JP2950335B2 - LCD panel drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Regarding a liquid crystal panel driving device, when driving a liquid crystal panel having a simple matrix structure using a voltage averaging method, generation of luminance unevenness depending on a display pattern for each line is described. In the first mode, the driving device of the liquid crystal panel is provided with a data electrode driver for selecting and deselecting a positive voltage application mode period and a negative voltage application mode period for a liquid crystal panel drive device in order to suppress individual differences and changes over time of the liquid crystal panel. A power supply circuit for applying a selection voltage and a non-selection voltage in the positive voltage application mode period and the negative voltage application mode period to the voltage and scan electrode driver, and each data electrode and each scan electrode provided on the liquid crystal panel are supplied from the power supply circuit. The data electrode is selected so that it is driven by the voltage averaging method using the selection and non-selection voltage between the positive voltage application mode period and the negative voltage application mode period. A control circuit for sending a data signal to the driver and a scan signal to the scan electrode driver; a variation detection circuit provided on one scan electrode of the liquid crystal panel for detecting the variation of the scan electrode selection voltage; and one scan electrode drive time A correction parameter generation circuit for measuring a light / dark ratio of data displayed on a selected scan electrode to generate a correction parameter, and a correction voltage generation circuit for generating a correction voltage having a magnitude corresponding to the correction parameter. And a voltage addition circuit for adding the correction voltage to the scan voltage when the power supply circuit is selected, and a magnitude of each correction voltage according to a variation after the addition of the correction voltage in the scan electrode provided with the variation detection circuit. And a correction voltage correction circuit for correction.

Further, in the second embodiment, instead of providing the fluctuation amount detection circuit 6 for detecting the fluctuation amount of the scan electrode selection voltage on one scan electrode in the liquid crystal panel driving device of the first embodiment, the liquid crystal panel display is not changed. A detection electrode that intersects with the data electrode is provided outside the area, and a fluctuation amount detection circuit is connected to the detection electrode. Further, the same voltage as the selection voltage is applied to the detection electrode every predetermined time outside the display operation of the scan electrode driver. A detection electrode drive circuit to be applied is provided, and when the detection electrode drive circuit operates, a correction parameter is generated with a data signal in a predetermined pattern, and the amount of change after addition of the correction voltage is detected to correct the magnitude of each correction voltage.

[Industrial applications]

The present invention relates to a driving device for a liquid crystal panel having a simple matrix structure.

2. Description of the Related Art In recent years, with the spread of personal computers, wide processors, and the like, liquid crystal display devices that are lightweight, thin, and can be driven by batteries have become remarkable as display devices instead of large and large power consumption CRTs. Driving methods for liquid crystal display devices are roughly classified into simple matrix type and active matrix type.The active matrix type is difficult to manufacture because each pixel requires a non-linear element. Display devices generally employ a simple matrix structure.

However, in a display device having a simple matrix structure, as the display capacity is increased, display unevenness (crosstalk) depending on the display pattern occurs due to its characteristics, and display quality deteriorates. Therefore, it is strongly desired to eliminate the display unevenness. ing.

[Conventional technology]

FIG. 8, in the liquid crystal panel of simple matrix structure shown in FIG. 9, "bright" when the write (of the liquid crystal display is a liquid crystal display device of the entire line as the X ₁ row and X ₂ columns ○ ), And the driving waveform of the liquid crystal panel when writing “dark” (the display of the liquid crystal is ●). In FIG. (A) is X ₁ column of data voltage application waveform (thick line),
X is a data voltage application waveform (dotted line) of _two columns, and (b) is Y ₁
Scan voltage waveform applied row, and (c) Y ₂ rows of scan voltage waveform applied, it is (d) the drive voltage waveform of the cell alpha (thick line), the driving voltage waveform of the cell beta (dotted line).

In the conventional driving method, the voltage averaging method shown in FIG. 10 is adopted, in which the first cycle is selected during the period of a frame, and the second cycle is selected in the next frame. A device that switches the first period and the second period every other line is practically used, and a DC component is not applied to the liquid crystal to realize highly reliable driving without deteriorating panel characteristics.

The switching between the first cycle and the second cycle is called polarity inversion, and the control signal thereof is called a polarity inversion signal.

[Problems to be solved by the invention]

However, in the conventional driving method, for example, as shown in FIG. 11, the “bright” (）) display of the cell A immediately after displaying a large number of “dark” (●) on a certain scan electrode and the “bright” There is a problem that the cell A becomes brighter than the cell B when compared with the "bright" display of the cell B immediately after the large number of display.

