Sensing unit for a position detecting apparatus and its manufacturing method

• US 5,444,190 A
• Filed: 06/17/1992
• Issued: 08/22/1995
• Est. Priority Date: 12/05/1991
• Status: Expired due to Term

• Current Assignee: Kabushikikaisha Wacom
• Original Assignee: Kabushikikaisha Wacom
• Inventors: Yamanami, Tsuguya, Chikami, Toshihide
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Kim, Kevin
• Application Number:
  US07/899,782
• Time in Patent Office: 1,161 Days
• Field of Search: 178/18, 178/19, 178/20
• US Class Current: 178/18.03
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

The present invention provides a sensing unit for a position detecting apparatus permitting freer setting of a reading efficiency and having a thinner appearance and its manufacturing method for realizing simple manufacturing, high yield, and low cost.

According to the present invention, two plies of conductor patterns 22 and 23 are produced on one side 21a of an insulating substrate 21 to form a plurality of sense wires, a shielding plate 28 is adhered to other side of the insulating substrate 21, then the insulating substrate 21 is died together with the shielding plate 28. This obviates through holes for which drilling the insulating substrate is required, and diminishes the difference between the distances of the two plies of conductor patterns 22 and 23 from a position indicator. Furthermore, a spacer for separating conductor patterns from a shield becomes unnecessary.

Claims

1. A sensing unit for a position detecting apparatus having a plurality of sense wires formed of at least two layers of conductor patterns,

said two layers of conductor patterns being successively laminated on one side of an insulating substrate such that a top one of the two layers is free of an opposed substrate, and a magnetic shield mounted on another side of said insulating substrate so as to reduce the influence of external electromagnetic waves and reduce external leakage of an electromagnetic wave coupled between the position detecting apparatus and the two layers of conductor patterns,

the two layers of conductor patterns having respective upper and lower land patterns which abut each other for electrical connection, the upper land pattern extending through an electrical insulating layer and having a bottom face electrically and mechanically connected to an upper face of the lower land as a result of the abutting relation of the upper and lower lands.

2. A sensing tablet for the position of a position indicator responsive to waves including magnetic components comprising

an insulating substrate having opposed first and second faces,

a first plurality of spaced electrical conducting leads carried only by said substrate extending in a first coordinate direction, the first leads being on the same side as said first face,

a second plurality of spaced electrical conducting leads carried only by said substrate extending in a second coordinate direction, the second leads being on the same side as said first face,

an electrical insulating layer carried by said substrate on the same side as said first face, said layer being disposed between the first and second pluralities of spaced electrical conducting leads,

a magnetic shield carried by the substrate on the same side as said second face, said shield being positioned and arranged so waves on the side of said second face having magnetic components are decoupled from the first and second leads and there is a reduction of external leakage of an electromagnetic wave coupled between the position indicator and the first and second plurality of leads,

a lower electrically conducting land deposited as a coating on the substrate and electrically connected to the first leads, an upper electrically conducting land overlaying and abutting the lower land and electrically connected to the second leads and to the lower land, the upper land extending through the deposited coating and having a bottom face electrically and mechanically connected to an upper face of the lower land as a result of the abutting relation of the upper and lower lands.

3. The sensing tablet of claim 2 wherein:

the first leads are deposited coatings on the first face, the insulating layer is a deposited coating on the first leads and the first face, and the second leads are deposited coatings on the insulating layer.

4. The sensing tablet of claim 3 further including an electrical insulating overcoat deposited as a coating on the second leads and the insulating layer.

5. The sensing tablet of claim 2 wherein the shield and the second face are bonded to each other by an adhesive.

6. A method of making a sensing tablet for the position of a position indicator responsive to waves including magnetic components comprising:

forming a first plurality of spaced electrical conducting leads as coatings on a first face of a non-metallic substrate having a second opposed face, the first leads extending in a first coordinate direction,

depositing a layer of electrical insulating material on the first face of the substrate and the first leads so exposed portions of the first face and the first leads are overlaid by the electrical insulating material,

forming a second plurality of spaced electrical conducting leads as coatings on the deposited layer,

applying a magnetic shield on the side of the substrate where the second face is located, the shield being applied at a position and arranged so waves on the side of said second face having magnetic components are decoupled from the first and second leads and there is a reduction of external leakage of an electromagnetic wave coupled between the position indicator and the first and second plurality of leads, the shield being applied by applying adhesive to one of the shield and the second face and then contacting the shield, the adhesive and the second face, removing superfluous peripheral portions of the insulating substrate and shield, and

forming a first electrically conductive land on the first face as the first electrically conducting leads are formed and forming a second electrically conductive land so a lower face thereof abuts an upper face of the first land to be electrically and mechanically connected thereto, the second land being formed as the second leads are being formed.

7. The method of claim 6 further including applying an electrically insulating overcoat to the second leads and to the electrical insulating layer.

8. A method of making a sensing tablet for the position of a position indicator responsive to waves including magnetic components comprising:

forming a first plurality of spaced electrical conducting leads as coatings on a first face of a non-metallic substrate having a second opposed face, the first leads extending in a first coordinate direction,

depositing a layer of electrical insulating material on the first face of the substrate and the first leads so exposed portions of the first face and the first leads are overlaid by the electrical insulating material,

forming a second plurality of spaced electrical conducting leads as coatings on the deposited layer,

and applying a magnetic shield on the side of the substrate where the second face is located, the shield being applied at a position and arranged so waves on the side of said second face having magnetic components are decoupled from the first and second leads and there is a reduction of external leakage of an electromagnetic wave coupled between the position indicator and the first and second plurality of leads, forming a first electrically conductive land on the first face as the first electrically conducting leads are formed and forming a second electrically conductive land so a lower face thereof abuts an upper face of the first land to be electrically and mechanically connected thereto, the second land being formed as the second leads are being formed.

9. The method of claim 8 further including applying an electrically insulating overcoat to the second leads and to the electrical insulating layer.