CA1132734A - Liquid-crystal display device - Google Patents
Liquid-crystal display deviceInfo
- Publication number
- CA1132734A CA1132734A CA318,932A CA318932A CA1132734A CA 1132734 A CA1132734 A CA 1132734A CA 318932 A CA318932 A CA 318932A CA 1132734 A CA1132734 A CA 1132734A
- Authority
- CA
- Canada
- Prior art keywords
- group
- voltage
- actuation
- connections
- electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
- G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
- G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
- G09F9/35—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements being liquid crystals
-
- G—PHYSICS
- G04—HOROLOGY
- G04G—ELECTRONIC TIME-PIECES
- G04G9/00—Visual time or date indication means
- G04G9/02—Visual time or date indication means by selecting desired characters out of a number of characters or by selecting indicating elements the position of which represent the time, e.g. by using multiplexing techniques
- G04G9/06—Visual time or date indication means by selecting desired characters out of a number of characters or by selecting indicating elements the position of which represent the time, e.g. by using multiplexing techniques using light valves, e.g. liquid crystals
- G04G9/062—Visual time or date indication means by selecting desired characters out of a number of characters or by selecting indicating elements the position of which represent the time, e.g. by using multiplexing techniques using light valves, e.g. liquid crystals using multiplexing techniques
-
- G—PHYSICS
- G04—HOROLOGY
- G04G—ELECTRONIC TIME-PIECES
- G04G9/00—Visual time or date indication means
- G04G9/08—Visual time or date indication means by building-up characters using a combination of indicating elements, e.g. by using multiplexing techniques
- G04G9/12—Visual time or date indication means by building-up characters using a combination of indicating elements, e.g. by using multiplexing techniques using light valves, e.g. liquid crystals
- G04G9/122—Visual time or date indication means by building-up characters using a combination of indicating elements, e.g. by using multiplexing techniques using light valves, e.g. liquid crystals using multiplexing techniques
Abstract
ABSTRACT OF THE DISCLUSURE
A quasi-analog watch display device is provided with a number of separate liquid-crystal display elements which are arranged in two concentric circles for the indication of hours and minutes.
The display elements of each circle are divided into several groups each of the same size per circle and all the display elements of one group are controlled by first electrodes respectively and second electrode which is a common group electrode provided with d group connection. The group electrodes of the two circles are disposed in pairs in one and the same circle sector. Several element connections are connected with a single electrode of a display element from each group through conductors which extend exclusively radially between two adjacent display elements of the two circles and from circle sector to circle secter alternately on the inner and outer edges of the two circles substantially tangentially or on circular paths.
A quasi-analog watch display device is provided with a number of separate liquid-crystal display elements which are arranged in two concentric circles for the indication of hours and minutes.
The display elements of each circle are divided into several groups each of the same size per circle and all the display elements of one group are controlled by first electrodes respectively and second electrode which is a common group electrode provided with d group connection. The group electrodes of the two circles are disposed in pairs in one and the same circle sector. Several element connections are connected with a single electrode of a display element from each group through conductors which extend exclusively radially between two adjacent display elements of the two circles and from circle sector to circle secter alternately on the inner and outer edges of the two circles substantially tangentially or on circular paths.
Description
The invention relates to a method for the static actuation of a liquid-crystal display device having a nurnber of separate display elements divided into several groups of equal size, on several group electrodes common to all elements of one group and on several element connections connec-ted with a single electrode of one element of each group, in which different voltages are fed to group electrodes and to element connections selected for the generation of a specific display, which voltages become effective in each case in pairs with their voltage difference on the individual element. The element control voltages may comprise a zero voltage, a positive base voltage with an effective value lying closely below the threshold voltage of the display elements and a negative base voltage of equal magnitude.
In all display devices having a relatively large number of display elements, for example in an array of seven-segment display devices, there are considerable difficulties in connecting each display element individually to an actuator circuit. This is especially due to the fact that the number of connections of a highly integrated actuator circuit is limited. Thus in the case of an array of eight seven-segment display with direct acutation of each individual display element, fifty-seven connections of the actuator circuit are necessary for the connection of the display devices alone. ~aturally the number of connections could theoretically be reduced by a multiplex actuation of the display device, However as is known, in many liquid-crystal display devices, especially those which are designed for continuous operation with long life, the dynamic multiplex actuation is practically impossible by reason of the physical structure of the liquid-crys-tal display ele~ents. Here a satisfactory display is effected only with a static actuation, that is to say continuous for the duration of a specific display, of the display elements to be energized in each case.
For quasi-analog strip display devices consisting of a large number of liquid-crystal display elements arranged side by side in a row, the initially mentioned method of static actuation has already been proposed, which results in a reduction of the number of necessary connections by the combining of electrodes into group electrodes and the connection of several individual electrodes to common element connections in combination with a suitable determination of the actuator voltages to be fed to the group electrodes and the element connections. ~owever the proposed method is designed expressly for the relatively clearly laid out actuation conditions in the case of a strip display device, where in each case only one individual display element or the individual element plus all elements on the one side thereof are energized. Correspondingly in the case of the proposed method the element connections are charged with the two base voltages exclusively in alternating combination. Those group electrodes whose associated display elements are all to be extinguished receive the zero voltage, those group electrodes whose associated display elements are all to be energized receive an excess voltage which both with the positive and with the negative base voltage forms a voltage difference lying above the switch-on threshold voltage of the display elements, while finally the one group electrode on which the limit between energized and unenergized elements lies is actuated with an intermediate .
, 73~
voltage which with the one base voltage produces a ~/oltage difference adequate for switching on and with the other base voltage produces a voltage difference not adequate for switching on.
A quasi-analog watch display device has also already been considered in which the travel of the watch hands over the dial is simulated by the lighting up of one display element in each of the two circles, so that the position of the display element lighting in each case in the outer circle indicates for example the minute and the position of the display element lighting up in each case in the inner circle indicates the hour. The disadvantage of this quasi-analog watch display device consists in that with a fairly reasonably high number of display elements, for example sixty display elements per circle, one arrives at an extremely high number of electric connections, which signifies not only a very extensive circuitry for the actuating electronic chip, but - and this is still more serious - a correspondingly high number of output terminals of the electronic chip, which is not available in the case of highly integrated actuator chipsO Here again a reduction of the number of connections by a multiplex actuation of the display device does not come under consideration because, as already mentioned, in many display elements, especially in liquid-crystal display elements, and specifically here in those which are designed for a continuous operation with long life, the dynamic multiplex actuation is not possible with practically satisfactory results, and a good display can be effected only with a static actuation of the display elements to be energized in each case.
A further disadvantage of the quasi-analog watch display ~ ~ ~ 2~
device of the above-mentioned kind is to be seen in the fact that its described rnanner of operation with a display element lighting up in each of the two circles only very incompletely simulates the conventional analog time display with two hands, to which one is accustomed. A far better approximation would consist in causing elongated display elements of two different lengths, corresponding to the large and small hands of a conventional watch, to light up, in which case the small hand would be represented by the lighting up of a display element of the inner circle and the large hand by the lighting up of a display element of each of the inner and outer circles, lying on the same radius. This however presumes that the display elements of the two circles lie very close beside one another in the radial direction, so that in fact the optical impression of a continuous large hand and small hand is obtained. However this placing of the two circles of display elements very close together is likewise opposed by the hitherto necessary high number of connections, of which some must necessarily be provided between the two circles of display elements. For the stated reasons therefore hitherto, at least for smaller timepieces with limited space conditions, for example wristlet watches, quasi-analog display devices with liquid-crystal display elements arranged in two concentric circles and serving for the indication of the hour and the I minute have not been realized in practice.
The invention is based upon the problem of indicating a method for the static actuation of liquid-crystal display devices with complex actuation conditions~ the liquid-crystal elements of which do not permit multiplex actuation, which renders possible a ~3Z~
saving of actuation connections and especially of indicatin~J a quasi-analog watch display device and a method for its actuation which requires comparatively only few actuation connections.
According to the present invention there is provided a method for the selectively controlling excitation of a plurality oF
electrically responsive elements of the type having element electrodes and group electrodes which are separated from each other by a crystalline liquid, each group electrode being common to a plurality of an equal number of element electrodes, each of the element electrodes and the opposed group electrode with the liquid-crystal interposed therebetween constituting a liquid-crystal display unit, each of the elements having its own element electrode, each of the elements being excited by the application to its respective element electrode and the opposed group electrode of voltages creating a voltage greater than a predetermined operating voltage across that element, and each element electrode opposite to one group electrode being electrically connected to one of the element electrodes opposite to at least one other group electrode, the so-connected element electrodes forming sets of element electrodes; continuously applying a positive fundamental voltage to one group electrode and a negative fundamental voltage of equal absolute value to another group electrode, and applying to at least one of the sets of element electrodes an excitation voltage to excite at least a selected element in that set, said excitation voltage having a value such that the difference between said excitation voltage and said fundamental voltage applied to the selected element electrodes and its opposed group electrodes, respectively, equals or ~L3'~
exceeds -the operati ng vol ta~e.
~n the basis of this fundamental idea according to the invention it is surprisingly possib1e statically to actuate even display devices with complex actuation conditions, especially multi-digit display devices assembled in each place from scveral elements, but also quasi-analog display devices of complicated assembly, such as a quasi-analog watch display device, through less actuation connections than would be necessary in the case of a direct actuation of each individual display element of the display device.
In fact in the method according to the invention a specific number of different voltages is required for actuation. Their generation and distribution to the connections for the display device are possible in an especially highly integrated actuation circuit however without particular difficulties and practically without extra expense, while on the other hand the reduction of the necessary actuation connections is of very great advantage and substantially extends and/or improves the possibilities of application of liquid-crystal display devices which cannot be actuated by the multiplex method.
