Time controls with enhanced timing range

Details Time controls with enhanced timing range Time controls with enhanced timing range

2001-07-11

2004-06-08

Toatley, Jr., Gregory J. (Department: 2836)

Electrical transmission or interconnection systems

Switching systems

Plural switches

C219S719000, C219S492000

Reexamination Certificate

active

06747375

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention generally relates to time controls, such as repeat cycle timers or interval timers. More specifically, the present invention relates to a time control that includes a non-linear cycle time setting and a duty cycle setting such that the time control provides a broad range of timing capability.
In the early days of timer design, mechanical timers were available that were driven by synchronous AC motors to provide a means to generate “repeat cycle timing” of a load. These same types of synchronous motors also provided a means to generate “interval timing”. The time base in each of the time controls was generally set by the motor and a set of appropriate gears to slow down the motor rotation speed to the desired final speed. In the early days of timer design, adjustable mechanical cams and similar apparatus could be attached to revolving pieces of the control and these links enabled the user to adjust the duty cycle or interval time. However, the basic time base was very fixed and related to the final rotational speed of the “setting wheel”.
As timer design evolved, it became advantageous for designers and manufacturers to use analog oscillators as the adjustable time base for various time keeping functions. One common type of analog oscillator coupled a potentiometer to a knob with a printed time scale showing the approximate time on the face plate of the timer. The printed time scale served as a means to enable a widely variable time base that was not expected to be repeatable or extremely accurate for both repeat cycle times and interval timers.
As time keeping technology continued to evolve, it became advantageous for designers and manufacturers to use digital countdown circuits that were synchronized to accurate crystal time bases or an AC power line. Digital countdown circuits are typically found in either discrete digital logic components or can be implemented by software running within a microcomputer. In either case, these techniques offered a means to provide an accurate and repeatable timing function for both the repeat cycle timers and interval timers.
As shown in
FIG. 1
, a conventional repeat cycle timer can include two rotary knobs
12
and
14
that allow a user to set an “ON” time and an “OFF” time independently of each other. In the sample of the prior art illustrated in
FIG. 1
, each of the rotary time setting knobs
12
and
14
includes a linear time range spanning between 30 seconds and 15.5 minutes in thirty-two equally spaced steps of 30 second resolution. Thus, when utilizing the repeat cycle timer
10
illustrated in
FIG. 1
, the user can set a time base for the complete cycle of a minimum of 60 seconds to a maximum of 31 minutes and a duty cycle of 3.3% to 96.8%. In this control configuration, the user can select a desired repeating time base by summing the “ON” time and the “OFF” time of each rotary knob
12
and
14
. Similarly, the duty cycle (or active load percentage) can be set comparing the ratio of the “ON” rotary knob
12
and the “OFF” rotary knob
14
.
When utilizing the rotary timer
10
of the prior art, if the user needs a repeating time base of one minute, each knob of the cycle time could be set to 30 seconds. At this minimum value, there would be only one percentage setting available—50% duty cycle since the minimum resolution for each knob
12
and
14
is 30 seconds. In a second example, if the repeating time base was required to be two minutes, the sum of the settings of both knobs
12
and
14
could be set for that two minute requirement. In the prior art repeat cycle timer
10
illustrated in
FIG. 1
, three options would then be 30 seconds “ON” and 90 seconds “OFF” (25% duty cycle), 60 seconds “ON” and 60 seconds “OFF” (50% duty cycle), and 90 seconds “ON” and 30 seconds “OFF” (75% duty cycle). These two examples illustrate that the ultimate flexibility of the variable percentages is limited by the necessary choice of the time base. Secondly, unless the user carries a calculator, the mental math required to calculate the percentage duty cycle may be quite difficult. For example, 3.5 minutes “ON” and 13 minutes “OFF” requires a mental calculation of (3.5)/(3.5+13.0)=21.2%.
Therefore, it is an object of the present invention to provide a time control unit that allows the user greater flexibility, convenience and independence in setting both the repeating time base and the percentage duty cycle. It is a further object of the invention to provide a time control unit that includes one knob to define a timing range that grows in a non-linear manner from a relatively small minimum time to a relatively large maximum time. Further, it is an object of the present invention to provide a second knob that allows the user to define the duty cycle in a non-linear manner, preferably with greater resolution between 1% and 10% and 90% to 100% duty cycle. Further, it is an object of the present invention to present a time control unit that presents the user with an easy to understand determination of both the repeating time base and the load duty cycle.
SUMMARY OF THE INVENTION
The present invention relates to a time control unit that has a time base dial to set overall cycle time and a duty cycle dial to control the percent of the cycle time that a load is energized.
The time base dial of the time control unit is used to set the overall cycle time and includes a plurality of individual time base settings that increase in a non-linear manner from a minimum setting to a maximum setting. In one specific example of the invention, the values for each discrete position of the time base dial can be used to set the cycle time between a low value of 15 seconds and a high value of 24 hours. The individual settings between the high and low value generally increase in an exponential manner such that several decades of values can be represented over the thirty-two discrete settings for the time base dial.
The time control unit further includes a duty cycle dial that allows the user to accurately set the percentage of the cycle time which the load is activated. The duty cycle dial includes a plurality of discrete positions that allow the user to accurately determine the percentage of time the load is activated during the overall cycle time. The individual positions for the duty cycle dial can increase from a minimum setting to a maximum setting in either a linear manner or a non-linear manner, depending upon the user requirements. In one embodiment of the invention, the settings for the duty cycle dial include higher resolution near the 0% and 100% settings and a lower resolution near the 50% setting. Alternatively, the settings can be selected to increase generally exponentially to provide very high resolution near either the 100% or 0% settings, depending upon the user requirements.
The time control unit of the present invention includes a control unit that calculates and controls the cycle time and duty cycle based upon the settings of the time base dial and the duty cycle dial. The control unit polls each of the rotary switches that serve as the time base dial and the duty cycle dial to determine the current position of each dial. Based upon the current position of the dial, the control unit counts the required times and operates a relay circuit coupled to the control unit. The relay circuit, when closed, provides power to a load. The control unit can be programmed to allow the settings of both the time base dial and the duty cycle dial to be adjusted to any selected values such that the time control unit of the present invention can provide the user with extremely accurate and variable settings for both cycle time and the duty cycle.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.


REFERENCES:
patent: 3653699 (1972-04-01), Podesta et al.
patent: 3697770 (1972-10-01), Murata et al.
patent: 3723676 (1973-03-01), Harris
patent: 3768469 (1973-10-01), Myers
patent: 3992960 (1976-11-01), Rulseh
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