JP2600361Y2 - Cross coil meter drive - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention has a pair of cross coils and a magnet rotor that are orthogonal to each other, and displays a predetermined measurement amount from the rotation angle by rotating the magnet rotor by a magnetic field generated by the cross coils. The present invention relates to a cross-coil meter driving device.

[0002]

2. Description of the Related Art A cross-coil meter is generally shown in FIG.
It is configured as shown in (a) and (b). In the figure, a cross coil C is constituted by an inner coil C _I and an outer coil C _O arranged orthogonally to each other, and a magnet rotor Mg is rotatably arranged in a magnetic field generated by the cross coil C. A pointer A is attached to the center of the magnet rotor Mg. Reference numeral B denotes a scale plate for displaying the measured amount in cooperation with the pointer A, and for example, a speed display scale of the vehicle is provided as shown in the figure.

In the above-described configuration, a magnetic field is generated by the first and second coils L ₁ and L ₂ by applying a current to the coils. The magnet rotor Mg rotates so that the direction of the composite magnetic field of these magnetic fields matches the direction of the magnetic pole of the magnet rotor Mg.

[0004] The direction of the combined magnetic field is obtained by vectorially combining the respective magnetic fields generated by passing the currents I _I and I _O to the inner coil C _I and the outer coil C _O , and the magnitude of each magnetic field is It is proportional to the value of the current flowing through each of the coils C _I and C _O. Therefore, when a combined vector (synthetic magnetic field) is formed by flowing a current corresponding to a predetermined measurement amount to each of the coils C _I and C _O , the magnet rotor Mg rotates in that direction and the pointer A rotates to a predetermined rotation angle. Then, the pointer A indicates the predetermined measurement amount.

[0005]

The magnetic field H (I) generated by the current I flowing through the coil is as follows: H (I) = kNI (1) where N is the number of turns k is a constant.

Accordingly, as shown in FIG. 2 (A), the to shake angle guidance becomes theta _{1, I} I the inner coil C _I,
Flowing I _O becomes current to the outer coil _{C O, H I (I I} ) = kNI I H O (I O) = kNI O ··· (2) _{However, I I = I sin (θ} 1) I O = I cos (θ ₁ ) (3) Generates magnetic fields H _I (I _I ) and H _O (I _O ).

However, the inner coil C _I and the outer coil C _O
By such that the cross-sectional shape different, different values of the proportionality constant k in equation (2), the magnetic field be flowed to I _I and I _O occurs to the respective coils H _I '(I _I) = k _I NI _I H _O ′ (I _O ) = k _O NI _O (4), and as shown in FIG. 2B, the direction θ ₂ of the vector of the composite magnetic field is θ ₂ = tan ⁻¹ (H _I '(I _I ) / H _O ' (I _O ) = tan ^-1 [(k _I / k _O ) ・ tan θ ₁ ] (5) and an error is generated.

In general, in a cross coil, equation (4)
Since the constants k _I and k _O shown by are k _I > k _O (6), the indication error can be eliminated by reducing the current flowing through the inner coil. A resistor was connected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cross-coil meter driving device which has a small error without adding a resistor.

[0010]

A drive device for a cross-coil meter in which an inner coil and an outer coil are arranged orthogonal to each other, comprising: a first transistor for turning on and off a current flowing from a voltage source to the inner coil; a second transistor turning on and off the current flowing from the pressure source to the outer coil, the input signal is converted into a pulse of duty ratio corresponding to the meter indication value of the first transistor and to the main over data
Bei a driving value converter supplied to the second transistor
The first transistor only has a Darlington connection.
Was .

[0011]

[Function] The current flowing through the inner coil and the outer coil is
One by one transistor and one by second transistor
Is turned on and off, but only the first transistor is
Ton connection.

The on / off signals of the currents flowing through the inner and outer coils are turned on / off by a pulse signal having a duty ratio corresponding to the meter indicated value of the input signal output from the drive value converter.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
In FIG. 1, 1 is a drive value converter, 2 and 3 are duty ratio generators, 4 to 7 are AND circuits, Q _{1 to} Q ₁₀ are transistors, C _I is an inner coil, and C _O is an outer coil.

