KR20040007881A - Delay integrated circuit for fuel gauge warning display of automobile - Google Patents

Abstract

PURPOSE: A warning lamp delaying integrated circuit of a fuel sensing device for a vehicle is provided to accurately set an electric charging time, in particular, a delay time of a remaining fuel detecting time and a lamp control time by constantly setting initial voltage of a capacitor and to stably keep a lighting-up state of the lamp by lighting the lamp with constant current even if source voltage is changed and improve reliability. CONSTITUTION: A warning lamp delaying integrated circuit of a fuel sensing device for a vehicle is composed of a switch(SW) switched on or off to the remaining amount of fuel; a lighting control unit(10) for receiving source voltage to the switching state of the switch, delaying a lamp(LAMP) for a predetermined time, and outputting a lamp driving control signal; and an integrated circuit unit(20) for driving the lamp for receiving the lamp driving control signal of the lighting control unit and driving the lamp by constant current without regard to source voltage.

Description

Automotive fuel detector warning light delay integrated circuit {DELAY INTEGRATED CIRCUIT FOR FUEL GAUGE WARNING DISPLAY OF AUTOMOBILE}

The present invention relates to a technology for detecting and displaying a warning when a fuel level of a vehicle reaches a replenishment level. Particularly, when the fuel level falls below a certain level, the warning display lamp is stably maintained regardless of the shaking of the vehicle and the change of temperature. An automobile fuel sensor warning light delay integrated circuit is adapted to be lit.

1 is a conventional vehicle fuel sensor warning light delay integrated circuit diagram, and as shown therein, a fuel residual amount detection switch (SW) switched according to the fuel residual amount of a fuel tank; A lighting controller (1) which charges an input voltage in a state where the fuel residual amount detection switch (SW) is closed and supplies the charged voltage as a driving control voltage; The lamp driver 2 is configured to receive a driving control voltage of the lighting controller 1 to drive a lamp LAMP.

Hereinafter, the operation and configuration of the conventional automotive fuel sensor warning light delay integrated circuit as described above will be described in more detail.

First, while the fuel residual amount of the fuel tank of the vehicle is maintained for a predetermined value or more, the fuel residual amount detection switch SW is maintained in an open state.

In this state, there is no voltage supplied to the lighting control unit 1, and thus the lamp LAMP remains off. This means that the fuel level indicator shown on the front panel of the driver's seat does not turn on, so the driver has a certain amount of fuel. You will know.

When the vehicle continues to run in this state and consumes fuel, and the remaining fuel amount is reduced to a predetermined value or less, the fuel residual amount detection switch SW is closed.

In such a state that the fuel residual amount detection switch SW is closed, the voltage of the power supply voltage V1 is supplied to the lighting controller 1. In this case, the lighting controller 1 includes an indicator 3 and a resistance card 4 that is a variable resistor, and is configured such that a voltage applied through the resistor RA is charged in the capacitor CA.

Thus, the voltage by the power supply voltage V1 is charged to the capacitor CA, and the charged voltage is output as a drive control voltage.

Then, the lamp driving unit 2 applied with the driving control voltage drives the lamp LAMP so that the lamp LAMP is turned on.

In this case, the lamp driver 2 is formed of a Darlington-connected transistor (Q1-Q3), in order to drive the transistor (Q1 ~ Q3), the charging voltage of the capacitor (CA) must be above a certain voltage, After a predetermined time has elapsed after the fuel residual amount detection switch SW is closed, the charging voltage becomes a voltage suitable for driving the transistors Q1 to Q3.

The time at which the charging voltage reaches a voltage value capable of driving the transistors Q1 to Q3 depends on the time constants of the capacitor CA and the resistor RA, and usually takes 60 to 120 seconds.

That is, after the fuel residual amount detection switch SW is closed, the lamp LAMP is turned on after a delay of about 60 to 120 seconds and the fuel level warning light is turned on. The driver can recognize the fact and refuel.

