schematic plan view showing an image sensor with an infrared ray correction function according to an embodiment of the present invention.

As shown in FIG. 4, the image sensor has a spectral sensitivity corresponding to a different color using a color filter, and has R, G, and B cells 100 corresponding to each pixel arranged in a checkered pattern on the same plane. An IR cell 200 having a spectral sensitivity corresponding to external light and disposed on a vertical line below and below the surface of the R, G, and B cells 100.

The IR cell 200 is conventionally disposed horizontally on the same plane as the R, G, and B cells 100, as shown in FIG. 3, but in the present invention, as shown in FIG. It is characterized by being placed vertically.

As such, when the R, G, B cells 100 and the IR cells 200 are vertically disposed, the infrared light has a longer wavelength than visible light, and thus infrared light penetrates deep into the semiconductor.

In addition, in the vertical arrangement of the R, G, and B cells 100 and the IR cells 200, image quality deterioration due to the reduction of the G cells occurring in the case of the conventional horizontal arrangement may be eliminated, and the IR cells 200 may be eliminated. The area of) is up to 4 times larger than that of the horizontal arrangement, so the sensitivity of infrared light is much better.

On the other hand, the IR value is close to the R value due to the characteristics of the frequency, and has a large influence on the R value, and the G value and the B value are relatively small. Therefore, in order to correct the IR value added to the R, G, and B values, correction must be made for each color value.

Accordingly, the image sensor detects R, G, and B values captured by the IR output unit that outputs infrared light, and the imaging unit, and detects R, G, and B values based on the IR values output from the IR output unit. It further comprises a color correction unit for correcting for each color value, and a color output unit for outputting the R, G, B values corrected through the color correction unit.

In this case, the color value correction performed by the color correction unit is basically implemented by the following equations (1), (2) and (3), as shown in FIG.

R = r-(A * IR + B)

G = g-(C * IR + D)

B = b-(E * IR + F)

Equation 1 is an equation for correcting an R value, Equation 2 is an equation for correcting a G value, and Equation 3 represents an equation for correcting a B value.

In Equations 1 to 3, r is an output value of an R cell, g is an output value of a G cell, b is an output value of a B cell, and IR is an output value of an IR cell. And R, G, and B are corrected color values, and A, B, C, D, E, and F are coefficients and constant values. The coefficient value for each of the colors can be changed to a value obtained by an experiment due to the semiconductor structure and characteristics.

In this case, as shown in FIG. 1, the sensitivity 10, 20 and 30 for each wavelength of the R, G, and B cells are shown, whereas the sensitivity 40 of the IR cell is similar to a curve appearing in the IR wavelength bands of the G and B cells. appear. Therefore, in the 650 ~ 850 wavelength (nm) region, it is difficult to correct according to the wavelength of sensitivity because the sensitivity for each color is different.

Therefore, in the present invention, a two-band filter (not shown) is configured to correct more accurately. At this time, the band region of the two-band filter passes only the 400-650 wavelength (nm) region, which is the visible light region, and the 850-950 wavelength (nm) region, which is the IR region. This excludes the 650-850 wavelength (nm) region where the sensitivity of the R, G, B cells and the IR cells are different, and corrects only the 850-950 wavelength (nm) region, which has almost the same sensitivity. Single equations such as 2 and 3 allow for more accurate calibration.

6 is a schematic plan view showing an image sensor with an infrared ray correction function according to another embodiment of the present invention.

As shown in FIG. 6, the IR cells 200 disposed on the vertical lines below and below the planes of the R, G, and B cells 100 corresponding to the pixels arranged in a checkered pattern on the same plane are R, G, and B. The cell 100 may be selectively disposed among the cell surfaces other than the front surface of the cell 100.

However, in a Bayer cell of an actual image sensor, in order to reduce an area, 2x2 cells do not become one pixel, but each cell corresponds to one pixel. Therefore, the G and B values of R cells are obtained by interpolating the values of adjacent G or B cells. Therefore, if the IR cell is configured in every cell, the resolution of the IR can be quite excellent. If placed in one of the 2x2 cells, the IR values in the remaining cells should be interpolated equally to the color values.

When the image sensor of the present invention configured as described above is applied to a video call camera of a mobile communication terminal, a function of a proximity sensor that is recently applied to a smartphone can be implemented.

