JPH0623773B2 - Analog indicator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an analog indicator that indicates a measured quantity by displacement of a pointer.

[Prior art]

Conventionally, as an analog indicator of this type, as disclosed in, for example, Japanese Utility Model Laid-Open No. 56-84751, the indicator axis of a pointer is connected to a drive unit via a bearing provided in a part of the instrument body. Connected, comparing the DC voltage according to the measured quantity with the triangular wave to generate an output pulse with a duty ratio corresponding to the DC voltage, and generating an intermittent driving force from the drive unit in response to the output pulse. , The indicator shaft is slightly vibrated by the intermittent driving force from the drive unit, is smoothly rotated against the contact frictional force with the bearing, and the indication of the analog amount by the pointer is hysteresis. There are things that I tried to do without.

[Problems to be solved by the invention]

However, in such a configuration, since the change range of the measured amount is wide from a small value to a large value, when the measured amount is small, the generation interval of the output pulse is wide and the microvibration causes the needle deflection of the needle. On the other hand, when the quantity to be measured is large, there is a problem that the generation interval of the output pulse is narrow and the driving unit cannot finely vibrate the pointing shaft, thereby increasing the pointing hysteresis of the pointer.

In order to cope with such a situation, the present invention provides an analog indicator in which the pointer is accurately and stably displaced in accordance with the measured amount, and the reference position is accurately indicated when the measured amount is zero. Is what you are trying to do.

[Means for solving problems]

In solving such problems, the structural features of the present invention are as follows.
In an analog indicator equipped with an instrument main body consisting of a pointer that indicates the measured quantity by the amount of displacement from the reference position and a drive unit that displaces the pointer from the reference position by an amount proportional to the driving current that flows, the measured quantity A first drive control means for intermittently flowing a drive current of a predetermined high duty ratio having a peak value proportional to the drive section, and a predetermined low duty ratio having a peak value of a predetermined magnitude. Second drive control means for intermittently supplying a drive current to the drive part and second drive control means for controlling the second drive control means to drive the drive part when the measured amount is close to zero. There is a prohibition means for prohibiting the flow of an electric current.

[Action effect]

In the present invention configured as described above, since the first drive control means intermittently supplies a drive current having a predetermined high duty ratio having a peak value of a magnitude proportional to the measured amount to the drive portion, The part displaces the pointer from the reference position by an amount proportional to the measured amount while slightly vibrating the pointer. in this case,
Even if the measured amount is large, the first drive control unit always keeps the time interval of the drive current flowing through the drive unit constant, so that the drive unit can surely vibrate the pointer. Further, when the measured amount is small, the drive control unit shown in FIG. 2 has a predetermined crest value having a predetermined magnitude at a constant time interval in addition to a small amount of drive current by the first drive control unit. Since the driving current having a low duty ratio is passed through the driving unit, the driving unit can surely slightly vibrate the pointer by the both currents. As a result, regardless of whether the measured quantity is large or small, the pointer stably and accurately indicates the measured quantity by its displacement amount without causing hysteresis.

Further, when the measured amount becomes almost zero, the inhibiting means controls the second drive control means so that the drive current does not flow to the drive section. Therefore, in this case, a small force for displacing the pointer by the second drive control means from the reference position is also removed, and the pointer can be accurately moved to the reference position even if there is a frictional force such as the bearing of the pointer. Can be returned to.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
The figure shows an example in which the present invention is applied to a moving coil type speedometer, and this speedometer includes an instrument body M and a speed sensor 10 which are connected to a DC power source B via an ignition switch IG of the vehicle. ing. The speed sensor 10 includes a permanent magnet 12 connected to an output shaft of a transmission (not shown) via a speedometer cable 11 of the vehicle.
And a reed switch 13 arranged so as to have a magnetic relationship with the permanent magnet 12, and a resistor 14 connected in series with the reed switch 13. Then, the speed sensor 10 is activated by receiving the power supply voltage from the DC power supply B to the resistor 14 by closing the ignition switch IG of the vehicle, and repeatedly detects the rotational position of the permanent magnet 12 by the opening / closing operation of the reed switch 13. Then
Each of these detection results is generated as a series of pulse signals having a frequency proportional to the traveling speed of the vehicle.

