JP2738870B2 - Indicating instrument control circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indicating instrument control circuit, and more particularly to an instruction for controlling an indicating instrument that converts a physical change into digital data and performs display according to the digital data. It relates to an instrument control circuit.

2. Description of the Related Art For example, a control circuit for controlling the display of an indicating instrument such as an automobile speedometer, an engine speedometer, a water temperature gauge, and a fuel gauge conventionally converts an input signal shown in FIG. After the conversion, the signal is supplied to the drive circuit 9 via the digital filter circuit 4 for adjusting the response characteristic, and a drive signal corresponding to the digital data supplied by the drive circuit 9 is generated and supplied to the display device 10. Was.

Problems to be Solved by the Invention However, the conventional indicating instrument control circuit does not include a circuit such as a hysteresis circuit for preventing the indicating instrument from running or flickering at the time of constant speed running. Or, a flicker may occur in the indication, and if a hysteresis circuit or the like is provided in order to reduce a variation in the indication or indication of the indicating instrument, there is a problem that the entire circuit configuration becomes complicated and the cost increases. Was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an indicating instrument circuit which has been made in view of the above points, and which can reduce display or instruction variations occurring on the indicating instrument at low cost.

Means for Solving the Problems According to the present invention, a detection signal is converted into digital data by a signal conversion means, the digital data is adjusted in response characteristics through a digital filter circuit, and then supplied to an indicating instrument to give an instruction. In the indicating instrument control circuit, the processing of a fraction generated in a calculation result at the time of calculation processing performed in the digital filter circuit is processed so that hysteresis occurs in the digital filter circuit.

Operation Various operation processes such as addition, subtraction, multiplication and division are performed in the digital filter circuit, and the operation results have fractions. Hysteresis characteristics can be added to the digital filter circuit by appropriately performing the fraction processing of the calculation result.

Embodiment FIG. 1 is a block diagram showing a main part of an embodiment of the present invention.

This embodiment is an example in which the present invention is used as a control circuit of an indicating instrument for indicating the number of revolutions of an engine of an automobile or the like. As shown in FIG. 3, a terminal 1 is an input terminal to which an input pulse signal synchronized with the rotation of the engine is supplied. The terminal 1 is connected to the waveform shaping circuit 2, and an input pulse signal input from the terminal 1 is supplied to the waveform shaping circuit 2.

The waveform shaping circuit 2 shapes and outputs the waveform of the input pulse signal. The input pulse signal whose waveform has been shaped by the waveform shaping circuit 2 is supplied to the frequency counting circuit 3, where the frequency counting circuit 3 counts the number of pulses during a certain period and converts it into digital data. The output digital data X [n] of the frequency counting circuit 3 is
Supplied to

As shown in FIG. 1, the digital filter circuit 4 cuts off a fraction generated by a 1/4 division circuit 7 comprising an adder 5, a latch circuit 6, a 1/4 division circuit 7, and a 3/4 division circuit 8, and 3 /Four
The fraction generated in the division circuit 8 is configured to be rounded up to 2/4 or more and rounded down to less than 2/4. The adder 5 receives the digital data X [n] from the frequency count circuit 3 and
Digital data is supplied from the 3/4 division circuit 8 and the data is added. The output digital data Y [n] of the adder 5 is delayed by the latch circuit 6. Latch circuit 6
Output digital data Y [n-1] is divided by a 1/4 division circuit 7
, Is multiplied by 1/4 and output as A [n], and is also supplied to the 3/4 divider 8 to be multiplied by 3/4 and supplied to the adder 5.

Output digital data A of digital filter circuit 4
[N] is supplied to the drive circuit 9. The drive circuit 9 generates a drive signal for causing the display device 10 to perform display according to the input signal from the output digital data A [n] of the digital filter circuit 4, and supplies the drive signal to the display device 10. Display device
Reference numeral 10 performs a display according to the input signal in accordance with the drive signal from the drive circuit 9.

