Resistive touchscreen having multiple selectable regions for pressure discrimination

• US 5,815,141 A
• Filed: 04/12/1996
• Issued: 09/29/1998
• Est. Priority Date: 04/12/1996
• Status: Expired due to Fees

• Current Assignee: Tyco Electronics Corporation (TE Connectivity Limited)
• Original Assignee: Elo Touchsystems Incorporated (Elo Touch Solutions, Inc.)
• Inventors: Phares, Robert
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US08/631,065
• Time in Patent Office: 900 Days
• Field of Search: 178/18, 178/19, 178/20, 345/173, 345/174, 345/179
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A resistive two sheet touchscreen that provides discrimination between objects touching the surface thereof. This is achieved by subdividing at least one sheet into a selected number of separated portions of selected configuration. Each of these portions is connected through a switch apparatus to circuitry for evaluating a signal on the separated portions corresponding to the position of touch. This switch can be utilized to deactivate any selected portion so that an object contacting this portion provides no signal to the circuitry. Any active portion that remains connected to the circuitry provides position information as with any touchscreen. Accordingly, for example, the touchscreen can be made insensitive to portions of a hand, while being sensitive to a stylus held by that hand. An embodiment utilizing a single resistive layer coupled with a conductive layer is described together with an embodiment utilizing two resistive layers, are described.

Claims

1. A resistive position touchscreen for providing information as to a point of touch by an object, and selectively discriminating against contact of other objects, said resistive position touchscreen comprising:

first and second closely spaced and separated sheets, said first and second sheets contacting each other at a point when touched by an object at that point, at least one of said first and second sheets divided into a plurality of electrically separated regions;

a resistive layer applied to at least one of said first and second sheets on a surface facing another of said first and second sheets, said resistive layer having a selected substantially uniform resistivity throughout said resistive layer;

field generating means connected to opposite edges of said resistive layer for producing electrical fields in said resistive layer;

a circuit means for applying voltages in proper timed sequence to said field generating means, and for receiving and analyzing signals from said plurality of separated regions to ascertain information as to a point of touch; and

a switch means connected to each of said separated regions to selectively connect at least one of said separated regions with said circuit means whereby a selected portion of said resistive layer is active for providing information as to the position of touch of the object.

2. The touchscreen of claim 1 wherein a first resistive layer and a second resistive layer are applied to confronting surfaces of said first and second sheets, respectively, each said first and second resistive layers having a substantially uniform resistivity throughout;

and

wherein said field generating means is connected to opposite edges of said first resistive layer on said first sheet and to opposite edges of said second resistive layer on said second sheet to effectively provide intersecting electrical fields in said resistive position touchscreen in a selected alternating timed sequence.

3. The touchscreen of claim 1 wherein said resistive layer is applied to said first sheet, said second sheet having a conductive layer confronting said resistive layer, said conductive layer being divided into said plurality of electrically separated regions;

and

wherein said field generating means is connected to both opposite edges of said resistive layer to provide within said resistive layer alternating intersecting electrical fields in a selected time sequence.

4. The touchscreen of claim 2 wherein said first resistive layer is divided into said plurality of electrically separated regions.

5. The touchscreen of claim 2 wherein said first resistive layer and said second resistive layer are each divided into said plurality of electrically separated regions.

6. A resistive touchscreen for providing information as to a point of touch by an object, and selectively discriminating against contact of other objects, said resistive touchscreen comprising:

a resistive layer having a selected substantially uniform resistivity throughout said resistive layer, said resistive layer defining perimeter edges;

field generating means connected proximate said perimeter edges of said resistive layer for producing intersecting orthogonal electrical fields in said resistive layer;

a conductive layer overlaying and uniformly spaced from said resistive layer for contacting said resistive layer when touched by the object, said conductive layer divided into a plurality of electrically separated conductive regions;

a circuit means for applying voltages in proper timed sequence to said field generating means, and for receiving and analyzing signals from said plurality of conductive regions to ascertain the information as to the point of touch; and

a switch means connected to each of said conductive regions to selectively connect at least one of said conductive regions with said circuit means whereby a portion of said resistive layer associated with said connected conductive region is active for providing information at said circuit means as to the position of a touch of the object to said connected conductive region, and whereby portions of said resistive layer associated with conductive regions not attached by said switch means to said circuit means are inactive as to providing position information.

7. The resistive touchscreen of claim 6 further comprising insulator means for preventing inadvertent contact between said conductive layer and said resistive layer.

