JPH0255749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a drive circuit for a crossed coil meter.

Conventional configuration and its problems Cross-coil meters such as automobile meters use a frequency/voltage (F/V) conversion circuit that converts an input signal frequency proportional to the number of rotations of a wheel into a DC signal voltage. A rotating magnetic field proportional to the input signal is generated by applying two meter drive outputs with a sine and cosine relationship to two orthogonal coils from a meter drive circuit that receives the DC signal voltage from the same circuit. This is used to generate the signal and make the meter indicate the signal.

The drive circuit output of conventional crossed coil meters was fixed at a circuit-specific level, so if the power supply voltage was low, the meter could not be driven, or the output level was limited by the power supply voltage, resulting in poor accuracy. It was impossible to drive the meter while maintaining the

Furthermore, if the output level is set to match the low power supply voltage in order to prevent the above drawbacks, the output level will be kept low even at the high power supply voltage, making it impossible to obtain a sufficiently large torque.

In other words, under usage conditions with a wide power supply voltage range,
The output level is determined by the minimum operating power supply voltage, and the drawback is that it cannot meet the demand for high torque at high power supply voltages.

OBJECTS OF THE INVENTION The present invention provides a driving circuit for a crossed coil type meter which improves the drawbacks of the above-mentioned conventional example.

Structure of the Invention The present invention has an F/V conversion circuit that converts an input signal frequency into a DC signal voltage, and connects its output to the input of a meter drive circuit.
By connecting the power terminals of the F/V conversion circuit and the meter drive circuit to an external power supply, the meter drive circuit outputs a pair of outputs corresponding to the power supply voltage. You can get the output.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a circuit configuration diagram of an embodiment of the present invention. That is, the circuit configuration of this embodiment includes an F/V conversion circuit 1 that outputs a DC signal voltage proportional to the power supply voltage.
This is a crossed coil type meter drive circuit comprising a meter drive circuit 2 which receives this DC signal voltage as input and generates a sine component output and a cosine component output for meter drive at a level proportional to the power supply voltage.

Since the output level of the F/V conversion circuit and the input level of the meter drive circuit corresponding one-to-one are not directly related to torque, they may be fixed as long as they are set to be lower than the minimum power supply voltage.

That is, the F/V conversion circuit 1 and the meter drive circuit 2 have a function of detecting the power supply voltage and generating an F/V conversion circuit output proportional to the power supply voltage, as well as a sine component output and a cosine component output. however,
The final objective is to increase the sine component output and cosine component output in proportion to the power supply voltage.
The aim is to obtain high torque, and if the level of the F/V conversion circuit output, which is an intermediate output, is set so that the output does not saturate and operates normally even at low power supply voltages, it will not depend on the power supply voltage. It may be fixed.

FIGS. 2(A) to 2(E) are characteristic diagrams obtained in an embodiment of the present invention. Figures 2 (a) and (b) show the input frequency on the horizontal axis and the output of the meter drive circuit on the vertical axis.
FIG. 2(A) shows a case where the power supply voltage is high, and FIG. 2(B) shows a case where the power supply voltage becomes low and the output level of the meter drive circuit decreases accordingly. Second
Figure (c) shows the F/V conversion circuit characteristics.
This shows that when the power supply voltage decreases from (a) to (b), the DC signal voltage level decreases accordingly. Furthermore, FIGS. 2(d) and (e) show the DC signal voltage of the F/V conversion circuit on the horizontal axis and the output of the meter drive circuit on the vertical axis. In other words, when the power supply voltage is high in Figure 2 (D), the power supply voltage is low in Figure 2 (E),
This is a case where both the DC signal voltage of the F/V conversion circuit and the output level of the meter drive circuit become small.

Effects of the Invention According to the present invention, the pair of outputs of the meter drive circuit changes in proportion to the power supply voltage while maintaining the ratio of the sine component and the cosine component. Maximum torque at voltage can be obtained, and crossed coil meters can be driven with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a cross-coil type meter drive circuit diagram of the present invention, and FIGS. 2(A) to (E) are characteristic diagrams showing embodiments of the present invention. 1... F/V conversion circuit, 2... Meter drive circuit, 3... Cross coil type meter, 4, 5... Drive coil, 6... External power supply.

Claims (1)

[Claims] 1. In a frequency/voltage conversion circuit that converts an input signal frequency to a DC signal voltage, and a meter drive circuit that drives a crossed coil meter using this DC signal voltage as input, the frequency/voltage conversion circuit converts a DC signal proportional to a power supply voltage. 1. A drive circuit for a crossed coil type meter, characterized in that the meter drive circuit is configured to output a signal voltage and generate an output proportional to a power supply voltage.