JP2508978Y2 - Input data detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an input data detection circuit for inputting a reference potential and data input to a comparison circuit and outputting a comparison result.

[Prior Art] As an input data detection circuit of this type, for example, there is an air bag system circuit mounted in a vehicle as shown in FIG.

This circuit includes a power source 1, a contact point 2a of a first G sensor 2 connected in series between the power source 1 and a ground, a contact point 3a of a second G sensor 3, and the first and second contacts, respectively. First and second resistors 2b and 3b as monitor resistors connected in parallel
And a squib 4 as an ignition plug of an airbag that is inserted between the two G sensors to form a third resistance, and voltage dividing resistors 5, 6, 7 connected in series between a power source and ground.
And the squib power supply side potential is input to the non-inverting input and the potential Va at the point A is input to the inverting input as the first reference potential.
The second comparison circuit 9 for inputting the potential Vb at the point B as the reference potential to the non-inverting input and the ground side potential of the squib to the inverting input, and the outputs of the comparison circuits 8 and 9. It is composed of an OR circuit 10.

The resistance value of the squib 4 is normally about several ohms, and the first and second resistors 2b and 3b are generally set to about several kilohms.

In the circuit having such a configuration, the first and second resistors 2
When any of b, 3b and the squib 4 has an open or short circuit failure, an output is output to the OR circuit 10 as shown in FIG. 4 and the failure can be detected.

[Problems to be Solved by the Invention] Although the resistance value of the squib 4 is several ohms, which is very low compared to the first and second resistances, the conventional input data detection circuit is Since the main purpose was to monitor the second resistance, the failure of the resistance of the squib could not be detected until the resistance value reached several kilo-ohms, and the accuracy was poor.

Further, by adjusting each resistance value while maintaining the circuit configuration, it is possible to make both the failure detection of the first and second resistances 2b and 3b and the squib 4 compatible with each other. Since it becomes narrower, it is difficult to configure the circuit even if you use the E96 series resistors whose resistance values are classified into the finest, and it is practically impossible considering the change in resistance value due to temperature and deterioration and the change in power supply voltage. Met.

In order to solve the above problems, the present invention provides an input data detection circuit that can monitor changes in the resistance value of the squib more accurately by adding a circuit dedicated to monitoring the resistance value of the squib to the conventional circuit configuration. The purpose is to do.

[Means for Solving the Problem] In order to solve such a problem, in the present invention, first and second resistors connected in series between a power source and ground, and a series connection between these two resistors. A third resistor inserted in the first resistor, a plurality of voltage dividing resistors for dividing the power source voltage to generate first and second reference potentials, and a third resistor for comparing the power source side potential of the third resistor with the first reference potential. 1 comparison circuit, a second comparison circuit for comparing the ground side potential of the third resistor with the second reference potential, and an OR circuit for inputting the outputs of the first and second comparison circuits. In the input data detection circuit, a third and a fourth voltage dividing resistor, which are inserted between at least a first and a second voltage dividing resistor among the plurality of voltage dividing resistors to generate third and fourth reference potentials, , A third comparison circuit for comparing the power supply side potential of the third resistor with the third reference potential, and the ground side potential of the third resistor A fourth comparison circuit for comparing the fourth reference potential; and a logical product circuit for receiving the outputs of the third comparison circuit and the fourth comparison circuit and outputting the output to the logical sum circuit. It is an input data detection device.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS.

 The description of the same parts as those of the conventional configuration will be omitted.

The input data detection circuit according to the present invention differs from the conventional input data detection circuit in the following points.

Voltage dividing resistors 11, 12, and 13 are inserted in series between the voltage dividing resistors 5 and 7 in place of the voltage dividing resistor 6.

In addition to the comparison circuits 8 and 9, comparison circuits 14 and 15 are newly provided.

The non-inverting input of the comparison circuit 14 is the squib 4 (third resistance).
Connected to the power supply side of the
Is connected to the connection point C.

The non-inverting input of the comparison circuit 15 is connected to the connection point D of the voltage dividing resistor 12 and the voltage dividing resistor 13, and the inverting input is connected to the ground side of the squib.

Further, the outputs of the comparison circuits 14 and 15 are AND circuits 16 respectively.
Is input to

The output of the AND circuit 16 is ORed with the outputs of the comparison circuits 8 and 9.
Input to the circuit 10.

 Next, the operation of this embodiment will be described with reference to FIG.

In FIG. 2, Vc represents the potential at the connection point C, and Vd represents the potential at the connection point D. V1 represents the power supply side potential of the squib 4, that is, the non-inverting input potential of the comparison circuit 14, and V2 represents the ground side potential of the squib 4, that is, the inverting input potential of the comparison circuit 15.

Vc and Vd are the reference potentials of the comparison circuits 14 and 15, respectively, but the potential difference between the reference potentials Vc and Vd can be detected even if the resistance value of the squib 4 changes by several ohms. It is set to be sufficiently smaller than the potential difference between the reference potentials Va and Vb.

As shown in Fig. 2, V1 and V2 do not change their resistance values only when the squib 4 has an open failure, and V1 becomes Vc or more and V2 becomes Vd or more, so it is output to the AND circuit 16. Appears, and the failure detection signal is output from the OR circuit 10.

However, when the first and second resistors 2 and 3 are open or short-circuited, V1 and V2 change in conjunction with each other, so that no output appears in the AND circuit.

Further, since the reference potentials of the comparison circuits 8 and 9 are set in the same manner as in the conventional case, the first and second resistors 2b and 3b are opened,
In case of short circuit failure, the comparison circuit 8,
9 outputs, and OR circuit 10 outputs a failure detection output.

As described above, according to this embodiment, the open failure of the squib 4 can be accurately detected, and the open and short failures of the first and second resistors (monitor resistance) of the G sensor can be detected as in the conventional case. .

[Effect] With the above configuration, in the present invention, the resistance of the low resistance value can be monitored accurately by making the difference in the reference potential of the comparison circuit smaller than before.

Further, since the comparison circuits are independent of each other, the monitor resistance of the G sensor can be monitored as in the conventional comparison circuit.

Further, since the logical sum of the detection result of the comparison circuit according to the present invention and the detection result of the conventional comparison circuit is taken, it is possible to monitor the resistance having a low resistance value and the resistance having a high resistance value. You can

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of an input data detection circuit according to the present invention. FIG. 2 is an operation time chart of the input data detection circuit according to the present invention. FIG. 3 is a circuit diagram of a conventional input data detection circuit. FIG. 4 is a time chart of the conventional input data detection circuit. 4 ... Squib (third resistance) 10 ... OR circuit 11, 12, 13 ... Dividing resistance 14, 15 ... Comparison circuit 16 ... AND circuit

Claims (1)

(57) [Scope of utility model registration request] 1. A first resistor, a second resistor connected in series between a power source and ground, a third resistor inserted in series between these two resistors, and a first source for dividing a power source voltage. , A plurality of voltage dividing resistors for producing a second reference potential, a first comparison circuit for comparing the power source side potential of the third resistor with the first reference potential, and a ground side potential of the third resistor And a second comparison circuit that compares the second reference potential with each other, and an OR circuit that inputs the outputs of the first and second comparison circuits. At least of the first and second
The third and fourth voltage dividing resistors that are inserted between the voltage dividing resistors to generate the third and fourth reference potentials, and the power supply side potential of the third resistor and the third reference potential are compared. A third comparison circuit, a fourth comparison circuit that compares the ground-side potential of the third resistor with the fourth reference potential, and inputs of the outputs of the third comparison circuit and the fourth comparison circuit And an AND circuit that outputs the output to the OR circuit.