JPH0772802A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To realize a liquid crystal display device maintaining a uniform and excellent display without cross-talk by stably dissolving display unevenness due to the waveform deformation of impressed voltage of a liquid crystal. CONSTITUTION:Even when the an ambient temp. is changed and the capacitance, etc., of a liquid crystal cell is changed by a secular change since a detection voltage of a first detection electrode 12(a) is used as a reference voltage, and a distortion voltage component is extracted by taking a difference with the detection voltage of a second detection electrode 12(b), since the detection voltage of the first detection electrode 12(a) and the detection voltage of the second detection electrode 12(b) are potential-changed at the same condition also even if any disturbance is given, no distortion voltage component extracted by comparing them is affected by disturbance, and since only the distortion voltage component is extracted always and correctly, and excellent feed-back control is performed, the distortion component of a driving voltage waveform is eliminated, and a display defect is dissolved stably.

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 a liquid crystal display element (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. 8A 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. The waveform of such a scanning voltage V2 is shown in FIG. Further, the signal electrode driver (not shown) is ± V as shown in FIG.
It is assumed that the signal voltage V1 having a waveform whose polarity is inverted between rev is output.

Considering the case where a square-wave signal voltage V1 is applied to the electrostatic capacitance (liquid crystal capacitance) 901 of the liquid crystal layer from the signal electrode driver side in this equivalent circuit, the liquid crystal capacitance (C _LC ) 901 and the total electrical At the connection point 903 with the resistor (R) 902, a spike-like strain voltage V3 based on the time constant C _LC · R is generated. The waveform of this distortion voltage V3 is shown in FIG.
It shows in (d). Since such a spiked distortion voltage V3 is generated, the liquid crystal applied voltage applied to the liquid crystal capacitance C _LC 901 is reduced by a voltage corresponding to the spiked distortion voltage V3 as shown in FIG. The waveform looks like a lag.
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.

It is also conceivable 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 such a special driver IC is not easy to develop. 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 is changed from the theoretical ideal waveform due to the distortion voltage generated due to the electrostatic capacitance of, and display unevenness (crosstalk) occurs on the screen.

In the known technique devised against this, there are problems that the preset compensation voltage deviates from the required optimum compensation voltage, and the device becomes complicated or expensive. there were.

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 of 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. A liquid crystal display element having a signal electrode substrate formed with a plurality of signal electrodes opposed to each other, and a liquid crystal layer sandwiched and sandwiched between the scanning electrode and the signal electrode, and a drive voltage The plurality of scan electrodes having a drive voltage generation circuit that outputs a plurality of potentials and a switch circuit that selects one voltage from a plurality of potentials output from the drive voltage generation circuit and applies the selected voltage to the scan electrodes. In a liquid crystal display device having a scan driver circuit for applying a scan voltage to each and a signal driver circuit for applying a signal voltage to each of the plurality of signal electrodes, an input of each of the plurality of scan electrodes A first electric resistance whose one end is connected to the portion, and a first detection electrode which is connected to the other end of the first electric resistance and detects the voltage of the input end portion of the scanning electrode all together. , A second electric resistance whose one end is connected to a portion different from the input end portion of each of the plurality of scan electrodes, and the other end of the second electric resistance is collectively connected to the second electric resistance of the scan electrode. A second detection electrode for collectively detecting the voltage of the portion to which the electric resistance is connected, and the second voltage and the second voltage based on the voltage detected by the first detection electrode.
Comparing with the voltage detected by the detection electrode, the operational amplifier circuit for taking out the distorted voltage component from the voltage of the scanning electrode and synthesizing it with the potential forming the scanning voltage among the plurality of potentials output from the drive voltage generating circuit. And suppressing generation of strain voltage of the plurality of scan electrodes.

