TWI436640B - Image sensor - Google Patents

Description

Image sensor

The present invention relates to image sensing, and more particularly to an image sensor composed of a plurality of image sensing units corresponding to different colors.

Today, image sensors have been widely used in digital cameras, digital cameras and portable electronic devices to provide image capture. However, as the size of these electronic devices shrinks and the size of the image sensor itself shrinks and the resolution of the image sensor increases, some problems existing in the image sensor become more and more obvious. Please refer to FIG. 1 , which is a schematic structural view of a conventional image sensor. As shown, the image sensor 100 includes a color filter array 110 on which a microlens array 120 is disposed, and a color filter array 120 is disposed below the color filter array 120. There is a sensing array 130 for converting incident light into an electronic signal to obtain an image to be captured. Generally, the sensing array 130 includes a plurality of sensing units, which may be complementary metal oxide semiconductor (CMOS) sensing units or charge-coupled device (CCD) sensing units. Each of the sensing units receives incident light that passes through the color filter array 110 above it to sense a particular color component size corresponding to a certain pixel. For example, the sensing unit 131 receives the filtered incident light L that penetrates one of the microlenses 121 of the microlens array 120 and one of the color filters R of the color filter array 110, thereby generating a corresponding one. The sensing unit 132 receives the filtered incident light that penetrates one of the microlenses 122 of the microlens array 120 and one of the color filters G of the color filter array 110. L', which in turn generates a sensing signal corresponding to a green component of a certain pixel, whereby each sensing unit senses a sensing signal corresponding to a certain color component, and the image processing technology can These sensing signals corresponding to the respective color components are recalculated to obtain complete color component information (eg, R, G, and B values) for each pixel in the image. However, as the size of the image sensor is reduced and the resolution of the image sensor is increased, the size of the sensing unit is also reduced, which makes the crosstalk phenomenon more obvious. For example, due to characteristics such as diffraction and interference of light, the sensing unit 131 may erroneously sense the filtered incident light L′ penetrating the microlens 122 and the color filter G, and the sensing unit 132 The filtered incident light L penetrating the microlens 121 and the color filter R is also erroneously sensed. In the original design of the image sensor, each of the sensing units should respectively sense light of different color components, for example, the sensing unit 131 is used to sense the red color component in the incident light, and the sensing unit 132 is used to sense the green color component in the incident light. This crosstalk phenomenon will cause the sensing units 131 and 132 to erroneously sense other color components, which may cause subsequent image processing operations to be generated. The result of the error is that the color component information of each pixel cannot be correctly taken, so that the image quality is affected.

Moreover, another cause of crosstalk is that when the resolution of the image sensor is increased, the sensing unit is bound to shrink, so the distance between each sensing unit is relatively small. In this way, when sensing relatively strong light, the sensing unit generates more electric charge, so the charge overflow is prone to occur, and the overflowed electric charge may further interfere with the adjacent sensing unit to cause the sensing result. Error. It can be seen that under the trend of image sensor size reduction and resolution improvement, the conventional image processor architecture is facing many insurmountable tests.

In view of this, the present invention provides an image sensor architecture that can solve the crosstalk problem. The image sensor architecture utilizes multiple image sensing units that respectively sense different color components to capture images to obtain different color component information on different sensing arrays, thereby reducing crosstalk phenomenon to image quality. The impact. In addition, the present invention further adjusts the set height of the microlens array in the image sensing unit according to the difference in color components sensed by the image sensing unit, thereby improving the image quality of the image sensor.

According to an embodiment of the present invention, an image sensor is provided. The image sensor includes: a first image sensing unit and a second image sensing unit. The first image sensing unit includes: a first color filter and a first sensing array. The first color filter corresponds to a first color and is used to filter a color component of the incident light other than the first color to generate a first filtered incident light. The first sensing array has a plurality of sensing units and is configured to sense the first filtered incident light to generate a first sensing result. Furthermore, the second image sensing unit comprises: a second color filter and a second sensing array. The second color filter corresponds to a second color, and is configured to filter color components of the incident light other than the second color to generate a second filtered incident light, wherein the second color is The first color is different. The second sensing array has a plurality of sensing units and is configured to sense the second filtered incident light to generate a second sensing result.

