GB2064186A - Information display system - Google Patents

Abstract

An information display system for use on boats has a central computer unit (12) which receives data from transducers (14, 20, 28, 32) and supplies this data and functions computed from it to analogue meters (42 etc) and to a plurality of digital displays (54). The digital data is transmitted by a data bus (52) as 32 coded data items in time division multiplex. Each digital display (54) is preselectable to display on a liquid crystal display (64) any desired four of the data items, the items displayed at any instant being selected from the four preselected items by a touchpad (66). In the computer unit each data digit of each data item is encoded direct into a 14 bit code, each pair of bits (01 or 10) corresponding to one segment of the 7-segment character display. <IMAGE>

Description

SPECIFICATION Information display system This invention relates to an information display system, particularly, though not exclusively, to such a system for use on yachts.

The present invention is defined in the appended claims, to which reference should now be made.

The invention will be described by way of example with reference to the drawings, in which: Figure 1 is a block schematic diagram of an information display system embodying the invention for use on a sailing yacht.

Figure 2 is a front view of one of the multi-function displays (MFDs) used in the system of Figure 1.

Figures 3A and 3B which when placed side-by-side form a single composite figure, are a circuit diagram of the circuitry in one of the multi-function displays.

Figure 4 is a circuit diagram of part of the computer unit of the system of Figure 1.

Figures 5A and 5B, which when placed side-by-side form a single composite figure, are a circuit diagram of another part of the computer unit.

Figure 6 is a circuit diagram of a digital input multiplexer in the computer unit.

Figure 7 is a circuit diagram of an amplifier which may be included in the computer unit to amplify signals representing the boat speed.

Figure 8 is a circuit diagram of an amplifier which may be included in the computer unit to amplify signals representing the wind speed.

Figure 9 is a circuit diagram of a decoding circuit which may be included in the computer-unk to decode multiplexed input signals, and which we term the UART system.

Figure 10 is a block circuit diagram of a clock pulse generator in the computer unit.

Figure 11 is a circuit diagram showing the connections for a remote keyboard unit.

Figure 12 is a circuit diagram of the computer unit analogue output circuits.

Figure 13 is a circuit diagram of a successive approximation comparator, used in the computer unit as an analogue-to-digital converter.

Figure 14 is a circuit diagram of the keyboard module of the system of Figure 1.

The principles of the construction and operation of the system will be described with reference to Figures 1 and 2. The detailed circuit construction is shown in the subsequent figures which carry the necessary information for the construction of the circuits in conventional manner. A full discussion of these figures is therefore not necessary, although a brief description will be given of certain salient points.

Referring thus to Figure 1, the system 10 illustrated is designed for use in yachts to provide a display of relevant data to the yacht crew. To this end the system has a computer unit 12 linked on the one hand to a number of sensors or transducers and on the other to a plurality of display devices.

Three types of sensor are shown. The first of these comprises a pair of underwater units 14 which measure the speed of the boat through the water. One unit is fitted to the port side of the keel and the other to starboard, and a change-over switch 16 automatically selects the unit which is lowest in the water. Such sensors are known as "logs". One log only can be used in which case the switch 16 is omitted, as shown by the dashed connection 18.

The second input sensor is a masthead unit 20 which includes a transducer 22 for wind direction and a transducer 24 for wind speed. These are supported clear of the mast to ensure accurate measurement. The two wind transducers are connected by a six-core cable and if necessary junction boxes as at 26 to an input of the computer unit.

The third sensor shown may be compass repeater 28 which is connected in conventional manner to be controlled by a compass control unit (not shown). Alternatively the sensor may be the compass control unit.

Additional inputs can be provided by way of a input junction box 30. This receives the outputs of up to say six additional sensors 32 and multiplexes these signals onto an input data bus 34 to the computer unit 12. If only one of these additional sensors 32 is present, it can be directly connected to the computer unit as indicated at 36, the input junction box 30 then being unnecessary.

The computer unit 12 provides both analogue and digital outputs. The first analogue output 40 indicates wind direction and is applied to a meter 42 capable of giving a 360 degree indication. For this purpose a three-core cable is required. Additional repeater meters 42a can be wired in parallel with the meter 42 if required.

The other three analogue outputs are applied over a four or six core cable 44 to three respective meters 46, 48 and 50 which indicate boat speed, magnified wind direction, and wind speed. In each case the current supplied by the computer unit 12 is proportional to the displayed variable, thus repeater meters 46a, 48a and 50a are wired in series with the meters 46, 48 and 50 respectively.

The system also includes a digital output 52. This is described in more detail below, but, briefly, contains a plurality of time division data slots, for example 32 slots, which carry respective items of information for display as desired. The output cable is connected to a plurality of multi-function display unit 54, each of which can display any one of up to four preselected items of information. The display units 54 are connected in parallel in the most convenient fashion, i.e. they can be looped into the nearest adjacent unit, as shown. A recorder 56 can also be connected to the digital output.