Further, in the liquid crystal display device of the present invention, a scanning electrode substrate having a plurality of scanning electrodes formed thereon and a plurality of signal electrodes arranged so as to oppose each other so as to intersect the plurality of scanning electrodes while maintaining a gap therebetween. A liquid crystal display element having a formed signal electrode substrate, a liquid crystal layer enclosed and sandwiched between the scanning electrode and the signal electrode, and a drive voltage generation circuit for outputting a plurality of potentials for generating a drive voltage A scan driver circuit that has a switch circuit that selects one voltage from a plurality of potentials output from the drive voltage generation circuit and applies the voltage to the scan electrodes, and a scan driver circuit that applies a scan voltage to each of the plurality of scan electrodes. A liquid crystal display device having a signal driver circuit for applying a signal voltage to each of the plurality of signal electrodes,
A first electric capacitance whose one end is connected to the input end portion of each of the plurality of scan electrodes, and the other end of the first electric capacitance are collectively connected to collectively collect the voltage of the input end portion of the scan electrode. A first detection electrode that is detected by a second electric capacitance, one end of which is connected to a portion different from the input end portion of each of the plurality of scanning electrodes, and the other end of the second electric capacitance that is collectively connected. A second detection electrode for collectively detecting the voltage of a portion of the scan electrode to which the second capacitance is connected, and the voltage and the first detection electrode based on the voltage detected by the first detection electrode. The voltage detected by the second detection electrode is compared to extract the distorted voltage component from the voltage of the scan electrode,
An operational amplifier circuit for synthesizing a potential forming a scanning voltage among a plurality of potentials output from the drive voltage generating circuit is provided to suppress generation of a distortion voltage of the plurality of scanning electrodes.

It should be noted that one end of the second electric resistance or the second electric capacitance is connected to a portion different from the input end portion of the scan electrode to which the first electric resistance or the first electric capacitance is connected as described above. However, this may be connected to, for example, the open end portion of the scan electrode, or may be connected to the central portion of the scan electrode. It is preferable to connect to the open end portion of the scan electrode because it is possible to detect a gradual voltage drop or distortion voltage due to the internal resistance of the scan electrode over substantially the entire length from the input end to the open end of the scan electrode. Alternatively, for example, in the case of a liquid crystal display device in which driving circuits are connected to both ends of one scanning electrode and driven from both ends, one end of the second electric resistance or the second electric capacity is provided at the center of each scanning electrode. Should be connected.

Further, in the above-mentioned first capacitance and second capacitance, the scanning electrode and the signal electrode are used as two electrodes facing each other, and the liquid crystal layer is used as a dielectric material sandwiched between the two electrodes. May be.

Needless to say, the scan voltage output from the scan driver circuit is a voltage formed by the scan non-selection voltage and the scan selection voltage (so-called scan pulse), but the polarity inversion is performed. As for the method, even when the voltage during scanning non-selection is constant and only the voltage during scanning selection (scanning pulse) inverts the polarity with the voltage during scanning non-selection as the center voltage, or the voltage during scanning selection around a specific center voltage The present invention can be applied to both of the cases where the polarities of the voltages are reversed when scanning is not selected.

[0025]

In the liquid crystal display device according to the present invention, the voltage detected from the input end portion of the scanning electrode by the first electric resistance or the first electric capacity is used as the reference voltage, and the reference voltage and the second electric resistance or The operational amplifier circuit compares the voltage detected from the scan electrode via the second electric capacity with the operational amplifier circuit to extract only the distorted voltage component from the voltage detected by the second electric resistance or the second electric capacity. By amplifying and feeding back to the scan electrode, the strain voltage generated in the scan electrode can be canceled. At this time, needless to say, the operational amplifier circuit is set to have a polarity (a displacement direction of the output voltage) and an amplification factor that can cancel the distortion voltage generated in the scan electrodes.

As described above, distortion voltage components, such as spike distortion voltages, which are generated in the voltage of the scan electrodes and which have an unfavorable influence on image display are collectively extracted from a plurality of scan electrodes, and the distortion voltage components are scanned. By returning the voltage to the electrodes, it is possible to suppress the strain voltage that is about to occur in the scan electrodes.

When the above-mentioned distorted voltage component is extracted from the voltage of the scan electrode, the voltage detected at the input end portion of the scan electrode itself is used as a reference voltage, and this reference voltage and the second electric resistance or the second electric resistance are used. Since only the distortion voltage component is extracted by calculating the difference from the detection voltage detected from the scan electrode with the electric capacity of, the magnitude of the voltage applied from the drive voltage generation circuit to the liquid crystal cell (liquid crystal layer) can be determined. Regardless of what value is changed or how the voltage is changed due to temperature change or aging of the liquid crystal layer, both the reference voltage and the detection voltage are almost the same due to such disturbance. , The distortion voltage component obtained as a relative difference between these voltages is always accurately extracted.

