GB2091913A - Timed control of central heating system - Google Patents

Abstract

A control unit of an H.W. & C.H system Fig. 1 comprises switches 8 to select any of six operating periods. Light-emitting elements 4 give analogue indication of time of day and also of the selected time periods in a manner distinguished therefrom eg by colour or by flashing. Sliders 82 are continuously variable to select room temperature, from heating OFF to maximum temp, during a respective period. Switches 18a enable setting of desired H.W. temp. A microprocessor 42 Fig. 3 includes means for comparing the set temperature with actual temperature. <IMAGE>

Description

SPECIFICATION Improvements in or relating to programming devices This invention relates to programming devices for electrical output functions, as exemplified in particular by devices for time control of heating apparatus such as space heating and water heating for buildings.

Typically, such devices incorporate a clock or the like established an overall time period or programme base, e.g. a 24-hour time base, with means to set four switching times adjustably in that period, although some programming devices are known that have means providing a larger number of switching times but with some restriction on their positions.

The selection of output function control has normally been limited, for example, there being function selector switches that allow the operation of space heating means, or draw-off hot water heating means, or both, from two time-operated switches responding in different ways at the set switching times. Associated selector switches allow the selection of a single on/off cycle or doubie on/off cycles for each function (space heating ahd hot water) during the 24-hour period, and it may be possible also to select a continuous "on" or continuous "off" setting for one or both functions.

Programming devices incorporating these features have been available for many years in electro-mechanical form. The programme time base is generated by an electric (or clockwork) motor driving through a gearbox a rotary outpt member taking 24 hours for each revolution, for example. Adjustable actuators for setting the switching times are attached to or contacted by the rotating member to operate a cam mechanism which in turn operates electrical switches. These switches control the output functions by operating in their different ways through manual selector switches which select the required options for the respective output functions.

Such devices necessarily offer only limited control. Further control facilities, e.g. a day omission facility in a 7-day period, have also been provided but with the additional complexity of these much of the ease of understanding and simplicity of use is lost.

There have also been electronic programming devices produced more recently that offer many of the features described above, but in adapting to electronic techniques the devices have also been less easy to understand and to use than conventional electomechanical devices.

Programming devices, and especially devices for programming domestic heating will often be used by people with no particular knowledge or training and any added complexity will limit the usefulness of more flexible control arrangements. By virtue of being more difficult to understand they may discourage the consumer from making use of the facilities that are provided, and they are more likely to be operated incorrectly. Moreover, the electronic devices so far adopted may not even provide greater control than the known electro-mechanical devices.

According to the invention, there is provided a programming device for at least one electrical output function comprising an electronic circuit for producing output signals controlling said at least one output function and arranged to operate in conjunction with adjustable setting means adapted to define setting control values of said at least one function for adjustable time periods within a larger overall time period, the device having electronic analogue display means for displaying said overall time period and for indicating thereon time-ofday and the adjustably set time periods, and means for the display of setting conditions within said periods of the overall time period.

In a particularly simple arrangement, the setting conditions in the individual periods of the overall time period are arranged to be displayed on said electronic analogue display also. As an alternative, particularly if greater flexibility of operation is required, the setting means may comprise an arrangement of manually adjustable elements that provide a time sequence display of the setting control values within the individual periods defined by the timing means. Different adjustable elements may be arranged to control different output functions.

The individual elements of the setting means may form a series in which each element is associated with a particular control value (in the simplest case, "on" or "off") and the elements are adjustable simply to set the starting times for those control values.It is possible, however, to provide a device according to the invention with setting means that allow a greater freedom of adjustment,wherein the setting means comprise both adjustable timing means adapted to delineate adjustable time periods within the larger overall time period, and a series of adjustable programming elements each for setting a control value for a respective delineated time period, whereby said at least one output function is determined in each adjustable time period by the setting of the programming element associated with that period, the programming elements thereby displaying the control values set within said delineated time periods as displayed on the analogue display means.

