Position sensing method and position sensing apparatus and its construction

• US 20050083298A1
• Filed: 08/13/2004
• Published: 04/21/2005
• Est. Priority Date: 08/21/2003
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Balinsky, Helen, Loh, Weng Wah, Dickin, Fraser John
• Granted Patent: US 8,922,478 B2
• Time in Patent Office: Days
• US Class Current: 345/156
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A position sensor is disclosed with detector elements 11 coupled to a set of output lines 20 according to a connection pattern 30. An object 2 triggers a window subset of the detector elements 11, causing a logic output on the set of output lines 20. Some output lines 20a are coupled to more that one detector element 11. However, the connection pattern 30 is arranged such that for any window subset of the detector elements falling in a variable length range, a unique logic output is provided on the set of output lines 20 to identify the position of the object. A sensing method and search process for determining the connection pattern are also disclosed.

Claims

1. A position sensor, comprising:

a sensor array having a plurality of detector elements; and

a set of output lines coupled to the plurality of detector elements according to a connection pattern arranged such that the number of detector elements is greater than the number of output lines, and that in use triggering any window subset of the detector elements provides a unique output on the set of output lines, wherein each window subset has a length falling in a predetermined variable length range.

2. The position sensor of claim 1, wherein each window subset of the detector elements falls within a range defined between a minimum number n and a maximum number m of detector elements, where m>

n.

3. The position sensor of claim 1, wherein the window subset comprises consecutive detector elements.

4. The position sensor of claim 1, wherein the detector elements are arranged in a linear array.

5. The position sensor of claim 1, wherein each detector element is triggerable by an object in order to generate a logic output on a respective one of the output lines.

6. The position sensor of claim 1, wherein each output line is represented by one abstract character in a reference alphabet and the connection pattern is defined by a string of characters taken from the reference alphabet, such that each window subset of the detector elements corresponds to a unique character combination.

7. The position sensor of claim 6, wherein each character appears only once in any one window subset, without duplication.

8. The position sensor of claim 6, wherein each window subset corresponds to a unique character combination, without repetition subject to permutation.

9. The position sensor of claim 6, wherein each character in the reference alphabet is an alphabetic character.

10. The position sensor of claim 6, each output line is represented by a numeric value, such that each window subset is represented by a combined numeric total obtained by summing numeric values for each triggered output line.

11. The position sensor of claim 10, wherein each output line is represented by one of a numerically weighted set such that for each window subset a unique numerical value is derived.

12. The position sensor of claim 11, wherein the numerically weighted set is a sequence of power terms.

13. The position sensor of claim 1, wherein each output line is allocated one element in the binary power sequence 1, 2, 4, 8, 16, 32, . . . , such that each logic output the set of output lines combines to form a binary numeric value.

14. The position sensor of claim 1, wherein the detector elements are each proximity detectors.

15. The position sensor of claim 1, wherein the position sensor is a touch strip sensor.

16. A position sensing system comprising:

a position sensor having a sensor array with a plurality of detector elements and a set of output lines coupled to the plurality of detector elements according to a connection pattern arranged such that the number of detector elements is greater than the number of output lines, and that in use triggering any window subset of the detector elements provides a unique output on the set of output lines, wherein each window subset has a length falling in a predetermined variable length range; and

a controller arranged to receive a logic output from the set of output lines and thereby determine a corresponding absolute position of an object in relation to the sensor array.

17. The position sensing system of claim 16, comprising:

a look up table arranged to store a mapping of logic outputs from the set of output lines against absolute positions of an object in relation to the position sensor.

18. The position sensing system of claim 17, wherein the mapping is derived from the connection pattern between the detector elements and the output lines.

19. A position sensor for sensing position of an object, the position sensor comprising:

a plurality of sensors arranged such that a window subset of the sensors are triggered in use by an object; and

a set of output lines coupled to the sensors according to a connection pattern, to provide a logic output responsive to the triggered window subset of the sensors;

wherein the connection pattern is arranged such that for any window subset of the sensors, a unique logic output is provided on the set of output lines to identify a position of the object.

20. The position sensor of claim 19, wherein:

each output line is represented by one character in a reference alphabet, such that the connection pattern is represented by a connection pattern character string and each window subset corresponds to a substring of characters from the connection pattern character string;

there are no character duplications within any window subset; and

no two window subsets contain equivalent permutations of character combinations.

21. The position sensor of claim 19, wherein each output line is allocated one binary power term 1, 2, 4, 8, 16, etc, such that triggering a window subset of the sensors provides a logic output on the set of output lines as a combined binary numeric value.

22. The position sensor of claim 19, wherein the window subset comprises a variable number of sensors in a predetermined range.

