Electrooptical display device

Claim 2

An electrooptical display device, comprising: a display panel including a common electrode group having common electrode lines with common electrodes and a segment electrode group having segment electrode lines with segment electrodes; a driving power source; a common electrode driving circuit coupled between the driving power source and the display panel for driving the common electrode lines; a segment electrode driving circuit coupled between the driving power source and the display panel for driving the segment electrode lines; and an adjusting circuit including current detection means for detecting actual current flowing through the display panel, said detected current varying with the driving voltage of the display panel, said adjusting circuit including voltage control means responsive to a change in the detected actual current for steeply increasing or decreasing the level of the driving voltage from a normal level thereof for a short period to add an impulse correction voltage to the driving voltages applied to at least one of said segment electrode and said common electrode driving circuits for correcting deformation of waveforms of the driving voltage.

Claim 3

The electrooptical display device of claim 1 wherein the adjusting circuit includes means for providing positive feedback to increase current flowing into a load of said display panel.

Claim 4

The electrooptical display device of claim 2, wherein the display panel comprises a plurality of liquid crystals; and wherein the positive feedback means includes means for generating charge current to fully charge total capacitance of the display panel.

Claim 5

The electrooptical display device of claim 1 wherein the current detection means is connected to at least one of said common electrode and said segment electrode driving circuits, and said voltage control means is connected to at least the one of said common electrode and said segment electrode driving circuits disconnected from the current detection means.

Claim 6

The electrooptical device of claim 1 wherein the current detection means is connected to at least one of said common electrode and said segment electrode driving circuits, and the voltage control means is connected to said at least one driving circuit through said current detection means.

Claim 7

The electrooptical device of claim 5 wherein the current detection means includes means for detecting current flowing through one of the common and segment electrode driving circuits; the voltage control means including means for controlling a voltage of one of the common and segment electrode being integrated with the current detection means to form one circuit; said one circuit including; an operational amplifier having a negative input terminal, a positive input terminal, and an output terminal; the output terminal being connected to one of the common and segment electrode driving circuits and fed back to the negative input terminal, the positive input terminal being set to a reference voltage level corresponding to the voltage setting of one of the common and segment electrode driving voltages, the output of this operational amplifier being positively fed back to the positive input terminal through a capacitance.

Claim 8

The electrooptical display device of claim 6, wherein a resistor is inserted in a positive feed-back circuit coupled between the positive input terminal and output of the operational amplifier.

Claim 9

An electrooptical display device according to claim 6, wherein the current detection means includes means for detecting current flowing through said common electrode driving circuit and said voltage control means includes means for controlling voltage of said common electrode group.

Claim 10

The electrooptical display device of claim 1, wherein both said current detection means and said voltage control means are connected to both said common electrode and said segment electrode driving circuits.

Claim 11

The electrooptical display device of claim 1, wherein said current detection means is connected to one of said common electrode and said segment electrode driving circuits, are said voltage control means is connected to both of said common electrode and said segment electrode driving circuits.

Claim 12

The electrooptical display device of claim 10 wherein the voltage control means comprises a first voltage control and a second voltage control means separate from one another; and the current detection means and the first voltage control means being connected to one of said common electrode and said segment electrode driving circuits, the second voltage control means being connected to the other of the common electrode and segment electrode driving circuits.

Claim 13

The electrooptical display device of claim 11, wherein said second voltage control means is controlled by said current detection means.

Claim 14

The electrooptical display device of claim 1 wherein the voltage control means includes means for controlling the voltage of all but a selected common electrode in the common electrode group; and wherein the current detection means includes means for detecting the current in all but a selected common electrode in the common electrode group.

Claim 15

The electrooptical display device of claim 1 wherein at least one of the current detection means and the voltage control means is disconnected from common electrodes selected by the common electrode driving circuit.

Claim 16

The electrooptical display device of claim 1 wherein the driving power source circuit comprises, means for applying a plurality of segment electrode driving voltages to said segment electrode driving circuit.