Conveniently, both time-of-day and the delineated time periods are shown on a common display, which may take the form of a linear array of light-emitting elements, each representing a discrete time period. If both time-ofday and the delineated time periods are dis played simultaneously on a common display, preferably means are provided to distinguish between them visually.

The invention will be more particularly described by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 illustrates the front panel of a programming device according to the invention, Figure 2 is a block diagram of the circuitry of the device in Fig. 1, Figures 3 and 4 illustrate in more detail the power board and the display board, respectively, of the circuitry in Fig. 2, Figure 5 illustrates a front panel of another form of programming device according to the invention, Figure 6 is a block diagram of the circuit of the device of Fig. 5, Figures 7 and 8 illustrate two forms of programming device according to the invention, Figures 9a and 9b illustrate features of a remote temperature control for use with the device of Fig. 8, Figure 10 shows the front panel of another form of programming device according to the invention, Figure ii illustrates the display characters that appear on the front panel of Fig. 10 to indicate the different days of a weekly programme cycle, and Figure 12 is a perspective view of a programming device according to the invention, illustrating a modification.

Fig. 1 illustrates the front panel 2 of a first form of device according to the invention in which a time display 4 of the programme base is provided by means of an array of lightemitting elements, and the time of day is indicated by illumination of each element in turn in accordance with the inscribed time scale. In this example there is a rectilinear array of 48 similar elements 6, the individual elements corresponding to half-hour periods of a 24-hour clock, but of course the overall time period can be subdivided into greater or lesser periods if required.

The device illustrated is arranged to have six adjustable switching times within an over all period represented by the array of ele ments 6. These times are set by respective timing push switches 8 labelled "Set A", "Set B''...."Set F", arranged in a rectilinear array 10 like the time display 4. The associ ated circuits are so arranged that when an individual push switch 8 is held down the switching time A, B...F associated with that switch sweeps progressively to and fro be tween the limits set by the adjacent preceding and succeeding switching times (and in the case of the switches "Set A" and "Set F" the beginning and end, respectively, of the array), until stopped by releasing the push switch.In this way, all six switching times are individually adjustable, although as will be explained later a switching operation does not necessarily occur at the set times.

The light-emitting elements 6 also serve to show the programmed switching times set by the push switches, but in a manner that is differentiated from the time-of-day indication, e.g. as by being of a different colour or by using a flashing signal for the time-of-day indication. In the latter case, when the timeof-day indication is coincident with a programmed switching time it can be arranged that the light-emitting element concerned will then flash with a different duty cycle than if it indicated only time-of-day: e.g. for the timeof-day only it might have a light-dark cycle of 1:9 whereas with the two indications coincident this changes to 9:1. In order to avoid confusion when adjusting the switching times, it can be arranged that the time-of-day indication is extinguished while any of the push switches 8 are being held down.

It will also be necessary to adjust the position of the time-of-day indication, both for initial setting purposes and for clock adjustments such as the changeover to and from Summer Time. The front panel of the device has two push switches 12, 14 for this purpose, giving forward and backward adjustments respectively. By pressing the forward switch 1 2 the time-of-day indication will for example move forwards progressively through the elements to the right-hand end of the time display 4 and then reappear at the left-hand end and continue to step forwards until the switch is released. The backward adjustment switch 14 of course will operate in the oppo site manner. Again, to avoid confusion with the programme switching time indications set by the switches 8, these indications can be arranged to be extinguished during a time-of day setting process.

Because the time is indicated by the ele ments 4 in discrete steps, when the time setting operation is carried out in the manner described it is preferably arranged that the programme base timing begins from the exact half-hour point selected, to avoid ambiguity in the setting procedure, i.e. so that it will take the complete half hour before the time-of-day indication moves to the next element. If it is desired to be able to set the internal time of the device closer to real time an intermediate step facility can be provided to allow adjust ments in smaller steps of, e.g. five minutes.