As shown in FIGS. 1 to 3, the instrument body M has a pointer P.
And a movable coil drive unit M connected to a support shaft P1 of a pointer P which is rotatably supported by a bearing Br provided in a part of the instrument main body M.
The moving coil drive unit MC of the instrument main body M has an ignition switch I at one input terminal thereof.
It is connected to the DC power source B via G and is grounded via the constant current circuits 80 and 90 described later at the other side input terminal.

The buffer circuit 20 sequentially shapes the waveform of each pulse signal from the speed sensor 10 to generate a shaped pulse. Frequency-
The voltage converter 30 (hereinafter referred to as the FV converter 30) is
The frequency of the shaped pulse from the buffer circuit 20 is converted into an analog voltage proportional to this. Constant voltage generation circuit 40
Receives a power supply voltage from the DC power supply B through the ignition switch IG and generates a constant voltage. The sawtooth wave generation circuit 50 generates a sawtooth wave signal at a predetermined frequency (for example, about 100 Hz). As shown in FIGS. 1 and 4, the window comparator 60 includes a voltage divider 61 connected to the constant voltage circuit 40, the voltage divider 61 and the sawtooth tooth generator 5.
The voltage divider 61 includes a pair of comparators 62 and 63 connected to 0, and resistors 61a and
The constant voltage from the constant voltage circuit 40 is divided by 61b and 61c, and the divided voltage VL is obtained from the common terminal of the resistors 61a and 61b.
And the divided voltage VU is generated from the common terminal of both resistors 61b and 61c. In such a case, both divided voltage V
The resistance values of the resistors 61a, 61b, 61c are determined so that the difference between U and VL corresponds to 5% of the full width of the rising level of the sawtooth wave signal in the low level region.

Each comparator 62, 63 has a resistor 62a, 63a and a diode 62b, 63b when the level of each sawtooth signal from the sawtooth generator 50 is between the divided voltages VL and VU from the voltage divider 61. A low level signal is generated from the common cathode terminal of both diodes 62b and 63b through (see FIG. 4) to control the transistor 81 in the non-conducting state. Further, when the level of each sawtooth wave signal from the sawtooth wave generator 50 is not between the divided voltages VL and VU, the voltage of the common cathode terminal of both diodes 62b and 63b becomes high level and the transistor 81 is turned on. Control to the conductive state. This means that the window comparator 60 responds to each sawtooth wave signal from the sawtooth wave generator 50 at a predetermined low duty ratio (5%) in relation to the low level region of each sawtooth wave signal. This means controlling 81 to be in a non-conductive state.

As shown in FIGS. 1 and 5, the window comparator 70 includes a voltage divider 71 connected to the constant voltage circuit 40, and a pair of comparators 72, 73 connected to the voltage divider 71 and the sawtooth wave generator 50. The voltage divider 71 divides the constant voltage from the constant voltage circuit 40 by the resistors 71a, 71b, 71c connected in series with each other to divide the resistors 71a, 7b.
The divided voltage V ₁ is generated from the common terminal of 1b, and the divided voltage Vu is generated from the common terminal of both resistors 71b and 71c. In this case, bisection voltage Vu, V _l differences each so as to correspond to the full width 75% of the elevated level resistance in the region other than the low areas of elevated levels of the respective saw-tooth wave signal between 71
The resistance values of a, 71b, 71c are defined. Therefore, Vu> _Vl >VU> VL is established.

When the level of each sawtooth wave signal from the sawtooth wave generator 50 is between the two divided voltages V ₁ and Vu from the voltage divider 71, each comparator 72, 73 has each resistor 72a, 73a and each diode 72b, A low level signal is generated from the common cathode terminal of both diodes 72b and 73b through 73b (see FIG. 5) to control the transistor 91 in the non-conducting state. This means that the window comparator 70 responds to the respective sawtooth wave signals from the sawtooth wave generator 50 in relation to the regions other than the low level region of the respective sawtooth wave signals, and the predetermined high duty ratio (75%). Means controlling the transistor 91 in a non-conducting state.

The constant current circuit 80 includes a transistor 81 and a series resistor 8
2, 83, a comparator 84 and both transistors 85,
The transistor 81 has a base 86, and the base of the transistor 81 includes both diodes 62b and 63 of the window comparator 60.
It is connected to the common cathode terminal of b (see FIGS. 1 and 4). Therefore, the transistor 81 is intermittently controlled to be in a non-conductive state at a predetermined low duty ratio in response to each low level signal from the window comparator 60.
In addition, the constant current circuit 80 receives a constant voltage from the constant voltage circuit 40 at both series resistors 82 and 83, and under the intermittent non-conduction state of the transistor 81, the emitter of the transistor 85 and both resistors 82 and 83. Both transistors 85 and 86 are intermittently turned on so that the common connection terminal of 83 has the same potential. This means that the intermittent current flowing into the instrument main body M under the intermittent conduction of both the transistors 85 and 86 is
As indicated by symbol a in the figure, it means that the pulse width is defined by the predetermined low duty ratio based on a constant value.

