GB2104254A - Electronic timing devices - Google Patents

Abstract

An electronic controller such as a time switch has a four digit segmented display (12) for indicating the time of day. When it is required to indicate the day of the week, for example while setting up a weekly control sequence, individual upright segments are used as pointers to identify respective days, denoted by their corresponding initial letters aligned with the segments. <IMAGE>

Description

SPECIFICATION Electronic timing devices This invention relates to electronic timing devices, and particularly, though not exclusively, to electronic controllers.

Controllers are widely used, for example, for providing (electrical) output signals at preselectable times, in some cases on preselected days of the week. Such controllers have until recently generally been electro-mechanical in nature, and thus prone to wear of moving parts and subject to the cost of manual assembly of many component parts. Furthermore, a choice has usually had to be made between flexibility of operation, involving a complex and costly design, and simplicity and economy of construction, which severely limits the capabilities of the controller. With the introduction of digitial electronics, in particular microprocessors, and solidstate display devices such as liquid crystal displays, it has become possible to contemplate the design and manufacture of controllers which offer sophisticated combinations of control capabilities but use very few individual components.

However, the ability to provide, for example, automatic selection of different preprogrammed control sequences for different days in the week has resulted in another problem. It is obviously desirable to be able to indicate not only a particular control sequence but also the day(s) of the week to which it applies (though not necessarily simultaneously). In known display arrangements this has been accomplished by providing both a time display (such as a setofseven-segmented displays) and a separate day-of-the-week display (such as seven selectively illuminated lamps or light-emitting diodes). However, this entails both the cost of two displays and the need for sufficient connecting pins to drive the displays on the controlling microprocessor. This constraint may severely limit the choice of microprocessor or even render the design impracticable.It is therefore an object of the invention to alleviate this problem.

According to one aspect of this invention there is provided an electronic timing device for providing output signals at preselectable times on preselectable days of the week, said timing device having a display including at least four digits of the segmentated type for displaying said times, wherein at least some of the segments making up said digits are also used as pointers to indicate respective ones of the days of the week.

An electronic timing device in accordance with this invention for use as a controller will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows the display panel of the controller; Figure 2 shows the four-digit seven-segment display identifying days of the week; Figure 3 shows the configuration of a sevensegment numerical display device; and Figure 4 is a table showing code and segment drive signals for different display patterns.

The controller to be described is intended to provide separate timed on/off control of each of three outputs, for controlling, for example, heating of three different areas of a building. Two of the outputs can be switched on and off again to provide a total of three on-periods per day, while the third output can be thus switched twice a day. In addition, any selected switching operation may be pre-set to occur only on pre-chosen days of the seven-day cycle.

The circuitry of the controller comprises a microprocessor having four switches connected to various inputs and three relats coupled via buffer amplifiers and triacs to its outputs, plus a liquid crystal display device. The programming of the microprocessor to scan the switches, implement the switch functions, maintain clock time, operate the relays at the desired times and appropriately drive the display generally follows conventional principles, and only those details which are relevent to the present invention, concerning the manner of data presentation to the user, need be described here.

Referring to Figure 1,the liquid crystal display device 10 is generally rectangular and has a fourdigit seven-segmentated display 12, three sets of arrow-heads 14, 16 and 18 along its left, lower and right edges, and a dot indicator 20 at the lower right-hand corner. Beneath the left-hand edge of the display device 10, there is a column of four switches 22 to 28. Alongside each switch there are four legend areas 30, each vertically aligned beneath a respective one of the four arrow-heads in the set 16. During setting of the controller, the three arrow heads in the set 14 point to respective legends along the left-hand edge of the display to indicate output is being set, while those in the set 18 point to legends along the right-hand edge of the display to indicate which switching period is being set for that output.The indicator 20 shows where it is the start (on) or end (off) of the period that is being set.

During normal operation, the left-hand one of the arrowheads 16 is visable, and the controller runs normally. The preset timing can be overridden manually for any of the outputs by pressing the appropriate one of the switches 24 to 28 (as indicated by the left-hand column of the legend areas 30) to alter the state of the corresponding relay.

If it is desired to alter the preset timing, the switch 22 is pressed once, whereupon the second arrowhead from the left in the set 16 becomes visible, indicating that the switches 24 to 28 now have the functions shown in the second column of legend areas 30 from the left. In particular, the switch 24 sets the hours, the switch 26 sets the minutes (both as indicated conventionally by the display 12), while the switch 28 selects the next timed switching operation for display and possible alteration. The operation involved is identified, as explained above, by the arrow-heads 14 and 18 and the indicator 20.

To alter the selection of days for which a particular switching operation is effective, the switch 22 is pressed again, moving the displayed arrow-head in the set 16 one place to the right, thereby indicating that the switches 24 to 28 have the functions shown in the third column of legends 30 from the left. The manner in which the days of the week are displayed will be discussed in more detail below.

Finally, pressing the switch 22 one more renders the right-hand column of legends 30 applicable, so that the switch 24 can be used to set the clock hours, the switch 26 to set the tens of minutes and the switch 28 to set the minutes. During this operation the display 12 indicates the time of day in the conventional manner. Thereafter, the controller is returned to its normal operating mode by pressing the switch 22.

To identify the individual days of the week, use is made of the pairs of upright segments in each of the seven-segment digits of the display 12. Thus, as shown in Figure 2, the right-hand upright pair of segments in the left most digit is used to point to 'S' for Sunday; the uprights of the next digit point to 'M' for Monday and 'T' for Tuesday; and the remaining uprights likewise point to W,T,F, and S for Wednesday, Thursday, Friday and Saturday. The left-hand upright of the left-hand digit can be used, as also indicated in Figure 2, as a PM indicator if the clock display is of the 12-hour variety.