This can be so arranged that by pressing the time advance or retard switches 10,1 2 briefly, e.g. holding one or other down for less than + second, a five minute step will be added to or subtracted from the internal time-keeping reg ister. This can be repeated as desired in either direction, allowing adjustments to be made in any multiple of five minutes. It will be under stood that this is an optional adjustment, and although the facility may not be self-evident to an uninformed user, such a user will not be unduly concerned about precise setting of the "time of day".

Associated with the programme switching times are a series of selector switches 1 6 movable between on and off positions to control the state of a programmed output function in the respective periods delineated by the programme timing switches 8. Thus, with the push switches 8 and time display 4 indicating a series of particular switching times A to F, the six selector switches 1 6 determined whether the output function controlled is on or off during individual periods A to B, B to C... F to A. It is to be noted that the selector switches define the programme control values within individual delineated time periods independently of the time period setting means.Of course, if it is desired to subdivide the overall programme time period into a greater or lesser number of sectors by providing a different number of setting switches 8, the number of selector switches would then be changed correspondingly so that each time sector can be individually controlled.

Equally, however, it is not necessary to have a change of state at the end of each set period. The output function defined by any selector switch is independent of the function set by any other selector switch so that the user has complete choice.

The selector switches 1 6 have distinctively different appearances in their alternative positions so that the overall programme set by the switches is immediately apparent: i.e. as they appear in Fig. 1, they show "on" periods from A to B, C to D and E to F alternating with "off" periods from B to C, D to E and F to A. Moreover, because the switches 1 6 are arranged as a rectilinear array 1 8 parallel to the time display 4 and the timing switches 8, they can be easily related to the indicated switching times A to F, so that even an unsophisticated user is able to comprehend easily the programme that has been set and to make adjustments without difficulty.

An indicator light 20 is provided adjacent the array 1 8 of programme selector switches to show whether the output is on or off at any instant. This is operated from the control signal generated by the device so as to indicate the instantaneous state of the programme regardless of possible back-feeds from load circuits or the like.

The panel 2 also carries an override or boost switch 22 by means of which it is possible to modify temporarily a preset programme. There may be an illuminated indicator incorporated in the switch to show when it has been operated. In particular, the function of the switch 22 may be to increase the length of time during which the output function is on for some period, and the device thereafter resuming its preset programme.

This may be arranged so that, if the output function is off when the override switch is operated, an immediate one-hour "on" period is initiated. If the output is already on, due to the preset programme, it may be arranged that the override switch will have no immediate effect but will add a further one-hour period to the "on" state from the moment at which the control would have been switched to "off" by the preset programme.

The front panel of the display device also has an auto/off switch 24. In the auto position the output function is determined by the preset programme. The output function is in the "off" state continuously when the switch is in the off position, although the device may still have its indicating elements 6 functioning, at least to give a time-of-day display. As shown, the state of the switch 24 is indicated by its position, but it can additionally or alternatively have illuminated indicating means.

Fig. 2 is a block diagram of the electronic modules associated with the display panel already described. A power board 30 receives the mains input 32 and one or more load circuits 34, which may be at mains voltage or low voltage, are connected to the power board. The power board 30, also provides low voltage power through connections 36 to a main control board 38, from which a line 40 returns to it output function signals to control the load circuit outputs.

The low voltage power supply 36 is connected to a microprocessor 42 on the main board, from which the output function signals are produced. There are inputs to the microprocessor from the various time setting and control switches 8, 12, 14, 22 on the front panel, as well as from the programme selector switches 16, and the microprocessor outputs to the various front panel indicating elements 6, 20, 22, and time display 4, this last being mounted on a display board 44. An emergency battery supply 46 is provided to allow the internal timing mechanism of the device to continue functioning in the event of a power failure, so that the time-of-day computation is continued, although there is no timeof-day display if this requires excessive power, and the storage means of the microprocessor continues to hold the manually adjusted time periods of the set programme.

