JPH0792446A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device capable of displaying a high definition image by resolving a problem of occurring display unevenness (cross talk) on a screen by a simple and inexpensive means. CONSTITUTION:Since a distortion voltage component is extracted by taking a difference with a detection voltage from a detection electrode 13 based on a reference voltage Vref outputted from a reference voltage generation circuit 15 formed by a complementary MOS-FET, by the distortion voltage component extracted by taking the difference between them, no error due to waveform bluntness when the polarity of a scanning voltage is inverted and both plarities of the rise/the fall of a waveform occurs, and further, no distortion voltage component is affected by the disturbance of the change, etc., in an ambient temp. also, and only the distortion voltage component is extracted always and correctly, and excellent feedback control is performed, and the display defect of the cross talk, etc., is dissolved always and correctly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as information processing devices such as word processors and personal computers, and display devices such as small televisions and projection type televisions by taking advantage of features such as thinness and low power consumption. . As a liquid crystal display element in such applications,
It can be roughly divided into two types, the simple matrix type and the active matrix type.

A simple matrix type liquid crystal display device is
Since it has a simple structure including the structure of the liquid crystal display panel and can easily manufacture large-sized ones at a low manufacturing cost, it is used in a wide range of applications.

Further, the active matrix type liquid crystal display device, for example, utilizes a characteristic that a high-definition and high-contrast clear image can be displayed, and for example, a VGA (Video Grap).
It is also used as a high-definition liquid crystal display device such as a display device called hicArray) compatible display device or a CG (Computer Graphics) compatible display device.

A liquid crystal display device used for such a display device is required to have multi-digit display and high-quality display. In order to meet such demands, in recent years, the number of pixels (the number of scanning electrodes × the number of signal electrodes) of a simple matrix type liquid crystal display element represented by an STN (Super Twisted Nematic) type liquid crystal display element has significantly increased. Further, along with this, the driving frequency of the liquid crystal display element (frequency of driving voltage pulse) is also increasing.

For example, there are 200 scanning electrodes and 640 signal electrodes.
The two-valued liquid crystal display element has a time equivalent to the scanning time for one scanning electrode, that is, the minimum pulse width of the driving voltage is 60
It is as short as ~ 70μs.

In general, the liquid crystal cell for each pixel of the liquid crystal display element can be represented as a capacitor (electric capacity) in an equivalent circuit. Further, the driver IC for driving the liquid crystal display element has an output impedance, which can be generally expressed as an electric resistance by an equivalent circuit. The simple matrix type liquid crystal display device is driven by a combination of square wave pulses.
Distortion or dullness occurs in the drive voltage waveform due to the output resistance of C, the connection resistance between the driver IC and the liquid crystal display element, the drive electrode resistance of the liquid crystal display element, and the capacitance of the liquid crystal layer. The distortion and dullness of these drive voltage waveforms are
The voltage applied to the liquid crystal layer lowers or rises, which results in a positional variation in the light transmittance within the screen of the liquid crystal display element, which is a phenomenon of display unevenness called so-called crosstalk on the screen. Appear in. It can be said that the fluctuation of the liquid crystal applied voltage caused by the distortion voltage generated in the scanning electrodes is most involved in the occurrence of crosstalk in the simple matrix liquid crystal display element. Therefore, this phenomenon will be described with an example.

FIG. 7A shows an equivalent circuit in which one scanning electrode of a conventional XY simple matrix type liquid crystal display device is partially extracted. Here, C _LC is the scan electrode Y
_{n is} the capacitance 901 of the liquid crystal layer for one electrode, and R is the output resistance of the scan electrode driver, the connection resistance of the driver IC and the liquid crystal display element, and the internal resistance of the electrode itself of the scan electrode Y _n of the liquid crystal display element. Is the total electrical resistance 902.

The liquid crystal display device is usually driven by an alternating liquid crystal applied voltage. Here, it is assumed that the scan electrode driver (not shown) outputs a voltage whose polarity is inverted between ± Vrev with the reference potential Vcom as the center. An example of the waveform of the scanning voltage V2 is shown in FIG. 7 (c). A signal electrode driver (not shown) outputs a signal voltage V1 having a waveform in which the polarity is inverted between ± Vrev as shown in FIG. 7 (b).