This problem will be described in more detail with reference to FIGS. It is known that the apparent resistance of the liquid crystal cell is lower in the "bright" display than in the "dark" display, and therefore, a larger current flows to the scan electrode in the "bright" display. Flow in. Therefore, as shown in FIG.
When liquid crystal cells 1 to N are connected to one scan electrode via resistors R, respectively, the potential difference Vd between both ends of the scan electrode can be expressed by the following equation.

Here, the "dark" display at the time of _{i K (K = 1~N) =} i B, "bright" display at the time of _{i K (K = 1~N) =} i W, and if put, when the "bright" display The fact that a larger current flows into the scan electrode in can be expressed by i _W = i _B + Δi. And
The potential difference Vd _B of the scan electrode when “dark” is displayed on all the cells 1 to N, , And “light” in cells X to Y (1 ≦ X <Y ≦ N)
The potential difference Vd _W of the scan electrode at the time of displaying is further reduced by displaying “bright” in the cells X to Y of the potential difference Vd _B , It is because the amount is added.

Therefore, the scan voltage becomes “dark” as shown in FIG.
The case where a large number of displays are performed (thick line) and the case where a large number of “bright” displays are performed (dotted line) are different. When the “bright” display is performed, the selection voltage level of the scan voltage application waveform is the first. It rises in the cycle of, and falls in the second cycle. Then the 14th
As shown in FIG. 15 and FIG. 15, the voltage level during the selection period of the cell drive waveform fluctuates, and the effective voltage decreases in both the “bright” display and the “dark” display cells.

As a result, the cells on the scan electrode displaying a large number of “bright” have a darker display than the cells on the scan electrode displaying a large number of “dark”.

In addition, since the amount of the change in the scan electrode selection voltage as described above also differs depending on the difference in the liquid crystal material and the difference in the panel temperature, it is said that simply correcting the scan electrode selection voltage reduces the degree of improvement in the luminance unevenness. There are also problems.

An object of the present invention is to provide a liquid crystal display device which solves the problems of the conventional simple matrix liquid crystal display device and can suppress the occurrence of luminance unevenness including a solid-state difference, a temperature difference, and a change with time of a liquid crystal panel. It is intended for.

[Means for solving the problem]

FIG. 1A shows the principle configuration of a first embodiment of the liquid crystal display device of the present invention which solves the conventional problems. First
Is a driving device for a simple matrix type liquid crystal panel 3 provided with a data electrode driver 1 and a scan electrode driver 2, wherein the data electrode driver 1 is supplied with a selection voltage in a positive voltage application mode period and a negative voltage application mode period. A power supply circuit 4 for applying a selection voltage and a non-selection voltage to the non-selection voltage and scan electrode driver 2 during the positive voltage application mode period and the negative voltage application mode period, and each data electrode and each scan electrode provided on the liquid crystal panel 3 The data electrode driver 1 and the scan electrode driver 2 are driven so that the data electrode driver 1 is driven by a voltage averaging method using a selection of a positive voltage application mode period and a negative voltage application mode period supplied from the power supply circuit 4 and a non-selection voltage. And a control circuit 5 for sending a scan signal to a scan electrode of one of the liquid crystal panels 3 for changing the scan electrode selection voltage. A variation detecting circuit 6 for detecting, 1
For each scan electrode drive time, a correction parameter generation circuit 7 that measures the ratio of light and dark of data displayed on the selected scan electrode to generate a correction parameter, and generates a correction voltage having a magnitude corresponding to the correction parameter. A correction voltage generation circuit 8, a voltage addition circuit 9 for adding the correction voltage to the scan voltage when the power supply circuit 4 is selected, and a variation amount after the addition of the correction voltage in the scan electrode provided with the variation amount detection circuit 6. And a correction voltage correction circuit 10 for correcting the magnitude of each correction voltage.

