Touch screen panel for sensing touch using TFT photodetectors integrated thereon

Patent metadata

Field	Value
Publication number	US-12446335-B2
Application number	US-202418641093-A
Country	US
Kind code	B2
Filing date	Apr 19, 2024
Priority date	Aug 20, 2019
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A touch screen panel using a thin film transistor (TFT) photodetector includes a touch panel including at least one unit pattern for sensing light reflected by a touch by using a TFT photodetector including an active layer formed of amorphous silicon or polycrystalline silicon on an amorphous transparent material, and a controller configured to scan the at least one unit pattern and read touch coordinates as a result of the scanning.

First claim

What is claimed is:

1. A touch screen panel using a thin film transistor (TFT) photodetector, the touch screen panel comprising:
a touch panel including a plurality of unit patterns for sensing light reflected by a touch by using a TFT photodetector; and
a controller configured to read touch coordinates on the touch panel,
wherein the TFT photodetector comprises:
an active layer formed of amorphous silicon or polycrystalline silicon on an amorphous transparent material;
a gate electrode; and
a backlight light source configured to irradiate backlight in a transmission direction of the transparent material through a space between adjacent TFT photodetector;
an oxide film interposed between the active layer and the gate electrode, and
wherein electrons by tunneling from the active layer to the oxide film migrate into the gate electrode,
wherein the plurality of unit patterns collect the backlight passed through the transparent material and then reflected back from a body, and the controller is configured to process touch recognition along with the positioning of the body by the light generated from the backlight light source and then collected.

2. The touch screen panel according to claim 1 , wherein the electron migration changes a threshold voltage of a current channel between a source and a drain in correspondence with a change in a total amount of charge in the gate, photocurrent proportional to the intensity of the incident light flows in the active layer, and a voltage output is generated from the flowing photocurrent.

3. The touch screen panel according to claim 2 , wherein the plurality of unit patterns comprise a plurality of first unit patterns which are arranged in parallel with each other in a first direction, and a plurality of second unit patterns which are arranged in parallel with each other in a second direction crossing the first direction, insulated from the plurality of first unit patterns.

4. The touch screen panel according to claim 3 , wherein the controller is configured to:
scan each of the plurality of first unit patterns by supplying a first voltage to the plurality of first unit patterns in line by line manner;
scan all of the plurality of second unit patterns by sequentially supplying the first voltage to the plurality of second unit patterns according to a first scanning control signal, each time each of the plurality of first unit patterns is scanned; and
connect to the first and second unit patterns of the touch panel and detect a touch recognition signal indicating whether a touch has occurred, and a touch position by comparing a voltage of initial capacitance of each of the first and second unit patterns with a voltage of current capacitance of the unit pattern, each time the first voltage is supplied to the plurality of first unit patterns and the plurality of second unit patterns by a driving circuit.

5. The touch screen panel according to claim 3 , wherein the controller comprises a first driving circuit configured to scan the first unit patterns by supplying the first voltage to the first unit patterns, and a second driving circuit configured to scan the second unit patterns by supplying the first voltage to the second unit patterns,
wherein the first driving circuit comprises a plurality of first control switches configured to respectively supply the first voltage to the plurality of first unit patterns in response to a first scanning control signal and a second scanning signal from the controller, and a plurality of second control switches configured to respectively supply the first voltage to the plurality of second unit patterns in response to the first scanning control signal and the second scanning signal from the controller.

6. The touch screen panel according to claim 1 , wherein the controller comprises:
a first integration processor including a first capacitor charged by a capacitance variation in the first unit patterns; and
a comparator configured to compare a level of an output signal of the first integration processor with a predetermined reference level,
wherein when the level of the output signal of the first integration processor is higher than the reference level, the comparator controls each of the plurality of switches to discharge the first capacitor.

7. The touch screen panel according to claim 6 , wherein the controller further comprises:
a second integration processor including a second capacitor charged by the charged first capacitor; and
a calculator configured to determine a touch input from an output signal of the second integration processor.

8. The touch screen panel according to claim 7 , wherein the controller further comprising a noise canceller including a plurality of switches operating according to an output of the comparator,
wherein the noise canceller comprises a first switch connected to a ground and a second switch connected to an input node of the second integration processor, and
wherein when the level of the output signal of the first integration processor is higher than the reference level, the comparator is configured to turn off the second switch and turn on the first switch.

9. The touch screen panel according to claim 6 , wherein the comparator comprises:
a first comparison circuit configured to compare the level of the output signal of the first integration processor with a first reference level; and
a second comparison circuit configured to compare the level of the output signal of the first integration processor with a second reference level, and
wherein when the level of the output signal of the first integration processor is higher than the first reference level or lower than the second reference level, the comparator operates each of the plurality of switches to discharge the first capacitor.

10. The touch screen panel according to claim 1 , wherein the touch panel further comprises an infrared (IR) light source configured to cause diffused reflection on the transparent material by irradiating IR light from one side of the transparent material, and
wherein the plurality of unit patterns collect the IR light diffusedly reflected from a body contacting the transparent material, and the controller processes touch recognition along with positioning of the body by the light generated from the IR light source and then collected.

11. The touch screen panel according to claim 1 , wherein the TFT photodetector is electrically coupled to at least one transistor and the at least one transistor is configured to generate a voltage output from photocurrent generated in the active layer.

12. The touch screen panel according to claim 1 , wherein the active layer includes a material having a conductive property controllable by tunneling or an electric field.

13. The touch screen panel according to claim 1 , wherein the TFT photodetector uses light generated from a display panel as a light source for the plurality of unit patterns.

14. An electronic device using a thin film transistor (TFT) photodetector, the electronic device comprising:
a touch panel including a plurality of unit patterns for sensing light reflected by a touch by using a TFT photodetector;
a backlight light source configured to irradiate backlight in a transmission direction of a transparent material through a space between adjacent TFT photodetector; and
a controller configured to scan the plurality of unit patterns and read touch coordinates as a result of the scanning,
wherein the TFT photodetector includes a source, a drain and an active layer formed between the source and the drain,
wherein the active layer includes a current channel formed between the source

Assignees

• Kim Hoon

Inventors

• Kim Hoon

Classifications

• H10F77/16

  Material structures, e.g. crystalline structures, film structures or crystal plane orientations · CPC title

• H10F39/80377

  characterised by the channel of the transistor, e.g. channel having a doping gradient · CPC title

• H10F39/8037

  the integrated elements comprising a transistor · CPC title

• H10F39/014

  of CMOS image sensors · CPC title

• H10F30/282

  Insulated-gate field-effect transistors [IGFET], e.g. MISFET [metal-insulator-semiconductor field-effect transistor] phototransistors · CPC title