JPH09281169A - Measuring device - Google Patents

Abstract

(57) Abstract: In a measuring device for measuring the electrical characteristics of a device under test such as a semiconductor device, the matrix for reliably preventing the risk of destruction of the device under test and configuring a meter circuit The effort to measure the response time of each switching element of the relay circuit is greatly reduced. A switching element K ₉ that generates a time measurement start signal in response to a relay drive signal from a relay drive circuit and is driven by this relay drive signal.
˜K ₂₄ , a measurement auxiliary circuit 9 for generating a stop signal for time measurement, and a time from the start signal input to the stop signal input from the measurement auxiliary circuit 9 is measured to measure each switching element K. _{9 to} K ₂₄ and a time measuring circuit 10 for determining the response time Δt ₁ .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for measuring electrical characteristics of semiconductor elements and the like, and more particularly, by adding a self-diagnosis function, high accuracy is maintained and adjustment and maintenance reliability is improved. It is related to the technology to improve.

[0002]

2. Description of the Related Art For various electric elements, when measuring, evaluating, and judging the electric characteristics, various measurement items required for examining the electric characteristics are preset,
It is necessary to rearrange the connections of the power supply, the voltmeter, the ammeter and the like in accordance with a predetermined sequence so that the required measurement result corresponding to each of these measurement items can be obtained.

Therefore, conventionally, a measuring device having a configuration as shown in FIGS. 5 and 6 has been provided.

That is, this measuring apparatus has various electric elements to be measured (hereinafter referred to as "elements under test") 5
A system control unit (CPU) 1 that performs control for configuring a measurement circuit that is suitable for measuring the electrical characteristics of, and a relay drive circuit 3 that outputs a relay drive signal in response to a command from the system control unit 1. A matrix relay circuit 4 whose connection is switched by a relay drive signal from the relay drive circuit 3 and an instrument unit 2 for measuring the electrical characteristics of the device under test 5 by switching the connection of the matrix relay circuit 4 are provided. The instrument unit 2 includes a constant current source 6, a constant voltage source (not shown), a voltmeter 7, an ammeter (not shown),
Further, the matrix relay circuit 4 is configured by arranging switching elements K (only K _{1 to} K ₈ are shown in FIG. 6) in a matrix.

Next, a sequence for measuring the characteristics of one element under test (diode in the example shown in FIG. 6) 5 by using the measuring apparatus of this configuration will be described.

First, as shown in FIG. 6A, the device under test 5 is connected to the matrix circuit 4.

Subsequently, the system control circuit 1 gives the measuring section 2 a measuring condition according to the measurement item of the device under test 5, so that the constant current source 6 and the voltmeter 7 constituting the measuring section 2 have a predetermined range. Is set to.

Next, the system control circuit 1 gives the relay drive circuit 3 conditions for constructing a measurement circuit according to the measurement item of the device under test 5. Then, in response thereto, the relay drive circuit 3 outputs the relay drive signals S _{1 to} S ₄ to the matrix relay circuit ₄ at the same timing, as shown in the timing chart of FIG. 7. Matrix relay circuit 4 by the relay driving signal S ₁ to S ₄
The contacts of the switching elements indicated by the symbols K ₁ , K ₄ , K ₄ , and K ₈ are switched to the ON state after Δt ₁ , and the measurement circuit as shown in FIG. Is ready for measurement.

Then, subsequently, the relay drive circuit 3 outputs the constant current source output signal S _{5 at} a time delayed by Δt ₂ from the output timing of each of the relay drive signals S _{1 to} S ₄ , and further Δt ₃ The voltmeter measurement signal S ₆ is output at a time delayed by a certain amount, and the voltage value of the device under test 5 is measured.

[0010]

As described above, in the case where the measurement circuit is constructed according to the conditions suitable for various measurement items for the device under test 5, in order to reduce the measurement error, the voltage of the path through which the current flows is reduced. It is necessary to minimize the amount of descent.

Therefore, as each switching element K constituting the matrix relay circuit 4, a reed relay having a minimum contact resistance value is usually used.