FIG. 1B shows the principle configuration of the device according to the second embodiment of the present invention. The device of the second embodiment is a driving device of a simple matrix type liquid crystal panel 3 provided with a data electrode driver 1 and a scan electrode driver 2.
A power supply circuit 4 for applying selection and non-selection voltages, and data electrodes and scan electrodes provided on the liquid crystal panel 3 are driven by a voltage averaging method using a voltage supplied from the power supply circuit 4. A control circuit 5 for sending a data signal to the data electrode driver 1 and a scan signal to the scan electrode driver 2, a detection electrode 11 provided outside the display area of the liquid crystal panel 3 so as to intersect with the data electrode,
A detection electrode drive circuit 12 for applying the same voltage as the selection voltage to the detection electrode 11 at predetermined time intervals outside the display operation of the scan electrode driver 3;
For each scan electrode drive time, the correction parameter is generated by measuring the light / dark ratio of the data displayed on the selected scan electrode, and the correction parameter is generated by setting the data signal to a predetermined pattern when the detection electrode drive circuit 12 operates. And a correction voltage generating circuit 8 for generating a correction voltage having a magnitude corresponding to the correction parameter.
A voltage adding circuit 9 for adding the correction voltage to the scan voltage when the power supply circuit 4 is selected; and a fluctuation amount after addition of the correction voltage at the detection electrode 11 provided with the fluctuation amount detection circuit 6 to detect each correction. Correction voltage correction circuit that corrects the magnitude of voltage
Consists of 10 and 10.

[Action]

According to the present invention, the amount of voltage level variation of the liquid crystal cell applied waveform depending on the display pattern for each line is obtained from the display pattern, and the power supply circuit increases the effective voltage of the cell applied waveform when there are many "bright" displays. Is corrected. In the scan electrode to which the fluctuation amount detection circuit is connected, the voltage fluctuation amount of the scan electrode after the correction control of the power supply circuit is periodically detected, and the selected voltage level of the scan electrode is corrected according to the fluctuation amount. . As a result, the correction voltage is automatically corrected to an appropriate value even if there is a change in a display pattern, a difference between individual liquid crystal panels, a change in temperature, a change with time, or the like.
Fluctuations in the selection voltage level of the scan electrode are eliminated, and luminance unevenness is suppressed with high manufacturability and maintainability.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a circuit diagram showing a configuration of an embodiment of a liquid crystal panel driving device embodying the present invention. In the figure, a data electrode driver (X driver) 21 is applied to a data electrode of a liquid crystal panel 23, and a scan electrode driver (Y driver) is applied to a scan electrode.
Drivers) 22 are connected respectively.

Reference numeral 24 denotes a power supply circuit which divides between two electrodes V _CC and V _EE by a plurality of resistors to generate voltages V _{1 to} V ₆ . Voltage
V ₁ ~V ₆ is the voltage needed to perform the voltage averaging method described in Figure 9, its value _{is, V 1 = V V 4 =} (2 / a) V V 2 = (1-1 / a) is a _{V V 5 = (1 / a} ) V V 3 = (1-2 / a) V V 6 = 0 ( where, a is a number determined by the duty ratio.) Then, the data electrode driver 21 Are supplied with voltages V ₁ , V ₃ , V ₄ , V ₆ from the power supply circuit 24, and the scan electrode driver 22 receives the voltages V ₁ , V ₂ , V ₂ from the power supply circuit 24 through a correction voltage addition circuit 29 described later. _5, the potentials of V ₆ is provided. A liquid crystal panel controller 26 is connected to the data electrode driver 21 and the scan electrode driver 22. The liquid crystal panel control device 26 transmits X data XDATA and Y data YDATA, which are liquid crystal panel display data, to the data electrode driver 21 and the scan electrode driver 22 in response to a command from a limiting device such as a personal computer 25. , And a polarity switching signal DF for switching between the positive voltage application mode period and the negative voltage application mode period (hereafter, an example in which switching is performed for each frame will be described). Is to give.

The data electrode driver 21 and the scan electrode driver 22 receive X data XDATA from the liquid crystal panel controller 26,
Each data electrode of the liquid crystal panel 23 according to the Y data YDATA,
And the aforementioned voltage V ₁ from the power supply circuit 24 to each scan electrode.
Providing by selecting one of ~V _6. That is, during the positive voltage application mode, the data electrode driver 21 outputs the X data XD
V is applied to the data electrode selected based on the ATA, and (1-2 / a) V is applied to the unselected data electrode. The scan electrode driver 22 selects the scan electrode selected based on the Y data YDATA. 0 for non-selected scan electrodes (1
−1 / a) Apply V.

Similarly, during the negative voltage application mode, the data electrode driver 21 applies 0 to the data electrode selected based on the X data XDATA, applies (2 / a) V to the non-selected data electrode, The driver 22 applies V to selected scan electrodes and (1 / a) V to unselected scan electrodes based on the Y data YDATA.

