representing the first cluster of strength values 212 that correspond to the first touch input 202 and a second touch island 224 representing the second cluster of strength values 214 that correspond to the second touch input 204 on the touchscreen 102. The touch bitmap 220 corresponds to the strength bitmap 210 shown in FIG. 2B. In various embodiments, a touch bitmap 220 can be created and recorded for each frame based on the strength values on the strength bitmap 210. Each frame of the touch bitmap 220 can be recorded and analyzed across sequential frames to determine merge conditions.

In one or more embodiments, the touch bitmap 220 shows binary values, 0 or 1, that represent strength values on the touch nodes of the strength bitmap 210 compared to a strength threshold. Each touch node with a strength value greater than a strength threshold may be assigned ‘1’ and each touch node with a strength value less than the strength threshold may be assigned ‘0’. In the illustrated example, the strength threshold may be +250. While the strength threshold has a value of 250, the strength threshold may vary for different devices or projects that require different touch strengths. For example, the strength thresholds may be 100, 150, 200, etc. for different projects.

In one or more embodiments, the touch islands on touch bitmap 220 represents the spatial distribution of each touch input. The touch controller 104 can store the touch bitmaps in memory 110 for multiple sequential frames to enable analysis of multiple touch inputs and overlapping touch node patterns across frames. The touch controller 104 can use the touch islands on the touch bitmap to determine whether to report the touch inputs as separate touch coordinates (e.g., split coordinates) or a single touch coordinate (e.g., merged coordinates) to the system on a chip 106.

FIGS. 3A-3C illustrate touch bitmaps for multiple touch inputs on an electronic device according to an embodiment of the present application. FIGS. 3A-3C will be described in conjunction with FIGS. 1A-1B. The touch bitmaps represent touch input processing across sequential frames according to various embodiments.

FIGS. 3A-3C show touch bitmaps 300, 310, 320 for sequential frames N−2, N−1, N. In various embodiments, the sequential frames N−2, N−1, N may be referred to as a current frame (e.g., N), a preceding frame (e.g., N−1), previous frames (e.g., N−1, N−2), or next frame (e.g., N+1, N+n). In other embodiments, the sequential frames N−2, N−1, N may be referred to numerically, for example, as a first frame (e.g., N−2), a second frame (e.g., N−1), and a third frame (e.g., N).

In one or more embodiments, when multiple touch inputs are detected on a touchscreen 102, the touch islands may be split so that the touch inputs are reported as separate touch coordinates for some frames or merged so that the touch inputs are reported as a single touch coordinate for other frames. For example, when two touch inputs are stationary for a plurality of frames, the stationary touch inputs may be inconsistently reported as a single touch coordinate and as two separate coordinates in different frames. In various embodiments, separate touch coordinates may be referred to as split coordinates and a single touch coordinate may be referred to as a merged coordinate. The touch bitmaps 300, 310, 320 show the touch islands corresponding to the reported touch coordinates for the sequential frames N−2, N−1, N.

FIG. 3A shows the touch bitmap 300 for a first frame N−2. The touch bitmap 300 shows separate touch islands or split islands 322, 324 that are reported as separate touch coordinates in the first frame N−2. FIG. 3B shows the touch bitmap 310 for second frame N−1. The touch bitmap 310 shows separate touch islands 322, 324 that are reported as a single or merged touch coordinate 325 in the second frame N−1. FIG. 3C shows the touch bitmap 320 for a third frame N. The touch bitmap 320 shows separate touch islands 322, 324 that are reported as separate touch coordinates in the third frame N.

In one or more embodiments, the touch controller 104 detects a plurality of touch inputs for a plurality of frames on a touchscreen of an electronic device. In one or more embodiments, the touch controller 104 records the touch inputs on a touch bitmap for each frame and stores the recorded touch bitmaps in memory 110. In one or more embodiments, the touch controller 104 can utilize the touch bitmaps of previous frames to determine whether the touch inputs and the touch islands have met at least one merge criteria for a current frame. For example, the touch bitmaps 300, 310, 320 for the sequential frames N−2, N−1 can be utilized to determine whether to merge the touch inputs of the frame N−1, and the sequential frames N−1, N can be utilized to determine whether to merge the touch inputs of the frame N.