In general, the proximity sensor is composed of a photodiode that senses the distance by receiving IR reflected from the IrED, and thus cannot be integrated with an existing image sensor using an IR cut-off filter.

However, when the IR cut-off filter is not used as in the present invention, only the IR value is read from the image sensor to replace the role of the proximity sensor. In addition, the image sensor having the same structure as the present invention can implement the illumination sensor function. That is, the illuminance sensor adjusts the brightness of the display LCD by accepting only the visible light value. Since the infrared light correction circuit can separate only the visible light, the illuminance sensor corrects the IR value from the value obtained from the visible cell. It is possible.

In the present invention, in order to minimize the power consumption during the simultaneous operation of the image sensor and the proximity and illumination sensor and the proximity / illuminance sensor operation, the proximity sensor and the illumination sensor are integrated into the image sensor and implemented as an on-chip. . That is, when the entire image sensor having the shape of FIG. 4 or FIG. 6 is used as a proximity sensor or an illuminance sensor, power consumption is high, and it is difficult to use the proximity and illuminance functions during camera operation. Together with the image sensor, a proximity sensor and an illuminance sensor were implemented.

As shown in Figs. 7 and 8, the image sensor has a spectral sensitivity corresponding to different colors using a color filter, and R, G, B cells corresponding to each pixel arranged in a checkered pattern on the same plane, and red An image sensor having an spectral sensitivity corresponding to external light and including an IR cell disposed in a vertical line below and below the planes of the R, G, and B cells, wherein the image sensor is disposed on at least one side of the image sensor. A proximity sensor 300 including an unused visible cell, and an IR cell having a sensitivity suitable for infrared light and disposed on a vertical line below and below the surface of the visible cell, and at least one side of the image sensor And an illuminance sensor 400, which is located at and includes an IR cell which has a sensitivity suitable for infrared light, and an IR cell which is disposed on a vertical line below and on the surface of the visible cell. .

Since the proximity sensor 300 uses an IR cell, and the illumination sensor 400 operates by recognizing only visible light, the proximity sensor 300 corrects an IR value from a value obtained from a visible cell through this characteristic, thereby providing a proximity function or illumination. Implement each of the functions.

In the drawing, the proximity sensor 300 and the illuminance sensor 400 are configured in one cell unit, but may be configured in two or more cell units.

In addition, the proximity sensor 300 and the illuminance sensor 400 are located on at least one side of the image sensor, and when implemented as two or more cells, the proximity or illuminance value is an average value of the values detected in each cell. To calculate.

In addition, the proximity sensor 300 and the illumination sensor 400 are preferably configured to be located at the center of the side of the image sensor.

Although the technical spirit of the present invention described above has been described in detail in a preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a graph showing the spectral sensitivity characteristics of each of the RGB light receiving pixels in which the respective RGB filters are disposed;

FIG. 2 is a schematic plan view showing an image sensor having a configuration of a color filter array having a conventional Bayer arrangement. FIG.

FIG. 3 is a schematic plan view showing an image sensor with an IR filter with the IR cut-off filter removed in FIG.

4 is a schematic plan view showing an image sensor with an infrared correction function according to an embodiment of the present invention.

FIG. 5 is a configuration diagram illustrating a process of performing correction for each color value through the color correction unit of FIG. 4. FIG.

6 is a schematic plan view showing an image sensor with an infrared correction function according to another embodiment of the present invention.

FIG. 7 is a schematic plan view illustrating a structure in which an image sensor with an infrared ray correction function and a proximity sensor and an illuminance sensor are included according to another embodiment of the present invention.

