JPH0692984B2 - Drive device for cross coil type instrument - Google Patents

Description

The present invention relates to a drive device for a cross-coil type instrument.

[Problems to be Solved by Prior Art and Invention] Conventionally, the information to be displayed by an instrument of this type has, for example, a form of an analog voltage value generated by changing a resistance value in accordance with a change in liquid amount. Is input, and the deflection angle of the pointer changes with the change of the analog voltage value.

The deflection angle of the pointer is determined by the direction of the combined vector of the magnetic fields generated by the coils by passing a current through a pair of coils arranged in a crossed manner, but in order to change the direction of the combined vector, The ratio of the current flowing through each coil is directly changed by an analog amount from a sensor or the like.

By the way, recently, in a certain type of vehicle, various signal data generated in the vehicle are collectively collected as digital data in a vehicle-mounted computer and processed. Most of the displays are digital.

However, even in a vehicle in which the signal data has been digitally processed in this way, there are many users who desire the display to be performed by an analog instrument according to a pointer. In such a case, it is possible to deal with this by incorporating a circuit system for generating and processing analog signal data for display separately without using digital data for display, but forming existing digital data for display. In addition to the waste of the circuit, the circuit becomes complicated and the cost becomes high.

Therefore, in view of the above-mentioned problems of the conventional device, the present invention provides a drive device for a cross-coil type instrument, which can drive the cross-coil type instrument according to the display information in which the sensor signal has already been processed and becomes digital data. Is what you are trying to do.

[Means for solving problems]

As shown in the basic configuration diagram of FIG. 1, the driving device for the cross-coil type instrument according to the present invention for solving the above-mentioned problems is such that the information displayed by the deflection angle of the pointer of the cross-coil type instrument A is digital data. Data input terminal IN that is input in the form of a line and digital data D ₀ and D _{1 that} are input to the data input terminal IN before and after D ₀ <D ₁ the digital data to be increased by one to the digital data D _1, D _0> the value a at a time digital data when D ₁
The digital data that decreases to D ₁ is the digital data
It is generated as duty determination data that determines the duty of a rectangular wave required to generate a pointer deflection angle obtained by dividing the pointer deflection angle corresponding to D ₀ and D ₁ into a predetermined number.
Duty determination data generating means B for sequentially outputting these at equal intervals during the input cycle of the digital data that follows them.
One of a variable duty rectangular wave generating means C for generating a rectangular wave having a duty corresponding to the duty determining data generated by the duty determining data generating means B, and a rectangular wave generating by the variable duty rectangular wave generating means C. At one level and the driver means D for supplying a current to the other side of the cross coil at the other level.

[Work]

One of the cross coils of the cross coil type instrument A is energized at one level of the rectangular wave generated by the variable duty rectangular wave generating means C, and the other is energized at the other level of the rectangular wave. Since the duty of is determined by a plurality of duty determination data obtained by the digital data which is to be displayed by the indicator deflection angle of the meter A, the display corresponding to the data is input when the digital data is input. The variable duty rectangular wave generating means C generates a rectangular wave having a duty that sequentially increases and decreases in order to perform a predetermined display while changing smoothly.

〔Example〕

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

FIG. 2 is a circuit block diagram of a driving device for a cross-coil type instrument according to the present invention, in which 1 is a central processing unit comprising a microcomputer which receives digital data having information such as liquid amount, temperature and voltage from a data input terminal IN. Device (CP
U), which processes digital data according to a predetermined program and outputs data that determines the duty of a rectangular wave. Reference numeral 2 denotes a variable duty rectangular wave generation circuit that generates a rectangular wave having a duty corresponding to the digital data by the duty determination data that the CPU 1 processes and outputs the digital data. Reference numerals 3a and 3b are cross coils that constitute the cross coil type meter 3 and are arranged orthogonally to each other. One ends of the cross coils 3a and 3b are connected to a + power source. 4a,
Reference numeral 4b denotes a driver that receives a rectangular wave generated by the variable duty rectangular wave generation circuit 2 and causes a current to flow through each of the cross coils 3a and 3b. The outputs of the drivers 4a and 4b are the cross coil 3a and 3b.
It is connected to the other end of 3b. The driver 4a has an amplifier 4a ₁ that non-inverts and amplifies the rectangular wave from the variable duty rectangular wave generating circuit 2 and a switching transistor 4a ₂ that is turned on when the output of the amplifier 4a ₁ is at H level. A current flows through the cross coil 3a while the output of the circuit 2 is at the H level. On the other hand, the driver 4b includes a switching transistor 4b ₂ to turn on when the output of the amplifier 4b ₁ and the amplifier 4b ₁ for inverting amplifying the H level square wave from the variable duty square wave generating circuit 2, a variable duty square wave A current flows through the cross coil 3b while the output of the generation circuit 2 is at the L level.