An important and preferred development of the method according to the invention consists in that in the case of the presence of a total of two group electrodes in a display device the one group electrode is actuated continuously with the positive base voltage and the other continuously with the negative base voltage.
This development is especially suitable for a two-digit display device having the same number of display elements in each place, for example, for a two-digit seven-segment display device, where a group electrode is allocated to each place and each element connection is ~3273~
common to both digits. If more than two places are to he actuated, these are assembled by pairs and treated as one display device per pair. If m is the number of places and n the number of display elements of each place, an actuator integrated circuit chip must possess in the case of an even m the number m.n/2+2 and in the case of an odd _ the number (m+l).n/2+2 of actuator connections for the_ actuation of all places, while in application, m.n+l necessary actuation connections results. If conversely, an actuator integrated circuit chip is provided having a specific number of actuation connections, with this chip, using the method according to the invention, it is possible for more places to be actuated at the same time than in the case of the usual static actuation.
If in the disclosed development of the new method the element connections are actuated in each case either with the zero voltage or with a positive intermediate voltage the difference of which from the two base voltages lies respectively above and below the switch-on threshold voltage of the display elements or with a negative intermediate voltage of equal value or with an excess voltage, the difference of which from the two base voltages lies in each case above the switch-on threshold voltage, on each element connection in the simplest manner all four possible combinations of switch-on or energization conditions of the two display elements attainable through the element connection can be set and thus a completely independent actuation of the two places of the display device is realized, as naturally necessary for example for alpha-numerical display devices. On application of the zero voltage to an element connection both the associated display elements are - ;.-. . ~` :
:
Zt73~
unenergized, since the base voltage is lower than the threshold voltage as from which a variation of contrast of the display element commences. On application of the excess voltage both elements are energized~ Finally on application of one of the two intermediate voltages the one element is energized and the other unenergized, this condition exchanging on transition to the other intermediate voltage.
The suitable values for the intermediate voltages and the excess voltage are determined individually according to the electro-optical transmission characteristic of the utilized display elements. If the positive base voltage is called U and it is assumed that a voltage of 3U exceeds the switch-on voltage, which practically all current liquid-crystal elements guarantee, a suitable intermediate voltage amounts to 2U or minus 2U and a suitable excess voltage amounts to I qU. If the switch-on voltage lies below 2U, intermediate voltages of tU and-U, that is to say intermediate voltages equal to the base voltages and a switch-on voltage of 3U are sufficient.
Preferably it is arranged that one group of electrodes is actuated by one of the two base voltages and the other group of electrodes with the zero voltage. ~his development is intended primarily for the drastic reduction of the necessary number of connections for display devices with a relatively large number of disp1ay elements, of which two elements in each case are to be energized in any desired combination. In this case the two base voltages are applied to those two group electrodes in the groups of which the two elements to be energized are situated. Provided that the switch-on voltage of the display elements is lower than twice the threshold voltage, the selection of the two elements to be energized within the groups thus de-termined can best be effected in that of the many element connections present one element connection is actuated with the one base voltage, possibly a -further element connection with the other base voltage in each case and all other element connections with the zero voltage. The energization of two specific elements is here based upon the fact that the base voltage on one element connection with the other base voltage of opposite polarity on a group electrode produces a difference voltage which is greater than the switch-on voltage, while on the second group electrode, in relation to the equal base voltage present there, absolutely no difference voltage results and for the second, possibly actuated, element connection precisely the converse is valid. ~ecause in relation to all other group electrodes charged with the zero voltage no difference voltage sufficing for switching on results, through each element connection precisely the one display element is ener-gized which lies at the "intersection point" of the two base voltages of opposite polarities. The actuation of only one single element connection occurs when both elements to be energized are connected by their individual electrode to the same element connection. Then the element connection receives the one base voltage and the two affected group electrodes receive the other base voltage in common.
A display device in which exactly two elements are always energized is for example a quasi-analog watch display device in which one element indicates the hour and one element the minute. If for example such a watch display device has sixty elements for the hour arranged in a circle and sixty elements for the minute arranged in a concentric circle, in the case of conventional actuation 121 3~
connections would be necessary. Using the method according to the invention and a division of the total of 120 elements into for example 12 groups each of lU elemen-ts, on the other hand only 10~12 =
22 connections are necessary. Moreover it is an important advantage that the two circles with display elemen-ts can lie quite close to one another, because between the circles no electric connections extending in the circumferential direction, but only radial connections between the individual electrodes of each two elements adjacent in the two circles are necessary.
I 10 The quasi-analog watch display may be provided with a number of separate liquid-crystal display elements each individually actuatable through a single electrode and a further electrode, and arranged in two concentric circles. The display elements of each circle may be divided into several groups, of equal size in each case per circle, and all display elements of a group in each case may comprise a common group electrode, provided with a group connection, as second electrode. The group electrodes of the two circles preferably lie in each case by pairs in one and the same circle sector and several element connections are in each case connected with one single electrode of one display element of each group, through conductor tracks which extend between each two adjacent display elements of the two circles exclusively radially and from circle sector to circle sector alternately on the inner and on the outer edge of the two circles substantially tangentially or on ci rcular paths.
A watch display~ device of such design has considerably less èlectric connections than would be present if each display element ~3~73~
were separately connected at least with one single electrode. This is due to the fact that in each circle several display elements possess a common group electrode and the single electrodes of several display elements, namely of one display elernent from each group, are connected with one another and connected to an element connection which is common in each case. The conductor tracks which connect the single electrodes extend without crossing one another, in space-saving manner in meander form on the inner and outer edges of the two circles of display elements, while between the two circles exclusively radial connections of the single electrodes are necessary which can be kept as short as desired. Thus the display elements of the two circles can be placed very close to one another in the radial direction. Finally the important advantage exists that the new watch display device can be actuated, using the method according to the invention, so that two display elements lying end to end in the radial direction of the inner and of the outer circle due to common energization simulate a large hand and serve to indicate the minute, while in each case one single display element of the inner circle -or equally of the outer circle, which however is less logical -indicates the hour similarly to the small hand of an ordinary watch.
The element connections may lie on the outer edges of the two circles for reasons of space. It is especially advantageously suitable for the imitation of ordinary watch hands of different lengths to provide a configuration of elongated, radially directed strips wherein the display elements of the inner circle are longer than the display elements of the outer circle.
An especially advantageous method for the actuation of the ~3~
above-described quasi-analog watch display device is characterized in that four actuator voltages VO, Vl, V2 and V3 are used of which the actuator voltages Vl, V2 and V3 with the preceding actuator voltage in each case form a difference of the effective value Ueff and the ! 5 actuator voltages V2 and V3 with the actuator voltage VO form a difference of the effective value 2Ueff or 3Ueff respectively, in that a first selected element connection is charged with the actuator voltage V33 in that the other element connections, two first group connections allocated to one and the same selected circle sector and possibly a further selected group connection are charged with actuator voltages in one of the following four combinations:
I) Vl and/or V2 are applied to all other element connections, Vl and/or VO to the two first group connections;
II) Vl and/or VO are applied to all other element connections9 Vl and/or VO to the two first group connections and to the further group connection;
III) V2 are applied to a further, selected element connection, Vl to the remaining element connections, Vl and VO to the two first group connections;
IV) Vl are applied to a further selected element connection, V2 to the remaining element connections, Vl to the two first group connections, V3 t.o the further group connection;
and the remaining group connections having applied thereto the actuator voltage V2.
This actuation method takes account of` the four different ~L~Zt7~3~
fundamental arrays which mus-t be reproducible in the static actuation of the new watch display device, in order to arrive at the explained representation of "large hand" and "small hand", these arrays being reproducible with a minimum of actuation expense, especially with comparatively few and easily producible voltage levels.
In the case of the first array I the two hands are one above the other. Correspondingly two display elements, lying on the same radius and therefore connected to the same element connection, which have two group electrodes lying in the same circle sector, must be energized. In the further three arrays the two hands do not coin-cide. Two display elements lying on the same radius and in addition a further third display element preferably of the inner circle must always be energized. This third display element can be connected by its single electrode to the same element connection as the other two display elements, in which case it necessarily lies in a different circle sector from the other two display elements. Then the second array exists, which is reproduced with the second actuation combina-tion. In the case of the third array the third display element lies in the same circle sector as the other two display elements, in which case then it is necessarily connected by its single electrode to a different ele~ent connection from the other two display elements.
Finally in the case of the fourth array which is reproduced with the actuation combination IV, the third display element lies in a differ-ent circle sector from the other two display elements and is further-more connected by its single electrode to a different element connec-tion from the other two display elements. Of course furthermore, the two or three display elements which are energized in one of the four constellations must also be so selected that the display desired in ~3Z~73~
the individual case results. This and the de-termination o~ the cor-rect array for the c~esired time display can be brough-t about without substantial difficulties with ordinary logic circuits, namely highly integrated logic circuits.
Actuation combinations conforming as extensively as pos-sible for the four arrays may be obtained. In this connection it should be mentioned that the reproduction of the first and second configurations using the predetermined acutation voltages can also be achieved successfully with two different acutation combinations. In the one of these two actuation combinations some or all of the re-maining group connections are charged, instead of with the actuation voltage V2, with the actuation voltage V3, which then admittedly requires a charging of all other element combinations with the actuation voltage V2. The other actuation combination uses the actuation voltage V2 instead of the actuation voltage V3 for the actuation of the first element connection and the actuation voltage V0 for the actuation of the two first group connections. These two actuation combinations are however relatively unfavourable because they depart from the principle of charging the first element connection with V3 and the remaining group connections with V2.
