JPH0461307B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an analog indicator.

(Prior Art) Conventionally, in this type of analog indicator, for example, the indicator shaft of the pointer is coaxially connected to the drive unit through a bearing provided in the center of the instrument body, and the spiral hairspring is connected to the support. The hairspring is fitted coaxially to the shaft, and the inner and outer ends of the hairspring are respectively fixed to the intermediate portion of the support shaft and a part of the instrument body, and a DC voltage representing an analog quantity is intermittently applied to the drive section. and generate a driving force from this drive part while changing it intermittently, until this driving force reaches an equilibrium rotation position with the repulsive force of the hairspring,
The support shaft is slightly vibrated by the driving force from the drive unit in response to the intermittent changes, and is smoothly rotated against the contact friction force between the bearing and the guide shaft. There is a device that allows analog quantities to be indicated correctly without hysteresis. In addition, in such an analog indicator, when the driving force becomes equal to or less than the contact frictional force as the analog quantity decreases, the repulsive force of the hairspring also becomes equal to or less than the contact frictional force. It cannot be rotated due to frictional force. Therefore, the pointer is stopped by an appropriate stopper at a rotational position of the support shaft that specifies an analog quantity corresponding to a driving force substantially equal to the contact frictional force, and the contact frictional force of the driving force is This is designed to prevent erroneous instructions from being caused by the guideline due to a drop below.

(Problem to be Solved by the Invention) However, in such a configuration, the pointer vibrates slightly in response to the minute vibrations of its support shaft, so when the pointer approaches the stopper, the pointer vibrates slightly when the pointer approaches the stopper. There was a problem in which the needles interfered with each other, causing a large needle deflection phenomenon, making the indicated value of the pointer unclear and giving the occupants a sense of discomfort.

Therefore, in order to cope with this problem, the present invention attempts to stop the slight vibration of the above-mentioned pointer when the pointer approaches the stopper in an analog pointer.

(Means for Solving the Problem) In solving the problem, the structural features of the present invention include a pointer for indicating an analog quantity, a drive section, and a rotary movement of the drive section via a bearing provided on a stationary member. a support shaft that is coaxially connected to support the pointer so as to rotate integrally therewith; and an intermediate portion of the support shaft and each end portion fixed to a stationary member, respectively; detecting a spiral spring fitted coaxially and the analog quantity;
A detection means that generates a detection signal and a driving force necessary to rotate the support shaft are generated from the drive unit while intermittently changing a duty ratio according to a change in the detection signal. and control means for controlling the drive unit, the drive unit causing the support shaft to vibrate slightly in response to changes in the drive force, while resisting the contact friction force between the support shaft and the bearing. and when the value of the detection signal decreases to a lower limit value corresponding to a driving force approximately equal to the contact friction force, In an analog indicator equipped with a stopper for regulating rotation of a support shaft, a reference signal generating means for generating a value near the lower limit value as a reference signal;
A prohibition means for prohibiting the control of the control means when the value of the detection signal decreases to the value of the reference signal is provided.

(Operation and Effect) By configuring the present invention in this way, when the value of the detection signal decreases to the value of the reference signal and the pointer approaches the stopper,
Since the inhibiting means inhibits the control of the control means and eliminates the driving force from the drive unit, the slight vibration of the pointer stops and a large needle vibration phenomenon of the pointer due to interference with the stopper is eliminated. This prevents the occurrence of such problems, and as a result, the occupants are not given the above-mentioned discomfort.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. The drawings show an example in which the present invention is applied to a moving coil type speedometer, and this speedometer is connected to the ignition of the vehicle. It is equipped with a meter body M and a speed sensor 10 connected to a DC power source B via a switch IG. 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;
The reed switch 13 is arranged to have a magnetic relationship with the permanent magnet 12, and a resistor 14 is connected in series with the reed switch 13. When the ignition switch IG of the vehicle is closed, the speed sensor 10 receives the power supply voltage from the DC power supply B through the resistor 14 and becomes activated, and the rotational position of the permanent magnet 12 is changed by the opening/closing operation of the reed switch 13. The detection results are repeatedly detected as a series of pulse signals having a frequency proportional to the traveling speed of the vehicle.

