GB2115198A - Improvements in or relating to visual display instrument component assemblies - Google Patents

Abstract

A linear array of e.g. sixteen light control or emitting devices, e.g. liquid crystal or LED (2), are assembled in a unitary capsule (1), together with integrated circuit (5) and e.g. ten connector pins (6). The circuit comprises a bi-directional shift-register and latches, so that a column of activated devices or a dot, counting from either end, can be displayed and a new member can be set up and the display instantaneously changed. Analogue values can be displayed via a voltage- frequency converter. Capsules can be connected end to end indefinitely for a longer display. <IMAGE>

Description

SPECIFICATION Improvements in/or relating to visual display instrument component assemblies.

This invention relates to visual display instrument component assemblies and more particularly to components for such assemblies of the kind in which a plurality of light controlling elements such as light emitting diodes or liquid crystal elements are disposed in an array and are connected to appropriate circuitry such as to provide a desired display for instrument output purposes, for example.

It is an object of the present invention to provide a simply connected and conveniently usable component assembly of this kind.

According to the invention there is provided a visual display component assembly including a plurality of electronic light controlling devices disposed in linear array in a unitary capsule, the capsule incorporating electrical driving circuitry for the plurality of devices; and electrical terminals mounted on the capsule for external electrical connection.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which Figure 1 is a plan view of a component assembly according to the invention which provides a linear bar graph assembly: Figure 2 is a sectional side elevation of the assembly of Fig. 1; Figure 3 is a partial isometric view of the assembly of Fig. 1; Figure 4 is a circuit diagram of the internal circuitry including the driving stages of the assembly of Fig. 1; and Figure 5 is a diagrammatic representation of printed circuit board traces required for the end to end disposition of assemblies of the kind illustrated in Fig. 1.

As will be seen from Figs. 1 to 3 the component assembly comprises a capsule 1 carrying sixteen sets of light emitting diodes 2 each set comprising two chips bonded to a circuit board 3 within the capsule. A diffusing body 4 is formed within the capsule above each diode 2 from a glass filled colour-tinted epoxy resin.

The capsule includes a microchip based internal electrical driving circuit 5 mounted on the circuit board 3 and described in detail hereinbelow.

Ten terminal pins 6 of a standard dual in line design are mounted on the circuit board 3 and project from the base of the capsule 1.

The internal driving circuit for the light emitting diodes is illustrated in Fig. 4. There is illustrated the circuit for the first three and last three of sixteen identical stages. The circuit broadly comprises a multi-stage bidirectional serial in and serial/parallel out shift register, with output latches and corresponding light emitting diodes. With the arrangement illustrated each of the parallel output stages of the shift register (the aggregation of all elements 17, 18, 19, 20, 21) is connected to the corresponding light emitting diode in the linear array via the output latch in such a way that when a logic "1" is shifted into a stage of the register the light emitting diode at that stage will be illuminated.

Referring now in particular to Fig. 4, operation of the circuit calls for the following connections: Data Clock 7 serial in right 8, Clear 9, ground 10 (0 volts) serial out right 11, latch enable (load) 12, serial in left 1 3 direction control 14, positive power supply 1 5 (5 volts), serial out left 16.