However, since each reed relay K is composed of a magnet coil and a mechanical contact, the time required for the contact to turn on or off in response to the relay drive signals S _{1 to} S ₄ (hereinafter , This is called the response time) Δt ₁
Takes longer than other switching elements. Moreover, the response time Δt ₁ of the contact opening / closing of each individual reed relay K is as shown in FIG.
However, in practice, there is a variation of about 0.5 ms to 1.00 ms for each reed relay K.

Further, each reed relay K is turned on / off.
The response characteristic deteriorates as the number of operations to be turned off increases, and the response time Δt ₁ gradually increases.

As described above, the response time Δt ₁ of each reed relay K varies, and the response time Δt ₁ becomes longer as the number of times of use of the reed relay K increases. If Δt ₁ is significantly increased from the initial state, the device under test 5 is adversely affected.

For example, of the reed relays K ₁ , K ₄ , K ₅ , K ₈ to be operated in response to the relay drive signals S ₁ -S ₄ ,
When the response time Δt _{1 of a} certain reed relay, for example, K ₁ becomes long and becomes later than the timing at which the constant current source output signal S ₅ is output (when Δt ₂ <Δt ₁ ), FIG. As shown in, the constant current source output signal S ₅ is output before the reed relay K ₁ is turned on.

That is, at the time when the constant current source output signal S ₅ is output, the reed relays of K ₄ , K ₅ , and K ₈ in FIG. 6A are turned on, but the reed relay of K ₁ is turned on. Remains off, the constant current source 6 is in a no-load state and the voltage rises to the maximum power supply capacity.

From this state, when the contact of the reed relay K ₁ is next closed and turned on, the terminals of the device under test 5 are
There is a risk that the device under test 5 will be destroyed because an overvoltage that is higher than the rating is temporarily applied.

In order to avoid such an inconvenience, it is necessary to check the response time Δt ₁ of each reed relay K incorporated in the matrix relay circuit 4 each time before the measurement of the device under test 5 is started. is there. Therefore, conventionally,
After removing the individual reed relays K, the response time Δt ₁ was observed by an oscilloscope and evaluated using a dedicated measuring circuit as shown in FIG.

That is, as shown in FIG. 10, the drive signal Sa is input to the input terminal in on the coil side of one reed relay K, and in response to this, the output terminal connected to the contact side of the reed relay K. The contact signal Sb output from out is observed with an oscilloscope, and the response time Δt ₁ is checked from both signals Sa and Sb.

However, such a method of evaluation requires the work of removing and installing the individual reed relays K, which is extremely troublesome, time-consuming, and complicated.

The present invention has been made in order to solve the above problems, and adds a function of self-diagnosing the delay of the response time of each switching element constituting the matrix relay circuit to destroy the element under test. It is an object of the present invention to surely prevent the risk of, and to greatly reduce the time and effort for measuring the response time of each switching element.

[0022]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a system control circuit for performing control for constructing a measurement circuit suitable for measuring the electrical characteristics of a device under test, and this system. A relay drive circuit that outputs a relay drive signal in response to a command from the control circuit; and a matrix relay circuit whose connection is switched by the relay drive signal from the relay drive circuit, wherein the matrix relay circuit has a plurality of switching elements. Is arranged in a matrix, and the following configuration is adopted in a measuring device that measures the electrical characteristics of the device under test by a measuring circuit configured by switching the connection of each of these switching devices.

That is, the measuring device of the present invention generates a time measurement start signal in response to the relay drive signal from the relay drive circuit, and outputs the time in response to the switching operation of the switching element driven by this relay drive signal. A measurement auxiliary circuit that generates a measurement stop signal and a time measurement circuit that measures the time from the start signal input to the stop signal input from the measurement auxiliary circuit to determine the response time of each switching element are included.

With this configuration, it is possible to measure the response time of each switching element that constitutes the matrix relay circuit inside the measuring device, prevent the risk of destruction of the element under test, and yet to prevent the risk of destruction of the individual switching elements. The time and effort required to measure the response time can be greatly saved.

[0025]

1 is a block diagram showing the overall structure of a measuring device according to the present invention, and FIG. 2 is a structural diagram showing details of essential parts of the measuring device.