Both the analogue and digital displays can be illuminated by connection to a battery or to a common dimmer circuit.

Finally, also connected to the computer unit 12 is a master keyboard control unit 58 and a battery 60.

The computer unit 12 accepts inputs from all the sensors and provides outputs to drive the analogue indicators and the digital display units. Where necessary, the content of the information provided by the computer unit can be controlled centrally from the master keyboard 58, e.g. certain types of display can be reset.

The digital display units 54 are as shown in Figure 2. On the front face 62 of the unit there is a liquid crystal device (LCD) 64 which can display up to four digits with a decimal point optionally present between any adjacent pair of digits.

Each digit is made up from up to seven segments. The unit 54 also has a touch-sensitive keypad 66 which has four sensitive areas 68. These correspond to the four data items which the unit can be preadjusted to display. The names of the data items are written at 70, and the LCD 64 also contains a flag 72 which indicates which of the four functions is being displayed at any instant. For use at night time the appropriate touchpad region can also be illuminated.

Each of the display units 54 can be adjusted internally to indicate any four of the up to 32 data types generated in the computer unit 12. The desired one of the four functions is called up by pressing the appropriate one of the four 'keys' 68 on the keypad 66. The left-hand key is the primary function of the display and it will always indicate this function when power is first applied. A display unit may be dedicated to a single data type simply by adjusting all the keys to display the same information.

The master keyboard 58, if used, is essentially based on the construction of one of the displays 54 but with the LCD 64 replaced by a blanking plate. The computer unit 12 itself has no controls at all, except for calibration adjustments, so its position is not critical. Calibration is performed by setting binary switches located in a sealed (water-tight) portion of the computer unit 12. If the computer unit 12 has to be replaced, calibration with the new unit can be achieved simply by copying the switching settings from the old unit.

Calibration is applied to the input from the ships log or underwater units 14, to the wind angle signal from the transducer 22, and to the wind speed signal from the transducer 24, and similar switches may be used to input certain data appertaining to the vessel, e.g. its rating, for use in calculation, or to alter the scale of the display, e.g. between knots and metres per second.

The functions which can be displayed by the system will now be described. They may be allocated to the 32 data output time channels as shown in the following table.

TABLE Keyboard Channel Module Number Controls Function O Boat speed 1 Apparent wind angle 2 Compass heading 3 Depth - metres 4 Depth - feed/fathoms 5 K1 Stopwatch -- hours/minutes 6 K1 Stopwatch - minutes/seconds 7 K2 5 minute countdown 8 K2 Average boat speed 9 Apparent wind speed - damped 10 Apparent wind speed - undamped 11 K4 True wind speed 12 K4 True wind angle 13 K4 True magnetic wind direction 14 K2 Reset log 15 K3 Stored log 16 K4 Performance - windward 17 K4 Performance - reaching 18 K4 Performance - downwind 19 K4 Performance-Vs/Va 20 K2, K4 Course made good 21 K2, K4 Distance made good 22 Barometric pressure 23 Temperature 24 Shaft speed 25 Battery volts 26 to 31 Spare The keyboard module controls operate as follows: K1-Operates the stopwatch (channels 5 and 6) in the sequence start/stop/reset.

K2-Resets the resetable functions in channels 7, 8, 14, 20 and 21.

K3-Alters the range of the stored log display by moving the decimal point between its three positions, ie after the second, third or fourth digits of the display.

K4 Inhibits displays which involve the processing of information from two or more transducers, as required when racing under RORC rules.

The stored log (channel 15), and other permanent data is retained in a data memory in the computer unit 12 which is maintained by a built-in rechargeable cell. The boat speed (channel O) is damped and the amount of damping applied can be varied automatically in the computer unit 12 in dependence upon the sea state. The reset log (channel 14) restarts whenever the system is switched on. Apparent wind angle (channel 1) is displayed as a three-digit figure of degrees, from 000 to 1 80.

Port or starboard is indicated by activating the central horizontal segment of either the first or fourth digit on the display respectively, the remaining three digits being used for the number of degrees. The damped apparent wind speed (channel 9) is the average value over the last 16 seconds, while the undamped value (channel 10) is the maximum gust in the same period.

The precise details of other functions can be varied at will and a sufficient indication has been given of the flexibility of the system. The computer unit 12 can be adapted to process data for display, and in particular to generate computed functions such as the performance functions (channels 16 to 19).

It should be noted that the recorder 56 of Figure 1 can be included to record the data transmitted on the data bus 52 onto a simple cassette tape. This allows a record to be kept of all the data channels.

This enables an accurate comparison of all the factors influencing the boat to be made at leisure. This can be used to assess or improve the performance of the boat and its crew.

The data transmission format on the data output bus 52 is as follows. Each frame of data consists of 32 data sets. Each data set comprises: 1. A9-bitstartcode0l 1111111.

