Electronic timer

An electronic timer having two electromagnetic relays is disclosed. The two electromagnetic relays are mounted on an insulating base plate. The electronic timer further comprises a delay circuit. At least one of the two electromagnetic relays is connected to an external power supply through the delay circuit. These two electromagnetic relays may be connected in such a manner that when connected with an external power supply, one of them is operated instantaneously while the other is actuated after a delay time, or in such a manner that both of them are simultaneously operated after a predetermined delay time, or in such a manner that they are operated after different delay times.

BACKGROUND OF THE INVENTION 
This invention relates to an electronic timer, or more in particular to an 
electronic timer comprising a delay circuit and two electromagnetic relays 
mounted on a common base plate carrying output terminals of the relays and 
a couple of power supply terminals. 
In conventional electronic timers, the timer proper and the relays are 
constructed separately and used by combining them, resulting in a large 
space occupied by them. Even those conventional timers in which the timer 
and the relays are incorporated in a single construction have the 
disadvantages of complex structure and bulkiness. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a compact electronic timer 
with a simple construction having no shortcomings as mentioned above. 
According to the present invention, there is provided an electronic timer 
comprising two electromagnetic relays, an insulating base plate on which 
the electromagnetic relays are mounted, and a delay circuit. At least one 
of the two electromagnetic relays is connected to an external power supply 
through the delay circuit. These two electromagnetic relays may be 
connected in such a manner that when connected with an external power 
supply, one of them is actuated instantaneously and the other after a 
timing, or in such a manner that both of them are simultaneously actuated 
after a predetermined delay time, or in such a manner that they are 
actuated after different delay times.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings, two single-pole electromagnetic relays 12 and 14 
are arranged in the same orientation and secured in spaced relation with 
each other on an insulating base 10. The base 10 is provided on the 
underside thereof with two sets of output terminals a.sub.1, b.sub.1, 
c.sub.1 ; and a.sub.2, b.sub.2, c.sub.2 for the relays 12 and 14 
respectively, and power terminals 16 and 18 connected to an external power 
supply. The relays 12 and 14 have exciting coils 20 and 22 respectively. 
Each of the relays 12 and 14 also includes two fixed contacts and a 
contact movably supported between the two fixed contacts. A movable 
contactor for carrying the movable contact of the relay 12 is designated 
by reference numeral 24, and that for carrying the movable contact of the 
relay 14 by numeral 26. The two fixed contacts of the relay 12 are 
connected to terminals a.sub.1 and b.sub.1 respectively, while the movable 
contact thereof is connected to the terminal c.sub.1. The two fixed 
contacts of the relay 14, on the other hand, are connected to terminals 
a.sub.2 and b.sub.2 respectively while the movable contact thereof to the 
terminal c.sub.2. 
All or substantially all electrical/electronic parts 30 constituting the 
delay circuit 28 are mounted on a printed base 31 which is securely 
erected on the base 10 on the side opposite to the contact means of the 
two relays 12 and 14 with respect to the respective exciting coils 20 and 
22. Among the electronic parts, comparatively large parts such as 
capacitors 34 are located in the space available between the relays 12 and 
14. 
Reference numeral 36 shows a timing-regulating variable resistor which is 
fixed on an upper casing 38, so that the timing may be regulated by 
turning a knob positioned on the upper surface of the upper casing 38. 
The upper casing 38 is stacked on an outer casing 42 of the base 10. The 
upper casing 38 is made of opaque material, while the outer casing 42 is 
preferably made of transparent material so that the operation of the 
contacts of the relays 12 and 14 inside may be observed from outside of 
the casing 42. No observation is required, however, from outside the walls 
on three sides of the outer casing 42 facing the coils 20 and 22 and the 
printed base 32 and hence these three walls may be appropriately provided 
with serration 44 to make the inside parts in that section substantially 
invisible in the view point of design. 