In this equivalent circuit, a square-wave-shaped signal voltage V1 is applied from the signal electrode driver side to the electrostatic capacitance 901 of the liquid crystal layer.
In consideration of the case where the voltage is applied to, a spike-like strain voltage V3 based on the time constant C _LC · R is generated at the connection point 903 between the liquid crystal layer (C _LC ) 901 and the total electric resistance (R) 902. This distortion voltage V3 is shown in FIG. Since the spike-shaped distortion voltage V3 is generated, the liquid crystal layer C _LC 90
The liquid crystal applied voltage applied to No. 1 has a waveform in which the voltage corresponding to the spiked distortion voltage V3 has been removed as shown in FIG. 7 (e). Such a voltage change appears as uneven display on the screen, so-called crosstalk.

Further, a transparent electrode made of tin oxide or ITO (indium oxide) is generally used as a scanning electrode or a signal electrode used inside a liquid crystal display element. Such a transparent electrode has an electric resistance. Because it is relatively large,
The above-mentioned waveform rounding and distortion voltage are more remarkably generated in these electrodes.

In order to solve the above problem of display unevenness, for example, as a technique for STN type liquid crystal display element, as disclosed in JP-A-2-71718 and SID'90 Digest p.413, A method of forming a compensation voltage to be applied to the scan electrode driver based on the display data output from the signal electrode driver and appropriately changing the compensation voltage to cancel the distortion voltage at the output terminal of the scan electrode driver has been studied. ing.

However, as described above, the conventional technique does not fundamentally eliminate the influence of the connection resistance between the driver IC and the liquid crystal display element, the resistance of the driving electrode of the liquid crystal display element, and the like. Correspondingly, the distortion voltage is canceled out based on a minute compensation voltage that is set in advance. For example, in the case of a device that changes the contrast by changing the liquid crystal drive voltage or a device that expresses gradation, Since the magnitude of the distortion voltage also changes as the driving voltage changes, the initially set compensation voltage deviates from the optimum compensation value, and effective compensation is difficult. Alternatively, it may be considered to add an adjustment circuit that resets the optimum compensation voltage each time, but when incorporating a circuit that has such an adjustment circuit and performs delicate setting of the compensation voltage based on the display data. However, there is a problem that the structure of the liquid crystal drive circuit system becomes very complicated.

Regarding the problem of the internal resistance of the transparent electrode described above, from the viewpoint of making the voltage waveform uniform on the transparent electrode, the transparent electrode is formed by arranging metal wiring in parallel beside the transparent electrode. It is conceivable to reduce the apparent resistance of (1) to suppress the occurrence of distortion of the waveform of the distortion voltage and the voltage applied to the liquid crystal.

However, in such a method, there are problems that the internal structure of the liquid crystal display element including the vicinity of the transparent electrode is complicated, the manufacturing is not easy, and the manufacturing cost is high.

Further, it is possible to use a driver IC with a very small output resistance in order to suppress the distortion of the voltage waveform and the bluntness of the voltage applied to the liquid crystal, but it is not easy to develop such a special driver IC. However, there is also a problem that its use is not practical because the price is expensive.

[0017]

As described above, in the conventional liquid crystal display device, the output resistance of the driver IC, the connection resistance between the driver IC and the liquid crystal display element, the driving electrode resistance of the liquid crystal display element, and the liquid crystal layer. There is a problem that the waveform of the voltage applied to the liquid crystal changes from the ideal waveform on the theory of operation due to the distortion voltage generated due to the capacitance of the liquid crystal display, and uneven display (crosstalk) occurs on the screen. .

In the known technique devised against this, there is a problem that the preset compensation voltage deviates from the required optimum compensation voltage due to a disturbance such as temperature change or noise, and the apparatus is complicated or expensive. There was a problem such as becoming.

The present invention has been made to solve such a problem, and an object thereof is to solve the problem that display unevenness (crosstalk) occurs on the screen of a liquid crystal display device by a simple and inexpensive means. Another object of the present invention is to provide a liquid crystal display device capable of displaying high-quality images.

