Patent Publication Number: US-2023133741-A1

Title: Far infrared sensor apparatus having multiple sensing element arrays inside single package

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 16/294,873, filed on Mar. 6, 2019, which is a continuation application of U.S. application Ser. No. 15/394,844, filed on Dec. 30, 2016. The contents of these applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to infrared detection, and more particularly, to a far infrared sensing device having multiple far infrared sensing element arrays combined and arranged in a single package. 
     2. Description of the Prior Art 
     Typically, in order to detect distribution of thermal radiation, it needs a sensor with sensing elements of array structure to measure infrared light radiating over the space.  FIG.  1    illustrates a conventional infrared sensor package  100  including an 8×8 sensing element array. The infrared sensor package  100  comprises a package body  110 , a filter  120 , an infrared sensor array integrated circuit  130  and a circuit board  140 . The infrared sensor array integrated circuit  130  comprises a sensing element array  135  and a control circuit (not shown) for controlling operations of the sensing element array  135 . 
     Thermal radiation is the emission of electromagnetic waves. Therefore, only the light with specific temperature range (e.g. specific wavelength) can pass through the filter  120 . When the infrared light applies onto the sensing element array  135 , each sensing elements therein have physical changes at different extents. The physical changes will be further converted to electrical signals. Taking the thermopile sensing element as an example, the infrared light is absorbed by the sensing element and converted to thermal energy. The thermal energy will lead to potential difference between two terminals of the sensing element. Then, the sensing control circuit can detect the potential difference, thereby obtaining the sensed signal. 
     When sensors suppliers manufacture the sensing element array, such as the sensing element array  135 , they may produce sensing element arrays having different dimensions in order to meet different customers&#39; requirements. This means sensors suppliers have to set up production lines dedicated to different sensor dimensions. However, different production lines lead to lower overall productivity and higher manufacturing costs. 
     SUMMARY OF THE INVENTION 
     In order to improve the flexibility and efficiency in manufacturing and reduce the manufacturing costs, the present invention proposes an innovative design approach of the infrared sensor array, which facilitates realizing the modular design and modular production for the infrared sensor. 
     According to one embodiment of the present invention, a far infrared sensor package is provided. The far infrared sensor package comprises: a package body and a plurality of far infrared sensor array integrated circuits. The plurality of far infrared sensor array integrated circuits are disposed on a same plane and inside the package body, wherein each of the far infrared sensor array integrated circuits includes a far infrared sensing element array of a same size. Additionally, a first far infrared sensor array integrated circuit of the plurality of far infrared sensor array integrated circuits includes a first sensing control circuit, and the first sensing control circuit performs a compensation computation according to a plurality of sensed signals derived respectively from a plurality of far infrared sensing element arrays. A second far infrared sensor array integrated circuit of the plurality of far infrared sensor array integrated circuits includes an far infrared sensing element array that is coupled to the first sensing control circuit. Each of a plurality of third far infrared sensor array integrated circuits of the plurality of far infrared sensor array integrated circuits includes a third sensing control circuit, and the third sensing control circuit includes a computation circuit for compensation computation that is disabled. The first sensing control circuit is arranged to read a plurality of second sensed signals of the sensed signals from the far infrared sensing element array of the second and the third far infrared sensor array integrated circuits, and performs the compensation computation according to the plurality of sensed signals. The second far infrared sensor array integrated circuit does not include a sensing control circuit. 
     According to one embodiment, a far infrared sensor package is provided. The far infrared sensor package comprises: a package body and a plurality of far infrared sensor array integrated circuits. The plurality of far infrared sensor array integrated circuits are disposed on a same plane and inside the package body, wherein each of the far infrared sensor array integrated circuits includes a far infrared sensing element array of a same size. Additionally, a first far infrared sensor array integrated circuit of the plurality of far infrared sensor array integrated circuits includes a first sensing control circuit, and the first sensing control circuit performs a compensation computation according to a plurality of sensed signals derived respectively from a plurality of far infrared sensing element arrays. At least one second far infrared sensor array integrated circuit of the plurality of far infrared sensor array integrated circuits includes a second sensing control circuit. A function providable by the first sensing control circuit is different from functions providable by the second sensing control circuit. Each of the first sensing control circuit and the second sensing control circuit includes a computation circuit for compensation computation, and only one of computation circuits of the first sensing control circuit and the second sensing control circuit is enabled. 
