WO2022096323A1

WO2022096323A1 - Sensor arrangement and producing method thereof

Info

Publication number: WO2022096323A1
Application number: PCT/EP2021/079686
Authority: WO
Inventors: Maarten Pennings; Johan De Meulder
Original assignee: Ams Sensors Belgium Bvba
Priority date: 2020-11-05
Filing date: 2021-10-26
Publication date: 2022-05-12

Abstract

A sensor arrangement (1) comprises at least three types of receiving elements (4), wherein the receiving elements (4) of a particular type are configured to detect light in a respective wavelength range. The receiving elements (4) are arranged in a matrix (2), wherein columns (3, 3') of the matrix comprise receiving elements (4) of the at least three types which are arranged in predefined sequences (6, 6') such that the sequence (6') of at least one column (3') of the matrix (2) is formed by the sequence (6) of a respective preceding column (3), which is cyclically shifted by at least one receiving element (4) in a predefined direction.

Description

SENSOR ARRANGEMENT AND PRODUCING METHOD THEREOF

The present disclosure relates to a sensor arrangement , an image sensor and a method for producin a sensor arrangement .

BACKGROUND OF THE INVENTION

CMOS image sensors are used in a wide range of applications , such as for camera modules and smartphones , tablet computers , laptops , automotive applications etc . Some of these applications , such as photography, rely on sensitivities in the visible optical domain while other applications , such as 3D imaging and identi fication, require the image sensor to be sensitive in the infrared ( IR) domain . For example , the infrared domain is used in dark environments or at least in situations with limited brightness . But the infrared domain can also be used to enhance normal RGB images : it brings "texture" because infrared radiation can " see through" certain conditions like haze that light in the visible wavelength domain cannot .

It is desirable to provide an image sensor that is sensitive in both the visible and in the infrared domain . To this end, each sensor arrangement of the image sensor can comprise color receiving elements , each sensitive to a certain portion of the visible spectrum as well as IR receiving elements for the infrared spectrum .

Sensor arrangements that have only visible color receiving elements typically have these arranged in a speci fic pattern, the so-called Bayer pattern, wherein the sensor arrangement comprises four receiving elements that are arranged in a 2x2 array, of which two receiving elements are arranged opposite to each other and are sensitive to the green portion of the visible spectrum, while the other two receiving elements are sensitive in the blue and red part of the spectrum, respectively . The reason for having two receiving elements for the green domain is that the human eye is more sensitive to green than to red or blue . An image signal processor ( ISP ) maps mono-color picture elements ( every element only contains information of the single color of its receiving elements ) to an array of poly-color picture elements ( every element stores all received colors ) , which is achieved by evaluating the color information from neighboring receiving elements . Moreover, the ISP could employ other algorithms , e . g . for edge preservation of the image . The image trans formation made by such an ISP is referred to as "demosaicing" . In the particular case of Bayer patterns it is sometimes referred to as "debayering" .

Implementing an additional IR receiving element in these image sensors is typically achieved by sacri ficing a subset of the receiving elements . For example , in some earlier implementations one of the green receiving elements of a Bayer filter array pattern is sacri ficed . However, the loss of a green receiving element leads to a deterioration of the image perception, since the human eye is most sensitive to green . Another approach is to use a dedicated area of the sensor arrangement for infrared receiving elements . The problem in this case is that the receiving elements are not evenly distributed over the sensor area, so that receiving elements for di f ferent colors could be spaced far away from each other . However, for the above-mentioned image trans formation ( demosaicing) missing color information has to come from neighboring receiving elements .

Therefore , an obj ective to be achieved is to provide an improved concept for a sensor arrangement with an ef fective distribution of receiving elements , which overcomes the above mentioned drawbacks of existing sensor arrangements .

This obj ect is achieved with the subj ect-matter of the independent claims . Embodiments and developments of the improved concept are defined as the dependent claims .

Here and in the following, green receiving elements refer to receiving elements , which are capable to sense light in the green wavelength range . Accordingly, blue receiving elements and red receiving elements refer to receiving elements , which are capable to sense light in the blue or red wavelength range , respectively . IR receiving elements refer to receiving elements which are capable to sense light in the infrared domain, especially in the near-infrared (NIR) domain . The term light may refer to electromagnetic radiation in general including infrared radiation, near-infrared radiation and visible light . Accordingly, green, blue , red and NIR light will refer to light in the respective wavelength range . Moreover, in the following the term "color information" refers to an intensity value of light in a speci fic wavelength range . For example , the wavelength range can correspond to blue , green or red light . However, it can also correspond to IR or NIR light . Accordingly, the term "color" refers to the respective wavelength domain of light , including the IR wavelength domain . The sensor arrangement according to the improved concept comprises at least three types of receiving elements , wherein the receiving elements of a particular type are configured to detect light in a respective wavelength range . The receiving elements are arranged in a matrix . Columns of the matrix comprise receiving elements of the at least three types which are arranged in predefined sequences such that the sequence of at least one column of the matrix is formed by the sequence of a respective preceding column, which is cyclically shi fted by at least one receiving element in a predefined direction .

Receiving elements of di f ferent types may be configured to detect light in di f ferent wavelength ranges . However, the wavelength ranges may at least partially overlap . In an embodiment the sensor arrangement comprises four or at least four types of receiving elements . For example , the receiving elements of a first type are configured to detect light in the red wavelength range . The receiving elements of a second type are configured to detect light in the green wavelength range . The receiving elements of a third type are configured to detect light in the blue wavelength range . The receiving elements of a fourth type are configured to detect light in the IR wavelength range . However, the assignment to speci fic wavelength ranges can also be di f ferent or interchanged .

The matrix may comprise receiving elements which are arranged in columns and rows of the matrix . It will be appreciated that the terms "column" and "row" may be used interchangeably : by rotating a matrix by 90 degree , columns of the matrix become rows and vice versa . Therefore , by using the terms "column" and "row" it is merely referred to an arbitrary orientation of the matrix . The number of receiving elements in one column of the matrix is mainly arbitrary. However, it may depend on the total number of different types of receiving elements. The columns of the matrix may comprise receiving elements of each type of the sensor arrangement. Therefore, the number of rows of the matrix may be at least as large as the number of different types of receiving elements. For example, if four types of receiving elements are comprised by the sensor arrangement, the number of receiving elements in each column, i.e. the number of rows of the matrix, may be at least four, so that receiving elements of each of the four types can be arranged in the columns.

