JPS62182714A - System for driving liquid crystal display device - Google Patents

Abstract

PURPOSE:To facilitate adjusting the contrast of a fixed pattern display part independently of a high time division driven display part with respect to software by changing contents of a memory to adjust the time when a voltage is impressed to a liquid crystal layer. CONSTITUTION:All of data stored in memories M1, M2...Mn of a data memory 7 are not '1', but '1' is stored in a half of these memories and '0' is stored in the other half. Then, a selecting signal V0 or '0' is outputted for memory parts where data '1' is stored, and a non-selecting signal V2 or V3 is outputted for memory parts where data '0' is stored, and a voltage (f) is impressed between a common electrode and segment electrodes of the liquid crystal. In this case, an effective voltage is V3/2. As the result, the contrast of only the fixed pattern part of a fixed pattern display part 2 is adjusted without changing the value of the liquid crystal driving voltage V0.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a driving method for a liquid crystal display device, and in particular to a driving method suitable for contrast adjustment of a liquid crystal display device having a time-division drive display section and a static drive display section. This is related to the method.

[Background of the invention]

A method for displaying letters, numbers, and figures using a liquid crystal display device is a dot matrix type display, in which intersections of striped electrodes are selected as appropriate, and letters, numbers, and figures are displayed using a combination of the intersections. For example, when limited to numbers only, a segment type display (Japanese Patent Publication No. 14360/1983) displays numbers from 0 to 9 by appropriately selecting seven segment-shaped electrodes arranged in a Japanese character shape; When it is necessary to always display the same characters, numbers, or figures, fixed pattern displays, etc., are used in which electrodes are formed in the shape of the letters, numbers, or figures, and a voltage is applied to the electrodes at any time to display the display. be.

Recently, as the uses and display contents of liquid crystal display devices have diversified, one liquid crystal display surface of a liquid crystal display device, that is, a liquid crystal panel, has a combination of the dot matrix type display and the segment type display, and the dot matrix type IJ lux display. It has become necessary to perform a display by a combination of the segment type display and the fixed pattern display, or a combination of the segment type display and the fixed pattern type display.

Generally, the intensity of transmitted light through a liquid crystal layer is determined depending on the effective value of the voltage applied to the liquid crystal layer.

The voltage averaging method is the most common IJ Lux dynamic method, but the voltage averaging method is selected as a method to obtain the maximum operating margin and high display quality for the number of time divisions N (N = number of scanning electrodes). The voltages alternately applied to the selected signal electrodes are Vlxl, V112, and the voltages alternately applied to the unselected signal electrodes are Vs21. V122, the voltage applied alternately to the selected scan electrodes is set to V211. V212
, Vux is the voltage applied alternately to the unselected scan electrodes.
.

V222, the amplitude of the AC voltage applied to the picture element in the selected state is vo1, an arbitrary constant is a (breath>1), and v111?
-Vo KatsuVoz) -Vo (7) Condition f, Vllll,
V112m &
When set arbitrarily, V121 = Vllll -1-Vo
(11V211 = Vltt -1-Vo
f21V221 = Vllll -) - Vo
(31 凰V122 = V112-Vo (41
V212 = V112- Vo
(51V222 = V112- Vo
(5) It is common practice to drive under conditions that satisfy the system (
Special Publication No. 57-57718). This driving method is explained below/
This is called a bias drive method. At this time, the effective voltage value V@t, Vat at the aforementioned selection point and half-selection point is expressed by the following equation when the number of scanning lines is N, and remains constant even if the display pattern changes.

It can be seen from equations (8) and (9) that the larger the time division number N becomes, the smaller the contrast between the lit point and the non-lit point becomes.

Therefore, in a liquid crystal display device that has a time division drive display section that performs dot matrix display and a static drive display section that performs fixed pattern display on the same liquid crystal panel surface,
Since the contrast in the IJx display section and the contrast in the statically driven fixed pattern display section are significantly different, there is a problem in that the quality of the displayed image is degraded.

Furthermore, if the time division drive circuit and the static drive circuit are configured as the same drive circuit, the contrast of only the static display section cannot be adjusted independently, and the drive 8 voltage of the high time division drive display section fluctuates at the same time. There was a drawback.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a liquid crystal display device that can display images with the same contrast in a high time division drive display section and a static drive display section. The objective is to provide a driving method.

[Summary of the invention]

In order to achieve such an object, the present invention drives a time-division drive display section and a static drive display section using the same drive circuit, and also stores the pulse width of the drive voltage applied to the static display section as display data. It is controlled by data stored in memory.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a driving method for a liquid crystal display device l according to the present invention. In the figure, 1 is a dot matrix display section, 2 is MIN, TYP.

