GB2094050A - Improvements in and relating to display systems - Google Patents

Abstract

A liquid crystal (LCD) display arrangement has separate LCD's 12 ("ENTER"), 14 ("CLEAR"), 16 (digits "0" to "9") and 18 (a frame for a digit display). These LCD's are arranged behind a screen and initially only the LCD 12 ("ENTER") is visible. Each of the LCD's 12, 14 and 16 incorporates a proximity switch; when the operator touches LCD 12 ("ENTER"), logic causes the LCD's 14, 16 and 18 to be rendered visible and the operator can then enter digit values into the system by touching LCD's 16. The digits touched are displayed within the frame 18. When the operator touches LCD 14 ("CLEAR"), the LCD's 14, 16 and 18 are switched off and become invisible. <IMAGE>

Description

SPECIFICATION Improvements in and relating to display systems The invention relates to display arrangements and more specifically to display arrangements incorporating liquid crystal displays (LCD's).

Various novel features of the invention will be apparent from the following description, given by way of example only, of display arrangements embodying the invention, reference being made to the accompanying drawings in which: Figure 1 is a digrammatic front view of the display face of one of the display arrangements; Figure2 is a block circuit diagram of the electrical circuit of the display arrangement; Figure 3 shows a side view of one form which one of the LCD units may take; Figure 4 is a plan view corresponding to Figure 3; and Figure 5 is a circuit diagram of the LCD unit shown in Figures 3 and 4.

More specifically to be described below is a display arrangement comprising a plurality of discrete display means which are rendered visible in a predetermined sequence under control of electrical switch means physically associated with at least one of the display means.

The switch means may be switch means adapted to be activated by immediate proximity of part of the operator's body (e.g. his finger).

In a more detailed sense, there will be disclosed below a display arrangement comprising a plurality of liquid crystal display units, electrical switch means physically associated with each of the LCD's means operative initially to energise and thus render visible one, or some, only, of the LCD's, and means responsive to activation of the switch means associated with the energised LCD, or one of the energised LCD's to energise, and thus render visible, one or more other predetermined ones ofthe LCD's.

The foregoing are exemplary of and not exhaustive of the various novel features of the display arrangement now to be more specifically described.

As shown in Figure 1, the display unit (in this example) presents a display screen 10 on which may be displayed, by means of respective LCD units, the legends 12, 14, 16 and 18 shown in the Figure that is, "ENTER", "CLEAR", the digits "0", "1", 9", and a frame for a digit display.

In a manner to be explained, howver, all the legends shown are not permanently displayed.

Thus, when the unit is initially switched on, only the legend "ENTER" IS displayed and the rest of the display screen 5 is blank. When the operator places his finger on the displayed legend "ENTER", this operates a switching arrangement (to be described) which causes the remainder of the legends to be displayed, that is, the legend "CLEAR", and the digits "0"....."9". The operator may then eneter particular numerical values into the unit by placing his finger on appropriate ones of the digits "0"....."9". Each digit value entered in this way is displayed (again by an LCD unit) in the display frame 18.

When the operator wishes to clear the display, he places his finger over the legend "clear", and all the legends (including the frame 18) are removed, leaving only the displayed legend "ENTER".

The foregoing of course represents merely as simplified example of various possible displays.

Thus, many other forms of display may be provided in which the arrangement is such that part, only, of the total display is shown initially and another part, or the remainder, of the display is then shown to the operator when he responds to the first part displayed. The different parts of the display are shown in logical sequence so that the operator is led through this sequence and is not, for example, presented with the total display initially. For example the initial display may present the operator with a choice of response, and he makes his choice by placing his finger over the one of the two or more legends displayed. The additional display which this choice produces depends on the choice.

Figure 2 shows the logic circuit for the display arrangement shown in Figure 1,that is, the legend 12 ("ENTER"), the legend 14 ("CLEAR"), the legends 16-0 to 16-9 ("0"...."9"), the legend 18 (the frame for the digit display) and, in dotted form, legends 20A to 20D (the digits which may be displayed within the frame 18). As explained, each of these legends 12, 14, and 16 has associated with it an electrical switch arrangement which responds to the proximity of the operator's finger. These switch arrangements are shown diagramaticallyat 12A, and 16A.

One form which the LCD's and their associated switches may take will be described below with reference to Figures 3,4 and 5.

Four drive units 22, 24, 26 and 28 are provided for driving the LCD's. Drive unit 22 drives the LCD 12, drive unit 24 drives the LCD 14, drive unit 26 drives the LCD's 16-0 to 16-9 and drive unit 28 drives the LCD 18.

