JPS5936041Y2 - timer circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a timer circuit that starts a load with a short delay and prevents re-energization of the load for a required period of time after the load is de-energized.

A timer circuit to which the present invention is applied is used, for example, in the control circuit of an air conditioner shown in FIG.

In Figure 1, 1 is an AC power supply, 2 is an operation switch, and 3
FM is a fan motor connected to the AC power supply 1 via the operation switch 2 and the wind speed selection switch 3, CM is a compressor motor energized via the operation switch 2 and the normally open relay switch X1, 4 is an overvoltage absorption element, 5 is a step-down transformer, 6 is a rectifier circuit, 7 is a constant voltage circuit, 8 is a bridge circuit 11 including a room temperature sensor 9 and a temperature setting resistor 10, and the voltage at the output terminals 12 and 13 of the bridge circuit 11. TC is a timer circuit to which the output voltage from the thermocircuit 8 is supplied via a protective resistor 15, and its output is supplied to the relay X for controlling the relay switch X1. Ru.

In order to prevent the starting current of the fan motor FM and the starting current of the compressor motor CM from overlapping when the operation switch 2 is turned on, the timer circuit TC is activated with a delay of, for example, about 3 seconds after the output of the thermo circuit 8 is output. Relay X must be activated so that fan motor FM and compressor motor CM are activated in sequence.

In addition, when the compressor motor CM is stopped due to opening of the operation switch 2 or the room temperature reaches the set temperature and the output of the thermo circuit 8 is stopped, the timer circuit TC is activated when the operation switch 2 is turned on again or when the room temperature reaches the set temperature. Even if the temperature rises and the output is supplied from the thermo circuit 8, it is necessary to prevent the compressor motor CM from restarting for about 3 minutes.

This is because the refrigerant circuit (not shown) of the air conditioner requires approximately 3 minutes to balance high and low pressures, so if the compressor motor CM is forced to start during this time, the compressor motor CM may have to be burnt out. This is because there is.

Incidentally, various types of timer circuits of this type have been devised in the past, including a discrete type using a PUT and one using two comparators.

In the former case, not only does it require a large mounting area for the printed circuit board, but it also requires a long assembly time.

In the latter case, there will be a total of three including one comparator used in the thermo circuit 8, and products with only one comparator, combinations of two comparators, and four comparators are commercially available as one element. Therefore, using a combination of four elements would be wasteful, and using two elements, one element and a combination of two elements, would leave a problem of installation space.

The present invention was made in view of the above-mentioned facts, and it is possible to obtain two types of desired time-limited outputs using one comparator, and to combine it with comparators used in other circuit configurations. Another object of the present invention is to provide a timer circuit that facilitates individual time settings, reduces the installation area, and is constructed at low cost.

FIG. 2 shows an embodiment of the present invention, and shows a specific example of a timer circuit TC used in the control circuit of the air conditioner shown in FIG.

11 and 12 are bus bars to which thermo output is supplied, and a resistor R1 and a first capacitor C1 are connected in series between the bus bars 11 and 12.
A charging circuit 16 made up of the above-mentioned resistors R2 and a reference voltage generation circuit 17 made up of series resistors R2 and R3 are connected.

Dl is a diode connected in parallel to resistor R1.

18 is a power supply terminal 18A, 18B first input terminal 181. It is a comparator equipped with a second input terminal 182 and an output terminal 183, and power supply terminals 18A and 18B are connected to buses 11 and 1, respectively.
2 and the first input terminal 181 is connected to the output point 161 of the charging circuit 16 via a resistor R4, and the second input terminal 1
82 is a resistor R5 with a large resistance value and a second capacitor C2
The output point 17 of the reference voltage generation circuit 17 via the parallel circuit of
Connected to 1.

Also, the output terminal 183 and the first input terminal 18 of the comparator 18
1, a feedback resistor RF with a relatively large resistance value is connected between the output terminal 183 and the second input terminal 182, a resistor R6 with a small resistance value and a diode D2 are connected in series between the first input terminal 181 and the second input terminal 182, A diode D3 is connected between the two input terminals 182.

Also, the output terminal 183 of the comparator 18 is connected to N via the resistor R7.
PN) is connected to the base of transistor 19, the emitter of transistor 19 is connected to bus 12, and the collector is connected to relay
are respectively connected to the bus bar 11 via.

Therefore, the thermo circuit 8 in Fig. 1 is now connected between the busbars 11 and 12.
The output voltage of capacitor CI is supplied.

Assuming that there is no residual charge on C2, the output terminal 183 of the comparator 18 will be at a low voltage and the transistor 19 will be in an off state.

First, charging of the first capacitor C1 starts via the resistor R1.

At this time, the output point 161 of the charging circuit 16 is connected to the capacitor C.
1, the voltage gradually increases to a voltage determined by the voltage division between the resistor R.1, the resistor R4, and the feedback resistor RF.

Note that the second capacitor C2 has no charging path and is not being charged.

Then, the voltage at the output point 161 exceeds the voltage at the output point 171 determined by the resistors R2 and R3 of the reference voltage generation circuit 17,
When the input voltage at the first input terminal 181 of the comparator 18 becomes higher than the input voltage at the second input terminal 182, the high voltage of the bus bar 11 appears at the output terminal 183 of the comparator 18, causing the transistor 19 to conduct.

As a result, relay X is energized and compressor motor CM, which is a load, is started.

In this embodiment, when a DC voltage is applied between the bus bars 11 and 12 from a state in which both the capacitors CI and C2 have no charge, the relay X is activated 3 seconds later.