In one or more embodiments, the touch controller 104 can compare the touch nodes of a current frame N with the touch nodes of a preceding or previous frame N−1. The touch controller 104 can continuously evaluate the touch nodes of the current frame N and compare the touch nodes of the current frame N with the touch nodes of the previous frame N−1 to determine whether merge criteria has been met. For example, criteria for merging the touch inputs on the current frame N based on the preceding frame N−1 can include determining whether the touch inputs on the preceding frame N−1 have been merged to a single touch coordinate, determining a number of touch nodes in the current frame N that overlap with the touch nodes in the preceding frame N−1, and determining a speed (i.e., change in distance and time) between the touch inputs in the preceding frame N−1 and corresponding touch inputs in the current frame N. When one or more merge criteria is met, the touch controller 104 merges the touch inputs in the current frame N to a single touch coordinate.

FIG. 4 illustrates a merge analysis according to an embodiment of the present application. FIG. 4 will be described in conjunction with FIGS. 1A and 3A-3C. The merge analysis shows touch input processing between a recorded frame 400 for a preceding or previous frame and a bitmap check 410 for a current frame according to various embodiments.

In one or more embodiments, each touch input on the previous frame N−1 is recorded and stored in memory 110 to be utilized to determine whether to merge the touch inputs on the current frame. The recorded frame 400 for the previous frame N−1 shows a first touch input 426, a second touch input 428, and a merged touch island 425. The first touch input 426 includes a corresponding first touch island and the second touch input 428 includes a corresponding second touch island that is adjacent to the first touch island. The first touch island and the second touch island can be combined to the merged touch island 425 based on a recorded frame (not shown) preceding the previous frame N−1.

The bitmap check 410 shows a first touch island 432 of the current frame N, a second touch island 434 of the current frame N, and the merged touch island 425 of the previous frame N−1. When the bitmap check 410 indicates that a touch island of the current frame N overlaps with the merged touch island 425 of the previous frame N−1 by more than an overlap threshold, the touch controller 104 assigns a touch index from the previous frame N−1 as a merge identifier or merge ID to the touch island of the current frame N. The overlap threshold may be between 60% and 90%, e.g., 75%. The touch index is a numerical identifier assigned to each individual touch input detected by the screen that allows the system to differentiate between each finger touching the screen simultaneously. For example, when a user touches the touchscreen 102 at five different points in a given frame, the touch controller 104 may allocate, for that frame, touch indices of 01, 02, 03, 04, and 05 respectively to each user touch.

When the touch inputs are merged to a merged touch coordinate in the previous frame N−1, the touch index of the merged touch coordinate can be assigned as the merge ID on the current frame. For example, if the first touch input 426 has a touch index of 01 in the previous frame N−1, the second touch input 428 has a touch index 02 in the previous frame N−1, the first touch input 426 and the second touch input 428 is merged in the previous frame N−1, and the first touch input 426 is the reported merged touch coordinate in the previous frame N−1, each touch input on the current frame N can be assigned 01 as the merge ID if the overlap for that touch input exceeds the overlap threshold. In one or more embodiments, the touch controller 104 determines an overlap percentage of overlapping touch nodes on the touch bitmap of the current frame N and touch bitmap of the previous frame N−1. For example, the overlap percentage for the touch input can be calculated using the formula

$\frac{A ⋂ B}{A},$

where A is the number of touch nodes in the touch island in the current frame N and B is the number of touch nodes in the merged touch island in the previous frame N−1. The touch controller 104 assigns a merge ID to the touch island on the current frame N based on the overlap percentage of the touch nodes. When the touch islands of the current frame N and the previous frame N−1 overlap by more than an overlap threshold, the merge ID assigned to the touch island on the current frame N may be a touch index of the previous frame N−1. Following the example above, if the first touch island 432 on the current frame N has an overlap percentage that exceeds the overlap threshold, the touch controller 104 assigns the touch index 01 as the merge ID for the first touch island 432 in the current frame N. If the second touch island 434 has an overlap percentage that exceeds the overlap threshold, the touch controller 104 assigns the touch index 01 as the merge ID for the second touch island 434 in the current frame N.

When the merge IDs for the touch islands match on the current frame N, the touch controller 104 merges the touch islands 432, 434 and reports the corresponding touch inputs as a merged touch coordinate to the system on a chip 106. Following the example above, the merge ID for the first touch island is 01 and the merge ID for the second touch island is 01, the touch controller 104 can merge the touch islands 432, 434 on the current frame and report the corresponding touch inputs as a merged touch coordinate to the system on a chip 106.