For the display constellation in which both hands coincide, a further improvement of perceptibility, namely the demonstration that a long and short hand are again present~ can be achieved by a "widening" of the short hand, which is effected in that in the hour circle, that is ordinarily in the inner circle, three display elements side by side are energized, while the display element energized in the outer circle lies in the extension of the middle of ;~
the three display elements of ~ n~e7r3c ~cle. The actuation combination I according to the development is used when all four display elements to be energized lie in the same circle sector, while the actuation combination II concerns the other possible case where three display elements to be energi~ed lie on the edge of one circle sector and the fourth display element to be energized lies on the adjacent edge of the next circle sector, the fourth display element being connected by its single electrode necessarily to the same element connection as the two display elements to be energized lying on the same radius.
In principle all the mentioned actuation voltages can be direct-current voltages. Since however as is known every direct-current component in the actuation signal greatly reduces the life of liquid-crystal display elements, in the method according to the invention likewise an actuation with alternating current voltages of sine wave or especially square wave form will ordinarily be preferred. In this case, the graduation of the four actuation voltages by the effective value Ueff in each case is achieved in an especially simple manner with a development of the actuation method, the generation of the four alternating actuation voltages becoming especially simple, because pre~cisely symmetrical conditions are present and basically only two alternating actuation voltages must be produced, from which the two other actuation voltages can be derived by a simple phase shift through l80.
Furthermore, the latter development has the advantage that the greater of the two actuation voltages has the minimum possible effective value of l.5 Ueff, which advantage is important in view of ~!
the fact that portable timepieces rnust be supplied from very samll batteries.
DESCRIPTION OF T~IE DRAWINGS
The invention is explained in greater detail below wikh further advantageous details with reference to several diagrammatically illustrated examples of embodiment in the drawing, wherein:
Figure l shows a two-digit seven segment display device which is designed for actuation by the method according to the invention;
Figure 2 shows diagrammatically a quasi-analog watch display device which is designed for actuation by the method according to the invention in the second development;
Figure 3 shows diagrammatically another improved form of actuation of the watch display device;
Figure 4 shows a transmission characteristic curve of the display elements of the display device according to Figure 3;
Figure 5 shows diagrammatic representations of four different possible display configurations in the display device according to Figure 3.
Figure 6 shows diagrammatic representations of two alternative display configurations in the display device according to Figure 3;
Figure 7A shows a table indicative of the effective voltage levels and phase lag of alternating voltage controlling the display electrodes;
Figure 7B shows the wave forms of the alternating voltages;
~L3'Z~`~3'~
Figure ~A shows a table indica-ting voltage difference obtained by selectively combining the alternating voltayes; and Figure 8B shows the wave forms of the selectively combined voltages.
DETAILED DESCRIPTION OF THE DRAWINGS
According to Figure l a two-place digital display device consisting of two liquid-crystal display units l and 2 is provided with a total of l4 liquid-crystal display elements F of linear form which are arranged in the usual 8-shaped configuration of seven elements F for each place and thus divided into two groups each of seven elements F. The elements of each place or group have a common group electrode A and B respectively. Moreover each element F has its own single electrode El/l, El/2, El/3, El/4, El/5, El/6, El/7 and E2/l, E2/2, E2/3, E2/4, E2/5, E2/6, E2/7 as counter-electrode to the group electrode A and B respectively. These single electrodes are shown somewhat larger in each case in Figure l than the associated elements E, in order to achieve a somewhat clearer illustration. In reality however the elements F and their associated electrodes in each case coincide. The single electrodes El/l ... El/7 of the elements F of a place are in each case connected with the corresponding single electrodes E2/l ... E2/7 of the element F of the other place which is similar in each case as regards its position, and conducted to a common electrode connection e, so that for the two digits there are a total of seven element connections e l ... e 7 corresponding to the number of elements F in each group. The two group electrodes A and B each have a group connection a and b. All elements F have the same transmission characteristic with a specific ~ ~L~ 3 ~
threshold voltage at which the optical contrast variation begins, and a specific switch-on voltage, beyond which no further contrast variation takes place, the switch-on voltage amounting at most to three times a voltage Us Iying close below the threshold voltage, at which the element is still securely extinguished.
For actuation a positive base voltage with the value U is fed to the group electrode A and a negative base volatage -U of equal magnitude is fed to the group electrode B. The terms positive and negative relate directly to direct-current voltages. If for reasons of long life actuation is effected with alternating current voltage free from direct-current voltage, the "negative" base voltacle -U is a voltage which is shifted in phase through 180 in relation to the "positive" base voltage U and has the same amplitude as the latter.
The two base voltages U and -U are fed continuously in each case to the two group electrodes A and B.
The generation of a specific display is controlled exclusively through the element connections el ... e7, in that to each element connection el ... e7 there is fed one of four different voltages, according to the desired display. It is here a matter of a zero voltage V0 with the value 0, a positive intermediate voltage Vl with the value 2U, an equally great negative intermediate voltage V2 of value -2U and a positive excess voltage V3 of value 4U. These voltages become effective with their difference from the base voltage U or -U lying on the group electrode A or B, in each case nn both display units 1 and 2, the single electrodes El/l .... El/7 and E2/1 ... E2/7 of which are in each case connected commonly to an element connection _l ... e7. This results for each element connection el_ ... e7 in four different combinations of states of energization of ~ '~ 3~ 3~
the two elements reachable in each case through an element connection, in accordance with the following table:-Voltage on the Voltage on the element connection e group electrode ~IU -2U 2U 0 Difference E-A 3U 3U U U A - Ug voltage on on off off and state E-B 5U U 3U U B = -Ug of energization on off on off From the table it is seen that by selection of the actuation voltage for an element connection it is possible in each case either to keep both elements Fl and F2 lying on the same connection e switched on, or in each case to keep both elements Fl and F2 extinguished, or to keep the element Fl pertaining to the group electrode A switched on and the other element F2 extinguished, or conversely to keep the element F2 pertaining to the group electrode B switched on and the other element Fl extinguished. These are all possible combinations so that it is possible through the seven element connections el e7 and the two group electrodes A and B to actuate both display units l and 2, that is both places of the display device, independently of one another for a specific display.
Figure 2 shows diagrammatically a quasi-analog watch dis-play device of a total of l20 separate, mutually similar, liquid-crystal display elements F which are arranged in two concentric circles each of 60 elements at minute interval, in each case lying by pairs on the same pole radius. In each circle the elements F are -- 19 -- , .~
~ .3'~3~
divided into six groups I ... XII each of ten elements, a common group electrode GE 1 ... GE 12 being allocated in each case to the elements F of a group, which group electrode constitutes the counter-electrode to d sin~le electrode E of each element F. In -the drawing the elements FE and their respective single electrodes E are represented in each case as identical rectangles.
The display device has, in conformity with a number of elements F in each group I ... XII, a total of ten element con-nections el ... elO. Each of the element connections el ... elO is connected with the single electrode E of an element F of each group I
... XII, so that a total of 12 elements are connected to each of the element connections el ... elO. All single electrodes E of the elements F are connected in series by groups by leads L. As repre-sented in Figure 2, the leads L extend between the individual elec-trodes in meander form on the outer and inner edges of the two element circles. Between the two element circles no addltional space for leads is required, since here only short, radial connection pieces L are necessary between the single electrodes E of each two adjacent elements F in the inner and outer element circles. The group electrodes GEl .... GE12 each have a connection 91 .... ~2 which, like the element connections, can lie in the interior of the double circle, but are drawn radially outwards in the drawing for reasons of clear illustration.
This watch display device is operated so that in each case an element F of the outer circle is switched on for the indication of the minutes and an element of the inner circle, representing the hour hand, is switched on to indicate the hours, while all other elements are switched off. Provided that the switch-on voltage of the ~3~J'i'3~
elements is not greater than ~U, the corresponding actuation takes place in a manner in which the two group electrodes, GE l/GE 7, or GE
In all display devices having a relatively large number of display elements, for example in an array of seven-segment display devices, there are considerable difficulties in connecting each display element individually to an actuator circuit. This is especially due to the fact that the number of connections of a highly integrated actuator circuit is limited. Thus in the case of an array of eight seven-segment display with direct acutation of each individual display element, fifty-seven connections of the actuator circuit are necessary for the connection of the display devices alone. ~aturally the number of connections could theoretically be reduced by a multiplex actuation of the display device, However as is known, in many liquid-crystal display devices, especially those which are designed for continuous operation with long life, the dynamic multiplex actuation is practically impossible by reason of the physical structure of the liquid-crys-tal display ele~ents. Here a satisfactory display is effected only with a static actuation, that is to say continuous for the duration of a specific display, of the display elements to be energized in each case.
For quasi-analog strip display devices consisting of a large number of liquid-crystal display elements arranged side by side in a row, the initially mentioned method of static actuation has already been proposed, which results in a reduction of the number of necessary connections by the combining of electrodes into group electrodes and the connection of several individual electrodes to common element connections in combination with a suitable determination of the actuator voltages to be fed to the group electrodes and the element connections. ~owever the proposed method is designed expressly for the relatively clearly laid out actuation conditions in the case of a strip display device, where in each case only one individual display element or the individual element plus all elements on the one side thereof are energized. Correspondingly in the case of the proposed method the element connections are charged with the two base voltages exclusively in alternating combination. Those group electrodes whose associated display elements are all to be extinguished receive the zero voltage, those group electrodes whose associated display elements are all to be energized receive an excess voltage which both with the positive and with the negative base voltage forms a voltage difference lying above the switch-on threshold voltage of the display elements, while finally the one group electrode on which the limit between energized and unenergized elements lies is actuated with an intermediate .