When the output terminal 183 of the comparator 18 becomes a high voltage, a charging current flows through the output terminal 183 to the capacitor C2 via the diode D2 and the resistor R6, and also in the path of the output terminal 183, the feedback resistor RF, and the diode D3. Since the charging current flows through the capacitor C2, the resistance value of the resistor R6 is small, and the resistance value of the resistor R5 is much higher than that of the resistor R3, the second capacitor C2 is connected to the bus line 11 approximately.
The voltage is instantaneously charged to the polarity shown.

Further, a charging current also flows through the first capacitor C1 via the output terminal 183, the feedback resistor RF, and the resistor R4, and the charging voltage of the first capacitor C1 is further increased.

During this time, the input voltage of the first input terminal 1810 of the comparator 18 is always kept higher than the input voltage of the second input terminal 182 by the forward voltage drop of the diode D3, and even after the second capacitor C2 is charged, A current flows through the resistor R5 and the resistor R3, and the diode D3 remains on, so that the input voltage at the first input terminal 181 increases by the forward voltage drop of the diode D3 to the second input terminal 182.
The output terminal 18 of the comparator 18 is held higher than the input terminal of the comparator 18.
3 is maintained at a high voltage state, the second capacitor C2
The comparator 18 continues to operate stably even after charging is completed.

When the operation switch 2 is turned off or the room temperature reaches the set temperature and the output of the thermo circuit 8 disappears, the relay The diode D is connected through the protective resistor 15 and comparator 14 of the thermo circuit 8 in
Since the voltage equal to or more than the forward voltage drop of 3 is instantaneously discharged, the first input terminal 181 and the second input terminal 1 of the comparator 18
The voltage level of 82 is inverted and the output terminal 183 changes from high level to low level.

On the other hand, the second capacitor C2 gradually discharges through the high resistance R5, and the discharge is completed after about 3 minutes.

Therefore, before the second capacitor C2 finishes discharging, the bus 1
1 and 12, the first capacitor C1 is charged to a predetermined bias level determined by the resistors R1 and R4 and the feedback resistor RF, but the input voltage at the second input terminal 182 of the comparator 18 is the second capacitor C2
The output terminal 183 of the comparator 18 remains low since the residual voltage at the output point 171 is increased by a certain amount.

When the second capacitor C2 has finished discharging and the input voltage at the first input terminal 181 exceeds the input voltage at the second input terminal 182, the comparator 18 outputs a high voltage to the output terminal 183, causing the transistor 19 to conduct. to reenergize relay X.

In this embodiment, the first capacitor C1 is biased with a feedback resistor RF having a relatively large resistance value in order to obtain a timed output for 3 seconds from power supply to the buses 11 and 12 to activation of the relay X. Therefore, malfunctions due to noise in the comparator 18 are reduced, the bias level of the output point 161 is increased, the design of the reference voltage generation circuit 17 is facilitated, and a small capacitance and inexpensive capacitor C1 can be used.

Moreover, at the same time that the high voltage output is output from the comparator 18, the second capacitor C2 is instantaneously charged mainly through the resistor R6, which has a small resistance value, so that a discharge time of 3 minutes can be ensured. Therefore, it can sufficiently cope with frequent repeated operations of the operation switch 2.

In addition, the diode D2. Both D3 are the second capacitor C2
The diode D2 has the function of blocking the discharge current from flowing to other than the resistor R5, and the diode D2 connects the small resistor R6 to the first capacitor C.
It has the function of making it irrelevant to the bias level of 1.

As described above, the present invention provides a timer having a first timed output for starting the load with a short delay and a second timed output for preventing re-energization of the load for a required period of time after the load has been de-energized. Since the circuit is configured using one comparator, the installation area can be reduced, and it is highly flexible, as it can be combined with a single comparator of other circuit configurations to use a set of two elements. It becomes something.

Moreover, when the operation switch is turned off or the output of the thermo circuit disappears, the first capacitor is instantly discharged with a voltage equal to or more than the forward voltage drop of the diode, and the voltage between the first and second input terminals of the comparator is The high voltage level is reversed and the output terminal changes from high level to low level, and this low level is maintained until the second capacitor has finished discharging, so even if the output of the operation switch or thermo circuit is momentarily cut off, it is reliable. The timer output can be taken from the comparator.

In addition, individual time settings can be easily and reliably obtained without complicating the design, and the structure is extremely inexpensive, and excellent effects can be expected for control circuits of air conditioners.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing a control circuit of an air conditioner to which the present invention is applicable, and FIG. 2 is an electric circuit diagram showing an embodiment of the present invention. TC...Timer circuit, 16...Charging circuit, 17...Reference voltage generation circuit, 161.17
1...Output point, 18...Comparator, 18
1...First input terminal, 182...Second input terminal
Input terminal, 183...Output terminal, CI, C2・
... Capacitor, R1-R7 ... Resistor,
RF...Feedback resistor, D2. D3...Diode.

Claims (1)

[Scope of utility model registration request] a charging circuit consisting of a series resistor and a first capacitor to which an input voltage signal is supplied; a reference voltage generating circuit comprising a plurality of series resistors to which the input voltage signal is supplied; a comparator to which one input terminal is connected, and a second input terminal is connected to the output point of the reference voltage generation circuit via a parallel circuit of a resistor and a second capacitor, and the output terminal and the first input of the comparator. a feedback resistor connected between the terminals, a series circuit of a resistor and a diode connected between the output terminal and the second input terminal of the comparator, and a diode connected between the first and second input terminals. A timer circuit characterized in that the discharge time of the second capacitor is set longer than that of the first capacitor, and a timer output is taken out from the output terminal of the comparator.