When the CPU 1 has an 8-bit configuration, digital data is handled in 8-bit units, so that the variable duty rectangular wave generation circuit 2 shown in FIG. 3 is used, for example.

In FIG. 3, 2a is an 8-bit shift register to which 8-bit duty determination data is serially input from the CPU 1, 2b is an 8-bit comparison counter to which a count-up clock is input from a clock generator (not shown), and 2c is Compare the contents of the shift register 2a and the comparison counter 2b,
The output is set to L level while the shift register 2a is larger,
When the comparison counter 2b becomes larger, it operates so as to set the output to the H level, and outputs a rectangular wave having a duty corresponding to the duty determination data.

Now, assuming that the data 03H (hexadecimal) is set in the shift register 2a and the comparison counter 2b is reset,
The magnitude comparator 2c compares the contents of both,
Since the shift register 2a is larger, the L level is output. After that, the counter up pulse is the comparison counter
When it is input to 2b and its content is incremented by 1, the value of the comparison counter 2b becomes 1, but the content of the shift register 2a is still larger, so the output of the magnitude comparator 2c is at L level. However, if the comparison counter 2b continues to count up, the comparison counter 2b
Since the content of 2b becomes larger than the content of the shift register 2a, the output of the magnitude comparator 2c is inverted at that time and becomes H level.

After that, the comparison counter 2b counts up, so
The output of the magnitude comparator 2c keeps H level, but the content of the comparator 2b for comparison is FFH (hexadecimal).
When it rolls over from 00H to 00H, the content of the comparison counter becomes smaller than that of the shift register 2a, so that the output of the magnitude comparator 2c is inverted again to the L level. By repeating the above operation, a rectangular wave with a duty of 3/256 can be continuously obtained. The contents of the shift register 2a are replaced by the duty determination data from the CPU 1 only when the duty is changed, and the value is changed within the range of 1/256 to 256/256 (or 0/256 to 255/256).

Now, it is assumed that the digital data input to the data input terminal IN is data indicating the liquid level for the fuel tank of the vehicle. The data is generated by an A-D converter that performs analog-digital (A-D) conversion of the analog signal generated by the liquid level sensor with a predetermined resolution. If the resolution is, for example, 1/15, the data is 0000,0001, …… 11
It can be represented by a 4-bit binary number like 11, but CPU1 has 8
In the case of the bit configuration, the data represented by using the lower 4 bits of 8 bits is a constant period T in units of 8 bits, for example,
It will be entered every 504 ms.

On the other hand, the deflection angle θ of the pointer of the cross coil type instrument 3 is given by Ia and Ib, which are the currents flowing through the cross coils 3a and 3b, respectively. According to the present invention, the ratio of Ia and Ib is calculated by the ratio of the H level and the L level of the rectangular wave, that is, the duty ratio R _DUTY.
Corresponding to The deflection angle is determined by.

Therefore, as described above, the duty determining data is directly selected by the digital data having the resolution of 1/15 and the rectangular wave having the duty ratio is generated. Therefore, the deflection angle θ of the pointer of the measuring instrument has a span of 90 °. In this case, θ ₀ = 0 °, θ ₁ = 6
It is divided into 15 such as ゜, θ ₂ = 12 °, ..., θ ₁₅ = 90 °,
The duty ratio R _DUTY for each deflection angle is as follows.

_{R DUTY = 0 R DUTY1 = 0.0951} R DUTY2 = 0.1753:: when using R _DUTY14 = 0.9049 R _DUTY15 = 1 variable duty square wave generating circuit 2 of the third, as shown in FIG configuration, a rectangular wave of the duty ratio In order to generate it, the CPU1 needs to output x, which makes x / 256 closest to the above duty ratio, as the duty determination data. For this reason, the CPU1 needs to output the read only memory (ROM).
And has a table for outputting the date determination data x corresponding to the digital data. In the above example, a table of digital data duty determination data x 0000 0 0001 24 0010 45 :: 1110 232 1111 255 may be prepared.

The CPU 1 also determines the duty determination data D ₁ selected by the digital data input at the constant cycle T and the duty determination data selected by the previously input digital data.
The difference with D ₀ is taken, this difference is divided into N, and the value A obtained by this N division
The duty determination data D (1) to D (N) obtained by adding an integer multiple of the above to the duty determination data D ₁ or D ₀ are output at intervals of T / N and are supplied to the variable duty rectangular wave generation circuit 2.

For example, when certain digital data is input at time T _{0 and} duty determination data D ₀ corresponding to this digital data is output at time T ₁ , digital data larger than the previous time is input and corresponds to this digital data. The date determination data is D ₁ and N is 4
Then, as shown in FIG. 4 and FIG.
Time point T ₂ at which digital data will be input next from T ₁
Is divided into four equal parts, and each time point T ₁ + (T ₂ −
_{T 1) / 4, T 1} +2 (T 2 -T 1) / 4, the _{T 1 +3 (T 2 -T 1} ) / 4, D (1) = D 0 + (D 1 -D 0) / 4 , D (2) = D ₀ +2
The duty determination data of (D ₁ −D ₀ ) / 4 and D (3) = D ₀ +3 (D ₁ −D ₀ ) / 4 are output.

