# US 11,029,782 B2 · Light emitting diode (LED) touch display circuit

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- Number: US 11,029,782 B2
- Document ID: US11029782B2
- Status: Granted
- Kind: B2
- Application number: 16/403,200
- Filed: 2019-05-03
- Published: 2020-11-05
- Granted: 2021-06-08
- Earliest claimed: 2019-05-03
- Assignees: Sigmasense, LLC.
- Applicants: SigmaSense, LLC.
- Inventors: Daniel Keith Van Ostrand; Gerald Dale Morrison; Richard Stuart Seger, Jr.; Timothy W. Markison
- Web page: https://patentgrep.com/patent/US11029782B2

## CPC

- G06F 3/04166: {Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184)}
- G06F 3/042: by opto-electronic means
- G06F 3/0421: {by interrupting or reflecting a light beam, e.g. optical touch-screen}
- G06F 3/0488: using a touch-screen or digitiser, e.g. input of commands through traced gestures
- G09G 3/3225: using an active matrix
- G06F 2203/04101: 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
- G09G 2310/066: Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
- G09G 2320/0606: Manual adjustment
- G09G 2354/00: Aspects of interface with display user
- G09G 2360/144: the light being ambient light
- G09G 2370/18: Use of optical transmission of display information
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

A touch display cell includes a light emitting diode (LED) and an LED touch sensor. The LED touch sensor includes a data drive input circuit operable to generate a transmit-receive signal based on a digital input. The transmit-receive signal includes a transmit signal component and a receive signal component. The LED touch sensor further includes a drive-sense circuit operable to: when the transmit signal component is active, forward bias the LED in accordance with a light intensity value of the transmit signal component such that the LED emits light, and when the receive signal component is active: reverse bias the LED such that the LED generates a current based on received light and generate a digital representation of the current. The LED touch sensor further includes a data output circuit operable to produce a digital representation of light intensity based on the digital representation of the current.

## Claims

### Claim 1

A touch display cell comprises:
a light emitting diode (LED); and
an LED touch sensor including:
a data drive input circuit operable to generate an analog input signal based on a digital input, wherein the analog input signal includes a transmit signal component and a receive signal component;
a drive-sense circuit including:
a resistive network operable to:
receive the analog input signal from the data drive input circuit;
generate a reference signal voltage from the analog input signal; and
generate a data signal voltage from the analog input signal;
a difference detection circuit operable to output an analog output voltage based on a comparison of the reference signal voltage and the data signal voltage;
a bi-directional current source operable to generate an error correction current based on the output voltage, wherein the error correction current adjusts the data signal voltage in order to keep inputs to the difference detection circuit substantially equal;
and wherein when the transmit signal component is active, the data signal voltage forward biases the LED in accordance with a light intensity value of the transmit signal component such that the LED emits light; and
when the receive signal component is active, the data signal voltage:
reverse biases the LED such that the LED generates a current based on received light; and
an analog to digital converter (ADC) operable to convert the analog output signal into a digital representation of the current; and
a data output circuit operable to produce a digital representation of light intensity based on the digital representation of the current.

### Claim 2 (depends on 1)

The touch display cell of claim 1 further comprises:
a lens coupled to the LED.

### Claim 3 (depends on 1)

The touch display cell of claim 1 further comprises:
a processing module operable to:
generate the digital input; and
generate a response output based on the digital representation of the light intensity.

### Claim 4 (depends on 3)

The touch display cell of claim 3 further comprises:
the processing module is further operable to:
process the digital representation of the light intensity to determine an ambient light pattern; and
determine an adjusted light intensity value based on the ambient light pattern; and
the drive-sense circuit is further operable to:
when the transmit signal component is active, forward bias the LED in accordance with the adjusted light intensity value such that the LED emits light in accordance with the ambient light pattern.

### Claim 5 (depends on 3)

The touch display cell of claim 3, wherein the processing module is operable to generate the response output by:
processing the digital representation of the light intensity to determine an ambient light pattern that includes a maximum ambient light measurement;
determining a hover indication by:
determining a deviation from the maximum ambient light measurement to a hover threshold, wherein the hover threshold is between a first distance from the LED touch sensor associated with a first ambient light intensity and a second distance from the LED touch sensor associated with a second ambient light intensity, wherein the first distance is closer to the LED touch sensor than the second distance, and wherein the second ambient light intensity is higher than the first ambient light intensity; and
processing the hover indication to generate the response output.

### Claim 6 (depends on 5)

The touch display cell of claim 5, wherein the processing module is operable to generate the response output by:
determining a touch indication by:
detecting a deviation from the maximum ambient light measurement or the hover threshold to a touch threshold, wherein the touch threshold is between the first distance associated with the first ambient light intensity and a surface of the LED touch sensor associated with a third ambient light intensity, wherein the third ambient light intensity is substantially zero; and
processing the touch indication to generate the response output.

### Claim 7 (depends on 6)

The touch display cell of claim 6, wherein the processing module is operable to generate the response output by:
determining a rate of distance change from the second distance to the first distance;
determining a pressure level based on the rate of distance change;
when the pressure level compares favorably to a touch pressure threshold:
determining the touch indication; and
processing the touch indication to generate the response output; and
when the pressure level compares favorably to a hover pressure threshold:
determining the hover indication; and
processing the hover indication to generate the response output.

### Claim 8 (depends on 1)

The touch display cell of claim 1, wherein the analog input signal is a square wave, wherein the square wave has a transmit component, wherein the transmit component includes a pulse width modulation signal representative of a light intensity value and an overall fixed period.

### Claim 9 (depends on 1)

The touch display cell of claim 1, wherein the analog input signal is a sinusoidal signal, wherein the sinusoidal signal has a transmit component based on a light intensity value and an overall fixed period.

### Claim 10

A touch display cell comprises:
a light emitting diode (LED); and
an LED touch sensor including:
a data drive input circuit operable to generate an analog input signal based on a digital input, wherein the analog input signal includes a transmit signal component and a receive signal component;
a drive-sense circuit including:
a resistive network operable to:
receive the analog input signal from the data drive input circuit; and
receive the analog input signal from the data drive input circuit;
generate a reference signal voltage from the analog input signal; and
generate a data signal voltage from the analog input signal;
a difference detection circuit operable to output an analog output voltage based on a comparison of the reference signal voltage and the data signal voltage;
a bi-directional current source operable to generate an error correction current based on the output voltage, wherein the error correction current adjusts the data signal voltage in order to keep inputs to the difference detection circuit substantially equal;
and wherein when the transmit signal component is active, the data signal voltage forward biases the LED in accordance with a light intensity value of the transmit signal component such that the LED emits light; and
when the receive signal component is active, the data signal voltage:
reverse biases the LED such that the LED generates a current based on received light; and
an analog to digital converter (ADC) operable to convert the analog output signal into a digital representation of the current;
a data output circuit operable to produce a digital representation of light intensity based on the digital representation of the current; and
a processing module operable to generate a response output based on the digital representation of the light intensity.