When the merge IDs on the current frame N have the touch index of the previous frame N−1, this may indicate that the touch input has not significantly changed between frames. When the merge ID for two or more touch islands on the current frame N are the same, excluding touch islands that are assigned the default merge ID, the touch controller 104 merges the touch islands to a single touch island and reports the touch inputs as a merged touch coordinate to the system on a chip 106. When the touch islands of the current frame N and the previous frame N−1 overlap by less than the overlap threshold, the merge ID assigned to the touch island on the current frame N may be a default merge ID (e.g., touch index 255). When the merge ID for two or more touch islands on the current frame N are assigned the default merge ID, the touch controller 104 does not merge the touch islands and reports the touch inputs as a separate touch coordinate to the system on a chip 106.

The touch controller 104 continues to evaluate the touch bitmaps and the merge IDs across the frames. The continuous evaluation of this merge criterion can provide stable touch coordinate reporting while allowing appropriate touch separation when conditions change. In the absence of this algorithm, the touch controller 104 may report a merged touch, followed by a two separate touches, followed again by a merged touch, and so on. This instability could then make subsequent downstream processing to be unstable/inaccurate.

FIGS. 5A-5B illustrate touch bitmaps for multiple touch inputs on an electronic device according to an embodiment of the present application. FIGS. 5A-5B will be described in conjunction with FIG. 1A. The touch bitmaps represent touch input processing across sequential frames according to various embodiments.

In one or more embodiments, the touch controller 104 compares the touch bitmaps between frames and determines whether the touch inputs and touch islands of the current frame N meet one or more criteria to merge. The merge criteria may include matching merge IDs, speeds between touch inputs that are below a speed threshold, distances between touch inputs that are below a distance threshold, or any combination thereof. For example, merged touch input on a previous frame N−1 may remain merged in the current frame N when the merge IDs match, when the speed of the touch inputs between frames is less than a speed threshold, or when the distance between the touch inputs is less than a distance threshold. If any criterion is not met, for example, non-matching merge IDs, the speeds exceed the speed threshold, and the distance exceed the distance threshold, the previously merged touch inputs may be split and reported as two separate touch inputs.

FIG. 5A shows a touch bitmap 500 for a previous frame N−1. The touch bitmap 500 shows a first touch input 526, a second touch input 528, and a merged touch island 525 of a previous frame N−1.

FIG. 5B shows a touch bitmap 510 for a current frame N and the previous frame N−1. The touch bitmap 510 shows, for the previous frame N−1, the first touch input 526, a first touch island 522 for the first touch input 526, the second touch input 528, a second touch island 524 for the second touch input 528, and the merged touch island 525 of the previous frame N−1. The touch bitmap 510 also shows, for the current frame N, a first touch input 536, a first touch island 532 for the first touch input 536, a second touch input 538, and a second touch island 534 for the second touch input 538. The first touch input 526 from the previous frame N−1 and the first touch input 536 from the current frame N may be, for example, a finger touch on the touchscreen 102 that is held on the touchscreen 102 for at least two frames. While the inventive aspects are described primarily in the context of a first touch input and a second touch input, it should also be appreciated that these inventive aspects may also apply to two or more touch inputs.

Referring to FIG. 5B, the touch bitmap 510 depicts merge criteria that the touch controller 104 can use to determine whether multiple touches should be merged. In one or more embodiments, the touch controller 104 determines whether merge IDs assigned to touch islands match, the speed of touch inputs between the previous frame N−1 and the current frame N is less than the speed threshold, or the distance between touch inputs in the current frame N are less than a distance threshold.

In one or more embodiments, a merge ID is assigned to the touch islands of the touch bitmap for each frame as described in FIG. 4. When the touch islands on the current frame N overlap with the touch islands on the previous frame N−1 by more than an overlap threshold, a touch index of the previous frame N−1 is assigned as the merge ID on the current frame N. When the merge ID for two or more touch islands are the same, the touch controller 104 determines that the touch inputs of the current frame N should be merged, merges the touch inputs to a single touch input, and reports the merged touch input as a single touch coordinate to the system on a chip 106.

For example, when the first touch island 532 and the second touch island 534 on the current frame N overlaps the first touch island 522 and the second touch island 524 on the previous frame N−1, the touch index of the previous frame is assigned as the merge ID for the first touch island 532 and the second touch island 534. When the first touch island 532 and the second touch island 534 have the same merge ID, the touch controller 104 merges the first touch island 532 and the second touch island 534 and reports the touch inputs as a merged touch coordinate to the system on a chip 106. When the merge ID for two or more touch islands are the different, the touch controller 104 determines that the touch inputs of the current frame N should be separate touch coordinates and reports each touch input as separate touch coordinates to the system on a chip 106.

