JPH0727244Y2 - Lighting device drive circuit - Google Patents

Description

[Detailed Description of the Invention] Industrial field of application The lighting device drive circuit of the present invention relates to the ON / OFF of each switch,
The present invention relates to a lighting device drive circuit that lights up a lighting device when at least one switch among a plurality of switches connected so as to be discriminated to be turned off is turned on.

2. Description of the Related Art An automobile or the like is provided with an interior light that blinks in synchronization with a door in order to safely get on and off at night.

In addition, there is one provided with a warning light for a half door in order to prevent traveling in the half door state. Among them, there is a half-door warning light that can identify which door is a half-door.

As a drive circuit for driving such an interior light and a warning display device, a structure as shown in FIG. 2 has been conventionally used.

The door switches SW _{1 to} SW ₄ are attached to each door of the automobile and turned on and off as the doors are opened and closed.

The plurality of switches SW _{1 to} SW ₄ are connected to the NAND gate 2.
The output of the NAND gate 2 is output via the resistor R ₅ to the NPN transistor Q.
Connected to the base of ₀ . The voltage V is applied to the light bulb 1
_1G is applied and controlled by NPN transistor Q ₀ .

Further, CPU 5 of the input ports for the switch SW ₁ to SW ₄ is to determine the state of the switch SW ₁ to SW _4, and displays the determination result
It is connected to P ₁ to P _4. Further, the voltage V _DD is applied to the input ports P _{1 to} P ₄ of the CPU 5 via the resistors R _{1 to} R ₄ . The light bulb 1 has a NA when at least one of the switches SW _{1 to} SW ₄ is turned on.
The output of the ND gate goes low, so that the transistor Q ₀ turns on and lights up.

Further, CPU 5 of the on input ports P ₁ to P ₄ are switches SW ₁ to SW _4, corresponding to the OFF becomes high or low level, thereby CPU 5 Which switch is ON among the switches SW ₁ to SW _4, It is determined which switch is off, and the result of the determination is displayed on the display device 6. With this configuration, it is possible to recognize which door is a half-door or an open state.

However, the conventional lighting device drive circuit has a plurality of switches.
Since the transistor Q ₀ is connected to the control terminal of the control transistor Q ₀ via the NAND gate and the lighting device is controlled by the transistor Q ₀ , the circuit becomes complicated and the transistor Q ₀
There is a problem that a relatively large current flows through the device, and therefore a heat sink or the like is required, so that the space occupied by the circuit becomes large.

The present invention has been made in view of the above points, and an object thereof is to provide a lighting device drive circuit that is simple and has a small occupied space.

Means for Solving the Problems The present invention connects a plurality of switches to a lighting device, and when at least one of the plurality of switches is turned on, a driving current is supplied to the lighting device from a driving power source, In a lighting device drive circuit for lighting the device, connected between each of the plurality of switches and the lighting device, to pass the drive current when the plurality of switches are turned on, in the opposite direction to the drive current. A first rectifying element for blocking current, and a plurality of input terminals corresponding to the plurality of switches,
A display control unit that determines the switching states of the plurality of switches according to the signal levels of the plurality of input terminals and performs display, and supplies a determination signal of a predetermined level to the plurality of input terminals of the display control unit. It is connected between the discrimination signal supply means, the connection point of the first rectifying element and the plurality of switches, and the plurality of input terminals of the display control means, and is connected to the plurality of input terminals of the drive current. A second connecting element for blocking inflow.

Advantageous Effects of Invention According to the present invention, the first rectifying element can prevent the signal from the determination signal supply means from flowing into the lighting device, so that it is possible to prevent the lighting device from being turned on regardless of whether the switch is turned on or off. Since the second rectifying element can prevent the drive current from driving the lighting device to be turned on to the input terminal of the display control means from flowing in, it is possible to prevent destruction due to the drive current of the display control means.

For this reason, a plurality of switches can be shared and used for the drive current and the determination signal having different levels, and a simple configuration displays even the direct drive of the lighting device by the plurality of switches and the switching state of each of the plurality of switches. It becomes possible.

Embodiment FIG. 1 shows a circuit diagram of an embodiment of the present invention.

In the figure, reference numeral 1 denotes a light bulb which serves as an illuminating device driven by a drive circuit, and here shows an interior light of an automobile. One end of the light bulb 1 is connected to the power supply of voltage V _1G , the other end is connected to the switch SW ₁ via the diode D ₁ and the switch S is connected via the diode D _2.
It is connected to the switch SW ₃ via W ₂ and the diode D ₃ , and further connected to the switch SW ₄ via the diode D ₄ .

Switch SW ₁ to SW ₄ is turned on by opening and closing of the four-door type vehicle door is mounted so as to turn off.

The other end of the switch SW ₁ to SW ₄ is connected to ground.
The cathodes of the diodes D _{1 to} D ₃ are connected to the switches SW _{1 to} SW ₄ side, and the anodes are connected to the light bulb 1 side.