The sequence of receiving elements in one column refers to the sequential arrangement of the types of receiving elements, for example from top to bottom of the column. Consecutive receiving elements in the column, for example a topmost and a second topmost receiving element, may have same or different types. However, in a preferred embodiment, at least two of three consecutive receiving elements have different types.

The sequences of consecutive columns, for example the first and the second column of the matrix, can be the same or different. However, the sequence of at least one column is different from the sequence of the respective preceding column in that it is cyclically shifted by at least one receiving element in the predefined direction.

A cyclically shifted sequence of receiving elements means that the sequence is rotated with respect to an original sequence. The predefined direction of that rotation can be upwards or downwards, by way of example. The cyclically shifted sequence forms a modified sequence with respect to the original sequence, wherein the receiving elements of the modified sequence are shifted in a circle: a cyclical shift by one receiving element in a downward direction means that the topmost receiving element of the original sequence is mapped to the second topmost position of the modified sequence, the second topmost receiving element of the original sequence is mapped to the third topmost position of the modified sequence, and so on up to the last receiving element at the bottom of the original sequence, which is again mapped to the topmost position of the modified sequence .

Accordingly, the cyclical shift or rotation, respectively, can also be performed in an upward direction, so that, for example, the topmost receiving element of the original sequence is mapped to the bottom position of the modified sequence and so on.

Moreover, the modified sequence can be formed by the original sequence, which is cyclically shifted by more than one receiving element. This means that the modified sequence can be a cyclically shifted version of the original sequence, in which the receiving elements are shifted by more than one positions. In other words, a sequence that is cyclically shifted by x receiving elements is defined as a sequence that is x times cyclically shifted by one receiving element, where x is a natural number. For example, cyclic downward shifting by two receiving elements means that the topmost receiving element of the original sequence is mapped to the third topmost position of the modified sequence and so on, until the last but one receiving element is mapped to the topmost and the last receiving element is mapped to the second topmost position of the modi fied sequence .

For example , the sequence of the second column of the matrix is cyclically shi fted by at least one receiving element with respect to sequence of the first column of the matrix . In addition or alternatively, the sequence of the third column of the matrix is cyclically shi fted by at least one receiving element with respect to sequence of the second column of the matrix . The sequences of the remaining columns of the matrix can be handled accordingly .

In such sensor arrangements receiving elements of each type are distributed over the sensor arrangement in an ef fective way . Moreover, the sensor arrangement comprises a suf ficiently large amount of receiving elements of each type per sensor area .

In an embodiment of the sensor arrangement the sequence of each except a first column of the matrix is formed by the sequence of the respective preceding column, which is cyclically shi fted by at least one receiving element in the predefined direction .

In other words , subsequent columns of the matrix comprise a respective modi fied sequence of receiving elements , wherein the modi fied sequence is formed by the sequence of the respective preceding column, which is cyclically shi fted by at least one receiving element in the predefined direction .

The sequences of di f ferent columns of the matrix can be formed by the same cyclic shi ft with respect to the sequence of the respective preceding column . However, it should be noted that cyclic shi fts of sequences from one column to another column can also be di f ferent in the number of receiving elements to be shi fted and/or in the predefined direction .

In such sensor arrangements , the receiving elements of each type are distributed over the sensor arrangement in an ef fective way . Additionally, the sensor arrangement comprises a suf ficiently large amount of receiving elements of each type per sensor area .

In addition to the above-mentioned features or as alternative to the above mentioned embodiments , the sensor arrangement comprises a matrix of receiving elements , wherein the matrix is formed such that each receiving element of a particular type , which is completely surrounded by other receiving elements , has at least one neighboring receiving element of each other type . In some embodiments each receiving element of a particular type , which is completely surrounded by other receiving elements , has at least two neighboring receiving elements of each other type .

In the following, receiving elements , which are completely surrounded by other receiving elements , are called central receiving elements . In other words , each central receiving element of a particular type , i . e . each receiving element which is not located at the margin of the matrix, has at least one neighboring receiving element of each other type or at least two neighboring receiving elements of each other type , respectively . Having at least one neighboring receiving element of each other type can be achieved, for example , i f columns of the matrix comprise receiving elements of each type which are arranged in predefined sequences such that the sequence of each, except a first column of the matrix, is formed by the sequence of the respective preceding column, which is cyclically shifted by at least one receiving element in the predefined direction. If the columns of such matrix are formed by the sequence of the respective preceding column, which is cyclically shifted by more than one receiving element, e.g. two receiving elements, the number of neighboring receiving elements of each type, can be even more than one, e.g. at least two.

As mentioned above, the sensor arrangement can comprise at least three different types of receiving elements. For example, the sensor arrangement comprises three, four or even more types of receiving elements.

Neighboring receiving elements share at least an edge or a corner with each other. This means that receiving elements being rectangular in top-view and completely surrounded by other receiving elements have eight direct neighboring receiving elements. Some of the neighboring receiving elements can have the same type as the central receiving element .

In even further embodiments each receiving element of a particular type, which is completely surrounded by other receiving elements, has three or at least three neighboring receiving elements of each other type. For example, in case of rectangular receiving elements of three different types, a receiving element of the first type can have three neighboring receiving elements of the second type, three neighboring receiving elements of the third type and two neighboring receiving elements of the same (first) type. In such sensor arrangements the receiving elements of each type are distributed over the sensor arrangement in an ef fective way . Additionally, the sensor arrangement comprises a suf ficiently large amount of receiving elements of each type per sensor area .

In a further embodiment of the sensor arrangement the matrix is an m x n matrix with m and n being integers and being at least 3 . This means that the matrix can have m rows and n columns . The numbers of rows and columns can be equal or di f ferent to each other . In other words , the matrix can, but not necessarily have to be a quadratic matrix . For example , the matrix can be an n x n matrix . The number of rows of the matrix depends on the number of di f ferent types of receiving elements , as each column of the matrix comprises all types of receiving elements . This means that the number of rows is equal as or larger than the number of types of receiving elements .

