JPH0526905A - Drive circuit for cross coil movement - Google Patents

Abstract

PURPOSE:To cancel a change due to the existence or nonexistence of vibration and thereby to reduce a display error by setting two kinds of SIN and COS approximation signals corresponding to input signals, respectively, and by changing a cross coil angle by selecting either of these two kinds of signals. CONSTITUTION:A determination circuit 10 determines whether a change in a control angle is in a rising direction or a falling direction by comparing voltages V inputted from a frequency measuring circuit 1 before and after a prescribed time, and controls MPX circuits 13 and 14 by its output, so as to select two approximation signals from memories 11 and 12 wherein SIN and COS signals for a rise and a fall are set beforehand. The two signals are supplied to coils 6a and 6b, through two PWMs 4 and 8 and drivers 5 and 9 and thereby a cross coil movement 6 is driven. In this case, a difference in a control angle by the SIN approximation signals for the rise and the fall is so set as to correspond to hysteresis characteristic angles of the coils 6a and 6b making up a cross coil being driven under the control, and therefore skipping of an indicator at the time of switching from the rise over to the fall or from the fall over to the rise is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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.

[0002]

2. Description of the Related Art As a conventional cross coil movement driving circuit, for example, there is one shown in FIG. In FIG. 8, reference numeral 1 denotes a frequency measurement circuit for measuring a frequency (or cycle) of a measurement signal (pulse) from a sensor (not shown) such as a vehicle speed sensor, and an F-V that converts the frequency into a voltage and outputs the voltage. The conversion part A is formed. Reference numeral 2 is a calculation circuit for dividing the frequency measured by the frequency measurement circuit 1 into sine and cosine, 3 is a SIN function generating circuit, and 4 is a first pulse width for pulse-width modulating the SIN approximation signal from the SIN function generating circuit 3. Modulation circuit (first PWM), 5 is the first PW
A first driver 7 for driving one coil 6a of the cross coil movement 6 forming the cross coil portion C based on the SIN approximate signal PWM-chopped in M4, and 7 is C
OS function generating circuit, 8 is C from the COS function generating circuit 7.
A second pulse width modulation circuit (second PWM) 9 for performing pulse width modulation on the OS approximate signal, and 9 is a second driver for driving the other coil 6b of the cross coil movement 6 based on the COS approximate signal PWM choppered in the second PWM 8. Therefore, the calculation circuit 2 and each part of the driver 9 (excluding the cross coil movement 6) form a VI conversion part B.

Next, the operation will be described. The frequency measuring circuit 1 measures the input frequency from the sensor, and the frequency measuring circuit 1 outputs a voltage V corresponding to the input frequency f shown in FIG. The calculation circuit 2 divides the input frequency into the SIN function and the COS function, and the SIN function is generated in the first PWM 4 by the PWM chopper of the SIN function generating circuit 3 to excite one coil 6a of the cross coil movement 6 by the first driver 5. To do. The COS function is COS
PWM chopper is performed in the second PWM 8 via the function generating circuit 7, and the second driver 9 excites the other coil 6b of the cross coil movement 6. 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 a vehicle meter is instructed by a pointer driven by this movable magnet.

[0004]

However, in such a conventional cross-coil movement drive circuit, the cross-coil type instrument (display) is electrically controlled mainly by mechanical loss of a movable part such as a bearing. The actual indicated angle differs from the angle (hysteresis angle Δθ). Therefore, the control angle is increased (0 ° → 360 °) and decreased (3 °).
In the case of 60 ° → 0 °), the indicated value is different for the same input frequency (input signal). Further, there is a problem that the magnitude of hysteresis changes depending on the vibration condition from the vehicle, and the display error increases depending on the presence or absence of vibration.

The present invention has been made in view of such conventional problems, and an object thereof is to reduce a display error.