Further details of the power board 30 are shown in Fig. 3. To filter out any high frequency or high voltage transients in the mains supply, the mains input 32 is connected to the primary of a step-down transformer 48 through an interference-suppression capacitance and inductance (or resistance) circuit 50 and a transient suppression voltage dependent resistor 52. The output from the transformer secondary winding has any residual mainsborne interference or high frequency compo nent filtered out by a capacitance 54 and provides the low voltage supply 36 suitable for rectification and supply to the microprocessor 42. On-off switching of the load circuit 34 is performed by a change-over switch 58 controlled by a relay 60 operated by the output 40 from the microprocessor.The load circuit is also linked by capacitances 56 to the neutral of the mains input 32 to minimise any rapid voltage transients that may occur in the load circuit when the relay operates and prevent them affecting the microprocessor. The control of the output load circuits by a relay is preferred to the use of solid state devices such as triacs, since it can provide completed electrical isolation and needs dissipate very little power. The complete isolation of the output circuit from the mains supply makes the control of low voltage or d.c. loads possible.

Some of the circuitry of the display board 44 is illustrated in Fig. 4. This carries the 48element time display 4, the elements 6 of which may be light-emitting diodes. To minimise the number of connections to the board the circuit thereon also includes driving means 66 and a control transistor sub-circuit 68 for the time display 4. The driving means 66 comprises a 28-bit serial-in-parallel-out shift register with current-sinking current-limited outputs. In addition to power connections 68a, 68b the shift register has input connections 70, 72 from the microprocessor for clock and programme data.

The l.e.ds are connected in known manner in parallel pairs 6a, 6b to input lines 74a, 74b from respective pairs of control transistors 76a, 78a and 76b, 78b and the pairs of transistors are operated by 4 bits of the driving means 66 to alternately render active the lines 74a, 74b to one or other half of the t.e.d. array. The individual l.e.ds of each half of the array are sequenced by the other 24 bits of the shift register.

The l.e.ds of the time display 4 are fixed directly to the circuit board 44 and their electrical connections are made by means of the direct wire-bonding process used in semiconductor packages. The same technique can be employed for the shift register 66 and the control transistor sub-circuit 68. By this means, a compact-low-profile assembly is obtained which can be covered with a translucent plastics moulding for mechanical strength and which also forms a window through which the display can be viewed.

The microprocessor 42 may be a known commercial unit programmed to perform the required functions of this application. The remaining circuits on the main board will be adapted to suit such a unit. The battery 46 provides power for the processor to keep time and maintain stored data in the event of mains failure. In order to keep time accurately without requiring the provision of accurate timing components (e.g. crystal or close-toler- ance resistors and capacitors) the processor makes measurements of the difference in time taken for it to perform its normal cyclic tasks when the mains input is present, and the period of the mains a.c. input. Thus, when there is no mains input and the processor is running from the battery, it adds the previously measured time difference to its own task-cycle time, so simulating the period of the main supply.During normal operation the main supply frequency is sampled periodically and when the supply fails the sample before the last taken is used as a datum, so that there is less risk of using a false value associated with the cause of failure.

Preferably, the microprocessor is arranged to set automatically the 6 switching times when power is first applied to the unit, whether when the unit is initially installed or when power is restored after a battery has run flat. These initial switching times may be at the positions representing the most customary settings for the intended use in preference to setting them all to one end of the scale, for example.

In a simplified form of device according to the invention illustrated in Figs. 5 and 6, parts identical to those already described are indicated by the same reference numbers.

Thus, this device also has a time display 4 provided by a series of indicating elements, in this example again arranged as a rectilinear array of 48 similar elements: The display is driven by a microcomputer 42 that in most respects may be operated in exactly the same manner as described in the preceding embodiment. The micro computer also has an output of a relay 33 for actuating a load circuit performing the programmed function.