In one or more embodiments, a speed is determined between the first touch input of the previous frame N−1 and the corresponding first touch input of the current frame N. The speed is a calculated based on a distance between the corresponding touch inputs and the time between the previous frame N−1 and the current frame N. For example, in FIG. 5B, the speed for the first touch input can be calculated based on the distance between the first touch input 526 of the previous frame N−1 and the first touch input 536 of the current frame N and the time between the previous frame N−1 and the current frame N. Similarly, the speed for the second touch input can be calculated based on the distance between the second touch input 528 of the previous frame N−1 and the second touch input 538 of the current frame N and the time between the previous frame N−1 and the current frame N.

When the calculated speeds are less than a speed threshold, the touch controller 104 determines that the touch inputs of the current frame N is likely to be a merged touch and should be merged after further check with distance condition, merges the touch inputs to a single touch input, and reports the merged touch input to the system on a chip 106. The speed threshold may be between 30 and 60 pixels per frame, e.g., 45 pixels per frame. Each frame may be measured in milliseconds based on a touch scan rate of the touch controller 104. For example, each frame may be 8.3 ms with a touch scan rate of 120 Hz. When at least one of the calculated speeds are greater than or equal to the speed threshold, the touch input having a speed greater than the speed threshold may be a new touch input that should not be merged with the other touch inputs after traditional merge check as a new touch. For example, when the speed for the first touch input is less than the speed threshold and the speed for the second touch input is greater than the speed threshold, the second touch input is likely to be a new separate touch input (e.g., subsequent touch or tap) instead of the same touch input recorded in the previous frame N−1 (e.g., a touch or tap held on the touchscreen during the previous frame N−1 and the current frame N).

In one or more embodiments, a distance is calculated between the touch inputs of the current frame N. The distance is determined between the first touch input of the current frame N and the second touch input of the current frame N. For example, the distance can be measured from the first touch input 536 and the second touch input 538.

When the distance is less than a distance threshold, the touch controller 104 determines that the touch inputs of the current frame N should be merged, merges the touch inputs to a single touch input, and reports the merged touch input to the system on a chip 106. The distance threshold may be between 50 and 100 pixels, e.g., 75 pixels. When the distance is greater than or equal to the distance threshold, one or both of the touch inputs may be a new touch input that should not be merged with the other touch input after traditional merge check as a new touch. For example, when the distance between the first touch input 536 and the second touch input 538 is greater than the distance threshold, at least one of the first touch input or the second touch input is likely to be a new separate touch input (e.g., subsequent touch or tap) instead of the same touch input recorded in the previous frame N−1 (e.g., a touch or tap held on the touchscreen during the previous frame N−1 and the current frame N).

In one or more embodiments, the touch controller 104 determines to merge the touch inputs of the current frame N when all merge criteria are met. For example, merged touch inputs on a previous frame N−1 may remain merged in the current frame N when the merge IDs for the touch islands match, the speed is less than a speed threshold, and the distance between the touch inputs is less than a distance threshold. If any criterion is not met, for example, the speeds exceed the speed threshold, the distance exceeds the distance threshold, or the merge IDs do not match, the previously merged touch inputs may be split and reported as two separate coordinates.

In one or more embodiments, when the touch inputs merge, the touch controller 104 may report a coordinate in between the first touch input 526 and the second touch input 528. For example, when the first touch input 526 and the second touch input 528 are merged at frame N, the touch controller 104 can report a coordinate at a mid-point between the first touch input 526 and the second touch input 528. The mid-point may be calculated using a centroid method based on the merged touch islands.

The touch controller utilizes the touch bitmaps to evaluate the touch inputs and previously recorded touch coordinates based on their spatial and temporal characteristics. The evaluation process enables stable coordinate reporting for merged touches and preserves the ability to separate distinct touch inputs.

FIG. 6 illustrates a process flow 600 for assigning a merge ID according to an embodiment of the present application. The touch controller 104 performs the process flow for assigning the merge ID as described in FIG. 4.

In one or more embodiments, the process flow 600 for assigning the merge ID is performed for each frame. While the process flow 600 will be described in the context of a current frame, the process flow applies to previous frames and subsequent frames. The process begins by setting an initial merge ID to the current frame N in step 601. The initial merge ID may be a default merge ID. The default merge ID may be a touch index of 255.

In step 603, the touch controller 104 records unmerged touch islands and corresponding touch inputs of a previous frame N−1. The touch islands and touch inputs are stored in memory to be compared with the current frame. In step 605, the touch controller 104 creates a touch bitmap for the current frame. The touch bitmap is created from a strength bitmap for the current frame as described in FIG. 2C.

