Liquid crystal display with temperature compensation

• US 10,643,554 B2
• Filed: 10/01/2015
• Issued: 05/05/2020
• Est. Priority Date: 10/02/2014
• Status: Active Grant

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Tari, Joseph A., Keiling, Cheryl M., Creighton, Jamie, Richards, Jeffrey C., Rudd, Sean, Volkmann, Charles
• Primary Examiner(s): Sarma, Abhishek
• Application Number:
  US15/515,462
• Publication Number:
  US 20170221430A1
• Time in Patent Office: 1,678 Days
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A liquid crystal display (LCD) unit and associated method for compensating for the effects of low temperatures. The LCD unit includes a heating panel disposed adjacent to the LCD panel. A temperature sensor measures the temperature of the LCD panel. A controller compares the measured temperature to a threshold temperature and one or more set points and operates the heating panel accordingly. Further, the controller is configured to control one or more contrast parameters in response to the comparison of the measured temperature to the one or more set points.

Claims

1. A liquid crystal display (LCD) unit with temperature compensation, comprising:

a housing;

an LCD panel arranged in the housing;

a backlight for the LCD panel arranged in the housing;

a heating panel arranged between the LCD panel and the backlight;

a temperature sensor arranged at the LCD panel and configured to measure a temperature of the LCD panel; and

a controller arranged to receive information from the temperature sensor, the controller being configured to compare the measured temperature to a threshold temperature, wherein when the measured temperature is below the threshold temperature the controller is further configured to compare the measured temperature to one or more setpoints and control the heating panel and one or more contrast parameters of the LCD panel in response to the comparison of the measured temperature with the one or more setpoints.

2. The LCD unit of claim 1, wherein the heating panel is formed from indium-tin-oxide.

3. The LCD unit of claim 1, wherein the controller includes a PWM circuit arranged to deliver power to the heating panel at a selected duty cycle.

4. A method of operating a liquid crystal display (LCD), comprising:

measuring a temperature of an LCD panel;

comparing the measured temperature to a threshold temperature;

when the measured temperature is below a threshold temperature, comparing the measured temperature to a plurality of set points; and

controlling one or more contrast parameters of the LCD panel in response to the measured temperature; and

operating a heating panel arranged within the LCD at one of a plurality of control rates in response to the comparison of the measured temperature to the plurality of set points, wherein the plurality of control rates control power supplied to the heating panel at multiple controlled rates.

5. The method of claim 4, wherein the plurality of control rates comprise controlling a pulse width modulation circuit at different duty cycle levels.

6. The method of claim 4, wherein the one or more contrast parameters include one or more of potentiometer value, bias ratio, and gain value.

7. The method of claim 4, wherein the heating panel is arranged within the LCD panel.