In the time display, the individual elements each correspond to a half hour period of a 24 hour cycle and the time of the day is indicated by the energisation of each element of the array in turn, in accordance with the inscribed time scale. For adjusting the position of the time of day indication, the two push-switches 12, 14 give forward and backward adjustments respectively. The elements 6 of the time display are also energised to show the periods of the 24 hour cycle when the microcomputer output is holding the relay in. Fig. 5 indicates a number of groups of such energised elements by the reference 6a. To distinguish between a time-of-day indication and a programmed-state indication, different manners of energisation are provided. For example, the time-of-day can be indicated by a flashing or winking element as shown at 6b on Fig. 1, and the programmed indication by continuous energisation, and by the use of different flashing duty cycles it is possible to distinguish whether the flashing time-of-day indication is coincident with the programme "on" or "off" state. The indicator light 20 on the panel is energised when the programme is in the "on" state.

In order to set the programme, in addition to the switches 12, 14, only the one change switch 1 7 is necessary. Pushing this switch causes the microcomputer to change over the programmed state at the period represented by the operative time-of-day element and, of course, to effect a corresponding change of the energisation of the element. By stepping the time-of-day indication through the 24 hour cycle lusing one or both of the push switches 12, 14 and operating the push switch 1 7 at the desired points on that cycle, a complete programme can be built up in the microcomputer store and simultaneously appears on the display 4.It may be arranged that the change switch can be held down continuously while the time-of-day display is stepped to make it simpler to set extended programme periods of any length, while the minimum programme length is determined only by the operative period of each element 6 so there can be as many changes in a programme as there are time display elements.

Thus, it will be noted in this example that for programming the setting conditions of the individual time periods, the means for adjusting the time-of-day indication in the analogue display of the device is arranged to be employed in such a way that it is necessary to provide only a single additional manual switch that has the function of changing the programmed state at chosen time-of-day indications.

Once the required programme has been set, the time-of-day indication can be adjusted by means of the push switches 12, 1 4 to the position best corresponding to clock time (with a finer adjustment as already described, if required) and the indication will then step forwards at each elapsed half hour under the control of the microcomputer, at each step the programme state set for that half hour period being selected and the relay thereby being operated in the programmed sequence.

It is possible to add a further manual switch to override the programme. As in the previously described embodiment this can be in the form of the override or boost switch 22, with an associated indicator light 23, which when operated changes over the output state of the programme from that existing until the next programmed change of state occurs, i.e.

it anticipates the next change of the pre-set programme. The switch is automatically reset and its illumination extenguished at the end of the override period, i.e. at that next programmed change of output state.

Fig. 6 illustrates an a.c. mains supply to the power supply unit 30 within the device which provides the necessary low voltage supply to the microcomputer as well as a timing reference signal derived from the mains supply.

Fig. 6 also illustrates how one or more auxiliary loads 33a can be connected in parallel with the load circuit to be operated by the relay.

Although not illustrated, a battery input can be provided to protect the stored programme against power loss. To minimise the costs of this provision, it may be arranged that the battery power supply does not operate the display but simply maintains the programme and the prevailing output state for some short period, possibly less than an hour or even only some tens of seconds.

Fig. 7 shows the front panel of a further programming device according to the invention with corresponding parts to those already described indicated by the same references, but having a second series of selector switches 1 6a arranged in a similar array 1 8a so that the device can control two different output functions independently, in particular space heating and domestic or draw-off hot water circuits. The programmes for each output function, while being based on the same six switching times, can therefore be set independently of each other, and the second functions control can include its own override or boost switch 22a and indicator light 20a.

In instances in which the two different functions have some interdependence, e.g. if a heating system uses thermosyphon circulation between a boiler and a hot water tank it is not possible to have space heating without hot water, the two corresponding programme selector switches of the two corresponding programme selector switches of the two arrays 18, 1 8a can be mechanically interlinked to prevent the user setting alternatives that the system cannot provide. This interlinking can be provided electronically also, in which case the switches can conveniently be in the form of momentary push buttons with illuminated tell-tales.