In this embodiment, in addition to the above configuration, a correction parameter generation circuit 27, a D / A conversion circuit 28, a correction voltage addition circuit 29, a fluctuation detection circuit 30, and a correction voltage correction circuit 31 are provided. Have been.

The correction parameter generation circuit 27 has a data clock signal
A data latch circuit that captures X data XDATA in synchronization with DCLK, and a data detection circuit that detects “on” data from the output of data latch circuit 271 and data clock signal DCLK
272 and a counter 273 that receives the output of the data detection circuit 272 and determines the number of “ON” data.
A scan synchronization signal SSYNC for synchronizing scan electrode driving is connected to the initialization input RST of the counter 273, and the counter 273 is reset and set to an initial state every scan drive period.

The D / A conversion circuit 28 generates a correction voltage, and converts a digital count result output from the counter 273 into a voltage value corresponding to the digital count result. The correction voltage addition circuit 29 to the scan electrode selection voltage V ₁ and the scan electrode selection voltage V ₆ from the power supply circuit 24, which adds the correction voltage generated by the D / A conversion circuit 28, the scan electrode selection voltage
an adding circuit 291 that adds the correction voltage to v _{1 as} it is, an inverting circuit 292 that inverts the correction voltage, and a scan electrode selection voltage V
_And an addition circuit 293 for adding the inverted correction voltage to ₆ .

Further, in this embodiment, the fluctuation detecting circuit 30 is connected to both ends of the scan electrode 231 farthest from the data electrode driver 21, and the fluctuation of the voltage at both ends after the selection voltage is corrected by the correction voltage adding circuit 29. The amount (voltage drop) is detected. The detection output of the fluctuation amount detection circuit 30 is input to a correction voltage correction circuit 31, and when the fluctuation amount is out of a specified value range, an output for correcting the correction voltage is output from the correction amount voltage correction circuit 31 to the D / A conversion circuit 28. Is output to

Next, the operations of the correction parameter generation circuit 27, the D / A conversion circuit 28, the correction voltage addition circuit 29, the variation detection circuit 30, and the correction voltage correction circuit 31 configured as described above will be described.

X data XDATA output from the liquid crystal panel controller 26
Is sent to the data electrode driver 21 at the same time as the data latch circuit 27 therein by the correction parameter generation circuit 27.
It is fetched to 1 in synchronization with the data clock signal DCLK and output immediately after latching. Then, the data detection circuit 272
At the same time, the logical product of the output of the data latch circuit 271 and the data clock signal DCLK is obtained, so that the X data XD
Only when ATA is “ON” is the pulse detected by the data detection circuit 272
Output from A scan synchronization signal SSYNC for synchronizing scan electrode driving is input to an initialization input RST of the counter 273 to which this output is input, and the counter 273 is reset every one scan driving period. Then, X data XDATA in one scan drive period
The number of “ON” in the count is counted by the number of rising or falling edges of the pulse output from the data detection circuit 272, and the result is output as a correction parameter.

This correction parameter output is converted into a voltage by a D / A conversion circuit 28, which is a subsequent correction voltage generation circuit, and output as a correction voltage. This correction voltage is applied to a correction voltage addition circuit.
Is directly input to the adder 291 in the 29, the scan electrode selection voltages V ₁ is corrected. Also, this correction voltage is
292 is inverted is input to the addition circuit 293 through the scan electrode selection voltage V ₆ in the opposite direction is corrected to the correction of the scan electrode selection voltage V _1. This correction voltage is the X data XDATA
The value becomes larger as the number of “on” in the inside increases.

FIG. 3 shows scan voltage waveforms when a large number of “dark” and a large number of “bright” are displayed. Third
FIG. 7A shows the operation waveform of the scan voltage when there are many "dark" displays. At this time, since the correction voltage hardly occurs, the maximum value of the scan electrode selection voltage is V and the minimum value is 0.
The waveform is the same as before. On the other hand, as shown in FIG. 3 (b), when the "bright" display is large, a large correction voltage is generated, so that the maximum value of the scan electrode selection voltage is larger than V and the minimum value is smaller than 0. . FIG. 3 (c) shows a change in voltage at each position of the scan electrode according to the present invention as compared with the conventional one. Conventionally, there are many "dark" indications on the side far from the power supply of the scan electrode and "bright"
Although the potential difference when the display is large was large, it can be seen that the potential difference on the side far from the power supply of the scan electrode is not so different between the case where there are many "dark" displays and the case where there are many "bright" displays in the present invention.

