JPH0561565B2 - - Google Patents

Description

[Detailed description of the invention]

[Purpose of the invention] (Industrial application field) This invention relates to an instrument drive device used in a vehicle instrument, etc., and in particular, the present invention relates to an instrument drive device used for a vehicle instrument, etc., and in particular, the invention relates to an instrument drive device used for a vehicle instrument, etc., and in particular, a system that instructs necessary information on the surface of an instrument panel by controlling the rotation of a DC motor. This is related to the improvement of technology to achieve this goal. (Prior art) Among vehicle instruments, the ones that move the indicated value linearly according to the movement of the motor are generally rotary type, eddy current type, moving coil type, and crossed coil type meters. There is insufficient torque. Therefore, for example, as a linear display speedometer,
Conventionally, as shown in FIG. 4, the motor 2 is generally controlled by operating a motor control circuit 9 based on signals from the speed detection sensor 4 and the position detection sensor 3. In the figure, 1 is a belt-driven display mechanism connected to the motor 2, and 10 is a speed display board on which a pointer 1a provided on the display mechanism 1 forms an index. An example of the motor control circuit 9 is a linear servo system shown in FIG. 5, for example. In this method, a pulse signal obtained by the sensor 4 is converted into a voltage signal that changes linearly by a voltage conversion circuit 7, and is inputted to one input terminal of a DC operational amplifier 5. On the other hand, the position detection sensor 3 is a potentiometer, for example, that directly detects the rotational phase of the motor 2 or detects the phase according to the movement of the display mechanism 1.
The output of the differential amplifier 5 is inputted to the other input terminal of the differential amplifier 5 through the voltage conversion circuit 8. Then, the differential amplifier 5 has an output state corresponding to the difference between the two inputs, and outputs the output from this to the motor 2 through the linear bridge driver circuit 6, thereby driving the motor 2 to rotate. The motor 2 performs normal rotation, reverse rotation, and stop depending on the input difference, and displays a predetermined speed on the instrument panel 10 through the display mechanism 1. Further, as an alternative to such a linear servo method, there is a digital servo method. As shown in FIG. 6, in this system, a pulse signal obtained by a speed sensor 4 is processed by a conversion circuit 11, and inputted to a command circuit 12 composed of a CPU or the like, and the signal is processed. A position command signal is inputted to one input terminal of the digital motor control circuit 13 by using the following command. On the other hand, a signal indicating the display position is taken out from a position detection sensor 3 consisting of a digital potentiometer or the like via the motor 2 or the display mechanism 1, and this output is input to the other input terminal of the digital motor control circuit 13. The control circuit 13 is controlled by these two signals.
outputs a rotation control signal to the motor 2 according to the position command signal of the command circuit 12, and controls the motor 2 according to the position command signal of the command circuit 12.
By the rotation of , a predetermined speed is displayed on the instrument panel 10 via the display mechanism 1. (Problem to be solved by the invention) However, in the former linear servo system,
When the input voltage from the speed sensor and the feedback voltage from the position detection sensor become close to each other, the differential output becomes small, resulting in a lack of motor torque. Therefore, it was necessary to increase the torque of the motor and increase the gain of the differential amplifier. Further, in the latter digital servo method, the detection accuracy is improved because of digital control, but the cost of the position detection sensor and the control circuit is too high, and it is economically disadvantageous. This invention was made to solve the above problems, and by turning the motor ON and OFF, the torque generated by the motor can be fully utilized, the control circuit is simplified, and the cost is reduced. The purpose of the present invention is to provide a motor control circuit for an instrument that can be manufactured at low cost. [Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, the present invention includes a detection sensor, a position detection sensor that detects the rotational position of a motor, and a signal from the position detection sensor. A voltage conversion circuit that inputs and outputs two systems of signals with a slight potential difference, a comparison circuit and an inversion comparison circuit that connect the signals from the detection sensor and the respective signals from the voltage conversion circuit to their input terminals, The motor bridge drive circuit is provided with a motor bridge drive circuit that receives outputs from the comparison circuit and the inversion comparison circuit, and rotates the motor in forward or reverse directions or stops the motor depending on the output states of both. (Function) As shown in FIG. 1, the pulse signal obtained by the detection sensor 400 is changed into a linearly changing voltage signal by the voltage conversion circuit, and this signal is transmitted to the comparison circuit 500 and the inversion comparison circuit 600. input to one input end of the . On the other hand, a signal indicating the display position is transmitted directly or indirectly to the position detection sensor 300 via the motor 200 or the display mechanism 100.
This signal is taken out by the voltage conversion circuit 900 as two outputs with a slight potential difference, and is input to the other side input terminals of the comparison circuit 500 and the inversion comparison circuit 600. and,
The output from this will be sent to the motor bridge driver circuit 7.
By inputting 00, the motor 200 rotates forward, reverse, and stops, and a predetermined display is displayed on the instrument panel 110 via the display mechanism 100. (Example) Hereinafter, an example of the present invention will be described in detail using the drawings. In FIG. 2, this motor control circuit includes a speed detection sensor 400, an F/V conversion circuit 800 that inputs a pulse signal from the speed detection sensor and converts it into a voltage change, and a display mechanism 100.
Potentiometer 3 to detect display position via
00, and a voltage conversion circuit 900 that inputs the signal from this potentiometer 300 and outputs two systems of signals with a slight potential difference, and the F/V
Comparison circuit 500 and inverting comparison circuit 60 receiving outputs from conversion circuit 800 and voltage conversion circuit 900
0, and a motor bridge drive circuit 700 which receives outputs from the comparator circuit 500 and the invert comparator circuit 600 and rotates and stops the motor in accordance with the output states of both. The display mechanism 100 includes a rotor 102 rotatably connected at one end to a motor 200 via a reduction gear group 101, and a pin 104 that slides into a spiral cam lead groove transformed into the rotor 102.
It also consists of a slider 103 that slides along a slider shaft 105, and a pointer 106 that slides together with the slider 103 and indicates an index formed on an instrument panel 110. A reduction gear group 1 is provided on the other end side of the rotor 102.
07 to the input shaft of the potentiometer 300, and rotates the potentiometer 300, thereby changing the resistance RP. One end of resistor RP is the power supply
Vcc, and the other end is connected to the voltage conversion circuit 900.
It is connected to the ground side through the resistor RE provided inside the , and the contact is also connected to the resistor of the voltage conversion circuit 900.
Connected to RA and RC. The voltage conversion circuit 900 includes resistors RA-RB,
It consists of two systems of DC circuits, RC and RD, and the voltages of the two systems with a slight potential difference created by voltage division are fed back into the comparison circuit 500 and the inversion comparison circuit 600. That is, the DC circuit has the following relationship. RB/RA+RB>RD/RC+RD However, it is necessary that RP+RE<<RA+RB, RC+RD in order to obtain linear feedback input. In addition, contrary to the above, it is the same even if RB/RA+RB<RD/RC+RD, and in this case, the motor 20
0 just rotates in the opposite direction. The comparison circuit 500 and the inversion comparison circuit 600
are comparator circuits A, both consisting of comparator ICs,
The inverting comparator 600 inverts the input by connecting the converter C to the output terminal of the comparator circuit B. In addition, even when the signal of the speed detection sensor 400 is "0", that is, when the speed is "0", in order to establish the potential difference expressed by the following formula: ERB/RA+RB>ERD/RC+RD, the voltage between the contact and the ground must be E must not be 0. Therefore, by connecting the resistor RE in series with the potentiometer, the voltage E does not become 0 even when the potentiometer becomes 0Ω. Similarly, the voltage of the output of the F/V conversion circuit 800 when the speed is “0” must not be “0”, and naturally the F/V conversion circuit 800 from the speed “0” to the maximum speed and the voltage change of the voltage conversion circuit 900 are both in the same state. Next, the principle of forward rotation, reverse rotation, and stopping of the motor by the bridge driver circuit 700 will be explained. First, the operation of the motor with respect to the input/output to the bridge driver circuit 700 is as shown in Table 1 below.

