JPH03274089A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To easily adjust a correction voltage without using a special jig by inverting and amplifying one correction voltage by taking an almost central voltage as reference. CONSTITUTION:An inversion amplifier circuit constituted of an arithmetic amplifier circuit 113 and fixed resistances 109 and 110 performs -one fold amplification because the resistance values of two fixed resistances 107 and 108 are equal. When a selection voltage VOU is inputted in the inversion amplifier circuit, a voltage obtained by multiplying the voltage VOU by -1 with reference to a central voltage is outputted to the circuit 113. The obtained voltage is taken as the correction voltage V5L of the selection voltage V5N. When a difference between the correction voltage VOU of the selection voltage and the selection voltage VON(this difference is taken as DELTAV) is changed by adjusting a semi-fixed resistance 111, a difference between the selection voltage V5N and the correction voltage V5L of the selection voltage, which are another pair, always becomes equal to DELTAV by interlocking with the change. Therefore, the semi-fixed resistance 111 is adjusted with a driver, etc., while viewing a display pattern where horizontal noise appears.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a driving circuit for a liquid crystal panel, and particularly to a power supply circuit that generates a voltage necessary for driving.

[Conventional technology]

Conventionally, power supply circuits that generate the multiple voltages necessary to drive a liquid crystal panel have a resistor divider circuit in which multiple resistors are connected in series between the highest voltage and the lowest voltage among the multiple voltages, and The power supply circuit was composed of a voltage follower circuit using an operational amplifier circuit that lowered the impedance of the divided voltage obtained by the circuit.

[Problem to be solved by the invention]

Here, the patent application proposed by the authors (patent Rr463-
159914), the selection voltage, non-selection voltage,
A liquid crystal display device that drives a liquid crystal panel by using a correction voltage for at least one of the lighting voltage and non-lighting voltage in place of at least one of the lighting voltage and non-lighting voltage has two sets of voltages to prevent DC voltage from being applied to the liquid crystal panel. The selection voltage, non-selection voltage, lighting voltage, non-lighting voltage, and at least one correction voltage are required for each of these voltages.

That is, one set of correction voltages for at least one of the selection voltage, non-selection voltage, lighting voltage, and non-lighting voltage is required, and the other set of correction voltages for that voltage are required. The difference between these two correction voltages and the corresponding voltage needs to be approximately equal. In addition, due to variations in the characteristics of each finished panel,
The correction voltage must be adjusted for each individual liquid crystal display device.

However, in the conventional circuit described above, it was difficult to set the two supplementary voltages to optimal values.

This will be explained using FIG.

Figure 2 shows the power supply circuit (
26 of Japanese Patent Application No. 63-159914).

In the figure, 101 to 105 are fixed resistors, 201 and 202 are semi-fixed resistors, and 112 is a voltage follower circuit using an operational amplifier circuit. Fixed resistors 101 to 1.05 and semi-fixed resistors 201 and 202 are connected in series to form a resistance divider circuit. Here, in the figure, VOU, VONSVl, v2
, V3, V4, V5N, and V5L are the voltages generated across each resistor, and VON, V4, V5, V3, and vOU are the selection voltage, non-selection voltage, lighting voltage, non-lighting voltage,
and a correction voltage for the selection voltage. Also, v5, vl, VO
1v2 and V5L are correction voltages for the selection voltage, non-selection voltage, lighting voltage, non-lighting voltage, and selection voltage of the other set.

The difference between these two correction voltages and their respective selection voltages is changed by adjusting the semi-fixed resistance.

The two sets of selection voltage, non-selection voltage, point-to-point voltage, and non-lighting voltage are outputted by the voltage follower circuit 112 with reduced impedance.

With the above configuration, semi-fixed resistors 201 and 20
2, the optimum correction voltage can be set by adjusting A jig or the like that can adjust the two semi-fixed resistors to match the voltage is required. Alternatively, the use of two semi-fixed resistors or the like may be considered, but problems such as tracking errors and increased size arise.

Furthermore, the authors proposed a patent application (Japanese Patent Application No. 1999).
-100683), when changing the correction voltage depending on the surrounding environmental temperature, two temperature sensors with the same characteristics are required to change the two correction voltages depending on the environmental temperature. there was.

As mentioned above, there is a problem in that it is difficult to optimize the supplementary iE voltage while equalizing the difference between the two compensation voltages and the corresponding voltage. This makes it possible to adjust the correction voltage. It also reduces the number of temperature sensors.

[Means to solve the problem]

That is, the liquid crystal display device of the present invention is a liquid crystal display device that drives a liquid crystal panel with a plurality of voltages, and includes a circuit that generates a voltage approximately at the center of the highest voltage and the lowest voltage among the plurality of voltages; At least one voltage higher or lower than the center voltage among the plurality of voltages is inverted and amplified with reference to the center voltage to obtain a voltage lower or higher than the center voltage among the plurality of voltages. The invention is characterized by comprising a circuit that generates at least one voltage.

[For production]

Since one of the correction voltages is inverted and amplified using the voltage at the center of the dot as a reference, when one correction voltage is changed, the other correction voltage also changes in conjunction.