In the above-mentioned construction according to the present invention, as 
shown in FIG. 5A, the ends of the exciting coil 20 of the relay 12 may be 
directly connected to the power supply terminals 16 and 18 may be 
connected, while the ends of the exciting coil 22 of the relay 14 are 
connected to the same power supply terminals 16 and 18 through the delay 
circuit 28, so that the output terminals a.sub.1, b.sub.1 and c.sub.1 for 
the relay 12 act for instantaneous operating contacts and the output 
terminals a.sub.2, b.sub.2 and c.sub.2 for the relay 14 act for timed 
operating contacts. 
Alternatively, the power supply terminals 16 and 18 may be connected, as 
shown in FIG. 5B, across a parallel circuit of the exciting coils 20 and 
22 of the respective relays 12 and 14 through the delay circuit 28, so 
that both the output terminals a.sub.1, b.sub.1, c.sub.1 ; and a.sub.2, 
b.sub.2, c.sub.2 act for simultaneous timing contacts. 
Alternatively, the power supply terminals 16 and 18 may be connected, as 
shown in FIG. 5C, across two timing circuits, one comprising a combination 
of the exciting coil 20 of the relay 12 and a part of the delay circuit 
28, and the other comprising a combination of the exciting coil 22 of the 
relay 14 and another part of the delay circuit 28, so that the output 
terminals a.sub.1, b.sub.1, c.sub.1 and a.sub.2, b.sub.2, c.sub.2 function 
for two different timed operating contacts. 
If the output terminals a.sub.1, b.sub.1, c.sub.1 and a.sub.2, b.sub.2, 
c.sub.2 for the relays 12 and 14 are disposed so as to match selected two, 
preferably outside two, of three arrays of terminal insertion holes of an 
ordinary three-pole relay socket as shown in FIG. 3B, it is not necessary 
to prepare a special socket for the electronic timer according to the 
invention. By arranging the output terminals a.sub.1, b.sub.1, c.sub.1 and 
a.sub.2, b.sub.2, c.sub.2 to match the outside two of the three arrays of 
the terminal insertion holes of an ordinary three-pole relay socket, a 
space is available between the two juxtaposed relays 12 and 14 and may be 
occupied by comparatively large parts as described above. FIG. 3B shows an 
ordinary three-pole relay socket of the type previously mentioned, having 
three arrays of terminal insertion holes, the outer two arrays a.sub.1 ', 
b.sub.1 ', c.sub.1 ' and a.sub.2 ', b.sub.2 ', c.sub.2 ' of which 
correspond respectively to the output terminals a.sub.1, b.sub.1, c.sub.1 
and a.sub.2, b.sub.2, c.sub.2 of the timer as shown in FIG. 3A. Holes 16' 
and 18' are provided for receiving the power input terminals 16 and 18 of 
the timer. 
In the vicinity of the upper end of the printed base 32, light-emitting 
diode display units 46 for indicating the timer operating condition to the 
outside are preferably mounted. 
The embodiment shown in FIG. 6 is not of the pointer type as shown in FIG. 
1 but of the digital display type. In the embodiment under consideration, 
the timing is set by depressing the desired one of the push buttons 48 and 
displayed digitally through the windows 50. 
It will be understood from the foregoing description that according to the 
present invention meritorious effects are shown in that the two 
electromagnetic relays 12 and 14 and the delay circuit 28 are arranged on 
the same base and the output terminals a.sub.1, b.sub.1, c.sub.1 ; and 
a.sub.2, b.sub.2, c.sub.2 for the relays 12 and 14 and the power supply 
terminals 16 and 18 are led out, thereby easily providing an electronic 
timer with the above-mentioned construction of contacts, and eliminating 
the use of two independent units of a timer and relays on the one hand and 
saves the space on the other hand. Further, the lead-out terminals on the 
lower part of the timer may be arranged, as shown in FIG. 3, so as to be 
equivalent to those of a three-pole relay, without the central output 
terminal arrays, thus making it possible to use an ordinary three-pole 
relay socket. Furthermore, the resulting space available between the 
relays 12 and 14 may be used to accommodate comparatively large electronic 
parts.