Display-integrated type tablet device

• US 5,592,197 A
• Filed: 07/14/1994
• Issued: 01/07/1997
• Est. Priority Date: 03/12/1991
• Status: Expired due to Fees

• Current Assignee: Sharp Electronics Corporation (Hon Hai Precision Industry Co., Ltd.), Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Tagawa, Takao
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): WU, XIAO MIN
• Application Number:
  US08/275,116
• Time in Patent Office: 908 Days
• Field of Search: 345/173, 345/174, 345/175, 345/176, 345/177, 345/178, 345/179, 345/182, 345/104, 178/18, 178/19
• US Class Current: 345/173
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• 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

A switching circuit 7 switchedly selects the side of a detection control circuit 6 for the coordinate detection period in compliance with control of a control circuit 10. Then according to each signal from the detection control circuit 6, a segment drive circuit 3 generates a segment electrode scan signal to scan segment electrodes X of a liquid crystal panel 1 in turn. Subsequently, a common drive circuit 2 generates a common electrode scan signal to scan common electrodes Y in turn. An x-coordinate detection circuit 8 and a y-coordinate detection circuit 9 detects the x- and y-coordinates of the tip of an electronic pen 11 on the basis of an induced voltage developed to a tip electrode of the electronic pen 11. During the display period, the side of a display control circuit 4 is switchedly selected, displaying an image onto the liquid crystal panel 1. Thus, there is provided a display-integrated type tablet device into which display function has been integrated, in order to make the image easy-to-view and the device itself more compact, less costly.

Claims

1. A display-integrated type tablet device comprising:

a display panel having a plurality of first electrodes arrayed in parallel to one another and a plurality of second electrodes arrayed in parallel to one another in a direction other than the direction in which the first electrodes are arrayed;

an electronic pen having at its tip an electrode electrostatically coupled with the first electrodes and the second electrodes of the display panel;

a display control circuit for producing a display control signal and display data for displaying an image to the plurality of first electrodes and the plurality of second electrodes of the display panel;

a detection control circuit for producing a detection-scanning control signal for scanning the first electrodes and the second electrodes to detect coordinates of the tip of the electronic pen on the display panel;

a switching circuit for switchedly selecting a side of the display control circuit for a display period to produce the display control signal and display data from the display control circuit and for switchedly selecting a side of the detection control circuit for a coordinate detection period to produce the detection-scanning control signal from the detection control circuit, under control of a control circuit;

a second-electrode drive circuit for generating a second-electrode drive signal during the display period to select among the second electrodes in turn according to the display control signal;

a first-electrode drive circuit for generating a first-electrode drive signal during the display period to display pixels relative to the second electrodes selected by the second-electrode drive signal according to the display control signal and display data and for generating a first electrode scan signal during the coordinate detection period to feed a scan voltage to the first electrodes in turn according to the detection-scanning control signal from the switching circuit; and

a coordinate detection circuit for receiving an input of induced voltage developed to the electrode of the electronic pen according to the first-electrode scan signal fed from the first-electrode drive circuit to the first electrodes, and then detecting coordinates of the tip of the electronic pen by a predetermined procedure on the basis of the induced voltage derived from the electronic pen to produce an x-coordinate signal, wherein the second-electrode drive circuit generates during the display period the second-electrode drive signal in which a coordinate detection signal including a predetermined non-direct current voltage component is superimposed onto a scan pulse, and

the coordinate detection circuit has an extraction means for separating the coordinate detection signal out of the induced voltage fed from the electronic pen, and based on the extracted coordinate detection signal, detects a y-coordinate of the tip of the electronic pen.

2. A display-integrated type tablet device as claimed in claim 1, wherein the extraction means is a filter.

3. A display-integrated type tablet device as claimed in claim 1, wherein the coordinate detection signal is a high-frequency voltage signal.

4. A display-integrated type tablet device, comprising:

a display panel having a plurality of first electrodes arrayed in parallel to one another and a plurality of second electrodes arrayed in parallel to one another in a direction other than the direction in which the first electrodes are arrayed forming a pixel matrix;

an electronic pen having at its tip an electrode coupled with the first electrodes and the second electrodes of the display panel by floating capacity;

a display control circuit for producing a display control signal and display data for displaying an image to the plurality of first electrodes and the plurality of second electrodes of the display panel;

a detection control circuit for producing a detection-scanning control signal for scanning the first electrodes and the second electrodes to detect coordinates of the tip of the electronic pen on the display panel;

a switching circuit for switchedly selecting a side of the display control circuit for a display period to produce the display control signal and display data from the display control circuit and for switchedly selecting a side of the detection control circuit for a coordinate detection period to produce the detection-scanning control signal from the detection control circuit, under control of a control circuit;

a second-electrode drive circuit for generating a second-electrode drive signal during the display period to select in turn among the second electrodes according to the display control signal and for generating a second-electrode scan signal during the coordinate detection period to feed a scan voltage to the second electrodes in turn according to the detection-scanning control signal from the switching circuit;

a first-electrode drive circuit for generating a first-electrode drive signal during the display period to display pixels relative to the second electrodes selected by the second-electrode drive signal according to the display control signal and display data and for generating a first electrode scan signal during the coordinate detection period to feed a scan voltage to the first electrodes in turn according to the detection-scanning control signal from the switching circuit; and

a coordinate detection circuit for receiving an input of induced voltage developed to the electrode of the electronic pen according to the second-electrode scan signal and the first-electrode scan signal fed from the second-electrode drive circuit and the first-electrode drive circuit to the second electrodes and the first electrodes, respectively, and then detecting coordinates of the tip of the electronic pen by a predetermined procedure on the basis of the induced voltage derived from the electronic pen to produce an x-coordinate signal and y-coordinate signal, wherein

the display period and the coordinate detection period are appropriately set by the control circuit, so that during the display period, the image is displayed onto the pixel matrix of the display panel while during the coordinate detection period a point of the tip of the electronic pen on the display panel is detected without displaying the image onto the pixel matrix, and

wherein at least one drive circuit of the second drive circuit and the first drive circuit generates during the coordinate detection period a scan signal in which a high-frequency wave has been inserted into the scan period in the scan signal, and wherein the coordinate detection circuit, having a filter for separating a high-frequency component of an induced voltage derived from the electronic pen, separates the high-frequency component of an induced voltage developed to the electrode of the electronic pen according to the scan signal, generated by at least one drive circuit, into which the high-frequency wave has been inserted and thereby detects coordinates of the tip of the electronic pen by a predetermine procedure according to the separated high-frequency component.

5. A display-integrated type tablet device as claimed in claim 4, wherein the second drive circuit generates during the coordinate detection period a second electrode scan signal in which a first high-frequency wave having a specified frequency has been inserted into the scan period, the first drive circuit generates during the coordinate detection period a first electrode scan signal in which a second high-frequency wave having a specified frequency different from the first high-frequency wave has been inserted into the scan period, and wherein the coordinate detection circuit has both a first filter for separating the first high-frequency component of an induced voltage developed to the electrode of the electronic pen according to the second electrode scan signal and the first electrode scan signal, and a second filter for separating the second high-frequency component thereof, and detects the y-coordinate of the tip of the electronic pen by a predetermined procedure according to the first high-frequency component separated by the first filter while it detects the x-coordinate of the tip of the electronic pen by a predetermined procedure according to the second high-frequency component separated by the second filter.

6. A display-integrated type tablet device as claimed in claim 5, wherein the frequencies of the first and the second high-frequency waves are not any odd multiple of each other.