Further, the present invention provides one feedback loop for the scan electrode and its drive circuit, that is, specifically, a feedback loop whose main part is composed of electric resistance or capacitance, detection electrode, operational amplifier circuit and the like. Since it only needs to be formed,
It is possible to realize a liquid crystal display device capable of displaying a high-quality image very easily and inexpensively.

In this way, according to the present invention, it is possible to obtain a stable crosstalk removing effect without fluctuation of the operating characteristics by a simple means when the ambient temperature changes.

[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 a liquid crystal driving circuit 5 on the scanning side and a liquid crystal driving circuit 6 on the signal side for driving the same.

The liquid crystal driving circuit 5 on the scanning side has a scanning driver circuit 7, a scanning voltage generating circuit 8 for supplying a power supply voltage to the scanning driver circuit 7, and an operational amplifier circuit 9 for receiving the feedback voltage and controlling the scanning voltage. The liquid crystal drive circuit 6 on the signal side includes a signal driver circuit 10 and a signal voltage generation circuit 11 that supplies a power supply voltage to the signal driver circuit 10.

Further, as shown in FIG. 2, the liquid crystal display element 4
Includes a first electric resistance 12 on each end of each scanning electrode 1.
(A) and 2nd electric resistance 12 (b) are each arrange | positioned.

The first electric resistor 12 (a) is electrically connected to the input end portion of the scanning electrode 1 at one end and the first end at the first end.
Are collectively connected to the detection electrodes 13 (a), and the voltages at the input end portions of the scanning electrodes 1 detected by the first electric resistance 12 (a) are collectively collected to form the wiring 14 (a). It is input to the operational amplification circuit 9 of the liquid crystal drive circuit 5 on the scanning side via the above.

The second electric resistance 12 (b) is electrically connected to the open end portion of the scan electrode 1 at one end and the second end at the second end.
Are collectively connected to the detection electrodes 13 (b), and the voltages at the open ends of the scanning electrodes 1 detected by the second electric resistance 12 (b) are collectively collected to form the wiring 14 (b). It is input to the operational amplification circuit 9 of the liquid crystal drive circuit 5 on the scanning side via the above.

Then, the operational amplifier circuit 9 uses the input voltage of the input end portion of the scan electrode 1 as a reference voltage, and compares this reference voltage with the input voltage of the open end portion of the scan electrode 1. As a result, the distortion voltage component generated in the scan electrode 1 is taken out and fed back to the scan electrode 1 as a voltage for canceling the distortion voltage component. With such an electrical structure, the distorted voltage component of the scan electrode 1 can be accurately canceled no matter how the voltage of the scan electrode 1 is changed by disturbance. This can eliminate crosstalk in the display image.

The above has outlined the electrical structure and operation of the liquid crystal display device according to the present invention. Next, the specific structure and operation of the liquid crystal display device of the first embodiment 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 STN type liquid crystal display element 4 has a cell gap of about 7 μm and is provided with an alignment film (not shown) made of a resin subjected to a rubbing alignment treatment, and the liquid crystal of the liquid crystal layer 3 is provided between the cell gaps of the liquid crystal display element 4. The molecules are oriented so that they twist by 240 °. Liquid crystal layer 3
ZLI-2293 manufactured by Merck was used as the liquid crystal composition. Further, the transparent electrodes of the scan electrode 1 and the signal electrode 2 are IT
It is formed from O.

An optical phase compensating cell (not shown) is pasted on the glass substrates 203 (a) and (b) on the outward side of the liquid crystal display element to display in black and white, and black when no voltage is applied. A white display is obtained when a voltage is applied.

