JPS5939650Y2 - Deviation indicator - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a deviation indicating device using a deviation meter whose needle swings in both positive and negative directions around a center zero point.

This deviation indicating device compares the output to be detected with a reference voltage and displays the difference (deviation) therebetween using a meter.

This standard is usually obtained using a constant voltage element such as a Zener diode, but since there are variations in the characteristics of the constant voltage element, the DC voltage level of the detected output is adjusted to compensate for this variation. ing.

However, depending on the application, it may not be possible to adjust the DC voltage level of the detected output due to output impedance or the like.

This invention is particularly suitable for application in cases where it is not possible to adjust the DC level of the detected output as described above, and compensates for variations in the characteristics of the constant voltage element to obtain the desired reference voltage.
Moreover, it is an object of the present invention to provide a deviation indicating device in which the reference voltage is less affected by the magnitude of the current flowing through the meter and the display accuracy is less degraded.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In the figure, the detected output VIN given as the output of the amplifier 11 is sent to the deviation meter 14 via a resistor 12 and a variable resistor 13.

On the other hand, the reference voltage circuit has a series circuit of a resistor 15, a variable resistor 16, and a silicon diode 17.

A power supply voltage VCC is applied to one end of this series circuit, and a constant voltage Vz is applied to the other end.

The Zener diode 18 and the resistor 19 constitute a circuit for obtaining this constant voltage Vz.

In this circuit, the variable range of the reference voltage VS is VZ+
VD<VS<VZ+VD+VRV where VD: forward voltage drop of diode 17 VRV: voltage drop across variable resistor 16.

Furthermore, VRV extension RA: resistance value of resistor 15 RV: resistance value between both ends of variable resistor 16 It is.

Here, it is preferable to select RV<<RA and make VRV small.

Then, VS is mainly determined by Vz+VD.

Preferably, VRV is set to a value smaller than the forward voltage drop of one silicon diode, and the main adjustment of Vs (compensation for variations in Zener voltage Vz) is performed by adjusting the number of diodes to be connected. The variable resistor 16 performs voltage adjustment so fine that it cannot be compensated for.

In this way, the variation in the Zener voltage is compensated for by using the forward voltage drop of the silicon diode, and further fine compensation is performed by the voltage drop caused by the resistor to set the desired reference voltage vs.

Therefore, even if the current IM flowing through the meter 14 increases or decreases, VR
Since only V changes, there is little variation in the reference voltage vs, and there is little possibility that display accuracy will deteriorate.

Therefore, this is advantageous when the DC voltage level of the output to be detected cannot be changed.

In other words, if it is possible to change the DC voltage level of the output to be detected, it is easy to install a voltage divider circuit at the output to be detected.
If this is not possible, the only option is to change the reference voltage.

Conventionally, changing the reference voltage relied only on the voltage drop that occurred in the resistor, so if the current flowing through the meter 14 changed, the voltage drop changed and the reference voltage fluctuated, resulting in poor accuracy, but this has been improved. be.

As explained above, according to the present invention, it is possible to set a predetermined reference voltage by compensating for variations in the characteristics of the constant voltage element, and the reference voltage is not affected by fluctuations in the current flowing through the meter. few.

Therefore, even in applications where the DC voltage level of the output to be detected cannot be changed, extremely accurate deviation instructions can be provided.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the present invention. 11... Amplifier, 14... Deviation meter, VIN...
・Detected output, Vs...Reference voltage, VZ...Zener voltage, VD...Forward drop voltage of diode 17, V
RV...Voltage drop across the variable resistor 16, VCC...
・Power supply voltage, IM...meter current.

Claims (1)

[Scope of utility model registration request] A deviation indicator meter is connected between the output terminal to be detected and a reference voltage circuit, and the reference voltage circuit causes a current to flow from the power supply terminal to which the power supply voltage is applied to the Zener diode through the first resistor, and A second resistor, fixed terminals at both ends of a variable resistor, and one or several O diodes are connected in series between a power supply terminal and a connection point between the first resistor and the Zener diode, The voltage drop generated between the fixed terminals at both ends is made smaller than the forward voltage drop of one diode, and the reference voltage is generated from the variable terminal, and the reference voltage is adjusted by adjusting the number of connected diodes. The deviation indicating device is configured to change the reference voltage smaller than the forward voltage drop of one diode by adjusting the variable terminal of the variable resistor.