According to another embodiment of the present invention, an image sensing unit is provided. The image sensing unit includes: a color filter, a sensing array, and a microlens array. The color filter corresponds to a color and is used to filter a color component other than the color of the incident light to generate a filtered incident light. The sensing array has a plurality of sensing units and is configured to sense the filtered incident light to generate a sensing result. The microlens array is disposed between the color filter and the sensing array.

Please refer to FIG. 2, which is a side view of an embodiment of the image sensor of the present invention. As shown in the figure, the image sensor 200 includes a first image sensing unit 210, a second image sensing unit 220, and a third image sensing unit 230. The image sensing units are arranged adjacent to each other. Each image sensor includes (from top to bottom): a color filter (eg, 212, 222, 232) and a sensing array (eg, 216, 226, 236). Each of the color filters 212, 222, and 232 respectively corresponds to a single color, and is used to filter color components other than the color in the incident light, since the principle of the color filter is in the technical field of the present invention. It is well known to those of ordinary skill and will not be described here. Compared with the conventional image sensor, the color filter array (for example, Bayer filter array) composed of a plurality of small color filters corresponding to different color components is used to filter the incident light, and the image sensing of the present invention is performed. The color filters 212, 222, and 232 employed by the device are larger color filters corresponding to a single color. For example, the color filter 212 may correspond to a red color component and filter other color components other than the red color component of the incident light to generate a filtered incident with the red color component as the main component. Light. When the filtered incident light generated by the color filter 212 is received by the sensing array 216, the plurality of sensing units in the sensing array 216 respectively generate charges according to the received light intensity, and then output corresponding signals. The first image sensing unit 210 generates a first sensing result according to the sensing signals. Therefore, by sensing the plurality of sensing units on the array 216 (wherein the sensing units may be complementary metal-oxi-semiconductor (CMOS) sensing units or charge coupled elements (Charge- The first image sensing unit 210 can generate the first sensing result corresponding to the red color component of each pixel. Furthermore, the second image sensing unit 220 and the third image sensing unit 230 perform similar operations to further generate other color components corresponding to the incident light (eg, a green color component (G color component) and a blue color component. A second sensing result of the component (B color component) and a third sensing result are used to complete the image capturing operation of the image sensor 200. In addition, in the above embodiment, the first image sensing unit 210, the second image sensing unit 220, and the third image sensing unit 230 may respectively be used to sense different color components in the incident light, but In other embodiments of the invention, more than one image sensing unit may be included for sensing the same color component. For example, the image sensor includes four image sensing units, and two of the image sensing units are used simultaneously. In order to sense the green color component in the incident light, the other two image sensing units respectively sense the red color component and the blue color component, and such an embodiment still belongs to the scope of the present invention, that is, the present invention There is no limit to the number of image sensing units in the image sensor, and there is no limit to the number of image sensing units corresponding to the same color component.

In addition, in the present embodiment, the first sensing array 216, the second sensing array 226, and the third sensing array 236 are connected to each other in order to prevent the sensing results of the different color components from interfering with each other. They are independent of one another and are disposed on a plurality of different substrates 218, 228 and 238, respectively. However, this is only one embodiment of the present invention. In different embodiments of the present invention, the first sensing array 216, the second sensing array 226, and the third sensing array 236 may also be disposed on the same substrate.

As can be seen from the above, most of the conventional image sensors only have a sensing array and a color filter array, and utilize a plurality of sensing units on the sensing array to simultaneously sense different color components in the light. Therefore, the crosstalk phenomenon is quite obvious. In contrast, the present invention utilizes multiple image sensing units to sense different color components in the incident light. Therefore, the present invention can avoid the mutual interference of light of different color components and cause sensing of the sensing unit. Bad effects.

