JP2508992Y2 - Input circuit of the meter assembly of the electric rotation measuring instrument - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric rotation measuring instrument which receives a signal from a sensor for detecting the rotation of a portion to be measured, outputs a rectangular wave pulse by comparison with a reference voltage and sends it to a meter driving portion. The input circuit of the meter assembly.

[0002]

2. Description of the Related Art A sensor for detecting the rotational speed of a rotating object, for example, an electric sensor for detecting the rotational speed of a vehicle engine or a rear end portion of a transmission to measure the engine rotational speed or vehicle speed. The following two types are commonly used. One is a pulse type sensor that uses transistor switching, and the other is a power generation type sensor. In the pulse type, a magnetic change due to the rotation of the rotating portion is usually detected by a Hall element, shaped and amplified, inputted to a transistor, and extracted as a rectangular wave pulse by a switching operation. On the other hand, the power generation sensor extracts a sine wave output signal by inducing a coil to magnetically change due to the rotation of the rotating portion. The output of this sensor is input to an input circuit of a meter assembly including a meter, a meter driving unit, an input circuit and the like.

As shown in FIG. 2, the input circuit of the meter assembly for receiving the output signal of the pulse type sensor has a diode D ₁ and a low-pass filter (integrator circuit) composed of R ₂ and C ₂ connected in series. The cathode side of the diode D ₁ is connected to the input terminal A ₁ of the input circuit, and the output terminal of the filter is connected to the negative input terminal (inverting input terminal) of the comparator (comparator) 1. The connection point between the diode D ₁ and the filter is connected to the constant voltage V _CC by the pull-up resistor R ₁ . Further, a reference voltage is applied to the positive input terminal (non-inverting input terminal) of the comparator 1, and the reference voltage is connected to the resistors R ₃ and R ₄ connected in series between the constant voltage V _CC and the ground. Although taken out from the intermediate point, feedback is applied to the plus input terminal from the output terminal of the comparator 1 by the resistor R ₅ . The power source of the comparator 1 is a single pole and a constant voltage V _CC is applied.

When the input terminal A ₁ of this input circuit is connected to the output terminal of the pulse type sensor, that is, the collector of the transistor (the ground side is not shown), the transistor is off when the base input of the transistor is Low. Therefore, the voltage at the input terminal A ₁ is approximately V _CC . Also, the base input is H
When it is high, the transistor turns on and the input terminal A ₁
The voltage at the point is approximately 0v. This square wave pulse is R ₂ , C
_It is applied to the negative input terminal of the comparator 1 through a low pass filter (integrator circuit) consisting of ₂ . Since the reference voltage is applied to the positive input terminal of the comparator 1, the output of the comparator 1 becomes V _CC when the voltage of the negative input terminal is lower than the reference voltage, and 0 _V is output when it is higher than the reference voltage. Then, a rectangular wave pulse corresponding to the input signal is output. A resistor R ₅ is connected from the output terminal of the comparator 1 to the positive input terminal.
Since the feedback is applied at 1, the reference voltage fluctuates depending on the output voltage of the output terminal, so that the comparator 1 has a hysteresis characteristic.

[0005] On the other hand, if the sensor is of the power sensor input circuit of the meter assembly receiving the output signal of the sensor, as shown in FIG. 3, a capacitor C _1,
A low-pass filter (integrator circuit) consisting of R ₂₀ and C ₂₀ is connected in series, one end of the capacitor C ₁ is connected to the input end A ₂ of the input circuit, and the output end of the filter is the negative input terminal of the comparator 1. It is connected. In addition, the output terminal of the filter, that is, the negative input terminal of the comparator 1, has a resistor R
The voltage of V _CC × R ₇ / (R ₆ + R ₇ ) is biased by ₆ and R ₇ .

The positive input terminal of the comparator 1 has resistors R ₃₀ , R ₄₀ and R ₅₀ , as in the pulse type input circuit described above.
The reference voltage is applied by. It should be noted that the bias voltage is applied to the negative input terminal when the input signal of the input circuit is a power generation sensor, the input waveform is a sine wave, and the voltage fluctuates up and down around GND (ground), This is because the comparator 1 in the subsequent stage is operated by the single power supply V _CC and cannot be detected at zero cross.

