Patent Publication Number: US-11032463-B2

Title: Image capture apparatus and control method thereof

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention is related to a technique for displaying a focus frame in an image. 
     Description of the Related Art 
     In digital cameras and digital video cameras, a live view image is displayed on a display or electronic view finder (EVF) in the camera or a display unit external to the camera, and shooting is performed while confirming a shooting target. 
     Also, an auto focus (AF) function is provided in digital cameras and digital video cameras. A photographer can confirm a focus position in the image by an AF function, but confirmation of the focus position is difficult in a small camera since the display is also small and the resolution is low. 
     Accordingly, as supplementary information for confirming the focus position in the image, for example, there is a method of displaying a frame at a focus position of the image, a method of enlarging and displaying a part of the image, and a method called peaking of thickly coloring a contour of an object in the display. Also, in Japanese Patent Laid-Open No. 2016-58764, a method of using object distance information to display only an image of a region that is in-focus, and not display other image regions is described. 
     However, in the foregoing conventional techniques, there are cases in which time is required for image processing, and the display processing for the guide for confirming the focus position in the image cannot follow the movement of an object or focus detection. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in consideration of the aforementioned problems, and realizes techniques for accelerating display processing for a guide for confirming a focus position in an image, and enabling display that follows object movement and focus detection. 
     In order to solve the aforementioned problems, the present invention provides an image capturing apparatus, comprising: a detector configured to detect a focus adjustment position in an image; a processor configured to generate a composite image in which a guide indicating the detected position is superimposed on the image; a display configured to display the composite image generated by the processor; and a controller configured to update, in accordance with information of the position detected by the detector, display information used for processing for generating the composite image. 
     In order to solve the aforementioned problems, the present invention provides a method for controlling an image capture apparatus having a detector, a processor, a display and a controller, the method comprising: detecting a focus adjustment position in an image; generating a composite image in which a guide indicating the detected position is superimposed on the image; displaying the composite image generated by the processor; and updating, in accordance with information of the position detected by the detector, display information used for processing for generating the composite image. 
     In order to solve the aforementioned problems, the present invention provides a non-transitory computer-readable storage medium storing a program for causing a computer to execute a method for controlling an image capture apparatus having a detector, a processor, a display and a controller, the method comprising: detecting a focus adjustment position in an image; generating a composite image in which a guide indicating the detected position is superimposed on the image; displaying the composite image generated by the processor; and updating, in accordance with information of the position detected by the detector, display information used for processing for generating the composite image. 
     According to the present invention, processing for displaying a guide for confirming a focus position in an image is accelerated, and display that follows object movement and focus detection is enabled. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a block diagram for illustrating an apparatus configuration of a first embodiment. 
         FIG. 1B  is a block diagram for illustrating an apparatus configuration of a second embodiment. 
         FIG. 2A  is a flowchart for illustrating AF frame display processing of the first embodiment. 
         FIG. 2B  is a flowchart for illustrating AF frame display processing of the second embodiment. 
         FIGS. 3A to 3E  are views for describing AF frame generation processing of the first embodiment. 
         FIGS. 4A to 4G  are views for describing AF frame generation processing of the second embodiment. 
         FIGS. 5A and 5B  are timing charts for illustrating AF frame display processing of the first and second embodiments. 
         FIGS. 6A and 6B  are views for exemplifying an AF frame and display information for the AF frame. 
         FIG. 7  is a view exemplifying an LUT used to generate an AF frame. 
         FIGS. 8A to 8C  are views for exemplifying pixel arrays of imaging elements. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will be described in detail below. The following embodiments are merely examples for practicing the present invention. The embodiments should be properly modified or changed depending on various conditions and the structure of an apparatus to which the present invention is applied. The present invention should not be limited to the following embodiments. Also, parts of the embodiments to be described later may be properly combined. 
     First Embodiment 
     In the first embodiment, description is given of AF frame display processing in which only AF frames corresponding to an in-focus position of an object in all AF frames arranged two-dimensionally in an imaging screen are displayed to be superimposed on a live view image, and the other AF frames are not displayed. 
