SEGMENTED DISPLAY

Abstract: An eleven-segment display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals (0 to 9). The display has a single central vertical segment (8) and continuous left and right vertical segments (2, 3). The segmented display is less complex than conventional alphanumeric segmented displays.

Description: Segmented Display The present invention relates to segmented displays, and in particular to electronic or electrical segmented displays. A segmented display is a device comprising a plurality of independent segments arranged such that the device is capable of representing letters and/or numerals by activating, i.e. turning on, selected segments of the display. The segments may be activated electrically, for example illuminated, or mechanically, for example uncovered. Segmented displays have been used for many years to represent numerals and letters. The original type of segmented display was the seven-segment display, shown in Figure 1. This display comprises seven segments which are activated in various combinations to display the Arabic numerals 0 to 9. Such displays are common in digital watches, alarm clocks, calculators and the like, where the segments are often light emitting diodes (LEDs) or elements of liquid crystal displays (LCDs) . Mechanical seven-segment displays are also known, for example in petrol pumps and clocks . The success of the seven-segment display in displaying numerals led to the development of the fourteen-segment display, shown in Figure 2, which is capable of displaying all of the capital letters of the English alphabet, in addition to the Arabic numerals 0 to 9. A development of the fourteen-segment display which allows greater flexibility in the characters that can be displayed is the sixteen-segment display, shown in Figure 3. In more recent times, there has been a move away from the fourteen- and sixteen-segment displays towards dot matrix displays, such as shown in Figure 4. The dot matrix display is capable of displaying letters and numerals in a shape that is often more natural than can be displayed on a fourteen- or sixteen-segment display. It will be seen therefore that as the flexibility of segmented displays has increased by introducing more segments, so has the complexity of the display structure. For each segment of an electronic display, a respective electrical connection must be provided to supply electricity selectively to that segment. Similarly, in the case of a mechanical display, an activation mechanism is required for each segment. It is apparent that as the complexity of the display structure increases so the number of connections that must be made to the display also increases . In view of the above, the present invention seeks to provide an improved segmented display. Viewed from a first aspect, the invention provides a segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9 , wherein the display comprises at least 11 but not more than 13 individual segments . Thus, the invention provides an alphanumeric segmented display, which requires up to five fewer segments than prior art alphanumeric segmented displays, while maintaining the same ability to display letters and numerals. Clearly, the reduction in segments, and the consequent reduction in electrical connections, represents a significant technical advance in the field of segmented displays, which has been characterised by increasing complexity. A segmented display device may comprise a plurality of segmented displays according to the invention in order to display a plurality of characters. For example, in the case of a six-character display device, up to thirty fewer segments are required than in the equivalent device according to the prior art . The invention is based, at least in part, on the realisation that in a conventional fourteen-segment or sixteen-segment display, it is unnecessary to provide upper and lower central vertical segments. The inventor has determined that it is possible to display all of the capital letters of the English alphabet and the Arabic numerals 0 to 9 on a segmented display with a continuous central vertical segment or at least a central vertical segment comprising two halves which can only be activated simultaneously. Thus, the segmented display according to the invention may comprise a single central vertical segment extending along substantially the entire length of the display in the vertical direction. This in itself is believed to be a novel arrangement and thus viewed from a second aspect the invention provides a segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9, wherein the display comprises a single central vertical segment extending along substantially the entire length of the display in the vertical direction. ,The central vertical segment may be arranged to have the appearance of two distinct sub-segments, but according to the invention the sub-segments are connected such that it is only possible to activate both sub-segments together. For example, the two sub- segments of the central vertical segment may be connected by a relatively thin portion which does not have significant visual impact on the observer. Alternatively, the sub-segments may be