When the input terminal A ₂ of this input circuit is connected to the output terminal of the power generation sensor, that is, the coil (the ground side is not shown), the sine wave output which is the output of the power generation sensor is connected to the capacitor C ₁ . It is applied to the negative input terminal of the comparator 1 through a low-pass filter (integrator circuit) composed of R ₂₀ and C ₂₀ and biased with a constant voltage. Since the reference voltage is applied to the plus input terminal of the comparator 1, if the voltage of the minus input terminal is less than or equal to the reference voltage, the comparator 1
Output becomes V _CC , and 0 _V is output when the reference voltage is exceeded, and a rectangular wave pulse corresponding to the input signal is output.

The rectangular wave pulse output in this manner is subsequently input to the meter drive unit, for example, when the meter is a cross-coil type, normally to the F / V conversion circuit, and then s
Meters such as a speedometer and a tachometer are driven by an in / cos generator circuit or the like.

[0009]

However, if the type of the sensor for detecting the rotation is different, if the input circuit for receiving the output is different, the type of the meter assembly is increased and the cost is increased. It is inconvenient because it is necessary to check when attaching.

It is an object of the present invention to provide an input circuit of a meter assembly of an electric rotary measuring instrument which can use the same meter assembly regardless of the output format of the sensor.

[0011]

DISCLOSURE OF THE INVENTION The present invention is an electric rotation device which receives a signal from a sensor for detecting the rotation of a portion to be measured, outputs a rectangular wave pulse by comparison with a reference voltage, and sends it to a meter driving portion. An input circuit of a meter assembly of a measuring instrument, in which an input terminal of the input circuit is connected to a constant voltage power source by a series circuit of a resistor and a diode, and one input terminal of a comparator is connected through a series circuit of a capacitor and a low-pass filter. And bias the input terminal with a bias circuit,
Further, it is characterized in that a reference voltage is applied to the other input terminal of the comparator.

[0012]

When the coil of the power generation sensor for detecting the rotation is connected to the input terminal of the input circuit of the meter assembly of the electric rotation measuring instrument based on the above-mentioned structure, the output signal GND (ground) of the coil is applied. The sine wave swinging up and down around the center is slightly biased by the resistance connected to the constant voltage power supply at the input end and the resistance of the diode and the coil. And, through the series circuit of the capacitor and the low pass filter,
Further, it is input to one input terminal of the comparator while being biased with a constant voltage. The input sine wave is compared with the reference voltage, and by moving the reference voltage up or down, the output of the comparator becomes high or low, and a rectangular wave corresponding to the input sine wave is output.

On the other hand, when a pulse type sensor utilizing switching of a transistor is connected to the input end of the input circuit of the meter assembly of the electric rotation measuring instrument,
Since the collector of the transistor is directly connected to the input terminal of the input circuit, when the base input of the transistor is low, the transistor is turned off and the voltage at the input terminal is the constant voltage minus the forward voltage drop of the diode. . Further, when the base input is high, the transistor is turned on and the voltage at the input end becomes approximately 0v. This rectangular wave pulse has a direct current component removed when it passes through a capacitor, becomes an integral waveform through a low-pass filter, and is input to one input terminal of a comparator while being biased with a constant voltage. The input waveform is compared with the reference voltage, and the output of the comparator becomes high or low by raising or lowering the reference voltage, and a rectangular wave pulse corresponding to the input rectangular wave is output.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 illustrates an input circuit of a meter assembly of an electric rotation measuring instrument of the present invention. The input terminal A ₃ of the input circuit is connected to the constant voltage V _CC of the constant voltage power source by the series circuit of the diode D ₁ and the resistor R ₁ . The input terminal A ₃ is connected to the capacitor C ₁ and R ₂₀ , C ₂₀
Is connected to the negative input terminal of the comparator (comparator) 1 via a low-pass filter (integrator circuit) composed of a constant voltage V _CC divided by a resistor R ₆ and a resistor R ₇ . It is biased with voltage. Further, a reference voltage is applied to the positive input terminal of the comparator 1 from the connection point of the series resistor R ₃₀ and the resistor R ₄₀ connected between the constant voltage V _CC and the ground, and the positive input terminal is also applied. Is fed back from the output terminal side of the comparator 1 by a resistor R ₅₀ . The power source of the comparator 1 is a constant voltage V _CC .