     First, using  FIG. 1A , a configuration of an image capture apparatus of the first embodiment will be described. 
     The digital camera  10  of the present embodiment is not limited to a digital camera or a digital video camera having an autofocus function, and application to an information processing apparatus such as a mobile phone, to a smart device which is a type thereof, or to a tablet terminal that have a camera function is also possible. 
     An optical system  100  comprises an imaging lens, a shutter, an aperture, or the like. An image sensor  101  comprises an imaging element such as a CCD, a CMOS, or the like. The image sensor  101  photoelectrically converts the quantity of the light incident through the optical system  100  and a subject image that was formed by focus adjustment, and thereby generates an analog image signal. Also, the image sensor  101  has an AD conversion unit for converting an analog signal into a digital signal. In each pixel of an imaging element of the image sensor  101 , a color filter of either R (red), G (green), or B (blue) is arranged regularly in a mosaic, wherein, for example, there is a set of one red pixel, one blue pixel, and two green pixels for every four pixels. Such a pixel arranged is referred to as a Bayer array.  FIG. 8A  exemplifies a case in which, for each RGB pixel  801 ,  802 , and  803 , one pixel is configured by a single region.  FIG. 8B  exemplifies a case in which, for each RGB pixel  811 ,  812 ,  821 ,  822 ,  831 , and  832 , one pixel is configured by two regions (an A image region and a B image region). In the present embodiment, an example in which an image sensor (divided pixel sensor) of the structure of  FIG. 8B  is employed will be described. 
       FIG. 8C  exemplifies the structure of the image sensor  101  of  FIG. 8B . In  FIG. 8C , light receiving elements for the A image  811 ,  821 , and  831  receive light that has passed through an A image region of an imaging lens  100 , and light receiving elements for the B image  812 ,  822 , and  832  receive light that has passed through a B image region of the imaging lens  100 . By receiving the A image and the B image of the same imaging lens in the divided region of each pixel through a single microlens  840 , it is possible to obtain two image signals for which there is parallax. 
     The image signal generated by the image sensor  101  is outputted to a focus/object detector  102  as Bayer image information. 
     A focus/object detector  102  outputs, to a development processor  103 , Bayer image information resulting from adding image information obtained from each of the A image region and the B image region illustrated in  FIG. 8C . Also, the focus/object detector  102  has a function for detecting an object in a live view image, a function for detecting a distance of an object, and a function for detecting a degree of focus (degree of out-of-focus) of an object. High-frequency components (edge information of an object) are extracted from the image information and an object is detected based on the size of the extracted components. A FIR (Finite Impulse Response) type bandpass filter, for example, is used as the method of extracting the edge information. Also, the locations at which edge information is extracted may be all locations of the image information, and it is possible to designate a location at which to extract the edge information of a portion in the image information according to object distance information. The object distance and degree of focus are calculated from the parallax information obtained by a correlation calculation for the respective image information of the A image region and the B image region. The focus/object detector  102  detects a plurality of faces in the image information, for example, and calculates distance information and a degree of focus of each detected face, and outputs these to a controller  104 . 
     A development processor  103  obtains Bayer image information from the focus/object detector  102 , and performs offset adjustment, gain adjustment, and gamma correction processing on the RGB image signal. Gamma correction is processing for generating, based on characteristics of a lens of the optical system  100 , characteristics of the image sensor  101 , or the like, image data of tone characteristics that the user desires. The user can change gamma correction values to generate image data for display on a display or to generate image data in which a feeling or tone of a movie film is reproduced. Also, the development processor  103  converts the RGB image signal into a luminance signal (Y) and color difference signals (Cb and Cr), and outputs the result to a display processor  107 . Also, the development processor  103  performs lens distortion aberration correction processing, camera vibration damping processing, noise reduction processing, and the like. 
     The controller  104  includes a CPU  104   a  which is an arithmetic processing unit and a memory  104   b  which stores a program that the CPU  104   a  executes, and controls operation of the entire digital camera  10 . In the memory  104   b , a later-described AF frame setting table is stored, and the content of the table can be updated by the CPU  104   a.    