The sequence of at least one column of the matrix is formed by the sequence of the respective preceding column, which is cyclically shi fted in the predefined direction by at least one receiving element and at most m- 1 receiving elements . Alternatively, the sequence of each except the first column of the matrix is formed by the sequence of the respective preceding column, which is cyclically shi fted in the predefined direction by at least one receiving element and at most m- 1 receiving elements .

Cyclically shi fting by m receiving elements would mean that the modi fied sequence equals the original sequence , as each column has exactly m receiving elements correspondingly to the number of rows of the matrix . Therefore , cyclically shi fting by more than m- 1 receiving elements does not lead to new sequences and thus does not have to be considered .

With respect to the number of rows and columns the matrix can be chosen as large as required in order to achieve a suf ficient image resolution . Alternatively, the sensor arrangement can be formed by combination of several matrices with a smaller number of rows and columns , respectively, such that a larger overall matrix is formed . Such matrices are arranged adj acent to each other in a main plane of extension of the sensor arrangement . This can mean that the matrices are arranged adj acent to each other in lateral directions .

According to another aspect of the sensor arrangement , the number of receiving elements of a speci fic type exceeds the number of receiving elements of other types in the columns of the matrix .

This also means that in the matrix the number of receiving elements of the speci fic type is larger than the number of receiving elements of other types . For example , the receiving elements of the speci fic type are configured to detect light in a wavelength range of particular interest . Therefore , the sensor arrangement can be formed in such a way that it is more sensitive to that speci fic wavelength domain than to other wavelength domains . For example , the wavelength range of particular interest could by the green wavelength range and the receiving elements of the speci fic type are green receiving elements , since the human eye is most sensitive to green .

Alternatively or additionally, the matrix of the sensor arrangement is formed such that each receiving element , which is completely surrounded by other receiving elements , has at least as much neighboring receiving elements of the speci fic type as receiving elements of other types . In other words , each central receiving element has at least as much neighboring receiving elements of the speci fic type as receiving elements of other types . In some embodiments , each central receiving element has even more neighboring receiving elements of the speci fic type as receiving elements of other types .

As mentioned above and in case of rectangular receiving elements , completely surrounded receiving elements have exactly eight neighboring receiving elements , which share a corner or an edge with the respective central receiving element . The central receiving element itsel f can also be of the speci fic type .

The above-mentioned feature assures that all over the sensor arrangement a suf ficiently large amount of receiving elements are present , which are configured to detect light in the wavelength range of particular interest . This speci fic color information can thus be evaluated with enhanced accuracy .

In a further embodiment of the sensor arrangement receiving elements of a first type are configured to detect light in the red wavelength range , receiving elements of a second type are configured to detect light in the green wavelength range , receiving elements of a third type are configured to detect light in the blue wavelength range , and receiving elements of a fourth type are configured to detect light in the infrared wavelength range . This can mean that the sensor arrangement comprises four or at least four types of receiving elements . However, the assignment of particular types of receiving elements to respective wavelength domains can also be di f ferent or interchanged . Moreover, the wavelength domains to be detected by the receiving elements of di f ferent types can also overlap .

Image sensors comprising such sensor arrangements with sensitivities in both the visible ( red, green, blue ) and the infrared wavelength range can conveniently be employed for both imaging in the visible , such as photography, as well as imaging in the infrared for 3D imaging and/or identi fication applications that use active illumination with an infrared light source , for instance . The image quality can be enhanced by means of the infrared domain . Di f ferent wavelengths have di f ferent absorption characteristics in for example humid air like haze or fog . Infrared light has better absorption characteristics in those environments than visible light . Therefore , the addition of IR/NIR sensitivity in an image sensor allows for adding "texture" to images , which improves the image quality . Moreover, image sensors with sensitivity in IR/NIR domain allows usage in dark environments .

According to a further embodiment , the sensor arrangement comprises at least two matrices as described in one of the preceding embodiments , wherein the matrices are arranged adj acent to each other in the main plane of extension of the sensor arrangement .

For example , the sensor arrangement comprises a plurality of matrices , which are arranged adj acent to each other in lateral directions , so that an overall matrix is formed . The matrices can be of the same kind . In that sense , each matrix can be seen as unit cell of the overall matrix, the unit cells being repeated periodically . That the matrices are di f ferent to each other is likewise possible . As mentioned above , each matrix comprises a plurality of receiving elements . Thus , in typical applications the sensor arrangement comprises about four millions of receiving elements , which are embedded in an overall matrix comprising about two thousand rows and columns , respectively . The overall matrix can be formed as large as required in order to achieve a suf ficient image resolution .

I f the matrix has n rows and m columns , the overall matrix can have a times n rows and b times m columns , wherein a, b, m and n are integers . However, the overall matrix could also be chopped . In this case , matrices at the margin of the overall matrix can have a lower number of rows and/or columns . This is because the image ' s height and/or width does not need to be an integer multiple of the matrix' s height and/or width .

In some embodiments of the sensor arrangement receiving elements have a top surface of rectangular, in particular of square , shape .

This means that in a top view receiving elements have a rectangular shape , for example a square shape . Receiving elements of rectangular or square shape can be combined to arrays and matrices , respectively .

In some embodiments of the sensor arrangement the receiving elements comprise a sensor element , in particular a photodiode . Each receiving element of the sensor arrangement is configured to capture optical information that is incident upon the respective receiving element and to generate electrical signals representative of the optical information . Especially for image sensors fabricated according to standard CMOS technologies , the working principle of the receiving elements is the conversion of optical intensity into a photocurrent using a photodiode . Silicon-based photodiodes are a common choice in this connection, as these diodes are sensitive over a broad wavelength range between 190 nm and 1100 nm and therefore cover the relevant part of the electromagnetic spectrum in both the visible and in the infrared domain . In addition, due to the large bandgap of silicon, silicon-based photodiodes show a superior noise performance compared to other photodiodes , such as germanium- based photodiodes .