In addition, since a predetermined delay time is required for charging as described above, even when the fuel residual amount detection switch SW is momentarily turned on by the shaking of the vehicle in a state where the residual fuel level is a predetermined value or more, the warning display is thereby performed. The lamp (LAMP) does not light up. Therefore, in such a case, the driver does not feel unnecessary anxiety.

However, in the conventional technology as described above, when the power supply voltage V1 is changed, the time for charging the capacitor CA is changed so that accurate detection of fuel is not performed.

Unlike the conventional embodiment, there is an example of using a thermistor. Thus, the thermistor type fuel shortage warning light device is installed near the bottom of the fuel tank, and connects the thermistor and the warning light in series.

In such a configuration, when there is much fuel, that is, when the thermistor is immersed in the fuel, the temperature of the thermistor is kept relatively low, and the resistance value becomes large.

As the resistance of the thermistor increases, the current cannot flow and the lamp remains off.

If the state is maintained while the fuel is consumed and the thermistor is exposed to the air in the fuel tank, the thermistor will not be able to dissipate its heat and the temperature will rise.

As a result, the resistance of the thermistor becomes small, current flows to the lamp, and the lamp is turned on.

However, the method of using the thermistor in this way is that when the liquid level of the fuel vibrates severely, that is, when the vehicle is traveling on an unpaved road or uneven road, the thermistor is immersed in fuel and exposed to the air, The process may be repeated, and the lamp will continue to flash, causing the operator to be confused.

In addition, since the resistance value of the thermistor changes according to the ambient temperature, the thermistor has a problem that accurate fuel detection cannot be performed due to the temperature change.

However, such a conventional fuel gauge warning display circuit does not accurately detect the remaining fuel amount according to the fluctuation of the power supply voltage, and the fuel gauge warning display device using a thermistor changes the characteristics of fuel detection according to the ambient temperature. There was a problem.

In view of the above problems, the present invention aims to provide a delayed integrated circuit for a vehicle fuel sensing device warning light insensitive to a change in temperature by turning on or off a lamp at a certain time regardless of a change in power supply voltage.

1 is a conventional automobile fuel sensor warning light delay integrated circuit diagram.

Figure 2 is a vehicle integrated fuel alarm warning light delay integrated circuit diagram of the present invention.

3 is a detailed circuit diagram of FIG.

* Description of the symbols for the main parts of the drawings *

10: lighting control unit 20: lamp driving integrated circuit unit

21: current inlet breaker 22: Schmitt trigger unit

23: constant current source 24: constant current circuit

25: Drive part

The above object is a switch that is switched according to the remaining amount of fuel; A lighting control unit which receives a power supply voltage according to a switching state of the switch and outputs a lamp driving control signal with a predetermined time delay; This is achieved by applying a lamp driving control signal of the lighting control unit to a lamp driving integrated circuit unit for driving a lamp regardless of a change in power supply voltage using a constant current, and the present invention will be described in detail with reference to the accompanying drawings. The explanation is as follows.

FIG. 2 is a circuit diagram showing a delayed integrated circuit of a warning light for a vehicle fuel detector according to the present invention, and FIG. 3 is a detailed circuit diagram thereof, and a fuel residual amount detection switch SW switched as shown in FIG. A lighting control unit 10 that charges the power supply voltage V1 by applying a power supply voltage V1 in a state where the fuel residual amount detection switch SW is closed and delaying the predetermined time, and outputs the charged voltage as a drive control voltage; ; The lamp driving integrated circuit unit 20 receives a driving control voltage of the lighting control unit 10 and drives the lamp LAMP by using a constant current.

