Data input device that utilizes a layer of magnetic particles to store non-volatile input data that is magnetically coupled to an underlying MRAM array

• US 7,532,203 B2
• Filed: 04/26/2004
• Issued: 05/12/2009
• Est. Priority Date: 04/26/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Sharma, Manish
• Primary Examiner(s): LEWIS, DAVID LEE
• Application Number:
  US10/831,110
• Publication Number:
  US 20050237309A1
• Time in Patent Office: 1,842 Days
• Field of Search: 345/156, 345/157, 345/158, 345/159, 345173-178, 345/179, 178/18.03, 178/19.01, 178/19.02, 178/19.03, 178 1801- 1811
• US Class Current: 345/173
• CPC Class Codes: G06F 3/046 by electromagnetic means
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 3/3486 using light modulating elements actuated by a magnetic field

Abstract

An input device includes a plurality of MRAM cells and a layer of particles. An MRAM cell in the input device includes a sense layer having a magnetic orientation. At least one particle of the layer of particles is located near the MRAM cell such that the particle affects the magnetic orientation of the sense layer of the MRAM cell.

Claims

1. An input device, comprising:

a plurality of MRAM cells, each including a sense layer having a changeable magnetic orientation and a reference layer having a pinned magnetic orientation; and

a layer of particles including at least one particle spaced-apart from a sense layer of a first MRAM cell in said plurality of MRAM cells,

wherein the at least one particle affects an orientation of a magnetic field of the sense layer of the first MRAM cell when a magnetic orientation of the at least one particle is changed.

2. The input device of claim 1, wherein the at least one particle emits a magnetic field with a changeable orientation that affects the orientation of the magnetic field of the sense layer of the first MRAM cell.

3. The input device of claim 2, wherein each of the plurality of MRAM cells further comprises a barrier layer extending between respective sense and reference layers within a corresponding MRAM cell.

4. The input device of claim 3, further comprising a control unit operable to measure a resistance of the first MRAM cell to determine a state of the at least one particle that is spaced-apart from the sense layer of the first MRAM cell.

5. The input device of claim 1, wherein the particles in said layer of particles are magnetic particles.

6. The input device of claim 5, further comprising a magnetic field generating device for altering an orientation of a magnetic field of one or more of the magnetic particles in said layer of particles when placed in proximity to said layer of particles.

7. The input device of claim 6, wherein the magnetic field generating device comprises an electromagnet having a polarity;

and a switch for controlling the polarity of the electromagnet operable to apply a magnetic field to the one or more particles.

8. The input device of claim 5, wherein the magnetic particles have an electrostatic charge.

9. The input device of claim 8, further comprising an electrostatic field generating device for altering an orientation of a magnetic field of one or more of the magnetic particles when placed in proximity to the layer of particles.

10. The input device of claim 1, further comprising an integrated display having a plurality of pixels and wherein at least one of the pixels is directly controlled by at least one of said plurality of MRAM cells.

11. The input device of claim 1, further comprising an integrated display having a plurality of pixels and wherein at least one of the pixels is indirectly controlled by at least one of said plurality of MRAM cells.

12. The input device of claim 1, wherein said layer of particles provide non-volatile data storage that is magnetically coupled to non-volatile data storage provided by said plurality of MRAM cells.

13. The input device of claim 12, further comprising an initializer to apply a voltage to the layer of particles to erase data stored in the layer of particles.

14. A non-volatile input memory device, comprising;

a layer of particles operable to non-volatility store input information; and

a plurality of MRAM cells that are magnetically coupled to the layer of particles, but are electrically insulated from the layer of particles, wherein at least one cell of the plurality of MRAM cells reads the input information stored in at least a portion of the layer of particles.

15. The non-volatile input memory device of claim 14, wherein at least one of the plurality of MRAM cells includes a barrier layer having a magnetic tunnel junction.

16. The non-volatile input memory device of claim 14, wherein at least one of the particles in the layer of particles has an electrostatic charge.

17. The non-volatile input memory device of claim 14, wherein the at least a portion of the layer of particles is operable to receive the input information from a user input device.

18. The non-volatile input memory device of claim 14, further comprising a display having a plurality of pixels and wherein at lease one of the pixels is directly controlled by the input information stored in the layer of particles.

19. The non-volatile input memory device of claim 14, further comprising a display having a plurality of pixels and wherein at least of the pixels is indirectly controlled by the input information stored in the layer of particles.