The digital filter circuit 4 will be described in more detail. Assuming that the digital data output from the frequency count circuit 3 and the digital data input to the digital filter circuit 4 is X [n] and the output digital data from the adder 5 is Y [n], the latch circuit 6
Is Y [n-1]. Further, the output digital data of the digital filter circuit 4 obtained by multiplying Y [n-1] by 1/4 by the 1/4 divider circuit 7 is defined as A [n].

The output digital data Y [n] of the adder 5 is added to the input digital data X [n] of the digital filter circuit 3 by 3 /
The result is obtained by adding the digital data output from the 4 division circuit 8 to the 3/4 division circuit 8 from the latch circuit 6.
Y [n] = X [n] + Y [n−1] · 3/4 because the digital data of [1] is supplied. Since the output digital data A [n] of the digital filter circuit 7 is obtained by multiplying the output digital data Y [n-1] of the latch circuit 6 by 1/4, A [n] = Y [n-1].・ It becomes 1/4.

In the 3/4 division circuit 8, when the remainder generated when Y [n-1] is multiplied by 3/4 becomes 2/4 or more, the remainder is rounded up, and when the remainder is less than 2/4, rounding down is performed. In step 8, the process of cutting off all remainders is performed.

Thus, by performing such remainder processing in the 3/4 division circuit 8 and the 1/4 division circuit 7, a hysteresis characteristic can be provided. For example, as shown in Table 1, X
When [n] falls from 20 to 10 at n = 0 to n = 1, A
[N] converges to 10.

As shown in Table 2, when X [n] goes from 0 to 10 at n = 0 to n = 1, A [n] converges to 9.

In this manner, a digital filter circuit having a hysteresis characteristic can be formed, and the variation in display or instruction of the display device 10 can be further reduced, and a display or instruction with a better feeling can be performed.

The display device 10 may be not only a digital display device using a light emitting diode or the like, but also an analog display device such as a cross-coil instrument.

Further, the digital filter circuit 4 is not limited to the configuration shown in FIG. 1, but a more complicated high-order filter may be used, and furthermore, a plurality of filters may be used.

As described above, since the hysteresis characteristic can be added with a simple circuit configuration and without providing a special circuit, variations in the display or instruction of the indicating instrument can be reduced at low cost.

The digital filter circuit 4 can be configured by a logic circuit, or can be configured by being programmed by a microcomputer or the like. Alternatively, it may be configured by another method. Also, the method of processing the fraction is not limited to that of the present embodiment, but the point is that it is sufficient to perform the fraction processing for obtaining the hysteresis characteristic.

Further, in this embodiment, the signal converting means 11 is connected to the waveform shaping circuit 2.
And a frequency counting circuit 3 for instructing the number of rotations and the like. In order to instruct the pressure, temperature and the like, for example, as shown in FIG.
The A / D conversion circuit 12 may be configured to convert a signal obtained through a sensor for detecting temperature, pressure, and the like and a sensor amplifier 14 into digital data X [n].

As described above, according to the present invention, the hysteresis characteristic can be added to the digital filter circuit only by appropriately performing the fraction processing of the digital filter circuit, so that the display instrument or the display flicker can be reduced at low cost. It has features such as being able to do.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of one embodiment of the present invention, FIG. 2 is a block diagram of a main part of another embodiment of the present invention, and FIG. 3 is a block diagram of an example of an indicating instrument control circuit. . 4 ... Digital filter circuit, 5 ... Adder, 6 ...
Latch circuit, 7: 1/4 division circuit, 8: 3/4 division circuit.

Claims (1)

(57) [Claims] A detection signal is converted to digital data by a signal conversion means, and the digital data is adjusted in response characteristics through a digital filter circuit. Then, the digital signal is supplied to an indicating instrument according to output digital data of the digital filter circuit. An indicating instrument control circuit for performing an instruction, wherein a processing of a fraction generated in an operation result in an operation processing performed in the digital filter circuit is performed so that hysteresis occurs in the digital filter circuit. circuit.