Claim 17

The electrooptical display device of claim 15 wherein the adjusting circuit comprises in the alternative a plurality of the voltage control means or a plurality of the current detection means connected to the respective plurality of segment electrode driving voltage sources.

Claim 18

The electrooptical display device of claim 15 wherein the adjusting circuit comprises a plurality of voltage control means connected to the segment electrode driving circuit of the display panel; each of said plurality being controlled by an output signal from the current detection means; and the current detection means being connected to the common electrode driving circuit.

Claim 19

The electrooptical device of claim 17 wherein the current detection means is connected for detecting current flowing through the common electrode driving circuit; the current detection means includes a first operational amplifier having an output, a negative input terminal, and a positive input terminal, a current detection resistor connected to the output of the first operational amplifier; the voltage control means includes a first and second voltage control means, each said first and second voltage control means being connected to a respective segment electrode driving source, each of the first and second voltage control means includes, a second operational amplifier having an output terminal, a negative input terminal and a positive input terminal, the output terminal being connected to one of the common electrode and segment electrode driving circuits, the positive input terminal being at a reference voltage level of a driving voltage applied to said one of the common and segment electrode driving circuits, the negative input terminal being at a voltage level determined in accordance with the voltage at the positive input terminal and a variable voltage corresponding to current flowing into the display panel, and a feedback resistor connecting the output terminal to the negative input terminal; the first voltage control means being connected to one of the plurality of segment electrode driving voltage source and the second voltage control means connected to another of the said signal electrode driving voltage source; and the negative input terminal each of the second operational amplifier of the voltage control means being connected to the output of the first operational amplifier of the current detection means; each one of the reference voltages of the plurality of segment electrode driving voltage source being input to the positive input terminals of the respective second operational amplifiers of the first and the second voltage control means.

Claim 20

The electrooptical display device of claim 15 wherein the current detection means comprises a plurality of current detection means connected to the segment electrode driving circuit of the display panel; and the voltage control means being connected to the common electrode driving circuit, and controlled by each one of the plurality of current detection means.

Claim 21

The electrooptical device of claim 19 wherein each of the plurality of current detection circuits comprises a first operational amplifier having an output, a negative input terminal, a positive input terminal, and a current detection resistor connected to the output of the operational amplifier, the plurality of current detection means includes a first current detection means connected to one of the segment electrode driving voltage sources and a second current detection means connected to the other one of the segment electrode driving voltage sources, the output of each first operational amplifier being connected to the voltage control means and fed back through the current detection resistor to the negative input terminal, the negative input terminal being connected to one of the common electrode and the segment electrode driving circuits, the positive input terminal being at a reference voltage level applied to said one of the common electrode and the segment electrode driving circuits connected to the negative input terminal; the voltage control means comprising, a second operational amplifier having an output terminal, a negative input terminal and a positive input terminal; the output terminal being connected to one of the common electrode and segment electrode driving circuits, the positive input terminal being set at a reference voltage level of a driving voltage applied to said one of the common and segment electrode driving circuits, the negative input terminal being at a voltage level determined in accordance with the voltage at the positive input terminal and a variable voltage corresponding to current flowing into the display panel and a feedback resistor connecting the output terminal to the negative input terminal; the output of the first current detection means and the second current detection means being connected to the negative input of the second operational amplifier and the positive input terminal of the second operational amplifier being connected to each one of the reference voltages of the plurality of segment electrode driving voltage sources.

Claim 22

The electrooptical display device of claim 19, wherein the plurality of the current detection means comprises a first current detection means connected to one of said plurality of segment electrode driving voltage sources for detecting current through said segment electrode driving circuit and a second current detection means connected to another one of said segment electrode driving voltage sources for detecting current flowing through said segment electrode driving circuit; the voltage control means being connected to both of said first and second current detection means and driving voltage sources and further connected to said common electrode driving circuit, the first and second current detection means and the voltage control means including the voltage control means including means controlling a voltage of one of the common and segment electrode being integrated with the current detection means to form one circuit; said one circuit including; an operational amplifier having a negative input terminal, a positive input terminal, and an output terminal; the output terminal being connected to one of the common and segment electrode driving circuits and fed back to the negative input terminal, the positive input terminal being set to a reference voltage level corresponding to the voltage setting of one of the common and segment electrode driving voltages, the output of this operational amplifier being positively fed back to the positive input terminal through a capacitance; and the output of the first and second current detection means being input to the negative input terminal of the voltage control means.