With the above configuration, as shown in the flowchart of FIG. 6, the CPU 1 takes in digital data from the data input terminal IN in step S1 and determines whether or not the digital data is different from the data immediately before it. Is determined in step S2. If there is no change in the data and the determination is NO, the procedure returns to step S1 to capture the next digital data. If the determination is YES, the duty determination data D ₁ corresponding to the captured digital data is read from the table in ROM in the next step S3, and this is followed by the duty previously read from the table in ROM in step S4. Decision data D ₀
Then, it is determined whether or not D ₁ > D ₀ .

When the determination in step S4 is YES, the process proceeds to step S5, where (D ₁ −D ₀ ) / 4 = A is obtained. Then step
Proceed to S6, where D (1) = D ₀ + A, D (2) = D ₀ +2
A and D (3) = D ₀ + 3A are obtained. On the other hand, when the determination in step S4 is NO, the process proceeds to step S7, where (D ₀
−D ₁ ) / 4 = A is calculated. After that, the process proceeds to step S8, where D (1) = D ₁ + 3A, D (2) = D ₁ + 2A, D (3) = D ₁
Calculate + A respectively.

After obtaining D (1) to D (3) in step S6 or S8, the process proceeds to step S9, where it is determined whether or not time T / 4 has elapsed. If the determination is NO, T / 4 is Step S until elapsed
Repeat the judgment of 9. When the determination in step S9 is YES, the process proceeds to step S10, where the duty determination data D (1) obtained in step S6 or S8 is transferred to the shift register 2a of the variable duty rectangular wave generation circuit 2.

When the duty determination data is set in the shift register 2a, the comparison counter 2b is reset at the same time,
After that, the output of the magnitude comparator 2c repeatedly outputs a rectangular wave with a constant duty ratio determined by the duty determination data set in the shift register 2a until the duty determination data is changed, and this is applied to the drivers 4a, 4b. To do. Since the drivers 4a and 4b pass currents to the cross coils 3a and 3b at the H and L levels of the rectangular wave, respectively, the direction of the combined vector of the magnetic fields generated by the cross coils 3a and 3b depends on the duty ratio. The pointer of 3 indicates a deflection angle according to digital data.

After that, the time 2T / 4 is elapsed in step S11 and the data D (2) is transferred in step S12, and subsequently the time 3T / 4 is elapsed in step S13 and the data D (3) is transmitted in step S14.
To transfer. After that, after a lapse of time T in step S15, the data D ₁ is transferred in step S16, and the process returns to step S1.

[Effect]

As described above, according to the present invention, since the cross-coil type instrument can perform a predetermined display by the display information input in a digital format, in a device in which digital data has already been prepared for digital display, In addition to the easy analogization of the display, if the microcomputer is equipped for digital data processing, it can be easily implemented by adding a few circuits and changing the program of the microcomputer. can get.

In addition, since the pointer is smoothly driven at intervals at which the pointer deflection angle between the digital data input before and after is divided into a plurality, the pointer does not move abruptly due to changes in the digital data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a device according to the present invention, FIG. 2 is a circuit block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a specific example of a part of FIG. 4 and 5 are explanatory views for explaining the principle of the present invention, and FIG. 6 is a flow chart showing the operation of the central processing unit in FIG. A: Cross coil type instrument, B: Duty determination data generating means, C: Variable duty rectangular wave generating means, D
...... Driver means, IN …… Data input means.

Claims (1)

[Claims] 1. A device for driving a cross-coil type instrument having a pair of cross-coils arranged so as to intersect with each other, and data input in which information displayed by a deflection angle of a pointer of the cross-coil type instrument is input in the form of digital data. Digital data that increases to the digital data D ₁ by a value obtained by dividing the difference between these terminals by a predetermined number when the digital data D ₀ and D ₁ input before and after the data input terminal are D ₀ <D ₁ When D ₀ > D ₁ , the data is reduced by the value A to the digital data D _1, and the digital data is divided into a predetermined number between the needle deflection angles corresponding to the digital data D ₀ and D ₁ , respectively. Duty that is generated as duty determination data that determines the duty of the rectangular wave required to generate the angle, and that is sequentially output at equal intervals during the input cycle of the digital data that follows it. A constant data generating means, a variable duty rectangular wave generating means for generating a rectangular wave having a duty in accordance with the duty determining data generated by the duty determining data generating means, and a rectangular wave generating by the variable duty rectangular wave generating means. A driving device for a cross-coil type instrument, comprising: driver means for supplying a current to one of the cross coils at one level and supplying a current to the other of the cross coils at the other level.