GB2119994A

GB2119994A - Liquid crystal displays

Info

Publication number: GB2119994A
Application number: GB08213161A
Authority: GB
Inventors: Harry Suzuki; Gerald Anthony Garies
Original assignee: CONIC SEMICONDUCTOR Ltd
Current assignee: CONIC SEMICONDUCTOR Ltd
Priority date: 1982-05-06
Filing date: 1982-05-06
Publication date: 1983-11-23
Also published as: GB2119994B

Abstract

A liquid crystal display comprising at least one seven segment alphanumeric display character (8) and an additional pattern in the form, e.g. of a face. When selected segments A to G of the alphanumeric character (8) are energised for display, connecting portions of the pattern (12, 14, 16, 18) are similarly energised. The seven segment character is typically the minutes character of a watch display such that the pattern (face) changes with each change in minute displayed. <IMAGE>

Description

SPECIFICATION Liquid crystal displays This invention relates to liquid crystal displays (LCD's).

LCD's are a very popular means of displaying electronically controlled images. Probably the most extensively used LCD's are based on the well known seven segment alphanumeric displays, such as the 3 < digit seven segment LCD's used in electronic watches. The drive electronics for such LCD's (often based on CMOS circuitry to reduce current drain) are standard circuits readily available commercially. LCD's have not been restricted to such seven segment displays and any manner of display patterns have been created. However, for such specialised patterns it is necessary to provide customised drive electronics which are more expensive than the readily-available drive circuits.An alternative approach, which has been employed particularly with handheld electronic games, is to build up more complex patterns from seven segment display modules, but the results sometimes leave much to be desired.

The present invention is concerned with enabling a variety of patterns to be provided by an LCD, but by employment of standard drive electronics such as available for seven segment displays.

According to a first aspect of the invention there is provided an LCD comprising at least one seven segment alphanumeric display character and at least one additional pattern, said character and pattern being connected such that when selected segments of the character are energised for display by display drive means, corresponding connecting portions of said pattern are similarly energised.

According to a second aspect of the invention, the first aspect is modified such that the pattern is driven directly by said display drive means, independently of the drive energisation of any seven segment display characters.

Figure 1 illustrates the front pane of an LCD according to the invention for use in an electronic watch and, Figure 2 illustrates various patterns obtainable from an LCD using the pane similar to that of Fig. 1.

Referring to Fig. 1, there is shown the front pane of a 3 2 digit seven segment display for use in an electronic watch. In this example the LCD is designed for use with static direct drive electronics: that is with a common back pane and the front pane/back pane segments unmultiplexed.

The LCD comprises the usual conductive pattern carried on a glass substrate including a two segment "tens hours" character 2, seven segment "unit hours" character 4, and seven segment "tens minute" and "unit minute" characters 6 and 8. In static direct drive, each segment is individually connected to the drive electronics via connector areas 10, only some of which are illustrated for clarity. For character 8, the segments are identified A to G and their connector areas 1 0A to 1 OG. The characters are energised in conjunction with a single conductive area on the back pane of the LCD (not shown). Thus far, the LCD is a normal 3Q digit display for static direct driving.

To the right of character 8 are four further conductive segments 12, 14, 16, 1 8 visually giving the impression of a face (coloured black).

Segment 1 2 is electrically connected to segment G of character 8, and segment 14 to segment C. Segments 1 6 and 1 8 lead out to connector areas X and Y respectively.

The LCD is assembled in the watch as normal, but additionally an external connection is made between selected pairs of segments A, B, D, E, F to segments 1 6 and 1 8 through their respective connector areas. In this example, it will be assumed that 1 f is externally connected to A via X and 1 OA, 1 8 to E via Y and 1 OE (shown in dotted detail in Fig. 1). With this arrangement is changing sequence of six different face patterns is provided with the sequence of changing digits shown by character 8. The pattern, as character 8 goes from 1 to O is illustrated in Fig. 2, in the second column of faces, headed C-G, A-E.

Referring to this column in Fig. 2, when character 8 displays "1", this also shows a side face. This arises because the "1" is created by energisation of only segments B and C. Energisation of C simultaneously energises 1 4. The remaining segments of the face remain invisible. When character 8 displays "5" (energisation of segments A, C, D, F, G) segments 12, 14 and 1 6 are simultaneously energised to display a full face but without a collar (segment 1 8 remaining invisible as segment E is unenergised).

The particular interconnection combination described is advantageous in that, of the six possible faces which may be displayed, a different one is shown with each successive change of minute in character 8. If the interconnections are between different segments then a change in digit for character 8 may not produce a change of face. An example is when the external connections are A to X and D to Y (the first column of faces in Fig. 2). In this instance the same face is displayed with digits 3, 5, 6, 8 and 9, since A, D, C, and G are energised for each of these digits, and these segments also energise 1 2 to 1 8.

It is not essential that external connections be made between specified segments, since by varying the patterning technique all connections may be made internally either on the front pane or (if the pattern is distributed between front and back panes) by intercon necting between the two panes. The invention is also not restricted to direct drive electronics and a variation in patterning will enable a multiplexed drive (with fewer drive lines) to be employed. By interconnecting segments in pairs, for example, a biplexed design may be achieved as is known in the art.

In an alternative embodiment of the invention which is not illustrated, the face pattern consists of one or more conductive segments that are not connected either externally or internally to segments of a digit character.

These face pattern segments have separate leads, similar to X and Y above, but are driven directly from one of the drive lines of the display electronics. For example, with CMOS electronics designed for a 32 digit alarm watch, the face pattern may replace an alarm pattern, with the face visible and changing when the alarm function is activated.

The invention is not limited to faces but may embrace other designs, including ones that change or not.

Claims

1. A liquid crystal display comprising at least one seven segment alphanumeric display character and at least one additional pattern, said character and pattern being connected such that when selected segments of the character are energised for display by display drive means, corresponding connecting portions of said pattern are similarly energised.

2. A display according to claim 1 wherein the pattern comprises one or more conductive portions on either or both of a front and back pane of the display, each conductive portion being connected electrically to a different conductive area forming a segment of the seven segment character.

3. A display according to claim 2 wherein the conductive portions forming the pattern and the conductive areas forming the segments of the seven segment character are disposed on the same pane with at least some of the interconnections therebetween being provided by conductive links disposed on said pane.

4. A liquid crystal display substantially as hereinbefore described with reference to Fig.

1 of the drawings.

5. An electronic watch comprising a liquid crystal display as claimed in any of claims 1 to 4.

6. An electronic watch according to claim 5 wherein the pattern is connected to segments of the right-most seven segment character of the display.

7. A modification of the display as claimed in claim 1 wherein the pattern is driven directly by said display drive means, independently of the drive energisation of any seven segment display characters.