     According to one embodiment, a far infrared sensor array integrated circuit combination is provided. The far infrared sensor array integrated circuit combination comprises: a first far infrared sensor array integrated circuit including a first far infrared sensing element array and a first sensing control circuit; and a plurality of second far infrared sensor array integrated circuits, at least one including a second far infrared sensing element array and a second sensing control circuit. Additionally, a size of the first far infrared sensing element array is substantially consistent with a size of the second far infrared sensing element array and a function providable by the first sensing control circuit is different from functions providable by the second sensing control circuit. A size of the first sensing control circuit is not consistent with a size of the second sensing control circuit. Each of the first sensing control circuit and the second sensing control circuit includes a computation circuit for compensation computation, and only one of computation circuits of the first sensing control circuit and the second sensing control circuit is enabled. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates structure of a conventional infrared sensor package. 
         FIG.  2    illustrates structure of a far infrared sensor package according to one embodiment of the present invention. 
         FIG.  3    illustrates a simplified diagram of a far infrared sensor array integrated circuit according to one embodiment of the present invention. 
         FIG.  4    illustrates a diagram of a far infrared sensor array integrated circuit combination according to one embodiment of the present invention. 
         FIGS.  5 A- 5 D  illustrates diagrams of far infrared sensor array integrated circuit combinations according to various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terms are used throughout the following descriptions and claims to refer to particular system components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not differ in functionality. In the following discussion and in the claims, the terms “include”, “including”, “comprise”, and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” The terms “couple” and “coupled” are intended to mean either an indirect or a direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
       FIG.  2    illustrates a sectional view of structure of a far infrared sensor package according to one embodiment of the present invention. As illustrated, a far infrared sensor package  200  has a package body  210 , an optical element  220 , a far infrared sensor array integrated circuit combination  230  and a circuit board  240 . The far infrared sensor array integrated circuit combination  230  comprises a plurality of far infrared sensor array integrated circuits  231 _ 1 - 231 _N that are substantially mounted on a same plane. At least one of the far infrared sensor array integrated circuits  231 _ 1 - 231 _N is basically as illustrated by  FIG.  3   , and includes a far infrared sensing element array  310 _N and a sensing control circuit  320 _N. The far infrared sensing element array  310 _N comprises a plurality of sensing elements that are arranged in form of array. Please note that the far infrared sensing element array  310 _N is described as an 8×8 sensing element array in the following descriptions. However, this is just intended for illustrative purposes rather than limitations. The optical element  220  is lens having specialized coatings thereon. When the thermal radiation applies on the optical element  220 , the infrared light with specific temperatures/wavelengths could pass through. Each sensing element in the far infrared sensing element array  310 _N will have physical change corresponding to the intensity of received infrared light, thereby forming a sensed signal. The sensing control circuit  320 _N is utilized for (but not limited to) controlling a driving operation regarding each sensing element and a reading operation regarding the sensed signal of each sensing element in the far infrared sensing element array  310 _N. Additionally, the sensing control circuit  320 _N may comprise (but not limited to) a driver, a multiplexer, an analog-to-digital converter and a register for facilitating the driving and reading operation as well as a computation circuit for performing a compensation computation. In one embodiment, the far infrared sensing element can be implemented with thermopile structure. However, such implementation is not the only one and a limitation of the present invention. Further, the sizes of far infrared sensing element arrays  310 _ 1 - 310 _N in the far infrared sensor array integrated circuits  231 _ 1 - 231 _N are basically identical. Preferably, the far infrared sensor array integrated circuits  231 _ 1 - 231 _N are applicable to detecting the light with wavelength longer than 3 μm. 