23. The position sensor of claim 19, wherein the window subset comprises consecutive sensors in a one-dimensional array.

24. The position sensor of claim 19, wherein at least one of the output lines is coupled to more than one of the sensors, and each sensor is coupled to only a respective one of the output lines.

25. A biometric input device for sensing position of a human finger comprising a position sensor having a sensor array with a plurality of detector elements and a set of output lines coupled to the plurality of detector elements according to a connection pattern arranged such that the number of detector elements is greater than the number of output lines, and that in use triggering any window subset of the detector elements provides a unique output on the set of output lines, wherein each window subset has a length falling in a predetermined variable length range.

26. A biometric input device for sensing position of a human finger comprising a position sensor having:

a plurality of sensors arranged such that a window subset of the sensors are triggered in use by an object; and

a set of output lines coupled to the sensors according to a connection pattern, to provide a logic output responsive to the triggered window subset of the sensors;

wherein the connection pattern is arranged such that for any window subset of the sensors, a unique logic output is provided on the set of output lines to identify a position of the object.

27. Computing apparatus comprising:

a display screen;

and a position sensor having a sensor array with a plurality of detector elements and a set of output lines coupled to the plurality of detector elements according to a connection pattern arranged such that the number of detector elements is greater than the number of output lines, and that in use triggering any window subset of the detector elements provides a unique output on the set of output lines, wherein each window subset has a length falling in a predetermined variable length range;

wherein the position sensor is arranged to control a scrolling function of the display screen.

28. The computing apparatus of claim 27, wherein the apparatus is a cellular telephone, a personal digital assistant, or a handheld computing device.

29. A method of sensing a position of an object, using a position sensor having a plurality of detector elements coupled to a set of output lines according to a connection pattern arranged such that the number of detector elements is greater than the number of output lines, the method comprising the steps of:

triggering a window subset of the detector elements according to a position of the object, where the window subset has a variable length within a predetermined range;

providing a logic output on the set of output lines corresponding to the triggered window subset of detector elements according to the connection pattern, such that any window subset of consecutive detector elements within the predetermined range provides a unique logic output on the set of output lines without repetition subject to permutation.

30. The method of claim 29, comprising the step of:

mapping the logic output provided on the set of output lines to an absolute position of the object.

31. The method of claim 29, comprising the step of:

providing on each output line either a first binary logic level where any one or more detector elements coupled to the respective output line is triggered by an object or else providing a second binary logic level, such that a pattern of binary outputs is provided as the logic output on the set of output lines.

32. The method of claim 29, comprising determining a binary numeric value from the logic outputs on the set of output lines, the binary numeric value representing the absolute position of the object in relation to the detector elements.

33. A method of constructing a position sensor, comprising the steps of:

providing a total number of detection elements L;

determining a range of window subset sizes between a maximum size m and a minimum size n;

allocating each of a plurality of output lines a unique character in a reference alphabet;

forming a connection pattern represented by a character string of length L from the reference alphabet using a combinatorial search to determine character combinations for each window subset of between n and m consecutive characters, wherein each character combination appears in the character string only once without repetition subject to permutation; and

connecting the detector elements to the output lines according to the connection pattern.

34. The method of claim 33, comprising:

mapping potential outputs from the set of output lines against absolute positions of an object in relation to the detection elements.

35. The method of claim 34, comprising recording the mapping in a look up table.

36. A search process for use in determining a connection pattern between a plurality of detector elements and a set of output lines, the search process comprising the steps of:

defining a desired length of the connection pattern L according to a total number of the detector elements, and defining a window range of between n and m consecutive detector elements for unique position determination;

allocating to each output line one element in a reference alphabet, where the reference alphabet is a sequence of binary power terms 1, 2, 4, 8, 16, 32, . . . ;

selecting an initial string comprising a first m+1 elements from the reference alphabet;

calculating a numeric value for each window subset of length n to m along the string as a search list;

searching the search list for repeated numeric values, and if so then returning to the selecting step to reselect the string by replacing or reordering one or more elements, or else adding an additional element to the string and returning to the calculating step; and

continuing the search until a connection pattern of the desired length L is achieved.

37. The search process of claim 36, wherein the additional element added to the string is either an element that has already been used at least m+1 places earlier in the string, or is a previously unused element from the reference alphabet.

38. The search process of claim 36, wherein the calculating step calculates m−

n+1 new numeric values following addition of each additional element, and the searching step searches each of the new m−

n+1 numeric values against the previous search list prior to adding each value to the search list.

39. The search process of claim 36, comprising the step of checking each combined numeric value to identify duplications of an element of the reference alphabet within any one window subset.