JPH0582158B2 - - Google Patents

Description

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

(Prior Art) Conventionally, the turning-on of a switch in the above case is detected by providing a record separately branched from the switch and detecting the voltage applied to the wiring. However, this would complicate the wiring, so as mentioned above, a device was developed that indirectly detects the turning-on of a switch by detecting the voltage applied to the transistor, and the applicant filed a patent application in 1983-
It has been filed as No. 215715.

(Problem that the invention aims to solve) However, with this, if the switch is clogged with dust, etc., and even if a slight leakage current flows, a considerable voltage will be generated across the transistor, so it may falsely detect that the switch has been turned on. There was a problem that I could think of.

Therefore, in view of the above problems, it is an object of the present invention to provide a switch-on detection circuit that can accurately detect switch-on even if there is a leakage current.

(Embodiment) An example in which an embodiment of the present invention is applied to a charge lamp circuit of a power generation device will be described below.

In this system, 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, but in order to reduce the number of wiring, changes in the voltage applied to the transistor are used.
This detects the activation of the aforementioned key switch.

The first explanation will be given below.

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; 11 is a power transistor that drives the charge lamp; is the power generation voltage control circuit,
Reference numeral 13 indicates a voltage detection circuit serving as means for determining whether the key switch is turned on, 19 indicates a power generation detection circuit, 18 indicates a circuit for preventing malfunction due to leakage current, 11a indicates a level shift diode, 51 indicates a rotor coil, 52 indicates a stator coil, 53 indicates a rectifier, and 121 indicates a rectifier. A current-carrying transistor 132 is a power switch transistor for field current control.

131a is a transistor for determining whether the key switch is on, 181 is a leak current compensation resistor, 182 is a transistor for cutting off the leak compensation resistor, T ₂ to _{T 6} are external terminals of the regulator 1, and T ₂ , T ₄ , T ₅ , and T ₆ are for power generation. The terminal T ₃ is connected to the vehicle side, that is, the charge lamp 4.

The battery 2, key switch 3, and charge lamp 4 constitute a first series circuit, and the leak current compensation resistor 181 and the leak compensation resistor cutoff transistor 1
82 constitutes a second series circuit, and these first and second series circuits are connected in series via terminal _T3 .

When the key switch 3 is not turned on, the external terminal _T3 is open (zero potential), the transistors 131a and 132 are turned 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
It is OFF and no excitation current flows. but,
The charge lamp driving transistor 11 and the leakage compensation resistor cutoff transistor 182 are biased from the terminal _T6 to which the output B+ of the rectifier 53 is applied, and are turned on.

Next, when key switch 3 is turned on, the external terminal
The potential of T ₃ is determined by the charge lamp 4 and the partial voltage of the leakage compensation resistor 181 (partial voltage of the battery voltage).

This potential causes transistors 131a and 1
32 is turned on, 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 terminal
The voltage at T ₅ is zero. Therefore, the power generation detection circuit 1
Since the reference voltage Vref of comparator 191 of 9 is set to a value larger than 0, comparator 191
The output of the transistor 91 becomes Hi, and the transistor 11 and the resistance cutoff transistor 182 continue to be turned on.
Then, the potential of terminal T ₃ is equal to the collector-emitter voltage drop (V _CE ) of transistor 11.
and the voltage drop (V _F ) of the level shift diode 11a, that is, V _CE (Tr11) + VF (Di11
a), but the transistor 131a
V _BE for turning ON is this V _CE (Tr11) + V _F
(Di11a) Since it is set to a lower value, transistors 131a and 132 continue to be turned on.

On the other hand, in the power generation control circuit 12, since the battery voltage V _B is lower than the regulating voltage of the regulator 1, the Zener diode 12a does not shut down the breaker, and the transistor 121 is turned on, and the rotor coil 5
A field current is applied to 1.

Then, when the engine (not shown) starts, the generator starts generating electricity and the voltage at terminal T5 rises.
In the power generation detection circuit 19, when the voltage becomes higher than the reference voltage Vref of the comparator 191, the comparator 19
The output of the transistor 1 becomes L ₀ , the transistor 11 and the transistor 182 are turned off, the charge lamp 4 is turned off, and the current flowing through the leak compensation resistor 181 is also cut off. As a result, the potential at the terminal _T3 becomes the battery voltage.

Further, in the power generation control circuit 12, the power supply transistor 121 is controlled by switching so that the power generation voltage, that is, the voltage at the terminal _T6 is kept constant (adjusted voltage).