As described above, the driving waveform of the conventional scan electrode does not change when there are many "dark" displays, and the voltage at the time of selecting the scan electrodes changes compared to the conventional case when there are many "bright" displays. Then, as "bright" is displayed more, the scan selection voltage is corrected in a direction to increase the effective voltage, so that there is no drop in the cell drive voltage at this time, and the effective voltage is reduced because "bright" is displayed. Therefore, a high quality display can be obtained.

However, even if the voltage during the selection period of the scan electrode is corrected as described above, the correction amount may not be appropriate due to a difference in liquid crystal material, a difference in panel temperature, or a change with time of the liquid crystal panel. Thus, in the embodiment of FIG. 2, the voltage at both ends of the scan electrode 231 farthest from the data electrode driver 21 is measured by the fluctuation amount detection circuit 30. This measurement may be performed for each frame, but may be performed at appropriate time intervals to observe a change in temperature or a change with time.

Being determined by the variation detecting circuit 30 is a potential difference Vd of the scan electrodes at both ends in FIG. 3 (c), the maximum value V _max is when performing the display "bright" all one line Vα
_W -Buiganma, the minimum value V _min is Vα _B -Vβ when the "dark" display was performed on all one line, the different values of the potential difference Vd measured by the display pattern. Therefore, in the embodiment of FIG. 2, the correction voltage correction circuit 31 previously stores a standard potential difference Vd between both ends of the scan electrode according to the display pattern,
When the selection voltage of the scan electrode corrected by the D / A converter 28 is different from the potential difference Vd between both ends of the standard scan electrode, the correction voltage correction circuit 31 performs the subsequent D / A converter 28.
, Correct all the correction voltages for each scan electrode.

In this way, even if there is a difference in liquid crystal material, a change in panel temperature, or a change in the liquid crystal panel over time, the correction amount of the scan voltage is always appropriately corrected. As a result, the correction voltage is automatically corrected to an appropriate value even if there is a change in a display pattern, a difference between individual liquid crystal panels, a change in temperature, a change with time, etc., so that there is no change in the selection voltage level of the scan electrode. Brightness is suppressed by high manufacturability and maintainability.

In the above-described embodiment, the display pattern is detected, and the selection voltage of the scan electrode is corrected to a voltage having a higher “dark” display. However, the voltage may be corrected to a voltage having a higher “bright” display. Good thing. In addition, the correction of the selection voltage of the scan electrode is not performed when the number of “bright” and “dark” of the display pattern is the same, and when the number of “bright” displays is large, the effective voltage is increased.
When there are many "dark" displays, the effective voltage may be reduced. In this case, as shown in FIG. 4, the correction parameter generation circuit 57 may be constituted by the data latch circuit 271 and the up / down counter 571.

FIG. 5 shows a configuration of a correction parameter generation circuit 67 of another embodiment of the correction parameter generation circuit 27 of FIG. The apparatus of this embodiment includes a coordinate measuring circuit 671 that counts the X data DCLK and outputs the X coordinate of the data, a weighting circuit 672 that receives the output and outputs a value weighted by the coordinates, A control buffer 673 that outputs the value from the weighting circuit 672 based on the output from the data latch circuit 271 when the X data XDATA contains “ON” data, and an integrating circuit that integrates this output during one scan driving period 674
Is provided.

The difference between this device and the device of Fig. 2 is that X data XDAT
Even if the same “ON” data exists in A, the “ON” data displayed on the scan electrode closer to the power supply circuit 24 is counted as a small value and displayed on the scan electrode farther from the power supply circuit 24 The "on" data is counted as a large value. This has a small effect on the voltage drop of the "bright" display scan electrode of the liquid crystal cell connected to the scan electrode closer to the power supply circuit 24.
"Akira" of the liquid crystal cell connected to the scan electrode far away from 24
This is because the influence on the voltage drop of the scan electrode for display is large. With this device, it is possible to cope with a phenomenon in which the amount of change in the scan selection voltage varies depending on the position where “bright” is displayed on the same scan electrode, and more appropriate correction can be performed.