The separate switches 22, 22a may, as in the case of the programme selector switches, be interlinked if necessary.

A more flexibly controllable heating programme is provided in another form of device according to the invention, the front panel of which is illustrated in Fig. 8. In many respects it is identical to that preceding example, but in place of on-off switches for the heating selector switchs, there is provided a rectilinear array 82 of slider switches 84 giving a continuously variable adjustment for each of the individual time periods set, fom a "heating off" position to a maximum of approximately 80 degrees F (28 degrees C).

This form of control is used in conjunction with a temperature sensor 86 fitted in an optimum position in the space being heated, the sensor being schematically illustrated in Figs. 9a and 9b and comprising a thermistor 88 and a variable resistance 90 connected in series. The microprocessor provides a voltage source of known internal impedance across the terminals 92 of the sensor and so generates a voltage that is a function of the temperature sensed. This can be compared in the microprocessor with the adjustable reference voltage set by the operative slider 84 for the time period in question, and an output function control signal is generated accordingly.

The variable resistor 90 in the sensor is adjusted by a rotary knob 94 on the front cover of the sensor and allows a small local adjustment of temperature to be made by the user thereby modifying the combined resistance of the thermistor and resistor. The adjustment may allow a variation of temperature of plus or minus 10% relative to the setting of the programme selector slider - e.g. for a 60"F (15 C) nominal setting there will be a possible adjustment between 66"F and 54"F (1 3.5'C and 16.5"C). This form of adjustment may be particularly useful to make temporary adjustments to the heating level without having to change the previously set optimum programme on the heating selector sliders.

Further flexibility of operation can be provided by allowing changes of programme from day to day so that, for example, the different days of the week can be differently programmed. A front panel programming device according to the invention having this facility is illustrated in Fig. 1 0. It includes many of the features already described, but it will be seen that a two-character day indication 102 is now also provided on the panel.

One way in which the necessary characters can be provided by a segmental display is shown in Fig. 11, in which there are nine light-emitting segments provided from which to form the first character and six segments for the second character.

To programme the device, the "Set Day" push button 104 is used to step the "Day" display and the associated part of the microprocessor store. Operating the "Set Day" switch does not affect the time-of-day display, and of course it is arranged that during the normal operation of the device the day indication 102 is incremented automatically when the time-of-day display moves to 1 2.00 midnight.

The switching times are set in the manner already described, and if desired the variable temperature selection means could be employed here also. For simplicity it may be arranged that a single set of switching times is selected that will then be common to all the days of the programme. It is alternatively possible to provide the facility to set different switching times for each day but this adds to the complications of use.

In addition to other features already described with reference to the earlier embodiments. there are for example, "Omit Heating" and ' "Omit Water" push switches 106, 108 that are operated when the device is being programmed to arrange that on particular days of a programme period the respective output circuit will be maintained in the "off" state for the duration of the day or days concerned. They can be cancelled by operating the switches a second time, and they incorporate illuminating elements that are lit on those days when the "omit" function is operative.

The "End Today" push switch 110 cancels any remaining "on" periods of the current day's programme and it too is illuminated so show that it has been operated.lt is selfcancelling at the end of the day's programme but can also be cancelled before then by pressing the switch again.

Other functions could be provided as well as or instead of the "End Today", "Omit Water", "Omit Heating" functions just described. A single switch could perform the function of the "Omit Water" and "Omit Heating" switches operated together. The respective series of selector switches 1 6 and 1 6a could be used to define two different programmes for a one-output device, the programme to be operative on any given day being chosen by operating alternative "Select P1" or "Select P2" switches while the appropriate day is being displayed. Many combinations of functions on a multi-day unit are possible, but the basic operation of the unit around its display of time-of-day and switching times, in conjunction with whatever programme select function is energised for the particular day, remains generally as previously described.Using the "Set Day" switch 104 to step through the 7 day cycle the selected options for each day can be observed from the states of the relevant function indicator lights.

