JPH06230037A - Cross coil drive circuit - Google Patents

Abstract

PURPOSE:To perform correct display regardless of the environment by providing a cross coil drive IC to receive an output signal from a signal processing means and output a signal corresponding to each source gage signal to a cross coil. CONSTITUTION:Signals on vehicle side are input in types of frequency pulse or duty signal, input type of direct current voltage or resistance, or multiplex communication serial signal type. Against these signals, respective interfaces I/F are provided, and the input ports of a CPU 1 are provided with an A/D converter, UART as I/F of asynchronous system, or the like, so as to suitably deal with them in response to the sorts of signals. As for the output side of the CPU 1, the gage signals are output to cross coil drive IC 2 as change of frequency by real time output RTO or pulse width modulation PWM function. In this way, display by a cross coil which can be performed only in a limited indication up to the present, can be more correctly performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having a rotary pointer and a driving method of the pointer driving an analog gauge by a cross coil.

[0002]

2. Description of the Related Art Conventionally, an analog gauge (or an analog meter) using a crossing coil is used for a vehicle or the like.
An apparatus having a structure as shown in is used. The cross coil originally has a mechanism for converting a linear change of an analog signal into a rotational change for display. The principle is that a DC voltage from a sensor is applied to one drive coil side of the cross coil, and a magnetic field proportional to the strength of the voltage is generated in the drive coil, which is rotated by the magnetic field of the permanent magnet applied to the pointer shaft. The pointer stops at the point where the force is obtained and balances with the force of the other rotation control coil of the cross coil.

Further, recently, in many cases, a pulse signal is used to obtain an electric signal from a transistor or the like for state detection. Since it takes time and effort to convert this into an analog signal, this pulse signal is directly subjected to F / V (frequency / voltage) conversion and si through the I / F (interface).
Inputting to a crossing coil drive IC having a built-in n / cos voltage circuit and outputting to a crossing coil are performed. Therefore, the output of this IC can be driven at an angle of 90 ° or more and is used for a wide-angle gauge such as a speedometer.

[0004]

However, the analog gauge has the following problems due to its structure and characteristics. First, in the case of resistance input directly connected to the cross coil or DC voltage drive, it is not possible to display an angle of 90 ° or more (wide angle gauge), and DC signals are sensitive to noise such as vibration. For this reason, a damper and hysteresis are added to slow down the response, which prevents quick display. Secondly, in the case of a crossing coil driving IC that handles pulse signals, a low level signal, that is, when the frequency of pulses is reduced, the responsiveness decreases and the gauge pointer fluctuates greatly. There is a problem that it will end up. Thirdly, recently, it has been considered that various signals are serially transmitted by one signal line, and there is a problem that such a form of signal cannot be supported by the analog gauge as it is.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the structure of the present invention is directed to a sensor, a communication module or the like in a cross coil drive circuit for sending a gauge signal to a rotary pointer type analog gauge having a cross coil. A plurality of I / s that receive a plurality of source gauge signals from the quantity generation unit and send them to the CPU
F, and a signal output means for processing the plurality of source gauge signals and a signal output means for sending an appropriate signal from the calculated signals to a plurality of cross coil drive ICs.
And a cross coil driving IC directly connected to the cross coil, which receives the output signal from the signal processing unit and outputs signals corresponding to the source gauge signals to the cross coil. Is characterized by.

[0006]

The gage signal from the sensor or the like enters the CPU via the I / F and is normalized by removing noise or correction by the signal processing means, and RTO (real time output) or PWM (pulse width). A pulse signal is output to the cross coil drive IC by the modulation function. When the source signal is serial, the input unit of the CPU or the I / F at the previous stage is equipped with a UART (I / F of start-stop synchronization method), etc., and each sensor signal is distributed to each port by time-division processing to reduce noise. Processing etc. are performed. When the source gauge signal is an analog signal, it is digitized by a CPU provided with an A / D converter, and similarly, signal normalization and the like are performed. The source gauge signal refers to an input signal from the vehicle, which corresponds to the analog gauge and is input to the CPU via the interface.