The meter body M includes a pointer P, a movable coil drive unit coaxially connected to a support shaft of the pointer P via a bearing provided in the center of the meter body M, and a movable coil drive unit coaxially fitted to an intermediate portion of the support shaft. The hairspring is provided with a spiral hairspring whose inner and outer ends are fixed to the intermediate portion of the support shaft and a part of the instrument body M, respectively. In addition, the instrument body M
is provided with a stopper, and this stopper is configured to adjust the traveling speed corresponding to a driving force substantially equal to the contact friction force between the support shaft and the bearing, out of the driving force generated from the movable coil drive unit as described below. The support shaft is fixed at a proper position on the instrument body M at a rotational position that specifies the support shaft. The movable coil drive unit of this meter body M is connected to a DC power supply B via an ignition switch IG at one input terminal, and is connected to a constant current circuit 5, which will be described later, at another input terminal.
It is grounded via 0.

The buffer circuit 20 sequentially shapes the waveform of each pulse signal from the speed sensor 10 to generate shaped pulses. The monostable multivibrator 30 is activated by receiving the first constant voltage from the constant voltage circuit 40, and generates a high level signal having a predetermined signal width in response to each shaped pulse from the buffer circuit 20 in sequence. The constant current circuit 50 is activated by receiving the second constant voltage from the constant voltage circuit 40, responds to each high level signal from the monostable multivibrator 30, and connects the emitter of the transistor 51 and both resistors 52 and 53. Both transistors 51 and 54 are intermittently turned on to operate the operational amplifier 55 so that the common connection terminal of the transistors 51 and 54 have the same potential. This means that the movable coil drive section of the meter body M generates a driving force while intermittently changing the driving force at a duty ratio based on the intermittent conduction of both transistors 51 and 54. Note that the constant voltage circuit 40
receives the power supply voltage from the DC power supply B through the ignition switch IG and generates the above-mentioned first and second constant voltages.

Next, to explain the configuration of the main part of the present invention, a frequency-voltage converter 60 (hereinafter referred to as F-V converter 60) and an inhibition circuit 70 are provided between the buffer circuit 20 and the constant current circuit 50. The F-V converter 60 converts the frequency of each shaped pulse from the buffer circuit 20 into a proportional analog voltage. The inhibition circuit 70 includes a pair of resistors 7 connected in series with each other to constitute a reference voltage generator.
1, 72, and a comparator 73 connected to the reference voltage generator and the F-V converter 60. The resistor 72, in cooperation with the resistor 71, receives the first constant voltage from the constant voltage circuit 40. The voltage is divided and generated as a reference voltage. In such a case, this reference voltage is
It represents the traveling speed corresponding to a driving force that is somewhat larger than the contact friction force.

A comparator 73 generates a high level signal when the analog voltage from the F-V converter 60 is lower than the reference voltage from the resistor 72, and eliminates the high level signal when the analog voltage is higher than the reference voltage. The transistor 75 has its base connected to the output terminal of the comparator 73 via both bias resistors 74, and the collector of the transistor 75 is connected to the monostable multivibrator 3.
0 (ie, the base of the transistor 54 of the constant current circuit 50). Therefore, this transistor 75 is connected to the comparator 73
In response to a high level signal from the comparator 73, conduction is made to ground the output terminal of the monostable multivibrator 30, and in response to disappearance of the high level signal from the comparator 73, the ground is released. In the figure, reference numeral 76 indicates a resistor, and this resistor 76 functions to provide hysteresis in the timing of generation and disappearance of the high level signal in the comparator 73.

In this embodiment configured as described above, when the vehicle is placed in a running state with the ignition switch IG closed, a series of pulse signals are 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 shaped pulses, and in response to each of these shaped pulses, the monostable multivibrator 30 operates in cooperation with the constant voltage circuit 40. The F-V converter 60 generates an analog voltage while repeatedly generating a high level signal.

In such a state, if the running speed of the vehicle is high and the analog voltage from the F-V converter 60 is higher than the reference voltage from the resistor 72 of the inhibiting circuit 70, the transistor 75 causes the high-level signal from the comparator 73 to disappear. and maintains a non-conducting state.
This means that the prohibition circuit 70 allows each high level signal to be applied from the monostable multivibrator 30 to the constant voltage circuit 50. Thus, the constant current circuit 50 responds to each high level signal from the monostable multivibrator 30 in cooperation with the constant voltage circuit 40, and connects the emitter of the transistor 51 and both resistors 52 and 53. Both transistors 51 and 54 are intermittently turned on to operate the operational amplifier 55 so that the common connection terminal and the common connection terminal have the same potential.