[Table] In other words, the inputs to the bridge driver circuit 700 are the output E of the F/V conversion circuit 800, the output Ea (input voltage to the comparison circuit A side) of the voltage conversion circuit 900, and Eb (input voltage to the comparison circuit B side). The comparator circuit B is provided with a converter C so that when there is a difference in the voltages (input voltages), the voltage is always H, L or L, H. Since there is a slight potential difference between the output voltages Ea and Eb, the output voltage characteristics will be as shown in the graph of Figure 3, and only one comparison circuit will be inverted, so the motor will stop and the display mechanism will also stop. Here, when either voltage changes again, the motor 200 rotates forward or reverse. Note that the converter C may be included in either of the comparison circuits A and B. In the case opposite to the embodiment, only the direction of rotation of the motor 200 is reversed. Table 2 below collectively displays the output of the bridge driver circuit 700 for each input voltage to the comparison circuits A and B, and the motor operation and pointer movement based on the output.

[Table] Although the display mechanism in the embodiment has been described as having a form in which the pointer is displayed by moving it in a straight line, this invention is not limited to this. It is possible to do so. [Effects of the Invention] As explained in detail in the above embodiments, the motor only repeats ON and OFF operations in the forward and reverse directions. In this way, torque can be fully generated without causing a torque shortage, and the motor can be made smaller and the mechanism can be made more compact. Further, according to the present invention, the motor control circuit itself can be simplified and costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a motor control circuit according to the present invention, Fig. 2 is an explanatory diagram showing a specific circuit configuration, Fig. 3 is a graph showing the same output characteristics, and Fig. 4 is a general diagram of a linear type meter. Figure 5 is a block diagram showing the electrical configuration of a conventional linear servo type motor control circuit, and Figure 6 shows the electrical configuration of a conventional digital servo type motor control circuit. It is a block diagram. 100...display mechanism, 200...motor, 30
0...Position detection sensor, 500...Comparison circuit,
600... Inverting comparison circuit, 700... Motor bridge driver circuit, 900... Voltage conversion circuit.

Claims (1)

[Claims] 1 A detection sensor, a position detection sensor that detects the rotational position of the motor, a voltage conversion circuit that inputs the signal from the position detection sensor and outputs two systems of signals with a slight potential difference, and a detection sensor A comparator circuit and an inverting comparator circuit have input terminals connected to the signals from the voltage converter circuit and the signals from the voltage converter circuit, respectively. A motor control circuit for an instrument, comprising a motor bridge drive circuit for forward/reverse rotation and stop.