, 73~
voltage which with the one base voltage produces a ~/oltage difference adequate for switching on and with the other base voltage produces a voltage difference not adequate for switching on.
A quasi-analog watch display device has also already been considered in which the travel of the watch hands over the dial is simulated by the lighting up of one display element in each of the two circles, so that the position of the display element lighting in each case in the outer circle indicates for example the minute and the position of the display element lighting up in each case in the inner circle indicates the hour. The disadvantage of this quasi-analog watch display device consists in that with a fairly reasonably high number of display elements, for example sixty display elements per circle, one arrives at an extremely high number of electric connections, which signifies not only a very extensive circuitry for the actuating electronic chip, but - and this is still more serious - a correspondingly high number of output terminals of the electronic chip, which is not available in the case of highly integrated actuator chipsO Here again a reduction of the number of connections by a multiplex actuation of the display device does not come under consideration because, as already mentioned, in many display elements, especially in liquid-crystal display elements, and specifically here in those which are designed for a continuous operation with long life, the dynamic multiplex actuation is not possible with practically satisfactory results, and a good display can be effected only with a static actuation of the display elements to be energized in each case.
A further disadvantage of the quasi-analog watch display ~ ~ ~ 2~
device of the above-mentioned kind is to be seen in the fact that its described rnanner of operation with a display element lighting up in each of the two circles only very incompletely simulates the conventional analog time display with two hands, to which one is accustomed. A far better approximation would consist in causing elongated display elements of two different lengths, corresponding to the large and small hands of a conventional watch, to light up, in which case the small hand would be represented by the lighting up of a display element of the inner circle and the large hand by the lighting up of a display element of each of the inner and outer circles, lying on the same radius. This however presumes that the display elements of the two circles lie very close beside one another in the radial direction, so that in fact the optical impression of a continuous large hand and small hand is obtained. However this placing of the two circles of display elements very close together is likewise opposed by the hitherto necessary high number of connections, of which some must necessarily be provided between the two circles of display elements. For the stated reasons therefore hitherto, at least for smaller timepieces with limited space conditions, for example wristlet watches, quasi-analog display devices with liquid-crystal display elements arranged in two concentric circles and serving for the indication of the hour and the I minute have not been realized in practice.
The invention is based upon the problem of indicating a method for the static actuation of liquid-crystal display devices with complex actuation conditions~ the liquid-crystal elements of which do not permit multiplex actuation, which renders possible a ~3Z~
saving of actuation connections and especially of indicatin~J a quasi-analog watch display device and a method for its actuation which requires comparatively only few actuation connections.
According to the present invention there is provided a method for the selectively controlling excitation of a plurality oF
electrically responsive elements of the type having element electrodes and group electrodes which are separated from each other by a crystalline liquid, each group electrode being common to a plurality of an equal number of element electrodes, each of the element electrodes and the opposed group electrode with the liquid-crystal interposed therebetween constituting a liquid-crystal display unit, each of the elements having its own element electrode, each of the elements being excited by the application to its respective element electrode and the opposed group electrode of voltages creating a voltage greater than a predetermined operating voltage across that element, and each element electrode opposite to one group electrode being electrically connected to one of the element electrodes opposite to at least one other group electrode, the so-connected element electrodes forming sets of element electrodes; continuously applying a positive fundamental voltage to one group electrode and a negative fundamental voltage of equal absolute value to another group electrode, and applying to at least one of the sets of element electrodes an excitation voltage to excite at least a selected element in that set, said excitation voltage having a value such that the difference between said excitation voltage and said fundamental voltage applied to the selected element electrodes and its opposed group electrodes, respectively, equals or ~L3'~
exceeds -the operati ng vol ta~e.
~n the basis of this fundamental idea according to the invention it is surprisingly possib1e statically to actuate even display devices with complex actuation conditions, especially multi-digit display devices assembled in each place from scveral elements, but also quasi-analog display devices of complicated assembly, such as a quasi-analog watch display device, through less actuation connections than would be necessary in the case of a direct actuation of each individual display element of the display device.
In fact in the method according to the invention a specific number of different voltages is required for actuation. Their generation and distribution to the connections for the display device are possible in an especially highly integrated actuation circuit however without particular difficulties and practically without extra expense, while on the other hand the reduction of the necessary actuation connections is of very great advantage and substantially extends and/or improves the possibilities of application of liquid-crystal display devices which cannot be actuated by the multiplex method.
An important and preferred development of the method according to the invention consists in that in the case of the presence of a total of two group electrodes in a display device the one group electrode is actuated continuously with the positive base voltage and the other continuously with the negative base voltage.
This development is especially suitable for a two-digit display device having the same number of display elements in each place, for example, for a two-digit seven-segment display device, where a group electrode is allocated to each place and each element connection is ~3273~
common to both digits. If more than two places are to he actuated, these are assembled by pairs and treated as one display device per pair. If m is the number of places and n the number of display elements of each place, an actuator integrated circuit chip must possess in the case of an even m the number m.n/2+2 and in the case of an odd _ the number (m+l).n/2+2 of actuator connections for the_ actuation of all places, while in application, m.n+l necessary actuation connections results. If conversely, an actuator integrated circuit chip is provided having a specific number of actuation connections, with this chip, using the method according to the invention, it is possible for more places to be actuated at the same time than in the case of the usual static actuation.
If in the disclosed development of the new method the element connections are actuated in each case either with the zero voltage or with a positive intermediate voltage the difference of which from the two base voltages lies respectively above and below the switch-on threshold voltage of the display elements or with a negative intermediate voltage of equal value or with an excess voltage, the difference of which from the two base voltages lies in each case above the switch-on threshold voltage, on each element connection in the simplest manner all four possible combinations of switch-on or energization conditions of the two display elements attainable through the element connection can be set and thus a completely independent actuation of the two places of the display device is realized, as naturally necessary for example for alpha-numerical display devices. On application of the zero voltage to an element connection both the associated display elements are - ;.-. . ~` :
:
Zt73~
unenergized, since the base voltage is lower than the threshold voltage as from which a variation of contrast of the display element commences. On application of the excess voltage both elements are energized~ Finally on application of one of the two intermediate voltages the one element is energized and the other unenergized, this condition exchanging on transition to the other intermediate voltage.
The suitable values for the intermediate voltages and the excess voltage are determined individually according to the electro-optical transmission characteristic of the utilized display elements. If the positive base voltage is called U and it is assumed that a voltage of 3U exceeds the switch-on voltage, which practically all current liquid-crystal elements guarantee, a suitable intermediate voltage amounts to 2U or minus 2U and a suitable excess voltage amounts to I qU. If the switch-on voltage lies below 2U, intermediate voltages of tU and-U, that is to say intermediate voltages equal to the base voltages and a switch-on voltage of 3U are sufficient.
Preferably it is arranged that one group of electrodes is actuated by one of the two base voltages and the other group of electrodes with the zero voltage. ~his development is intended primarily for the drastic reduction of the necessary number of connections for display devices with a relatively large number of disp1ay elements, of which two elements in each case are to be energized in any desired combination. In this case the two base voltages are applied to those two group electrodes in the groups of which the two elements to be energized are situated. Provided that the switch-on voltage of the display elements is lower than twice the threshold voltage, the selection of the two elements to be energized within the groups thus de-termined can best be effected in that of the many element connections present one element connection is actuated with the one base voltage, possibly a -further element connection with the other base voltage in each case and all other element connections with the zero voltage. The energization of two specific elements is here based upon the fact that the base voltage on one element connection with the other base voltage of opposite polarity on a group electrode produces a difference voltage which is greater than the switch-on voltage, while on the second group electrode, in relation to the equal base voltage present there, absolutely no difference voltage results and for the second, possibly actuated, element connection precisely the converse is valid. ~ecause in relation to all other group electrodes charged with the zero voltage no difference voltage sufficing for switching on results, through each element connection precisely the one display element is ener-gized which lies at the "intersection point" of the two base voltages of opposite polarities. The actuation of only one single element connection occurs when both elements to be energized are connected by their individual electrode to the same element connection. Then the element connection receives the one base voltage and the two affected group electrodes receive the other base voltage in common.
A display device in which exactly two elements are always energized is for example a quasi-analog watch display device in which one element indicates the hour and one element the minute. If for example such a watch display device has sixty elements for the hour arranged in a circle and sixty elements for the minute arranged in a concentric circle, in the case of conventional actuation 121 3~
connections would be necessary. Using the method according to the invention and a division of the total of 120 elements into for example 12 groups each of lU elemen-ts, on the other hand only 10~12 =
22 connections are necessary. Moreover it is an important advantage that the two circles with display elemen-ts can lie quite close to one another, because between the circles no electric connections extending in the circumferential direction, but only radial connections between the individual electrodes of each two elements adjacent in the two circles are necessary.
I 10 The quasi-analog watch display may be provided with a number of separate liquid-crystal display elements each individually actuatable through a single electrode and a further electrode, and arranged in two concentric circles. The display elements of each circle may be divided into several groups, of equal size in each case per circle, and all display elements of a group in each case may comprise a common group electrode, provided with a group connection, as second electrode. The group electrodes of the two circles preferably lie in each case by pairs in one and the same circle sector and several element connections are in each case connected with one single electrode of one display element of each group, through conductor tracks which extend between each two adjacent display elements of the two circles exclusively radially and from circle sector to circle sector alternately on the inner and on the outer edge of the two circles substantially tangentially or on ci rcular paths.
