Liquid crystal driver, electronic apparatus, and mobile body

Patent metadata

Field	Value
Publication number	US-10984746-B2
Application number	US-201916727497-A
Country	US
Kind code	B2
Filing date	Dec 26, 2019
Priority date	Dec 27, 2018
Publication date	Apr 20, 2021
Grant date	Apr 20, 2021

Abstract

A liquid crystal driver (100) includes: a segment driving circuit (150) that outputs a segment driving signal (SGQ) for driving a segment electrode of a liquid crystal panel, a first segment terminal (TSD1) from which a segment driving signal (SGQ) is to be output to the segment electrode, a second segment terminal (TSD2) to which a segment monitoring signal (SMN), which is a monitoring signal from the segment electrode, is to be input, and an anomalous segment detection circuit (160) that detects anomalous driving of the segment electrode based on the segment monitoring signal (SMN).

First claim

What is claimed is:

1. A liquid crystal driver comprising:
a segment driving circuit configured to output a first segment driving signal for driving a segment electrode of a liquid crystal panel;
a first segment terminal from which the first segment driving signal is to be output to the segment electrode;
a second segment terminal to which a segment monitoring signal, which is a monitoring signal from the segment electrode, is to be input;
an anomalous segment detection circuit configured to detect anomalous driving of the segment electrode based on the segment monitoring signal; and
a control circuit configured to control a drive timing when the liquid crystal driver drives a liquid crystal panel,
wherein the segment driving circuit includes:
a segment signal output circuit configured to output a segment signal based on segment driving data; and
an output circuit configured to output the first segment driving signal based on the segment signal,
wherein the anomalous segment detection circuit includes an exclusive OR circuit for obtaining an exclusive OR of the segment monitoring signal and the segment signal, and is configured to output an output signal of the exclusive OR circuit as the result of comparison between the segment monitoring signal and the segment signal, and wherein the anomalous segment detection circuit further includes an OR circuit configured to obtain the output signal from the exclusive OR circuit, and to output a summation output signal to the control circuit.

2. The liquid crystal driver according to claim 1 ,
wherein the output circuit includes a first level shifter that level-shifts the segment signal, and is configured to output the first segment driving signal based on an output signal of the first level shifter, and
the anomalous segment detection circuit includes a second level shifter that level-shifts the segment monitoring signal and is configured to output the level-shifted segment monitoring signal to the exclusive OR circuit.

3. The liquid crystal driver according to claim 1 ,
wherein the segment signal output circuit includes:
a polarity inversion circuit configured to perform processing to invert the polarity of the segment driving data, and
a latch circuit that latches the output signal of the polarity inversion circuit by a latch pulse, and outputs the segment signal.

4. The liquid crystal driver according to claim 1 ,
wherein the anomalous segment detection circuit is configured to detect the anomalous driving by comparing the segment monitoring signal and the first segment driving signal.

5. The liquid crystal driver according to claim 4 ,
wherein the segment driving circuit includes:
a segment signal output circuit configured to output a segment signal based on segment driving data; and
an output circuit configured to output the first segment driving signal based on the segment signal, and
the anomalous segment detection circuit is configured to detect the anomalous driving by comparing the segment monitoring signal, the segment signal, and the first segment driving signal.

6. The liquid crystal driver according to claim 5 ,
wherein the anomalous segment detection circuit includes an exclusive OR circuit for obtaining an exclusive OR of the segment monitoring signal, the segment signal, and the first segment driving signal, and
is configured to output an output signal of the exclusive OR circuit as the result of comparison between the segment monitoring signal, the segment signal, and the first segment driving signal.

7. The liquid crystal driver according to claim 6 ,
wherein the output circuit includes a first level shifter that level-shifts the segment signal, and is configured to output the first segment driving signal based on an output signal of the first level shifter, and
the anomalous segment detection circuit includes:
a second level shifter that level-shifts the segment monitoring signal and outputs the level-shifted segment monitoring signal to the exclusive OR circuit, and
a third level shifter that level-shifts the first segment driving signal and outputs the level-shifted first segment driving signal to the exclusive OR circuit.

8. The liquid crystal driver according to claim 1 , further comprising:
a common driving circuit configured to output a common driving signal for driving a common electrode of the liquid crystal panel;
a first common terminal from which the common driving signal is to be output to the common electrode;
a second common terminal to which a common monitoring signal, which is a monitoring signal from the common electrode, is to be input; and
an anomalous common detection circuit configured to detect anomalous driving of the common electrode based on the common monitoring signal.

9. The liquid crystal driver according to claim 1 ,
wherein the segment driving circuit is configured to, when the anomalous driving of the segment electrode has been detected, output the first segment driving signal, or a second segment driving signal for driving the segment electrode separately from the first segment driving signal to the second segment terminal.

10. The liquid crystal driver according to claim 9 ,
wherein the segment driving circuit includes a switch circuit, and
the switch circuit is configured to, when the anomalous driving of the segment electrode is not detected, output the segment monitoring signal input to the second segment terminal to the anomalous segment detection circuit, and
when the anomalous driving of the segment electrode has been detected, output the first segment driving signal, or the second segment driving signal for driving the segment electrode separately from the first segment driving signal to the second segment terminal.

11. The liquid crystal driver according to claim 1 ,
wherein the first segment terminal and the second segment terminal are arranged adjacent to each other along a longitudinal direction of the liquid crystal driver.

12. The liquid crystal driver according to claim 1 ,
wherein the first segment terminal and the second segment terminal are arranged adjacent to each other along a direction that intersects a longitudinal direction of the liquid crystal driver.

13. The liquid crystal driver according to claim 1 , further comprising a nonvolatile memory for storing a detection history of the anomalous driving.

14. An electronic apparatus comprising:
the liquid crystal driver according to claim 1 .

15. A mobile body comprising:
the liquid crystal driver according to claim 1 .

16. A liquid crystal driver comprising:
a segment driving circuit configured to output a segment driving signal for driving a segment electrode of a liquid crystal panel;
a segment terminal from which the segment driving signal is to be output to the segment electrode;
an anomalous segment detection circuit configured to detect anomalous driving of the segment electrode; and
a control circuit configured to control a drive timing when the liquid crystal driver drives a liquid crystal panel,
wherein the segment driving circuit includes:
a segment signal output circuit configured to output a segment signal based on segment driving data; and
a driving circuit configured to output the segment driving signal based on the segment signal,
wherein the anomalous segment detection circuit is configured to detect the anomalous driving by comparing the segment signal and the segment driving signal,
wherein the anomalous segment detection circuit includes an exclusive OR circuit for obtaining an exclusive OR of a segment monitoring signal, which is a monitori

Assignees

• Seiko Epson Corp

Inventors

• Muraki Norichika
• Kobayashi Hironori

Classifications

• G09G3/36 Primary

  using liquid crystals · CPC title

• G09G3/3614

  Control of polarity reversal in general · CPC title

• G09G3/04 Primary

  for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments {using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions} · CPC title

• G09G3/006

  Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309) · CPC title

• G09G2330/12

  Test circuits or failure detection circuits included in a display system, as permanent part thereof · CPC title