8. The resistive touchscreen of claim 7 wherein said insulator means is a plurality of substantially uniformly distributed insulator islands positioned between said conductive regions and said resistive layer, said insulator islands having a height sufficient to prevent said inadvertent contact, and allow contact when said conductive layer is touched by the object.

9. The resistive touchscreen of claim 6 wherein said resistive layer is supported by a substrate layer.

10. The resistive touchscreen of claim 6 wherein said field generating means comprises:

a plurality of resistance elements one each being positioned proximate each of said perimeter edges of said resistive layer, each of said plurality of resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said plurality of resistance elements comprising a plurality of discontinuous units in electrical contact with said resistive layer, each of said units formed by at least one line of conductive material spaced from a line of conductive material of an adjacent unit to define a separation gap of a selected width and length whereby said width and length of said gap and said resistivity of said resistive layer establish a unit resistance for said units;

connection elements at said joined ends of said plurality of resistance elements connected to said circuit means for applying voltage to said joined ends; and

a plurality of electrodes positioned on, and electrically connected to, said resistive layer along a preselected symmetrical path proximate each perimeter edge of said resistive layer, said electrodes each being connected to selected positions along each of said plurality of resistance elements to introduce said orthogonal electric fields in said resistive layer, said electrodes having a selected spacing and each electrode having an effective length along said path to produce a selected voltage gradient at each of said electrodes to compensate for any cumulative voltage drop along said resistance element perpendicular to current flow through said resistive layer during operation of said resistive touchscreen when said orthogonal electric fields are introduced into said resistive layer.

11. A resistive touchscreen for providing information as to a point of touch by an object, and selectively discriminating against contact of other objects, said resistive touchscreen comprising:

a substrate;

a resistive coating applied to a surface of said substrate, said resistive coating having a selected substantially uniform resistivity throughout said resistive coating, said resistive coating defining perimeter edges;

field generating means connected proximate said perimeter edges of said resistive coating for producing orthogonal electrical fields in said resistive coating;

a conductive layer overlaying and uniformly spaced from said resistive coating for contacting said resistive coating when touched by the object, said conductive layer divided into a plurality of electrically separated conductive regions;

insulator means for preventing inadvertent contact between said conductive layer and said resistive coating;

a circuit means for applying voltages in proper time sequence to said field generating means, and for receiving and analyzing signals from said plurality of conductive regions to ascertain the information as to the point of touch; and

a switch means connected to each of said conductive regions to selectively connect at least one of said conductive regions with said circuit means whereby a portion of said resistive coating associated with said connected conductive region is active for providing information at said circuit means as to the position of a touch of the object to said connected conductive region, and whereby portions of said resistive coating associated with conductive regions not attached by said switch means to said circuit means are inactive as to providing position information.

12. The resistive touchscreen of claim 11 wherein said field generating means comprises:

a plurality of resistance elements one each being positioned proximate each of said perimeter edges of said resistive layer, each of said plurality of resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said plurality of resistance elements comprising a plurality of discontinuous units in electrical contact with said resistive coating, each of said units formed by at least one line of conductive material spaced from a line of conductive material of an adjacent unit to define a separation gap of a selected width and length whereby said width and length of said gap and said resistivity of said resistive coating establish a unit resistance for said units;

connection elements at said joined ends of said plurality of resistive elements connected to said circuit means for applying voltage to said joined ends; and

a plurality of electrodes positioned on, and electrically connected to, said resistive coating along a preselected symmetrical path proximate each perimeter edge of said resistive coating, said electrodes each being connected to selected positions along said plurality of resistance elements to introduce said orthogonal electric fields in said resistive coating, said electrodes having a selected spacing and each electrode having an effective length along said path to produce a selected voltage gradient at each of said electrodes to compensate for any cumulative voltage drop along said resistance element perpendicular to current flow through said resistive coating during operation of said resistive touchscreen when said orthogonal electric fields are introduced into said resistive coating.

13. A resistive touchscreen for providing information as to loci of points along a line of touch by a hand-held object, and selectively discriminating against contact of other objects, said resistive touchscreen comprising:

a substrate;

a resistive coating applied to a surface of said substrate, said resistive coating having a selected substantially uniform resistivity throughout said resistive coating, said resistive coating defining perimeter edges;

field generating means connected proximate said perimeter edges of said resistive coating for producing orthogonal electrical fields in said resistive coating;

a conductive layer overlaying and uniformly spaced from said resistive coating for contacting said resistive coating when touched by the object, said conductive layer divided into a plurality of electrically separated conductive regions, at least one of said regions for receiving the line of touch by the hand-held object and at least one region for supporting the hand;

insulator means for preventing inadvertent contact between said conductive regions and said resistive coating;

a circuit means for applying voltages in proper time sequence to said field generating means, and for receiving and analyzing signals from said plurality of conductive regions to ascertain the information as to the loci of points of the touch; and

a switch means connected to each of said conductive regions to selectively connect at least one of said conductive regions with said circuit means whereby a portion of said resistive coating associated with said connected conductive region is active for providing information at said circuit means as to the loci of points of the touch of the object to said connected conductive region, and whereby portions of said resistive coating associated with conductive regions not attached by said switch means to said circuit means are inactive as to providing position information to discriminate against touch of the hand.