[0020]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention intersects with a scanning electrode substrate having a plurality of scanning electrodes formed thereon while maintaining a gap between the plurality of scanning electrodes. And a liquid crystal display element having a signal electrode substrate formed with a plurality of signal electrodes facing each other, and a liquid crystal layer sandwiched and sandwiched between the scanning electrodes and the signal electrodes, and a scanning voltage is generated. In a liquid crystal display device having a scan driver circuit for applying the voltage to the scan electrodes and a signal driver circuit for generating a signal voltage and applying the signal voltage to the signal electrodes, an electric capacitance having one end connected to each of the plurality of scan electrodes or An electric resistance, a detection electrode which is connected to the other end of the electric capacity or the electric resistance, and detects a voltage collectively from the scan electrode in a portion where the other end is connected, and a complementary MOS. A reference voltage generating circuit which is formed of a field effect transistor and outputs a reference voltage; and a detection voltage, which is connected to the detection electrode and which calculates and amplifies a difference between the voltage detected from the scanning electrode via the detection electrode and the reference voltage. And an operational amplifier circuit for extracting the distorted voltage component and feeding back the distorted voltage component to the scan electrodes to suppress the generation of the distorted voltage of the plurality of scan electrodes.

Incidentally, the return destination of the distorted voltage component extracted from the voltage detected by the detection electrode by the operational amplifier circuit and fed back to the scanning electrode may be finally the scanning electrode. The output of the operational amplifier circuit may be directly connected and fed back, or the output of the operational amplifier circuit may be once connected to the scan driver circuit and the distortion voltage component may be superimposed on the scan voltage inside the scan voltage wiring circuit. After
It may be applied to the scanning electrodes and returned. In any case, when the distortion voltage component extracted by the operational amplifier circuit is fed back to the scan electrode, the distortion voltage of the scan electrode is effectively suppressed so that the distortion voltage of the scan electrode can be effectively suppressed. It goes without saying that it is desirable to set the rate and the polarity of its output to appropriate values.

Further, the above-mentioned capacitance may be formed by using the scanning electrode and the signal electrode as two electrodes facing each other and by using a liquid crystal layer as a dielectric material sandwiched between the two electrodes.

Further, in the reference voltage generating circuit formed of the complementary MOS field effect transistor (MOS-FET) described above, the reference voltage output from the complementary MOS field effect transistor may be symmetrically equal in polarity with respect to the center voltage. The more there is, the more preferable.

In addition, the above complementary MOS-F
The scan driver circuit including the reference voltage generating switch of the ET structure may be formed as a thin film transistor element on the scan electrode substrate to be a so-called integrated drive circuit type, or may be formed as an IC externally attached to the liquid crystal display element. Alternatively, it may be connected to the scanning electrode of the liquid crystal display element via a connection terminal or the like.

[0025]

In the liquid crystal display device according to the present invention, a voltage is detected from a plurality of scanning electrodes by a detection electrode through an electric capacity or an electric resistance, and a spike-like strain voltage generated in the detected voltage of the scanning electrode is detected. For example, a voltage change component that has an unfavorable effect on image display, that is, a distortion voltage component, can be extracted by the operational amplifier circuit and fed back to the scan electrode to suppress the distortion voltage or the like that is likely to occur in the scan electrode. At this time, needless to say, the operational amplifier circuit sets the output polarity (displacement direction of the output voltage) and the amplification factor so as to cancel the distortion voltage generated in the scan electrodes. In this way, it is possible to suppress the inconvenient voltage change that may occur in the scan electrodes.

Further, since the distorted voltage component extracted by the operational amplifier circuit is extracted by subtracting the reference voltage from the voltage detected from the scan electrode and amplifying the reference voltage, the reference voltage as the reference is inverted in polarity. When the waveform has a different amplitude or different dullness in both polarities with the center voltage as the center, the distortion voltage component extraction becomes inaccurate, and effective feedback control of the scan electrode voltage cannot be performed. There is inconvenience.

Therefore, in the present invention, when the above-mentioned reference voltage is generated, the symmetry of the switching characteristics of the rising and falling waveforms of both polarities with respect to the center voltage is extremely good, and the output waveform is not blunted. By using a reference voltage generation switch that uses a complementary MOS-FET with extremely low current consumption, even if the reference voltage inverts, the distortion voltage component can always be extracted accurately regardless of whether the waveform is rising or falling. Can be done.

As a result, even if the magnitude of the voltage applied from the drive voltage power supply circuit to the liquid crystal cell (liquid crystal layer) is changed to any value, or the voltage changes depending on the temperature change or the time change of the liquid crystal layer. Even when changing the polarity of the reference voltage, there is no error in the reference voltage due to such disturbance, and the distortion voltage component can always be accurately extracted.
It is possible to effectively eliminate display unevenness (crosstalk) on the screen.

