# US 7,746,294 B2 · Transflective liquid crystal display

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- Number: US 7,746,294 B2
- Document ID: US7746294B2
- Status: Granted
- Kind: B2
- Application number: 11/404,539
- Filed: 2006-04-14
- Published: 2007-10-18
- Granted: 2010-06-29
- Earliest claimed: 2006-04-14
- Assignees: University of Central Florida Research Foundation, Inc.; Toppoly Optoelectronics Corp.
- Inventors: Ju-Hyun Lee; Xinyu Zhu; Shin-Tson Wu
- Web page: https://patentgrep.com/patent/US7746294B2

## CPC

- G02F 1/133514: {Colour filters}
- G02F 1/133555: {Transflectors}
- G09G 3/3607: {for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels (display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127)}
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- G09G 3/3659: {the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes}
- G02F 1/133622: {Colour sequential illumination}
- G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)}
- G09G 2300/0426: Layout of electrodes and connections
- G09G 2300/0456: with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
- G09G 2300/0809: Several active elements per pixel in active matrix panels
- G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor
- G09G 2310/02: Addressing, scanning or driving the display screen or processing steps related thereto
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- 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

The apparatus, methods, system and devices of the present invention provides transflective LCD system structure wherein each pixel is composed of at least three reflective sub-pixels and at least one transmissive sub-pixel. The reflective sub-pixels have a color filter layer for displaying color reflective images and the transmissive sub-pixel it is driven by color sequential imaging method for displaying a color transmissive image. The configuration of the sub-pixels and the location of the sub-pixel electronics increases the aperture ratio of both transmissive sub-pixel and reflective sub-pixel to improve the image brightness and lower the overall power consumption of the device.

## Claims

### Claim 1

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels, the at least one electronic circuit comprises:
plural first and second scan electrodes;
plural first and second data electrodes, wherein one of the plural first scan electrodes and one of the plural first data electrode connect each one of the at least three reflective sub-pixels to the at least one electronic circuit and one of the plural second scan electrodes and one of the plural second data electrodes connect each one of the transmissive sub-pixel to the at least one electronic circuit; and
at least four pixel electronic circuits connected with the plural first and second scan electrodes and the plural first and second data electrodes for driving the at least three reflective sub-pixel and the transmissive sub-pixel, respectively, for each of the plural pixels, at least three of the pixel electronic circuits are each located in a region of a corresponding one of the at least three reflective sub-pixel and the transmissive sub-pixel, at least three of the at least four pixel electronic circuits are each located below the reflective layer of a corresponding one of the at least three reflective sub-pixels to increase an aperture ratio of the at least three reflective sub-pixel to provide brighter reflective image for the reflective modes;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images.

### Claim 2 (depends on 1)

The transflective liquid crystal display of claim 1, wherein each one of the plural pixels further comprises:
at least three different color filter layers located on one of the top and the bottom substrate of the at least three reflective sub-pixels, respectively, wherein the at least three color filter layers display a reflective color image using incoming light from ambient; and
at least three different color light sources below the transmissive sub-pixel to sequentially transmit a color transmissive image for each of the at least three different colors during one time frame.

### Claim 3

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels, the at least one electronic circuit comprises:
plural first and second scan electrodes;
plural first and second data electrodes, wherein one of the plural first scan electrodes and one of the plural first data electrode connect each one of the at least three reflective sub-pixels to the at least one electronic circuit and one of the plural second scan electrodes and one of the plural second data electrodes connect each one of the transmissive sub-pixel to the at least one electronic circuit; and
at least four pixel electronic circuits connected with the plural first and second scan electrodes and the plural first and second data electrodes for driving the at least three reflective sub-pixel and the transmissive sub-pixel, respectively, for each of the plural pixels, wherein the at least four pixel electronic circuits are each located in a region of a corresponding one of the at least three reflective sub-pixel and the transmissive sub-pixel and one of the at least four pixel electronic circuits drives the transmissive sub-pixel and is located below the reflective layer of the at least three reflective sub-pixels to increase an aperture ratio of the transmissive sub-pixel to provide a brighter transmissive image for the transmissive mode;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images.

### Claim 4

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels, the at least one electronic circuit comprises:
plural first and second scan electrodes;
plural first and second data electrodes, wherein one of the plural first scan electrodes and one of the plural first data electrode connect each one of the at least three reflective sub-pixels to the at least one electronic circuit and one of the plural second scan electrodes and one of the plural second data electrodes connect each one of the transmissive sub-pixel to the at least one electronic circuit;
a reflective pixel electronic circuit connected with the plural first scan and first data electrodes for driving each one of the at least three reflective sub-pixels; and
a dual-switch based transmissive pixel electronic circuit connected with the plural second scan and second data electrodes for driving the transmissive sub-pixel;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images.