2. A 5-bit address (channel number) code.

3. A 1-bit update command, discussed below.

4. The data.

The data consists of four digits. Each digit is encoded at the computer unit 12 by a seven-bit code which directly associates the seven segments of the displayed character with a corresponding bit on the common digital data bus. The seven segments of the character are labelled a tog on Figure 2, and the decimal point is labelled h.The codes for the characters 0 to 9 are thus as follows: a b C d e f g 0 1 1 1 1 1 1 0 1 0 1 1 0 0 0 0 2 1 1 0 1 1 0 1 3 1 1 1 1 0 0 1 4 0 1 1 0 0 1 1 5 1 0 1 1 0 1 1 6 1 0 1 1 1 1 1 7 1 1 1 0 0 0 0 8 1 1 1 1 1 1 1 9 1 1 1 1 0 1 1 By encoding the data at the computer unit 12 in this way, substantial economies result in the construction of the multifunction display unit 54, as the data received can be directly applied to control the appropriate display segments without having to be coded into the 7-segment code in each display unit. In practice each 0 is sent as the combination 01 and each 1 is sent as combination 10.A total of 64 bits are then required for the data, but the advantage is that a degree of parity protection is thereby introduced, and furthermore it becomes a relatively easy matter to extract the clock rate from the data at the display unit 54 by means of a phase locked loop circuit.

The update command indicates whether the data set contains information which should be updated immediately on receipt, ie during the immediately following data set, or data which can be updated once per frame at a common update constant, eg during the channel 0 data set. Channels 1 to 7 are updated immediately.

A convenient bit rate for use with the illustrated system is in the region of 1500 Hz. This gives a frame time of a little under two seconds.

If the computer unit provides only a digital output, the analogue meters 42, 46, 48 and 50 can be run from the digital data line 52 via suitable digital-to-analogue converters.

For a detailed description of the circuits in the computer unit 12, display units 54, and keyboard module 58, reference is made to Figures 3A to 14 of the drawings. These figures carry full identifying information where necessary, including integrated circuit numbers for example, and so, as noted above, these figures will not be described in detail as their content is self-evident. A few explanatory comments only will be made as follows.

Figures 3A and 3B should be placed side-by-side to form a single composite figure. In this figure are seen near the top left-hand corner the data input, and the other, power inputs are along the lefthand edge. The keyboard unit is a separate plug-in unit shown at the bottom left of the figure. Figure 3A also shows the block of channel selector switches S1 to S4 for the four displayed channels. These are 5-bit dual-in-line switches which are preset with the channel number (in binary code) which is to be displayed. To the bottom right of the figure are a phase locked loop circuit which drives a clock pulse generator for synchronising the unit to the input data timing.

The computer unit 12 is illustrated in Figures 4 to 13. Figure 4 shows the main computing circuitry which is used to produce computed functions and includes storage for stored functions such as the stored log. The CPU shown is programmed to provide the various functions which have been described in the foregoing or which may be required by the user using standard techniques. Figures 5A and 5B show the main multiplexing circuitry leading to the digital data bus, and include the circuitry for processing analogue inputs. Associated with this is the circuitry of Figure 6 which multiplexes the digital data inputs and includes calibration switches S1, S2.

Figures 7 and 8 show simply suitable amplifier circuits for the signals representing boat speed and wind speed respectively. Figure 9 is a demultiplexerfor demultiplexing data received from the input junction box 30. Figure 10 is a clock generator and Figure 11 shows an interface for the keyboard module 58. Figure 12 shows the analogue output circuits which feed the analogue outputs 40 and 44 of Figure 1, and Figure 13 is a simple successive approximation comparator used in the computer unit as an ADC. Suitable power supply circuits are also provided for the computer unit 12.

In Figures 4, 5A, SB, 6 and 9 the terminals P 10 to P 17 are shown. These are all connected together to form an internal 8-bit data bus. In fact terminal P 10 is not required on Figure 5A.

Finally the keyboard module is shown in Figure 14. This is connected to the Figure 11 circuit and is provided with a keyboard, not shown on Figure 14, but similar to the keyboard at the bottom of Figure 3A.

Amongst the features of the system described it will be seen that the system enables the selection at the individual displays of one of four preselected functions out of the many provided by the central unit 12. This system is particularly suited for marine use but is not limited to such use. The displayed characters are transmitted from the central unit in a 7-segment display code reducing the need for display coding to an absolute minimum, regardless of the number of display units or displayed functions.

Claims (4)

1. An information display system, particularly suitable for marine use, comprising a central unit providing at least several different digital data outputs, and a plurality of display units connected to the central unit, each display unit having provision for preselecting two or more of the data outputs of the central unit, and for selecting for display at any instant a desired one of the preselected data outputs.

2. An information display system, comprising a central unit providing digital data outputs, and a plurality of display units connected to the central unit, each display unit providing a display of each character by selectively illuminating linear character sections, and in which the data outputs of the central unit present the data in a display format such that each character section is associated with corresponding digit(s) of each data output.

3. An information display system according to claim 1 or 2, in which the data outputs are in time division multiplex.

4. An information display system substantially as herein described with reference to Figures 1 and 2 of the drawings.