Electro-optical panel, method for driving the same, electrooptical device, and electronic equipment

• US 20020015031A1
• Filed: 07/24/2001
• Published: 02/07/2002
• Est. Priority Date: 07/24/2000
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Fujita, Shin, Ozawa, Tokuro
• Granted Patent: US 6,791,523 B2
• Time in Patent Office: Days
• US Class Current: 345/204
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: 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

Abstract

To maintain image quality when a field frequency is dynamically changed. In an image display area AA, control lines 4a are arranged respectively corresponding to scanning lines 3a, and TFTs 50 and 51, a pixel electrode 9a, and a storage capacitor 52 are arranged at each intersection of one of data lines 6a and scanning lines 3a. A control signal SC supplied through the control line 4a controls the TFT 51 for an on and off operation. A timing signal generator circuit 300 activates the control signal SC when a field frequency is not higher than 60 Hz, and deactivates the control signal SC when a field frequency is above 60 Hz. In this way, whether or not to connect the storage capacitor 52 to the pixel electrode 9a is determined.

Claims

1. An electro-optical panel comprising:

a first substrate having a plurality of scanning lines and a plurality of data lines formed thereon;

a second substrate opposed to the first substrate, an electro-optical material interposed between the first substrate and the second substrate, and wherein;

the first substrate includes;

a plurality of control lines respectively formed corresponding to the scanning lines,

a first switching element, which is arranged at each intersection of one of the scanning lines and one of the data lines, is controlled for an on and off operation in response to a scanning signal supplied through the scanning line, and is connected between the data line and a pixel electrode, and

a second switching element, which is arranged at each intersection of one of the scanning lines and one of the data lines, is controlled for an on and off operation in response to a control signal supplied through the control line, and is connected between the pixel electrode and a storage capacitor.

2. The electro-optical panel according to claim 1, further comprising:

a first converter which converts input image data into point-at-a-time image data;

a second converter which converts the point-at-a-time image data into line-at-a-time image data;

a data line signal supplier which supplies each data line with a data line signal that is generated in accordance with the line-at-a-time image data; and

a scanning line driver which generates a scanning signal for successively selecting the scanning lines and supplies the scanning lines with the scanning signal.

3. An electro-optical device comprising:

the electro-optical panel according to claim 1, and

a control signal generator which generates the control signal in accordance with a field frequency.

4. The electro-optical device according to claim 3, the control signal generator generates the control signal respectively corresponding to each control line, and supplies the control line with the respective control signal.

5. An electro-optical device comprising:

the electro-optical panel according to claim 1, and

a control signal generator generating the control signal depending on whether an image to be displayed is a moving picture or a still picture.

9. The electro-optical panel according to claim 1, wherein the first switching element and the second switching element are thin-film transistors.

18. Electronic equipment comprising the electro-optical device according to claim 4.

6. An electro-optical panel comprising:

a first substrate having a plurality of scanning lines and a plurality of data lines formed thereon;

a second substrate opposed to the first substrate;

an electro-optical material interposed between the first substrate the second substrate;

wherein the first substrate includes;

a plurality of control lines respectively formed corresponding to the scanning lines,

a first switching element, which is arranged at each intersection of one of the scanning lines and one of the data lines, is controlled for an on and off operation in response to a scanning signal supplied through the scanning line, and is connected between the data line and a pixel electrode,

a second switching element, which is arranged at each intersection of one of the scanning lines and one of the data lines, is controlled for an on and off operation in response to a control signal supplied through the control line, and is connected between the pixel electrode and a storage capacitor, and

a plurality of control circuits generating the control signal, to be supplied to each control line, in accordance with the scanning signal and a common control signal indicating whether an image to be displayed is a moving picture or a still picture.

7. The electro-optical panel according to claim 6, wherein:

during an active period of the scanning signal, the control circuit generates the control signal for turning off the second switching element when the common control signal indicates the moving picture generates the control signal for turning on the second switching element when the common control signal indicates the still picture; and

during a non-active period of the scanning signal, the control circuit generates the control signal for holding the state of the second switching element during the active period immediately prior to this non-active period of the scanning signal.

8. The electro-optical panel according to claim 7, comprising:

a scanning line driver generating the scanning signal for successively selecting the scanning lines and supplies the scanning lines with the scanning signal for only a period during which an enable signal supplied from outside remains active.

10. An electro-optical device which switches between a moving picture and a still picture on a field by field basis, the electro-optical device comprising:

the electro-optical device according to claim 8,

a common control signal generator generating the common control signal which is a binary signal which transitions in level on a field by field basis for indicating a moving picture with one signal level thereof and a still picture with the other signal level thereof, depending on whether an image to be displayed is the moving picture or the still picture, and

an enable signal generator generating the enable signal that alternates between an active period and a non-active period with a constant period, wherein the enable signal is active during a moving picture display period, while, during a still picture display period, the enable signal is active in a first field and becomes non-active in one field or a plurality of fields subsequent to the first field.