At the input end portion and the open end portion of each scanning electrode 1 provided on the glass substrate 203 (b), the first electric resistance 12 (a) and the second electric resistance 12 are respectively provided as described above. (B) is provided. These electrical resistance 12
Specifically, (a) and 12 (b) are specifically the scanning electrodes 1 respectively.
The first detection electrode 13 (a) and the second detection electrode 13 (b) each having a strip shape are formed by printing resistors on the scanning electrode 1 so as to cross all the scanning electrodes 1. Once formed, the other ends of all the first electric resistances 12 (a) are collectively connected to the first detection electrode 13 (a), and the other ends of all the second electric resistances 12 (b) are connected. They are collectively connected to the second detection electrode 13 (b). First electrical resistance 12
(A) and the second electric resistance 12 (b) are formed to have the same electric resistance value and the same shape, and the first detection electrode 13
(A) and the second detection electrode 13 (b) are also formed in the same shape.

FIG. 3 is a block diagram showing the overall structure of the liquid crystal display device of this embodiment. A scan driver circuit 7 and a signal driver circuit 10 are connected to the scan electrodes 1 and the signal electrodes 2 in the liquid crystal display element 4, respectively.

The liquid crystal driving circuit 5 on the scanning side supplies a power supply voltage to the scanning driver circuit 7, and at the same time, the first detection electrode 1
3 (a) and the second detection electrode 13 (b) respectively, and has an operational amplifier circuit 9 for receiving the voltages detected and feedback-controlling the distortion voltage component of the scanning electrode 1.

The signal side liquid crystal drive circuit 6 has a signal driver circuit 10 and a signal voltage generation circuit 11 for applying a power supply voltage to the signal driver circuit 10.

In FIG. 3, the scanning voltage generating circuit 8 and the signal voltage generating circuit 11 are shown separately for easier understanding of the illustration and description, but in practice they are combined into one. Composed. This is because the structure can be simple, accurate, and inexpensive by combining them into one. In this embodiment, the circuit that is combined into one is configured as a drive voltage generation circuit 401 as shown in FIG.

The scan driver circuit 7 receives the control signal from the scan data generation circuit 402 and receives Y1 of the scan electrode 1.
One of the output potentials V0Y, V1, V4, and V5Y output from the drive voltage generating circuit 401 is selected from the output potentials from Y to Y200. Specifically, as shown in FIG. 3, a shift register 403 that sequentially transfers scan data and a scan potential when scanning is selected, that is, a scan pulse (V0Y, V5Y) or a scan potential (V1 when not scanning) is selected according to this data. ,
The main part is composed of a switch section 404 for selecting V4), and the shift register 403 receives FP (frame pulse) that determines one frame time as basic scan data, and becomes LP (latch pulse) that determines one scan time. Based on this, data is transferred from outputs Y1 to Y200. 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 driver circuit 10 receives a signal from the video signal data generation circuit 405 and sets the output potentials of X1 to X640 of the signal electrode 2 to V0 and V640, respectively.
Select one from 2, V3 and V5 and set.

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, and a signal selection potential (V0 for designating ON display by this data). , V5) or a switch section 408 for selecting a signal non-selection potential (V2, V3) designating OFF display, and the shift register 406 is shown as video signal data (shown as DATA in the drawing).
(Hereinafter referred to as DATA), the data is transferred from X1 to X640 by the clock pulse CP for transferring this DATA. Then, in the data latch 407, L
DA from X1 to X640 in response to P (latch pulse)
Accumulate TA. In the switch unit 408, based on the accumulated DATA, the selection potential V5 (or the potential V0 at the time of polarity reversal during AC drive) is selected data when the DATA is the selection (ON) data, and the non-selection potential is the non-selection data (OFF). V3 (or potential V2 at the time of polarity reversal during AC driving) is selected and output to each signal electrode 2. Thus, for example, a signal electrode drive waveform by a general voltage averaging method as shown in FIG. 5B is obtained.

As shown in FIG. 4, the drive voltage generating circuit 401 receives the power source voltage VDD from the power source and divides it by the electric resistances R5 and R6 of the voltage dividing circuit 409 to drive the liquid crystal display element 4. In general, the potential (V0, V
1, V2, V3, V4, V5, V0Y, V5Y) are produced and output as the above potential through the buffers 410 (a) to (f) using operational amplifiers. Of these output potentials, V0Y, V1, V4, and V5Y are supplied to the scan driver circuit 7, and V0, V2, V3, and V5 are supplied to the signal driver circuit 10, respectively, and the scan driver is used by using these potentials. The scanning voltage having the above waveform is applied to the scanning electrode 1 from the circuit 7, and the signal voltage having the above waveform is applied to the signal electrode 2 from the signal driver circuit 10.