[0007]

Since the CPU properly processes a plurality of signals, accurate display is possible regardless of the environment. In particular, in the case of a type that is driven by a pulse frequency like a speedometer, the non-uniformity of the pointer in the low signal portion can be eliminated, and the response can be improved by moving the speed of the pointer according to the situation. The serial data can be dealt with without any problem, and the wiring can be simplified. In addition, it can be applied to wide-angle gauges that are easy to see, as the rotation angle can be given as much as necessary,
More accurate display is possible.

[0008]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a block diagram showing the case where the present invention is applied to a meter of a vehicle. However, FIG. 1 is written including all main components. That is, a, b, and
Each of c indicates that the type of signal on the vehicle side is different, a is input by a frequency pulse or duty signal, b is a DC voltage or resistance input type, and c is a multiplex communication serial signal type. Each I against them
There is an / F, and there is an A / D converter, a UART, etc. so that the input port of the CPU can perform appropriate processing according to the type of signal. Then, the gauge signal is output to the cross coil drive IC as a frequency change by the RTO or PWM function on the output side of the CPU. The cross-coil drive IC is a well-known technique, and therefore its explanation is omitted. It should be noted that the CPU may be one having as many input ports as necessary for input signals, and it is not always necessary to have all the various input ports.

FIG. 2 shows an example of a program for performing signal processing for one port in this configuration. Figure 2
The data input to the CPU is constantly processed according to the flowchart shown in FIG. In step 20, a noise component is removed from the gauge signal coming to the input port through a filter, and in step 22, the signal output value corresponding to the input signal is determined. The signal value is compared with the previous value, and if it is the same, nothing is done, and if it is changed, the new signal output value is set to the value corresponding to the pulse signal and set in the RAM (step 26). To update. The output determines the pulse width based on this RAM value. In the case of RTO, set the RAM value to the register value, and when the counter reaches the register value,
As in (b), an interrupt signal is generated, the output is inverted, and the RAM value which is a new display value is set in the register value (step 30), and the next inversion counting is continued. In PWM, the pulse width is also changed according to the data value in a substantially similar flowchart. The crossing coil drive IC controls the energization of the crossing coil so as to show a correct gauge value by this pulse signal.

In a speedometer or a tachometer inputting with a frequency pulse, the pulse signal has been intermittent at a low speed and the signal output is unstable and the display is inaccurate. A stable low-speed signal can be output by adding the possible offset frequency, and the pointer can be displayed accurately. The resistance input or the DC voltage input directly connected to the cross coil can be displayed on the wide-angle gauge like a speedometer by using the cross coil driving IC, and more accurate display can be performed. Further, it is possible to suppress fluctuations and improve responsiveness by averaging processing or the like. For serial data from multiplex communication modules, serial I / F such as UART or USRT (character synchronization method) is used to classify any type of serial data by program and remove noise to distribute to each output port. You can Moreover, since only one data line is required, the wiring can be omitted.

As described above, by using the conventional cross coil driving IC as it is and normalizing the input signal by the CPU, the display by the cross coil, which has been limited to the display up to now, is highly reliable. It was possible to display more accurately and arbitrarily within the range desired by the designer.

[Brief description of drawings]

FIG. 1 is a block diagram of a vehicle-mounted analog meter drive circuit to which the present invention is applied.

FIG. 2 is a flow chart diagram for one input of the CPU of FIG.

FIG. 3 is a block diagram of a conventional analog meter drive circuit.

[Explanation of symbols]

 1 ... CPU 2 ... Crossing coil drive IC 3 ... Crossing coil

Claims (1)

[Claims] 1. A cross coil drive circuit for sending a gauge signal to a rotary pointer type analog gauge having a cross coil, wherein a plurality of source gauge signals from an instruction amount generator such as a sensor or a communication module are received and sent to a CPU. Of the above, a signal calculation means for processing the plurality of source gauge signals, and a signal output means for sending an appropriate signal from the calculated signals to a plurality of predetermined cross coil drive ICs.
A cross comprising: a signal processing unit including U; and a plurality of cross coil driving ICs that receive output signals from the signal processing unit and output signals corresponding to the source gauge signals to the cross coil. Coil drive circuit.