14. The resistive touchscreen of claim 13 further comprising insulator means for preventing inadvertent contact between said conductive layer and said resistive coating.

15. The resistive touchscreen of claim 14 wherein said insulator means is a plurality of substantially uniformly distributed insulator islands positioned between said conductive regions and said resistive coating, said insulator islands having a height sufficient to prevent said inadvertent contact, and allow contact when said conductive layer is touched by the object.

16. The resistive touchscreen of claim 13 wherein said field generating means comprises:

a plurality of resistance elements one each being positioned proximate each of said perimeter edges of said resistive coating, each of said plurality of resistance elements having opposite ends joined to proximate ends of adjoining resistance elements, each of said plurality of resistance elements comprising a plurality of discontinuous units in electrical contact with said resistive coating, each of said units formed by at least one line of conductive material spaced from a line of conductive material of an adjacent unit to define a separation gap of a selected width and length whereby said width and length of said gap and said resistivity of said resistive coating establish a unit resistance for said units;

connection elements at said joined ends of said plurality of resistive elements connected to said circuit means for applying voltage to said joined ends; and

a plurality of electrodes positioned on, and electrically connected to, said resistive coating along a preselected symmetrical path proximate each perimeter edge of said resistive coating, said electrodes each being connected to selected positions along said plurality of resistance elements to introduce said orthogonal electric fields in said resistive coating, said electrodes having a selected spacing and each electrode having an effective length along said path to produce a selected voltage gradient at each of said electrodes to compensate for any cumulative voltage drop along said resistance element perpendicular to current flow through said resistive coating during operation of said resistive touchscreen when said orthogonal electric fields are introduced into said resistive coating.

18. The resistive touchscreen of claim 16 wherein said first and second resistive layers are separated with a plurality of substantially uniformly distributed insulator islands, said insulator islands having a height sufficient to prevent inadvertent contact between said first and second resistive layers, and allow contact when one of said resistive layers is touched by the object.

19. The resistive touchscreen of claim 16 wherein said field generating means comprises:

a first pair of electrodes in electrical contact with said first resistive layer at opposite of said perimeter edges;

a second pair of electrodes in electrical contact with said second resistive layer at opposite of said perimeter edges, said second pair of electrodes being orthogonally arranged with respect to said first pair of electrodes; and

connections from said first and second pair of electrodes to said circuit means to receive voltages in a selected timed sequence to produce electrical fields in said first and second resistor layers that are intersecting with respect to each other.

17. A resistive position touchscreen for providing information as to a point of touch by an object, and selectively discriminating against contact of other objects, said resistive touchscreen comprising:

a first resistive layer having a selected substantially uniform resistivity throughout said first resistive layer, said first resistive layer defining perimeter edges;

a second resistive layer closely spaced from said first resistive layer, said second resistive layer having a selected substantially uniform resistivity throughout said second resistive layer of a value corresponding to said resistivity of said first resistive layer, said second resistive layer defining perimeter edges, at least one of said first and second resistive layers divided into a plurality of electrically separated regions;

electrical field generating means connected proximate opposite of said perimeter edges of said first and second resistive layers for producing intersecting electrical fields in said resistive touchscreen in alternating timed sequence;

a circuit means for applying voltages in proper timed sequence to said field generating means, and for receiving and analyzing signals from said plurality of separated regions to ascertain the information as to the point of touch; and

a switch means connected to each of said electrically separated regions to selectively connect at least one of said separated regions with said circuit means whereby a portion of said at least one of said first and second resistive layers associated with said connected separated region is active for providing information at said circuit means as to the position of a touch of the object to said connected separated region, and whereby portions of said at least one of said first and second resistive layers associated with separated regions not attached by said switch means to said circuit means are inactive as to providing position information.

20. The touchscreen of claim 17 wherein both of said first and second resistive layers are divided into a plurality of electrically separated regions, electrodes of each said separated regions connected to said circuit means.