A watch display~ device of such design has considerably less èlectric connections than would be present if each display element ~3~73~
were separately connected at least with one single electrode. This is due to the fact that in each circle several display elements possess a common group electrode and the single electrodes of several display elements, namely of one display elernent from each group, are connected with one another and connected to an element connection which is common in each case. The conductor tracks which connect the single electrodes extend without crossing one another, in space-saving manner in meander form on the inner and outer edges of the two circles of display elements, while between the two circles exclusively radial connections of the single electrodes are necessary which can be kept as short as desired. Thus the display elements of the two circles can be placed very close to one another in the radial direction. Finally the important advantage exists that the new watch display device can be actuated, using the method according to the invention, so that two display elements lying end to end in the radial direction of the inner and of the outer circle due to common energization simulate a large hand and serve to indicate the minute, while in each case one single display element of the inner circle -or equally of the outer circle, which however is less logical -indicates the hour similarly to the small hand of an ordinary watch.
The element connections may lie on the outer edges of the two circles for reasons of space. It is especially advantageously suitable for the imitation of ordinary watch hands of different lengths to provide a configuration of elongated, radially directed strips wherein the display elements of the inner circle are longer than the display elements of the outer circle.
An especially advantageous method for the actuation of the ~3~
above-described quasi-analog watch display device is characterized in that four actuator voltages VO, Vl, V2 and V3 are used of which the actuator voltages Vl, V2 and V3 with the preceding actuator voltage in each case form a difference of the effective value Ueff and the ! 5 actuator voltages V2 and V3 with the actuator voltage VO form a difference of the effective value 2Ueff or 3Ueff respectively, in that a first selected element connection is charged with the actuator voltage V33 in that the other element connections, two first group connections allocated to one and the same selected circle sector and possibly a further selected group connection are charged with actuator voltages in one of the following four combinations:
I) Vl and/or V2 are applied to all other element connections, Vl and/or VO to the two first group connections;
II) Vl and/or VO are applied to all other element connections9 Vl and/or VO to the two first group connections and to the further group connection;
III) V2 are applied to a further, selected element connection, Vl to the remaining element connections, Vl and VO to the two first group connections;
IV) Vl are applied to a further selected element connection, V2 to the remaining element connections, Vl to the two first group connections, V3 t.o the further group connection;
and the remaining group connections having applied thereto the actuator voltage V2.
This actuation method takes account of` the four different ~L~Zt7~3~
fundamental arrays which mus-t be reproducible in the static actuation of the new watch display device, in order to arrive at the explained representation of "large hand" and "small hand", these arrays being reproducible with a minimum of actuation expense, especially with comparatively few and easily producible voltage levels.
In the case of the first array I the two hands are one above the other. Correspondingly two display elements, lying on the same radius and therefore connected to the same element connection, which have two group electrodes lying in the same circle sector, must be energized. In the further three arrays the two hands do not coin-cide. Two display elements lying on the same radius and in addition a further third display element preferably of the inner circle must always be energized. This third display element can be connected by its single electrode to the same element connection as the other two display elements, in which case it necessarily lies in a different circle sector from the other two display elements. Then the second array exists, which is reproduced with the second actuation combina-tion. In the case of the third array the third display element lies in the same circle sector as the other two display elements, in which case then it is necessarily connected by its single electrode to a different ele~ent connection from the other two display elements.
Finally in the case of the fourth array which is reproduced with the actuation combination IV, the third display element lies in a differ-ent circle sector from the other two display elements and is further-more connected by its single electrode to a different element connec-tion from the other two display elements. Of course furthermore, the two or three display elements which are energized in one of the four constellations must also be so selected that the display desired in ~3Z~73~
the individual case results. This and the de-termination o~ the cor-rect array for the c~esired time display can be brough-t about without substantial difficulties with ordinary logic circuits, namely highly integrated logic circuits.
Actuation combinations conforming as extensively as pos-sible for the four arrays may be obtained. In this connection it should be mentioned that the reproduction of the first and second configurations using the predetermined acutation voltages can also be achieved successfully with two different acutation combinations. In the one of these two actuation combinations some or all of the re-maining group connections are charged, instead of with the actuation voltage V2, with the actuation voltage V3, which then admittedly requires a charging of all other element combinations with the actuation voltage V2. The other actuation combination uses the actuation voltage V2 instead of the actuation voltage V3 for the actuation of the first element connection and the actuation voltage V0 for the actuation of the two first group connections. These two actuation combinations are however relatively unfavourable because they depart from the principle of charging the first element connection with V3 and the remaining group connections with V2.
For the display constellation in which both hands coincide, a further improvement of perceptibility, namely the demonstration that a long and short hand are again present~ can be achieved by a "widening" of the short hand, which is effected in that in the hour circle, that is ordinarily in the inner circle, three display elements side by side are energized, while the display element energized in the outer circle lies in the extension of the middle of ;~
the three display elements of ~ n~e7r3c ~cle. The actuation combination I according to the development is used when all four display elements to be energized lie in the same circle sector, while the actuation combination II concerns the other possible case where three display elements to be energi~ed lie on the edge of one circle sector and the fourth display element to be energized lies on the adjacent edge of the next circle sector, the fourth display element being connected by its single electrode necessarily to the same element connection as the two display elements to be energized lying on the same radius.
In principle all the mentioned actuation voltages can be direct-current voltages. Since however as is known every direct-current component in the actuation signal greatly reduces the life of liquid-crystal display elements, in the method according to the invention likewise an actuation with alternating current voltages of sine wave or especially square wave form will ordinarily be preferred. In this case, the graduation of the four actuation voltages by the effective value Ueff in each case is achieved in an especially simple manner with a development of the actuation method, the generation of the four alternating actuation voltages becoming especially simple, because pre~cisely symmetrical conditions are present and basically only two alternating actuation voltages must be produced, from which the two other actuation voltages can be derived by a simple phase shift through l80.
Furthermore, the latter development has the advantage that the greater of the two actuation voltages has the minimum possible effective value of l.5 Ueff, which advantage is important in view of ~!
the fact that portable timepieces rnust be supplied from very samll batteries.
DESCRIPTION OF T~IE DRAWINGS
The invention is explained in greater detail below wikh further advantageous details with reference to several diagrammatically illustrated examples of embodiment in the drawing, wherein:
Figure l shows a two-digit seven segment display device which is designed for actuation by the method according to the invention;
Figure 2 shows diagrammatically a quasi-analog watch display device which is designed for actuation by the method according to the invention in the second development;
Figure 3 shows diagrammatically another improved form of actuation of the watch display device;
Figure 4 shows a transmission characteristic curve of the display elements of the display device according to Figure 3;
Figure 5 shows diagrammatic representations of four different possible display configurations in the display device according to Figure 3.
Figure 6 shows diagrammatic representations of two alternative display configurations in the display device according to Figure 3;
Figure 7A shows a table indicative of the effective voltage levels and phase lag of alternating voltage controlling the display electrodes;
Figure 7B shows the wave forms of the alternating voltages;
~L3'Z~`~3'~
Figure ~A shows a table indica-ting voltage difference obtained by selectively combining the alternating voltayes; and Figure 8B shows the wave forms of the selectively combined voltages.
DETAILED DESCRIPTION OF THE DRAWINGS
According to Figure l a two-place digital display device consisting of two liquid-crystal display units l and 2 is provided with a total of l4 liquid-crystal display elements F of linear form which are arranged in the usual 8-shaped configuration of seven elements F for each place and thus divided into two groups each of seven elements F. The elements of each place or group have a common group electrode A and B respectively. Moreover each element F has its own single electrode El/l, El/2, El/3, El/4, El/5, El/6, El/7 and E2/l, E2/2, E2/3, E2/4, E2/5, E2/6, E2/7 as counter-electrode to the group electrode A and B respectively. These single electrodes are shown somewhat larger in each case in Figure l than the associated elements E, in order to achieve a somewhat clearer illustration. In reality however the elements F and their associated electrodes in each case coincide. The single electrodes El/l ... El/7 of the elements F of a place are in each case connected with the corresponding single electrodes E2/l ... E2/7 of the element F of the other place which is similar in each case as regards its position, and conducted to a common electrode connection e, so that for the two digits there are a total of seven element connections e l ... e 7 corresponding to the number of elements F in each group. The two group electrodes A and B each have a group connection a and b. All elements F have the same transmission characteristic with a specific ~ ~L~ 3 ~
threshold voltage at which the optical contrast variation begins, and a specific switch-on voltage, beyond which no further contrast variation takes place, the switch-on voltage amounting at most to three times a voltage Us Iying close below the threshold voltage, at which the element is still securely extinguished.
For actuation a positive base voltage with the value U is fed to the group electrode A and a negative base volatage -U of equal magnitude is fed to the group electrode B. The terms positive and negative relate directly to direct-current voltages. If for reasons of long life actuation is effected with alternating current voltage free from direct-current voltage, the "negative" base voltacle -U is a voltage which is shifted in phase through 180 in relation to the "positive" base voltage U and has the same amplitude as the latter.
The two base voltages U and -U are fed continuously in each case to the two group electrodes A and B.