FIG. 6 shows the configuration of a liquid crystal panel driving device according to a second embodiment of the present invention. The same components as those in the embodiment of FIG. 2 are denoted by the same reference numerals and description thereof is omitted. Only components different from those of the embodiment shown in FIG. 2 will be described. In this embodiment, a detection electrode 232 is provided at the end of the liquid crystal panel 23 farthest from the data electrode driver 21 so as to cross each data electrode. The detecting electrode 232 is not connected to the scan electrode driver 22 is connected to the detection electrode driver 32 provided for selectively applying voltages V ₁ or V ₆ only on the detection electrode 232 by the synchronous signal . Accordingly, the detection electrode driver 32 is supplied with the potentials of the voltages V ₁ and V ₆ and the polarity switching signal DF from the power supply circuit 24.
Further, both ends of the detection electrode 232 are connected to the variation detection circuit 30.

In this embodiment, the X data XDATA given from the liquid crystal panel control device 26 to the data electrode driver 21 is given to the data electrode driver 21 via the data conversion circuit 33. The data conversion circuit 33 supplies all “bright” data or all “dark” data to the data electrode driver 21 according to a synchronization signal from the synchronization signal generation circuit. The synchronizing signal generation circuit 34 has Y data YDATA given to the scan electrode driver 22 from the liquid crystal panel controller 26.
Then, a time signal TIME from the computer 25 is given.
The time signal TIME is periodically supplied from the computer to the synchronization signal generation circuit 34, and the synchronization signal generation circuit 34
TIME, Y data YDAT from LCD panel controller 26
A synchronization signal is supplied to the data conversion circuit 33, the detection electrode driver 32, and the variation detection circuit 30 during a period in which there is no A (return period of the television signal).

Next, the operation of the second embodiment configured as described above will be described. Correction according to the display pattern of the applied voltage in the selection period of the positive voltage application mode period and the negative voltage application mode period of the scan electrode is not performed. It is exactly the same as the circuit of the embodiment of FIG. When the time signal TIME is periodically supplied from the computer 25 to the synchronization signal generation circuit 34, the synchronization signal generation circuit
34 generates a synchronizing signal in a period in which there is no Y data YDATA from the liquid crystal panel control device 26 by the time signal TIME, and this synchronizing signal is given to the data conversion circuit 33, the detection electrode driver 32, and the variation detection circuit 30. .

The synchronization signal causes the data conversion circuit 33 to
Data in which the display on 232 is all “bright” is sent to the data electrode driver 21. On the other hand, the detecting electrode 232 in response to the synchronizing signal, for example, the same voltage V ₆ and the selection voltage at the positive voltage application mode period is applied from the detection electrode driver 32, the variation detecting circuit 30 in the "bright" display state The voltage drop across the detection electrode 232 is measured, and the measured value is sent to the correction voltage correction circuit 31. Correction voltage correction circuit
31 stores a standard voltage drop value at the time of "bright" display, and when the measured value by the fluctuation detecting circuit 30 has a difference from this value, D is set so that the measured value matches the standard value. / A conversion circuit 2
A correction signal is sent to 8.

Note that the detection electrode 232 must also be driven with a voltage between the positive voltage application mode period and the negative voltage application mode period to prevent deterioration. the selection voltage in the application mode period and the same voltage V ₆ selected voltages V ₁ in the negative voltage application mode period, so as to alternately applying two consecutive frames depending on the polarity switching signal DF, the correction voltage modification circuit 31
May be obtained by averaging the voltage drop value during the positive voltage application mode period and the voltage drop value during the negative voltage application mode period.

Further, in the embodiment of FIG. 6, the synchronizing signal is generated during the period when there is no Y data YDATA, but the Y data YDAT
A may generate a synchronization signal during a certain period.
In this case, data to be displayed on any one of the lines is converted into all “bright” data or all “dark” data by the data conversion circuit 33, and detection is performed from the detection electrode 232.

Further, in the embodiment shown in FIG.
V ₁ and V ₆ are connected, but the detection electrode 232 was driven only by V ₁ or V _6, a non-selection voltage V ₂ of the further positive voltage application mode period to the detection electrode driver 32, the negative voltage application mode period connect the non-selection voltage V ₅ of the one in which may be applied in accordance with the non-selective voltage V ₂ or V ₅ is not a period of the synchronization signal to the polarity switching vibration DF.