### Claim 5 (depends on 4)

The transflective liquid crystal display of claim 4, wherein the dual-switch based transmissive pixel electronic circuit comprises:
a first and a second thin film transistor; and
a first and second charge holding device connected with a first and second thin film transistor to connect the plural second scan and second data electrodes to drive the transmissive sub-pixels of the plural pixels, wherein the first thin film transistor and first capacitor functions as a frame memory part and the second thin firm transistor and second capacitor functions as a liquid crystal driver.

### Claim 6

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels, wherein the at least one electronic circuit comprises:
plural first and second scan electrodes;
plural first and second data electrodes, wherein one of the plural first scan electrodes and one of the plural first data electrode connect each one of the at least three reflective sub-pixels to the at least one electronic circuit and one of the plural second scan electrodes and one of the plural second data electrodes connect each one of the transmissive sub-pixel to the at least one electronic circuit;
a dual-switch based reflective pixel electronic circuit connected with the plural first scan and first data electrodes for driving each one of the at least three reflective sub-pixels; and
a dual-switch based transmissive pixel electronic circuit connected with the plural second scan and second data electrodes for driving the transmissive sub-pixel;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images.

### Claim 7

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images, wherein the timing control unit includes:
a reflective timing signal for scanning the reflective sub-pixels row-by-row once during each one of plural frame periods; and
a transmissive timing signal for scanning the transmissive sub-pixels row-by-row for six sub-frames during each one of the plural frame periods, wherein a color sub-frame and a dark sub-frame are interleaved within the six sub-frames.

### Claim 8 (depends on 7)

The transflective liquid crystal display of claim 7, wherein the reflective timing signal and the transmissive timing signal further comprises:
a synchronization of the scanning of the reflective and transmissive sub-pixels during the first sub-frame in each frame period.

### Claim 9 (depends on 8)

The transflective liquid crystal display of claim 8, further comprising:
a transmissive color signal having six sub-frame periods per time period, wherein a first one of the at least three different color light is activated between a first time point when a first row of transmissive sub-pixels are scanned at a first sub-frame scanning and a second time point when the first row of the transmissive sub-pixels are scanned at a second sub-frame scanning; a second one of the at least three different color light source is activated between the second time point when the first row of the transmissive sub-pixels are scanned during the second sub-frame scanning and a third time point when the first row of the transmissive sub-pixels are scanned during a fifth sub-frame scanning; and a third one of the at least three different color light sources is activated between the third time point when the first row of the transmissive sub-pixels are scanned at a fifth sub-frame scanning and the first time point when the first row of the transmissive sub-pixels are scanned at next first sub-frame scanning of the next frame imaging.

### Claim 10

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images, wherein the timing control unit further comprises:
a reflective timing signal for scanning the reflective sub-pixels row-by-row once during each one of plural frame periods; and
a transmissive timing signal for scanning the transmissive sub-pixels row-by-row for six sub-frames during each one of the plural frame periods.

### Claim 11 (depends on 10)

The transflective liquid crystal display of claim 10, wherein the transmissive timing signal further comprises:
a synchronization of the reflective timing signal with the transmissive timing signal for synchronizing the scanning of the transmissive sub-pixels in a first one of the three sub-frames with the scanning of the first, second and third reflective sub-pixels during the frame time period.

### Claim 12 (depends on 11)

The display of claim 11, wherein the scanning period of each sub-frame of the transmissive sub-pixels is less than approximately ⅓ of one frame period.

### Claim 13 (depends on 10)

The transflective liquid crystal display of claim 10, further comprising:
a scanning period having a time interval from a beginning time point when the first row of transmissive sub-pixels are scanned through an end time point when the last row transmissive sub-pixels are scanned during one sub-frame period.

### Claim 14 (depends on 10)

The transflective liquid crystal display of claim 10, further comprising:
a first one of the at least three different color light sources is activated between a first time point when a last row of the transmissive sub-pixels are scanned for a first sub-frame scanning and a second time point when the first row of the transmissive sub-pixels are scanned for a second sub-frame scanning;
a second one of the at least three different color light sources is activated between the second time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning and a third time point when the first row of the transmissive sub-pixels are scanned for the third sub-frame scanning; and
a third one of the at least three different color light sources is activated between the third time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning and the first time point when the first row of the transmissive sub-pixels are scanned for the first sub-frame scanning of a next frame imaging.

### Claim 15

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images, wherein the timing control unit further comprises:
a reflective timing signal for scanning the reflective sub-pixels row-by-row once during each one of plural frame periods; and
a transmissive timing signal for scanning the transmissive sub-pixels row-by-row for six sub-frames during each one of the plural frame periods.

### Claim 16 (depends on 15)

The transflective liquid crystal display of claim 15, wherein the transmissive timing signal further comprises:
a synchronization of the reflective timing signal with the transmissive timing signal for synchronizing the scanning of the transmissive sub-pixels in a first one of the three sub-frames with the scanning of the first, second and third reflective sub-pixels during the frame time period.

### Claim 17 (depends on 16)

The transflective liquid crystal display of claim 16, further comprising:
a transmissive image data are transferred to an image buffer memory in the transmissive pixel electronics during the transmissive sub-frame scanning.