In some embodiments , the sensor elements , in particular the photodiodes , are adj usted to a portion of the wavelength spectrum . This means that the sensor elements can be implemented di f ferently depending on the wavelength range to be detected by them . Thus , at least some of the sensor elements can have di f ferent characteristics such as being more sensitive to NIR light . The sensor elements , in particular the photodiodes , can convert optical information ef ficiently into electrical signals , which can be further evaluated by means of read-out circuitry .

In some embodiments of the sensor arrangement receiving elements further comprise a wavelength filter . For adj usting the sensitivity to a certain portion of the spectrum of incident electromagnetic radiation, in addition to a photodiode , each receiving element can comprise an optical wavelength filter that is arranged between a top surface of the receiving element , i . e . of the photodiode , and a source of the incident electromagnetic radiation .

The wavelength filter for each receiving element of the first , the second and the third type of receiving elements can be one of complementary color filters , for example according to the RGB additive color model . For instance , a red color filter is transmissive or translucent for red light but opaque for other light , particularly for green, blue and/or IR light . Hence , for each of the complementary colors red, green and blue , there is at least one receiving element of the first , the second or the third type of receiving elements that is sensitive for the respective complementary color . Here and in the following "transmissive" or "translucent" refers to a transparency of at least 60 % or at least 80 % .

Analogously, each receiving element of the fourth type of receiving elements can comprise an infrared filter, in particular a near-infrared filter . In order to provide a receiving element that is predominantly or exclusively sensitive to infrared light of a certain wavelength range , the receiving elements of the fourth type of receiving elements can comprise an infrared filter . The wavelength range at which said infrared filter is transmissive can be dependent on the spectrum of an illuminating light source such as an infrared LED, for instance . For example , the wavelength range of transmission of the infrared filter includes light at 940 nm or at 850 nm .

In some embodiments the sensitivity to speci fic wavelength domains is achieved by a combination of more than one filter . For example, a bandpass filter is combined with a cut-off filter. The bandpass filter may be transmissive for light of a specific color, while the cut-off filter may additionally block light in a different wavelength domain, e.g. ultraviolet (UV) light.

Furthermore, an image sensor is provided that comprises the sensor arrangement. This means that all features disclosed for the sensor arrangement are also disclosed for and applicable to the image sensor and vice-versa.

The image sensor further comprises circuitry for reading out electrical signals from the receiving elements. For example, for readout purposes the image sensor comprises storage capacitors, memory elements, an analog-to-digital converter (ADC) or the like. For the transfer of charges from the photodiodes to the circuitry the receiving elements can be connected to an accumulation node. Receiving elements of the same type can be connected to a respective shared accumulation node. In particular, if receiving elements of the same type are neighbored, they can be connected to a common accumulation node. In that way these receiving elements are fused and form a larger single receiving element. Such fused receiving elements can exhibit an enhanced quantum efficiency (QE) , since they have an increased overall top surface. Alternatively, all receiving elements are connected to an individual accumulation node.

Such an image sensor can be conveniently employed in electronic devices, such as smart phones, tablet computers, laptops, or camera modules. For example, the camera module is configured to operate in the visible domain for photography and/or video capturing and in the infrared domain for 3-D imaging and/or identi fication purposes . Moreover, image sensors with infrared sensitivity can be used in dark environments where video feed is required . Such application reach from mobile phone face unlock to automotive driver monitoring systems . Both deploy illuminators that are in the NIR spectrum, so that the phone user/driver is not blinded by the light that is illuminating him/her . This means that the illuminator, which may use flash light , does not disturb the person being filmed as this flash is in the invisible wavelength range , e . g . NIR light .

In some embodiments the image sensor further comprises an image signal processor, which is configured to generate a digital image based on the electrical signals from the receiving elements .

The image signal processor ( ISP ) maps mono-color picture elements to an array of poly-color picture elements , which is achieved by evaluating the color information from neighboring receiving elements . Moreover, the ISP may also be responsible for edge preservation of the image , among other tasks .

The image trans formation ( demosaicing) performed by this ISP may be di f ferent from conventional algorithms as described above in conj unction with conventional sensor arrangements employing Bayer patterns ( debayering) . This is because the proposed sensor arrangement comprises receiving elements which are arranged in a di f ferent manner than in Bayer patterns .

The obj ect is further solved by a method for producing a sensor arrangement . All features disclosed for the sensor arrangement are also disclosed and applicable to method for producing a sensor arrangement and vice-versa .

The method comprises providing at least three types of receiving elements , wherein the receiving elements of a particular type are configured to detect light in a respective wavelength range . The receiving elements are arranged in a matrix, wherein columns of the matrix comprise receiving elements of the at least three types . In the columns the receiving elements are arranged in predefined sequences such that the sequence of at least one column of the matrix is formed by the sequence of a respective preceding column, which is cyclically shi fted by at least one receiving element in a predefined direction .

By this producing method receiving elements of each type are distributed over the sensor arrangement in an ef fective way . The sensor arrangement comprises a suf ficiently large amount of receiving elements of each type per sensor area .

In a variant of the method or in an alternative method the matrix is formed such that each receiving element of a particular type , which is completely surrounded by other receiving elements , has at least one neighboring receiving element of each other type .

In some further variants of the method each receiving element of a particular type , which is completely surrounded by other receiving elements , i . e . each central receiving element , has at least two neighboring receiving elements of each other type . This property, that central receiving elements of a particular type have at least one or at least two neighboring receiving elements of other types , can be achieved, for example , i f columns of the matrix comprise receiving elements of each type . These are arranged in predefined sequences such that the sequence of each except a first column of the matrix is formed by the sequence of the respective preceding column, which is cyclically shi fted by at least one receiving element in the predefined direction .

The number of neighboring receiving elements of another type also depends on the total number of di f ferent types of receiving elements . For example , in case that only three di f ferent types of receiving elements are comprised by the sensor arrangement , a central receiving element can even have at least three neighboring receiving elements of each other type . In case that nine di f ferent types of receiving elements are used, a central receiving element can have exactly one neighboring receiving element of each other type . This is because rectangular receiving elements have eight neighboring receiving elements , which share a corner or an edge with the respective central receiving element .