The lamp driving integrated circuit unit 20 supports the increase of the charging voltage by blocking the inflow of current when the power supply voltage V1 of the lighting control unit 10 is charged, and when the charging voltage is higher than a predetermined voltage, the power supply voltage. A current inflow interrupting unit 21 for outputting V1; A Schmitt trigger unit 22 for operating the constant current source 23 by receiving the power supply voltage V1 of the current inflow interrupting unit 21; A constant current circuit unit 24 which receives and outputs a current of the constant current source 23 according to the operation of the Schmitt trigger unit 22; It consists of a drive unit 25 for driving the lamp (LAMP) by the output current of the constant current circuit section 24.

Hereinafter, the configuration and operation of the present invention as described above in more detail.

First, when the residual amount of fuel is above a certain value, the fuel residual amount detection switch SW is open and the lamp LAMP is turned off.

When the vehicle is driven while the lamp LAMP is turned off, the fuel remaining amount detecting switch SW is closed when fuel is consumed and the remaining amount is reduced to a predetermined value or less.

When the fuel remaining amount detection switch SW is closed, the power supply voltage V1 is applied to the lighting controller 10.

The lighting controller 10 includes a resistor R1 and diodes D1 and D2 connected in series between the power supply voltage V1 and the ground when the fuel residual amount detection switch SW is closed, and the power supply voltage. A resistor (R2) and a capacitor (C1) connected in series between V1 and ground, and a diode connecting a contact between the resistor (R1) and the diode (D1) and a contact between the resistor (R2) and the capacitor (C1) ( D3).

When the power supply voltage V1 is applied to the lighting control unit 10 having the above configuration, the voltage value divided by the resistors R1 and R2 is charged in the capacitor C1.

At this time, the voltage charged in the capacitor C1 is initially charged with a lower voltage than the voltage for driving the lamp, and the charging voltage increases as time passes.

That is, even when it is detected that the remaining amount of fuel is smaller than the reference, the lamp is turned on after a predetermined time has elapsed.

In addition, the initial charge voltage of the capacitor (C1) is always the same value by the diode (D1 ~ D3).

This is because the initial voltage applied to the capacitor C1 is always kept constant, and when the initial charge voltage value of the capacitor C1 is changed due to a change in the power supply voltage V1 value, the delay time by the capacitor C1 is changed. This is to prevent accurate detection.

Then, the current inflow interrupting unit 21 is operated by the voltage charged in the capacitor C1.

The current inflow blocking unit 21 is composed of two transistors Q4 and Q5 having a Darlington configuration.

Due to the characteristic of the Darlington configuration, the charging of the capacitor C1 is prevented from flowing in the initial stage of the charging of the capacitor C1 to increase the charging voltage of the capacitor C1.

When the charging voltage of the capacitor C1 of the lighting controller 10 is sufficiently large, the two transistors Q4 and Q5 of the Darlington configuration are turned on to flow a current by the power supply voltage V1.

The current at this time is applied to the Schmitt trigger unit 22, the Schmitt trigger unit 22 drives the constant current source 23 and the constant current circuit unit 24 to be described later.

A detailed configuration of the Schmitt trigger unit 22 may include a resistor R4 for converting the current output from the current inlet breaker 21 into a voltage and applying a voltage determined by the resistor R4 to the base. The emitter is connected to one output path of the constant current source 23 through a resistor, and the collector is connected to the transistor Q6, which is grounded through the resistor R6, and the base is connected to the collector of the transistor Q6. The emitter is connected to the emitter at Q6, the collector is grounded via a resistor R7, and the base is connected to the collector of the transistor Q7, and the emitter is connected to the constant current circuit section 24. It is connected to one end of and the emitter consists of a transistor Q8 grounded via a resistor R8.

When the current by the power supply voltage V1 is applied, the Schmitt trigger unit 22 having the above-described configuration turns off the transistor Q6 to turn on the transistor Q7. Accordingly, the constant current source 23 Drive.

When the transistor Q7 is turned on, the transistor Q8 is also turned on, thereby driving the constant current circuit unit 24.

Both the constant current source 23 and the constant current circuit unit 24 have a structure of a current mirror, and the constant current circuit unit 24 serves to transfer the constant current generated from the constant current source 23 to the next stage without loss.

