GB1596705A

GB1596705A - Electro-optic display device

Info

Publication number: GB1596705A
Application number: GB1540678A
Authority: GB
Original assignee: Citizen Watch Co Ltd
Current assignee: Citizen Watch Co Ltd
Priority date: 1977-04-19
Filing date: 1978-04-19
Publication date: 1981-08-26
Also published as: DE2817054A1

Description

(54) ELECTRO-OPTIC DISPLAY DEVICE (71) We, CITIZEN WATCH COMPANY LIMITED, a corporation organized under the laws of Japan, of No. 1--1, 2-chome, Nishishinjuku, Shinjuku-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a display device which makes use of liquid crystals, a material elastically deformable in an electric field, an incandenscent body or exothermic body or a heat-sensitive material capable of coloration, and more particularly to a display device in which the electrodes of display elements are connected in matrix form, the optical characteristics being substantially dependent upon the rms value of the applied periodic voltage.

In a matrix drive system, display elements are arranged in n-rows and mcolumns. If a row drive signal r is applied to a row electrode and a column drive signal C to a column electrode, the rms value of the voltage impressed upon a display element at a cross-point is given by

for one period T of the drive signals. When the waveforms of the drive signals rand C are applied to produce a desired pattern such that certain display elements attain a state (hereinafter referred to as the ON state) where they are impressed with a high rms voltage while the other display elements attain a state (hereinafter referred to as the OFF state) where they are impressed with a low rms voltage, the operation margin is expressed by the ratio ug=Von/Voff where Von is the minimum voltage applied among the display elements in the ON state, and Voft is the maximum voltage applied among the display elements in the OFF state. Although the absolute values of Von, Voff change depending upon the power source voltage, the operation margin is a constant determined by the drive system and serves as the criterion by which the quality of the drive system can be judged.

In a twist-type nematic liquid crystal display system, variations in optical characteristics which accompany voltage variations are gradual; hence, good contrast cannot be obtained if the drive system does not exhibit an operation margin on the order of 1.7 to 2. In particular, as large an operation margin as possible is preferable in order to satisfy the demand for attractive reflective-type displays resistant to power source voltage fluctuations over a wide temperature range, especially in the case of displays for timepieces.

In drive systems according to the prior art, the row drive signals for driving an n-row matrix were specific signal waveforms which were unrelated to the display pattern and which adopted a waveform having symmetry between mutually adjacent row signals. The drive signals of a drive signal system capable of forming a display of combinations of all patterns, i.e., 2n patterns, were applied to the row and column electrodes. The operation margin was therefore small, for example,

in the case of a 1/2 bias method using two power sources and three potential levels, and

in the case of a 1/3 bias method using four power sources and four potential levels. Thus, it was considerably difficult to drive a matrix having rows for four or more digits.

When displaying numerals, characters, graphs or animations, there are many cases where there is a relationship to a certain extent between display elements which attain the ON state and display elements which attain the OFF state; hence, if the display element connections are taken into account, there is no need to make connections which correspond to all 2n patterns.

On the other hand, among 2n patterns there are desirable patterns which are easy to drive, that is, those for which a large operation margin can easily be obtained, and those which are difficult to drive, that is, undesirable patterns which develop difficulties when attempting to enlarge the operation margin. What really decide the the operation margin are the cases where combinations of specific patterns develop between several columns. Since the conventional drive method adopted drive signals of a drive system capable of correspondance with all patterns including the worst patterns, the operation margin was small. According to the present invention, however, display elements are connected so as not to produce the worst patterns, or to produce only those combinations of patterns that are easy to drive, and a drive system suited to a desired pattern is adopted, wherein drive signals which provide a large operation margin, or which require only a small number of power sources, are applied to the column and row electrodes. This allows an attractive display with good contrast to be readily obtained. The present invention is particularly suitable for use in display devices which employ twist-type nematic liquid crystal displays of reflective type as are found in timepieces and calculators.

