GB2068622A - Programmable liquid crystal display e.g. for jewellery - Google Patents

Abstract

A visual display apparatus comprises a liquid crystal display (LCD) which has a number of display electrode elements and is controlled by a (CMOS) integrated circuit (1) having a programmable read-only-memory (PROM) (3) which contains sets of data instructions. The PROM selects via a driver (8) the LCD electrodes to receive signals from a HF oscillator (11) so as to produce a display. As an LF oscillator (10) changes the addressing of the PROM, further sets of instructions make new selections of electrodes and different visual displays are produced. The frequency of change of the visual display is controlled, e.g. manually, by the LF oscillator (10). The integrated circuit and LCD is combined with a power source in one unit, which is preferably an article of jewellery. <IMAGE>

Description

SPECIFICATION Electronic display apparatus The present invention relates to electronic apparatus for controlling the presentation of a changeable visual display.

According to the present invention there is provided changeable visual display comprising a programmable semi-conductor device and a changeable liquid crystal display, said display being changeable from one visual presentation to another in accordance with instructions from said programmable semiconductor device.

In a preferred form of the invention, the semiconductor device and the LCD are combined with a power source in an article of jewellery.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 7 is a block diagram of a circuit for carrying out the present invention; and Figure 2 is a block diagram of an alternative circuit for carrying out the present invention.

Referring now to Figure 1 a semiconductor device in the form of a 'chip' 1 has electrical circuitry located thereon fabricated by a low voltage complementary metal-oxide-semiconductor (CMOS) process or similar.

An N bit binary counter 2 is connected to a decoder 6 which decodes the said counter's output state to select an address of a preprogrammed read-only-memory (PROM) 3 to which it is connected. One of the decoder outputs 4 is preprogrammed to reset the binary counter 2 in order that the sequence may be recycled after a specified number of steps. The PROM 3 has M parallel outputs 5 which are connected to liquid crystal display drivers 8, and the drivers 8 also have M parallel outputs 9 which are connected to the front plane electrodes (not shown in the interest of clarity) of a liquid crystal display (also not shown in the interest of clarity).A first oscillator 10 is connected to the N bit binary counter 2, and a second oscillator 11 is connected to the liquid crystal display (LCD) drivers 8 and to the back plane electrode (not shown) of the liquid crystal display.

The frequencies of the first and second oscillators are set by the value of external resistive and capacitive components (not shown) which are located external to the semiconductor chip 1.

Power is supplied to the chip via terminals 12 and 13 which are at a potential of typically 41/2 volts and zero volts respectively.

The data which has been 'read' from the PROM 3 is transferred in M parallel rows by the PROM outputs 5 to the liquid crystal display drivers 8 in accordance with the frequency of the oscillator 10.

The visual display data is caused to oscillate according to the frequency of oscillator 11 such that the data is either in-phase or in antiphase with the signal to the back plane electrode. Signals in antiphase cause the electrode elements to darken while those in phase cause the appearance of the visual display to remain unchanged.

The visual display data is then transferred from the drivers 8 to M liquid crystal display electrodes in accordance with the frequency of oscillator 11, the frequency of which is typically 100 Hz to prevent deterioration of the liquid crystal display. Thus, data signals are presented to the front plane electrodes in phase, or in antiphase, with signals from the oscillator 11 to the back plane electrode of the liquid crystal display.

The visual display thus presented is representative of the particular row of data read from the pre programmed read-only-memory 3. The visual dis play presented is continuously changed in accordance with the program in the PROM 3 and the frequency of change is controlled by oscillator 10, which is typically 0.1 Hz to 2 Hz.

The number of electrodes of the liquid crystal display (M) and the number of steps in the display sequency (2N) should be as large as possible to provide maximum versatility. Maximum values of N and M are typically 5 and 30 respectively.

Referring now to Figure 2, an N-bit shift register 14 and NOR gate 15 are connected to the PROM 3 in place of the binary counter 2 and decoder 6, and a latch buffer 7 is inserted between the M parallel outputs 5 and the LCD drivers 8. The outputs 7a of the latch buffer 7 are connected to the LCD drivers 8, and the oscillator 10 is also connected to the latch buffers 7, otherwise the circuit is the same as for Figure 1.

In use, the shift register 14 is clocked by the oscillaor 10 which then sends an electrical signal corresponding to a logic "1" to the PROM 3 enabling data corresponding to a particular visual display to be read. The NOR gate 15 ensures that there is only one logic "1" in the shift register at any one time.

The data which has been read is transferred in (M) parallel rows by the PROM outputs 5 to the latch buffers 7. The data is then transferred from the latch buffers 7 to the LCD drivers 8 in accordance with the frequency of the oscillator 10. The control of the display by the oscillator 11, is the same as forthe first circuit shown in Figure 1.

The external resistor of the oscillator 1 is variable so that the frequency of the change of the visual display can be adjusted manually, which is an advantage of the apparatus according to the present invention.

One processing mask will be unique to a particular liquid crystal design. This mask will contain data by which memory transistors in the read-only-memory are enabled or disenabled to provide the required output bit pattern.

A further advantage is that the CMOS-based operation requires very low power consumption, resulting in continuous operation, over a period of a year or more, being achieved without battery renewal.

Although it is envisaged that the present invention described in this embodiment will have application in electronicjewellery it should be also realised that the present invention will have application in many other fields such as advertising and learning methods without departing from the scope of the invention.

Claims (3)

1. A changeable visual display apparatus comprising a programmable semiconductor device and a changeable liquid crystal display, the display being changeable from one visual presentation to another in accordance with instructions from said programmable semiconductor device.

2. Apparatus as claimed in claim 1 wherein said programmable device is a complementary metal oxide semiconductor (CMOS) programmable readonly-memory (PROM) located on an integrated circuit.

3. Apparatus as claimed in claim 2 wherein the integrated circuit has a first oscillator and a second oscillator, the first oscillator controlling the frequency of change of said changeable visual display.

3. Apparatus as claimed in either claim 1 or claim 2 wherein the integrated circuit has a first oscillator and a second oscillator, the first oscillator controlling the frequency of change of said changeable visual display.

4. Apparatus as claimed in any preceding claim wherein a binary counter and decoder are connected to said PROM.

5. Apparatus as claimed in any one of claims 1 - 3 wherein a shift register and a NOR gate are connected to said PROM.

6. Apparatus as claimed in claim 5 wherein the first oscillator is also connected to latch buffer means.

7. Apparatus as claimed in any preceding claim wherein the liquid crystal display includes a plurality of electrodes.

8. Apparatus as claimed in claim 7 wherein a liquid crystal display driver is connected to the outputs of the PROM, the data from the LCD driver being passed to the electrodes in accordance with the frequency of the second oscillator.

9. Apparatus as claimed in any preceding claim wherein the frequency of the first oscillator is variable externally of the integrated circuit whereby the frequency of change of the changeable liquid crystal display can be effected manually.

10. Apparatus substantially as hereinbefore described with r'erence to the accompanying drawings.

New claims or amendments to claims filed on 10 Apr.1981 Superseded claims 1,3 New or amended claims:

1. Changeable visual display apparatus comprising a programmable semiconductor device and a changeable liquid crystal display, the liquid crystal display being changeable from one visual presentation to another in accordance with the instructions from said programmable semiconductor device.