Moreover, in the preferred embodiment of the present invention, each image sensing unit has a microlens array, such as the microlens arrays 214, 224, and 234 shown in FIG. Different from the conventional image sensor, in the embodiment, the microlens arrays 214, 224 and 234 are respectively disposed between the color filter and the sensing array of the image sensing unit. Moreover, in the image sensing unit corresponding to different colors, the distance between the microlens array and the sensing array is different. For example, in the image sensing unit 210, the distance between the microlens array 214 and the sensing array 216 is D, and in the image sensing unit 220, between the microlens array 224 and the sensing array 226. The distance D is D, and when the image sensing unit 210 and the image sensing unit 220 are respectively used to sense different color components in the incident light, the distance D is different from the distance D′. However, when both the image sensing unit 210 and the image sensing unit 220 are used to sense the same color component in the incident light, the distance D is the same as the distance D'. In other words, in the embodiment, the distance between the microlens array and the sensing array in the image sensing unit is adjustable, and is determined according to the color corresponding to the color filter of the image sensing unit. The idea of such a design is that since the light rays corresponding to different color components have different wavelengths, there are different focal lengths for the same lens, so the concept of the present invention adjusts the microlens array according to the difference in color components. The distance between the arrays is sensed, that is, the pitch is adjusted according to the focal length corresponding to the light of different color components. In turn, each image sensing unit corresponding to a different color component can be optimized to improve the imaging quality of the image sensor.

Next, please refer to FIG. 3 and FIG. 4 , which are respectively upper schematic views of different embodiments of the image sensor of the present invention, which illustrate possible arrangement of image sensing units in the image sensor of the present invention. . As shown in the figure, in different embodiments, the image sensing units in the image sensor of the present invention will have different arrangements. For example, the image sensing units 310-330 in FIG. 3 are vertically oriented. The directions are arranged and correspond to a red (R) color component, a green (G) color component, and a blue (B) color component, respectively, for respectively sensing different color components in the incident light, and respectively outputting corresponding to R, G The plurality of sensing results are compared with B, and the image sensing units 410 to 430 in FIG. 4 are arranged in a triangular manner, and output a plurality of sensing results corresponding to R, G, and B, respectively. It can be seen from the above two embodiments that the present invention does not limit the arrangement of the image sensing units in the image sensor, that is, any possible arrangement is within the scope of the present invention.

The image sensor of the present invention may include an image compensation unit, the purpose of which is to compensate for the aberration caused by the image sensing unit being disposed at different positions. For example, please refer to FIG. 4, because the sensing unit at positions 4101, 4201 and 4301 respectively sense the red color component, the green color component and the blue color component, which belong to the same pixel in one image. The color component, however, may cause aberrations between the sensing results of the image sensing unit due to the difference in the actual position of the sensing unit. Therefore, the present invention needs to pass an image compensation unit to target different image sensing units. The resulting sensing results are corrected to improve the imaging quality of the image sensor of the present invention. Therefore, in a preferred embodiment of the image sensor of the present invention, an image compensation unit is coupled to at least one of the image sensing units of the image sensor of the present invention, and is used for Compensating at least one of the sensing results generated by the image sensing unit.

Furthermore, in another embodiment, the image sensor of the present invention may further comprise an image sensing unit without a color filter for providing the image with a color filter. Corresponds to the white (W) color component in the incident light to assist in operations such as white balance and color correction. For an example of this embodiment, please refer to FIG. 5, which is a schematic diagram of the upper side of the image sensor of the present invention. As shown in the figure, the image sensor 500 includes a first image sensing unit 510, a second image sensing unit 520, a third image sensing unit 530, and a fourth image sensing unit 540. The first image sensing unit 510, the second image sensing unit 520, and the third image sensing unit 530 are similar to the structure of the image sensing unit in FIG. 2, however, the fourth image sensing unit 540 has Differently, there is no color filter in its structure, but only a microlens array and a sensing array. Therefore, the white (W) color component in the light can be received. The main purpose of the fourth image sensing unit 540 is to provide information of white color components for white balance and color correction. Moreover, since the fourth image sensing unit 540 does not have a color filter, the sensing result generated by the fourth image sensing unit 540 can correspond to the Y component value in the YUV color space. Therefore, the present invention can further adjust the coefficients used to convert the RGB values in the RGB color space into the YUV values in the YUV color space through the sensing results of the fourth image sensing unit 540. Further, when converting the RGB color space to the YUV color space, a formula of Y=0.299R+0.587G+0.114B may be used. Therefore, the conventional image sensor directly uses such a formula to sense the image. The R, G, and B values obtained are converted to YUV values. However, the coefficients used by the above formulas (eg, 0.299, 0.587, and 0.114) may not be suitable for all situations depending on the characteristics of the image sensor. Therefore, the present invention can generate the sensing result corresponding to the Y value generated by the fourth image sensing unit 540 and the first image sensing unit 510, the second image sensing unit 520, and the third image sensing unit 530. These coefficients are re-adjusted corresponding to the sensing results of the R, G, and B values in the RGB color space. Therefore, the image sensor 500 may further include an image processing circuit (not shown) coupled to the first image sensing unit 510, the second image sensing unit 520, and the third image sensing unit 530. And the fourth image sensing unit 540, and adjusts the RGB according to the sensing results of the first image sensing unit 510, the second image sensing unit 520, the third image sensing unit 530, and the fourth image sensing unit 540. The coefficients used to convert the RGB values in the color space to the YUV values in the YUV color space (eg, eg 0.299, 0.587, and 0.114).