In such sensor arrangements the receiving elements of each type are distributed over the sensor arrangement in an ef fective way . Additionally, the sensor arrangement comprises a suf ficiently large amount of receiving elements of each type per sensor area .

Further embodiments of the method become apparent to the skilled reader from the embodiments of the receiving element arrangement described above . BRIEF DESCRIPTION OF THE DRAWINGS

The following description of figures may further illustrate and explain aspects of the improved concept . Components and parts of the sensor arrangement that are functionally identical or have an identical ef fect are denoted by identical reference symbols . Identical or ef fectively identical components and parts might be described only with respect to the figures where they occur first . Their description is not necessarily repeated in successive figures .

Figures la-d show sensor arrangements to illustrate the improved concept .

Figure 2 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figure 3 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figure 4 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figure 5 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figure 6 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figures 7a-c show various sequences for the first column of a matrix comprised by a sensor arrangement .

Figure 8 shows a top view of an exemplary embodiment of a sensor arrangement according to the improved concept .

Figure 9 shows a perspective view on the sensor arrangement according to Fig . 3 .

Figure 10 shows a schematic diagram of an image sensor comprising a sensor arrangement .

DETAILED DESCRIPTION

Figures la to Id illustrate the idea on which the improved concept of a sensor arrangement 1 is based .

In Fig . la a top view of three consecutive columns 3 of an exemplary sensor arrangement 1 are shown . The columns comprise nine receiving elements 4 . The receiving elements 4 are denoted with numbers from -4 to +4 . Equally denoted receiving elements 4 correspond to receiving elements of a same type . Receiving elements 4 of a particular type are configured to detect light in a respective wavelength range , like the red, green, blue or IR wavelength range . Di f ferently denoted receiving elements 4 can correspond to receiving elements of di f ferent types . However, the denotation is rather exemplary so that di f ferently denoted receiving elements 4 can also correspond to receiving elements 4 of the same type . In any case , the sensor arrangement 1 comprises at least three di f ferent types of receiving elements 4 .

The receiving elements 4 are arranged in a matrix 2 . In the example of Fig . la the sensor arrangement 1 is formed by a matrix 2 with three identical columns 3 , thus forming a 9 x 3 matrix with nine rows 5 and three column 3 . The number of columns 3 and rows 5 is mainly arbitrary and may only depend on the number of different types of receiving elements 4. Columns 3 of the matrix 2 may comprise receiving elements 4 of each type, which are arranged in predefined sequences 6. This means that, with respect to different types of receiving elements 4, the sequence 6 of each column 3 is predefined from top to bottom. In the example of Fig. la the sequences 6 of receiving elements 4 are equal in each column 3. This means that receiving elements of respective rows 5 of the sensor arrangement 1 are of the same type. For example, the topmost receiving elements 4 of each column 3 have the same type, and therefore they each are denoted with +4.

In the matrix 2 of Fig. la a sub-matrix 7 is marked. The submatrix 7 is a 3 x 3 sub-matrix 7 with a central receiving element 8 in the center. The central receiving element 8, which is completely surrounded by other receiving elements 4, has eight direct neighboring receiving elements 4. Neighboring receiving elements 4 share at least an edge or a corner with each other. Since the receiving elements 4 of Fig. la have a top surface of rectangular shape, each receiving element 4, which is completely surrounded by other receiving elements 4, has exactly eight direct neighboring receiving elements 4.

In case that differently denoted receiving elements 4 correspond to receiving elements 4 of different types, the central receiving element 8 of Fig. la, which is denoted with =0, has neighboring receiving elements 4 of only two other types, which are denoted with +1 and -1. This situation is however not optimal, since for image transformation missing color information comes from neighboring receiving elements 4. In the present case the color information can be evaluated from only three types of receiving elements 4 (i.e. -1, =0, +1) , although color information from up to nine different types (i.e. -4 to +4) are present. However, this situation can be improved by the embodiments shown in Fig. lb to Id, which are described in the following.

In Fig. lb a top view of an embodiment of the sensor arrangement 1 is shown. Fig. lb may show at least a portion of a matrix 2 with three consecutive columns 3, the matrix 2 being comprised by the sensor arrangement 1. Elements of the embodiment according to Fig. lb that are similar to corresponding elements of the example according to Fig. la are designated with the same reference numerals. Fig. lb is different from Fig. la in that the sequence 6 of receiving elements 4 of a first column 3 is cyclically shifted upwards by one receiving element 4. The sequence 6' ' of receiving elements 4 of a third column 3' ' is cyclically shifted downwards by one receiving element 4. The cyclic shift is indicated by arrows.

Fig. lb can also be interpreted in such a way, that the sequence 6' of a second column 3' is downwards cyclically shifted by one receiving element 4 with respect to the sequence 6 of the first column 3. The sequence 6' ' of the third column 3' ' is downwards cyclically shifted by one receiving element 4 with respect to the sequence 6' of second column 3' .

In general, the sequence 6' of at least one column 3' of the matrix 2 is formed by the sequence 6 of a respective preceding column 3, which is cyclically shifted by at least one receiving element 4 in a predefined direction. In other words, a subsequent column 3' comprises a modified sequence 6' of receiving elements 4, wherein the modified sequence 6' is formed by a cyclic shift of the sequence 6 of the respective preceding column 3.

Looking at the sub-matrix 7 with the central receiving element 8, it can be seen that the central receiving element 8 has neighboring receiving elements 4 of four other types, which are designated with ±1 and ±2, respectively. This means that by the aforementioned shift the central receiving element 8 comprises direct neighboring receiving elements 4 of two more types (i.e. -2 and +2) than in the example of Fig. la. Also other receiving elements 4, which are completely surrounded by further receiving elements 4, comprise neighboring receiving elements 4 of four other 4 types .

The embodiment of Fig. 1c is similar to the embodiment of Fig. lb. Here, subsequent columns 3' , 3' ’ comprise modified sequences 6' , 6' ' of receiving elements 4, wherein each modified sequence 6' , 6' ' is formed by the sequence 6, 6' of the respective preceding column 3, 3' , which is cyclically shifted by two receiving elements 4. Looking again at the sub-matrix 7, the central receiving element 8 of this embodiment have neighboring receiving elements 4 of six other types, which are designated with ±1, ±2 and ±3, respectively. This means that by the shift (cyclic shifting by two receiving elements) central receiving elements 8 comprise direct neighboring receiving elements 4 of four more types (i.e. -2, +2, -3 and +3) than in the example of Fig. la.