When the drive voltage is applied to each of the scan electrode 1 and the signal electrode 2 in this way, the voltage waveform applied to the liquid crystal layer 3 is inverted in polarity, for example, for each frame as shown in FIG. 5C. 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. A function for inverting the polarity at a constant cycle is added to the switch units 404 and 408 of the scan driver circuit 7 and the signal driver circuit 10 described in Section 1 above, and the polarity inversion is controlled by the FR signal (polarity inversion signal). Done.

Then, the drive voltage generating circuit 4 as described above is used.
01, an operational amplifier circuit 9 for controlling the distortion of the voltage of the scan electrode 1 is added, and the voltage detected by the second detection electrode 12 (b) is detected by the first detection electrode 12 (a). The voltage detected by the first detection electrode 12 (a) is used as a reference voltage and the second detection electrode 12 (b) is compared.
Only the distorted voltage component of the voltage detected in (3) is taken out and fed back to the scan electrode 1 to eliminate the distorted voltage generated in the scan electrode 1. Here, the operational amplifier circuit 9 described above
In the present embodiment, the first buffer 411
(A), second buffer 411 (b), differential amplifier circuit 4
Operational amplifier circuit 4 using 12 and 4 buffers, respectively
10 (a), (b), (e), (f).

As shown in FIG. 4, the first detection electrode 13
The voltage on the input end side of the scan electrode 1 detected in (a) is transmitted via the first buffer 411 (a) to the differential amplifier circuit 412.
Input to the inverting terminal of. In addition, the second detection electrode 13
The voltage on the open end side of the scan electrode 1 detected in (b) is transmitted to the differential amplifier circuit 412 via the second buffer 411 (b).
Input to the non-inverting terminal of.

The differential amplifier circuit 412 includes the first detection electrode 1
Detection with a large amount of distortion on the open end side of the scan electrode 1 detected by the second detection electrode 13 (b) using the detection voltage on the input end side of the scan electrode 1 detected in 3 (a) as a reference voltage. The difference from the voltage is calculated, and the strain voltage component generated in the scan electrode 1 is extracted. And the extracted distortion voltage component is R1 in the latter stage.
, R2, R3, R4 set negative amplification factor
Four operational amplifier circuits 410 (a), (b), (e),
Capacitive coupling 413 (a), (b), (c),
It is input via (d). Connected via capacitive coupling are four operational amplifier circuits 410 (a),
When the input sides of (b), (e), and (f) are electrically directly connected to one wiring, the potentials V0Y, V output from the voltage dividing circuit 409.
Since 1, V4 and V5Y are short-circuited, it is necessary to separate them from the DC voltage in order to avoid this.

The operational amplifier circuit 410 (a),
(B), (e) and (f) are potentials V0 output from the voltage dividing circuit 409 as potentials for forming the scanning voltage waveform.
Y, V1, V4, V5Y and the distorted voltage component output from the differential amplifier circuit 412 are superimposed and output to the switch unit 404. Then, the switch unit 404 outputs the scanning voltage on which the distortion voltage component is superimposed to each scanning electrode 1.

In this way, the scan driver outputs a voltage obtained by inverting only the distortion voltage component from the detection voltage containing a large amount of the distortion component on the open end side of the scanning electrode 1 detected by the second detection electrode 13 (b). By applying the voltage from the circuit 7 to the scan electrode 1, the distortion voltage generated in the voltage of the scan electrode 1 can be eliminated. Moreover, even if the capacitance of the liquid crystal cell changes due to a change in the ambient temperature or a change over time, the second detected voltage of the first detection electrode 13 (a) is used as the reference voltage.
The distorted voltage component is extracted by taking the difference with the detection voltage of the detection electrode 13 (b). Therefore, no matter what kind of disturbance, the first detection electrode 13
Since the detection voltage of (a) and the detection voltage of the second detection electrode 13 (b) both fluctuate in the same manner, the distortion voltage components extracted by comparing them (by taking a relative difference) are Without being disturbed, only the distortion voltage component is always accurately extracted, and good feedback control can be performed. As a result, it is possible to always effectively eliminate the unevenness of display (crosstalk) and maintain good image display.

