JPS62239062A - Driving circuit for cross coil type meter - Google Patents

Abstract

PURPOSE:To obtain a cross coil type meter driving circuit which has small deviation from linearity by generating a sine component voltage and a cosine component voltages which are approximated to a trapezoid having two gradients at oblique side parts. CONSTITUTION:The output of a reference voltage generating circuit 2 is inputted to a two-voltage generating circuit and also inputted to an output circuit 8 and selective inverting circuits 4 and 5. Two outputs of the sine component voltage Vsin and cosine component voltage Vcos of the circuit 1 are inputted to an output circuit 6 and the circuit 5, and an output circuit 7 and the circuit 4 respectively. The circuits 4 and 5 invert the signals selectively so that the absolute values of the sine component voltage and cosine component voltage can be compared with each other, and their outputs are inputted to a comparing circuit 3 for switching two gradients of oblique side parts of the trapezoid, and the output of the circuit 3 is inputted to the circuit 1. Then the outputs of the circuits 6, and 7 and 8 are inputted to two coils of the cross type meter 9, which is driven.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a drive circuit for a crossed coil meter.

(Prior art) Cross-coil meters conventionally used in automobile meters etc. are usually driven by trapezoidal approximation as pseudo sine components or pseudo cosine components due to the technical difficulty of driving with perfect sine and cosine components. Driving was performed using the same driving voltage. FIG. 3(a) shows the relationship between input and output in a conventional example.

(Problems to be Solved by the Invention) In such a conventional drive system, the deviation from the linearity of the indicated angle is large in some parts compared to drive using complete sine and cosine components, and the indicated angle of the meter is This causes an error in the movement of the pointer when the meter is driven, and causes an unnatural movement of the pointer when the meter is driven. FIG. 3(b) shows the deviation of the indicated angle from linearity when the parameters of the trapezoidal output are determined so as to minimize the error of the indicated angle. Here, Δθ = θ (th) - 〇 (units) where o (th); Output angle θ (units) when driven with ideal sine and cosine components; Driven with trapezoidal approximated sine and cosine components is the output angle when . As shown in FIG. 3(b), in the case of driving using pseudo sine components and pseudo cosine components approximated to a trapezoid, a deviation from linearity of about ±1.5'' occurs at the minimum.

(Means for Solving the Problem) In order to solve the above problem, the present invention generates a sine component voltage and a cosine component voltage that are approximated to a trapezoid having two slopes on the hypotenuse, and generates a sine component voltage and a cosine component voltage. The absolute values of the differences between the reference voltages of the sine component voltages and the cosine component voltages are compared, and at the point where the absolute values become equal, the two slopes of the hypotenuses of the sine component voltages and the cosine component voltages are mutually switched.

(Function) With the above configuration, by adding a simple voltage comparison circuit and a circuit that mutually switches the two slopes of the hypotenuse of the trapezoid, the deviation from the linearity of the indicated angle that occurs in the trapezoidal approximation can be corrected. Small.

Furthermore, the unnatural movement of the pointer when driving the meter can be improved.

(Embodiment) FIG. 1 is a block diagram showing a crossed coil type meter drive circuit according to an embodiment of the present invention. In FIG. 1, 1 inputs an input signal voltage VIN, and a sine component voltage V sin and a cosine component voltage are approximated to a trapezoid having two slopes on the hypotenuse in order to obtain an output angle proportional to the input signal voltage. 2 is a reference voltage Vcenter generating circuit that generates a reference voltage for the sine component voltage V sin and the cosine component voltage Vcos. The output of the reference voltage generation circuit 2 is the output of the double pressure generation circuit 1.
The signal is input to the output circuit 8 and the selection inversion circuit 4.5. The two outputs of the sine component voltage Vsin and the cosine component voltage Vcos of the double pressure generation circuit 1 are as follows:
output circuit 6, selection inversion circuit 5, and output circuit 7, respectively.
and is input to the selection inversion circuit 4. Selection inversion circuit 4, 5
is for selectively inverting the signal so that the absolute values of the sine component voltage and the cosine component voltage can be compared, and its output is input to a comparison circuit 3 for switching between the two slopes of the hypotenuse portion of the trapezoid. The output of the comparison circuit 3 is input to the double pressure generation circuit 1. Each output of the output circuits 6, 7 and 8 is input to two coils of a crossed coil type meter 9,
The meter 9 is driven.

FIG. 2(a) shows the output characteristics of the drive circuit of this embodiment, in which the output characteristics of the comparator circuit 3 are as follows.

At each point b and c, the slope of the hypotenuse of the trapezoid of the sine component voltage V sin and the cosine component voltage V cos changes from 81 to 82,
Alternatively, the process switches from S2 to 81. For example, ■ Since points cO8 and c are smaller than the reference voltage, these are inverted as b' and c' by selective inversion circuits 4 and 5, and this inverted signal voltage is input to comparison circuit 3 and compared with Vsin. Then, at the point where the absolute values become equal, each slope is switched.

FIG. 2(b) shows the deviation between the output angle in this embodiment and the output angle -4= when driven by ideal sine and cosine components. In this case, by appropriately setting the values of Sl and 82, the deviation from linearity can be significantly reduced compared to the conventional example, and the unnatural movement of the meter pointer can also be significantly improved.

(Effects of the Invention) As explained above, according to the present invention, with the configuration in which a simple circuit for switching the slope of the trapezoid hypotenuse portion of the output is added to the conventional circuit, the deviation from linearity is much greater than in the conventional example. A small crossed coil meter drive circuit can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a crossed coil type meter drive circuit in one embodiment of the present invention, FIG. 2(a) is an output characteristic diagram showing the relationship between input signal voltage and output voltage in the same embodiment, and FIG. Figure 3 (b) is a characteristic diagram showing the relationship between the input signal voltage and the deviation from linearity of the output angle, and Figure 3 (a) is the output characteristic diagram showing the relationship between the input signal voltage and output voltage in the conventional example. FIG. 3(b) is a characteristic diagram showing the relationship between the input signal voltage and the deviation of the output angle from linearity in the related art. DESCRIPTION OF SYMBOLS 1...Double pressure generation circuit, 2...Reference voltage generation circuit, 3...Comparison circuit, 4, 5...Selection inversion circuit,
6,7.8...Output circuit, 9...Cross coil meter. Patent Applicant: Matsushita Electric Industrial Co., Ltd. Figure 1 2, 6.7.8, $p 9? Kt Kobenshi meter Figure 2 (a) Figure 3

Claims (1)

[Claims] A reference voltage generation circuit that applies a reference voltage to a common terminal of two coils of a crossed coil meter, and a sine component voltage and a cosine component voltage that are approximated to a trapezoid having two slopes on the hypotenuse based on the reference voltage. a drive voltage generating circuit that generates a voltage and applies each of these voltages to the two coils, and the absolute value of the difference between the sine component voltage and the reference voltage, and the difference between the cosine component voltage and the reference voltage. and a comparison means for comparing the absolute values and inputting the comparison signal to the drive voltage generation circuit, and the comparison signal makes the absolute values of the differences between the sine component voltage and the cosine component voltage equal to each reference voltage. A drive circuit for a crossed coil type meter, characterized in that the two slopes of the hypotenuse portions of the sine component voltage and the cosine component voltage are mutually switched.