The memory (not shown) of the drive value converter 1 includes:
Using the input digital value as an address, D _O , S _O ,
D _I and S _I and is recorded, the recording data values corresponding to the input value is read. That is, if the shake of the meter corresponding to the input digital values I _S and I _S is θ, the following relationship holds: I _S = k · θ (7)

Therefore, in the memory at the address of I _S , D _O = | cos θ | D _I = | sin θ | (8), and in S _O and S _I , θ is the first quadrant. When S _O = 1, S _I = 1 θ is in the second quadrant, S _O = 0, and when S _I = 1 θ is in the third quadrant, S _O = 0 and S _I = 0 θ is in the fourth quadrant. when quadrant _{S O = 1, S I =} 0 ··· (9) is recorded.

The duty ratio generators 2 and 3 generate pulses having a duty ratio equal to the values of D _O and D _I output from the drive value converter 1. The AND circuit 4 and 5 and the S _O output from the driving value converter 1 and the output of from duty ratio generator, also the AND circuit 6, and 7
It is taken is and the S _I outputted from the driving value converter 1 and the output of from duty ratio generator 3.

The outputs of the AND circuits 4 to 7 are connected to the second transistor
Is connected to the bases of the transistors Q ₁ to Q ₄ and the transistor _{Q 5, Q 9, Q 7} , Q 10 as a static, if the output of the AND circuit is 1 the transistor in a conductive state, it flows in the case of 0 the current Is turned off. 1st
Transistor Q ₈ as a transistor and Q ₁₀ and Q ₆
And Q ₉ are Darlington connected, and transistor Q
_{When the} transistor ₁₀ is turned on, the transistor Q ₈ is turned on, and when the transistor Q ₉ is turned on, the transistor Q ₆ is also turned on.

Accordingly, the average value I _{O of the} current flowing through the coil C _O is I _O = (V−V _Q1 −V _Q2 ) / R · sin θ or I _O = (V−V _Q3 −V _Q4 ) / R · sin θ ··· (10) However, V _Q1 ~V _Q4 are emitter-collector voltage R when the respective transistor is oN resistance also of the coil C _O, the average value I _I of the current flowing through the coil C _I is I _I = (V−V _Q5 −V _Q6 ) / R · cos θ or I _I = (V−V _Q7 −V _Q8 ) / R · cos θ (11)

Transistors Q _{1 to} Q ₅ and Q ₇ are ON
Voltage V _Q1 between the emitter and the collector of the time became but ~V _Q5 and V _Q7 are the same value, the transistor Q ₆ and Q
Emitter-collector voltage V _Q6 when ₈ turns ON
And V _Q8 are connected to Darlington, so V _Q1
It is larger than V _Q5 and V _Q7 .

Therefore, the current value I expressed by equation (11)
_I is the current value becomes small by the emitter-collector voltage rises by a transistor Q ₆ or Q ₈ are Darlington connected. Therefore, as described in the prior art, the composite vector of the magnetic field generated by both coils is weakened magnetic field of the inner coil H _I shown in FIG. 2 (B), the becomes circular as shown in FIG. 2 (A) The indication error is eliminated.

[0021]

As described above, according to the present invention, the following effects can be obtained. The cross coil is driven by the current turned on and off by the transistor, and only the first transistor, which turns on and off the current flowing in the inner coil, is configured by Darlington connection. The difference in the strength of the magnetic field due to the difference in the shape of the coil can be eliminated, and the indication error of the meter can be eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a magnetic field generated by a cross coil.

FIG. 3 is an explanatory diagram of a cross coil.

[Explanation of symbols]

1 driving value converter 2 duty ratio generator 4-7 AND circuit Q ₁ to Q ₁₀ transistor C _I inner coil C _O outer coil

Claims (1)

(57) [Scope of request for utility model registration] 1. A driving device for a cross-coil meter in which an inner coil and an outer coil are arranged orthogonally to each other, wherein a current flowing from a voltage source to the inner coil is turned on / off .
The turning on and off 1 and the transistor, the current flowing through the outer coil than the voltage source
2 transistor and an input signal is converted into a pulse of duty ratio corresponding to the meter indication value of the first transistor and the ocular over data
A cross-coil meter driving device , comprising: a driving value converter for supplying a second transistor; and only the first transistor is Darlington-connected .