The generation of a specific display is controlled exclusively through the element connections el ... e7, in that to each element connection el ... e7 there is fed one of four different voltages, according to the desired display. It is here a matter of a zero voltage V0 with the value 0, a positive intermediate voltage Vl with the value 2U, an equally great negative intermediate voltage V2 of value -2U and a positive excess voltage V3 of value 4U. These voltages become effective with their difference from the base voltage U or -U lying on the group electrode A or B, in each case nn both display units 1 and 2, the single electrodes El/l .... El/7 and E2/1 ... E2/7 of which are in each case connected commonly to an element connection _l ... e7. This results for each element connection el_ ... e7 in four different combinations of states of energization of ~ '~ 3~ 3~
the two elements reachable in each case through an element connection, in accordance with the following table:-Voltage on the Voltage on the element connection e group electrode ~IU -2U 2U 0 Difference E-A 3U 3U U U A - Ug voltage on on off off and state E-B 5U U 3U U B = -Ug of energization on off on off From the table it is seen that by selection of the actuation voltage for an element connection it is possible in each case either to keep both elements Fl and F2 lying on the same connection e switched on, or in each case to keep both elements Fl and F2 extinguished, or to keep the element Fl pertaining to the group electrode A switched on and the other element F2 extinguished, or conversely to keep the element F2 pertaining to the group electrode B switched on and the other element Fl extinguished. These are all possible combinations so that it is possible through the seven element connections el e7 and the two group electrodes A and B to actuate both display units l and 2, that is both places of the display device, independently of one another for a specific display.
Figure 2 shows diagrammatically a quasi-analog watch dis-play device of a total of l20 separate, mutually similar, liquid-crystal display elements F which are arranged in two concentric circles each of 60 elements at minute interval, in each case lying by pairs on the same pole radius. In each circle the elements F are -- 19 -- , .~
~ .3'~3~
divided into six groups I ... XII each of ten elements, a common group electrode GE 1 ... GE 12 being allocated in each case to the elements F of a group, which group electrode constitutes the counter-electrode to d sin~le electrode E of each element F. In -the drawing the elements FE and their respective single electrodes E are represented in each case as identical rectangles.
The display device has, in conformity with a number of elements F in each group I ... XII, a total of ten element con-nections el ... elO. Each of the element connections el ... elO is connected with the single electrode E of an element F of each group I
... XII, so that a total of 12 elements are connected to each of the element connections el ... elO. All single electrodes E of the elements F are connected in series by groups by leads L. As repre-sented in Figure 2, the leads L extend between the individual elec-trodes in meander form on the outer and inner edges of the two element circles. Between the two element circles no addltional space for leads is required, since here only short, radial connection pieces L are necessary between the single electrodes E of each two adjacent elements F in the inner and outer element circles. The group electrodes GEl .... GE12 each have a connection 91 .... ~2 which, like the element connections, can lie in the interior of the double circle, but are drawn radially outwards in the drawing for reasons of clear illustration.
This watch display device is operated so that in each case an element F of the outer circle is switched on for the indication of the minutes and an element of the inner circle, representing the hour hand, is switched on to indicate the hours, while all other elements are switched off. Provided that the switch-on voltage of the ~3~J'i'3~
elements is not greater than ~U, the corresponding actuation takes place in a manner in which the two group electrodes, GE l/GE 7, or GE
2/GE ~, or GE 3/GE 9, or GE 4/GE 10, or GE 5/GE 11, or GE 6/GE 12 as the case may be, to which the elements F to be switched on in each case are allocated, are charged with the two base voltages explained with reference to Figure 1. For the case where the two elements to be switched on are not allocated to the same element connection e, in this case the one group electrode GE, for example the group electrode GE 7 ... GE 12 pertaining to the inner circle, receives the positive base voltage U and the other group electrode GE 1 .... GE 6 allocated to the outer circle receives the negative base voltage -U. All other group electrodes receive the zero voltage. The negative base voltage is applied to the element connection which is connected with the single electrode F of the element F to be switched on in the inner circle, while the positive base voltage is applied to the element connection el ... elO which is connected with the single electrode E
of the element F to be switched on in the outer circle. Thus on the two elements F to be switched on a difference voltage 2U occurs which suffices for switching on, while on all other elements there occurs a difference voltage according to element of U or 0, at which the rele-vant elements F remain extinguished. For the case where both elements F to be switched on are connected with their single elec-trode E to the same element connection el ... elO, the corresponding group electrodes GE 1 ... GE 12 are both charged with the same one base voltage, for example the negative base voltage -U, and the element connection el ... elO is charged with the complementary base voltage, for example the positive base voltage U.
The quasi-analog watch display device as illustrated in ;~
~ 3~J~7~3'1 Figure 3 comprises a total of 120 separate liquid-crystal display elements Fl and F2. 60 display elements Fl are arranged in an outer circle and the other 60 display elements F2 in an inner circle con-centric therewith and immediately ad~ioining the outer circle. The 60 display elements Fl and F2 of each circle are divided into six groups I ... VI of equal size each of ten display elements Fl and F2 re-spectively. All display elements Fl or F2 of a group I ,.. XII have a common group electrode GE 1 ... GE 12 as counter-electrode to a single electrode E of each display element Fl or F2. Correspondingly for the display elements Fl in the outer circle there are the group electrodes GE 1, GE 2, GE 3, GE 4~ GE 5 and GE 6 and for the display elements F2 of the inner circle the group electrodes GE 7, GE 8, GE
9, GE 10, GE 11 and GE 12. lhe group electrodes GE of the two circles lie in each case by pairs in one and the same circle sector, that is for example the group electrodes GE 1 and GE 7 or GE 2 and GE
8. All group electrodes GE are in each case connected through a printed conductor Lg electrically with a group connection gl, g2 912 allocated to the respective group electrode, while the group con-nections are arranged on the outer edge of the two element circles.
The display device further has, according to the number oF
display elements Fl or F2 in each group, ten element connections el, e2 ... elO which likewise are arranged outside the two element circles in the circle sector in which the two group electrodes GEl and GE7 lie. Each element connection el ... elO is connected with the single electrode E of a display element Fl of the group I. As may be seen from Figure 3, not only are all single electrodes E of the elements Fl of the outer circle connected by short radial leads ~ 22 -.
~3~7~
Lz with the single electrodes E, lying in each case on the same pole radius, of the elements F2 lying on the inner circle, but the single electrode E of all single elements Fl ancl F2 of the two circles are connected with one another in each case in groups by conductors Ll, L2, L3, L4, L5 so that in each case twelve single elements, lying in series with one another, are connected commonly in each case to one of the element connections el ... elO.
The conductors Ll ... L5 extend in each case partially radially and partially on concentric circle arcs. Here the conductors Ll and L2 lie on the outer edge of the two circles, while the conductors L3, L4 and L5 lie in meander form on the inner edge of the element circles. Between the two circles of display elements there are no connections and no conductors extending on circular paths, but only the short, radial connection pieces Lz between the single electrodes in each case of two adjacent elements lying on the same radius, in the inner and outer circles. The conductors could extend substantially partially tangentially instead of on circular paths.
The display elements F2 of the inner circle have the form of elongated strips of tapering width, while the display elements Fl of the outer circle are shorter than those of the inner circle and have the form of a radially outwardly directed arrowhead.
As in the example of embodiment according to Figure 2, all liquid-crystal display elements Fl and F2 have the same transmission characteristic as represented in Figure 4, which shows the optical contrast K over the effective actuation voltage V applied to the electrodes of the relevant display element. The optical contrast .
~3~3~
begins to vary at a threshold voltage Us lying close above a value U.
It has reached its saturation at a switch-on voltage which amounts to approximately 2U. It is known nowadays how one achieves such a transmission characteristic of liquid-crystal display elements~
For the actuation of the watch display device as shown in Figure 3, there are used four square-wave alternating current voltages tsee Figures 7A and 7B) of which the two actuation voltages V3 and V2 are equal in phase with one another and have the effective value 1.5 U and 0.5 IJ, while the other two actuation voltages Vl and V0, which in turn are equal in phase with one another, are shifted in phase by 180 in relation to the two first-mentioned actuation voltages, but likewise have the effective value of 0.5 U and 1.5 U
respectively. Thus the actuation voltages Vl, V2 and V3 with the numerically preceding actuation voltage in each case form a difference of the effective value U and the actuation voltages V2 and V3 with the actuation voltage V0 form a difference of the effective value 2U and 3U respectively (see Figures 8A and 8B).
Figure 5 shows in four highly simplified details of the display device according to Figure 3 four different display configurations Xl, X2, X3 and X4 which must be realisable in order to be able to display all occurring time indications in simulation of the ordinary analog watch display with a large hand and a small hand, the large hand being simulated by the energization in each case of two display elements, lying on the same pole radius, of the inner and outer circles and the small hand being simulated by the energization of one display element of the inner circle.
The four display configurations Xl, X2, X3 and X4 are ~L3~3~
generated in that the four actuation voltages VO, Vl, V2 and V3 are fed in one of the tour -Following actuation combinations to the element connections El ... ElO and to the group connections gl ...
gl2 of the display device.
In all combinations a first element connection, with which the single electrodes of the two display elements are connected for the representation of the large hand, is charged with the actuation voltage V3.
In the case of the configuration Xl the large and the small hands are in coincidence, apart from the first element connection all other element connections are charged with the actuation voltage V2.
The two group connections of the two group electrodes lying in the same circle sector of the two display elements Fl and F2 to be energized are charged with the actuation voltage Vl, and all remaining group connections apart from these two first group connections are charged with the actuation voltage V2. Thus the switch^on voltage 2U, as difference of the voltages applied to the group and single electrodçs, occurs only on the two display elements to be energized. The difference on all other display elements is only U or 0.
In the further configurations X2, X3 and X4 the large and small hands have different angle positions. Three display elements Fl and F2 have always to be energized, these always including two which lie on the same pole radius and thus in the same circle sector, the single electrodes of which as stated receive the actuation voltage V3 through the relevant first element connection.