[0006]

According to a first aspect of the present invention, there is provided a cross-coil movement drive circuit which generates a SIN approximation signal and a COS approximation signal according to an input frequency, and a first pulse width modulation circuit produces the SIN approximation signal. The signal is pulse-width modulated, and at the same time, the second pulse width modulation circuit
In the cross coil movement drive circuit configured to drive the cross coil movement by pulse-width modulating the OS approximation signal, two kinds of the SIN approximation signal and the COS approximation signal corresponding to the input frequency are set in advance. It is characterized in that any one of them is selected when the pointer is raised and lowered, and is supplied to the cross coil movement.

The cross coil movement drive circuit according to the second aspect of the invention has an SI corresponding to the input frequency.
Each of the N-approximate signal and the COS-approximate signal is set in advance, and any one of them is selected according to the rising, stopping, and falling of the pointer.

[0008]

According to the invention of claim 1, S corresponding to the input signal is applied.
Two kinds of each of the IN approximate signal and the COS approximate signal are set in advance, and the invention according to claim 2 sets three kinds of each of the SIN approximate signal and the COS approximate signal in advance, and a control angle changing direction with respect to the input signal. Either the SIN approximate signal or the COS approximate signal set according to the above is selected to change the control angle for the cross coil movement drive circuit, so that the hysteresis change (decreasing direction) when vibration is applied is fixed. It is possible to reduce the display error by canceling the change in the display error caused by the presence or absence of vibration.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the present invention. First, the configuration will be described. In FIG. 1, which is the same as the conventional device shown in FIG.
A determination circuit 10 is provided for comparing the voltage value output from the frequency measurement circuit 1 forming the V conversion unit A before and after a predetermined time and determining whether the control angle change is in the ascending or descending direction. The determination circuit 10 is composed of, for example, a time constant circuit 10a and a Schmitt circuit 10b.

Further, the V-I conversion section B is a memory in which two kinds of SIN approximation signal and COS approximation signal for rising and falling are respectively set in advance on the output side of the SIN function generating circuit 3 and the COS function generating circuit 7. 11 and 12 and one of the two types of the SIN approximate signal and the COS approximate signal based on the determination output of the determination circuit 10 to select the first PWM.
Multiplexer circuits (hereinafter abbreviated as MPX circuits) 13 and 14 for outputting to the fourth and second PWMs 8 are provided.

Next, the operation will be described. The voltage V output from the frequency measuring circuit 1 based on the input signal is V-
It is supplied to the calculation circuit 2 and the determination circuit 10 of the I conversion unit B.
The calculation circuit 2 converts the input voltage V into the SIN function and COS.
Divide into functions. This divided SIN function and COS
Corresponding to the function, the rising and falling SIN approximate signals and COS approximate signals shown in FIG.
Is set to.

On the other hand, the judging circuit 10 compares the voltage V input from the frequency measuring circuit 1 before and after a predetermined time,
It is determined whether the change in the control angle is in the ascending direction or the descending direction, and the MPX circuits 13 and 14 are controlled by this determination output to control the memory 11
And 12 to select the rising or falling SIN approximate signal and the COS approximate signal, and the SIN coil 6a and the COS coil 6 via the first PWM 4, 8 and the drivers 5, 9.
b to drive the cross coil movement 6. In this case, the rising and falling SIN approximation signals and COS
The control angle difference Δθ based on the approximate signal is set to be equivalent to the hysteresis characteristic angle of the SIN coil 6a and the COS coil 6b, which are the crossing coils to be controlled and driven, so that a guideline for switching from rising to falling or from falling to rising is provided. Prevent flying.

FIG. 3 shows a second embodiment. In this embodiment, the VI converting section B has the same structure as the conventional device shown in FIG. 4, and the output voltage V of the frequency measuring circuit 1 is shown in FIG. As shown, a level shift circuit (for example, an adder circuit) 15 that changes and outputs for ascending or descending is provided, and the level shift circuit 15 is controlled by the judgment output of the judgment circuit 10. The output difference of the level shift circuit 15 corresponds to the hysteresis angle of the control angle difference Δθ, and has the same effect as the first embodiment.

