Analogue displays for electronic timepieces or meters

• US 4,342,030 A
• Filed: 03/07/1980
• Issued: 07/27/1982
• Est. Priority Date: 03/13/1979
• Status: Expired due to Term

• Current Assignee: National Research Development Corporation
• Original Assignee: National Research Development Corporation
• Inventors: Shanks, Ian A.
• Primary Examiner(s): Curtis, Marshall M.
• Application Number:
  US06/128,059
• Time in Patent Office: 872 Days
• Field of Search: 340/753, 340/754, 340/784, 340/765, 340/774, 340/756, 340/752, 340/783, 368/239, 368/240, 368/242
• US Class Current: 345/38
• CPC Class Codes: G04G 9/062 using multiplexing techniques

Abstract

An analogue display with a panel having an electro-optic medium contained between two sets of electrodes. One set is arranged in a plurality of segments each divided into inner and outer portions. Each portion is planar and has a plurality of digits. The digits of one portion are interposed alternate with, and in between, the digits of the other. The other set has a planar meander configuration modified by an electrode interposed in its folds. The sets of electrodes when registered one over the other define two subsets of different selectable index positions. Selected alternating voltages are applied simultaneously to the electrodes maintaining the panel ON at two selected index positions and OFF elsewhere a dial shaped display area which is other than circular or arcuate, e.g. Preferably the voltages are selected from the set (+2V, +V, -V) of RMS magnitudes (2V_c, V_c, V_c) where V_c is equal to the threshold voltage of the panel. The panel may contain liquid crystal material, as medium, to perform as a dyed phase change, or twisted nematic effect device.

Claims

1. An analogue display comprising in combination:

a display panel;

address means for providing a set of voltage signals to operate the display panel; and

,

selector means, capable of response to input data, for selecting voltage signals from the address means, and for applying these signals to the display panel to enable display of two indices on the display panel against an otically contrasting background;

wherein, the display panel includes;

two parallel substrates;

an electrically sensitive medium contained between the two substrates, the medium being capable of adopting simultaneously in different regions thereof each of two optical states, an ON state, and an OFF state, respectively, in response to different electrical fields developed thereacross;

a first set of electrodes arranged in a plurality of segments, each segment being divided into an inner and an outer portion, each portion being planar and having a plurality of joined digits, the digits of one portion being interposed alternate with and in between the digits of the other portion, the first set of electrodes being mounted on the inwardly facing surface of the first substrate, and connected to the selector means; and

a second set of electrodes having a configuration in which a single electrode is interposed between meandering electrodes in folds formed by the meandering electrodes to form collectively a modified meander structure, the second set of electrodes being mounted on the inwardly facing surface of the second substrate, and connected to the selector means;

the two sets of electrodes being registered one set over the other with alternate digits and alternate meander electrodes defining two subsets of selectable index positions each subset to display a different index; and

,

the selector means being constructed to respond to input data and connected to the two sets of electrodes to drive the panel medium in the ON state at two different selected index positions simultaneously, the panel medium being in the OFF state at all other selectable index positions.

2. A display according to claim 1 wherein the medium is of liquid crystal material.

3. A display according to claim 2 wherein the panel is a dyed cholesteric to nematic phase change device, the material being cholesteric and containing at least one pleochroic dye.

4. A display according to claim 3 wherein the pleochroic dye is an anthraquinone dye having the formula:

##STR3##

5. A display according to claim 3 wherein the display panel includes reflector means arranged to reflect light transmitted through the liquid crystal material.

6. A display according to claim 5 wherein the reflector means is provided by one of the two sets of electrodes, this set of electrodes being of thick reflective, electrically conductive film material.

7. A display according to claim 6 wherein the reflector means is provided by the second set of electrodes.

8. A display according to claim 2 wherein the panel includes two polarizers one to the outside of each substrate,

the liquid crystal material is capable of adopting a 90°

helical twist between the two sets of electrodes, and, the two sets of electrode bearing surfaces and liquid crystal material interact so that the liquid crystal material adopts this helical twist in the OFF state, the two polarizers being aligned relative to each other and to the electrode bearing substrates so to provide a twisted nematic effect device.

9. A display according to claim 8 wherein the two polarizers are crossed and aligned parallel or perpendicular to the liquid crystal alignment directions on the electrode bearing surfaces so to transmit light in the OFF state.

10. A display according to claim 1 wherein the two sets of electrodes are configured to provide a dial shaped display area.

11. A display according to claim 1 wherein the address means is constructed to provide a set of alternating voltage signals (+2 V, +V, -V), the signals +V and -V, respectively, being in-phase and in anti-phase with the signal +2 V, and such that the set of signals, when applied to the panel, have RMS magnitudes (2 V_c, V_c, V_c), the voltage magnitude V_c being no greater than the threshold voltage of the display panel, the selector means being constructed to develop an RMS voltage difference of magnitude 3 V_c across the two different selected index positions, and an RMS voltage difference of magnitude V_c across the other selectable index positions.

12. A display according to claim 11 wherein the set of voltage signals have RMS magnitudes (2 V_c, V_c, V_c) and are applied directly to the panel.

13. A display according to claim 1 wherein the address means is constructed to provide a set of alternating voltage signals (+2 V, +V, -V) which have added thereto a common voltage signal Δ

V, the selector means being constructed to apply signals (+2 V+Δ

V, +V+Δ

V, -V+Δ

V, and Δ

V) to the display panel so to develop an RMS voltage difference of magnitude 3 l V_c across the two different selected index positions, and an RMS voltage difference of magnitude V_c across the other selectable index positions.

14. An analogue display comprising in combination:

a display panel;

address means for providing a set of voltage signals to operate the display panel;

a data source; and

,

selector means, responsive to the data source, for selecting voltage signals from the address means, and, for applying these signals to the display panel to enable display of two indices on the display panel against an optically contrasting background;

wherein, the display panel includes;

two parallel substrates;

an electrically sensitive medium contained between the two substrates, the medium being capable of adopting simultaneously in different regions thereof each of two optical states, an ON state, and, an OFF state, respectively, in response to different electrical field developed thereacross;

a first set of electrodes arranged in a plurality of segments, each segment being divided into an inner and an outer portion, each portion being planar and having a plurality of formed digits, the digits of one portion being interposed alternate with and in between the digits of the other portion, the first set of electrodes being mounted on the inwardly facing surface of the first substrate, and connected to the selector means; and

,

a second set of electrodes having a configuration in which a single electrode is interposed between meandering electrodes in folds formed by the meandering electrodes to form collectively a modified meander structure, the second set of electrodes being mounted on the inwardly facing surface of the second substrate, and connected to the selector means;

the two sets of electrodes being registered one set over the other with alternate digits and alternate meander electrodes defining two subsets of selectable index positions each subset to display a different index; and

,

the selector means being constructed to respond to input data and connected to the two set of electrodes to drive the panel medium in the ON state at two different selected index positions simultaneously, the panel medium being in the OFF state at all other selectable index positions.

15. An analogue display according to claim 14 arranged as a meter display,

the data source being capable of response to measured variation of a physical variable and of providing digital input data as a measure thereof;

and

the first set of electrodes being arranged in ten segments.

16. An analogue display according to claim 14 arranged as a time-piece,

the data source consisting of an oscillator and a divider chain to provide digital input data as a measure of time;

and,

the first set of electrodes being arranged in twelve segments.