The measuring device of this embodiment comprises a system control unit (CPU) 1, an instrument unit 2, a relay drive circuit 3, and a matrix relay circuit 4, and the instrument unit 2 has a constant current source and a constant voltage source. , Voltmeter, ammeter (none shown)
In addition, the matrix relay circuit 4 includes a reed relay K (K _9-in FIG. 2) as a switching element.
K ₂₄ ) is arranged in a matrix, which is similar to the case of the conventional example shown in FIGS. 5 and 6,
Detailed description is omitted.

The feature of this embodiment is that a measurement auxiliary circuit 9 and a time measuring circuit 10 are further added to the above configuration, and the response time Δt ₁ of each reed relay K constituting the matrix relay circuit 4 is self-diagnosed. That is what I am trying to do.

That is, the measurement auxiliary circuit 9 of the present example generates the time measurement start signal A according to the relay drive signal from the relay drive circuit, and the switching operation of the reed relay K driven by this relay drive signal. In the present example, a matrix line selection circuit 12 for selecting each row of the matrix relay circuit 4 and an OR gate 13 for inputting a relay drive signal from the relay drive circuit 3 are generated. Two comparators 14 and 15 and resistors R _L and R _{1 to} R ₄ are provided.

The time measuring circuit 10 measures the time from the input of the start signal A to the input of the stop signal B from the measurement auxiliary circuit 9 to determine the response time of each reed relay K. In this example, the time measuring counter 11 is used.

Next, with reference to the timing chart shown in FIG. 3, the sequence for confirming the response time Δt ₁ of one reed relay (here, K ₉ ) that constitutes the matrix relay circuit 4 in this measuring apparatus will be described. explain.

When the confirmation mode for evaluating the response time Δt ₁ of the reed relay K ₉ is selected, the system control unit 1 uses the constant voltage source V _SI of the meter unit 2 to set a predetermined constant voltage. (5V in this example) is output, and the matrix line selection circuit 12 is controlled to select the line L ₁ of the first row including the reed relay K ₉ to be evaluated.
As a result, the constant voltage (5 V) from the constant voltage source V _{SI is applied} to the resistor R
_It is applied to the contacts of the reed relays K _{9 to} K _{12 on} the first line of the matrix relay circuit 4 via _L and the matrix line selection circuit 12.

In this state, subsequently, the system controller 1 controls the relay drive circuit 3 to output a relay drive signal to the reed relay K _{21 in} the bottom row of the first column,
The contact of the reed relay K ₂₁ is closed and the matrix line selection circuit 12 is controlled to select the line L ₄ of the fourth row including the reed relay K ₂₁ .

As a result, the circuit shown in FIG. 4 is constructed. In this case, the reed relay K ₂₁ is turned on and the constant current source V
_Although it is connected to the negative side of _SI , the reed relay K ₉ is still off and the constant voltage (5 V) from the constant voltage source V _SI is still applied.

Next, the system control unit 1 resets the count content of the time measuring counter 11 which constitutes the time measuring circuit 10 and puts it in a state of waiting for a start signal.

Subsequently, the system control unit 1 controls the relay drive circuit 3 from this state of waiting for measurement and outputs a relay drive signal to the reed relay K ₉ to be evaluated.

The relay drive signal drives the reed relay K ₉ to be evaluated, and this relay drive signal is supplied to one comparator 15 of the measurement auxiliary circuit 9.
Input to the positive phase terminal (+) of.

A reference voltage determined by the voltage dividing resistors R ₃ and R ₄ is applied to the negative phase terminal (-) of the comparator 15, and when the relay drive signal is larger than this reference voltage, The output of the comparator 15 is inverted from the high level to the low level, and this level-inverted signal is input to the time measurement counter 14 constituting the time measurement circuit 10 as the time measurement start signal A. As a result, the time measuring counter 11 starts counting operation.