As shown in FIG. 1, the constant current circuit 90 includes a transistor 91, a comparator 92 and both transistors 93 and 94.
The transistor 91 has its base connected to the common cathode terminal of both diodes 72b and 73b of the window comparator 70 (see FIG. 5). Then, the transistor 91 becomes the unwind comparator 7.
In response to a low level signal from 0, the non-conductive state is intermittently controlled at the predetermined high duty ratio. The constant current circuit 90 receives the analog voltage from the FV converter at the non-inverting input terminal of the comparator 92, and under the intermittent non-conduction state of the transistor 91, the emitter of the transistor 93 and the comparator 92. The non-inverting input terminal of
Both transistors 93 and 94 are intermittently turned on so that they have the same potential. This means that both transistors 93, 9
The intermittent current flowing into the meter main body M under the intermittent conduction of 4 is defined by the predetermined high duty ratio based on the peak value proportional to the analog voltage, as indicated by the symbol b in FIG. Means that.

Further, the constant current circuit 80 is provided with a transistor 87, and the comparison circuit 100 is connected between the FV converter 30, the constant voltage circuit 40, and the constant current circuit 80.
The comparison circuit 100 includes a voltage divider 1 connected to the constant voltage circuit 40.
01 and a comparator 102 connected to the voltage divider 101 and the FV converter 30.
Is generated from the common connection terminal of both series resistors 101a and 101b by dividing the constant voltage from the constant voltage circuit 40 by the series resistors 101a and 101b. In such a case, the resistance values of both series resistors 101a and 101b are determined so that the divided voltage from the voltage divider 101 corresponds to a predetermined value speed (for example, about 0.5 km / h) of the vehicle.

The comparator 102 generates a high level new (or low level signal) when the analog voltage from the FV converter 30 is lower (or higher) than the divided voltage from the voltage divider 101. The transistor 87 becomes conductive (or non-conductive) in response to the high level signal (or low level signal) from the comparator 102. This means that the transistor 87
However, in response to the conduction (or non-conduction), the conduction of both transistors 85 and 86 is prohibited (or permitted) regardless of the action of the transistor 81.

In the present embodiment configured as described above, when the vehicle is in a traveling state with the ignition switch IG closed, a series of pulse signals is generated from the reed switch 13 of the speed sensor 10. Then, the buffer circuit 20 sequentially responds to each pulse signal from the reed switch 13 to generate a shaping pulse, and responds to each shaping pulse by F-V.
The converter 30 produces an analog voltage.

First, a case where the vehicle is traveling at a speed higher than a predetermined low speed (for example, 0.5 km / h) will be described. In this case, since the output voltage of the FV converter 30 is high, the comparison circuit 100 outputs a low level signal and the transistor 87 is kept in a non-conductive state. Further, the window comparator 60 relates to the predetermined low duty ratio based on both the divided voltages VL and VU from the voltage divider 61 in relation to the low level region of each sawtooth wave signal from the sawtooth wave generator 50. At, a low level signal is generated to intermittently control the transistor 81 of the constant current circuit 80 to the non-conducting state. On the other hand, the window comparator 70 outputs the voltage of the sawtooth wave signal from the sawtooth wave generator 50 to both the driving and penalizing voltages V _l and Vu from the voltage divider 71 in relation to the region other than the low region of the level. A low level signal is generated at a predetermined high duty ratio to intermittently control the transistor 91 of the constant current circuit 90 to be in a non-conductive state.

Then, under the action of the constant current circuit 80 based on the intermittent non-conduction of the transistor 81 as described above, the current a (the sixth
(See the figure) intermittently flows into the meter main body M at a predetermined low duty ratio with a predetermined crest value determined in relation to the voltage of the common connection terminal of both resistors 82 and 83, and this intermittent current a Under different phases, the current b (see FIG. 6) has a peak value proportional to the analog voltage under the action of the current-stop circuit 90 based on the intermittent conduction of the transistor 91 as described above. It intermittently flows into the instrument main body M at the predetermined high duty ratio.