     As illustrated in  FIG. 3B , an all-AF-frames image  302  is image information in which guides (AF frames)  303  of a quantity equal to the number of positions (distance measurement points) at which detection is possible in the entire imaging screen (the entire imaged image) of the image sensor  101  are rendered. An AF frame  303  is a graphic image of a frame that displays a focus adjustment position (in-focus position) in an image. The all-AF-frames image  302  may be stored in advance in an image memory such as a DRAM (not shown graphically) or the like, and configuration may be taken so as generate the all-AF-frames image  302  by the controller  104  or a rendering processor such as a GPU (Graphics Processing Unit) (not shown graphically).  FIG. 3E  illustrates an enlargement of three AF frames  303   a ,  303   b , and  303   c  of the top-left end of the all-AF-frames image  302  of  FIG. 3B . For the pixels indicated by the frame 0, the pixel value [0] is held, for the pixels indicated by the frame 1, the pixel value [1] is held, and for a region  303   d  indicated by hatching other than the frames, information such as the pixel value [1023], for example, is held. 
     An AF frame information generation unit  105 , based on object distance information and degree-of-focus information obtained from the controller  104 , generates display information for generating an AF frame image  304  of  FIG. 3C . In the AF frame image  304  of  FIG. 3C , it is possible to display, out of the all-AF-frames image  302  of  FIG. 3B , only the AF frames  305  corresponding to the in-focus position when superimposing onto the live view image. The display information is stored in a lookup table (LUT) for AF frame settings as illustrated in  FIG. 3D , and the CPU  104   a  of the controller  104  updates the content of the LUT in accordance with the successively detected in-focus positions. The LUT includes frame numbers of the AF frames  303 , color information for each frame number, and transparency information (an a value in alpha blending), for example. The color information includes a luminance value and color difference values and/or R (red), G (green), and B (blue) values. 
     A display processor  107  obtains the all-AF-frames image  302  of  FIG. 3B . Also, the display processor  107 , based on the display information (LUT) generated by the AF frame information generation unit  105 , generates the AF frame image  304  where only the AF frames  305  of  FIG. 3C  which correspond to in-focus positions are displayable (α=100%) out of the all-AF-frames image  302  of  FIG. 3B . Regarding the AF frames in the all-AF-frames image  302  of  FIG. 3B  other than the AF frames  305  of  FIG. 3C  corresponding to the in-focus position, the compositing ratio α=0% is set. AF frames whose a value (compositing ratio) is 100% are displays as opaque with a transparency of 0%, and the AF frames whose a value (compositing ratio) is 0% are displayed as transparent with a transparency of 100%. Also, the display processor  107  performs alpha blending in which the generated AF frame image  304  is superimposed on the live view image outputted from the development processor  103  in accordance with the α values (compositing ratios), and outputs composite image information  301  illustrated in  FIG. 3A  to a display apparatus  108  together with a synchronization signal for display. The synchronization signal for display is a horizontal direction synchronization signal for the image, a vertical direction synchronization signal for the image, an effective image position synchronization signal, or the like. 
     &lt;AF Frame Display Processing During Shooting&gt; 
     Next, with reference to  FIG. 2A , AF frame display processing by the digital camera of the present embodiment will be described. 
       FIG. 2A  is a flowchart for illustrating AF frame display processing at the time of shooting performed by the digital camera of the present embodiment. Note that the processing of  FIG. 2A  is implemented by the CPU  104   a  of the controller  104  executing a program stored in the memory  104   b , and thereby controlling each part of the camera. Note that the processing of  FIG. 2A  is started when the digital camera  10  is activated and an AF mode is set. 
     In step S 201 , the CPU  104   a  obtains object distance information calculated by the focus/object detector  102 . The focus/object detector  102  calculates object distance information from parallax information obtained from the A image region and the B image region of the imaging lens  100  illustrated in  FIG. 8C , and outputs it to the controller  104 . 