〔Example〕

Example 1 The present invention will be further explained using an example. FIG. 1 is a circuit diagram showing the IM circuit of this embodiment. In the same figure, 1.01
110 is a fixed resistor, 111 is a semi-fixed resistor, and 112 is a voltage follower circuit using an operational amplifier circuit. 113
The operational amplifier circuit constitutes an inverting amplifier circuit with resistors 109 and 110.

The fixed resistors 101 to 106 and the semi-fixed resistor 111 are connected in series, a voltage is applied to both ends, and constitute a resistance divider circuit. Here, in the figure, vOUSVON, Vl,
V2, V3, v4, V 5 N it The voltages generated across each low resistance, VON, V4, v5, V3, VOU are one set of selection voltage, non-selection voltage, lighting voltage, non-lighting voltage, and selection voltage. This is the voltage correction voltage. Also, V5, ■1, V
O1 and 2 are the selection voltage, non-selection voltage, lighting voltage, and non-lighting voltage of the other set.

Here, the resistance values of the fixed resistors 101 to 105 are as follows: (usually takes a value of about 4 to 40).

Further, the resistance values of the semi-fixed resistor 111 and the fixed resistor 106 are approximately equal.

Furthermore, the fixed resistors 107 and 108 have the same value, and similarly, the fixed resistors 10 and 110 also have the same value.

The circuit configuration is as described above.

For this reason, fixed resistors 107 and 108 have the same resistance and a voltage is applied to both ends, so fixed resistor 107
At the connection point between and 108, there is a circuit tM that generates a voltage at the center of the voltages applied to both ends.

Then, an operational amplifier circuit 113 and fixed resistors 109 and 110
Since the resistance values of these two fixed resistors are equal, the inverting amplifier circuit composed of the following is amplified by a factor of 11. The reference voltage at this time (that is, the non-inverting input of the operational amplifier circuit 113) is the center voltage generated by the circuit that generates the above-mentioned center voltage.

Here, the voltage VOU can be arbitrarily set by adjusting the semi-fixed resistor 111. This voltage VOU is then input to the above-mentioned inverting amplifier circuit. That is, it is manually applied to the inverting input of the operational amplifier circuit 113 via the fixed resistor 109. Therefore, the operational amplifier circuit 113 outputs a voltage obtained by multiplying the voltage OU by 11 times the center voltage. This voltage is set as the correction voltage V5L of the selection voltage v5N.

By the above operation, when the selection voltage compensation i [the difference between the voltage VOU and the selection voltage VON (this difference is defined as △■) is changed by adjusting the semi-fixed resistor 111, the other The selection voltage V5N of the set and the correction voltage V5 of this voltage
The difference in L will always be equal to ΔV.

Therefore, without the need for a special jig, for example, while looking at the display pattern in which weft threads appear, use a screwdriver or the like to adjust the anti-fixed resistor 111.
It became possible to adjust.

In addition, in this embodiment, the correction voltage of the selection voltage necessary for correcting the sleeve for the "weft thread pulling mode" has been explained, but the correction voltage necessary for the correction for other thread pulling modes, for example, the correction i for the non-selected voltage v1, is explained. “Of course, when creating voltage,
A similar circuit can generate a correction voltage for the non-selection voltage V4, and has a similar effect.

Furthermore, it is also possible to generate voltages V5N, V4, and V3 from voltages VONSVl and V2 by a similar circuit.

The authors applied for the proposed patent (Japanese Patent Application No. 11006
Even when the correction voltage is changed depending on the surrounding environmental temperature as in No. 83), according to the present invention, even if one correction voltage changes depending on the environmental temperature, the other correction voltage is linked to this, so that one It is sufficient to provide a temperature sensor only in the circuit that generates the correction voltage of , and the number of temperature sensors can be reduced.

Note that although the above circuit generates a voltage lower than the center voltage from a voltage higher than the center voltage, conversely, a voltage higher than the center voltage may be generated from a voltage lower than the center voltage.

〔Effect of the invention〕

As mentioned above, by providing a circuit that generates a center voltage and an inverting amplifier circuit that multiplies the voltage by 11 times based on this center voltage, a center voltage is generated and the voltage is higher than this voltage. A voltage lower or higher than the center voltage can be generated from a voltage or a lower voltage, and the difference between the voltage higher or lower than the center voltage and this center voltage, and the difference between the center voltage and a voltage lower or higher than this center voltage. Since the differences can always be made equal, adjusting one voltage automatically changes the other voltage, making adjustment possible without the need for special jigs.

Furthermore, even if one voltage changes due to the temperature sensor, the other voltage changes by the same amount, so the number of temperature sensors can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of the present invention. FIG. 2 is a circuit diagram showing the configuration of the prior art. 101 to 110...Fixed resistance 111...Semi-fixed resistance 112...Voltage follower circuit based on operational amplifier circuit 113...More than operational amplifier circuit

Claims (1)

[Claims] (1) In a liquid crystal display device that drives a liquid crystal panel with a plurality of voltages, a circuit that generates a voltage approximately at the center of the highest voltage and the lowest voltage among the plurality of voltages; At least one voltage that is higher or lower than the center voltage is inverted and amplified with reference to the center voltage to generate at least one voltage that is lower or higher than the center voltage among the plurality of voltages. A liquid crystal display device characterized in that it is equipped with a circuit that allows