In summary, the image sensor architecture provided by the present invention can reduce crosstalk, and also provides better white balance and color correction capability, so that it can have imaging better than conventional image sensors. quality.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100, 200, 300, 400, 500. . . Image sensor

110. . . Color filter array

120, 214, 224, 234. . . Microlens array

121, 122. . . Microlens

130, 216, 226, 236. . . Sensing array

131, 132. . . Sensing unit

210, 220, 230, 310~330, 410~430, 510~540. . . Image sensing unit

212, 222, 232. . . Color filter

218, 228, 238. . . Base

4101, 4201, 4304. . . position

Figure 1 is a schematic view of the structure of a conventional image sensor.

2 is a schematic side view showing an embodiment of an image sensor of the present invention.

Figure 3 is a schematic diagram of the upper structure of an embodiment of the image sensor of the present invention.

Figure 4 is a schematic view of the upper structure of another embodiment of the image sensor of the present invention.

Fig. 5 is a schematic view showing the upper structure of still another embodiment of the image sensor of the present invention.

200. . . Image sensor

210, 220, 230. . . Image sensing unit

212, 222, 232. . . Color filter

214, 224, 234. . . Microlens array

216, 226, 236. . . Sensing array

218, 228, 238. . . Base

Claims (8)

An image sensor includes: a first image sensing unit, comprising: a first color filter corresponding to a first color for filtering colors other than the first color of an incident light a component for generating a first filtered incident light; and a first sensing array having a plurality of sensing units for sensing the first filtered incident light to generate a first sensing result; The second image sensing unit includes: a second color filter corresponding to a second color for filtering color components other than the second color of the incident light to generate a second filtered incident light The second color is different from the first color system; and a second sensing array has a plurality of sensing units for sensing the second filtered incident light to generate a second sensing result a third image sensing unit, comprising: a third color filter corresponding to a third color for filtering color components other than the third color of the incident light to generate a third filter After incident light, where Three first color and the second color are different lines; and a third sensing array having a plurality of sensing unit for sensing the third filter the incident light, to generate a third sensing result; a fourth image sensing unit includes: a sensing array having a plurality of sensing units for sensing the incident light to be a fourth sensing result; and an image processing circuit coupled to the first An image sensing unit, the second image sensing unit, the third image sensing unit, and the fourth image sensing unit are configured to adjust the first sensing result according to the fourth sensing result, The second sensing result is converted from a first color space to a second color space; wherein the first image sensing unit is located beside the second image sensing unit . The image sensor of claim 1, wherein the first color and the second color are respectively one of red (R), green (G) or blue (B). The image sensor of claim 1, further comprising: an image compensation circuit coupled to the at least one sensing array of the first sensing array and the second sensing array for compensating At least one of the first sensing result and the second sensing result. The image sensor of claim 1, wherein the first sensing array and the second sensing array are independent of each other and are respectively disposed on a plurality of different substrates. The image sensor of claim 1, wherein the plurality of sensing sheets Each sensing unit in the element is a Complementary Metal-Oxide-Semiconductor (CMOS) sensing unit or a Charge-coupled Device (CCD) sensing unit. The image sensor of claim 1, wherein the fourth image sensing unit further comprises: a microlens array disposed on the sensing array. The image sensor of claim 1, wherein the first image sensing unit and the second image sensing unit respectively comprise: a microlens array disposed on the color filter and the sensing Between arrays. The image sensor of claim 7, wherein the distance between the microlens array and the sensing array is different in the first image sensing unit and the second image sensing unit.