Electro-optical element driving circuit, electro-optical device, and electronic device

• US 6,392,354 B1
• Filed: 12/09/1999
• Issued: 05/21/2002
• Est. Priority Date: 05/20/1998
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsueda, Yojiro
• Primary Examiner(s): VU, DAVID HUNG
• Application Number:
  US09/445,014
• Time in Patent Office: 894 Days
• Field of Search: 315/169.2, 315/169.1, 315/169.3, 345/87, 345/89, 345/95, 345/96
• US Class Current: 315/169.1
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• 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 2310/0289 Details of voltage level shifters arranged for use in a driving circuit
• CPC Class Codes: G09G 2330/12 Test circuits or failure detection circuits included in a display system, as permanent part thereof
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: H03M 1/804 with charge redistribution

Abstract

In a driving circuit of an electro-optical device, after a shift register as a digitalprocessing element perform predetermined digital processing to a digital driving signal and generates a processing digital driving signal, a level shifter as a voltage increasing element increases voltage of the processing digital driving signal and generates a voltage-increased digital driving signal. Then, a D/A converter as a digital/analog converting element digital/analog converts the voltage-increased digital driving signal, generates an analog driving signal, and applies the analog driving signal to each electro-optical element. Furthermore, among capacitance elements used for the D/A converter, elements with a large capacitance are formed in a low density wire region in the vicinity of a pixel portion, and elements with small capacitance are formed in a high density wire region which is separated from the pixel portion.

Claims

1. An electro-optical device comprising:

a plurality of data inputting lines corresponding to a bit number;

a plurality of signal lines for supplying signals to a plurality of electro-optical elements;

a plurality of digital processing elements for performing digital processing of digital driving signals supplied from the plurality of data inputting lines, the plurality of digital processing elements corresponding to each of the plurality of signal lines;

a plurality of voltage transforming elements each of which transforms a digital voltage supplied from each of the digital processing elements; and

a plurality of digital/analog converting elements each of which converts an output of each of the plurality of voltage transforming elements into an analog driving signal,

wherein the plurality of digital/analog converting elements comprise a plurality of analog switches and a plurality of capacitance elements,

wherein capacitances of the capacitor elements are mutually different, and

wherein, if n and u are respectively, a natural number and an arbitrary unit of capacitance, a capacitance of a capacitor element corresponding to n^th bit among the plurality of capacitor elements is expressed by 2<sup>n−

1</sup>u.

2. The electro-optical device according to claim 1,

wherein capacitance of the capacitor element corresponding to n^th bit comprises 2^n-1 cells of which the capacitance is u.

3. An electro-optical device comprising:

a plurality of data inputting lines corresponding to a bit number;

a plurality of signal lines for supplying signals to a plurality of electro-optical elements;

a plurality of digital processing elements for performing digital processing of digital driving signals supplied from the plurality of data inputting lines, the plurality of digital processing elements corresponding to each of the plurality of signal lines;

a plurality of voltage transforming elements each of which transforms a digital voltage supplied from each of the digital processing elements; and

a plurality of digital/analog converting elements each of which converts an output of each of the plurality of voltage transforming elements into an analog driving signal,

wherein the plurality of digital/analog converting elements comprise a plurality of analog switches and a plurality of capacitance elements, and

wherein if n and u are respectively, a natural number and an arbitrary unit of capacitance, a capacitance of a capacitor element corresponding to n^th bit among the plurality of capacitor elements is smaller than a nominally determined capacitance of 2<sup>n−

1</sup> u of the capacitor element.

4. An electro-optical device comprising:

a plurality of data inputting lines corresponding to a bit number;

a plurality of signal lines for supplying signals to a plurality of electro-optical elements;

a plurality of digital processing elements for performing digital processing of digital driving signals supplied from the plurality of data inputting lines, the plurality of digital processing elements corresponding to each of the plurality of signal lines;

a plurality of voltage transforming elements each of which transforms a digital voltage supplied from each of the digital processing elements; and

a plurality of digital/analog converting elements each of which converts an output of each of the plurality of voltage transforming elements into an analog driving signal,

wherein the plurality of digital/analog converting elements comprise a plurality of analog switches and a plurality of capacitance elements, and

wherein a capacitor element with the largest capacitance among the capacitor elements is disposed the closest position to one of the plurality of signal lines that corresponds to the capacitor elements.

5. An electro-optical device comprising:

a plurality of data inputting lines corresponding to a bit number;

a plurality of signal lines for supplying signals to a plurality of electro-optical elements;

a plurality of digital processing elements for performing digital processing of digital driving signals supplied from the plurality of data inputting lines, the plurality of digital processing elements corresponding to each of the plurality of signal lines;

a plurality of voltage transforming elements each of which transforms a digital voltage supplied from each of the digital processing elements; and

a plurality of digital/analog converting elements each of which converts an output of each of the plurality of voltage transforming elements into an analog driving signal,

wherein the plurality of digital/analog converting elements comprise a plurality of analog switches and a plurality of capacitance elements, and

wherein a capacitor element with the largest capacitance among the capacitor elements is disposed the closest position to one of the plurality of signal lines that corresponds to the capacitor elements.

6. The electro-optical device according to claim 5,

wherein a distance between a position where on of the capacitor elements is disposed and the signal line increases, as a capacitance of the capacitor element decreases.

7. the electro-optical device according to claim 5,

wherein between two adjacent capacitor elements of the plurality of capacitor elements, capacitance of one capacitor element closer to the signal line is larger than that of the other.