Coordinate reading apparatus

• US 5,025,410 A
• Filed: 08/11/1988
• Issued: 06/18/1991
• Est. Priority Date: 08/12/1987
• Status: Expired due to Term

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Seiko Instruments Incorporated (Seiko Group)
• Inventors: Morita, Yoshiyuki
• Primary Examiner(s): Fleming, Michael R.
• Assistant Examiner(s): HAUSER, ROBERT
• Application Number:
  US07/233,263
• Time in Patent Office: 1,041 Days
• Field of Search: 178/18, 178/19, 178/20, 364/556, 364/900, 364/200
• US Class Current: 178/18.01
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A coordinate reading apparatus for inputting coordinate data to a computer and operable in either a relative coordinate mode or an absolute coordinate mode, the apparatus including a tablet defining a coordinate surface and a coordinate designator movable across the surface so that signals are generated which are inversely proportional to the distance between the designator and the surface. In order to derive an indication of the position of the designator relative to the surface, the generated signals are compared with a reference signal and an output is produced only when the maximum generated signal exceeds the reference signal. The value of the reference signal is varied in dependence on which coordinate mode is to be employed.

Claims

1. A coordinate reading apparatus for inputting coordinate data to a computer and operable in a selected one of a relative coordinate mode and a second mode, said apparatus comprising:

a first member constituting a tablet defining a coordinate surface;

a second member in the form of a coordinate designator movable across said surface so that a distance exists between said designator and said surface;

position signal producing means associated with said members for producing a plurality of induced signals each inversely proportional to the distance between said designator and said surface so that one of the induced signals will have a value greater than the value of each other induced signal so that the value of the one of the induced signals will be a maximum induced signal value relative to the values of all of the induced signals; and

coordinate value outputting means connected to said position signal producing means for producing coordinate value output signals representative of the coordinate value of the point designated by said designator, wherein said outputting means comprise;

mode setting means responsive to a setting operation for generating a control signal indicative of the relative coordinate mode;

selecting means for producing a first signal representing a predetermined value in the absence of the control signal, and responsive to the control signal for selectively producing, in place of the first signal, a second signal representing a value greater than the predetermined value;

comparator means connected to said position signal producing means and to said selecting means for comparing the maximum induced signal value produced by said position signal producing means with the signal being produced by said selecting means and producing a comparison signal when the maximum induced signal value exceeds the value represented by the signal being produced by said selecting means; and

coordinate value calculating means connected to said position signal producing means and to said comparator means for producing a coordinate value output signal from the induced signal value occurring in the time coincidence with the comparison signal.

2. Apparatus as defined in claim 1 wherein the two modes are absolute coordinate value mode and relative coordinate value mode and said calculating means are operative for producing coordinate value output signals associated with either mode.

3. Apparatus as defined in claim 2 wherein said calculating means are connected for producing output signals based on the selected mode indicated by the control signal.

4. A coordinate reading apparatus for inputting coordinate data to a computer and operable in a selected one of a relative coordinate mode and an absolute coordinate mode, said apparatus comprising:

a first member constituting a tablet defining a coordinate surface;

a second member in the form of a coordinate designator movable across said surface so that one of the induced signals will have a value greater than the value of each other induced signal so that the value of the one of the induced signals will be maximum induced signal value relative to the values of all of the induced signals;

position signal producing means associated with said members for producing a plurality of induced signals each inversely proportional to the distance between said designator and said surface; and

coordinate value outputting means connected to said position signal producing means for producing coordinate value output signals representative of the coordinate value of the point designated by said designator, wherein said outputting means comprise;

mode setting means responsive to a manual setting operation to designate a selected mode for producing a first control signal when the absolute coordinate mode is designated by a setting operation and a second control signal when the relative coordinate mode is designated by a setting operation;

selecting means responsive to the signal produced by said setting means for producing a first signal representing a first predetermined value when the first control signal is being produced and a second signal representing a second predetermined value greater than the first predetermined value when the second control signal is being produced;

comparator means connected to said position signal producing means and to said selecting means for comparing the maximum induced signal value produced by said position signal producing means with the signal being produced by said selecting means and producing a comparison signal when the maximum induced signal value exceeds the value represented by the signal being produced by said selecting means; and

coordinate value calculating means connected to said position signal producing means and to said comparator means for producing a coordinate value output signal from the induced signal value occurring in time coincidence with the comparison signal.

5. Apparatus as defined in claim 4 wherein said calculating means for calculating absolute coordinate values and means for calculating relative coordinate values.

6. Apparatus as defined in claim 5 wherein said calculating means comprise means for operating said means for calculating absolute coordinate values when said mode setting means are producing the first control signal and for operating said means for calculating relative coordinate values when said mode setting means are producing the second control signal.