In this way, when the intermittent currents a and b alternately flow into the meter body M with different phases, the moving coil drive section MC of the meter body M alternately receives the intermittent currents a and b. Intermittent driving force is generated, and the support shaft P1 of the pointer P receives the intermittent driving force and vibrates slightly, and smoothly rotates against the contact frictional force with the bearing Br, so that the pointer P moves. Support shaft P1
The vehicle speed (corresponding to the frequency of each pulse voltage) of the vehicle is instructed while slightly vibrating in accordance with the slight vibration. In such a case, as the traveling speed of the vehicle, that is, the higher the analog voltage, the total average current flowing into the moving coil drive unit MC is the average value of the intermittent current a (see La in FIG. 7).
And the average value of the intermittent current b increases as indicated by the reference symbol Ls (see FIG. 7) in accordance with the increase in the traveling speed, so that it is proportional to the traveling speed of the vehicle, that is, the total average current Ls. The pointer P can be swung. Further, when the traveling speed of the vehicle is low, the peak value of the intermittent current b becomes small, but the intermittent current a is maintained at the duty ratio with a constant peak value. On the other hand, when the traveling speed of the vehicle is high, the slight vibration of the pointer P can be reliably ensured by the duty ratios of the both intermittent currents a and b. Therefore, over the wide range of the traveling speed of the vehicle, it is possible to always give a correct instruction without causing an undesired needle shaking phenomenon or hysteresis phenomenon under the accurate slight vibration of the pointer P. Further, since the slight vibration of the pointer P is specified by the predetermined low duty ratio and the predetermined high duty ratio that are irrelevant to the traveling speed of the vehicle, the pointer P is caused by the resonance frequency of the moving coil drive unit MC. No resonance phenomenon occurs, and the meter body M in the low traveling speed range
The scale of can be equalized.

Next, when the vehicle is almost stopped, that is, the traveling speed of the vehicle is lower than a predetermined low speed (for example, 0.5 km).
/ H or less) will be described. In this case, since the analog voltage from the FV converter 30 is lower than the divided voltage from the voltage divider 101, the comparator 102 generates a high level signal, and in response to this, the transistor 87 becomes conductive and both transistors 85 and 86. Is prohibited. Further, at this time, in the constant current circuit 90, since the analog voltage from the FV converter 30 is low, the peak value of the intermittent current b is maintained at a very low level, so that it flows into the meter body M. The current is almost zero. As a result, at a traveling speed of 0.5 km / h or less of the vehicle, even if a slight frictional force acts between the pointer P and the bearing Br, the pointer P moves the moving coil drive unit M.
Since the pointer P is not driven by C and the pointer P is not slightly vibrated and the traveling speed is almost zero, the pointer P can be correctly recognized without causing any discomfort.

In addition, in the said Example, although the example to which this invention was applied to the moving coil type speedometer was demonstrated, it may replace with this and may implement even if this invention is applied to various moving coil type analog indicators. Good. The present invention may be applied to various types of analog indicators, not limited to the moving coil type.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of the instrument main body in FIG. 1, FIG. 3 is a partially cutaway front view thereof, and FIGS. 6 is a detailed circuit diagram of each window comparator in FIG. 6, FIG. 6 is a time chart of the intermittent current flowing into the meter main body in FIG. 1, and FIG. 7 is a relationship between the traveling speed of the vehicle and the total average current to the meter main body. It is a graph which shows. Explanation of code 10 ... Speed sensor, 30 ... FV converter, 50 ...
Sawtooth wave generator, 60, 70 ... Wind comparator, 80, 90 ... Constant current circuit, M ... Instrument main body, P ...
... pointer, MC ... coil drive section.

Claims (1)

[Claims] 1. An analog indicator provided with a meter main body comprising a pointer for indicating a measured amount according to a displacement amount from a reference position and a drive section for displacing the pointer from the reference position by an amount proportional to a flowing drive current. A first drive control means for intermittently flowing a drive current having a predetermined high duty ratio having a peak value proportional to the measured amount to the drive section, and having a peak value of a predetermined magnitude. Second drive control means for intermittently supplying a drive current of a predetermined low duty ratio to the drive part, and second drive control means for controlling the second drive control means when the measured amount is close to zero. An analog indicator, wherein the drive control means is provided with a prohibiting means for prohibiting a drive current from flowing to the drive section.