The embodiment of Fig. Id is similar to the embodiment of Fig. 1c. Here, subsequent columns 3' , 3' ’ comprise modified sequences 6' , 6' ’ of receiving elements 4, wherein each modified sequence 6' , 6' ' is formed by the sequence 6, 6' of the respective preceding column 3, 3' which is cyclically shifted by three receiving elements 4. Looking again at the sub-matrix 7, central receiving elements 8 of this embodiment, have neighboring receiving elements 4 of eight other types, which are designated with ±1, ±2, ±3 and ±4, respectively. This means that by the shift (cyclic shift by three receiving elements) central receiving elements 8 comprise neighboring receiving elements 4 of six more types (i.e. -2, +2, -3, +3, -4 and +4) than in the example of Fig. la. In other words, each central receiving element 8 comprises neighboring receiving elements 4 of altogether eight other types.

In conclusion, starting with a column 3 having a predefined sequence 6 of receiving elements 4 of different types, subsequent columns 3' can be added to form a matrix 2 of receiving elements 4. The subsequent columns 3' can have modified sequences 6' which are formed by cyclically shifting the sequence 6 of the respective preceding column 3. The improved concept of the sensor arrangement 1 is based on the insight that by such shift operations the number of different types of neighboring receiving elements 4 can be increased. In this way, the image transformation conducted by an image signal processor can be performed more accurately, since the distribution of receiving elements 4 of different types over the matrix 2 is more effective.

Figure 2 shows a top view of another exemplary embodiment of the sensor arrangement 1. The sensor arrangement 1 of Fig. 2 comprises four 3 x 3 matrices 2 which are arranged adjacent to each other in lateral directions x, y. Lateral directions x, y run parallel to a main plane of extension of the sensor arrangement 1. This means that the matrices can share common borders with each other . The common border is indicated by dashed lines .

It is noted that the sensor arrangement 1 may comprise further matrices 2 , which are arranged in a similar manner next to the matrices 2 shown in Fig . 2 . This means that further matrices 2 may expand the sensor arrangement 1 in each lateral direction x, y, as indicated by the ellipses . The matrices 2 of the embodiment of Fig . 2 are equal . However, further matrices 2 (not shown) , which are provided to expand the sensor arrangement 1 , could be chopped of , i f they are arranged at the edges of the sensor arrangement 1 .

The matrices 2 of Fig . 2 comprise three types of receiving elements 4 , which are arranged in three columns 3 , 3 ' , 3 ' ’ and three rows 5 . For example , a first type 9 of receiving elements 4 may be configured to detect light in the red wavelength range . A second type 10 of receiving elements 4 may be configured to detect light in the green wavelength range . A third type 11 of receiving elements 4 may be configured to detect light in the blue wavelength range . However, the assignment to wavelength ranges is merely arbitrary and depends on speci fic applications .

The receiving elements 4 in each matrix 2 are arranged according to a pattern . The pattern is formed in the following way : in the first column 3 the receiving element 4 of the first type 9 is arranged at the topmost position, while the receiving element 4 of the second type 10 is arranged at the second topmost position and the receiving element 4 of the third type 11 is arranged at the bottom position of the first column 3 . Thus , the receiving elements 4 are arranged according to a predefined sequence 6 . The sequence 6 ' of the second column 3 ' is formed by cyclically shi fting the sequence 6 of the first column 3 downwards by one receiving element 4 . This means that the in the second column 3 ' the receiving element 4 of the first type 9 is arranged at the second topmost position, while the receiving element 4 of the second type 10 is arranged at the bottom position and the receiving element 4 of the third type 11 is arranged at the topmost position . Thus , the receiving elements 4 of the second column 3 ' are arranged according to a modi fied sequence 6 ' .

The sequence 6 ' ' of the third column 3 ' ' is formed by cyclically shi fting the sequence 6 ' of the second column 3 ' downwards by one receiving element 4 . This means that the in the third column 3 ' ' the receiving element 4 of the first type 9 is arranged at the bottom position, while the receiving element 4 of the second type 10 is arranged at the topmost position and the receiving element 4 of the third type 11 is arranged at the second topmost position . Thus , also the receiving elements 4 of the second column 3 ' ' are arranged according to a further modi fied sequence 6 ' ' .

In the sensor arrangement 1 according to Fig . 2 each receiving element 4 of a particular type , which is completely surrounded by other receiving elements 4 , has three neighboring receiving elements 4 of each other type . Besides , it has two neighboring receiving elements 4 of the same type .

In Fig . 3 an exemplary embodiment comprising a 5 x 5 matrix with four di f ferent types of receiving elements 4 is shown . For example and as in the previous embodiment , the receiving elements 4 of the first type 9 , the second type 10 and the third type 11 can be configured to detect light in the visible wavelength range (Red, Green, Blue) . Receiving elements 4 of a fourth type 12 may be configured to detect light in the infrared wavelength range. However, the assignment to specific wavelength ranges can also be different .

In the embodiment according to Fig. 3, in the columns 3 of the matrix 2 the number of receiving elements 4 of the second type 10 exceeds the number of receiving elements 4 of other types. This way, the sensor arrangement 1 can be more sensitive to a specific wavelength range. For example, the sensor arrangement 1 can be more sensitive to the green wavelength range, because the human is most sensitive to green .

In the sensor arrangement 1 of Fig. 3 the first column 3 is formed by receiving elements 4, which are arranged from top to bottom in a predefined sequence 6. In this case, the first topmost receiving element 4 is of the first type 9, the second receiving element 4 is of the second type 10, the third receiving element 4 is of the third type 11, the fourth receiving element 4 is of the fourth type 12 and the fifth receiving element 4 at the bottom of the first column 3 is again of the second type 10. However, this specific sequence 6 is arbitrary and can also be changed.