20. The non-volatile input memory device of claim 14, further comprising an initializer operable to erase the input information stored in the layer of particles.

21. The non-volatile input memory device of claim 14, wherein at least one of the plurality of MRAM cells includes a reference layer having a pinned magnetic orientation, a barrier layer adjacent to the reference layer, and a sense layer adjacent to the barrier layer, the sense layer having a changeable magnetic orientation.

22. A method of operating an input device having a layer of particles therein, each particle having a magnetic orientation, the layer of particles overlaying a plurality of MRAM cells having respective sense and reference layers therein, the method comprising:

changing the magnetic orientation of at least one particle in the layer of particles;

providing a voltage to at least one of the plurality of MRAM cells wherein the at least one MRAM cell is substantially underlying the at least one particle; and

detecting a change in resistance of the at least one MRAM cell in response to said changing the magnetic orientation of the at least one particle in the layer of particles.

23. The method according to claim 22, further comprising activating a pixel of a display in response to the detection of the change in resistance of the at least one MRAM cell.

24. The method according to claim 22, further comprising:

receiving a magnetic field at the layer of particles, wherein the magnetic field is generated by a magnetic field generator and changes the magnetic orientation of the at least one particle.

25. The method according to claim 22, further comprising initializing the apparatus by aligning the magnetic orientation of each particle of the layer of particles in substantially one direction.

26. The method according to claim 25, wherein initializing includes providing a voltage to the layer of particles.

27. The method according to claim 25, wherein initializing includes providing an external magnetic field to the layer of particles.

28. The method according to claim 22, wherein each of the plurality of MRAM cells includes a sense layer having a changeable magnetic orientation and a reference layer having a pinned magnetic orientation;

and wherein the step of changing the magnetic orientation of at least one particle in the layer of particles causes the magnetic orientation of the sense layer to change.

29. The method according to claim 22, further comprising:

receiving an electrostatic field at the layer of particles, wherein the electrostatic field is generated by an electrostatic field generator and changes the magnetic orientation of the at least one particle.

30. An apparatus having a layer of particles, each particle having a magnetic orientation, the layer of particles overlaying and spaced-apart from a plurality of MRAM cells so that the layer of particles and the plurality of MRAM cells are electrically isolated from each other, the apparatus comprising:

means for changing the magnetic orientation of at least one particle in the layer of particles;

means for providing a voltage to at least one of the MRAM cells; and

means for detecting a change in resistance of the at least one of the MRAM cells located under the at least one particle, the change in resistance in response to the change of the magnetic orientation of the at least one particle.

31. The apparatus of claim 30, further comprising means for activating a pixel of a display in response to the detection of the change in resistance of one of the MRAM cells.

32. The apparatus of claim 30, further comprising means for aligning the magnetic orientation of each particle in the layer of particles in substantially one direction.

33. The apparatus of claim 30, wherein the at least one of the MRAM cells further comprises sense means responsive to the magnetic orientation of at least one particle in the layer of particles.

34. A non-volatile data input device, comprising:

an array of MRAM cells having sense layers therein that are switchable between multiple magnetic field orientations and reference layers having pinned magnetic orientations; and

a layer of magnetic particles suspended in a medium disposed on said array of MRAM cells, said layer having a sufficient density of magnetic particles therein to induce non-volatile magnetic coupling between a plurality of the magnetic particles and a corresponding plurality of the sense layers; and

wherein the layer of magnetic particles are electrically insulated from the sense layers in said array of MRAM cells.

35. The device of claim 34, wherein the non-volatile magnetic coupling between a first sense layer and at least one of the magnetic particles disposed opposite the first sense layer is of sufficient strength to cause a change in the magnetic field orientation of the first sense layer in response to a change in orientation of the at least one of the magnetic particles.

36. The device of claim 35, further comprising an initializer configured to erase non-volatile data stored in said layer of magnetic particles.

37. The device of claim 34, wherein each of the plurality of magnetic particles has an electrostatic charge associated therewith.

38. The device of claim 34, wherein said layer of magnetic particles is configured to support a non-volatile reorientation of magnetic particles therein in response to movement of a stylus across the medium.

39. The device of claim 34, further comprising respective pairs of conductors electrically coupled to each of a first plurality of MRAM cells in said array of MRAM cells, said pairs of conductors configured to support the passing of read currents through the first plurality of MRAM cells to thereby determine logic states of the first plurality of MRAM cells;

and wherein said layer of magnetic particles are electrically insulated from said pairs of conductors during said passing of the read currents.