       FIG.  4    illustrates a plain view of structure of the far infrared sensor array integrated circuit combination  230  according to one embodiment of the present invention. As illustrated, the far infrared sensor array integrated circuit combination  230  is composed of far infrared sensor array integrated circuits  231 _ 1 - 231 _ 4 . The far infrared sensor array integrated circuit  231 _ 1  comprises a far infrared sensing element array  310 _ 1  and a sensing control circuit  320 _ 1 . The far infrared sensor array integrated circuit  231 _ 2  comprises a far infrared sensing element array  310 _ 2  and a sensing control circuit  320 _ 2 ; the far infrared sensor array integrated circuit  231 _ 3  comprises a far infrared sensing element array  310 _ 3  and a sensing control circuit  320 _ 3 ; the far infrared sensor array integrated circuit  231 _ 4  comprises a far infrared sensing element array  310 _ 4  and a sensing control circuit  320 _ 4 . A valid sense region of the far infrared sensor array integrated circuit combination  230  is substantially equal to the area  280 . Infrared light passing through the optical element  220  will be gathered onto the area  280 . Subsequently, the far infrared sensing element arrays  310 _ 1 - 310 _ 4  generate corresponding sensed signals. Inside the area  280 , there is an region  282  that is not covered with any sensing elements. Therefore, at least one of the sensing control circuits  320 _ 1 - 320 _ 4  employs the sensed signals of the sensing elements adjacent to the region  282 , to perform a compensation computation, which generates estimated sensed signals regarding the region  282 . In one embodiment, the compensation computation is an interpolation, which computes average values of the sensed signals of the sensing elements adjacent to the region  282 . The average values will be used as sensed signals corresponding to the region  282 . 
     The far infrared sensor array integrated circuits  231 _ 1 - 231 _N in the far infrared sensor array integrated circuit combination  230  are interconnected through wires. In one embodiment, the far infrared sensor array integrated circuits  231 _ 1 - 231 _N have bonding pads thereon. By means of wire bonding, the far infrared sensor array integrated circuits are interconnected. One of the far infrared sensor array integrated circuits  231 _ 1 - 231 _N is arranged for collecting and integrating sensed signals obtained from other far infrared sensor array integrated circuits, and accordingly, performs the compensation computation on these sensed signals to obtain the sensed signals corresponding to the region  282 . Taking the embodiment of  FIG.  4    as an example, the sensing control circuit  320 _ 4  of the far infrared sensor array integrated circuit  231 _ 4  is provided with a computation circuit  322 _ 4 , which is employed for collecting and integrating those sensed signals read by other far infrared sensor array integrated circuits. Additionally, through an input interface, bonding pads and wires that are coupled to the far infrared sensor array integrated circuits  231 _ 1 - 231 _ 3 , the sensing control circuit  320 _ 4  derives the sensed signals read by the sensing control circuit  320 _ 1 - 320 _ 3  corresponding to the far infrared sensing element arrays  310 _ 1 - 310 _ 3 . Afterwards, the computation circuit  322 _ 4  performs the compensation computation according to the sensed signals obtained from the far infrared sensing element arrays  310 _ 1 - 310 _ 4  and integrates the result of the compensation computation with the sensed signals, thereby obtaining 16×16 sensed results. Through an output interface, the bonding pads and wires that are connected to the circuit board  240 , the sensed results are sent to external devices. 
     In one embodiment, the sensing control circuits  320 _ 1 - 320 _ 4  may have identical circuitry and manufactured by an identical process. During the process of integrating the far infrared sensor array integrated circuits  231 _ 1 - 231 _ 4  to form the far infrared sensor array integrated circuit combination  230 , some functions providable by the sensing control circuits  320 _ 1 - 320 _ 3  may be disabled. In addition, some contacts of interfaces of the sensing control circuits  320 _ 1 - 320 _ 3  may not be coupled to the bonding pads of the far infrared sensor array integrated circuits  231 _ 1 - 231 _ 3 . Specifically, each of the sensing control circuits  320 _ 1 - 320 _ 3  may include the computation circuit. However, after the far infrared sensor array integrated circuit combination  230  is formed, these computation circuits will be disabled. The sensing control circuits  320 _ 1 - 320 _ 3  may have the input/output interface of the width that is consistent with the width of the input/output interface of the sensing control circuit  320 _ 4 . However, after forming the far infrared sensor array integrated circuit combination  230 , the sensing control circuits  320 _ 1 - 320 _ 3  only reserve a portion of the interface that is wide enough for outputting the sensed signals to the sensing control circuit  320 _ 4 . Such design thinking is to simplify design and manufacturing process of the far infrared sensor array integrated circuits  231 _ 1 - 231 _ 4 . However, in some applications, in order to satisfy other design requirements, the sensing control circuit may have different circuitry and made by different manufacturing processes, which will be explained later. 