Further, according to the present invention, one feedback loop is provided in the scan electrode and the drive voltage generating circuit thereof, that is, a feedback loop whose main part is composed of an electric resistance or capacitance, a detection electrode, an operational amplifier circuit and the like. Since it is only necessary to form a loop, it is possible to realize a liquid crystal display device capable of displaying high-quality images very easily and inexpensively.

[0030]

Embodiments of the liquid crystal display device of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram schematically showing the structure of a liquid crystal display device according to a first embodiment of the present invention. This liquid crystal display device includes a liquid crystal display element (liquid crystal display panel) 4 in which scanning electrodes 1 and signal electrodes 2 made of a transparent electrode such as ITO are arranged in a matrix so as to face each other, and a liquid crystal layer 3 is sandwiched between the scanning electrodes 1. , And has a scan driver circuit 5 and a signal driver circuit 6 for driving it. The scan driver circuit 5 and the signal driver circuit 6 are each formed of, for example, a thin film transistor (TFT).

The scan driver circuit 5 includes a scan electrode driver 7
And a scanning voltage power supply circuit 8 for supplying a power supply voltage thereto and an operational amplifier circuit 9 for receiving the feedback voltage and controlling the scanning voltage. The signal driver circuit 6 also includes a signal electrode driving unit 10 and a signal voltage power supply circuit 11 that supplies a power supply voltage to the signal electrode driving unit 10.

Further, in the liquid crystal display element 4, an electric capacitance 12 is arranged at each end of each scanning electrode 1. These electric capacitances 12 are electrically connected at one end to the scanning electrode 1 as described above, and at the other end to the detection electrode 13 collectively, and detect the voltage of the scanning electrode 1 detected by the electric capacitance 12. They are collected together and connected to the operational amplifier circuit 9 of the scan driver circuit 5 via the wiring 14. The operational amplifier circuit 9 has a complementary MOS-FET.
(Complementary Metal Oxide Semiconductor −Field
Effect Transistor: A reference voltage Vref is input from a reference voltage generation circuit 15 formed by a complementary MOS field effect transistor. In the liquid crystal display device of the present invention, since the electrical main part is configured in this manner, the distortion voltage component generated in the scan electrode 1 is reduced to the reference voltage Vre.
The reference voltage waveform output from the f generator circuit 15 has a very good rising / falling symmetry in polarity reversal and a reference voltage Vref with very little waveform bluntness. Since the extracted voltage is fed back to the scan electrode 1 as a voltage for canceling the strain voltage of the electrode 1, the generation of the strain voltage is accurately eliminated no matter how the voltage of the scan electrode 1 is changed by disturbance. can do. As a result, the crosstalk of the display image can be effectively eliminated.

The outline of the electrical structure of the liquid crystal display device according to the present invention has been described above. Next, the specific structure and operation of the embodiment of the liquid crystal display device according to the present invention will be described in detail.

As the liquid crystal display element 4, an STN type liquid crystal display element was used. The screen size is A4, and the display capacity (number of pixels) is 640 x 200 dots. The cell gap of this STN type liquid crystal display element 4 is about 7 μm, and it is provided with alignment films 201 (a) and (b) made of a resin subjected to a rubbing alignment treatment, and a liquid crystal layer is provided between the cell gaps of the liquid crystal display element 4. The liquid crystal molecules of No. 3 are oriented so that they are twisted by 240 °. As the liquid crystal composition of the liquid crystal layer 3, ZLI-2293 manufactured by Merck Ltd. was used. The transparent electrodes of the scan electrode 1 and the signal electrode 2 are I
It is formed from TO. The liquid crystal display device of the present embodiment is provided with the optical phase compensation cell 202 in order to display black and white.
The glass substrate 203 on the outward side of the liquid crystal display device
It was pasted on (a) and (b) so that black display was obtained when no voltage was applied and white display was obtained when voltage was applied. The structure of such a liquid crystal display element 4 is shown in FIG. Glass substrate 203
(B) The electric capacitance 12 is arranged at the end portion of each scanning electrode 1 provided above, as described above. This capacitance 1
2 is a detection electrode 13 and a scanning electrode which are substantially the same as the signal electrode 2 provided on the glass substrate 203 (a) so as to face the end of the scanning electrode 1 with the liquid crystal layer 3 interposed therebetween. It is formed by using the liquid crystal layer 3 sandwiched between 1 and 1 as a dielectric.

