JPS6267922A - Switch circuit - Google Patents

Abstract

PURPOSE:To attain the long service life of a switch by preventing a mechanical switch from being applied with a high voltage signal on the way of changeover of the moving contact of the mechanical switch switching the high voltage signal so as to prevent the discharge between the switch contacts. CONSTITUTION:A high voltage sinusoidal wave signal obtained by applying half wave rectification to an output voltage of a power amplifier 14 is applied to the upper side fixed contact of switches 22, 24. In measuring the characteristic of a transistor (TR) 64 in TRs 64, 66 to be measured, switches 22, 30 are changed over. In such a case, the moving contact of the switches 22, 30 is moved at the same time and not in contact with a lower side fixed contact, a voltage of a left center fixed contact of the switch 30, that is, a voltage at a rigger terminal of a multivibrator 36 changes from a + voltage to a common voltage, the multivibrator 36 is triggered, then an electronic switch 10 is changed over in a high speed by a prescribed period to select the common. The output voltage of the power amplifier 14, that is, a voltage of the upper side fixed contact of the switch 22 (and 24) goes to a common voltage or a very low voltage and no high voltage signal is applied during the changeover of the switch 22.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a switch circuit for switching high voltage signals.

[Conventional technology]

For example, in a curve tracer, a switch is used to switch among a plurality of transistors to be measured, and one selected transistor to be measured is measured. In this case, since the collector voltage ranges from low voltage to high voltage by 1, the collector voltage changeover switch must have a high withstand voltage. In a switch that switches high-voltage signals in this way, discharge (arc) occurs when the movable contact switches.

[Problem that the invention seeks to solve]

High-voltage switches or relays suitable for switching high-voltage signals that have a long lifespan against discharge are extremely expensive. There are also inexpensive high-voltage switches available.

Such switches are susceptible to discharge and have a short lifespan.

Therefore, an object of the present invention is to provide a switch circuit that can have a long switching life while using an inexpensive high-voltage switch.

[Means for solving problems]

The switch circuit of the present invention includes an electronic switch that selects an input signal or ground, a power amplifier that receives the output signal of the electronic switch, a first mechanical switch that receives the output signal of the power amplifier, and a first mechanical switch that receives the output signal of the power amplifier. A second mechanical switch interlocks with the first mechanical switch, and a monostable multivibrator that is triggered by the switching operation of the second mechanical switch. An electronic switch selects ground for a predetermined period of time after the multivibrator is triggered.

[For production]

In the switch circuit of the present invention, the output signal of the power amplifier is switched by a mechanical switch, and at the time of this switching, the monostable multivibrator is triggered.

Since the electronic switch selects ground quickly, the output voltage of the power amplifier goes to ground or very low.

That is, while the movable contact of the mechanical switch 9 is in the middle of switching, no high voltage signal is applied to this mechanical switch.

No discharge occurs. Therefore, even if an inexpensive mechanical switch is used, the life span will be sufficiently long. In addition.

The time constant of the multivibrator is set to a time sufficient to complete the switching operation of the movable contact.

Further, since a power amplifier is used, a desired high-voltage signal can be obtained from a low-voltage, low-current input signal, and an electronic switch can be used.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The accompanying figure is a block diagram of a curve tracer that includes a preferred embodiment of the present invention. Electronic switch 10 selects and applies a sine wave signal from sine wave generator 12 or ground to power amplifier 14 . The output signal of this power amplifier 14 is
Transformer 16. It is supplied via a diode 18 and a collector resistor 20 to the upper fixed contacts of one mechanical switch 22 and 24. The central fixed contacts of these switches 22 and 24 connect to collector terminals 26 and 28, respectively.

The movable contact of the mechanical switch 30 is interlocked with the movable contact of the switch 22, and the movable contact of the mechanical switch 32 is interlocked with the movable contact of the switch 24.
It works in conjunction with the movable contact. These switches 22-30 and 24-32 are, for example, interlocking pushbutton switches. The upper and lower fixed contacts on the left side of the switch 30 are connected to the voltage source, and the center fixed contact is connected to the switch 3
Connect to the left center fixed contact of 2.

Further, the right center fixed contacts of switches 30 and 32 are grounded. The upper and lower fixed contacts on the left side of the switch 32 are resistors 34
It is connected directly to the trigger (clock) terminal of the monostable multivibrator 36. The Q output signal of this multi-pipe lake 36 is transmitted to the electronic switch 10.
control. In addition.

The movable contacts of mechanical switches 22 and 30 operate simultaneously 9
Note that the movable contacts of mechanical switches 24 and 32 also operate simultaneously. Further, the time constant of the multivibrator 36 is set such that the output pulse width when triggered is sufficiently longer than the time required for switching operation of one mechanical switch 22, 24, 30, and 32.

