SE447519B - PROCEDURE AND DEVICE FOR DRIVING LCD DISPLAYS - Google Patents

Description

447 519 Q Said further object is achieved by means of a device according to the present invention, which is mainly characterized in that more than a number of display segments of the LCD type are each via a connection connectable to an AC voltage source and to a plurality of display segments intended for said plurality of display segments. common backplane, and that there are means to individually vary the alternating voltage for the optional pairwise display segments and backplane.

The invention is described below as a preferred embodiment, reference being made to the drawings, in which Fig. 1 shows a schematic perspective view of a display according to the invention, Fig. 2 shows voltage curves in known displays, and Fig. 3 shows voltage curves according to the invention.

The LCD display 1 schematically shown in Fig. 1 comprises a plurality of display segments 2, 3, which in a known manner have electrical connections 4, 5, which are arranged to be able to be connected to a suitable so-called backplane 6 in order to enable a voltage to be applied between the respective pair segments. and backplane 2, 6; 3, 6 via an electrical connection going to the backplane 6. According to the invention, a backplane 6 common to a plurality of segments 2, 3 can be connected in pairs, and to enable the backplane 6 and the segments 2, 3 to be applied and operated individually with variable alternating voltage, as shown in Fig. 3, in order to achieve the desired color shade and / or grayscale of the LCD display segments 2, 3 in question. In this case, the backplane 6 common to a plurality of segments 2, 3 is connected to a constant reference level. U6 regarding the voltage, for example 5 volts, and in doing so you can select this reference level freely within a large range. The zero crossings for the respective alternating voltages, the oscillations of which may have, for example, a curved shape or so-called square shape, are arranged to lie substantially at said reference level U6, in contrast to the prior art, as shown in Fig. 2 in the form of curves for an example. B) oscillate from a zero level, for example 0 volts, to the desired voltage level while allowing the voltage for the respective segments S1 and S2 to oscillate between desired values, for example between 1 and 4 volts and 2 and 3 volts, respectively, to obtain 3 447 519 of potential difference between the respective back plane and segment and to achieve shade change of the display with, among other things, degradation of the LCD liquid, as a negative result.

Great freedom is now obtained thanks to the invention to set the reference level to the desired level, as shown in Fig. 3 of the drawings, and that a single common backplane 6 intended for a plurality of segments 2, 3 is made possible.

By, for example, applying voltages U2 and U3 of different values, for example that it varies between 4 and 6 volts and between 2 and 8 volts for the respective segments 2 and 3, respectively, so that the potential difference between the paired segments and the backplane 2-6 and 3-6, respectively. it is intended, for example 1 volt and 3 volts, respectively, so that the liquid of the respective LCD display is influenced to transmit light to varying degrees with the possibility of achieving any desired shade and / or grass scale of the respective display segments 2, 3. .

Means are provided in the intended device according to the invention for individually varying the alternating voltage for the respective optional display segments 2, 3 and backplane 6, and may be known ones, in order to enable a certain amplitude of the driving voltage to be achieved so that each individual LCD segments can be activated at the desired time. Thus, when the voltage is reduced from the intended selected reference level, the density of the segments 2, 3 in question decreases, which means that it fades.

A further technical effect, which is made possible thanks to the invention, is that it is possible to apply different frequencies for the segments 2, 3, as also appears from Fig. 3, whereby means are available for this.

The invention is not limited to the exemplary embodiment described above and shown in the drawings, but can be varied within the scope of the claims without departing from the spirit of the invention.

Claims (4)

447 519 P a t e n t k r a v Method for operating LCD displays, which comprise more than one number of display segments (2, 3), which are electrically connectable to a number of so-called backplanes (6) and between the respective paired segments and backplane (2-Q; 3-6) is arranged to be applied a voltage, in order to achieve the desired color shade and / or grayscale of the display, characterized by V, that a common backplane for more than a number of LCD segments (2, 3) is connected (6) to a reference level (U6) and allows the segments (2, 3) to be driven individually with variable alternating voltages, the zero crossings of which are substantially at the reference level. Method according to Claim 1, characterized in that different frequencies are applied at the same time for the segments in question (2, 3). Device for carrying out a method according to one of the preceding claims, characterized in that more than a number of display segments (2, 3) of the LCD type can each be connected via a connection (4, 5; 7) to a alternating voltage source and with a common backplane (6) intended for the said plurality of display segments (2, 3), and that means are available for individually varying the alternating voltage for the optional pairwise display segments and backplane (2-6; 3-6). Device according to claim 3, characterized in that means are provided for varying at one and the same time the frequency of the voltages of the segments (2, 3).