connected by a connection, for example an electrical connection, which is not visible to the observer. The invention is also based, at least in part, on the realisation that in a conventional fourteen-segment or sixteen-segment display, it is unnecessary to provide independent upper and lower outer (i.e. left and right) vertical segments. The inventor has determined that it is possible to display all of the capital letters of the English alphabet and the Arabic numerals 0 to 9 on a segmented display with continuous left and right vertical segments or at least left and right vertical segment comprising two halves which can only be activated simultaneously. It has been appreciated by the inventor that in most instances where a vertical segment extending from the middle segment to the top or bottom segment is required in a conventional fourteen- or sixteen-segment display, a corresponding diagonal segment may be used without significantly affecting the appearance of the characters produced by the display. Thus, the segmented display according to the invention may comprise at least one continuous outer, i.e. left and/or right, vertical segment extending along substantially the entire length of the display in the vertical direction. This in itself is believed to be a novel arrangement and thus viewed from a third aspect the invention provides a segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9, wherein the display comprises at least one continuous outer vertical segment extending along substantially the entire length of the display in the vertical direction. In general a continuous left vertical segment and a continuous right vertical segment are provided. The outer vertical segment may be arranged to have the appearance of two distinct sub-segments, but according to the invention the sub-segments are connected such that it is only possible to activate both sub-segments together. For example, the two sub- segments of the outer vertical segment may be connected by a relatively thin portion which does not have significant visual impact on the observer. Alternatively, the sub-segments may be connected by a connection, for example an electrical connection, which is not visible to the observer. As used herein, the term "vertical" is not used in a strict sense, but is intended to indicate the direction of the upward and downward strokes used in the formation of English capital letters. Likewise, the term "horizontal" is used to denote the direction of the strokes which run transverse to this direction. Thus, for example, the letter "T" comprises a "vertical" stroke abutting the centre of a "horizontal" stroke. It is envisaged that the horizontal and vertical directions may not necessarily be mutually perpendicular, as is the case for example in italic script. As used herein, the "left" and "right" (or "outer") positions correspond to the positions of the two vertical strokes in a letter "N" . Similarly, the "top" and "bottom" positions correspond to the two horizontal strokes in a letter "Z" . The "middle" position corresponds to the position of the horizontal stroke in a letter "H" , and "upper" means above and "lower" below this position. The "central" position corresponds to the position of the vertical stroke in a letter "T" . The "diagonal" positions correspond to the positions of the four limbs of the letter "X" . The segments of the display may be formed by light emitting diodes, by regions of liquid crystal in an LCD display or by any other suitable electrical means. In a preferred arrangement the display is in the form of an electroluminescent display. According to this arrangement, a layer of electroluminescent material (for example zinc sulphide doped with manganese and microencapsulated in a dielectric material) is sandwiched between a first, transparent electrode (for example indium tin oxide (ITO) on a polyester substrate) and a plurality of second electrodes each corresponding to a segment of the display. When an AC driving voltage is applied between the first electrode and a respective second electrode the electroluminescent material emits light and the corresponding segment is illuminated. The display of the invention may also be applied to mechanical displays. It will be apparent that, in common with electrical displays, provision of fewer segments simplifies control of the display. An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a seven- segment display according to the prior art; Figure 2 is a schematic representation of a fourteen-segment display according to the prior art; Figure 3 is a schematic representation of a sixteen-segment display according to the prior art; Figure 4 is a schematic representation of a dot matrix display according to the prior art; Figure 5 is a schematic representation of an eleven-segment display according to the invention; and Figure 6 shows the capital letters of the English alphabet and the digits 0 to 9 represented by the display of Figure 5. Figure 1 shows a seven-segment display according to the prior art. This display has a top segment 1, a middle segment 4, a bottom segment 7, left and right upper segments 2, 3 and left and right lower segments 5, 6. The display of Figure 1 