11. The electro-optical device according to claim 10, wherein the common control signal generator transitions the signal level of the common control signal within a vertical blanking period, and

wherein the enable signal generator switches between the active period and the non-active period in the enable signal within the vertical blanking period.

12. An electro-optical device which switches between a moving picture and a still picture on a scanning line by scanning line basis, the electro-optical device comprising:

the electro-optical device according to claim 8,

a common control signal generator generating the common control signal which is a binary signal which transitions in level for indicating a moving picture with one signal level thereof and a still picture with the other signal level thereof, depending on whether a moving picture display area is scanned during a moving picture display period or a still picture display area is scanned during a still picture display period, and

an enable signal generator generating the enable signal that alternates between an active period and a non-active period with a constant period wherein the enable signal is active during the moving picture display period in each field, while, during the still picture display period, the enable signal is active in a first field and becomes non-active in one field or a plurality of fields subsequent to the first field.

13. The electro-optical device according to claim 12, wherein the common control signal generator transitions the signal level of the common control signal within one of a vertical blanking period and a horizontal blanking period, and

wherein the enable signal generator switches between the active period and the non-active period in the enable signal during one of the vertical blanking period and the horizontal blanking period.

14. A driving method for displaying an image on an electro-optical panel including a plurality of scanning lines, a plurality of data lines, and a matrix of first capacitors and second capacitors, each of the first and second capacitors arranged at an intersection of one of the scanning lines and one of the data lines, the driving method comprising the steps of:

determining whether a field frequency of an image to be displayed is higher or lower than a predetermined frequency,

writing the voltage of the data line to the first capacitor by successively selecting the scanning lines with the first capacitor disconnected from the second capacitor when the field frequency is higher than the predetermined frequency, and

writing the voltage of the data line to the first capacitor and the second capacitor by successively selecting the scanning lines with the first capacitor connected to the second capacitor when the field frequency is lower than the predetermined frequency.

15. A driving method for displaying an image on an electro-optical panel including a plurality of scanning lines, a plurality of data lines, and a matrix of first capacitors and second capacitors, each of the first and second capacitors arranged at an intersection of one of the scanning lines and one of the data lines, the driving method comprising the steps of:

determining whether an image to be displayed is a moving picture or a still picture,

writing the voltage of the data line to the first capacitor by successively selecting the scanning lines with the first capacitor disconnected from the second capacitor when the image to be displayed is the moving picture, and

writing the voltage of the data line to the first capacitor and the second capacitor by successively selecting the scanning lines with the first capacitor connected to the second capacitor when the image to be displayed is the still picture.

16. A driving method for displaying an image on an electro-optical panel with a moving picture and a still picture alternating with each other on a field by field basis, the electro-optical panel including a plurality of scanning lines, a plurality of data lines, and a matrix of first capacitors and second capacitors, each of the first and second capacitors arranged at an intersection of one of the scanning lines and one of the data lines, the driving method comprising the steps of:

writing the voltage of the data line to the first capacitor by successively selecting the scanning lines with the first capacitor disconnected from the second capacitor in each field in which the moving picture is displayed,

writing the voltage of the data line to the first capacitor and the second capacitor by successively selecting the scanning lines with the first capacitor connected to the second capacitor in a first field of fields in which the still picture is displayed,

holding the voltage written on the first capacitor and the second capacitor with the scanning lines not selected in one field or a plurality of fields subsequent to the first field, and

repeating the writing steps and the holding step with a constant period.

17. A driving method for displaying an image on an electro-optical panel with a moving picture and a still picture alternating with each other on a per scanning line basis, the electro-optical panel including a plurality of scanning lines, a plurality of data lines, and a matrix of first capacitors and second capacitors, each of the first and second capacitors arranged at an intersection of one of the scanning lines and one of the data lines, the driving method comprising the steps of:

writing the voltage of the data line to the first capacitor by successively selecting the scanning lines with the first capacitor disconnected from the second capacitor in each scanning line in which a moving picture is displayed,

writing the voltage of the data line to the first capacitor and the second capacitor by successively selecting the scanning lines with the first capacitor connected to the second capacitor in a first field in each scanning line in which a still picture is displayed,

holding the voltage written to the first capacitor and the second capacitor with the scanning lines not selected in one field or a plurality of fields subsequent to the first field, and

repeating the writing steps and the holding step with a constant period.