When a coil of a power generation sensor that generates a sine wave is connected to the input terminal A ₃ of this input circuit as shown in the figure, the input signal of the input terminal A ₃ is in the order of V _CC to diode D ₁ . Directional voltage drop V _f minus voltage (V _CC −
V _f ) becomes a sine wave biased by a voltage obtained by dividing V _f ) by the resistance R ₁ and the resistance r of the coil. When this input signal passes through the capacitor C ₁ , the bias component at the input terminal A ₃ is removed, and after passing through the low pass filter, the resistors R ₆ and R
It is biased by a predetermined voltage by ₇ and input to the negative input terminal of the comparator 1.

In this case, since the reference voltage is applied to the plus input terminal of the comparator 1, if the input voltage of the minus input terminal becomes higher than the reference voltage, the output of the output terminal of the comparator 1 becomes 0v. If the input voltage becomes lower than the reference voltage, the output of the output terminal becomes V _CC, and a rectangular wave pulse corresponding to the input waveform is output. In order to stably output the signal detected by the power generation sensor, the comparator 1 is provided with a hysteresis characteristic by the feedback resistor R ₅₀ . The square wave pulse output in this way is
As described in the conventional example, the meter is then input to the meter driver, and the meter is driven by the driver.

On the other hand, at the input terminal A ₃ of this input circuit,
As shown in the figure, when a pulse sensor using switching of the transistor T _R is connected, the transistor T
_Since the collector of _R is directly connected to the input terminal of the input circuit, when the base input of the transistor is Low, the transistor T _R is off and the voltage at the input terminal A ₃ is the constant voltage V _CC.
A voltage obtained by subtracting the forward voltage drop V _f of the diodes from (V _CC -V _f). Further, when the base input is high, the transistor is turned on and the voltage at the input end becomes approximately 0v. This rectangular wave pulse has a direct current component removed when it passes through the capacitor C ₁ , becomes an integral waveform through a low-pass filter, and is biased at a constant voltage by the resistors R ₆ and R _{7 so} that Input to the minus input terminal. This input waveform is compared with the reference voltage, and if it is larger than the reference voltage, the output of the comparator 1 is 0v, and if it is smaller than the reference voltage, the output of the comparator 1 is V _CC , and the input terminal of the input circuit. A rectangular wave pulse corresponding to the rectangular wave pulse of A ₃ is output.

[0019]

As described above, according to the present invention,
Even if the sensor output format of the electric rotation measuring instrument is different, the input circuit of the meter assembly that receives this output signal can be handled by a single circuit, so the meter assembly can be standardized, cost can be reduced, and the assembly can be done. Will also be easier.

[Brief description of drawings]

FIG. 1 is an input circuit of a meter assembly of an electric rotation measuring instrument according to an embodiment of the present invention.

FIG. 2 is an input circuit of a pulse type meter assembly in which the output format of the sensor is a transistor in a conventional electric rotation measuring instrument.

FIG. 3 is an input circuit of a sine wave meter assembly in which the output format of a sensor is a power generation type in a conventional electric rotation measuring instrument.

[Explanation of symbols]

1 Comparator D ₁ diode

Claims (1)

(57) [Scope of utility model registration request] 1. An input circuit of a meter assembly of an electric rotation measuring instrument, which receives a signal from a sensor for detecting the rotation of a portion to be measured, outputs a rectangular wave pulse by comparison with a reference voltage and sends it to a meter driving portion. The input terminal of the input circuit is connected to a constant voltage power source through a series circuit of a resistor and a diode, and is also connected to one input terminal of a comparator through a series circuit of a capacitor and a low-pass filter, and the input terminal Is biased by a bias circuit, and a reference voltage is applied to the other input terminal of the comparator, which is an input circuit of a meter assembly of an electric rotation measuring instrument.