8 is a schematic plan view showing a structure in which an image sensor having an infrared correction function and a proximity sensor and an illuminance sensor are included according to another embodiment of the present invention;

* Explanation of symbols for main parts of the drawings

10: B component 20: G component

30: R component 40: IR component

100: R, G, B cell 200: IR cell

300: proximity sensor 400: illumination sensor

Claims (12)

An image sensor having an imaging unit consisting of a plurality of light receiving pixels arranged two-dimensionally on a substrate, R, G, B cells corresponding to each pixel arranged in a checkered pattern on the same plane with spectral sensitivity corresponding to different colors using a color filter, An IR cell having a spectral sensitivity corresponding to infrared light and disposed on a plane different from the plane of the R, G, and B cells below the plane; A color correction unit detecting the R, G and B values captured by the image pickup unit and correcting the detected R, G and B values for each color value based on an IR value; Located at the top of the color correction unit, the image sensor having an infrared correction function, characterized in that it comprises a two-band filter passing only the 400 ~ 650 wavelength (nm) region and 850 ~ 950 wavelength (nm) region. The method of claim 1, wherein the color correction unit The detected R value is calculated by applying the formula R = r-(A * IR + B), The detected G value is calculated by applying the formula G = g-(C * IR + D), The detected B value is calculated by applying the formula B = b-(E * IR + F), Where r is the output value of the R cell, g is the output value of the G cell, b is the output value of the B cell, IR is the output value of the IR cell, and R, G, B are corrected color values, and A, B, C, D, E, F is an image sensor with an infrared correction function, characterized in that the coefficient and the constant value. The method of claim 1, The IR cell is an image sensor having an infrared correction function, characterized in that the arrangement corresponding to all of the R, G, B cells or the cell surface of each of the R, G, B selectively disposed. An image sensor having an imaging unit consisting of a plurality of light receiving pixels arranged two-dimensionally on a substrate, R, G, and B cells corresponding to each pixel having spectral sensitivity corresponding to different colors and arranged in a checkered pattern on the same plane; An IR cell having a spectral sensitivity corresponding to infrared light and disposed on a vertical line below and on the plane of the R, G, and B cells, IR output unit for outputting infrared light, A color correction unit detecting the R, G, and B values captured by the image pickup unit and correcting the detected R, G, and B values for each color value based on the IR values output from the IR output unit; Located at the top of the color correction unit, a two-band filter that passes only the 400 ~ 650 wavelength (nm) region and 850 ~ 950 wavelength (nm) region, And a color output unit configured to output the corrected R, G, and B values through the color corrector. An image sensor having an imaging unit consisting of a plurality of light receiving pixels arranged two-dimensionally on a substrate, R, G, B cells corresponding to respective pixels arranged in a checkered pattern on the same plane with spectral sensitivity corresponding to different colors using a color filter, and spectral sensitivity corresponding to infrared light, wherein R IR cells arranged on a vertical line below and below the G and B cells, An infrared ray correction function further comprising a proximity sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell Image sensor provided with. An image sensor having an imaging unit consisting of a plurality of light receiving pixels arranged two-dimensionally on a substrate, R, G, B cells corresponding to respective pixels arranged in a checkered pattern on the same plane with spectral sensitivity corresponding to different colors using a color filter, and spectral sensitivity corresponding to infrared light, wherein R IR cells arranged on a vertical line below and below the G and B cells, Infrared correction function further comprises an illumination sensor positioned on at least one side of the image sensor, the illumination sensor including a visible cell, and an IR cell disposed on a vertical line below and below the surface of the visible cell. Image sensor provided with. An image sensor having an imaging unit consisting of a plurality of light receiving pixels arranged two-dimensionally on a substrate, R, G, B cells corresponding to respective pixels arranged in a checkered pattern on the same plane with spectral sensitivity corresponding to different colors using a color filter, and spectral sensitivity corresponding to infrared light, wherein R IR cells arranged on a vertical line below and below the G and B cells, A proximity sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell; Infrared correction function further comprises an illuminance sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell. Image sensor provided with. The method of claim 1, wherein the image sensor A proximity sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell; At least one of an illuminance sensor positioned on at least one side of the image sensor and including a visible cell and an IR cell disposed on a vertical line below and below the surface of the visible cell; Image sensor with infrared correction function. The method according to any one of claims 5, 7, and 8, The proximity sensor is an image sensor having an infrared correction function, characterized in that configured in at least one cell unit. The method of claim 9, The proximity sensor is an image sensor having an infrared correction function, characterized in that located in the center of the side of the image sensor. The method according to any one of claims 6, 7, and 8, The illumination sensor is an image sensor having an infrared correction function, characterized in that composed of at least one cell unit. The method of claim 11, The illuminance sensor is an image sensor having an infrared correction function, characterized in that located in the center of the side of the image sensor.

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