JPH0615294Y2 - Signal generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a signal generator for outputting a predetermined signal,
More specifically, the present invention relates to a signal generator for preventing the release between the output terminal and the sense terminal of the signal source.

[Prior Art] A constant-voltage device or a constant-current device that supplies a predetermined voltage or current to a load, or a constant-voltage current generator used for calibration or scale determination in a DC or AC digital instrument or analog instrument, etc. Etc., there is provided a detection terminal for feeding back the state of the signal applied to the load to the signal source, that is, a sense terminal together with output terminals from these signal sources. This sense terminal is shorted at the output end,
Alternatively, unless it is used in the four-terminal method, feedback information cannot be obtained, and an abnormally high voltage is generated because the signal source is controlled based on the feedback information.

Therefore, in the conventional sense terminal of this type, a resistor is connected between the output terminal and the output terminal to prevent an open state between the output terminal and the sense terminal. For this resistor, a resistor having a high resistance value is used so that an output error due to the resistor can be ignored when the output terminal and the sense terminal are connected via a load or the like.

In addition, instead of this resistor, we also proposed a model in which a diode is connected, and when the output terminal and the sense terminal are not connected, this diode operates to prevent the terminals from opening. Has been done. In the case of this diode type, if the voltage between the terminals of the diode when the output terminal and the sense terminal are connected via a load, etc., is below the operating voltage of this diode, the diode will not operate and the diode There is no output error due to.

[Problems to be solved by the device]

However, in this resistance type, if the load is mistakenly connected to the sense terminal when the output terminal and the sense terminal are not connected via a load, the resistance directly receives the voltage from the signal source. Therefore, from the standpoint of its protection, it is necessary to have a high resistance resistor having a power resistance. As is well known, the higher the power value is, the larger the resistor becomes, and the signal source occupies a large installation area.

In the case of the diode type, if the output terminal and the sense terminal are not connected via a load, etc., and if the load is accidentally connected to the sense terminal, the diode will be damaged and If the distance between the output terminal of the signal source, the sense terminal and the load is long as well as the open state, the potential difference between the output terminal and the sense terminal will cause the diode to operate due to the resistance of the connecting line connecting them. This is larger than the voltage, which causes a large error in the output voltage.

Therefore, an object of the present invention is to improve the above-mentioned drawbacks of the conventional sense terminal structure, and to provide a signal generator capable of reliably preventing an open state between the output terminal and the sense terminal with a simple configuration. Is.

[Means for Solving the Problems]

The present invention is directed to a signal generator including a DC signal source, an output terminal for applying a signal from the DC signal source to a load, and a sense terminal for feeding back the state of the signal applied to the load to the DC signal source. In the device, a constant current means for preventing an open state from occurring between the output terminal and the sense terminal is connected in advance.

〔Example〕

An embodiment of the present invention shown in the drawings will be described below. This embodiment takes as an example the case where it is applied to a known DC voltage generator. A DC signal source 2 that generates a desired DC voltage is housed in the housing 1, and the + and-side output lead wires 3 and 4 are provided so as to be exposed on one side surface of the housing 1. It is connected to the + side output terminal 5 and the − side output terminal 6. A + -side sense terminal 7 and a −-side sense terminal 8 are provided on the side surface of the housing 1 near each of these output terminals 5 and 6, and these sense terminals 7 and 8 are
Connecting conductor 9 to a monitoring circuit (not shown) in the DC signal source 2
And connected by 10. A constant current circuit 11 and a resistor 12 connected in series are connected between the output conductor 3 and the connection conductor 9. A constant current circuit 13 and a resistor 14 are similarly connected between the output conductor 4 and the connecting conductor 10. A load 15 is connected between the output terminals 5 and 6, and the generated voltage is applied to one end of the load 15 to which the output terminal 5 is connected.
The positive side sense terminal 7 is also connected so as to detect at the end, and the reference potential (ground potential) of the DC signal source 2 is detected at this load 15 end at the other end side of the load 15 to which the output terminal 6 is connected. The negative-side sense terminal 8 is also connected as described above. This 2
The voltage applied to the load 15 by one sense line and the detection voltage of the error amplifier circuit (not shown) connected to the sense line in the DC signal source 2 match.

Each of the constant current circuits 11 and 13 may be composed of only a constant current diode or a conventional constant current circuit using a transistor, a field effect transistor or an operational amplifier. A diode or a Zener diode may be used instead of the resistors 12 and 14. The resistance values of the constant current circuits 11 and 13 and the resistors 12 and 14 are set to be much larger than the resistance values of the connecting conductors from the output terminals 3 and 4 to the load 15 to the sense terminals 7 and 8. The constant current circuit 11,13
Is configured so that only a small amount of current flows as compared with the current value from the DC signal source 2.

Therefore, when the load 15 is correctly connected to the output terminals 3 and 4 and the sense terminals 7 and 8, that is, when these terminals 3, 4 and 7 and 8 are short-circuited externally, a constant current circuit is provided. No current flows through 11,13 and resistors 12,14. Further, the resistance values of the constant current circuits 11 and 13 and the resistors 12 and 14 are set to be much larger than the resistance values of the connecting conductors from the output terminals 3 and 4 through the load 15 to the sense terminals 7 and 8. Therefore, the error due to the constant current circuits 11 and 13 and the resistors 12 and 14 can be ignored.

When the load 15 is not connected to the output terminals 3 and 4 and the sense terminals 7 and 8, that is, these terminals 3, 4 and 7,
When 8 is not shorted externally, constant current circuit 11,1
Current flows from 3 to the resistors 12 and 14, the output terminals 3 and 4 and the sense terminals 7 and 8 are short-circuited, and the sense terminals 7 and 8
Can be prevented from being opened. If a load 15 is erroneously connected between the sense terminals 7 and 8 in this state, current flows from the output terminals 3 and 4 to the sense terminals 7 and 8 through the constant current circuits 11 and 13 and the resistors 12 and 14, respectively. However, since a small amount of current flows through the constant current circuits 11 and 13, the heat loss is also small, so that the resistors 12 and 14 need only have low power resistance and can be miniaturized.

[Effect of device]

As described above, the signal generator of the present invention has an extremely simple structure in which the constant current means is connected between the sense terminal and the output terminal, but when the signal is normally connected to the load, etc. It does not affect the output of the generator. Further, even if the sense terminal and the output terminal are not externally connected or the load is mistakenly connected to the sense terminal in this state, it is possible to reliably prevent the sense terminal from being in the open state.

[Brief description of drawings]

The drawing is a block diagram showing an embodiment of the present invention. In the drawings, 1 is a housing, 2 is a DC signal source, 3 and 4 are output leads, 5 and 6 are output terminals, 7 and 8 are sense terminals, 9 and
10 is a connecting wire, 11 and 13 are constant current circuits, 12 and 14 are resistors, 15
Is the load.

Claims (1)

[Scope of utility model registration request] 1. A DC signal source, an output terminal for applying a signal from the DC signal source to a load, and a sense terminal for feeding back the state of the signal applied to the load to the DC signal source. In the signal generator provided, a constant current means for preventing an open state from occurring between the output terminal and the sense terminal is connected in advance to the signal generator.