Fig. 1 2 illustrates a modification that can be employed in any of the embodiments of the invention described above. The front panel face or at least a major part of that face is covered by a hinged dust cover 1 20 of a transparent but tinted plastics material, this protecting the control elements which can disturb the selected programme. On a suitable part 1 22 of thevinner surface of the cover there are printed brief operating instructions that in the illustrated position of the cover are clearly visible, being in contrast to the tinted appearance of the cover. The instructions are, however, in a colour that closely matches the panel front face, so that when the cover is closed the printing becomes invisible because of the lack of contrast with its background.

For the best effect the part 1 22 is then located over an area of the panel front face that has no markings, but in any case it should be confined to an area where it will not hinder the user's view of the time display, the timing switches or the selector switches and their indicators.

In each of the examples of the invention illustrated, the display is easily comprehensi ble because the time display,the setting time switches and the programme selector switches are all arranged as parallel linear arrays giving the user complete information of the operating conditions set by the device and the current state of the programme. In place of the horizontal rectilinear arrangement shown, a vertical rectilinear arrangement could be used instead, or even a curvilinear arrangement, i.e.

arcuate or circular, in each instance possibly as more than one line of elements. It will normally be preferred that the setting switches and the selector switches follow the same rectilinear or curvilinear configuration as that chosen for the time display for ease of viewing and use. The microcomputer may, of course, produce the required display in other ways than that described. Although illustrated examples show a light-emitting diode time display, it is possible to use other means, such as liquid crystal, preferably illuminated, gas discharge, fluorescent anode, or electroluminescent means.

For the selector switches to give a visual representation of the selected programme, the switch actuators may be in many different forms, e.g. sliders, rockers or paddles, but preferably have coloured portions and/or illumination means for further visual distinctiveness of their different positions. With the illustrated paddle switches 16, 16a, each can have a visually distinctive indicator appearing in an upper position if the switch is off and the same or another indicator appearing in a lower position if the switch is on.

Some of the accompanying drawings also appear in our co-pending application, No 8201 647 filed simultaneously herewith which relates to another invention illustrated therein.

Claims (24)

1. A programming device for at least one electrical output function comprising an electronic circuit for producing output signals controlling said at least one output function and arranged to operate in conjunction with adjustable setting means adapted to define setting control values of said at least one function for adjustable time periods within a larger overall time period, the device having electronic analogue display means for displaying said overall time period and for indicating thereon time-ofday and the adjustably set time periods, and means for the display of setting conditions within said periods of the overall time period.

2. A programming device according to claim 1 wherein a common display means is provided for time-of-day and said adjusted time periods.

3. A device according to claim 2 wherein time-of-day and the adjusted time periods are arranged to be displayed simultaneously, and means are provided for distinguishing between the indications of time-of-day and said time periods.

4. A device according to any one of claims 1 to 3 wherein the display means has a linear configuration and time-of-day is arranged to be displayed by unidirectional displacement of an indication along said configuration, and said adjustable setting means comprise a series of elements for setting the limits between successive time periods arranged in an array parallel to said linar configuration.

5. A programming device according to any one of the preceding claims wherein the adjustable setting means comprises an arrangement of manually adjustable elements that provide a time-sequence display of the setting control values within the individual periods defined by the timing means.

6. A device according to any one of the preceding claims wherein the setting means comprise both adjustable timing means adapted to delineate adjustable time periods within the larger overall time period, and a series of adjustable programming elements each for setting a control value for a respective delineated time period, whereby said at least one output function is determined in each adjustable time period by setting of the programming element associated with that period, the programming elements thereby displaying the control values set within said delineated time periods as displayed on the analogue display means.