As is clear from FIG. 2, the capacitance 12 is formed by using the open end of the scanning electrode 1 and the detection electrode 13 as electrodes, and the liquid crystal layer 3 sandwiched between the electrodes as a dielectric. Therefore, the liquid crystal display element 4 of the present embodiment is the detection electrode 1
The structure of the conventional liquid crystal display element need not be changed by only adding 3, and it can be manufactured extremely easily.

FIG. 3 is a block diagram showing the overall structure of the liquid crystal display device of this embodiment. A scan driver circuit 5 and a signal driver circuit 6 are connected to the scan electrodes 1 and the signal electrodes 2 in the liquid crystal display element 4, respectively. The scan driver circuit 5 generates a reference voltage Vref from a scan electrode driving unit 7, a scan voltage power supply circuit 8 for supplying a power supply voltage thereto, and a voltage detected by the detection electrode 13 from the scan electrode 1 through the electric capacitance 12. It has an operational amplifier circuit 9 for extracting a distortion voltage component as a reference and feeding it back to the scan electrode 1. Further, the signal driver circuit 6 has a signal electrode drive unit 10 and a signal voltage power supply circuit 11 for applying a power supply voltage to the signal electrode drive unit 10. Further, inside the scanning voltage power supply circuit 8, a reference voltage generation circuit 15 formed by a complementary MOS-FET is formed.

In FIG. 3, the scanning voltage power supply circuit 8 and the signal voltage power supply circuit 11 are shown separately for easier understanding of the illustration and description, but in reality (actual circuit structure Is composed as one. This is because the structure can be simple, accurate, and inexpensive by combining them into one. In this embodiment, the drive voltage power supply circuit 4 shown in FIG.
Configured as 01.

The scan electrode driver 7 receives the control signal from the scan data generating circuit 402 and outputs the respective output potentials of Y1 to Y200 of the scan electrode 1 to V0Y, V1, V4,
Select one from V5Y. Specifically, as shown in FIG. 3, a shift register 40 that sequentially transfers scan data is used.
3 and a switch section 404 for selecting the scanning potential when scanning is selected, that is, the scanning pulse (V0Y, V5Y) or the scanning potential (V1, V4) when not scanning is selected by this data. Receives FP (frame pulse) which determines one frame time as basic scanning data, and transfers data from outputs Y1 to Y200 based on LP (latch pulse) which determines one scanning time. In the switch unit 404, based on these transferred data, the selection potential V0Y (potential V5Y at the time of polarity reversal at the time of alternating current driving) is selected data if it is selected data, and the non-selection potential V4 (when alternating current driving is performed at the time of non-selected data) When the polarity is inverted, the potential V1) is selected and output to each scan electrode 1. In this way, for example, a scan electrode driving waveform by a general voltage averaging method as shown in FIG. 5A is obtained.

On the other hand, the signal electrode driving section 10 receives the signal from the video signal data generating circuit 405 and receives the signal electrode 2
The output potential of each of X1 to X640 of V0, V2
, V3, or V5, select and set one. Specifically, as shown in FIG. 3, a shift register 406 for sequentially transferring video signal data, a data latch 407 for temporarily storing this data, a signal selection potential (V0, V5) for designating ON display by this data, or A switch unit 4 for selecting a signal non-selection potential (V2, V3) designating OFF display
08, and the shift register 406 includes video signal data (indicated as DATA in the drawing, hereinafter referred to as DATA).
In response to this, DATA is transferred from X1 to X640 by the clock pulse CP for transferring this DATA.
The data latch 407 receives LP (latch pulse) and accumulates DATA from X1 to X640. In the switch unit 408, based on the accumulated DATA, if DATA is selected (on) data, the selection potential V5
(Or potential V0 at the time of polarity reversal during AC drive)
If non-selected data (OFF) is selected, the non-selected potential V3 (or the potential V2 at the time of polarity reversal during AC driving) is selected and output to each signal electrode 2. Thus, for example, in FIG.
A signal electrode drive waveform is obtained by a general voltage averaging method as shown in (b).

When the driving voltage is applied to each of the scanning electrode 1 and the signal electrode 2 as described above, the voltage waveform applied to the liquid crystal layer 3 has a polarity inversion as shown in FIG. With this waveform, the amplitude of the selected pulse changes according to the display contents (ON, OFF).

