Display unit

• US 4,841,290 A
• Filed: 09/25/1987
• Issued: 06/20/1989
• Est. Priority Date: 09/25/1986
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Saito, Yusaku, Watanabe, Syoyu, Nakano, Masaaki, Iwata, Syuji
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): OBERLEY, ALVIN E
• Application Number:
  US07/101,032
• Time in Patent Office: 634 Days
• Field of Search: 340/365 P, 340/706, 340/707, 340/708, 340/709, 340/815.3, 340/711, 340/712, 350/332, 350/333, 178/18, 178/19
• US Class Current: 345/179
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

In a display unit comprising a plate-shaped display panel with X-Y matrix electrodes consisting of two groups of electrodes, X-axis electrodes and Y-axis electrodes, display signals are applied to the X-Y matrix electrodes, a.c. current is applied to at least one group of electrodes one after another, and the phase of the a.c. current is compared with that of the output of an input pen having means for detecting the magnetic flux induced by the a.c. current, so that the position of the input pen on the display panel is detected from the result of the comparison.

Claims

1. A display unit with position detecting capabilities, said display unit comprising:

a flat-plate-shaped display panel having X-Y matrix electrodes consisting of two groups of electrodes which are arranged in a crossed-grid fashion to cover a major portion of said display panel;

display-signal applying means for applying display signals to said X-Y matrix electrodes;

current applying means for applying a current having a.c. components to at least one group of said X-Y matrix electrodes in such a manner that said current is sequentially applied to respective one of said electrodes in said at least one group, in a predetermined sequential order;

an input pen with magnetic flux detecting means for detecting magnetic flux associated with a current flowing in an electrode at a matrix location where said input pen is applied;

phase comparison means for comparing a phase of said current applied to said electrodes with that of an output signal of said magnetic flux detecting means; and

position detecting means for detecting the position of said input pen on said display panel according to an output signal of said phase comparison means.

2. A display unit as claimed in claim 1, further comprising:

driver means having a first driver connected to first ends of a selected group of electrodes and having a second driver connected to opposite ends of said selected group of electrodes; and

wherein said current applying means, in a display mode, causes said first and second drivers to output said display signals at the same voltage at said first and opposite ends of an electrode, and, in a position detection mode, causes said first and second drivers at said first and opposite ends of a selected one of said electrodes to output sine wave voltages different by 180°

in phase from each other.