Subsequent columns 3' of the matrix 2 shown in Fig. 3 are formed by modifying that sequence 6. In particular, subsequent columns 3' comprise modified sequences 6' of receiving elements 4, wherein the respective modified sequence 6' is formed by the sequence 6, of the respective preceding column 3, which is cyclically shifted by one receiving element 4. The cyclic shift is downwards, which means that if a specific receiving element 4 is at the topmost position in the preceding column 3, such receiving element 4 is in the second topmost position in the subsequent column 3' .

It is noted that the sensor arrangement 1 may comprise further matrices 2, which are arranged in a similar manner next to the matrix 2 shown in Fig. 3. This means that further matrices 2 may expand the sensor arrangement 1 in each lateral direction x, y, as indicated by the ellipses.

The sensor arrangement 1 of Fig. 3 has the property that each receiving element 4 of a particular type, which is completely surrounded by other receiving elements 4, has at least one neighboring receiving element 4 of each other type. Moreover, each receiving element 4, which is completely surrounded by other receiving elements 4, has more neighboring receiving elements 4 of the second type 10 as receiving elements 4 of other types.

In Fig. 4 another exemplary embodiment comprising a 5 x 5 matrix with four different types of receiving elements 4 is shown. This embodiment is similar to the embodiment of Fig. 3, but differs in that subsequent columns 3' of the matrix 2 are constructed in a different way: they comprise modified sequences 6' of receiving elements 4, wherein the respective modified sequence 6' is formed by the sequence 6 of the respective preceding column 3, which is cyclically shifted by two receiving elements 4. The cyclic shift is downwards. This means, for example, that if a specific receiving element 4 is at the topmost position in the preceding column 3, such receiving element 4 is in the third topmost position in the subsequent column 3' . The sensor arrangement 1 of Fig . 4 has the property that each receiving element 4 of a particular type , which is completely surrounded by other receiving elements 4 , has at least two neighboring receiving element 4 of each other type . Moreover, each receiving element 4 , which is completely surrounded by other receiving elements 4 , has at least as much neighboring receiving elements 4 of the second type 10 as receiving elements 4 of other types .

Accordingly, Figs . 5 and 6 show exemplary embodiments similar to the embodiments of Figs . 3 and 4 , in which the sequence 6 ' of receiving elements 4 in a subsequent column 3 ' is formed by the sequence 6 of a respective preceding column 3 , which is cyclically shi fted by three or four receiving elements 4 , respectively .

The properties of the sensor arrangement 1 of Fig . 5 are similar to those of Fig . 4 . This means that each receiving element 4 of a particular type , which is completely surrounded by other receiving elements 4 , has at least two neighboring receiving element 4 of each other type and at least as much neighboring receiving elements 4 of the second type 10 as receiving elements 4 of other types .

The properties of the sensor arrangement 1 of Fig . 6 are similar to those of Fig . 3 . This means that each receiving element 4 of a particular type , which is completely surrounded by other receiving elements 4 , has at least one neighboring receiving element 4 of each other type and more neighboring receiving elements 4 of the second type 10 as receiving elements 4 of other types . In the embodiments described above the sequence 6' of each except a first column of the matrix 2 is formed by shifting the sequence 6 of the respective preceding column 3. Therefore, the exact pattern of the matrix 2 also depends on the sequence 6 of the first column 3. However, that sequence 6 is rather arbitrary. Without claiming completeness Figs. 7a-c show possible sequences 6 of the first column 3 of the matrix 2 according to the previous embodiments.

Moreover, the matrix 2 is not limited to be a 3 x 3 matrix 2 as shown in Fig. 2 or to be a 5 x 5 matrix 2 as shown in Figs. 3 to 6. In contrast, any matrix 2 is possible, which comprises at least three columns 3 and at least three rows 5. The number of rows and the number of columns can be chosen independently. For example, Fig. 8 shows a 6 x 6 matrix comprising four different types of receiving elements 4. The sequence 6' of subsequent columns 3' is formed by cyclic shifting the sequence 6 of the respective preceding column 3 by three receiving elements 4, whereby in this specific case it is equivalent in which of the two directions the sequence 6 is shifted.

In the embodiment of Fig. 8 the percentage of receiving elements 4 of the second type 10 is even larger than in the previous embodiments, as each column 3, 3' is 50% filled with receiving elements 4 of the second type 10. All other features, which have been described in context of previous Figures, may also apply in a same or similar way to the embodiment shown in Fig. 8.

It is noted that all embodiments may also be combined with each other such that an overall sensor arrangement 1 is formed by combining the sensor arrangements 1 according to

Figs . 1 to 8 .

Fig . 9 shows a perspective view on the sensor arrangement 1 according to Fig . 3 . The dashed lines indicate that further matrices 2 can be arranged next to it in lateral directions x, y such that the complete sensor arrangement 1 is formed . The matrix 2 comprises a substrate 13 in which sensor elements 14 are embedded . The sensor elements 14 each can be formed in the same substrate 13 , for example a semiconductor substrate 13 . Each sensor element 14 comprises a top surface 15 .

In a vertical direction z , which is perpendicular to the main plane of extension of the sensor arrangement 1 , a filter layer 16 is arranged on the top surfaces 15 of the sensor elements 14 . The filter layer 16 comprises wavelength filters 17 , such that they form the pattern as described above . The wavelength filters 17 are arranged between the top surfaces 15 of the sensor elements 14 and a source of the incident electromagnetic radiation (not shown) . This way, the underlying sensor elements 14 detect light in that speci fic wavelength domain, for which the respective wavelength filter 17 is transparent .

Fig . 10 shows a schematic diagram of an exemplary embodiment of an image sensor 18 comprising the sensor arrangement 1 as discussed above . The image sensor 18 further comprises circuitry 19 for reading out electrical signals from the receiving elements 4 . For example , the circuitry 19 may include storage capacitors , memory elements , an analog-to- digital converter (ADC ) or the like . The circuitry 19 is electrically connected to the receiving elements 4 of the sensor arrangement 1 . It is noted that the sensor arrangement 1 may comprise a plurality of receiving elements 4 . The circuitry 19 and the sensor arrangement 1 may be integrated on a sensor chip 20 . The image sensor 18 further comprises an image signal processor 21 , ISP, which is configured to generate a digital image based on the electrical signals from the receiving elements 4 . Therefore , the ISP 21 is electrically connected to the circuitry 19 for reading out the electrical signals from the receiving elements 4 . The ISP 21 may form a chip separate from the sensor chip 20 .