In the case of the display configuration X2 the small -- 25 ~
~3~3~
hand, -that is the third display element, lies in a different circle sector from the large hand, but its single electrode E is connected to the same element connection as the single electrodes of the other two display elements. As in configuration Xl all other element connections receive the actuation voltage V2. The two first group connections ancl the further group connection allocated to the third display element to be energized are charged with the actuation voltage Vl, while all the rest of the group connections are charged with the actuation voltage V2.
In the case of configuration X3, the small hand, that is the third display element, lies in the same circle sector as the other two display elements to be energized. The single electrode of this third display element receives the actuation voltage V2 through the associated element connection, while the acutation voltage Vl is applied to the remaining element connections. The actuation voltages Vl and V0 are present on the two first group connections, namely in such a way that the outer group electrode of the relevant circle sector has the actuation voltage Vl and the inner group electrode the actuation voltage V0. All the rest of the group connections receive the actuation voltage V2.
Finally in the case of the fourth display configuration X4 the third display element to be energized is situated in a different circle sector from the two first display elements and moreover is connected in its single electrode to a different element connection from these. The single electrode of the third display element receives the actuation voltage Vl through the associated element connection, while the actuation voltage V2 is present on the ~a ~3Z~73~
remaining element connections. The two first group connections which are allocated to the circle sector of the large hand both receive the actuation voltage Vl, while the group electrode of the third display element is charged with the actuation vol-tage V3 through its group connection. Again the actuation voltage V2 is present on the rest of the group connections.
Figure 6 shows a variant oF the display in which, in the case of coincidence of the hands, the two display elements which are immediately adjacent on the left and right to the energized display element in the inner circle, are additionally energized. For this purpose, there are the two possible display configurations characterized in Figure 4 by Xl' and X2', which differ in that in the case of Xl' all four display elements to be energized lie in the same circle sector, while in the other case - X2' - three display elements lie on the edge of the one circle sector and one display element on the adjacent edge of the next circle sector. Starting from configuration Xl, the display configuration Xl' is generated in that the inner group electrode of the circle sector is charged with VO
instead of with the actuation voltage Vl, the actuation vnltage V2 is fed to the single electrodes of the two additional adjacent display elements through their single connections, and the actuatinn voltage Vl is fed to all the rest of the element connections. The display configuration X2' is realized, starting from configuration II, in that the inner group electrode of the circle sector in which three display elements for energization lie, is charged with actuation voltage VO instead of with Vl, further the actuation voltage V2 is fed to the single electrode of the additional display element in the 73~
circle sector with the three display elements, through the corresponding element connection, and finally all other element connections are charged with the actuation voltage Vl. On account of the described guidance of -the conductors Le the single electrode of S the single display element to be energized in the other circle sector receives the actuation voltage v3 through the first element connection.
of the element F to be switched on in the outer circle. Thus on the two elements F to be switched on a difference voltage 2U occurs which suffices for switching on, while on all other elements there occurs a difference voltage according to element of U or 0, at which the rele-vant elements F remain extinguished. For the case where both elements F to be switched on are connected with their single elec-trode E to the same element connection el ... elO, the corresponding group electrodes GE 1 ... GE 12 are both charged with the same one base voltage, for example the negative base voltage -U, and the element connection el ... elO is charged with the complementary base voltage, for example the positive base voltage U.
The quasi-analog watch display device as illustrated in ;~
~ 3~J~7~3'1 Figure 3 comprises a total of 120 separate liquid-crystal display elements Fl and F2. 60 display elements Fl are arranged in an outer circle and the other 60 display elements F2 in an inner circle con-centric therewith and immediately ad~ioining the outer circle. The 60 display elements Fl and F2 of each circle are divided into six groups I ... VI of equal size each of ten display elements Fl and F2 re-spectively. All display elements Fl or F2 of a group I ,.. XII have a common group electrode GE 1 ... GE 12 as counter-electrode to a single electrode E of each display element Fl or F2. Correspondingly for the display elements Fl in the outer circle there are the group electrodes GE 1, GE 2, GE 3, GE 4~ GE 5 and GE 6 and for the display elements F2 of the inner circle the group electrodes GE 7, GE 8, GE
9, GE 10, GE 11 and GE 12. lhe group electrodes GE of the two circles lie in each case by pairs in one and the same circle sector, that is for example the group electrodes GE 1 and GE 7 or GE 2 and GE
8. All group electrodes GE are in each case connected through a printed conductor Lg electrically with a group connection gl, g2 912 allocated to the respective group electrode, while the group con-nections are arranged on the outer edge of the two element circles.
The display device further has, according to the number oF
display elements Fl or F2 in each group, ten element connections el, e2 ... elO which likewise are arranged outside the two element circles in the circle sector in which the two group electrodes GEl and GE7 lie. Each element connection el ... elO is connected with the single electrode E of a display element Fl of the group I. As may be seen from Figure 3, not only are all single electrodes E of the elements Fl of the outer circle connected by short radial leads ~ 22 -.
~3~7~
Lz with the single electrodes E, lying in each case on the same pole radius, of the elements F2 lying on the inner circle, but the single electrode E of all single elements Fl ancl F2 of the two circles are connected with one another in each case in groups by conductors Ll, L2, L3, L4, L5 so that in each case twelve single elements, lying in series with one another, are connected commonly in each case to one of the element connections el ... elO.
The conductors Ll ... L5 extend in each case partially radially and partially on concentric circle arcs. Here the conductors Ll and L2 lie on the outer edge of the two circles, while the conductors L3, L4 and L5 lie in meander form on the inner edge of the element circles. Between the two circles of display elements there are no connections and no conductors extending on circular paths, but only the short, radial connection pieces Lz between the single electrodes in each case of two adjacent elements lying on the same radius, in the inner and outer circles. The conductors could extend substantially partially tangentially instead of on circular paths.
The display elements F2 of the inner circle have the form of elongated strips of tapering width, while the display elements Fl of the outer circle are shorter than those of the inner circle and have the form of a radially outwardly directed arrowhead.
As in the example of embodiment according to Figure 2, all liquid-crystal display elements Fl and F2 have the same transmission characteristic as represented in Figure 4, which shows the optical contrast K over the effective actuation voltage V applied to the electrodes of the relevant display element. The optical contrast .
~3~3~
begins to vary at a threshold voltage Us lying close above a value U.
It has reached its saturation at a switch-on voltage which amounts to approximately 2U. It is known nowadays how one achieves such a transmission characteristic of liquid-crystal display elements~
For the actuation of the watch display device as shown in Figure 3, there are used four square-wave alternating current voltages tsee Figures 7A and 7B) of which the two actuation voltages V3 and V2 are equal in phase with one another and have the effective value 1.5 U and 0.5 IJ, while the other two actuation voltages Vl and V0, which in turn are equal in phase with one another, are shifted in phase by 180 in relation to the two first-mentioned actuation voltages, but likewise have the effective value of 0.5 U and 1.5 U
respectively. Thus the actuation voltages Vl, V2 and V3 with the numerically preceding actuation voltage in each case form a difference of the effective value U and the actuation voltages V2 and V3 with the actuation voltage V0 form a difference of the effective value 2U and 3U respectively (see Figures 8A and 8B).
Figure 5 shows in four highly simplified details of the display device according to Figure 3 four different display configurations Xl, X2, X3 and X4 which must be realisable in order to be able to display all occurring time indications in simulation of the ordinary analog watch display with a large hand and a small hand, the large hand being simulated by the energization in each case of two display elements, lying on the same pole radius, of the inner and outer circles and the small hand being simulated by the energization of one display element of the inner circle.
The four display configurations Xl, X2, X3 and X4 are ~L3~3~
generated in that the four actuation voltages VO, Vl, V2 and V3 are fed in one of the tour -Following actuation combinations to the element connections El ... ElO and to the group connections gl ...
gl2 of the display device.
In all combinations a first element connection, with which the single electrodes of the two display elements are connected for the representation of the large hand, is charged with the actuation voltage V3.
In the case of the configuration Xl the large and the small hands are in coincidence, apart from the first element connection all other element connections are charged with the actuation voltage V2.
The two group connections of the two group electrodes lying in the same circle sector of the two display elements Fl and F2 to be energized are charged with the actuation voltage Vl, and all remaining group connections apart from these two first group connections are charged with the actuation voltage V2. Thus the switch^on voltage 2U, as difference of the voltages applied to the group and single electrodçs, occurs only on the two display elements to be energized. The difference on all other display elements is only U or 0.
In the further configurations X2, X3 and X4 the large and small hands have different angle positions. Three display elements Fl and F2 have always to be energized, these always including two which lie on the same pole radius and thus in the same circle sector, the single electrodes of which as stated receive the actuation voltage V3 through the relevant first element connection.
In the case of the display configuration X2 the small -- 25 ~
~3~3~
hand, -that is the third display element, lies in a different circle sector from the large hand, but its single electrode E is connected to the same element connection as the single electrodes of the other two display elements. As in configuration Xl all other element connections receive the actuation voltage V2. The two first group connections ancl the further group connection allocated to the third display element to be energized are charged with the actuation voltage Vl, while all the rest of the group connections are charged with the actuation voltage V2.
In the case of configuration X3, the small hand, that is the third display element, lies in the same circle sector as the other two display elements to be energized. The single electrode of this third display element receives the actuation voltage V2 through the associated element connection, while the acutation voltage Vl is applied to the remaining element connections. The actuation voltages Vl and V0 are present on the two first group connections, namely in such a way that the outer group electrode of the relevant circle sector has the actuation voltage Vl and the inner group electrode the actuation voltage V0. All the rest of the group connections receive the actuation voltage V2.