Then, the movable coil drive section of the meter main body M receives power from the DC power supply B via the ignition switch IG, and generates a driving force in response to the intermittently conductive use of both transistors 51 and 54 of the constant current circuit 50. The support shaft of the pointer P receives the applied driving force while changing intermittently, vibrates slightly in response to the intermittent changes, until it reaches a rotational position where this driving force and the repulsive force of the hairsprig are balanced. The running speed of the vehicle (corresponding to the frequency of each of the pulse voltages) is maintained while the pointer P vibrates slightly with the slight vibration of its support shaft while smoothly rotating against the contact friction force between the bearing and the bearing. instruct.

Thereafter, as the traveling speed of the vehicle decreases, the pointer P vibrates slightly and is displaced to reduce its indicated value, and the analog voltage from the F-V converter 60 is applied to the resistor 72 in the prohibition circuit 70. comparator 73 generates a high level signal, in response to which transistor 7
5 conducts to ground the output terminal of the monostable multivibrator 30, that is, the base of the transistor 54 in the constant current circuit 50, and prohibits the application of each high level signal from the monostable multivibrator 30 to the constant current circuit 50. At this time, a current corresponding to the output from the operational amplifier 55 passes through the transistor 75 and flows out from its emitter. This means that both transistors 51 and 54 of the constant current circuit 50 become non-conductive, and the above-described operation of the operational amplifier 55 is stopped. Therefore, the movable coil drive section of the meter body M is maintained in a non-grounded state at the other input terminals and stops generating driving force. As a result, the pointer P stops vibrating slightly together with its support shaft, is displaced by the repulsive force of the hair spring, and is stopped by being stopped by the stopper. In other words,
Since the pointer P stops its fine vibrations in advance and locks with the stopper, the predicted interference between the pointer P and the stopper that occurs when the pointer P locks with the stopper under the fine vibrations is avoided. It is possible to prevent the occurrence of a large needle runout phenomenon, and as a result, the occupant is not given the strange feeling described at the beginning of this specification. In the above-described operation, since the comparator 73 is provided with the resistor 76, the hysteresis phenomenon caused by the hunting effect of the comparator 73 does not occur.

Further, in the above embodiment, an example in which the present invention is applied to a moving coil type speedometer has been described, but instead of this, the present invention may be applied and implemented to various moving coil type analog indicators. In such a case, the present invention can be applied to various types of analog indicators without being limited to the moving coil type. In addition, F
-V converter 60 may be omitted if necessary.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram showing an embodiment of the present invention. Explanation of symbols, 10... Speed sensor, 30... Monostable multivibrator, 50... Constant current circuit,
70...Prohibition circuit, 71,72...Resistor, M...
Instrument body, P... pointer.

Claims (1)

[Claims] 1. A pointer for indicating an analog quantity, a driving section, and a support shaft rotatably coaxially connected to the driving section via a bearing provided on a stationary member and supporting the pointer so as to rotate together with the pointer. , a spiral spring having each end fixed to the intermediate portion of the support shaft and a stationary member, and coaxially fitted to the intermediate portion of the support shaft; and a spiral spring that detects the analog quantity and generates a detection signal. While intermittently changing the driving force necessary to rotate the detection means and the support shaft at a duty ratio according to changes in the detection signal,
a control means for controlling the drive unit so that the drive force is generated by the drive unit, and the drive unit causes the support shaft to vibrate slightly in response to a change in the drive force, while causing the support shaft to vibrate slightly in response to a change in the drive force, and The rotation is made to a balanced rotation position between the driving force and the repulsive force of the spring against the contact friction force between the two, and the detection is performed until the lower limit value corresponds to a driving force that is approximately equal to the contact friction force. The analog indicator includes a stopper that restricts the rotation of the support shaft when the value of the signal decreases, and a reference signal generating means that generates a value near the lower limit value as a reference signal; An analog indicator characterized in that it is further provided with prohibition means for prohibiting the control of the control means when the value of the reference signal is decreased.