The uprights of the display digits are used in two ways. If it is merely required to indicate the current day of the week, the upper half of the appropriate upright is energised to point to the required letter. In the 'set day' mode of operation mentioned above, this pointer can be stepped along successive days by pressing switch 24 ('Move Pointer') until it reaches the correct day, whereupon the switch 26 ('Enter') is pressed.

If the switch 28 is now pressed, the days for which a particular switching operation is applicable are displayed. To this end, the upper half of each upright corresponding to an applicable day is energised as a marker, while the lower half of only one upright is energised to point to the day for which the selection of that switching operation can currently be changed (by pressing the switch 26). As before, pressing the switch 24 advances the pointer along the successive days. Thus, in the example shown in Figure 2, a 'particular switching operation has been selected or marked as being effective on Monday through to Friday inclusive, as indicated by the upper halves of the pairs of upright segments; and the selection of that operation for Sunday could be changed (in this case enabled) by pressing the switch 26.Pressing the switch 24 would move the pointer (that is, the lower half of a pair of upright segments) along from Sunday to Monday.

As mentioned above, the programming of a microprocessor to implement the required functions described above involves conventional principles and techniques well known to those skilled in the art.

However, one manner in which the day-of-the-week display can be obtained will be described with reference to Figures 3 and 4.

During this discussion the various segments of the seven-segment display will be identified in conventional manner, as shown in Figure 3.

Inspection of the various combinations in which the markers and pointers can occur (bearing in mind that onit one day pointer is required along the whole display), shows that any one digit may have to display any one of twelve different patterns, as shown in the DISPLAY column of Figure 4. Assuming that the seven segments a tog of each digit are coupled to seven of the eight lines of the microprocessor data bus (a being coupled to the least significant bit line), the bytes corresponding to each required display pattern are shown in the SEGMENT DRIVE BYTE column, with a 1 indicating that the corresponding segment is energised. An arbitary 4-bit code, in which the two lower significance bits code for the upper segments of each digit and the two higher significance bits code for the lower segments, is also shown in the 4-BIT CODE column for each display pattern.Finally, an arbitary readonly memory (ROM) address sequence, starting at hexadecimal address 1C60, and the associated hexadecimal data stored at each address (and corresponding to the SEGMENT DRIVE BYTE values) are shown in the two right-hand columns of Figure 4.

Each digit of the four-digit display has associated with it a specific random-access memory (RAM) location for storing the current value of the 4-bit code associated with that digit. Thus, for the display shown in Figure 3, the 4-bit codes would be 0100, 0011,0011 and 0010 respectively. To energise the segments of any digit appropriately the microprocessor need merely take the current 4-bit code for that digit from the corresponding RAM location, add it to the value 1 C60, and then apply the ROM data stored in the address defined by the result of the addition to the data bus, simultaneously enabling the appropriate display digit to accept the data in any conventional manner. It will be noted in this respectthat the values of the 4-bit codes shown in Figure 4 correspond to the decimal numbers from 0 to 11.

For example, the 4-bit code for the left-hand digit in Figure 2 is 0100 (decimal 4). Adding this to 1C60 gives an address value of 1 C64. The ROM data in address 1 C64 is 04, which, when applied to the data bus, with the display segments connected as specified, causes the segment cto be energised as required.

Thus, the microprocessor program only has to update the 4-bit codes in the RAM locations for the four display digits as and when required in response to manual operation of the switches 22 to 28, and repetitively supply the corresponding ROM data to the display segments as described above, and the required day-of-the-week pointer (and markers) will automatically be displayed.

Several modifications can be made to the described embodiment of the invention. For example, if the clock display is of the 12 hour variety as mentioned earlier, the display 12 can be of the so-called 31/2-digit type, where the leftmost digit is the -digit and comprises at least one upright segment, and preferably two aligned upright segments corresponding to the segments band c of Figure 3, for displaying the numeral 1. In this case, the display is provided with a separate AM/PM pointer.

Additionally, other forms of segmented digit display, eg in which the segments are slightly curved or otherwise stylized, can be used, and segments thereof other than those specifically chosen in the preferred embodiment, including horizontally ex tending segments, can be used as pointers to indicate the days of the week if desired. Finally, a horizontally extending segment can be used an as a.m./p.m. indicator if desired.

Claims (8)

1. An electronic timing device for providing output signals at preselectable times on preselectable days of the week, said timing device having a display including at least four digits of the segmented type for displaying said times, wherein at least some of the segments making up said digits are also used as pointers to indicate respective ones of the days of the week.

2. Atiming device as claimed in claim 1,wherein the segments making up said digits include at least seven substantially upright segments disposed in a substantially horizontally extending row, each of said upright segments being used to indicate a respective one of the days of the week.

3. Atiming device as claimed in claim 2, wherein at least the three rightmost digits are of the sevensegment type and each comprise two horizontallyspaced pairs of aligned upright segments, and wherein the fourth digit comprises at least one pair of aligned upright segments.

4. A timing device according to claim 3, wherein the upper segments of each of said seven pairs of upright segments are used to indicate said days of the week.

5. Atiming device according to claim 3, wherein one segment of each of said seven pairs of upright segments is used to indicate whether the respective day of the week has been preselected for provision of output signals, and the other segment of each of said seven pairs of upright segments is used to indicate the day oftheweekforwhich the preselected status can currently be altered.

6. A timing device according to any one of claims 3 to 5, wherein the fourth digit is also of the seven-segment type, wherein time is displayed on a 12-hour clock basis, and wherein at least one segment from the pair of upright segments of the fourth digit not used to indicate a day of the week is used for a.m./p.m. indication.

7. A timing device substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

8. Atiming device substantially as hereinbefore described with reference to the accompanying drawings.