Electronic Timer

This invention relates to an electronic timer, and more particularly to an oscillation counting timer which is used in a sequence circuit device or the like.

There is well known an oscillation counting timer with a multiple time range which includes a pulse generator or oscillator, a frequency divider for receiving a pulse train generated from the pulse generator, and a counter for counting outputs from the frequency divider, dividing factors of the frequency divider being selected for a plurality of time ranges. Such a conventional timer has an operation panel marked with a plurality of time scales in accordance with the respective dividing factors, but has the disadvantages that if a great number of time ranges are designated to be performed, the design of the operation panel is complicated with many different time scale and not practical in use.

It is, therefore, a primary object of this invention to provide an electronic timer with a multiple time range in which a time scale on an operation panel is used in common for a plurality of time scales.

It is a further object of this invention to provide an electronic timer having a plurality of time ranges which can be externally selected with ease.

Other objects and advantages of this invention will be apparent upon reference to the following description in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of an electronic timer as a preferred embodiment of this invention;

FIG. 2 is a block diagram of a frequency divider employed in the timer of FIG. 1;

FIG. 3 is a first elevation assembled view of the timer of FIG. 1;

FIG. 4 is a plan view showing a time scale plate mounted on the timer of FIG. 3;

FIGS. 5 and 6 are perspective partial views showing the timers of FIG. 1, time ranges of which are preset by a pair of key switches and a pair of rotary switches; and

FIG. 7 is a detailed block diagram showing a multiplexer which is employed in the frequency divider of FIG. 2.

Referring, now, to FIG. 1, there is shown an oscillation counting timer as a preferred embodiment of this invention, which includes an oscillator 1 for developing outputs or a pulse train, a frequency divider 2 for dividing the frequency of the pulse train, a counter 3 which on counting a predetermined number of outputs of the divider 2 generates an output, an output circuit 4 which in response to the output from the counter 3 switches a load (not shown) connected thereto, a reset circuit 5, and a pair of time range setting switches 90 and 91 for selecting a couple of dividing factors of the divider 2. In FIG. 2 there is illustrated in detail the frequency divider 2 having an input terminal 6 connected to the oscillator 1 and an output terminal 7 connected to the counter 3. The frequency divider 2 consists of dividing circuits 12, 13 and 14 with the respective dividing factors 1/2, 1/5 and 1/2, a multiplexer 15 for selecting one of signals divided by the factors 1/1, 1/2, 1/10 and 1/20 in accordance with a logic input applied to input terminals 8 and 9, dividing circuits 16, 17 and 18 with the respective dividing factors 1/60, 1/60 and 1/24, and a multiplexer 19 for selecting one of signals divided by the factors 1/1, 1/60, 1/(60.times.60) and 1/(60.times.60.times.24) in accordance with a logic input applied to input terminals 10 and 11. In FIG. 7 the multiplexer 15 is exemplarily illustrated in detail, which includes AND-gates 51 to 54, an OR-gates 55, and inverters 56 and 57. If both input terminals 15f and 15g are at low levels, a signal at terminal 15a appears at output terminal 15e. If the terminals 15f and 15g are at low and high levels, respectively, a signal at terminal 15b appears at the terminal 15e. Thus, by applying a high or low signal to the input terminals 15f and 15g, one of input signals at the terminals 15a to 15d is selected to appear at the terminal 15e. The multiplexer 19 employs the same circuit as that of FIG. 7, and by applying a high or low signal to input terminals 10 and 11, one of signals at terminals 19a to 19d is selected to appear at terminal 7. The outputs from the oscillator 1 are applied to the respective terminals 15a, 15b, 15c and 15d at the dividing factors of 1/1, 1/2, 1/(2.times.5) and 1/(2.times.5.times.2), so that in accordance with the logic signals at the terminals 8 and 9, the multiplexer 15 selects a multiplying factor of a time range of the timer. The outputs from the multiplexer 15 are applied to the respective terminals 19a, 19b, 19c and 19d at the dividing factors of 1/1, 1/60, 1/(60.times.60) and 1/(60.times.60.times.24), so that in accordance with the logic signals at the terminals 10 and 11, the multiplexer 19 selects a time unit of a time range of the timer. The time range setting switch 90 is coupled to the terminals 8 and 9 to select a multiplying factor, and the switch 91 is coupled to the terminals 10 and 11 to select a time unit.

Thus, the timer of FIG. 1 performs the sixteen time ranges as shown in the following table:

In Table 1, the numerals "8" and "9" in the first row and the numerals "10" and "11" in the first column represent terminals 8 and 9 and terminals 10 and 11 of FIG. 2, and "L" and "H" represent a low level signal and a high level signal applied to the respective terminals 8 to 11. For instance, if the terminals 8 and 10 are supplied with a low level signal and the terminals 9 and 11 are supplied with a high level signal, the timer of FIG. 1 is set into the time range of 1 minute.

FIG. 3 is a front view of an operation panel of the timer, which includes a window 21 in case 21' for displaying a time multiplying factor ("5" in FIG. 3) and a window 22 for displaying a time unit ("sec" in FIG. 3). Thus, simply by changing the time multiplying factor and time unit in the windows 21 and 22, the time scale on the operation panel can be used in common for the sixteen time ranges in Table 1. In FIG. 4 there is shown a time scale plate 40 mounted on the panel in FIG. 3 which is used in common for the sixteen time ranges. Manually adjustable control 40' is used for setting the desired time.

In FIG. 5 there are shown the time range setting switches 90 and 91 which employ set keys 23 and 24. The set keys 23 and 24 are prepared for each multiplying factor and for each time unit listed in Table 1, and marked in the designations of the respective multiplying factors and time units. Moreover, they have distinct configurations of inserting portions (23a, 24a) to specify their multiplying factors or time units. If the set keys 23 and 24 are inserted into the windows 21 and 22, their inserting portions 23a and 24a actuate the respective switches 90 and 91 which are installed inside the windows 21 and 22 so that predetermined logic signals corresponding to the respective set keys 23 and 24 may be applied to the terminals 8 to 11.

Alternatively, the time range setting switches 90 and 91 may employ a pair of rotary switches (31) and rotary indication disks (30) fixed to rotary shafts (31a) of the rotary switches (31) as shown in FIG. 6. The rotary switches (31) are installed inside the windows 21 and 22. The rotary shafts (31a) of the switches are adapted to be rotated by an external driver 34 so as to select a multiplying factor and a time unit for indication in the windows 21 and 22 and for application of predetermined logic signals to the terminals 8 to 11.

Thus, the electronic timer according to this invention includes a pair of selecting circuits for selecting a time multiplying factor and a time unit, and a pair of switches upon changing an indication in a display window for changing a logic signal as a selecting signal applied to the selecting circuits, so that a single time scale plate on an operation panel of the timer can be used for a great number of time ranges in common.

It should be understood that the above description is merely illustrative of this invention and that many changes and modifications may be made by those skilled in the art without departing from the scope of the appended claims.