FIG. 5 shows a third embodiment, in which the memory 1
There are three types of SIN approximate signals and COS approximate signals that should be preset in 1 and 12, one for rising, one for falling, and one for stopping (no change), and M is determined by the determination output of the determination circuit 10.
The PX circuits 13 and 14 are controlled to select the above three types of SIN approximate signal and COS approximate signal.
The same effects as those of the first embodiment shown in are obtained.

That is, in the conventional device shown in FIG.
As shown by 0, there is a hysteresis angle Δθ in the ascending / descending control direction of the pointer 16 with respect to the control angle, and the pointer 16 moves in the control angle direction due to external vibration, which causes an instruction error.

However, according to the present invention, the angle is advanced by .DELTA..theta. / 2 with respect to the control angle with respect to the input signal so that the original position of the pointer 16 in the ascending / descending control direction is reached. Is added, the hysteresis decreases toward each of the rising / falling control angles. Therefore, although the same hysteresis angle Δθ as that of the above conventional device occurs, the control error is defined in the ascending direction or the descending direction by the SIN approximate signal and the COS approximate signal for stopping when there is no ascending / descending, and therefore the display error is Δθ / It can be as small as 2.

[0017]

As described above, according to the present invention, two kinds or three kinds of the SIN approximate signal and the COS approximate signal corresponding to the input frequency (input signal) are set in advance, whichever of them is set. Since it is configured to be supplied to the cross coil movement 6 when the pointer is raised or lowered, the direction in which the control angle with respect to the input signal changes is determined and the SIN coil and COS of the cross coil portion are determined.
The control angle with respect to the coil can be changed, and the hysteresis change (decreasing direction) when vibration is applied can be regulated to a certain direction to cancel the display error change and reduce the display error. In the above embodiment, Δθ is equivalent to the hysteresis generated in the bearing portion, but it is needless to say that it must be set to a value considering gear backlash when a gear is provided on the rotating shaft. That's a good thing.

[Brief description of drawings]

FIG. 1 is a block diagram of a cross coil movement drive circuit according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing the relationship between the drive current and the control angle in the first embodiment.

FIG. 3 is a block diagram of a cross coil movement drive circuit according to a second embodiment of the present invention.

FIG. 4 is a waveform diagram showing the relationship between the drive current and the control angle in the second embodiment.

FIG. 5 is a block diagram of a cross coil movement drive circuit according to a third embodiment of the present invention.

FIG. 6 is a waveform diagram showing the relationship between the drive current and the control angle in the third embodiment.

FIG. 7 is an operation explanatory diagram of a pointer in the third embodiment.

FIG. 8 is a block diagram of a conventional cross coil movement drive circuit.

FIG. 9 is a waveform diagram showing the relationship between the output voltage with respect to the input signal and the drive current with respect to the control angle in the conventional circuit.

FIG. 10 is a diagram for explaining the operation of the pointer in the conventional circuit.

[Explanation of symbols]

4 First pulse width modulation circuit 6 crossed coil movement 8 Second pulse width modulation circuit

Claims (2)

[Claims] 1. A SIN approximation signal and a COS approximation signal are generated according to an input frequency, the first pulse width modulation circuit (4) pulse-width modulates the SIN approximation signal, and a second pulse width modulation circuit (8). ), The cross coil movement driving circuit is configured to drive the cross coil movement (6) by pulse-width-modulating the COS approximation signal, and the SIN corresponding to the input frequency.
Two types of the approximate signal and the COS approximate signal are set in advance, and one of them is selected when the pointer rises and falls and is supplied to the cross coil movement (6). Drive circuit. 2. Three kinds of SIN approximate signals and COS approximate signals corresponding to the input frequency are set in advance, respectively.
2. The cross coil movement drive circuit according to claim 1, wherein any one of them is selected when the pointer is raised, stopped, and lowered.