### Claim 18 (depends on 17)

The transflective liquid crystal display of claim 17, wherein the transmissive image data in the image buffer are transferred to the second charge holding devices to apply voltage to liquid crystal layer in the transmissive pixel electronics at time point after the last row of the transmissive sub-pixels are scanned for each of sub-frame scanning to draw the image.

### Claim 19 (depends on 16)

The transflective liquid crystal display of claim 16, wherein a first one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning; whererin a second one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning; and wherein a third one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning of the next frame imaging.

### Claim 20

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels;
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images, wherein the timing control unit further comprises:
a reflective timing signal for scanning the reflective sub-pixels row-by-row once during each one of plural frame periods; and
a transmissive timing signal for scanning the transmissive sub-pixels row-by-row for six sub-frames during each one of the plural frame periods.

### Claim 21 (depends on 20)

The transflective liquid crystal display of claim 20, wherein the transmissive timing signal further comprises:
a synchronization of the reflective timing signal with the transmissive timing signal for synchronizing the scanning of the transmissive sub-pixels in a first one of the three sub-frames with the scanning of the first, second and third reflective sub-pixels during the frame time period.

### Claim 22 (depends on 21)

The transflective liquid crystal display of claim 21, further comprising:
a transmissive image data are transferred to an image buffer memory in the transmissive pixel electronics during the transmissive sub-frame scanning.

### Claim 23 (depends on 22)

The transflective liquid crystal display of claim 22, wherein the transmissive image data in the image buffer memory are transferred to the second charge holding devices to apply voltage to liquid crystal layer in the transmissive pixel electronics at time point after the last row of the transmissive sub-pixels are scanned for each of sub-frame scanning to draw the transmissive image.

### Claim 24 (depends on 20)

The transflective liquid crystal display of claim 20, wherein the transmissive image data transferred during a fourth sub-frame scanning are a dark image data.

### Claim 25 (depends on 20)

The transflective liquid crystal display of claim 20, further comprising
a first one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning;
a second one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning; and
a third one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the fourth sub-frame scanning.

### Claim 26 (depends on 20)

The transflective liquid crystal display of claim 20, wherein a backlight is deactivated between the time point when the last row of the transmissive sub-pixels are scanned for the fourth sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning of the next frame imaging.

### Claim 27

A transflective liquid crystal display comprising:
a top and a bottom substrate having a liquid crystal layer sandwiched between the top and the bottom substrate;
plural pixels, each one of the plural pixels comprising:
at least three reflective sub-pixels for displaying a reflective image, wherein each one of the at least three reflective sub-pixels having a reflective layer on an inner surface of the bottom substrate to reflect an incident light back to a viewer; and
a transmissive sub-pixel for displaying a transmissive image;
at least one electronic circuit for driving the at least three reflective sub-pixels and the transmissive sub-pixel of each one of the plural pixels
a backlight below the transmissive sub-pixels; and
a timing control unit connected with the at least one electronic circuit for converting and distributing an incoming video data to the plural pixels and controlling the backlight to synchronize the reflective and transmissive display images, wherein the timing control unit further comprises:
a reflective timing signal for scanning the reflective sub-pixels row-by-row once during each one of plural frame periods; and
a transmissive timing signal for scanning the transmissive sub-pixels row-by-row for six sub-frames during each one of the plural frame periods.

### Claim 28 (depends on 27)

The transflective liquid crystal display of claim 27, wherein the transmissive timing signal further comprises:
a synchronization of the reflective timing signal with the transmissive timing signal for synchronizing the scanning of the transmissive sub-pixels in a first one of the three sub-frames with the scanning of the first, second and third reflective sub-pixels during the frame time period.

### Claim 29 (depends on 28)

The display of claim 28, wherein the reflective image data in the frame buffer are transferred to the second charge holding devices to apply voltage to liquid crystal layer in the reflective pixel electronics at time point after the last row of the reflective sub-pixels are scanned for each frame scanning to draw the reflective image.

### Claim 30 (depends on 28)

The display of claim 28, wherein the transmissive image data in the frame buffer are transferred to the second charge holding devices to apply voltage to liquid crystal layer in the transmissive pixel electronics at time point after the last row of the transmissive sub-pixels are scanned for each of sub-frame scanning to draw the image.

### Claim 31 (depends on 27)

The transflective liquid crystal display of claim 27, further comprising:
a transmissive image data are transferred to an image buffer memory in the transmissive pixel electronics during the transmissive sub-frame scanning and a reflective image data are transferred to an image buffer memory in the reflective pixel electronics during the reflective frame scanning.

### Claim 32 (depends on 27)

The transflective liquid crystal display of claim 27, further comprising:
a first one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning;
a second one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the second sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning; and
a third one of the at least three different color light is activated between the time point when the last row of the transmissive sub-pixels are scanned for the third sub-frame scanning and the time point when the last row of the transmissive sub-pixels are scanned for the first sub-frame scanning of the next frame imaging.