     In step S 202 , the CPU  104   a  obtains focus information indicating a degree of focus of the object calculated by the focus/object detector  102 . 
     In step S 203 , the CPU  104   a , based on the object distance obtained in step S 201  and the focus information obtained in step S 202 , determines whether it is possible to detect a in-focus position in the live view image. 
     In a case where a in-focus position cannot be detected in step S 203 , the CPU  104   a , after making the AF frames non-displayed in step S 204 , returns to step S 202  and obtains focus information once again. Meanwhile, in a case where it is possible to detect a in-focus position in step S 203 , the CPU  104   a , in step S 205 , rewrites the LUT (hereinafter, the AF frame setting table) for AF frame settings of  FIG. 3D  in accordance with the in-focus position. For example, in a case where in-focus positions are the six regions of the frame numbers  18 ,  30 ,  31 ,  43 ,  44 , and  57  in the all-AF-frames image  302  of  FIG. 3B , rewriting of transparency information (α) to 100% and the color information to red is performed only for the numbers corresponding to the AF frame setting table indicated in  FIG. 3D  generated by the AF frame information generation unit  105 . The color information includes a luminance value and color difference values and/or R (red), G (green), and B (blue) values. In the present embodiment, processing for updating the AF frame setting table is executed by the CPU  104   a  of the controller  104  without accessing the image memory (the VRAM) in which the AF frame image is rendered, and so a high-speed rewrite is possible. Accordingly, AF frame display processing is accelerated, and it becomes possible to display AF frames that follow the movement of the object and focus detection. Also, in a case where the data capacity of the AF frame setting table is fixed, it is possible to change the color information and transparency information resolution in accordance with the number of AF frames within the data capacity. For example, as illustrated in  FIG. 7 , in a case where the AF frame setting table is of a 256-byte capacity, it is possible to store the data of the color information and transparency information each in 8 bits when the number of frames is 64. Similarly, it is possible to store data for each of the color information and transparency information in 4 bits when the number of frames is 128, 2 bits when the number of frames is 256, and 1 bit when the number of frames is 512. 
     In step S 206 , the CPU  104   a  reads the all-AF-frames image  302  of  FIG. 3B  from the image memory (VRAM) (not shown graphically) or the like by the display processor  107 . Also, the CPU  104   a , based on the AF frame setting table rewritten in step S 205 , generates the AF frame image  304  in which only the AF frames  305  of the in-focus position as illustrated in  FIG. 3C  are displayable from the all-AF-frames image  302  of  FIG. 3B . Regarding the all-AF-frames image  302 , the size of one frame and the number of frames can change depending on the characteristics of the image sensor  101  or the like. The all-AF-frames image  302  may be stored in the memory  104   b  of the controller  104  in advance, and may be generated by the CPU  104   a  or a rendering processor such as in a GPU (not shown graphically). 
     In step S 207 , the CPU  104   a  composites, by the display processor  107 , the live view image outputted from the development processor  103  and the AF frame image  304  generated in step S 206 , and thereby generates the composite image  301  illustrated in  FIG. 3A . 
     In step S 208 , the CPU  104   a  displays the composite image  301  generated in step S 207  on the display apparatus  108  and then repeats the processing from step S 201 . 
     Next, the processing from step S 202  to step S 208  of  FIG. 2A  will be described using the timing charts illustrated in  FIGS. 5A and 5B . 
     The focus detection timings are indicated by FT (Focus Timing), and for example, focus detection is performed at a frequency of 120 Hz or 60 Hz, and the focus information is updated at each FT. 
     Display timings are indicated by DT (Display Timing), and there are cases where their period is different to that of the FTs, and there are cases where their period is the same as that of the FTs but the phase is different. The focus information F 1  updated at FT 1  is obtained at DT 1 , and used as table mask information M 1  for the AF frame setting table, to output a display of image information D 1 . By updating the AF frame setting table at the closest DT from the FT change point, it is possible to display AF frames that follow the focus detection. The table mask information M is updated at a rising change point of a DT wave, and the period of time from the fall to the rise of the DT wave is an active display period, and display of the image D is outputted. 