As is well known, the polarity inversion driving method is a driving method which is performed by using an AC liquid crystal applied voltage in order to prevent deterioration of the liquid crystal composition due to application of a DC voltage component to the liquid crystal layer. Drive voltage power supply circuit 401 described in
A reference voltage generation circuit 15 formed of a complementary MOS-FET having a function of inverting the polarity at a constant cycle is added to the device, which is controlled by an FR (polarity inversion) signal as shown in FIG. 6A. Fig. 6 (b)
A reference voltage Vref having a substantially symmetrical waveform in both polarities with respect to the center voltage Vc as shown in (1) and having very little waveform blunting at the time of polarity reversal is output.

In general, the complementary MOS-FET has a very good symmetry in both rising and falling polarities of the output waveform and very little blunting of the output waveform. At both sides, the reference voltage V is symmetrical and has little bluntness
It is suitable as a means for generating ref. Therefore, by generating the reference voltage Vref by the reference voltage generation circuit 15 using such a complementary MOS-FET and using it as the reference, the distortion voltage component can be accurately extracted from the detected voltage with both polarities. Of.
Moreover, since the complementary MOS-FET consumes very little power, it is suitable as a circuit element used in a liquid crystal display device. Further, for example, by forming the entire scan driver circuit or the like with complementary MOS-FETs,
Since the operating speeds of the scan driver circuit 8 and the signal driver circuit 11 can be made substantially equal to each other, it is possible to eliminate the deviation of the operation timing, which is preferable.

The drive voltage power supply circuit 401 receives the power supply voltage VDD from the power supply and receives the liquid crystal drive voltage potentials (V0, V1, V) which are generally necessary for driving the liquid crystal display element 4.
2, V3, V4, V5, V0Y, V5Y) and output. Of these potentials, V0Y, V1, V4 and V5Y are supplied to the scan electrode driving section 7, and V0, V2, V3 and V5 are supplied to the signal electrode driving section 10, respectively.

An operational amplifier circuit 9 for controlling the distortion of the voltage of the scan electrode 1 is formed in the drive voltage power supply circuit 401, and only the distortion voltage component of the voltage detected by the detection electrode 13 is calculated. It is extracted by the amplifier circuit 9 and fed back to the scan electrode 1.

The voltage detected by the detection electrode 13 is inputted to the non-inverting terminal 412 side of the differential amplifier 411 through the wiring 14 and the buffer 410 in the driving voltage power supply circuit 401 as shown in FIG. . On the other hand, the reference voltage generation circuit 15
A reference voltage Vref that changes in synchronism with the polarity inversion signal FR and has an amplitude equal to the amplitude of the scanning voltage output from the voltage dividing circuit 413 is generated and input to the inverting terminal 414 of the differential amplifier 411. As described above, the reference voltage Vref changes in potential in synchronization with the scanning voltage (FIG. 6B).
The voltage waveform has both rising and falling polarities and good symmetry and little blunting as shown in FIG. Further, the scanning voltage also has a waveform with little dullness as shown in FIG.

Then, the differential amplifier 411 calculates the difference between the detection voltage and the reference voltage Vref, and the difference is calculated by the resistor 415.
The distortion voltage component generated in the scan electrode 1 is extracted by performing amplification based on the amplification factor set by the above. Then, the extracted distortion voltage components are electric resistances R1, R2,
The four operational amplifiers 416 (a), (b), (e), and (f) whose negative amplification factors are set by R3 and R4 are connected to capacitors 417 (a), (b), (c), ( It is input via capacitive coupling according to d). Here, what is connected via capacitive coupling by the capacitor 417 is that the input sides of the four operational amplifiers 416 (a), (b), (e), and (f) are electrically connected to one wiring. Then, the potentials V0Y, V1, V4, and V5Y output from the voltage dividing circuit 413 are short-circuited, and in order to avoid this, it is necessary to separate each from the DC voltage component.

Operational amplifier 416 (a), (b),
(E) and (f) are potentials V0Y, V1 output from the voltage dividing circuit 413 as potentials for forming the scanning voltage waveform.
The above-mentioned extracted strained voltage components are superimposed on V4 and V5Y by inverting the displacement direction and output to the switch section 404. Then, the switch section 404 outputs the scan voltage to each scan electrode 1 as described above. In this way, the scanning voltage obtained by subtracting the voltage corresponding to the distortion voltage component by the feedback control is applied from the scanning electrode driving unit 7 to the scanning electrode 1,
The distortion voltage generated in the voltage of the scan electrode 1 can be eliminated.