Bias circuit 38 provides bias signals to Beine terminals 44 and 46 via relays 40 and 42. These relays 40 and 42 are controlled by solenoids 48 and 50, respectively, and the solenoid 48 is connected to the upper right fixed contact of the switch 30.

The solenoid 50 is connected to the upper right fixed contact of the switch 32. Emitter terminals 52 and 54 are grounded.

The lower end of the secondary winding of the transformer 16 is grounded via a collector current detection resistor 56. Differential amplifier 58 is resistor 56
The horizontal display position of the 1-display device 60 is controlled by detecting the potential difference between both ends of the display. In addition, the voltage divider 62 is connected to the collector terminal 26.
Or divide the collector voltage applied to 28 to display 1 display 60
Controls the vertical display position of A transistor to be measured 64 is connected to the terminals 26, 44 and 52, and a transistor to be measured 66 is connected to the terminals 28, 54 and 46.

Switches 22, 24, 30.32 and relays 40°42
In the illustrated position of the movable contact, the transistor under test 64
and 66 are not selected.

However, a half-wave rectified high voltage sine wave signal is applied to the upper fixed contacts of the switches 22 and 24.

To measure the characteristics of transistor 64, switch 22
and switch 30. At this time, the movable contacts of these switches 22 and 30 begin to move simultaneously.

When it comes out of contact with the lower fixed contact, the voltage at the left center fixed contact of the switch 30, that is, the trigger terminal of the multivibrator 36 changes from 10 voltage to ground.

Because this multivibrator 36 is triggered.

The electronic switch 10 switches at high speed for a predetermined period of time.

Select ground. In addition, the switching operation of the electronic switch is 1
Note that this is much faster than the switching action of a mechanical switch. Only during this predetermined period, the output voltage of the power amplifier 14, that is, the voltage at the upper fixed contact of the switch 22 (and 24) is grounded or at an extremely low voltage. Therefore, switch 2
No high voltage signal is applied during switching of 2, and no discharge occurs.

When the switches 22 and 30 are completely switched, the trigger terminal of the multivibrator 36 is at ten voltage, and then a high voltage signal is applied to the upper fixed contacts of the switches 22 (and 24). Meanwhile, the solenoid 48 operates.

Relay 40 also switches. Therefore, the transistor 64 can be measured. When restoring the connection state of the switches 22 and 30, the multi-pipe lnter 36 is triggered by the operation opposite to that described above, and the switch 22 is closed again for a predetermined period of time.
A high voltage signal is no longer applied to the upper fixed terminal (and 24).

With switches 22 and 30 in the illustrated state.

When measuring transistor 66, the movable contacts of switches 24 and 32 are switched. At this time, the trigger terminal of the multivibrator 36 changes from 10 voltage to ground again, so that it is triggered and the electronic switch 10 selects ground for a predetermined period. Therefore.

In the switching operation of switch 24, discharge is prevented.

When switching of switches 24 and 32 is completed, relay 4
2 is switched, and a bias signal from the bias circuit 38 is applied to the terminal 46. Note that the switches 30 and 32 are electrically connected.

The multivibrator 36 can be shared.

Although the above describes one preferred implementation of the invention, various modifications are possible. For example, although two sets of mechanical switches are used in the embodiment, it may be one set or three or more sets. Also, when one set of mechanical switches is switched, the other set of switches may be mechanically coupled so that the movable contacts return to their original positions. Furthermore, if the output of the power amplifier is large enough,
The transformer may be removed. In addition, Curve Tracer JA
The present invention can also be used for other purposes.

[Effects of the Invention] As described above, according to the present invention, the high voltage signal is stopped when one mechanical switch is switched, so there is no discharge between the contacts of the switch, and the life of the switch is extended. I cut it. Even if a plurality of sets of mechanical switches are provided, if the fixed contacts of each set of switches are connected as shown in the figure, only a single electronic switch control circuit (multivibrator) is required, which simplifies the configuration.

[Brief explanation of drawings]

The accompanying figure is a block diagram of a curve tracer that includes a preferred embodiment of the present invention. In the figure, 10 is an electronic switch, 14 is a power amplifier,
22.24.30 and 32 are mechanical switches. 36 is a monostable multivibrator.

Claims (1)

[Claims] an electronic switch that selects an input signal or ground; a power amplifier that receives an output signal of the electronic switch; a first mechanical switch that receives an output signal of the power amplifier; and a first mechanical switch that operates in conjunction with the first mechanical switch. 2 mechanical switches and a monostable multivibrator triggered by the switching operation of the second mechanical switch, the electronic switch is controlled by the output signal of the monostable multivibrator, and the monostable multivibrator is triggered. A switch circuit characterized in that the electronic switch selects grounding for a subsequent predetermined period of time.