The embodiments of the sensor arrangement 1 and the method of producing the sensor arrangement 1 disclosed herein have been discussed for the purpose of familiari zing the reader with novel aspects of the idea . Although preferred embodiments have been shown and described, many changes , modi fications , equivalents and substitutions of the disclosed concepts may be made by one having skill in the art without unnecessarily departing from the scope of the claims .

It will be appreciated that the disclosure is not limited to the disclosed embodiments and to what has been particularly shown and described hereinabove . Rather, features recited in separate dependent claims or in the description may advantageously be combined . Furthermore , the scope of the disclosure includes those variations and modi fications , which will be apparent to those skilled in the art and fall within the scope of the appended claims .

The term " comprising" , insofar it was used in the claims or in the description, does not exclude other elements or steps of a corresponding feature or procedure . In case that the terms " a" or " an" were used in conj unction with features , they do not exclude a plurality of such features . Moreover, any reference signs in the claims should not be construed as limiting the scope .

This patent application claims the priority of German patent application 102020129181 . 7 , the disclosure content of which is hereby incorporated by reference .

Reference symbols

1 sensor arrangement

2 matrix

3 , 3 ’ , 3 ’ ’ columns of matrix

4 receiving element

5 rows of matrix

6 , 6 ' , 6 ' ’ sequences of receiving elements

7 sub-matrix

8 central receiving element

9 first type of receiving elements

10 second type of receiving elements

11 third type of receiving elements

12 fourth type of receiving elements

13 substrate

14 sensor element

15 top surface of receiving element

16 filter layer

17 wavelength filter

18 image sensor

19 circuitry

20 sensor chip

21 image signal processor x, y lateral directions z vertical direction

Claims

1. Sensor arrangement (1) comprising

- at least four types of receiving elements (4) , wherein the receiving elements (4) of a particular type are configured to detect light in a respective wavelength range, wherein

- receiving elements (4) of a first type (9) are configured to detect light in the red wavelength range,

- receiving elements (4) of a second type (10) are configured to detect light in the green wavelength range,

- receiving elements (4) of a third type (11) are configured to detect light in the blue wavelength range, and

- receiving elements (4) of a fourth type (12) are configured to detect light in the infrared wavelength range,

- the receiving elements (4) are arranged in a matrix (2) ,

- columns (3, 3' ) of the matrix comprise receiving elements (4) of the at least four types which are arranged in predefined sequences (6, 6' ) such that

- the sequence (6' ) of at least one column (3' ) of the matrix is formed by the sequence (6) of a respective preceding column (3) , which is cyclically shifted by at least one receiving element (4) in a predefined direction.

2. Sensor arrangement (1) according to the preceding claim, wherein the sequence (6' ) of each except a first column (3' ) of the matrix (2) is formed by the sequence (6) of the respective preceding column (3) , which is cyclically shifted by at least one receiving element (4) in the predefined direction .

3. Sensor arrangement (1) according to one of the preceding claims, wherein the matrix (2) is formed such that each 38 receiving element (4) of a particular type, which is completely surrounded by other receiving elements (4) , has at least one neighboring receiving element (4) of each other type or at least two neighboring receiving elements (4) of each other type.

4. Sensor arrangement (1) according to one of the preceding claims, wherein the matrix (2) is an m x n matrix (2) with m and n being at least 3, and wherein the sequence (6' ) of at least one column (3' ) of the matrix (2) is formed by the sequence (6) of the respective preceding column (3) , which is cyclically shifted in the predefined direction by at least one receiving element (4) and at most m-1 receiving elements (4) .

5. Sensor arrangement (1) according to one of the preceding claims, wherein in the columns (3, 3' ) of the matrix (2) the number of receiving elements (4) of a specific type exceeds the number of receiving elements (4) of other types.

6. Sensor arrangement (1) according to the preceding claim, wherein the matrix (2) is formed such that each receiving element (4) , which is completely surrounded by other receiving elements (4) , has at least as much neighboring receiving elements (4) of the specific type as receiving elements (4) of other types.

7. Sensor arrangement (1) according to one of the preceding claims, comprising at least two matrices (2) as described in one of the preceding claims, wherein the matrices (2) are arranged adjacent to each other in a main plane of extension of the sensor arrangement (1) .

8. Sensor arrangement (1) according to one of the preceding claims, wherein receiving elements (4) have a top surface (15) of rectangular, in particular of square, shape.

9. Sensor arrangement (1) according to one of the preceding claims, wherein receiving elements (4) comprise a sensor element (14) , in particular a photodiode.

10. Sensor arrangement (1) according to one of the preceding claims, wherein receiving elements (4) further comprise a wavelength filter (17) .

11. Image sensor (18) comprising the sensor arrangement (1) of one of the preceding claims, the image sensor (18) further comprising circuitry (19) for reading out electrical signals from the receiving elements (4) .

12. Image sensor (18) according to the preceding claim, further comprising an image signal processor (21) , which is configured to generate a digital image based on the electrical signals from the receiving elements (4) .

13. Method for producing a sensor arrangement (1) , the method comprising

- providing at least four types of receiving elements (4) , wherein the receiving elements (4) of a particular type are configured to detect light in a respective wavelength range, wherein

- receiving elements (4) of a second type (10) are configured to detect light in the green wavelength range, - receiving elements (4) of a third type (11) are configured to detect light in the blue wavelength range, and

- arranging the receiving elements (4) in a matrix (2) , wherein

- the sequence (6' ) of at least one column (3' ) of the matrix (2) is formed by the sequence (6) of a respective preceding column (3) , which is cyclically shifted by at least one receiving element (4) in a predefined direction.

14. Method according to the preceding claim, wherein the matrix (2) is formed such that each receiving element (4) of a particular type, which is completely surrounded by other receiving elements (4) , has at least one neighboring receiving element (4) of each other type or at least two neighboring receiving elements (4) of each other type.