A fixed pattern display section 3 displays a fixed pattern such as MAX, and a power supply circuit 3 generates a plurality of voltages having different values for driving the dot matrix display section 1 and the fixed pattern display section 2. are generated from the power supply voltage Vo by each of the five resistance elements R1. Reference numeral 4 denotes a drive circuit which inputs the power supply voltage VO20 and divided voltages Vl and V4 supplied from the power supply circuit 3 and outputs them selectively in order to gradually scan the common electrode 2 of the dot matrix display section 1; 5, a power supply circuit; The partial pressure supplied from V2. A static drive circuit inputs V3, selects it according to the fixed pattern to be displayed, and outputs the common of the fixed pattern display section 2 to the pole 22. 6 is a power supply voltage Vo, Q, and a divided voltage supplied from the power supply circuit 3. Voltage V2. Data ``1'' is input from the data memory which will be described later by inputting V3.
' for voltage vO or 0. The divided voltage v2 or V3 for the data "On" is selected by the alternating current signal M for inverting the polarity of the voltage applied to the liquid crystal layer, and the segment electrodes 23 of the dot matrix display section 1 and the fixed pattern display section Segment drive circuit outputs to each segment electrode 24 of 2, γ is a memory consisting of data ゛°1'' @011 corresponding to the pattern to be displayed l)M
The contents of I, Mz...Mn are sent to the segment drive circuit 6.
This is a data memory that sequentially outputs to the input terminal of
, M2 . . . Mn corresponds to the number n of time divisions of the segment electrodes of the dot matrix display section 1.

In such a configuration, for example, only the fixed pattern rMINJ2a in FIG. 1 is lit, and the other fixed patterns rT
A case will be described below using an example in which YPJ 2b and rMAXJ 2e are not lit.

Also in the fixed pattern display section 2, the fixed pattern a display section 2 tv
Common drive signals v2 and v3 as shown in FIG. 2(a) are applied alternately to the common electrode 22 from the static drive circuit 5. On the other hand, segment drive signals vO90 as shown in FIG. 2(b) are applied to the segment electrodes 24 of the fixed pattern display section 2 from the segment drive circuit 6, respectively. It is applied in response to V3. Then, by writing all @1 data in the A part of the memo IJMI, M2...Mn of the data memory T, and all "0" data in the B part and 0 part, a fixed pattern is displayed. The display pattern of only rMINJ2a is statically displayed in section 2. In this case, the voltage shown in (d) of the same figure is applied between the common electrode and the segment electrode of the liquid crystal, so the effective voltage is Next, data memory γ
Memo IJMI, M2...Mn, do not put all the data in each memory '1#, for example, only half "
1'' and the rest are 0#, the memory part containing the data ``'1#'' in the same figure (b
), the selection voltage VO or 0 is output in the same way, but the non-selection voltage V2 or v3 is output for the part containing data ``0'' as shown in the same figure (・), and the liquid crystal display The same figure (
A voltage as shown in f) is applied.

The effective voltage in this case is v3/2.

According to such a driving method, the memo IJMI, M2...
By changing the number of data "1"s input into Mn, the output time of the selection voltage can be changed, and the effective voltage can also be changed in multiple stages.

As a result, the contrast of only the fixed pattern portion of the fixed pattern display section 2 can be adjusted without changing the value of the liquid crystal drive voltage vO.

〔Effect of the invention〕

As explained above, according to the present invention, by changing the memory contents and adjusting the voltage application time applied to the liquid crystal layer, it is possible to add a new circuit and simplify the liquid crystal display device. be.

[Brief explanation of drawings]

FIG. 1 is a driving circuit diagram for explaining one embodiment of a method of driving a liquid crystal display device according to the present invention, and FIG. 2 is a voltage waveform diagram thereof. 1...φ dot matrix display section, 2...fixed pattern display section, 3...@power supply circuit, 4...common drive circuit for dot matrix, 5...static drive circuit, 6 ...Segment drive circuit, T...
...Data memory. Agent: Patent Attorney Katsoo OgawaFigure 2

Claims (1)

[Claims] A dot matrix display section driven in time division, a fixed pattern display section driven statically, a segment drive circuit that drives the dot matrix display section and fixed pattern display section with the same signal, and a display corresponding to the number of time divisions. 1. A driving method for a liquid crystal display device, comprising a data memory for storing data, and controlling a voltage pulse width from the segment driving circuit applied to a fixed pattern display section using the display data.