JPS6146200A - Switch closure detector circuit - Google Patents

Abstract

PURPOSE:To accurately detect the closure of a switch by detecting the closure of a switch by a voltage applied to a transistor. CONSTITUTION:When a key switch 3 is closed, the voltage of an external terminal T3 becomes a voltage decided by the divided voltage of a charge lamp 4 and a leakage compensating resistor 151. Transistors 131a, 132 are turned ON by the voltage, and a current is supplied to a generating voltage controller 12 and a generation detector 19. When an engine starts so that the voltage at a terminal T5 becomes higher than a reference voltage Vref, the output of a comparator 191 becomes L, transistors 11, 182 become OFF, a charge lamp 4 is turned OFF, and the current flowed to a resistor 181 for compensating the leakage is interrupted.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a load (for example, a charge lamp of a power generator) that operates when a switch in the housing is turned on and a transistor is turned on. The present invention relates to a switch-on detection circuit that detects the switching-on of the switch based on a voltage applied to the transistor.

(Prior Art) Conventionally, when turning on a switch in the above case, a wiring branched separately from the switch is provided, and the turning on of the switch is detected by detecting the voltage applied to the wiring. but,
Since this would complicate the wiring, a device was developed that indirectly detects the turning on of a switch by detecting the voltage applied to the transistor as described above, and the applicant filed the application as Japanese Patent Application No. 58-215715. ing.

(Problem to be solved by the invention) However, with this, if the switch is clogged with dust, etc., and even a small leakage source flows, a considerable voltage will be generated across the transistor, so it may falsely detect that the switch is turned on. There was a problem that could be considered.

Therefore, in view of the above problems, it is an object of the present invention to provide a circuit for a switch-on faucet that can accurately detect switch-on even if there is a leakage current. - (Example) Hereinafter, an example in which an example of the present invention is applied to a charge lamp circuit of a power generation device will be described.

In this case, a charge lamp, which is a load, is turned on when a key switch, which is a switch, is turned on and a transistor is turned on.In order to reduce the wiring, the voltage change applied to a transistor is used to turn on the key switch. is detected.

This will be explained below with reference to FIG.

5 is a charging generator for a vehicle, 1 is a control device (hereinafter referred to as a regulator) provided integrally with the charging generator for a vehicle, 2 is a battery, 3 is a key switch, 4 is a charge lamp, and 11 is a power that drives the charge lamp. 12 is a transistor, 12 is a power generation voltage control circuit, 13 is a voltage detection circuit forming a key switch ON determination means, 19 is a power generation detection circuit, 18 is a malfunction prevention circuit due to leakage current, lla is a level shift diode, 51 is a rotor coil, 52 53 is a stator coil, 53 is a rectifier, 121 is a current-carrying transistor for field current control, and 132 is a power switch transistor.

131a is a transistor for identifying a key switch official;
81 is a leakage current compensation resistor, 182 is a leakage compensation resistor cutoff transistor, T2 to T6 are external terminals of the regulator 1, and T2. T4: 'rs.

T6 is connected to the generator 5, and terminal T3 is connected to the military side, ie, to the charge lamp 4.

When the key switch 3 is not turned on, the external terminal T3 is in an oven (zero potential) state, and the transistor 131a
and 132 are OFF, and no current is supplied to the voltage control circuit 12 and the power generation detection circuit 19. Therefore, the current-carrying transistor 121 is OFF, and no excitation current flows.

However, the transistor 11 for driving the circuit lamp and the transistor 182 for cutting off the leakage compensation resistor are
is biased from the terminal T6 to which the output B+ of O is applied.
I'm doing N.

Next, when the key switch 3 is turned on, the potential of the external terminal T3 becomes a potential determined by the charge lamp 4, the leak compensation, and the voltage division of the common resistor 151 (the voltage division of the battery voltage).

This potential turns transistors 131a and 132 into
N, and current is supplied to the power generation voltage control circuit 12 and the power generation detection circuit 19 via the transistor 132.

Here, since the generator 5 is in a stopped state, the voltage at the terminal T5 is O. Therefore, since the reference voltage Vref of the comparator 191 of the power generation detection circuit 19 is set to a value larger than O, the output of the comparator 191 becomes Ht, and the transistor 11 and the 1 degree cutoff transistor 182 continue at 0.NL.

Then, the potential of the terminal T3 is the sum of the voltage drop (Vc-[) between the collector and emitter of the transistor 11 and the voltage drop (VF) of the level shift diode lla (Vc c (Trll) + VF (D i 11
a), but the VBE for turning on the transistor 131a is this VCE (Trll) + VF
(Dilla), transistors 131a and 132 continue to be ONL.

On the other hand, in the power generation control circuit 12, the battery voltage Va
is lower than the regulated voltage of regulator 1, Zener diode 12a breaks down and transistor 121
causes a field current to flow through the ONL rotor coil 51.