In the liquid crystal display device according to the present invention as described above, a duty ratio of 1/200, a bias ratio of 1/13 and a frame frequency are used by using a liquid crystal driving voltage having a waveform as shown in FIG.
Display was performed by driving at 80 Hz so that the polarity was reversed every 13 lines, and the display quality was visually verified.

First, after displaying the entire screen in white, a horizontal striped pattern of black and white is displayed in an area of 150 dots vertically by 10 dots horizontally in the vicinity of the center of the screen, and then the number of horizontal dots in this area is set to 5
The number was gradually increased to 00 dots, but in each case, a uniform display without crosstalk could be maintained. Also,
Although Chinese characters and alphabets were displayed continuously, the generation of strain voltage on the scan electrodes was suppressed, and a uniform display without crosstalk could be maintained.

In the above embodiment, the detection electrode 13 is collectively detected via the electric capacitance 12 to detect the voltage of the scanning electrode 1, but in addition to this, the electric capacitance 12 is also detected.
You may use electric resistance instead of.

[0052]

As is clear from the detailed description above, the liquid crystal display device of the present invention eliminates the display unevenness caused by the waveform rounding of the liquid crystal applied voltage, and provides a uniform and good display without crosstalk. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a liquid crystal display device of the present invention.

FIG. 2 is a diagram schematically showing a liquid crystal display element used in the liquid crystal display device of the present invention.

FIG. 3 is a block diagram showing an overall circuit configuration of a liquid crystal display device of the present invention.

FIG. 4 is a diagram showing a drive voltage power supply circuit of a liquid crystal display device according to the present invention.

FIG. 5 is a diagram showing a liquid crystal drive voltage waveform used in the liquid crystal display device of the present invention.

FIG. 6 is a FR signal used in the liquid crystal display device of the present invention;
The figure which shows each waveform of reference voltage Vref and scanning voltage.

FIG. 7 is a conceptual diagram in which only one scanning electrode 1 of a conventional liquid crystal display device is extracted and expressed by an equivalent circuit and its V1.
Showing voltage waveforms of V, V2 and V3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scan electrode, 2 ... Signal electrode, 3 ... Liquid crystal layer, 4 ... Liquid crystal display element, 5 ... Scan driver circuit, 6 ... Signal driver circuit, 7 ... Scan electrode drive part, 8 ... Scan voltage power supply circuit, 9 ...
Operational amplifier circuit, 10 ... Signal electrode drive unit, 11 ... Signal voltage power supply circuit, 12 ... Electric capacitance, 13 ... Detection electrode, 14 ... Wiring, 15 ... Reference voltage generation circuit, 204 ... Scan electrode voltage detection unit, 401 ... Drive Voltage power supply circuit, 404, 408 ... Switch section, 410 ... Buffer, 411 ... Differential amplifier, 4
16 ... Operational amplifier

Claims (1)

[Claims] 1. A scan electrode substrate on which a plurality of scan electrodes are formed, and a signal electrode substrate on which a plurality of signal electrodes are formed to face each other so as to intersect the plurality of scan electrodes while maintaining a gap therebetween. A liquid crystal display element having a liquid crystal layer sandwiched between the scan electrodes and the signal electrodes, a scan driver circuit for generating a scan voltage and applying the scan voltage to the scan electrodes, and a signal voltage for generating the signal A liquid crystal display device having a signal driver circuit applied to electrodes, wherein one end of each of the plurality of scan electrodes is connected to an electric capacity or electric resistance, and the other end of the electric capacity or electric resistance is connected to the other, A detection electrode for collectively detecting a voltage from the scanning electrode at the end connected portion and a reference voltage generator for outputting a reference voltage, which is formed of a complementary MOS field effect transistor. A circuit, which is connected to the detection electrode and which calculates and amplifies the difference between the voltage detected from the scanning electrode via the detection electrode and the reference voltage to extract a distortion voltage component, A liquid crystal display device, comprising: an operational amplifier circuit that feeds back to the scan electrodes and suppresses the generation of the distortion voltage of the plurality of scan electrodes.