Programmable automatic power-off system for a digital terminal

A programmable unit for attachment to a work-station whereby power to the work-station will be shut off after a pre-set time-period, unless work-station activity occurs before the outset of the time-period, when the pre-set time-period will initiate again.

FIELD OF THE INVENTION 
This disclosure relates to the timed control of power involving terminals 
and work stations in an individual terminal work station or a network of 
terminal work stations. 
BACKGROUND OF THE INVENTION 
Due to present concern for conservation of power usage, many areas of 
technology have conceived and developed methods for conserving electrical 
power usage. 
One of the commonly occurring situations which involves waste and 
unnecessary use of power is the situation wherein offices where 
engineering groups, realtors' offices, brokerage offices, clerical 
offices, etc., using digital equipment, may use their work station 
terminals for very long periods of time or, due to other duties and 
requirements, make only intermittent use of the work station or receiving 
units in a network. 
To this end, it has often been office policy or plant policy that equipment 
be turned off when not in use or overnight when the office or plant is 
closed. 
Quite occasionally, however, the operators of terminal equipment may not 
want to turn off the power in their terminals when being interrupted or 
having to leave for short periods, after which they intend to return. 
However, sometimes the unavoidable absences extend to longer periods of 
time and there is no chance or occasion to return and shut off the 
terminal equipment. 
Thus it is conceivable that consideration should be given to automatic 
methods of power turn-off for work station and other terminals. 
This could involve considerable savings since many plants and offices use 
not only two or three work station terminals but sometimes these number in 
the hundreds of work station terminals. 
SUMMMARY OF THE INVENTION 
In order to eliminate the need for worrying as to whether or not a system 
or a set of work stations or a single terminal have been used with 
attention to the most economical power savings, the present disclosure 
involves an automatic timing and power turn-off system which may be 
provided within each work station terminal or which may be supplied as a 
separate and discrete modular unit which is attachable to a work station 
terminal. 
In the presently described system there is provided a timer control logic 
unit whereby a coded key-stroke code can be used to set a desired time-out 
into the unit so that, if no keyboard or data transmission activity has 
occurred within that period of time-out, then the logic unit will activate 
a power control relay to shut-off power to the work station terminal. 
The programmatic feature provides a flexibility and user-control to 
determine what period of inactivity should be used to constitute the 
time-out period for developing a power-off situation. It permits the 
flexibility for leaving the terminal on for long periods of time if 
desired. 
The present system contemplates that if, during the running of the time-out 
period, there is any key-stroke activity or data messages to the work 
station terminal, then the previous time-out period will be canceled and a 
new time-out period will be started. Further, the present system permits 
for an immediate "turn-on" of power, either by a manual override button on 
the power control relay or by means of a mere touch of the key-stroke 
button of a terminal work station. 
The present configuration involves the use of a power control relay which 
can switch power off/on to the terminal work station and whereby the power 
control relay is regulated by a timer control logic unit. Thus, by keying 
the keyboard on the work station, there is developed a key-stroke code 
which can be conveyed to the timer control logic unit to establish the 
running of the time-out period and also for the cancellation and 
re-initialization of the time-out period should there be any activity 
whatsoever in the form of key-strokes on the work station or data being 
transferred from another terminal into the local work station terminal.

DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 shows a power control relay A which conveys alternating current 
power to a terminal or work station T. The power control relay A has one 
input from the AC power source 10 via a mechanical on/off switch 11. The 
other input to the power control relay A is a manual overrride switch 10m 
which is used to close the relay in A so as to apply power to the terminal 
T. 
The terminal T provides DC logic power on line 15 to the power control 
relay A and also, on line 16, to another unit designated as the timer 
control logic unit B. 
An output line 18 from the timer control logic unit B connects to the power 
control relay A for purposes of turning the power off by opening up the 
relay in the relay control A. The lines 14 convey AC power to the terminal 
T. 
The power control relay A and the timer control logic unit B could be 
placed and mounted in an external box and constitute an independent unit 
which could be attached to the system. On the other hand, this combination 
of control relay A and timer logic unit B could all be built into the 
terminal or work station T. 
The DC logic power shown on line 15 of FIG. 1 could be provided internally 
within the work station or it could be generated within the control relay 
A and timer logic unit B. 
Alternatively, the DC logic power for the timer control logic unit B could 
be placed at the AC power source 10 so that the timer control unit is 
always energized as long as the AC power is supplied at 10. 
Another possibility for power to the timer control logic unit B is that it 
be provided with its own internal battery unit to provide the DC logic 
power which would replace the power coming on line 16 from terminal T. 
As seen in FIG. 1, there is another output bus 17 which exits from the 
terminal T and which provides an eight bit code entitled "Key Stroke 
Code". This Key Stroke Code is useful to set the time-out period function 
and will be described in connection with FIG. 2. 
The power control relay A has a normally closed relay switch which can be 
opened or interrupted when the "power-off" signal on line 18 is received 
from the timer control logic unit B. This will cause the relay in the 
control relay A to open and to stop the AC power on line 14 to terminal T. 
The power control relay A closes the relay when the manual override switch 
10.sub.m is activated. It is needed to "turn-on" the power after the unit 
has been "powered off" via the automatic timer control logic unit B. 
However, if the time-out period has not yet run, then any time there is any 
key-stroke activity in the terminal T where the terminal T is receiving a 
message, then the timer control logic unit B will cause the power control 
relay A to be reset and to re-initialize the timer control logic B so that 
a new time-out period is now started and the old one has been effectively 
canceled. 
As seen in FIG. 1, the DC logic power outputs from terminal T over to the 
power control relay A on line 15. Another line 16 branches off the DC 
logic power over to the timer control logic unit B. The power conveyed on 
line 16 functions to convey DC power from the terminal T over to the timer 
control logic unit B. 
In FIG. 1, an eight-bit coded signal is conveyed on bus 17 over to the 
timer control logic unit B. This signal is manually keyed-in by the 
operator of the terminal T to represent a settable time-period "P" which 
will permit a "power-on" condition to continue until the time period P has 
run out, after which the timer logic unit B will "shut-off" the power via 
the control relay A. 
It should be noted here that the time period P can only run to its full 
termination as long as there has not been any activity on bus 17; that is 
to say, there have been no data transmissions involving the terminal T for 
the time period P. 
The time-out period P may be looked at as the "maximum pre-set" time period 
between key-stroke activity. Thus, if any key-stroke activity activates 
signals on bus 17, the previous time-out period P is canceled and a new 
time-out period is started so that there is no need for manual resetting 
or concern as to how the new time period will be set. 
The eight-bit bus 17 may be looked upon as a "key-stroke bus" and is a tap 
signal that constitutes a communication line between the keyboard of the 
terminal and the terminal T itself. This communication line could be 
expanded and tapped to form a communication line between the terminal T 
and the main host system in order to detect any receive/send activity 
between the terminal and the host system. Thus, any such receive/send 
activity between the terminal and the host system will, in effect, cancel 
the last pre-set time period P and will re-initialize and restart the 
running of the time-out period. 
Referring to FIG. 2, there are shown the elements of the timer control 
logic unit B. An internal clock B3 feeds its clock output on line 33 to an 
eight-bit register B2 and also to a 16-bit counter B4 on line 34. 
The decoder-control logic B1 receives the key-stroke code from the terminal 
T and decodes it in the following fashion. If the code is the 
predetermined code which would set up the program value of P, then it will 
put the register B2 and the counter B4 into the "load mode" via lines 24 
and 23, respectively. Then it will take the next key-stroke code as the 
value P which may, for example, be the number of minutes, and load this 
code into the eight-bit register B2. On the next clock, this value will be 
transferred to the upper eight bits of the 16-bit counter B4. At the same 
time, the decoder-control logic B1 will put the eight-bit register B2 into 
the "hold mode" via the control line 24. Then the decoder controller logic 
B1 will put the counter B4 into the "count-down mode" via the control line 
23. 
Finally, the decoder-control logic B2 will set the timer enable flag B5 
(flip-flop) via line 21, thus enabling the power control logic to AND gate 
B7. 
If the key-stroke code is any other code (non-setup code), then the 
decode-control logic B1 will put the 16-bit counter B4 into the "load 
mode" via the control line 23 in order to reload the contents on the 
eight-bit register (B2) value into the upper eight bits of the 16-bit 
counter B4. Then the decoder-control logic B1 will put back the counter B4 
over into the "count down" mode again via the control line 23. 
Optionally, another predetermined key code could be defined for the 
"disable" function. In this case, the decoder-control logic B1 would 
detect this code and simply reset the timer enable flag flip-flop B5 via 
the control line 21. 
As the "power-up clear" signal (when starting the system) can be generated 
by the DC power supply of the terminal T, by the power control relay A, or 
internally by the timer control logic unit B, then this signal will reset 
the timer enable flag flip-flop B5 in order that it does not have a false 
"power-off" signal during initialization. 
The "power-up clear" signal also initializes the decoder-control logic B1. 
This includes presetting the registers B2 and counter B4 with a "default 
value", which is a predetermined value in some available programmable 
storage. 
In the simplest default case, the "default" would do nothing, which means 
that the entire "power-off" feature is disabled, which is already done by 
the resetting of the timer enable flag flip-flop B5. 
The internal clock B3 provides clock signals to register B2 and counter B4. 
The clock period can be determined by defining the "key-byte" value. 
A simple example is the case where the key-stroke code of eight bits is the 
binary equivalent of "minutes", then the clock period must be 256/60 
Hertz. 
However, this could be done many different ways. The decoder-control logic 
B1 could convert this by mapping the key-stroke code to another value 
before loading the eight-bit register B2. Also, the 16-bit counter B4 
could be expanded for different clock resolution. 
The 16-bit counter B4 value will feed the time-out detector B6 of FIG. 2, 
which then detects all "0" conditions as a "time-out" situation. 
Then the time-out detector B6 will put the 16-bit counter B4 into the "hold 
mode" via the control line 37, thus stop the counter from counting down. 
Further, the time-out signal 37 feeds the AND gate B7. In actual 
operation, the lines 36 and 37 could be operated as the same output line 
from time-out detector B6. 
In FIG. 2, the line 31 from the timer enable flag flip flop B5 would be set 
to its "true" value by the decoder-control logic B1 during the earlier 
phase of operation. Now, when the time-out line 36 becomes "true" by the 
time-out detector B6, then the output of the AND gate B7 becomes "true" on 
line 18. This line is designated as the "power-off" line, which is 
connected to the power control relay A in order to open up the relay and 
to turn off the power to the terminal T. 
There has herein been described a power control system for conserving 
energy in the usage of work stations and terminals in small or large 
digital networks. The benefits of the present system provide for automatic 
turn-off of power to any one or more terminals connected to a 
communication line when that particular terminal has been left unattended 
or unused, whether in the transmit or in the receive mode. However, should 
any activity occur before the time-out period has run out, then the system 
will be reset to cancel out the old running time period and to 
re-initialize and re-establish a new running time period before the power 
turn-off cycle will have shut off the power to the unit or other connected 
terminals in the system. 
While a specific embodiment has been described which accomplishes the above 
mentioned features, it should be understood that other variations of the 
applicable concept may be effectuated but would still fall within the 
scope of the appended claims hereinafter.