     By the above-described processing, AF frame display processing is accelerated, and it becomes possible to display AF frames that follow the movement of the object and focus detection. 
     Note that in the first embodiment, an example of displaying six adjacent AF frames  305  in the all-AF-frames image  302  was given, but it is possible to simultaneously display AF frames on a plurality of separated regions (three locations)  601 ,  602 , and  603  in the imaging screen as illustrated in  FIG. 6A . Furthermore, it is possible to set the colors of the AF frames of the three locations  601 ,  602 , and  603  illustrated in  FIG. 6A  to be different colors such as red, blue, and green in the AF frame setting table as illustrated in  FIG. 6B . 
     Second Embodiment 
     In the second embodiment, AF frame display processing in which, from the all-AF-frames image arranged two-dimensionally in the imaging screen, only AF frames corresponding to an in-focus object position are cut out (extracted), and displayed to be superimposed on the live view image will be described. 
       FIG. 1B  exemplifies an apparatus configuration of a digital camera of the second embodiment. In the digital camera  10  of the present embodiment, an AF frame generation unit  205  is provided in place of the AF frame information generation unit  105  illustrated in  FIG. 1A  of the first embodiment. Other configurations are similar to  FIG. 1A  and so description thereof is omitted. 
     The AF frame generation unit  205  generates an AF frame image in accordance with the position and shape of an in-focus object detected by the focus/object detector  102 . The AF frame generation unit  205  cuts out, from the all-AF-frames image  402  illustrated in  FIG. 4B , an AF frame  403  indicated in  FIG. 4C  in accordance with the coordinates (x, y) of the position of the in-focus object illustrated in  FIG. 4E , for example, and further generates the AF frame image  404  of only frames that accord to the shape of the object as illustrated in  FIG. 4D . The AF frame image  404  of  FIG. 4D , similarly to the first embodiment is generated using the AF frame setting table illustrated in  FIG. 4F .  FIG. 4G  illustrates an enlargement of the AF frame  403  of  FIG. 4C . For each pixel indicated by the frames 0 to 7 and the region illustrated in hatching other than the frames, information of each pixel value is held. 
     Next, with reference to  FIG. 2B , AF frame display processing by the digital camera of the second embodiment will be described. 
       FIG. 2B  is a flowchart for illustrating AF frame display processing at the time of shooting performed by the digital camera of the present embodiment. Note that the processing of  FIG. 2B  is implemented by the CPU  104   a  of the controller  104  executing a program stored in the memory  104   b , and thereby controlling each part of the camera. Note that the processing of  FIG. 2B  is started when the digital camera  10  is activated and an AF mode is set. 
     In step S 211 , the CPU  104   a  obtains object distance information calculated by the focus/object detector  102 . The focus/object detector  102  calculates object distance information from parallax information obtained from the A image region and the B image region illustrated in  FIG. 8C , and outputs it to the controller  104 . 
     In step S 212 , the CPU  104   a  obtains object information indicating a position, shape, and a degree of focus of the object calculated by the focus/object detector  102 . 
     In step S 213 , the CPU  104   a , based on the object distance obtained in step S 211  and the object information obtained in step S 212 , determines whether it is possible to detect the position of an in-focus object. 