In operation, switching on of the system by means of a switch indicated diagrammatically at 30 activates the drive unit 22 which energises the LCD 12 so as to display the legend "ENTER". None of the other drive units is activated. When the operator places his finger on the legend "ENTER", he closes the switch 12A and this activates the drive units 24,26 and 28 which therefore energise the LCD's 14, 16-0 to 16-9, and 18.

When the operator wishes to enter digit information into the system, he places his finger on the appropriate one of the legends "O"...."9" and this closes the corresponding switch 16A. This activates a logic unit 30 which produces corresponding output signals on a channel 32 to cause the appropriate one of the LCD's 20A to 20D to display the value of the digit entered. The logic unit 30 may take any suitable known form and is not believed to need specific description.

In a practical case, of course, signals representing the data entered by means of the switches 16A may also be passed, by means of an output channel 34, to equipment intended to respond to that data.

When the operator places his finger over the legend "CLEAR" so closing the switch 14a, the drive units 24, 26 and 28 are de-energised so as to clear the displays; additionally, the logic unit 30 is switched to clear the digits displayed by the LCD's 20A to 20D.

Figure 3 and 4 show, diagrammatically, one of the LCD's.

It comprises upper and lower plates 40 and 42 of glass of similar transparent material. On the underside of the upper plate 40, and on the top side of the lower plate 42, are formed transparent alignment layers of electrically conductive indium tin oxide 44 which are physically arranged in the manner of the intended visual display. Between the plates 40 and 42 and the electrodes 44the liquid crystal material (not shown) is positioned.

Electrical connections 46 and 48 are made to the upper and lower conductors 44. When a suitable potential difference is applied between the conductors 46 and 48, the liquid crystal material becomes aligned to produce the required display.

For example, a low frequency square wave may be applied to each of the conductors 46 and 48. When the square waves are in phase, there is no potential difference between the conductors 46 and 48 and the display is inactive. However, if one of the square waves is inverted, so causing a 180 phase difference between the two waves, a potential difference is developed across the conductors and the display becomes visible.

The switches 12A, 14A associated with the LCD's can take any suitable form so as to be responsive to the proximity of the operator's finger.

One such form is illustrated in Figures 3 to 5 and is of the capacitive type comprising an additional layer 50 of indium tin oxide on the upper face of the plate 40 and with an electrical connection 52.

Figure 5 shows the circuitry associated with one of the LCD's, LCD 12 for example, and also shows how operation of the switch associated with that LCD activates the drive units 24, 26, 28 (see Figure 2).

As shown, the drive unit includes a square wave source 60 producing a square wave having a frequency of, say, 32 Hz and this energises line 46 directly, line 46 being connected to the indium tin oxide conductors on the underside of the upper plate 40 of the appropriate LCD. In addition, the square wave output is fed through a NAND gate 62 to the conductor 48 which energises the indium tin oxide conductors 44 on the upper face of the lower plate 42. When the second input, line 64, to the NAND gate 62 is unenergised, the square waves on lines 46 and 48 will be in phase and there will therefore be no potential difference between them and the LCD unit will be inactive.The circuit associated with the switch 1 2A comprises a comparator 66 one input of which is fed with an alternating input from a source 68 having a frequency of, say, 32KHz. Source 68 feeds the second input of comparator 66 through capacitors 70 and 72 and an adjustable resistor 74. A third capacitor, capacitor 76, has one of its plates formed by the conductor 50 (see Figure 3) and the remainder of it is constituted by the operator's grounded body when he places his finger on the conductor 50.

Resistor 74 is adjusted so that the two inputs to comparator 66 are balanced when there is no capacitive connection between conductor 50 and ground that is, when the operator's finger is clear of the conductor 50. In this condition, line 64 is unenergised, and therefore conductors 46 and 48 in the drive unit 22 will be in phase.

When the operator places his finger over conductor 50, however, a capacitive connection to ground is produced which unbalances the two inputs to the comparator 66 and line 64 becomes energised. This causes NAND gate 62 to invert its output and lines 46 and 48 now become out of phase and produce the required potential difference across the conductors to energisethe LCD's 14, 16 and 18.

CLAIMS (filed 16.10.81) 1. A display arrangement comprising a plurality of discrete display means which are rendered visible in a predetermined sequence under control of electrical switch means physically associated with at last one of the display means.