       FIGS.  5 A- 5 D  illustrate different arrangements of the far infrared sensor array integrated circuits  231 _ 1 - 231 _N in the far infrared sensor array integrated circuit combination  230  according to various embodiments of the present invention. The far infrared sensor array integrated circuits  231 _ 1 - 231 _N may be in a side-by-side arrangement as shown by  FIG.  5 A  or in a head-to-tail arrangement as shown by  FIG.  5 B . Alternatively, the far infrared sensor array integrated circuits  231 _ 1 - 231 _N may be arranged in a mixed arrangement as illustrated by  FIG.  5 C . In the arrangement shown by  FIG.  5 B , there are large gap areas between neighboring far infrared sensor array integrated circuits  231 _ 1 - 231 _N. Those large gap areas are not covered by the far infrared sensing element arrays, which causes the compensation computation to be more difficult and complicated. In order to overcome such problem, some of the far infrared sensor array integrated circuits  231 _ 1 - 231 _N, such as, the far infrared sensor array integrated circuits  231 _ 2 - 231 _ 3 , comprise simplified sensing control circuits  320 _ 2 - 320 _ 3  whose circuit size is smaller. Compared to the sensing control circuit  320 _ 1 , the sensing control circuits  320 _ 2 - 320 _ 3  may not include the computation circuit for performing the compensation computation. The sensing control circuits  320 _ 2 - 320 _ 3  may only include circuit blocks for driving and reading the sensing element arrays  310 _ 2 - 310 _ 3 . By scaling down the sizes of the sensing control circuits, the gap areas that are not covered by the far infrared sensing element arrays in specific arrangements. In the embodiment illustrated by  FIG.  5 C , the far infrared sensor array integrated circuits  231 _ 2  does not include the sensing control circuit, driving and reading operations regarding the far infrared sensing element array  310 _ 2  may be conducted by the sensing control circuits  320 _ 1  and  320 _ 3  of the far infrared sensor array integrated circuits  231 _ 1  and  231 _ 3 . In the embodiment of  FIG.  5 D , the far infrared sensor array integrated circuit combination  230  include far infrared sensor array integrated circuits  231 _ 1 - 231 _ 9 , where the far infrared sensor array integrated circuit  231 _ 5  only include the far infrared sensing element array  310 _ 5  but does not include the sensing control circuit. Sensed signals on the far infrared sensing element array  310 _ 5  can be read by the sensing control circuits in other far infrared sensor array integrated circuits. Furthermore, the sensing control circuit  320 _ 1  and  320 _ 9  in the far infrared sensor array integrated circuits  231 _ 1  and  231 _ 9  may both have enabled computation circuit for performing compensation computation. The sensing control circuits of the far infrared sensor array integrated circuits  231 _ 2 - 231 _ 4  and  231 _ 6 - 231 _ 8  may not have the computation circuit, or their computation circuits are not enabled. Alternatively, circuit blocks in the far infrared sensor array integrated circuits  231 _ 2 - 231 _ 4  and  231 _ 6 - 231 _ 8  that are intended for driving and/or reading operations may be disabled. These driving and/or reading operations are performed by the sensing control circuit  320 _ 1  and  320 _ 9  instead. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. Thus, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter. 
     In conclusion, by unifying the design and manufacturing of the far infrared sensor array integrated circuits, the sensors suppliers can easily manufacture the sensors with different dimensions to meet different customers&#39; requirements. In addition, the far infrared sensor array integrated circuits of the present invention have good flexibility in the design of the sensing control circuit. Sensing control circuit of different far infrared sensor array integrated circuits may have identical circuitry in the design and manufacture stages. However, in the actual applications, some circuit blocks in the sensing control circuit may be disabled if not necessary. Furthermore, in order to realize special arrangements of the infrared sensor array integrated circuit combination, some far infrared sensor array integrated circuits may not include a sensing control circuit or include a smaller sensing control circuit with different circuitry. As a result, the flexibility and the efficiency of manufacturing the far infrared sensor package can be improved. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.