The drive signal waveforms will now be described in terms of vector representation. A single period of a drive signal waveform will be divided into several intervals tl, t2, ... tj, and the drive signal will have the same potential throughout each interval. If T is the duration of a single period, tj the width of the i-th interval, and lj the potential of the drive signal, then a j-dimension vector e is defined in which

is the i-th element, whereby the drive signal waveform E is brought into correspondance with the point e on thej-dimension rectangular coordinate graph.

If n signal waveforms A1, A2 ... An are divided into intervals in similar fashion, they will be expressed as a1, a2,... an when bought into correspondance with vectors.

The distances between the coordinates ak, al are equivalent to the rms value of the potential differences between the waveforms Ak and Al. Further, the waveforms A1, A2 ... An can be converted to vectors a,', a2, ... an' by dividing the waveforms in a different manner. The coordinates a, a2... an and a,', a21... a,' are congruent. In other words, the two sets of coordinates can be made to coincide by means of rotational and parallel movement as well as inverse transformation. The transformation from vectors to signal waveforms is performed by reversing the above procedure. In such a case, since the method of dividing the intervals is not unique, a transformation to A,', A21... A,' in addition to A1, A2... An is possible when converting the vectors ar, a2... an to signal waveforms. However, the sets of signal waveforms A1, A2... A,, obtained from the transformation of vectors a, a2... and the vectors a,', a21... a,' obtained by the rotational and parallel movement as well as the inverse transformation of vectors a1, a2... a, form a single set of waveforms having the same properties from the point of view of the rms voltage impressed upon the display elements. If the i-th display element can be made 0 with regard to all vectors at the time of the rotational and parallel movement, the number of dimensions can be reduced by 1 and, if non-zero display elements are added to all vectors, the number of dimensions can be increased.

What is referred to as the "worst pattern" may be defined as follows. When row drive signals r1, r,... rn satisfy the following conditions, the row drive signals are said to possess symmetry. If the mean value of the potential of a row drive signal over successive instants of time is taken as rO, for one period T of a drive signal, 1 #T(ri-ro)2dt T is equivalent to a constant value R2 regardless of i, and 1 #T(ri-ro)(rj-ro)dt T is equivalent to a constant value -R2/(n-l) regardless of i and j when t andj are unequal. These conditions may be expressed in terms of vectors as follows. r, r2 ... rn lie on the periphery of a sphere or (n-l) dimensioned hypersphere the center of which is rO, and, when n is 3 or more, any three points ri, rj, rk define an equilateral triangle the length of each side of which is 2nR2/(n-1). C shall be referred to as a column drive signal which, in an n-row matrix, is applied to a column to turn ON display elements in an m rows and turn OFF display elements in (n-m) rows. The sum of the squares of the voltage at display elements in the OFF state, namely

can be expressed as

adopting rOff as the mean value of the OFF row signal. The sum of the squares of the voltage at display elements in the ON state, namely

is expressed as

adopting 5 as the mean value of the ON row signal. To maximize Son and hold Soff constant, C should lie on the linear extension of ruff, rOn if expressed in terms of vectors. Using a positive coefficient A, it is most advantageous to obtain the following value for C, namely

represents the sum total with regard to the ON rows. If the above relation is attained, the voltages Von and Voff at respective ON and OFF display elements are given as follows when the row drive signal possesses symmetry: Von2=In-l t2(n-m)A+m(n-m)A2J . R2 (n-l) (1) Voff={n-1-2mA+m(n-m)A] . R2 (n-l) (2) Von2-Voff=2nA R2/(n- 1) The number of ON display elements of the worst pattern and the optimum value of A at this time can be determined on the basis of the above equations. The procedure is (a) tentatively to decide the value of Von2, (b) obtain values of A corresponding to each Von2 with regard to values of m from 1 to (n-l), and (c) obtain values of Voff2 corresponding to each A with regard to values of m from 1 to (n-l), and to let the maximum value be (VOf?)max including the case where m=0.