2. An arrangement according to claim 1, in which the switch means is switch means adapted to be activated by immediate proximity of part of the operator's body (e.g. his finger).

3. An arrangement according to claim 1 or 2, in which each display means is in the form of a liquid crystal display.

4. A display arrangement comprising a pluality of liquid crystal display units, electrical switch means physically associated with each of the LCDCs, means operative initially to energise and thus render visible one, or some, only, of the LCD's and means responsive to activation of the switch means associated with the energised LCD, or one of the energised LCD's to energise, and thus render visible, one or more other predetermined ones of the LCD's.

5. A display arrangement substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. the displays; additionally, the logic unit 30 is switched to clear the digits displayed by the LCD's 20A to 20D. Figure 3 and 4 show, diagrammatically, one of the LCD's. It comprises upper and lower plates 40 and 42 of glass of similar transparent material. On the underside of the upper plate 40, and on the top side of the lower plate 42, are formed transparent alignment layers of electrically conductive indium tin oxide 44 which are physically arranged in the manner of the intended visual display. Between the plates 40 and 42 and the electrodes 44the liquid crystal material (not shown) is positioned. Electrical connections 46 and 48 are made to the upper and lower conductors 44. When a suitable potential difference is applied between the conductors 46 and 48, the liquid crystal material becomes aligned to produce the required display. For example, a low frequency square wave may be applied to each of the conductors 46 and 48. When the square waves are in phase, there is no potential difference between the conductors 46 and 48 and the display is inactive. However, if one of the square waves is inverted, so causing a 180 phase difference between the two waves, a potential difference is developed across the conductors and the display becomes visible. The switches 12A, 14A associated with the LCD's can take any suitable form so as to be responsive to the proximity of the operator's finger. One such form is illustrated in Figures 3 to 5 and is of the capacitive type comprising an additional layer 50 of indium tin oxide on the upper face of the plate 40 and with an electrical connection 52. Figure 5 shows the circuitry associated with one of the LCD's, LCD 12 for example, and also shows how operation of the switch associated with that LCD activates the drive units 24, 26, 28 (see Figure 2). As shown, the drive unit includes a square wave source 60 producing a square wave having a frequency of, say, 32 Hz and this energises line 46 directly, line 46 being connected to the indium tin oxide conductors on the underside of the upper plate 40 of the appropriate LCD. In addition, the square wave output is fed through a NAND gate 62 to the conductor 48 which energises the indium tin oxide conductors 44 on the upper face of the lower plate 42. When the second input, line 64, to the NAND gate 62 is unenergised, the square waves on lines 46 and 48 will be in phase and there will therefore be no potential difference between them and the LCD unit will be inactive.The circuit associated with the switch 1 2A comprises a comparator 66 one input of which is fed with an alternating input from a source 68 having a frequency of, say, 32KHz. Source 68 feeds the second input of comparator 66 through capacitors 70 and 72 and an adjustable resistor 74. A third capacitor, capacitor 76, has one of its plates formed by the conductor 50 (see Figure 3) and the remainder of it is constituted by the operator's grounded body when he places his finger on the conductor 50. Resistor 74 is adjusted so that the two inputs to comparator 66 are balanced when there is no capacitive connection between conductor 50 and ground that is, when the operator's finger is clear of the conductor 50. In this condition, line 64 is unenergised, and therefore conductors 46 and 48 in the drive unit 22 will be in phase. When the operator places his finger over conductor 50, however, a capacitive connection to ground is produced which unbalances the two inputs to the comparator 66 and line 64 becomes energised. This causes NAND gate 62 to invert its output and lines 46 and 48 now become out of phase and produce the required potential difference across the conductors to energisethe LCD's 14, 16 and 18. CLAIMS (filed 16.10.81)

1. A display arrangement comprising a plurality of discrete display means which are rendered visible in a predetermined sequence under control of electrical switch means physically associated with at last one of the display means.

2. An arrangement according to claim 1, in which the switch means is switch means adapted to be activated by immediate proximity of part of the operator's body (e.g. his finger).

3. An arrangement according to claim 1 or 2, in which each display means is in the form of a liquid crystal display.

4. A display arrangement comprising a pluality of liquid crystal display units, electrical switch means physically associated with each of the LCDCs, means operative initially to energise and thus render visible one, or some, only, of the LCD's and means responsive to activation of the switch means associated with the energised LCD, or one of the energised LCD's to energise, and thus render visible, one or more other predetermined ones of the LCD's.

5. A display arrangement substantially as described with reference to the accompanying drawings.