In the liquid crystal display device of the first embodiment according to the present invention as described above, the duty ratio 1/200, the bias ratio 1/13, the frame frequency are used by using the liquid crystal drive voltage having the 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 stripe pattern of white and black is displayed in an area of vertical 150 dots × horizontal 10 dots near 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.

Next, the liquid crystal display device of the present embodiment is set at an ambient temperature of 50.
When the above-mentioned display was performed under the environment of ° C, a uniform display without crosstalk could be maintained as in the above.

Further, when this was moved to an environment of an ambient temperature of 10 ° C. and a display similar to the above was performed, it was possible to maintain a uniform display without crosstalk.

Furthermore, after moving this to an environment of an ambient temperature of 25 ° C. and continuously lighting it for 2000 hours, the same display as above was displayed, but in this case as well, a uniform display without crosstalk was obtained. I was able to maintain. From such an experiment, it was confirmed that the liquid crystal display device of the present invention has high display quality, excellent durability, and high reliability.

(Comparative Example to First Example) From the liquid crystal display device of the first example, the first electric resistance 12 (a) and the second electric resistance 12 (b), which are the main parts of the present invention, are provided. ,
First detection electrode 13 (a), second detection electrode 13
(B), the operational amplifier circuit 9 and the like are removed, and the drive voltage generating circuit is divided into a voltage dividing circuit 409 and a buffer 6 as shown in FIG.
01 (a), (b), (c), (d), (e), (f)
Drive voltage generation circuit 600 of conventional general structure using
Replaced with. A liquid crystal display device having such a conventional structure was caused to perform display under the same driving conditions as in the first embodiment, and the display quality was visually verified.

First, after displaying the entire screen in white, a horizontal stripe pattern of white and black is displayed in an area of vertical 150 dots × horizontal 10 dots near the center of the screen, and then the number of horizontal dots in this area is set to 5
I gradually increased it to 00 dots, but when a white and black horizontal stripe pattern was displayed in an area of vertical 150 dots × horizontal 10 dots, dark crosstalk occurred in the vertical direction and the display area As the number of dots in the horizontal direction of was increased, this vertical crosstalk occurred more significantly.
In addition, new crosstalk occurs in the horizontal direction of the display,
The display quality is significantly degraded. In addition, Chinese characters and alphabets were displayed continuously, but in this case as well, remarkable crosstalk in the vertical and horizontal directions occurred, and the nonuniformity of the screen was noticeable.

(Embodiment 2) The liquid crystal display element 4 in the liquid crystal display device of the first embodiment is the first one used in the first embodiment.
Electrical resistance 12 (a) and second electrical resistance 12 (b)
Instead of the above, a liquid crystal display element 702 as shown in FIG. 7 using the first electric capacity 701 (a) and the second electric capacity 701 (b) was replaced.

Then, the voltage detected by the first electric capacity 701 (a) electrically connected to the first detection electrode 13 (a) is used as a reference, and this and the second detection electrode 13 (b) are connected to each other. Each operation forming the operational amplifier circuit 9 so that the voltage detected by the electrically connected second capacitance 701 (b) is compared with the operational amplifier circuit 9 to accurately extract the distorted voltage component. The amplification circuits (buffers) 410 (a) to (f) and the amplification factor of the differential amplification circuit 412 were changed, and the other parts had substantially the same structure as the first embodiment.

Here, the above-mentioned first electric capacity 701
Specifically, (a) and the second capacitance 701 (b) are substantially the same as the signal electrode 2 provided on the glass substrate 203 (a) so as to face the scanning electrode 1 with the liquid crystal layer 3 in between. Electrode-shaped first detection electrode 13 (a), second detection electrode 1
3 (b) and the scanning electrode 1 are used as a pair of electrodes facing each other, and the liquid crystal layer 3 sandwiched between the facing electrodes is used as a dielectric.