According to this procedure, (Voff2)max is obtained as a function of Von2; Von2 is determined so as to maximize the operation margin, and m, which determines (VOffl)m,,x, becomes the number k of ON display elements of the worst pattern.

According to the present invention, there is provided an electro-optic display device comprising a plurality of groups of 7 display elements (a) through (g) as hereinafter defined, each group being arranged so as to display any numeral from 0 to 9 and each having first, second and third row electrodes and first, second and third column electrodes connected in the configuration of a 3-row 3-column matrix, the first and third row electrodes being connected in respective groups to two different display elements and the remaining second row electrode being connected in respective groups to three display elements, while in each group the first and second column electrodes are connected to three different display elements of the respective group and the remaining third column electrode is connected to the remaining single display element among said 7 display elements, or the respective group.

In the accompanying drawings, in which: Figure 1 is a graph showing the characteristic of the operation margin in a matrix drive system; Figure 2 is a front view of a display device of 7 display segments for displaying a numeral as referred to in the claims of the present invention; Figures 3A and 3B are tables showing which display elements are turned on in the display device of Figure 2 to produce the numerals from 0 to 9; Figures 4A, 4B, 4C; Figures 5A, 5B and Figures 6A, 6B are schematic views of preferred embodiments of connection diagrams for a case in which the present invention is applied to a time display device in a timepiece; and Figures 7A, 7B and 7C are schematic views of another preferred embodiment of connection diagrams for a case in which the present invention is applied to a time display device in a timepiece.

Figure 1 shows the relationships among the above-mentioned equations, with n=5 fixed and A varying and with m as a parameter and Von2-Voffl taken along the X-axis and Toff2 taken along the Y-axis. A straight line 2 and parabolic 3, 4, 5, 6 pass through the point (0, R2). Von2 is constant along the straight line 1 having a slope of -1, and the value of Voff, according to procedure (c), is found at the points of intersection between straight line 1 and the parabolic 2, 3, 4, 5, 6. (Voff2)max is located at point 7 which is the point of intersection furthest to the upper left.

Substituting Von2, the point which represents (Voff2)max moves along the curve 8 (indicated by the bold line) which is formed by connecting the minimum portions of the existing curves in the drawing. In order to obtain a large operation margin a, Voff/(Von2-Voffl) should be as small as possible; hence, when a point P is placed on curve 8, a stright line connecting P and the origin 0 most favorably contacts the curve. This represents the limit of the operation margin of a drive signal system capable of displaying all combinations of patterns.

Only one integer exists which satisfies the inequality

where n'3. It can be understood that the straight line OP contacts the parabola for the case where the number of ON display elements m=k. In this case, the constant A and operation margin a are given by

When n=2, the point P is located at the intersection of the straight line for m=0 and the parabola for m=l; hence, A=2 and a=3.

In the drive signal system capable of displaying all combinations of patterns, the practical system is not necessarily limited to that which can produce row drive signals having an ideal value of A for the sake of obtaining suitable power source voltage and limited the number of such sources, for example in the prior art using a 1/2 or 1/3 bias method. Even so, the operation margin is restricted by the state which turns ON k display elements in a n-row matrix, and the worst pattern for n=3 is the case where k=l as found by the abovementioned inequality, namely the case where there is simultaneous coexistence of all combinations in which there is a row where one display element of one column of a 3-column matrix is ON while those in the remaining two columns are OFF.

It is therefore the object of the present invention to accomplish matrix drive for n=3 while eliminating the worst possible pattern, wherein 7 display segments are for displaying numerals from 0 to 9.

A detailed description of a preferred embodiment of the present invention will now be made with reference to the accompanying drawings.

Figure 2 shows the arrangement of 7 display elements a through g which are assigned corresponding reference numerals 11 through 17. Hereafter, the relative positional relationships of the display segments corresponding to the symbols a through g will be the same as those of Figure 2 for other groups of such elements. If there are a plurality of such groups, they will be distinguished by adding the suffix i (a positive integer); in other words, the designation will be a-g1.