     In a case where an in-focus object cannot be detected in step S 213 , the CPU  104   a , after making the AF frame not displayed in step S 214 , returns to step S 212  and obtains the object information once again. In step S 212 , object position detection is performed. Meanwhile, in a case where it is not possible to detect the position of an in-focus object in step S 213 , the CPU  104   a  rewrites the AF frame setting table illustrated in  FIG. 4F  in accordance with the position of the in-focus object in step S 215 . For example, in a case where the positions of the in-focus object are the six regions whose frame numbers are 1, 2, 3, 4, 5, and 7 illustrated in  FIG. 4D , transparency information (α) is rewritten to 100% and the color information to red only for the numbers corresponding to the AF frame setting table illustrated in  FIG. 4F  out of the AF frame  403  illustrated in  FIG. 4C  generated by the AF frame generation unit  205 . The color information may be set by a luminance value and color difference values or R (red), G (green), and B (blue) values, or the like. In the present embodiment, processing for updating the AF frame setting table is executed by the CPU  104   a  of the controller  104  without accessing the image memory (the VRAM) in which the AF frame image is rendered, and so a high-speed rewrite is possible. Accordingly, AF frame display processing is accelerated, and it becomes possible to display AF frames that follow the movement of the object in the live view image and focus detection. Also, in a case where the data capacity of the AF frame setting table is fixed, it is possible to change the color information and transparency information resolution in accordance with the number of AF frames within the data capacity. For example, as illustrated in  FIG. 7 , in a case where the AF frame setting table is fixed at a 256-byte capacity, it is possible to store the data of the color information and transparency information each in 8 bits when the number of frames is 64. Similarly, it is possible to store data for each of the color information and transparency information in 4 bits when the number of frames is 128, 2 bits when the number of frames is 256, and 1 bit when the number of frames is 512. 
     In step S 216 , the CPU  104   a  reads the all-AF-frames image  402  illustrated in  FIG. 4B  from the image memory (VRAM) (not shown graphically) or the like by the display processor  107 , cuts out the AF frame  403  illustrated in  FIG. 4C  in accordance with the in-focus object position from the all-AF-frames image  402 , and further generates the AF frame image  404  of only frames that accord to the object shape as illustrated in  FIG. 4D . Regarding the all-AF-frames image  402 , the size of one frame and the number of frames can change depending on the characteristics of the image sensor  101  or the like. The all-AF-frames image  402  may be stored in the memory  104   b  of the controller  104  in advance, and may be generated by the CPU  104   a  or a rendering processor such as in a GPU (not shown graphically). 
     In step S 217 , the CPU  104   a , by the display processor  107 , composites, in accordance with the coordinates (x, y) of the position of the object illustrated in  FIG. 4E , the live view image outputted from the development processor  103  and the AF frame image  404  generated in step S 216 , and thereby generates the composite image  401  illustrated in  FIG. 4A . Regarding the position of the object illustrated in  FIG. 4E , it is possible to composite by designating positions in the horizontal direction x and the vertical direction y with the top-left of the live view image as the origin, for example. 
     In step S 218 , the CPU  104   a  displays the composite image  401  generated in step S 217  on the display apparatus  108 , and repeats the processing from step S 211 . 
     Next, the processing from step S 212  to step S 218  of  FIG. 2B  will be described using the timing charts illustrated in  FIGS. 5A and 5B . 
     For example, focus detection is performed at a frequency of 120 Hz or 60 Hz, and object information is updated at each focus detection timing FT. For the display timing DT, the object information F 1  updated at FT 1  is obtained at DT 1 , and used as table mask information M 1  for the AF frame setting table, to output a display of image information D 1 . By updating the AF frame setting table at the closest DT from the FT change point, it is possible to display AF frames that follow the focus detection. The table mask information M is updated at a rising change point of the DT wave, and the period of time from the fall to the rise of the DT wave is an active display period, and display of the image D is outputted. 
     By the above-described processing, AF frame display processing is accelerated, and it becomes possible to display AF frames that follow the movement and position of the object. 
     Note that in the second embodiment, an example of displaying six adjacent AF frames (AF frame image  404 ) in the all-AF-frames image  402  was given, but it is possible to simultaneously display AF frames on a plurality of separated regions (three locations)  601 ,  602 , and  603  in the imaging screen as illustrated in  FIG. 6A . Furthermore, it is possible to set the colors of the AF frames of the three locations  601 ,  602 , and  603  illustrated in  FIG. 6A  to be different colors such as red, blue, and green in the AF frame setting table as illustrated in  FIG. 6B . 
     Other Embodiments 
     Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2018-091406, filed May 10, 2018 which is hereby incorporated by reference herein in its entirety.