That is, the liquid crystal layer 3 is used as a dielectric between the first detection electrode 13 (a) and the input end portion of the scanning electrode 1,
701 (a) is formed, and the second capacitance 701 (b) is formed between the second detection electrode 13 (b) and the open end portion of the scanning electrode 1 by using the liquid crystal layer 3 as a dielectric. Are formed.

In the liquid crystal display device of the second embodiment as described above, the duty ratio 1/200 and the bias ratio 1 are used by using the liquid crystal drive voltage having the waveform as shown in FIG. 5 similarly to the first embodiment.
The display quality was visually verified by driving the display at a polarity of / 13 and a frame frequency of 80 Hz so that the polarity was reversed every 13 lines. First, after displaying the entire screen in white, a horizontal stripe pattern of white and black is displayed in the area of 150 dots vertically × 10 dots horizontally near the center of the screen, and the number of horizontal dots in this area is gradually increased to 500 dots. However, in each case, a uniform display without crosstalk could be maintained. Further, although Chinese characters and alphabets were displayed continuously, generation of strain voltage in the scan electrodes was suppressed, and uniform display without crosstalk could be maintained. In this case, the effect of suppressing crosstalk was higher than that in Example 1.
Next, the liquid crystal display device of this example was placed in an environment of an ambient temperature of 50 ° C. to perform the above-mentioned display, but similarly, it was possible to maintain a uniform display without crosstalk. Moreover, this was moved to an environment of an ambient temperature of 10 ° C. and a similar display was performed, but similarly, a uniform display without crosstalk could be maintained. Furthermore, after moving this to an environment with an ambient temperature of 25 ° C and lighting it for 2000 hours continuously, the same display as above was displayed, but in this case as well, it is possible to maintain a uniform display without crosstalk. did it. From such an experiment, it was confirmed that the liquid crystal display device of the present invention has high display quality, excellent durability, and high reliability.

(Comparative Example to Second Example) From the liquid crystal display device of the second example, the first part which is the main part of the present invention
Electric capacity 701 (a) of the second electric capacity 701
(B), first detection electrode 13 (a), second detection electrode 1
3 (b), the operational amplifier circuit 9 and the like are removed, and the drive voltage power supply circuit 401 is divided into a voltage dividing circuit 409 and buffers 601 (a), (b), (c), (d), as shown in FIG.
The drive voltage generating circuit 600 of the conventional general structure using (e) and (f) is replaced. A liquid crystal display device having such a conventional structure was caused to perform display under the same driving conditions as in the second embodiment, 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 vertical 150 dots × horizontal 10 dots near the center of the screen, and then the number of horizontal dots in this area is set to 5
I gradually increased it to 00 dots, but when a white and black horizontal stripe pattern was displayed in an area of vertical 150 dots × horizontal 10 dots, dark crosstalk occurred in the vertical direction and the display area As the number of dots in the horizontal direction of was increased, this vertical crosstalk occurred more significantly.
In addition, new crosstalk occurs in the horizontal direction of the display,
The display quality is significantly degraded. In addition, Chinese characters and alphabets were displayed continuously, but in this case as well, remarkable crosstalk in the vertical and horizontal directions occurred, and the nonuniformity of the screen was noticeable.

As the circuit structure forming the operational amplifier circuit 9, the structures shown in the above embodiments are merely examples, and the circuit structure capable of performing the operation as the operational amplifier circuit 9 according to the present invention. In addition to the above, various structures are conceivable. Therefore, the circuit structure forming the operational amplifier circuit 9 is not limited to the above embodiment.

Needless to say, various changes can be made to the material and structure of each part of the liquid crystal display device according to the present invention without departing from the scope of the present invention.

[0072]

As described above in detail, according to the present invention, the display unevenness caused by the waveform rounding of the liquid crystal applied voltage is eliminated, and a uniform and good display without crosstalk is realized. Further, it is possible to realize a liquid crystal display device that maintains a uniform and excellent display without crosstalk regardless of any disturbance.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a structure of a liquid crystal display device according to a first embodiment.

FIG. 2 is a diagram showing a structure of a liquid crystal display element used in the liquid crystal display device of the first embodiment.

FIG. 3 is a block diagram showing the overall structure of the liquid crystal display device of the first embodiment.