Figure 3 illustrates which elements of Figure 2 are turned ON or OFF to display numerals from 0 to 9. Elements to be turned ON to display the corresponding numeral are indicated by 0. Thus, Figure 3A shows a case where the numeral 7 is displayed by turning ON the three display elements a, b and c, and Figure 3B shows a case where the numeral 7 is displayed by turning ON the four display elements a, b, c, andf. In Figure 3A, noting the elements connected by the arrows, it can be seen that, among the combinations of three elements a, b and c, a condition does not exist in which only one of the elements in each set of three is turned ON when displaying each of the numerals 0 through 9, and the same can be said for combinations of the three elements d,f and g. In Figure 3B, again noting the arrows, the same condition holds for combinations of display elements a,f and g, and for b, c and d. Accordingly, if, in the case of Figure 3A, column electrodes are connected respectively to one group of three elements a, b, and c, one group of three elements d, f, and g and to display element e, then it would be possible to eliminate the condition for the worst pattern, namely the condition in which, for any column electrode, the display element on one row electrode is turned ON while the display elements corresponding to the other two rows are turned OFF. The same can be said for the arrangement of Figure 3B if column electrodes are similarly connected respectively to one group of three elements a, f and g, one group of elements b, c and d, and to display element e. If a graph similar to that of Figure 1 is now drawn for n=3 and excluding the curve for m=l, an undesirable pattern which restricts the operation margin can be understood to occur at the intersection of the straight line m=0 and the curve for m=2. The ideal value for A in this case is 2, and the limit imposed on the operation margin is therefore 4. For the sake of reference, the value of A is 1, and the limit of the operation margin is therefore 2, for the condition of the worst pattern where n=3.

Figures 4A to 4C shows an example of a case where the display pattern of Figure 3A is applied to a time display device. Figure 4A depicts the arrangement of display elements, in which reference numerals 18, 19, 20 denote respective groups of 7 display elements each, 21 denotes the display elements of the tens of hours digit, and 22 designates the display elements for a colon used to separate minutes from hours. Figure 4B shows the row electrode connections, in which 23, 24 and 25 denote the row electrodes. Figure 4C illustrates the column electrode connections, in which reference numerals 26 through 34 denote column electrodes. As shown in Figure 4B and 4C, the electrode-optic display device comprises a plurality of groups of 7 display elements whose electrodes are connected in the configuration of a 3-column and 3-row matrix so as to form display numerals, the first and second column electrodes from among three column electrodes are connected -to respective groups of three different display elements chosen from the 7-display elements, the remaining third column electrode is connected to the remaining single display element. In each group of 7 display elements, more specifically, electrodes of display elements corresponding to those a, b and c of Figure 2 are connected to the first column electrode 26, 29 or 32, electrodes of display elements corresponding to those d, f and g are connected to the second column electrode 27, 30 or 33, the remaining electrode of the display element corresponding to that e is connected to the remaining third column electrode 28, 31 or 34. In each group of 7 display elements, moreover, the electrodes of display elements a and f are connected to the first row electrode 23, the electrodes of display elements b, e and g are connected to the second row electrode 24, and the electrodes of display elements c and d are connected to the remaining third row electrode 25. This arrangement makes it possible to eliminate the condition in which, regardless of the row electrode chosen, one display element on one column electrode is turned ON while the display elements corresponding to the other two columns are turned OFF. In other words, with regard to column electrodes 26, 27, 29, 30, 32 and 33, a condition in which the display element corresponding to any one row electrode is ON while the display elements corresponding to the other two row electrodes are OFF does not exist, as made clear with respect to Figure 3A. With regard to column electrode 28, although there does exist a condition in which display element e,8 and one of the two display elements 21 attain the ON state, the column electrode 28 does not intersect row electrode 25 so that, in a case where only element e18 is to be turned ON, drive signals which induce the ON state are supplied both row electrodes 24, 25, and in a case where only element 21 is to be turned ON, drive signals which induce the ON state are supplied to both electrodes 23, 25, whereby it is possible to eliminate the condition wherein only the display element corresponding to any one of the row electrodes is turned ON while the display elements corresponding to the other two row electrodes are turned OFF. What applies for column electrode 28 also holds for column electrode 31. Although column electrode 34 does have an intersection with row electrode 23, the intersection does not constitute a display element. Thus, if it is desired to turn display element e20 ON, a drive signal which induces the ON state is supplied to row electrodes 24 and 25, and when it is desired to turn the display element OFF, a drive signal which induces the OFF state is supplied to all three of the row electrodes, whereby the point of intersection with row electrode 23 does not attain the ON state. This also makes it possible to eliminate the condition wherein only one display element corresponding to any one row electrode is turned ON while the display elements corresponding to the other row electrodes are turned OFF.