Then, when the engine (not shown) starts, the generator starts generating electricity, and the voltage at terminal T5 rises, causing the electricity generation detection circuit 1
9, higher than the reference voltage Vref of the comparator 191 (then the output of the comparator 191 becomes Lo,
Transistor 11 and transistor 182 are 0FFL
, the charge lamp 4 goes out, and the leak compensation resistor 181
The current flowing through is also cut off. As a result, the potential of the terminal T3 becomes the battery voltage.

Furthermore, in the power generation control circuit 12, switching control is performed on the energizing transistor 121 so as to keep the power generation voltage, that is, the voltage at the terminal T6 constant (adjusted voltage).

Here, when the key switch 43 is cut off, the potential of the terminal T3 becomes 0, so the transistors 131a and 132
is turned OFF, the current supply to the voltage control circuit 12 and the power generation detection circuit 19 is cut off, the regulator 1 is stopped, and the voltage at the terminal T5 is almost lowered, so the output of the comparator 191 becomes Hi, and the output from the L transistor 11 and Resistance cutoff transistor 182 is turned on.

As described above, a method is adopted in which the potential generated at the external terminal T3 is detected and current is supplied to the regulator voltage control circuit and the voltage detection circuit 19.

FIG. 2 shows the voltage characteristics generated at the external terminal T3. A is the characteristic when there is no leakage compensation resistor 181, and 2 is the sum of 'JCE of the l transistor 11 and VF of the level shift diode lla. This (2) has semiconductor characteristics, and even when a very small current flows into the R1 element 1-3, it rises suddenly as shown in the figure, and after that it hardly changes.

Now, when the key switch 3 is turned off, a leak may occur in the key switch 3 due to some reason, for example,
When a minute current (leakage current through foreign matter such as dust) of several tens of microamperes flows into the external terminal T3, the rise of the terminal voltage generated by this current causes the transistor 13 to
1a and 132 are ONL, key switch 3 is (OFF)
), the voltage detection circuit 13 will falsely detect it, and as mentioned above, the current-carrying transistor 121 will be ON, and the field current (about 4A) will continue to flow, and if this state continues, the battery will run out. I'll wake you up.

Generally, a bypass circuit using a resistor or the like is usually provided as a measure to prevent malfunctions due to such leakage current. The voltage and current characteristics of a circuit in which this resistor is inserted are improved as shown in FIG. 2B.

However, as in the present invention, the terminal T where leakage occurs
! If the potential of 3 fluctuates over a wide range from OV (when key switch 3 is OFF), 2 V (key switch 3 ON, no power generation), to 14VC (key switch 3 ON, power generation) under normal usage conditions, connect the leak compensation resistor 181 to the terminal. T3
If you connect directly between the
There are problems with the power consumption of the resistor 181 during power generation (when the terminal T3 voltage is 14 V), or there are problems such as the charge lamp 4 turning light red even though the transistor 11 is OFF, and the resistance value of the resistor 181 cannot be made small, making it ineffective. Compensation ability cannot be obtained.

Therefore, in the present invention, a transistor 182 is added in series to cut off the leakage compensation resistor 181 during power generation when the leakage compensation resistor 181 is not required (--when the transistor LL is OFF).

Next, a second example will be described.　　　・　.

In this TS2 embodiment, a part of FIG. 1 is modified as shown in FIG. , when the key switch 3 is OFF, the transistor 11 is turned OFF and only the transistor 182 is turned ON.In this way, the transistor 11 is connected to the bias resistor (see Fig. 1) leading to the terminal T6 to which the battery voltage is always applied. 11b), there is an advantage that there is no need to flow unnecessary bias current and power loss is small.

(Effects of the Invention) In the present invention, when the transistor (11) is turned on while the switch (3) is turned on, the load (4) is activated.

Then, turn on the switch (3) using the transistor (11).
It is detected by the voltage applied to the wiring gate and is reduced. (Such circuits may be required in various electronic and electronic circuits for vehicles.) 6 In this case, depending on the characteristics of the transistor, a small current (leakage current) through the switch (3) causes the transistor (11 ) rises (there is an injection amount, but when switch (3) is OFF, that is, when there is a possibility that this operation will occur due to leakage current,
Since a resistor with a low resistance value can be connected in parallel with 11), there is no possibility of erroneously detecting that the switch is ON due to leakage current.

As described above, the present invention has the advantage that switch-on detection can be performed accurately and a highly reliable device can be achieved.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a vehicle power generator showing an embodiment of the circuit of the present invention, FIG. 2 is an external terminal voltage characteristic diagram for explaining the operation of the above embodiment, and FIG. FIG. 2 is a partial electrical circuit diagram showing a second embodiment. 11...Transistor, 4...Charge lamp serving as a load, T3...External terminal forming a connection point, 181...
-Resistance, 182...Switch means.

Claims (1)

[Claims] It has a series circuit of a load (4) supplied with load current via a transistor (11) and a switch (3), and a connection point (T3) between the load (4) and the transistor (11).
In the circuit including a voltage detection circuit (13) that detects a voltage of and switch means (1
82) is connected in series, and the OF of the switch (3) is connected.
A switch-on detection circuit characterized in that the switch means (182) is turned on at F time.