FIG. 4 is a diagram showing a drive voltage generating circuit of the liquid crystal display device of the first embodiment.

FIG. 5 is a voltage waveform (a) applied to the scanning electrodes, a voltage waveform (b) applied to the signal electrodes, and a liquid crystal applied to the liquid crystal of the liquid crystal display device of the first and second embodiments. The figure which shows an applied voltage waveform (c).

FIG. 6 is a diagram showing a drive voltage generating circuit in a conventional general liquid crystal display device used as a comparative example with respect to the first embodiment and the second embodiment.

FIG. 7 is a diagram showing the structure of a liquid crystal display element used in the liquid crystal display device of the second embodiment.

FIG. 8 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 side liquid crystal drive circuit, 6 ... Signal side liquid crystal drive circuit, 7 ... Scan driver circuit, 8 ... Scan voltage generation Circuit, 9 ... Operational amplifier circuit, 10 ... Signal driver circuit, 11
... Signal voltage generating circuit, 12 (a) ... First electric resistance, 1
2 (b) ... 2nd electric resistance, 13 (a) ... 1st detection electrode, 13 (b) ... 2nd detection electrode, 14 (a), 14
(B) ... Wiring, 401 ... Driving voltage generating circuit, 409 ... Voltage dividing circuit, 410 (a) to (f) ... Operational amplifier circuit (buffer), 412 ... Differential amplifier circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Shoko 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Incorporated company Toshiba Yokohama Office

Claims (2)

[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 enclosed and sandwiched between the scanning electrode and the signal electrode, a drive voltage generation circuit for outputting a plurality of potentials for generating a drive voltage,
A scan driver circuit that has a switch circuit that selects one voltage from a plurality of potentials output from the drive voltage generation circuit and applies the voltage to the scan electrodes, and a scan driver circuit that applies a scan voltage to each of the plurality of scan electrodes. In a liquid crystal display device having a signal driver circuit for applying a signal voltage to each of the plurality of signal electrodes, a first electric resistance having one end connected to each input end portion of each of the plurality of scan electrodes, A first detection electrode which is connected to the other end of the electric resistance of the scanning electrode and collectively detects the voltage of the input end portion of the scan electrode, and one end of which is connected to a portion different from the input end portion of each of the plurality of scan electrodes. And a second detection electrode for collectively detecting the voltage of a portion of the scanning electrode to which the other end of the second electric resistance is connected and which is connected to the second electric resistance. , The voltage detected by the first detection electrode is used as a reference, and the voltage detected by the second detection electrode is compared to extract a distortion voltage component from the voltage of the scan electrode to generate the drive voltage. An operational amplifier circuit that synthesizes a potential forming a scanning voltage among a plurality of potentials output from the circuit,
A liquid crystal display device, wherein generation of a strain voltage of the plurality of scan electrodes is suppressed. 2. 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 facing 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 enclosed and sandwiched between the scanning electrode and the signal electrode, a drive voltage generation circuit for outputting a plurality of potentials for generating a drive voltage,
A scan driver circuit that has a switch circuit that selects one voltage from a plurality of potentials output from the drive voltage generation circuit and applies the voltage to the scan electrodes, and a scan driver circuit that applies a scan voltage to each of the plurality of scan electrodes. In a liquid crystal display device having a signal driver circuit for applying a signal voltage to each of the plurality of signal electrodes, a first capacitance having one end connected to an input end portion of each of the plurality of scan electrodes, and the first capacitance A first detection electrode, which is connected to the other end of the capacitance and collectively detects the voltage of the input end portion of the scan electrode, and one end of which is connected to a portion different from the input end portion of each of the plurality of scan electrodes. A second electric capacitance, and a second detection electrode for collectively detecting a voltage of a portion of the scan electrode to which the other end of the second electric capacitance is connected and to which the second electric capacitance is connected, The distortion voltage component is extracted from the voltage of the scan electrode by comparing the voltage detected by the first detection electrode with the voltage detected by the second detection electrode, and the drive voltage generation circuit And an operational amplifier circuit that synthesizes a scanning voltage forming potential among a plurality of potentials output by
A liquid crystal display device, wherein generation of a strain voltage of the plurality of scan electrodes is suppressed.