is capable of displaying the digits 0 to 9 by selectively activating the segments 1- 7, in a well-known manner. Figure 2 shows a fourteen-segment display according to the prior art. This display differs from that shown in Figure 1 in that instead of a middle segment 4 the fourteen-segment display has two middle half-segments 4a and 4b. In addition, upper and a lower central segments 8 and 9 and four diagonal segments 10-13 are provided. The display of Figure 2 is capable of displaying the capital letters of the English alphabet and the Arabic numerals 0 to 9. Figure 3 shows a sixteen-segment display according to the prior art. This display differs from that of Figure 2 in that instead of each of the top and bottom horizontal segments 1 and 7, there are provided two top half-segments la and lb, and two bottom half-segments 7a and 7b, respectively. The display of Figure 3 is capable of displaying all the capital letters of the English alphabet and the Arabic numerals 0 to 9 . Figure 4 shows a dot matrix display according to the prior art. The display of Figure 4 comprises 228 pixels 1 arranged in a 12 by 19 array. The display of Figure 4 is capable of representing any character by activating selected pixels of the dot matrix array. Figure 5 shows an eleven-segment display according to the invention. The eleven-segment display of Figure 5 differs from the fourteen-segment display of Figure 2 in that there are no upper and lower left and right segments 2, 3 and 5, 6, only a single, continuous left segment 2 and a single, continuous right segment 3, each of which extend along substantially the entire length of the display in the vertical direction. In addition, rather than the upper and lower central segments 8 and 9 of Figure 2, the display of Figure 5 has a single central segment 8 with a narrow bridging portion between the upper and lower sub- segments of the central segment 8. It will be seen that the display of Figure 5 consists of only eleven independent segments and thus only eleven electrical connections are required to the display of Figure 5 in order to represent all of the capital letters of the English alphabet and the Arabic numerals 0 to 9, as shown in Figure 6. In addition, as shown in Figure 6, other characters (* + - \) are easily represented. Although the invention has been described in terms of a display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9 , display of the Arabic numerals may not be required in all applications. Thus, the invention is equally applicable to a display which is capable of displaying each of the capital letters of the English alphabet. Furthermore, the preferred arrangement of the display consists of 11 segments, as this has the fewest segments. It will be apparent to the skilled person, however, that displays having a total of 12 or 13 segments may be created in accordance with the invention.

Claims: Claims 1. A segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9, wherein the display comprises at least 11 but not more than 13 individual segments . 2. A segmented display as claimed in claim 1 comprising a single central vertical segment extending along substantially the entire length of the display in the vertical direction. 3. A segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9 , wherein the display comprises a single central vertical segment extending along substantially the entire length of the display in the vertical direction. 4. A segmented display as claimed in claim 2 or 3 , wherein the central vertical segment comprises two connected sub-segments. 5. A segmented display as claimed in claim 4, wherein the two sub-segments are connected by a connection which is not visible, in use of the display. 6. A segmented display as claimed in any preceding claim, comprising at least one continuous outer vertical segment extending along substantially the entire length of the display in the vertical direction. 7. A segmented display which is capable of displaying each of the capital letters of the English alphabet and each of the Arabic numerals 0 to 9 , wherein the display comprises at least one continuous outer vertical segment extending along substantially the entire length of the display in the vertical direction. 8. A segmented display as claimed in claim 6 or 7 comprising a continuous left vertical segment and a continuous right vertical segment. 9. A segmented display as claimed in any of claims 6 to 8, wherein the outer vertical segment comprises two connected sub-segments . 10. A segmented display as claimed in claim 9, wherein the two sub-segments are connected by a connection which is not visible, in use of the display. 11. A segmented display as claimed in any preceding claim in the form of an electroluminescent display. 12. A segmented display substantially as represented in Figure 5. 13. A segmented display device comprising a plurality of segmented displays according to any preceding claim.

Inventors: BARNARDO CHRISTOPHER JOHN ANDR, BARNARDO, CHRISTOPHER, JOHN, ANDREW
Applicants: BARNARDO CHRISTOPHER JOHN ANDR, CAMBRIDGE CONSULTANTS, BARNARDO, CHRISTOPHER, JOHN, ANDREW, CAMBRIDGE CONSULTANTS LIMITED
Application year: 2000
Main classification: G09F9
IPC codes: G09F9