To illuminate the display column of the assembly to a particular length, the sequence and circuit operation is as follows: Firstly the latches 22 are enabled i.e. (set transparent) by taking the latch enable signal 1 2 to a logic "1". The shift register and output latches are then cleared by taking the clear signal 9 to a logic "0" and then returning it to a logic "1". The required direction of movement for the display column is then selected by placing a logic "O"n on the direction input 14 for left to right column movement or by placing a logic "1" '' on the direction input 14 for a right to left movement.A logic "1" level is then applied to the appropriate serial in input 8 or 1 3 (right or left) and by taking the data clock input 7 from a logical "0" to a logical ''1'' the data at the appropriate serial in 8 or 1 3 will be loaded into the first stage of the shift register, which will be SOA (numbered 1 7) or 51 SA (numbered 18) depending on the state of the directional signal input, and the corresponding light emitting diode will be illuminated.If a moving dot only is required the selected serial data input 8 or 1 3 must be returned to a logic "O". If a varying length column is required, then the serial in signal input 8 or 1 3 must be maintained at a logical ''1''. Each successive data clock pulse from input 7 will now move the end of the column (or dot) one place to the right or left, depending upon the state of the direction input 14. If the latch enable input 1 2 is taken to a logic "0" the data in the output latches (and therefore the illuminated column) will be held constant whilst data in the shift register may be cleared and a new column or dot position shifted in.When the latch enable input 1 2 is returned to a logic "1" the pattern in the column of light emitting diodes will change instantly to the new pattern in the shift register. With this feature new data may be "shifted in"' while still maintaining the previous display, enabling such facilities as "flashing curser segments" brightness control and other display enhancement techniques to be provided.

As can be seen from Fig. 4 each encapsulated module includes a series of flip-flop latches such as those numbered 1 7 and 1 8 whose output data is steered to either "the previous" or "following" stage by sets of three nand gates such as the set numbered 19, 20 and 21 connected as a "data selec tor", controlled by the logic level on the direction input 14 so that data can be transferred through the shift register in either direction.

Also connected to the output of each flipflop is a transparent latch such as that numbered 22 the output of which follows the input when the latch enable input 1 2 is high, but which stores the current data when the latch enable input 1 2 is low. Thers transparent latches enable independent operation of the shift register and light enitting diodes 2.

The output of the transparent latch drives the visible light emitting diode 2 which comprises, typically two .040 X .010 inch dies of gallium arsenide bonded to the printed circuit board 3 which also serves to mount the internal driving circuit 5 and diffusion bodies 4.

As mentioned above the capsule is provided with ten connection pins 6 connected to the internal driving circuit 5 these being chosen to enable an external printed circuit board (shown in Fig. 5) to cascade any numbers of encapsulated display assemblies mounted end to end on such external board without need for links or double sided boards.

The assembly according to the invention enables for example a column of light emitting diodes to represent an analogue function by varying the height (or length) of the column. By means of the invention this can be provided without need of additional driving circuitry, with a fully static operation, with a column (or dot) entry from either end, with a column height adjustable with one clock pulse per segment, without incurring high current spikes on power supplies, high resolution at low cost and with simplicity of implementation. In practical terms there are no real limits to the end to end stacking of the assemblies possible. The arrangement is easily driven by voltage to frequency converters to form a low cost A/D function and display.

Circular and alpha numeric displays may also be built up from components according to the invention incorporating driving circuitry of the kind illustrated, and the operational description hereinabove is equally applicable in principle to many forms of graphic display such as linear, alphanumeric or circular displays.

The assembly of the present invention has numerous applications including radio tuning scales, contents/level indicators, minic diagrams for railway operation etc., temperature/pressure indicators, automotive/ aircraft/ marine displays, histogram type displays, (for example for spectrum analysis) weighting machines, mechanical meter replacements, VU meters, position indicators, gas discharge linear "bar graphs" display replacements, electronic toys, medical parameter displays, and "trend" indicators to compliment 7 segment displays.

Claims (5)

1. A visual display component assembly including a plurality of electronic light controlling devices disposed in a linear array in a unitary capsule, the capsule incorporating electrical driving circuitry for the plurality of devices, and electrical terminals mounted on the capsule for external electrical connection.

2. An assembly according to Claim 1 wherein the driving circuitry incorporates a microchip component.

3. An assembly according to Claim 1 or 2 wherein the driving circuitry incorporates a multi-stage bi-directional shift register having serial input and aerial/parallel output, and with output latches corresponding to said light controlling devices.

4. An assembly according to anyone of the preceding claims wherein the light controlling devices are light emitting diodes.

5. A visual display component assembly substantially as shown in and as hereinbefore described with reference to the accompanying drawings.