7. A device according to claim 6 wherein the display means has a linear configuration and time-of-day is arranged to be displayed by unidirectional displacement of an indication along said configuration and said programming elements for the successive time periods are arranged as an array of selector switches parallel to said linear configuration.

8. A device according to claim 6 or claim 7 wherein the programming elements comprise at least one manually adjustable switch providing variable temperature settings for an electrical output function formed by or regulating heating means.

9. A device according to claim 8 in combination with temperature adjustment means comprising a thermosensitive device for regulating said heating means and arranged to provide the electronic circuit with a signal representative of the temperature in the vicinity of said element, the electronic circuit being thereby actuable to produce an output in dependence upon the comparative values of said signal and the temperature setting of said at least one adjustable programming switch.

10. A device in combination with temperature adjustment means according to claim 9 wherein said thermosensitive device is provided with adjustment means to alter its signal at a given sensed temperature in order to modify the electronic circuit output signal at a given setting of said at least one adjustable programming switch.

11. A device according to any one of claims 1 to 3 wherein the electronic analogue display is arranged to display the setting conditions in the individual periods of the overall time period.

12. A device according to any one of the preceding claims having a linear array of lightemitting elements for said analogue time display means, each repressnting a discrete time period.

1 3. A device according to claim 12 comprising means for adjusting Ilbe time-of-day indication to a fractional paii: of the time period representeeS by caeka element of said display means.

14. A device according to any one of the preceding claims comprising on-off manual control means for over ride of a pre-programmed setting of the device.

1 5. A device according to any one of the preceding claims etimprising manual control means for override of a pre-programmed setting of the device and arranged to be operable to change the state cf or rnaintaiei the changed state of at least one output function for a determined time period.

16. A device according to claim 14 or claim 15 comprising light-emitting means for indicating the actuation of said manual control means.

17. A device according to any one of the preceding claims arranged to be operated by an external power input and comprising a stand-by battery-powered means which, upon failure of said exiernal input, is adapted to maintain the operation of computation means for the time-of-day display and of store means for the adjustable time period values.

18. A device according to any one of the preceding claims wherein means are provided to set pre-programmea' switching times for said output functions upon the application of electrical power to the device and before the operation of the adjustable timing means.

19. A device according to any one of the preceding claims wherein the time-of-day display extends over a 24-hour period and means are provided for programming a cycle extending over a plurality of days, and wherein a common 24-hour series of switching times is arranged to be set for all the days of the cycle but means are provided for defining different sequences on different days in the course of said common switching times.

20. A device according to any one of claims 1 to 1 8 wherein the time-of-day display extends over a 24-hour period and the setting means are able to set mutually indipendent series of adjusted time periods for successive days of a programming cycle extending over a plurality of days, means being provided to display each series of adjusted time periods in turn on their alloted days of the cycle.

21. A device according to claim 19 or claim 20 arranged to be loaded with a 7-day programme and provided with a 2-character display means for indicating the effective day of the week in the programme cycle.

22. A device according to claim 21 wherein said characters are each formed by selective illumination of groups of elements in two light-emitting arrays of segmental elements, the first character array having 9 elements and the second character array having 6 elements.

23. A programming device for at least one electrical output function comprising an electronic circuit for producing output signals controlling said at least one output function and arranged to operate in conjunction with adjustable setting means adapted to define setting control values of said at least one function for adjustable time periods within a larger overall time period, the device having electronic analogue display means for displaying said overall time period and for indicating thereon time-ofday and the adjustably set time periods, said setting means comprising an arrangement of manually adjustable elements that provide a time-sequence display to the setting control values within the individual periods defined by the timing means the device thereby providing a simultaneous display of time-of-day, together with the delineated time periods and the setting conditions within said periods of said overall time period.

24. A programming device constructed and arranged for use and operation substantially as described herein with reference to any of the examples in the accompanying drawings.