In accordance with the above description of the three column electrodes corresponding to the 7 display segments a through g, the column electrode connected to single display element e may be further connected to one more display element from another 7-element group, and this one other element can be turned ON-and OFF independently of the display element e. In Figure 4A, this other display element is the display element 21 of the tens of hours digit, or the colon display element 22. However, connections can also be made to AM and PM display elements or to display elements used for other kinds of indices. Further, the column electrode 34 in Figure 4 can be connected to one other display element, other than e20, to be arbitrarily turned ON and OFF. By leading out all the column electrodes 26-34 from one side of the display elements as shown in Figure 4C, the lead wire of one other display element, in addition to element e20, capable of connection to column electrode 34 can be disposed at any convenient position on the side of column electrodes 26-34 which is opposite to the side of the corresponding electrode lead-out wires (in the drawing, the opposite side would be the bottom side of display elements 18-22). Alternatively, the lead wires could be disposed between those of column electrodes 29 and 34 on the same side from which all the wires are led out.

Figure 5 shows a case in which there are two groups of display elements of 7 segments each, wherein corresponding display elements e in each group are connected to a single column electrode, and each display element e is arbitrarily turned ON and OFF. Figure 5A is an example of the row electrode connections in which 35, 36, 37 are the row electrodes, and Figure 5B shows an example of the column electrode connections, in which 38 through 42 are five column electrodes.

It is possible in this case to reduce by one the number of column electrodes corresponding to the two groups of display elements.

Figure 6 shows an example of a case where the display pattern of Figure 3B is applied to a time display device. Here, the arrangement of display elements is identical to that of Figure 4A. Figure 6A shows the row electrode connections and 6B the column electrode connections, in which row electrodes are designated at 43, 44, 45, and column electrodes at 46 through 54. As in the embodiment of Figure 4, the arrangement is driven as a three row matrix, and, regardless of the column electrode chosen, it is possible to eliminate the worst pattern wherein one display element corresponding to any one row electrode is turned ON while the display elements corresponding to the other two row electrodes are turned OFF.

The present invention as described above not only provides a 7-display element connection arrangement that prevents the occurence of the worst pattern which lowers operation margin, but also allows the column electrode connected to the display element e to be connected to one display element other than the 7 elements in a particular group, and makes it possible to arbitrarily turn the other display element ON and OFF independently of the display element e. It is also possible to increase the number of drivable display elements with the same number of column electrodes, or reduce the number of column electrodes needed to drive the same number of display elements.