Finally in the case of the fourth display configuration X4 the third display element to be energized is situated in a different circle sector from the two first display elements and moreover is connected in its single electrode to a different element connection from these. The single electrode of the third display element receives the actuation voltage Vl through the associated element connection, while the actuation voltage V2 is present on the ~a ~3Z~73~
remaining element connections. The two first group connections which are allocated to the circle sector of the large hand both receive the actuation voltage Vl, while the group electrode of the third display element is charged with the actuation vol-tage V3 through its group connection. Again the actuation voltage V2 is present on the rest of the group connections.
Figure 6 shows a variant oF the display in which, in the case of coincidence of the hands, the two display elements which are immediately adjacent on the left and right to the energized display element in the inner circle, are additionally energized. For this purpose, there are the two possible display configurations characterized in Figure 4 by Xl' and X2', which differ in that in the case of Xl' all four display elements to be energized lie in the same circle sector, while in the other case - X2' - three display elements lie on the edge of the one circle sector and one display element on the adjacent edge of the next circle sector. Starting from configuration Xl, the display configuration Xl' is generated in that the inner group electrode of the circle sector is charged with VO
instead of with the actuation voltage Vl, the actuation vnltage V2 is fed to the single electrodes of the two additional adjacent display elements through their single connections, and the actuatinn voltage Vl is fed to all the rest of the element connections. The display configuration X2' is realized, starting from configuration II, in that the inner group electrode of the circle sector in which three display elements for energization lie, is charged with actuation voltage VO instead of with Vl, further the actuation voltage V2 is fed to the single electrode of the additional display element in the 73~
circle sector with the three display elements, through the corresponding element connection, and finally all other element connections are charged with the actuation voltage Vl. On account of the described guidance of -the conductors Le the single electrode of S the single display element to be energized in the other circle sector receives the actuation voltage v3 through the first element connection.
Claims (18)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. A method for the selectively controlling excitation of a plurality of electrically responsive elements of the type having element electrodes and group electrodes which are separated from each other by a crystalline liquid, each group electrode being common to a plurality of an equal number of element electrodes, each of the element electrodes and the opposed group electrode with the liquid-crystal interposed therebetween constituting a liquid crystal display unit, each of the elements having its own element electrode, each of the elements being excited by the application to its respective element electrode and the opposed group electrode of voltages creating a voltage greater than a predetermined operating voltage across that element, and each element electrode opposite to one group electrode being electrically connected to one of the element electrodes opposite to at least one other group electrode, the so-connected element electrodes forming sets of element electrodes;
continuously applying a positive fundamental voltage to one group electrode and a negative fundamental voltage of equal absolute value to another group electrode, and applying to at least one of the sets of element electrodes an excitation voltage to excite at least a selected element in that set, said excitation voltage having a value such that the difference between said excitation voltage and said fundamental voltage applied to the selected element electrodes and its opposed group electrodes, respectively, equals or exceeds the operating voltage.
continuously applying a positive fundamental voltage to one group electrode and a negative fundamental voltage of equal absolute value to another group electrode, and applying to at least one of the sets of element electrodes an excitation voltage to excite at least a selected element in that set, said excitation voltage having a value such that the difference between said excitation voltage and said fundamental voltage applied to the selected element electrodes and its opposed group electrodes, respectively, equals or exceeds the operating voltage.
2. A method as claimed in claim 1, wherein said excitation voltage is one of four voltages of serially increasing value in equal increments.
3. A method as claimed in claim 2, wherein at least two of said excitation voltage values are respectively equal to said positive fundamental voltage and said negative fundamental voltage.
4. A method as claimed in claim 1, in which said excitation voltage differs by an amount at least equal to three times the fundamental voltage applied to the group electrode on which the selected element is located.
5. A method as claimed in claim 4, in which said excitation voltage differs by an amount not substantially in excess of five times the voltage applied to the group electrode on which the selected element is located.
6. A method as claimed in claim 1, in which said excitation voltage and one of said fundamental voltages are alternating voltages having the same frequency and having opposite polarity with respect to each other.
7. A method as claimed in claim 1, comprising applying to at least one other of the sets of element electrodes an excitation voltage to excite at least a selected element in the latter set, said excitation voltage having a value that differs by an amount substantia11y in excess of said fundamental voltage applied to the group electrode on which the second selected element is located.
8. A method as claimed in claim I, in which said excitation voltage differs from said excitation voltage by an amount not substantially in excess of said fundamental voltage applied to the group electrode on which the selected electrode is located.
9. A method as claimed in claim 1, in which said excitation voltage is an overvoltage that differs from the fundamental voltage applied to said one group of electrodes and the fundamental voltage applied to said one other group of electrodes by an amount substantially in excess of said absolute value of said fundamental voltages.
10. A quasi-analog watch display device having a number of separate display elements each capable of actuation through a single electrode and further electrode, which elements are arranged in two concentric circles for the indication of hours and minutes, wherein the display elements of each circle are divided into several groups each of the same size per circle and all display elements of one group comprise as the second electrode a common group electrode provided with a group connection, the group electrodes of the two circles being disposed in pairs in one and the same circle sector, and several element connections being connected with a single electrode of a display element from each group through conductors which extend exclusively radially between two adjacent display elements of the two circles and from circle sector to circle sector alternately on the inner and outer edges of the two circles substantially tangentially or on circular paths.
11. A watch display device as claimed in claim 10, wherein the element connections lie on the outer edges of the two circles.
12. A watch display device as claimed in claim 10, wherein the display elements have each the configuration of elongated, radially directed strips.
13. A watch display device as claimed in claim 10, wherein the display elements of the inner circle are longer than the display elements of the outer circle.
14. A method for the static actuation of the watch display device, the display elements of which all have an equal threshold voltage lying close above a value U and a switch-on voltage amounting to approximately 2U, in which for the generation of a specific display different actuation voltages are fed to the group connections and the element connections in selected combinations, which voltages become effective by pairs with their difference on the individual display element, wherein four actuation voltages V0, V1, V2 and V3 are used of which the actuation voltages V1, V2 and V3 with the actuation voltage preceding form a difference voltage U and the actuation voltages V2 and V3 with the actuation voltage V0 difference voltages 2U and 3U respectively, a first selected element connection is charged with the actuation voltage V3, and the other element connections, two first group connections allocated to one and the same selected circle sector and a further selected group connection have applied thereto actuation voltages in one of the following four combinations:
I) V1 and/or V2 are applied to all other element connections, V1 and/or V0 to the two first group connections;
II) V1 and/or V2 are applied to all other element connections, V1 and/or V0 to the two first group connections and to the further group connections;
III) V2 is applied to a further, selected element connection, V1 to the remaining element connections, V1 and V0 to the two first group connections;
IV) V1 is applied to a further selected element connection, V2 to the rest of the element connections, V1 to the two first group connections, V3 to the further group connection;
and the remaining group connections having applied thereto the actuation voltage V2.
I) V1 and/or V2 are applied to all other element connections, V1 and/or V0 to the two first group connections;
II) V1 and/or V2 are applied to all other element connections, V1 and/or V0 to the two first group connections and to the further group connections;
III) V2 is applied to a further, selected element connection, V1 to the remaining element connections, V1 and V0 to the two first group connections;
IV) V1 is applied to a further selected element connection, V2 to the rest of the element connections, V1 to the two first group connections, V3 to the further group connection;
and the remaining group connections having applied thereto the actuation voltage V2.
15. A method as claimed in claim 14, wherein in the case of the combinations I) and II) the two first group connections and the further group connection have applied thereto the actuation voltage V1 and all other element connections have applied thereto the actuation voltage V2.
16. A method as claimed in claim 14, wherein in the case of combination I) and in the case of combination II) two further selected element connections or one further selected element connection have or has applied thereto the actuation voltage V2, the remaining element connections having applied thereto the actuation voltage V1 and the two first group connections having applied thereto the actuation voltages V1 and V0.
17. A method as claimed in claim 14, wherein alternating current voltages are used as actuation voltages, of which the actuation voltages V3 and V2 equal in phase with one another are shifted in phase by 180° in relation to the actuation voltages V1 and V0 equal in phase with one another.
18. A method as claimed in claim 17, wherein the actuation voltages V3 and V0 have the effective value 1.5U and the actuation voltages V2 and V1 the effective value 0.5U.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19782803899 DE2803899C2 (en) | 1978-01-30 | 1978-01-30 | Method for controlling a quasi-analog clock display device |
| DEP2803899.5 | 1978-01-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1132734A true CA1132734A (en) | 1982-09-28 |
Family
ID=6030707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA318,932A Expired CA1132734A (en) | 1978-01-30 | 1979-01-02 | Liquid-crystal display device |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1132734A (en) |
| DE (1) | DE2803899C2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2834387C3 (en) | 1978-08-05 | 1981-04-16 | Eurosil GmbH, 8000 München | Electro-optical time display device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2410527C3 (en) * | 1973-03-08 | 1983-11-03 | Casio Computer Co., Ltd., Tokyo | Electronic time display device |
| GB1472260A (en) * | 1973-10-29 | 1977-05-04 | Murrell N | Electro optical display system in a time-piece |
| DE2551542A1 (en) * | 1975-11-17 | 1977-05-26 | Joachim Reich | ELECTRONIC CLOCK |
| GB1599667A (en) * | 1977-05-12 | 1981-10-07 | Murrell N J | Electrooptical analogue display with reduced connections |
-
1978
- 1978-01-30 DE DE19782803899 patent/DE2803899C2/en not_active Expired
-
1979
- 1979-01-02 CA CA318,932A patent/CA1132734A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2803899C2 (en) | 1983-05-26 |
| DE2803899A1 (en) | 1979-08-16 |
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