A CPU 5 determines which of the switches SW _{1 to} SW ₄ is on and controls the display of the warning display device 6. CPU5 The have four switches SW ₁ to SW ₄ 4 for distinguishing the input ports P ₁ to P ₄ are provided, the input ports P ₁ and diode D ₄ and the switch SW ₄ via the diode D ₅ The input port P ₂ is connected to the connection point of the diode D ₃ and the switch SW ₃ via the diode D ₆ , and the input port P ₃ is connected to the diode D ₂ and the switch SW via the diode D _{7. The} input port P ₄ is connected to the diode D ₁ and the switch via the diode D ₈
Connected to the connection point with SW ₁ .

Diodes D _{5 to} D ₈ are diodes for backflow prevention so that the anode is on the input port P _{1 to} P ₄ side of CPU 5 and the cathode is connected to diodes D _{1 to} D ₄ and switches SW _{1 to} SW _4. It is connected so as to be on the point side, and prevents current from flowing from the light bulb 1 side to the input ports P _{1 to} P _{4 of the} CPU 5.

The voltage V _DD is applied to the connection point between the diode D ₅ and the input port P ₁ via the resistor R ₁ , and the diode D ₆ and the input port P ₂
A voltage V _DD via a resistor R ₂ to the connection point is applied and, in the connection point between the diode D ₇ and the input port P ₃ is the voltage V _DD via a resistor R ₃ is applied, further, the diode D _The voltage V _DD is applied to the connection point between ₈ and the input port P ₄ via the resistor R ₄ .

Next, the operation of the circuit will be described. First, a plurality of switches SW ₁ to SW ₄ are all in the off, the diode D ₁ to D ₄
Since the diodes D _{5 to} D ₈ are turned off, the light bulb 1 is turned off, and the input ports P _{1 to} P ₄ of the CPU 5 are at high level. The CPU 5 determines that all the switches SW _{1 to} SW ₅ are in the off state when the input ports P _{1 to} P ₄ are at the high level, and turns off all the warning display devices 6 corresponding to the switches SW _{1 to} SW _5. Control.

When the switch SW ₁ is turned on, the diode D ₁ is turned on, a current flows through the light bulb 1 through the diode D ₁ and the switch SW ₁ , and the light bulb 1 is turned on. Further, when the switch SW ₁ is turned on, the diode D ₈ is also turned on, and the input port P ₄ becomes low level. For this reason, CPU5 of the input port P ₁ ~P ₃
Is high level, and the input port P ₄ is low level. As a result, the CPU 5 turns on the switch SW _{1 and} turns on the switches SW _{2 to} SW ₄
Is determined to be in the off state, and the warning display device 6 is controlled to notify that the door corresponding to the switch SW ₁ is in the half-door state.

The switches SW _{2 to} SW ₄ operate similarly to the switch SW _{1, respectively} . Further, even when a plurality of switches SW _{1 to} SW ₄ are turned on at the same time, the light bulb 1 is turned on, and the warning display device 6 indicates that the door corresponding to the turned-on switch is in a half-door state. A notice is displayed.

In this way, even if one of the switches SW _{1 to} SW ₄ is turned on, that is, even if one of the switches is in the open state, the interior light is turned on to inform that the door is in the half-door state.

When a plurality of doors are in the half-door state at the same time, the doors are prioritized and the warning display device 6 displays a warning in the half-door state according to the priority.

Note that the warning may be displayed separately for each door.

Thus, the switches SW ₁ -S are routed through the diodes D ₁ -D _4.
With the structure supplying a current to W _4, the rectifying elements such as diodes D ₁ to D ₄ as compared to switching elements such as transistors are caused by a large current, a strong thermal radiator plate or the like is not required, the circuit The private space of can be reduced. Further, the diodes D _{1 to} D _{4 form a} transistor,
Since the operation of the NAND gate is overridden, the circuit can be simplified and the cost can be reduced.

Effect of the Invention As described above, according to the present invention, the lighting device can be directly controlled by the plurality of switches through the rectifying element and the ON / OFF states of the plurality of switches can be displayed. It has features such as simplification and a small circuit space.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional example. 1 ... bulb, 3 ... CPU, 4 ... display device, SW ₁ to SW ₄ ... switch, D ₁ to D ₈ ... diodes.

Claims (1)

[Scope of utility model registration request] 1. A lighting device comprising: a plurality of switches connected to a lighting device; and when at least one of the plurality of switches is turned on, a driving current is supplied to the lighting device from a driving power supply to turn on the lighting device. A device driving circuit, which is connected between each of the plurality of switches and the lighting device, passes the driving current when the plurality of switches are turned on, and blocks a current in a direction opposite to the driving current; 1 having a rectifying element and a plurality of input terminals corresponding to the plurality of switches,
A display control unit that determines the switching states of the plurality of switches according to the signal levels of the plurality of input terminals and performs display, and supplies a determination signal of a predetermined level to the plurality of input terminals of the display control unit. It is connected between the discrimination signal supply means, the connection point of the first rectifying element and the plurality of switches, and the plurality of input terminals of the display control means, and is connected to the plurality of input terminals of the drive current. A lighting device drive circuit, comprising: a second connection element that blocks an inflow.