Here, when key switch 3 is cut off, the terminal
Since the potential of T ₃ becomes O, the transistor 131
a and 132 are turned OFF, and voltage control circuit 1
2 and the power generation detection circuit 19 are cut off, the regulator 1 is stopped, and the voltage at the terminal _T5 decreases, so the output of the comparator 191 becomes Hi, and the transistor 11 and the resistance cutoff transistor 182 are turned on. Become.

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 characteristics of the voltage generated at this external terminal _T3 . A is the characteristic when there is no leakage compensation resistor 181, _{and V2} is the sum of _VcE of the transistor 11 and _VF of the level shift diode 11a. This V ₂
has semiconductor characteristics and has extremely small terminals.
As shown in the figure, the current flowing into T ₃ causes a sudden rise, and after that, the characteristics hardly change.

Now, when the key switch 3 is turned OFF, a leak occurs in the key switch 3 due to some factor (for example, a leak current through foreign matter such as dust), and a minute current of about 100 + _μA flows into the external terminal T ₃ . Then, due to the rise of the terminal voltage generated by this current, transistors 131a and 1
32 is turned on, and the key switch 3 is turned on (despite being OFF), the voltage detection circuit 13 will falsely detect the current-carrying transistor 121 as described above.
becomes 0N, the field current (about 4A) is allowed to flow, and if this state continues, the battery will rise.

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 where leakage occurs
If the potential of T ₃ fluctuates over a wide range from 0V (key switch 3 OFF), 2V (key switch 3 ON, no power generation), to 14V (key switch 3 ON, power generation) under normal use, leak compensation resistor 181
If you connect directly between the terminal T ₃ and the ground, there will be a problem of power consumption of the resistor 181 when the key switch 3 is ON (when the voltage at the terminal T ₃ is 14 V), or
There was a problem such as the charge lamp 4 dimming even though the transistor 11 was OFF, so the resistor 181
resistance value cannot be made small, and effective compensation ability cannot be obtained.

Therefore, in the present invention, the leak compensation resistor 181
During power generation when there is no need for (transistor 11, 0FF
(time), a transistor 182 is added in series to cut off the leakage compensation resistor 181.

Next, a second example will be described.

This second embodiment is a modification of a part of FIG. 1 as shown in FIG.
When the key switch 3 is turned off, the transistor 11 is turned off and only the transistor 182 is turned on. In this way, the transistor 11 does not have a bias resistor (11b in Figure 1) connected to the terminal _T6 to which the battery voltage is constantly applied, so unnecessary bias current does not have to flow, and power loss is reduced. There is an advantage.

(Effects of the Invention) As described above, according to the present invention, since the turning on of the switch 3 is detected by the voltage applied to the transistor 11 for driving the load 4, the wiring for driving the load is It is possible to share the wiring for switch-on detection with switch 3, thereby reducing the number of wiring (such circuits are sometimes required in various electronic circuits for vehicles). When opened, this switch 3
Even if a small leakage current occurs through the contact part of the switch, the voltage used for switch-on detection is suppressed by the resistor 181 to a value smaller than the predetermined value that is determined as a switch-on, so it will not be mistaken as a switch-on. Detectable and preventable.

[Brief explanation of the drawing]

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. 113...Transistor, 4...Charge lamp serving as a load, _T3 ...External terminal forming a connection point,
181...Resistance, 182...Switch means.

Claims (1)

[Claims] 1 Battery 2, Switch 3, Load 4, Transistor 11, Connection terminal T3, Leak current compensation resistor 1
81, leak compensation resistance cutoff switch means 182
and a voltage detection circuit 13, the battery 2 supplies current to the load 4, the switch 3 connects the battery 2 and the load 4 when turned on, and the switch 3 connects the battery 2 and the load 4 when turned on. The transistor 11 drives the load 4 when the switch 3 is turned on, and the connection terminal T3 is connected to the switch 3.
The leak current compensation resistor 181 is a terminal to which the current from the battery 2 is supplied through the
When a leakage current occurs through the contact portion of the switch 3 when the switch 3 is opened, the voltage of the connection terminal T3 is suppressed to a predetermined value or less, and the leakage compensation resistance cutoff switch means 18
2 controls energization or cutoff of the leakage current compensation resistor 181, and is maintained in the ON state when the switch 3 is opened;
The voltage detection circuit 13 detects when the voltage of the connection terminal T3 is larger than the predetermined value as the time when the switch 3 is turned on, and the battery 2, The switch 3, the load 4
are connected in series to constitute a first series circuit; the leak current compensation resistor 181 and the leak compensation resistance cutoff switch means 182 are connected in series to constitute a second series circuit; The two series circuits are connected in series through the connection point T3, and the transistor 11 has its emitter.
A switch-on detection circuit in which the connection terminal T3 is grounded via a collector.