FIG. 7 shows the configuration of a liquid crystal panel driving device according to a third embodiment of the present invention. The same components as those in the embodiment of FIG. 6 are denoted by the same reference numerals and description thereof is omitted. Only the components different from the embodiment of FIG. 6 will be described. This embodiment differs from the embodiment of FIG.
The difference is that the detection electrode 232 in the figure is shared with the scan electrode 233 at the end farthest from the data electrode driver 21 of the liquid crystal panel 23. Therefore, an OR circuit 35 is provided between the scan electrode 233 and the scan electrode driver 22.
The output of the OR circuit 35 is connected to one end of the scan electrode 30,
One input of the circuit 35 is connected to the scan electrode driver 22, and the other input is connected to the detection electrode driver 32 and the variation detection circuit.
Connected to 30. The other end of the detection electrode 233 is also connected to the fluctuation amount detection circuit 30.

In the third embodiment configured as described above, the correction according to the display pattern of the applied voltage during the positive and negative selection periods of the scan electrode is exactly the same as the circuit of the embodiment of FIG. The scan electrode 233 is connected to the scan electrode driver 22.
Accordingly, during the display period, the display is driven and driven like the other scan electrodes.

By the periodic time signal TIME from the computer 25,
The synchronizing signal generation circuit 34 generates a synchronizing signal during a period in which there is no Y data YDATA from the liquid crystal panel control device 26, that is, during a retrace period. The data which is supplied to the data electrode driver 21 is sent to the data electrode driver 21 from the data conversion circuit 33 as in the embodiment of FIG. The voltage drop across the detection electrode 233 in the “Bright” display state is measured, and a correction signal is sent from the correction voltage correction circuit 31 to the D / A conversion circuit 28 based on the measured value.

In the embodiment of FIG. 7, the detection electrode 233 is the scan electrode at the end farthest from the data electrode driver 21 of the liquid crystal panel 23. However, the position of the detection electrode is along the scan electrode, and Any position on the liquid crystal panel 23 may be provided as long as the position intersects with.

Further, in the embodiment shown in FIG. 7, the synchronizing signal is generated during the period when there is no Y data YDATA, but the Y data YDAT
A may generate a synchronization signal during a certain period.
In this case, the data to be displayed on the detection electrode 233 is converted into all “bright” data or all “dark” data by the data conversion circuit 33, and detection is performed from the detection electrode 232.

Further, in the above embodiment, the bias ratio a was set to a theoretical optimum value. (However, D is a duty ratio). This method is disclosed in JP-A-59-160124, and has an effect of improving the contrast ratio in addition to the effect of reducing the driving voltage described in the publication. However, if this method is used simply, the drive margin becomes narrow, so that the transmittance greatly changes due to a slight change in the effective voltage, and there is a problem that crosstalk is likely to occur. Therefore, by suppressing the fluctuation of the effective voltage due to the display pattern by combining the present invention, the drive voltage can be reduced without the problem of crosstalk,
In addition, the contrast ratio can be improved.

Incidentally, in the illustrated _{embodiment, V 1 = V V 4 =} (2 / a) V V 2 = (1-1 / a) V V 5 = (1 / a) V V 3 = (1-2 / a ) it was a V V ₆ = 0, the difference of each voltage is the voltage averaging method has only to satisfy this relationship, a high V ₁ ~V ₆ by a predetermined voltage value, or may be lower.

In the above description, “ON” display data is “bright”.
In the embodiment, the liquid crystal display device corresponding to the display is described. However, in the liquid crystal display device corresponding to the “on” display data, the “dark” display corresponds to the “dark” display, and the “dark” display corresponds to the “dark” display. The same applies to the case where the display is read as "bright".