In step 607, the touch controller 104 calculates an overlap percentage for overlapping touch nodes on the touch bitmap of the current frame N created in step 605 and the touch bitmap of the previous frame N−1 recorded in step 603. In some embodiments, the touch controller 104 may calculate separate overlap percentages for each touch island that corresponds to each touch input. For example, the touch controller 104 may calculate a first overlap percentage for a first touch island on the current frame that overlaps with a first touch island on the previous frame and calculate a second overlap percentage for a second touch island on the current frame that overlaps with a second touch island on the previous frame. When the overlap percentage is calculated, the touch controller 104 determines whether the overlap percentage exceeds an overlap threshold.

When the overlap percentage exceeds the overlap threshold, the touch controller 104 assigns merge identifiers or merge IDs to the corresponding touch islands in step 609. In various embodiments, a first merge ID is assigned to the first touch island and a second merge ID is assigned to the second touch island based on the respective overlap percentages. The assigned merge ID may correspond to a touch index from the previous frame when sufficient overlap is detected. When the overlap percentage does not exceed the overlap threshold, the touch controller 104 assigns a default merge ID to the touch islands in the current frame in step 611.

The merge IDs provide a mechanism for tracking touch relationships across frames. In one or more embodiments, touch inputs sharing the same merge IDs can be merged. In other embodiments, touch inputs sharing the same merge IDs may be merged when additional merge criteria, such as speed and distance thresholds, are satisfied. The process flow repeats for each frame to maintain consistency in touch input tracking while allowing for dynamic merge analysis based on changing touch inputs.

FIG. 7 illustrates a flow diagram 700 for merging multiple touch inputs according to an embodiment of the present application. The flow diagram 700 is a process flow for determining whether to merge touch inputs of a current frame. When the touch inputs of the current frame meet the merge criteria in the flow diagram 700, the touch controller 104 can merge the touch inputs.

In step 701, the touch inputs on the current frame are evaluated. In one or more embodiments, the evaluation of the touch inputs on the current frame includes determining whether merge IDs of adjacent touch inputs have a same merge ID, determining a speed between the adjacent touch inputs of the current frame and the adjacent touch inputs on a previous frame of the plurality of frames, and determining a distance between adjacent touch inputs on the current frame.

For example, when two touch inputs are detected on the current frame, the evaluation of the two touch inputs on the current frame includes determining whether merge IDs of the first touch input and the merge ID of the second touch input have a same merge ID, calculating a speed between the first touch input on the current frame and the first touch input on a previous frame, calculating a speed between the second touch input on the current frame and the second touch input on the previous frame, and calculating a distance between the first touch input and the second touch input on the current frame.

The evaluation of the touch inputs in step 701 can be used to determine whether the merge criteria is met. In step 703, a first merge criterion is met when the merge ID of the adjacent touch inputs are the same. In step 705, a second merge criterion is met when the calculated speed between the touch inputs on the current frame and the corresponding touch inputs on the previous frame is less than a speed threshold. In step 707, a third merge criterion is met when the calculated distance between the adjacent touch inputs on the current frame is less than a distance threshold. While the first, second, and third merge criteria in steps 703, 705, 707 are shown consecutively in the flow diagram 700, the steps may occur simultaneously or in a different order from the order shown in flow diagram 700.

When the first, second, and third merge criteria are satisfied, the touch inputs can be merged for the current frame in step 709. When one of the merge criteria is not satisfied, the touch controller 104 proceeds to perform a traditional merge check in step 711. The traditional merge check may include checking the current frame N based on distance, axis projection strength, island length, etc. In one or more embodiments, the touch inputs can be merged based on the traditional merge check.

FIG. 8 illustrates a flow diagram of a method for processing touch inputs according to various embodiments. At block 801, the touch controller 104 detects a plurality of touch inputs across multiple sequential frames on a touchscreen 102. The touch inputs may be detected through capacitive strength measurements on the touch sensing layer 116. At block 803, the touch controller 104 determines a distance between adjacent touch inputs detected on a current frame. In various embodiments, the distance calculation measures spatial separation between touch positions within the same frame to evaluate their proximity. At block 805, the touch controller 104 determines speeds between the adjacent touch inputs by comparing their positions in the current frame to corresponding positions in the previous frame. The speed calculations consider the distance between each touch and the time interval between frames. At block 807, the touch controller 104 merges the adjacent touch inputs based on the determined distance and speed. The adjacent touch inputs may merge into a single touch input when the distance is less than a distance threshold and the speeds are less than a speed threshold.