The constant current source 23 includes resistors R10 and R11, and the resistors R10 and R11 monitor the ratio of the supply voltage to determine the trigger resistance of the transistor Q6.

Next, the driving unit 25 receiving the constant current of the constant current circuit unit 24 turns on the lamp LAMP.

In the configuration of the driver 25, a constant current is applied to the base, and the emitter is grounded through the resistor R15, and the lamp LAMP and the power supply voltage are generated according to the emitter voltage of the transistor Q13. And a transistor Q14 that turns on the lamp LAMP by forming a loop of V1).

When the constant current is applied, transistor Q13 is turned on and transistor Q14 is also turned on.

At this time, even when the value of the power supply voltage V1 is changed due to an external unexpected change, the lamp LAMP can be stably lit by the constant current.

As described above, the present invention uses a resistor and a capacitor to drive the lamp after a predetermined time has elapsed from the time when the fuel residual amount is detected, thereby preventing the fuel residual amount from being incorrectly detected by the vibration of the vehicle and transmitting it to the driver. In the configuration, it is possible to control the initial voltage of the capacitor constantly, so as to set an accurate delay time.

In addition, the use of a constant current source makes it possible to stably turn on the lamp even in a situation where the power supply voltage is changed.

As described above, according to the present invention, in a circuit for controlling a lamp after a predetermined time has elapsed from the time of detecting the remaining fuel level by using the charging time of the capacitor, the initial voltage of the capacitor is set constant to detect the correct charging time, that is, the remaining fuel amount. There is an effect that can accurately set the delay time between the time point and the ramp control point.

In addition, by turning on the lamp using a constant current, even when the power supply voltage changes, it is possible to stably maintain the lighting state of the lamp, thereby improving the reliability,

By implementing the above circuits into integrated circuits to form a single chip, it is possible to reduce manufacturing costs and to accurately detect fuel residual amount regardless of temperature change.

Claims (5)

A switch switched according to the remaining amount of fuel; A lighting control unit which receives a power supply voltage according to a switching state of the switch and outputs a lamp driving control signal with a predetermined time delay; And a lamp driving integrated circuit unit configured to receive a lamp driving control signal of the lighting control unit to drive a lamp regardless of a change in power supply voltage using a constant current. The display device of claim 1, wherein the lighting controller comprises: first resistors, first and second diodes connected in series between a power supply voltage and a ground when the switch is closed; A second resistor and a capacitor connected in series between the power supply voltage and ground; And a third diode configured to connect the contacts of the first resistor and the first diode and the contacts of the second resistor and the capacitor. The lamp driving integrated circuit of claim 1, wherein the lamp driving integrated circuit blocks an inflow of current while the power supply voltage of the lighting controller is charged to support an increase in the charge voltage, and outputs a power supply voltage when the charge voltage is higher than a predetermined voltage. A current inflow interrupting unit; A Schmitt trigger unit configured to operate by receiving a power supply voltage of the current inlet breaker, and detect a change in the power supply voltage to control a trigger voltage; A constant current source for generating a constant current according to the operation of the Schmitt trigger unit; A constant current circuit unit configured to receive and output a constant current of the constant current source according to the operation of the Schmitt trigger unit; And a driving unit for lighting a lamp by the constant current of the constant current circuit unit. [4] The warning light delay integrated circuit of claim 3, wherein the current inflow interrupting unit is composed of two transistors connected to Darlington. 4. The first transistor of claim 3, wherein the Schmitt trigger unit receives an output voltage of the current inlet breaker to the base, the emitter is connected to one output path of the constant current source through a resistor, and the collector is grounded through the first resistor. The base is connected to the collector of the first transistor, the emitter is connected to the emitter of the first transistor, the collector is grounded through a second resistor, and the base is connected to the collector of the second transistor. And a third transistor having an emitter connected to one end of the constant current circuit portion and the emitter grounded through a third resistor.