Claim 23

The electrooptical display device of claim 1 wherein the current detection means comprises an operational amplifier having an output, a negative input terminal, and a positive input terminal and a current detection resistor connected to the output of the operational amplifier; the output of the operational amplifier being connected to the voltage control means and fed back through the current detection resistor to the negative input terminal, the negative input terminal being connected to one of said common electrode driving circuit and said segment electrode driving circuit, the positive input terminal being at a reference voltage level applied to the one of said common electrode driving circuit and the segment electrode driving circuit that is connected to the negative input terminal.

Claim 24

The electrooptical device of claim 22 wherein the display panel comprises a substrate, and the current detection resistor is mounted on the substrate.

Claim 25

The electrooptical device of claim 23 wherein the display panel has an inner resistance; and the current detection resistance includes the inner resistance of the display panel.

Claim 26

An electrooptical display device according to claim 1 wherein the voltage control means comprises: an operational amplifier having an output terminal, a negative input terminal and a positive input terminal; the output terminal being connected to one of the common electrode driving circuit and segment electrode driving circuit, the positive input terminal being set to a reference voltage level of a driving voltage applied to said common electrode driving circuit; the negative input terminal being connected to the current detection means; and a feedback resistor connecting the output terminal to the negative input terminal.

Claim 27

The electrooptical display device of claim 25, wherein each of said first and second current detection means comprises a plurality of primary coils connected between a reference voltage source of one of said segment and common electrode driving voltages and one of said segment and common electrode driving circuits, and a plurality of secondary coils connected to the voltage control means.

Claim 28

An electrooptical display device according to claim 1, wherein the current detection means is comprised of resistance.

Claim 29

An electrooptical display device according to claim 27, wherein the resistance includes resistors mounted on a substrate of the display panel.

Claim 30

The electrooptical display device of claim 28, wherein the resistance includes an inner resistance of the display panel.

Claim 31

An electrooptical display device according to claim 1, wherein the current detection means includes means for detecting a total current flowing through the entire display panel, the voltage control means including means for adjusting voltage variation of both said common segment electrode driving voltages of the display panel.

Claim 32

An electro-optical display device according to claim 1, wherein said adjusting circuit includes means for adjusting said deformation of said wave-form by rapidly varying the driving voltage applied to at least one group of electrodes selected from the common electrodes group and the segment electrodes group of said display panel.

Claim 33

An electro-optical display device according to claim 31, wherein a voltage level of said driving voltage applied to at least one group of electrodes selected from the common electrodes group and the segment electrodes group of said display panel is steeply increased at the beginning of a period when said driving voltage is initially supplied thereto so as to form a rising edge.

Claim 34

An electro-optical display device according to claim 31, wherein a voltage level of said driving voltage applied to at least one group of electrodes selected from the common electrodes group and the segment electrodes group of said display panel exceeds the normal level of the voltage, a period when said driving voltage is initially supplied thereto, so as to form a rising edge.

Claim 35

An electro-optical display device according to claim 1, wherein said current detection means is connected to said segment electrode driving circuit; and said voltage control means comprises: an operational amplifier having an output terminal, a negative input terminal, and a positive input terminal, the output terminal being connected to said common electrode driving circuit, and fed back to the negative input terminal through a resistor, the negative input terminal further being connected to a reference voltage of a driving voltage applied to said common electrode driving circuit, the positive input terminal being connected to said current detection means and set at a voltage level determined in accordance with the reference voltage and a variable voltage corresponding to current flowing into the display panel.