As described above, the contact of the reed relay K ₉ is closed after the elapse of a certain response time Δt ₁ by the relay drive signal, and the turning on of this contact causes the line L of the first row of the matrix relay circuit 4 to be closed. _{Since 1} is in the grounded state, the voltage at one end of the resistor R _L drops, and this voltage dropped signal is input to the negative phase terminal (−) of the other comparator 14 of the measurement auxiliary circuit 9 as a contact signal. It

A reference voltage determined by the voltage dividing resistors R ₁ and R ₂ is applied to the positive phase terminal (+) of the comparator 14, and when the contact signal becomes smaller than this reference voltage. The output of the comparator 14 is inverted from a low level to a high level, and this level-inverted signal is input to the time measuring counter 14 constituting the time measuring circuit 10 as a time measurement stop signal B. As a result, the time measuring counter 11 stops the counting operation.

Therefore, the time measured from the time measurement counter 11 starting the count operation by the start signal A input from one comparator 15 to the stop operation by the stop signal B input from the other comparator 14 is measured. , Which corresponds to the time required for turning on or off the contact of the reed relay in response to the relay drive signal, that is, the response time Δt ₁ . Then, the response time Δt ₁ is recognized by the system control unit 1 and displayed on a display device (not shown) of the instrument unit 2.

In the above embodiment, the case where only the response time Δt _{1 of} one reed relay K ₉ is evaluated is described, but this sequence is applied to each reed relay K 9.
If it is repeated every _{9 to} K ₂₄ , it is possible to continuously diagnose the response time Δt ₁ of all the reed relays K _{9 to} K ₂₄ .

[0042]

According to the present invention, the following effects can be obtained.

(1) In the invention having the structure described in claim 1, since the delay of the response time of each switching element forming the matrix circuit can be self-diagnosed, the risk of destruction of the device under test is surely prevented. In addition, the time and effort required to measure the response time of the switching element can be greatly reduced as compared with the conventional case.

(2) In the invention described in claim 2,
In addition to the effects described, since the reed relay is used as the switching element of the matrix relay circuit, the voltage drop on the path through which the current flows can be minimized and the measurement error can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a measuring device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of a main part of the measuring apparatus of FIG.

FIG. 3 is a timing chart for explaining the operation of measuring the response time of the reed relay in the measuring device of FIG.

4 is a circuit diagram configured to measure a response time of a reed relay of a matrix relay circuit of the measuring device of FIG.

FIG. 5 is a block diagram showing an overall configuration of a conventional measuring device.

6 is a circuit diagram which is configured when the electrical characteristics of a device under test are examined using the measuring device of FIG.

7 is a timing chart for explaining the operation when examining the electrical characteristics of the device under test in the measuring apparatus of FIG.

FIG. 8 is a timing chart provided for explaining the inconvenience when the response time of the reed relay becomes long in the measuring device of FIG.

FIG. 9 is a configuration diagram of a dedicated measuring circuit for measuring the response time of the reed relay.

10 is a timing chart for explaining a response time measurement operation of a reed relay using the measurement circuit of FIG.

[Explanation of symbols]

1 ... System control part, 2 ... Instrument part, 3 ... Relay drive circuit, 4 ... Matrix relay circuit, 5 ... Device under test, 9
... measuring auxiliary circuit, 10 ... time measuring circuit, K ₉ ~K ₂₄ ... switching device (reed relays).

Claims (2)

[Claims] 1. A system control circuit for performing control for constituting a measurement circuit suitable for measuring the electrical characteristics of a device under test, and a relay drive for outputting a relay drive signal in response to a command from the system control circuit. A circuit and a matrix relay circuit whose connection is switched by a relay drive signal from the relay drive circuit, wherein the matrix relay circuit is formed by arranging a plurality of switching elements in a matrix, and switching the connection of each of these switching elements. In a measuring device for measuring the electrical characteristics of the device under test by a configured measuring circuit, a start signal for time measurement is generated in response to a relay driving signal from the relay driving circuit, and driven by this relay driving signal. Generates a stop signal for time measurement according to the switching operation of the switching element And a time measuring circuit for measuring the time from the start signal input to the stop signal input from the measurement auxiliary circuit to determine the response time of each switching element. . 2. The measuring device according to claim 1, wherein the switching element is a reed relay.