Figure 7 shows another example of an electro-optic display device according to the present invention. Figure 7A depicts the arrangement of display segments, in which reference numerals 118 through 122 denote respective groups of 7 display segments each, 123 designates the display segments of the tens of hours digit, 124 the display segments for a colon used to separate minutes from hours, and 125 through 131 denote 7 display segments t through z each capable of indicating one of the 7 days of the week Sunday through Saturday. Any one, and only one, of the 7 display segments 125 through 131 is in the OFF or extinguished state while the remaining 6 display segments are all ON, with the position of the single OFF or extinguished display segment indicating the day of the week. Figure 7B shows an example of the row electrode connections, in which reference numerals 132, 133 and 134 denote the row electrodes. Figure 7C illustrate an example of the column electrode connections, in which reference numerals 135 through 150 denote column electrodes. These connections do not permit the row electrode wires and column electrode wires to horizontally overlap at positions other than the positions of the display segments, making it possible to eliminate the condition in which, regardless of the column electrode chosen, a display segment corresponding to one row electrode is turned ON while the displav segments corresponding to the other two row electrodes are turned OFF. In other words, with regard to column electrodes 135, 136, 138, 139, 141, 142, 143, 144, 145, and 146, a condition in which the display segment corresponding to any one row electrode is ON while the display segments corresponding to the two row electrodes are OFF does not exist, as made clear with respect to Figure 3A. Turning now to segment electrodes 147 and 148, it was explained above that a condition does not exist wherein only one of the display segments, in the groups 125-127 and 128-130 of three segments each, attains the ON state. According to this arrangement in which only one of the 7 display segments t through z is turned OFF or extinguished while the other 6 display segments are turned ON, the 7 display segments are connected by means of three column electrodes. However, in a case where the 7 segments t through z are each to be turned ON and OFF in arbitrary fashion, the number of column electrodes corresponding to the 7 display segments t through z is decreased by one to give a total of four, and the number of display segments connected to each of the four column electrodes must be two or less.

The present invention as described above not only provides a 7-display segment connection arrangement for displaying numerals and a 7-display segment connection arrangement for displaying the corresponding 7 days of the week from Sunday to Saturday, wherein the arrangements are adapted to prevent the occurrence of the worst pattern which lowers the operation margin, but also makes it possible to increase the number of drivable display segments with the same number of column electrodes, or reduce the number of column electrodes needed to drive the same number of display segments.

WHAT WE CLAIM IS: 1. An electro-optic display device comprising a plurality of groups of 7 display elements (a) through (g) as hereinbefore defined, each group being arranged so as to display any numeral from 0 to 9 and each having first, second and third row electrodes and first, second and third column electrodes connected in the configuration of a 3-row 3-column matrix, the first and third row electrodes being connected in respective groups to two different display elements and the remai

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the arrangement is driven as a three row matrix, and, regardless of the column electrode chosen, it is possible to eliminate the worst pattern wherein one display element corresponding to any one row electrode is turned ON while the display elements corresponding to the other two row electrodes are turned OFF. The present invention as described above not only provides a 7-display element connection arrangement that prevents the occurence of the worst pattern which lowers operation margin, but also allows the column electrode connected to the display element e to be connected to one display element other than the 7 elements in a particular group, and makes it possible to arbitrarily turn the other display element ON and OFF independently of the display element e. It is also possible to increase the number of drivable display elements with the same number of column electrodes, or reduce the number of column electrodes needed to drive the same number of display elements. Figure 7 shows another example of an electro-optic display device according to the present invention. Figure 7A depicts the arrangement of display segments, in which reference numerals 118 through 122 denote respective groups of 7 display segments each, 123 designates the display segments of the tens of hours digit, 124 the display segments for a colon used to separate minutes from hours, and 125 through 131 denote 7 display segments t through z each capable of indicating one of the 7 days of the week Sunday through Saturday. Any one, and only one, of the 7 display segments 125 through 131 is in the OFF or extinguished state while the remaining 6 display segments are all ON, with the position of the single OFF or extinguished display segment indicating the day of the week. Figure 7B shows an example of the row electrode connections, in which reference numerals 132, 133 and 134 denote the row electrodes. Figure 7C illustrate an example of the column electrode connections, in which reference numerals 135 through 150 denote column electrodes. These connections do not permit the row electrode wires and column electrode wires to horizontally overlap at positions other than the positions of the display segments, making it possible to eliminate the condition in which, regardless of the column electrode chosen, a display segment corresponding to one row electrode is turned ON while the displav segments corresponding to the other two row electrodes are turned OFF. In other words, with regard to column electrodes 135, 136, 138, 139, 141, 142, 143, 144, 145, and 146, a condition in which the display segment corresponding to any one row electrode is ON while the display segments corresponding to the two row electrodes are OFF does not exist, as made clear with respect to Figure 3A. Turning now to segment electrodes 147 and 148, it was explained above that a condition does not exist wherein only one of the display segments, in the groups 125-127 and 128-130 of three segments each, attains the ON state. According to this arrangement in which only one of the 7 display segments t through z is turned OFF or extinguished while the other 6 display segments are turned ON, the 7 display segments are connected by means of three column electrodes. However, in a case where the 7 segments t through z are each to be turned ON and OFF in arbitrary fashion, the number of column electrodes corresponding to the 7 display segments t through z is decreased by one to give a total of four, and the number of display segments connected to each of the four column electrodes must be two or less. The present invention as described above not only provides a 7-display segment connection arrangement for displaying numerals and a 7-display segment connection arrangement for displaying the corresponding 7 days of the week from Sunday to Saturday, wherein the arrangements are adapted to prevent the occurrence of the worst pattern which lowers the operation margin, but also makes it possible to increase the number of drivable display segments with the same number of column electrodes, or reduce the number of column electrodes needed to drive the same number of display segments. WHAT WE CLAIM IS:

1. An electro-optic display device comprising a plurality of groups of 7 display elements (a) through (g) as hereinbefore defined, each group being arranged so as to display any numeral from 0 to 9 and each having first, second and third row electrodes and first, second and third column electrodes connected in the configuration of a 3-row 3-column matrix, the first and third row electrodes being connected in respective groups to two different display elements and the remaining second row electrode being connected in respective groups to three display elements, while in each group the first and second column electrodes are each

connected to three different display elements of the respective group and the remaining third column electrode is connected to the remaining single display element among said 7 display elements of the respective group.

2. An electro-optic display device according to claim 1, wherein the third column electrode connected to said single display element among said 7 display elements is connected to one display element other than said 7 display elements.

3. An electro-optic display device according to claims I or 2, wherein the first column electrode is connected to three display elements (a), (b) and (c) from among said 7 display segments (a) through (g), the second column electrode is connected to three display elements (d), (f) and (g), and the third column electrode is connected to the remaining display element (e).

4. An electro-optic display device according to claims 1 or 2, wherein the first column electrode is connected to three display elements (a), (f) and (g) from said 7 display elements (a) through (g), the second column electrode is connected to three display elements (b), (c) and (d), and the third row column is connected to the remaining display element (e).

5. An electro-optical display device according to claim 1, further comprising another group of 7 display elements (t) through (z) including first, second and third row electrodes and first, second and third column electrodes arranged in a matrix configuration for displaying the corresponding 7 different data.

6. An electro-optical display device according to claim 5, wherein the third column electrode from among said another group of 7 display elements is connected to one of said another group of 7 display elements and also connected to one display element of said group of 7 display elements (a) through (g) for displaying the numerals.

7. An electro-optical display device according to claim 6, wherein said one display element is the display element (e) of the group of 7 display elements (a) through (g).

8. An electro-optical display device according to claims 5, 6 or 7, wherein the first, second and third row electrodes of said another group of 7 display segments (t) through (z) are respectively connected to the first, second and third row electrodes of the group of 7 display elements (a) through (g).

9. An electro-optical display device according to claim 8, wherein the first row electrode is connected to first selected ones of said another group of 7 display elements (t) through (z), the second row electrode is connected to second selected ones of said another group of 7 display elements (t) through (z), and the third row electrode is connected to remaining ones of said another group of 7 display elements (t) through (z).

10. An electro-optical display device substantially as shown and described with reference to the accompanying drawings.