Display module with reduced power consumption

• US 6,323,849 B1
• Filed: 01/22/1999
• Issued: 11/27/2001
• Est. Priority Date: 01/22/1999
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Roccapriore, Phillip L., He, Fan, Grivas, Chris
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US09/236,119
• Time in Patent Office: 1,040 Days
• Field of Search: 345/204, 345/211, 345/98, 345/100, 345/87, 345/214
• US Class Current: 345/204
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A display module (100) with reduced power consumption uses a control circuit (110) to reset row and column display drivers (130, 140) and turn off a portion of the display (150) when the display module (100) is in a partial display mode. The partial display mode allows a reduction in the driving voltages for the display which in turn reduces the power needed by the bias voltage divider (120) which produces the driving voltages. The display module (100) with reduced power consumption is applicable to both LCD and non-LCD technologies, such as electroluminescence or cathode ray tube, using a multiplex or scanning methodology.

Claims

1. A liquid crystal display module comprising:

a microprocessor having a line control signal output, a frame control signal output, and a partial display control signal output;

a control circuit having a display driver reset signal output, the control circuit coupled to the partial display control signal output, the line control signal output, and the frame control signal output of the microprocessor;

a row display driver coupled to the line control signal output and the frame control signal output of the microprocessor, the row display driver coupled to the display driver reset signal output of the control circuit;

a column display driver coupled to the microprocessor;

a liquid crystal display coupled to the row display driver and the column display driver; and

a bias voltage divider coupled to the row display driver and the column display driver.

2. A display module according to claim 1, the control circuit comprises a counter circuit having inputs coupled to the partial display control signal output, the line control signal output and the frame control signal output of the microprocessor, an output of the counter circuit is the display driver reset signal output.

3. A display module according to claim 1, the control circuit comprises a timer circuit having inputs coupled to the partial display control signal output, the line control signal output and the frame control signal output of the microprocessor, an output of the timer circuit is the display driver reset signal output.

4. A display module according to claim 1, the bias voltage divider comprises a plurality of voltage outputs formed by a voltage divider network having a bias voltage input, a micro-power amplifier disposed between each of the voltage outputs and the bias voltage input, a buffer coupled to an output of at least some of the micro-power amplifiers.

5. A display module according to claim 4, each buffer comprises a bipolar transistor follower.

6. A display module according to claim 4, a voltage compensation circuit disposed between first and second voltage outputs, the voltage compensation circuit disposed between inputs of the corresponding first and second micro-power amplifiers and the bias voltage input.

7. A radiotelephone comprising:

a microprocessor having a line control signal output, a frame control signal output, and a partial display control signal output;

a control circuit having a display driver reset signal output, the control circuit coupled to the partial display control signal output, the line control signal output, and the frame control signal output of the microprocessor

a row display driver coupled to the line control signal output and the frame control signal output of the microprocessor, the row display driver coupled to the display driver reset signal output of the control circuit;

a column display driver coupled to the microprocessor;

a liquid crystal display coupled to the row display driver and the column display driver; and

a bias voltage divider coupled to the row display driver and the column display driver.

8. A radiotelephone according to claim 7, the control circuit comprises a counter circuit having inputs coupled to the partial display control signal output, the line control signal output and the frame control signal output of the microprocessor.

9. A radiotelephone according to claim 7, the control circuit comprises a timer circuit having inputs coupled to the partial display control signal output, the line control signal output and the frame control signal output of the microprocessor.

10. A radiotelephone according to claim 7, a bias voltage divider coupled to the row display driver and the column display driver, the bias voltage divider comprises a plurality of voltage outputs formed by a voltage divider network having a bias voltage input, a micro-power amplifier disposed between each of the voltage outputs and the bias voltage input, a buffer coupled to an output of at least some of the micro-power amplifiers.

11. A method for operating a radiotelephone having a display driven by a column display driver and a row display driver in a partial display mode, the method comprising:

generating a partial display control signal by detecting a condition of the radiotelephone in which it is desirable to display a predetermined partial portion of the display;

generating a display driver reset signal dependent on the partial display control signal by determining when the predetermined partial portion of the display has been activated with a bias voltage; and

resetting the row display driver after the predetermined partial portion of the display has been activated by communicating the display driver reset signal to the row driver.

12. A method according to claim 11, determining when the predetermined partial portion of the display has been activated by counting a predetermined number of line control signal pulses.

13. A method according to claim 11, determining when the predetermined partial portion of the display has been activated by operating a timer circuit.

14. A method according to claim 11, varying a line control signal pulse frequency based on the partial display control signal.

15. A method according to claim 11, generating the partial display control signal based on whether the radiotelephone is in a standby mode.

16. A method according to claim 11, generating the partial display control signal based on whether a predetermined amount of time has elapsed since a key of the radiotelephone was activated.

17. A method according to claim 11, generating the partial display control signal based on a physical condition of the radiotelephone.

18. A method according to claim 11, generating the partial display control signal based on whether a keypad cover is covering a keypad of the radiotelephone.

19. A method according to claim 11, generating the display driver reset signal by counting a predetermined number of lines of the display activated by the row display driver.

20. A method according to claim 11, generating the display driver reset signal by timing a predetermined elapsed time period corresponding at least approximately to a predetermined number of lines of the display activated by the row display driver.