JPH0650777Y2 - Cross coil movement drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cross coil movement drive circuit for supplying a measurement signal detected by a sensor to a cross coil meter to drive the cross coil meter.

[Conventional technology]

As a conventional cross coil movement driving circuit, for example, there is one shown in FIG. In the figure, 1 is a frequency measuring circuit for measuring the frequency (or period) of a measurement signal (pulse) from a sensor (not shown) such as a vehicle speed sensor, and 2 is the sine and cosine of the frequency measured by the frequency measuring circuit 1. The calculation circuit for dividing into 3 is a SIN function generation circuit, 4 is a first pulse width modulation circuit (first PWM) for pulse width modulating the SIN approximation signal from the SIN function generation circuit 3, and 5 is a
The first driver that drives one coil 6a of the cross coil movement 6 based on the SIN approximation signal PWM-chopped in 1PWM4, 7 is a COS function generation circuit, 8 is a pulse width modulation of the COS approximation signal from the COS function generation circuit 7. A second pulse width modulation circuit (second PWM) 9 for driving is a second driver for driving the other coil 6b of the cross coil movement 6 based on the COS approximation signal PWM choppered by the second PWM 8.

The following operation will be described.

The input frequency from the sensor is measured by the frequency measurement circuit 1, the input frequency is divided into the SIN function and the COS function by the calculation circuit 2, and the SI is generated in the first PWM 4 via the SIN function generation circuit 3.
The N function is PWM chopper to excite one coil 6a of the cross coil movement 6 by the first driver 5. Also,
The COS function is P in the second PWM8 via the COS function generation circuit 7.
The second driver 9 excites the other coil 6b of the cross coil movement 6 by the WM chopper. Then, a movable magnet (not shown) is rotationally driven by the magnetic fields of both coils 6a and 6b of the cross coil movement 6, and the pointer for the vehicle is used to indicate.

[Problems to be solved by the device]

However, in such a conventional cross coil movement driving circuit, the SIN approximate signal and the COS approximate signal are
Since the PWM chopper is used to drive the cross coil movement 6, there is a problem that when the chopper frequency is higher than the audible frequency, the response of the element is deteriorated, the linearity is deteriorated, and radio noise is generated. . Further, if the chopper frequency is too low, there is a problem that a sound is generated from the cross coil movement 6 and a needle shake occurs, and it is difficult to find a compromise.

The present invention has been made in view of such a conventional problem, and an object thereof is to provide a cross coil movement drive circuit in which a sound is not generated from a cross coil movement or a needle shake is not generated. To do.

[Means for Solving the Problems]

The cross-coil movement drive circuit according to the present invention comprises first and second pulse width modulation circuits for respectively pulse width modulating a SIN function and a COS function according to an input signal,
The first and second pulse width modulation circuits are separately connected, and provided with first and second PWM-DC conversion circuits for converting the pulse width modulated SIN approximate signal and COS approximate signal into a DC voltage. It is a thing.

[Action]

The cross-coil movement drive circuit in this invention generates the SIN function and the COS function according to the input frequency,
The MIN chopper modulates the SIN approximate signal and the COS approximate signal, and the PWM-DC conversion circuit converts them into DC voltage.

〔Example〕

 The invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the same or equivalent components as in FIG. In FIG. 1, reference numeral 10 is a first PWM-DC conversion circuit for converting the pulse width, which is PWM choppered by the first PWM4 at a low chopper frequency, which changes like a SIN function into an analog DC voltage, and 11 is a first PWM-DC conversion circuit.
The first DC amplifier circuit for DC-amplifying the analog DC voltage from the PWM-DC converter circuit 10 of the above, 12 is the PWM chopper by the second PWM8 at a low chopper frequency, and the COS function changing pulse width is converted into the analog DC voltage. Second PWM-DC
A conversion circuit 13 is a second DC amplification circuit for DC-amplifying the analog DC voltage from the second PWM-DC conversion circuit 12.

Next, the operation will be described.

The frequency measurement circuit 1 measures the frequency of the measurement signal from the sensor. Then, the SIN approximation signal is generated in the calculation circuit 2 and the SIN function generation circuit 3. This SIN approximate signal changes the pulse width in a SIN function by the first PWM4.
In the first PWM-DC conversion circuit 10, the PWM signal from the first PWM4 is converted into an analog DC voltage, and the first DC amplification circuit 11 performs DC amplification to amplify one coil 6a of the cross coil movement 6.
To excite. Further, the COS approximation signal obtained from the calculation circuit 2 and the COS function generation circuit 7 changes the pulse width as a COS function by the second PWM8. The second PWM-DC conversion circuit 12 converts the PWM signal from the second PWM8 into an analog DC voltage,
The second DC amplification circuit 13 carries out DC amplification to excite the other coil 6b of the cross coil movement 6. Then, the movable magnet is rotationally driven by the magnetic fields of both coils 6a and 6b of the cross coil movement 6, and an instruction according to the input signal from the sensor is given by the pointer of the vehicle meter.

[Effect of device]

As described above, according to the present invention, the configuration is such that the SIN approximate signal and the COS approximate signal are generated according to the input frequency, and the SIN approximate signal is pulse-width modulated by the first pulse width modulation circuit. A cross-coil movement driving circuit for driving the cross-coil movement by pulse-width modulating the COS approximate signal by a second pulse-width modulating circuit, which is connected to the first pulse-width modulating circuit and pulse-width modulating A first PWM-DC converting circuit for converting the SIN approximated signal thus converted into a DC voltage and a second PWM circuit for converting the pulse width modulated COS approximated signal into a DC voltage. The cross-coil movement drive circuit is characterized by having two PWM-DC conversion circuits, so sound is generated from the cross-coil movement and needle shake occurs. Moreover, since the cross coil movement is driven by an analog DC voltage, the effect of eliminating the stepwise movement of the needle, which is a problem during digital driving, can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a crossing coil movement drive circuit according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional crossing coil movement drive circuit. 4 ... 1st pulse width modulation circuit, 6 ... Cross coil movement, 8 ... 2nd pulse width modulation circuit, 10 ... 1st PWM-D
C conversion circuit, 12 ... Second PWM-DC conversion circuit.

Claims (1)

[Scope of utility model registration request] 1. A SIN approximation signal and COS depending on an input frequency.
An approximate signal is generated, the first pulse width modulation circuit (4) pulse-width modulates the SIN approximate signal, and the second pulse
In the cross-coil movement drive circuit in which the COS approximation signal is pulse-width modulated by the pulse-width modulation circuit (8) to drive the cross-coil movement (6), the first pulse width modulation circuit (4) is Connected to the first PWM-DC conversion circuit (10) for converting the pulse width modulated SIN approximation signal into a DC voltage and the second pulse width modulation circuit (8) for pulse width modulation. Above
A cross coil movement drive circuit comprising a second PWM-DC conversion circuit (12) for converting a COS approximate signal into a DC voltage.