〔The invention's effect〕

As described above, according to the present invention, in a simple matrix type liquid crystal display device, “light”
Even if a large number of display is performed, the scan electrode selection voltage does not decrease and the occurrence of uneven brightness can be suppressed including the individual difference of the liquid crystal panel, the temperature difference, and the change with time, and the display quality can be improved. There is an effect that can be.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of the configuration of a liquid crystal display device according to the present invention, FIG. 2 is a circuit diagram showing the configuration of an embodiment of the liquid crystal display device according to the present invention, and FIG. FIG. 4 is a waveform diagram showing voltage waveforms showing the effects when there are many "dark" displays and when there are many "bright" displays. FIG. 4 is a circuit configuration of another embodiment of the correction parameter generating circuit shown in FIG. FIG. 5, FIG. 5 is a circuit configuration diagram of still another embodiment of the correction parameter generation circuit of FIG. 2, FIG. 6 is a circuit diagram showing a configuration of a second embodiment of the liquid crystal panel driving device of the present invention, FIG. 7 is a circuit diagram showing the configuration of a third embodiment of the liquid crystal panel driving device of the present invention, FIG. 8 is a diagram showing driving voltage waveforms of cells α and β in FIG. 9, and FIG. FIG. 10 shows an example of a display pattern on a panel, FIG. 10 shows a voltage averaging method, and FIG. 11 shows another display pattern on a liquid crystal panel. FIG. 12 is an explanatory diagram showing a transmission circuit and a current flowing through a liquid crystal cell connected to one scan electrode. FIG. 13 is a waveform diagram showing a change in scan voltage according to the display pattern shown in FIG. FIGS. 14 and 15 are diagrams showing driving waveforms of the liquid crystal cell when a large number of "bright" and a large number of "dark" are displayed. 21: Data electrode driver, 22: Scan electrode driver, 23: Liquid crystal panel, 24: Power supply circuit, 26: Liquid crystal panel control device, 27: Correction parameter generation circuit, 28: D / A conversion circuit 29 Correction voltage addition circuit 30 Change amount detection circuit 31 Correction voltage correction circuit 32 Detection voltage driver 33 Data conversion circuit 34 Synchronization signal generation circuit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisashi Yamaguchi 1015 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited (56) References JP-A-2-89 (JP, A) JP-A-63-220228 (JP, A) JP-A-1-29899 (JP, A) JP-A-2-61612 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02F 1/133 G09G 3 / 36

Claims (2)

(57) [Claims] 1. A driving device for a simple matrix type liquid crystal panel (3) comprising a data electrode driver (1) and a scan electrode driver (2), wherein the data electrode driver (1) is provided with bright and dark data voltages and scan electrodes. A power supply circuit (4) for applying a selection or non-selection voltage to the driver (2), and each data electrode and each scan electrode provided on the liquid crystal panel (3) use a voltage supplied from the power supply circuit (4). A control circuit (5) for sending a data signal to the data electrode driver (1) and a scan signal to the scan electrode driver (2) so as to be driven by the voltage averaging method; and a control circuit on one scan electrode of the liquid crystal panel (3). Provided in
A change amount detection circuit (6) for detecting a change amount of the scan electrode selection voltage; and a correction for generating a correction parameter by measuring a light / dark ratio of data displayed on the selected scan electrode for each scan electrode driving time. A parameter generation circuit (7), a correction voltage generation circuit (8) for generating a correction voltage of a magnitude corresponding to the correction parameter, and a voltage for adding the correction voltage to a scan voltage when the power supply circuit (4) is selected An adder circuit (9); a correction voltage correction circuit (10) for correcting the magnitude of each correction voltage according to the fluctuation amount after the correction voltage addition in the scan electrode provided with the fluctuation amount detection circuit (6); A driving device for a liquid crystal panel, comprising: 2. A driving device for a simple matrix type liquid crystal panel (3) comprising a data electrode driver (1) and a scan electrode driver (2), wherein the data electrode driver (1) includes a light / dark data voltage and a scan electrode. A power supply circuit (4) for applying a selection or non-selection voltage to the driver (2), and each data electrode and each scan electrode provided on the liquid crystal panel (3) use a voltage supplied from the power supply circuit (4). A control circuit (5) for sending a data signal to the data electrode driver (1) and a scan signal to the scan electrode driver (2) so as to be driven by the voltage averaging method. A detection electrode (11) provided to cross the data electrode; and a fluctuation amount detection circuit (6) connected to the detection electrode (11).
A detection electrode drive circuit (12) for applying the same voltage as the selection voltage to the detection electrode (11) at predetermined time intervals outside the display operation of the scan electrode driver (3); A correction parameter generation circuit that measures a light / dark ratio of data to be displayed on the scan electrode to generate a correction parameter, and generates a correction parameter with a data signal in a predetermined pattern when the detection electrode driving circuit (12) operates. (7), a correction voltage generating circuit (8) for generating a correction voltage having a magnitude corresponding to the correction parameter, and a voltage adding circuit (7) for adding the correction voltage to the scan voltage when the power supply circuit (4) is selected. 9) and a correction voltage correction circuit (11) that detects a fluctuation amount after the addition of the correction voltage in the detection electrode (11) provided with the fluctuation amount detection circuit (6) and corrects the magnitude of each correction voltage ( 10) A driving device for a liquid crystal panel, comprising: